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20110801_Revised FRN_EO12866_GHG+Fuel Eff Stds for Med-Heavy-Duty Engines+Vehicles 2060-

AP61 FRM.docx

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 85, 86, 600, 1033, 1036, 1037, 1039, 1065, 1066, and 1068

DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration 

49 CFR Parts 523, 534, and 535

[EPA–HQ–OAR–2010–0162; NHTSA-2010-0079; FRL-xxxx-x]

RIN 2060-AP61; RIN 2127-AK74

Greenhouse Gas Emissions Standards and Fuel Efficiency Standards for Medium- and 

Heavy-Duty Engines and Vehicles

AGENCIES: Environmental Protection Agency (EPA) and National Highway Traffic 

Safety Administration (NHTSA)

ACTION: Final Rules

__________________________________________________________________

SUMMARY:

EPA and NHTSA, on behalf of the Department of Transportation, are each finalizing 

rules to establish a comprehensive Heavy-Duty National Program that will reduce 

greenhouse gas emissions and fuel consumption for on-road heavy-duty vehicles, 

responding to the President’s directive on May 21, 2010, to take coordinated steps to 

produce a new generation of clean vehicles. NHTSA’s final fuel consumption standards 

and EPA’s final carbon dioxide (CO2) emissions standards are tailored to each of three 

regulatory categories of heavy-duty vehicles: (1) Combination Tractors; (2) Heavy-duty

Pickup Trucks and Vans; and (3) Vocational Vehicles. The rules include separate 

standards for the engines that power combination tractors and vocational vehicles. 

Certain rules are exclusive to the EPA program. These include EPA’s final

hydrofluorocarbon standards to control leakage from air conditioning systems in 

combination tractors, and pickup trucks and vans. These also include EPA’s final nitrous 

oxide (N2O) and methane (CH4) emissions standards that will apply to all heavy-duty 

engines, pickup trucks and vans. 

EPA’s final greenhouse gas emission standards under the Clean Air Act will begin with 

model year 2014. NHTSA’s final fuel consumption standards under the Energy

Independence and Security Act of 2007 will be voluntary in model years 2014 and 2015, 

becoming mandatory with model year 2016 for most regulatory categories. Commercial 

trailers are not regulated in this phase of the Heavy-Duty National Program.
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The agencies estimate that the combined standards will reduce CO2 emissions by

approximately 270 million metric tons and save 530 million barrels of oil over the life of 

vehicles sold during the 2014 through 2018 model years, providing over $7 billion in net 

societal benefits, and $49 billion in net societal benefits when private fuel savings are 

considered.

EPA is also finalizing provisions allowing light-duty vehicle manufacturers to use CO2

credits to meet the light-duty vehicle N2O and CH4 standards, technical amendments to 

the fuel economy provisions for light-duty vehicles in 40 CFR part 600, and a technical 

amendment to the criteria pollutant emissions requirements for certain switch 

locomotives in 40 CFR part 1039.

DATES: These final rules are effective on [Insert date 60 days after publication in the 

Federal Register], sixty days after date of publication in the Federal Register. The 

incorporation by reference of certain publications listed in this regulation is approved by 

the Director of the Federal Register as of [Insert date 60 days after publication in the 

Federal Register].

ADDRESSES: EPA and NHTSA have established dockets for this action under Docket 

ID No. EPA–HQ–OAR–2010–0162 and NHTSA-2010-0079, respectively. All 

documents in the docket are listed on the www.regulations.gov web site. Although listed 

in the index, some information is not publicly available, e.g., confidential business 

information or other information whose disclosure is restricted by statute. Certain other 

material, such as copyrighted material, is not placed on the Internet and will be publicly

available only in hard copy form. Publicly available docket materials are available either 

electronically through www.regulations.gov or in hard copy at the following locations: 

EPA: EPA Docket Center, EPA/DC, EPA West Building, 1301 Constitution Ave., N.W., 

Room 3334, Washington DC. The Public Reading Room is open from 8:30 a.m. to 4:30

p.m., Monday through Friday, excluding legal holidays. The telephone number for the 

Public Reading Room is (202) 566–1744, and the telephone number for the Air Docket is 

(202) 566-1742. NHTSA: Docket Management Facility, M-30, U.S. Department of 

Transportation, West Building, Ground Floor, Rm. W12-140, 1200 New Jersey Avenue, 

SE, Washington, DC 20590. The Docket Management Facility is open between 9 a.m. 

and 5 p.m. Eastern Time, Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT: NHTSA: Lily Smith, Office of 

Chief Counsel, National Highway Traffic Safety Administration, 1200 New Jersey

Avenue, SE, Washington, DC 20590. Telephone: (202) 366-2992. EPA: Lauren Steele, 

Office of Transportation and Air Quality, Assessment and Standards Division (ASD), 

Environmental Protection Agency, 2000 Traverwood Drive, Ann Arbor, MI 48105; 

telephone number: (734) 214-4788; fax number: (734) 214-4816; email address:

steele.lauren@epa.gov, or contact the Assessment and Standards Division, email 

OTAQPUBLICWEB@epa.gov. 

SUPPLEMENTARY INFORMATION: 
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A. Does this Action Apply to Me

This action affects companies that manufacture, sell, or import into the United States new 

heavy-duty engines and new Class 2b through 8 trucks, including combination tractors, 

school and transit buses, vocational vehicles such as utility service trucks, as well as 3⁄4-

ton and 1-ton pickup trucks and vans. The heavy-duty category incorporates all motor 

vehicles with a gross vehicle weight rating of 8,500 pounds or greater, and the engines 

that power them, except for medium-duty passenger vehicles already covered by the 

greenhouse gas emissions standards and corporate average fuel economy standards issued 

for light-duty model year 2012-2016 vehicles. Regulated categories and entities include 

the following: 

Category NAICS CodeaExamples of Potentially Affected Entities

Industry 336111 Motor Vehicle Manufacturers, Engine and 

336112 Truck Manufacturers

336120

Industry 541514 Commercial Importers of Vehicles and 

811112 Vehicle Components

811198

Industry 336111 Alternative Fuel Vehicle Converters

336112

422720

454312

541514

541690

811198

Industry 333618 Manufacturers, remanufacturers and importers of 

336510 locomotives and locomotive engines

Note:

a

 North American Industry Classification System (NAICS)

This table is not intended to be exhaustive, but rather provides a guide for readers 

regarding entities likely covered by these rules. This table lists the types of entities that 

the agencies are aware may be regulated by this action. Other types of entities not listed 

in the table could also be regulated. To determine whether your activities are regulated 

by this action, you should carefully examine the applicability criteria in the referenced

regulations. You may direct questions regarding the applicability of this action to the 

persons listed in the preceding FOR FURTHER INFORMATION CONTACT section.

Table of Contents

I. Overview

A. Introduction
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B. Building Blocks of the Heavy-duty National Program

C. Summary of the Final EPA and NHTSA HD National Program

D. Summary of Costs and Benefits of the HD National Program

E. Program Flexibilities

F. EPA and NHTSA Statutory Authorities

G. Future HD GHG and Fuel Consumption Rulemakings

II. Final GHG and Fuel Consumption Standards for Heavy-duty Engines and Vehicles

A. What Vehicles Will Be Affected?

B. Class 7 and 8 Combination Tractors

C. Heavy-Duty Pickup Trucks and Vans

D. Class 2b-8 Vocational Vehicles

E. Other Standards

III. Feasibility Assessments and Conclusions

A. Class 7-8 Combination Tractor

B. Heavy-Duty Pickup Trucks and Vans

C. Class 2b-8 Vocational Vehicles

IV. Final Regulatory Flexibility Provisions

A. Averaging, Banking, and Trading Program

B. Additional Flexibility Provisions

V. NHTSA and EPA Compliance, Certification, and Enforcement Provisions

A. Overview

B. Heavy-duty Pickup Trucks and Vans

C. Heavy-Duty Engines

D. Class 7 and 8 Combination Tractors

E. Class 2b-8 Vocational Vehicles

F. General Regulatory Provisions

G. Penalties

VI. How Will This Program Impact Fuel Consumption, GHG Emissions, and Climate 

Change?

A. What Methodologies Did the Agencies Use to Project GHG Emissions and Fuel 

Consumption Impacts?

B. MOVES Analysis

C. What Are the Projected Reductions in Fuel Consumption and GHG Emissions?

D. Overview of Climate Change Impacts from GHG Emissions

E. Changes in Atmospheric CO2 Concentrations, Global Mean Temperature, Sea Level 

Rise, and Ocean pH Associated with the Program’s GHG Emissions Reductions

VII. How Will This Final Action Impact Non-GHG Emissions and Their Associated 

Effects?

A. Emissions Inventory Impacts

B. Health Effects of Non-GHG Pollutants

C. Environmental Effects of Non-GHG Pollutants

D. Air Quality Impacts of Non-GHG Pollutants
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VIII. What are the Agencies’ Estimated Cost, Economic, and Other Impacts of the Final 

Program?

A. Conceptual Framework for Evaluating Impacts

B. Costs Associated With the Final Program

C. Indirect Cost Multipliers

D. Cost per Ton of Emissions Reductions

E. Impacts of Reduction in Fuel Consumption

F. Class Shifting and Fleet Turnover Impacts

G. Benefits of Reducing CO2 Emissions

H. Non-GHG Health and Environmental Impacts

I. Energy Security Impacts

J. Other Impacts

K. The Effect of Safety Standards and Voluntary Safety Improvements on Vehicle 

Weight

L. Summary of Costs and Benefits

M. Employment Impacts

IX. Analysis of the Alternatives

A. What Are the Alternatives that the Agencies Considered?

B. How Do These Alternatives Compare in Overall GHG Emissions Reductions and Fuel 

Efficiency and Cost?

C. What Is the Agencies’ Decision Regarding Trailer Standards?

X. Public Participation

XI. NHTSA’s Record of Decision

A. The Agency’s Decision

B. Alternatives Considered by NHTSA in Reaching its Decision, Including the 

Environmentally Preferable Alternative

C. Factors Balanced by NHTSA in Making its Decision

D. How the Factors and Considerations Balanced by NHTSA Entered into its Decision

E. The Agency’s Preferences among Alternatives Based on Relevant Factors, Including 

Economic and Technical Considerations and Agency Statutory Missions

F. Mitigation

XII. Statutory and Executive Order Reviews

XIII. Statutory Provisions and Legal Authority

I. Overview

A. Introduction

EPA and NHTSA (“the agencies”) are announcing a first-ever program to reduce 

greenhouse gas (GHG) emissions and fuel consumption in the heavy-duty highway 

vehicle sector. This broad sector – ranging from large pickups to sleeper-cab tractors –

together represent the second largest contributor to oil consumption and GHG emissions
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from the mobile source sector, after light-duty passenger cars and trucks. These are the 

second joint rules issued by the agencies, following on the April 1, 2010 standards to 

sharply reduce GHG emissions and fuel consumption from MY 2012-2016 passenger 

cars and light trucks (published on May 7, 2010 at 75 FR 25324). 

In a May 21, 2010 memorandum to the Administrators of EPA and NHTSA (and 

the Secretaries of Transportation and Energy), the President stated that “America has the 

opportunity to lead the world in the development of a new generation of clean cars and 

trucks through innovative technologies and manufacturing that will spur economic 

growth and create high-quality domestic jobs, enhance our energy security, and improve 

our environment.” 1,2 In the May 2010 memorandum, the President specifically requested

the Administrators of EPA and NHTSA to “immediately begin work on a joint 

rulemaking under the Clean Air Act (CAA) and the Energy Independence and Security

Act of 2007 (EISA) to establish fuel efficiency and greenhouse gas emissions standards 

for commercial medium-and heavy-duty on-highway vehicles and work trucks beginning 

with the 2014 model year (MY).” In this final rulemaking, each agency is addressing this 

Memorandum by adopting rules under its respective authority that together comprise a 

coordinated and comprehensive HD National Program designed to address the urgent and 

closely intertwined challenges of reduction of dependence on oil, achievement of energy

security, and amelioration of global climate change. 

At the same time, the final program will enhance American competitiveness and 

job creation, benefit consumers and businesses by reducing costs for transporting goods, 

and spur growth in the clean energy sector. 

The HD National Program the agencies are finalizing today reflects a 

collaborative effort between the agencies, a range of public interest nongovernmental 

organizations (NGOs), the state of California and the regulated industry. At the time of 

the President’s announcement, a number of major HD truck and engine manufacturers 

representing the vast majority of this industry, and the California Air Resources Board

(California ARB), sent letters to EPA and NHTSA supporting the creation of a HD 

National Program based on a common set of principles. In the letters, the stakeholders 

committed to working with the agencies and with other stakeholders toward a program 

consistent with common principles, including:

 Increased use of existing technologies to achieve significant GHG emissions and fuel 

consumption reductions;

 

1

Improving Energy Security, American Competitiveness and Job Creation, and Environmental Protection 

Through a Transformation of Our Nation’s Fleet of Cars And Trucks,” Issued May 21, 2010, published at 

75 FR 29399, May 26, 2010.

2 The May 2010 Presidential Memorandum also directed EPA and NHTSA, in close coordination with the

California Air Resources Board, to build on the National Program for 2012-2016 MY light-duty vehicles 

by developing and proposing coordinated light-duty vehicle standards for MY 2017-2025. The agencies 

have taken an initial step in this process, releasing a Joint Notice of Intent and Initial Joint Technical 

Assessment Report in September 2010 (75 FR 62739), and a Supplemental Notice of Intent (75 FR 76337). 

The agencies plan to issue a full light-duty vehicle proposal to extend the National Program to MY 2017-

2025 in September 2011.
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 A program that starts in 2014 and is fully phased in by 2018;

 A program that works towards harmonization of methods for determining a vehicle’s 

GHG and fuel efficiency, recognizing the global nature of the issues and the industry;

 Standards that recognize the commercial needs of the trucking industry; and

 Incentives leading to the early introduction of advanced technologies.

The final rules adopted today reflect these principles. The final HD National 

Program also builds on many years of heavy-duty engine and vehicle technology

development to achieve what the agencies believe is the greatest degree of fuel 

consumption and GHG emission reduction appropriate, technologically and economically 

feasible, and cost-effective for model years 2014-2018. In addition to taking aggressive 

steps that are reasonably possible now, based on the technological opportunities and 

pathways that present themselves during these model years, the agencies and industry

will also continue learning about emerging opportunities for this complex sector to 

further reduce fuel consumption and GHG emission through future regulatory steps. 

Similarly, the agencies will participate in efforts to improve our ability to 

accurately characterize the actual in-use fuel consumption and emissions of this complex 

sector. As technologies progress in the coming years and as the agencies improve the 

regulatory tools to evaluate real world vehicle performance, we expect that we will 

develop a second phase of regulations to reinforce these initial rules and achieve further

reductions in GHG emissions and fuel consumption reduction for the mid- and longerterm time frame (beyond 2018). The agencies are committed to working with all 

interested stakeholders in this effort and to the extent possible working towards alignment 

with similar programs being developed in Canada, Mexico, Europe, China, and Japan. In 

doing so, we will continue to evaluate many of the structural and technical decisions we 

are making in today’s final action in the context of new technologies and the new 

regulatory tools that we expect to realize in the future.

The regulatory program we are finalizing today is largely unchanged from the 

proposal the agencies made on November 30, 2010 (See 75 FR 741512). The structure of 

the program and the stringency of the standards are essentially the same as proposed. We 

have made a number of changes to the testing requirements and reporting requirements to 

provide greater regulatory certainty and better align the NHTSA and EPA portions of the 

program. In response to comments, we have also made some changes to the averaging, 

banking and trading (ABT) provisions of the program that will make implementation of 

this final program more flexible for manufacturers. We have added provisions to further 

encourage the development of advanced technologies and to provide a more 

straightforward mechanism to certify engines and vehicles using innovative technologies. 

Finally in response to comments, we have made some technical changes to our emissions 

compliance model that results in different numeric standards for both combination 

tractors and vocational vehicles to more accurately characterize emissions while 

maintaining the same overall stringency and therefore expected costs and benefits of the 

program.
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Heavy-duty vehicles move much of the nation’s freight and carry out numerous 

other tasks, including utility work, concrete delivery, fire response, refuse collection, and 

many more. Heavy-duty vehicles are primarily powered by diesel engines, although 

about 37 percent of these vehicles are powered by gasoline engines.3 Heavy-duty trucks4

have long been an important part of the goods movement infrastructure in this country

and have experienced significant growth over the last decade related to increased imports 

and exports of finished goods and increased shipping of finished goods to homes through 

internet purchases.

The heavy-duty sector is extremely diverse in several respects, including types of 

manufacturing companies involved, the range of sizes of trucks and engines they

produce, the types of work the trucks are designed to perform, and the regulatory history 

of different subcategories of vehicles and engines. The current heavy-duty fleet 

encompasses vehicles from the “18-wheeler” combination tractors one sees on the 

highway to school and transit buses, to vocational vehicles such as utility service trucks, 

as well as the largest pickup trucks and vans.

For purposes of this preamble, the term “heavy-duty” or “HD” is used to apply to 

all highway vehicles and engines that are not within the range of light-duty vehicles, 

light-duty trucks, and medium-duty passenger vehicles (MDPV) covered by the GHG and 

Corporate Average Fuel Economy (CAFE) standards issued for MY 2012-2016.5 It also 

does not include motorcycles. Thus, in this rulemaking, unless specified otherwise, the 

heavy-duty category incorporates all vehicles with a gross vehicle weight rating above 

8,500 pounds, and the engines that power them, except for MDPVs.6 

The agencies proposed to cover all segments of the heavy-duty category above,

except with respect to recreational vehicles (RV’s or motor homes). We note that the 

Energy Independence and Security Act of 2007 requires NHTSA to set standards for 

“commercial medium- and heavy-duty on-highway vehicles and work trucks.”

7

 The 

standards that EPA is finalizing today cover recreational on-highway vehicles, 

while NHTSA proposed not to include recreational vehicles based on an interpretation of 

the term “commercial medium- and heavy-duty on-highway commercial” vehicles. 

 

3 References in this preamble to “gasoline” engines (and the vehicles powered by them) generally include 

other Otto-cycle engines as well, such as those fueled by ethanol and natural gas, except in contexts that are 

clearly gasoline-specific.

4

In this rulemaking, EPA and NHTSA use the term “truck” in a general way, referring to all categories of 

regulated heavy-duty highway vehicles (including buses). As such, the term is generally interchangeable 

with “heavy-duty vehicle.”

5

 Light-Duty Vehicle Greenhouse Gas Emission Standards and Corporate Average Fuel Economy 

Standards; Final Rule 75 FR 25323, May 7, 2010.

6

 The CAA defines heavy-duty as a truck, bus or other motor vehicles with a gross vehicle weight rating 

exceeding 6,000 pounds (CAA section 202(b)(3)). The term HD as used in this action refers to a subset of 

these vehicles and engines.

7

49 U.S.C. 32902(k)(2). “Commercial medium- and heavy-duty on-highway vehicles” are defined as onhighway vehicles with a gross vehicle weight rating of 10,000 pounds or more, while “work trucks” are 

defined as vehicles rated between 8,500 and 10,000 pounds gross vehicle weight that are not MDPVs. See

49 U.S.C. §§ 32901(a)(7) and (a)(19).
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NHTSA stated in the NPRM that recreational vehicles are non-commercial, and therefore 

outside of the term and the scope of its rule. 

Oshkosh Corporation commented that this interpretation did not match the 

statutory definition of the term in EISA, which defines “commercial medium- and heavyduty on-highway vehicle” by weight only,

8

and that therefore the agency’s interpretation 

of the term should be explicitly broadened to include all vehicles, and more than only

vehicles that are not engaged in interstate commerce as defined by the Federal Motor 

Carrier Safety Administration in 49 CFR § 202. Alternatively, Oshkosh suggested that if 

NHTSA followed the definition provided in EISA, which makes no direct reference to 

the concept of “commercial,” there would be no logical reason to exclude RVs based on 

that definition. 

NHTSA has considered Oshkosh’s comment and reconsidered its interpretation 

that effectively read words into the statutory definition. Given the very wide variety of 

vehicles contained in the HD fleet, reading those words into the definition and thereby 

excluding certain types of vehicles could create illogical results, i.e., treating similar 

vehicles differently. Therefore, NHTSA will adhere to the statutory definition contained 

in EISA for this rulemaking. However, as RVs were not included by NHTSA in the 

proposed regulation in the NPRM, they are not within the scope and must be excluded in 

NHTSA’s portion of the final program. Accordingly, NHTSA will address this issue in 

the next rulemaking. However, as noted, RVs are subject to the CO2 standards for 

vocational vehicles. 

Setting fuel consumption standards for the heavy-duty sector, pursuant to 

NHTSA’s EISA authority, will also improve our energy and national security by

reducing our dependence on foreign oil, which has been a national objective since the 

first oil price shocks in the 1970s. Net petroleum imports now account for approximately

49-51 percent of U.S. petroleum consumption. World crude oil production is highly

concentrated, exacerbating the risks of supply disruptions and price shocks as the recent 

unrest in North Africa and the Persian Gulf highlights. Recently, oil prices have been

over $100 per barrel, gasoline and diesel fuel prices in excess of $4 per gallon, causing 

financial hardship for many families and businesses. The export of U.S. assets in 

exchange for oil imports continues to be an important component of the historically

unprecedented U.S. trade deficits. Transportation accounts for about 72 percent of U.S. 

petroleum consumption. Heavy-duty vehicles account for about 17 percent of 

transportation oil use, which means that they alone account for about 12 percent of all 

U.S. oil consumption.

9

Setting GHG emissions standards for the heavy-duty sector will help to 

ameliorate climate change. The EPA Administrator found after a thorough examination 

of the scientific evidence on the causes and impact of current and future climate change, 

and careful review of public comments, that the science compellingly supports a positive 

finding that atmospheric concentrations of six greenhouse gases taken in combination 

 

8

See 49 U.S.C. 32902(k)(2), Note 7 above.

9

In 2009 Source: EIA Annual Energy Outlook 2010 released May 11, 2010.
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result in air pollution which may reasonably be anticipated to endanger both public health 

and welfare and that the combined emissions of these greenhouse gases from new motor 

vehicles and engines contributes to the greenhouse gas air pollution that endangers public 

health and welfare. In her finding, the Administrator carefully studied and relied heavily 

upon the major findings and conclusions from the recent assessments of the U.S. Climate

Change Science Program and the U.N. Intergovernmental Panel on Climate Change. 74 

FR 66496, December 15, 2009. As summarized in the Technical Support Document for 

EPA’s Endangerment and Cause or Contribute Findings under section 202(a) of the 

Clean Air Act, anthropogenic emissions of GHGs are very likely (a 90 to 99 percent 

probability) the cause of most of the observed global warming over the last 50 years.10 

Primary GHGs of concern are carbon dioxide (CO2), methane (CH4), nitrous oxide

(N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride

(SF6). Mobile sources emitted 31 percent of all U.S. GHGs in 2007 (transportation 

sources, which do not include certain off-highway sources, account for 28 percent) and 

have been the fastest-growing source of U.S. GHGs since 1990.11 Mobile sources 

addressed in EPA’s endangerment and contribution findings under CAA section 202(a) --

light-duty vehicles, heavy-duty trucks, buses, and motorcycles -- accounted for 23 

percent of all U.S. GHG emissions in 2007.12 Heavy-duty vehicles emit CO2, CH4, N2O, 

and HFCs and are responsible for nearly 19 percent of all mobile source GHGs (nearly

6% of all U.S. GHGs) and about 25 percent of section 202(a) mobile source GHGs. For 

heavy-duty vehicles in 2007, CO2 emissions represented more than 99 percent of all 

GHG emissions (including HFCs).

13

In developing this HD National program, the agencies have worked with a large 

and diverse group of stakeholders representing truck and engine manufacturers, trucking 

fleets, environmental organizations, and states including the State of California.14 

Further, it is our expectation based on our ongoing work with the State of California that 

the California ARB will be able to adopt regulations equivalent in practice to those of this 

HD National Program, just as it has done for past EPA regulation of heavy-duty trucks 

and engines. NHTSA and EPA have been working with California ARB to enable that 

outcome.

In light of the industry’s diversity, and consistent with the recommendations of 

the National Academy of Sciences (NAS) as discussed further below, the agencies are 

adopting a HD National Program that recognizes the different sizes and work 

 

10 U.S. EPA. (2009). “Technical Support Document for Endangerment and Cause or Contribute Findings 

for Greenhouse Gases Under Section 202(a) of the Clean Air Act” Washington, D.C., available at Docket: 

EPA-HQ-OAR-2009-0171-11645, and at http://epa.gov/climatechange/endangerment.html.

11 U.S. Environmental Protection Agency. 2009. Inventory of U.S. Greenhouse Gas Emissions and Sinks: 

1990-2007. EPA 430-R-09-004. Available at 

http://epa.gov/climatechange/emissions/downloads09/GHG2007entire_report-508.pdf 

12 See Endangerment TSD, Note 10, above, at pp. 180-194.

13 U.S. Environmental Protection Agency. 2009. Inventory of U.S. Greenhouse Gas Emissions and Sinks: 

See Note 11, above. 

14 Pursuant to DOT Order 2100.2, NHTSA has docketed a memorandum recording those meetings that it 

attended and documents submitted by stakeholders which formed a basis for this action and which can be 

made publicly available in its docket for this rulemaking. DOT Order 2100.2 is available at 

http://www.reg-group.com/library/DOT2100-2.PDF.
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requirements of this wide range of heavy-duty vehicles and their engines. NHTSA’s final 

fuel consumption standards and EPA’s final GHG standards apply to manufacturers of 

the following types of heavy-duty vehicles and their engines; the final provisions for each 

of these are described in more detail below in this section:

 Heavy-duty Pickup Trucks and Vans

 Combination Tractors

 Vocational Vehicles

As in the light-duty 2012-2016 MY vehicle rule, EPA’s and NHTSA’s final

standards for the heavy-duty sector are largely harmonized with one another due to the 

close and direct relationship between improving the fuel efficiency of these vehicles and 

reducing their CO2 tailpipe emissions. For all vehicles that consume carbon-based fuels, 

the amount of CO2 exhaust emissions is essentially constant per gallon for a given type of 

fuel that is consumed. The more efficient a heavy-duty truck is in completing its work, 

the lower its environmental impact will be, because the less fuel consumed to move cargo 

a given distance, the less CO2 that truck emits directly into the air. The technologies 

available for improving fuel efficiency, and therefore for reducing both CO2 emissions 

and fuel consumption, are one and the same.15 Because of this close technical 

relationship, NHTSA and EPA have been able to rely on jointly-developed assumptions, 

analyses, and analytical conclusions to support the standards and other provisions that 

NHTSA and EPA are adopting under our separate legal authorities.

This program is based on standards for direct exhaust emissions from engines and 

vehicles. In characterizing the overall emissions impacts, benefits and costs of the 

program, analyses of air pollutant emissions from upstream sources have been conducted. 

In this action, the agencies use the term upstream to include emissions from the 

production and distribution of fuel. A summary of the analysis of upstream emissions can 

be found in Section VI.C of this preamble, and further details are available in Chapter 5 

of the RIA.

The timelines for the implementation of the final NHTSA and EPA standards are 

also closely coordinated. EPA’s final GHG emission standards will begin in model year 

2014. In order to provide for the four full model years of regulatory lead time required 

by EISA, as discussed in Section I. B. (5) below, NHTSA’s final fuel consumption 

standards will be voluntary in model years 2014 and 2015, becoming mandatory in model 

year 2016, except for diesel engine standards which will be voluntary in model years 

2014, 2015 and 2016, becoming mandatory in model year 2017. Both agencies are also 

allowing for early compliance in model year 2013. A detailed discussion of how the final 

standards are consistent with each agency’s respective statutory requirements and 

authorities is found later in this preamble. 

 

15 However, as discussed below, in addition to addressing CO2, the EPA’s final standards also include 

provisions to address other GHGs (nitrous oxide, methane, and air conditioning refrigerant emissions). See

Section II.
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Allison Transmission stated that sufficient time must be taken before issuing the 

final rules in order to ensure that the standards are supportable. As explained in Sections 

II and III below, as well as in the RIA, the agencies believe there is sufficient lead time to 

meet all of the standards adopted in today’s rules. For those areas for which the agencies 

have determined that insufficient time is available to develop appropriate standards, such 

as for trailers, the agencies are not including regulations as part of this initial program.

NHTSA received several comments related to the timing of the implementation of 

its fuel consumption standards. The Engine Manufacturers Association (EMA), the 

National Automobile Dealers Association (NADA), The Volvo Group (Volvo), and 

Navistar argued that the timing of NHTSA’s standards violated the lead time requirement 

of 49 U.S.C. 32902(k)(3)(A), which states that standards under the new medium- and 

heavy-duty program shall have “not less than 4 full model years of regulatory lead-time.” 

The commenters seemed to interpret the voluntary program as the imposition of 

regulation upon industry. NADA described NHTSA’s standards during the voluntary

period as “mandates.” 

NHTSA has reviewed this issue and believes that the regulatory schedule is 

consistent with the lead time requirement of 32902(k)(3). To clarify, NHTSA will not be 

imposing a mandatory regulatory program until 2016, and none of the voluntary

standards will be “mandates.” As described in later sections, the voluntary standards 

would only apply to a manufacturer if it makes the voluntary and affirmative choice to 

opt-in to the program. 16 Mandatory NHTSA standards will first come into effect in 

2016, giving industry four full years of lead time with the NHTSA fuel consumption 

standards. 

EMA, NADA, and Navistar also argued that the proposed standards would violate 

the stability requirement of 49 U.S.C. 32902(k)(3)(B), which states that they shall have 

“not less than 3 full model years of regulatory stability.” EMA stated that since there are 

HD emission standards taking effect in 2013, the 2014 implementation date for this rule 

would violate the stability requirements. NADA argued that the MY 2014-2017/2018 

phase-in period was inadequate to fulfill the stability requirement. 

Congress has not spoken directly to the meaning of the words “regulatory

stability.” NHTSA believes that the “regulatory stability” requirement exists to ensure

that manufacturers will not be subject to new standards in repeated rulemakings too 

rapidly, given that Congress did not include a minimum duration period for the MD/HD 

standards.17 NHTSA further believes that standards, which as set provide for increasing 

stringency during the period that the standards are applicable under this rule to be the 

maximum feasible during the regulatory period, are within the meaning of the statute. In 

this statutory context, NHTSA interprets the phrase “regulatory stability” in § 

32902(k)(3)(B) as requiring that the standards remain in effect for three years before they

 

16 Prior to or at the same time that a manufacturer submits its first application for a certificate of 

conformity; See Section V below. 

17 In contrast, light-duty standards must remain in place for “at least 1, but not more than 5, model years.” 

23902(b)(3)(B).
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may be increased by amendment. It does not prohibit standards which contain predetermined stringency increases. 

As laid out in Section II below, NHTSA’s final standards follow different phasein schedules based on differences between the regulatory categories. Consistent with 

NHTSA’s statutory obligation to implement a program designed to achieve the maximum 

feasible fuel efficiency improvement, the standards increase in stringency based upon 

increasing fleet penetration rates for the available technologies. The NPRM proposed 

phase-in schedules aligned with EPA’s, some of which followed pre-determined 

stringency increases. The NPRM also noted that NHTSA was considering alternate 

standards that would not change in stringency during the time frame when the regulations 

are effective for those standards that increased throughout the mandatory program. As 

described in Section II below, the final rule includes the proposed alternate standards for 

those standards that follow such a stringency phase-in path. Therefore, NHTSA believes 

that the final rule provides ample stability for each standard.

Each standard, associated phase-in schedule, and alternative standard 

implemented by this final rule was noticed in the NPRM. Those fuel consumption 

standards that become mandatory in 2017 will remain in effect through at least 2019. 

This further ensures that the fuel consumption standards in this rule will remain in effect 

for at least three years, providing the statutorily-mandated three full years of regulatory

stability, and ensuring that manufacturers will not be subject to new or amended 

standards too rapidly. (The greenhouse gas emission standards remain in effect unless 

and until amended in all later model years in any case.) Therefore, NHTSA believes the 

commenters’ concern about regulatory stability is addressed in the structure of the rule.

Neither EPA nor NHTSA is adopting standards at this time for GHG emissions or 

fuel consumption, respectively, for heavy-duty commercial trailers or for vehicles or 

engines manufactured by small businesses. The agencies recognize that aerodynamic and 

tire rolling resistance improvements to trailers represent a significant opportunity to 

reduce fuel consumption and GHGs as evidenced, among other things, by the work of the 

EPA SmartWay program. While we are deferring action today on setting trailer 

standards, the agencies are committed to moving forward to create a regulatory program 

for trailers that would complement the current vehicle program. See Section IX for more 

details on the agencies’ decisions regarding trailers, and Sections II and XII for more 

details on the agencies’ decisions regarding small businesses. 

The agencies have analyzed in detail the projected costs, fuel savings, and 

benefits of the final GHG and fuel consumption standards. Table I-1 shows estimated 

lifetime discounted program costs (including technological outlays), fuel savings, and

benefits for all heavy-duty vehicles projected to be sold in model years 2014-2018 over 

these vehicles’ lives. Section I.D includes additional information about this analysis.
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Table I-1: Estimated Lifetime Discounted Costs, Fuel Savings, Benefits, and Net Benefits

for 2014-2018 Model Year Heavy-Duty Vehicles a,b (Billions, 2009$)

Lifetime Present Valuec– 3% Discount Rate

Program Costs $8.1

Fuel Savings $50

Benefits $7.3

Net Benefitsd$49

Annualized Valuee– 3% Discount Rate

Annualized Costs $0.4

Fuel Savings $2.2

Annualized Benefits $0.4

Net Benefitsd$2.2

Lifetime Present Valuec- 7% Discount Rate

Program Costs $8.1

Fuel Savings $34

Benefits $6.7

Net Benefitsd$33

Annualized Valuee– 7% Discount Rate

Annualized Costs $0.6

Fuel Savings $2.6

Annualized Benefits $0.5

Net Benefitsd$2.5

Notes:

a The agencies estimated the benefits associated with four different values of a one ton 

CO2 reduction (model average at 2.5% discount rate, 3%, and 5%; 95th percentile at 3%), 

which each increase over time. For the purposes of this overview presentation of 

estimated costs and benefits, however, we are showing the benefits associated with the 

marginal value deemed to be central by the interagency working group on this topic: the 

model average at 3% discount rate, in 2009 dollars. Section VIII.F provides a complete 

list of values for the 4 estimates.

b Note that net present value of reduced GHG emissions is calculated differently than

other benefits. The same discount rate used to discount the value of damages from future 

emissions (SCC at 5, 3, and 2.5 percent) is used to calculate net present value of SCC for 

internal consistency. Refer to Section VIII.F for more detail.

c

Present value is the total, aggregated amount that a series of monetized costs or benefits 

that occur over time is worth now (in year 2009 dollar terms), discounting future values 

to the present.

d Net benefits reflect the fuel savings plus benefits minus costs.

e The annualized value is the constant annual value through a given time period (2012 

through 2050 in this analysis) whose summed present value equals the present value from 

which it was derived.
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B. Building Blocks of the Heavy-duty National Program

The standards that are being adopted in this notice represent the first time that 

NHTSA and EPA are regulating the heavy-duty sector for fuel consumption and GHG 

emissions, respectively. The HD National Program is rooted in EPA’s prior regulatory 

history, the SmartWay Transport Partnership program, and extensive technical and 

engineering analyses done at the federal level. This section summarizes some of the most 

important of these precursors and foundations for this HD National Program. 

(1) EPA’s Traditional Heavy-duty Regulatory Program

Since the 1980s, EPA has acted several times to address tailpipe emissions of 

criteria pollutants and air toxics from heavy-duty vehicles and engines. During the last 

18 years, these programs have primarily addressed emissions of particulate matter (PM) 

and the primary ozone precursors, hydrocarbons (HC) and oxides of nitrogen (NOX). 

These programs have successfully achieved significant and cost-effective reductions in 

emissions and associated health and welfare benefits to the nation. They have been 

structured in ways that account for the varying circumstances of the engine and truck 

industries. As required by the CAA, the emission standards implemented by these 

programs include standards that apply at the time that the vehicle or engine is sold as well 

as standards that apply in actual use. As a result of these programs, new vehicles meeting 

current emission standards will emit 98 percent less NOX and 99 percent less PM than 

new trucks 20 years ago. The resulting emission reductions provide significant public 

health and welfare benefits. The most recent EPA regulations which were fully phased-in 

in 2010, the monetized health and welfare benefits alone are projected to be greater than 

$70 billion in 2030 – benefits far exceeding compliance costs and not including the 

unmonetized benefits resulting from reductions in air toxics and ozone precursors (66 FR 

5002, January 18, 2001). 

EPA’s overall program goal has always been to achieve emissions reductions 

from the complete vehicles that operate on our roads. The agency has often accomplished 

this goal for many heavy-duty truck categories through the regulation of heavy-duty

engine emissions. A key part of this success has been the development over many years 

of a well-established, representative, and robust set of engine test procedures that industry

and EPA now routinely use to measure emissions and determine compliance with 

emission standards. These test procedures in turn serve the overall compliance program 

that EPA implements to help ensure that emissions reductions are being achieved. By

isolating the engine from the many variables involved when the engine is installed and 

operated in a HD vehicle, EPA has been able to accurately address the contribution of the 

engine alone to overall emissions. The agencies discuss below how the final program 

incorporates the existing engine-based approach used for criteria pollutant regulations, as 

well as new vehicle-based approaches. 
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(2) NHTSA’s Responsibilities to Regulate Heavy-Duty Fuel Efficiency under 

EISA

With the passage of the EISA in December 2007, Congress laid out a framework 

developing the first fuel efficiency regulations for HD vehicles. As codified at 49 U.S.C. 

32902(k), EISA requires NHTSA to develop a regulatory system for the fuel efficiency of 

commercial medium-duty and heavy-duty on-highway vehicles and work trucks in three 

steps: a study by NAS, a study by NHTSA, and a rulemaking to develop the regulations 

themselves.18

Specifically, section 102 of EISA, codified at 49 U.S.C. 32902(k)(2), states that 

not later than two years after completion of the NHTSA study, DOT (by delegation, 

NHTSA), in consultation with the Department of Energy (DOE) and EPA, shall develop 

a regulation to implement a “commercial medium-duty and heavy-duty on-highway

vehicle and work truck fuel efficiency improvement program designed to achieve the 

maximum feasible improvement.” NHTSA interprets the timing requirements as 

permitting a regulation to be developed earlier, rather than as requiring the agency to wait 

a specified period of time.

Congress specified that as part of the “HD fuel efficiency improvement program 

designed to achieve the maximum feasible improvement,” NHTSA must adopt and 

implement:

 Appropriate test methods;

 Measurement metrics;

 Fuel economy standards;19 and

 Compliance and enforcement protocols.

Congress emphasized that the test methods, measurement metrics, standards, and 

compliance and enforcement protocols must all be appropriate, cost-effective, and 

technologically feasible for commercial medium-duty and heavy-duty on-highway

vehicles and work trucks. NHTSA notes that these criteria are different from the “four 

factors” of 49 U.S.C. 32902(f)20 that have long governed NHTSA’s setting of fuel 

economy standards for passenger cars and light trucks, although many of the same issues 

are considered under each of these provisions.

 

18 The NAS study is described below, and the NHTSA study accompanies this FRM.

19 In the context of 49 U.S.C. 32902(k), NHTSA interprets “fuel economy standards” as referring not 

specifically to miles per gallon, as in the light-duty vehicle context, but instead more broadly to account as 

accurately as possible for MD/HD fuel efficiency. While it is a metric that NHTSA considered for setting 

MD/HD fuel efficiency standards, the agency recognizes that miles per gallon may not be an appropriate 

metric given the work that MD/HD vehicles are manufactured to do. NHTSA is thus finalizing alternative 

metrics as discussed further below.

20 49 U.S.C. 32902(f) states that “When deciding maximum feasible average fuel economy under this 

section, [NHTSA] shall consider technological feasibility, economic practicability, the effect of other motor 

vehicle standards of the Government on fuel economy, and the need of the United States to conserve 

energy.”
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Congress also stated that NHTSA may set separate standards for different classes 

of HD vehicles, which the agency interprets broadly to allow regulation of HD engines in 

addition to HD vehicles, and provided requirements new to 49 U.S.C. 32902 in terms of 

timing of regulations, stating that the standards adopted as a result of the agency’s 

rulemaking shall provide not less than four full model years of regulatory lead time, and 

three full model years of regulatory stability.

(3) National Academy of Sciences Report on Heavy-Duty Technology 

In April 2010 as mandated by Congress in EISA, the National Research Council 

(NRC) under NAS issued a report to NHTSA and to Congress evaluating medium-duty

and heavy-duty truck fuel efficiency improvement opportunities, titled “Technologies and 

Approaches to Reducing the Fuel Consumption of Medium- and Heavy-duty Vehicles.”

21 This study covers the same universe of heavy-duty vehicles that is the focus of this 

final rulemaking – all highway vehicles that are not light-duty, MDPVs, or motorcycles. 

The agencies have carefully evaluated the research supporting this report and its

recommendations and have incorporated them to the extent practicable in the 

development of this rulemaking.

The NAS report is far reaching in its review of the technologies that are available 

and which may become available in the future to reduce fuel consumption from medium 

and heavy-duty vehicles. In presenting the full range of technical opportunities the report 

includes technologies which may not be available until 2020 or even further into the 

future. As such, the report provides not only a valuable list of off the shelf technologies 

from which the agencies have drawn in developing this near-term 2014-2018 program 

consistent with statutory authorities and with the set of principles set forth by the 

President, but the report also provides a road map the agencies can use as we look to 

develop future regulations for this sector. A review of the technologies in the NAS report 

makes clear that there are not only many technologies readily available today to achieve 

important reductions in fuel consumption, like the ones we used in developing the 2014-

2018 program, but there are also great opportunities for even larger reductions in the 

future through the development of advanced hybrid drive systems and sophisticated 

engine technologies such as Rankine waste heat recovery. The agencies will again make 

extensive use of this report when we move forward to develop the next phase of 

regulations for medium and heavy-duty vehicles.

Allison Transmission commented that NHTSA (implicitly, both agencies) had 

improperly relied on the NAS report and failed to do sufficient independent analysis, 

which Allison claimed did not meet the statutory obligation to provide an adequate basis 

for the rule. First, an agency does not improperly delegate its authority or judgment 

merely by using work performed by outside parties as the factual basis for its decision 

making. See U.S. Telecom Ass’n v. FCC, 359 F.3d 554, 568 (D.C. Cir. 2004); United 

 

21 Committee to Assess Fuel Economy Technologies for Medium- and Heavy-Duty Vehicles; National 

Research Council; Transportation Research Board (2010). “Technologies and Approaches to Reducing the 

Fuel Consumption of Medium- and Heavy-Duty Vehicles,” (hereafter, “NAS Report”). Washington, D.C., 

The National Academies Press. Available electronically from the National Academies Press Website at 

http://www.nap.edu/catalog.php?record_id=12845 (last accessed September 10, 2010).
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Steelworkers of Am. v. Marshall, 647 F.2d 1189, 1216-17 (D.C. Cir. 1980). Here, 

although EPA and NHTSA carefully considered the NAS report, the agencies’ 

consideration and use of the report was not uncritical and the agencies exercised 

reasonable independent judgment in developing the proposed and final rules. Consistent 

with EISA’s direction, NAS submitted a report evaluating MD/HD fuel economy

standards to NHTSA in March of 2010. Indeed, many commenters argued that the 

agencies should have adopted more of the NAS report recommendations. The agencies 

reviewed the findings and recommendations of the NAS report when developing the 

proposed rules, as was clearly intended by Congress, but also conducted an independent 

study, as described throughout the record to the proposal and summarized in Section X of 

the NPRM, 75 FR at 74351-56. In conducting its analysis of the NAS report, the 

agencies found that several key recommendations, such as the use of fuel efficiency

metrics, were the best approach to implementing the new program. However, the 

agencies rejected other recommendations of the NAS report, for example, by proposing 

separate regulation of engines and vehicles and the regulation of large manufacturers. 

(4) The NHTSA and EPA Light-duty National GHG and Fuel Economy 

Program

On May 7, 2010, EPA and NHTSA finalized the first-ever National Program for 

light-duty cars and trucks, which set GHG emissions and fuel economy standards for 

model years 2012-2016 (See 75 FR 25324). The agencies have used the light-duty

National Program as a model for this final HD National Program in many respects. This 

is most apparent in the case of heavy-duty pickups and vans, which are very similar to the 

light-duty trucks addressed in the light-duty National Program both technologically as 

well as in terms of how they are manufactured (i.e., the same company often makes both 

the vehicle and the engine). For these vehicles, there are close parallels to the light-duty 

program in how the agencies have developed our respective final standards and 

compliance structures, although, as discussed below, the technologies applied to lightduty trucks are not invariably applicable to heavy-duty pickups and vans at the same 

penetration rates in the lead time afforded in this heavy-duty action. Another difference 

is that each agency adopts standards based on attributes other than vehicle footprint, as 

discussed below.

Due to the diversity of the remaining HD vehicles, there are fewer parallels with 

the structure of the light-duty program. However, the agencies have maintained the same 

collaboration and coordination that characterized the development of the light-duty 

program. Most notably, as with the light-duty program, manufacturers will be able to 

design and build vehicles to meet a closely coordinated, harmonized national program, 

and avoid unnecessarily duplicative testing and compliance burdens. 

(5) EPA’s SmartWay Program

EPA’s voluntary SmartWay Transport Partnership program encourages shipping 

and trucking companies to take actions that reduce fuel consumption and CO2 by working 

with the shipping community and the freight sector to identify low carbon strategies and 

technologies, and by providing technical information, financial incentives, and partner 
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recognition to accelerate the adoption of these strategies. Through the SmartWay

program, EPA has worked closely with truck manufacturers and truck fleets to develop 

test procedures to evaluate vehicle and component performance in reducing fuel 

consumption and has conducted testing and has established test programs to verify

technologies that can achieve these reductions. Over the last six years, EPA has 

developed hands-on experience testing the largest heavy-duty trucks and evaluating 

improvements in tire and vehicle aerodynamic performance. In 2010, according to 

vehicle manufacturers, approximately five percent of new combination heavy-duty trucks 

will meet the SmartWay performance criteria demonstrating that they represent the 

pinnacle of current heavy-duty truck reductions in fuel consumption. 

In developing this HD National Program, the agencies have drawn from the 

SmartWay experience, as discussed in detail both in Sections II and III below (e.g., 

developing test procedures to evaluate trucks and truck components) but also in the RIA 

(estimating performance levels from the application of the best available technologies 

identified in the SmartWay program). These technologies provide part of the basis for 

the GHG emission and fuel consumption standards in this rulemaking for certain types of 

new heavy-duty Class 7 and 8 combination tractors. 

In addition to identifying technologies, the SmartWay program includes 

operational approaches that truck fleet owners as well as individual drivers and their 

freight customers can incorporate, that the NHTSA and EPA believe will complement the 

final standards. These include such approaches as improved logistics and driver training, 

as discussed in the RIA. This approach is consistent with the one of the three alternative 

approaches that the NAS recommended be considered. The three approaches were 

raising fuel taxes, relaxing truck size and weight restrictions, and encouraging incentives 

to disseminate information to inform truck drivers about the relationship between driving 

behavior and fuel savings. Taxes and truck size and weight limits are mandated by public 

law; as such, these options are outside EPA’s and NHTSA’s authority to implement. 

However, complementary operational measures like driver training, which SmartWay

does promote, can complement the final standards and also provide benefits for the 

existing truck fleet, furthering the public policy objectives of addressing energy security

and climate change.

(6) Environment Canada

The Government of Canada’s Department of the Environment (Environment 

Canada) assisted EPA's development of this rulemaking by conducting emissions testing 

of heavy-duty vehicles at their test facilities to gather data on a range of possible test 

cycles, and to evaluate the impact of certain emissions reduction technologies.

Environment Canada also facilitated the evaluation of heavy-duty vehicle aerodynamic 

properties at Canada’s National Research Council wind tunnel, and during coastdown 

testing.

We expect the technical collaboration with Environment Canada to continue as 

we implement testing and compliance verification procedures for this rulemaking. We 

may also begin to develop a knowledge base enabling improvement upon this regulatory
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framework for model years beyond 2018 (for example, improvements to the means of 

demonstrating compliance). We also expect to continue our collaboration with 

Environment Canada on compliance issues. 

Collaboration with Environment Canada is taking place under the Canada-U.S. 

Air Quality Committee.

C. Summary of the Final EPA and NHTSA HD National Program

When EPA first addressed emissions from heavy-duty trucks in the 1980s, it 

established standards for engines, based on the amount of work performed (grams of 

pollutant per unit of work, expressed as grams per brake horsepower-hour or g/bhp-hr).22 

This approach recognized the fact that engine characteristics are the dominant 

determinant of the types of emissions generated, and engine-based technologies 

(including exhaust aftertreatment systems) need to be the focus for addressing those 

emissions. Vehicle-based technologies, in contrast, have less influence on overall truck 

emissions of the pollutants that EPA has regulated in the past. The engine testing 

approach also recognized the relatively small number of distinct heavy-duty engine 

designs, as compared to the extremely wide range of truck designs. EPA concluded at 

that time that any incremental gain in conventional emission control that could be 

achieved through regulation of the complete vehicle would be small in comparison to the 

cost of addressing the many variants of complete trucks that make up the heavy-duty 

sector – smaller and larger vocational vehicles for dozens of purposes, various designs of 

combination tractors, and many others.

Addressing GHG emissions and fuel consumption from heavy-duty trucks, 

however, requires a different approach. Reducing GHG emissions and fuel consumption 

requires increasing the inherent efficiency of the engine as well as making changes to the 

vehicles to reduce the amount of work demanded from the engine in order to move the 

truck down the road. A focus on the entire vehicle is thus required. For example, in 

addition to the basic emissions and fuel consumption levels of the engine, the 

aerodynamics of the vehicle can have a major impact on the amount of work that must be 

performed to transport freight at common highway speeds. For this first rulemaking, the 

agencies proposed a complementary engine and vehicle approach in order to achieve the 

maximum feasible near-term reductions.

NHTSA received comments on the proposal to create complementary engine and 

vehicle standards. Volvo and Daimler argued that EISA limited NHTSA’s authority to 

the regulation of completed vehicles and did not give NHTSA authority to regulate 

engines. 49 U.S.C. 32902(k)(2) grants NHTSA broad authority to regulate this sector, 

stating simply that the Secretary “shall determine in a rulemaking proceeding how to 

 

22 The term “brake power” refers to engine torque and power as measured at the interface between the 

engine’s output shaft and the dynamometer. This contrasts with “indicated power”, which is a calculated 

value based on the pressure dynamics in the combustion chamber, not including internal losses that occur 

due to friction and pumping work. Since the measurement procedure inherently measures brake torque and 

power, the final regulations refer simply to g/hp-hr. This is consistent with EPA’s other emission control 

programs, which generally include standards in g/kW-hr.
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implement a commercial medium- and heavy-duty on-highway vehicle and work truck 

fuel efficiency improvement program designed to achieve the maximum feasible 

improvement,” considering appropriateness, cost-effectiveness, and technological 

feasibility. NHTSA does not believe that this language precludes the regulation of 

engines, but rather explicitly leaves the regulatory approach to the agency’s expertise and 

discretion. See 75 FR at 74173 n. 36. Considering the factors described in the NPRM 

and in Sections III and IV below, NHTSA continues to believe that the separate 

regulation of engines and vehicles is both consistent with the agency’s statutory mandate 

to determine how to implement a regulatory program designed to achieve the maximum 

feasible improvement and facilitates coordination with EPA’s efforts to reduce 

greenhouse gas emissions. The Clean Air act, of course, mandates standards for both 

“new motor vehicles” and “new motor vehicle engines”, so there is no issue of authority 

for separate engine standards under the EPA GHG program. CAA section 202 (a)(1).

As described elsewhere in this preamble, the final standards under the HD 

National Program address the complete vehicle, to the extent practicable and appropriate 

under the agencies’ respective statutory authorities, through complementary engine and 

vehicle standards. The agencies continue to believe that this complementary engine and 

vehicle approach is the best way to achieve near term reductions from the heavy-duty 

sector. However, we also recognize as did the NAS committee and a wide range of 

industry and environmental commenters, that in order to fully capture the multi-faceted 

synergistic aspects of engine and vehicle design a more comprehensive complete vehicle 

standard may be appropriate in the future. The agencies are committed to fully exploring 

such a possibility and to developing the testing and modeling tools necessary to enable 

such a regulatory approach. We intend to work with all interested stakeholders as we 

move forward. 

(1) Brief Overview of the Heavy-duty Truck Industry

The heavy-duty truck sector spans a wide range of vehicles with often unique 

form and function. A primary indicator of the extreme diversity among heavy-duty 

trucks is the range of load-carrying capability across the industry. The heavy-duty truck 

sector is often subdivided by vehicle weight classifications, as defined by the vehicle’s 

gross vehicle weight rating (GVWR), which is a measure of the combined curb (empty) 

weight and cargo carrying capacity of the truck.

23

 Table I-2 below outlines the vehicle 

weight classifications commonly used for many years for a variety of purposes by 

businesses and by several federal agencies, including the Department of Transportation, 

the Environmental Protection Agency, the Department of Commerce, and the Internal 

Revenue Service.

 

23 GVWR describes the maximum load that can be carried by a vehicle, including the weight of the vehicle 

itself. Heavy-duty vehicles also have a gross combined weight rating (GCWR), which describes the 

maximum load that the vehicle can haul, including the weight of a loaded trailer and the vehicle itself. 
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Table I-2: Vehicle Weight Classification

Class 2b 3 4 5 6 7 8

GVWR 

(lb)

8,501 -

10,000

10,001-

14,000

14,001-

16,000

16,001-

19,500

19,501 

-26,000

26,001-

33,000

> 33,001

In the framework of these vehicle weight classifications, the heavy-duty truck 

sector refers to Class 2b through Class 8 vehicles and the engines that power those 

vehicles.24 Unlike light-duty vehicles, which are primarily used for transporting 

passengers for personal travel, heavy-duty vehicles fill much more diverse operator 

needs. Heavy-duty pickup trucks and vans (Classes 2b and 3) are used chiefly as work 

truck and vans, and as shuttle vans, as well as for personal transportation, with an average 

annual mileage in the range of 15,000 miles. The rest of the heavy-duty sector is used for 

carrying cargo and/or performing specialized tasks. “Vocational” vehicles, which may

span Classes 2b through 8, vary widely in size, including smaller and larger van trucks, 

utility “bucket” trucks, tank trucks, refuse trucks, urban and over-the-road buses, fire 

trucks, flat-bed trucks, and dump trucks, among others. The annual mileage of these 

trucks is as varied as their uses, but for the most part tends to fall in between heavy-duty 

pickups/vans and the large combination tractors, typically from 15,000 to 150,000 miles 

per year, although some travel more and some less. Class 7 and 8 combination tractortrailers – some equipped with sleeper cabs and some not -- are primarily used for freight 

transportation. They are sold as tractors and sometimes run without a trailer in between 

loads, but most of the time they run with one or more trailers that can carry up to 50,000 

pounds or more of payload, consuming significant quantities of fuel and producing 

significant amounts of GHG emissions. The combination tractor-trailers used in 

combination applications can travel more than 150,000 miles per year.

EPA and NHTSA have designed our respective standards in careful consideration 

of the diversity and complexity of the heavy-duty truck industry, as discussed next. 

(2) Summary of Final EPA GHG Emission Standards and NHTSA Fuel 

Consumption Standards

As described above, NHTSA and EPA recognize the importance of addressing the 

entire vehicle in reducing fuel consumption and GHG emissions. At the same time, the 

agencies understand that the complexity of the industry means that we will need to use 

different approaches to achieve this goal, depending on the characteristics of each general 

type of truck. We are therefore dividing the industry into three discrete regulatory

categories for purposes of setting our respective standards – combination tractors, heavyduty pickups and vans, and vocational vehicles -- based on the relative degree of 

homogeneity among trucks within each category. For each regulatory category, the 

agencies are adopting related but distinct program approaches reflecting the specific 

challenges that we see in these segments. In the following paragraphs, we discuss EPA’s 

final GHG emission standards and NHTSA’s final fuel consumption standards for the 

three regulatory categories of heavy-duty vehicles and their engines. 

 

24 Class 2b vehicles designed as passenger vehicles (Medium Duty Passenger Vehicles, MDPVs) are 

covered by the light-duty GHG and fuel economy standards and not addressed in this rulemaking.
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The agencies are adopting test metrics that express fuel consumption and GHG 

emissions relative to the most important measures of heavy-duty truck utility for each 

segment, consistent with the recommendation of the 2010 NAS Report that metrics 

should reflect and account for the work performed by various types of HD vehicles. This 

approach differs from NHTSA’s light-duty program that uses fuel economy as the basis. 

The NAS committee discussed the difference between fuel economy (a measure of how 

far a vehicle will go on a gallon of fuel) and fuel consumption (the inverse measure, of 

how much fuel is consumed in driving a given distance) as potential metrics for MD/HD 

regulations. The committee concluded that fuel economy would not be a good metric for 

judging the fuel efficiency of a heavy-duty vehicle, and stated that NHTSA should 

instead consider fuel consumption as the metric for its standards. As a result, for heavyduty pickup trucks and vans, EPA and NHTSA are finalizing standards on a per-mile 

basis (g/mile for the EPA standards, gallons/100 miles for the NHTSA standards), as 

explained in Section I. C. (2) (b) below. For heavy-duty trucks, both combination and 

vocational, the agencies are adopting standards expressed in terms of the key measure of 

freight movement, tons of payload miles or, more simply, ton-miles. Hence, for EPA the 

final standards are in the form of the mass of emissions from carrying a ton of cargo over 

a distance of one mile (g/ton-mi). Similarly, the final NHTSA standards are in terms of 

gallons of fuel consumed over a set distance (one thousand miles), or gal/1,000 ton-mile. 

Finally, for engines, EPA is adopting standards in the form of grams of emissions per unit 

of work (g/bhp-hr), the same metric used for the heavy-duty highway engine standards 

for criteria pollutants today. Similarly, NHTSA is finalizing standards for heavy-duty 

engines in the form of gallons of fuel consumption per 100 units of work (gal/100 bhphr).

Section II below discusses the final EPA and NHTSA standards in greater detail.

(a) Class 7 and 8 Combination Tractors

Class 7 and 8 combination tractors and their engines contribute the largest portion

of the total GHG emissions and fuel consumption of the heavy-duty sector, 

approximately 65 percent, due to their large payloads, their high annual miles traveled, 

and their major role in national freight transport.25 These vehicles consist of a cab and 

engine (tractor or combination tractor) and a detachable trailer. In general, reducing 

GHG emissions and fuel consumption for these vehicles will involve improvements in 

aerodynamics and tires and reduction in idle operation, as well as engine-based efficiency

improvements. 

In general, the heavy-duty combination tractor industry consists of tractor 

manufacturers (which manufacture the tractor and purchase and install the engine) and 

trailer manufacturers. These manufacturers are usually not the same entity. We are not 

aware of any manufacturer that typically assembles both the finished truck and the trailer 

and introduces the combination into commerce for sale to a buyer. The owners of trucks 

 

25 The on-highway Class 7 and 8 combination tractors constitute the vast majority of this regulatory 

category, and form the backbone of this HD National Program. A small fraction of combination tractors 

are used in off-road applications and are regulated differently, as described in Section II. 
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

24 of 971

and trailers are often distinct as well. A typical truck buyer will purchase only the tractor. 

The trailers are usually purchased and owned by fleets and shippers. This occurs in part 

because trucking fleets on average maintain 3 trailers per tractor and in some cases as 

many as 6 or more trailers per tractor. There are also large differences in the kinds of 

manufacturers involved with producing tractors and trailers. For HD highway tractors 

and their engines, a relatively limited number of manufacturers produce the vast majority

of these products. The trailer manufacturing industry is quite different, and includes a 

large number of companies, many of which are relatively small in size and production 

volume. Setting standards for the products involved -- tractors and trailers -- requires 

recognition of the large differences between these manufacturing industries, which can 

then warrant consideration of different regulatory approaches. 

Based on these industry characteristics, EPA and NHTSA believe that the most 

straightforward regulatory approach for combination tractors and trailers is to establish 

standards for tractors separately from trailers. As discussed below in Section IX, the 

agencies are adopting standards for the tractors and their engines in this rulemaking, but 

did not propose and are not adopting standards for trailers. 

As with the other regulatory categories of heavy-duty vehicles, EPA and NHTSA 

have concluded that achieving reductions in GHG emissions and fuel consumption from 

combination tractors requires addressing both the cab and the engine, and EPA and 

NHTSA each are adopting standards that reflect this conclusion. The importance of the 

cab is that its design determines the amount of power that the engine must produce in 

moving the truck down the road. As illustrated in Figure I-1, the loads that require

additional power from the engine include air resistance (aerodynamics), tire rolling 

resistance, and parasitic losses (including accessory loads and friction in the drivetrain). 

The importance of the engine design is that it determines the basic GHG emissions and 

fuel consumption performance of the engine for the variety of demands placed on the 

engine, regardless of the characteristics of the cab in which it is installed. The agencies 

intend for the final standards to result in the application of improved technologies for 

lower GHG emissions and fuel consumption for both the cab and the engine.
*** E.O. 12866 Review – Revised Version 

Figure 

Accordingly, for Class 7 and 8 combination tractors, the agencies are each 

finalizing two sets of standards. For vehicle

tractor manufacturers are required to 

vehicle standard will typically be determined based on a customized vehicle simulation 

model, called the Greenhouse gas Emissions Model (GEM)

NAS Report recommendations to require compliance testing for combination tractors 

using vehicle simulation rather than chassis dynamometer testing. This compliance 

model was developed by EPA specifically for this final action. It is an accurate and cost

effective alternative to measuring emissions and fuel consumption while operating the 

vehicle on a chassis dynamometer. Instead of using a chassis dynamometer as an indirect 

way to evaluate real-world operation and performance, various characteristics of the 

vehicle are measured and these measurements are used as inputs to the model. These 

characteristics relate to key technologies appropriate for this subcategory of truck 

including aerodynamic features, weight reductions, tire rolling resistance, the presence of 

idle-reducing technology, and vehicle speed limiters. The model also assumes 

a representative typical engine, rather than a vehicle

regulated separately. Using these inputs, the model will be used to quantify the overall 

performance of the vehicle in terms of 

model’s development and design, as well as the sources for inputs, are discussed in detail 

in Section II below and in Chapter 4 of the RIA. 

(i) Final Standards for Class 7 and 8 Combination Tractors and Their Engines

The vehicle standards 

combination tractor manufacturers are based on several key attributes related to GHG 

emissions and fuel consumption that we believe reasonably represent the many 

differences in utility and performance among

depending on GVWR (i.e

 

26 Adapted from Figure 4.1. Class 8 Truck Energy Audit, Technology Roadmap for the 21st Century Truck 

Program: A Government-Indust

Revised Version – Do Not Cite, Quote, or Release During Review ***

25 of 971

Figure I-1: Combination Tractor and Trailer Loads26

Accordingly, for Class 7 and 8 combination tractors, the agencies are each 

finalizing two sets of standards. For vehicle-related emissions and fuel consumption, 

tractor manufacturers are required to meet vehicle-based standards. Compliance with the 

le standard will typically be determined based on a customized vehicle simulation 

model, called the Greenhouse gas Emissions Model (GEM), which is consistent with the 

NAS Report recommendations to require compliance testing for combination tractors 

ehicle simulation rather than chassis dynamometer testing. This compliance 

model was developed by EPA specifically for this final action. It is an accurate and cost

effective alternative to measuring emissions and fuel consumption while operating the 

icle on a chassis dynamometer. Instead of using a chassis dynamometer as an indirect 

world operation and performance, various characteristics of the 

vehicle are measured and these measurements are used as inputs to the model. These 

haracteristics relate to key technologies appropriate for this subcategory of truck 

including aerodynamic features, weight reductions, tire rolling resistance, the presence of 

reducing technology, and vehicle speed limiters. The model also assumes 

a representative typical engine, rather than a vehicle-specific engine, because engines are 

regulated separately. Using these inputs, the model will be used to quantify the overall 

performance of the vehicle in terms of CO2 emissions and fuel consumption. The 

s development and design, as well as the sources for inputs, are discussed in detail 

in Section II below and in Chapter 4 of the RIA. 

Final Standards for Class 7 and 8 Combination Tractors and Their Engines

The vehicle standards that EPA and NHTSA are adopting for Class 7 and 8 

combination tractor manufacturers are based on several key attributes related to GHG 

emissions and fuel consumption that we believe reasonably represent the many 

differences in utility and performance among these vehicles. The final standards differ 

i.e., whether the truck is Class 7 or Class 8), the height of the roof 

 

Class 8 Truck Energy Audit, Technology Roadmap for the 21st Century Truck 

Industry Research Partnership, 21CT-001, December 2000.

Do Not Cite, Quote, or Release During Review ***

Accordingly, for Class 7 and 8 combination tractors, the agencies are each 

related emissions and fuel consumption, 

based standards. Compliance with the 

le standard will typically be determined based on a customized vehicle simulation 

which is consistent with the 

NAS Report recommendations to require compliance testing for combination tractors 

ehicle simulation rather than chassis dynamometer testing. This compliance 

model was developed by EPA specifically for this final action. It is an accurate and costeffective alternative to measuring emissions and fuel consumption while operating the 

icle on a chassis dynamometer. Instead of using a chassis dynamometer as an indirect 

world operation and performance, various characteristics of the 

vehicle are measured and these measurements are used as inputs to the model. These 

haracteristics relate to key technologies appropriate for this subcategory of truck –

including aerodynamic features, weight reductions, tire rolling resistance, the presence of 

reducing technology, and vehicle speed limiters. The model also assumes the use of 

specific engine, because engines are 

regulated separately. Using these inputs, the model will be used to quantify the overall 

nsumption. The 

s development and design, as well as the sources for inputs, are discussed in detail 

Final Standards for Class 7 and 8 Combination Tractors and Their Engines

that EPA and NHTSA are adopting for Class 7 and 8 

combination tractor manufacturers are based on several key attributes related to GHG 

emissions and fuel consumption that we believe reasonably represent the many 

these vehicles. The final standards differ 

., whether the truck is Class 7 or Class 8), the height of the roof 

Class 8 Truck Energy Audit, Technology Roadmap for the 21st Century Truck 
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26 of 971

of the cab, and whether it is a “day cab” or a “sleeper cab.” These later two attributes are 

important because the height of the roof, designed to correspond to the height of the 

trailer, significantly affects air resistance, and a sleeper cab generally corresponds to the 

opportunity for extended duration idle emission and fuel consumption improvements. 

We received a number of comments supporting this approach and no comments that 

provided a compelling reason to change our approach in this final action.

Thus, the agencies have created nine subcategories within the Class 7 and 8 

combination tractor category based on the differences in expected emissions and fuel 

consumption associated with the key attributes of GVWR, cab type, and roof height. The 

agencies are setting standards beginning in 2014 model year with more stringent 

standards following in 2017 model year. Table I-3 presents the agencies’ respective 

standards for combination tractor manufacturers for the 2017 model year. The standards 

represent an overall fuel consumption and CO2 emissions reduction up to 23 percent from 

the tractors and the engines installed in them when compared to a baseline 2010 model 

year tractor and engine without idle shutdown technology. The standard values shown 

below differ somewhat from the proposal, reflecting refinements made to the GEM in 

response to comments. These changes did not impact our estimates of the relative 

effectiveness of the various control technologies modeled in this final action nor the 

overall cost or benefits or cost effectiveness estimated for these final vehicle standards. 

As proposed, the agencies are exempting certain types of tractors which operate 

off-road to be exempt from the combination tractor vehicle standards (although standards 

would still apply to the engines installed in these vehicles). The criteria for tractors to be 

considered off-road have been amended slightly from those proposed, in response to 

public comment. The agencies have also recognized, again in response to public 

comment, that some combination tractors operate in a manner essentially the same as 

vocational vehicles and have created a subcategory of “vocational tractors” as a result. 

Vocational tractors will be subject to the standards for vocational vehicles rather than the 

combination tractor standards. See Section II.B of this preamble.
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Table I-3: Heavy-duty Combination Tractor EPA Emissions Standards (g CO2/ton-mile) and 

NHTSA Fuel Consumption Standards (gal/1,000 ton-mile)

2017 Model Year CO2 Grams per Ton-Mile

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 104 80 66

Mid Roof 115 86 73

High Roof 120 89 72

2017 Model Year Gallons of Fuel per 1,000 Ton-Mile

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 10.2 7.8 6.5

Mid Roof 11.3 8.4 7.2

High Roof 11.8 8.7 7.1

In addition, the agencies are finalizing separate performance standards for the 

engines manufactured for use in these trucks. EPA’s engine-based CO2 standards and 

NHTSA’s engine-based fuel consumption standards are implemented using EPA’s 

existing test procedures and regulatory structure for criteria pollutant emissions from 

medium- and heavy-duty engines. As at proposal, the final engine standards vary

depending on engine size linked to intended vehicle service class. Consistent with our 

proposal, the agencies are finalizing an interim alternative compression ignition engine 

standard for model years 2014-2016. This alternative standard is designed to provide a 

glide path for legacy diesel engine products that may not be able to comply with the final 

engine standards for model years 2014-16 given the short (approximately 2-year) lead 

time of this program. We believe this alternative standard is appropriate for a first-ever 

program when the overall baseline performance of the industry is quite varied and where 

the short lead time means that not every product can be brought into compliance by 2014. 

The alternative standard only applies through and including model year 2016.

Separately, EPA is adopting standards for combination tractors that apply in use. 

EPA is also finalizing engine-based N2O and CH4 standards for manufacturers of the 

engines used in these combination tractors. EPA is finalizing separate engine-based 

standards for N2O and CH4 because the agency believes that emissions of these GHGs are 

technologically related solely to the engine, fuel, and emissions aftertreatment systems, 

and the agency is not aware of any influence of vehicle-based technologies on these 

emissions. NHTSA is not incorporating standards for N2O and CH4 because these 

emissions do not impact fuel consumption in a significant way. The standards that EPA 

is finalizing for N2O and CH4 are less stringent than those we proposed, reflecting new

data provided to EPA in comments on the proposal showing that the current baseline 

level of N2O and CH4 emissions varies more than EPA had expected. EPA expects that 

manufacturers of current engine technologies will be able to comply with the final N2O 

and CH4 “cap” standards with little or no technological improvements; the value of the 

standards will be to prevent significant increases in these emissions as alternative 

technologies are developed and introduced in the future. Compliance with the final EPA 

engine-based CO2 standards and the final NHTSA engine-based fuel consumption 
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standards, as well as the final EPA N2O and CH4 standards, will be determined using the 

appropriate EPA engine test procedure, as discussed in Sections II.B, II.D, and II.E

below. 

As with the other categories of heavy-duty vehicles, EPA and NHTSA are 

finalizing respective standards that will apply to Class 7 and 8 tractors at the time of 

production (as in Table I-3, above). In addition, EPA is finalizing separate standards that 

will apply for a specified period of time in use. All of the standards for these vehicles, as 

well as details about the provisions for certification and implementation of these 

standards, are discussed in more detail in Sections II, III, IV, and V below and in the 

RIA.

(ii) EPA’s Final Air Conditioning Leakage Standard for Class 7 and 8 Combination 

Tractors

In addition to the final EPA tractor- and engine-based standards for CO2 and 

engine-based standards for N2O, and CH4 emissions, EPA is finalizing a separate 

standard to reduce leakage of HFC refrigerant from cabin air conditioning (A/C) systems 

from combination tractors, to apply to the tractor manufacturer. This standard is 

independent of the CO2 tractor standard, as discussed below in Section II.E.5. Because 

the current refrigerant used widely in all these systems has a very high global warming 

potential, EPA is concerned about leakage of refrigerant.27 

Because the interior volume to be cooled for most tractor cabins is similar to that 

of light-duty vehicles, the size and design of current tractor A/C systems is also very 

similar. The compliance approach for Class 7 and 8 tractors is therefore similar to that in 

the light-duty rule in that these standards are design-based. Manufacturers will choose 

technologies from a menu of leak-reducing technologies sufficient to comply with the 

standard, as opposed to using a test to measure performance. 

However, the final heavy-duty A/C provisions differ in two important ways from 

those established in the light-duty rule. First, the light-duty provisions were established 

as voluntary ways to generate credits towards the CO2 g/mi standard, and EPA took into 

account the expected use of such credits in determining the stringency of the CO2

emissions standards. In the HD National Program, EPA is requiring that manufacturers 

actually meet a standard – as opposed to having the opportunity to earn a credit -- for A/C 

refrigerant leakage. Thus, refrigerant leakage control is not separately accounted for in 

the final heavy-duty CO2 standards. We are taking this approach here recognizing that 

while the benefits of leakage control are almost identical between light-duty and heavyduty vehicles on a per vehicle basis, these benefits on a per mile basis expressed as a 

percentage of overall GHG emissions are much smaller for heavy-duty vehicles due to 

their much higher CO2 emissions rates and higher annual mileage when compared to 

light-duty vehicles. Hence a credit-based approach as done for light-duty vehicles would 

provide less motivation for manufacturers to install low leakage systems even though 

 

27 The global warming potential for HFC-134a refrigerant of 1430 used in this program is consistent with 

the Intergovernmental Panel on Climate Change Fourth Assessment Report.
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such systems represent a highly cost effective means to control GHG emissions. The 

second difference relates to the expression of the leakage rate. The light-duty A/C 

leakage standard is expressed in terms of grams per year. For EPA’s heavy-duty

program, however, because of the wide variety of system designs and arrangements, a 

one-size-fits-all gram per year standard would not be appropriate, so EPA is adopting a 

standard in terms of annual mass leakage rate for A/C systems with refrigerant capacities 

less than or equal to 733 grams and percent of total refrigerant leakage per year for A/C 

systems with refrigerant capacities greater than 733 grams. The percent of total 

refrigerant leakage per year requires the total refrigerant capacity of the A/C system to be 

taken into account in determining compliance. EPA believes that this approach -- a 

standard instead of a credit, and basing the standard on percent or mass of leakage over 

time – is more appropriate for heavy-duty tractors than the light-duty vehicle approach 

and that it will achieve the desired reductions in refrigerant leakage. Compliance with 

the standard will be determined through a showing by the tractor manufacturer that its

A/C system incorporates a combination of low-leak technologies sufficient to meet the 

leakage rate of the applicable standard. The “menu” of technologies is very similar to 

that established in the light-duty 2012-2016 MY vehicle rule.28 

Finally, the agencies did not propose and are not adopting an A/C system 

efficiency standard in this heavy-duty rulemaking, although an efficiency credit was a 

part of the light-duty rule. The much larger emissions of CO2 from a heavy-duty tractor 

as compared to those from a light-duty vehicle mean that the relative amount of CO2 that 

could be reduced through A/C efficiency improvements is very small. 

A more detailed discussion of A/C related issues is found in Section II.E.5 of this 

preamble. 

(b) Heavy-Duty Pickup Trucks and Vans (Class 2b and 3)

Heavy-duty vehicles with GVWR between 8,501 and 10,000 lb are classified in 

the industry as Class 2b motor vehicles per the Federal Motor Carrier Safety

Administration definition. As discussed above, Class 2b includes MDPVs that are 

regulated by the agencies under the light-duty vehicle rule, and the agencies are not 

adopting additional requirements for MDPVs in this rulemaking. Heavy-duty vehicles 

with GVWR between 10,001 and 14,000 lb are classified as Class 3 motor vehicles. 

Class 2b and Class 3 heavy-duty vehicles (referred to in these rules as “HD pickups and 

vans”) together emit about 15 percent of today’s GHG emissions from the heavy-duty 

vehicle sector. 

About 90 percent of HD pickups and vans are 3⁄4-ton and 1-ton pickup trucks, 12-

and 15-passenger vans, and large work vans that are sold by vehicle manufacturers as 

complete vehicles, with no secondary manufacturer making substantial modifications 

 

28 EPA has approved an alternative refrigerant, HFO-1234yf, which has a very low GWP, for use in lightduty vehicle mobile A/C systems. The final heavy-duty vehicle A/C leakage standard is designed to 

account for use of an alternative, low-GWP refrigerant. If in the future this refrigerant is approved for 

heavy-duty applications and if it becomes widespread as a substitute for HFC-134a in heavy-duty vehicle 

mobile A/C systems, EPA may propose to revise or eliminate the leakage standard. 
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prior to registration and use. These vehicle manufacturers are companies with major 

light-duty markets in the United States, primarily Ford, General Motors, and Chrysler. 

Furthermore, the technologies available to reduce fuel consumption and GHG emissions 

from this segment are similar to the technologies used on light-duty pickup trucks, 

including both engine efficiency improvements (for gasoline and diesel engines) and 

vehicle efficiency improvements. 

For these reasons, EPA believes it is appropriate to adopt GHG standards for HD 

pickups and vans based on the whole vehicle (including the engine), expressed as grams 

per mile, consistent with the way these vehicles are regulated by EPA today for criteria 

pollutants. NHTSA believes it is appropriate to adopt corresponding gallons per 100 mile 

fuel consumption standards that are likewise based on the whole vehicle. This complete 

vehicle approach being adopted by both agencies for HD pickups and vans is consistent 

with the recommendations of the NAS Committee in their 2010 Report. EPA and 

NHTSA also believe that the structure and many of the detailed provisions of the recently 

finalized light-duty GHG and fuel economy program, which also involves vehicle-based 

standards, are appropriate for the HD pickup and van GHG and fuel consumption 

standards as well, and this is reflected in the standards each agency is finalizing, as 

detailed in Section II.C. These commonalities include a new vehicle fleet average 

standard for each manufacturer in each model year and the determination of these fleet 

average standards based on production volume-weighted targets for each model, with the 

targets varying based on a defined vehicle attribute. Vehicle testing will be conducted on 

chassis dynamometers using the drive cycles from the EPA Federal Test Procedure 

(Light-duty FTP or “city” test) and Highway Fuel Economy Test (HFET or “highway”

test).29

For the light-duty GHG and fuel economy standards, the agencies factored in 

vehicle size by basing the emissions and fuel economy targets on vehicle footprint (the 

wheelbase times the average track width).30 For those standards, passenger cars and light 

trucks with larger footprints are assigned higher GHG and lower fuel economy target 

levels in acknowledgement of their inherent tendency to consume more fuel and emit 

more GHGs per mile. For HD pickups and vans, the agencies believe that setting 

standards based on vehicle attributes is appropriate, but feel that a work-based metric 

serves as a better attribute than the footprint attribute utilized in the light-duty vehicle 

rulemaking. Work-based measures such as payload and towing capability are key among 

the parameters that characterize differences in the design of these vehicles, as well as 

differences in how the vehicles will be utilized. Buyers consider these utility-based 

attributes when purchasing a heavy-duty pickup or van. EPA and NHTSA are therefore 

finalizing standards for HD pickups and vans based on a “work factor” attribute that 

combines their payload and towing capabilities, with an added adjustment for 4-wheel 

drive vehicles. The agencies received a number of comments supporting this approach 

 

29 The Light-duty FTP is a vehicle driving cycle that was originally developed for certifying light-duty

vehicles and subsequently applied to HD chassis testing for criteria pollutants. This contrasts with the 

Heavy-duty FTP, which refers to the transient engine test cycles used for certifying heavy-duty engines 

(with separate cycles specified for diesel and spark-ignition engines).

30 EISA requires CAFE standards for passenger cars and light trucks to be attribute-based; See 49 U.S.C. 

32902(b)(3)(A).
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arguing, as the agencies had, that this approach was an effective way to encourage

technology development and to appropriately reflect the utility of work vehicles while 

setting a consistent metric measure of vehicle performance.

As proposed, the agencies are adopting provisions such that each manufacturer’s 

fleet average standard will be based on production volume-weighting of target standards 

for all vehicles that in turn are based on each vehicle’s work factor. These target 

standards are taken from a set of curves (mathematical functions), presented in Section 

II.C below and in §1037.104. EPA is also phasing in the CO2 standards gradually

starting in the 2014 model year, at 15-20-40-60-100 percent of the model year 2018 

standards stringency level in model years 2014-2015-2016-2017-2018, respectively. The 

phase-in takes the form of a set of target standard curves, with increasing stringency in 

each model year, as detailed in Section II.C. The final EPA standards for 2018 (including 

a separate standard to control air conditioning system leakage) represent an average pervehicle reduction in GHGs of 17 percent for diesel vehicles and 12 percent for gasoline 

vehicles, compared to a common baseline, as described in Sections II.C and III.B of this 

preamble. The rule contains separate standards for diesel and gasoline heavy duty 

pickups and vans for reasons described in Section II.C below. EPA is also finalizing a 

compliance alternative whereby manufacturers can phase in different percentages: 15-20-

67-67-67-100 percent of the model year 2019 standards stringency level in model years 

2014-2015-2016-2017-2018-2019, respectively. This compliance alternative parallels 

and is equivalent to NHTSA’s first alternative described below.

NHTSA is allowing manufacturers to select one of two fuel consumption standard 

alternatives for model years 2016 and later. The first alternative defines individual 

gasoline vehicle and diesel vehicle fuel consumption target curves that will not change 

for model years 2016-2018, and are equivalent to EPA’s 67-67-67-100 percent target 

curves in model years 2016-2017-2018-2019, respectively. The target curves for this 

alternative are presented in Section II.C. The second alternative uses target curves that 

are equivalent to the EPA’s 40-60-100 percent target curves in model years 2016-2017-

2018, respectively. Stringency for the alternatives has been selected to allow a 

manufacturer, through the use of the credit and deficit carry-forward provisions that the 

agencies are also finalizing, to rely on the same product plans to satisfy either of these 

two alternatives, and also EPA requirements. If a manufacturer cannot meet an 

applicable standard in a given model year, it may make up its shortfall by overcomplying 

in a subsequent year, called reconciling a credit deficit. NHTSA is also allowing 

manufacturers to voluntarily opt into the NHTSA HD pickup and van program in model 

years 2014 or 2015. For these model years, NHTSA’s fuel consumption target curves are 

equivalent to EPA’s target curves.

The agencies received a number of comments including from the Senate authors 

and supporters of the Ten-in-Ten Fuel Economy Act suggesting that the standards for 

heavy-duty pickups and vans should be made more stringent for gasoline vehicles and 

that the phase-in timing of the standards should be accelerated to the 2016 model year 

(from 2018). We also received comments arguing that the proposed standards were 

aggressive and could only be met given the phase-in schedules proposed by the agencies. 

In response to these comments, we reviewed again the technology assessments from the 
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2010 NAS report, our own joint light-duty 2012-2016 rulemaking, and information 

provided by the commenters relevant to the stringency of these standards. After 

reviewing all of the information, we continue to conclude that the proposed standards and 

associated phase-in schedules represent technically stringent but reasonable standards 

considering the available lead time and costs to bring the necessary technologies to 

market and our own assessments of the efficacy of the technologies when applied to 

heavy-duty pickup trucks and vans. Further detail on the feasibility of the standards and 

the agencies’ choices among alternative standards is found in Section III.C below.

The Senate authors and supporters of the Ten-in-Ten Fuel Economy Act sent a 

letter to the agencies encouraging the agencies to finalize a fuel economy labeling 

requirement for heavy-duty pickups and vans.31 The agencies recognize that consumer 

information in the form of a fuel efficiency label can be a valuable tool to help achieve 

our goals, and we note that the agencies have just recently finalized a new fuel economy 

label for passenger cars and light trucks. See 76 FR at 39478. That rulemaking effort 

focused solely on modifying an existing label and was a multi-year process with 

significant public input. As we did not propose a consumer label for heavy-duty pickups 

and vans in this action and have not appropriately engaged the public in developing such 

a label, we are not prepared to finalize a consumer-based label in this action. However, 

we do intend to consider this issue as we begin work on the next phase of regulations, as 

we recognize that a consumer label can play an important role in reducing fuel 

consumption and GHG emissions.

The form and stringency of the EPA and NHTSA standards curves are based on a 

set of vehicle, engine, and transmission technologies expected to be used to meet the 

recently established GHG emissions and fuel economy standards for model year 2012-

2016 light-duty vehicles, with full consideration of how these technologies are likely to

perform in heavy-duty vehicle testing and use. All of these technologies are already in 

use or have been announced for upcoming model years in some light-duty vehicle 

models, and some are in use in a portion of HD pickups and vans as well. The 

technologies include:

 advanced 8-speed automatic transmissions

 aerodynamic improvements

 electro-hydraulic power steering

 engine friction reductions

 improved accessories

 low friction lubricants in powertrain components

 lower rolling resistance tires

 lightweighting

 gasoline direct injection

 diesel aftertreatment optimization

 

31 See Docket EPA-HQ-OAR-2010-0162.
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 air conditioning system leakage reduction (for EPA program only)

See Section III.B for a detailed analysis of these and other potential technologies, 

including their feasibility, costs, and effectiveness when employed for reducing fuel 

consumption and CO2 emissions in HD pickups and vans.

A relatively small number of HD pickups and vans are sold by vehicle 

manufacturers as incomplete vehicles, without the primary load-carrying device or 

container attached. We are generally regulating these vehicles as Class 2b through 8 

vocational vehicles but are also allowing manufacturers the option to choose to comply

with heavy-duty pickup or van standards, as described in Section I.C.(2)(c). Although, as 

with vocational vehicles generally, we have little information on baseline aerodynamic 

performance and opportunities for improvement, a sizeable subset of these incomplete 

vehicles, often called cab-chassis vehicles, are sold by the vehicle manufacturers in 

configurations with many of the components that affect GHG emissions and fuel 

consumption identical to those on complete pickup truck or van counterparts — including 

engines, cabs, frames, transmissions, axles, and wheels. We are including provisions that 

will allow manufacturers to include these vehicles, as well as some Class 4 and 5 

vehicles, to be regulated under the chassis-based HD pickup and van program (i.e. subject 

to the standards for HD pickups and vans), rather than the vocational vehicle program. 

These provisions are described in Section V.B(1)(e). 

In addition to the EPA CO2 emission standards and the NHTSA fuel consumption 

standards for HD pickups and vans, EPA is also finalizing standards for two additional 

GHGs, N2O and CH4, as well as standards for air conditioning-related HFC emissions. 

These standards are discussed in more detail in Section II.E. Finally, EPA is finalizing 

standards that will apply to HD pickups and vans in use. All of the standards for these 

HD pickups and vans, as well as details about the provisions for certification and 

implementation of these standards, are discussed in Section II.C.

(c) Class 2b-8 Vocational Vehicles

Class 2b-8 vocational vehicles consist of a wide variety of vehicle types. Some of 

the primary applications for vehicles in this segment include delivery, refuse, utility, 

dump, and cement trucks; transit, shuttle, and school buses; emergency vehicles, motor 

homes,32 tow trucks, among others. These vehicles and their engines contribute 

approximately 20 percent of today’s heavy-duty truck sector GHG emissions. 

Manufacturing of vehicles in this segment of the industry is organized in a more 

complex way than that of the other heavy-duty categories. Class 2b-8 vocational vehicles 

are often built as a chassis with an installed engine and an installed transmission. Both 

the engine and transmissions are typically manufactured by other manufacturers and the 

chassis manufacturer purchases and installs them. Many of the same companies that 

build Class 7 and 8 tractors are also in the Class 2b-8 chassis manufacturing market. The 

chassis is typically then sent to a body manufacturer, which completes the vehicle by

 

32 NHTSA’s final fuel consumption standards will not apply to recreational vehicles, as discussed in earlier 

in this preamble section.
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installing the appropriate feature -- such as dump bed, delivery box, or utility bucket --

onto the chassis. Vehicle body manufacturers tend to be small businesses that specialize 

in specific types of bodies or specialized features. 

EPA and NHTSA proposed that in this vocational vehicle category the proposed 

GHG and fuel consumption standards apply to chassis manufacturers. Chassis 

manufacturers play a central role in the manufacturing process. The product they

produce – the chassis with engine and transmission – includes the primary technologies 

that affect GHG emissions and fuel consumption. They also constitute a much more 

limited group of manufacturers for purposes of developing and implementing a 

regulatory program. The agencies believe that a focus on the body manufacturers would 

be much less practical, since they represent a much more diverse set of manufacturers, 

many of whom are small businesses. Further, the part of the vehicle that they add affords 

very few opportunities to reduce GHG emissions and fuel consumption (given the limited 

role that aerodynamics plays in many types of lower speed and stop-and-go operation 

typically found with vocational vehicles.) Therefore, the agencies proposed that the 

standards in this vocational vehicle category would apply to the chassis manufacturers of 

all heavy-duty vehicles not otherwise covered by the HD pickup and van standards or 

Class 7 and 8 combination tractor standards discussed above. The agencies requested 

comment on the proposed focus on chassis manufacturers.

Volvo commented that the EISA does not speak to the regulation of subsystems, 

such as incomplete vehicles, and argued that on the other hand, Section 32902(k)(2) 

prescribes the regulation of vehicles. Volvo further stated that precedent for the 

regulation of complete vehicles exists in the light-duty fuel economy rule. As noted 

above, NHTSA does not believe that EISA mandates a particular regulatory approach, 

but rather gives the agency wide latitude and explicitly leaves that determination to the 

agency. NHTSA also notes that its heavy-duty rule creates a new fuel efficiency program 

for which the light-duty program does not necessarily serve as a useful precedent for 

considerations of its structure. Unlike the light-duty fuel economy program, MD/HD 

vehicles are produced in widely diverse stages. Further, given the MD/HD market 

structure, where the complete vehicle manufacturers are numerous, diverse, and often 

small businesses, the regulation of complete vehicles would create unique difficulties for 

the application of appropriate and feasible technologies. These same considerations 

justify EPA’s determination, pursuant to CAA section 202 (a), to regulate only chassis 

manufacturers in this first stage of GHG rules for the heavy-duty sector. NHTSA also 

notes that this rule does not represent the first time that the agency has regulated 

incomplete vehicles. Rather, incomplete vehicles have a history of regulation under the 

Federal Motor Vehicle Safety Standards.33 For this first phase of the HD National 

Program, NHTSA and EPA believe that given the complexity of the manufacturing 

process for vocational vehicles, and given the wide range of entities that participate in 

that process, vehicle fuel consumption standards would be most appropriately applied to 

chassis manufacturers and not to body builders. 

 

33 See 49 U.S.C. §§ 567.5 and 568.4
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The agencies continue to believe that regulation of the chassis manufacturers for 

this vocational vehicle category will achieve the maximum feasible improvement in fuel 

efficiency for purposes of EISA and appropriate emissions reductions for purposes of the 

CAA. Therefore, consistent with our proposal the final standards in this vocational 

vehicle category apply to the chassis manufacturers of all heavy-duty vehicles not 

otherwise covered by the HD pickup and van standards or Class 7 and 8 combination 

tractor standards discussed above. As discussed above, EPA and NHTSA have concluded 

that reductions in GHG emissions and fuel consumption require addressing both the 

vehicle and the engine. As discussed above for Class 7 and 8 combination tractors, the 

agencies are each finalizing two sets of standards for Class 2b-8 vocational vehicles. For 

vehicle-related emissions and fuel consumption, the agencies are adopting standards for 

chassis manufacturers: EPA CO2 (g/ton-mile) standards and NHTSA fuel consumption 

(gal/1,000 ton-mile) standards). While the agencies believe that a freight-based metric is 

broadly appropriate for vocational vehicles because the vocational vehicle population is 

dominated by freight trucks and maintain that it is appropriate for the first phase of the 

program, the agencies may consider other metrics for future phases of a HD program. 

Manufacturers will use GEM, the same customized vehicle simulation model used for 

Class 7 and 8 tractors, to determine compliance with the vocational vehicle standards 

finalized in this action. The primary manufacturer-generated input into the GEM for this 

category of trucks will be a measure of tire rolling resistance, as discussed further below, 

because tire improvements are the primary means of vehicle improvement available at 

this time for vocational vehicles. The model also assumes the use of a typical 

representative, compliant engine in the simulation, resulting in an overall value for CO2

emissions and one for fuel consumption. This is done for the same reason as for 

combination tractors. As is the case for combination tractors, the manufacturers of the 

engines intended for vocational vehicles will be subject to separate engine-based 

standards.

(i) Final Standards for Class 2b-8 Vocational Vehicles and their Engines

Based on our analysis and research, the agencies believe that the primary

opportunity for reductions in vocational vehicle GHG emissions and fuel consumption 

will be through improved engine technologies and improved tire rolling resistance. For 

engines, EPA and NHTSA are adopting separate standards for the manufacturers of 

engines used in Class 2b-8 vocational vehicles (the same approach as for combination 

tractors and engines intended for use in those tractors). EPA’s final engine-based CO2

standards and NHTSA’s final engine-based fuel consumption standards vary based on the 

expected weight class and usage of the truck into which the engine will be installed. Tire 

rolling resistance is closely related to the weight of the vehicle. Therefore, we are 

adopting vehicle-based standards for these trucks which vary according to one key

attribute, GVWR. For this initial HD rulemaking, we are adopting standards based on the 

same groupings of truck weight classes used for the engine standards -- light heavy-duty, 

medium heavy-duty, and heavy heavy-duty. These groupings are appropriate for the final 

vehicle-based standards because they parallel the general divisions among key engine 

characteristics, as discussed in Section II.
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The agencies are also finalizing an interim alternative compression ignition 

(diesel) engine standard for model years 2014-2016, again analogous to the alternative 

standards for compression ignition engines use in combination tractors. The need for this 

provision and our considerations in adopting it are the same for the engines used in 

vocational vehicles as for the engines used in combination tractors. As we proposed, 

these alternative standards will only be available through model year 2016. In addition, 

manufacturers that use the interim alternative diesel engine standards for model years 

2014-2016 under the EPA program must use equivalent fuel consumption standards 

under the NHTSA program. 

For the 2014 to 2016 model years, manufacturers may also choose to meet 

alternative engine standards that are phased-in over the model years to coincide with new 

EPA On-Board Diagnostic (OBD) requirements applicable for these same model years. 

See Sections II.B and II.D below.

The agencies received a significant number of comments including from the 

Senate authors and supporters of the Ten-in-Ten Fuel Economy Act arguing that our 

proposed standards for vocational vehicles did not reflect all of the technologies 

identified in the 2010 NAS report. The commenters encouraged the agencies to expand 

the program to bring in additional reductions through the use of new transmission 

technologies, vehicle weight reductions and hybrid drivetrains. In general, the agencies 

agree with the commenters’ central contention that there are additional technologies to 

improve the fuel efficiency of vocational vehicles. As discussed later, we are finalizing 

provisions to allow new technologies to be brought into the program through the 

innovative technology credit program. More specifically, we are including provisions to 

account for and credit the use of hybrid technology as a technology that can reduce 

emissions and fuel consumption. Hybrid technology can currently be a cost-effective 

technology in certain specific vocational applications, and the agencies want to recognize 

and promote the use of this technology. (See Sections I.E and IV below.) However, we 

are not finalizing standards that are premised on the use of these additional technologies 

because we have not been able to develop the test procedures, regulatory mechanisms and 

baseline performance data necessary to adopt a more comprehensive approach to 

controlling fuel efficiency and GHG emissions from vocational vehicles. In concept, the 

agencies would need to know the baseline weight, aerodynamic performance, and 

transmission configuration for the wide range of vocational vehicles produced today. We 

do not have this information even for relatively small portions of this market (e.g. 

concrete mixers) nor are we well informed regarding the potential tradeoffs to changes to 

vehicle utility that might exist for changes to concrete mixer designs in response to a 

regulation. Nor did the commenters provide any such information. Absent this 

information and the necessary regulatory tools, we believe the standards we are finalizing 

for vocational vehicles represent the most appropriate standards for this segment during 

the model years of the first phase of the program. We intend to address fuel consumption 

and GHG emissions from these vehicles in a more comprehensive manner through future 

regulation and look forward to working with all stakeholders on this important segment 

in the future. 
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The agencies are setting standards beginning in the 2014 model year and 

establishing more stringent standards in the 2017 model year. Table I-4 presents EPA’s 

final CO2 standards and NHTSA’s final fuel consumption standards for chassis 

manufacturers of Class 2b through Class 8 vocational vehicles for the 2017 model year. 

The 2017 model year standards represent a 6 to 9 percent reduction in CO2 emissions and 

fuel consumption over a 2010 model year vehicle.

Table I-4: Final 2017 Class 2b-8 Vocational Vehicle EPA CO2 Standards and NHTSA Fuel 

Consumption Standards

EPA CO2 (gram/ton-mile) Standard Effective 2017 Model Year

Light Heavy-Duty 

Class 2b-5

Medium HeavyDuty

Class 6-7

Heavy Heavy-Duty

Class 8

CO2 Emissions 373 225 222

NHTSA Fuel Consumption (gallon per 1,000 ton-mile) Standard Effective 2017 Model 

Year

Light Heavy-Duty 

Class 2b-5

Medium HeavyDuty

Class 6-7

Heavy Heavy-Duty

Class 8

Fuel Consumption 36.7 22.1 21.8

 As mentioned above for Class 7 and 8 combination tractors, EPA believes that 

N2O and CH4 emissions are technologically related solely to the engine, fuel, and 

emissions aftertreatment systems, and the agency is not aware of any influence of 

vehicle-based technologies on these emissions. Therefore, for Class 2b-8 vocational 

vehicles, EPA’s final N2O and CH4 standards cover manufacturers of the engines to be 

used in vocational vehicles. EPA did not propose, nor are we adopting separate vehiclebased standards for these GHGs. As for the engines used in Class 7 and 8 tractors, we are 

finalizing a somewhat higher N2O and CH4 emission standards reflecting new data 

submitted to the agencies during the public comment period. EPA expects that 

manufacturers of current engine technologies will be able to comply with the final “cap” 

standards with little or no technological improvements; the value of the standards is that 

they will prevent significant increases in these emissions as alternative technologies are 

developed and introduced in the future. Compliance with the final EPA engine-based 

CO2 standards and the final NHTSA fuel consumption standards, as well as the final EPA 

N2O and CH4 standards, will be determined using the appropriate EPA engine test 

procedure, as discussed in Section II below. 

As with the other regulatory categories of heavy-duty vehicles, EPA and NHTSA 

are adopting standards that apply to Class 2b-8 vocational vehicles at the time of 

production, and EPA is adopting standards for a specified period of time in use. All of 

the standards for these trucks, as well as details about the final provisions for certification 

and implementation of these standards, are discussed in more detail later in this notice 

and in the RIA.
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EPA did not propose, nor is it adopting A/C refrigerant leakage standards for 

Class 2b-8 vocational vehicles, primarily because of the number of entities involved in 

their manufacture and thus the potential for different entities besides the chassis 

manufacturer to be involved in the A/C system production and installation. 

(d) What Manufacturers Are Not Covered by the Final Standards?

The NPRM proposed to defer temporarily greenhouse gas emissions and fuel 

consumption standards for any manufacturers of heavy-duty engines, manufacturers of 

combination tractors, and chassis manufacturers for vocational vehicles that meet the 

“small business” size criteria set by the Small Business Administration (SBA). 13 CFR 

121.201 defines a small business by the maximum number of employees; for example, 

this is currently 1,000 for heavy-duty vehicle manufacturing and 750 for engine 

manufacturing.34 The agencies stated that they would instead consider appropriate GHG 

and fuel consumption standards for these entities as part of a future regulatory action. 

This includes both U.S.-based and foreign small-volume heavy-duty manufacturers. To 

ensure that the agencies are aware of which companies would be exempt, the agencies 

proposed to require that such entities submit a declaration describing how it qualifies as a 

small entity under the provisions of 13 CFR 121.201 to EPA and NHTSA as prescribed 

in Section V below.

EPA and NHTSA were not aware of any manufacturers of HD pickups and vans 

that meet these criteria. For each of the other categories and for engines, the agencies 

identified a small number of manufacturers that would appear to qualify as small 

businesses under the SBA size criterion, which were estimated to comprise a negligible 

percentage of the U.S. market.35 Therefore, the agencies believed that deferring the 

standards for these companies at this time would have a negligible impact on the GHG 

emission reductions and fuel consumption reductions that the program would otherwise 

achieve. The agencies proposed to consider appropriate GHG emissions and fuel 

consumption standards for these entities as part of a future regulatory action.

The Institute for Policy Integrity (IPI) commented that the small business 

exemption proposed in the NPRM was based on the improper framework of whether the 

exemption would have a negligible impact, and did not adequately explain why the 

regulation of small businesses would face special compliance and administrative burdens. 

IPI argued that the only proper basis for this exemption would be if the agencies could 

explain how these burdens create costs that exceeded the benefits of regulation. 

NHTSA believes that developing standards that are “appropriate, cost-effective, 

and technologically feasible” under 49 U.S.C. 32902(k)(2) includes the authority to 

exclude certain manufacturers if their inclusion would work against these statutory

 

34 See §1036.150 and §1037.150 

35 Two heavy-duty combination tractor and ten chassis manufacturers each comprising less than 0.5 percent 

of the total tractor and vocational market based on Polk Registration Data from 2003 through 2007, and 

three engine manufacturing entities based on company information included in Hoover’s, comprising less 

than 0.1 percent of the total heavy-duty engine sales in the United States based on 2009 and 2010 EPA 

certification information.
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factors. Similarly, under section 202 (a) of the CAA, EPA may reasonably choose to 

defer regulation of industry segments based on considerations of cost, cost-effectiveness 

and available lead time for standards. As noted above, small businesses make up a very

small percentage of the market and are estimated to have a negligible impact on the 

emissions and fuel consumption goals of this program. The short lead time before the 

CO2 standards take effect, the extremely small fuel savings and emissions contribution of 

these entities, and the potential need to develop a program that would be structured 

differently for them (which would require more time to determine and adopt), all led to 

the decision that the inclusion of small businesses would not be appropriate at this time. 

Therefore, the final rule exempts small businesses as proposed. 

Volvo and EMA stated that by exempting small businesses based on the definition 

from SBA, the rules would create a competitive advantage for small businesses over 

larger entities. EMA commented that the exemption should not apply to market segments 

where a small business has a significant share of a particular HD market. Volvo argued 

that the exempted businesses could expand their product offerings or sell vehicles on 

behalf of larger entities, thereby inappropriately increasing the scope of the exclusion. 

The agencies anticipate that the gain a manufacturer might achieve by restructuring its 

practices and products to circumvent the standard (which for vocational vehicles simply

means installing low rolling resistance tires) in the first few years of this program will be 

outweighed by the costs, particularly as small businesses anticipate their potential 

inclusion in the next rulemaking. 

Volvo also commented that the agencies should elaborate on the requirements for 

the exemption in greater detail. The agencies agree that this may help to clarify the 

process. As suggested by Volvo, the agencies will consider affiliations to other 

companies and evidence of spin-offs for the purpose of circumventing the standards in 

determining whether a business qualifies as a small entity for this exclusion. Each 

declaration must be submitted in writing to EPA and NHTSA as prescribed in Section V 

below. As the agencies gain more experience with this exemption, these clarifications 

may be codified in the regulatory text of a future rulemaking.

Volvo further commented that the agencies were adopting an exemption of “small 

businesses” in order to avoid doing a Small Business Regulatory Enforcement Fairness 

Act (SBREFA) and Regulatory Flexibility Act (RFA) analysis. The agencies would like 

to reiterate that they have decided not to include small businesses at this time due to the 

factors described above. The discussion on an RFA analysis is laid out in Section XII(4). 

The agencies continue to believe that deferring the standards for these companies 

at this time will have a negligible impact on the GHG emission reductions and fuel 

consumption reductions that the program would otherwise achieve. Therefore, the final 

rules include the small business exemption as proposed. The specific deferral provisions 

are discussed more detail in Section II.

The agencies will consider appropriate GHG emissions and fuel consumption 

standards for these entities as part of a future regulatory action. 
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(e) Light-duty Vehicle CH4 and N2O Standards Flexibility 

After finalization of the N2O and CH4 standards for light-duty vehicles as part of 

the 2012-2016 MY program, some manufacturers raised concerns that they may have 

difficulty meeting those standards across their light-duty vehicle fleets. In response to 

these concerns, as part of the same Federal Register notice as the heavy-duty proposal, 

EPA requested comments on additional options for manufacturers to comply with lightduty vehicle N2O and CH4 standards to provide additional near-term flexibility. 

Commenters providing comment on this issue supported additional flexibility for 

manufacturers. EPA is finalizing provisions allowing manufacturers to use CO2 credits, 

on a CO2-equivalent basis, to meet the N2O and CH4 standards, which is consistent with 

many commenters’ preferred approach. Manufacturers will have the option of using CO2

credits to meet N2O and CH4 standards on a test group basis as needed for MYs 2012-

2016.

(f) Alternative Fuel Engines and Vehicles

The agencies believe that it is also appropriate to take steps to recognize the 

benefits of flexible-fueled vehicles (FFVs) and dedicated alternative-fueled vehicles. In 

the NPRM, EPA proposed to determine the emissions performance of dedicated 

alternative fuel engines and pickup trucks and vans by measuring tailpipe CO2 emissions. 

NHTSA proposed to determine fuel consumption performance of non-electric dedicated 

alternative fuel engines and pickup trucks and vans by measuring fuel consumption with 

the alternative fuel and then calculating a petroleum equivalent fuel consumption using a 

Petroleum Equivalency Factor (PEF) that is determined by the Department of Energy. 

NHTSA proposed to treat electric vehicles as having zero fuel consumption, comparable 

to the EPA proposal. Both agencies proposed to determine FFV performance in the same 

way as for GHG emissions for light-duty vehicles, with a 50-50 weighting of alternative 

and conventional fuel test results through MY 2015, and a weighting based on 

demonstrated fuel use in the real world after MY 2015 (defaulting to an assumption of 

100 percent conventional fuel use). This approach was considered to be a reasonable and 

logical way to properly credit alternative fuel use in FFVs in the real world without 

imposing a difficult burden of proof on manufacturers. However, unlike in the light-duty 

rule, the agencies do not believe it is appropriate to create a provision for additional 

incentives similar to the 2012-2015 light-duty incentive program (See 49 U.S.C. 32904) 

because the HD sector does not have the incentives mandated in EISA for light-duty 

FFVs, and so has not relied on the existence of such credits in devising compliance 

strategies for the early model years of this program. See 74 FR at 49531. In fact, 

manufacturers have not in the past produced FFV heavy-duty vehicles. On the other 

hand, the agencies sought comment on how to properly recognize the impact of the use of 

alternative fuels, and E85 in particular, in HD pickups and vans, including the proper 

accounting for alternative fuel use in FFVs in the real world.36 See 75 FR at 74198. 

The agencies received several comments from natural gas vehicle (NGV) interests 

arguing for greater crediting of NGVs than the proposed approach would have provided. 

 

36 E85 is a blended fuel consisting of nominally 15 percent gasoline and 85 percent ethanol.
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Clean Energy, Hayday Farms, Border Valley, AGA, Ryder, Encana, and a group of NGV 

interests commented that the NPRM ignored Congress’ intent to incentivize the use of 

NGVs by not including the conversion factor that exists in the light-duty statutory

language. The commenters argued that Congress’ intent to incentivize NGVs is evident 

in the formula contained in 49 U.S.C. 32905, which deems a gallon equivalent of gaseous 

fuel to have a fuel content of 0.15 gallon of fuel. The commenters also argued that 

Congress implicitly intended NGVs to be incentivized in this rulemaking, as evidenced 

by the incentives in the light-duty statutory text. AGA and Hayday suggested that the 

agencies were not including the NGV incentive from light-duty because Congress did not 

explicitly include it in 49 U.S.C. 32902(k), and argued that this would contradict the 

agencies’ inclusion of other incentives similar to the light-duty rule. 

The American Trucking Association expressed support for estimating natural gas 

fuel efficiency by using carbon emissions from natural gas rather than energy content to 

estimate fuel consumption. ATA explained that two vehicles can achieve the same fuel 

efficiency, yet one operated on natural gas would have a lower carbon dioxide emissions 

rate. A natural gas conversion factor that uses carbon content versus energy content is a 

more appropriate method for calculating fuel consumption, in the commenter’s view. A

number of other groups commented on the appropriate method to use in establishing fuel 

consumption from alternative fueled vehicles. A group of NGV interests, Ryder, Border 

Valley Trading, Waste Management, Robert Bosch and the Blue Green Alliance 

encouraged the agencies to adopt the 0.15 conversion factor in estimating fuel 

consumption for FFVs and alternative fuel vehicles finalized in the light-duty 2012-2016

MY vehicle standards. The suggested incentive would effectively reduce the calculated 

fuel consumption for FFVs and alternative fuel vehicles by a factor of 85 percent. The 

commenters argued that the incentive is needed for heavy-duty vehicles to encourage the 

use of natural gas and to reduce the nation’s dependence on petroleum. 

The agencies reassessed the options for evaluating the CO2 and fuel consumption 

performance of alternative fuel vehicles in response to comments and because the 

agencies recognized that the treatment of alternate fuel vehicles was one of the few 

provisions in the proposal where the EPA and NHTSA programs were not aligned. The 

agencies conducted an analysis comparing fuel consumption calculated based on CO2

emissions37 to fuel consumption calculated based on gasoline or diesel energy 

equivalency to evaluate impacts of a consistent consumption measurement for all vehicle 

classes covered by this program and to further understand how alternative fuels would be 

impacted by this measurement methodology. In particular the agencies evaluated how 

measuring consumption via CO2 emissions would hinder or benefit the application of 

alternative fuels versus following similar alternative fuel incentivizing programs provided 

via statute for the Agency’s light-duty programs. The analysis showed measuring a 

vehicle’s CO2 output converted to fuel consumption provided a fuel consumption 

measurement benefit to those vehicles operating on fuels other than gasoline or diesel. 

For CNG, LNG and LPG the benefit is approximately 19 percent to 24 percent, for 

 

37 Fuel consumption calculated from measured CO2 using conversion factors of 8,887 g CO2/gallon for 

gasoline (for alternative fuel engines that are derived from gasoline engines), and 10,180 g CO2/gallon for 

diesel fuel (for alternative fuel engines that are derived from diesel engines).
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biodiesel and ethanol blends the benefit is approximately 1 percent to 3 percent, and for 

electricity and hydrogen fuels the benefit is 100 percent benefit, as fuel consumption is 

zero. The agencies also considered that the EPA Renewable Fuel Standard,38 a separate 

program, requires an increase in the volume of renewable fuels used in the U.S. 

transportation sector. For the fuels covered by the Renewable Fuels Standard additional 

incentives are not needed in this regulation given the large volume increases required 

under the Renewable Fuel Standard.

The agencies continue to believe that alternative-fueled vehicles, including 

NGVs, provide fuel consumption benefits that should be, and are, accounted for in this 

program. However, the agencies do not agree with the commenters’ claim that the NGV

incentive contained in EISA, and reflected in the light-duty program, is an explicit 

Congressional directive that must also be applied to the heavy-duty program, nor that the 

light-duty incentive for NGVs should be interpreted as an implicit Congressional 

directive for NGVs to be comparably incentivized in the heavy-duty program. Further, 

the agencies believe that the fuel consumption benefits that alternative fuel vehicles

would obtain through measuring CO2 emissions for the EPA program and converting 

CO2 emissions to fuel consumption for the NHTSA program accurately reflects their 

energy benefits. This accurate accounting, in conjunction with the volumetric increases 

required by the Renewable Fuels Standard, provides sufficient incentives for these 

vehicles. The agencies continue to believe that the light-duty conversion factor is not 

appropriate for this program. Instead, the agencies are finalizing measuring the 

performance of alternative fueled vehicles by measuring CO2 emissions for the EPA 

program and converting CO2 emissions to fuel consumption for the NHTSA program. 

The agencies are also finalizing measuring FFV performance with a 50-50 weighting of 

alternative and conventional fuel test results through MY 2015, and an agency- or 

manufacturer-determined weighting based on demonstrated fuel use in the real world 

after MY 2015 (defaulting to an assumption of 100 percent conventional fuel use). 

The agencies believe this structure accurately reflects the fuel consumption of the 

vehicles while at the same time providing an incentive for the alternative fuel use. (For 

example, natural gas heavy duty engines perform 20 to 30 percent better than their diesel 

and gasoline counterparts from a CO2 perspective, and so meet the standards adopted in 

these rules without cost, and indeed will be credit generators without cost.) We believe 

this is a substantial enough advantage to spur the market for these vehicles. The 

calculation at the same time does not overestimate the benefit from these technologies, 

which could reduce the effectiveness of the regulation. Therefore, the final rules do not 

include the light-duty 0.15 conversion factor for NGVs. The agencies would like to 

clarify that the decision not to include an NGV incentive was based on this policy

determination, not on a belief that incentives present in the light-duty rule could not be 

developed for the heavy-duty sector because they were not explicitly included in Section 

32902(k).

 

38 EPA is responsible for developing and implementing regulations to ensure that transportation fuel sold in 

the United States contains a minimum volume of renewable fuel. The RFS program was created under the 

Energy Policy Act (EPAct) of 2005, and expanded under the Energy Independence and Security Act 

(EISA) of 2007. 
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NHTSA recognizes that EPCA/EISA promotes incentives for alternative fueled 

vehicles for different purposes than does the CAA, and that there may be additional 

energy and national security benefits that could be achieved through increasing fleet 

percentages of natural gas and other alternative-fueled vehicles. More alternative-fueled 

vehicles on road would arguably displace petroleum-fueled vehicles, and thereby increase 

both U.S. energy and national security by reducing the nation’s dependence on foreign 

oil. 

However, a rule that adopts identical incentive provisions reduces industry 

reporting burdens and NHTSA’s monitoring burden. In addition, the agencies are 

concerned that providing greater incentives under EPCA/EISA might lead to little 

increased production of alternative fueled vehicles. If this were the case, then the 

benefits of harmonization could outweigh any potential gains from providing greater 

incentives. It is also consistent with Executive Order 13563.

39

Adopting the same incentive provisions could also have benefits for the public, 

the regulated industries, and the agencies. This approach allows manufacturers to project

clear benefits for the application of GHG-reduction and fuel efficiency technologies, thus

spurring their adoption.

This combined rulemaking by EPA and NHTSA is designed to regulate two 

separate characteristics of heavy duty vehicles: greenhouse gas emissions (GHG) and 

fuel consumption. In the case of diesel or gasoline powered vehicles, there is a one-toone relationship between these two characteristics. Each gallon of gasoline combusted 

by a truck engine generates approximately 8,887 grams of CO2; and each gallon of diesel 

fuel burned generates about 10,180 grams of CO2. Because no available technologies 

reduce tailpipe CO2 emissions per gallon of fuel combusted, any rule that limits tailpipe 

CO2 emissions is effectively identical to a rule that limits fuel consumption. Compliance 

by a truck manufacturer with the NHTSA fuel economy rule assures compliance with the 

EPA rule, and vice versa.

For alternatively fueled vehicles, which use no petroleum, the situation is 

different. For example, a natural gas vehicle that achieves approximately the same fuel 

economy as a diesel powered vehicle would emit 20 percent less CO2; and a natural gas 

vehicle with the same fuel economy as a gasoline vehicle would emit 30 percent less 

CO2. Yet natural gas vehicles consume no petroleum. To the extent that the goal of the 

NHTSA fuel economy portion of this rulemaking is to curb petroleum use, crediting 

natural gas vehicles with zero fuel consumption per mile could contribute to achieving 

that goal. Similar differences between oil consumption and greenhouse gas emissions 

would apply to electric vehicles, hybrid electric vehicles, and biofuel-powered vehicles.

 

39 EO 13563 states that an agency shall “tailor its regulations to impose the least burden on society, 

consistent with obtaining regulatory objectives, taking into account, among other things, and to the 

extent practicable, the costs of cumulative regulations,” and “promote such coordination, 

simplification, and harmonization” as will reduce redundancy, inconsistency, and costs of multiple 

regulatory requirements.
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NHTSA notes that the purpose of EPCA/EISA is not merely to curb petroleum 

use – it is more generally to secure energy independence, which can be achieved by

reducing petroleum use. The value of incentivizing natural gas, electric vehicles, 

biofuels, hydrogen, or other alt fuel vehicles for energy independence is limited to the 

extent that the alternative fuels may be imported. In the recent rulemaking for light-duty 

vehicles, EPA and NHTSA have followed the light duty specific statutory provision that 

treats one gallon of alternative fuel as equivalent to 0.15 gallons of gasoline until MY 

2016, when performance on the EPA CO2 standards is measured based on actual 

emissions. 75 FR at 25433. Following that MY 2012-2015 approach in this heavy duty 

program would mean that, for example, a natural gas powered truck would have 

attributed to it 20 percent less CO2 emissions than a comparable diesel powered truck, but 

85 percent less fuel consumption. Engine manufacturers with a relatively large share of 

alternative-fuel products would likely have an easier time complying with NHTSA’s 

average fuel economy standard than with EPA’s GHG standard. Similarly, engine 

manufacturers with a relatively small share of alternative-fuel products would have a 

relatively easier time complying with EPA’s CO2 standard than with NHTSA’s fuel 

economy standard. In that way, the rule would not differ from the light duty vehicle 

rules.

Instead, in this program, EPA and NHTSA are establishing identical rules. Fuel 

consumption for alternatively-powered vehicles will be calculated according to their 

tailpipe CO2 emissions. In that way, there will be a one-to-one relationship between fuel 

economy and tailpipe CO2 emissions for all vehicles. However, this might not result in a 

one-to-one relationship between petroleum consumption and GHG emissions for all 

vehicles. On the other hand, it could have the disadvantage of not doing more to 

encourage some cost-effective means of reducing petroleum consumption by trucks, and 

the accompanying energy security costs. By attributing to natural gas engines only 20 

percent less fuel consumption than comparable diesel engines, because they emit 20 

percent less CO2, rather than attributing to them a much larger percentage reduction in 

fuel consumption, because they use no petroleum, this uniform approach to rulemaking 

provides less of an incentive for technologies that reduce consumption of petroleumbased fuels.

In the future, the Agencies will consider the possibility of proposing standards in 

a way that more fully reflects differences in fuel consumption and greenhouse gas 

emissions. Under such standards, any given vehicle might “over-comply” with the fuel 

economy standard, but might “under-comply” with the greenhouse gas standard.

Therefore, in meeting the fleet-wide requirements, a manufacturer would need to meet 

both standards using all available options, such as credit trading and technology mix.

Allowing for two distinct standards might enable manufacturers to achieve the twin goals 

of reducing greenhouse gas emissions and decreasing consumption of petroleum-based 

fuels in a more cost-effective manner.

D. Summary of Costs and Benefits of the HD National Program

This section summarizes the projected costs and benefits of the final NHTSA fuel 

consumption and EPA GHG emissions standards. These projections helped to inform the 
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agencies’ choices among the alternatives considered and provide further confirmation 

that the final standards are an appropriate choice within the spectrum of choices 

allowable under the agencies’ respective statutory criteria. NHTSA and EPA have used 

common projected costs and benefits as the bases for our respective standards.

The agencies have analyzed in detail the projected costs, fuel savings, and 

benefits of the final GHG and fuel consumption standards. Table I-5 shows estimated 

lifetime discounted program costs (including technological outlays), fuel savings, and

benefits for all heavy-duty vehicles projected to be sold in model years 2014-2018 over 

these vehicles’ lives. The benefits include impacts such as climate-related economic 

benefits from reducing emissions of CO2 (but not other GHGs) and reductions in energy

security externalities caused by U.S. petroleum consumption and imports. The analysis 

also includes economic impacts stemming from additional heavy-duty vehicle use

attributable to fuel savings, such as the economic damages caused by accidents, 

congestion and noise. Note that benefits reflect on estimated values for the social cost of 

carbon (SCC), as described in Section VIII.G.

The costs, fuel savings, and benefits summarized here are slightly higher than at 

proposal, reflecting the use of 2009 (versus 2008) dollars, some minor changes to our 

cost estimates in response to comments, and a change to the 2011 Annual Energy

Outlook (AEO) estimate of economic growth and future fuel prices. In aggregate, these 

changes lead to an increased estimate of the net benefits of the final action compared to 

the proposal.
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Table I-5: Estimated Lifetime Discounted Costs, Fuel Savings, Benefits, and Net Benefits

for 2014-2018 Model Year Heavy-Duty Vehicles a,b (Billions, 2009$)

Lifetime Present Valuec– 3% Discount Rate

Program Costs $8.1

Fuel Savings $50

Benefits $7.3

Net Benefitsd$49

Annualized Valuee– 3% Discount Rate

Annualized Costs $0.4

Fuel Savings $2.2

Annualized Benefits $0.4

Net Benefitsd$2.2

Lifetime Present Valuec- 7% Discount Rate

Program Costs $8.1

Fuel Savings $34

Benefits $6.7

Net Benefitsd$33

Annualized Valuee– 7% Discount Rate

Annualized Costs $0.6

Fuel Savings $2.6

Annualized Benefits $0.5

Net Benefitsd$2.5

Notes:

a The agencies estimated the benefits associated with four different values of a one ton 

CO2 reduction (model average at 2.5% discount rate, 3%, and 5%; 95th percentile at 3%), 

which each increase over time. For the purposes of this overview presentation of 

estimated costs and benefits, however, we are showing the benefits associated with the 

marginal value deemed to be central by the interagency working group on this topic: the 

model average at 3% discount rate, in 2009 dollars. Section VIII.F provides a complete 

list of values for the 4 estimates.

b Note that net present value of reduced GHG emissions is calculated differently than

other benefits. The same discount rate used to discount the value of damages from future 

emissions (SCC at 5, 3, and 2.5 percent) is used to calculate net present value of SCC for 

internal consistency. Refer to Section VIII.F for more detail.

c

Present value is the total, aggregated amount that a series of monetized costs or benefits 

that occur over time is worth now (in year 2009 dollar terms), discounting future values 

to the present.

d Net benefits reflect the fuel savings plus benefits minus costs.

e The annualized value is the constant annual value through a given time period (2012 

through 2050 in this analysis) whose summed present value equals the present value from 

which it was derived.

Table I-6 shows the estimated lifetime reductions in CO2 emissions (in million 

metric tons (MMT)) and fuel consumption for all heavy-duty vehicles sold in the model 

years 2014-2018. The values in Table I-6 are projected lifetime totals for each model 

year and are not discounted. The two agencies’ standards together comprise the HD 

National Program, and the agencies’ respective GHG emissions and fuel consumption 

standards, jointly, are the source of the benefits and costs of the HD National Program. 
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Table I-6: Estimated Lifetime Reductions in Fuel Consumption and CO2 Emissions for 2014-2018 

Model Year HD Vehicles

All Heavy-Duty 

Vehicles

2014 MY 2015 

MY

2016 

MY

2017 

MY

2018 MY Total

Fuel (billion gallons) 4.0 3.6 3.6 5.1 5.8 22.1

Fuel (billion barrels) 0.10 0.09 0.08 0.12 0.14 0.53

CO2 (MMT)a50.2 44.8 44.0 62.8 71.7 273

Note: aIncludes upstream and downstream CO2 reductions.

Table I-7 shows the estimated lifetime discounted benefits for all heavy-duty

vehicles sold in model years 2014-2018. Although the agencies estimated the benefits 

associated with four different values of a one ton CO2 reduction ($5, $22, $36, $66), for 

the purposes of this overview presentation of estimated benefits the agencies are showing

the benefits associated with one of these marginal values, $22 per ton of CO2, in 2009

dollars and 2010 emissions. Table I-7 presents benefits based on the $22 per ton of CO2

value. Section VIII.F presents the four marginal values used to estimate monetized 

benefits of CO2 reductions and Section VIII presents the program benefits using each of 

the four marginal values, which represent only a partial accounting of total benefits due 

to omitted climate change impacts and other factors that are not readily monetized. The 

values in the table are discounted values for each model year of vehicles throughout their 

projected lifetimes. The analysis includes other economic impacts such as energy

security, and other externalities such as impacts on accidents, congestion and noise. 

However, the model year lifetime analysis supporting the program omits other impacts 

such as benefits related to non-GHG emission reductions.40 The lifetime discounted 

benefits are shown for one of four different SCC values considered by EPA and NHTSA. 

The values in Table I-7 do not include costs associated with new technology required to 

meet the GHG and fuel consumption standards.

Table I-7: Estimated Lifetime Discounted Benefits for 2014-2018 Model Year HD Vehicles Assuming 

the Model Average, 3% Discount Rate SCC Valuea,b,c (billions of 2009 dollars)

Discount Rate Model Year

2014 2015 2016 2017 2018 Total

3% $10.7 $9.4 $9.2 $13.2 $14.9 $57

7% $8.3 $6.9 $6.6 $9.2 $10.1 $41

Notes:

a The analysis includes impacts such as the economic value of reduced fuel consumption and 

accompanying climate-related economic benefits from reducing emissions of CO2 (but not other 

GHGs), and reductions in energy security externalities caused by U.S. petroleum consumption and 

imports. The analysis also includes economic impacts stemming from additional heavy-duty vehicle 

use, such as the economic damages caused by accidents, congestion and noise.

b Note that net present value of reduced CO2 emissions is calculated differently than other benefits. 

The same discount rate used to discount the value of damages from future emissions (SCC at 5, 3, 

and 2.5 percent) is used to calculate net present value of SCC for internal consistency. Refer to 

Section VIII.F for more detail, including a list of all four SCC values, which increase over time.

 

40 Non-GHG emissions and health-related impacts were estimated for the calendar year analysis. See

Section VII for more information about non-GHG emission impacts and Section VIII for more information 

about non-GHG-related health impacts.
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c Benefits in this table include fuel savings.

Table I-8 shows the agencies’ estimated lifetime fuel savings, lifetime CO2

emission reductions, and the monetized net present values of those fuel savings and CO2

emission reductions. The gallons of fuel and CO2 emission reductions are projected 

lifetime values for all vehicles sold in the model years 2014-2018. The estimated fuel 

savings in billions of barrels and the GHG reductions in million metric tons of CO2

shown in Table I-8 are totals for the five model years throughout their projected lifetime 

and are not discounted. The monetized values shown in Table I-8 are the summed values 

of the discounted monetized-fuel consumption and monetized-CO2 reductions for the five 

model years 2014-2018 throughout their lifetimes. The monetized values in Table I-8

reflect both a 3 percent and a 7 percent discount rate as noted.

Table I-8: Estimated Lifetime Reductions and Associated Discounted Monetized Benefits for 2014-

2018 Model Year HD Vehicles (monetized values in 2009 dollars)

Amount $ value (billions)

Fuel Consumption Reductions 0.53 billion 

barrels

$50.1, 3% discount 

rate $34.4, 7% 

discount rate

CO2 Emission Reductionsa

Valued assuming $22/ton CO2 in 2010

273 MMT CO2 $5.8b

Notes:

a

Includes both upstream and downstream CO2 emission reductions.

b Note that net present value of reduced CO2 emissions is calculated differently than other benefits. The 

same discount rate used to discount the value of damages from future emissions (SCC at 5, 3, and 2.5 

percent) is used to calculate net present value of SCC for internal consistency. Refer to Section VIII.F 

for more detail. 

Table I-9 shows the estimated incremental and total technology outlays for all 

heavy-duty vehicles for each of the model years 2014-2018. The technology outlays 

shown in Table I-9 are for the industry as a whole and do not account for fuel savings 

associated with the program.

Table I-9: Estimated Incremental Technology Outlays for 2014-2018 Model Year HD Vehicles

(billions of 2009 dollars)

2014

MY

2015

MY

2016

MY

2017

MY

2018

MY

Total

All HeavyDuty Vehicles

$1.6 $1.4 $1.5 $1.6 $2.0 $8.1

Table I-10 shows the agencies’ estimated incremental cost increase of the average 

new heavy-duty vehicle for each model year 2014-2018. The values shown are 

incremental to a baseline vehicle and are not cumulative. 
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Table I-10: Estimated Incremental Increase in Average Cost for 2014-2018 Model Year HD Vehicles

(2009 dollars per unit)

2014

MY

2015

MY

2016

MY

2017

MY

2018 MY

Combination Tractors $6,019 $5,871 $5,677 $6,413 $6,215

HD Pickups &Vans $165 $215 $422 $631 $1,048

Vocational Vehicles $329 $320 $397 $387 $378

Both costs and benefits presented in this section are in comparison to a reference 

case with no improvements in fuel consumption or greenhouse gas emissions in model 

years 2014 to 2018. 

E. Program Flexibilities

For each of the heavy-duty vehicle and heavy-duty engine categories for which 

we are adopting respective standards, EPA and NHTSA are also finalizing provisions 

designed to give manufacturers a degree of flexibility in complying with the standards. 

These final provisions have enabled the agencies to consider overall standards that are 

more stringent and that will become effective sooner than we could consider with a more 

rigid program, one in which all of a manufacturer’s similar vehicles or engines would be 

required to achieve the same emissions or fuel consumption levels, and at the same time.

41

 We believe that incorporating carefully structured regulatory flexibility provisions into 

the overall program is an important way to achieve each agency’s goals for the program. 

NHTSA’s and EPA’s flexibility provisions are essentially identical in structure 

and function. Within combination tractor and vocational vehicle categories and within

heavy-duty engines, we are finalizing four primary types of flexibility: averaging, 

banking, and trading (ABT) provisions; early credits; advanced technology credits 

(including hybrid powertrains); and innovative technology credit provisions. The final 

ABT provisions are patterned on existing EPA and NHTSA ABT programs and will 

allow a vehicle manufacturer to reduce CO2 emission and fuel consumption levels further 

than the level of the standard for one or more vehicles to generate ABT credits. The 

manufacturer can use those credits to offset higher emission or fuel consumption levels in 

the same averaging set, “bank” the credits for later use, or “trade” the credits to another 

manufacturer. For HD pickups and vans, we are finalizing a fleet averaging system very

similar to the light-duty GHG and CAFE fleet averaging system.

At proposal, we restricted the use of the ABT provisions of the program to 

vehicles or engines within the same regulatory subcategory. This meant that credit 

exchanges could only happen between similar vehicles meeting the same standards. We 

proposed this approach for two reasons. First, we were concerned about a level playing 

 

41 NHTSA notes that it has greater flexibility in the HD program to include consideration of credits and 

other flexibilities in determining appropriate and feasible levels of stringency than it does in the light-duty 

CAFE program. Cf. 49 U.S.C. 32902(h), which applies to light-duty CAFE but not heavy-duty fuel 

efficiency under 49 U.S.C. 32902(k).
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field between different manufacturers who may not participate equally in the various 

truck and engine markets covered in the regulation. Second, we were concerned about 

the uncertainties inherent in credit calculations that are based on projections of lifetime 

emissions for different vehicles in wholly different vehicle markets. In response to 

comments, we have revised our ABT provisions to provide greater flexibility while 

continuing to provide assurance that the projected reductions in fuel consumption and 

GHG emissions will be achieved. We are relaxing the restriction on averaging, banking, 

and trading of credits between the various regulatory subcategories, by defining three HD 

vehicle averaging sets: Light Heavy-Duty (Classes 2b-5); Medium Heavy-Duty (Class 6-

7); and Heavy Heavy-Duty (Class 8). This allows the use of credits between vehicles 

within the same weight class. This means that a Class 8 day cab tractor can exchange 

credits with a Class 8 high roof sleeper tractor but not with a smaller Class 7 tractor. 

Also, a Class 8 vocational vehicle can exchange credits with a Class 8 tractor. We are 

adopting these revisions based on comments from the regulated industry that convinced 

us these changes would allow the broadest trading possible while maintaining a level 

playing field among the various market segments. However, we are restricting trading 

between engines and chassis, even within the same vehicle class. 

The agencies believe that restricting trading to within the same eight classes as 

EPA’s existing criteria pollutant program (i.e. Heavy-Heavy Duty, Light Heavy-Duty, 

Medium Heavy-Duty) and restricting between engines and chassis for the same vehicle 

type, but not restricting trading between vehicle or engine type (such as combination 

tractors), is appropriate and reasonable. We do not expect emissions from engines and 

vehicles – when restricted by weight class – to be dissimilar. We therefore expect that 

the lifetime vehicle performance and emissions levels will be very similar across these 

defined categories, and the estimated credit calculations will fairly ensure the expected 

fuel consumption and GHG reductions. 

The agencies considered even broader averaging, banking, and trading provisions 

but decided that in this first phase of regulation, it would be prudent to start with the 

program described here, which will regulate greenhouse gas emissions and fuel 

consumption from this sector for the first time and provide considerable early reductions 

as well as opportunities to learn about technical and other issues that can inform future 

rulemakings. In the future we intend to consider whether such provisions could be 

designed so as to address any other relevant concerns.

Reducing the cost of regulation through broader use of market tools is a high 

priority for the Administration. See Executive Order 13563 and in particular section 

1(b)(5) and section 4. Consistent with this principle, we intend to seek public comment 

through a Notice of Data Availability after credit trading begins in 2013, the first year we 

expect manufacturers to begin certifying 2014 model year vehicles, on whether broader 

credit trading is more appropriate in developing the next phase of heavy-duty regulations. 

We believe that input will be better informed by the work the agencies and the regulated 

industry will have put into implementing this first phase of heavy-duty regulations.

Through this public process, emphasizing the Administration’s strong preference 

for flexible approaches and maximizing the use of market tools, the agencies intend to 
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fully consider whether broader credit trading is more appropriate in developing the next 

phase of heavy-duty regulations.

This program thus does not allow credits to be exchanged between heavy-duty

vehicles and light-duty vehicles, nor can credits be traded from heavy-duty vehicle fleets 

to light-duty vehicle fleets and vice versa. 

The engine ABT provisions are also changed from the proposal and now are the 

same as in EPA’s existing criteria pollutant emission rules. The agencies have broadened 

the averaging sets to include both FTP-certified and SET-certified engines in the same 

averaging set. For example, a SET-certified engine intended for a Class 8 tractor can 

exchange credits with a FTP-certified engine intended for a Class 8 vocational vehicle. 

The agencies are finalizing three year deficit carry-forward provisions for heavyduty engines and vehicles within a limited time frame. This flexibility is expected to 

provide an opportunity for manufacturers to make necessary technological improvements 

and reduce the overall cost of the program without compromising overall environmental 

and fuel economy objectives. This flexibility, similar to the flexibility the agencies have 

offered under the light-duty vehicle program, is intended to assist the broad goal of 

harmonizing the two agencies’ standards while preserving the flexibility of manufacturers 

of vehicles and engines in meeting the standards, to the extent appropriate and required 

by law. During the MYs 2014–2018 manufacturers are expected to go through the 

normal business cycle of redesigning and upgrading their heavy-duty engine and vehicle 

products, and in some cases introducing entirely new vehicles and engines not on the 

market today. As explained in the following paragraph, the carry-forward provision will

allow manufacturers the time needed to incorporate technology to achieve GHG 

reductions and improve fuel economy during the vehicle redesign process.

We received comments from Center for Biological Diversity against the need to 

offer the deficit carry-forward flexibility. CBD has stated that allowing manufacturers to 

carry-forward deficits for up to three years would incentivize delays in investment and 

technological innovation and allow for the generation of additional tons of GHG 

emissions that may be prevented today. However, the deficit carry-forward flexibility (as 

well as ABT generally) has enabled the agencies to consider overall standards that are 

more stringent and that will become effective at an earlier period than we could consider 

with a more rigid program. The agencies also believe this flexibility is an important 

aspect of the program, as it avoids the much higher costs that would occur if 

manufacturers needed to add or change technology at times other than their scheduled 

redesigns, i.e. the cost of adopting a new engine or vehicle platform mid-production or 

mid-design. This time period would also provide manufacturers the opportunity to plan 

for compliance using a multi-year time frame, again consistent with normal business 

practice. Over these four model years, there would be an opportunity for manufacturers to 

evaluate practically all of their vehicle and engine model platforms and add technology in 

a cost effective way to control GHG emissions and improve fuel economy. 

As noted above, in addition to ABT, the other primary flexibility provisions in 

this program involve opportunities to generate early credits, advanced technology credits 
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(including for use of hybrid powertrains), and innovative technology credits. For the 

early credits and advanced technology credits, the agencies sought comment on the 

appropriateness of providing a 1.5x multiplier as an incentive for their use. We received 

a number of comments supporting the idea of a credit multiplier, arguing it was an 

appropriate means to incentivize the early compliance and advanced technologies the 

agencies sought. We received other comments suggesting a multiplier was unnecessary. 

After considering the comments, the agencies have decided to finalize a 1.5x multiplier 

consistent with our request for comments. We believe that given the very short lead time 

of the program and the nascent nature of the advanced technologies identified in the 

proposal, that a 1.5x multiplier is an effective means to bring technology forward into the 

heavy-duty sector sooner than would otherwise occur. In addition, advanced technology 

credits could be used anywhere within the heavy duty sector (including both vehicles and 

engines), but early credits would be restricted to use within the same defined averaging 

set generating the credit.

For other technologies which can reduce CO2 and fuel consumption, but for 

which there do not yet exist established methods for quantifying reductions, the agencies 

still wish to encourage the development of such innovative technologies, and are 

therefore adopting special “innovative technology” credits. These innovative technology

credits will apply to technologies that are shown to produce emission and fuel 

consumption reductions that are not adequately recognized on the current test procedures 

and that are not yet in widespread use in the heavy-duty sector. Manufacturers will need 

to quantify the reductions in fuel consumption and CO2 emissions that the technology is 

expected to achieve, above and beyond those achieved on the existing test procedures. 

As with ABT, the use of innovative technology credits will only be allowed for use 

among vehicles and engines of the same defined averaging set generating the credit, as 

described above. The credit multiplier will not be used for innovative technology credits.

CBD argued that including any opportunities for manufacturers to earn credits in 

the final rule would violate NHTSA’s statutory mandate to implement a program 

designed to achieve the maximum feasible improvement. 

NHTSA strongly believes that creating credit flexibilities for manufacturers for 

this first phase of the HD National Program is fully consistent with the agency’s 

obligation to develop a fuel efficiency improvement program designed to achieve the 

maximum feasible improvement. EISA gives NHTSA broad authority to develop 

“compliance and enforcement protocols” that are “appropriate, cost-effective, and 

technologically feasible,” and the agency believes that compliance flexibilities such as 

the opportunity to earn and use credits to meet the standards are a reasonable and 

appropriate interpretation of that authority, along with the other compliance and 

enforcement provisions developed for this final rule. Unlike in NHTSA’s light-duty 

program, where the agency is restricted from considering the availability of credits in 

determining the maximum feasible level of stringency for the fuel economy standards,42

in this HD National Program, NHTSA and EPA have based the levels of stringency in 

part on our assumptions of the use of available flexibilities that have been built into the 

 

42 See 49 U.S.C. 32902(h).
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program to incentivize over-compliance in some respects, to balance out potential undercompliance in others. 

By assuming the use of credits for compliance, the agencies were able to set the 

fuel consumption/GHG standards at more stringent levels than would otherwise have 

been feasible. Greater improvements in fuel efficiency will occur under more stringent 

standards; manufacturers will simply have greater flexibility to determine where and how 

to make those improvements than they would have without credit options. Further, this is 

consistent with EOs 12866 and 13563, which encourage agencies to design regulations 

that promote innovation and flexibility where possible.43

A detailed discussion of each agency’s ABT, early credit, advanced technology, 

and innovative technology provisions for each regulatory category of heavy-duty vehicles 

and engines is found in Section IV below.

F. EPA and NHTSA Statutory Authorities

(1) EPA Authority

Title II of the CAA provides for comprehensive regulation of mobile sources, 

authorizing EPA to regulate emissions of air pollutants from all mobile source categories. 

When acting under Title II of the CAA, EPA considers such issues as technology

effectiveness, its cost (both per vehicle, per manufacturer, and per consumer), the lead 

time necessary to implement the technology, and based on this the feasibility and 

practicability of potential standards; the impacts of potential standards on emissions 

reductions of both GHGs and non-GHGs; the impacts of standards on oil conservation 

and energy security; the impacts of standards on fuel savings by customers; the impacts 

of standards on the truck industry; other energy impacts; as well as other relevant factors 

such as impacts on safety. 

This final action implements a specific provision from Title II, section 202(a).44 

Section 202(a)(1) of the CAA states that “the Administrator shall by regulation prescribe 

(and from time to time revise)...standards applicable to the emission of any air pollutant 

from any class or classes of new motor vehicles ..., which in his judgment cause, or 

contribute to, air pollution which may reasonably be anticipated to endanger public health 

or welfare.” With EPA’s December 2009 final findings that certain greenhouse gases 

may reasonably be anticipated to endanger public health and welfare and that emissions 

 

43 EO 12866 states that an agency must “design its regulations in the most cost-effective manner to achieve 

the regulatory objective... consider[ing] incentives for innovation... [and] flexibility,” among other 

factors; EO 13563 directs agencies to “seek to identify, as appropriate, means to achieve regulatory goals 

that are designed to promote innovation,” and “identify and consider regulatory approaches that... 

maintain flexibility.”

44 See 42 U.S.C. 7521 (a). A number of commenters believed that the GHG program was being adopted 

pursuant to section 202 (a)(3)(A) and that the lead time requirements of section 202 (a)(3)(C) therefore 

apply. This is mistaken. Section 202 (a)(3)(A) applies to standards for emissions of hydrocarbons, carbon 

monoxide, oxides of nitrogen, and particulate matter from heavy-duty vehicles and engines. This does not 

include the GHGs regulated under the standards in today’s action. This comment is addressed further in 

the Response to Comment document.
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of GHGs from section 202 (a) sources cause or contribute to that endangerment, section 

202(a) requires EPA to issue standards applicable to emissions of those pollutants from 

new motor vehicles.

Any standards under CAA section 202(a)(1) “shall be applicable to such vehicles 

... for their useful life.” Emission standards set by the EPA under CAA section 202(a)(1) 

are technology-based, as the levels chosen must be premised on a finding of 

technological feasibility. Thus, standards promulgated under CAA section 202(a) are to 

take effect only “after providing such period as the Administrator finds necessary to 

permit the development and application of the requisite technology, giving appropriate 

consideration to the cost of compliance within such period” (section 202(a)(2); see also

NRDC v. EPA, 655 F. 2d 318, 322 (D.C. Cir. 1981)). EPA is afforded considerable 

discretion under section 202(a) when assessing issues of technical feasibility and 

availability of lead time to implement new technology. Such determinations are “subject 

to the restraints of reasonableness”, which “does not open the door to ‘crystal ball’

inquiry.” NRDC, 655 F. 2d at 328, quoting International Harvester Co. v. Ruckelshaus, 

478 F. 2d 615, 629 (D.C. Cir. 1973). However, “EPA is not obliged to provide detailed 

solutions to every engineering problem posed in the perfection of the trap-oxidizer. In 

the absence of theoretical objections to the technology, the agency need only identify the 

major steps necessary for development of the device, and give plausible reasons for its 

belief that the industry will be able to solve those problems in the time remaining. The 

EPA is not required to rebut all speculation that unspecified factors may hinder ‘real 

world’ emission control.” NRDC, 655 F. 2d at 333-34. In developing such technologybased standards, EPA has the discretion to consider different standards for appropriate 

groupings of vehicles (“class or classes of new motor vehicles”), or a single standard for 

a larger grouping of motor vehicles (NRDC, 655 F. 2d at 338).

Although standards under CAA section 202(a)(1) are technology-based, they are 

not based exclusively on technological capability. EPA has the discretion to consider and 

weigh various factors along with technological feasibility, such as the cost of compliance 

(See section 202(a) (2)), lead time necessary for compliance (section 202(a)(2)), safety 

(See NRDC, 655 F. 2d at 336 n. 31) and other impacts on consumers, and energy impacts 

associated with use of the technology. See George E. Warren Corp. v. EPA, 159 F.3d 

616, 623-624 (D.C. Cir. 1998) (ordinarily permissible for EPA to consider factors not 

specifically enumerated in the CAA). See also Entergy Corp. v. Riverkeeper, Inc., 129 

S.Ct. 1498, 1508-09 (2009) (congressional silence did not bar EPA from employing costbenefit analysis under Clean Water Act absent some other clear indication that such 

analysis was prohibited; rather, silence indicated discretion to use or not use such an 

approach as the agency deems appropriate).

In addition, EPA has clear authority to set standards under CAA section 202(a) 

that are technology forcing when EPA considers that to be appropriate, but is not required 

to do so (as compared to standards set under provisions such as section 202(a)(3) and 
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section 213(a)(3)).45 EPA has interpreted a similar statutory provision, CAA section 231, 

as follows: 

While the statutory language of section 231 is not identical to other provisions in 

title II of the CAA that direct EPA to establish technology-based standards for various 

types of engines, EPA interprets its authority under section 231 to be somewhat similar to 

those provisions that require us to identify a reasonable balance of specified emissions 

reduction, cost, safety, noise, and other factors. See, e.g., Husqvarna AB v. EPA, 254 

F.3d 195 (D.C. Cir. 2001) (upholding EPA’s promulgation of technology-based standards 

for small non-road engines under section 213(a)(3) of the CAA). However, EPA is not 

compelled under section 231 to obtain the ‘‘greatest degree of emission reduction 

achievable’’ as per sections 213 and 202 of the CAA, and so EPA does not interpret the 

Act as requiring the agency to give subordinate status to factors such as cost, safety, and 

noise in determining what standards are reasonable for aircraft engines. Rather, EPA has 

greater flexibility under section 231 in determining what standard is most reasonable for 

aircraft engines, and is not required to achieve a ‘‘technology forcing’’ result (70 FR

69664 and 69676, November 17, 2005). 

This interpretation was upheld as reasonable in NACAA v. EPA, 489 F.3d 1221, 

1230 (D.C. Cir. 2007). CAA section 202(a) does not specify the degree of weight to 

apply to each factor, and EPA accordingly has discretion in choosing an appropriate 

balance among factors. See Sierra Club v. EPA, 325 F.3d 374, 378 (D.C. Cir. 2003) 

(even where a provision is technology-forcing, the provision “does not resolve how the 

Administrator should weigh all [the statutory] factors in the process of finding the 

‘greatest emission reduction achievable’”). See also Husqvarna AB v. EPA, 254 F. 3d 

195, 200 (D.C. Cir. 2001) (great discretion to balance statutory factors in considering 

level of technology-based standard, and statutory requirement “to [give appropriate] 

consideration to the cost of applying ... technology” does not mandate a specific method 

of cost analysis); see also Hercules Inc. v. EPA, 598 F. 2d 91, 106 (D.C. Cir. 1978) (“In 

reviewing a numerical standard the agencies must ask whether the agency’s numbers are 

within a zone of reasonableness, not whether its numbers are precisely right”); Permian 

Basin Area Rate Cases, 390 U.S. 747, 797 (1968) (same); Federal Power Commission v. 

Conway Corp., 426 U.S. 271, 278 (1976) (same); Exxon Mobil Gas Marketing Co. v. 

FERC, 297 F. 3d 1071, 1084 (D.C. Cir. 2002) (same).

(a) EPA Testing Authority

Under section 203 of the CAA, sales of vehicles are prohibited unless the vehicle 

is covered by a certificate of conformity. EPA issues certificates of conformity pursuant 

to section 206 of the Act, based on (necessarily) pre-sale testing conducted either by EPA 

or by the manufacturer. The Heavy-duty Federal Test Procedure (Heavy-duty FTP) and 

the Supplemental Engine Test (SET) are used for this purpose. Compliance with 

standards is required not only at certification but throughout a vehicle’s useful life, so 

 

45

 One commenter mistakenly stated that section 202 (a) standards must be technology-forcing, but the 

provision plainly does not require EPA to adopt technology-forcing standards. See further discussion in 

Section III.A below.
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that testing requirements may continue post-certification. Useful life standards may

apply an adjustment factor to account for vehicle emission control deterioration or 

variability in use (section 206(a)). 

EPA established the Light-duty FTP for emissions measurement in the early 

1970s. In 1976, in response to the Energy Policy and Conservation Act, EPA extended 

the use of the Light-duty FTP to fuel economy measurement (See 49 U.S.C. 32904(c)). 

EPA can determine fuel efficiency of a vehicle by measuring the amount of CO2 and all 

other carbon compounds (e.g., total hydrocarbons and carbon monoxide (CO)), and then, 

by mass balance, calculating the amount of fuel consumed.

(b) EPA Enforcement Authority

Section 207 of the CAA grants EPA broad authority to require manufacturers to 

remedy vehicles if EPA determines there are a substantial number of noncomplying 

vehicles. In addition, section 205 of the CAA authorizes EPA to assess penalties of up to 

$37,500 per vehicle for violations of various prohibited acts specified in the CAA. In 

determining the appropriate penalty, EPA must consider a variety of factors such as the 

gravity of the violation, the economic impact of the violation, the violator’s history of 

compliance, and “such other matters as justice may require.”

(2) NHTSA Authority

In 1975, Congress enacted the Energy Policy and Conservation Act (EPCA), 

mandating a regulatory program for motor vehicle fuel economy to meet the various 

facets of the need to conserve energy. In December 2007, Congress enacted the Energy

Independence and Securities Act (EISA), amending EPCA to require, among other 

things, the creation of a medium- and heavy-duty fuel efficiency program for the first 

time. This mandate in EISA represents a major step forward in promoting EPCA’s goals 

of energy independence and security, and environmental and national security.

NHTSA has primary responsibility for fuel economy and consumption standards, 

and assures compliance with EISA through rulemaking, including standard-setting; 

technical reviews, audits and studies; investigations; and enforcement of implementing 

regulations including penalty actions. This final action implements Section 32902(k)(2) 

of EISA, which instructs NHTSA to create a fuel efficiency improvement program for 

“commercial medium- and heavy-duty on-highway vehicles and work trucks”46 by

rulemaking, which is to include standards, test methods, measurement metrics, and 

enforcement protocols. See 49 U.S.C. 32902(k)(2). Congress directed that the standards, 

test methods, measurement metrics, and compliance and enforcement protocols be 

“appropriate, cost-effective, and technologically feasible” for the vehicles to be regulated, 

while achieving the “maximum feasible improvement” in fuel efficiency.

NHTSA has clear authority to design and implement a fuel efficiency program for 

vehicles and work trucks under EISA, and was given broad discretion to balance the 

 

46 “Commercial medium- and heavy-duty on-highway vehicles” are defined at 49 U.S.C. 32901(a)(7), and 

“work trucks” are defined at (a)(19).
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statutory factors in 32902(k)(2) in developing fuel consumption standards to achieve the 

maximum feasible improvement. Since this is the first rulemaking that NHTSA has 

conducted under 49 U.S.C. 32902(k)(2), the agency interpreted these elements and 

factors in the context of setting standards, choosing metrics, and determining test 

methods and compliance/enforcement mechanisms. Discussion of the application of 

these factors can be found in Section III below. Congress also gave NHTSA the authority

to set separate standards for different classes of these vehicles, but required that all 

standards adopted provide not less than four full model years of regulatory lead-time and 

three full model years of regulatory stability.

In EISA, Congress required NHTSA to prescribe separate average fuel economy

standards for passenger cars and light trucks in accordance with the provisions in 49 

U.S.C. Section 32902(b), and to prescribe standards for work trucks and commercial 

medium- and heavy-duty vehicles in accordance with the provisions in 49 U.S.C. 

32902(k). See 49 U.S.C. Section 32902(b)(1). Congress also added in EISA a 

requirement that NHTSA shall issue regulations prescribing fuel economy standards for 

at least 1, but not more than 5, model years. See 49 U.S.C. Section 32902(b)(3)(B). For 

purposes of the fuel efficiency standards that the agency proposed for HD vehicles and 

engines, the NPRM stated an interpretation of the statute that the 5-year maximum limit 

did not apply to standards promulgated in accordance with 49 U.S.C. Section 32902(k), 

given the language in Section 32902(b)(1). Based on this interpretation, NHTSA 

proposed that the standards ultimately finalized for HD vehicles and engines would 

remain in effect indefinitely at their 2018 or 2019 model year levels until amended by a 

future rulemaking action. In any future rulemaking action to amend the standards, 

NHTSA would ensure not less than four full model years of regulatory lead-time and 

three full model years of regulatory stability. NHTSA sought comment on its

interpretation of EISA.

Robert Bosch LLC (Bosch) commented that the absence of an expiration date for 

the standards proposed in the NPRM could violate 49 U.S.C. Section 32902, which it

interpreted as requiring the MD/HD program to have standards that expire in five years. 

Section 32902(k)(3), which lays out the requirements for the MD/HD program, specifies 

the minimum regulatory lead and stability times, as described above, but does not specify

a maximum duration period. In contrast, Section 32902(b)(3)(B) lays out the minimum 

and maximum durations of standards to be established in a rulemaking for the light-duty 

program, but prescribes no minimum lead or stability time. Bosch argued that as 49 

U.S.C. Section 32902(k)(3) does not require a maximum duration period, Congress 

intended that NHTSA take the maximum duration period specified for the light-duty

program in Section 32902(b)(3)(B), five years, and apply it to Section 32902(k)(3). 

Bosch also argued, however, that the minimum duration period should not be carried over 

from the light-duty to the heavy-duty section, as a minimum duration period for HD was 

specified in Section 32902(k)(3).

NHTSA has revisited this issue and continues to believe that it is reasonable to 

assume that if Congress intended for the HD/MD regulatory program to be limited by the 

timeline prescribed in Subsection (b)(3)(B), it would have either mentioned HD/MD 
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vehicles in that subsection or included the same timeline in Subsection (k).47 In addition, 

in order for Subsection (b)(3)(B) to be interpreted to apply to Subsection (k), the agency

would need to give less than full weight to the earlier phrase in the statute directing the 

Secretary to prescribe standards for “work trucks and commercial medium-duty or heavyduty on-highway vehicles in accordance with Subsection (k).” 49 U.S.C. 32902(b)(1)(C). 

Instead, this direction would need to be read to mean “in accordance with Subsection (k) 

and the remainder of Subsection (b).” NHTSA believes this interpretation would be 

inappropriate. Interpreting “in accordance with Subsection (k)” to mean something 

indistinct from “in accordance with this Subsection” goes against the canon that statutes 

should not be interpreted in a way that “render[s] language superfluous.” Dobrova v. 

Holder, 607 F.3d 297, 302 (2d Cir. 2010), quoting Mendez v. Holder, 566 F. 3d 316, 321-

22 (2d Cir. 2009). Based on this reasoning, NHTSA believes the more reasonable and 

appropriate approach is reflected in the proposal, and the final rules therefore follow this 

approach. 

Another commenter, CBD, expressed concern that lack of an expiration date 

meant that the standards would remain indefinitely, thus forgoing the possibility of 

increased stringency in the future. CBD argued that this violated NHTSA’s statutory

duty to set maximum feasible standards. NHTSA disagrees that the indefinite duration of 

the standards in this rule would prevent the agency from setting future standards at the 

maximum feasible level in future rulemakings. The absence of an expiration date for 

these standards should not be interpreted to mean that there will be no future rulemakings 

to establish new MD/HD fuel efficiency standards for MYs 2019 and beyond – the 

agencies have already previewed the possibility of such a rulemaking in other parts of 

this final rule preamble. Therefore, NHTSA believes this concern is unnecessary.

(a) NHTSA Testing Authority

49 U.S.C. Section 32902(k)(2) states that NHTSA must adopt and implement 

appropriate, cost-effective, and technologically feasible test methods and measurement 

metrics as part of the fuel efficiency improvement program. For this program, 

manufacturers will test and conduct modeling to determine GHG emissions and fuel 

consumption performance, and EPA and NHTSA will perform validation testing. The 

results of the validation tests will be used by EPA to create a finalized reporting that 

confirms the manufacturer’s final model year GHG emissions and fuel consumption 

results, which each agency will use to enforce compliance with its standards.

 

47 “[W]here Congress includes particular language in one section of a statute but omits it in another section 

of the same Act, it is generally presumed that Congress acts intentionally and purposely in the disparate 

inclusion or exclusion.” Russello v. United States, 464 U.S. 16, 23 (1983), quoting U.S. v. Wong Kim Bo, 

472 F.2d 720, 722 (5th Cir 1972)., See also Mayo v. Questech, Inc., 727 F.Supp. 1007, 1014 (E.D.Va. 1989) 

(conspicuous absence of provision from section where inclusion would be most logical signals Congress 

did not intend for it to be implied). 
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(b) NHTSA Enforcement Authority

(i) Overview

The NPRM proposed a compliance and enforcement program that included civil 

penalties for violations of the fuel efficiency standards. 49 U.S.C. 32902(k)(2) states that 

NHTSA must adopt and implement appropriate, cost-effective, and technologically

feasible compliance and enforcement protocols for the fuel efficiency improvement 

program. Congress gave DOT broad discretion to fashion its fuel efficiency 

improvement program and thus necessarily did not speak directly or specifically as to the 

nature of the compliance and enforcement protocols that would be best suited for 

effectively supporting the yet-to-be-designed-and-established program. Instead, it left the 

matter generally to the Secretary. Congress’ approach is unlike CAFE enforcement for 

passenger cars and light trucks, where Congress specified the precise details of a program 

and provided that a manufacturer either complies with standards or pays civil penalties. 

The statute is silent with respect to how “protocol” should be interpreted. The 

term “protocol” is imprecise and thus Congress’ choice of that term affords the agency

substantial breadth of discretion. For example, in a case interpreting section 301(c)(2) of 

the Comprehensive Environmental Response, Compensation, and Liability Act 

(CERCLA), the D.C. Circuit noted that the word “protocols” has many definitions that 

are not much help. Kennecott Utah Copper Corp., Inc. v. U.S. Dept. of Interior, 88 F.3d. 

1191, 1216 (D.C. Cir. 1996). Section 301(c)(2) of CERCLA prescribed the creation of 

two types of procedures for conducting natural resources damages assessments. The 

regulations were to specify (a) “standard procedures for simplified assessments requiring 

minimal field observation” (the “Type A” rules), and (b) “alternative protocols for 

conducting assessments in individual cases” (the “Type B” rules).48 The court upheld the 

challenged provisions, which were a part of a set of rules establishing a step-by-step 

procedure to evaluate options based on certain criteria, and to make a decision and 

document the results.

Taking the considerations above into account, including Congress’ instructions to 

adopt and implement compliance and enforcement protocols, and the Secretary’s 

authority to formulate policy and make rules to fill gaps left, implicitly or explicitly, by

Congress, the agency interpreted “protocol” in the context of EISA as authorizing the 

agency to determine both whether manufacturers have complied with the standards, and 

to establish suitable and reasonable enforcement mechanisms and decision criteria for 

non-compliance. Therefore, NHTSA interpreted its authority to develop an enforcement 

program to include the authority to determine and assess civil penalties for noncompliance.

Several commenters disagreed with this interpretation. Volvo and EMA 

commented that the penalties proposed by NHTSA exceeded the authority granted to the 

agency by Congress, and Volvo commented that the fact that Congress did not adopt an 

entirely new statute for the HD program should be interpreted to mean that provisions 

 

48 State of Ohio v. U.S. Dept. of Interior, 880 F.2d 432, 439 (D.C. Cir. 1989).
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adopted for the light-duty program should apply to the HD program as well. Daimler 

argued that it was likely that EISA did not give NHTSA the authority to assess civil 

penalties, and Navistar and EMA argued that NHTSA could not have the authority as 

Congress did not expressly grant it.

NHTSA continues to believe that it is reasonable to interpret “compliance and 

enforcement protocols” to include authority to impose civil penalties. Where a statute 

does not specify an approach, the discretion to do so is left to the agency. When 

Congress has “explicitly left a gap for an agency to fill, there is an express delegation of 

authority to the agency to elucidate a specific provision of the statute by regulation.”

United States. v. Mead, 533 U.S. 218, 227 (2001), quoting Chevron v. NRDC, 467 U.S. 

837, 843-44 (1984). The delegation of authority may be implicit rather than express. Id. 

at 229. NHTSA believes it would be unreasonable to assume that Congress intended to 

create a hollow regulatory program without a mechanism for effective enforcement. 

Further, interpreting “enforcement protocols” to mean not more than “compliance 

protocols” would go against the canon noted above that statutes should not be interpreted 

in a way that “render[s] language superfluous.” Dobrova v. Holder, 607 F.3d 297, 302 

(2d Cir. 2010), quoting Mendez v. Holder 566 F. 3d 316, 321-22 (2d Cir. 2009). The 

interpretation urged by the commenters would render an entire program superfluous.

Further, NHTSA believes that Congress would have anticipated that compliance 

and enforcement protocols would include civil penalties for the HD sector, given that 

penalties are an integral part of a product standards program and given the long precedent 

of civil penalties for the light-duty sector. The agency disagrees with the argument that 

the HD program would have appeared in a wholly separate statute if Congress had not 

intended the penalty program for light-duty to apply to it. The inclusion of the MD/HD 

program in Title 329 does not mean that Congress intended for the boundaries and 

differences between the separate sections to be ignored. Rather, this argument leads to 

the opposite conclusion that the fact that Congress created a new section for the HD 

program, instead of simply amending the existing light-duty program to include “work 

trucks and other vehicles” in addition to automobiles, means the agency should assume 

that Congress acted intentionally when it created two wholly separate programs and 

respect their distinctions.

Therefore, consistent with the statutory interpretation proposed in the NPRM, the final 

rule includes penalties for non-compliance with the fuel efficiency standards. 

(ii) Penalty Levels

NHTSA proposed to adopt penalty levels equal to those in EPA’s existing heavyduty program, in order to provide adequate deterrence as well as consistency with the 

GHG regulation. The proposed maximum penalty levels were $37,500.00 per vehicle or 

engine.

Several manufacturers commented that the penalty levels should be limited to 

those mandated in the light-duty program. Volvo and Daimler argued that Congress 
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intended lower penalties for the HD program than were proposed in the NPRM, because 

they believed that Congress had expressly or implicitly intended for the HD program to 

be included in the penalty calculation of Section 32912(b). That section prescribes 

penalty levels for violators under Section 32902 of “$5 multiplied by each tenth (0.1) of a 

mile a gallon by which the applicable average fuel economy standard under that section 

exceeds the average fuel economy,”49 calculated and applied to automobiles. Volvo 

further argued that NHTSA was relying upon the CAA as the statutory basis for the 

penalty levels. 

NHTSA recognizes that Section 329 contains a detailed penalty scheme, for lightduty vehicle CAFE standards. However, Section 32902(k)(2) explicitly directs NHTSA 

to “adopt and implement appropriate test methods, measurement metrics, fuel economy 

standards, and compliance and enforcement protocols,” in the creation of the new HD 

program. NHTSA continues to believe that this broad Congressional mandate should be 

interpreted based on a plain text reading, which includes the authority to determine 

compliance and enforcement protocols that will be effective and appropriate for this new 

sector of regulation. NHTSA also believes that reading Section 32912 to apply to the 

new HD program would contradict Congress’ broad mandate for the agency to establish 

new measurement metrics and a compliance and enforcement program. Further, 

interpreting the requirement to create “enforcement protocols” for HD vehicles to mean 

that NHTSA should rely on the enforcement provisions for light-duty vehicles would go 

against the canon noted above that statutes should not be interpreted in a way that 

“render[s] language superfluous.” Dobrova v. Holder, 607 F.3d 297, 302 (2d Cir. 2010), 

quoting Mendez v. Holder 566 F. 3d 316, 321-22 (2d Cir. 2009).

NHTSA believes that Section 32912 does not apply to the new HD program for 

several other reasons. First, this section uses a fuel economy metric, miles/gallon, while 

the HD program is built around a fuel consumption metric, per the requirement to 

develop a “fuel efficiency improvement program” and the agencies’ conclusion, 

supported by NAS, that a fuel consumption metric is a much more reasonable choice than 

a fuel economy metric for HD vehicles given their usage as work vehicles. Second, this 

section specifies a calculation for automobiles, a vehicle class which is confined to the 

light-duty rule. In addition, the HD program prescribes fuel consumption standards, not 

average fuel economy standards. 

Finally, NHTSA believes that if Congress had intended for a pre-determined 

penalty scheme to apply to the new HD program, it would have been specific. Instead, 

Congress explicitly directed the agency to develop a new measurement, compliance, and 

enforcement scheme. Consistent with the statutory interpretation of the duration of the 

standards, NHTSA believes that if Congress intended for particular penalty levels to be 

used in 32902(k)(3), it would have either included a reference to those levels or included 

 

49 This fine was increased by 49 CFR Part 578.6, which provides that “Except as provided in 49 U.S.C. 

32912(c), a manufacturer that violates a standard prescribed for a model year under 49 U.S.C. 32902 is 

liable to the United States Government for a civil penalty of $5.50 multiplied by each 0.1 of a mile a gallon 

by which the applicable average fuel economy standard under that section exceeds the average fuel 

economy.”
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a reference in 32912 to the vehicles and metrics regulated by 32902(k)(3). SeeRussello v. 

United States, 464 U.S. 16, 23 (1983), quoting United States. v. Wong Kim Bo, 472 F.2d 

720, 722 (5th Cir 1972) (“[W]here Congress includes particular language in one section 

of a statute but omits it in another section of the same Act, it is generally presumed that 

Congress acts intentionally and purposely in the disparate inclusion or exclusion.”)

Instead, the absence of such language could mean either that Congress did not 

contemplate the specific penalty levels to be used, or that Congress left the choice of 

specific penalty levels to the agency. See Alliance for Community Media v. F.C.C. 529 F. 

3d 763, 779 (6th Cir. 2008) (absence of a statutory deadline in one section but not others 

meant that Congress authorized but did not require it in that section).

Therefore, the final rule retains the maximum penalty level proposed in the 

NPRM. 

G. Future HD GHG and Fuel Consumption Rulemakings

This final action represents a first regulatory step by NHTSA and EPA to address 

the multi-faceted challenges of reducing fuel use and greenhouse gas emissions from 

these vehicles. By focusing on existing technologies and well-developed regulatory

tools, the agencies are able to adopt rules that we believe will produce real and important 

reductions in GHG emissions and fuel consumption within only a few years. Within the 

context of this regulatory time frame, our program is very aggressive - with limited lead 

time compared to historic heavy-duty regulations - but pragmatic in the context of 

technologies that are available and that can be reasonably implemented during the 

regulatory time frame. 

While we are now only finalizing this first step, it is worthwhile to consider how 

the next regulatory step may be designed. Technologies such as hybrid drivetrains, 

advanced bottoming cycle engines, and full electric vehicles are promoted in this first 

step through incentive concepts as discussed in Section IV, but we believe that these 

advanced technologies will not be necessary to meet the final standards. Today’s 

standards are premised on the use of existing technologies given the short lead time, as 

discussed in Section III, below. When we begin work to develop a possible next set of 

regulatory standards, the agencies expect these advanced technologies to be an important 

part of the regulatory program and will consider them in setting the stringency of any

standards beyond the 2018 model year.

We will not only consider the progress of technology in our future regulatory

efforts, but the agencies are also committed to fully considering a range of regulatory

approaches. To more completely capture the complex interactions of the total vehicle 

and the potential to reduce fuel consumption and GHG emissions through the 

optimization of those interactions may require a more sophisticated approach to vehicle 

testing than we are adopting today for the largest heavy-duty vehicles. In future 

regulations, the agencies expect to fully evaluate the potential to expand the use of 

vehicle compliance models to reflect engine and drivetrain performance. Similarly, we 

intend to consider the potential for complete vehicle testing using a chassis dynamometer, 

not only as a means for compliance, but also as a complementary tool for the 
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development of more complex vehicle modeling approaches. In considering these more 

comprehensive regulatory approaches, the agencies will also reevaluate whether separate 

regulation of trucks and engines remains necessary.

In addition to technology and test procedures, vehicle and engine drive cycles are 

an important part of the overall approach to evaluating and improving vehicle 

performance. EPA, working through the WP.29 Global Technical Regulation process, 

has actively participated in the development of a new World Harmonized Duty Cycle for 

heavy-duty engines. EPA is committed to bringing forward these new procedures as part 

of our overall comprehensive approach for controlling criteria pollutant and GHG 

emissions. However, we believe the important issues and technical work related to 

setting new criteria pollutant emissions standards appropriate for the World Harmonized 

Duty Cycle are significant and beyond the scope of this rulemaking. Therefore, the 

agencies are not adopting these test procedures in this action, but we are ready to work 

with interested stakeholders to adopt these procedures in a future action.

As noted above, the agencies also intend to further investigate possibilities of 

expanded credit trading across the heavy-duty sector. As part of this effort, the agencies 

will investigate the degree to which the issue of credit trading is connected with complete 

vehicle testing procedures.

As with this program, our future efforts will be based on collaborative outreach 

with the stakeholder community and will be focused on a program that delivers on our 

energy security and environmental goals without restricting the industry’s ability to 

produce a very diverse range of vehicles serving a wide range of needs.

II. Final GHG and Fuel Consumption Standards for Heavyduty Engines and Vehicles

This section describes the standards and implementation dates that the agencies 

are finalizing for the three categories of heavy-duty vehicles and engines. The agencies 

have performed a technology analysis to determine the level of standards that we believe 

will be cost-effective, feasible, and appropriate in the lead time provided. This analysis, 

described in Section III and in more detail in the RIA Chapter 2, considered for each of 

the regulatory categories:

 the level of technology that is incorporated in current new engines and trucks, 

 forecasts of manufacturers’ product redesign schedules,

 the available data on corresponding CO2 emissions and fuel consumption for these 

engines and vehicles, 

 technologies that would reduce CO2 emissions and fuel consumption and that are 

judged to be feasible and appropriate for these vehicles and engines through the 2018 

model year, 

 the effectiveness and cost of these technologies, and
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 projections of future U.S. sales for trucks and engines. 

A. What Vehicles Will Be Affected?

EPA and NHTSA are finalizing standards for heavy-duty engines and also for 

what we refer to generally as “heavy-duty vehicles.” In general, these standards will 

apply for the model year 2014 and later engines and vehicles, although some standards do 

not apply until 2016 or 2017. The EPA standards will apply throughout the useful life of 

the engine or vehicle, just as existing criteria emission standards apply throughout the 

useful life. As noted in Section I, for purposes of this preamble and rules, the term 

“heavy-duty or “HD” applies to all highway vehicles and engines that are not regulated 

by the light-duty vehicle, light-duty truck and medium-duty passenger vehicle 

greenhouse gas and CAFE standards issued for MYs 2012-2016. Thus, in this notice, 

unless specified otherwise, the heavy-duty category incorporates all vehicles rated with 

GVWR greater than 8,500 pounds, and the engines that power these vehicles, except for 

MDPVs. The CAA defines heavy-duty vehicles as trucks, buses or other motor vehicles 

with GVWR exceeding 6,000 pounds. See CAA section 202(b)(3). In the context of the 

CAA, the term HD as used in these final rules thus refers to a subset of these vehicles and 

engines. EISA section 103(a)(3) defines a ‘commercial medium- and heavy-duty onhighway vehicle’ as an on-highway vehicle with GVWR of 10,000 pounds or more.50

 

EISA section 103(a)(6) defines a ‘work truck’ as a vehicle that is rated at between 8,500 

and 10,000 pounds gross vehicle weight and is not a medium-duty passenger vehicle.51 

Therefore, the term “heavy-duty vehicles” in this rulemaking refers to both work trucks 

and commercial medium- and heavy-duty on-highway vehicles as defined by EISA. 

Heavy-duty engines affected by the standards are those that are installed in commercial 

medium- and heavy-duty vehicles, except for the engines installed in vehicles certified to 

a complete vehicle emissions standard based on a chassis test, which would be addressed 

as a part of those complete vehicles, and except for engines used exclusively for 

stationary power when the vehicle is parked. The agencies’ scope is the same with the 

exception of recreational vehicles (or motor homes), as discussed above. The standards 

that EPA is finalizing today cover recreational on-highway vehicles, while NHTSA 

limited its scope in the proposal to not include these vehicles. See Section I.A above. 

The NPRM did not include an export exclusion in NHTSA’s fuel consumption 

standards. Oshkosh Corporation commented that NHTSA should add an export 

exclusion in order to accommodate the testing and delivery needs of manufacturers of 

vehicles intended for export. NHTSA agrees with this comment and Section 535.3 of the 

final rule specifies such an exclusion. 

 

50 Codified at 49 U.S.C. 32901(a)(7).

51 EISA Section 103(a)(6) is codified at 49 U.S.C. 32901(a)(19). EPA defines medium-duty passenger 

vehicles as any complete vehicle between 8,500 and 10,000 pounds GVWR designed primarily for the 

transportation of persons which meet the criteria outlined in 40 CFR 86.1803-01. The definition 

specifically excludes any vehicle that (1) has a capacity of more than 12 persons total or, (2) is designed to 

accommodate more than 9 persons in seating rearward of the driver’s seat or, (3) has a cargo box (e.g., 

pickup box or bed) of six feet or more in interior length. (See the Tier 2 final rulemaking, 65 FR 6698, 

February 10, 2000.)
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EPA and NHTSA are finalizing standards for each of the following categories, 

which together comprise all heavy-duty vehicles and all engines used in such vehicles. In 

order to most appropriately regulate the broad range of heavy-duty vehicles and engines, 

the agencies are setting separate engine and vehicle standards for the combination tractors 

and Class 2b through 8 vocational vehicles. The engine standards and test procedures for 

engines installed in the tractors and vocational vehicles are discussed within the preamble 

sections for combination tractors and vocational vehicles, respectively. The agencies are 

establishing standards for heavy-duty pickups and vans that apply to the entire vehicle;–

there are no separate engine standards.

As discussed in Section IX, the agencies are not adopting GHG emission and fuel 

consumption standards for trailers at this time. In addition, the agencies are not adopting 

standards at this time for engine, chassis, and vehicle manufacturers which are small 

businesses (as defined by the Small Business Administration). More detailed discussion 

of each regulatory category is included in the subsequent sections below.

B. Class 7 and 8 Combination Tractors

EPA is finalizing CO2 standards and NHTSA is finalizing fuel consumption 

standards for new Class 7 and 8 combination tractors. The standards are for the tractor 

cab, with a separate standard for the engine that is installed in the tractor. Together these 

standards would achieve reductions of up to 23 percent compared to the model 2010 

baseline level. As discussed below, EPA is finalizing its proposal to adopt the existing 

useful life definitions for Class 7 and 8 tractors and the heavy-duty engines installed in 

them. NHTSA and EPA are finalizing revised fuel consumption and GHG emissions 

standards for tractors, and finalizing as proposed engine standards for heavy-duty engines 

in Class 7 and 8 tractors. The agencies' analyses, as discussed briefly below and in more 

detail later in this preamble and in the RIA Chapter 2, show that these standards are 

feasible and appropriate under each agency’s respective statutory authorities. 

EPA is also finalizing standards to control N2O, CH4, and HFC emissions from 

Class 7 and 8 combination tractors. The final heavy-duty engine standards for both N2O 

and CH4 and details of the standard are included in the discussion in Section II.E.1.b and 

II.E.2.b, respectively. The final air conditioning leakage standards applying to tractor 

manufacturers to address HFC emissions are discussed in Section II.E.5.

The agencies are finalizing CO2 emissions and fuel consumption standards for the 

combination tractors that reflect reductions that can be achieved through improvements in 

the tractor (such as aerodynamics), tires, and other vehicle systems. The agencies are 

also finalizing heavy-duty engine standards for CO2 emissions and fuel consumption that 

reflect technological improvements in combustion and overall engine efficiency. 

The agencies have analyzed the feasibility of achieving the CO2 and fuel 

consumption standards, and have identified means of achieving the standards that are 

technically feasible in the lead time afforded, economically practicable and cost-effective. 

EPA and NHTSA present the estimated costs and benefits of the standards in Section III. 

In developing the final rules, the agencies have evaluated the kinds of technologies that 

could be utilized by engine and tractor manufacturers, as well as the associated costs for 
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the industry and fuel savings for the consumer and the magnitude of the national CO2 and 

fuel savings that may be achieved.

The agencies received comments from multiple stakeholders regarding the 

definition and classification of “combination tractors.” The commenters raised three key

issues. First, EMA/TMA, Navistar and DTNA requested that both agencies use the same 

definition for “tractor” or “truck tractor” in the final rules. EPA proposed a definition for

“tractor” in § 1037.801 as:

Tractor means a vehicle capable of pulling trailers that is not intended to carry

significant cargo other than cargo in the trailer, or any other vehicle intended for 

the primary purpose of pulling a trailer. For purposes of this definition, the term 

‘‘cargo’’ includes permanently attached equipment such as fire-fighting 

equipment. 

(1) The following vehicles are tractors: 

(i) Any vehicle sold to an ultimate purchaser with a fifth wheel coupling 

installed.

(ii) Any vehicle sold to an ultimate purchaser with the rear portion of the 

frame exposed where the length of the exposed portion is 5.0 meters or 

less. See § 1037.620 for special provisions related to vehicles sold to 

secondary vehicle manufacturers in this condition.

(2) The following vehicles are not tractors:

(i) Any vehicle sold to an ultimate purchaser with an installed cargo 

carrying feature. For example, this would include dump trucks and cement 

trucks.

(ii) Any vehicle lacking a fifth wheel coupling sold to an ultimate 

purchaser with the rear portion of the frame exposed where the length of 

the exposed portion is more than 5.0 meters.

NHTSA proposed a definition of “truck tractor” in 49 CFR 571.3 as:

Truck tractor means a truck designed primarily for drawing other motor vehicles 

and not so constructed as to carry a load other than a part of the weight of the 

vehicle and the load so drawn.

Second, EMA/TMA, NTEA and Navistar expressed concerns over, and requested 

the removal of, the proposed language that all vehicles with sleeper cabs would be 

classified as tractors. The commenters argued that because there are vocational vehicles 

manufactured with sleeper cabs that operate as vocational vehicles and not as tractors, 

those vehicles should be treated the same as all other vocational vehicles. Third, eleven 

different commenters requested that the agencies subdivide tractors into line-haul tractors 

and vocational tractors and treat each based upon their operational characteristics: 
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vocational tractors, which operate at lower speeds offroad or in stop-and-go city driving 

as vocational vehicles; and line-haul tractors, which operate at highway speeds on 

interstate roadways over long distances, as line-haul tractors. 

In response to the first comment, the agencies have decided to standardize the 

definition of tractor by using the long-standing NHTSA definition of “truck tractor” 

established in 49 CFR 571.3. 49 CFR 571.3(b) states that a “truck tractor means a truck 

designed primarily for drawing other motor vehicles and not so constructed as to carry a 

load other than a part of the weight of the vehicle and the load so drawn.” EPA’s 

proposed definition for “tractor” in the NPRM was similar to the NHTSA definition, but 

included some additional language to require a fifth wheel coupling and an exposed 

frame in the rear of the vehicle where the length of the exposed portion is 5.0 meters or 

less. EMA and Navistar argued that these two different definitions could lead to 

confusion if the agencies applied their requirements for truck tractors differently from 

each other. The commenters suggested that the EPA definition was more complicated 

than necessary, and that the simpler NHTSA definition should be used by both agencies 

as the base definition of truck tractor.

The agencies agree that the definitions should be standardized and that the 

NHTSA definition is sufficient and includes the essential requirement that a truck tractor 

is a truck designed “primarily for drawing other motor vehicles and not so constructed as 

to carry a load other than a part of the weight of the vehicle and the load so drawn.” 

EPA’s proposed tractor definition was intended to be functionally equivalent to

NHTSA’s definition based on design, but to be more objective by including the criteria 

related to “fifth wheels” and exposed rear frame. However, EPA no longer believes that 

such additional criteria are needed for implementation. NHTSA established the 

definition for truck tractor in 49 CFR 571.3(b) years ago,

52 and has not encountered any 

notable problems with its application. Nevertheless, because the NHTSA definition 

relies more on design intent than EPA’s proposed definition, we recognize that there may

be some questions regarding how the agencies would apply the NHTSA definition being 

finalized to certain unique vehicles. For example, many of the common automobile and 

boat transport trucks may look similar to tractors, but the agencies would not consider 

them to meet the definition, because they have the capability to carry one or several 

vehicles as cargo with or without a trailer attached, and therefore are not “constructed as 

to carry a load other than a part of the weight of the vehicle and the load so drawn.” 

Similarly, a “dromedary” style truck that has the capability to carry a large load of cargo 

with or without drawing a trailer would also not qualify as a tractor. 53 Even though these 

particular vehicles identified could potentially draw other motor vehicles like a trailer, 

they have also been designed to carry cargo with or without the trailer attached. NHTSA 

has previously interpreted its definition for “truck tractor” as excluding these specific 

vehicles like the dromedary and automobile/boat transport vehicles. Tow trucks have 

also been excluded from the category of truck tractor. On the other hand, it is worth 

clarifying that designs that allow cargo to be carried in the passenger compartment, the 

sleeper compartment, or external toolboxes would not exclude a vehicle from the tractor 

 

52 33 FR 19703, December 25, 1968.

53 A dromedary is a box, deck or plate mounted behind the cab to carry freight or cargo.
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category. The agencies plan to continue with this approach for the HD fuel efficiency

and GHG standards, which means that these particular vehicles will be subject to the 

vocational vehicle standards and not the tractor standards, but vehicles that did meet the 

definition above for “tractor” will be subject to the combination tractor standards. 

In response to the second comment, the agencies have decided not to classify

vocational vehicles with sleeper cabs as tractors. In the NPRM, the agencies proposed 

that vocational vehicles with sleeper cabs be classified as tractors out of concern that a 

vehicle could initially be manufactured as a straight truck vocational vehicle with a 

sleeper cab and, soon after introduction into commerce, be converted to a combination 

tractor as a means to circumvent the Class 8 sleeper cab regulations. Commenters who 

addressed this issue generally disagreed with the agencies’ concern. EMA/TMA, for 

example, argued that it is expensive and difficult for a manufacturer to change a vehicle 

from a straight truck to a tractor, because of modifications required to the vehicle, such as

to the vehicle’s air brake system, and also because of the manufacturers ultimate 

responsibility for recertification to NHTSA’s safety standards. EMA/TMA also argued 

that straight trucks are often built with sleeper cabs to perform the functions of a 

vocational type vehicle and not the functions of a line-haul tractor. NTEA also provided 

an example of a straight truck (Expediter Cab) that can be built with a sleeper cab and a 

cargo-carrying body, which it argued should be classified as a vocational vehicle and not 

a tractor. 

Upon further consideration, the agencies agree that vocational vehicles with 

sleeper cabs are more appropriately classified as vocational vehicles than as tractors. The 

comments discussed above help to illustrate the reasons for building a vocational vehicle

with a sleeper cab and the difficulties of converting a straight truck to a tractor. 

Moreover, 49 U.S.C. Chapter 301 requires any service organization making such 

modifications to be responsible for recertification to all applicable Federal motor vehicle 

safety standards, which should act as a further deterrent to anyone contemplating making 

such a conversion. Together these two items address the agencies’ primary reason for 

proposing the requirement that all vehicles with sleeper cabs be treated as tractors – the 

concern of circumvention of the tractor standards. However, the agencies will continue 

to monitor whether it appears that the definitions are creating unintended consequences, 

and may consider revising the definitions in a future rulemaking to address such issues

should any arise. NHTSA and EPA have concluded that the engine and tire 

improvements required in the vocational category are appropriate for this set of vehicles 

based on the typical operation of these vehicles. The agencies did not intend to include 

vocational vehicles with sleeper cabs, such as an Expediter vehicle, into the tractor 

category in either the NPRM or in this final action, and the agencies’ analyses at proposal 

reflected this intention. Therefore the agencies did not make any adjustments to the 

program costs and benefits due to this classification change. 

In response to the third comment, the agencies have decided to allow 

manufacturers to exclude certain vocational-type of tractors from the combination tractor 

standards and instead be subject to the vocational vehicle standards. We discuss below 

the reasoning underlying this decision, the criteria manufacturers would use in asserting a 
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claim that a vocational tractor should be reclassified as a vocational vehicle, and the 

procedures the agencies will use to accept or reject manufacturers’ claims. 

Multiple commenters (Allison Transmission, ATA, CALSTART, Eaton, 

EMA/TMA, National Solid Waste Management Association, MEMA, Navistar, NADA, 

RMA, and Volvo) argued that the agencies’ proposed classification failed to recognize 

genuine differences between vocational tractors, which typically operate at lower speeds 

in stop-and-go city driving, and line-haul tractors, which typically operate at highway

speeds on interstate roadways over long distances. Commenters argued that the proposed 

tractor standards and associated tractor GEM test cycles were derived based primarily

upon the operational characteristics of the line-haul tractors, and that technologies that 

apply to these line-haul tractors, such as improved aerodynamics, vehicle speed limiters 

and automatic engine shutdown, as well as engine performance for improving emissions 

and fuel consumption, do not have the same positive impact on fuel consumption when 

used on tractors In today’s market, as mentioned by Volvo and ATA, we understand that 

approximately 15 percent, or approximately 15,000 to 20,000, of the Class 7 and 8 

tractors could be classified as vocational tractors based upon the work they perform.

The agencies agree that the overall operation of these vocational-types of tractors 

resembles other vocational vehicles’ operation: lower average speed and more stop and 

go activity than line-haul tractors. Due to their operation style, a FTP certified engine is a 

better match for these tractors than a SET certified engine, because the FTP cycle uses a 

lower average speed and more stop and go activity than the SET cycle. In addition, the 

limited high speed operation leads to minimal opportunities for fuel consumption and 

CO2 emissions reductions due to aerodynamic improvements. Conversely, the additional 

weight of the aerodynamic components could cause an unintended consequence of 

increasing gram per ton-mile emissions by reducing the amount of payload the vehicle 

can carry in those applications which are weight-limited. Similarly, the vocational 

tractors typically do not hotel overnight and therefore will have little to no benefit 

through the installation of an idle reduction technology. 

The agencies received several other comments that described criteria that could be 

used to distinguish between vocational and non-vocational tractors. Volvo suggested that

a tractor could be a vocational tractor if it meets three of five specified features: 

(1) a frame Resisting Bending Moment (RBM) greater than or equal to 

2,000,000 in-lbs per rail, or rail and liner combination; 

(2) an approach angle greater than or equal to 20 degrees nominal design 

specification, to exclude extended front rails/bumpers for additional equipment 

(e.g. – pumps, winch, front engine PTO); 

(3) ground clearance greater than or equal to 14 inches as measured 

unladen from the lowest point of any frame rail or body mounted components, 

excluding axles and suspension (for HHD and MHD vehicles this is usually 

considered as the lowest point of the fuel tank/mounting or chassis aerodynamic 

devices); 
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(4) a total reduction in high gear greater than or equal to 3.00:1; and 

(5) a total reduction in low gear greater than or equal to 57:1. 

The approach proposed by Volvo is somewhat similar to the approach NHTSA 

has for determining if a vehicle is a light truck under the light vehicle CAFE program, in 

which a vehicle must either have a GVWR greater than 6,000 pounds or have 4-wheel 

drive, and meet four of the five specified suspension characteristics (approach angle, 

break-over angle, axle clearance, etc.) to be classified as a light truck. Although we do 

not believe that the criteria suggested by Volvo are workable for all manufacturers and all 

applications, we agree that these criteria would reflect a reasonable basis for allowing 

manufacturers to reclassify their vehicles as vocational tractors.

Two other commenters, EMA/TMA and Navistar, suggested simply that the 

manufacturer should have the burden of establishing that a tractor is a vocational tractor 

to the agencies’ reasonable satisfaction. The commenters also suggested some factors 

that could be used to establish that a tractor is actually a “vocational tractor”, including: 

(1) a vehicle speed limiter set at 55 mph or less; 

(2) power take-off (PTO) controls; 

(3) extended front frame; 

(4) ground clearance greater than 14 in.; 

(5) an approach angle greater than 20 degrees; 

(6) frame RBM greater than 2,000,000 in-lbs.; and 

(7) a total gear reduction in low gear greater than 57 and a total gear reduction in 

top gear greater than 3.

The agencies believe that both suggested approaches have some merit. A rule 

based on specific criteria as suggested by Volvo could help to minimize the burden on 

both the manufacturers and the agencies, as manufacturer-written requests for approval 

and agency approvals of those requests would not be required for each vocational tractor 

determination whereas the EMA/TMA and Navistar approach requires the opposite 

namely that each manufacturer would have to justify the determination of each vocational 

tractor based upon its related design features in a separate petition to the agencies. 

Neither of the two approaches, which are based on specific criteria, could be used to 

identify all the tractors that should be classified as vocational tractors. An urban 

beverage delivery tractor, for example, may not be designed with any of the features 

mentioned but is used in a vocational vehicle manner. Also, the agencies were concerned 

about the possibility of manufacturers circumventing the system by incorporating design 

changes to their line-haul tractors in order to classify them as vocational tractors required 

to meet less stringent emission and fuel consumption standards. However, at this time 

the agencies do not believe that circumventing the system is likely, as most of these 

vocational tractors are built to order and will incorporate the design features required by 

the customer. Manufacturer vehicle offerings are designed or tailored to suit the 
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particular task of the consumer. The vehicle transport mission including vehicle type, 

gross vehicle weight, gross combination weight, body style and load handling 

characteristics, must be considered in the design process. Further, how the vehicle will 

be utilized, including operating cycles, operating environment and road conditions, is 

another important consideration in designing a vehicle to accomplish a particular task. 

The agencies agree that these criteria could also be used as part of a basis for 

classification. We also note that many of these vehicles have front axle weight ratings 

greater than 14,600 pounds. 

Although the agencies agree that these vocational tractors are operated differently

than line-haul tractors and therefore fit more appropriately into the vocational vehicle 

category, we need to ensure that only tractors that are truly vocational tractors are 

classified as such. Upon further consideration of the comments received the agencies 

have decided to allow manufacturers to exclude certain vocational-type tractors from the 

combination tractor standards, and instead be subject to the standards for vocational 

vehicles. A vehicle determined by the manufacturer to be a HHD vocational tractor 

would fall into the HHD vocational vehicle subcategory and be regulated as a vocational 

vehicle. Similarly, MHD which the manufacturer chooses to reclassify as vocational 

tractors will be regulated as a MHD vocational vehicle. Specifically, under the provision 

being finalized at 40 CFR 1037.630 and NHTSA’s regulation at 49 CFR 523.2 of today’s 

rules only the following three types of vocational tractors are eligible for reclassification

by the manufacturer:

(1) Low-roof tractors intended for intra-city pickup and delivery, such as those 

that deliver bottled beverages to retail stores.

(2) Tractors intended for off-road operation (including mixed service operation), 

such as those with reinforced frames and increased ground clearance.

(3) Tractors with a GCWR over 120,000 pounds.

As adopted in 40 CFR 1037.230(a)(1)(xiii), manufacturers will be required to 

group vocational tractors into a unique family, separate from other combination tractors 

and vocational vehicles. The provision being adopted in 40 CFR 1037.630 and 49 CFR 

535.8 requires the manufacturers to summarize in their applications their basis for 

believing that the vehicles are eligible for manufacturer reclassification as vocational 

tractors. EPA and NHTSA could ask for a more detailed description of the basis and 

EPA would deny an application for certification where it determines the manufacturer 

lacks an adequate basis for reclassification. The manufacturer would then have to 

resubmit a modified application to certify the vehicles in question to the tractor standards. 

Where we determine that a manufacturer is not applying this allowance in good faith, we 

may require that manufacturer to obtain preliminary approval before using this 

allowance. This would mean that a manufacturer would need to submit its detailed 

records to EPA and receive formal approval before submitting its application for 

certification. The agencies plan to monitor how manufacturers classify their tractor fleets 

and would reconsider the issue of vocational tractor classification in a future rulemaking 

if necessary.
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Because the difference between some vocational tractors and line-haul tractors is 

potentially somewhat subjective, we are also including an annual sales limit of 7,000 

vocational tractors per manufacturer (based on a three year rolling average) consistent 

with past production volumes of such vehicles. It is important to note, however, that we 

do not expect it to be common for manufacturers to be able to justify classifying 7,000 

vehicles as vocational tractors in a given model year.

Under the regulations being promulgated in 40 CFR 1037.630 and 49 CFR Part 

523.2, manufacturers will be required to keep records of how they determined that such 

vehicles qualify as vocational. These records would be more detailed than the description 

submitted in the applications. Typically, this would be a combination of records of the 

design features and/or purchasers of the vehicles. The agencies have analyzed the design 

features that reflect the special needs of these vocational tractors in the three areas noted 

above– mixed service, heavy haul, and urban delivery. Mixed service applications, such 

as construction trucks, typically require higher ground clearance and approach angle to 

accommodate non-paved roads. In addition, they often require frame rails with greater 

resisting bending moment (RBM) because of the terrain where they operate.

54

 The mixed 

service applications also sometimes require higher front axle weight ratings to 

accommodate extra loads and/or power take off systems for additional capability. Heavy

haul tractors are typically designed with frame rails with extra strength (greater RBM) 

and higher front axle weight ratings to accommodate the heavy payloads. Often the 

heavy haul tractors will also have higher ground clearance and greater approach angle for 

similar reasons as the mixed service applications. Lastly, heavy haul vehicles require a 

total gear reduction of 57:1 or greater to provide the torque necessary to start the vehicle 

moving. Urban delivery tractors, such as beverage haulers, have less defined design 

features that reflect their operational needs. These vehicles offer options which include 

high RBM rails and front axle weight ratings, but not all beverage trucks are specified 

with these options. The primary differentiation of these urban delivery tractors is their 

operation. For this final rulemaking, the agencies projected the costs and benefits of the 

program considering this provision. As detailed in RIA Section 5.3.2.2.1, the agencies 

assumed that approximately 20 percent of short-haul tractors sold in 2014 model year and 

beyond will be vocational tractors. As such, these vehicles will experience benefits 

reflective of a FTP-certified engine and tire rolling resistance improvement at the 

technology costs projected in the rules for vocational vehicles. 

(1) What is the form of the Class 7 and 8 Tractor CO2 Emissions and Fuel 

Consumption Standards?

As proposed, EPA and NHTSA are finalizing different standards for different 

subcategories of these tractors with the basis for subcategorization being particular tractor 

attributes. Attribute-based standards in general recognize the variety of functions 

 

54 The agencies have found based on standard truck specifications, that vehicles designed for significant 

off-road applications, such as concrete pumper and logging trucks have resisting bending moment greater 

than 2,100,000 lb-in. (ranging up to 3,580,000 lb-in.). The typical on highway tractors have resisting 

bending moment of 1,390,000 lb-in. An example line haul truck is the Mack Pinnacle which has a RBM of 

1,390,000 lb-in, as shown at 

http://www.macktrucks.com/assets/MackMarketing/Specifications/CXU6124x2PinAxleBack.pdf.
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performed by vehicles and engines, which in turn can affect the kind of technology that is 

available to control emissions and reduce fuel consumption, or its effectiveness. 

Attributes that characterize differences in the design of vehicles, as well as differences in 

how the vehicles will be employed in-use, can be key factors in evaluating technological 

improvements for reducing CO2 emissions and fuel consumption. Developing an 

appropriate attribute-based standard can also avoid interfering with the ability of the 

market to offer a variety of products to meet consumer demand. There are several 

examples of where the agencies have utilized an attribute-based standard. In addition to 

the example of the light-duty 2012-16 MY vehicle rule, in which the standards are based 

on the attribute of vehicle “footprint,” the existing heavy-duty highway engine standards 

for criteria pollutants have for many years been based on a vehicle weight attribute (Light 

Heavy, Medium Heavy, Heavy Heavy) with different useful life periods, which is a 

similar approach finalized for the engine GHG and fuel consumption standards discussed 

below. 

Heavy-duty combination tractors are built to move freight. The ability of a 

vehicle to meet a customer’s freight transportation requirements depends on three major 

characteristics of the tractor: the gross vehicle weight rating (which along with gross 

combination weight rating (GCWR) establishes the maximum carrying capacity of the 

tractor and trailer), cab type (sleeper cabs provide overnight accommodations for 

drivers), and the tractor roof height (to mate tractors to trailers for the most fuel-efficient 

configuration). Each of these attributes impacts the baseline fuel consumption and GHG 

emissions, as well as the effectiveness of possible technologies, like aerodynamics, and is 

discussed in more detail below. 

The first tractor characteristic to consider is payload which is determined by a 

tractor’s GVWR and GCWR relative to the weight of the tractor, trailer, fuel, driver, and 

equipment. Class 7 trucks, which have a GVWR of 26,001-33,000 pounds and a typical 

GCWR of 65,000 pounds, have a lesser payload capacity than Class 8 trucks. Class 8 

trucks have a GVWR of greater than 33,000 pounds and a typical GCWR of greater than 

80,000 pounds, the effective weight limit on the federal highway system except in states 

with preexisting higher weight limits. Consistent with the recommendation in the 

National Academy of Sciences 2010 Report to NHTSA,55 the agencies are finalizing a 

load-specific fuel consumption metric (g/ton-mile and gal/1,000 ton-mile) where the 

“ton” represents the amount of payload. Generally, higher payload capacity vehicles 

have better specific fuel consumption and GHG emissions than lower payload capacity 

vehicles. Therefore, since the amount of payload that a Class 7 vehicle can carry is less 

than the Class 8 vehicle’s payload capacity, the baseline fuel consumption and GHG 

emissions performance per ton-mile differs between the categories. It is consequently

reasonable to distinguish between these two vehicle categories, so that the agencies are 

finalizing separate standards for Class 7 and Class 8 tractors. 

The agencies are not finalizing a single standard for both Class 7 and 8 tractors 

based on the payload carrying capabilities and assumed typical payload levels of Class 8 

tractors alone, as that would quite likely have the perverse impact of increasing fuel 

 

55 See 2010 NAS Report, Note 21, Recommendation 2-1.
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consumption and greenhouse gas emissions. Such a single standard would penalize Class 

7 vehicles in favor of Class 8 vehicles. However, the greater capabilities of Class 8 

tractors and their related greater efficiency when measured on a per ton-mile basis are 

only relevant in the context of operations where that greater capacity is needed. For 

many applications such as regional distribution, the trailer payloads dictated by the goods 

being carried are lower than the average Class 8 tractor payload. In those situations, 

Class 7 tractors are more efficient than Class 8 tractors when measured by ton-mile of 

actual freight carried. This is because the extra capabilities of Class 8 tractors add 

additional weight to vehicles that is only beneficial in the context of its higher 

capabilities. The existing market already selects for vehicle performance based on the 

projected payloads. By setting separate standards the agencies do not advantage or 

disadvantage Class 7 or 8 tractors relative to one another and continue to allow trucking 

fleets to purchase the vehicle most appropriate to their business practices.

The second characteristic that affects fuel consumption and GHG emissions is the 

relationship between the tractor cab roof height and the type of trailer used to carry the 

freight. The primary trailer types are box, flat bed, tanker, bulk carrier, chassis, and low 

boys. Tractor manufacturers sell tractors in three roof heights – low, mid, and high. The 

manufacturers do this to obtain the best aerodynamic performance of a tractor-trailer 

combination, resulting in reductions of GHG emissions and fuel consumption, because it 

allows the frontal area of the tractor to be similar in size to the frontal area of the trailer. 

In other words, high roof tractors are designed to be paired with a (relatively tall) box 

trailer while a low roof tractor is designed to pull a (relatively low) flat bed trailer. The 

baseline performance of a high roof, mid roof, and low roof tractor differs due to the 

variation in frontal area which determines the aerodynamic drag. For example, the 

frontal area of a low roof tractor is approximately 6 square meters, while a high roof 

tractor has a frontal area of approximately 9.8 square meters. Therefore, as explained 

below, the agencies are using the roof height of the tractor to determine the trailer type 

required to be used to demonstrate compliance of a vehicle with the fuel consumption and 

CO2 emissions standards. As with vehicle weight classes, setting separate standards for 

each tractor roof height helps ensure that all tractors are regulated to achieve appropriate 

improvements, without inadvertently leading to increased emissions and fuel 

consumption by shifting the mix of vehicle roof heights offered in the market away from 

a level determined by market foces linked to the actual trailers vehicles will haul in-use.

Tractor cabs typically can be divided into two configurations – day cabs and 

sleeper cabs. Line haul operations typically require overnight accommodations due to 

Federal Motor Carrier Safety Administration hours of operation requirements.

56

 

Therefore, some truck buyers purchase tractor cabs with sleeping accommodations, also 

known as sleeper cabs, because they do not return to their home base nightly. Sleeper 

cabs tend to have a greater empty curb weight than day cabs due to the larger cab volume 

and accommodations, which lead to a higher baseline fuel consumption for sleeper cabs 

 

56 The Federal Motor Carrier Safety Administration’s Hours-of-Service regulations put limits in place for 

when and how long commercial motor vehicle drivers may drive. They are based on an exhaustive 

scientific review and are designed to ensure truck drivers get the necessary rest to perform safe operations. 

See 49 CFR part 395, and see also http://www.fmcsa.dot.gov/rules-regulations/topics/hos/index.htm (last 

accessed August 8, 2010).
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when compared to day cabs. In addition, there are specific technologies, such as 

extended idle reduction technologies, which are appropriate only for tractors which hotel 

-- such as sleeper cabs. To respect these differences, the agencies are finalizing separate 

standards for sleeper cabs and day cabs.57 

The agencies received comments from industry stakeholders (EMA, Allison 

Transmission, Bosch, and the Heavy-Duty Fuel Efficiency Leadership Group) and ICCT 

supporting the nine tractor regulatory subcategories proposed and did not receive any

comments which supported an alternate classification. Thus, to account for the relevant 

combinations of these attributes, the agencies are adopting the classification scheme 

proposed, segmenting combination tractors into the following nine regulatory

subcategories:

 Class 7 Day Cab with Low Roof

 Class 7 Day Cab with Mid Roof

 Class 7 Day Cab with High Roof

 Class 8 Day Cab with Low Roof

 Class 8 Day Cab with Mid Roof

 Class 8 Day Cab with High Roof

 Class 8 Sleeper Cab with Low Roof

 Class 8 Sleeper Cab with Mid Roof

 Class 8 Sleeper Cab with High Roof

Adjustable roof fairings are used today on what the agencies consider to be low 

roof tractors. The adjustable fairings allow the operator to change the fairing height to 

better match the type of trailer that is being pulled which can reduce fuel consumption 

and GHG emissions during operation. As proposed, the agencies are treating tractors with 

adjustable roof fairings as low roof tractors that will tested with the fairing in its lowest 

position. 

(2) What are the Final Class 7 and 8 Tractor and Engine CO2 Emissions and 

Fuel Consumption Standards and Their Timing?

In developing the final standards for Class 7 and 8 tractors and for the engines 

used in these tractors, the agencies have evaluated the current levels of emissions and fuel 

consumption, the kinds of technologies that could be utilized by truck and engine 

manufacturers to reduce emissions and fuel consumption from tractors and associated 

engines, the necessary lead time, the associated costs for the industry, fuel savings for the 

consumer, and the magnitude of the CO2 and fuel savings that may be achieved. The 

technologies on whose performance the final tractor standards are predicated are 

improvements in aerodynamic design, lower rolling resistance tires, extended idle 

reduction technologies, and lightweighting of the tractor. The technologies on whose 

 

57 The agencies note, as discussed in the previous section, that some day cabs and sleeper cabs will be 

reclassified as vocational tractors and if so will not be subject to the combination tractor standards.
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performance the final tractor standards are predicated are engine friction reduction, 

aftertreatment optimization, and turbocompounding, among others, as described in RIA 

Chapter 2.4. The agencies’ evaluation showed that these technologies are available 

today, but have very low application rates on current vehicles and engines. EPA and 

NHTSA also present the estimated costs and benefits of the Class 7 and 8 combination 

tractor and engine standards in Section III and in RIA Chapter 2, explaining as well the 

basis for the agencies’ conclusion not to adopt standards which are less stringent or more 

stringent.

(a) Tractor Standards

The agencies are finalizing the following standards for Class 7 and 8 combination 

tractors in Table II-1, using the subcategorization approach that was proposed. As 

explained below in Section III, EPA has determined that there is sufficient lead time to 

introduce various tractor and engine technologies into the fleet starting in the 2014 model 

year, and is finalizing standards starting for that model year predicated on performance of 

those technologies. EPA is finalizing more stringent tractor standards for the 2017 model 

year which reflect the CO2 emissions reductions required for 2017 model year engines. 

(As explained in Section II.B(3)(h)(v) below, engine performance is one of the inputs 

into the compliance model, and that input will change in 2017 to reflect the 2017 MY 

engine standards.) The 2017 MY vehicle standards are not premised on tractor 

manufacturers installing additional vehicle technologies. EPA’s final standards apply 

throughout the useful life period as described in Section V. As proposed, and as 

discussed further in Section IV below, manufacturers may generate and use credits from 

Class 7 and 8 combination tractors to show compliance with the standards. 

NHTSA is finalizing Class 7 and 8 tractor fuel consumption standards that are 

voluntary standards in the 2014 and 2015 model years and become mandatory beginning 

in the 2016 model year, as required by the lead time within EISA. The 2014 and 2015 

model year standards are voluntary in that manufacturers are not subject to them unless 

they opt-in to the standards.58 Manufacturers that opt in become subject to NHTSA 

standards for all regulatory categories. NHTSA is also adopting new tractor standards for 

the 2017 model year which reflect additional improvements in only the heavy-duty 

engines. As proposed, NHTSA is not implementing an in-use compliance program for 

fuel consumption because it does not anticipate that there will be notable deterioration of 

fuel consumption over the useful life of the vehicle. 

As explained more fully in Section III and Chapter 2 of the RIA, EPA and 

NHTSA are not adopting more stringent tractor standards for 2014-2017 MY. The final 

tractor standards are based on the maximum application rates of available technologies 

considering the available lead time, and we explain in Section III and Chapter 2 of the 

RIA that use of additional technologies, or further application of the technologies already 

mentioned would be either infeasible in the lead time afforded, or uneconomic. 

 

58 Once a manufacturer opts into the NHTSA program it must stay in the program for all the optional MYs.
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Table II-1: Heavy-duty Combination Tractor Emissions and Fuel Consumption Standards

2014 Model Year CO2 Grams per Ton-Mile

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 107 81 68

Mid Roof 119 88 76

High Roof 124 92 75

2014-2016 Model Year Gallons of Fuel per 1,000 Ton-Mile59

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 10.5 8.0 6.7

Mid Roof 11.7 8.7 7.4

High Roof 12.2 9.0 7.3

2017 Model Year CO2 Grams per Ton-Mile

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 104 80 66

Mid Roof 115 86 73

High Roof 120 89 72

2017 Model Year and Later Gallons of Fuel per 1,000 Ton-Mile

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 10.2 7.8 6.5

Mid Roof 11.3 8.4 7.2

High Roof 11.8 8.7 7.1

The standard values shown above differ somewhat from the proposal, reflecting 

refinements made to the GEM in response to comments. For example, the agencies 

received comments from stakeholders concerned that the 2017 MY tractor standards 

appeared to be backsliding because the reductions were not in line with the reductions 

expected from the 2017 MY engine standards. The agencies reviewed the issue and 

found that the engine maps we created in the GEM for the 2017 model year for the 

proposal did not appropriately reflect the engine improvements. Therefore, the agencies 

developed new fuel maps for the GEM v2.0 which fully reflect the engine improvements 

due to the 2017 MY standards.60 These changes to the GEM did not impact our estimates 

of the relative effectiveness of the greenhouse gas emissions and fuel consumption 

improving technologies modeled in this final action nor the overall cost or benefits 

estimated for these final vehicle standards. 

 

59 As noted above, manufacturers may voluntarily opt-in to the NHTSA fuel consumption program in 2014 

or 2015. Once a manufacturer opts into the NHTSA program it must stay in the program for all the 

optional MYs. 

60 See RIA Chapter 4 for the engine fuel maps used in GEM v2.0.
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Based on our analysis, the 2017 model year standards for combination tractors 

and engines represent up to a 23 percent reduction in CO2 emissions and fuel 

consumption over a 2010 model year baseline tractor (the baseline sleeper cab does not 

include idle shutdown technology), as detailed in Section III.A.2.In considering the 

feasibility of vehicles to comply with the standards, EPA also considered the potential for 

CO2 emissions to increase during the regulatory useful life of the product. As we discuss 

separately in the context of deterioration factor (DF) testing, we have concluded that CO2

emissions are likely to stay the same or actually decrease in-use compared to new 

certified configurations. In general, engine and vehicle friction decreases as products 

wear in leading to reduced parasitic losses and lower CO2 emissions. Similarly, tire 

rolling resistance falls as tires wear due to the reduction in tread height. In the case of 

aerodynamic components, we project no change in performance through the regulatory 

life of the vehicle since there is essentially no change in their physical form as vehicles 

age. Similarly, weight reduction elements such as aluminum wheels are not projected to 

increase in mass through time, and hence, we can conclude will not deteriorate with 

regard to CO2 performance in-use. Given all of these considerations, EPA is confident in 

projecting that the standards finalized today will be technical feasible throughout the 

regulatory useful life of the program.

(b) Standards for Engines Installed in Combination Tractors

EPA is adopting GHG standards and NHTSA is adopting fuel consumption 

standards for new heavy-duty engines. This section discusses the standards for engines 

used in Class 7 and 8 combination tractors and also provides some overall background 

information. We also note that the agencies are adopting standards for heavy-duty 

engines used in vocational vehicles. However, as explained further below, compliance 

with the standards would be measured using different test procedures, corresponding with 

actual vehicle use, depending on whether the vehicle in which the engine is installed is a 

Class 7 and 8 combination tractor or a vocational vehicle. 

The heavy-duty engine standards vary depending on the type of vehicle in which 

they are installed, as well as whether the engines are compression ignition or spark 

ignition. The agencies are adopting separate engine fuel consumption and GHG 

emissions standards for engines installed in combination tractors versus engines installed 

in vocational vehicles. Also, for the purposes of the GHG engine emissions and engine 

fuel consumption standards, the agencies are adopting engine subcategories that match 

EPA’s existing criteria pollutant emissions regulations for heavy-duty highway engines 

which established four regulatory service classes that represent the engine’s intended and 

primary vehicle application.61 The Light Heavy-Duty (LHD) diesel engines are intended 

for application in Class 2b through Class 5 trucks (8,501 through 19,500 pounds GVWR). 

The Medium Heavy-Duty (MHD) diesel engines are intended for Class 6 and Class 7 

trucks (19,501 through 33,000 pounds GVWR). The Heavy Heavy-Duty (HDD) diesel 

engines are primarily used in Class 8 trucks (33,001 pounds and greater GVWR). Lastly, 

spark ignition engines (primarily gasoline-powered engines) installed in incomplete 

vehicles less than 14,000 pounds GVWR and spark ignition engines that are installed in 

 

61 See 40 CFR 86.90-2.
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all vehicles (complete or incomplete) greater than 14,000 pounds GVWR are grouped 

into a single engine service class. The engines in these four regulatory service classes 

range in size between approximately five liters and sixteen liters. This subcategory

structure enables the agencies to set standards that appropriately reflect the technology

available for engines installed in each type of vehicle, and that are therefore 

technologically feasible for these engines. This is the same engine classification scheme 

the agencies proposed, and there were no adverse comments in response to the proposal.

Heavy heavy-duty diesel and medium heavy-duty diesel engines are used today in 

combination tractors. The following section refers to the engine standards for these types 

of engines. This section does not cover gasoline or light heavy-duty diesel engines

because they are not used in combination tractors.

In the NPRM, the agencies proposed CO2 and fuel consumption standards for HD 

diesel engines to be installed in Class 7 and 8 combination tractors as shown in Table II2.62

Table II-2: Proposed Heavy-duty Diesel Engine Standards for Engines Installed in Tractors

Effective 2014 Model Year Effective 2017 Model Year

CO2 standard 

(g/bhp-hr)

Voluntary Fuel 

Consumption 

Standard 

(gal/100 bhp-hr)

CO2 standard 

(g/bhp-hr)

Fuel 

Consumption 

Standard 

(gal/100 bhp-hr)

MHD diesel 

engine

502 4.93 487 4.78

HHD diesel 

engine

475 4.67 460 4.52

The agencies proposed to require diesel engine manufacturers to achieve, on 

average, a three percent reduction in fuel consumption and CO2 emissions for the 2014 

standards over the baseline MY 2010 performance for the engines.63 The agencies’ 

preliminary assessment of the findings of the 2010 NAS Report and other literature 

sources indicated that there are technologies available to reduce fuel consumption by this 

amount in the time frame in the lead time provided by the rules. These technologies 

include improved turbochargers, aftertreatment optimization, and low temperature 

exhaust gas recirculation. 

The agencies also proposed to require diesel engine manufacturers to achieve, on 

average, a six percent reduction in fuel consumption and CO2 emissions for the 2017 MY 

 

62 The agencies note that the CO2 and fuel consumption standards for Class 7 and 8 combination tractors do

not cover gasoline or LHDD engines, as those are not used in Class 7 and 8 combination tractors.

63 The baseline HHD diesel engine performance in MY 2010 on the SET is 490 g CO2/bhp-hr (4.81 gal/100 

bhp-hr), as determined from confidential data provided by manufacturers and data submitted for the nonGHG emissions certification process. The baseline MHD diesel engine performance on the SET cycle is 

518 g CO2/bhp-hr (5.09 gallon/100-bhp-hr) in MY 2010. Further discussion of the derivation of the 

baseline can be found in Section III. 
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standards over the baseline MY 2010 performance for MHD and HHD diesel engines 

required to use the SET-based standard. The agencies stated that additional reductions 

could likely be achieved through the increased refinement of the technologies projected 

to be implemented for 2014, plus the addition of turbocompounding, which the agencies’ 

analysis showed would require a longer development time and would not be available in

MY 2014. The agencies therefore proposed to provide additional lead time to allow for 

the introduction of this additional technology, and to wait until 2017 to increase 

stringency to levels reflecting application of this technology.

The agencies proposed that the MHD and HHD diesel engine CO2 standards for 

Class 7 and 8 combination tractors would become effective in MY 2014 for EPA, with 

more stringent CO2 standards becoming effective in MY 2017, while NHTSA’s fuel 

consumption standards would become effective in MY 2017, which would be both 

consistent with the EISA four-year minimum lead-time requirements and harmonized 

with EPA’s timing. The agencies explained that the three-year timing, besides being 

required by EISA, made sense because EPA’s heavy-duty highway engine program for 

criteria pollutants had begun to provide new emissions standards for the industry in three 

year increments, which had caused the heavy-duty engine product plans to fall largely 

into three year cycles reflecting this regulatory environment. To further harmonize with 

EPA, NHTSA proposed voluntary fuel consumption standards for MHD and HHD diesel 

engines that are equivalent to EPA CO2 standards for MYs 2014-2016, allowing

manufacturers to opt into the voluntary standards in any of those model years.64 NHTSA 

proposed that manufacturers could opt into the program by declaring their intent to opt in 

to the program at the same time they submit the Pre-Certification Compliance Report,

and that a manufacturer opting into the program would begin tracking credits and debits 

beginning in the model year in which they opt into the program. Both agencies proposed 

to allow manufacturers to generate and use credits to achieve compliance with the HD 

diesel engine standards, including averaging, banking, and trading (ABT) and deficit 

carry-forward. The agencies sought comment on the proposed MHD and HHD engine 

standards and timing.

The agencies received comments from EMA, Navistar, Cummins, ACEEE, 

Center for Biological Diversity, Detroit Diesel Corporation, American Lung Association, 

and the Union of Concerned Scientists. Comments were divided with respect to the 

proposed levels of stringency. While Cummins and DDC expressed support for the CO2

and fuel consumption standards for diesel engines, and EMA and Navistar stated the 

standards could be met if the flexibilities outlined in the NPRM are finalized as proposed, 

Navistar also stated that the model year 2017 standard may not be feasible since what the 

agencies characterized as existing technologies are not in production for all 

manufacturers In contrast, environmental groups and NGOs stated that the standards did 

not reflect the potential reductions outlined in the 2010 NAS study and should be more 

stringent. CBD argued that the standards were not set at the maximum feasible level by

definition, because the agencies had said that they were based on the use of existing 

 

64 Once a manufacturer opts into the NHTSA program it must stay in the program for all the optional MYs 

and remain standardized with the implementation approach being used to meet the EPA emission program.
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technologies. In addition, the Center for Neighborhood Technology encouraged the 

agencies to implement the rules as soon as possible, beginning in the 2012 model year. 

In light of the above comments, the agencies re-evaluated the technical basis for 

the heavy-duty engine standards. The baseline HHD diesel engine performance in 2010 

model year on the SET is estimated at 490 g CO2/bhp-hr (4.81 gal/100 bhp-hr), based on 

our analysis of confidential data provided by manufacturers and data submitted for the 

non-GHG emissions certification process. Similarly, the baseline MHD diesel engine 

performance on the SET cycle is estimated to be 518 g CO2/bhp-hr (5.09 gallon/100-bhphr) for the 2010 model year. Further discussion of the derivation of the baseline can be 

found in Section III. The agencies believe that the MY 2014 standards can be achieved 

by most manufacturers through the use of technologies time frame such as improved 

aftertreatment systems, friction reduction, improved auxiliaries, turbochargers, pistons, 

and other components. These standards will require diesel engine manufacturers to 

achieve on average a three percent reduction in fuel consumption and CO2 emissions over 

the baseline 2010 model year levels. 

However, in recognizing that some manufacturers have engines that would not 

meet the standard even after applying technologies that improve GHG emissions and fuel 

consumption by three percent, the agencies are finalizing both the proposed ABT 

provisions for these engines and also an optional alternate engine standard for 2014 

model year, described in more detail below. We believe that concerns expressed by

Navistar regarding the 2014 MY standards will be addressed by this alternative standard. 

The agencies also continue to believe that the 2017 MY standards are achievable using 

the above approaches and, in the case of SET certified engines, turbocompounding. 

While Navistar commented that the 2017 MY standard may be challenging because not 

all manufacturers are presently producing the technologies that may be required to meet 

the standards, the agencies believe that since manufacturers that may require 

turbocompounding to meet the standards will not have to do so until 2017 MY, there will 

be sufficient lead time for all manufacturers to introduce this technology. As noted 

above, by MY 2017 all MHD and HHD engines installed in combination tractors should 

have gone through a redesign during which all needed technology can be applied. We 

note that we are finalizing these standards as proposed based on the assessment that most 

manufacturers (not just Navistar) will need to make improvements to existing engine 

systems in order to meet the standards. EPA’s HD diesel engine CO2 emission standards 

and NHTSA’s HD diesel engine fuel consumption standards for engines installed in 

tractors are presented in Table II-3. As explained above, the first set of standards take 

effect with MY 2014 (mandatory standards for EPA, voluntary standards for NHTSA), 

and the second set take effect with MY 2017 (mandatory for both agencies). 
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Table II-3 Final Heavy-duty Diesel Engine Standards for Engines Installed in Tractors

Effective 2014 Model Year Effective 2017 Model Year

CO2 standard 

(g/bhp-hr)

Voluntary Fuel 

Consumption 

Standard 

(gal/100 bhp-hr)

CO2 standard 

(g/bhp-hr)

Fuel 

Consumption 

Standard 

(gal/100 bhp-hr)

MHD diesel 

engine

502 4.93 487 4.78

HHD diesel 

engine

475 4.67 460 4.52

The agencies have also decided to remove NHTSA’s proposed Pre-Certification 

Compliance Report requirement. Instead, manufacturers must submit their decision to opt

into NHTSA’s voluntary standards for the 2014 through 2016 model years as part of its 

certification process with EPA. Once a manufacturer opts into the NHTSA program it 

must stay in the program for all the subsequent optional model years. Manufacturers that 

opt in become subject to NHTSA standards for all regulatory categories. The declaration 

statement must be entered prior to or at the same time the manufacturer submits its first 

application for a certificate of conformity. NHTSA will begin tracking credits and debits 

beginning in the model year in which a manufacturer opts into its program.

Compliance with the CO2 emissions and fuel consumption standards will be 

evaluated based on the SET engine test cycle. In the NPRM, the agencies proposed 

standards based on the SET cycle for MHD and HHD engines used in tractors due to 

these engines’ primary use in steady state operating conditions (typified by highway

cruising). Tractors spend the majority of their operation at steady state conditions, and 

will obtain in-use benefit of technologies such as turbocompounding and other waste heat 

recovery technologies during this kind of typical engine operation. Therefore, the 

engines installed in tractors will be required to meet the standard based on the SET, 

which is a steady state test cycle. 

The agencies gave full consideration to the need for engine manufacturers to 

redesign and upgrade their engines during the MYs 2014-2017 to meet standards, and 

fully considered the cost-effectiveness of the standards and the available lead time. The 

final two-step CO2 emission and fuel consumption standards recognize the opportunity

for technology improvements over the rulemaking time frame, while reflecting the typical 

engine manufacturers’ product plan cycles. Over these four model years there will be an 

opportunity for manufacturers to evaluate almost every one of their engine models and 

add technology in a cost-effective way, consistent with existing redesign schedules, to 

control GHG emissions and reduce fuel consumption. The time-frame and levels for the 

standards, as well as the ability to average, bank and trade credits and carry a deficit 

forward for a limited time, are expected to provide manufacturers the time and 

flexibilities needed to incorporate technology that will achieve the final GHG and fuel 

consumption standards within the normal engine redesign process. This is an important 

aspect of the final rules, as it will avoid the much higher costs that would occur if 

manufacturers needed to add or change technology at times other than these scheduled 
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redesigns.65 This time period will also provide manufacturers the opportunity to plan for 

compliance using a multi-year time frame, again in alignment with their normal business 

practice. Further details on lead time, redesigns and technical feasibility can be found in 

Section III.

The agencies continue to believe the standards for MHD and HHD diesel engines 

installed in combination tractors are the most stringent technically feasible in the time 

frame established in this regulation. The standards will require a 3 percent reduction in 

engine fuel consumption and GHG emissions in 2014 MY based on improvements to 

engine components and aftertreatment systems. The 2017 MY standards will require a 6 

percent reduction in fuel consumption and GHG emissions over a 2010 model year 

baseline and assumes the introduction, for some engines, of technologies such as 

turbocompounding. The standards, however, are not premised on the introduction of 

technologies that are still in development – such as Rankine bottoming cycle - since these 

approaches cannot be introduced without further technical development or engine redesign.66

Additional discussion on technical feasibility is included in Section III below and 

in Chapter 2 of the RIA.

The agencies recognize, however, that the schedule of changes for the final 

standards may not be the most cost-effective one for all manufacturers. The agencies 

also sought comment as to whether an alternate phase-in schedule for the HD diesel 

engine standards for combination tractors should be considered. In developing the 

proposal, heavy-duty engine manufacturers stated that the phase-in of the GHG and fuel 

consumption standards should be aligned with the On Board Diagnostic (OBD)67 phasein schedule, which includes new requirements for heavy-duty vehicles in the 2013 and 

2016 model years. The agencies did not adopt this suggestion in the proposal, explaining 

that the credit averaging, banking and trading provisions would provide manufacturers 

with considerable flexibility to manage their GHG and fuel efficiency standard 

compliance plans – including the phase-in of the new heavy-duty OBD requirements –

but requested comment on whether EPA and NHTSA should provide an alternate phasein schedules that would more explicitly accommodate this request in the event that 

manufacturers did not agree that the ABT provisions mitigated their concern about the 

GHG/fuel consumption standard phase-in. See 75 FR at 74178.

In response, Cummins, Engine Manufacturers Association, and DTNA 

commented that their first choice was a delay in the OBD effective date for one year to 

the 2014 model year. The industry’s second choice was to provide manufacturers with an 

optional GHG and fuel consumption phase-in that aligns their product development plans 

with their current plans to meet the OBD regulations for EPA and California in the 2013 

 

65 See 75 FR at 25467-68 for further discussion of the negative cost implications of establishing 

requirements outside of the redesign cycle. 

66 See RIA Chapter 2.4.2.7.

67 On-board diagnostics (OBD) is a computer-based emissions monitoring system that was first required in 

2007 for vehicles under 14,000 pounds (65 FR 59896, Oct. 6, 2000) and in 2010 for vehicles over 14,000

pounds (74 FR 8310, Feb. 24, 2009).
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and 2016 model years. These commenters argued that meeting the OBD regulation in the 

2013 model year already poses a significant challenge, and that having to meet GHG and 

fuel consumption standards beginning in 2014 could require them to redesign and 

recertify their products just one year later. They argued that bundling design changes 

where possible can reduce the burden on industry for complying with regulations, so 

aligning the introduction of the OBD, GHG, and fuel consumption standards could help 

reduce manufacturers’ burden for product development, validation and certification.

In order to provide additional flexibility for manufacturers looking to align their 

technology changes with multiple regulatory requirements, the agencies are finalizing an 

alternate “OBD phase-in” option for meeting the standards for MHD and HHD diesel 

engines installed in tractors (in addition to engines installed in vocational vehicles as 

noted below in Section II.D), which delivers equivalent CO2 emissions and fuel 

consumption reductions as the primary standards for the engines built in the 2013 through 

2017 model years, as shown in Table II-4. The optional OBD phase-in schedule requires 

that engines built in the 2013 and 2016 model years to achieve greater reductions than the 

engines built in those model years under the primary program, but requires fewer 

reductions for the engines built in the 2014 and 2015 model years. 

Table II-4: Comparison of CO2 reductions for the HHD and MHD Tractor Standards Under the 

Alternative OBD Phase-in and Primary Phase-In

HHD Tractor Engines MHD Tractor Engines

Primary 

Phase-in 

Standard 

(g/bhp-hr)

Optional 

Phase-in 

Standard 

(g/bhp-hr)

Difference 

in Lifetime 

CO2 Engine 

Emissions 

(MMT)

Primary 

Phase-in 

Standard 

(g/bhp-hr)

Optional 

Phase-in 

Standard 

(g/bhp-hr)

Difference in

Lifetime CO2

Engine Emissions 

(MMT)

Baseline 490 490 -- 518 518 --

2013 MY 

Engine

490 485 14 518 512 17

2014 MY 

Engine

475 485 -28 502 512 -28

2015 MY 

Engine

475 485 -28 502 512 -28

2016 MY 

Engine

475 460 42 502 487 42

2017 MY 

Engine

460 460 0 487 487 0

Net Reductions 

(MMT)

0 3

The technologies for the 2013 model year optional standard include a subset of 

technologies that could be used to meet the primary 2014 model year standard. The 

agencies believe this approach is appropriate because the shorter lead time provided for 

manufacturers selecting this option limits the technologies which can be applied. 

However, in order to maintain equivalent CO2 emissions and fuel consumption reduction 

over the 2013 through 2017 model year period, it is necessary for the 2016 model year 
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standard to be equal to the 2017 model year standard, using the same technology paths 

described for the primary engine program. If a manufacturer selects this optional phasein, then the engines must be certified starting in the 2013 model year and continue using 

this phase-in through 2016 model year. That is, once electing this compliance path, 

manufacturers must adhere to it.68 Manufacturers may opt into the optional OBD phasein through the voluntary NHTSA program, but must opt in in the 2013 model year and 

continue using this phase-in through the 2016 model year. Manufacturers that opt in to 

the voluntary NHTSA program in 2014 and 2015 will be required to meet the primary

phase-in schedule and may not adopt the OBD phase-in option. Table II-5 below 

presents the final HD diesel engine CO2 emission standards under the “OBD phase-in” 

option.

Table II-5: Optional Heavy-Duty Engine Standard Phase-in Schedule for Tractor Engines

Effective 2013 Through 2015 Model Year

MHD Diesel 

Engine

HHD Diesel 

Engine

CO2 Standard (g/bhp-hr) 512 485

Voluntary Fuel Consumption Standard 

(gallon/100 bhp-hr)

5.03 4.76

Effective 2016 Model Year and Later

MHD Diesel 

Engine

HHD Diesel 

Engine

CO2 Standard (g/bhp-hr) 487 460

Fuel Consumption (gallon/100 bhp-hr) 4.78 4.52

Although the agencies believe that the standards for the HD diesel engines 

installed in combination tractors are generally appropriate, cost-effective, and 

technologically feasible in the rulemaking time frame, we also recognize that when 

regulating a category of engines for the first time, there will be individual products that 

may deviate significantly from the baseline level of performance, whether because of a 

specific approach to criteria pollution control, or due to engine calibration for specific 

applications or duty cycles. In the current fleet of 2010 and 2011 model year engines

used in combination tractors, NHTSA and EPA understand that there is a relatively small 

group of legacy engines that are up to approximately 25 percent worse than the average 

baseline for other engines. For this group of legacy MHD and HHD diesel engines

installed in tractors, when compared to the typical performance levels of the majority of 

the engines in the fleet and the fuel consumption/GHG emissions reductions that the 

majority of engines would achieve through increased application of technology, the same 

reduction from the industry baseline may not be possible at reasonably comparable cost 

given the same amount of lead-time, because these products may require a total redesign 

in order to meet the standards. Manufacturers of the MHD and HHD diesel engines 

installed in tractors with atypically high baseline CO2 and fuel consumption levels may

 

68 See §1036.150(e).
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also, in some instances, have a limited line of engines across which to average 

performance to meet the generally-applicable standards. 

To account for this possibility, the agencies requested comment in the NPRM on 

the establishment of an optional alternative MHD and HHD engine standard for those 

engines installed in combination tractors which would be set at 3 percent below a 

manufacturer’s 2011 engine baseline emissions and fuel consumption, or alternatively, at 

2 percent below a manufacturer’s 2011 baseline. The agencies also requested comment 

on extending this optional standard one year (to the 2017 MY) for a single engine family 

at a 6 percent level below the 2011 baseline.69 This option would not be available unless 

and until a manufacturer had exhausted all available credits and credit opportunities, and 

engines under the optional standard could not generate credits. 

In comments to the NPRM, Navistar supported the alternative engine standard, 

but recommended that it be set at 2 percent below the manufacturer’s 2011 baseline. 

They also supported the extension to 2017 MY at 6 percent. Navistar provided CBI in 

support of its comments. Volvo, DTNA, environmental groups, NGOs, and the New 

York State Department of Environmental Conservation opposed the optional engine 

standard, arguing that existing flexibilities are sufficient to allow compliance with the 

standards and that all manufacturers should be held to the same standards. 

Based on the CBI submitted by Navistar, the agencies found that a large majority

of the HD diesel engines used in Class 7 and 8 combination tractors were relatively close 

to the average baseline, with some above and some below, but also that some legacy

MHD and HDD diesel engines were far enough away from the baseline that they could 

not meet the generally-applicable standards with application of technology that would be 

available for those specific engines by 2014. The agencies continue to believe that an 

interim alternative standard is needed for these products, and that an interim standard 

reflects a legitimate difference between products starting from different fuel 

consumption/GHG emitting baselines. As explained in the proposal, it is legally 

permissible to accommodate short term lead time constraints with alternative standards. 

Commenters did not dispute that there are legacy engine families with significantly

higher CO2 emissions and fuel consumption baselines, and that these engines require 

longer lead time to meet the principal standards in the early model years of the program. 

Although the agencies acknowledge the view that all manufacturers should be subject to 

the same burden for meeting the primary standards, the agencies believe that, in the initial 

years of a new program, additional flexibilities should be provided. The GHG standards 

and fuel consumption standards are first-time standards for these engines, so the 

possibility of significantly different baselines is not unexpected.70 Moreover, the 

agencies do not believe that the alternative standard affords a relative competitive 

advantage to the higher emitting legacy engines: the same level of improvement at the 

same cost will be required of those tractor engines, and in addition, by 2017 MY, those 

tractor engines will be required to make the additional improvements to meet the same 

standards as other engines. We believe that the concern expressed by Navistar regarding 

 

69 See 75 FR at 74178-74179.

70See 75 FR at 74178. 
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the 2014 MY standards will be addressed by this alternative. The agencies also continue 

to believe the 2017 MY standards are achievable using the above approaches and, in the 

case of MHD and HHD engines installed in tractors, turbocompounding. While Navistar 

commented that the 2017 MY standard may be challenging, the agencies believe that 

since manufacturers which may need to use turbocompounding to meet the standards will 

not have to do so until 2017 MY, there will be sufficient lead time for all engine 

manufacturers to introduce this technology. Thus, the agencies are finalizing a regulatory

alternative whereby a manufacturer, for an interim period of the 2014-2016 model years,

would have the option to comply with a unique standard based on a three percent 

reduction from an individual engine’s own 2011 model year baseline level. Our 

assessment is that this three percent reduction is appropriate given the potential for 

manufacturers to apply similar technology packages with similar cost to what we have 

estimated for the primary program. This is similar to EPA’s approach in the light-duty 

rule for handling a certain subset of vehicles that were deemed unable to meet the 

generally-applicable GHG standards during the 2012-2015 time frame due to higher 

initial baseline conditions, and which therefore needed alternate standards in those model 

years.71 

The agencies stress that this is a temporary and limited option being implemented

to address diverse manufacturer needs associated with complying with this first phase of 

the regulations. As codified in 40 CFR 1036.620 and 49 CFR 535.5(d), this optional 

standard will be available only for the 2014 through 2016 model years, because we 

believe that manufacturers will have had ample opportunity to make appropriate changes 

to bring their product performance into line with the rest of the industry after that time. 

As proposed, the final rules require that manufacturers making use of these provisions for 

the optional standard would need to exhaust all credits available to this averaging set

prior to using this flexibility and would not be able to generate emissions credits from 

other engines in the same regulatory averaging set as the engines complying using this 

alternate approach. 

The agencies note again that manufacturers choosing to utilize this option in MYs 

2014-2016 will have to make a greater relative improvement in MY 2017 than the rest of 

the industry, since they will be starting from a worse level – for compliance purposes, 

emissions from engines certified and sold at the three percent level will be averaged with 

emissions from engines certified and sold at more stringent levels to arrive at a weighted 

average emissions for all engines in the subcategory. Again, this option can only be 

taken if all other credit opportunities have been exhausted and the manufacturer still 

cannot meet the primary standards. If a manufacturer chooses this option to meet the 

EPA emission standards in the MY 2014 – 2016, and wants to opt into the NHTSA fuel 

consumption program in these same MYs it must follow the exact path followed under 

the EPA program utilizing equivalent fuel consumption standards. Since the NHTSA 

standards are optional in 2014, manufacturers may choose not to adopt either the 

alternative engine standard or the regular voluntary standard by not participating in the 

NHTSA program in 2014 and 2015. 

 

71 See 75 FR 25414-25419
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Some commenters argued that manufacturers could game the standard by 

establishing an artificially high 2011 baseline emission level. This could be done, for 

example, by certifying an engine with high fuel consumption and GHG emissions that is 

either: 1) not sold in significant quantities; or 2) later altered to emit fewer GHGs and 

consume less fuel through service changes. In order to mitigate this possibility, the 

agencies are requiring that the 2011 model year baseline must be developed by averaging 

emissions over all engines in an engine family certified and sold for that model year so as 

to prevent a manufacturer from developing a single high GHG output engine solely for 

the purpose of establishing a high baseline. As an alternative, if a manufacturer does not 

certify all engine families in an averaging set to the alternate standards, then the tested 

configuration of the engine certified to the alternate standard must have the same engine 

displacement and its rated power within 5 percent of the highest rated power of the 

baseline tested configuration. In addition, the tested configuration of the engine certified 

to the alternate standard must be a configuration sold to customers. These three 

requirements will prevent a manufacturer from producing an engine with an artificially

high power rating and therefore produce artificially low grams of CO2 emissions and fuel 

consumption per brake horsepower. In addition, the tested configurations must have a 

BSFC equivalent to or better than all other configurations within the engine family which 

will prevent a manufacturer from creating a baseline configuration with artificially high 

CO2 emissions and fuel consumption. 

(c) In-use Standards

Section 202(a)(1) of the CAA specifies that EPA is to adopt emissions standards 

that are applicable for the useful life of the vehicle. The in-use standards that EPA is 

finalizing would apply to individual vehicles and engines. NHTSA is adopting an 

approach which does not include in-use standards. 

EPA proposed that the in-use standards for heavy-duty engines installed in 

tractors be established by adding an adjustment factor to the full useful life emissions and 

fuel consumption results projected in the EPA certification process to address 

measurement variability inherent in comparing results among different laboratories and 

different engines. The agency proposed a two percent adjustment factor and requested 

comments and additional data during the proposal to assist in developing an appropriate 

factor level. The agency received additional data during the comment period which 

identified production variability which was not accounted for at proposal. Details on the 

development of the final adjustment factor are included in RIA Chapter 3. Based on the 

data received, EPA determined that the adjustment factor in the final rules should be 

higher than the proposed level of two percent. EPA is finalizing a three percent 

adjustment factor for the in-use standard to provide a reasonable margin for production 

and test-to-test variability that could result in differences between the initial emission test 

results and emission results obtained during subsequent in-use testing. 

We are finalizing regulatory text (in §1036.150) to allow engine manufacturers to 

used assigned deterioration factors (DFs) without performing their own durability

emission tests or engineering analysis. However, the engines would still be required to 

meet the standards in actual use without regard to whether the manufacturer used the 
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assigned DFs. This allowance is being adopted as an interim provision applicable only

for this initial phase of standards. 

Manufacturers will be allowed to use an assigned additive DF of 0.0 g/bhp-hr for 

CO2 emissions from any conventional engine (i.e., an engine not including advance or 

innovative technologies). Upon request, we could allow the assigned DF for CO2

emissions from engines including advance or innovative technologies, but only if we 

determine that it would be consistent with good engineering judgment. We believe that 

we have enough information about in-use CO2 emissions from conventional engines to 

conclude that they will not increase as the engines age. However, we lack such 

information about the more advanced technologies. 

EPA is also finalizing the proposed provisions requiring that the useful life for 

these engine and vehicles with respect to GHG emissions be set equal to the respective 

useful life periods for criteria pollutants. EPA is adopting provisions where the existing 

engine useful life periods, as included in Table II-6, be broadened to include CO2

emissions for both engines (See 40 CFR 1036.108(d)) and tractors (See 40 CFR 

1037.105).

Table II-6: Tractor and Engine Useful Life Periods

Years Miles

Medium Heavy-Duty Diesel Engines 10 185,000

Heavy Heavy-Duty Diesel Engines 10 435,000

Class 7 Tractors 10 185,000

Class 8 Tractors 10 435,000

(3) Test Procedures and Related Issues

The agencies are finalizing a complete set of test procedures to evaluate fuel 

consumption and CO2 emissions from Class 7 and 8 tractors and the engines installed in 

them. Consistent with the proposal, the test procedures related to the tractors are all new, 

while the engine test procedures already established were built substantially on EPA’s 

current non-GHG emissions test procedures, except as noted. This section discusses the 

final simulation model developed for demonstrating compliance with the tractor standard 

and the final engine test procedures.

(a) Vehicle Simulation Model

We are finalizing as proposed separate engine and vehicle-based emission 

standards to achieve the goal of reducing emissions and fuel consumption for both 

combination tractors and engines. Engine manufacturers are subject to the engine 

standards while the Class 7 and 8 tractor manufacturers are required to install certified 

engines in their tractors. The tractor manufacturer is also subject to a separate vehiclebased standard which utilizes a vehicle simulation model to evaluate the impact of the 

tractor cab design to determine compliance with the tractor standard. 
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A simulation model, in general, uses various inputs to characterize a vehicle’s 

properties (such as weight, aerodynamics, and rolling resistance) and predicts how the 

vehicle would behave on the road when it follows a driving cycle (vehicle speed versus 

time). On a second-by-second basis, the model determines how much engine power 

needs to be generated for the vehicle to follow the driving cycle as closely as possible. 

The engine power is then transmitted to the wheels through transmission, driveline, and 

axles to move the vehicle according to the driving cycle. The second-by-second fuel 

consumption of the vehicle, which corresponds to the engine power demand to move the 

vehicle, is then calculated according to a fuel consumption map in the model. Similar to 

a chassis dynamometer test, the second-by-second fuel consumption is aggregated over 

the complete drive cycle to determine the fuel consumption of the vehicle.

Consistent with the proposal, NHTSA and EPA are finalizing a procedure to 

evaluate fuel consumption and CO2 emissions respectively through a simulation of 

whole-vehicle operation, consistent with the NAS recommendation to use a truck model 

to evaluate truck performance.72 The EPA developed the Greenhouse gas Emissions 

Model (GEM) for the specific purpose of this rulemaking to evaluate truck performance. 

The GEM is similar in concept to a number of vehicle simulation tools developed by

commercial and government entities. The model developed by the EPA and finalized 

here was designed for the express purpose of vehicle compliance demonstration and is 

therefore simpler and less configurable than similar commercial products. This approach 

gives a compact and quicker tool for vehicle compliance without the overhead and costs 

of a more sophisticated model. Details of the model are included in Chapter 4 of the 

RIA. The agencies are aware of several other simulation tools developed by universities 

and private companies. Tools such as Argonne National Laboratory's Autonomie, 

Gamma Technologies’ GT-Drive, AVL’s CRUISE, Ricardo’s VSIM, Dassault’s 

DYMOLA, and University of Michigan's HE-VESIM codes are publicly available. In 

addition, manufacturers of engines, vehicles, and trucks often have their own in-house 

simulation tools. The agencies sought comments regarding other software packages 

which would better serve the compliance purposes of the rules than the GEM, but did not 

receive any recommendations. 

The GEM is designed to focus on the inputs most closely associated with fuel 

consumption and CO2 emissions - i.e., on those which have the largest impacts such as 

aerodynamics, rolling resistance, weight, and others. 

EPA has validated the GEM based on the chassis test results from two 

combination tractors tested at Southwest Research Institute. The validation work 

conducted on this vehicle was representative of the other Class 7 and 8 tractors. Many 

aspects of one tractor configuration (such as the engine, transmission, axle configuration, 

tire sizes, and control systems) are similar to those used on the manufacturer’s sister 

models. For example, the powertrain configuration of a sleeper cab with any roof height 

is similar to the one used on a day cab with any roof height. Overall, the GEM predicted 

the fuel consumption and CO2 emissions within 2 percent of the chassis test procedure 

results for three test cycles – the California ARB Transient cycle, 65 mph cruise cycle, 

 

72 See 2010 NAS Report. Note 21, Recommendation 8-4. Page 190.
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and 55 mph cruise cycle. These cycles are the ones the agencies are utilizing in 

compliance testing. Since the time of the proposal, the EPA also conducted a validation 

of the GEM relative to a commonly used vehicle simulation software, GT-Power. The 

results of this validation found that the two software programs predicted the fuel 

efficiency of each subcategory of tractor to be within 2 percent. Test to test variation for 

heavy-duty vehicle chassis testing can be higher than 4 percent due to driver variation 

alone. The final simulation model is described in greater detail in Chapter 4 of the RIA 

and is available for download by at (http://www.epa.gov/otaq/climate/regulations.htm).

After proposal, the agencies conducted a peer review of GEM version 1.0 which 

was proposed. In addition, we requested comment on all aspects of this approach to 

compliance determination in general and to the use of the GEM in particular. The 

agencies received comments from stakeholders and made changes for the release of GEM 

v2.0 to address concerns raised in the comments, along with the comments received 

during the peer review process. The most noticeable changes to the GEM include 

improvements to the graphical user interface (GUI). In response to comments, the 

agencies have reduced the amount of information required in the Identification section; 

linked the inputs to the selected subcategory while graying-out the items that are not 

applicable to the subcategory; and added batch modeling capability to reduce the 

compliance burden to manufacturers. In addition, substantial work went into model 

validations and benchmarking against vehicle test data and other commonly used vehicle 

simulation models. 

The model also includes a new driver model, a simplified electric system model, 

and revised engine fuel maps to better reflect the 2017 model year engine standards. The 

model in the final rulemaking uses the targeted vehicle driving speed to estimate vehicle 

torque demand at any given time, and then the power required to drive the vehicle is 

derived to estimate the required accelerator and braking pedal positions. If the driver 

misses the vehicle speed target, a speed correction logic controlled by a PID controller is 

applied to adjust necessary accelerator and braking pedal positions in order to match 

targeted vehicle speed at every simulation time step. The enhanced driver model used in 

the final rulemaking with its feed-forward driver controls more realistically models 

driving behavior. The GEM v1.0, the proposed version of the model, had four individual 

components to model the electric system – starter, electrical energy system, alternator, 

and electrical accessory. For the final rulemaking, the GEM v2.0 has a single electric 

system model with a constant power consumption level. Based on comments received, 

the agencies revisited the 2017 model year proposed fuel maps, specifically the low load 

area, which was extrapolated during the proposal and (incorrectly) generated negative 

improvements. The agencies redeveloped the fuel maps for the final rulemaking to better 

predict the fuel consumption of engines in this area of the fuel consumption map. Details 

of the changes are included in RIA Chapter 4.

To demonstrate compliance, a Class 7 and 8 tractor manufacturer will measure the 

performance of specified tractor systems (such as aerodynamics and tire rolling 

resistance), input the values into the GEM, and compare the model’s output to the 

standard. The rules require that a tractor manufacturer provide the inputs for each of 

following factors for each of the tractors it wishes to certify under CO2 standards and for 
*** E.O. 12866 Review – Revised Version 

establishing fuel consumption values: Coefficient of Drag, Tire Rolling Resistance 

Coefficient, Weight Reduction, Vehicle Speed Limiter, and Extended Idle Reduction 

Technology. These are the technologies on which the agencies’ own feasibility analysis 

for these vehicles is predicated. An example of the GEM input screen is included in 

Figure II-1.

For the aerodynamic assessment, tire rolling resistance, and tractor weight 

reduction, the input values for the simulation model will be determined by the 

manufacturer through conducting tests using the test procedures finalized by the agencies 

in this action and described below. The agencies are allowing several testing alternatives 

for aerodynamic assessment referenced back to a coastdown test procedure, a single 

procedure for determination of the coefficient of 

prescribed method to determine tractor weight reduction. The agencies have finalized 

defined model inputs for determining vehicle speed limiter and extended idle reduction 

technology benefits. The other aspects of vehicle performance are fixed within the model 

as defined by the agencies and are not varied for the purpose of compliance.

(b) Metric

Test metrics which are quantifiable and meaningful are critical for a regulatory 

program. The CO2 and fuel consumption metric should reflect what we wish to control 

(CO2 or fuel consumption) relative to the clearest value of its use: in this case, carrying 

freight. It should encourage efficiency improvements that will lead to reductions i

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establishing fuel consumption values: Coefficient of Drag, Tire Rolling Resistance 

Weight Reduction, Vehicle Speed Limiter, and Extended Idle Reduction 

Technology. These are the technologies on which the agencies’ own feasibility analysis 

for these vehicles is predicated. An example of the GEM input screen is included in 

Figure II-1: GEM Input Screen

For the aerodynamic assessment, tire rolling resistance, and tractor weight 

reduction, the input values for the simulation model will be determined by the 

conducting tests using the test procedures finalized by the agencies 

in this action and described below. The agencies are allowing several testing alternatives 

for aerodynamic assessment referenced back to a coastdown test procedure, a single 

determination of the coefficient of rolling resistance (CRR)

prescribed method to determine tractor weight reduction. The agencies have finalized 

defined model inputs for determining vehicle speed limiter and extended idle reduction 

hnology benefits. The other aspects of vehicle performance are fixed within the model 

as defined by the agencies and are not varied for the purpose of compliance.

Test metrics which are quantifiable and meaningful are critical for a regulatory 

and fuel consumption metric should reflect what we wish to control 

or fuel consumption) relative to the clearest value of its use: in this case, carrying 

freight. It should encourage efficiency improvements that will lead to reductions i

Do Not Cite, Quote, or Release During Review ***

establishing fuel consumption values: Coefficient of Drag, Tire Rolling Resistance 

Weight Reduction, Vehicle Speed Limiter, and Extended Idle Reduction 

Technology. These are the technologies on which the agencies’ own feasibility analysis 

for these vehicles is predicated. An example of the GEM input screen is included in 

For the aerodynamic assessment, tire rolling resistance, and tractor weight 

reduction, the input values for the simulation model will be determined by the 

conducting tests using the test procedures finalized by the agencies 

in this action and described below. The agencies are allowing several testing alternatives 

for aerodynamic assessment referenced back to a coastdown test procedure, a single 

) for tires, and a 

prescribed method to determine tractor weight reduction. The agencies have finalized 

defined model inputs for determining vehicle speed limiter and extended idle reduction 

hnology benefits. The other aspects of vehicle performance are fixed within the model 

as defined by the agencies and are not varied for the purpose of compliance.

Test metrics which are quantifiable and meaningful are critical for a regulatory 

and fuel consumption metric should reflect what we wish to control 

or fuel consumption) relative to the clearest value of its use: in this case, carrying 

freight. It should encourage efficiency improvements that will lead to reductions in 
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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emissions and fuel consumption during real world operation. The agencies are finalizing 

standards for Class 7 and 8 combination tractors that would be expressed in terms of 

moving a ton (2,000 pounds) of freight over one mile. Thus, NHTSA’s final fuel 

consumption standards for these trucks would be represented as gallons of fuel used to 

move one ton of freight 1,000 miles, or gal/1,000 ton-mile. EPA's final CO2 vehicle 

standards would be represented as grams of CO2 per ton-mile. The model converts CO2

emissions to fuel consumption using the CO2 grams per ton mile estimated by GEM and 

an assumed 10,180 grams of CO2 per gallon of diesel fuel.

This approach tracks the recommendations of the NAS report. The NAS panel 

concluded, in their report, that a load-specific fuel consumption metric is appropriate for 

HD trucks. The panel spent considerable time explaining the advantages of and 

recommending a load-specific fuel consumption approach to regulating the fuel 

efficiency of heavy-duty trucks. See NAS Report pages 20 through 28. The panel first 

points out that the nonlinear relationship between fuel economy and fuel consumption has 

led consumers of light-duty vehicles to have difficulty in judging the benefits of replacing 

the most inefficient vehicles. The panel describes an example where a light-duty vehicle 

can save the same 107 gallons per year (assuming 12,000 miles travelled per year) by

improving one vehicle’s fuel efficiency from 14 to 16 mpg or improving another 

vehicle’s fuel efficiency from 35 to 50.8 mpg. The use of miles per gallon leads 

consumers to undervalue the importance of small mpg improvements in vehicles with 

lower fuel economy. Therefore, the NAS panel recommends the use of a fuel 

consumption metric over a fuel economy metric. The panel also describes the primary

purpose of most heavy-duty vehicles as moving freight or passengers (the payload). 

Therefore, they concluded that the most appropriate way to represent an attribute-based 

fuel consumption metric is to normalize the fuel consumption to the payload.

With the approach to compliance NHTSA and EPA are adopting, a default 

payload is specified for each of the tractor categories suggesting that a gram per mile 

metric with a specified payload and a gram per ton-mile metric would be effectively 

equivalent. The primary difference between the metrics and approaches relates to our 

treatment of mass reductions as a means to reduce fuel consumption and greenhouse gas 

emissions. In the case of a gram per mile metric, mass reductions are reflected only in 

the calculation of the work necessary to move the vehicle mass through the drive cycle. 

As such it directly reduces the gram emissions in the numerator since a vehicle with less 

mass will require less energy to move through the drive cycle leading to lower CO2

emissions. In the case of Class 7 and 8 tractors and our gram/ton-mile metric, reductions 

in mass are reflected both in less mass moved through the drive cycle (the numerator) and 

greater payload (the denominator). We adjust the payload based on vehicle mass 

reductions because we estimate that approximately one third of the time the amount of 

freight loaded in a trailer is limited not by volume in the trailer but by the total gross 

vehicle weight rating of the tractor. By reducing the mass of the tractor the mass of the 

freight loaded in the vehicle can go up. Based on this general approach, it can be 

estimated that for every 1,200 pounds in mass reduction across all Class 7 and 8 tractors 

on the road, that total vehicle miles traveled, and therefore trucks on the road, could be 

reduced by one percent. Without the use of a per ton-mile metric it would not be clear or 

straightforward for the agencies to reflect the benefits of mass reduction from large 
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freight carrying vehicles that are often limited in the freight they carry by the gross 

vehicle weight rating of the vehicle. There was strong consensus in the public comments 

for adopting the proposed metrics for tractors.

(c) Vehicle Aerodynamic Assessment

The aerodynamic drag of a vehicle is determined by the vehicle’s coefficient of 

drag (Cd), frontal area, air density and speed. As noted in the NPRM, quantifying truck 

aerodynamics as an input to the GEM presents technical challenges because of the 

proliferation of vehicle configurations, the lack of a clearly preferable standardized test 

method, and subtle variations in measured aerodynamic values among various test 

procedures. Class 7 and 8 tractor aerodynamics are currently developed by 

manufacturers using a range of techniques, including wind tunnel testing, computational 

fluid dynamics, and constant speed tests. 

Consistent with our discussion at proposal, we believe a broad approach allowing 

manufacturers to use these multiple different test procedures to demonstrate aerodynamic 

performance of its tractor fleet is appropriate given that no single test procedure is 

superior in all aspects to other approaches. Allowing manufacturers to use multiple test 

procedures and modeling coupled with good engineering judgment to determine 

aerodynamic performance is consistent with the current approach used in determining 

representative road load forces for light-duty vehicle testing (40 CFR 86.129-00(e)(1)). 

However, we also recognize the need for consistency and a level playing field in 

evaluating aerodynamic performance. 

The agencies are retaining an aerodynamic bin structure for the final rulemaking, 

but are adjusting the method used to determine the bins. To address the consistency and 

level playing field concerns, NHTSA and EPA proposed that manufacturers use a twopart screening approach for determining the aerodynamic inputs to the GEM. The first 

part would have required the manufacturers to assign each vehicle aerodynamic 

configuration based on descriptions of vehicle characteristics to one of five aerodynamics 

bins created by EPA and NHTSA. The proposed assignment by bin would have fixed (by 

rule) the aerodynamic characteristics of the vehicle. However, the agencies, while 

working with industry, concluded for the final rulemaking that an approach which 

identified a reference aerodynamic test method and a procedure to align results from 

other aerodynamic test procedures with the reference method is a simpler, more accurate 

approach than deciphering and interpreting written descriptions of aerodynamic 

components.

Therefore, we are finalizing an approach, as described in Section V.B.3.d and 

§1037.501, which uses an enhanced coastdown procedure as a reference method and 

defines a process for manufacturers to align drag results from each of their own test 

methods to the reference method results. Manufacturers will be able to use any 

aerodynamic evaluation method in demonstrating a vehicle’s aerodynamic performance 

as long as the method is aligned to the reference method. The results from the 

aerodynamic testing will be the single determining factor for aerodynamic bin 

assignments. 
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EPA and NHTSA recognize that wind conditions, most notably wind direction, 

have a greater impact on real world CO2 emissions and fuel consumption of heavy-duty 

trucks than of light-duty vehicles. As noted in the NAS report,73 the wind average drag 

coefficient is about 15 percent higher than the zero degree coefficient of drag. In 

addition, the agencies received comments that supported the use of wind averaged drag 

results for the aerodynamic determination. The agencies considered finalizing the use of 

a wind averaged drag coefficient in this regulatory program, but ultimately decided to 

finalize drag values which represent zero yaw (i.e., representing wind from directly in 

front of the vehicle, not from the side) instead. We are taking this approach recognizing 

that the reference method is coastdown testing which is not capable of determining wind 

averaged yaw. Wind tunnels are currently the only tool which can accurately assess the 

influence of wind speed and direction on a vehicle’s aerodynamic performance. The 

agencies recognize, as NAS did, that the results of using the zero yaw approach may

result in fuel consumption predictions that are offset slightly from real world performance 

levels, not unlike the offset we see today between fuel economy test results in the CAFE 

program and actual fuel economy performance observed in-use. We believe this approach 

will not impact overall technology effectiveness or change the kinds of technology

decisions made by the tractor manufacturers in developing equipment to meet our final 

standards. However, the agencies are adopting provisions which allow manufacturers to 

generate credits reflecting performance of technologies which improve the aerodynamic 

performance in crosswind conditions, similar to those experienced by vehicles in use 

through innovative technologies, as described in Section IV.

As just noted, the agencies are adopting an approach for this final action where 

the manufacturer would determine a tractor’s aerodynamic drag force using their own 

aerodynamic assessment tools and correlating the results back to the reference 

aerodynamic test method of enhanced coastdown testing. The manufacturer determines 

the appropriate predefined aerodynamic bin based on the correlated test results and then 

inputs the predefined Cd value for that aerodynamic bin into the GEM. Coefficient of 

drag and frontal area of the tractor-trailer combination go hand-in-hand to determine the 

force required to overcome aerodynamic drag. The agencies proposed that the Cd value 

would be a GEM input derived by the manufacturer and that the agencies would specify

the vehicle’s frontal area for each regulatory subcategory. The agencies sought and 

received comment recommending an alternate approach where the aerodynamic input 

tables (as shown in Table II-7 and Table II-8) represent the drag force as defined as Cd

multiplied by the frontal area. Because both approaches are essentially equivalent and the 

use of CdA more directly relates back to the aerodynamic testing, the agencies are 

finalizing the use of CdA as recommended by manufacturers. 

The agencies are finalizing aerodynamic technology bins which divide the wide 

spectrum of tractor aerodynamics into five bins (i.e., categories) for high roof tractors. 

The first high roof category, Bin I, is designed to represent tractor bodies which prioritize 

appearance or special duty capabilities over aerodynamics. These Bin I trucks 

incorporate few, if any, aerodynamic features and may have several features which 

detract from aerodynamics, such as bug deflectors, custom sunshades, B-pillar exhaust 

 

73 See 2010 NAS Report, Note 21, Finding 2-4 on page 39.
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stacks, and others. The second high roof aerodynamics category is Bin II which roughly 

represents the aerodynamic performance of the average new tractor sold today. The 

agencies developed this bin to incorporate conventional tractors which capitalize on a 

generally aerodynamic shape and avoid classic features which increase drag. High roof 

tractors within Bin III build on the basic aerodynamics of Bin II tractors with added 

components to reduce drag in the most significant areas on the tractor, such as integral 

roof fairings, side extending gap reducers, fuel tank fairings, and streamlined 

grill/hood/mirrors/bumpers, similar to SmartWay trucks today. The Bin IV aerodynamic 

category for high roof tractors builds upon the Bin III tractor body with additional 

aerodynamic treatments such as underbody airflow treatment, down exhaust, and lowered 

ride height, among other technologies. And finally, Bin V tractors incorporate advanced 

technologies which are currently in the prototype stage of development, such as advanced 

gap reduction, rearview cameras to replace mirrors, wheel system streamlining, and 

advanced body designs. 

The agencies had proposed five aerodynamic bins for each tractor regulatory 

subcategory. The agencies received comments from ATA, EMA/TMA, and Volvo 

indicating that this approach was not consistent with the aerodynamics of low and mid 

roof tractors. High roof tractors are consistently paired with box trailer designs, and 

therefore manufacturers can design the tractor aerodynamics as a tractor-trailer unit and 

target specific areas like the gap between the tractor and trailer. In addition, the high roof 

tractors tend to spend more time at high speed operation which increases the impact of 

aerodynamics on fuel consumption and GHG emissions. On the other hand, low and mid 

roof tractors are designed to pull variable trailer loads and shapes. They may pull trailers 

such as flat bed, low boy, tankers, or bulk carriers. The loads on flat bed trailers can 

range from rectangular cartons with tarps, to a single roll of steel, to a front loader. Due 

to these variables, manufacturers do not design unique low and mid roof tractor 

aerodynamics but instead use derivatives from their high roof tractor designs. The 

aerodynamic improvements to the bumper, hood, windshield, mirrors, and doors are 

developed for the high roof tractor application and then carried over into the low and mid 

roof applications. As mentioned above, the types of designs that would move high roof 

tractors from a Bin III to Bins IV and V include features such as gap reducers and 

integral roof fairings which would not be appropriate on low and mid roof tractors. The 

agencies considered and largely agree with these comments and are therefore finalizing 

only two aerodynamic bins for low and mid roof tractors. The agencies are reducing the 

number of bins to reflect the actual range of aerodynamic technologies effective in low 

and mid roof tractor applications. Thus, the agencies are differentiating the aerodynamic 

performance for low and mid roof applications into two bins – conventional and 

aerodynamic.74

For high roof combination tractor compliance determination, a manufacturer 

would use the aerodynamic results determined through testing to establish the appropriate 

bin. The manufacturer would then input into GEM the Cd value specified for each bin as 

 

74 As explained in Section IV, there are no ABT implications to this change from proposal, since all Class 8 

combination tractors are considered to be a single averaging set for ABT purposes. Similarly, all Class 7 

tractors are considered to be a single averaging set for ABT purposes.
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defined in Table II-7 and Table II-8. For example, if a manufacturer tests a Class 8 

sleeper cab high roof tractor and the test produces a CdA value between 5.8 and 6.6, the 

manufacturer would assign this tractor to the Class 8 Sleeper Cab High Roof Bin III. The 

manufacturer would then use the Cd value identified for Bin III of 0.60 as the input to 

GEM.

The Cd values in Table II-7 and Table II-8 differ from proposal based on a change 

in the reference method (enhanced coastdown procedure) and additional testing 

conducted by EPA. Details of the test program and results are included in RIA Chapter 

2.5.1.4.

Table II-7: Aerodynamic Input Definitions to GEM for High Roof Tractors

Class 7 Class 8

Day Cab Day Cab Sleeper Cab

High Roof High Roof High Roof

Aerodynamic Test Results (CdA in m2)

Bin I ≥ 8.0 ≥ 8.0 ≥ 7.6

Bin II 7.1-7.9 7.1-7.9 6.7-7.5

Bin III 6.2-7.0 6.2-7.0 5.8-6.6

Bin IV 5.6-6.1 5.6-6.1 5.2-5.7

Bin V ≤ 5.5 ≤ 5.5 ≤ 5.1

Aerodynamic Input to GEM (Cd)

Bin I 0.79 0.79 0.75

Bin II 0.72 0.72 0.68

Bin III 0.63 0.63 0.60

Bin IV 0.56 0.56 0.52

Bin V 0.51 0.51 0.47

The CdA values in Table II-8 are based on testing using the enhanced coastdown 

test procedures adopted for the final rulemaking, which includes aerodynamic assessment 

of the low and mid roof tractors without a trailer. The removal of the trailer significantly

reduces the CdA value of mid roof tractors with tanker trailers because of the poor 

aerodynamic performance of the tanker trailer. The agencies developed the Cd input for 

each of the low and mid roof tractor bins to represent the Cd of the tractor, its frontal 

area, and the impact of the Cd value due to the trailer such that the GEM value is 

representative of a tractor-trailer combination, as it is for the high roof tractors.
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Table II-8: Aerodynamic Input Definitions to GEM for Low and Mid Roof Tractors

Class 7 Class 8

Day Cab Day Cab Sleeper Cab

Low Roof Mid Roof Low Roof Mid Roof Low Roof Mid Roof

Aerodynamic Test Results (CdA in m2)

Bin I ≥ 5.1 ≥ 5.6 ≥ 5.1 ≥ 5.6 ≥ 5.1 ≥ 5.6

Bin II ≤ 5.0 ≤ 5.5 ≤ 5.0 ≤ 5.5 ≤ 5.0 ≤ 5.5

Aerodynamic Input to GEM (Cd)

Bin I 0.77 0.87 0.77 0.87 0.77 0.87

Bin II 0.71 0.82 0.71 0.82 0.71 0.82

(d) Tire Rolling Resistance Assessment

NHTSA and EPA are finalizing as proposed that the tractor’s tire rolling 

resistance input to the GEM be determined by either the tire manufacturer or tractor 

manufacturer using the test method adopted by the International Organization for 

Standardization, ISO 28580:2009.75 The agencies believe the ISO test procedure is 

appropriate for this program because the procedure is the same one used by NHTSA in its 

fuel efficiency tire labeling program76 and is consistent with the testing direction being 

taken by the tire industry both in the United States and Europe. The rolling resistance 

from this test would be used to specify the rolling resistance of each tire on the steer and 

drive axle of the tractor. The results would be expressed as a rolling resistance 

coefficient (CRR) and measured as kilogram per metric ton (kg/metric ton). The 

agencies are finalizing as proposed that three tire samples within each tire model be 

tested three times each to account for some of the production variability and the average 

of the nine tests would be the rolling resistance coefficient for the tire. The GEM will use 

the steer and drive tire rolling resistance inputs and distribute 15 percent of the gross 

weight of the tractor and trailer to the steer axle, 42.5 percent to the drive axles, and 42.5 

percent to the trailer axles.77 The trailer tires’ rolling resistance is prescribed by the 

agencies as part of the standardized trailer used for demonstrating compliance at 6 

kg/metric ton, which was the average trailer tire rolling resistance measured during the 

SmartWay tire testing.78 

EPA and NHTSA conducted additional evaluation testing on HD trucks tires used 

for tractors, and also for vocational vehicles. The agencies also received several 

 

75 ISO, 2009, Passenger Car, Truck, and Bus Tyres – Methods of Measuring Rolling Resistance – Single 

Point Test and Correlation of Measurement Results: ISO 28580:2009(E), First Edition, 2009-07-01

76 NHTSA, 2009. “NHTSA Tire Fuel Efficiency Consumer Information Program Development: Phase 1 –

Evaluation of Laboratory Test Protocols.” DOT HS 811 119. June. (www.regulations.gov, Docket ID: 

NHTSA-2008-0121-0019).

77 This distribution is equivalent to the federal over-axle weight limits for an 80,000 GVWR 5-axle tractortrailer: 12,000 pounds over the steer axle, 34,000 pounds over the tandem drive axles (17,000 pounds per 

axle) and 34,000 pounds over the tandem trailer axles (17,000 pounds per axle). 

78 US Environmental Protection Agency. SmartWay Transport Partnership July 2010 e-update accessed 

July 16, 2010, from http://www.epa.gov/smartwaylogistics/newsroom/documents/e-update-july-10.pdf
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comments on the suitability of low rolling resistance tires for various HD vehicle 

applications. The summary of the agencies’ findings and a response to issues raised by 

commenters is presented in Section II.D(1)(a). 

(e) Weight Reduction Assessment

The agencies proposed that the tractor standards reflect improved CO2 emissions 

and fuel consumption performance of a 400 pound weight reduction in Class 7 and 8 

tractors through the substitution of single wide tires and light-weight wheels for dual tires 

and steel wheels. This approach was taken since there is a large variation in the baseline 

weight among trucks that perform roughly similar functions with roughly similar 

configurations. Because of this, the only effective way to quantify the exact CO2 and fuel 

consumption benefit of mass reduction using GEM is to estimate baseline weights for 

specific components that can be replaced with light weight components. If the weight 

reduction is specified for light weight versions of specific components, then both the 

baseline and weight differentials for these are readily quantifiable and well-understood. 

Lightweight wheels are commercially available as are single wide tires and thus data on 

the weight reductions attributable to these two approaches are readily available. 

The agencies received comments on this approach from Volvo, ATA, MEMA, 

Navistar, American Chemistry Council, the Auto Policy Center, Iron and Steel Institute, 

Arvin Meritor, Aluminum Association, and environmental groups and NGOs. Volvo and 

ATA stated that not all fleets can use single wide tires and if this is the case the 400 

pound weight reduction target cannot be met. Volvo stated that without the use of single 

wide drive tires, a 6x4 tractor will have a maximum weight reduction of 300 pounds if 

the customer selects all ten wheels to be outfitted with light weight aluminum wheels. A 

number of additional commenters – including American Chemistry Council, The Auto 

Policy Center, Iron and Steel Institute, Aluminum Association, Arvin Meritor, MEMA, 

Navistar, Volvo, and environmental and nonprofit groups – stated that manufacturers 

should be allowed to use additional light weight components in order to meet the tractor 

fuel consumption and CO2 emissions standards. These groups stated that weight 

reductions should not be limited to wheels and tires. They asked that cab doors, cab sides 

and backs, cab underbodies, frame rails, cross members, clutch housings, transmission 

cases, axle differential carrier cases, brake drums, and other components be allowed to be 

replaced with light-weight versions. Materials suggested for substitution included 

aluminum, light-weight aluminum, high strength steel, and plastic composites. The 

American Iron and Steel Institute stated there are opportunities to reduce mass by 

replacing mild steel – which currently dominates the heavy-duty industry – with high 

strength steel. 

In addition, The American Auto Policy Center asked that manufacturers be 

allowed to use materials other than aluminum and high strength steel to comply with the 

regulations. DTNA asked that weight reduction due to engine downsizing be allowed to 

receive credit. Volvo requested that weight reductions due to changes in axle 

configuration be credited. They used the example of a customer selecting a 4 X 2 over a 

6 X 4 axle tractor. In this case, they assert there would be a 1,000 pound weight savings 

from removing an axle.
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As proposed, many of the material substitutions could have been considered as 

innovative technologies for tractors and hence eligible for off cycle credits (so that the 

commenters overstated that these technologies were ‘disallowed’). Nonetheless in 

response to the above summarized comments, the agencies evaluated whether additional 

materials and components could be used directly for compliance with the tractor weight 

reduction through the primary program (i.e. be available as direct inputs to the GEM). 

The agencies reviewed comments and data received in response to the NPRM and 

additional studies cited by commenters. A summary of this review is provided in the 

following paragraphs.

TIAX, in their report to the NAS, cited information from Alcoa identifying 

several mass reduction opportunities from material substitution in the tractor cab 

components which were similar to the ones identified by the Aluminum Association in 

their comments to this rulemaking.79 TIAX included studies submitted by Alcoa showing

the potential to reduce the weight of a tractor-trailer combination by 3,500 to 4,500 

pounds.80 In addition, The U.S. Department of Energy has several projects underway to 

improve the freight efficiency of Class 8 trucks which provide relevant data:81 DOE

reviewed prospective lightweighting alternative materials and found that aluminum has a 

potential to reduce mass by 40 to 60 percent, which is in line with the estimates of mass 

reductions of various components provided by Alcoa, and by the Aluminum Association 

in their comments and as cited in the TIAX report. These combined studies, comments, 

and additional data provided information on specific components that could be replaced 

with aluminum components.

With regard to high strength steel, the Iron and Steel Institute found that the use of 

high strength steel and redesign can reduce the weight of light-duty trucks by 25 

percent.82 Approximately 10 percent of this reduction results from material substitution 

and 15 percent from vehicle re-design. While this study evaluated light-duty trucks, the 

agencies believe that a similar reduction could be achieved in heavy-duty trucks since the 

reductions from material substitution would likely be similar in heavy-trucks as in lighttrucks. U.S. DOE, in the report noted above, identified opportunities to reduce mass by

10 percent through high strength steel.83 This study was also for light-duty vehicles.

The agencies considered other materials such as plastic composites and 

magnesium substitutes but were not able to obtain weights for specific components made 

from these materials. We have therefore not included components made from these 

materials as possible substitutes in the primary program, but they may be considered 

 

79 TIAX, LLC. “Assessment of Fuel Economy Technologies for Medium- and Heavy-Duty Vehicles,” Final 

Report to National Academy of Sciences, November 19, 2009. Pages 4-62 through 4-64. 

80 Alcoa. “Improving Sustainability of Transport: Aluminum is Part of the Solution.” 2009

81 Schutte, Carol. U.S. Department of Energy, Vehicle Technologies Program. “Losing Weight – an 

enabler for a Systems Level Technology Development, Integration, and Demonstration for Efficient Class 8 

Trucks (SuperTruck) and Advanced Technology Powertrains for Light-Duty Vehicles” 

82 American Iron and Steel Institute. “A Cost Benefit Analysis Report to the North American Steel 

Industry on Improved Materials and Powertrain Architectures for 21st Century Trucks.”

83 Schutte, Carol. U.S. Department of Energy, Vehicle Technologies Program. “Losing Weight – an 

enabler for a Systems Level Technology Development, Integration, and Demonstration for Efficient Class 8 

Trucks (SuperTruck) and Advanced Technology Powertrains for Light-Duty Vehicles” 
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through the innovative technology/off-cycle credits provision. We may consider 

including these materials as part of the primary compliance option in a subsequent 

regulation if data become available. 

Based on this analysis, the agencies developed an expanded list of weight 

reduction opportunities for the final rulemaking that may be reflected in the GEM, as 

listed in Table II-9. The list includes additional components, but not materials, from 

those proposed. For high strength steel, the weight reduction value is equal to 10 percent 

of the presumed baseline component weight, as the agencies used a conservative value 

based on the DOE report. We recognize that there may be additional potential for weight 

reduction in new high strength steel components which combine the reduction due to the 

material substitution along with improvements in redesign, as evidenced by the studies 

done for light-duty vehicles. In the development of the high strength steel component 

weights, we are only assuming a reduction from material substitution and no weight 

reduction from redesign, since we do not have any data specific to redesign of heavy-duty 

components nor do we have a regulatory mechanism to differentiate between material 

substitution and improved design. We are finalizing for wheels that both aluminum and 

light weight aluminum are eligible to be used as light-weight materials. Aluminum, but 

not light-weight aluminum, can be used as a light-weight material for other components. 

The reason for this is that data were available for light weight aluminum for wheels but 

were not available for other components.

The agencies received comments on the proposal from the American Chemistry

Council highlighting the role of plastics and composites in heavy-duty vehicles. As they

stated, composites can be low density while having high strength and are currently used 

in applications such as oil pans and buses. The DOE mass reduction program 

demonstrated for heavy vehicles proof of concept designs for hybrid composite doors 

with an overall mass savings of 40 percent; 30 percent mass reduction of a hood system 

with carbon fiber sheet molding compound; 50 percent mass reduction from composite 

tie rods, trailing arms, and axles; and superplastically formed aluminum body panels.84 

While the agencies recognize these opportunities, we do not believe the technologies 

have advanced far enough to quantify the benefits of these materials because they are 

very dependent on the actual composite material. The agencies may consider such 

lightweighting opportunities in future actions, but are not including them as part of this 

primary program. Manufacturers which opt to pursue composite and plastic material 

substitutions may seek credits through the innovative technology provisions.

With regard to Volvo’s request that manufacturers be allowed to receive credit for 

trucks with fewer axles, the agencies recognize that vehicle options exist today which 

have less mass than other options. However, we believe the decisions to add or subtract 

such components will be made based on the intended use of the vehicle and not based on 

a crediting for the mass difference in our compliance program. It is not our intention to 

create a tradeoff between the right vehicle to serve a need (e.g. one with more or fewer 

 

84 Schutte, Carol. U.S. Department of Energy, Vehicle Technologies Program. “Losing Weight – an 

enabler for a Systems Level Technology Development, Integration, and Demonstration for Efficient Class 8 

Trucks (SuperTruck) and Advanced Technology Powertrains for Light-Duty Vehicles” 
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axles) and compliance with our final standards. Therefore, we are not including 

provisions to credit (or penalize) vehicle performance based on the subtraction (or 

addition) of specific vehicle components. Table II-9 provides weight reduction values for 

different components and materials.

Table II-9: Weight Reduction Values

Weight Reduction Technology Weight Reduction

(lb per tire/wheel)

Single Wide Drive

Tire with ...

Steel Wheel 84

Aluminum Wheel 139

Light Weight 

Aluminum Wheel

147

Steer Tire or Dual 

Wide Drive Tire 

with ...

High Strength Steel 

Wheel

8

Aluminum Wheel 21

Light Weight 

Aluminum Wheel

30

Weight Reduction Technologies Aluminum

Weight 

Reduction (lb.)

High Strength Steel 

Weight Reduction 

(lb.)

Door 20 6

Roof 60 18

Cab rear wall 49 16

Cab floor 56 18

Hood Support Structure 15 3

Fairing Support Structure 35 6

Instrument Panel Support Structure 5 1

Brake Drums – Drive (4) 140 11

Brake Drums – Non Drive (2) 60 8

Frame Rails 440 87

Crossmember - Cab 15 5

Crossmember – Suspension 25 6

Crossmember – Non Suspension (3) 15 5

Fifth Wheel 100 25

Radiator Support 20 6

Fuel Tank Support Structure 40 12

Steps 35 6
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Bumper 33 10

Shackles 10 3

Front Axle 60 15

Suspension Brackets, Hangers 100 30

Transmission Case 50 12

Clutch Housing 40 10

Drive Axle Hubs (8) 160 4

Non Drive Front Hubs (2) 40 5

Driveshaft 20 5

Transmission/Clutch Shift Levers 20 4

EPA and NHTSA are specifying the baseline vehicle weight for each regulatory

vehicle subcategory (including the tires, wheels, frame, and cab components) in the GEM 

in aggregate based on weight of vehicles used in EPA’s aerodynamic test program, but 

allow manufacturers to specify the use of light-weight components. The GEM then 

quantifies the weight reductions based on the pre-determined weight of the baseline 

component minus the pre-determined weight of the component made from light-weight 

material. Manufacturers cannot specify the weight of the light-weight component 

themselves, only the material used in the substitute component. The agencies assume the 

baseline wheel and tire configuration contains dual tires with steel wheels, along with 

steel frame and cab components, because these represent the vast majority of new vehicle 

configurations today. The weight reduction due to replacement of components with light 

weight versions will be reflected partially in the payload tons and partially in reducing the 

overall weight of the vehicle run in the GEM. The specified payload in the GEM will be 

set to the prescribed payload plus one third of the weight reduction amount to recognize 

that approximately one third of the truck miles are travelled at maximum payload, as 

discussed below in the payload discussion. The other two thirds of the weight reduction 

will be subtracted from the overall vehicle weight prescribed in the GEM.

The agencies continue to believe that the 400 pound weight target is appropriate 

to use as a basis for setting the final combination tractor CO2 emissions and fuel 

consumption standards. The agencies agree with the commenter that 400 pounds of 

weight reduction without the use of single wide tires may not be achievable for all tractor 

configurations. As noted, the agencies have extended the list of weight reduction 

components in order to provide the manufacturers with additional means to comply with 

the combination tractors and to further encourage reductions in vehicle weight. The 

agencies considered increasing the target value beyond 400 pounds given the additional 

reduction potential identified in the expanded technology list; however, lacking 

information on the capacity for the industry to change to these lightweight components 

across the board by the 2014 model year, we have decided to maintain the 400 pound 

target. The agencies intend to continue to study the potential for additional weight 

reductions in our future work considering a second phase of vehicle fuel efficiency and 

GHG regulations. In the context of the current rulemaking for HD fuel consumption and 

GHG standards, one would expect that reducing the weight of medium-duty trucks 

similarly would, if anything, have a positive impact on safety. However, given the large 
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difference in weight between light-duty and medium-duty vehicles, and even larger 

difference between light-duty vehicles and heavy-duty vehicles with loads, the agencies 

believe that the impact of weight reductions of medium- and heavy-duty vehicles would 

not have a noticeable impact on safety for any of these classes of vehicles.85 

(f) Extended Idle Reduction Technology Assessment

Extended idling from Class 8 heavy-duty long haul combination tractors 

contributes to significant CO2 emissions and fuel consumption in the United States. The 

Federal Motor Carrier Safety Administration regulations require a certain amount of 

driver rest for a corresponding period of driving hours.86 Extended idle occurs when 

Class 8 long haul drivers rest in the sleeper cab compartment during rest periods as 

drivers find it both convenient and less expensive to rest in the tractor cab itself than to 

pull off the road and find accommodations.87 During this rest period a driver will idle the 

tractor engine in order to provide heating or cooling, or to run on-board appliances. In 

some cases the engine can idle in excess of 10 hours. During this period, the engine will 

consume approximately 0.8 gallons of fuel and emit over 8,000 grams of CO2 per hour. 

An average tractor engine can consume 8 gallons of fuel and emit over 80,000 grams of 

CO2 during overnight idling in such a case. 

Idling reduction technologies (IRT) are available to allow for driver comfort 

while reducing fuel consumptions and CO2 emissions. Auxiliary power units, fuel 

operated heaters, battery supplied air conditioning, and thermal storage systems are 

among the technologies available today. The agencies are adopting a provision for use of 

extended idle reduction technology as an input to the GEM for Class 8 sleeper cabs. As 

discussed further in Section III, if a manufacturer wishes to receive credit for using IRT 

to meet the standard, then an automatic main engine shutoff must be programmed and 

enabled, such that engine shutdown occurs after 5 minutes of idling, to help ensure the 

reductions are realized in-use. A discussion of the provisions the agencies are adopting 

for allowing an override of this automatic shutdown can be found in RIA Chapter 2. As 

with all of the technology inputs discussed in this section, the agencies are not mandating 

the use of idle reductions or idle shutdown, but rather allowing their use as one part of a 

suite of technologies feasible for reducing fuel consumption and meeting the final 

standards and using these technologies as the inputs to the GEM. The default value (5 g 

CO2/ton-mile or 0.5 gal/1,000 ton-mile) for the use of automatic engine shutdown (AES) 

with idle reduction technologies was determined as the difference between a baseline 

main engine with idle fuel consumption of 0.8 gallons per hour that idles 1,800 hours and 

travels 125,000 miles per year, and a diesel auxiliary power unit operating in lieu of main 

engine during those same idling hours. The agencies received various comments from 

ACEEE and MEMA regarding the assumptions used to derive the idle reduction value. 

ACEEE argued that the agencies should use a fuel consumption rate of 0.47 gallon/hour 

for main engine idling based on a paper written by Kahn. MEMA argued that the 

 

85 For more information on the estimated safety effects of this rule, see Chapter 9 of the RIA.

86 Federal Motor Carrier Safety Administration. Hours of Service Regulations. Last accessed on August 2, 

2010 at http://www.fmcsa.dot.gov/rules-regulations/topics/hos/

87 The agencies note that some sleeper cabs may be classified as vocational tractors and therefore are 

expected to primarily travel locally and would not benefit from an idle reduction technology.
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agencies should use a main engine idling fuel consumption rate of 0.87 gal/hr, which is 

the midpoint of a DOE calculator reporting fuel consumption rates from 0.64 to 1.15 

gal/hr at idling conditions, and between 800 and 1200 rpm with the air conditioning on 

and off, respectively. The agencies respectfully disagree with the 0.47 gal/hr 

recommendation because the same paper by Kahn shows that while idling fuel 

consumption is 0.47 gal/hr on average at 600 rpm, CO2 emissions increase by 25 percent

with A/C on at 600 rpm, and increase by 165 percent between 600 rpm and 1,100 rpm 

with A/C on.88 MEMA recommended using 2,500 hours per year for APU operation. 

They cited the SmartWay website which uses 2,400 hours per year (8 hours per day and 

300 days per year). Also, they cited an Argonne study which assumed 7 hours per day

and 303 days per year, which equals 2,121 hours per year. Lastly, they referred to the 

FMCSA 2010 driver guidelines which reduce the number of hours driven per day by one 

to two hours, which would lead to 2,650 to 2,900 hours per year. The agencies reviewed 

other studies to quantify idling operations, as discussed in greater detail in RIA Section 

2.5.4.2, and believe that the entirety of the research does not support a change from the 

proposed calculation. Therefore, the agencies are finalizing the calculation as proposed. 

Additional details regarding the comments, calculations, and agency decisions are 

included in RIA Section 2.5.4.2. 

The agencies are adopting a provision to allow manufacturers to provide an AES 

system which is active for only a portion of a vehicle’s life. In this case, a discounted 

idle reduction value would be entered into GEM. A discussion of the calculation of a 

discounted IRT credit can be found in Section III. Additional details on the emission and 

fuel consumption reduction values are included in RIA Section 2.5.4.2.

(g) Vehicle Speed Limiters

The NPRM proposed to allow combination tractors that use vehicle speed limiters 

(VSL) to include the maximum governed speed value as an input to the GEM for 

purposes of determining compliance with the vehicle standards. The agencies also 

proposed not to assume the use of a mandatory vehicle speed limiter because of concerns 

about how to set a realistic application rate that avoids unintended consequences. See 75 

FR at 74223. Governing the top speed of a vehicle can reduce fuel consumption and 

GHG emissions, because fuel consumption and CO2 emissions increase proportionally to 

the square of vehicle speed.

89

 Limiting the speed of a vehicle reduces the fuel consumed, 

which in turn reduces the amount of CO2 emitted. The specific input to the GEM would 

be the maximum governed speed limit of the VSL that is programmed into the powertrain 

control module (PCM). The agencies stressed in the NPRM that in order to obtain a 

benefit in the GEM, a manufacturer must preset the limiter in such a way that the setting 

will not be “capable of being easily overridden by the fleet or the owner.” If the top 

speed could be easily overridden, the fuel consumption/CO2 benefits of the VSL might 

not be realized, and the agencies did not want to allow the technology to be used for 

 

88 See Gaines, L., A. Vyas, J.Anderson. “Estimation of Fuel Used by Idling Commercial Trucks,” Page 9 

(2006)

89 See 2010 NAS Report, Note 21, Page 28. Road Load Force Equation defines the aerodynamic portion of 

the road load as 1⁄2 * Coefficient of Drag * Frontal Area * air density * vehicle speed squared.
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compliance if the technology could be disabled easily and the real world benefits not 

achieved. 

Both the Center for Biological Diversity (CBD) and New York State Department 

of Transportation and Environmental Conservation commented that the application of 

speed limiters should be used to set the tractor standards.90 CBD urged the agencies to 

reconsider the position and adopt a speed limitation technology. NY State commented 

that the technologies are cost effective, reduce emissions, and appear to be generally 

acceptable to the trucking industry. They continued to say that the vehicle speed limit 

could be set without compromising operational logistics. 

Many commenters (Cummins, Daimler, EMA/TMA, ATA, AAPC, NADA) 

supported the use of VSLs as an input to the GEM, but requested clarification of what the 

specific requirements would be to ensure the VSL setting would not be capable of being 

easily overridden. Cummins and Daimler requested that the final rules explicitly allow 

vehicle manufacturers to access and adjust the VSL control feature for setting the

maximum governed speed, arguing that the diverse needs of the commercial vehicle 

industry warrant flexibility in electronic control features, and that otherwise supply chain 

issues91 may result from the use of VSLs. NADA and EMA/TMA also requested that 

VSLs have override features and be adjustable, citing various needs for flexibility by the 

fleets. EMA/TMA and ATA requested that VSLs be adjustable downward by fleets in 

order to obtain greater benefit in GEM, if company policies change or if a subsequent 

vehicle owner needs a different VSL setting. EMA/TMA stated that the agencies should 

prohibit tampering with VSLs, and both EMA and TRALA requested more information 

on how the agencies intended to address tampering with VSLs.

In addition to features governing the maximum vehicle speed, commenters 

requested adding other programmable flexibilities to mitigate potential drawbacks to 

VSLs. Cummins, DTNA, and EMA/TMA requested that a programmable “soft top” 

speed be added to PCMs which would allow a vehicle to exceed the speed limit setting 

governed by a VSL for a short period of time. A “soft top” feature could be used for a 

limited duration in order to maneuver and pass other on-road vehicles at speeds greater 

than that governed by the VSL. The commenters argued this was important for vehicle 

passing and safety-related situations where, without a soft top feature, it could be possible 

for speed limited trucks to obstruct other vehicles on the road and cause severe road 

congestion.

ATA and EMA/TMA also requested that manufacturers be allowed to program a

mileage based expiration into the VSL control feature, in order to preserve the value of 

vehicles for second owners who may require operation at higher speeds. ATA further 

commented that manufacturers should be allowed to account for additional GEM input 

 

90 One commenter mistakenly thought that the agencies were rejecting consideration of VSLs due to 

perceived jurisdictional obstacles. In fact, both the CAA and EISA allow consideration of VSL technology 

and the agencies considered the appropriateness of basing standards on performance of the technology.

91 Commenters stated that OEMs need access for setting appropriate trims for managing the VSL, otherwise 

significant supply chain issues could result such as parts shortages caused by the need for unique speed 

governed PCMs. 
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benefits if the speed governor is reprogrammed to a lower speed within the useful life of 

the vehicle. 

After carefully considering the comments, the agencies have decided, for these

final rules, to retain most of the elements in the proposal. Manufacturers will be allowed 

to implement a fixed maximum governed vehicle speed through a VSL feature and to use 

the maximum governed vehicle speed as an input to the GEM for certification. Also 

consistent with the proposal, the agencies are not premising the final standards on the use 

of VSLs. The comments received from stakeholders did not address the agencies’ 

concerns discussed in the proposal, specifically the risk of requiring VSL in situations 

that are not appropriate from an efficiency perspective because it may lead to additional 

vehicle trips to deliver the same amount of freight.92 The agencies continue to believe 

that we are not in a position to determine how many additional vehicles would benefit 

from the use of a VSL with a setting of less than 65 mph (a VSL with a speed set at or 

above 65 mph will show no CO2 emissions or fuel consumption benefit on the drive 

cycles included in this program). The agencies further believe that manufacturers will 

not utilize VSLs unless it is in their interest to do so, so that these unintended 

consequences should not occur when manufacturers use VSLs as a compliance strategy. 

We will monitor the industry’s use of VSL in this program and may consider using this 

technology in standard setting in the future. 

The agencies have decided to adopt commenters’ suggestions to allow adjustable 

lower limits that can be set and governed by VSLs independent of the one governing the 

maximum certified speed limit to provide the desired flexibility requested by the trucking 

industry. We believe that this flexibility would not decrease the anticipated fuel 

consumption or CO2 benefits of VSLs because the adjustable limits would be lower 

values. Issues identified by the commenters including the ability to change delivery 

routes requiring lower governed speeds or when a fleet’s business practices change 

resulting in a desire for greater fuel consumption savings are not in conflict with the 

purpose and benefit of VSLs. As such, the agencies have decided to allow a 

manufacturer to install features for its fleet customers to set their own lower adjustable 

limits below the maximum VSL specified by the agencies. However, the agencies have 

decided to not allow any additional benefit in the GEM to a manufacturer for allowing a 

lower governed speed in-use than the certified maximum limit for this first phase of the 

HD National Program because we can only be certain that the VSL will be at the 

maximum setting. 

Both agencies also agree that manufacturers can provide a “soft top” and 

expiration features to be programmed into PCMs to provide additional flexibility for fleet 

owners and so that fleets who purchase used vehicles have the ability to have different 

VSL policies than the original owner of the vehicle. Although the agencies considered 

limiting the soft top maximum level due to safety and fuel consumption/GHG benefit 

concerns, we have decided to allow the soft top maximum level to be set to any level 

higher than the maximum speed governed by the VSL. This approach will provide 

drivers with the ability to better navigate through traffic. However, the agencies are 

 

92 See 75 FR at page 74223
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requiring that manufacturers providing a soft top feature must design the system so it 

cannot be modified by the fleets and will not decrement the vehicle speed limit causing 

the vehicle to decelerate while the driver is operating a vehicle above the normal 

governed vehicle speed limit. For example, if a manufacturer designs a vehicle speed 

limiter that has a normal governed speed limiter setting of 62 mph, and a “soft top” speed 

limiter value of 65 mph, the algorithm shall not cause the vehicle speed to decrement 

causing the vehicle to decelerate while the driver is operating the vehicle at a speed 

greater that 62 mph (between 62 and 65 mph). The agencies are concerned that a forced 

deceleration when a driver is attempting to pass or maneuver could have an adverse 

impact on safety. 

In using a soft top feature, a manufacturer will be required to provide to the 

agencies a functional description of the “soft top” control strategy including calibration 

values, the speed setting for both the hard limit and the soft top and the maximum time 

per day the control strategy could allow the vehicle to operate at the “soft top” speed limit 

at the time of certification. This information will be used to derive a factor to discount 

the VSL input used in the GEM to determine the fuel consumption and GHG emissions 

performance of the vehicle. The agencies also agree with comments that VSLs should be 

adjustable so as not to potentially limit a vehicle’s resale value. However, manufacturers 

choosing the option to override the VSL after a specified number of miles would be 

required to discount the benefit of the VSL relative to the tractor’s full lifetime miles. 

The VSL discount benefits for using soft-top and expiration features must be calculated 

using Equation II-1.

93

 Additional details regarding the derivation of the discounted 

equation are included in RIA Chapter 2. The agencies are also requiring that any vehicle 

that has a “soft top” VSL to identify the use of the “soft top” VSL on the vehicle 

emissions label.

Equation II-1: Discounted Vehicle Speed Limiter Equation

VSL input for GEM = Expiration Factor * [Soft Top Factor* Soft Top VSL + (1-Soft 

Top Factor) * VSL] + (1-Expiration Factor)*65 mph

The agencies will require that the VSL algorithm be designed to assure that over 

the useful life of the vehicle that the vehicle will not operate in the soft top mode for 

more miles than would be expected based on the values used in Equation II-1, as 

specified by the expiration factor and the soft top factor. In addition, any time the 

cumulative percentage of operation in the soft top mode (based on miles) exceeds the 

maximum ratio that could occur at the full lifetime mileage, or at the expiration mileage 

if used, the algorithm must not allow the vehicle to exceed the VSL value. In this case, 

the soft top feature remain disabled until the vehicle mileage reaches a point where the 

ratio no longer meets this condition.

In response to the comments about how the agencies will evaluate tampering, 

NHTSA and EPA have added a number of requirements in these final rules relating to the 

VSL control feature. VSL control features should be designed so they cannot be easily

overridden. Manufacturers must ensure that the governed speed limit programmed into 

 

93 See §1037.640
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the VSL must also be verifiable through on-board diagnostic scanning tools, and must 

provide a description of the coding to identify the governed maximum speed limit and the 

expiration mileage both at the time of the initial vehicle certification and in-use. The

agencies believe both manufacturers and fleets should work toward maintaining the 

integrity of VSLs, and the agencies may conduct new-vehicle and in-use random audits to 

verify that inputs into GEM are accurate. 

The agencies are aware that some fleets/owners make changes to vehicles, such as 

installing different diameter tires, changing the axle (final drive) ratio and transmission 

gearing, such that a vehicle could travel at speeds higher than the speed limited by its 

VSL. Vehicles subject to FMCSA requirements must be in compliance with 49 CFR 

§ 393.82. The requirements apply to speedometers and states as follows:

Each bus, truck, and truck-tractor must be equipped with a speedometer indicating 

vehicle speed in miles per hour and/or kilometers per hour. The speedometer 

must be accurate to within plus or minus 8 km/hr (5 mph) at a speed of 80 km/hr 

(50 mph).

To facilitate adjustments for component changes affecting vehicle speed, 

manufacturers should provide a fleet/owner with the means to do so unless the 

adjustments would affect the VSL setting or operation. 

DTNA and ATA additionally requested that the agencies ensure that any VSL

provisions adopted under the GHG emissions and fuel efficiency rules align with existing 

NHTSA standards. The agencies agree and note that there are no existing standards for a 

VSL outside of this current rulemaking activity. However, NHTSA has announced its 

intent to publish a proposal in 2012 for a VSL.94 While both agencies have taken steps to 

avoid potential conflicts between the rulemaking being finalized today for fuel 

consumption and GHG emissions and the anticipated safety rulemaking, different 

conclusions may be reached in a safety-based rulemaking on VSLs, particularly in the 

approach to specifying soft top parameters and VSL expiration. 

(h) Defined Vehicle Configurations in the GEM

As discussed above, the agencies are adopting methodologies that manufacturers 

will use to quantify the values input into the GEM for these factors affecting vehicle 

efficiency: Coefficient of Drag, Tire Rolling Resistance Coefficient, Weight Reduction, 

Vehicle Speed Limiter, and Extended Idle Reduction Technology. The other aspects of 

the vehicle configuration are fixed within the model and are not varied for the purpose of 

compliance. The defined inputs include the tractor-trailer combination curb weight, 

payload, engine characteristics, and drivetrain for each vehicle type, and others. 

(i) Vehicle Drive Cycles

The GEM simulation model uses various inputs to characterize a vehicle’s 

configuration (such as weight, aerodynamics, and rolling resistance) and predicts how the 

 

94 76 FR 78.
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vehicle would behave on the road when it follows a driving cycle (vehicle speed versus 

time). As noted by the 2010 NAS Report,95 the choice of a drive cycle used in 

compliance testing has significant consequences on the technology that will be employed 

to achieve a standard as well as the ability of the technology to achieve real world 

reductions in emissions and improvements in fuel consumption. Manufacturers naturally 

will design vehicles to ensure they satisfy regulatory standards. An ill-suited drive cycle 

for a regulatory category could encourage GHG emissions and fuel consumption 

technologies which satisfy the test but do not achieve the same benefits in use. For 

example, requiring all trucks to use a constant speed highway drive cycle will drive 

significant aerodynamic improvements. However, in the real world a combination tractor 

used for local delivery may spend little time on the highway, reducing the benefits 

achieved by this technology. In addition, the extra weight of the aerodynamic fairings 

will actually penalize the GHG and fuel consumption performance in urban driving and 

may reduce the freight carrying capability. The unique nature of the kinds of CO2

emissions control and fuel consumption technology means that the same technology can 

be of benefit during some operation but cause a reduced benefit under other operation.96 

To maximize the GHG emissions and fuel consumption benefits and avoid unintended 

reductions in benefits, the drive cycle should focus on promoting technology that 

produces benefits during the primary operation modes of the application. Consequently, 

drive cycles used in GHG emissions and fuel consumption compliance testing should 

reasonably represent the primary actual use, notwithstanding that every vehicle has a 

different drive cycle in-use. 

The agencies proposed a modified version of the California ARB Heavy Heavyduty Truck 5 Mode Cycle

97, using the basis of three of the cycles which best mirror Class 

7 and 8 combination tractor driving patterns, based on information from EPA’s MOVES 

model.98 The key advantage of the California ARB 5 mode cycle is that it provides the 

flexibility to use several different modes and weight the modes to fit specific vehicle 

application usage patterns. For the proposal, EPA analyzed the five cycles and found that 

some modifications to the cycles were required to allow sufficient flexibility in 

weightings. The agencies proposed the use of the Transient mode, as defined by

California ARB, because it broadly covers urban driving. The agencies also proposed 

altered versions of the High Speed Cruise and Low Speed Cruise modes which reflected 

only constant speed cycles at 65 mph and 55 mph respectively. In the NPRM, the 

agencies proposed to use three cycles which were the ARB transient cycle, a 55 mph 

steady state cruise, and a 65 mph steady state cruise. 

The agencies received comment from NACAA recommending an increase in the 

high speed cruise cycle speed from the proposed value of 65 mph to 75 mph because 

 

95 See 2010 NAS Report, Note 21, Chapters 4 and 8.

96

 This situation does not typically occur for heavy-duty emission control technology designed to control 

criteria pollutants such as PM and NOX.

97 California Air Resources Board. Heavy Heavy-duty Diesel Truck chassis dynamometer schedule, 

Transient Mode. Last accessed on August 2, 2010 at 

http://www.dieselnet.com/standards/cycles/hhddt.html

98 EPA’s MOVES (Motor Vehicle Emission Simulator). See

http://www.epa.gov/otaq/models/moves/index.htm for additional information.
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trucks travel at higher speeds. The agencies analyzed the urban and rural interstate truck 

speed limits in each state to determine the national average truck speed limit. State 

interstate speed limits for trucks vary between 55 and 75 mph, depending on the state.99 

Based on this information, the national median truck speed limit is 65 mph. The agencies 

also analyzed the national average truck speed limit weighted by VMT for each state 

based on VMT data by state from the Federal Highway Administration as described in 

RIA Section 3.4.2. Based on this information, the national average VMT-weighted truck 

speed limit is 63 mph. The agencies continue to believe that the appropriate high speed 

cruise speed should be set at the national average truck speed limit to appropriately

balance the evaluation of technologies such as aerodynamics, but not overstate the 

benefits of these technologies. Therefore, the agencies are adopting as proposed a speed 

of 65 mph for the high speed cruise cycle.

The agencies also received comments from Allison which disagreed with 

proposed drive cycles for combination tractors because the cycles did not account for 

external factors such as grades, wind, traffic condition, etc. Allison also believes that the 

acceleration rates are too low. The agencies recognize that the proposed drive cycles do 

not incorporate the external factors described by Allison. Parallel to the approach used to 

evaluate light-duty vehicles, the drive cycles do not incorporate either grade or wind 

which can be difficult to simulate in chassis dynamometer cells. In the final rules, the 

agencies are defining an approach that manufacturers may take to evaluate their 

aerodynamic packages in a wind-averaged condition and use a modified Cd value in 

GEM.100 The agencies are also adopting provisions for the innovative technology

demonstration that allows for the use of on-road testing which includes grades for 

technologies whose benefits are reflected with grade. Lastly, the agencies’ final drive 

cycles for highway operation contain a constant speed, as proposed. The acceleration and 

deceleration rates are only used to bring the vehicle to the cruising speed and the CO2

emissions and fuel consumption from these portions of the drive cycle are not included in 

the composite emissions and fuel consumption results. The agencies did not include the 

speed dithering, which is representative of actual driving and traffic conditions, in the 

proposed constant speed portion of the cycles because the dithering does not provide any

additional distinction between technologies but only added complexity to the cycle. The 

agencies believe this approach is still appropriate for the final action.

Allison referred the agencies to the Oak Ridge National Laboratory and 

SmartWay program to review the amount of time long-haul vehicles spend on the 

highway. They believe the steady state highway speeds are overestimated. Data 

provided by Allison indicates that day cabs spend only 14 percent of miles traveling at 

speeds greater than 60 mph. NHTSA and EPA recognize that there is a variation in the 

amount of miles day cabs travel under different operations. As described above, the 

agencies are adopting an approach where tractors which operate like vocational vehicles 

may be regulated as such in the HD program. Thus, these day cabs will have a drive 

 

99 Governors Highway Safety Association. Speed Limit Laws May 2011. Last viewed on May 9, 2011 at 

http://www.ghsa.org/html/stateinfo/laws/speedlimit_laws.html

100 See Section IV.B.3.b below.
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cycle weighting representative of vocational vehicles with more weighting on the 

transient operation and less on the highway speed operation.

For proposal, EPA and NHTSA relied on the EPA MOVES analysis of Federal 

Highway Administration data to develop the mode weightings to characterize typical 

operations of heavy-duty trucks, per Table II-10 below.101 A detailed discussion of drive 

cycles is included in RIA Chapter 3.102 The agencies are adopting the proposed drive 

cycle weightings for combination tractors.

Table II-10: Drive Cycle Mode Weightings

Transient 55 mph Cruise 65 mph Cruise

Day Cabs 19% 17% 64%

Sleeper Cabs 5% 9% 86%

(ii) Standardized Trailers

As proposed, NHTSA and EPA are adopting provisions so that the tractor 

performance in the GEM is judged assuming the tractor is pulling a standardized trailer. 

The agencies did not receive any adverse comments related to this approach. The 

agencies believe that an assessment of the tractor fuel consumption and CO2 emissions 

should be conducted using a tractor-trailer combination. We believe this approach best 

reflects the impact of the overall weight of the tractor-trailer and the aerodynamic 

technologies in actual use, where tractors are designed and used with a trailer. The GEM 

will continue to use a predefined typical trailer in assessing overall performance. The 

high roof sleeper cabs are paired with a standard box trailer; the mid roof tractors are 

paired with a tanker trailer; and the low roof tractors are paired with a flat bed trailer. 

(iii) Empty Weight and Payload

The total weight of the tractor-trailer combination is the sum of the tractor curb 

weight, the trailer curb weight, and the payload. The total weight of a vehicle is 

important because it in part determines the impact of technologies, such as rolling 

resistance, on GHG emissions and fuel consumption. In this final action, the agencies are 

specifying each of these aspects of the vehicle, as proposed. 

In use, trucks operate at different weights at different times during their 

operations. The greatest freight transport efficiency (the amount of fuel required to move 

 

101 The Environmental Protection Agency. Draft MOVES2009 Highway Vehicle Population and Activity 

Data. EPA-420-P-09-001, August 2009 http://www.epa.gov/otaq/models/moves/techdocs/420p09001.pdf

102 In the light-duty vehicle rule, EPA and NHTSA based compliance with tailpipe standards on use of the 

FTP and HFET, and declined to use alternative tests. See 75 FR 25407. NHTSA is mandated to use the 

FTP and HFET tests for CAFE standards, and all relevant data was obtained by FTP and HFET testing in 

any case. Id. Neither of these constraints exists for Class 7-8 tractors. The little data which exist on 

current performance are principally measured by the ARB Heavy Heavy-duty Truck 5 Mode Cycle testing, 

and NHTSA is not mandated to use the FTP to establish heavy-duty fuel economy standards. See 49 

U.S.C. 32902(k)(2) authorizing NHTSA, among other things, to adopt and implement appropriate “test 

methods, measurement metrics, ... and compliance protocols”.
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a ton of payload) would be achieved by operating trucks at the maximum load for which 

they are designed all of the time. However, logistics such as delivery demands which 

require that trucks travel without full loads, the density of payload, and the availability of 

full loads of freight limit the ability of trucks to operate at their highest efficiency all the 

time. M.J. Bradley analyzed the Truck Inventory and Use Survey and found that 

approximately 9 percent of combination tractor miles travelled empty, 61 percent are 

“cubed-out” (the trailer is full before the weight limit is reached), and 30 percent are 

“weighed out” (operating weight equal 80,000 pounds which is the gross vehicle weight 

limit on the Federal Interstate Highway System or greater than 80,000 pounds for 

vehicles traveling on roads outside of the interstate system).103 

As described above, the amount of payload that a tractor can carry depends on the 

category (or GVWR and GCWR) of the vehicle. For example, a typical Class 7 tractor 

can carry less payload than a Class 8 tractor. For proposal, the agencies used the Federal 

Highway Administration Truck Payload Equivalent Factors using Vehicle Inventory and 

Use Survey (VIUS) and Vehicle Travel Information System data to determine the 

proposed payloads. FHWA’s results found that the average payload of a Class 8 vehicle 

ranged from 36,247 to 40,089 pounds, depending on the average distance travelled per 

day.

104

 The same results found that Class 7 vehicles carried between 18,674 and 34,210 

pounds of payload also depending on average distance travelled per day. Based on this 

data, the agencies proposed to prescribe a fixed payload of 25,000 pounds for Class 7 

tractors and 38,000 pounds for Class 8 tractors for their respective test procedures. The 

agencies proposed a common payload for Class 8 day cabs and sleeper cabs as predefined 

GEM input because the data available do not distinguish based on type of Class 8 tractor. 

These payload values represent a heavily loaded trailer, but not maximum GVWR, since 

as described above the majority of tractors “cube-out” rather than “weigh-out.” 

The agencies developed the proposed tractor curb weight inputs from actual 

tractor weights measured in two of EPA’s test programs and based on information from 

the manufacturers. The proposed trailer curb weight inputs were derived from actual 

trailer weight measurements conducted by EPA and weight data provided to ICF 

International by the trailer manufacturers.105 

The agencies received comments from UMTRI and ATA regarding the values 

assumed for the combination tractor weights. UMTRI recommended using 80,000 

pounds for the total weight for tractor-trailer combinations. ATA based on their analysis 

of the Federal Highway Administration’s Long Term Pavement Database, recommended 

5,000 to 10,000 pound payload for Class 7 tractors and 25,000 to 30,000 pounds for Class 

 

103 M.J. Bradley & Associates. Setting the Stage for Regulation of Heavy-Duty Vehicle Fuel Economy and 

GHG Emissions: Issues and Opportunities. February 2009. Page 35. Analysis based on 1992 Truck 

Inventory and Use Survey data, where the survey data allowed developing the distribution of loads instead 

of merely the average loads.

104 The U.S. Federal Highway Administration. Development of Truck Payload Equivalent Factor. Table 

11. Last viewed on March 9, 2010 at 

http://ops.fhwa.dot.gov/freight/freight_analysis/faf/faf2_reports/reports9/s510_11_12_tables.htm.

105 ICF International. Investigation of Costs for Strategies to Reduce Greenhouse Gas Emissions for 

Heavy-Duty On-road Vehicles. July 2010. Pages 4-15. Docket Number EPA-HQ-OAR-2010-0162-0044.
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8 tractors. ATA also determined from the same database that 20 percent of tractor miles 

are empty, 67 percent cube-out, and 13 percent weigh-out. The agencies are adopting the 

proposed tractor-trailer weights because we do not have strong evidence to select other 

values and because changing the assumed values would not change the impact on GHG 

emissions or fuel consumption of the technologies included in this phase of the HD 

program (the relative stringency of the standards and the projected emission reductions 

do not change with assumed payload). NHTSA and EPA intend to continue evaluating

additional sources of weight information in future phases of the program.

Details of the final individual weight inputs by regulatory category, as shown in 

Table II-11, are included in RIA Chapter 3.

Table II-11: Final Combination Tractor Weights

Model Type Regulatory 

Subcategory

Tractor Tare 

Weight (lbs)

Trailer 

Weight (lbs)

Payload (lbs) Total Weight 

(lbs)

Class 8 Sleeper Cab 

High Roof

19,000 13,500 38,000 70,500

Class 8 Sleeper Cab 

Mid Roof

18,750 10,000 38,000 66,750

Class 8 Sleeper Cab 

Low Roof

18,500 10,500 38,000 67,000

Class 8 Day Cab 

High Roof

17,500 13,500 38,000 69,000

Class 8 Day Cab 

Mid Roof

17,100 10,000 38,000 65,100

Class 8 Day Cab 

Low Roof

17,000 10,500 38,000 65,500

Class 7 Day Cab 

High Roof

11,500 13,500 25,000 50,000

Class 7 Day Cab 

Mid Roof

11,100 10,000 25,000 46,100

Class 7 Day Cab 

Low Roof

11,000 10,500 25,000 46,500

(iv) Standardized Drivetrain

The agencies’ assessment at proposal of the current vehicle configuration process 

at the truck dealer’s level was that the truck companies provide tools to specify the proper 

drivetrain matched to the buyer’s specific circumstances. These dealer tools allow a 

significant amount of customization for drive cycle and payload to provide the best 

specification for each individual customer. The agencies are not seeking to disrupt this 

process. Optimal drivetrain selection is dependent on the engine, drive cycle (including 

vehicle speed and road grade), and payload. Each combination of engine, drive cycle, 

and payload has a single optimal transmission and final drive ratio. The agencies received 

comments from ArvinMeritor and ICCT which suggested that the agencies incorporate 

the actual drivetrain configuration (axle configuration, driveline efficiency, and 

transmission) into the GEM. The agencies continue to believe, and therefore are 

adopting as proposed, that it is appropriate to specify the engine’s fuel consumption map, 
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drive cycle, and payload; therefore, it makes sense to also specify the drivetrain that 

matches. 

(v) Engine Input to the GEM for Tractors

As proposed, the agencies are defining the engine characteristics used in the 

GEM, including the fuel consumption map which provides the fuel consumption at 

hundreds of engine speed and torque points. If the agencies did not standardize the fuel 

map, then a tractor that uses an engine with emissions and fuel consumption better than

the standards would require fewer vehicle reductions than those technically feasible 

reductions reflected in the final standards. The agencies are finalizing two distinct fuel 

consumption maps for use in the GEM. The first fuel consumption map would be used in 

the GEM for the 2014 through 2016 model years and represents an average engine which 

meets EPA’s final 2014 model year engine CO2 emissions standards. The same fuel map 

would be used for NHTSA’s voluntary standards in the 2014 and 2015 model years, as 

well as its mandatory program in the 2016 model year. A second fuel consumption map 

will be used beginning in the 2017 model year and represents an engine which meets the 

2017 model year CO2 emissions and fuel consumption standards and accounts for the 

increased stringency in the final MY 2017 standard. The agencies have modified the 

2017 MY fuel map used in the GEM for the final rulemaking to address comments 

received. Details regarding this change can be found in RIA Chapter 4.4.4. Effectively 

there is no change in stringency of the tractor vehicle (not including the engine standards 

over the full rulemaking period).

106

 These inputs are appropriate given the separate 

regulatory requirement that Class 7 and 8 combination tractor manufacturers use only

certified engines.

(i) Heavy-Duty Engine Test Procedure for Engines Installed in Combination Tractors

The HD engine test procedure consists of two primary aspects – a duty cycle and 

a metric to evaluate the emissions and fuel consumption.

EPA proposed that the GHG emission standards for heavy-duty engines under the 

CAA would be expressed as g/bhp-hr while NHTSA’s proposed fuel consumption 

standards under EISA, in turn, be represented as gal/100 bhp-hr. The NAS panel did not 

specifically discuss or recommend a metric to evaluate the fuel consumption of heavyduty engines. However, as noted above they did recommend the use of a load-specific 

fuel consumption metric for the evaluation of vehicles.107 An analogous metric for 

engines is the amount of fuel consumed per unit of work. The g/bhp-hr metric is also 

consistent with EPA’s current standards for non-GHG emissions for these engines. The 

agencies did not receive any adverse comments related to the metrics for HD engines; 

therefore, we are adopting the metrics as proposed.

The agencies believe it is appropriate to set standards based on a single test 

procedure, either the Heavy-duty FTP or SET, depending on the primary expected use of 

 

106 As noted earlier, use of the 2017 model year fuel consumption map as a GEM input results in 

numerically more stringent final vehicle standards for MY 2017.

107 See NAS Report, Note 21, at page 39.
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the engine. This approach differs from EPA’s criteria pollutant standards for engines 

which currently require that manufacturers demonstrate compliance over the transient 

FTP cycle; over the steady-state SET procedure; and during not-to-exceed testing. EPA 

created this multi-layered approach to criteria emissions control in response to engine 

designs that optimized operation for lowest fuel consumption at the expense of very high 

criteria emissions when operated off the regulatory cycle. EPA’s use of multiple test 

procedures for criteria pollutants helps to ensure that manufacturers calibrate engine 

systems for compliance under all operating conditions. We are not concerned if 

manufacturers further calibrate engines off-cycle to give better in-use fuel consumption 

while maintaining compliance with the criteria emissions standards as such calibration is 

entirely consistent with the goals of our joint program. Further, we believe that setting 

GHG and fuel consumption standards based on both transient and steady-state operating 

conditions for all engines could lead to undesirable outcomes. 

It is critical to set standards based on the most representative test cycles in order 

for performance in-use to obtain the intended (and feasible) air quality and fuel 

consumption benefits. Tractors spend the majority of their operation at steady state 

conditions, and will obtain in-use benefit of technologies such as turbocompounding and 

other waste heat recovery technologies during this kind of typical engine operation. 

Turbocompounding is a very effective approach to lower fuel consumption under steady 

driving conditions typified by combination tractor trailer operation and is well reflected 

in testing over the SET test procedure. However, when used in driving typified by

transient operation as we expect for vocational vehicles and as is represented by the 

Heavy-duty FTP, turbocompounding shows very little benefit. Setting an emission 

standard based on the Heavy-duty FTP for engines intended for use in combination 

tractor trailers could lead manufacturers to not apply turbocompounding even though it 

can be a highly cost effective means to reduce GHG emissions and lower fuel 

consumption. (It is for this reason that turbocompounding is not part of the technology

basis for MHD or HHD engines installed in vocational vehicles.)

The agencies proposed that engines installed in tractors demonstrate compliance 

with the CO2 emissions and fuel consumption standards over the SET cycle. 

Commenters such as Cummins, Bosch, Daimler, and Honeywell supported the proposed 

approach. ACEEE recommended adopting a new test cycle, such as the World 

Harmonized Duty Cycle which was developed using newer data, to evaluate HD engines. 

Daimler also supported the WHDC for future phases of the program. The agencies 

continue to believe the important issues and technical work related to setting new criteria 

pollutant emissions standards appropriate for the World Harmonized Duty Cycle are 

significant and beyond the scope of this rulemaking. The SET cycle remains 

representative of typical driving cycles for combination tractors (and engines installed in 

them). Therefore, the agencies are adopting the SET cycle to evaluate CO2 emissions and 

fuel consumption of HD engines installed in tractors, as proposed.

The current non-GHG emissions engine test procedures also require the 

development of regeneration emission rates and frequency factors to account for the 

emission changes during a regeneration event (40 CFR 86.004-28). EPA and NHTSA 

proposed not to include these emissions from the calculation of the compliance levels 
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over the defined test procedures. Cummins and Daimler supported this approach and 

stated that sufficient incentives already exist for manufacturers to limit regeneration 

frequency. Conversely, Volvo opposed the omission of IRAF requirements for CO2

emissions because emissions from regeneration can be a significant portion of the 

expected improvement and a significant variable between manufacturers

At proposal, we considered including regeneration in the estimate of fuel 

consumption and GHG emissions and decided not to do so for two reasons. See 75 FR at 

74188. First, EPA’s existing criteria emission regulations already provide a strong 

motivation to engine manufacturers to reduce the frequency and duration of infrequent 

regeneration events. The very stringent 2010 NOX emission standards cannot be met by

engine designs that lead to frequent and extend regeneration events. Hence, we believe 

engine manufacturers are already reducing regeneration emissions to the greatest degree 

possible. In addition to believing that regenerations are already controlled to the extent 

technologically possible, we believe that attempting to include regeneration emissions in 

the standard setting could lead to an inadvertently lax emissions standard. In order to 

include regeneration and set appropriate standards, EPA and NHTSA would have needed 

to project the regeneration frequency and duration of future engine designs in the time 

frame of this program. Such a projection would be inherently difficult to make and quite 

likely would underestimate the progress engine manufacturers will make in reducing 

infrequent regenerations. If we underestimated that progress, we would effectively be 

setting a more lax set of standards than otherwise would be expected. Hence in setting a 

standard including regeneration emissions we faced the real possibility that we would 

achieve less effective CO2 emissions control and fuel consumption reductions than we 

will achieve by not including regeneration emissions. Therefore, the agencies are 

finalizing an approach as proposed which does not include the regenerative emissions. 

(j) Chassis-based Test Procedure

In the proposal, the agencies considered proposing a chassis-based vehicle test to 

evaluate Class 7 and 8 tractors based on a laboratory test of the engine and vehicle 

together. A “chassis dynamometer test” for heavy-duty vehicles would be similar to the 

Federal Test Procedure used today for light-duty vehicles. 

However, the agencies decided not to propose the use of a chassis test procedure 

to demonstrate compliance for tractor standards due to the significant technical hurdles to 

implementing such a program by the 2014 model year. The agencies recognize that such 

testing requires expensive, specialized equipment that is not yet widespread within the 

industry. The agencies have only identified approximately 11 heavy-duty chassis sites in 

the United States today and rapid installation of new facilities to comply with model year 

2014 is not possible.108 

In addition, and of equal if not greater importance, because of the enormous 

numbers of vehicle configurations that have an impact on fuel consumption, we do not 

 

108 For comparison, engine manufacturers typically own a large number of engine dynamometer test cells 

for engine development and durability (up to 100 engine dynamometers per manufacturer).
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believe that it would be reasonable to require testing of many combinations of tractor 

model configurations on a chassis dynamometer. The agencies evaluated the options 

available for one tractor model (provided as confidential business information from a 

truck manufacturer) and found that the company offered three cab configurations, six 

axle configurations, five front axles, 12 rear axles, 19 axle ratios, eight engines, 17 

transmissions, and six tire sizes – where each of these options could impact the fuel 

consumption and CO2 emissions of the tractor. Even using representative grouping of 

tractors for purposes of certification, this presents the potential for many different 

combinations that would need to be tested if a standard were adopted based on a chassis 

test procedure. 

The agencies received comments from ACEEE and UCS supporting a full vehicle 

testing approach, but these commenters recognized the difficulties in doing this in the 

first phase of the HD program. The agencies maintain that the full vehicle testing on 

chassis dynamometers is not feasible in the time frame of this rulemaking, although we 

believe such an approach may be appropriate in the future, if more testing facilities 

become available and if the agencies are able to address the complexity of tractor 

configurations issue described above. 

(4) Summary of Flexibility and Credit Provisions for Tractors and Engine 

Used in These Tractors

EPA and NHTSA are finalizing four flexibility provisions specifically for heavyduty tractor and engine manufacturers, as discussed in Section IV below. These are an 

averaging, banking and trading program for emissions and fuel consumption credits, as 

well as provisions for early credits, advanced technology credits, and credits for 

innovative vehicle or engine technologies which are not included as inputs to the GEM or 

are not demonstrated on the engine SET test cycle. With the exception of the advanced 

technology credits, credits generated under these provisions can only be used within the 

same averaging set which generated the credit (for example, credits generated by HD 

engines installed in tractors can only be used by HD engines). EPA is also adopting a 

N2O emission credit program, as described in Section IV below.

(5) Deferral of Standards for Tractor and Engine Manufacturing Companies 

That Are Small Businesses

EPA and NHTSA are not adopting greenhouse gas emissions and fuel 

consumption standards for small tractor or engine manufacturers meeting the Small 

Business Administration (SBA) size criteria of a small business as described in 13 CFR 

121.201.109 The agencies will instead consider appropriate GHG and fuel consumption 

standards for these entities as part of a future regulatory action. This includes both U.S.-

based and foreign small volume heavy-duty tractor and engine manufacturers.

The agencies have identified two entities that fit the SBA size criterion of a small 

business.110 The agencies estimate that these small entities comprise less than 0.5 percent 

 

109 See §1036.150 and §1037.150 

110 The agencies have identified Ottawa Truck, Inc. and Kalmar Industries USA as two potential small 

tractor manufacturers.
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of the total heavy-duty combination tractors in the United States based on Polk 

Registration Data from 2003 through 2007,111 and therefore that the exemption will have 

a negligible impact on the GHG emissions and fuel consumption improvements from the 

final standards. 

To ensure that the agencies are aware of which companies would be exempt, we 

are requiring that such entities submit a declaration to EPA and NHTSA containing a 

detailed written description of how that manufacturer qualifies as a small entity under the 

provisions of 13 CFR 121.201. 

C. Heavy-Duty Pickup Trucks and Vans

The primary elements of the EPA and NHTSA programs for complete HD 

pickups and vans are presented in this section. These provisions also cover optional 

chassis certification of incomplete HD vehicles and of Class 4 and 5 vehicles, as 

discussed in detail in Section V.B(1)(e). Section II.C(1) explains the form of the CO2 and 

fuel consumption standards, the numerical levels for those standards, and the approach to 

phasing in the standards over time. The measurement procedure for determining 

compliance is discussed in Section II.C(2), and the EPA and NHTSA compliance 

programs are discussed in Section II.C(3). Section II.C(4) discusses implementation 

flexibility provisions. Section II.E discusses additional standards and provisions for N2O 

and CH4 emissions, for vehicle air conditioning leakage, and for ethanol-fueled and 

electric vehicles. HD pickup and van air conditioning efficiency is not being regulated, 

for reasons discussed in Section II.E.

(1) What Are the Levels and Timing of HD Pickup and Van Standards?

(a) Vehicle-Based Standards

About 90 percent of Class 2b and 3 vehicles are pickup trucks, passenger vans, 

and work vans that are sold by the original equipment manufacturers as complete 

vehicles, ready for use on the road. In addition, most of these complete HD pickups and 

vans are covered by CAA vehicle emissions standards for criteria pollutants today (i.e., 

they are chassis tested similar to light-duty), expressed in grams per mile. This 

distinguishes this category from other, larger heavy-duty vehicles that typically have only 

the engines covered by CAA engine emission standards, expressed in grams per brake 

horsepower-hour. As a result, Class 2b and 3 complete vehicles share much more in 

common with light-duty trucks than with other heavy-duty vehicles.

Three of these commonalities are especially significant: (1) over 95 percent of the 

HD pickups and vans sold in the United States are produced by Ford, General Motors, 

and Chrysler – three companies with large light-duty vehicle and light-duty truck sales in 

the United States, (2) these companies typically base their HD pickup and van designs on 

higher sales volume light-duty truck platforms and technologies, often incorporating new 

light-duty truck design features into HD pickups and vans at their next design cycle, and 

(3) at this time most complete HD pickups and vans are certified to vehicle-based rather 

 

111 M.J. Bradley. Heavy-duty Vehicle Market Analysis. May 2009.
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than engine-based EPA standards. There is also the potential for substantial GHG and 

fuel consumption reductions from vehicle design improvements beyond engine changes 

(such as through optimizing aerodynamics, weight, tires, and accessories), and the 

manufacturer is generally responsible for both engine and vehicle design. All of these 

factors together suggest that it is appropriate and reasonable to set standards for the 

vehicle as a whole, rather than to establish separate engine and vehicle GHG and fuel 

consumption standards, as is being done for the other heavy-duty categories. This 

approach for complete vehicles is consistent with Recommendation 8-1 of the NAS 

Report, which encourages the regulation of “the final stage vehicle manufacturers since 

they have the greatest control over the design of the vehicle and its major subsystems that 

affect fuel consumption.” There was consensus in the public comments supporting this 

approach.

(b) Work-Based Attributes

In setting heavy-duty vehicle standards it is important to take into account the 

great diversity of vehicle sizes, applications, and features. That diversity reflects the 

variety of functions performed by heavy-duty vehicles, and this in turn can affect the kind 

of technology that is available to control emissions and reduce fuel consumption, and its 

effectiveness. EPA has dealt with this diversity in the past by making weight-based 

distinctions where necessary, for example in setting HD vehicle standards that are 

different for vehicles above and below 10,000 lb GVWR, and in defining different 

standards and useful life requirements for light-, medium-, and heavy-heavy-duty 

engines. Where appropriate, distinctions based on fuel type have also been made, though 

with an overall goal of remaining fuel-neutral. 

The joint EPA GHG and NHTSA fuel economy rules for light-duty vehicles 

accounted for vehicle diversity in that segment by basing standards on vehicle footprint 

(the wheelbase times the average track width). Passenger cars and light trucks with 

larger footprints are assigned numerically higher target levels for GHGs and numerically 

lower target levels for fuel economy in acknowledgement of the differences in 

technology as footprint gets larger, such that vehicles with larger footprints have an 

inherent tendency to burn more fuel and emit more GHGs per mile of travel. Using a 

footprint-based attribute to assign targets also avoids interfering with the ability of the 

market to offer a variety of products to maintain consumer choice. 

In developing this rulemaking, the agencies emphasized creating a program 

structure that would achieve reductions in fuel consumption and GHGs based on how 

vehicles are used and on the work they perform in the real world, consistent with the

NAS report recommendations to be mindful of HD vehicles’ unique purposes. Despite 

the HD pickup and van similarities to light-duty vehicles, we believe that the past 

practice in EPA’s heavy-duty program of using weight-based distinctions in dealing with 

the diversity of HD pickup and van products is more appropriate than using vehicle 

footprint. Work-based measures such as payload and towing capability are key among 

the things that characterize differences in the design of vehicles, as well as differences in 

how the vehicles will be used. Vehicles in this category have a wide range of payload and 

towing capacities. These work-based differences in design and in-use operation are the 
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key factors in evaluating technological improvements for reducing CO2 emissions and 

fuel consumption. Payload has a particularly important impact on the test results for HD 

pickup and van emissions and fuel consumption, because testing under existing EPA 

procedures for criteria pollutants is conducted with the vehicle loaded to half of its 

payload capacity (rather than to a flat 300 lb as in the light-duty program), and the 

correlation between test weight and fuel use is strong. 112 

Towing, on the other hand, does not directly factor into test weight as nothing is 

towed during the test. Hence only the higher curb weight caused by heavier truck 

components would play a role in affecting measured test results. However towing 

capacity can be a significant factor to consider because HD pickup truck towing 

capacities can be quite large, with a correspondingly large effect on design.

We note too that, from a purchaser perspective, payload and towing capability

typically play a greater role than physical dimensions in influencing purchaser decisions 

on which heavy-duty vehicle to buy. For passenger vans, seating capacity is of course a 

major consideration, but this correlates closely with payload weight.

Although heavy-duty vehicles are traditionally classified by their GVWR, we do 

not believe that GVWR is the best weight-based attribute on which to base GHG and fuel 

consumption standards for this group of vehicles. GVWR is a function of not only

payload capacity but of vehicle curb weight as well; in fact, it is the simple sum of the 

two. Allowing more GHG emissions from vehicles with higher curb weight tends to 

penalize lightweighted vehicles with comparable payload capabilities by making them 

meet more stringent standards than they would have had to meet without the weight 

reduction. The same would be true for another common weight-based measure, the gross 

vehicle combination weight, which adds the maximum combined towing and payload 

weight to the curb weight. 

Similar concerns about using weight-based attributes that include vehicle curb 

weight were raised in the EPA/NHTSA proposal for light-duty GHG and fuel economy 

standards: “footprint-based standards provide an incentive to use advanced lightweight 

materials and structures that would be discouraged by weight-based standards”, and 

“there is less risk of ‘gaming’ (artificial manipulation of the attribute(s) to achieve a more 

favorable target) by increasing footprint under footprint-based standards than by

increasing vehicle mass under weight-based standards—it is relatively easy for a 

manufacturer to add enough weight to a vehicle to decrease its applicable fuel economy 

target a significant amount, as compared to increasing vehicle footprint” (74 FR 49685, 

September 28, 2009). The agencies believe that using payload and towing capacities as 

the work-based attributes avoids the above-mentioned disincentive for the use of 

lightweighting technology by taking vehicle curb weight out of the standards 

determination. 

 

112 Section II.C(2) discusses our decision that GHGs and fuel consumption for HD pickups and vans be 

measured using the same test conditions as in the existing EPA program for criteria pollutants.
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After taking these considerations into account, EPA and NHTSA proposed to set 

standards for HD pickups and vans based on the proposed “work factor” attribute that 

combines vehicle payload capacity and vehicle towing capacity, in pounds, with an 

additional fixed adjustment for four-wheel drive (4wd) vehicles. This adjustment 

accounts for the fact that 4wd, critical to enabling the many off-road heavy-duty work 

applications, adds roughly 500 lb to the vehicle weight. There was consensus in the 

public comments supporting this attribute, and the agencies are adopting it as proposed. 

Target GHG and fuel consumption standards will be determined for each vehicle with a 

unique work factor (analogous to a target for each discrete vehicle footprint in the lightduty vehicle rules). These targets will then be production weighted and summed to 

derive a manufacturer’s annual fleet average standard for its heavy-duty pickups and 

vans. Widespread support for the proposed work factor-based approach to standards and 

fleet average approach to compliance was expressed in the comments we received.

To ensure consistency and help preclude gaming, we are finalizing the proposed 

provision that payload capacity be defined as GVWR minus curb weight, and towing 

capacity as GCWR minus GVWR. For purposes of determining the work factor, GCWR 

is defined according to the Society of Automotive Engineers (SAE) Recommended 

Practice J2807 APR2008, GVWR is defined consistent with EPA’s criteria pollutants 

program, and curb weight is defined as in 40 CFR 86.1803-01. Based on analysis of how 

CO2 emissions and fuel consumption correlate to work factor, we believe that a straight 

line correlation is appropriate across the spectrum of possible HD pickups and vans, and 

that vehicle distinctions such as Class 2b versus Class 3 need not be made in setting 

standards levels for these vehicles.113 This approach was supported by commenters.

We note that payload/towing-dependent gram per mile and gallon per 100 mile 

standards for HD pickups and vans parallel the gram per ton-mile and gallon per 1,000 

ton-mile standards being finalized for Class 7 and 8 combination tractors and for 

vocational vehicles. Both approaches account for the fact that more work is done, more 

fuel is burned, and more CO2 is emitted in moving heavier loads than in moving lighter 

loads. Both of these load-based approaches avoid penalizing vehicle designers wishing 

to reduce GHG emissions and fuel consumption by reducing the weight of their trucks. 

However, the sizeable diversity in HD work truck and van applications, which go well 

beyond simply transporting freight, and the fact that the curb weights of these vehicles 

are on the order of their payload capacities, suggest that setting simple gram/ton-mile and 

gallon/ton-mile standards for them is not appropriate. Even so, we believe that our 

setting of payload-based standards for HD pickups and vans is consistent with the NAS 

Report’s recommendation in favor of load-specific fuel consumption standards. Again, 

commenters agreed with this approach to setting HD pickup and van standards.

These attribute-based CO2 and fuel consumption standards are meant to be 

relatively consistent from a stringency perspective. Vehicles across the entire range of 

the HD pickup and van segment have their respective target values for CO2 emissions and 

fuel consumption, and therefore all HD pickups and vans will be affected by the standard. 

 

113 Memorandum from Anthony Neam and Jeff Cherry, U.S.EPA, to docket EPA-HQ-OAR-2010-0162, 

October 18, 2010.
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With this attribute-based standards approach, EPA and NHTSA believe there should be 

no significant effect on the relative distribution of vehicles with differing capabilities in 

the fleet, which means that buyers should still be able to purchase the vehicle that meets 

their needs.

(c) Standards

The agencies are finalizing standards based on a technology analysis performed 

by EPA to determine the appropriate HD pickup and van standards. This analysis, 

described in detail in RIA Chapter 2, considered:

 the level of technology that is incorporated in current new HD pickups and vans, 

 the available data on corresponding CO2 emissions and fuel consumption for these 

vehicles, 

 technologies that would reduce CO2 emissions and fuel consumption and that are 

judged to be feasible and appropriate for these vehicles through the 2018 model year, 

 the effectiveness and cost of these technologies for HD pickup and vans, 

 projections of future U.S. sales for HD pickup and vans, and 

 forecasts of manufacturers’ product redesign schedules.

Based on this analysis, EPA is finalizing the proposed CO2 attribute-based target 

standards shown in Figure II-2 and II-3, and NHTSA is finalizing the equivalent 

attribute-based fuel consumption target standards, also shown in Figure II-2 and II-3, 

applicable in model year 2018. These figures also shows phase-in standards for model 

years before 2018, and their derivation is explained below, along with alternative 

implementation schedules to ensure equivalency between the EPA and NHTSA programs 

while meeting respective statutory obligations. Also, for reasons discussed below, the 

agencies proposed and are establishing separate targets for gasoline-fueled (and any 

other Otto-cycle) vehicles and diesel-fueled (and any other Diesel-cycle) vehicles. The 

targets will be used to determine the production-weighted fleet average standards that 

apply to the combined diesel and gasoline fleet of HD pickups and vans produced by a 

manufacturer in each model year.
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Figure II-2: EPA CO2 Target Standards and NHTSA Fuel Consumption Target Standards for Diesel 

HD Pickups and Vans114

 

114 The NHTSA program provides voluntary standards for model years 2014 and 2015. Target line 

functions for 2016-2018 are for the second NHTSA alternative described in Section II.C(d)(ii).

300

350

400

450

500

550

600

650

700

750

800

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

Work Factor (pounds)

CO2 (grams per mile)

2.95

3.95

4.95

5.95

6.95

Fuel Consumption (gallons per 100 miles)

Diesel Vehicles

2018

2017

2015

2014

2016

300

350

400

450

500

550

600

650

700

750

800

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

Work Factor (pounds)

CO2 (grams per mile)

2.95

3.95

4.95

5.95

6.95

Fuel Consumption (gallons per 100 miles)

Diesel Vehicles

2018

2017

2015

2014

2016
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Figure II-3: EPA CO2 Target Standards and NHTSA Fuel Consumption Target Standards for 

Gasoline HD Pickups and Vans115

Described mathematically, EPA’s and NHTSA’s target standards are defined by

the following formulae:

EPA CO2 Target (g/mile) = [a x WF] + b

NHTSA Fuel Consumption Target (gallons/100 miles) = [c x WF] + d

Where:

WF = Work Factor = [0.75 x (Payload Capacity + xwd)] + [0.25 x Towing 

Capacity]

Payload Capacity = GVWR (lb) – Curb Weight (lb)

xwd = 500 lb if the vehicle is equipped with 4wd, otherwise equals 0 lb

Towing Capacity = GCWR (lb) – GVWR (lb)

Coefficients a, b, c, and d are taken from Table II-12 or Table II-13.

 

115 The NHTSA program provides voluntary standards for model years 2014 and 2015. Target line

functions for 2016-2018 are for the second NHTSA alternative described in Section II.C(d)(ii).

300

350

400

450

500

550

600

650

700

750

800

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

Work Factor (pounds)

CO2 (grams per mile)

3.38

4.38

5.38

6.38

7.38

8.38

Fuel Consumption (gallons per 100 miles)

Gasoline Vehicles

2018

2017

2015

2014

2016

300

350

400

450

500

550

600

650

700

750

800

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

Work Factor (pounds)

CO2 (grams per mile)

3.38

4.38

5.38

6.38

7.38

8.38

Fuel Consumption (gallons per 100 miles)

Gasoline Vehicles

2018

2017

2015

2014

2016
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Table II-12: Coefficients for HD Pickup and Van Target Standards 116

Diesel Vehicles

Model Year a b c d

2014 0.0478 368 0.000470 3.61

2015 0.0474 366 0.000466 3.60

2016 0.0460 354 0.000452 3.48

2017 0.0445 343 0.000437 3.37

2018 and later 0.0416 320 0.000409 3.14

Gasoline Vehicles

Model Year a b c d

2014 0.0482 371 0.000542 4.17

2015 0.0479 369 0.000539 4.15

2016 0.0469 362 0.000528 4.07

2017 0.0460 354 0.000518 3.98

2018 and later 0.0440 339 0.000495 3.81

Table II-13: Coefficients for NHTSA’s First Alternative and EPA’s Alternative HD Pickup and Van 

Target Standards

Diesel Vehicles

Model Year a b c d

2014a0.0478 368 0.000470 3.61

2015a0.0474 366 0.000466 3.60

2016-2018 0.0440 339 0.000432 3.33

2019 and later 0.0416 320 0.000409 3.14

Gasoline Vehicles

Model Year a b c d

2014a0.0482 371 0.000542 4.17

2015a0.0479 369 0.000539 4.15

2016-2018 0.0456 352 0.000513 3.96

2019 and later 0.0440 339 0.000495 3.81

Notes:

a NHTSA standards will be voluntary in 2014 and 2015

These targets are based on a set of vehicle, engine, and transmission technologies 

assessed by the agencies and determined to be feasible and appropriate for HD pickups 

and vans in the 2014-2018 time frame. See Section III.B for a detailed analysis of these 

 

116 The NHTSA program provides voluntary standards for model years 2014 and 2015. Target line 

functions for 2016-2018 are for the second NHTSA alternative described in Section II.C(d)(ii).
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vehicle, engine and transmission technologies, including their feasibility, costs, and 

effectiveness in HD pickups and vans.

To calculate a manufacturer’s HD pickup and van fleet average standard, the 

agencies are requiring that separate target curves be used for gasoline and diesel vehicles. 

The agencies estimate that in 2018 the target curves will achieve 15 and 10 percent 

reductions in CO2 and fuel consumption for diesel and gasoline vehicles, respectively, 

relative to a common baseline for current (model year 2010) HD pickup trucks and vans. 

An additional two percent reduction in GHGs will be achieved by the direct air 

conditioning leakage standard in the EPA standards. These reductions are based on the 

agencies’ assessment of the feasibility of incorporating technologies (which differ 

significantly for gasoline and diesel powertrains) in the 2014-2018 model years, and on 

the differences in relative efficiency in the current gasoline and diesel vehicles. The 

resulting reductions represent roughly equivalent stringency levels for gasoline and diesel 

vehicles, which is important in ensuring our program maintains product choices available 

to vehicle buyers. 

In written comments on the proposal, Cummins objected to setting separate diesel 

and gasoline vehicle standards, on the basis that it increases the burden for diesel engine 

manufacturers more than for gasoline engine manufacturers, and thereby could shift 

market share away from diesels. EMA argued for fuel-neutrality based on historical 

precedent and the fact that GHGs emitted by one type of engine are no different than 

those emitted by another type of engine. We believe that both engine types have roughly 

equivalent redesign burdens as evidenced by the feasibility and cost analysis in RIA 

Chapter 2. Also, even though the emissions and fuel consumption reductions are 

expressed from a common diesel/gasoline baseline in these final rules, the actual starting 

base for diesels is at a lower level than for gasoline vehicles. Other industry commenters, 

including those with sizeable diesel sales, expressed general support for the standards. 

The agencies agree that standards that do not distinguish between fuel types are generally 

preferable where technological or market-based reasons do not strongly argue otherwise. 

These technological differences exist presently between gasoline and diesel engines for 

GHGs, as described above. The agencies emphasize, however, that they are not 

committed to perpetuating separate GHG standards for gasoline and diesel heavy-duty 

vehicles and engines, and expect to reexamine the need for separate gasoline/diesel 

standards in the next rulemaking.

Environmental groups and others commented that the proposed standards were 

not stringent enough, citing the heavy-duty vehicle NAS study finding that technologies 

such as hybridization are feasible. However, in the ambitious time frame we are focusing 

on for these rules, targeting as it does technologies implementable in the HD pickup and 

van fleet starting in 2014 and phasing in with normal product redesign cycles through 

2018, our assessment shows that the standards we are establishing are appropriate. More 

advanced technologies considered in the NAS report would be appropriate for 

consideration in future rulemaking activity. Additional conventional technologies 

identified by commenters as promising in light-duty applications and potentially useful 

for HD applications are discussed in RIA Chapter 2.
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The NHTSA fuel consumption target curves and the EPA GHG target curves are 

equivalent. The agencies established the target curves using the direct relationship 

between fuel consumption and CO2 using conversion factors of 8,887 g CO2/gallon for 

gasoline and 10,180 g CO2/gallon for diesel fuel.

It is expected that measured performance values for CO2 will generally be 

equivalent to fuel consumption. However, as explained below in Section II. E. (3) , EPA 

is finalizing a provision for manufacturers to use CO2 credits to help demonstrate 

compliance with N2O and CH4 emissions standards, by expressing any N2O and CH4

undercompliance in terms of their CO2-equivalent and applying the needed CO2 credits. 

For test families that do not use this compliance alternative, the measured performance 

values for CO2 and fuel consumption will be equivalent because the same test runs and 

measurement data will be used to determine both values, and calculated fuel consumption 

will be based on the same conversion factors that are used to establish the relationship 

between the CO2 and fuel consumption target curves (8,887 g CO2/gallon for gasoline 

and 10,180 g CO2/gallon for diesel fuel). For manufacturers that choose to use the EPA 

provision for CO2 credit use in demonstrating N2O and CH4 compliance, compliance with 

the CO2 standard will not be directly equivalent to compliance with the NHTSA fuel 

consumption standard. 

(d) Implementation Plan

(i) EPA Program Phase-in MY 2014-2018

EPA is finalizing the proposed provision that the GHG standards be phased in 

gradually over the 2014-2018 model years, with full implementation effective in the 2018 

model year. Therefore, 100 percent of a manufacturer’s vehicle fleet will need to meet a

fleet-average standard that will become increasingly more stringent each year of the 

phase-in period. For both gasoline and diesel vehicles, this phase-in will be 15-20-40-60-

100 percent of the model year 2018 stringency in model years 2014-2015-2016-2017-

2018, respectively. These percentages reflect stringency increases from a baseline 

performance level for model year 2010, determined by the agencies based on EPA and 

manufacturer data. Because these vehicles are not currently regulated for GHG

emissions, this phase-in takes the form of target line functions for gasoline and diesel 

vehicles that become increasingly stringent over the phase-in model years. These yearby-year functions have been derived in the same way as the 2018 function, by taking a 

percent reduction in CO2 from a common unregulated baseline. For example, in 2014 the 

reduction for both diesel and gasoline vehicles will be 15% of the fully-phased-in 

reductions. Figures II-2 and II-3, and Table II-12, reflect this phase-in approach.

EPA is also providing manufacturers with an optional alternative implementation 

schedule in model years 2016 through 2018, equivalent to NHTSA’s first alternative for 

standards that do not change over these model years, described below. Under this option 

the phase-in will be 15-20-67-67-67-100 percent of the model year 2019 stringency in 

model years 2014-2015-2016-2017-2018-2019, respectively. Table II-13, above, 

provides the coefficients “a” and “b” for this manufacturer’s alternative. As explained 

below, this alternative will provide roughly equivalent overall CO2 reductions and fuel 

consumption improvements as the 15-20-40-60-100 percent phase-in. In addition, as 
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explained below, the stringency of this alternative was established by NHTSA such that a 

manufacturer with a stable production volume and mix over the model year 2016-2018 

period could use Averaging, Banking and Trading to comply with either alternative and 

have a similar credit balance at the end of model year 2018.

Under the above-described alternatives, each manufacturer will need to 

demonstrate compliance with the applicable fleet average standard using that year’s 

target function over all of its HD pickups and vans starting with its MY 2014 fleet of HD 

pickups and vans. No comments were received in support of an alternative approach that 

EPA requested comment on, involving phasing in an annually increasing percentage of 

each manufacturer’s sales volume.

(ii) NHTSA Program Phase-in 2016 and Later

NHTSA is finalizing the proposed provision to allow manufacturers to select one 

of two fuel consumption standard alternatives for model years 2016 and later. Each 

manufacturer will select an alternative in its joint pre-model year report, discussed below, 

that is now required to be electronically submitted to the agencies; and, once selected, the 

alternative will apply for model years 2016 and later, and cannot be reversed. The first 

alternative will define a fuel consumption target line function for gasoline vehicles and a 

target line function for diesel vehicles that will not change for model years 2016 to 2018. 

The target line function coefficients are provided in Table II-13. 

The second alternative will be equivalent to the EPA target line functions in each 

model year starting in 2016 and continuing afterwards. Stringency of fuel consumption 

standards will increase gradually for the 2016 and later model years. Relative to a model 

year 2010 unregulated baseline for both gasoline and diesel vehicles, stringency will be 

40, 60, and 100 percent of the 2018 target line function in model years 2016, 2017, and 

2018, respectively. The stringency of the target line functions in the first alternative for 

model years 2016-2017-2018-2019 is 67-67-67-100 percent, respectively, of the 2019 

stringency in the second alternative. The stringency of the first alternative was 

established so that a manufacturer with a stable production volume and mix over the 

model year 2016-2018 period could use Averaging, Banking and Trading to comply with 

either alternative and have a similar credit balance at the end of model year 2018 under 

the EPA and NHTSA programs.

(iii) NHTSA Voluntary Standards Period

NHTSA is finalizing the proposed provision that manufacturers may voluntarily

opt into the NHTSA HD pickup and van program in model years 2014 or 2015. If a 

manufacturer elects to opt into the program, it must stay in the program for all the 

optional model years. Manufacturers that opt in become subject to NHTSA standards for 

all regulatory categories. To opt into the program, a manufacturer must declare its intent 

to opt in to the program in its Pre-Model Year Report. The agencies have finalized new 

requirements for manufacturers to provide all early model declarations as a part of the 

pre-model year reports. See regulatory text for 49 CFR 535.8 for information related to 

the Pre-Model Year Report. A manufacturer would begin tracking credits and debits 
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beginning in the model year in which they opt into the program. The handling of credits 

and debits would be the same as for the mandatory program.

For manufacturers that opt into NHTSA’s HD pickup and van fuel consumption 

program in 2014 or 2015, the stringency would increase gradually each model year. 

Relative to a model year 2010 unregulated baseline, for both gasoline and diesel vehicles, 

stringency would be 15-20 percent of the model year 2019 target line function stringency

(under the NHTSA first alternative) and 15-20 percent of the model year 2018 target line 

function stringency (under the NHTSA second alternative) in model years 2014-2015, 

respectively. The corresponding absolute standards targets levels are provided in Figure 

II-2 and II-3, and the accompanying equations. 

(2) What Are the HD Pickup and Van Test Cycles and Procedures?

EPA and NHTSA are finalizing the proposed provision that HD pickup and van 

testing be conducted using the same heavy-duty chassis test procedures currently used by 

EPA for measuring criteria pollutant emissions from these vehicles, but with the addition 

of the highway fuel economy test cycle (HFET) currently required only for light-duty

vehicle GHG emissions and fuel economy testing. Although the highway cycle driving 

pattern is identical to that of the light-duty test, other test parameters for running the 

HFET, such as test vehicle loaded weight, are identical to those used in running the 

current EPA Federal Test Procedure for complete heavy-duty vehicles.

The GHG and fuel consumption results from vehicle testing on the Light-duty

FTP and the HFET will be weighted by 55 percent and 45 percent, respectively, and then 

averaged in calculating a combined cycle result. This result corresponds with the data 

used to develop the work factor-based CO2 and fuel consumption standards, since the 

data on the baseline and technology efficiency was also developed in the context of these 

test procedures. The addition of the HFET and the 55/45 cycle weightings are the same 

as for the light-duty CO2 and CAFE programs, as we believe the real world driving 

patterns for HD pickups and vans are not too unlike those of light-duty trucks, and we are 

not aware of data specifically on these patterns that would lead to a different choice of 

cycles and weightings, nor did any commenters provide such data. More importantly, we 

believe that the 55/45 weightings will provide for effective reductions of GHG emissions 

and fuel consumption from these vehicles, and that other weightings, even if they were to 

more precisely match real world patterns, are not likely to significantly improve the 

program results.

Another important parameter in ensuring a robust test program is vehicle test 

weight. Current EPA testing for HD pickup and van criteria pollutants is conducted with 

the vehicle loaded to its Adjusted Loaded Vehicle Weight (ALVW), that is, its curb 

weight plus 1⁄2 of the payload capacity. This is substantially more challenging than 

loading to the light-duty vehicle test condition of curb weight plus 300 pounds, but we 

believe that this loading for HD pickups and vans to 1⁄2 payload better fits their usage in 

the real world and will help ensure that technologies meeting the standards do in fact 

provide real world reductions. The choice is likewise consistent with use of an attribute 

based in considerable part on payload for the standard. We see no reason to set test load 

conditions differently for GHGs and fuel consumption than for criteria pollutants, and we 
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are not aware of any new information (such as real world load patterns) since the ALVW 

was originally set this way that would support a change in test loading conditions, nor did 

any commenters provide such information. We are therefore using ALVW for test 

vehicle loading in GHG and fuel consumption testing.

Additional provisions for our final testing and compliance program are provided 

in Section V.B.

(3) How Are the HD Pickup and Van Standards Structured?

EPA and NHTSA are finalizing the proposed fleet average standards for new HD 

pickups and vans, based on a manufacturer’s new vehicle fleet makeup. In addition, EPA 

is finalizing proposed in-use standards that apply to the individual vehicles in this fleet 

over their useful lives. The compliance provisions for these fleet average and in-use 

standards for HD pickups and vans are largely based on the recently promulgated lightduty GHG and fuel economy program, as described in detail in the proposal. 

(a) Fleet Average Standards

In the programs we are finalizing, each manufacturer will have a GHG standard 

and a fuel consumption standard unique to its new HD pickup and van fleet in each 

model year, depending on the load capacities of the vehicle models produced by that 

manufacturer, and on the U.S.-directed production volume of each of those models in that 

model year. Vehicle models with larger payload/towing capacities have individual 

targets at numerically higher CO2 and fuel consumption levels than lower payload/towing 

vehicles, as discussed in Section II.C(1). The fleet average standard for a manufacturer is 

a production-weighted average of the work factor-based targets assigned to unique

vehicle configurations within each model type produced by the manufacturer in a model 

year.

The fleet average standard with which the manufacturer must comply is based on 

its final production figures for the model year, and thus a final assessment of compliance 

will occur after production for the model year ends. Because compliance with the fleet 

average standards depends on actual test group production volumes, it is not possible to 

determine compliance at the time the manufacturer applies for and receives an EPA 

certificate of conformity for a test group. Instead, at certification the manufacturer will 

demonstrate a level of performance for vehicles in the test group, and make a good faith 

demonstration that its fleet, regrouped by unique vehicle configurations within each 

model type, is expected to comply with its fleet average standard when the model year is 

over. EPA will issue a certificate for the vehicles covered by the test group based on this 

demonstration, and will include a condition in the certificate that if the manufacturer does 

not comply with the fleet average, then production vehicles from that test group will be 

treated as not covered by the certificate to the extent needed to bring the manufacturer’s 

fleet average into compliance. As in the light-duty program, additional “model type” 

testing will be conducted by the manufacturer over the course of the model year to 

supplement the initial test group data. The emissions and fuel consumption levels of the 

test vehicles will be used to calculate the production-weighted fleet averages for the 
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manufacturer, after application of the appropriate deterioration factor to each result to 

obtain a full useful life value. See generally 75 FR 25470-25472.

EPA and NHTSA do not currently anticipate notable deterioration of CO2

emissions and fuel consumption performance, and are therefore requiring that an assigned 

deterioration factor be applied at the time of certification: an additive assigned 

deterioration factor of zero, or a multiplicative factor of one will be used. EPA and 

NHTSA anticipate that the deterioration factor may be updated from time to time, as new 

data regarding emissions deterioration for CO2 are obtained and analyzed. Additionally, 

EPA and NHTSA may consider technology-specific deterioration factors, should data 

indicate that certain control technologies deteriorate differently than others. See also 75 

FR 25474.

(b) In-Use Standards

Section 202(a)(1) of the CAA specifies that EPA set emissions standards that are 

applicable for the useful life of the vehicle. The in-use standards that EPA is finalizing 

apply to individual vehicles. NHTSA is not adopting in-use standards because they are 

not required under EISA, and because it is not currently anticipated that there will be any

notable deterioration of fuel consumption. For the EPA program, compliance with the inuse standard for individual vehicles and vehicle models will not impact compliance with 

the fleet average standard, which will be based on the production-weighted average of the 

new vehicles.

EPA is finalizing the proposed provision that the in-use standards for HD pickups 

and vans be established by adding an adjustment factor to the full useful life emissions 

and fuel consumption results used to calculate the fleet average. EPA is also finalizing 

the proposed provision that the useful life for these vehicles with respect to GHG 

emissions be set equal to their useful life for criteria pollutants: 11 years or 120,000 

miles, whichever occurs first (40 CFR 86.1805-04(a)).

As discussed above, we are finalizing the proposed provision that certification test 

results obtained before and during the model year be used directly to calculate the fleet 

average emissions for assessing compliance with the fleet average standard. Therefore,

this assessment and the fleet average standard itself do not take into account test-to-test 

variability and production variability that can affect measured in-use levels. For this 

reason, EPA is finalizing the proposed adjustment factor for the in-use standard to 

provide some margin for production and test-to-test variability that could result in 

differences between the initial emission test results used to calculate the fleet average and 

emission results obtained during subsequent in-use testing. EPA is finalizing the 

proposed provision that each model’s in-use CO2 standard be the model-specific level 

used in calculating the fleet average, plus 10 percent. This is the same as the approach 

taken for light-duty vehicle GHG in-use standards (See 75 FR 25473-25474). No adverse 

comments were received on this proposed provision.

As it does now for heavy-duty vehicle criteria pollutants, EPA will use a variety

of mechanisms to conduct assessments of compliance with the in-use standards, including 
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pre-production certification and in-use monitoring once vehicles enter customer service. 

The full useful life in-use standards apply to vehicles that have entered customer service. 

The same standards apply to vehicles used in pre-production and production line testing, 

except that deterioration factors are not applied.

(4) What HD Pickup and Van Flexibility Provisions Are Being Established?

This program contains substantial flexibility in how manufacturers can choose to 

implement the EPA and NHTSA standards while preserving their timely benefits for the 

environment and energy security. Primary among these flexibilities are the gradual 

phase-in schedule, alternative compliance paths, and corporate fleet average approach 

which encompasses averaging, banking and trading described above. Additional 

flexibility provisions are described briefly here and in more detail in Section IV.

As explained in Section II.C(3), we are finalizing the proposed provision that, at 

the end of each model year, when production for the model year is complete, a 

manufacturer calculate its production-weighted fleet average CO2 and fuel consumption. 

Under this approach, a manufacturer’s HD pickup and van fleet that achieves a fleet 

average CO2 or fuel consumption level better than its standard will be allowed to generate 

credits. Conversely, if the fleet average CO2 or fuel consumption level does not meet its 

standard, the fleet would incur debits (also referred to as a shortfall).

A manufacturer whose fleet generates credits in a given model year will have 

several options for using those credits to offset emissions from other HD pickups and 

vans. These options include credit carry-back, credit carry-forward, and credit trading. 

These provisions exist in the light-duty 2012-2016 MY vehicle rule, and similar 

provisions are part of EPA’s Tier 2 program for light-duty vehicle criteria pollutant 

emissions, as well as many other mobile source standards issued by EPA under the CAA. 

The manufacturer will be able to carry back credits to offset a deficit that had accrued in 

a prior model year and was subsequently carried over to the current model year, with a 

limitation on the carry-back of credits to three model years, consistent with the light-duty 

program. We are finalizing the proposed provision that, after satisfying any need to 

offset pre-existing deficits, a manufacturer may bank remaining credits for use in future 

years, with a limitation on the carry-forward of credits to five model years. We are also 

finalizing the proposed provision that manufacturers may certify their HD pickup and van 

fleet a year early, in MY 2013, to generate credits against the MY 2014 standards. This 

averaging, banking, and trading program for HD pickups and vans is discussed in more 

detail in Section IV.A. For reasons discussed in detail in that section, we are not 

finalizing any credit transferability to or from other credit programs or averaging sets.

Consistent with the President’s May 21, 2010 directive to promote advanced 

technology vehicles and with the agencies’ respective statutory authorities, we are 

adopting flexibility provisions that parallel similar provisions adopted in the light-duty 

program. These include credits for advance technology vehicles such as electric vehicles, 

and credits for innovative technologies that are shown by the manufacturer to provide 

GHG and fuel consumption reductions in real world driving, but not on the test cycle. 

See Section IV.B. 
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D. Class 2b-8 Vocational Vehicles

Heavy-duty vehicles serve a vast range of functions including service for urban 

delivery, refuse hauling, utility service, dump, concrete mixing, transit service, shuttle 

service, school bus, emergency, motor homes,117 and tow trucks to name only a small 

subset of the full range of vehicles. The vehicles designed to serve these functions are as 

unique as the jobs they do. They are vastly different – one from the other – in size, shape 

and function. The agencies were unable to develop a specific vehicle definition based on 

the characteristics of these vehicles. Instead at proposal, we proposed to define that Class 

2b-8 vocational vehicles as all heavy-duty vehicles which are not included in the Heavyduty Pickup Truck and Van or the Class 7 and 8 Tractor categories. In effect, we said 

everything that is not a combination tractor or a pickup truck or van is a vocational 

vehicle. We are finalizing that definition as proposed reflecting the same challenges we 

faced at proposal regarding defining the full range of heavy-duty vehicles. As at 

proposal, recreational vehicles are included under EPA’s standards but are not included 

under NHTSA’s final standards. The agencies note that we are adding vocational tractors 

to the vocational vehicle category in the final rulemaking, as described above in Section 

II.B. 

The agencies proposed that Class 4 pickup trucks although similar to Class 2b and 

3 vehicles be included in the vocational vehicle category. Comments from EMA, 

Cummins, NTEA and Navistar supported the premise that Class 4 vehicles belong as part 

of the vocational vehicle program because they are specifically designed and engineered 

to meet vocational requirements. They stated that components such as transmissions, 

axles, frames, and tires differ from the similar pickup trucks and vans in the Class 2b and 

3 market. We agree with commenters’ arguments that there are a number of important 

differences between the Class 4 and Class 3 trucks it unreasonable to regulate Class 4 

vehicles under the standards for heavy duty pickups and vans. As a result, we are 

keeping Class 4 vehicles in the vocational vehicle category, but are allowing the optional 

chassis certification of Class 4 and 5 vehicles. (See Section V.B(1)(e)). 

As mentioned in Section I, vocational vehicles undergo a complex build process. 

Often an incomplete chassis is built by a chassis manufacturer with an engine purchased 

from an engine manufacturer and a transmission purchased from another manufacturer. 

A body manufacturer purchases an incomplete chassis which is then completed by

attaching the appropriate features to the chassis. 

The diversity in the vocational vehicle segment can be primarily attributed to the 

variety of vehicle bodies rather than to the chassis. For example, a body builder can build 

either a Class 6 bucket truck or a Class 6 delivery truck from the same Class 6 chassis. 

The aerodynamic difference between these two vehicles due to their bodies will lead to 

different baseline fuel consumption and GHG emissions. However, the baseline fuel 

consumption and emissions due to the components included in the common chassis (such 

as the engine, drivetrain, frame, and tires) will be the same between these two types of 

complete vehicles. 

 

117 See above for discussion of applicability of NHTSA’s standards to non-commercial vehicles.
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The agencies face difficulties in establishing the baseline CO2 and fuel 

consumption performance for the wide variety of complete vocational vehicles because 

of the very large number of vehicle types and the need to conduct testing on each of the 

vehicle types to establish the baseline. To establish standards for a complete vocational 

vehicle, it would be necessary to assess the potential for fuel consumption and GHG 

emissions improvement for each of these vehicle types and to establish standards for each 

vehicle type. Because of the size and complexity of this task, the agencies judged it was 

not practical to regulate complete vocational vehicles for this first fuel consumption and 

GHG emissions program. To overcome the lack of baseline information from the 

different vehicle types and to still achieve improvements to fuel consumption and GHG 

emissions, the agencies proposed to set standards for the chassis manufacturers of 

vocational vehicles (but not the body builders) and the engine manufacturers. Chassis 

manufacturers represent a limited number of companies as compared to body builders, 

which are made up of a diverse set of companies that are typically small businesses. 

These companies would need to be regulated if whole vehicle standards were established. 

Similar to combination tractors, the agencies proposed to set separate vehicle and 

engine standards for vocational vehicles. A number of comments were received on the 

proposal to regulate chassis and engine manufacturers. The agencies received comments 

from DTNA supporting the proposal to regulate the chassis manufacturer but not body

manufacturers. While organizations like Cummins and ICCT expressed support for 

separate engine and vehicle standards; Navistar, Pew, and Volvo, in contrast, opposed 

separate engine and chassis standards, stating that separate engine standards 

disadvantages integrated truck/engine manufacturers and full vehicle standards should be 

required. Volvo asked that the standards include an alternative integrated standard as 

well as complete vehicle modeling and testing beginning in 2017. ACEEE and Sierra 

Club stated that the proposed standards and test procedures should move the agencies 

closer to full vehicle testing. 

Although the agencies understand that full vehicle standards would allow 

integrated truck/engine manufacturers – such as electrified accessories and weight 

reduction -- the agencies are finalizing separate standards for vocational vehicles that 

apply to chassis manufacturers and engine standards for engines installed in these 

vehicles that apply to engine manufacturers. The agencies continue to believe that it is 

not practical to regulate complete vocational vehicles for this first fuel consumption and 

GHG emissions program because of the size and complexity of the task associated with 

assessing the potential for fuel consumption and GHG emissions improvement for each 

of the myriad types of vocational vehicles. This issue is discussed further in comment 

responses found in sections 5 and 6.1.4 of the Response to Comment Document, as well 

as in the following section of the preamble. Thus, the agencies are finalizing a set of 

standards for the chassis manufacturers of vocational vehicles (but not the body builders) 

and for the manufacturers of HD engines used in vocational vehicles. 
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(1) What Are the Vocational Vehicle and Engine CO2 and Fuel Consumption 

Standards and Their Timing?

In the NPRM, the agencies proposed vehicle standards based on the agencies’ 

assessment of the availability of low rolling resistance tires that could be applied 

generally to vocational vehicles across the entire category. The agencies considered the 

possibility of including other technologies in determining the proposed stringency of the 

vocational vehicle standards, such as aerodynamic improvements, but as discussed in the 

NPRM, tentatively concluded that such improvements would not be appropriate for 

basing vehicle standard stringency in this phase of the rulemaking.118 For example, the 

aerodynamics of a recovery vehicle are impacted significantly by the equipment such as 

the arm located on the exterior of the truck.119 The agencies found little opportunity to 

improve the aerodynamics of the equipment on the truck. The agencies also evaluated 

the aerodynamic opportunities discussed in the NAS report. The panel found that there 

was minimal fuel consumption reduction opportunity through aerodynamic technologies 

for bucket trucks, transit buses, and refuse trucks120 primarily due to the low vehicle 

speed in normal operation. The panel did report that there are opportunities to reduce the 

fuel consumption of straight trucks by approximately 1 percent for trucks which operate 

at the average speed typical of a pickup and delivery truck (30 mph), although the 

opportunity is greater for vehicles that operate at higher speeds.121 

The agencies received comments from the Motor Equipment Manufacturers 

Association, Eaton, NRDC, NESCAUM, NACAA, ACEEE, ICCT, Navistar, Arvin 

Meritor, the Union of Concerned Scientists and others that technologies such as idle 

reduction, advanced transmissions, advanced drivetrains, weight reduction, hybrid 

powertrains, and improved auxiliaries provide opportunities to reduce fuel consumption 

from vocational vehicles. Commenters asked that the agencies establish regulations that 

would reflect performance of these technologies and essentially force their utilization. 

The agencies assessed these technologies and have concluded that they may have 

the potential to reduce fuel consumption and GHG emissions from at least certain 

vocational vehicles, but the agencies have not been able to estimate baseline fuel 

consumption and GHG emissions levels for each type of vocational vehicle and for each 

type of technology, given the wide variety of models and uses of vocational vehicles. For 

example, idle reduction technologies such as APUs and cabin heaters can reduce 

workday idling associated with vocational vehicles. However, characterizing idling 

activity for the vocational segment in order to quantify the benefits of idle reduction 

technology is complicated by the variety of duty cycles found in the sector. Idling in 

school buses, fire trucks, pickup trucks, delivery trucks, and other types of vocational 

vehicles varies significantly. Given the great variety of duty cycles and operating 

conditions of vocational vehicles and the timing of these rules, it is not feasible at this

time to establish an accurate baseline for quantifying the expected improvements which 

could result from use of idle reduction technologies. Similarly, for advanced drivetrains 

 

118 See 75 FR at 74241

119 A recovery vehicle removes or recovers vehicles that are disabled (broken down).

120 See 2010 NAS Report, Note 21, page 133.

121 See 2010 NAS Report, Note 21, page 110.
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and advanced transmissions determining a baseline configuration, or a set of baseline 

configurations, is extremely difficult given the variety of trucks in this segment. The 

agencies do not believe that we can legitimately base standard stringency on the use of 

technologies for which we cannot identify baseline configurations, because absent 

baseline emissions and baseline fuel consumption, the emissions reductions achieved 

from introduction of the technology cannot be quantified. For some technologies, such as 

weight reduction and improved auxiliaries – such as electrically driven power steering 

pumps and the vehicle’s air conditioning system -- the need to limit technologies to those 

under the control of the chassis manufacturer further restricted the agencies’ options for 

predicating standard stringency on use of these technologies. For example, lightweight 

components that are under the control of chassis manufacturers are limited to a very few 

components such as frame rails. Considering the fuel efficiency and GHG emissions 

reduction benefits that will be achieved by finalizing these rules in the time frame

proposed, rather than delaying in order to gain enough information to include additional 

technologies, the agencies have decided to finalize standards that do not assume the use 

of these technologies and will consider incorporating them in a later action applicable to 

later model years. Cf. Sierra Club v. EPA, 325 F. 3d 374, 380 (D.C. Cir. 2003) (in 

implementing a technology-forcing provision of the CAA, EPA reasonably adopted 

modest initial controls on an industry sector in order to better assess rules’ effects in 

preparation for follow-up rulemaking).

As the program progresses and the agencies gather more information, we expect 

to reconsider whether vocational vehicle standards for MYs 2019 and beyond should be 

based on the use of additional technologies besides low rolling resistance tires.

EPA is adopting CO2 standards and NHTSA is finalizing fuel consumption 

standards for manufacturers of chassis for new vocational vehicles and for manufacturers 

of heavy-duty engines installed in these vehicles. The final heavy-duty engine standards 

for CO2 emissions and fuel consumption focus on potential technological improvements 

in fuel combustion and overall engine efficiency and those controls would achieve most 

of the emission reductions. Further reductions from the Class 2b-8 vocational vehicle 

itself are possible within the time frame of these final regulations. Therefore, the agencies 

are also finalizing separate standards for vocational vehicles that will focus on additional 

reductions that can be achieved through improvements in vehicle tires. The agencies’

analyses, as discussed briefly below and in more detail later in this preamble and in the 

RIA Chapter 2, show that these final standards appear appropriate under each agency’s 

respective statutory authorities. Together these standards are estimated to achieve 

reductions of up to 10 percent from most vocational vehicles.

EPA is also adopting standards to control N2O and CH4 emissions from Class 2b8 vocational vehicles through controlling these GHG emissions from the HD engines. 

The final heavy-duty engine standards for both N2O and CH4 and details of the standard 

are included in the discussion in Section II.E.1.b and II.E.2.b. EPA neither proposed nor 

is adopting air conditioning leakage standards applying to vocational vehicle chassis 

manufacturers. 
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As discussed further below, the agencies are setting CO2 and fuel consumption 

standards for the chassis based on tire rolling resistance improvements and for the 

engines based on engine technologies. The fuel consumption and GHG emissions impact 

of tire rolling resistance is impacted by the mass of the vehicle. However, the impact of 

mass on rolling resistance is relatively small so the agencies proposed to aggregate 

several vehicle weight categories under a single category for setting the standards. The 

agencies proposed to divide the vocational vehicle segment into three broad regulatory

subcategories - Light Heavy-Duty (Class 2b through 5), Medium Heavy-Duty (Class 6 

and 7), and Heavy Heavy-Duty (Class 8) which is consistent with the nomenclature used 

in the diesel engine classification. The agencies received comments supporting the 

division of vocational vehicles into three regulatory categories from DTNA. The 

agencies also received comments from Bosch, Clean Air Task Force, and National Solid 

Waste Management Association supporting a finer resolution of vocational vehicle 

subcategories. Their concerns include that the agencies’ vehicle configuration in GEM is 

not representative of a particular vocational application, such as refuse trucks. Another 

recommendation was to divide the category by both GVWR and by operational 

characteristics. Upon further consideration, the agencies are finalizing as proposed three 

vocational vehicle subcategories because we believe this adequately balances simplicity

while still obtaining reductions in this diverse segment. (As noted in section IV.A below, 

these three subcategories also denominate separate averaging sets for purposes of ABT.). 

Finer distinctions in regulatory subcategories would not change the technology basis for 

the standards or the reductions expected from the vocational vehicle category. As the 

agencies move towards future heavy-duty fuel consumption and GHG regulations for 

post-2017 model years, we intend to gather GHG and fuel consumption data for specific 

vocational applications which could be used to establish application-specific standards in 

the future.

The agencies received comments supporting the exclusion of recreational 

vehicles, emergency vehicles, school buses from the vocational vehicle standards. The 

commenters argued that these individual vehicle types were small contributors to overall 

GHG emissions and that tires meeting their particular performance needs might not be 

available by 2014. The agencies considered these comments and the agencies have met 

with a number of tire manufacturers to better understand their expectations for product 

availability for the 2014 model year. Based on our review of the information shared, we 

are convinced that tires with rolling resistance consistent with our final vehicle standards 

and meeting the full range of other performance characteristics desired in the vehicle 

market, including for RVs, emergency vehicles, and school buses, will be broadly

available by the 2014 model year.122 Absent regulations for the vast majority of vehicles 

in this segment, feasible cost-effective reductions available at reasonable cost in the 

2014-2018 model years will be needlessly foregone. Therefore, the agencies have 

decided to finalize the vocational vehicle standards as proposed with recreational 

vehicles, emergency vehicles and school buses included in the vocational vehicle 

category. As RVs were not included by NHTSA for proposed regulation, they are not 

within the scope of the NPRM and are therefore excluded in NHTSA’s portion of the 

 

122 Bachman, Joseph. Memorandum to the Docket. Heavy-Duty Tire Evaluation. . See Docket #EPA-HQOAR-2010-0162.Pages 2-3 and Appendix B.
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final program. NHTSA will revisit this issue in the next rulemaking. In developing the 

final standards, the agencies have evaluated the current levels of emissions and fuel 

consumption, the kinds of technologies that could be utilized by manufacturers to reduce 

emissions and fuel consumption and the associated lead time, the associated costs for the 

industry, fuel savings for the consumer, and the magnitude of the CO2 and fuel savings 

that may be achieved. After examining the possibility of vehicle improvements based on 

use of the technologies underlying the standards for Class 7 and 8 tractors, including 

improved aerodynamics, vehicle speed limiters, idle reduction technologies, tire rolling 

resistance, and weight reduction, as well as use of hybrid technologies, the agencies 

ultimately determined to base the final vehicle standards on performance of tires with 

superior rolling resistance. For standards for diesel engines installed in vocational 

vehicles, the agencies examined performance of engine friction reduction, aftertreatment 

optimization, air handling improvements, combustion optimization, turbocompounding, 

and waste heat recovery, ultimately deciding to base the final standards on the 

performance of all of the technologies except turbocompounding and waste heat recovery

systems. The standards for gasoline engine installed in vocational vehicles are based on 

performance of technologies such as gasoline direct injection, friction reduction, and 

variable valve timing. The agencies’ evaluation indicates that these technologies, as 

described in Section III.C, are available today in the heavy-duty tractor and light-duty

vehicle markets, but have very low application rates in the vocational vehicle market. 

The agencies have analyzed the technical feasibility of achieving the CO2 and fuel 

consumption standards, based on projections of what actions manufacturers would be 

expected to take to reduce emissions and fuel consumption to achieve the standards, and 

believe that the standards are cost-effective and technologically feasible and appropriate 

within the rulemaking time frame. EPA and NHTSA also present the estimated costs and 

benefits of the vocational vehicle standards in Section III. 

(a) Vocational Vehicle Chassis Standards

In the NPRM, the agencies defined tire rolling resistance as a frictional loss of 

energy, associated mainly with the energy dissipated in the deformation of tires under 

load that influences fuel efficiency and CO2 emissions. Tires with higher rolling 

resistance lose more energy in response to this deformation, thus using more fuel and 

producing more CO2 emissions in operation, while tires with lower rolling resistance lose 

less energy, and save more fuel and CO2 emissions in operation. Tire design 

characteristics (e.g., materials, construction, and tread design) influence durability, 

traction (both wet and dry grip), vehicle handling, ride comfort, and noise in addition to 

rolling resistance.

The agencies explained that a typical Low Rolling Resistance (LRR) tire’s 

attributes, compared to a non-LRR tire, would include increased tire inflation pressure; 

material changes; and tire construction with less hysteresis, geometry changes (e.g., 

reduced height to width aspect ratios), and reduction in sidewall and tread deflection.

When a manufacturer applies LRR tires to a vehicle, the manufacturer generally also 

makes changes to the vehicle’s suspension tuning and/or suspension design in order to 

maintain vehicle handling and ride comfort.
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The agencies also explained that while LRR tires can be applied to vehicles in all 

MD/HD classes, they may have special potential for improving fuel efficiency and 

reducing CO2 emissions for vocational vehicles. According to an energy audit conducted 

by Argonne National Lab, tires are the second largest contributor to energy losses of 

vocational vehicles, after engines.123 Given this finding, the agencies considered the 

availability of LRR tires for vocational applications by examining the population of tires 

available, and concluded that there appeared to be few LRR tires for vocational 

applications. The agencies suggested in the NPRM that this low number of LRR tires for 

vocational vehicles could be due in part to the fact that the competitive pressure to 

improve rolling resistance of vocational vehicle tires has been less than in the line haul 

tire market, given that line haul vehicles generally drive significantly more miles and 

therefore have significantly higher operating costs for fuel than vocational vehicles, and

much greater incentive to improve fuel consumption. The small number of LRR tires for 

vocational vehicles may perhaps also be due in part to the fact that vocational vehicles 

generally operate more frequently on secondary roads, gravel roads and roads that have 

less frequent winter maintenance, which leads vocational vehicle buyers to value tire 

traction and durability more than rolling resistance. The agencies recognized that this 

provided an opportunity to improve fuel consumption and GHG emissions by creating a 

regulatory program that encourages improvements in tire rolling resistance for both line 

haul and vocational vehicles. The agencies proposed to base standards for all segments of 

HD vehicles on the use of LRR tires. The agencies estimated that a 10 percent reduction 

in average tire rolling resistance would be attainable between model years 2010 and 2014 

based on the tire development achievements over the last several years in the line haul 

truck market. This reduction in tire rolling resistance would correlate to a two percent 

reduction in fuel consumption as modeled by the GEM.124

(i) Summary of Comments

The agencies received many comments on the subject of tire rolling resistance as 

applied to vocational vehicles. Comments included suggestions for alternative test 

procedures; whether LRR tires should be applied to certain types of vocational vehicles

and whether certain vehicles should be exempted from the vocational vehicle standards if 

the standards are based on the ability to use LRR tires; the appropriateness of the 

proposed standards; and compliance issues (discussed below in Section II.D.2.b. 

Regarding whether LRR tires should be applied to certain types of vocational 

vehicles, the agencies received many comments from stakeholders, such as Daimler 

Trucks North America, Fire Apparatus Manufacturers Association (FAMA), International 

Association of Fire Chiefs, National Ready Mix, National Solid Wastes Management 

Association (NSWMA), Spartan Motors, National Automobile Dealers Association, 

among others. There were comments regarding applicability of low rolling resistance 

tires to vocational vehicles based on LRR tire availability, suitability of the tires for the 

 

123 A Class 6 pick up and delivery truck at 50% load has tires as the second largest contributor at speeds up 

to 35 mph, a typical average speed of urban delivery vehicles. See Argonne National Laboratory. 

“Evaluation of Fuel Consumption Potential of Medium and Heavy Duty Vehicles through Modeling and 

Simulation.” October 2009. Page 91.

124 See 75 FR at 74241.
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applications, fuel consumption and GHG emissions benefits and the appropriateness of 

standards. Many of these commenters focused particularly on the whether LRR tires 

would compromise the capability of emergency vehicles. 

Regarding whether LRR tires are available in the market for certain vocational 

vehicles and whether the vocational vehicle standards were therefore appropriate and 

feasible, both Ford and AAPC stated that the proposed model-based requirement for 

Class 2b-8 vocational chassis appeared to require tires with rolling resistance values of 

approximately 8.0-8.1 kg/metric ton or better, and that limited data available for smaller 

diameter tires, such as light-truck (LT) tires used on many light heavy-duty trucks and 

vans, suggested that there exist few if any choices for tires that would comply. Given this 

concern about the availability of compliant tires, particularly in the case of tires smaller 

than 22.5”, during the proposed regulatory time frame, AAPC and Ford requested 

revisions to the requirement, or the modeling method, to establish different standards for 

vehicles that use different tire classes, with separate requirements for LT tires, 19.5” tires, 

and 22.5” tires. AAPC argued that standards should be set based on data collected on 

high volume in-use tires, and that they should be set at a level that ensures the availability

of multiple compliant tires. CRR

(ii) Summary of Research Done Since the Notice of Proposed Rulemaking

Since the NPRM, the agencies have conducted additional research on tire rolling 

resistance for medium- and heavy-duty applications. This research involved direct

discussions with tire suppliers,125 assessment of the comments received, additional review 

of tire products available, and a more thorough review of tire use in the field. In addition, 

EPA has conducted tire rolling resistance testing to help inform the final rulemaking.126

The agencies discussed many aspects of low rolling resistance tire technologies 

and their application to vocational vehicles with tire suppliers since publication of the 

NPRM. Several tire suppliers indicated to the agencies that low rolling resistance tires 

are currently available for vocational applications that would enable compliance with the 

proposed vocational vehicle standards, such as delivery vehicles, refuse vehicles, and 

other vocations. However, these conversations also made the agencies aware that 

availability of low rolling resistance tires varies by supplier. Some suppliers stated they

focused their company resources on areas of the medium- and heavy-duty vehicle 

spectrum where fleet operators would see the most fuel efficiency benefits for the 

application of low rolling resistance technologies; specifically the long-haul, on-highway

applications that drive many miles and use large amounts of fuel. These suppliers stated 

that this choice was driven by the significant capital investment that would be needed to 

improve tire rolling resistance across the relatively large number of product offerings in 

the vocational vehicle segment, based on the wide range of tire sizes, load ratings, and 

speed ratings, compared to the much narrower range of offerings for long-haul 

 

125 Records of these communications, and additional information submitted by the supplier companies and 

not CBI, are available at Docket No. EPA-HQ-OAR-2010-0162.

126 Bachman, Joseph. Memorandum to the Docket. Heavy-Duty Tire Evaluation. July 2011. Docket 

EPA-HQ-OAR-2010-0162, Pages 3-6.
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applications.127 Other suppliers stated that they have made conscious efforts to reduce 

the rolling resistance of all of their medium- and heavy-duty vehicle tire offerings, 

including vocational applications, in an effort to become leaders in this technology.

The agencies also discussed with tire suppliers the potential tire attribute tradeoffs 

that may be associated with incorporating designs that improve tire rolling resistance, 

given the driving patterns, environmental conditions, and on-road and off-road surface 

conditions that vocational vehicles are subjected to. Some vehicle manufacturer 

commenters had suggested that changes in tire tread block design that improve rolling 

resistance may adversely affect tire performance characteristics such as traction, 

resistance to tearing, and resistance to wear and damage from scrubbing on curbs and 

frequent tight radius turns that are important to customers for vocational vehicle 

performance. The suppliers agreed that providing tires unable to withstand these 

conditions or meet the vehicle application needs would adversely affect customer 

satisfaction and warranty expenses, and would have detrimental financial effects to their 

businesses. One supplier indicated that theoretically, tread-wear (tire life) could be 

compromised if suppliers choose to reduce the initial tire tread depth without any

offsetting tire compound or design enhancements as the means to achieve rolling 

resistance reductions. That supplier argued that taking this approach could lead to more 

frequent tire replacements or re-treading of existing tire carcasses, and that the agencies

should therefore take a total lifecycle view when evaluating the effects of driving rolling 

resistance reductions. That supplier also indicated that a correlation of a 20 percent

reduction in rolling resistance achieved through tread depth reduction could lead to a 30

percent decrease in tread-life and 15 percent reduction in wet traction. The agencies note 

that when they inquired about potential ‘safety’ related tradeoffs, such as traction 

(braking and handling) and tread wear when applying low rolling resistance technologies,

tire suppliers which remain subject to safety standards regardless of this program,

consistently responded that they would not produce a tire that compromises safety when 

fitted in its proper application.

In addition to the supplier discussions and evaluation of comments to the Notice 

of Proposed Rulemaking, EPA conducted a series of tire rolling resistance tests on 

medium- and heavy-duty vocational vehicle tires. The testing measured the CRR of tires 

representing 16 different vehicle applications for Class 4 – 8 vocational vehicles. The 

testing included approximately 5 samples each of both steer and drive tires for each 

application. The tests were conducted by two independent tire test labs, Standards Testing 

Lab (STL) and Smithers-Rapra (Smithers). 

Overall, a total of 156 medium- and heavy-duty tires128 were included in this 

testing, which was comprised of 88 tires covering various commercial vocational vehicle 

 

127 More tire types and sizes have been developed for vocational vehicle applications than for long-haul 

applications. In some cases, suppliers offer up to 17 different vocational tire designs, and for each design 

there may be 8-10 different tire sizes. In contrast, a line-haul application may have only 2-3 tire designs 

with a fewer range of sizes.

128 After the agencies completed their analysis of these data, the agencies received raw data on 43 

additional tires. See Powell, Greg. Memorandum to the Docket. Additional Tire Testing Results. July 

2011. Docket NHTSA-2010-0079. The agencies have not analyzed these additional data, nor included 
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types, such as bucket trucks, school buses, city delivery vehicles, city transit buses and 

refuse haulers among others; 47 tires intended for application to tractors; and 21 tires 

classified as light-truck (LT) tires intended for Class 4 vocational vehicles such as 

delivery vans. In addition, approximately 20 of the tires tested were exchanged between 

the labs to assess inter-laboratory variability. 

The test results for 88 commercial vocational vehicle tires (19.5” and 22.5” sizes) 

showed a test average CRR of 7.4 kg/metric ton, with results ranging from 5.1 to 9.8. To 

comply with the proposed vocational vehicle fuel consumption and GHG emissions 

standards using improved tire rolling resistance as the compliance strategy, a 

manufacturer would need to achieve an average tire CRR value of 8.1 kg/metric ton.

129

 

The measured average CRR of 7.4kg/metric ton is thus better than the average value that 

would be needed to meet vocational vehicle standards. Of those 173 tires tested, twenty 

tires had CRR values exceeding 8.1 kg/metric ton, two were at 8.1 kg/metric ton, and 

sixty-six tires were better than 8.1 kg/metric ton. Additional data analyses examining the 

tire data by tire size to determine the range and distribution of CRR values within each 

tire size showed each tire size generally had tires ranging from approximately 6.0 to 8.5 

kg/metric ton, with a small number of tires in the 5.3 – 5.7 kg/metric ton range and a 

small number of tires in a range as high as 9.3 – 9.8 kg/ton. Review of the data showed 

that for each tire size and vehicle type, the majority of tires tested would enable 

compliance with vocational vehicle fuel consumption and GHG emission standards. 

The test results for the 47 tires intended for tractor application showed an overall 

average of 6.9 kg/ton, the lowest overall average rolling resistance of the different tire 

applications tested.

130 This is consistent with what the agencies heard through comments

and meetings with tire suppliers whose efforts have focused on tractor applications,

particularly for long-haul applications, which yield the highest fuel efficiency benefits 

from LRR tire technology. 

Finally, the 21 LT tires intended for Class 4 vocational vehicles were comprised 

of two sizes; LT225/75R16 and LT245/75R16 with 11 and 10 samples tested, 

respectively. Some auto manufacturers have indicated that CRR values for tires fitted to 

these Class 4 vehicles typically have a higher CRR values than tires found on commercial 

vocational vehicles because of the smaller diameter wheel size and the ISO testing 

protocol.131 The test data showed the average CRR for LT225/75R16 tires was 9.1 

kg/metric ton and the average for LT245/75R16 tires was 8.6 kg/metric ton. The range 

for the LT225/75R16 tires spanned 7.4 to 11.0132 and the range for the LT245/75R16 tires 

 

them in the final report, and the data therefore played no role in the agencies' determination of an 

appropriate standard for vocational vehicles. The agencies will analyze and consider these data, along with 

any future data received through continued testing, as appropriate, in the next rulemaking for the heavy 

duty sector.

129 See 75 FR at 74244.

130 The CRR values for these applications ranged from 5.4 to 9.2 kg/metric ton.

131 See comments to docket EPA-HQ-OAR-2010-0162-1761; Ford Motor Company

132 The agency notes the highest CRR values recorded for LT tires, of 11.0 and 10.9, were for two tires of 

the same size and brand. The nearest recorded values to these two tires were 9.8; substantially beyond the 

differences between other tires tested.
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ranged from 6.6 to 9.8 kg/metric ton. Overall, the average for the tested LT tires was 8.9

kg/metric ton.

Analysis of the EPA test data for all vocational vehicles, including LT tires, 

shows the test average CRR is 7.7 kg/metric ton with a standard deviation of 1.2

kg/metric ton. Review of the data thus shows that for each tire size and vehicle type, 

there are many tires available that would enable compliance with the proposed standards 

for vocational vehicles and tractors except for LT tires for Class 4 vocational vehicles 

where test results show the majority of these tires have CRR worse than 8.1 kg/metric

ton. 

The agencies also reviewed the CRR data from the tires that were tested at both 

the STL and Smithers laboratories to assess inter-laboratory and test machine variability. 

The agencies conducted statistical analysis of the data to gain better understanding of labto-lab correlation and developed an adjustment factor for data measured at each of the 

test labs. When applied, this correction factor showed that for 77 of the 80 tires tested, 

the difference between the original CRR and a value corrected CRR was 0.01 kg/metric 

ton. The values for the remaining three tires were 0.03 kg/metric ton, 0.05 kg/metric ton 

and 0.07 kg/metric ton. Based on these results, the agencies believe the lab-to-lab 

variation for the STL and Smithers laboratories would have very small effect on 

measured CRR values. Further, in analyzing the data, the agencies considered both 

measurement variability and the value of the measurements relative to proposed 

standards. The agencies concluded that although laboratory-to-laboratory and test 

machine-to-test machine measurement variability exists, the level observed is not 

excessive relative to the distribution of absolute measured CRR performance values and 

relative to the proposed standards. Based on this, the agencies concluded that the test 

protocol is reasonable for this program, but are making some revisions to the vehicle 

standards.

The agencies also conducted a winter traction test of 28 tires to evaluate the impact 

of low rolling resistance designs on winter traction. The results of the study indicate that 

there was no statistical relationship between rolling resistance and snow traction.133

(iii) Summary of Final Rules

For vocational vehicles, the agencies intend to keep rolling resistance as an input 

to the GEM but with modifications to the proposed targets as a result of the testing 

completed by EPA since the NPRM and information from tire suppliers. The agencies 

continue to believe that LRR tires, which are an available, cost-effective, and appropriate 

technology with demonstrated fuel efficiency and GHG reduction benefits, are reasonable 

for all on-highway vehicles. 

The agencies acknowledge there can be tradeoffs when designing a tire for 

reduced rolling resistance. These tradeoffs can include characteristics such as wear 

resistance, cost and scuff resistance. However, the agencies have continued to review 

 

133 Bachman, Joseph. Memorandum to Docket. Heavy-Duty Tire Evaluation. Docket EPA-HQ-OAR2010-0162. Pages 3-6.
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this issue and do not believe that LRR tires as specified in the rules present safety issues. 

As just noted, the agencies conducted independent testing of current tires available to 

assist confirming the finalized rolling resistance standards. The tire test samples were 

selected from those currently available on the market and therefore have no known safety 

issues and meet all current requirements to allow availability in commerce; including 

wear, scuff resistance, braking, traction under wet or icy conditions, and other 

requirements. These tires included a wide array of sizes and designs intended for most all 

vocational applications, including those used for school buses, refuse haulers, emergency

vehicles, concrete mixers, and recreational vehicles. As the test results revealed, there 

are a significant number of tires available that meet or do better than the rolling resistance 

targets for vocational vehicles; both light-truck (with an adjustment factor described later 

in this preamble section) and non-LT tire types, while meeting all applicable safety 

standards.

The agencies also recognize the extreme conditions fire apparatus equipment must 

navigate to enable firefighters to perform their duties. As described below, the final rules 

contain provisions to allow for exemption of specific off-road capable vocational vehicles 

from the fuel efficiency and greenhouse gas standards. Included in the exemption criteria 

are provisions for vehicles equipped with specific tire types that would be fit to a vehicle 

to meet extreme demands, including those vehicles designed for off-road capability. 

As follow-up to the final rules and in support for development of a separate 

FMVSS rule, NHTSA plans to conduct additional performance-focused testing (beyond 

rolling resistance) for medium- and heavy-duty trucks. This testing is targeted for 

completion toward the end of this year. The agencies will review these performance data 

when available, in concert with any subsequent proposed rulemakings regarding fuel 

consumption and GHG emissions standards for medium- and heavy-duty vehicles.

For vocational vehicles, the rolling resistance of each tire will be measured using 

the ISO 28850 test method for drive tires and steer tires planned for fitment to the vehicle 

being certified. Once the test CRR values are obtained, a manufacturer will input the 

CRR values for the drive and steer tires separately into the GEM where, for vocational 

vehicles, the vehicle load is distributed equally over the steer and drive tires. Once 

entered, the amount of GHG reduction attributed to tire rolling resistance will be 

incorporated into the overall vehicle compliance value. The following table provides the 

revised target CRR values for vocational vehicles for 2014 and 2017 model years that are 

used to determine the vehicle standards.

Table II-14: Vocational Vehicle – Target CRR Values for GEM Input

2014 MY 2017 MY

Tire Rolling Resistance 

(kg/metric ton)

7.7 kg/metric ton 7.7 kg/metric ton

These target values are being revised based on the significant availability of tires 

for vocational vehicles applications which have performance better than the originally

proposed 8.1 kg/metric ton target. As just discussed, 63 of the 88 tires tested for 
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vocational applications had CRR values better than the proposed target. The tires tested 

covered fitment to a wide range of vocational vehicle types and classes; thus agencies 

believe the original target value of 8.1 kg/metric ton was possibly too lenient after 

reviewing the testing data. Therefore, the agencies believe it is appropriate to reduce the 

proposed vehicle standard based on performance of a CRR target value of 7.7 kg/metric 

ton for non-LT tire type. As discussed previously, this value is the test average of all 

vocational tires tested (including LT) which takes a conservative approach over setting a 

target based on the average of only the non-LT vocational tires tested. For LT tires, based 

on both the test data and the comments from AAPC and Ford Motor Company, the 

agencies recognize the need to provide an adjustment. In lieu of having two sets of Light 

Heavy-Duty vocational vehicle standards, the agencies are finalizing an adjustment factor 

which applies to the CRR test results for LT tires. The agencies developed an adjustment 

factor dividing the overall vocational test average CRR of 7.7 by the LT vocational 

average of 8.9. This yields an adjustment factor of 0.87. For LT vocational vehicle tires, 

the measured CRR values will be multiplied by the 0.87 adjustment factor before entering 

the values in the GEM for compliance. 

Based on the tire rolling resistance inputs noted above EPA is finalizing the 

following CO2 standards for the 2014 model year for the Class 2b through Class 8 

vocational vehicle chassis, as shown in Table II-15. Similarly, NHTSA is finalizing the 

following fuel consumption standards for the 2016 model year, with voluntary standards 

beginning in the 2014 model year. For the EPA GHG program, the standard applies 

throughout the useful life of the vehicle. The agencies note that both the baseline 

performance and standards derived for the final rules slightly differ from the values 

derived for the NPRM. The first difference is due to the change in the target rolling 

resistance from 8.1 to 7.7 kg/metric ton based on the agencies’ test results. Second, there 

are minor differences in the fuel consumption and CO2 emissions due to the small 

modifications made to the GEM, as noted in RIA Chapter 4. Lastly, the final HHD 

vocational vehicle standard uses a revised payload assumption of 15,000 pounds instead 

of the 38,000 pounds used in the NPRM, as described in Section II.D.3.c.iii. As a result, 

the emission standards shown in Table II-15 for vocational vehicles have changed from 

the standards published in the NPRM. The changes for light heavy and medium heavyduty vehicles are modest. The change for heavy heavy-duty vocational vehicles is larger, 

due to the difference in assumed payload. 

As with the 2017 MY standards for Class 7 and 8 tractors, EPA and NHTSA are 

adopting more stringent vocational vehicle standards for the 2017 model year which 

reflect the CO2 emissions reductions required through the 2017 model year engine 

standards. See also Section II.B.2 explaining the same approach for the standards for 

combination tractors. As explained in Section II. D. (2) (c)(iv) below, engine 

performance is one of the inputs into the GEM compliance model that has a pre-defined 

(i.e. fixed) value established by the agencies, and that input will change in the 2017 MY 

to reflect the 2017 MY engine standards. The 2017 MY vocational vehicle standards are 

not premised on manufacturers installing additional vehicle technologies, and a 

vocational vehicle that complies with the standards in MY 2016 will also comply in MY 

2017 with no vehicle (tire) changes. Thus, although chassis manufacturers will not be 

required to make further improvements in the 2017 MY to meet the standards, the 
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standards will be more stringent to reflect the engine improvements required in that year. 

This is because in 2017 MY GEM vehicle modeling outputs (in grams per ton mile and 

gallons per 1,000 ton mile) will automatically decrease since engine efficiency will 

improve in that year. 

Table II-15: Final Class 2b-8 Vocational Vehicle CO2 and Fuel Consumption Standards 

EPA CO2 (gram/ton-mile) Standard Effective 2014 Model Year

Light Heavy-Duty

Class 2b-5

Medium HeavyDuty Class 6-7Heavy Heavy-Duty 

Class 8

CO2 Emissions 388 234 226

NHTSA Fuel Consumption (gallon per 1,000 ton-mile) Standard Effective 2016 Model 

Year134

Light Heavy-Duty

Class 2b-5

Medium HeavyDuty Class 6-7Heavy Heavy-Duty 

Class 8

Fuel Consumption 38.1 23.0 22.2

EPA CO2 (gram/ton-mile) Standard Effective 2017 Model Year

Light Heavy-Duty

Class 2b-5

Medium HeavyDuty Class 6-7Heavy Heavy-Duty 

Class 8

CO2 Emissions 373 225 222

NHTSA Fuel Consumption (gallon per ton-mile) Standard Effective 2017 Model Year

Light Heavy-Duty

Class 2b-5

Medium HeavyDuty Class 6-7Heavy Heavy-Duty 

Class 8

Fuel Consumption 36.7 22.1 21.8

(iv) Off-Road and Low-Speed Vocational Vehicle Standards

Some vocational vehicles, because they are primarily designed for off-road use, 

may not be good candidates for low rolling resistance tires. These vehicles may travel 

on-road for very limited periods of time, such as in traveling on an urban road, or if they

are off-loaded from another vehicle onto a road and then are driven off-road. The 

infrequent and limited exposure to on-road environments makes these vehicles suitable 

candidates for providing an exemption from the CO2 emissions and fuel consumption 

standards for vocational vehicles (although the standards for HD engines used in 

vocational vehicles would still apply).135 The agencies are also targeting other vehicles 

that travel at low-speeds and that are meant to be used both on- and off-road. The 

application of certain technologies to these vehicles may not provide the same level of 

benefits as it would for pure on-road vehicles, and moreover, could even reduce the 

functionality of the vehicle. In this case, the agencies want to ensure that vehicle 

functionality is maintained to the maximum extent possible, while avoiding the 

possibility that achievable benefits are not realized because of the structure of the 

 

134 Manufacturers may voluntarily opt-in to the NHTSA fuel consumption program in 2014 or 2015. Once 

a manufacturer opts into the NHTSA program it must stay in the program for all the optional MYs.

135 See 75 FR at 74199.
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regulations. The sections below explain this issue in more detail as it applies to tractors 

and vocational vehicles.

The agencies explained in the NPRM that certain vocational vehicles have very

limited on-road usage, and that although they would be defined as “motor vehicles” per 

40 CFR 85.1703, the fact that they spend the most of their operations off-road might be 

reason for excluding them from the vocational vehicle standards. Vocational vehicles, 

such as those used on oil fields and construction sites136, experience very little benefit 

from LRR tires or from any other technologies to reduce GHG emissions and fuel 

consumption. The agencies proposed to allow a narrow range of these de facto off-road 

vehicles to be excluded from the proposed vocational vehicle standards if equipped with 

special off-road tires having lug type treads. The agencies stated in the NPRM that on/off 

road traction is the only tire performance parameter which trades off with TRR so 

significantly that tire manufacturers could be unable to develop tires meeting both a TRR 

standard while maintaining or improving the characteristic allowing them to perform offroad. See generally 75 FR at 74199-200. Therefore, the agencies proposed to exempt 

these vehicles from the standards while requiring them to use certified engines, which 

would provide fuel consumption and CO2 emission reductions in all vocational 

applications. To ensure that these vehicles were in fact used chiefly off-road, the 

agencies proposed requirements that would allow exemption of a vehicle provided the 

vehicle and the tires were speed limited. As mentioned, the agencies were aware that the 

majority of off road trucks primarily use off-road tires and are low speed vehicles as well. 

Based upon this understanding, the agencies specifically proposed that a vehicle must 

meet the following requirements to qualify for an exemption from vocational vehicle 

standards:

 Tires which are lug tires or contain a speed rating of less than or equal to 

60 mph; and

 A vehicle speed limiter governed to 55 mph.

In response to the NPRM, EMA/TMA, Navistar and Volvo agreed with the 

proposal to exclude off-road vocational vehicles from the standards because these 

vehicles primarily operate off-road, but requested broadening the exclusion to cover other 

types of vocational vehicles. Several manufacturers (IAFC, FAMA, NTEA, NSWMA, 

AAPC, RMA, Navistar and DTNA) requested the exemption of specific vehicle types, 

such as on/off-road emergency vehicles, refuse vehicles, low speed transit buses or 

school buses, because their usage was viewed as being incompatible with LRR tires. 

Navistar opposed the application of the proposed regulations to school buses, arguing that 

LRR tires may impact the ride quality for children in school buses. However, Navistar 

also acknowledged that a significant portion of the national fleet of school buses already

utilizes off-road tires designed with lug type tread patterns (e.g., Kentucky). IAFC, 

FAMA and NTEA commented that fire trucks and ambulances should also be exempted 

due to their part-time off-road use such as in responding to a wildland fire or hazardous 

materials incidents which would require operations on dirt and gravel roads, fields or 

 

136

 Vehicles such as concrete mixers, off-road dump trucks, backhoes and wheel loaders.
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other off-road environments. Commenters also contended that by requiring a 55-mph 

limitation, the proposed exemption would be impractical for emergency vehicles due to 

the need to respond quickly to life-threatening events. The refuse truck manufacturers 

and trade associations, NSWMA and AAPC, commented that the solid waste industry

operates a variety of vocational vehicles that perform solely off-road at landfills. These 

comments also requested an exemption for certain refuse trucks (i.e., roll-off container 

trucks) that frequently go off-road at construction sites. Other commenters (FAMA, 

IAFC and Oshkosh) opposed compliance with the LRR standard for vocational vehicles 

for on/off road mixed service tires with aggressive or lug treads, stating that up to this 

point the industry has had very little interest in improving the LRR aspects of these tires 

or even to conducting testing to determine values for the coefficient of rolling resistance. 

For the final rules, the agencies have considered the issues raised by commenters 

and have decided to adopt different criteria than proposed for exempting vocational 

vehicles and vocational tractors that primarily travel off-road. The agencies believe that 

the reasons for proposing the exemption are equally applicable to a wider class of 

vocational vehicles operating mostly off-road so that the proposals were either unsuitable 

for the industry or too restrictive to capture all the vehicles intended for the exemption. 

For example, the NPRM proposal, by using tire tread patterns and VSLs as the basis for 

qualifying vehicles for the exemption, was too restrictive because other non-lug type 

tread patterns exist in the market as well as other technologies which are equally capable 

of limiting the speed of the vehicle, as mentioned by Volvo. Therefore, the proposed 

exemption for off-road vocational vehicles will be replaced with new criteria based on 

the vehicle application, whether it operates at low speed and whether the vehicle has 

speed restricted tires. The exemption is in part based on existing industry standards 

established by NHTSA.137 As such, any vocational vehicle including vocational tractors 

primarily used off-road or at low speeds must meet the following criteria to be exempt 

from GHG and fuel consumption vehicle standards: 

 Any vehicle primarily designed to perform work off-road such as in oil 

fields, forests, or construction sites and having permanently or temporarily 

affixed components designed to work in an off-road environment (i.e., 

hazardous material equipment or off-road drill equipment) or vehicles 

operating at low speeds making them unsuitable for normal highway

operation; and meeting one or more of the following criteria:

 Any vehicle equipped with an axle that has a gross axle weight 

rating (GAWR) of 29,000 pounds; or

 

137 The heavy-duty off road exemption is based in part on requirements existing in NHTSA’s Federal Motor 

Vehicle Safety Standards (FMVSS) Nos. 119 and 121. In FMVSS No. 119, titled “New pneumatic tires for 

motor vehicles with a GVWR of more than 4,538 kilograms (10,000 pounds) and motorcycles,” speed 

restricted tires rated at a speed of 55 mph or less are subjected to lower test drum speeds in the endurance 

test to account for their low design speeds (e.g., off-road tires). The off-road vehicle exemptions adopted 

for this heavy-duty program were based on the requirements used in FMVSS No. 121, “Air brake systems,” 

to identify and exclude vocational vehicles based upon their inability to meet on-highway stopping distance 

requirements.
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 Any truck or bus that has a speed attainable in 2 miles of not more 

than 33 mph; or

 Any truck that has a speed attainable in 2 miles of not more than 

45 mph, an unloaded vehicle weight that is not less than 95 percent 

of its gross vehicle weight rating (GVWR), and no capacity to 

carry occupants other than the driver and operating crew.

The agencies are also adopting in the final rules provisions to exempt any

vocational vehicle that can operate in both on and off-road environments and has speed 

restricted tires rated at 55 mph or below.138 The agencies’ reasoning in adopting a speed 

restricted exemption for tires is that the majority of mixed service tires used for off-road 

use was identified as being restricted at 55 mph or less.139 Also, as identified by FMVSS 

No. 119, speed restricted tires at a rating of 55 mph or less are incapable of meeting the 

same on-road performance standards as conventional tires. The agencies acknowledge 

that using a speed restriction criteria could allow certain vehicles to be exempted 

inappropriately (i.e., low speed city delivery tractors) but the agencies believe this is 

preferable to creating a situation where a segment of vehicles are precluded from 

performing their intended applications. Therefore, the final rules include an exemption 

for any mixed service (on and off-road) vocational vehicle equipped with off-road tires 

that are speed restricted at 55 mph or less. 

Manufacturers choosing to exempt vehicles based on the above criteria will be 

required to provide a description of how they meet the qualifications for each vehicle 

family group in their end-of-the year and final year reports (see Section V). 

A manufacturer having an off-road vehicle failing to meet the criteria under the 

agencies’ off-road exemptions will be allowed to submit a petition describing how and 

why their vehicles should qualify for exclusion. The process of petitioning for an 

exemption is explained in §§ 1037.631 and 535.8. For each request, the manufacturer 

will be required to describe why it believes an exemption is warranted and address the 

following factors which the agencies will consider in granting its petition: 

 The agencies provide an exemption based on off- road capability of the 

vehicle or if the vehicle is fitted with speed restricted tires. Which 

exemption does your vehicle qualify under; and

 Are there any comparable tires that exist in the market to carry out the 

desired application both on and off road for the subject vehicle(s) of the 

petition which have LLR values that would enable compliance with the 

standard?

 

138 See 40 CFR 1037.631

139 Particular tire use was identified during the FMVSS 119 rulemaking and confirmed through subsequent 

market research. See “2010 Year Book the Tire and RIM Association Inc.”
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(b) Heavy-duty Engine Standards for Engines Installed in Vocational Vehicles

EPA is finalizing GHG standards140 and NHTSA is finalizing fuel consumption 

standards for new heavy-duty engines installed in vocational vehicles. The standards will 

vary depending on whether the engines are diesel or gasoline powered since emissions 

and fuel consumption profiles differ significantly depending on whether the engine is 

gasoline or diesel powered. The agencies’ analyses, as discussed briefly below and in 

more detail later in this preamble and in the RIA Chapter 2, show that these standards are 

appropriate and feasible under each agency’s respective statutory authorities. 

The agencies have analyzed the feasibility of achieving the GHG and fuel 

consumption standards, based on projections of what actions manufacturers are expected 

to take to reduce emissions and fuel consumption. EPA and NHTSA also present the 

estimated costs and benefits of the heavy-duty engine standards in Section III below. In 

developing the final rules, the agencies have evaluated the kinds of technologies that 

could be utilized by engine manufacturers compared to a baseline engine, as well as the 

associated costs for the industry and fuel savings for the consumer and the magnitude of 

the GHG and fuel consumption savings that may be achieved.

EPA’s existing criteria pollutant emissions regulations for heavy-duty highway

engines establish four service classes (three for compression-ignition or diesel engines 

and one for spark ignition or gasoline engines) that represent the engine’s intended and 

primary vehicle application, as shown in Table II-16 (40 CFR 1036.140 and NHTSA’s 49 

CFR 535.4). The agencies proposed to use the existing service classes to define the 

engine subcategories in this HD GHG emissions and fuel consumption program. The 

agencies did not receive any adverse comments to using this approach. Thus, the 

agencies are adopting the four engine subcategories for this final action. 

Table II-16: Engine Regulatory Subcategories

Engine Category Intended Application

Light Heavy-duty (LHD) 

Diesel 

Class 2b through Class 5 trucks (8,501 through 19,500 

pounds GVWR)

Medium Heavy-duty 

(MHD) Diesel 

Class 6 and Class 7 trucks (19,501 through 33,000 pounds 

GVWR)

Heavy Heavy-duty (HHD) 

Diesel 

Class 8 trucks (33,001 pounds and greater GVWR

Gasoline Incomplete vehicles less than 14,000 pounds GVWR and all 

vehicles (complete or incomplete) greater than 14,000 

pounds GVWR

 

140 Specifically, EPA is finalizing CO2, N2O, and CH4 emissions standards for new heavy-duty engines over 

an EPA specified useful life period (See Section II. E. for the N2O and CH4 standards).
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(i) Diesel Engine Standards for Engines Installed in Vocational Vehicles

In the NPRM, the agencies proposed the following CO2 and fuel consumption 

standards for HD diesel engines to be installed in vocational vehicles, as shown in Table 

II-17.

Table II-17: Vocational Diesel Engine Standards over the Heavy-Duty FTP Cycle

Model 

Year

Standard Light 

Heavy-Duty

Diesel

Medium 

Heavy-Duty

Diesel

Heavy 

Heavy-Duty

Diesel

2014-2016 CO2 Standard (g/bhp-hr) 600 600 567

Voluntary Fuel Consumption 

Standard (gallon/100 bhp-hr)

5.89 5.89 5.57

2017 and 

Later

CO2 Standard (g/bhp-hr) 576 576 555

Fuel Consumption (gallon/100 

bhp-hr)

5.66 5.66 5.45

The agencies explained in the NPRM that the standards were based on our

assessment of the findings of the 2010 NAS report and other literature sources that there 

are technologies available to reduce fuel consumption in all these engines by this level in 

the final time frame in a cost-effective manner. Similar to the technology basis for HD 

engines used in combination tractors, these technologies include improved turbochargers, 

aftertreatment optimization, low temperature exhaust gas recirculation, and engine 

friction reductions. 

The agencies proposed that the HD diesel engine CO2 standards for vocational 

vehicles would become effective in MY 2014 for EPA, with more stringent CO2

standards becoming effective in MY 2017, while NHTSA’s fuel consumption standards 

would become effective in MY 2017, which would be both consistent with the EISA 

four-year minimum lead-time requirements and harmonized with EPA’s timing for 

stringency increases. The agencies explained that the three-year timing, besides being 

required by EISA, made sense because EPA’s heavy-duty highway engine program for 

criteria pollutants had begun to provide new emissions standards for the industry in three 

year increments, which had caused the heavy-duty engine and vehicle manufacturer 

product plans to fall largely into three year cycles reflecting this regulatory 

environment.141 To further harmonize with EPA, NHTSA proposed voluntary fuel 

consumption standards for HD diesel engines for vocational vehicles in MYs 2014-2016, 

allowing manufacturers to opt into the voluntary standards in any of those model years.142 

Manufacturers opting into the program must declare by statement their intent to comply 

prior to or at the same time they submit their first application for a certificate of 

conformity. A manufacturer opting into the program would begin tracking credits and 

debits beginning in the model year in which they opt in. Both agencies proposed to allow 

 

141 See generally 75 FR at 74200-201.

142 Once a manufacturer opts into the NHTSA program it must stay in the program for all the optional MYs 

and remain standardized with the implementation approach being used to meet the EPA emission program.
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manufacturers to generate and use credits to achieve compliance with the HD diesel 

engine standards for vocational vehicles, including averaging, banking, and trading 

(ABT), and deficit carry-forward.

The agencies proposed to require HD diesel engine manufacturers to achieve, on 

average, a three percent reduction in fuel consumption and CO2 emissions for the 2014 

standards over the baseline MY 2010 performance for the HHD diesel engines, and a five 

percent reduction for the LHD and MHD diesel engines. The standards for the LHD and 

MHD engine categories were proposed to be set at the same level because the agencies 

found that there is an overlap in the displacement of engines which are currently certified 

as LHDD or MHDD. The agencies developed the baseline 2010 model year CO2

emissions from data provided to EPA by manufacturers during the non-GHG certification 

process. Analysis of CO2 emissions from 2010 model year LHD and MHDD diesel 

engines showed little difference between LHD and MHD diesel engine baseline CO2

performance in the 2010 model year, which overall averaged 630 g CO2/bhp-hr (6.19 

gal/100 bhp-hr).

143

 Furthermore, the technologies available to reduce fuel consumption 

and CO2 emissions from these two categories of engines are similar. The agencies 

considered combining these engine categories into a single category, but decided to 

maintain these two separate engine categories with the same standard level to respect the 

different useful life periods associated with each category. 

For vocational engines certified on the FTP cycle, the agencies proposed to 

require a five percent reduction for HHD engines and nine percent for LHD and MHD 

engines. For LHD and MHD engines in 2017 MY, the nine percent reduction is based on 

the assumption that valvetrain friction reduction can be achieved in LHD and MHD 

engines in addition to turbo efficiency and accessory (water, oil, and fuel pump)

improvements, improved EGR cooler, and other approaches being used for HHD engines.

Commenters who discussed the HD diesel engine standards generally did not 

differentiate between the standards for engines used in combination tractors and the 

engines used in vocational vehicles. As explained above in Section II.B.2.b, some 

commenters, such as EMA/TMA, Cummins, DTNA, and other manufacturers, supported

the proposed standards, as long as the flexibilities proposed in the NPRM were finalized 

as proposed. Volvo argued that the standards are being phased in too quickly. 

Environmental groups and NGOs commented that the standards should be more stringent 

and reflect the potential for greater fuel consumption and CO2 emissions reductions 

through the use of additional technologies outlined in the 2010 NAS study. 

In response to those comments, the agencies refer back to our discussion in 

Section II.B.2.b. The agencies believe that the additional reductions may be achieved 

through the increased development of the technologies evaluated for the 2014 model year 

standard, but the agencies’ analysis indicates that this type of advanced engine 

development will require a longer development time than MY 2014. The agencies are 

therefore providing additional lead time to allow for the introduction of this additional 

 

143 Calculated using the conversion 10,180 g CO2/gallon for diesel fuel. 
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technology, and waiting until 2017 to increase stringency to levels reflecting application 

of turbocompounding. See Chapter 2 of the RIA for more details. 

While it made sense to set standards at the same level for LHD and MHD diesel 

engines for vocational vehicles, the agencies found that it did not make sense to set HHD 

standards at the same level. Based on manufacturer-submitted CO2 data for the nonGHG emissions certification process, the agencies found that the baseline for HHD diesel 

engines was much lower than for LHD/MHD diesel engines -- 584 g CO2/bhp-hr (5.74 

gal/100 bhp-hr) on average for HHD, compared to 630 g CO2/bhp-hr (6.19 gal/100 bhphr) on average for LHD/MHD.144

 In addition to the differences in the baseline 

performance, the agencies believe that there may be some technologies available to 

reduce fuel consumption and CO2 emissions that may be appropriate for the HHD diesel 

engines but not for the LHD/MHD diesel engines, such as turbocompounding. 

Therefore, the agencies are setting a different standard level for HHD diesel engines to be 

used in vocational vehicles. Additional discussion on technical feasibility is included in 

Section III below and in Chapter 2 of the RIA. 

After consideration of the comments, EPA and NHTSA are adopting as proposed 

the CO2 emission standards and fuel consumption standards for heavy-duty diesel 

engines installed in vocational vehicles are presented in Table II-17. Consistent with 

proposal, the first set of standards take effect with MY 2014 (mandatory standards for 

EPA, voluntary standards for NHTSA), and the second set take effect with MY 2017 

(mandatory for both agencies).

Compliance with the standards for engines installed in vocational vehicles will be 

evaluated based on the composite HD FTP cycle. In the NPRM, the agencies proposed 

standards based on the Heavy-duty FTP cycle for engines used in vocational vehicles 

reflecting their primary use in transient operating conditions (typified by both frequent 

accelerations and decelerations), as well as in some steady cruise conditions as 

represented on the Heavy-duty FTP. The primary reason the agencies proposed two 

separate certification cycles for HD diesel engines – one for HD diesel engines used in 

combination tractors and the other for HD diesel engines used in vocational vehicles -- is 

to encourage engine manufacturers to install technologies appropriate to the intended use 

of the engine with the vehicle.145 

DTNA, Cummins, EMA/TMA, and Honeywell commented that certain 

vocational vehicle applications would achieve greater fuel consumption and CO2

emissions reductions in-use by using an engine designed to meet the SET-based standard. 

They stated that some vocational vehicles operate at steady-state more frequently than in 

transient operation, such as motor coaches, and thus should be able to have an engine 

certified on a steady-state cycle to better reflect the vehicle’s real use.

In response, while the agencies recognize the value to manufacturers of having 

additional flexibility that allows them to meet the standards in a way most consistent with 

 

144 Calculated using the conversion 10,180 g CO2/gallon for diesel fuel.

145 See generally 75 FR at 74201.
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how their vehicles and engines will ultimately be used, we remain concerned about 

increasing flexibility in ways that might impair fuel consumption and CO2 emissions 

reductions. The agencies are therefore providing the option in these final rules for some 

vocational vehicles, but not others, to have SET certified engines. Heavy heavy-duty 

vocational engines will be allowed to be SET certified for vocational vehicles, since SET 

certified HHD engines must meet more stringent GHG and fuel consumption standards 

than FTP certified engines. We believe this will provide manufacturers additional 

flexibility while still achieving the expected fuel consumption and CO2 emissions 

reductions. However, medium heavy-duty vocational engines will not be allowed to be 

SET-certified, because medium heavy-duty engines certified on the FTP must meet a 

more stringent standard than engines certified on the SET, and the agencies are not 

confident that fuel consumption and CO2 emissions reduction levels would necessarily be 

maintained. 

As discussed above in Section II.B.2.b, the agencies place important weight in 

making our decisions about the cost-effectiveness of the standards and the availability of 

lead time on the fact that engine manufacturers are expected to redesign and upgrade their 

products during MYs 2014-2017. The final two-step CO2 emission and fuel consumption 

standards recognize the opportunity for technology improvements over the rulemaking

time frame, while reflecting the typical diesel truck manufacturers’ and diesel engine 

manufacturers’ product plan cycles. Over these four model years there will be an 

opportunity for manufacturers to evaluate almost every one of their engine models and 

add technology in a cost-effective way, consistent with existing redesign schedules, to 

control GHG emissions and reduce fuel consumption. The time-frame and levels for the 

standards, as well as the ability to average, bank and trade credits and carry a deficit 

forward for a limited time, are expected to provide manufacturers the time needed to 

incorporate technology that will achieve the final GHG and fuel consumption reductions, 

and to do this as part of the normal engine redesign process. This is an important aspect 

of the final rules, as it will avoid the much higher costs that would occur if manufacturers 

needed to add or change technology at times other than these scheduled redesigns.146

This time period will also provide manufacturers the opportunity to plan for compliance 

using a multi-year time frame, again in accord with their normal business practice. 

Further details on lead time, redesigns and technical feasibility can be found in Section 

III.

The agencies recognize, however, that the schedule of changes for the final 

standards may not be the most cost-effective one for all manufacturers. For HD diesel 

engines for use in tractors, the agencies discussed above in Section II.B.2.b our decision 

in this final program to allow an “OBD phase-in” option for meeting the standards, based 

on comments received from several industry organizations indicating that aligning 

technology changes for multiple regulatory requirements would provide them with 

greater flexibility. In the context of HD diesel engines for use in vocational vehicles, 

Volvo, EMA/TMA, and DDC specifically requested an “OBD phase-in” option in its 

comments to the NPRM. DDC argued that bundling design changes where possible can 

reduce the burden on industry for complying with regulations, so aligning the 

 

146 See 75 FR at 25467-68.
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introduction of the OBD, GHG, and fuel consumption standards could help reduce the 

resources devoted to validation of new product designs and certification.

The agencies have the same interest in providing this flexibility for manufacturers 

of HD diesel engines for use in vocational vehicles as in providing it for manufacturers of 

HD diesel engines for use in combination tractors, as long as equivalent emissions and 

fuel savings are maintained. Thus, in order to provide additional flexibility for 

manufacturers looking to align their technology changes with multiple regulatory

requirements, the agencies are finalizing an alternate “OBD phase-in” option for meeting 

the HD diesel engine standards which delivers equivalent CO2 emissions and fuel 

consumption reductions as the primary standards for the engines built in the 2013 through 

2017 model years, as shown in Table II-18. 

Table II-18 Comparison of CO2 reductions for the Engine Standards under the Alternative OBD 

Phase-in and Primary Phase-In

HHD FTP LHD/MHD FTP

Primary 

Phase-in 

Standard 

(g/bhp-hr)

Optional 

Phase-in 

Standard 

(g/bhp-hr)

Difference in 

Lifetime 

CO2 Engine 

Emissions 

(MMT)

Primary 

Phase-in 

Standard 

(g/bhp-hr)

Optional 

Phase-in 

Standard 

(g/bhp-hr)

Difference in 

Lifetime CO2

Engine 

Emissions 

(MMT)

Baseline 584 584 -- 630 630 --

2013 MY 

Engine

584 577 20 630 618 14

2014 MY 

Engine

567 577 -28 600 618 -22

2015 MY 

Engine

567 577 -28 600 618 -22

2016 MY 

Engine

567 555 34 600 576 29

2017 MY 

Engine

555 555 0 576 576 0

Net 

Reductions 

(MMT)

-3 0

Table II-19 presents the final HD diesel engine CO2 emission and fuel 

consumption standards under the optional “OBD phase-in” option.
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Table II-19: Optional Heavy-Duty Engine Standard Phase-in

Model 

Year

Standard Light 

HeavyDuty

Diesel

Medium 

HeavyDuty

Diesel

Heavy 

HeavyDuty

Diesel

2013 CO2 Standard (g/bhp-hr) 618 618 577

Voluntary Fuel Consumption 

Standard (gallon/100 bhp-hr)

6.07 6.07 5.67

2016 and 

Later

CO2 Standard (g/bhp-hr) 576 576 555

Fuel Consumption (gallon/100 

bhp-hr)

5.66 5.66 5.45

In order to ensure equivalent CO2 and fuel consumption reductions and orderly 

compliance, and to avoid gaming, the agencies are requiring that if a manufacturer selects 

the OBD phase-in option, it must certify its engines starting in the 2013 model year and 

continue using this phase-in through 2016 model year. Manufacturers may opt into the 

OBD phase-in option through the voluntary NHTSA program, but must opt in in the 2013 

model year and continue using this phase-in through the 2016 model year. Manufacturers 

that opt in to the voluntary NHTSA program in 2014 and 2015 will be required to meet

the primary phase-in schedule and may not adopt the OBD phase-in option. 

As discussed above in Section II.B.2.b, while the agencies believe that the HD 

diesel engine standards are appropriate, cost-effective, and technologically feasible in the 

rulemaking time frame, we also recognize that when regulating a category of engines for 

the first time, there will be individual products that may deviate significantly from the 

baseline level of performance, whether because of a specific approach to criteria 

pollution control, or due to engine calibration for specific applications or duty cycles. 

That earlier discussion described HD diesel engines for use in combination tractors, but 

the same supporting information is relevant to the agencies’ consideration of an alternate 

standard for HD diesel engines installed in vocational vehicles. In the NPRM, the 

agencies proposed an optional engine standard for HD diesel engines installed in 

vocational vehicles based on a five percent reduction from the engine’s own 2011 model 

year baseline level, but requested comment on whether a two percent reduction would be 

more appropriate.

147

 The comments received in response did not directly address engines 

for vocational vehicles, but the agencies believe that the information provided by

Navistar and others is equally applicable to HD diesel engines for combination tractors 

and for vocational vehicles. Our assessment for the final standards is that a 2.5 percent 

reduction is appropriate for LHD and MHD engines installed in vocational vehicles and 3 

percent is appropriate for HHD engines installed in vocational vehicles given the 

technologies available for application to legacy products by model year 2014.148 Unlike 

the majority of engine products in this segment, engine manufacturers have devoted few 

resources to developing technologies for these legacy products reasoning that the 

 

147 See 75 FR at 74202.

148 To be codified at 40 CFR 1036.620.
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investment would have little value if the engines are to be substantially redesigned or 

replaced in the next five years. Hence, although the technologies we have identified to 

achieve the proposed five percent reduction would theoretically work for these legacy

products, there is inadequate lead time for manufacturers to complete the pre application 

development needed to add the technology to these engines by 2014. The mix of 

technologies available off the shelf for legacy engines varies between engine lines within 

OEMs and varies among OEMs as well. On average, based on our review of 

manufacturer development history and current plans, we project that for the legacy

products approximately half of the defined technologies appropriate for the 2014 standard 

will be available and ready for application by 2014 for older legacy engine designs. 

Hence, we have concluded that if we limit the reductions to those improvements which 

reflect further enhancements of already installed systems rather than the addition or

replacement of technologies with fully developed new on the shelf components, the 

potential improvement for the 2014 model year will be 2.5 percent for LHD and MHD 

engines and 3 percent HHD engines. 

Just as for HD diesel engines used in combination tractors, the agencies stress that 

this option for HD engines used in vocational vehicles is temporary and limited and is 

being adopted to address diverse manufacturer needs associated with complying with this 

first phase of the regulations. This optional, alternative standard will be available only

for the 2014 through 2016 model years, because we believe that manufacturers will have 

had ample opportunity to make appropriate changes to bring their product performance 

into line with the rest of the industry after that time. This optional standard will not be 

available unless and until a manufacturer has exhausted all available credits and credit 

opportunities, and engines under the alternative standard could not generate credits. 

The agencies note that manufacturers choosing to utilize this option in MYs 2014-

2016 will have to make a greater relative improvement in MY 2017 than the rest of the 

industry, since they will be starting from a worse level. For compliance purposes, in 

MYs 2014-2016 emissions from engines certified and sold at the alternate level will be 

averaged with emissions from engines certified and sold at more stringent levels to arrive 

at a weighted average emissions level for all engines in the subcategory. Again, this 

option can only be taken if all other credit opportunities have been exhausted and the 

manufacturer still cannot meet the primary standards. If a manufacturer chooses this 

option to meet the EPA emission standards in MY 2014 – 2016, and wants to opt into the 

NHTSA fuel consumption program in these same MYs it must follow the exact path 

followed under the EPA program utilizing equivalent fuel consumption standards.

As discussed above in Section II.B.2.b, Volvo argued that manufacturers could 

game the standard by establishing an artificially high 2011 baseline emission level. This 

could be done, for example, by certifying an engine with high fuel consumption and 

GHG emissions that is either: 1) not sold in significant quantities; or 2) later altered to 

emit fewer GHGs and consume less fuel through service changes. In order to mitigate

this possibility, the agencies are requiring either that the 2011 model year baseline must 

be developed by averaging emissions over all engines in an engine averaging set certified 

and sold for that model year so as to prevent a manufacturer from developing a single 

high GHG output engine solely for the purpose of establishing a high baseline or meet 
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additional criteria. The agencies are allowing manufacturers to combine light heavy-duty 

and medium heavy-duty diesel engines into a single averaging set for this provision 

because the engines have the same GHG emissions and fuel consumption standards. If a 

manufacturer does not certify all engine families in an averaging set to the alternate 

standards, then the tested configuration of the engine certified to the alternate standard 

must have the same engine displacement and its rated power within 5 percent of the 

highest rated power as the baseline engine. In addition, the tested configurations must 

have a BSFC equivalent to or better than all other configurations within the engine family 

and represent a configuration that is sold to customers. 

(ii) Gasoline Engine Standard

Heavy-duty gasoline engines are also used in vocational vehicle applications. The

number of engines certified in the past for this segment of vehicles is very limited and has 

ranged between three and five engine models.149 Unlike the heavy-duty diesel engines 

typical of this segment which are built for vocational vehicles, these gasoline engines are 

developed for heavy-duty pickup trucks and vans primarily, but are also sold as loose 

engines to vocational vehicle manufacturers, for use in vocational vehicles such as some 

delivery trucks. Some fleets still prefer gasoline engines over diesel engines. In the past, 

this was the case since gasoline stations were more prevalent than stations that sold diesel 

fuel. Because they are developed for HD pickups and vans, the agencies evaluated these 

engines in parallel with the heavy-duty pickup truck and van standard development. As 

in the pickup truck and van segment, the agencies anticipated that the manufacturers will 

have only one engine re-design within the 2014-2018 model years under consideration 

within the proposal. The agencies therefore proposed fuel consumption and CO2

emissions standards for gasoline engines for use in vocational vehicles, which represent a 

five percent reduction in CO2 emissions and fuel consumption in the 2016 model year 

over the 2010 MY baseline through use of technologies such as coupled cam phasing, 

engine friction reduction, and stoichiometric gasoline direct injection. 

In our meetings with all three of the major manufacturers in the HD pickup and 

van segment, confidential future product plans were shared with the agencies. Reflecting 

those plans and our estimates for when engine changes will be made in alignment with 

those product plans, we had concluded for proposal that the 2016 model year reflects the 

most logical model year start date for the heavy-duty gasoline engine standards. In order 

to meet the standards we are finalizing for heavy-duty pickups and vans, we project that 

all manufacturers will have redesigned their gasoline engine offerings by the start of the 

2016 model year. Given the small volume of loose gasoline engine sales relative to 

complete heavy-duty pickup sales, we think it is appropriate to set the timing for the 

heavy-duty gasoline engine standard in line with our projections for engine redesigns to 

meet the heavy-duty pickup truck standards. Therefore, NHTSA’s final fuel 

consumption standard and EPA’s final CO2 standard for heavy-duty gasoline engines are 

first effective in the 2016 model year. 

 

149 EPA’s heavy-duty engine certification database at http://www.epa.gov/otaq/certdata.htm#largeng.
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The baseline 2010 model year CO2 performance of these heavy-duty gasoline 

engines over the Heavy-duty FTP cycle is 660 g CO2/bhp-hr (7.43 gal/100 bhp-hr) in 

2010 based on non-GHG certification data provided to EPA by the manufacturers. The 

agencies are finalizing 2016 model year standards that require manufacturers to achieve a 

five percent reduction in CO2 compared to the 2010 MY baseline through use of 

technologies such as coupled cam phasing, engine friction reduction, and stoichiometric 

gasoline direct injection. Additional detail on technology feasibility is included in 

Section III and in the RIA Chapter 2. As shown in Table II-20, NHTSA is finalizing as 

proposed a 7.06 gallon/100 bhp-hr standard for fuel consumption while EPA is adopting 

as proposed a 627 g CO2/bhp-hr standard tested over the Heavy-duty FTP, effective in 

the 2016 model year. Similar to EPA’s non-GHG standards approach, manufacturers 

may generate and use credits by the same engine averaging set to show compliance with 

both agencies’ standards.

Table II-20: Heavy-Duty Gasoline Engine Standards

Model 

Year

Gasoline Engine

Standard

2016 and 

Later

CO2 Standard (g/bhp-hr) 627

Fuel Consumption 

(gallon/100 bhp-hr)

7.06

(c) In-Use Standards

Section 202(a)(1) of the CAA specifies that emissions standards are to be 

applicable for the useful life of the vehicle. The in-use standards that EPA is finalizing 

apply to individual vehicles and engines. NHTSA is not finalizing in-use standards that 

would apply to the vehicles and engines in a similar fashion. 

EPA proposed that the in-use standards for heavy-duty engines installed in 

vocational vehicles be established by adding an adjustment factor to the full useful life 

emissions results projected in the EPA certification process to account for measurement 

variability inherent in testing done at different laboratories with different engines. The 

agency proposed a two percent adjustment factor and requested comments and additional 

data during the proposal to assist in developing an appropriate factor level. The agency

received additional data during the comment period which identified production 

variability which was not accounted for at proposal. Details on the development of the 

final adjustment factor are included in RIA Chapter 3. Based on the data received, EPA 

determined that the adjustment factor in the final rules should be higher than the proposed 

level of two percent. EPA is finalizing a three percent adjustment factor for the in-use 

standard to provide a reasonable margin for production and test-to-test variability that 

could result in differences between the initial emission test results and emission results 

obtained during subsequent in-use testing. 

We are finalizing regulatory text (in §1036.150) to allow engine manufacturers to 

used assigned deterioration factors (DFs) without performing their own durability
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emission tests or engineering analysis. However, the engines would still be required to 

meet the standards in actual use without regard to whether the manufacturer used the 

assigned DFs. This allowance is being adopted as an interim provision applicable only 

for this initial phase of standards. 

Manufacturers will be allowed to use an assigned additive DF of 0.0 g/bhp-hr for 

CO2 emissions from any conventional engine (i.e., an engine not including advance or 

innovative technologies). Upon request, we could allow the assigned DF for CO2

emissions from engines including advance or innovative technologies, but only if we 

determine that it would be consistent with good engineering judgment. We believe that 

we have enough information about in-use CO2 emissions from conventional engines to 

conclude that they will not increase as the engines age. However, we lack such 

information about the more advanced technologies. 

EPA proposed that the useful life for these engines and vehicles with respect to 

GHG emissions be set equal to the respective useful life periods for criteria pollutants. 

EPA proposed that the existing engine useful life periods, as included in Table II-21, be 

broadened to include CO2 emissions and fuel consumption for both engines and 

vocational vehicles. The agency did not receive any adverse comments with this 

approach and is finalizing the useful life periods as proposed (see 40 CFR 1036.108(d) 

and 1037.105). While NHTSA will use useful life considerations for establishing fuel 

consumption performance for initial compliance and for ABT, NHTSA does not intend to 

implement an in-use compliance program for fuel consumption, because it is not required 

under EISA and because it is not currently anticipated there will be notable deterioration 

of fuel consumption over the engines’ useful life. 

Table II-21: Useful Life Periods

Years Miles

Class 2b-5 Vocational Vehicles, Spark Ignited, and 

Light Heavy-Duty Diesel Engines

10 110,000

Class 6-7 Vocational Vehicles and Medium 

Heavy-Duty Diesel Engines

10 185,000

Class 8 Vocational Vehicles and Heavy HeavyDuty Diesel Engines10 435,000

(2) Test Procedures and Related Issues

The agencies are finalizing test procedures to evaluate fuel consumption and CO2

emissions of vocational vehicles in a manner very similar to Class 7 and Class 8 

combination tractors. This section describes the simulation model for demonstrating 

compliance, engine test procedures, and a test procedure for evaluating hybrid 

powertrains (a potential means of generating credits, although not part of the technology

package on which the final standard for vocational vehicles is premised).
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(a) Computer Simulation Model

As previously mentioned, to achieve the goal of reducing emissions and fuel 

consumption for both trucks and engines, we are finalizing separate engine and vehiclebased emission and fuel consumption standards for vocational vehicles and engines used 

in those vehicles. For the vocational vehicles, engine manufacturers are subject to the 

engine standards, and chassis manufacturers are required to install certified engines in 

their chassis. The chassis manufacturer is subject to a separate vehicle-based standard 

that uses the final vehicle simulation model, the GEM, to evaluate the impact of the tire 

design to determine compliance with the vehicle standard. 

A simulation model, in general, uses various inputs to characterize a vehicle’s 

properties (such as weight, aerodynamics, and rolling resistance) and predicts how the 

vehicle would behave on the road when it follows a driving cycle (vehicle speed versus 

time). On a second-by-second basis, the model determines how much engine power 

needs to be generated for the vehicle to follow the driving cycle as closely as possible. 

The engine power is then transmitted to the wheels through transmission, driveline, and 

axles to move the vehicle according to the driving cycle. The second-by-second fuel 

consumption of the vehicle, which corresponds to the engine power demand to move the 

vehicle, is then calculated according to the fuel consumption map embedded in the 

compliance model. Similar to a chassis dynamometer test, the second-by-second fuel 

consumption is aggregated over the complete drive cycle to determine the fuel 

consumption of the vehicle.

NHTSA and EPA are finalizing an approach consistent with the proposal to 

evaluate fuel consumption and CO2 emissions respectively through a simulation of 

whole-vehicle operation, consistent with the NAS recommendation to use a truck model 

to evaluate truck performance. The EPA developed the GEM for the specific purpose of 

this rulemaking to evaluate vehicle performance. The GEM is similar in concept to a 

number of vehicle simulation tools developed by commercial and government entities. 

The model developed by the EPA and finalized here was designed for the express 

purpose of vehicle compliance demonstration and is therefore simpler and less 

configurable than similar commercial products. This approach gives a compact and 

quicker tool for evaluating vehicle compliance without the overhead and costs of a more 

complicated model. Details of the model, including changes made to the model to 

address concerns of the peer reviewers and commenters are included in Chapter 4 of the 

RIA. An example of the GEM input screen is shown in Figure II-4.
*** E.O. 12866 Review – Revised Version 

EPA and NHTSA have validated the GEM simulation of vocational vehicles 

against a commonly used simulation tool used in 

vehicle subcategory. Prior to using GT

benchmarked a GT-Drive simulation of the combination tractor tested at Southwest 

Research against the experimental test results f

manner as done for GEM. Then the EPA developed three vocational vehicle models 

(LHD, MHD, and HHD) and simulated them using both GEM and GT

the GEM and GT-Drive predicted the fuel consumption and CO

vocational vehicle subcategories with differences of less than 2 percent for the three test 

cycles – the California ARB Transient cycle, 55 mph cruise, and 65 mph cruise cycle.

The final simulation model is described in greater 

available for download by interested parties at (

The agencies are requiring that for demonstrating compliance, a chassis 

manufacturer would measure the performance of tires, input the values into 

compare the model’s output to the standard. As explained earlier, low rolling resistance 

tires are the only technology on which the agencies’ own feasibility analysis for these 

vehicles is predicated. The input values for the simulation model wi

manufacturer from the final tire test procedure described in this action. The remaining 

 

150 See RIA Chapter 4, Table 4

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Figure II-4: Example GEM Input Screen

EPA and NHTSA have validated the GEM simulation of vocational vehicles 

against a commonly used simulation tool used in industry, GT-Drive, for each vocational 

vehicle subcategory. Prior to using GT-Drive as a comparison tool, the agencies first 

Drive simulation of the combination tractor tested at Southwest 

Research against the experimental test results from the chassis dynamometer in the same 

manner as done for GEM. Then the EPA developed three vocational vehicle models 

(LHD, MHD, and HHD) and simulated them using both GEM and GT-Drive. Overall, 

Drive predicted the fuel consumption and CO2 emissions for all three 

vocational vehicle subcategories with differences of less than 2 percent for the three test 

the California ARB Transient cycle, 55 mph cruise, and 65 mph cruise cycle.

The final simulation model is described in greater detail in RIA Chapter 4 and is 

available for download by interested parties at (http://www.epa.gov/otaq/

The agencies are requiring that for demonstrating compliance, a chassis 

manufacturer would measure the performance of tires, input the values into 

compare the model’s output to the standard. As explained earlier, low rolling resistance 

tires are the only technology on which the agencies’ own feasibility analysis for these 

vehicles is predicated. The input values for the simulation model will be derived by the 

manufacturer from the final tire test procedure described in this action. The remaining 

 

RIA Chapter 4, Table 4-8.

Do Not Cite, Quote, or Release During Review ***

EPA and NHTSA have validated the GEM simulation of vocational vehicles 

Drive, for each vocational 

Drive as a comparison tool, the agencies first 

Drive simulation of the combination tractor tested at Southwest 

rom the chassis dynamometer in the same 

manner as done for GEM. Then the EPA developed three vocational vehicle models 

Drive. Overall, 

emissions for all three 

vocational vehicle subcategories with differences of less than 2 percent for the three test 

the California ARB Transient cycle, 55 mph cruise, and 65 mph cruise cycle. 150 

detail in RIA Chapter 4 and is 

http://www.epa.gov/otaq/). 

The agencies are requiring that for demonstrating compliance, a chassis 

manufacturer would measure the performance of tires, input the values into GEM, and 

compare the model’s output to the standard. As explained earlier, low rolling resistance 

tires are the only technology on which the agencies’ own feasibility analysis for these 

ll be derived by the 

manufacturer from the final tire test procedure described in this action. The remaining 
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164 of 971

model inputs will be fixed values pre-defined by the agencies. These are detailed in the 

RIA Chapter 4, including the engine fuel consumption map to be used in the simulation.

(b) Tire Rolling Resistance Assessment

In terms of how tire rolling resistance would be measured, the agencies proposed 

to require that the tire rolling resistance input to the GEM be determined using ISO 

28580:2009(E), Passenger car, truck and bus tyres—Methods of measuring rolling 

resistance—Single point test and correlation of measurement results.

151

 The agencies 

stated that they believed the ISO test method was the most appropriate for this program 

because the method is the same one used by the NHTSA tire fuel efficiency consumer 

information program,152 by European regulations,153 and by the EPA SmartWay program. 

The NPRM also discussed the potential for tire-to-tire variability to confound 

rolling resistance measurement results for LRR tires – that is, different tires of the same 

tire model could turn out to have different rolling resistance measurements when run on 

the same test. NHTSA’s research during the development of the light-duty vehicle tire 

fuel efficiency consumer information program identified several sources of variability

including test procedures, test equipment and the tires themselves, but found that all of 

the existing test methods had similar levels of and sources of variability.

154

 The agencies 

proposed to address production tire-to-tire variability by specifying that three tire samples 

within each tire model be tested three times each, and that the average of the nine tests 

would be used as the Rolling Resistance Coefficient (CRR) for the tire, which would be 

the basis for the rolling resistance value for that tire that the manufacturer would enter 

into the GEM. The agencies requested comment on this proposed method.155

The agencies received many comments on the subject of tire rolling resistance, 

including suggestions for alternative test procedures and compliance issues. Regarding 

whether the agencies should base tire CRR inputs for the GEM on the use of the ISO 

28580 test procedure, the American Automotive Policy Council (AAPC) argued that the 

agencies should instead require the SAE J2452 Coastdown test method for calculating 

tire rolling resistance, which the commenter stated was preferred by OEMs because it 

simulates the use of tires on actual vehicles rather than the ISO procedure which tests the 

tire by itself. The Rubber Manufacturers Association (RMA) argued, in contrast, that the 

agencies should use the SAE J1269 multi-point test, which is currently the basis for the 

EPA SmartWayTM CRR baseline values. RMA also argued that the SAE J1269 multipoint test can be used to accurately predict truck/bus tire CRR at various loads and 

inflations, including at the ISO 28580 load and inflation conditions, and that therefore the 

agencies should use the SAE test, or if the agencies want to use ISO, they should accept 

results from the SAE test and just correlate them. Regarding compliance obligations, 

RMA further argued that it was not clear how or in what format testing information 

 

151

 See http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=44770.

152 75 FR 15893, March 30,2010

153 See http://www.energy.ca.gov/2009publications/CEC-600-2009-010/CEC-600-2009-010-SD-REV.PDF

(last accessed May 9, 2011)

154 75 FR 15893, March 30, 2010

155 See generally 75 FR at 74204.
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would need to be provided in order to be in compliance with the proposed requirement at

§1037.125(i).

The agencies analyzed many comments on the subject of tire rolling resistance.

One of the primary concerns raised in comments was that the proposed test protocol and 

measurement methodology would not adequately address production tire variability and 

measurement variability. Commenters stated that machine-to-machine differences are a 

significant source of variation, and this variation would make it difficult for 

manufacturers to be confident that the agency would assign the same CRR to a tire was 

tested for compliance purposes. Commenters argued that the ISO 28580 test method is 

unique in that it specifies a procedure to correlate results between different test 

equipment (i.e., different rolling resistance test machines), but not all aspects of the ISO 

procedure have been completely defined. Commenters stated that under ISO 28580, the 

lab alignment procedure depends on the specification of a reference test machine to 

which all other labs will align their measurement results. RMA particularly emphasized 

the need for establishing a tire testing reference lab for use with ISO 28580, referencing 

the European Tyre and Rim Technical Organization (ETRTO) estimate that CRR values 

could vary as much as 20 percent absent an inter-laboratory alignment procedure. RMA 

stated the agencies should specify a reference laboratory with the designation proposed in 

a supplemental notice that provides public comment. In addition, RMA commented that 

the extra burden proposed by the agencies for testing three tires, three times each is nine 

times more burdensome than what is required through the ISO procedure.

Based on the additional tire rolling resistance research conducted by the agencies, 

we have decided to use the ISO 28580 test procedure, as proposed, to measure tire 

performance for these final rules.

The agencies believe this test procedure provides two advantages over other test 

methods. First, the ISO 28580 test method is unique in that it specifies a procedure to 

correlate results between different test equipment (i.e., different tire rolling resistance test 

machines). This is important because NHTSA’s research conducted for the light-duty tire 

fuel efficiency program indicated that machine-to-machine differences are a source of 

variation.156 In addition, the ISO 28580 test procedure is either used, or proposed to be 

used, by several groups including the European Union through Regulation (EC) No 

661/2009157 and the California Air Resources Board (CARB) through a staff 

recommendation for a California regulation,

158 and the EPA SmartWay program. Using 

the ISO 28580 may help reduce burden on manufacturers by allowing a single test 

protocol to be used for multiple regulations and programs. While we recognize that 

commenters recommended the use of other test procedures, like SAE J1269, the agencies 

have determined there is no established data conversion method from the SAE J1269 

vehicle condition for vocational vehicle tires to the ISO 28580 single point condition at 

this time, and that given our reasonable preference for the ISO procedure, it would not be 

 

156 75 FR 15893, March 30, 2010

157 See http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2009:200:0001:0024:EN:PDF (last 

accessed May 8, 2011).

158 See http://www.energy.ca.gov/2009publications/CEC-600-2009-010/CEC-600-2009-010-SD-REV.PDF

(last accessed May 9, 2011)
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practical to attempt to include the use of the SAE J1269 procedure as an optional way of 

determining CRR values for the GEM inputs. 

The agencies received comments from the Rubber Manufacturers Association, 

Michelin, and Bridgestone which identified the need to develop a reference lab and 

alignment tires. Because the ISO has not yet specified a reference lab and machine for 

the ISO 28580 test procedure, NHTSA announced in its March 2010 final rule 

concerning the light-duty tire fuel efficiency consumer information program that NHTSA 

would specify this laboratory for the purposes of implementing that rule so that tire 

manufacturers would know the identity of the machine against which they may correlate 

their test results. NHTSA has not yet announced the reference test machine(s) for the tire 

fuel efficiency consumer information program. Therefore, for the light-duty tire fuel 

efficiency rule, the agencies are postponing the specification of a procedure for machineto-machine alignment until a tire reference lab is established. The agencies anticipate 

establishing this lab in the future with intentions for the lab to accommodate the lightduty tire fuel efficiency program.

Under the ISO 28580 lab alignment procedure, machine alignment is conducted 

using batches of alignment tires of two models with defined differences in rolling 

resistance that are certified on a reference test machine. ISO 28580 specifies 

requirements for these alignment tires (“Lab Alignment Tires” or LATs), but exact tire 

sizes or models of LATs are not specifically identified in ISO 28580. Because the test 

procedure has not been finalized and heavy-duty LATs are not currently defined, the 

agencies are postponing the use of these elements of ISO 28580 to a future rulemaking. 

The agencies also note the lab-to-lab comparison conducted in the most recent EPA tire 

test program mentioned previously. The agencies reviewed the CRR data from the tires 

that were tested at both the STL and Smithers laboratories to assess inter-laboratory and 

machine variability. The agencies conducted statistical analysis of the data to gain better 

understanding of lab-to-lab correlation and developed an adjustment factor for data 

measured at each of the test labs. Based on these results, the agencies believe the lab-tolab variation for the STL and Smithers laboratories would have very small effect on 

measured CRR values. Based on the test data, the agencies judge that it is reasonable to 

implement the HD program with current levels of variability, and to allow the use of 

either Smithers or STL laboratories for determining the CRR value in the HD program, or 

demonstrate that the test facilities will not bias results low relative to Smithers or STL 

laboratories. 

RMA also commented that the extra burden proposed by the agencies for testing 

three tires, three times each is nine times more burdensome than what is required through 

the ISO procedure. Since the proposal, EPA obtained replicate test data for a number of

Class 8 combination tractor tires from various manufacturers. Some of these were tires 

submitted to SmartWay for verification, while some were tires tested by manufacturers 

for other purposes. Three tire model samples for 11 tire models were tested using the 

ISO 28580 test.159 A mean and a standard deviation were calculated for each set of three 

 

159 Bachman, Joseph. EPA Memorandum to the Docket. Heavy-Duty Tire Evaluation. Docket EPA-HQOAR-2010-0162. July 2011.
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replicate measurements performed on each tire of the 3-tire sample. The coefficient of 

variability (COV) of the CRR was calculated by dividing the standard deviation by the 

mean. The values of COV ranged from 0 percent (no measurable variability) to six 

percent. In addition, during the period September 2010 and June 2011, EPA contracted 

with Smithers-Rapra to select and test for rolling resistance using ISO 28580 for a 

representative sample of Class 4-8 vocational vehicle tires. As part of the test, 10 tires 

were selected for replicate testing.160 Three replicate tests were conducted for each of the 

tires, to evaluate test variability only. The COV of the RRC results ranged from nearly 0 

to 2 percent, with a mean of less than 1 percent. Based on the results of these two testing 

programs, the agencies determined that the impact of production variability is greater 

than the impact of measurement variability. Thus, the agencies concluded that the extra 

burden of testing a single tire three times was not necessary to obtain accurate results, but 

the variability of RRC results due to manufacturing of the tires is significant to continue 

to require testing of three tire samples for each tire model. In summary, we are allowing 

manufacturers to determine the rolling resistance coefficient of the heavy-duty tires by 

testing three tire samples one time each. 

For the final rules, the agencies are also including a warm up cycle as part of the 

procedure for bias ply tires to allow these tires to reach a steady temperature and volume 

state before ISO 28580 testing. This procedure is similar to a procedure that was 

developed for the light-duty tire fuel efficiency consumer information program, and was 

adopted from a procedure defined in Federal motor vehicle safety standard No. 109 

(FMVSS No. 109).161

Finally, the agencies are including testing and reporting for ‘single-wide’ or 

‘super-single’ type tires. These tires replace the traditional ‘dual’ wheel tire combination 

with a single wheel and tire that is nearly as wide as the dual combination with similar 

load capabilities. These tire types were developed as a fuel saving technology. The tires

provide lower rolling resistance along with a reduction in weight when compared to a 

typical set of dual wheel tire combinations; and are one of the technologies included in 

the EPA SmartWayTM program. The agencies have learned that there is limited testing 

equipment available that is capable of testing single wide tires; single wide tires require a 

wider test machine drum than required for conventional tires. Although the number of 

machines available is limited, the agencies believe the equipment is adequate for the 

testing and reporting of CRR for this program.

As discussed above, the agencies are taking the approach of using CRR for the 

HD fuel efficiency and greenhouse gas program to align with the measurement 

methodology already employed or proposed by the EPA SmartWay program, the

European Union Regulation (EC) No 661/2009162 and the California Air Resources Board 

(CARB) through a staff recommendation for a California regulation.

163

 In the NPRM, 

the agencies proposed to use CRR, but for purposes of developing these final rules, the 

 

160 Bachman, Joseph. EPA Memorandum to the Docket. Heavy-Duty Tire Evaluation. Docket EPA-HQOAR-2010-0162. July 2011.

161 See 49 CFR 571.109.

162 See Note 157, above.

163 See Note 158, above.
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agencies also evaluated whether to use CRR or Rolling Resistance Force (RRF) as the 

measurement for tire rolling resistance for the GEM input. The agencies considered RRF

largely because in the NPRM for Passenger Car Tire Fuel Efficiency (TFE) program, 

NHTSA had proposed to use RRF. A key distinction between these two programs, and 

their associated metrics, are the differences in how the measurement data are used and 

who uses the data. In particular, the HD fuel efficiency and GHG emissions program is a 

compliance program using information developed by and for technical personnel at 

manufacturers and agencies to determine a vehicle’s compliance with regulations. The 

TFE program, in contrast, is a consumer education program intended to inform 

consumers making purchase decisions regarding the fuel saving benefits of replacement 

passenger car tires. The target audiences are much different for the two programs which 

in turn affect how the information will be used. The agencies believe that RRF may be 

more intuitive for non-technical people because tires that are larger and/or that carry

higher loads will generally have numerically higher RRF values than smaller tires and/or 

tires that carry lower loads. CRR values generally follow an opposite trend, where tires 

that are larger and/or carry higher loads will generally have numerically lower CRR

values than smaller tires and/or tires that carry lower loads. The agencies believe this key

distinction helps define the type of metrics to be used and communicated in accordance 

with their respective purposes.

Additionally, the CRR metric for use in the MD/HD program is not susceptible to 

the skew associated with tire diameter. Medium- and heavy-duty vehicle tires are 

available in a small fraction of the tire sizes of the passenger market and, for the most 

part, are larger tires than those found on passenger cars. When viewing CRR over a 

larger range of sizes, small diameter tires tend to appear as having a lower performance, 

which is not necessarily accurate, with the converse occurring as the diameter increases. 

Using the CRR value for determining the rolling resistance also takes into account 

the load carrying capability for the tire being tested, which, intuitively, can lead to some 

potentially confusing results. Several vocational vehicle manufacturers argued in their 

comments that LRR tires were not available for, e.g., vehicles like refuse trucks, which 

tend to use large diameter tires to carry very heavy loads. Based on the agencies’ testing, 

in fact, the measured CRR (as opposed to the RRF) for refuse trucks were found to be 

among the best tested. This finding can be explained by considering that CRR is 

calculated by dividing the measured rolling resistance force by the tire’s load capacity 

rating. Although the tire may have a relatively high rolling resistance force, the tire load 

capacity rating is also very high, resulting in an overall lower (better) CRR value than 

many other types of tires. The amount of load tire can carry (test load) contributes to a 

very low reported CRR, thus confirming low rolling resistance tires meeting the 

standards, as measured by CRR, are available to the industry regardless of segment or 

application.

Based on these considerations, the agencies have decided to use the CRR metric 

for the HD fuel efficiency and GHG emissions program.
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(c) Defined Vehicle Configurations in the GEM

As discussed above, the agencies are finalizing a methodology that chassis 

manufacturers will use to quantify the tire rolling resistance values to be input into the 

GEM. Moreover, the agencies are defining the remaining GEM inputs (i.e., specifying 

them by rule), which differ by the regulatory subcategory (for reasons described in the 

RIA Chapter 4). The defined inputs, among others, include the drive cycle, 

aerodynamics, vehicle curb weight, payload, engine characteristics, and drivetrain for 

each vehicle type.

(i) Metric

Based on NAS’s recommendation and feedback from the heavy-duty truck 

industry, NHTSA and EPA proposed standards for vocational vehicles that would be 

expressed in terms of moving a ton of payload over one mile. Thus, NHTSA’s proposed 

fuel consumption standards for these vehicles would be represented as gallons of fuel 

used to move one ton of payload one thousand miles, or gal/1,000 ton-mile. EPA’s 

proposed CO2 vehicle standards would be represented as grams of CO2 per ton-mile. The 

agencies received comments that a payload-based metric is not appropriate for all types 

of vocational vehicles, specifically buses. The agencies recognize that a payload-based 

approach may not be the most representative of an individual vocational application; 

however, it best represents the broad vocational category. The metric which we proposed 

treats all vocational applications equally and requires the same technologies be applied to 

meet the standard. Thus, the agencies are adopting the proposed metric, but will revisit 

the issue of metrics in any future action, if required, depending on the breadth of each 

standard.

(ii) Drive cycle

The drive cycles proposed for the vocational vehicles consisted of the same three 

modes used for the Class 7 and8 combination tractors. The proposed cycle included the 

Transient mode, as defined by California ARB in the HHDDT cycle, a constant speed 

cycle at 65 mph and a 55 mph constant speed mode. The agencies proposed different 

weightings for each mode for vocational vehicles than those proposed for Class 7 and 8 

combination tractors, given the known difference in driving patterns between these two 

categories of vehicles. The same reasoning underlies the agencies’ use of the Heavy-duty 

FTP cycle to evaluate compliance with the standards for diesel engines used in vocational 

vehicles.

The variety of vocational vehicle applications makes it challenging to establish a 

single cycle which is representative of all such trucks. However, in aggregate, the 

vocational vehicles typically operate over shorter distances and spend less time cruising 

at highway speeds than combination tractors. The agencies evaluated for proposal two 

sources for mode weightings, as detailed in RIA Chapter 3. The agencies proposed the 

mode weightings based on the vehicle speed characteristics of single unit trucks used in 

EPA’s MOVES model which were developed using Federal Highway Administration 
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data to distribute vehicle miles traveled by road type.164 The proposed weighted CO2 and 

fuel consumption value consisted of 37 percent of 65 mph Cruise, 21 percent of 55 mph 

Cruise, and 42 percent of Transient performance.

The agencies received comments stating that the proposed drive cycles and 

weightings are not representative of individual vocational applications, such as buses and 

refuse haulers. A number of groups commented that the vocational vehicle cycle is not 

representative of real world driving and recommended changes to address that concern. 

Several organizations proposed the addition of new drive cycles to make the test more 

representative. 

Bendix suggested using the Composite International Truck Local and Commuter 

Cycle (CILCC) as the general purpose mixed urban/freeway cycles and to use four 

representative cycles: mixed urban, freeway, city bus, refuse, and utility. Bendix 

suggested using the Standardized On-Road Test (SORT) cycles for vocational vehicles 

operating in the urban environment in addition to SORT cycles for 3 different vocations –

with separate weightings. They stated that SORT with an average speed of 11.2 mph, 

lines up most closely with the average of transit bus duty cycles at 9.9 mph as well as the 

overall US National average of 12.6 mph. As alternative approaches they suggested 

adopting the Orange County duty cycle for the urban transit bus vocation, or creating an 

Urban Transit Bus cycle with several possible weighting factors – all with very high 

percentage transient (90% to 100%), very low 55 mph (0% to 7%), very low 65 mph (0% 

to 3%), and an average speed of 15 to 17 mph. Bendix supported their assertions about 

urban bus vehicle speed with data from the 2010 American Public Transportation 

Association (APTA) ‘Fact Book’ and other sources. In contrast, Bendix stated, the GEM 

cycle average speed is currently 32.6 mph. Such high speeds at steady state will penalize 

technologies such as hybridization.

Clean Air Task Force said the agencies have not adequately addressed the 

diversity of the vocational vehicle fleet since they are not distinguished by different duty 

cycles. They urged the agencies to sub-divide vocational vehicles by expected use, with 

separate test cycles for each sub-group in order to capture the full potential benefits of 

hybridization and other advanced technologies in a meaningful and accurate way in 

future rulemakings for MY2019 and later trucks. 

Two groups cautioned that unintended consequences could result from the lack of 

diversity in duty cycles. DTNA said that the single drive cycle proposed for all vehicles 

by the agencies would likely lead to unintended consequences - such as customers being 

driven for regulatory reasons to purchase a transmission that does not suit their actual 

operation. Similarly, Volvo said medium- and heavy-duty vehicles are uniquely built for 

specific applications but it will not be feasible to develop regulatory protocols that can 

accurately predict efficiency in each application duty cycle. This trade-off could result in 

unintended or negative consequences in parts of the market. 

 

164The Environmental Protection Agency. Draft MOVES2009 Highway Vehicle Population and Activity 

Data. EPA-420-P-09-001, August 2009 http://www.epa.gov/otaq/models/moves/techdocs/420p09001.pdf
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Several commenters suggested changing the weightings of the cycle to more 

accurately reflect real world driving. Allison stated that the vocational vehicle cycle 

includes too much steady state driving time. They suggested (with supporting data from 

the Oakridge National Laboratory analysis) reducing steady state driving at 60 mph to 

minimal or no time on the cycle to address this problem. Allison commented that GEM 

contains lengthy accelerations to reach 55 and 65 miles per hour – much longer than is 

required in real world driving. They supported this statement with data from a testing 

program conducted at Oakridge National Laboratory showing medium- and heavy-duty 

vehicles accelerate more rapidly than in the GEM drive cycle. According to Allison, this 

long acceleration time in the GEM, coupled with too much steady state operation with 

very little variation, is not representative of vocational vehicle operation. In addition, 

Allison said that the GEM does not adequately account for shift time, clutch profile, turbo 

lag, and other impacts on both steady state and transient operation. The impact, they

state, is that the cycle will hinder proper deployment of technologies to reduce fuel 

consumption and GHG emissions.

BAE focused their comments on urban transit bus operation. They stated the 

weighting factors for steady state operation are inconsistent with urban transit bus cycles.

Other commenters suggested the agencies develop chassis dynamometer tests 

based on the engine (FTP) test. Cummins said that chassis dynamometer testing should 

allow the use of average vehicle characteristics to determine road load and make use of 

the vehicle FTP and SET cycles. Others commented that the correlation between the FTP 

and the UDDS is poor.

After careful consideration of the comments, the agencies are adopting the 

proposed drive cycles. The final drive cycles and weightings represent the straight truck 

operations which dominate the vehicle miles travelled by vocational vehicles. The 

agencies do not believe that application-specific drive cycles are required for this final 

action because the program is based on the generally-applicable use of low rolling 

resistance tires. The drive cycles that we are adopting treat all vocational applications 

equally predicate standard stringency on use of the same technology (LRR tires) to meet 

the standard. The drive cycles in the final rule accurately reflect the performance of this 

technology. The agencies are also finalizing, as proposed, the mode weightings based on 

the vehicle speed characteristics of single unit trucks used in EPA’s MOVES model 

which were developed using Federal Highway Administration data to distribute vehicle 

miles traveled by road type.165 Similar to the issue of metrics discussed above, the 

agencies may revisit drive cycles and weightings in any future regulatory action to 

develop standards specific to applications.

(iii) Empty Weight and Payload

The total weight of the vehicle is the sum of the tractor curb weight and the 

payload. The agencies are proposed to specify each of these aspects of the vehicle. The 

 

165The Environmental Protection Agency. Draft MOVES2009 Highway Vehicle Population and Activity 

Data. EPA-420-P-09-001, August 2009 http://www.epa.gov/otaq/models/moves/techdocs/420p09001.pdf
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agencies developed the proposed vehicle curb weight inputs based on industry

information developed by ICF.166 The proposed curb weights were 10,300 pounds for the 

LHD trucks, 13,950 pounds for the MHD trucks, and 29,000 pounds for the HHD trucks. 

NHTSA and EPA proposed payload requirements for each regulatory category

developed from Federal Highway statistics based on averaging the payloads for the 

weight categories represented within each vehicle subcategory.

167

 The proposed 

payloads were 5,700 pounds for the Light Heavy-Duty trucks, 11,200 pounds for 

Medium Heavy-Duty trucks, and 38,000 pounds for Heavy Heavy-Duty trucks. 

The agencies received comments from several stakeholders regarding the 

proposed curb weights and payloads for vocational vehicles. BAE said a Class 8 transit 

bus has a typical curb weight of 27,000 pounds and maximum payload of 15,000 pounds. 

Daimler commented that Class 8 buses have a GVWR of 42,000 pounds. Autocar said 

that Class 8 refuse trucks typically have a curb weight of 31,000 to 33,000 pounds, 

typical average payload of 10,000 pounds, and typical maximum payload of 20,000 

pounds.

Upon further consideration, the agencies are reducing the assigned weight of 

heavy heavy-duty vocational vehicles. While we still believe the proposed values are 

appropriate for some vocational vehicles, we reduced the total weight to bring it closer to 

some of the lighter vocational vehicles. The agencies are adopting final curb weights of 

10,300 pounds for the LHD trucks, 13,950 pounds for the MHD trucks, and 27,000 

pounds for the HHD trucks. The agencies are also adopting payloads of 5,700 pounds for 

the Light Heavy-Duty trucks, 11,200 pounds for Medium Heavy-Duty trucks, and 15,000 

pounds for Heavy Heavy-Duty trucks. Additional information is available in RIA Chapter 

3.

(iv) Engine

As the agencies are finalizing separate engine and vehicle standards, the GEM 

will be used to assess the compliance of the chassis with the vehicle standard. To 

maintain the separate assessments, the agencies are adopting the proposed approach of 

using fixed values that are predefined by the agencies for the engine characteristics used 

in GEM, including the fuel consumption map which provides the fuel consumption at 

hundreds of engine speed and torque points. If the agencies did not standardize the fuel 

map, then a vehicle that uses an engine with emissions and fuel consumption better than 

the standards would require fewer vehicle reductions than those being finalized. As 

proposed, the agencies are using diesel engine characteristics in the GEM, as most 

representative of the largest fraction of engines in this market. The agencies did not 

receive any adverse comments to using this approach. 

 

166 ICF International. “Investigation of Costs for Strategies to Reduce Greenhouse Gas Emissions for 

Heavy-Duty On-Road Vehicles.” July 2010. Pages 16-20. Docket ID# EPA-HQ-OAR-2010-0162-0044.

167 The U.S. Federal Highway Administration. Development of Truck Payload Equivalent Factor. Table 

11. Last viewed on March 9, 2010 at 

http://ops.fhwa.dot.gov/freight/freight_analysis/faf/faf2_reports/reports9/s510_11_12_tables.htm
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The agencies are finalizing two distinct sets of fuel consumption maps for use in 

GEM. The first fuel consumption map would be used in GEM for the 2014 through 2016 

model years and represent a diesel engine which meets the 2014 model year engine CO2

emissions standards. A second fuel consumption map would be used beginning in the 

2017 model year and represents a diesel engine which meets the 2017 model year CO2

emissions and fuel consumption standards and accounts for the increased stringency in 

the final MY 2017 standard). The agencies have modified the 2017 MY heavy heavyduty diesel fuel map used in the GEM for the final rulemaking to address comments 

received. Details regarding this change can be found in RIA Chapter 4.4.4. Effectively 

there is no change in stringency of the vocational vehicle standard (not including the 

engine) between the 2014 MY and 2017 MY standards for the full rulemaking period. 

These inputs are reasonable (indeed, seemingly necessitated) given the separate final 

regulatory requirement that vocational vehicle chassis manufacturers use only certified 

engines. 

(v) Drivetrain

The agencies’ assessment of the current vehicle configuration process at the truck 

dealer’s level is that the truck companies provide software tools to specify the proper 

drivetrain matched to the buyer’s specific circumstances. These dealer tools allow a 

significant amount of customization for drive cycle and payload to provide the best 

specification for the customer. The agencies are not seeking to disrupt this process. 

Optimal drivetrain selection is dependent on the engine, drive cycle (including vehicle 

speed and road grade), and payload. Each combination of engine, drive cycle, and 

payload has a single optimal transmission and final drive ratio. The agencies are 

specifying the engine’s fuel consumption map, drive cycle, and payload; therefore, it 

makes sense to specify the drivetrain that matches. 

(d) Engine Metrics and Test Procedures

EPA proposed that the GHG emission standards for heavy-duty engines under the 

CAA would be expressed as g/bhp-hr while NHTSA’s proposed fuel consumption 

standards under EISA, in turn, be represented as gal/100 bhp-hr. The NAS panel did not 

specifically discuss or recommend a metric to evaluate the fuel consumption of heavyduty engines. However, as noted above they did recommend the use of a load-specific 

fuel consumption metric for the evaluation of vehicles.168 An analogous metric for 

engines is the amount of fuel consumed per unit of work. The g/bhp-hr metric is also 

consistent with EPA’s current standards for non-GHG emissions for these engines. The 

agencies did not receive any adverse comments related to the metrics for HD engines; 

therefore, we are adopting the metrics as proposed. 

With regard to GHG and fuel consumption control, the agencies believe it is 

appropriate to set standards based on a single test procedure, either the Heavy-duty FTP 

or SET, depending on the primary expected use of the engine. EPA’s criteria pollutant 

standards for engines currently require that manufacturers demonstrate compliance over 

 

168 See NAS Report, Note 21, at page 39.
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the transient Heavy-duty FTP cycle; over the steady-state SET procedure; and during notto-exceed testing. EPA created this multi-layered approach to criteria emissions control 

in response to engine designs that optimized operation for lowest fuel consumption at the 

expense of very high criteria emissions when operated off the regulatory cycle. EPA’s 

use of multiple test procedures for criteria pollutants helps to ensure that manufacturers 

calibrate engine systems for compliance under all operating conditions. We are not 

concerned if manufacturers further calibrate these engines off cycle to give better in-use 

fuel consumption while maintaining compliance with the criteria emissions standards as 

such calibration is entirely consistent with the goals of our joint program. Further, we 

believe that setting standards based on both transient and steady-state operating 

conditions for all engines could lead to undesirable outcomes. 

It is critical to set standards based on the most representative test cycles in order 

for performance in-use to obtain the intended (and feasible) air quality and fuel 

consumption benefits. We are finalizing standards based on the composite Heavy-duty

FTP cycle for engines used in vocational vehicles reflecting these vehicles’ primary use 

in transient operating conditions typified by frequent accelerations and decelerations as 

well as some steady cruise conditions as represented on the Heavy-duty FTP. The 

primary reason the agencies are finalizing two separate diesel engine standards – one for 

diesel engines used in tractors and the other for diesel engines used in vocational vehicles 

-- is to encourage engine manufacturers to install engine technologies appropriate to the 

intended use of the engine with the vehicle. The current non-GHG emissions engine test 

procedures also require the development of regeneration emission rates and frequency

factors to account for the emission changes during a regeneration event (40 CFR 86.004-

28). EPA and NHTSA proposed not to include these emissions from the calculation of 

the compliance levels over the defined test procedures. Cummins and Daimler supported 

and stated sufficient incentives already exist for manufacturers to limit regeneration 

frequency. Conversely, Volvo opposed the omission of IRAF requirements for CO2

emissions because emissions from regeneration can be a significant portion of the 

expected improvement and a significant variable between manufacturers

For the proposal, we considered including regeneration in the estimate of fuel 

consumption and GHG emissions and decided not to do so for two reasons. First, EPA’s 

existing criteria emission regulations already provide a strong motivation to engine 

manufacturers to reduce the frequency and duration of infrequent regeneration events. 

The very stringent 2010 NOX emission standards cannot be met by engine designs that 

lead to frequent and extend regeneration events. Hence, we believe engine manufacturers 

are already reducing regeneration emissions to the greatest degree possible. In addition 

to believing that regenerations are already controlled to the extent technologically 

possible, we believe that attempting to include regeneration emissions in the standard 

setting could lead to an inadvertently lax emissions standard. In order to include 

regeneration and set appropriate standards, EPA and NHTSA would have needed to 

project the regeneration frequency and duration of future engine designs in the time 

frame of this program. Such a projection would be inherently difficult to make and quite 

likely would underestimate the progress engine manufacturers will make in reducing 

infrequent regenerations. If we underestimated that progress, we would effectively be 

setting a more lax set of standards than otherwise would be expected. Hence in setting a 
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standard including regeneration emissions we faced the real possibility that we would 

achieve less effective CO2 emissions control and fuel consumption reductions than we 

will achieve by not including regeneration emissions. Therefore, the agencies are 

finalizing an approach as proposed which does not include the regenerative emissions. 

(e) Hybrid Powertrain Technology

Although the final vocational vehicle standards are not premised on use of hybrid 

powertrains, certain vocational vehicle applications may be suitable candidates for use of 

hybrids due to the greater frequency of stop-and-go urban operation and their use of 

power take-off (PTO) systems. Examples are vocational vehicles used predominantly in 

stop-start urban driving (e.g., delivery trucks). As an incentive, the agencies are 

finalizing to provide credits for the use of hybrid powertrain technology as described in 

Section IV. Under the advanced technology credit provisions, credits generated by use of 

hybrid powertrains could be used to meet any of the heavy-duty standards, and are not 

restricted to the averaging set generating the credit, unlike the other credit provisions in 

the final rules. The agencies are finalizing that any credits generated using such 

advanced technologies could be applied to any heavy-duty vehicle or engine, and not be 

limited to the averaging set generating the credit. Section IV below also details the final 

approach to account for the use of a hybrid powertrain when evaluating compliance with 

the vehicle standard. In general, manufacturers can derive the fuel consumption and CO2

emissions reductions based on comparative test results using the final chassis testing 

procedures. 

(3) Summary of Final Flexibility and Credit Provisions

EPA and NHTSA are finalizing four flexibility provisions specifically for heavyduty vocational vehicle and engine manufacturers, as discussed in Section IV below. 

These are an averaging, banking and trading program for emissions and fuel consumption 

credits, as well as provisions for early credits, advanced technology credits, and credits 

for innovative vehicle or engine technologies which are not included as inputs to the 

GEM or are not demonstrated on the engine FTP test cycle. With the exception of the 

advanced technology credits, credits generated under these provisions can only be used 

within the same averaging set which generated the credit (for example, credits generated 

by HHD vocational vehicles can only be used by HHD vehicles). EPA is also adopting a 

temporary provision whereby N2O emission credits can be used to comply with the CO2

emissions standard, as described in Section IV below.

(4) Deferral of Standards for Small Chassis Manufacturing Business and 

Small Business Engine Companies

EPA and NHTSA are finalizing an approach to defer greenhouse gas emissions 

and fuel consumption standards from small vocational vehicle chassis manufacturers

meeting the SBA size criteria of a small business as described in 13 CFR 121.201 (see 40 

CFR 1036.150 and 1037.150). The agencies will instead consider appropriate GHG and 

fuel consumption standards for these entities as part of a future regulatory action. This 
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includes both U.S.-based and foreign small volume heavy-duty truck and engine 

manufacturers.

The agencies have identified ten chassis entities that appear to fit the SBA size 

criterion of a small business.169 The agencies estimate that these small entities comprise 

less than 0.5 percent of the total heavy-duty vocational vehicle market in the United 

States based on Polk Registration Data from 2003 through 2007,170 and therefore that the 

exemption will have a negligible impact on the GHG emissions and fuel consumption 

improvements from the final standards. 

EPA and NHTSA have also identified three engine manufacturing entities that 

appear to fit the SBA size criteria of a small business based on company information 

included in Hoover’s.171 Based on 2008 and 2009 model year engine certification data 

submitted to EPA for non-GHG emissions standards, the agencies estimate that these 

small entities comprise less than 0.1 percent of the total heavy-duty engine sales in the 

United States. The final exemption from the standards established under this rulemaking 

would have a negligible impact on the GHG emissions and fuel consumption reductions 

otherwise due to the standards. 

To ensure that the agencies are aware of which companies would be exempt, we 

are finalizing as proposed to require that such entities submit a declaration to EPA and 

NHTSA containing a detailed written description of how that manufacturer qualifies as a 

small entity under the provisions of 13 CFR 121.201, as described in Section V below. 

E. Other Standards 

In addition to finalizing CO2 emission standards for heavy-duty vehicles and 

engines, EPA is also finalizing separate standards for N2O and CH4 emissions.172 

NHTSA is not finalizing comparable separate standards for these GHGs because they are 

not directly related to fuel consumption in the same way that CO2 is, and NHTSA’s 

authority under EISA exclusively relates to fuel efficiency. N2O and CH4 are important 

GHGs that contribute to global warming, more so than CO2 for the same amount of 

emissions due to their high Global Warming Potential (GWP).173 EPA is finalizing N2O 

and CH4 standards which apply to HD pickup trucks and vans as well as to all heavy-duty 

 

169 The agencies have identified Lodal, Indiana Phoenix, Autocar LLC, HME, Giradin, Azure Dynamics, 

DesignLine International, Ebus, Krystal Koach, and Millenium Transit Services LLC as potential small 

business chassis manufacturers.

170 M.J. Bradley. Heavy-duty Vehicle Market Analysis. May 2009.

171 The agencies have identified Baytech Corporation, Clean Fuels USA, and BAF Technologies, Inc. as 

three potential small businesses.

172 NHTSA's statutory responsibilities relating to reducing fuel consumption are directly related to reducing 

CO2 emissions, but not to the control of other GHGs.

173 The global warming potentials (GWP) used in this rule are consistent with the 2007 Intergovernmental 

Panel on Climate Change (IPCC) Fourth Assessment Report (AR4). At this time, the 1996 IPCC Second 

Assessment Report (SAR) GWP values are used in the official U.S. greenhouse gas inventory submission 

to the United Nations Framework Convention on Climate Change (per the reporting requirements under 

that international convention). N2O has a GWP of 298 and CH4 has a GWP of 25 according to the 2007 

IPCC AR4.
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engines. EPA is not finalizing N2O and CH4 standards for the Class 7 and 8 tractor or 

Class 2b-8 chassis manufacturers because these emissions would be controlled through 

the engine program.

EPA requested comment on possible alternative CO2 equivalent approaches to 

provide near-term flexibility for 2012-14 MY light-duty vehicles. As described below, 

EPA is finalizing alternative provisions allowing manufacturers to use CO2 credits, on a 

CO2-equivalent (CO2eq) basis, to meet the N2O and CH4 standards, which is consistent 

with many commenters’ preferred approach. 

Almost universally across current engine designs, both gasoline- and dieselfueled, N2O and CH4 emissions are relatively low today and EPA does not believe it 

would be appropriate or feasible to require reductions from the levels of current gasoline 

and diesel engines. This is because for the most part, the same hardware and controls 

used by heavy-duty engines and vehicles that have been optimized for non-methane

hydrocarbon (NMHC) and NOX control indirectly result in highly effective control of 

N2O and CH4. Additionally, unlike criteria pollutants, specific technologies beyond those 

presently implemented in heavy-duty vehicles to meet existing emission requirements 

have not surfaced that specifically target reductions in N2O or CH4. Because of this, 

reductions in N2O or CH4 beyond current levels in most heavy-duty applications would 

occur through the same mechanisms that result in NMHC and NOX reductions and would 

likely result in an increase in the overall stringency of the criteria pollutant emission 

standards. Nevertheless, it is important that future engine technologies or fuels not 

currently researched do not result in increases in these emissions, and this is the intent of 

the final “cap” standards. The final standards would primarily function to cap emissions 

at today’s levels to ensure that manufacturers maintain effective N2O and CH4 emissions 

controls currently used should they choose a different technology path from what is 

currently used to control NMHC and NOX but also largely successful methods for 

controlling N2O and CH4. As discussed below, some technologies that manufacturers 

may adopt for reasons other than reducing fuel consumption or GHG emissions could 

increase N2O and CH4 emissions if manufacturers do not address these emissions in their 

overall engine and aftertreatment design and development plans. Manufacturers will be 

able to design and develop the engines and aftertreatment to avoid such emissions 

increases through appropriate emission control technology selections like those already

used and available today. Because EPA believes that these standards can be capped at 

the same level, regardless of type of HD engine involved, the following discussion relates 

to all types of HD engines regardless of the vehicles in which such engines are ultimately 

used. In addition, since these standards are designed to cap current emissions, EPA is 

finalizing the same standards for all of the model years to which the rules apply.

EPA believes that the final N2O and CH4 cap standards will accomplish the 

primary goal of deterring increases in these emissions as engine and aftertreatment 

technologies evolve because manufacturers will continue to target current or lower N2O 

and CH4 levels in order to maintain typical compliance margins. While the cap standards 

are set at levels that are higher than current average emission levels, the control 

technologies used today are highly effective and there is no reason to believe that 

emissions will slip to levels close to the cap, particularly considering compliance margin 
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targets. The caps will protect against significant increases in emissions due to new or 

poorly implemented technologies. However, we also believe that an alternative 

compliance approach that allows manufacturers to convert these emissions to CO2eq 

emission values and combine them with CO2 into a single compliance value would also 

be appropriate, so long as it did not undermine the stringency of the CO2 standard. As 

described below, EPA is finalizing that such an alternative compliance approach be 

available to manufacturers to provide certain flexibilities for different technologies.

EPA requested comments in the NPRM on the approach to regulating N2O and 

CH4 emissions including the appropriateness of “cap” standards, the technical bases for 

the levels of the final N2O and CH4 standards, the final test procedures, and the final 

timing for the standards. In addition, EPA requested any additional emissions data on 

N2O and CH4 from current technology engines. We solicited additional data, and 

especially data for in-use vehicles and engines that would help to better characterize 

changes in emissions of these pollutants throughout their useful lives, for both gasoline 

and diesel applications. As is typical for EPA emissions standards, we are finalizing that 

manufacturers should establish deterioration factors to ensure compliance throughout the 

useful life. We are not at this time aware of deterioration mechanisms for N2O and CH4

that would result in large deterioration factors, but neither do we believe enough is 

known about these mechanisms to justify finalizing assigned factors corresponding to no 

deterioration, as we are finalizing for CO2, or for that matter to any predetermined level. 

In addition to N2O and CH4 standards, this section also discusses air conditioning- related 

provisions and EPA provisions to extend certification requirements to all-electric HD 

vehicles and vehicles and engines designed to run on ethanol fuel.

(1) What is EPA’s Approach to Controlling N2O?

N2O is a global warming gas with a GWP of 298. It accounts for about 0.3% of 

the current greenhouse gas emissions from heavy-duty trucks.174 

N2O is emitted from gasoline and diesel vehicles mainly during specific catalyst 

temperature conditions conducive to N2O formation. Specifically, N2O can be generated 

during periods of emission hardware warm-up when rising catalyst temperatures pass 

through the temperature window when N2O formation potential is possible. For current 

heavy-duty gasoline engines with conventional three-way catalyst technology, N2O is not

generally produced in significant amounts because the time the catalyst spends at the 

critical temperatures during warm-up is short. This is largely due to the need to quickly

reach the higher temperatures necessary for high catalyst efficiency to achieve emission 

compliance of criteria pollutants. N2O formation is generally only a concern with diesel 

and potentially with future gasoline lean-burn engines with compromised NOX emissions 

control systems. If the risk for N2O formation is not factored into the design of the 

controls, these systems can but need not be designed in a way that emphasizes efficient 

NOX control while allowing the formation of significant quantities of N2O. However, 

these future advanced gasoline and diesel technologies do not inherently require N2O 

formation to properly control NOX. Pathways exist today that meet criteria emission 

 

174 Value adapted from “Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2007. April 2009.
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standards that would not compromise N2O emissions in future systems as observed in 

current production engine and vehicle testing175 which would also work for future diesel 

and gasoline technologies. Manufacturers would need to use appropriate technologies and 

temperature controls during future development programs with the objective to optimize 

for both NOX and N2O control. Therefore, future designs and controls at reducing criteria 

emissions would need to take into account the balance of reducing these emissions with 

the different control approaches while also preventing inadvertent N2O formation, much 

like the path taken in current heavy-duty compliant engines and vehicles. Alternatively, 

manufacturers who find technologies that reduce criteria or CO2 emissions but see 

increases N2O emissions beyond the cap could choose to offset N2O emissions with 

reduction in CO2 as allowed in the CO2eq option discussed in Section II.E.3.

EPA is finalizing an N2O emission standard that we believe would be met by most 

current-technology gasoline and diesel vehicles at essentially no cost to the vehicle, 

though the agency is accounting for additional N2O measurement equipment costs. EPA 

believes that heavy-duty emission standards since 2008 model year, specifically the very

stringent NOX standards for both engine and chassis certified engines, directly result in 

stringent N2O control. It is believed that the current emission control technologies used to 

meet the stringent NOX standards achieve the maximum feasible reductions and that no 

additional technologies are recognized that would result in additional N2O reductions. As 

noted, N2O formation in current catalyst systems occurs, but their emission levels are 

inherently low, because the time the catalyst spends at the critical temperatures during 

warm-up when N2O can form is short. At the same time, we believe that the standard 

would ensure that the design of advanced NOX control systems for future diesel and leanburn gasoline vehicles would control N2O emission levels. While current NOX control 

approaches used on current heavy-duty diesel vehicles do not compromise N2O emissions 

and actually result in N2O control, we believe that the standards would discourage any 

new emission control designs for diesels or lean-burn gasoline vehicles that achieve 

criteria emissions compliance at the cost of increased N2O emissions. Thus, the standard 

would cap N2O emission levels, with the expectation that current gasoline and diesel 

vehicle control approaches that comply with heavy-duty vehicle emission standards for 

NOX would not increase their emission levels, and that the cap would ensure that future 

diesel and lean-burn gasoline vehicles with advanced NOX controls would appropriately 

control their emissions of N2O. 

(a) Heavy-Duty Pickup Truck and Van N2O Exhaust Emission Standard

EPA is finalizing the proposed per-vehicle N2O emission standard of 0.05 g/mi, 

measured over the Light-duty FTP and HFET drive cycles. Similar to the CO2 standard 

approach, the N2O emission level of a vehicle would be a composite of the Light-duty 

FTP and HFET cycles with the same 55 percent city weighting and 45 percent highway

weighting. The standard would become effective in model year 2014 for all HD pickups 

and vans that are subject to the CO2 emission requirements. Averaging between vehicles 

would not be allowed. The standard is designed to prevent increases in N2O emissions 

from current levels, i.e., a no-backsliding standard. 

 

175Memorandum “N2O Data from EPA Heavy-Duty Testing” 
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The N2O standard level is approximately two times the average N2O level of 

current gasoline and diesel heavy-duty trucks that meet the NOX standards effective since 

2008 model year.176 Manufacturers typically use design targets for NOX emission levels 

at approximately 50 percent of the standard, to account for in-use emissions deterioration 

and normal testing and production variability, and we expect manufacturers to utilize a 

similar approach for N2O emission compliance. We are not adopting a more stringent 

standard for current gasoline and diesel vehicles because the stringent heavy-duty NOX

standards already result in significant N2O control, and we do not expect current N2O

levels to rise for these vehicles particularly with expected manufacturer compliance 

margins.

Diesel heavy-duty pickup trucks and vans with advanced emission control 

technology are in the early stages of development and commercialization. As this 

segment of the vehicle market develops, the final N2O standard would require 

manufacturers to incorporate control strategies that minimize N2O formation. Available 

approaches include using electronic controls to limit catalyst conditions that might favor 

N2O formation and considering different catalyst formulations. While some of these 

approaches may have associated costs, EPA believes that they will be small compared to 

the overall costs of the advanced NOX control technologies already required to meet 

heavy-duty standards.

The light-duty GHG rule requires that manufacturers begin testing for N2O by

2015 model year. The manufacturers of complete pickup trucks and vans (Ford, General 

Motors, and Chrysler) are already impacted by the light-duty GHG rule and will therefore 

have this equipment and capability in place for the timing of this rulemaking. 

Overall, we believe that manufacturers of HD pickups and vans (both gasoline 

and diesel) would meet the standard without implementing any significantly new 

technologies, only further refinement of their existing controls, and we do not expect 

there to be any significant costs associated with this standard. 

(b) Heavy-duty Engine N2O Exhaust Emission Standard

EPA proposed a per engine N2O emissions standard of 0.05 g/bhp-hr for heavyduty engines, but is finalizing a standard of 0.10 g/bhp-hr based on additional data 

submitted to the agency which better represents the full range of current diesel and 

gasoline engine performance. The final N2O standard becomes effective in 2014 model 

year for diesel engines, as proposed. However, EPA is finalizing N2O standards for 

gasoline engines that become effective in 2016 model year to align with the first year of 

the CO2 gasoline engine standards. Without this alignment, manufacturers would not 

have any flexibility, such as CO2eq credits, in meeting the N20 cap and therefore would 

not have any recourse to comply if an engine’s N2O emissions were above the standard. 

The standard remains the same over the useful life of the engine. The N2O emissions 

would be measured over the composite Heavy-duty FTP cycle because it is believed that 

this cycle poses the highest risk for N2O formation versus the additional heavy-duty 

 

176 Memorandum “N2O Data from EPA Heavy-Duty Testing.”
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compliance cycles. The agencies received comments from industry suggesting that the 

N2O and CH4 emissions be evaluated over the same test cycle required for CO2 emissions 

compliance. In other words, the commenters wanted to have the N2O emissions 

measured over the SET for engines installed in tractors. The agencies are not adopting 

this approach for the final action because we do not have sufficient data to set the 

appropriate N2O level using the SET. The agencies are not requiring any additional 

burden by requiring the measurement to be conducted over the Heavy-Duty FTP cycle 

because it is already required for criteria emissions. Averaging of N2O emissions 

between HD engines will not be allowed. The standard is designed to prevent increases in 

N2O emissions from current levels, i.e., a no-backsliding standard.

The proposed N2O level was twice the average N2O level of primarily pre-2010 

model year diesel engines as demonstrated in the ACES Study and in EPA’s testing of 

two additional engines with selective catalytic reduction aftertreatement systems.177

Manufacturers typically use design targets for NOX emission levels of about 50 percent of 

the standard, to account for in-use emissions deterioration and normal testing and 

production variability, and manufacturers are expected to utilize a similar approach for 

N2O emission compliance. 

EPA sought comment about deterioration factors for N2O emissions. See 75 FR 

74208. Industry stakeholders recommended that the agency define a DF of zero. While 

we believe it is also possible that N2O emissions will not deteriorate in use, very little 

data exist for aged engines and vehicles. Therefore, the value we are assigning is 

conservative, specifically additive DF of 0.02 g/bhp-hr. While the value is conservative, 

it is small enough to allow compliance for all engines except those very close to the 

standards. For engines too close to the standard to use the assigned DFs, the 

manufacturers would need to demonstrate via engineering analysis that deterioration is 

less than assigned DF.

EPA sought additional data on the level of the proposed N2O level of 0.05 g/bhphr. See 75 FR 74208. The agency received additional data of 2010 model year engines 

from the Engine Manufacturers Association.178 The agencies reanalyzed a new data set, 

as shown in Table II-22, to derive the final N2O standard of 0.10 g/bhp-hr with a defined 

deterioration factor of 0.02 g/bhp-hr. 

 

177 Coordinating Research Council Report: ACES Phase 1 of the Advanced Collaborative Emissions Study, 

2009.(This study included detailed chemical characterization of exhaust species emitted from four 2007 

model year heavy heavy diesel engines)

178 Engine Manufacturers Association. EMA N2O Email 03_22_2011. See Docket EPA-HQ-OAR-2010-

0162.
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Table II-22: N2O Data Analysis

Engine Family Rated Power 

(HP)

Composite FTP 

Cycle N2O Result 

(g/bhp-hr)

EPA Data of 2007 Engine with SCR 0.042

EPA Data of 2010 Production Intent 

Engine

0.037

A 450 0.0181

A 600 0.0151

B 360 0.0326

C 380 0.0353

D 560 0.0433

D 455 0.0524

E 600 0.0437

F 500 0.0782

G 483 0.1127

H 385 0.0444

H 385 0.0301

H 385 0.0283

J 380 0.0317

Mean 0.043

2 * Mean 0.09

Engine emissions regulations do not currently require testing for N2O. The 

Mandatory GHG Reporting final rule requires reporting of N2O and requires that 

manufacturers either measure N2O or use a compliance statement based on good 

engineering judgment in lieu of direct N2O measurement (74 FR 56260, October 30, 

2009). The light-duty GHG final rule allows manufacturers to provide a compliance 

statement based on good engineering judgment through the 2014 model year, but requires 

measurement beginning in 2015 model year (75 FR 25324, May 7, 2010). EPA is 

finalizing a consistent approach for heavy-duty engine manufacturers which allows them 

to delay direct measurement of N2O until the 2015 model year. 

Manufacturers without the capability to measure N2O by the 2015 model year 

would need to acquire and install appropriate measurement equipment in response to this 

final program. EPA has established four separate N2O measurement methods, all of 

which are commercially available today. EPA expects that most manufacturers would 

use either photo-acoustic measurement equipment for stand-alone, existing FTIR 

instrumentation at a cost of $50,000 per unit or upgrade existing emission measurement 

systems with NDIR analyzers for $25,000 per test cell. 

Overall, EPA believes that manufacturers of heavy-duty engines, both gasoline 

and diesel, would meet the final standard without implementing any new technologies, 

and beyond relatively small facilities costs for any company that still needs to acquire and 
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install N2O measurement equipment, EPA does not project that manufacturers would 

incur significant costs associated with this final N2O standard. 

EPA is not adopting any vehicle-level N2O standards for heavy-duty vocational 

vehicles and combination tractors. The N2O emissions would be controlled through the 

heavy-duty engine portion of the program. The only requirement of those vehicle 

manufacturers to comply with the N2O requirements is to install a certified engine.

(2) What is EPA’s Approach to Controlling CH4?

CH4 is greenhouse gas with a GWP of 25. It accounts for about 0.03 percent of 

the greenhouse gases from heavy-duty trucks.179

EPA is finalizing a standard that would cap CH4 emission levels, with the 

expectation that current heavy-duty vehicles and engines meeting the heavy-duty

emission standards would not increase their levels as explained earlier due to robust 

current controls and manufacturer compliance margin targets. It would ensure that 

emissions would be addressed if in the future there are increases in the use of natural gas 

or any other alternative fuel. EPA believes that current heavy-duty emission standards, 

specifically the NMHC standards for both engine and chassis certified engines directly 

result in stringent CH4 control. It is believed that the current emission control 

technologies used to meet the stringent NMHC standards achieve the maximum feasible 

reductions and that no additional technologies are recognized that would result in 

additional CH4 reductions. The level of the standard would generally be achievable 

through normal emission control methods already required to meet heavy-duty emission 

standards for hydrocarbons and EPA is therefore not attributing any cost to this part of 

the final action. Since CH4 is produced in gasoline and diesel engines similar to other 

hydrocarbon components, controls targeted at reducing overall NMHC levels generally 

also work at reducing CH4 emissions. Therefore, for gasoline and diesel vehicles, the 

heavy-duty hydrocarbon standards will generally prevent increases in CH4 emissions 

levels. CH4 from heavy-duty vehicles is relatively low compared to other GHGs largely 

due to the high effectiveness of the current heavy-duty standards in controlling overall 

HC emissions. 

EPA believes that this level for the standard would be met by current gasoline and 

diesel trucks and vans, and would prevent increases in future CH4 emissions in the event 

that alternative fueled vehicles with high methane emissions, like some past dedicated 

compressed natural gas vehicles, become a significant part of the vehicle fleet. Currently 

EPA does not have separate CH4 standards because, unlike other hydrocarbons, CH4 does 

not contribute significantly to ozone formation.180 However, CH4 emissions levels in the 

gasoline and diesel heavy-duty truck fleet have nevertheless generally been controlled by

the heavy-duty HC emission standards. Even so, without an emission standard for CH4, 

future emission levels of CH4 cannot be guaranteed to remain at current levels as vehicle 

technologies and fuels evolve.

 

179 Value adapted from “Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2007. April 2009.

180 But See Ford Motor Co. v. EPA, 604 F. 2d 685 (D.C. Cir. 1979) (permissible for EPA to regulate CH4

under CAA section 202(b)).
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In recent model years, a small number of heavy-duty trucks and engines were sold 

that were designed for dedicated use of natural gas. While emission control designs on 

these recent dedicated natural gas-fueled vehicles demonstrate CH4 control can be as 

effective as on gasoline or diesel equivalent vehicles, natural gas-fueled vehicles have 

historically generated significantly higher CH4 emissions than gasoline or diesel vehicles. 

This is because the fuel is predominantly methane, and most of the unburned fuel that 

escapes combustion without being oxidized by the catalyst is emitted as methane. 

However, even if these vehicles meet the heavy-duty hydrocarbon standard and appear to 

have effective CH4 control by nature of the hydrocarbon controls, the heavy-duty 

standards do not require CH4 control and therefore some natural gas vehicle 

manufacturers have invested very little effort into methane control. While the final CH4

cap standard should not require any different emission control designs beyond what is 

already required to meet heavy-duty hydrocarbon standards on a dedicated natural gas 

vehicle (i.e., feedback controlled 3-way catalyst), the cap will ensure that systems provide 

robust control of methane much like a gasoline-fueled engine. We are not finalizing more 

stringent CH4 standards because we believe that the controls used to meet current heavyduty hydrocarbon standards should result in effective CH4 control when properly

implemented. Since CH4 is already measured under the current heavy-duty emissions 

regulations (so that it may be subtracted to calculate NMHC), the final standard will not 

result in additional testing costs. 

(a) Heavy-duty Pickup Truck and Van CH4 Standard

EPA is finalizing the proposed CH4 emission standard of 0.05 g/mi as measured 

on the Light-duty FTP and HFET drive cycles, to apply beginning with model year 2014

for HD pickups and vans subject to the CO2 standards. Similar to the CO2 standard 

approach, the CH4 emission level of a vehicle will be a composite of the Light-duty FTP 

and HFET cycles, with the same 55 percent city weighting and 45 percent highway

weighting. 

The level of the standard is approximately two times the average heavy-duty

gasoline and diesel truck and van levels.181 As with N2O, this standard level recognizes 

that manufacturers typically set emissions design targets with a compliance margin of 

approximately 50 percent of the standard. Thus, we believe that the standard should be 

met by current gasoline vehicles with no increase from today’s CH4 levels. Similarly, 

since current diesel vehicles generally have even lower CH4 emissions than gasoline 

vehicles, we believe that diesels will also meet the standard with a larger compliance 

margin resulting in no change in today’s CH4 levels. 

(b) Heavy-duty Engine CH4 Exhaust Emission Standard

EPA is adopting a heavy-duty engine CH4 emission standard of 0.10 g/hp-hr with 

a defined deterioration factor of 0.02 g/bhp-hr as measured on the composite Heavy-duty 

FTP, to apply beginning in model year 2014 for diesel engines and in 2016 model year 

for gasoline engines. EPA is adopting a different CH4 standard than proposed based on 

 

181 Memorandum “CH4 Data from 2010 and 2011 Heavy-Duty Vehicle Certification Tests”.
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additional data submitted to the agency which better represents the full range of current 

diesel and gasoline engine performance. EPA is adopting CH4 standards for gasoline 

engines that become effective in 2016 model year to align with the first year of the 

gasoline engine CO2 standards. Without this alignment, manufacturers would not have 

any flexibility, such as CO2eq credits, in meeting the CH4 cap and therefore would not be 

able to sell any engine with a CH4 level above the standard. The final standard would cap 

CH4 emissions at a level currently achieved by diesel and gasoline heavy-duty engines. 

The level of the standard would generally be achievable through normal emission control 

methods already required to meet 2007 emission standards for NMHC and EPA is 

therefore not attributing any cost to this part of this program (see 40 CFR 86.007-11). 

The level of the final CH4 standard is twice the average CH4 emissions from 

gasoline engines from General Motors in addition to the four diesel engines in the ACES 

study.

182

 As with N2O, this final level recognizes that manufacturers typically set 

emission design targets at about 50 percent of the standard. Thus, EPA believes the final 

standard would be met by current diesel and gasoline engines with little if any

technological improvements. The agency believes a more stringent CH4 standard is not 

necessary due to effective CH4 controls in current heavy-duty technologies, since, as 

discussed above for N2O, EPA believes that the challenge of complying with the CO2

standards should be the primary focus of the manufacturers

CH4 is measured under the current 2007 regulations so that it may be subtracted to 

calculate NMHC. Therefore EPA expects that the final standard would not result in 

additional testing costs. 

EPA is not adopting any vehicle-level CH4 standards for heavy-duty combination

tractors or vocational vehicles in this final action. The CH4 emissions will be controlled 

through the heavy-duty engine portion of the program. The only requirement of these 

truck manufacturers to comply with the CH4 requirements is to install a certified engine.

(3) Use of CO2 Credits

As proposed, if a manufacturer is unable to meet the N2O or CH4 cap standards, 

the EPA program will allow the manufacturer to comply using CO2 credits. In other 

words, a manufacturer could offset any N2O or CH4 emissions above the standard by

taking steps to further reduce CO2. A manufacturer choosing this option would convert 

its measured N2O and CH4 test results that are in excess of the applicable standards into

CO2eq to determine the amount of CO2 credits required. For example, a manufacturer 

would use 25 Mg of positive CO2 credits to offset 1 Mg of negative CH4 credits or use 

298 Mg of positive CO2 credits to offset 1 Mg of negative N2O credits.183 By using the 

Global Warming Potential of N2O and CH4, the approach recognizes the inter-correlation 

of these compounds in impacting global warming and is environmentally neutral for 

demonstrating compliance with the individual emissions caps. Because fuel conversion 

manufacturers certifying under 40 CFR Part 85, subpart F do not participate in ABT 

 

182 Coordinating Research Council Report: ACES Phase 1 of the Advanced Collaborative Emissions Study, 

2009.

183 N2O has a GWP of 298 and CH4 has a GWP of 25 according to the IPCC AR4.
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programs, EPA is finalizing a compliance option for fuel conversion manufacturers to 

comply with the N2O and CH4 standards that is similar to the credit program just 

described above. The compliance option will allow conversion manufacturers, on an 

individual engine family basis, to convert CO2 overcompliance into CO2 equivalents of 

N20 and/or CH4 that can be subtracted from the CH4 and N20 measured values to 

demonstrate compliance with CH4 and/or N20 standards. Other than in the limited case 

of N2O for model years 2014-16, we have not finalized similar provisions allowing 

overcompliance with the N2O or CH4 standards to serve as a means to generate CO2

credits because the CH4 and N2O standards are cap standards representing levels that all 

but the worst vehicles should already be well below. Allowing credit generation against 

such cap standard would provide a windfall credit without any true GHG reduction.

The final NHTSA fuel consumption program will not use CO2eq, as suggested 

above. Measured performance to the NHTSA fuel consumption standards will be based 

on the measurement of CO2 with no adjustment for N2O and/or CH4. For manufacturers 

that use the EPA alternative CO2eq credit, compliance to the EPA CO2 standard will not 

be directly equivalent to compliance with the NHTSA fuel consumption standard.

(4) Amendment to Light-duty Vehicle N2O and CH4 Standards

EPA also requested comment on revising a portion of the light-duty vehicle 

standards for N2O and CH4. 75 FR at 74211. Specifically, EPA requested comments on 

two additional options for manufacturers to comply with N2O and CH4 standards to 

provide additional near-term flexibility. EPA is finalizing one of those options, as 

discussed below. 

For light-duty vehicles, as part of the MY 2012–2016 rulemaking, EPA finalized 

standards for N2O and CH4 which take effect with MY 2012. 75 FR at 25421–24. 

Similar to the heavy-duty standards discussed in Section II.E above, the light-duty

vehicle standards for N2O and CH4 were established to cap emissions and to prevent 

future emissions increases, and were generally not expected to result in the application of 

new technologies or significant costs for the manufacturers for current vehicle designs. 

EPA also finalized an alternative CO2 equivalent standard option, which manufacturers 

may choose to use in lieu of complying with the N2O and CH4 cap standards. The CO2

equivalent standard option allows manufacturers to fold all N2O and CH4 emissions, on a 

CO2eq basis, along with CO2 into their otherwise applicable CO2 emissions standard 

level. For flexible fueled vehicles, the N2O and CH4 standards must be met on both fuels 

(e.g., both gasoline and E–85). 

After the light-duty standards were finalized, manufacturers raised concerns that 

for a few of the vehicle models in their existing fleet they were having difficulty meeting 

the N2O and/or CH4 standards, especially in the early years of the program for a few of 

the vehicle models in their existing fleet. These standards could be problematic in the 

near-term because there is little lead time to implement unplanned redesigns of vehicles 

to meet the standards. In such cases, manufacturers may need to either drop vehicle 

models from their fleet or to comply using the CO2 equivalent alternative. On a CO2eq 

basis, folding in all N2O and CH4 emissions would add 3–4 g/mile or more to a 
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manufacturer’s overall fleet-average CO2 emissions level because the alternative standard 

must be used for the entire fleet, not just for the problem vehicles.184 See 75 FR at 74211. 

This could be especially challenging in the early years of the program for manufacturers 

with little compliance margin because there is very limited lead time to develop strategies 

to address these additional emissions. As stated at proposal, EPA believed this posed a 

legitimate issue of sufficiency of lead time in the short term, as well as an issue of cost, 

since EPA assumed that the N2O and CH4 standards would not result in significant costs 

for existing vehicles. Id. However, EPA expected that manufacturers would be able to 

make technology changes (e.g., calibration or catalyst changes) to the few vehicle models 

not currently meeting the N2O and/or CH4 standards in the course of their planned vehicle 

redesign schedules in order to meet the standards.

Because EPA intended for these standards to be caps with little anticipated nearterm impact on manufacturer’s current product lines, EPA requested comment in the 

heavy-duty vehicle and engine proposal on two approaches to provide additional 

flexibilities in the light-duty vehicle program for meeting the N2O and CH4 standards. 75 

FR at 74211. EPA requested comments on the option of allowing manufacturers to use 

the CO2 equivalent approach for one pollutant but not the other for their fleet—that is, 

allowing a manufacturer to fold in either CH4 or N2O as part of the CO2-equivalent 

standard. For example, if a manufacturer is having trouble complying with the CH4

standard but not the N2O standard, the manufacturer could use the CO2 equivalent option 

including CH4, but choose to comply separately with the applicable N2O cap standard. 

EPA also requested comments on an alternative approach of allowing 

manufacturers to use CO2 credits, on a CO2 equivalent basis, to offset N2O and CH4

emissions above the applicable standard. This is similar to the approach proposed and 

being finalized for heavy-duty vehicles as discussed above in Section II.E. EPA 

requested comments on allowing the additional flexibility in the light-duty program for 

MYs 2012–2014 to help manufacturers address any near-term issues that they may have 

with the N2O and CH4 standards.

Commenters providing comment on this issue supported additional flexibility for 

manufacturers, and manufacturers specifically supported the heavy-duty vehicle approach 

of allowing CO2 credits on a CO2 equivalent basis to be used to meet the CH4 and N2O 

standards. The Alliance of Automobile Manufacturers and the American Automotive 

Policy Council commented that the proposed heavy-duty approach represented a 

significant improvement over the approach adopted for light-duty vehicles. 

Manufacturers support de-linking N2O and CH4, and commented that the formation of the 

pollutants do not necessarily trend together. Manufacturers also commented that a deficit 

against the N2O or CH4 cap would be required to be covered with CO2 credits for that 

model, but the approach does not “punish” manufacturers for using a specific technology 

(which could provide CO2 benefits, e.g., diesel, CNG, etc.) by requiring manufacturers to 

use the CO2-equivalent approach for their entire fleet. The Natural Gas Vehicle Interests 

 

184 0.030 g/mile CH4 multiplied by a GWP of 25 plus 0.010 g/mile N2O multiplied by a GWP of 298 results 

in a combined 3.7 g/mile CO2-equivalent value. Manufacturers using the default N2O value of 0.10 g/mile 

prior to MY 2015 in lieu of measuring N2O would fold in the entire 0.010 g/mile on a CO2-equivalent 

basis, or about 3 g/mile under the CO2-equivalent option.
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also supported allowing the use of CO2 credits on a CO2-equivalent basis for compliance 

with CH4 standards and urged providing this type of flexibility on a permanent basis. The 

Institute for Policy Integrity also submitted comments supportive of providing additional 

flexibility to manufacturers as long as it does not undermine standard stringency. This 

commenter was supportive of either approach discussed at proposal.185

Manufacturers supported not only adopting the aspects of the heavy-duty 

approach noted above, but the entire heavy-duty vehicle approach, including two aspects 

of the program not contemplated in EPA’s request for comments. First, manufacturers 

commented that EPA incorrectly characterizes the light-duty vehicle issues with CH4 and 

N2O as short-term or early lead time issues. For the reasons discussed above, 

manufacturers believe the changes should be made permanent, for the entire 2012-2016 

light-duty rulemaking period and, indeed, in any subsequent rules for the light-duty

vehicle sector. Second, manufacturers commented that N2O and CH4 should be measured 

on the combined 55/45 weighting of the FTP and highway cycles, respectively, as these 

cycles are the yardstick for fuel economy and CO2 measurement. Manufacturers 

commented that there should not be a disconnect between the light-duty and heavy-duty 

vehicle programs.

EPA continues to believe that it is appropriate to provide additional flexibility to 

manufacturers to meet the N2O and CH4 standards. EPA is thus finalizing provisions 

allowing manufacturers to use CO2 credits, on a CO2-equivalent basis, to meet the N2O 

and CH4 standards, which is consistent with many commenters’ preferred approach. 

Manufacturers will have the option of using CO2 credits to meet N2O and CH4 standards 

on a test group basis as needed for MYs 2012-2016. Because fuel conversion 

manufacturers certifying under 40 CFR Part 85, subpart F do not participate in ABT 

programs, EPA is finalizing a compliance option for fuel conversion manufacturers to 

comply with the N2O and CH4 standards similar to the credit option just described above. 

The compliance option will allow conversion manufacturers, on an individual test group 

basis, to convert CO2 overcompliance into CO2 equivalents of N20 and/or CH4 that can be 

subtracted from the CH4 and N20 measured values to demonstrate compliance with CH4

and/or N20 standards.

In EPA’s request for comments, EPA discussed the new flexibility as being 

needed to address lead time issues for MYs 2012-2014. EPA understands that 

manufacturers are now making technology decisions for beyond MY 2014 and that some 

technologies such as FFVs may have difficulty meeting the CH4 and N2O standards, 

presenting manufacturers with difficult decisions of absorbing the 3-4 g/mile CO2-

equivalent emissions fleet wide, making significant investments in existing vehicle 

 

185 The Institute for Policy Integrity questioned whether EPA had provided adequate notice of the proposal, 

given that it appeared in the proposed GHG rules for heavy duty vehicles. EPA provided notice not only in 

the preamble, but in the summary of action appearing on the first page of the Federal Register notice (“EPA 

is also requesting comment on possible alternative CO2-equivalent approaches for model year 2012-14 

light-duty vehicles”). 75 FR at 74152. This is ample notice (demonstrated as well by the comments 

received on the issue, including from the Institute).
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technologies, or curtailing the use of certain technologies.186 The CH4 standard, in 

particular, could prove challenging for FFVs because exhaust temperatures are lower on 

E-85 and CH4 is more difficult to convert over the catalyst. EPA’s initial estimate that 

these issues could be resolved without disrupting product plans by MY 2015 appears to 

be overly optimistic, and therefore EPA is extending the flexibility through model year 

2016. This change helps ensure that the CH4 and N2O standards will not be an obstacle 

for the use of FFVs or other technologies in this time frame, and at the same time, assure 

that overall fleet average GHG emissions will remain at the same level as under the main 

standards.

In response to comments from manufacturers and from the Natural Gas Vehicle 

Interests that the changes to the program make sense and should be made on a permanent 

basis (i.e. for model years after 2016), EPA is extending this flexibility through MY 2016 

as discussed above, but we believe it is premature to decide here whether or not these 

changes should be permanent. EPA may consider this issue further in the context of new 

standards for MYs 2017-2025 in the planned future light-duty vehicle rulemaking. With 

regard to comments on changing the test procedures over which N2O and CH4 emissions 

are measured to determine compliance with the standards, the level of the standards and 

the test procedures go hand-in-hand and must be considered together. Weighting the 

highway test result with the city test result in the emissions measurement would in most 

cases reduce the overall emissions levels for determining compliance with the standards, 

and would thereby, in effect make the standards less stringent. This appears to be 

inappropriate. In addition, EPA did not request comments on changing the level of the 

N2O and CH4 standards or the test procedures and it is inappropriate to amend the 

standards for that reason as well.

(5) EPA’s Final Standards for Direct Emissions from Air Conditioning

Air conditioning systems contribute to GHG emissions in two ways – direct 

emissions through refrigerant leakage and indirect exhaust emissions due to the extra load 

on the vehicle’s engine to provide power to the air conditioning system. HFC 

refrigerants, which are powerful GHG pollutants, can leak from the A/C system.187 This 

includes the direct leakage of refrigerant as well as the subsequent leakage associate with 

maintenance and servicing, and with disposal at the end of the vehicle’s life.188 The most 

commonly used refrigerant in automotive applications – R134a, has a high GWP of 1430.

189

 Due to the high GWP of R134a, a small leakage of the refrigerant has a much greater 

 

186 “Discussions with Vehicle Manufacturers Regarding the Light-duty Vehicle CH4 and N2O Standards,” 

Memorandum from Christopher Lieske to Docket EPA-HQ-OAR-2010-0162, 

187 The United States has submitted a proposal to the Montreal Protocol which, if adopted, would 

phasedown production and consumption of HFCs.

188 The U.S. EPA has reclamation requirements for refrigerants in place under Title VI of the Clean Air 

Act.

189 The global warming potentials used in this rule are consistent with the 2007 Intergovernmental Panel on 

Climate Change (IPCC) Fourth Assessment Report. At this time, the global warming potential values from 

the 1996 IPCC Second Assessment Report are used in the official U.S. greenhouse gas inventory 

submission to the United Nations Framework Convention on Climate Change(per the reporting 

requirements under that international convention, which were last updated in 2006).
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global warming impact than a similar amount of emissions of CO2 or other mobile source 

GHGs. 

Heavy-duty air conditioning systems today are similar to those used in light-duty

applications. However, differences may exist in terms of cooling capacity (such that 

sleeper cabs have larger cabin volumes than day cabs), system layout (such as the number 

of evaporators), and the durability requirements due to longer vehicle life. However, the 

component technologies and costs to reduce direct HFC emissions are similar between 

the two types of vehicles. 

The quantity of GHG refrigerant emissions from heavy-duty trucks relative to the 

CO2 emissions from driving the vehicle and moving freight is very small. Therefore, a 

credit approach is not appropriate for this segment of vehicles because the value of the 

credit is too small to provide sufficient incentive to utilize feasible and cost-effective air 

conditioning leakage improvements. For the same reason, including air conditioning 

leakage improvements within the main standard would in many instances result in lost 

control opportunities. Therefore, EPA is finalizing the proposed requirement that vehicle 

manufacturers meet a low leakage requirement for all air conditioning systems installed 

in 2014 model year and later trucks, with one exception. The agency is not finalizing 

leakage standards for Class 2b-8 Vocational Vehicles at this time due to the complexity

in the build process and the potential for different entities besides the chassis 

manufacturer to be involved in the air conditioning system production and installation, 

with consequent difficulties in developing a regulatory system. 

For air conditioning systems with a refrigerant capacity greater than 733 grams, 

EPA is finalizing a leakage standard which is a “percent refrigerant leakage per year” to 

assure that high-quality, low-leakage components are used in each air conditioning 

system design. The agency believes that a single “gram of refrigerant leakage per year” 

would not fairly address the variety of air conditioning system designs and layouts found 

in the heavy-duty truck sector. EPA is finalizing a standard of 1.50 percent leakage per 

year for heavy-duty pickup trucks and vans and Class 7 and 8 tractors. The final standard 

was derived from the vehicles with the largest system refrigerant capacity based on the 

Minnesota GHG Reporting database.190 The average percent leakage per year of the 

2010 model year vehicles is 2.7 percent. This final level of reduction is roughly 

comparable to that necessary to generate credits under the light-duty vehicle program. 

See 75 FR 25426-25427. Since refrigerant leakage past the compressor shaft seal is the 

dominant source of leakage in belt-driven air conditioning systems, the agency

recognizes that a single “percent refrigerant leakage per year” is not feasible for systems 

with a refrigerant capacity of 733 grams or lower, as the minimum feasible leakage rate 

does not continue to drop as the capacity or size of the air conditioning system is reduced. 

The fixed leakage from the compressor seal and other system devices results in a 

minimum feasible yearly leakage rate, and further reductions in refrigerant capacity (the 

‘denominator’ in the percent refrigerant leakage calculation) will result in a system which 

cannot meet the 1.50 percent leakage per year standard. EPA does not believe that 

 

190 The Minnesota refrigerant leakage data can be found at 

http://www.pca.state.mn.us/climatechange/mobileair.html#leakdata.
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leakage reducing technologies are available at this time which would allow lower 

capacity systems to meet the percent per year standard, so we are finalizing a maximum 

gram per year leakage standard of 11.0 grams per year for air conditioning systems with a 

refrigerant capacity of 733 grams or lower. EPA defined the standard, as well as the 

refrigerant capacity threshold, by examining the State of Minnesota GHG Reporting 

Database for the yearly leakage rate from 2010 and 2011 model year pickup trucks. In 

the Minnesota data, the average leak rate for the pickup truck category (16 unique model 

and refrigerant capacity combinations) was 13.3 grams per year, with an average capacity

of 654 grams, resulting in an average percent refrigerant leakage per year of 2.0 percent. 

4 of the 16 model/capacity combinations in the reporting data achieved a leak rate 11.0 

grams per year or lower, and this was chosen as the maximum yearly leak rate, as several 

manufacturers have demonstrated that this level of yearly leakage is feasible. To avoid a 

discontinuity between the “percent leakage” and “leak rate” standards – where one 

approach would be more or less stringent, depending on the refrigerant capacity – a 

refrigerant capacity of 733 grams was chosen as a threshold capacity, below which, the 

leak rate approach can be used. EPA believes this approach of having a leak rate 

standard for lower capacity systems and a percent leakage per year standard for higher 

capacity systems will result in reduced refrigerant emissions from all air conditioning 

systems, while still allowing manufacturers the ability to produce low-leak, lower 

capacity systems in vehicles which require them.

Manufacturers can choose to reduce A/C leakage emissions in two ways. First, 

they can utilize leak-tight components. Second, manufacturers can largely eliminate the 

global warming impact of leakage emissions by adopting systems that use an alternative, 

low-Global Warming Potential (GWP) refrigerant. One alternative refrigerant, HFO1234yf, with a GWP of 4, has been approved for use in light-duty passenger vehicles 

under EPA’s Significant New Alternatives Program (SNAP). While the scope of this 

SNAP approval does not include heavy-duty highway vehicles, we expect that those 

interested in using this refrigerant in other sectors will petition EPA for broader approval 

of its use in all mobile air conditioning systems. In addition, the EPA is currently acting 

on a petition to de-list R-134a as an acceptable refrigerant for new, light-duty passenger 

vehicles. The time frame and scale of R-134a de-listing is yet to be determined, but any

phase-down of R-134a use will likely take place after this rulemaking is in effect. Given 

that HFO-1234yf is yet to be approved for heavy-duty vehicles, and that the time frame

for the de-listing of R-134a is not known, EPA believes that a leakage standard for 

heavy-duty vehicles is still appropriate. If future heavy-duty vehicles adopt refrigerants 

other than R-134a, the calculated refrigerant leak rate can be adjusted by multiplying the 

leak rate by the ratio of the GWP of the new refrigerant divided by the GWP of the old 

refrigerant (e.g. for HFO-1234yf replacing R-134a, the calculated leak rate would be 

multiplied by 0.0028, or 4 divided by 1430).

EPA believes that reducing A/C system leakage is both highly cost-effective and 

technologically feasible. The availability of low leakage components is being driven by 

the air conditioning program in the light-duty GHG rule which apply to 2012 model year 

and later vehicles. The cooperative industry and government Improved Mobile Air 

Conditioning program has demonstrated that new-vehicle leakage emissions can be 

reduced by 50 percent by reducing the number and improving the quality of the 
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components, fittings, seals, and hoses of the A/C system.191 All of these technologies are 

already in commercial use and exist on some of today’s systems, and EPA does not 

anticipate any significant improvements in sealing technologies for model years beyond 

2014. However, EPA has recognized some manufacturers utilize an improved 

manufacturing process for air conditioning systems, where a helium leak test is 

performed on 100 percent of all o-ring fittings and connections after final assembly. By

leak testing each fitting, the manufacturer or supplier is verifying the o-ring is not 

damaged during assembly (which is the primary source of leakage from o-ring fittings), 

and when calculating the yearly leak rate for a system, EPA will allow a relative emission 

value equivalent to a ‘seal washer’ can be used in place of the value normally used for an 

o-ring fitting, when 100% helium leak testing is performed on those fittings. While 

further updates to the SAE J2727 standard may be forthcoming (to address new materials 

and measurement methods for permeation through hoses, EPA believes it is appropriate 

to include the helium leak test update to the leakage calculation method at this time. 

Consistent with the light-duty 2012-2016 MY vehicle rule, we are estimating 

costs for leakage control at $18 (2008$) in direct manufacturing costs. Including a low 

complexity indirect cost multiplier (ICM) of 1.14 results in costs of $21 in the 2014 

model year. A/C control technology is considered to be on the flat portion of the learning 

curve, so costs in the 2017 model year will be $19. These costs are applied to all heavyduty pickups and vans, and to all combination tractors. EPA views these costs as 

minimal and the reductions of potent GHGs to be easily feasible and reasonable in the 

lead times provided by the final rules.

EPA is requiring that manufacturers demonstrate improvements in their A/C 

system designs and components through a design-based method. The method for 

calculating A/C leakage is based closely on an industry-consensus leakage scoring 

method, described below. This leakage scoring method is correlated to experimentallymeasured leakage rates from a number of vehicles using the different available A/C 

components. Under the final approach, manufacturers will choose from a menu of A/C 

equipment and components used in their vehicles in order to establish leakage scores, 

which will characterize their A/C system leakage performance and calculate the percent 

leakage per year as this score divided by the system refrigerant capacity. 

Consistent with the light-duty rule, EPA is finalizing a requirement that a 

manufacturer will compare the components of its A/C system with a set of leakagereduction technologies and actions that is based closely on that being developed through 

the Improved Mobile Air Conditioning program and SAE International (as SAE Surface 

Vehicle Standard J2727, “HFC-134a, Mobile Air Conditioning System Refrigerant 

Emission Chart,” August 2008 version). See generally 75 FR 25426. The SAE J2727 

approach was developed from laboratory testing of a variety of A/C related components, 

and EPA believes that the J2727 leakage scoring system generally represents a reasonable 

correlation with average real-world leakage in new vehicles. Like the cooperative 

industry-government program, our final approach will associate each component with a 

specific leakage rate in grams per year that is identical to the values in J2727 and then 

 

191 Team 1-Refrigerant Leakage Reduction: Final Report to Sponsors, SAE, 2007.
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sum together the component leakage values to develop the total A/C system leakage. 

However, in the heavy-duty vehicle program, the total A/C leakage score will then be 

divided by the value of the total refrigerant system capacity to develop a percent leakage 

per year. EPA believes that the design-based approach will result in estimates of likely

leakage emissions reductions that will be comparable to those that would eventually

result from performance-based testing.

EPA is not specifying a specific in-use standard for leakage, as neither test 

procedures nor facilities exist to measure refrigerant leakage from a vehicle’s air 

conditioning system. However, consistent with the light-duty rule, where we require that 

manufacturers attest to the durability of components and systems used to meet the CO2

standards (see 75 FR 25689), we will require that manufacturers of heavy-duty vehicles 

attest to the durability of these systems, and provide an engineering analysis which 

demonstrates component and system durability. 

(6) Indirect Emissions from Air Conditioning

In addition to direct emissions from refrigerant leakage, air conditioning systems 

also create indirect exhaust emissions due to the extra load on the vehicle’s engine to 

provide power to the air conditioning system. These indirect emissions are in the form of 

the additional CO2 emitted from the engine when A/C is being used due to the added 

loads. Unlike direct emissions which tend to be a set annual leak rate not directly tied to 

usage, indirect emissions are fully a function of A/C usage. 

These indirect CO2 emissions are associated with air conditioner efficiency, since 

air conditioners create load on the engine. See 74 FR 49529. However, the agencies are 

not setting air conditioning efficiency standards for vocational vehicles, combination 

tractors, or heavy-duty pickup trucks and vans. The CO2 emissions due to air 

conditioning systems in these heavy-duty vehicles are minimal compared to their overall 

emissions of CO2. For example, EPA conducted modeling of a Class 8 sleeper cab using 

the GEM to evaluate the impact of air conditioning and found that it leads to 

approximately 1 gram of CO2/ton- mile. Therefore, a projected 24 percent improvement 

of the air conditioning system (the level projected in the light-duty GHG rulemaking), 

would only reduce CO2 emissions by less than 0.3 g CO2/ton-mile, or approximately 0.3 

percent of the baseline Class 8 sleeper cab CO2 emissions.

(7) Ethanol-Fueled and Electric Vehicles

Current EPA emissions control regulations explicitly apply to heavy-duty engines 

and vehicles fueled by gasoline, methanol, natural gas and liquefied petroleum gas. For 

multi-fueled vehicles they call for compliance with requirements established for each 

consumed fuel. This contrasts with EPA’s light-duty vehicle regulations that apply to all 

vehicles generally, regardless of fuel type. As we proposed, we are revising the heavyduty vehicle and engine regulations to make them consistent with the light-duty vehicle 

approach, applying standards for all regulated criteria pollutants and GHGs regardless of 

fuel type, including application to all-electric vehicles (EVs). This provision will take 

effect in the 2014 model year, and be optional for manufacturers in earlier model years. 

However, to satisfy the CAA section 202(a)(3) lead time constraints, the provision will
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remain optional for all criteria pollutants through the 2015 model year. Commenters did 

not oppose this change in EPA regulations.

This change primarily affects manufacturers of ethanol-fueled vehicles (designed 

to operate on fuels containing at least 50 percent ethanol) and EVs. Flex-fueled vehicles 

(FFVs) designed to run on both gasoline and fuel blends with high ethanol content will 

also be impacted, as they will need to comply with requirements for operation both on 

gasoline and ethanol.

The regulatory requirements we are finalizing today for certification on ethanol 

follow those already established for methanol, such as certification to NMHC equivalent 

standards and waiver of certain requirements. We expect testing to be done using the 

same E85 test fuel as is used today for light-duty vehicle testing, an 85/15 blend of 

commercially-available ethanol and gasoline vehicle test fuel. EV certification will also 

follow light-duty precedents, primarily calling on manufacturers to exercise good 

engineering judgment in applying the regulatory requirements, but will not be allowed to 

generate NOX or PM credits.

This provision is not expected to result in any significant added burden or cost. It 

is already the practice of HD FFV manufacturers to voluntarily conduct emissions testing 

for these vehicles on E85 and submit the results as part of their certification application, 

along with gasoline test fuel results. No changes in certification fees are being set in 

connection with this provision. We expect that there will be strong incentives for any 

manufacturer seeking to market these vehicles to also want them to be certified: (1) 

uncertified vehicles carry a disincentive to potential purchasers who typically have the 

benefit to the environment as one of their reasons for considering alternative fuels, (2) 

uncertified vehicles are not eligible for the substantial credits they could likely otherwise 

generate, (3) EVs have no tailpipe or evaporative emissions and thus need no added 

hardware to put them in a certifiable configuration, and (4) emissions controls for 

gasoline vehicles and FFVs are also effective on dedicated ethanol-fueled vehicles, and 

thus costly development programs and specialized components will not be needed; in fact 

the highly integrated nature of modern automotive products make the emission control 

systems essential to reliable vehicle performance.

Regarding technological feasibility, as mentioned above, HD FFV manufacturers 

already test on E85 and the resulting data shows that they can meet emissions standards 

on this fuel. Furthermore, there is a substantial body of certification data on light-duty

FFVs (for which testing on ethanol is already a requirement), showing existing emission 

control technology is capable of meeting even the more stringent Tier 2 standards in 

place for light-duty vehicles. 

(8) Correction to 40 CFR 1033.625

In a 2008 final rule that set new locomotive and marine engine standards, EPA 

adopted a provision allowing manufacturers to use a limited number of nonroad engines 

to power switch locomotives provided, among other things, that “the engines were 

certified to standards that are numerically lower than the applicable locomotive standards 
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of this part (1033).” (40 CFR 1033.625(a)). The goal of this provision is to encourage the 

replacement of aging, high-emitting switch locomotives with new switch locomotives 

having very low emissions of PM, NOX, and hydrocarbons. However, this provision 

neglected to consider the fact that preexisting nonroad engine emission standards for CO 

were set at levels that were slightly numerically higher than those for locomotives. The 

applicable switch locomotive CO standard of Part 1033 is 3.2 g/kW-hr (2.4 g/hp-hr), 

while the applicable nonroad engine CO standard is 3.5 g/kW-hr (2.6 g/hp-hr). This is 

the case even for the cleanest final Tier 4 nonroad engines that will phase in starting in 

2014. Thus, nonroad engines cannot be certified to CO standards that are numerically 

lower than the applicable locomotive standards, and the nonroad engine provision is 

rendered practically unusable. This matter was brought to EPA’s attention by affected 

engine manufacturers.192 

As indicated above, EPA believes that allowing certification of new switch 

locomotive engines to nonroad engine standards will greatly reduce emissions from 

switch locomotives, and EPA does not believe the slight difference in CO standards 

should prevent this environmentally beneficial program. EPA is therefore adopting a 

corrective technical amendment in Part 1033. The regulation is being amended at § 

1033.625(a)(2) to add the following italicized text: “The engines were certified to PM, 

NOX, and hydrocarbon standards that are numerically lower than the applicable 

locomotive standards of this part.” This change is a straightforward correction to restore 

the intended usability of the provision and is not expected to have adverse environmental 

impacts, as nonroad engines have CO emissions that are typically well below both the 

nonroad and locomotive emissions standards.

(9) Corrections to 40 CFR part 600

EPA adopted changes to fuel economy labeling requirements on July 6, 2011 (76 

FR 39478). We are making the following corrections to these regulations in 40 CFR part 

600:

 We adopted a requirement to use the specifications of SAE J1711 for fuel 

economy testing related to hybrid-electric vehicles. In this final rule, we are 

extending that requirement to the calculation provisions in §600.114-12. This 

change was inadvertently omitted from the earlier final rule.

 We are correcting an equation in §600.116-12.

 We are removing text describing label content that differs from the sample 

labels that were published with the final rule. The sample labels properly

characterize the intended label content.

(10) Definition of Urban Bus 

EPA is adding a new section 86.012-2 to revise the definition of “urban bus.” 

The new definition will treat engines used in urban buses the same as engines used in any 

 

192 See e-mail correspondence from Timothy A. French, EMA, to Donald Kopinski and Charles Moulis, 

U.S. EPA dated 12/8/10, “Switcher Locomotive Flexibility”, docket# EPA-HQ-OAR-2010-0162.
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other HD vehicle application, relying on the definitions of primary intended service class 

for defining which standards and useful life apply for bus engines. This change is 

necessary to allow for installation of engines other than HHDDE for hybrid bus 

applications.

III. Feasibility Assessments and Conclusions

In this section, NHTSA and EPA discuss several aspects of our joint technical 

analyses. These analyses are common to the development of each agency’s final

standards. Specifically we discuss: the development of the baseline used by each agency

for assessing costs, benefits, and other impacts of the standards, the technologies the 

agencies evaluated and their costs and effectiveness, and the development of the final 

standards based on application of technology in light of the attribute based distinctions 

and related compliance measurement procedures. We also discuss the agencies’ 

consideration of standards that are either more or less stringent than those adopted. 

This program is based on the need to obtain significant oil savings and GHG 

emissions reductions from the transportation sector, and the recognition that there are 

appropriate and cost-effective technologies to achieve such reductions feasibly in the 

model years of this program. The decision on what standard to set is guided by each 

agency’s statutory requirements, and is largely based on the need for reductions, the 

effectiveness of the emissions control technology, the cost and other impacts of 

implementing the technology, and the lead time needed for manufacturers to employ the 

control technology. The availability of technology to achieve reductions and the cost and 

other aspects of this technology are therefore a central focus of this final rulemaking.

CBD submitted several comments on whether NHTSA had met EISA’s mandate 

to set standards “designed to achieve the maximum feasible improvement” and, to that 

end, appropriately considered feasible technologies in setting the stringency level. CBD 

stated that the proposed rule had been improperly limited to currently available 

technology, and that none of the alternatives contained all of the available technology, 

which it argued violated EISA and the CAA. CBD also stated that the phase-in schedule 

violated the technology-forcing intention of EISA, and that the agencies misperceived 

their statutory mandates, arguing that the agencies are required to force technological 

innovation through aggressive standards. 

As demonstrated in the standard-specific discussions later in this section of the 

preamble, the standards adopted in the final program are consistent with section 202 (a) 

of the CAA and section 32902 (k)(2) of EISA With respect to the EPA rules, we note at 

the outset, that CBD’s premise that EPA must adopt “technology-forcing” standards for 

heavy-duty vehicles and engines is wrong. A technology-forcing standard is one that is 

to be based on standards which will be available, rather than technology which is 

presently available. NRDC v. Thomas, 805 F. 2d 410, 429 (D.C. Cir. 1986). Clean Air 

Act provisions requiring “the greatest degree of emission reduction achievable through 

the application of technology which the Administrator determines will be available” are 
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technology-forcing. See e.g. CAA sections 202 (a)(3)(1)193; 213 (a)(3). Section 202(a) 

(1) standards are technology-based, but not technology-forcing, requiring EPA to issue 

standards for a vehicle’s useful life “after providing such period as the Administrator 

finds necessary to permit the development and application of the requisite technology, 

giving appropriate consideration to the cost of compliance within such period.” See 

NACAA v. EPA, 489 F. 3d 1221, 1230 (D.C. Cir. 2007) upholding EPA’s interpretation 

of similar language in CAA section 231 (a) as providing even greater leeway to weigh the 

statutory factors than if the provision were technology-forcing. See generally 74 FR at 

49464-465 (Sept. 28. 2009); 75 FR at 74171. 

Section 202 (a)(1) of course allows EPA to consider application of technologies 

which will be available as well as those presently available, id., and EPA exercised that 

discretion here. For example, as shown below, the agencies carefully considered 

application of hybrid technologies and bottoming cycle technologies for a number of the 

standards. Thus, the critical issue is whether EPA’s choice of technology penetration on 

which the standards are premised is reasonable considering the statutory factors, the key

ones being technology feasibility, technology availability in the 2014-2018 model years 

(i.e. adequacy of lead time), and technology cost and cost-effectiveness. EPA has 

considerable discretion to weigh these factors in a reasonable manner (even for 

provisions which are explicitly technology-forcing, see Sierra Club v. EPA, 325 F. 3d 

374, 378 (D.C. Cir. 2003)), and has done so here.

With respect to EISA, 49 U.S.C. section 32902(k)(2) directs NHTSA to 

“determine in a rulemaking proceeding how to implement a commercial medium- and 

heavy-duty on-highway vehicle and work truck fuel efficiency improvement program 

designed to achieve the maximum feasible improvement,” and “adopt and implement 

appropriate test methods, measurement metrics, fuel economy standards, and compliance 

and enforcement protocols that are appropriate, cost-effective, and technologically 

feasible for commercial medium- and heavy-duty on-highway vehicles and work trucks” 

NHTSA recognizes that Congress intended EPCA (and by extension, EISA, which 

amended it) to be technology-forcing. See Center for Auto Safety v. National Highway 

Traffic Safety Admin., 793 F.2d 1322, 1339 (D.C. Cir. 1986). However, NHTSA believes 

it is important to distinguish between setting “maximum feasible” standards, as 

EPCA/EISA requires, and “maximum technologically feasible” standards, as CBD would 

have NHTSA do. The agency must weigh all of the statutory factors in setting fuel 

efficiency standards, and therefore may not weigh one statutory factor in isolation of 

others. 

Neither EPCA nor EISA define “maximum feasible” in the context of setting fuel 

efficiency or fuel economy standards. Instead, NHTSA is directed to consider and meet

three factors when determining what the maximum feasible standards are –

“appropriateness, cost-effectiveness, and technological feasibility.” 32902(k)(2). These 

factors modify “feasible” in the context of the MD/HD rules beyond a plain meaning of 

 

193 CBD cites the District Court’s opinion in Cent. Valley Chrysler-Jeep Inc. v. Goldstene, 529 F. Supp. 2d 

1151, 1178 (E.D. Cal. 2007) for the proposition thatstandard-setting provisions of Title II of the CAA are 

technology forcing, but the court was citing to the technology-forcing provision section 202 (a)(3)(A)(i), 

which is not the applicable authority here.
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“capable of being done.” See Center for Biological Diversity v. National Highway 

Traffic Safety Admin., 538 F.3d 1172, 1194 (9th Cir. 2008). With respect to the setting of 

standards for light-duty vehicles, EPCA/EISA “gives NHTSA discretion to decide how to 

balance the statutory factors – as long as NHTSA’s balancing does not undermine the 

fundamental purpose of EPCA: energy conservation.” Id. at 1195. Where Congress has 

not directly spoken to a potential issue related to such a balancing, NHTSA’s 

interpretation must be a “reasonable accommodation of conflicting policies... committed 

to the agency’s care by the statute.” Id. (discussing consideration of consumer demand) 

(internal citations omitted). In the context of the agency’s light-duty vehicle authority, it 

was determined that Congress delegated the process for setting the maximum feasible 

standard to NHTSA with broad guidelines concerning the factors that the agency must 

consider. Id. (internal citations omitted) (emphasis in original). We believe that the same 

conclusion should be drawn about the statutory provisions governing the agency’s setting 

of standards for heavy-duty vehicles. Those provisions prescribe statutory factors 

commensurate to, and equally broad as, those prescribed for light-duty. Thus, NHTSA 

believes that it is firmly within our discretion to weigh and balance the factors laid out in 

32902(k) in a way that is technology-forcing, as evidenced by these standards 

promulgated in this final action, but not in a way that requires the application of 

technology which will not be available in the lead time provided by the rules, or which is 

not cost-effective, or is cost-prohibitive, as CBD evidently deems mandated.

As detailed below for each regulatory category, NHTSA has considered the 

appropriateness, cost-effectiveness, and technological feasibility of the standards in 

designing a program to achieve the maximum feasible fuel efficiency improvement. It 

believes that each of those criteria is met.

As described in Section I. F. (2) above, the final standards will remain in effect 

indefinitely at their 2018 or 2019 levels, unless and until the standards are revised. CBD 

maintained that this is a per se violation of EISA, arguing that, by definition, standards 

which are not updated continually and regularly cannot be considered maximum feasible. 

NHTSA would like to clarify that the NPRM specified that the standards would remain 

indefinitely “until amended by a future rulemaking action.” NPRM at 74172. Further, as 

noted above, NHTSA has broad discretion to determine the maximum feasible standards. 

Unlike § 32902(b)(3)(B), which applies to automobiles regulated under light-duty CAFE, 

§ 32902(k) does not specify a maximum number of years that fuel economy standards for 

heavy-duty vehicles will be in place. Consistent with its broad authority to define 

maximum feasible standards, NHTSA interprets its authority as including the discretion 

to define expiration periods where Congress has not otherwise specified. This is 

particularly appropriate for the heavy-duty sector, where fuel efficiency regulation is 

unprecedented. NHTSA believes that it would be unwise to set an expiration period for 

this first rulemaking absent both Congressional direction and a known compelling reason 

for setting a specific date. 

NHTSA believes that the phase-in schedules provide an appropriate balance 

between the technology-forcing purpose of the statute and EISA-mandated considerations 

of economic practicability. NHTSA recognizes, as noted in the case above, that 

balancing each statutory factor in order to set the maximum feasible standards means that 
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the agency must engage in a “reasonable accommodation of conflicting policies.” See

538 F.3d at 1195, supra. Here, the agency has determined that the phase-in schedules are

one such reasonable accommodation. 

 Navistar commented generally that the proposed rule was not technologically

feasible, stating that the proposed standards assume technologies which are not in 

production for all manufacturers. This is not the test for technical feasibility. Under the 

Clean Air Act, EPA needs only to outline a technical path toward compliance with a 

standard, giving plausible reasons for its belief that technology will either be developed 

or applied in the requisite period. NRDC v. EPA, 655 F. 2d 318, 333-34 (D.C. Cir. 

1981). EPA has done so here with respect to the alternative engine standards of 

particular concern to Navistar.194 Similarly, NHTSA has previously interpreted 

“technological feasibility” to mean “whether a particular method of improving fuel 

economy can be available for commercial application in the model year for which a 

standard is being established.’ 74 FR 14196, 14216. NHTSA has further clarified that 

the consideration of technological feasibility “does not mean that the technology must be 

available or in use when a standard is proposed or issued.” Center for Auto Safety v. 

National Highway Traffic Safety Admin., 793 F.2d 1322, 1325 n12 (D.C. Cir. 1986), 

quoting 42 Fed. Reg. 63, 184, 63, 188 (1977). 

Consistent with these previous interpretations, NHTSA believes that a technology

does not necessarily need to be currently available or in use for all regulated parties to be 

“technologically feasible” for this program, as long as it is reasonable to expect, based on 

the evidence before the agency, that the technology will be available in the model year in 

which the relevant standard takes effect. The agencies provide multiple technology

pathways for compliance with a standard, allowing each manufacturer to develop 

technologies which fit their current production and research, and the standards are based 

on fleet penetration rates of those technologies. As discussed below, it is reasonable to 

assume that all the technologies on whose performance the standards are premised will be 

available over the period the standards are in effect.

The Institute for Policy Integrity (IPI) commented that the agencies should 

increase the scope and stringency of the final rule to the point at which net benefits would 

be maximized, citing Executive Orders 12866 and 13563. EOs 12866 and 13563 instruct 

agencies, to the extent permitted by law, to select, among other things, the regulatory

approaches which maximize net benefits. NHTSA agrees with IPI about the applicability

of these EOs and has made every effort to incorporate their guidance in drafting this rule. 

Though IPI agreed that the proposed rule was cost-benefit justified, IPI further 

stated that the agencies must implement an alternative that provides the maximum net 

benefits. The agencies believe that standards that maximized net benefits would be 

beyond the point of technological feasibility for this first phase of the HD National 

Program. The standards already require the maximum feasible fuel efficiency 

improvements for the HD fleet in the 2014-2018 time frame. Thus, even though, the final 

standards are highly cost-effective, and standards that maximized net benefits would 

 

194 See 40 CFR 1036.620
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likely be more stringent than those being promulgated in this final action, NHTSA 

believes that standards that maximized net benefits would not be appropriate or 

technologically feasible in the rulemaking time frame. The Executive Orders cited by IPI 

cannot and do not require an agency to select a regulatory alternative that is inconsistent 

with its statutory obligations. Thus, the standards adopted in the final rules are consistent 

with the agencies’ respective statutory authorities, and are not established at levels which 

are infeasible or cost-ineffective. 

Here, the focus of the standards is on applying fuel efficiency and emissions 

control technology to reduce fuel consumption, CO2 and other greenhouse gases. 

Vehicles combust fuel to generate power that is used to perform two basic functions: 1) 

transport the truck and its payload, and 2) operate various accessories during the 

operation of the truck such as the PTO units. Engine-based technology can reduce fuel 

consumption and CO2 emissions by improving engine efficiency, which increases the 

amount of power produced per unit of fuel consumed. Vehicle-based technology can 

reduce fuel consumption and CO2 emissions by increasing the vehicle efficiency, which

reduces the amount of power demanded from the engine to perform the truck’s primary

functions.

Our technical work has therefore focused on both engine efficiency improvements 

and vehicle efficiency improvements. In addition to fuel delivery, combustion, and 

aftertreatment technology, any aspect of the truck that affects the need for the engine to 

produce power must also be considered. For example, the drag due to aerodynamics and 

the resistance of the tires to rolling both have major impacts on the amount of power 

demanded of the engine while operating the vehicle. 

The large number of possible technologies to consider and the breadth of vehicle 

systems that are affected mean that consideration of the manufacturer’s design and 

production process plays a major role in developing the final standards. Engine and 

vehicle manufacturers typically develop many different models based on a limited 

number of platforms. The platform typically consists of a common engine or truck model 

architecture. For example, a common engine platform may contain the same 

configuration (such as inline), number of cylinders, valvetrain architecture (such as 

overhead valve), cylinder head design, piston design, among other attributes. An engine 

platform may have different calibrations, such as different power ratings, and different 

aftertreatment control strategies, such as exhaust gas recirculation (EGR) or selective 

catalytic reduction (SCR). On the other hand, a common vehicle platform has different 

meanings depending on the market. In the heavy-duty pickup truck market, each truck 

manufacturer usually has only a single pickup truck platform (for example the F series by 

Ford) with common chassis designs and shared body panels, but with variations on load 

capacity of the axles, the cab configuration, tire offerings, and powertrain options. 

Lastly, the combination tractor market has several different platforms and the trucks 

within each platform (such as LoneStar by Navistar) have less commonality. Tractor 

manufacturers will offer several different options for bumpers, mirrors, aerodynamic 

fairing, wheels, and tires, among others. However, some areas such as the overall basic 

aerodynamic design (such as the grill, hood, windshield, and doors) of the tractor are tied 

to tractor platform.
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The platform approach allows for efficient use of design and manufacturing 

resources. Given the very large investment put into designing and producing each truck 

model, manufacturers of heavy-duty pickup trucks and vans typically plan on a major 

redesign for the models every 5 years or more (a key consideration in the choice of the 

five model year duration during which the vehicle standards are phased in). Recently, 

EPA’s non-GHG heavy-duty engine program provided new emissions standards every

three model years. Heavy-duty engine and truck manufacturer product plans typically 

have fallen into three year cycles to reflect this regime. While the recent non-GHG 

emissions standards can be handled generally with redesigns of engines and trucks, a 

complete redesign of a new heavy-duty engine or truck typically occurs on a slower cycle 

and often does not align in time due to the fact that the manufacturer of engines differs 

from the truck manufacturer. At the redesign stage, the manufacturer will upgrade or add 

all of the technology and make most other changes supporting the manufacturer’s plans 

for the next several years, including plans related to emissions, fuel efficiency, and safety 

regulations.

A redesign of either engine or truck platforms often involves a package of 

changes designed to work together to meet the various requirements and plans for the 

model for several model years after the redesign. This often involves significant 

engineering, development, manufacturing, and marketing resources to create a new 

product with multiple new features. In order to leverage this significant upfront 

investment, manufacturers plan vehicle redesigns with several model years of production 

in mind. Vehicle models are not completely static between redesigns as limited changes 

are often incorporated for each model year. This interim process is called a refresh of the 

vehicle and it generally does not allow for major technology changes although more 

minor ones can be done (e.g., small aerodynamic improvements, etc). More major 

technology upgrades that affect multiple systems of the vehicle thus occur at the vehicle 

redesign stage and not in the time period between redesigns.

As discussed below, there are a wide variety of CO2 and fuel consumption 

reducing technologies involving several different systems in the engine and vehicle that 

are available for consideration. Many can involve major changes to the engine or 

vehicle, such as changes to the engine block and cylinder heads or changes in vehicle 

shape to improve aerodynamic efficiency. Incorporation of such technologies during the 

periodic engine, transmission or vehicle redesign process would allow manufacturers to 

develop appropriate packages of technology upgrades that combine technologies in ways 

that work together and fit with the overall goals of the redesign. By synchronizing with 

their multi-year planning process, manufacturers can avoid the large increase in resources 

and costs that would occur if technology had to be added outside of the redesign process. 

We considered redesign cycles both in our costing and in assessing needed the lead time 

required.

As described below, the vast majority of technology on whose performance the 

final standards are predicated is commercially available and already being utilized to a 

limited extent across the heavy-duty fleet. Therefore the majority of the emission and 

fuel consumption reductions which would result from these final rules would result from 

the increased use of these technologies. EPA and NHTSA also believe that these final 
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rules will encourage the development and limited use of more advanced technologies, 

such as advanced aerodynamics and hybrid powertrains in some vocational vehicle

applications. 

In evaluating truck efficiency, NHTSA and EPA have excluded consideration of 

standards which could result in fundamental changes in the engine or vehicle’s 

performance. Put another way, none of the technology pathways underlying the final 

standards involve any alteration in vehicle utility. For example, the agencies did not 

consider approaches that would necessitate reductions in engine power or otherwise limit 

truck performance. The agencies have thus limited the assessment of technical feasibility 

and resultant vehicle cost to technologies which maintain freight utility. Similarly, the 

agencies’ choice of attributes on which to base the standards, and the metrics used to 

measure them, are consciously adopted to preserve the utility of heavy-duty vehicles and 

engines. 

The agencies worked together to determine component costs for each of the 

technologies and build up the costs accordingly. For costs, the agencies considered both 

the direct or “piece” costs and indirect costs of individual components of technologies. 

For the direct costs, the agencies followed a bill of materials approach utilized by the 

agencies in the light-duty 2012-16 MY vehicle rule. A bill of materials, in a general 

sense, is a list of components or sub-systems that make up a system— in this case, an 

item of technology which reduces GHG emissions and fuel consumption. In order to 

determine what a system costs, one of the first steps is to determine its components and 

what they cost. NHTSA and EPA estimated these components and their costs based on a 

number of sources for cost-related information. In general, the direct costs of fuel 

consumption-improving technologies for heavy-duty pickups and vans are consistent 

with those used in the light-duty 2012-2016 MY vehicle rule, except that the agencies 

have scaled up certain costs where appropriate to accommodate the larger size and/or 

loads placed on parts and systems in the heavy-duty classes relative to the light-duty 

classes. For loose heavy-duty engines, the agencies have consulted various studies and 

have exercised engineering judgment when estimating direct costs. For technologies 

expected to be added to vocational vehicles and combination tractors, the agencies have 

again consulted various studies and have used engineering judgment to arrive at direct 

cost estimates. Once costs were determined, they were adjusted to ensure that they were 

all expressed in 2009 dollars using a ratio of gross domestic product deflators for the 

associated calendar years. 

Indirect costs were accounted for using the ICM approach explained in Chapter 2 

of the RIA, rather than using the traditional Retail Price Equivalent (RPE) multiplier 

approach. For the heavy-duty pickup truck and van cost projections in this final action, 

the agencies have used ICMs developed for light-duty vehicles (with the exception that 

here return on capital has been incorporated into the ICMs, where it had not been in the 

light-duty rule) primarily because the manufacturers involved in this segment of the 

heavy-duty market are the same manufacturers that build light-duty trucks. For the Class 

7 and 8 tractor, vocational vehicle, and heavy-duty engine cost projections in this final 

rulemaking, EPA contracted with RTI International to update EPA’s methodology for 

accounting for indirect costs associated with changes in direct manufacturing costs for 
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heavy-duty engine and truck manufacturers.195 In addition to the indirect cost multipliers 

varying by complexity and time frame, there is no reason to expect that the multipliers 

would be the same for engine manufacturers as for truck manufacturers. The report from 

RTI provides a description of the methodology, as well as calculations of new indirect 

cost multipliers. The multipliers used here include a factor of 5 percent of direct costs 

representing the return on capital for heavy-duty engines and truck manufacturers. These 

indirect cost multipliers are intended to be used, along with calculations of direct 

manufacturing costs, to provide improved estimates of the full additional costs associated 

with new technologies. The agencies did not receive any adverse comments related to 

this methodology.

Details of the direct and indirect costs, and all applicable ICMs, are presented in 

Chapter 2 of the RIA. In addition, for details on the ICMs, please refer to the RTI report 

(See Docket ID EPA-HQ-OAR-2010-0162-0283). Importantly, the agencies have 

revised the ICM factors and the way that indirect costs are calculated using the ICMs. As 

a result, the ICM factors are now higher, the indirect costs are higher and, therefore, 

technology costs are higher. The changes made to the ICMs and the indirect cost 

calculations are discussed in Section VIII of this preamble and are detailed in Chapter 2 

of the RIA. 

EPA and NHTSA believe that the emissions reductions called for by the final 

standards are technologically feasible at reasonable costs within the lead time provided 

by the final standards, reflecting our projections of widespread use of commercially 

available technology. Manufacturers may also find additional means to reduce emissions 

and lower fuel consumption beyond the technical approaches we describe here. We 

encourage such innovation through provisions in our flexibility program as discussed in 

Section IV.

The remainder of this section describes the technical feasibility and cost analysis 

in greater detail. Further detail on all of these issues can be found in the joint RIA 

Chapter 2.

A. Class 7-8 Combination Tractor

Class 7 and 8 tractors are used in combination with trailers to transport freight.196

The variation in the design of these tractors and their typical uses drive different 

technology solutions for each regulatory subcategory. The agencies are adopting 

provisions to treat vocational tractors as vocational vehicles instead of as combination 

tractors, as noted in Section II.B. The focus of this section is on the feasibility of the 

standards for combination tractors, not the vocational tractors.

EPA and NHTSA collected information on the cost and effectiveness of fuel 

consumption and CO2 emission reducing technologies from several sources. The primary 

 

195 RTI International. Heavy-duty Truck Retail Price Equivalent and Indirect Cost Multipliers. July 2010.

196 “Tractor” is defined in 49 CFR Part 571.3 to mean “a truck designed primarily for drawing other motor 

vehicles and not so constructed as to carry a load other than a part of the weight of the vehicle and the load 

so drawn.”
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sources of information were the 2010 National Academy of Sciences report of 

Technologies and Approaches to Reducing the Fuel Consumption of Medium- and 

Heavy-Duty Vehicles,197 TIAX’s assessment of technologies to support the NAS panel 

report,198 EPA’s Heavy-duty Lumped Parameter Model199, the analysis conducted by the 

Northeast States Center for a Clean Air Future, International Council on Clean 

Transportation, Southwest Research Institute and TIAX for reducing fuel consumption of 

heavy-duty long haul combination tractors (the NESCCAF/ICCT study),200 and the 

technology cost analysis conducted by ICF for EPA.201 Following on the EISA of 2007, 

the National Research Council appointed a NAS committee to assess technologies for 

improving fuel efficiency of heavy-duty vehicles to support NHTSA’s rulemaking. The 

2010 NAS report assessed current and future technologies for reducing fuel consumption, 

how the technologies could be implemented, and identified the potential cost of such 

technologies. The NAS panel contracted with TIAX to perform an assessment of 

technologies which provide potential fuel consumption reductions in heavy-duty trucks 

and engines and the technologies’ associated capital costs. Similar to the Lumped 

Parameter model which EPA developed to assess the impact and interactions of GHG and 

fuel consumption reducing technologies for light-duty vehicles, EPA developed a new 

version of that model to specifically address the effectiveness and interactions of the final 

pickup truck and light heavy-duty engine technologies. The NESCAFF/ICCT study

assessed technologies available in 2012 through 2017 to reduce CO2 emissions and fuel 

consumption of line haul combination tractors and trailers. Lastly, the ICF report focused 

on the capital, maintenance, and operating costs of technologies currently available to 

reduce CO2 emissions and fuel consumption in heavy-duty engines, combination tractors, 

and vocational vehicles.

(1) What Technologies Did the Agencies Consider to Reduce the CO2

Emissions and Fuel Consumption of Combination Tractors?

Manufacturers can reduce CO2 emissions and fuel consumption of combination 

tractors through use of, among others, engine, aerodynamic, tire, extended idle, and 

weight reduction technologies. The standards in the final rules are premised on use of 

these technologies. The agencies note that SmartWay trucks are available today which 

incorporate the technologies on whose performance the final standards are based. We 

will also discuss other technologies that could potentially be used, such as vehicle speed 

limiters, although we are not basing the final standards on their use for the model years 

covered by this rulemaking, for various reasons discussed below. 

 

197 Committee to Assess Fuel Economy Technologies for Medium- and Heavy-Duty Vehicles; National 

Research Council; Transportation Research Board (2010). Technologies and Approaches to Reducing the 

Fuel Consumption of Medium- and Heavy-Duty Vehicles. (“The NAS Report”) Washington, D.C., The 

National Academies Press. Available electronically from the National Academy Press Website at 

http://www.nap.edu/catalog.php?record_id=12845.

198 TIAX, LLC. “Assessment of Fuel Economy Technologies for Medium- and Heavy-Duty Vehicles,” 

Final Report to National Academy of Sciences, November 19, 2009.

199 U.S. EPA. Heavy-duty Lumped Parameter Model.

200 NESCCAF, ICCT, Southwest Research Institute, and TIAX. Reducing Heavy-Duty Long Haul 

Combination Truck Fuel Consumption and CO2 Emissions. October 2009.

201 ICF International. “Investigation of Costs for Strategies to Reduce Greenhouse Gas Emissions for 

Heavy-Duty On-Road Vehicles.” July 2010. Docket Number EPA-HQ-OAR-2010-0162-0283. 
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In this section we discuss the baseline tractor and engine technologies for the 

2010 model year, and then discuss the types of technologies that the agencies considered 

to improve performance relative to this baseline, while Section III.A.2 discusses the 

technology packages the agencies used to determine the final standard levels.

(a) Baseline Tractor & Tractor Technologies

Baseline tractor: The agencies developed the baseline tractor to represent the 

average 2010 model year tractor. Today there is a large spread in aerodynamics in the 

new tractor fleet. Trucks sold may reflect so-called classic styling (as described in 

Section II.B.3.c), or may be sold with aerodynamic packages. Based on our review of 

current truck model configurations and Polk data provided through MJ Bradley,

202 we 

believe the aerodynamic configuration of the baseline new truck fleet is approximately 25 

percent Bin I, 70 percent Bin II, and 5 percent Bin III (as these bin configurations are 

explained above in Section II.B. (2)(c). The baseline Class 7 and 8 day cab tractor 

consists of an aerodynamic package which closely resembles the Bin I package described 

in Section II.B. (2)(c), baseline tire rolling resistance of 7.8 kg/metric ton for the steer 

tire and 8.2 kg/ metric ton,203 dual tires with steel wheels on the drive axles, and no 

vehicle speed limiter. The baseline tractor for the Class 8 sleeper cabs contains the same 

aerodynamic and tire rolling resistance technologies as the baseline day cab, does not 

include vehicle speed limiters, and does not include an idle reduction technology. The 

agencies assume the baseline transmission is a 10 speed manual. The agencies received a 

comment from the ICCT stating that the 0.69 Cd baseline for high roof sleepers published 

in the NPRM is higher than existing studies show. ICCT cited three studies including a 

Society of Automotive Engineering paper showing a lower Cd for tractor trailers. The 

agencies based the average Cd for high roof sleepers on available in use fleet composition 

data, combined with an assessment of drag coefficient for different truck configurations. 

The agencies are finalizing the 0.69 baseline Cd for high roof sleeper based on our 

assessment for the NPRM. However, we will continue to gather information on the 

composition of the in-use fleet and may alter the baseline in a future action, should more 

data become available that demonstrates our estimate is incorrect.

Performance from this baseline can be improved by the use of the following 

technologies:

Aerodynamic technologies: There are opportunities to reduce aerodynamic drag 

from the tractor, but it is difficult to assess the benefit of individual aerodynamic features. 

Therefore, reducing aerodynamic drag requires optimizing of the entire system. The 

potential areas to reduce drag include all sides of the truck – front, sides, top, rear and 

bottom. The grill, bumper, and hood can be designed to minimize the pressure created by 

the front of the truck. Technologies such as aerodynamic mirrors and fuel tank fairings 

can reduce the surface area perpendicular to the wind and provide a smooth surface to 

minimize disruptions of the air flow. Roof fairings provide a transition to move the air 

 

202 MJ Bradley. Heavy-duty Market Analysis. May 2009. Page 10.

203 US Environmental Protection Agency. SmartWay Transport Partnership July 2010 e-update accessed 

July 16, 2010, from http://www.epa.gov/smartwaylogistics/newsroom/documents/e-update-july-10.pdf
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smoothly over the tractor and trailer. Side extenders can minimize the air entrapped in 

the gap between the tractor and trailer. Lastly, underbelly treatments can manage the 

flow of air underneath the tractor. As discussed in the TIAX report, the coefficient of 

drag (Cd) of a SmartWay sleeper cab high roof tractor is approximately 0.60, which is a 

significant improvement over a truck with no aerodynamic features which has a Cd value 

of approximately 0.80.204 The GEM demonstrates that an aerodynamic improvement of a 

Class 8 high roof sleeper cab with a Cd value of 0.60 (which represents a Bin III tractor) 

provides a 5 percent reduction in fuel consumption and CO2 emissions over a truck with a 

Cd of 0.68.

Lower Rolling Resistance Tires: A tire’s rolling resistance results from the tread 

compound material, the architecture and materials of the casing, tread design, the tire 

manufacturing process, and its operating conditions (surface, inflation pressure, speed, 

temperature, etc.). Differences in rolling resistance of up to 50 percent have been 

identified for tires designed to equip the same vehicle. The baseline rolling resistance 

coefficient for today’s fleet is 7.8 kg/metric ton for the steer tire and 8.2 kg/metric ton for 

the drive tire, based on sales weighting of the top three manufacturers based on market 

share.205 Since 2007, SmartWay trucks have had steer tires with rolling resistance 

coefficients of less than 6.6 kg/metric ton for the steer tire and less than 7.0 kg/metric ton 

for the drive tire.206 Low rolling resistance (LRR) drive tires are currently offered in both 

dual assembly and single wide-base configurations. Single wide tires can offer rolling 

resistance reduction along with improved aerodynamics and weight reduction. The GEM 

demonstrates that replacing baseline tractor tires with tires which meet the Bin I level 

provides approximately a 4 percent reduction in fuel consumption and CO2 emissions 

over the prescribed test cycle, as shown in RIA Chapter 2, Figure 2-2.

Weight Reduction: Reductions in vehicle mass reduce fuel consumption and 

GHGs by reducing the overall vehicle mass to be accelerated and also through increased 

vehicle payloads which can allow additional tons to be carried by fewer trucks 

consuming less fuel and producing lower emissions on a ton-mile basis. Initially for 

proposal, the agencies considered evaluating vehicle mass reductions on a total vehicle 

basis for combination tractors.207 The agencies considered defining a baseline vehicle 

curb weight and the GEM would have used the vehicle’s actual curb weight to calculate 

the increase or decrease in fuel consumption related to the overall vehicle mass relative to 

that baseline. After considerable evaluation of this issue, including discussions with the 

industry, we decided it would not be possible to define a single vehicle baseline mass for 

the tractors that would be appropriate and representative. Actual vehicle curb weights for 

these classes of vehicles vary by thousands of pounds dependent on customer features 

added to vehicles and critical to the function of the vehicle in the particular vocation in 

which it is used. This is true of vehicles such as Class 8 tractors considered in this 

section that may appear to be relatively homogenous but which in fact are quite 

heterogeneous.

 

204 See TIAX, Note 198, Page 4-50.

205 See SmartWay, Note 203, above. 

206 Ibid.

207 The agencies are using the approach of evaluating total vehicle mass for heavy-duty pickups and vans 

where we have more data on the current fleet vehicle mass.
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This reality led us to the solution we proposed. In the proposal, we reflected mass 

reductions for specific technology substitutions (e.g., installing aluminum wheels instead 

of steel wheels) where we could with confidence verify the mass reduction information 

provided by the manufacturer even though we cannot estimate the actual curb weight of 

the vehicle. In this way, we accounted for mass reductions where we can accurately

account for its benefits. 

For the final rules, based on evaluation of the comments, the agencies developed 

an expanded list of weight reduction opportunities, from which the sum of the weight 

reduction from the technologies installed on a specific tractor can be input into the GEM 

as listed in Table II-9 in Section II. The list includes additional components, but not 

materials, from those proposed in the NPRM. For high strength steel, the weight 

reduction value is equal to 10 percent of the presumed baseline component weight, as the 

agencies used a conservative value based on the DOE report. We recognize that there 

may be additional potential for weight reduction in new high strength steel components 

which combine the reduction due to the material substitution along with improvements in 

redesign, as evidenced by the studies done for light-duty vehicles. In the development of 

the high strength steel component weights, we are only assuming a reduction from 

material substitution and no weight reduction from redesign, since we do not have any 

data specific to redesign of heavy-duty components nor do we have a regulatory

mechanism to differentiate between material substitution and improved design. We are 

finalizing for wheels that both aluminum and light weight aluminum are eligible to be 

used as light-weight materials. Only aluminum and not light weight aluminum can be 

used as a light-weight material for other components. The reason for this is data was 

available for light weight aluminum for wheels but was not available for other 

components.

As explained in Section II.B above, the agencies continue to believe that the 400 

pound weight target is appropriate for setting the final combination tractor CO2 emissions 

and fuel consumption standards. The agencies agree with the commenter that 400 pounds 

of weight reduction without the use of single wide tires may not be achievable for all 

tractor configurations. The agencies have expanded the list of weight reduction 

components which can be input into the GEM in order to provide the manufacturers with 

additional means to comply with the combination tractors and to further encourage 

reductions in vehicle weight. The agencies considered increasing the target value beyond 

400 pounds given the additional reduction potential identified in the expanded technology

list; however, lacking information on the capacity for the industry to change to these light 

weight components across the board by the 2014 model year, we have decided to 

maintain the 400 pound target. The agencies intend to continue to study the potential for 

additional weight reductions in our future work considering a second phase of truck fuel 

efficiency and GHG regulations.

A weight reduction of 400 pounds applied to a truck which travels at 70,000 

pounds will have a minimal impact on fuel consumption. However, for trucks which 

operate at the maximum GVWR which occurs approximately in one third of truck miles 

travelled, a reduced tare weight will allow for additional payload to be carried. The GEM 

demonstrates that a weight reduction of 400 pounds applied to the payload tons for one 
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third of the trips provides a 0.3 percent reduction in fuel consumption and CO2 emissions 

over the prescribed test cycle, as shown in Figure 2-3 of RIA Chapter 2.

Extended Idle Reduction: Auxiliary power units (APU)s, fuel operated heaters, 

battery supplied air conditioning, and thermal storage systems are among the 

technologies available today to reduce main engine extended idling from sleeper cabs. 

Each of these technologies reduces the baseline fuel consumption during idling from a 

truck without this equipment (the baseline) from approximately 0.8 gallons per hour 

(main engine idling fuel consumption rate) to approximately 0.2 gallons per hour for an 

APU.208 EPA and NHTSA agree with the TIAX assessment of a 6 percent reduction in 

overall fuel consumption reduction.209 

Vehicle Speed Limiters: Fuel consumption and GHG emissions increase 

proportional to the square of vehicle speed. Therefore, lowering vehicle speeds can 

significantly reduce fuel consumption and GHG emissions. A vehicle speed limiter 

(VSL), which limits the vehicle’s maximum speed, is a simple technology that is utilized 

today by some fleets (though the typical maximum speed setting is often higher than 65 

mph). The GEM shows that using a vehicle speed limiter set at 62 mph on a sleeper cab 

tractor will provide a 4 percent reduction in fuel consumption and CO2 emissions over the 

prescribed test cycles over a baseline vehicle without a VSL or one set above 65 mph.210

Transmission: As discussed in the 2010 NAS report, automatic and automated 

manual transmissions may offer the ability to improve vehicle fuel consumption by

optimizing gear selection compared to an average driver. However, as also noted in the 

report and in the supporting TIAX report, the improvement is very dependent on the 

driver of the truck, such that reductions ranged from 0 to 8 percent.211 Well-trained 

drivers would be expected to perform as well or even better than an automatic 

transmission since the driver can see the road ahead and anticipate a changing stoplight or 

other road condition that an automatic transmission can not anticipate. However, poorlytrained drivers that shift too frequently or not frequently enough to maintain optimum 

engine operating conditions could be expected to realize improved in-use fuel 

consumption by switching from a manual transmission to an automatic or automated 

manual transmission. Although we believe there may be real benefits in reduced fuel 

consumption and GHG emissions through the application of dual clutch, automatic or 

automated manual transmission technology, we are not reflecting this potential 

improvement in our standard setting or in our compliance model. We have taken this 

approach because we cannot say with confidence what level of performance 

improvement to expect. 

 

208 See the RIA Chapter 2 for details.

209 See the 2010 NAS Report, Note 197, above, at 128.

210 The Center for Biological Diversity thought that the agencies; were limiting their consideration of 

vehicle speed limiters as a potential control technology due to perceived legal constraints. As noted above, 

vehicle speed limiters are a potential control technology for heavy duty vehicles and there is no statutory 

bar on either agency considering the performance of VSLs in developing the standards.

211 See TIAX, Note 198, above at 4-70.
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Low Friction Transmission, Axle, and Wheel Bearing Lubricants: The 2010 NAS 

report assessed low friction lubricants for the drivetrain as a 1 percent improvement in 

fuel consumption based on fleet testing.212 The light-duty 2012-16 MY vehicle rule and 

the pickup truck portion of this program estimate that low friction lubricants can have an 

effectiveness value between 0 and 1 percent compared to traditional lubricants. However, 

it is not clear if in many heavy-duty applications these low friction lubricants could have 

competing requirements like component durability issues requiring specific lubricants 

with different properties than low friction. 

Hybrid: Hybrid powertrain development in Class 7 and 8 tractors has been 

limited to a few manufacturer demonstration vehicles to date. One of the key benefit 

opportunities for fuel consumption reduction with hybrids is less fuel consumption when 

a vehicle is idling, but the standard is already premised on use of extended idle reduction 

so use of hybrid technology would duplicate many of the same emission reductions 

attributable to extended idle reduction. NAS estimated that hybrid systems would cost 

approximately $25,000 per tractor in the 2015 through the 2020 time frame and provide a 

potential fuel consumption reduction of 10 percent, of which 6 percent is idle reduction 

which can be achieved (less expensively) through the use of other idle reduction 

technologies.213 The limited reduction potential outside of idle reduction for Class 8 

sleeper cab tractors is due to the mostly highway operation and limited start-stop 

operation. Due to the high cost and limited benefit during the model years at issue in this 

action (as well as issues regarding sufficiency of lead time (see Section III.2 (a) below), 

the agencies are not including hybrids in assessing standard stringency (or as an input to 

GEM). However as discussed in Section IV, the agencies are providing incentives to 

encourage the introduction of advanced technologies including hybrid powertrains in 

appropriate applications.

Management: The 2010 NAS report noted many operational opportunities to 

reduce fuel consumption, such as driver training and route optimization. The agencies 

have included discussion of several of these strategies in RIA Chapter 2, but are not using 

these approaches or technologies in the standard setting process. The agencies are 

looking to other resources, such as EPA’s SmartWay Transport Partnership and 

regulations that could potentially be promulgated by the Federal Highway Administration 

and the Federal Motor Carrier Safety Administration, to continue to encourage the 

development and utilization of these approaches. 

(b) Baseline Engine & Engine Technologies

The baseline engine for the Class 8 tractors is a Heavy Heavy-Duty Diesel engine 

with 15 liters of displacement which produces 455 horsepower. The agencies are using a 

smaller baseline engine for the Class 7 tractors because of the lower combined weights of 

this class of vehicles require less power, thus the baseline is an 11L engine with 350 

horsepower. The agencies developed the baseline diesel engine as a 2010 model year 

engine with an aftertreatment system which meets EPA’s 0.20 grams of NOX/bhp-hr 

 

212 See the 2010 NAS Report, Note 197, page 67.

213 See the 2010 NAS Report, Note 197, page 128.
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standard with an SCR system along with EGR and meets the PM emissions standard with 

a diesel particulate filter with active regeneration. The baseline engine is turbocharged 

with a variable geometry turbocharger. The following discussion of technologies 

describes improvements over the 2010 model year baseline engine performance, unless 

otherwise noted. Further discussion of the baseline engine and its performance can be 

found in Section III.A.2.6 below. 

With respect to stringency level, the agencies received comments from Cummins 

and Daimler stating that the proposed stringency levels were appropriate for the leadtimes. Conversely, the agencies received comments from several environmental groups 

(UCS, CATF, ACEEE) supporting a greater reduction in engine CO2 emissions and fuel 

consumption based on the NAS report. Navistar also stated that the agencies’ baseline 

engine is inappropriate since there is not currently a 0.20 NOX compliant engine in 

production. A discussion of how the baseline engine configuration can be found below in 

Section (2)(b)(i).

Navistar also stated that the baseline engines proposed in the NPRM, MY 2010 

selective catalytic reduction (SCR)-equipped, could not meet the agencies’ statutory

obligation to set feasible standards, and requested instead that MY 2010 engines currently 

in-use be used to meet the feasibility factor. The agencies thus disagree with the 

statement that SCR is infeasible and therefore, the agencies reaffirm that the engine used 

as the baseline engine in the agencies’ analysis does indeed exist. In fact, several engine 

families have been certified by EPA using SCR technology over the past two years, all of 

which have met the 0.20 g/bhp-hr NOX standard.214 EPA disagrees with Navistar that 

SCR engines currently certified do not meet this standard. Compliance with the 0.20 

g/bhp-hr FTP NOX standard is measured based on an engine’s performance when tested 

over a specific duty cycle (see 40 CFR § 86.007-11(a)(2)). This is also true regarding the 

SET standard (see 40 CFR § 86.007-11(a)(3)). Further, the FTP and SET tests are 

average tests, so emissions could go over 0.20 even for some portion of the test itself. 

Manufacturers are also required to ensure that their engines meet the NTE standard under 

all conditions specified in the regulations (see 40 CFR § 86.007-11(a)(4)). 

Several manufacturers have been able to show compliance with these standards in 

applications for certification provided to EPA for several engine families. Navistar has 

provided no information indicating that these tests were false or improper. Indeed, 

Navistar does not appear to suggest, or provide any evidence, that engines with working 

SCR systems do not meet the NOX standard. Thus, it is demonstrably false to conclude 

that the NOX standard cannot be met with SCR-equipped engines.

A more detailed response to these comments appears in Section 6.2 of the 

Response to Comment document for this rule.

Engine performance for CO2 emissions and fuel consumption can be improved by 

use of the following technologies:

 

214 See 2010 Model Year Engine Certification Data and 2011 Model Year Engine Certification Data files 

located in the Docket EPA-HQ-OAR-2010-0162.
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Improved Combustion Process: Fuel consumption reductions in the range of 1 to 

3 percent over the baseline diesel engine are identified in the 2010 NAS report through 

improved combustion chamber design, higher fuel injection pressure, improved injection 

shaping and timing, and higher peak cylinder pressures.215

Turbochargers: Improved efficiency of a turbocharger compressor or turbine 

could reduce fuel consumption by approximately 1 to 2 percent over variable geometry

turbochargers in the market today.

216

 The 2010 NAS report identified technologies such 

as higher pressure ratio radial compressors, axial compressors, and dual stage 

turbochargers as design paths to improve turbocharger efficiency.

Higher efficiency air handling processes: To maximize the efficiency of such 

processes, induction systems may be improved by manufacturing more efficiently

designed flow paths (including those associated with air cleaners, chambers, conduit, 

mass air flow sensors and intake manifolds) and by designing such systems for improved 

thermal control. Improved turbocharging and air handling systems must include higher 

efficiency EGR systems and intercoolers that reduce frictional pressure loss while 

maximizing the ability to thermally control induction air and EGR. The agencies 

received comments from Honeywell confirming that turbochargers provide a role in 

reducing the CO2 emissions from engines. Other components that offer opportunities for 

improved flow efficiency include cylinder heads, ports and exhaust manifolds to further 

reduce pumping losses. Variable air breathing systems such as variable valve actuation 

may provide additional gains at different loads and speeds. The NESCCAF/ICCT study

indicated up to 1.2% reduction could be achieved solely through improved EGR systems.

Low Temperature Exhaust Gas Recirculation: Most medium- and heavy-duty

vehicle diesel engines sold in the U.S. market today use cooled EGR, in which part of the 

exhaust gas is routed through a cooler (rejecting energy to the engine coolant) before 

being returned to the engine intake manifold. EGR is a technology employed to reduce 

peak combustion temperatures and thus NOX. Low-temperature EGR uses a larger or 

secondary EGR cooler to achieve lower intake charge temperatures, which tend to further 

reduce NOX formation. If the NOX requirement is unchanged, low-temperature EGR can 

allow changes such as more advanced injection timing that will increase engine 

efficiency slightly more than 1 percent.217 Because low-temperature EGR reduces the 

engine’s exhaust temperature, it may not be compatible with exhaust energy recovery

systems such as turbocompounding or a bottoming cycle.

Engine Friction Reduction: Reduced friction in bearings, valve trains, and the 

piston-to-liner interface will improve efficiency. Any friction reduction must be carefully

developed to avoid issues with durability or performance capability. Estimates of fuel 

consumption improvements due to reduced friction range from 0 to 2 percent.218

 

215 See TIAX. Note 198, Page 4-13.

216 See TIAX Note 198, Page 4-2.

217 See TIAX, Note 198, Page 4-13.

218 TIAX, Note 198, pg 4-15
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Reduced Parasitic Loads: Accessories that are traditionally gear or belt driven by

a vehicle’s engine can be optimized and/or converted to electric power. Examples include 

the engine water pump, oil pump, fuel injection pump, air compressor, power-steering 

pump, cooling fans, and the vehicle’s air-conditioning system. Optimization and 

improved pressure regulation may significantly reduce the parasitic load of the water, air 

and fuel pumps. Electrification may result in a reduction in power demand, because 

electrically powered accessories (such as the air compressor or power steering) operate 

only when needed if they are electrically powered, but they impose a parasitic demand all 

the time if they are engine driven. In other cases, such as cooling fans or an engine’s 

water pump, electric power allows the accessory to run at speeds independent of engine 

speed, which can reduce power consumption. The TIAX study used 2 to 4 percent fuel 

consumption improvement for accessory electrification, with the understanding that 

electrification of accessories will have more effect in short-haul/urban applications and 

less benefit in line-haul applications.219 Bendix, in their comments to the agencies, 

confirmed that there are engine accessories available that can improve an engine’s fuel 

efficiency. 

Selective catalytic reduction: This technology is common on 2010 the mediumand heavy-duty diesel engines used in Class 7 and 8 tractors (and the agencies therefore 

have included it as part of the baseline engine, as noted above). Because SCR is a highly

effective NOX aftertreatment approach, it enables engines to be optimized to maximize 

fuel efficiency, rather than minimize engine-out NOX. 2010 SCR systems are estimated 

to result in improved engine efficiency of approximately 3 to 5 percent compared to a 

2007 in-cylinder EGR-based emissions system and by an even greater percentage 

compared to 2010 in-cylinder approaches.220 As more effective low-temperature 

catalysts are developed, the NOX conversion efficiency of the SCR system will increase. 

Next-generation SCR systems could then enable additional efficiency improvements; 

alternatively, these advances could be used to maintain efficiency while down-sizing the 

aftertreatment. We estimate that continued optimization of the catalyst could offer 1 to 2 

percent reduction in fuel use over 2010 model year systems in the 2014 model year.221 

The agencies estimate an additional 1 to 2 percent reduction may be feasible in the 2017 

model year through additional refinement.

Mechanical Turbocompounding: Mechanical turbocompounding adds a low 

pressure power turbine to the exhaust stream in order to extract additional energy, which 

is then delivered to the crankshaft. Published information on the fuel consumption 

reduction from mechanical turbocompounding varies between 2.5 and 5 percent.222 Some 

of these differences may depend on the operating condition or duty cycle that was 

considered by the different researchers. The performance of a turbocompounding system 

tends to be highest at full load and much less or even zero at light load. 

 

219 See TIAX. Note 198, Page 3-5.

220 Stanton, D. “Advanced Diesel Engine Technology Development for High Efficiency, Clean 

Combustion.” Cummins, Inc. Annual Progress Report 2008 Vehicle Technologies Program: Advanced 

Combustion Engine Technologies, US Department of Energy. Pp 113-116. December 2008.

221 See TIAX, Note 198, pg. 4-9

222 NESCCAF/ICCT study (p. 54) and TIAX (2009, pp. 3-5)
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Electric Turbocompounding: This approach is similar in concept to mechanical 

turbocompounding, except that the power turbine drives an electrical generator. The 

electricity produced can be used to power an electrical motor supplementing the engine 

output, to power electrified accessories, or to charge a hybrid system battery. None of 

these systems have been demonstrated commercially, but modeled results by industry and 

DOE have shown improvements of 3 to 5 percent.223

Bottoming Cycle: An engine with bottoming cycle uses exhaust or other heat 

energy from the engine to create power without the use of additional fuel. The sources of 

energy include the exhaust, EGR, charge air, and coolant. The estimates for fuel 

consumption reduction range up to 10 percent as documented in the 2010 NAS report.224 

However, none of the bottoming cycle or Rankine systems has been demonstrated 

commercially and are currently in only the research stage. See Section 2.4.2.7 of the RIA 

and Section II.B above. 

(2) Projected Technology Package Effectiveness and Cost

(a) Class 7 and 8 Combination Tractors 

EPA and NHTSA project that CO2 emissions and fuel consumption reductions 

can be feasibly and cost-effectively achieved in these rules’ time frames through the 

increased application of aerodynamic technologies, LRR tires, weight reduction, 

extended idle reduction technologies, vehicle speed limiters, and engine improvements. 

The agencies believe that hybrid powertrains systems for tractors will not be sufficiently 

developed and the necessary manufacturing capacity put in place to base a standard on 

any significant volume of hybrid tractors. The agencies are not aware of any full hybrid 

systems currently developed for long haul tractor applications. To date, hybrid systems 

for tractors have been primarily focused on idle shutdown technologies and not the 

broader energy storage and recovery systems necessary to achieve reductions over typical 

vehicle drive cycles. The final standards reflect the potential for idle shutdown 

technologies through the GEM model. Further as highlighted by the 2010 NAS report, 

the agencies do believe that full hybrid powertrains have the potential in the longer term 

to provide significant improvements in fuel efficiency and to reduce greenhouse gas 

emissions. However lacking any existing systems or manufacturing base, we cannot

conclude such technology will be available in the 2014-2018 timeframe. Developing a 

full hybrid system itself would be a three to five project followed by several more years 

to put in place manufacturing capacity. The agencies are including incentives for the use 

of hybrid technologies to help encourage their development and to reward manufacturers 

that can produce hybrids through prototype and low volume production methods. The 

agencies also are not including drivetrain technologies in the standard setting process, as 

discussed in Section II.B.3.h.iv. 

The agencies evaluated each technology and estimated the most appropriate 

application rate of technology into each tractor subcategory. The next sections describe 

 

223 K. G. Duleep of Energy and Environmental Analysis, R. Kruiswyk, 2008, pp. 212-214, 

NESCCAF/ICCT, 2009, p. 54

224 See 2010 NAS Report, Note 197, page 57.
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the effectiveness of the individual technologies, the costs of the technologies, the 

projected application rates of the technologies into the regulatory subcategories, and 

finally the derivation of the final standards.

(i) Baseline Tractor Performance

The agencies developed the baseline tractor for each subcategory to represent an 

average 2010 model year tractor configured as noted earlier. The approach taken by the 

agencies was to define the individual inputs to the GEM, as shown in Table III-1. For 

example, the agencies evaluated the industry’s tractor offerings and concluded that the 

average tractor contains a generally aerodynamic shape (such as roof fairings) and avoids 

classic features such as an exhaust stacks at the B-pillar, which increases drag. As noted 

earlier, our assessment of the baseline new high roof tractor fleet aerodynamics consists

of approximately 25 percent Bin I, 70 percent Bin II, and 5 percent Bin III tractors. The 

baseline rolling resistance coefficient for today’s fleet is 7.8 kg/metric ton for the steer 

tire and 8.2 kg/metric ton for the drive tire, based on sales weighting of the top three 

manufacturers based on market share.225 The agencies assumed no application of vehicle 

speed limiters, weight reduction technologies, or idle reduction technologies in the 

baseline tractor. The agencies use the inputs in the GEM to derive the baseline CO2

emissions and fuel consumption of Class 7 and 8 tractors. The results are included in

Table III-1.

Table III-1: Baseline Tractor Definitions

Class 7 Class 8

Day Cab Day Cab Sleeper Cab

Low 

Roof

Mid 

Roof

High 

Roof

Low 

Roof

Mid 

Roof

High 

Roof

Low 

Roof

Mid 

Roof

High 

Roof

Aerodynamics (Cd)

Baseline 0.77 0.87 0.73 0.77 0.87 0.73 0.77 0.87 0.70

Steer Tires (CRR kg/metric ton)

Baseline 7.8 7.8 7.8 7.8 7.8 7.8 7.8 7.8 7.8

Drive Tires (CRR kg/metric ton)

Baseline 8.2 8.2 8.2 8.2 8.2 8.2 8.2 8.2 8.2

Weight Reduction (lb)

Baseline 0 0 0 0 0 0 0 0 0

Extended Idle Reduction (gram CO2/ton-mile reduction)

Baseline N/A N/A N/A N/A N/A N/A 0 0 0

Vehicle Speed Limiter

Baseline -- -- -- -- -- -- -- -- --

Engine

Baseline 2010 

MY 11L 

Engine

2010 

MY 11L 

Engine

2010 

MY 11L 

Engine

2010 

MY 15L 

Engine

2010 

MY 15L 

Engine

2010 MY 

15L 

Engine

2010 

MY 15L 

Engine

2010 

MY 15L 

Engine

2010 

MY 15L 

Engine

 

225 US Environmental Protection Agency. SmartWay Transport Partnership July 2010 e-update accessed 

July 16, 2010, from http://www.epa.gov/smartwaylogistics/newsroom/documents/e-update-july-10.pdf.
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Table III-2: Class 7 and 8 Tractor Baseline CO2 Emissions and Fuel Consumption

Class 7 Class 8

Day Cab Day Cab Sleeper Cab

Low

Roof

Mid 

Roof

High 

Roof

Low 

Roof

Mid 

Roof

High 

Roof

Low 

Roof

Mid 

Roof

High 

Roof

CO2 (grams 

CO2/ton-mile)

116 128 138 88 95 103 80 89 94

Fuel 

Consumption 

(gal/1,000 

ton-mile)

11.4 12.6 13.6 8.7 9.4 10.1 7.8 8.7 9.3

(ii) Tractor Technology Package Definitions

The agencies’ assessment of the final technology effectiveness was developed 

through the use of the GEM in coordination with chassis testing of three SmartWay

certified Class 8 sleeper cabs. The agencies developed the standards through a three-step 

process. First, the agencies developed technology performance characteristics for each 

technology, described below. Each technology is associated with an input parameter 

which is in turn modeled in the GEM. The performance levels for the range of Class 7 

and 8 tractor aerodynamic packages and vehicle technologies are described in Table III-3. 

Second, the agencies combined the technology performance levels with a projected 

technology application rate to determine the GEM inputs used to set the stringency of the 

final standards. Third, the agencies input the parameters into GEM and used the output 

to determine the final CO2 emissions and fuel consumption levels. 

Aerodynamics

The aerodynamic packages are categorized as Bin I, Bin II, Bin III, Bin IV, or Bin 

V based on the aerodynamic performance determined through testing conducted by the 

manufacturer. A more complete description of these aerodynamic packages is included 

in Chapter 2 of the RIA. In general, the CdA values for each package and tractor 

subcategory were developed through EPA’s coastdown testing of tractor-trailer 

combinations, the 2010 NAS report, and SAE papers. 

Tire Rolling Resistance

The rolling resistance coefficient for the tires was developed from SmartWay’s 

tire testing to develop the SmartWay certification, in addition to testing a selection of 

tractor tires as part of this program. The tire performance was evaluated in three levels -

the baseline (average), 15 percent better than the average, and an additional 15 percent 

improvement. The first 15 percent improvement represents the threshold used to develop 

SmartWay certified tires for long haul tractors. The second 15 percent threshold 

represents an incremental step for improvements beyond today’s SmartWay level and 

represents the best in class rolling resistance of the tires we tested.

Weight Reduction
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The weight reductions were developed from tire manufacturer information, the 

Aluminum Association, the Department of Energy, and TIAX, as discussed above in 

Section II.B.3.e. 

Idle Reduction

The benefits for the extended idle reductions were developed from literature, 

SmartWay work, and the 2010 NAS report. The agencies received comments from 

multiple stakeholders regarding idle reduction technologies (IRT). Two commenters 

asked us to revise the default value associated with the IRT technology, and two 

commenters want to use IRT in GEM even without automatic engine shut down (AES). 

The agencies proposed AES after 5 minutes with no exceptions to help ensure that the 

idle reductions are realized in-use. Use of an AES ensures the main engine will be shut 

down, whereas idle reduction technologies alone do not provide that level of certainty. 

Without an automatic shutdown of the main engine, actual savings would depend on 

operator behavior and thus be essentially unverifiable. The agencies are finalizing the 

calculation as proposed, along with the automotive engine shutdown requirement. 

Additional details regarding the comments and calculations are included in RIA Section 

2.5.4.2.

Several commenters requested that the level of emissions reductions vary in GEM

by different idle reduction technologies, and one commenter requested that the 

application of battery powered APUs be incentivized. The agencies recognize that the 

level of emission reductions provided by different IRT varies, but are adopting a 

conservative level to recognize that some vehicles may be sold with only an AES but 

may then install an IRT in-use. Or some vehicles may be sold with one IRT but then 

choose to install alternative ones in-use. The agencies cannot verify the savings which 

depend on operator behavior. 

One commenter requested that we provide manufacturers with an option to allow 

the AES feature to be reprogammable after a specified number of miles or time in 

service. The agencies recognize that AES may impact the resale value of tractors and, in 

response to comments, are adopting provisions for the optional expiration of an AES. 

Thus, the initial buyer could select AES only for the number of miles based on the 

expected time before resale. Similar to vehicle speed limiters, we would discount the 

impact based on the full life of the truck (e.g. 1,259,000 miles). Additional detail can be 

found in RIA Section 2.5.4.2.

Vehicle Speed Limiter

The agencies are not including vehicle speed limiters in the technology package 

for Class 7 and 8 tractors.

Summary of Technology Performance

Table III-3 describes the performance levels for the range of Class 7 and 8 tractor 

aerodynamic packages and vehicle technologies. 
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Table III-3: Class 7 and 8 Tractor Technology Values

Class 7 Class 8

Day Cab Day Cab Sleeper Cab

Low/Mid 

Roof

High 

Roof

Low/Mid 

Roof

High 

Roof

Low 

Roof

Mid 

Roof

High 

Roof

Aerodynamics (Cd)

Bin I 0.77/0.8

7

0.79 0.77/0.87 0.79 0.77 0.87 0.75

Bin II 0.71/0.8

2

0.72 0.71/0.82 0.72 0.71 0.82 0.68

Bin III 0.63 0.63 0.60

Bin IV 0.56 0.56 0.52

Bin V 0.51 0.51 0.47

Steer Tires (CRR kg/metric ton)

Baseline 7.8 7.8 7.8 7.8 7.8 7.8 7.8

Level I 6.6 6.6 6.6 6.6 6.6 6.6 6.6

Level II 5.7 5.7 5.7 5.7 5.7 5.7 5.7

Drive Tires (CRR kg/metric ton)

Baseline 8.2 8.2 8.2 8.2 8.2 8.2 8.2

Level I 7.0 7.0 7.0 7.0 7.0 7.0 7.0

Level II 6.0 6.0 6.0 6.0 6.0 6.0 6.0

Weight Reduction (lb)

Control 400 400 400 400 400 400 400

Extended Idle Reduction (gram CO2/ton-mile reduction)a

Control N/A N/A N/A N/A 5 5 5

Vehicle Speed Limiterb

Control N/A N/A N/A N/A N/A N/A N/A

Notes:

a While the standards are set based on this value, users would enter another value if AES is not applied or 

applied for less than the full useful life of the engine.

b Vehicle speed limiters are an applicable technology for all Class 7 and 8 tractors, however the standards 

are not premised on the use of this technology.

(iii) Tractor Technology Application Rates

As explained above, vehicle manufacturers often introduce major product changes 

together, as a package. In this manner the manufacturers can optimize their available 

resources, including engineering, development, manufacturing and marketing activities to 

create a product with multiple new features. In addition, manufacturers recognize that a 

truck design will need to remain competitive over the intended life of the design and meet 

future regulatory requirements. In some limited cases, manufacturers may implement an 

individual technology outside of a vehicle’s redesign cycle. 

With respect to the levels of technology application used to develop the final 

standards, NHTSA and EPA established technology application constraints. The first type 

of constraint was established based on the application of fuel consumption and CO2
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emission reduction technologies into the different types of tractors. For example, idle 

reduction technologies are limited to Class 8 sleeper cabs using the assumption that day

cabs are not used for overnight hoteling. A second type of constraint was applied to most 

other technologies and limited their application based on factors reflecting the real world 

operating conditions that some combination tractors encounter. This second type of 

constraint was applied to the aerodynamic, tire, and vehicle speed limiter technologies. 

Table III-4 specifies the application rates that EPA and NHTSA used to develop the final 

standards. The agencies received a significant number of comments related to this 

second basis. In particular, commenters questioned the reasons for not requiring the 

maximum reduction technology in every case. The agencies have not done so because 

we have concluded that within each of these individual vehicle categories there are 

particular applications where the use of the identified technologies would be either 

ineffective or not technically feasible. The addition of ineffective technologies provides 

no environmental or fuel efficiency benefit, increases costs and is not a basis upon which 

to set a maximum feasible improvement. For example, the agencies have not required the 

use of full aerodynamic vehicle treatments on 100 percent of tractors because we know 

that in many applications (for example gravel truck engaged in local aggregate delivery) 

the added weight of the aerodynamic technologies will increase fuel consumption and 

hence CO2 emissions to a greater degree than the reduction that would be accomplished 

from the more aerodynamic nature of the tractor. To simply set the standard based on the 

largest reduction possible estimated narrowly over a single test procedure while ignoring 

the in-use effects of the technology would in this case result in a perverse outcome that is 

not in keeping with the agencies’ goals or the requirements of the CAA and EISA.

Aerodynamics Application Rate

The impact of aerodynamics on a truck’s efficiency increases with vehicle speed. 

Therefore, the usage pattern of the truck will determine the benefit of various 

aerodynamic technologies. Sleeper cabs are often used in line haul applications and drive 

the majority of their miles on the highway travelling at speeds greater than 55 mph. The 

industry has focused aerodynamic technology development, including SmartWay

tractors, on these types of trucks. Therefore the agencies are adopting the most 

aggressive aerodynamic technology application to this regulatory subcategory. All of the 

major manufacturers today offer at least one SmartWay truck model. The 2010 NAS 

Report on heavy-duty trucks found that manufacturers indicated that aerodynamic 

improvements which yield 3 to 4 percent fuel consumption reduction or 6 to 8 percent 

reduction in Cd values, beyond technologies used in today’s SmartWay trucks are 

achievable.226 The aerodynamic application rate for Class 8 sleeper cab high roof cabs 

(i.e., the degree of technology application on which the stringency of the final standard is 

premised) consists of 20 percent of Bin IV, 70 percent Bin III, and 10 percent Bin II 

reflecting our assessment of the fraction of tractors in this segment that can successfully 

apply these aerodynamic packages. 

The 90 percent of tractors that we project can either be Bin II or Bin III equipped 

reflects the bulk of Class 8 high roof sleeper cab applications. We are not projecting a 

 

226 See TIAX, Note 198, Page 4-40.
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higher fraction of Bin III aerodynamic systems because of the limited lead time for the 

program and the need for these more advanced technologies to be developed and 

demonstrated before being applied across a wider fraction of the fleet. Aerodynamic 

improvements through new tractor designs and the development of new aerodynamic 

components is an inherently slow and iterative process. Aerodynamic impacts are highly 

nonlinear and often reflect unexpected interactions between multiple components. Given 

the nature of aerodynamic improvements it is inherently difficult to estimate the degree to 

which improvements can be made beyond previously demonstrated levels. The changes 

required for Bins III and IV reflect the kinds of improvements projected in the 

Department of Energy’s Supertruck program. That program assumes that such systems 

can be demonstrated on vehicles by 2017. In this case, the agencies are projecting that 

truck OEMs will be able to begin implementing these aerodynamic technologies prior to 

2017 on a limited scale. Importantly, our averaging, banking and trading provisions 

provide manufacturers with the flexibility to implement these technologies over time 

even though the standard changes in a single step. 

The final aerodynamic application for the other tractor regulatory categories is 

less aggressive than for the Class 8 sleeper cab high roof. The agencies recognize that 

there are truck applications which require on/off-road capability and other truck functions 

which restrict the type of aerodynamic equipment applicable. We also recognize that 

these types of trucks spend less time at highway speeds where aerodynamic technologies 

have the greatest benefit. The 2002 VIUS data ranks trucks by major use.227 The heavy 

trucks usage indicates that up to 35 percent of the trucks may be used in on/off-road 

applications or heavier applications. The uses include construction (16 percent), 

agriculture (12 percent), waste management (5 percent), and mining (2 percent). 

Therefore, the agencies analyzed the technologies to evaluate the potential restrictions 

that would prevent 100 percent application of SmartWay technologies for all of the 

tractor regulatory subcategories.

As discussed in Section II.B.2.c, in response to comments received from 

manufacturers making some of these same points, the agencies are finalizing only two 

aerodynamic bins for low and mid roof tractors. The agencies are reducing the number of 

bins for these tractors from the proposal to reflect the actual range of aerodynamic 

technologies effective in low and mid roof tractor applications. The aerodynamic 

improvements to the bumper, hood, windshield, mirrors, and doors are developed for the 

high roof tractor application and then carried over into the low and mid roof applications. 

As mentioned in Section II.B.2.c, the types of designs that would move high roof tractors 

from a Bin III to Bins IV and V include features such as gap reducers and integral roof 

fairings which would not be appropriate on low and mid roof tractors. Thus, the agencies 

are differentiating the aerodynamic performance for low- and mid-roof tractors into two 

bins – Bin I and Bin II. The application rates in the low and mid roof categories are the 

same as proposed, but aggregated into just two bins. Bin I for these tractors corresponds 

to the proposed “Classic” and “Conventional” bins and Bin II corresponds to the 

proposed “SmartWay,” “Advanced SmartWay,” and “Advanced SmartWay II” bins.

 

227 U.S. Department of Energy. Transportation Energy Data Book, Edition 28-2009. Table 5.7.
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Low Rolling Resistance Tire Application Rate

At proposal, the agencies stated that at least one LRR tire model is available today

that meets the rolling resistance requirements of the Level I and Level II tire packages so 

the 2014 MY should afford manufacturers sufficient lead time to install these packages. 

EPA and NHTSA conducted additional evaluation testing on HD tires used for tractors. 

The agencies also received several comments on the suitability of low rolling resistance 

tires for various HD truck applications. The summary of the agencies findings and a 

response to issues raised by commenters is presented in Section II.D(1)(a).

The agencies note that baseline rolling resistance level for tires installed on 

tractors is approximately equivalent to what the agencies consider to be low rolling 

resistance tires for vocational vehicles because of the tire manufacturer’s focus on 

improving the rolling resistance of tractor tires. For the tire manufacturers to further 

reduce tire rolling resistance, the manufacturers must consider several performance 

criteria that affect tire selection. The characteristics of a tire also influence durability, 

traction control, vehicle handling, comfort, and retreadability. A single performance 

parameter can easily be enhanced, but an optimal balance of all the criteria will require 

improvements in materials and tread design at a higher cost, as estimated by the agencies. 

Tire design requires balancing performance, since changes in design may change 

different performance characteristics in opposing directions. Similar to the discussion 

regarding lesser aerodynamic technology application in tractor segments other than 

sleeper cab high roof, the agencies believe that the final standards should not be premised 

on 100 percent application of Level II tires in all tractor segments given the interference 

with vehicle utility that would result. The agencies are basing their analyses on 

application rates that vary by subcategory recognizing that some subcategories require a 

different balancing of performance versus rolling resistance. 

Weight Reduction Technology Application Rate

The agencies proposed setting the 2014 model year tractor standards using 100 

percent application of a 400 pound weight reduction package. Volvo and ATA stated in 

their comments that not all fleets can use single wide tires and if this is the case the 400 

pound weight reduction cannot be met. The agencies also received comments from 

MEMA, Navistar, American Chemistry Council, the Auto Policy Center, Iron and Steel 

Institute, Arvin Meritor, Aluminum Association, and environmental groups and NGOs 

identifying other potential weight reduction opportunities for tractors. As described in 

Section II.B.3.e above, the agencies are adopting an expanded list of weight reduction 

options which can be input into the GEM for the final rulemaking. 

As also explained in that earlier discussion, the agencies, upon further analysis, 

continue to believe that a 400 pound weight reduction package is appropriate for tractors 

in the time frame. As stated in Section II.B.2.e above, for tractors where single wide tires 

are not appropriate, the manufacturers have additional options available to achieve weight 

reduction, such as body panels and chassis components as documented in the earlier 

discussion. The agencies have extended the list of weight reduction components in order 

to provide the manufacturers with additional means to comply with the combination 
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tractors and to further encourage reductions in vehicle weight. The agencies considered 

increasing the target value beyond 400 pounds given the additional reduction potential 

components identified in the expanded list; however, lacking information on the capacity 

for the industry to change to these light weight components across the board by the 2014

model year, we have decided to maintain the 400 pound target. The agencies intend to 

continue to study the potential for additional weight reductions in our future work 

considering a second phase of truck fuel efficiency and GHG regulations. 

Idle Reduction Technology Application Rate

Idle reduction technologies provide significant reductions in fuel consumption 

and CO2 emissions for Class 8 sleeper cabs and are available on the market today, and 

therefore will be available in the 2014 model year. There are several different 

technologies available to reduce idling. These include APUs, diesel fired heaters, and 

battery powered units. Our discussions with manufacturers indicate that idle technologies 

are sometimes installed in the factory, but it is also a common practice to have the units 

installed after the sale of the truck. We would like to continue to incentivize this practice 

and to do so in a manner that the emission reductions associated with idle reduction 

technology occur in use. Therefore, as proposed, we are allowing only idle emission 

reduction technologies with include an automatic engine shutoff (AES) . We are also 

adopting some override provisions in response to comments we received (as explained 

below). As proposed, we adopting a 100 percent application rate for this technology for 

Class 8 sleeper cabs, even though the current fleet is estimated to have a 30 percent 

application rate. The agencies are unaware of reasons why AES with extended idle 

reduction technologies could not be applied to all tractors with a sleeper cab, except those 

deemed a vocational tractor, in the available lead time. 

One commenter stated the application rate of AES should be less than 100 

percent, but did not recommend an alternative application rate or provide justification for 

a change. The agencies re-evaluated the proposed 100 percent application rate and 

determined that a 100 percent application rate for this technology for Class 8 sleeper cabs 

remains appropriate. The agencies have also considered the many comments which raised 

concerns about the proposed mandatory 5 minute automatic engine shut down without 

override capability (in terms of safety, extreme temperatures and low battery conditions). 

To avoid unintended adverse impacts, we are adopting limited override provisions. Three 

of the five exceptions are similar to those currently in effect under a California Air 

Resources Board (CARB) regulation. CARB provides AES exceptions (or overrides) 

within its existing heavy-duty vehicle anti-idling laws, which were developed to address

these same types of concerns. The exceptions we are adopting include override capability

during exhaust emissions control device regeneration, during engine servicing and 

maintenance, when battery state of charge is too low, in extreme ambient temperatures, 

when engine coolant temperature is too low, and during PTO operation. The RIA 

provides more detail about these final override provisions in Section 2.5.4.3.

The agencies received comment that we should extend the idle reduction benefits 

beyond Class 8 sleepers, including Class 7 tractors and vocational vehicles. The agencies 

reviewed literature to quantify the amount of idling which is conducted outside of 
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hoteling operations. One study, conducted by Argonne National Laboratory, identified 

several different types of trucks which might idle for extended amounts of time during 

the work day.

228

 Idling may occur during the delivery process, queuing at loading docks 

or border crossings, during power take off operations, or to provide comfort during the 

work day. However, the study provided only “rough estimates” of the idle time and 

energy use for these vehicles. The agencies are not able to appropriately develop a 

baseline of workday idling for the other types of vehicles and identify the percent of this 

idling which could be reduced through the use of AES. Absent such information, the 

agencies cannot justify adding substantial cost for AES systems with such uncertain 

benefits.

Vehicle Speed Limiter Application Rate

Vehicle speed limiters may be used as a technology to meet the standard, but in 

setting the standard we assumed a zero percent application rate of vehicle speed limiters. 

Although we believe vehicle speed limiters are a simple, easy to implement, and 

inexpensive technology, we want to leave the use of vehicles speed limiters to the truck 

purchaser. Since truck fleets purchase trucks today with owner set vehicle speed limiters, 

we considered not including VSLs in our compliance model. However, we have 

concluded that we should allow the use of VSLs that cannot be overridden by the 

operator as a means of compliance for vehicle manufacturers that wish to offer it and 

truck purchasers that wish to purchase the technology. In doing so, we are providing 

another means of meeting that standard that can lower compliance cost and provide a 

more optimal vehicle solution for some truck fleets. For example, a local beverage 

distributor may operate trucks in a distribution network of primarily local roads. Under 

those conditions, aerodynamic fairings used to reduce aerodynamic drag provide little 

benefit due to the low vehicle speed while adding additional mass to the vehicle. A 

vehicle manufacturer could choose to install a VSL set a 55 mph for this customer. The 

resulting truck modeled in GEM could meet our final emission standard without the use 

of any specialized aerodynamic fairings. The resulting truck would be optimized for its 

intended application and would be fully compliant with our program all at a lower cost to 

the ultimate truck purchaser.229 

As discussed in Section II.B.2.g above, we have chosen not to base the standards 

on performance of VSLs because of concerns about how to set a realistic application rate 

that avoids unintended adverse impacts. Although we expect there will be some use of 

VSL, currently it is used when the fleet involved decides it is feasible and practicable and 

increases the overall efficiency of the freight system for that fleet operator. However, at 

this point the agencies are not in a position to determine in how many additional 

situations use of a VSL would result in similar benefits to overall efficiency. Therefore, 

the agencies are not premising the final standards on use of VSL, and instead will rely on 

the industry to select VSL when circumstances are appropriate for its use. The agencies 

 

228Gaines, L., A. Vyas, J. Anderson. Estimation of Fuel Use by Idling Commercial Trucks. January 2006

229 Ibid

229 The agencies note that because a VSL value can be input into GEM, its benefits can be directly assessed 

with the model and off cycle credit applications therefore are not necessary even though the standard is not 

based on performance of VSLs (i.e. VSL is an on-cycle technology).
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have not included either the cost or benefit due to VSLs in analysis of the program’s costs 

and benefits. Implementation of this program may provide greater information for using 

this technology in standard setting in the future. Many stakeholders including the 

American Trucking Association have advocated for more widespread use of vehicle 

speed limits to address fuel efficiency and greenhouse gas emissions. The Center for 

Biological Diversity (CBD) argued the agencies should reflect the use of VSLs in setting 

the standard for tractors rather than assuming no VSL use in determining the appropriate 

standard. The agencies have chosen not to do so because, as explained, we are not able at 

this time to quantify to potential loss in utility due to the use of VSLs. Absent this 

information, we cannot make a determination regarding the reasonableness of setting a 

standard based on a particular VSL level. In confirmation, a number of commenters most 

notably the Owner Operator Independent Drivers Association (OOIDA) suggest that 

VSLs could significantly impact the ability of a vehicle to deliver goods against a fixed 

schedule and hence would significantly impact its utility. ATA commented that limited 

flexibility must be built into speed limiters as not to interfere with NHTSA planned 

rulemaking in response to 2006 ATA petition and its 2008 Sustainability Plan. Similar 

comments were received from DTNA requesting that the agencies consider any NHTSA 

safety regulations that may also be regulating VSLs. NHTSA plans to issue a rule in 

2012 addressing the safety performance features of VSLs.

Table III-4 provides the final application rates of each technology broken down 

by weight class, cab configuration, and roof height.
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Table III-4: Final Technology Application Rates for Class 7 and 8 Tractors

Class 7 Class 8

Day Cab Day Cab Sleeper Cab

Low/Mid 

Roof

High 

Roof

Low/Mid 

Roof

High 

Roof

Low 

Roof

Mid 

Roof

High 

Roof

Aerodynamics (Cd)

Bin I 40% 0% 40% 0% 30% 30% 0%

Bin II 60% 30% 60% 30% 70% 70% 10%

Bin III 60% 60% 70%

Bin IV 10% 10% 20%

Bin V 0% 0% 0%

Steer Tires (CRR kg/metric ton)

Baseline 40% 30% 40% 30% 30% 30% 10%

Bin I 50% 60% 50% 60% 60% 60% 70%

Bin II 10% 10% 10% 10% 10% 10% 20%

Drive Tires (CRR kg/metric ton)

Baseline 40% 30% 40% 30% 30% 30% 10%

Bin I 50% 60% 50% 60% 60% 60% 70%

Bin II 10% 10% 10% 10% 10% 10% 20%

Weight Reduction (lb)

400 lb. Weight 

Reduction

100% 100% 100% 100% 100% 100% 100%

Extended Idle Reduction (gram CO2/ton-mile reduction)

AES N/A N/A N/A N/A 100% 100% 100%

Vehicle Speed Limiter

VSL 0% 0% 0% 0% 0% 0% 0%

(iv) Derivation of the Final Tractor Standards

The agencies used the technology inputs and final technology application rates in 

GEM to develop the final fuel consumption and CO2 emissions standards for each 

subcategory of Class 7 and 8 combination tractors. The agencies derived a scenario 

tractor for each subcategory by weighting the individual GEM input parameters included 

in Table III-3 with the application rates in Table III-4. For example, the Cd value for a 

Class 8 Sleeper Cab High Roof scenario case was derived as 10 percent times 0.68 plus 

70 percent times 0.60 plus 20 percent times 0.55, which is equal to a Cd of 0.60. Similar 

calculations were done for tire rolling resistance, weight reduction, idle reduction, and 

vehicle speed limiters. To account for the two final engine standards, the agencies 

assumed a compliant engine in GEM.230 In other words, EPA is finalizing the use of a 

2014 model year fuel consumption map in GEM to derive the 2014 model year tractor 

standard and a 2017 model year fuel consumption map to derive the 2017 model year 

tractor standard.231 The agencies then ran GEM with a single set of vehicle inputs, as 

shown in Table III-5, to derive the final standards for each subcategory. Additional detail 

is provided in the RIA Chapter 2. 

 

230 See Section III.A.2.b below explaining the derivation of the engine standards

231 As explained further in Section V below, EPA would use these inputs in GEM even for engines electing 

to use the alternative engine standard.
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Table III-5: GEM Inputs for the Class 7 and 8 Tractor Standard Setting

Class 7 Class 8

Day Cab Day Cab Sleeper Cab

Low 

Roof

Mid 

Roof

High 

Roof

Low 

Roof

Mid 

Roof

High 

Roof

Low 

Roof

Mid 

Roof

High 

Roof

Aerodynamics (Cd)

0.73 0.84 0.65 0.73 0.84 0.65 0.73 0.84 0.59

Steer Tires (CRR kg/metric ton)

6.99 6.99 6.87 6.99 6.99 6.87 6.87 6.87 6.54

Drive Tires (CRR kg/metric ton)

7.38 7.38 7.26 7.38 7.38 7.26 7.26 7.26 6.92

Weight Reduction (lb)

400 400 400 400 400 400 400 400 400

Extended Idle Reduction (gram CO2/ton-mile reduction)

N/A N/A N/A N/A N/A N/A 5 5 5

Vehicle Speed Limiter

-- -- -- -- -- -- --

Engine

2014/17

MY 11L 

Engine

2014/17 

MY 11L 

Engine

2014/17 

MY 11L 

Engine

2014/17

MY 15L 

Engine

2014/17 

MY 15L 

Engine

2014/17 

MY 15L 

Engine

2014/17 

MY 15L 

Engine

2014/17 

MY 15L 

Engine

2014/17 

MY 15L 

Engine

The level of the 2014 and 2017 model year final standards and percent reduction 

from the baseline for each subcategory are included in Table III-6.
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Table III-6: Final 2014 and 2017 Model Year Tractor Reductions

2014 Model Year CO2 Grams per Ton-Mile

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 107 81 68

Mid Roof 119 88 76

High Roof 124 92 75

2014-2016 Model Year Gallons of Fuel per 1,000 Ton-Mile232

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 10.5 8.0 6.7

Mid Roof 11.7 8.7 7.4

High Roof 12.2 9.0 7.3

2017 Model Year CO2 Grams per Ton-Mile

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 104 80 66

Mid Roof 115 86 73

High Roof 120 89 72

2017 Model Year and Later Gallons of Fuel per 1,000 Ton-Mile

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 10.2 7.8 6.5

Mid Roof 11.3 8.4 7.2

High Roof 11.8 8.7 7.1

A summary of the final technology package costs is included in Table III-7 with 

additional details available in the RIA Chapter 2.

 

232 Manufacturers may voluntarily opt-in to the NHTSA fuel consumption program in 2014 or 2015. If a 

manufacturer opts-in, the program becomes mandatory. 
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Table III-7: Class 7 and 8 Tractor Technology Costs inclusive of Indirect Cost Markups in the 2014 

Model Yeara(2009$)

Class 7 Class 8

Day Cab Day Cab Sleeper Cab

Low/Mid 

Roof

High 

Roof

Low/ Mid 

Roof

High 

Roof

Low 

Roof

Mid 

Roof

High 

Roof

Aerodynamics $675 $924 $675 $924 $962 $983 $1,627

Steer Tires $68 $68 $68 $68 $68 $68 $68

Drive Tires $63 $63 $126 $126 $126 $126 $126

Weight 

Reduction

$1,536 $1,536 $1,980 $1,980 $3,275 $3,275 $1,980

Idle Reduction 

with Auxiliary

Power Unit

-- -- -- -- $3,819 $3,819 $3,819

Air 

Conditioningc

$22 $22 $22 $22 $22 $22 $22

Total $2,364 $2,612 $2,871 $3,119 $8,271 $8,291 $7,641

Notes:

a Costs shown are for the 2014 model year so do not reflect learning impacts which would result in lower 

costs for later model years. For a description of the learning impacts considered in this analysis and how it 

impacts technology costs for other years, refer to Chapter 2 of the RIA (see RIA 2.2.2).

b Note that values in this table include penetration rates. Therefore, the technology costs shown reflect the 

average cost expected for each of the indicated classes. To see the actual estimated technology costs 

exclusive of penetration rates, refer to Chapter 2 of the RIA (see RIA 2.9 in particular).

c EPA’s air conditioning standards are presented in Section II.E.5 above . 

(v) Reasonableness of the Final Standards

The final standards are based on aggressive application rates for control 

technologies which the agencies regard as the maximum feasible for purposes of EISA 

section 32902 (k) and appropriate under CAA section 202 (a) for the reasons given in 

Section (iii) above; see also RIA Chapter 2.5.8.2. These technologies, at the estimated 

application rates, are available within the lead time provided, as discussed in RIA 

Chapter 2.5. Use of these technologies would add only a small amount to the cost of the 

vehicle, and the associated reductions are highly cost effective, an estimated $20 per ton 

of CO2eq per vehicle in 2030 without consideration of the substantial fuel savings.233 

This is even more cost effective than the estimated cost effectiveness for CO2eq removal 

and fuel economy improvements under the light-duty vehicle rule, already considered by 

the agencies to be a highly cost effective reduction.234 Moreover, the cost of controls is 

rapidly recovered due to the associated fuel savings, as shown in the payback analysis 

 

233 See Section VIII.D below.

234 The light-duty rule had an estimated cost per ton of $50 when considering the vehicle program costs 

only and a cost of -$210 per ton considering the vehicle program costs along with fuel savings in 2030. See

75 FR 25515, Table III.H.3-1. 
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included in Table VIII-11 located in Section VIII below. Thus, overall cost per ton of the 

program, considering fuel savings, is negative – fuel savings associated with the rules

more than offset projected costs by a wide margin. See Table VIII-6 in Section VIII 

below. Given that the standards are technically feasible within the lead time afforded by

the 2014 model year, are inexpensive and highly cost effective even without accounting 

for the fuel savings, and have no apparent adverse potential impacts (e.g., there are no 

projected negative impacts on safety or vehicle utility), the final standards represent a 

reasonable choice under section 202(a) of the CAA and the maximum feasible under 

NHTSA’s EISA authority at 49 U.S.C. 32902(k)(2). 

(vi) Alternative Tractor Standards Considered

The agencies are not adopting tractor standards less stringent than the proposed 

standards because the agencies believe these standards are appropriate, highly cost 

effective, and technologically feasible within the rulemaking time frame. 

The agencies considered adopting tractor standards which are more stringent than 

those proposed reflecting increased application rates of the technologies discussed. We 

also considered setting more stringent standards based on the inclusion of hybrid 

powertrains in tractors. We stopped short of finalizing more stringent standards based on 

higher application rates of improved aerodynamic controls and tire rolling resistance 

because we concluded that the technologies would not be compatible with the use profile 

of a subset of tractors which operate in off-road conditions. We have not adopted more 

stringent standards for tractors based on the use of hybrid vehicle technologies, believing 

that additional development and therefore lead-time is needed to develop hybrid systems 

and battery technology for tractors that operate primarily in highway cruise operations. 

We know, for example, that hybrid systems are being researched to capture and return 

energy for tractors that operate in gently rolling hills. However, as discussed above, it is 

not clear to us today that these systems will be generally applicable to tractors in the time 

frame of this regulation. In addition, even if hybrid technologies were generally available 

for these tractors during the MY 2014-2017 period, their costs would be extremely high 

and benefits would be limited given that idle reduction controls already capture many of 

the same emissions. According to the 2010 NAS Report, hybrid powertrains in tractors 

have the potential to improve fuel consumption by 10 percent, but it displaces the 6 

percent reduction for idle reduction technologies, for a net improvement of 4 percent at a 

cost of $25,000 per vehicle.

235

(b) Tractor Engines

(i) Baseline Engine Performance

As noted above, EPA and NHTSA developed the baseline medium- and heavy

heavy-duty diesel engine to represent a 2010 model year engine compliant with the 0.20 

g/bhp-hr NOX standard for on-highway heavy-duty engines. 

 

235 See 2010 NAS Report, Note 197, Page 146. 
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The agencies developed baseline SET values for medium- and heavy heavy-duty

diesel engines based on 2009 model year confidential manufacturer data and from testing 

conducted by EPA. The agencies adjusted the pre-2010 data to represent 2010 model 

year engine maps by using predefined technologies including SCR and other systems that 

are being used in current 2010 model year production. If an engine utilized did not meet 

the 0.20 g/bhp-hr NOX level, then the individual engine’s CO2 result was adjusted to 

accommodate aftertreatment strategies that would result in a 0.20 g/bhp-hr NOX emission 

level as described in RIA Chapter 2.4.2.1. The engine CO2 results were then sales 

weighted within each regulatory subcategory (i.e., medium heavy-duty diesel or heavy 

heavy-duty diesel) to develop an industry average 2010 model year reference engine. 

Although, most of the engines fell within a few percent of this baseline at least one 

engine was more than six percent above this average baseline.

Table III-8: 2010 Model Year Baseline Diesel Engine Performance

CO2 Emissions 

(g/bhp-hr)

Fuel Consumption 

(gallon/100 bhp-hr)

Medium Heavy-Duty Diesel - SET 518 5.09

Heavy Heavy-Duty Diesel - SET 490 4.81

(ii) Engine Technology Package Effectiveness 

The MHD and HHD diesel engine technology package for the 2014 model year 

includes engine friction reduction, improved aftertreatment effectiveness, improved 

combustion processes, and low temperature EGR system optimization. The agencies 

considered improvements in parasitic and friction losses through piston designs to reduce 

friction, improved lubrication, and improved water pump and oil pump designs to reduce 

parasitic losses. The aftertreatment improvements are available through lower 

backpressure of the systems and optimization of the engine-out NOX levels. 

Improvements to the EGR system and air flow through the intake and exhaust systems, 

along with turbochargers can also produce engine efficiency improvements. We note that 

individual technology improvements are not additive due to the interaction of 

technologies. The agencies assessed the impact of each technology over each of the 13 

SET modes to project an overall weighted SET cycle improvement in the 2014 model 

year of 3 percent, as detailed in RIA Chapter 2.4.2.9 through 2.4.2.14. All of these 

technologies represent engine enhancements already developed beyond the research 

phase and are available as “off the shelf” technologies for manufacturers to add to their 

engines during the engine’s next design cycle. We have estimated that manufacturers 

will be able to implement these technologies on or before the 2014 engine model year. 

The agencies adopted a standard that therefore reflects a 100 percent application rate of 

this technology package. The agencies gave consideration to finalizing a more stringent 

standard based on the application of mechanical turbocompounding by model year 2014, 

a mechanical means of waste heat recovery, but concluded that manufacturers would 

have insufficient lead-time to complete the necessary product development and validation 

work necessary to include this technology. Implementing turbocompounding into an 

engine design must be done through a significant redesign of the engine architecture a 
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process that typically takes 4 to 5 years. Hence, we believe that turbocompounding is a 

more appropriate technology for the agencies to consider in the 2017 timeframe. 

As explained earlier, EPA’s heavy-duty highway engine standards for criteria 

pollutants apply in three year increments. The heavy-duty engine manufacturer product 

plans have fallen into three year cycles to reflect these requirements. The agencies are 

finalizing fuel consumption and CO2 emission standards recognizing the opportunity for 

technology improvements over this time frame (specifically, the addition of 

turbocompounding to the engine technology package) while reflecting the typical heavyduty engine manufacturer product plan redesign and refresh cycles. Thus, the agencies 

are finalizing a more stringent standard for heavy-duty engines beginning in the 2017 

model year.

The MHDD and HHDD engine technology package for the 2017 model year 

includes the continued development of the 2014 model year technology package 

including refinement of the aftertreatment system plus turbocompounding. The agencies 

calculated overall reductions in the same manner as for the 2014 model year package. 

The weighted SET cycle improvements lead to a 6 percent reduction on the SET cycle, as 

detailed in RIA Chapter 2.4.2.12. The agencies’ final standards are premised on a 100 

percent application rate of this technology package. 

Commenters noted that the National Academy of Sciences (NAS) study indicates 

that additional technology improvements can be made to heavy-duty engines in MY 2014 

and 2017. For diesel engine standards, the agencies evaluated the following 

technologies: combustion system optimization, turbocharging and air handling systems, 

engine parasitic and friction reduction, integrated aftertreatment systems, electrification, 

and waste heat recovery. 

The agencies carefully evaluated the research supporting the NAS report and its 

recommendations and incorporated them to the extent practicable in the development of 

the HD program. While the NAS report suggests that greater engine improvements could 

be achieved by the use of technologies such as improved emission control systems and 

turbo-compounding than do the agencies in this final action, we believe the standards 

being finalized represent the most stringent technically feasible for diesel engines used in 

tractors and vocational vehicles in the 2014 to 2017 model year time frame. The NAS 

study concluded that tractor engine fuel consumption can be reduced by approximately

15 percent in the 2015 to 2020 time frame and vocational engine fuel consumption can be 

reduced by approximately 10 to 17 percent in the same time frame compared to a 2008 

engine baseline.236 Throughout this presentation, the agencies’ projections of 

performance improvements are measured relative to a 2010 engine performance baseline 

that itself reflects a four to five percent improvement over the 2008 engine baseline used 

by NAS. Based on a review of existing studies, NAS study authors found a range of 

reduction potential exists for improvements in combustion efficiency, electrification of 

accessories; improved emission control systems; and turbocompounding. The study

 

236 National Research Council, "Technologies and Approaches to Reducing the Fuel Consumption of 

Medium- and Heavy-Duty Vehicles Figure S-1, page 4, National Acedemies Press, 2011
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found that improvements in combustion efficiency can provide reductions of 1 percent to 

4 percent; electrification of accessories can provide reductions of 2 percent to 5 percent in 

a hybridized vehicle; improved emission control systems can provide a 1 percent to 4 

percent improvement (depending on whether the improvement is to the EGR or SCR 

system); and a 2.5 percent to 10 percent reduction is possible with mechanical or 

electrical turbocompounding. While the reductions being finalized in this regulation are 

lower than those published in the NAS study, the agencies believe that the percent 

reductions being finalized in these rules are consistent with the findings of the NAS 

study. The reasons for this are as follows. 

First, some technologies cannot be used by all manufacturers. For example, 

improved SCR conversion efficiency, was projected by NAS to provide a 3 percent to 4 

percent improvement in fuel consumption. Conversely, low temperature EGR was found 

to provide only a one percent improvement. While the majority of manufacturers do use 

SCR systems and will be able to realize the 3 percent to 4 percent improvement, not all 

manufacturers use SCR for NOX aftertreatment. Manufacturers that do not use SCR 

aftertreatment systems would only be able to realize the 1 percent improvement from low 

temperature EGR. The agencies need to take into consideration the entire market in 

setting the stringency of the standards and, in assessing feasibility and cost, cannot 

assume that all manufacturers will be able to use all technologies. 

Second, significant technical advances may be needed in order to realize the 

upper end of estimates for some technologies. For example, studies evaluated by NAS on 

turbocompounding found that a 2.5 percent to 10 percent reduction is feasible. However, 

only one system is available commercially and this system provides reductions on the 

low end of this range.237 Little technical information is available on the systems that 

achieve reductions in the upper range for turbocompounding. These systems are based 

on proprietary designs the improvement results for which have not yet been replicated by 

other companies or organizations. The agencies are assuming that all tractor engine 

manufacturers will use turbocompounding by 2017 model year. This will require a 

significant change in the design of heavy-duty tractor engines, one that represents the 

maximum technically feasible standard even at the low end of the assumed improvement 

spectrum. 

Finally, different duty cycles used in the evaluation of medium- and heavy-duty

engine technologies can affect reported fuel consumption improvements. For example, 

some technologies are dependent on high load conditions to provide the greatest 

reductions. The duty cycles used to evaluate some of the technologies considered by 

NAS differed significantly from that used by the agencies in the modeling for this 

rulemaking. Maximum and average speed was higher in some of the cycles used in the 

studies, for example, and one result was demonstrated on a nonroad engine cycle. In 

another example, the effectiveness of turbocompounding when evaluated on a duty cycle 

with higher engine load can show a greater reduction potential than when evaluated with 

a lower engine load. In addition, technologies such as improvements to cooling fans, air 

 

237 NAS 2010, page 53 cites Detroit Diesel Corporation, DD15 Brochure, DDC-EMC-BRO-0003-0408, 

April 2008.
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compressors, and air conditioning systems will not be demonstrated using the engine 

dynamometer test procedures being adopted in this final action because those 

components are not installed on the engine during the testing. The agencies selected the 

duty cycles for analysis, and for the final standards, that we believed best suited tractor 

engines. 

The agencies selected engine technologies and the estimated fuel reduction 

percentages for setting the standards. For the reasons stated above, the agencies believe 

the technologies and required improvements in fuel consumption represent the maximum 

feasible improvement, and are appropriate, cost-effective, and technologically feasible.

We gave consideration to finalizing an even more stringent standard based on the 

use of waste heat recovery via a Rankine cycle (also called bottoming cycle) but 

concluded that there is insufficient lead-time between now and 2017 for this promising 

technology to be developed and applied generally to all heavy-duty engines. TIAX noted 

in their report to the NAS committee that the engine improvements beyond 2015 model 

year included in their report are highly uncertain, though they include Rankine cycle type 

waste heat recovery as applicable sometime between 2016 and 2020.238 The Department 

of Energy is working with industry to develop waste heat recovery systems for heavyduty engines. At the Diesel Engine-Efficiency and Emissions Research (DEER) 

conference in 2010, Caterpillar presented details regarding their waste heat recovery

systems development effort. In their presentation, Caterpillar clearly noted that the work 

is a research project and therefore does not imply commercial viability.239 At the same 

conference, Concepts NREC presented a status of exhaust energy recovery in heavy-duty 

engines. The scope of Concepts NREC included the design and development of 

prototype parts.240 Cummins, also in coordination with DOE, is also active in developing 

exhaust energy recovery systems. Cummins made a presentation to the DEER 

conference in 2009 providing an update on their progress which highlighted opportunities 

to achieve a 10 percent engine efficiency improvement during their research, but 

indicated the need to focus their future development on areas with the highest recovery

opportunities (such as EGR, exhaust, and charge air).241 Cummins also indicated that 

future development would focus on reducing the high additional costs and system 

complexity. Based upon the assessment of this information, the agencies did not include 

these technologies in determining the stringency of the final standards. However, we do 

believe the bottoming cycle approach represents a significant opportunity to reduce fuel 

consumption and GHG emissions in the future. EPA and NHTSA are therefore both 

 

238 See TIAX, Note 198, Page 4-29.

239 Kruiswyk, R. “An Engine System Approach to Exhaust Waste Heat Recovery.” Presented at DOE 

DEER Conference on September 29, 2010. Last viewed on May 11, 2011 at 

http://www1.eere.energy.gov/vehiclesandfuels/pdfs/deer_2010/wednesday/presentations/deer10_kruiswyk.

pdf

240 Cooper, D,, N. Baines, N. Sharp. “Organic Rankine Cycle Turbine for Exhaust Energy Recovery in a 

Heavy Truck Engine.” Presented at the 2010 DEER Conference. Last viewed on May 11, 2011 at 

http://www1.eere.energy.gov/vehiclesandfuels/pdfs/deer_2010/wednesday/presentations/deer10_baines.pdf

241 Nelson, C. “Exhaust Energy Recovery.” Presented at the DOE DEER Conference on August 5, 2009. 

Last viewed on May 11, 2011 at 

http://www1.eere.energy.gov/vehiclesandfuels/pdfs/deer_2009/session5/deer09_nelson_1.pdf
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finalizing provisions for advanced technology credits described in Section IV to create 

incentives for manufacturers to continue to invest to develop this technology.

(iii) Derivation of Engine Standards 

EPA developed the final 2014 model year CO2 emissions standards (based on the 

SET cycle) for diesel engines by applying the three percent reduction from the 

technology package (just explained above) to the 2010 model year baseline values 

determined using the SET cycle. EPA developed the 2017 model year CO2 emissions 

standards for diesel engines while NHTSA similarly developed the 2017 model year 

diesel engine fuel consumption standards by applying the 6 percent reduction from the 

2017 model year technology package (reflecting performance of turbocompounding plus 

the 2014 MY technology package) to the 2010 model year baseline values. The final 

standards are included in Table III-9.

Table III-9: Final Diesel Engine Standards Over the SET Cycle

Model Year MHD Diesel 

Engine 

HHD Diesel 

Engine

2014 – 2016 CO2 Standard (g/bhp-hr) 502 475

Voluntary Fuel Consumption Standard 

(gallon/100 bhp-hr)

4.93 4.67

2017 and later CO2 Standard (g/bhp-hr) 487 460

Fuel Consumption (gallon/100 bhp-hr) 4.78 4.52

(iv) Engine Technology Package Costs

EPA has historically used two different approaches to estimate the indirect costs 

(sometimes called fixed costs) of regulations including costs for product development, 

machine tooling, new capital investments and other general forms of overhead that do not 

change with incremental changes in manufacturing volumes. Where the Agency could 

reasonably make a specific estimate of individual components of these indirect costs, 

EPA has done so. Where EPA could not readily make such an estimate, EPA has instead 

relied on the use of markup factors referred to as indirect cost multipliers (ICMs) to 

estimate these indirect costs as a ratio of direct manufacturing costs. In general, EPA has 

used whichever approach it believed could provide the most accurate assessment of cost 

on a case by case basis. The agencies’ general approach used elsewhere in this action 

(for HD pickup trucks, gasoline engines, combination tractors, and vocational vehicles) 

estimates indirect costs based on the use of ICMs. See also 75 FR 25376. We have used 

this approach generally because these standards are based on installing new parts and 

systems purchased from a supplier. In such a case, the supplier is conducting the bulk of 

the research and development on the new parts and systems and including those costs in 

the purchase price paid by the original equipment manufacturer. In this situation, we 

believe that the ICM approach provides an accurate and clear estimate of the additional 

indirect costs borne by the manufacturer. 
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For the heavy-duty diesel engine segment, however, the agencies do not consider 

this model to be the most appropriate because the primary cost is not expected to be the 

purchase of parts or systems from suppliers or even the production of the parts and 

systems, but rather the development of the new technology by the original equipment 

manufacturer itself. Most of the technologies the agencies are projecting the heavy-duty 

engine manufacturers will use for compliance reflect modifications to existing engine 

systems rather than wholesale addition of technology (e.g., improved turbochargers rather 

than adding a turbocharger where it did not exist before as was done in our light-duty

joint rulemaking in the case of turbo-downsizing). When the bulk of the costs come from 

refining an existing technology rather than a wholesale addition of technology, a specific 

estimate of indirect costs may be more appropriate. For example, combustion 

optimization may significantly reduce emissions and cost a manufacturer millions of 

dollars to develop but will lead to an engine that is no more expensive to produce. Using 

a bill of materials approach would suggest that the cost of the emissions control was zero 

reflecting no new hardware and ignoring the millions of dollars spent to develop the 

improved combustion system. Details of the cost analysis are included in the RIA 

Chapter 2. The agencies did not receive any comments regarding the cost approach used 

in the proposal. 

The agencies developed the engineering costs for the research and development of 

diesel engines with lower fuel consumption and CO2 emissions. The aggregate costs for 

engineering hours, technician support, dynamometer cell time, and fabrication of 

prototype parts are estimated at $6.8 million (2009 dollars) per manufacturer per year 

over the five years covering 2012 through 2016. In aggregate, this averages out to $284 

per engine during 2012 through 2016 using an annual sales volume of 600,000 light-, 

medium- and heavy-HD engines. The agencies received comments from Horriba 

regarding the assumption the agencies used in the proposal that said manufacturers would 

need to purchase new equipment for measuring N2O and the associated costs. Horriba 

provided information regarding the cost of stand-alone FTIR instrumentation (estimated 

at $50,000 per unit) and cost of upgrading existing emission measurement systems with 

NDIR analyzers (estimated at $25,000 per unit). The agencies further analyzed our 

assumptions along with Horriba’s comments. Thus, we have revised the equipment costs 

estimates and assumed that 75 percent of manufacturers would update existing equipment 

while the other 25 percent would require new equipment. The agencies are estimating 

costs of $63,087 (2009 dollars) per engine manufacturer per engine subcategory (light-, 

medium- and heavy-HD) to cover the cost of purchasing photo-acoustic measurement 

equipment for two engine test cells. This would be a one-time cost incurred in the year 

prior to implementation of the standard (i.e., the cost would be incurred in 2013). In 

aggregate, this averages out to less than $1 per engine in 2013 using an annual sales 

volume of 600,000 light-, medium- and heavy-HD engines.

Where we projected that additional new hardware was needed to the meet the 

final standards, we developed the incremental costs for those technologies and marked 

them up using the ICM approach. Table III-10 below summarizes those estimates of cost 

on a per item basis. All costs shown in Table III-18, below, include a low complexity

ICM of 1.15 and flat-portion of the curve learning is considered applicable to each 

technology.
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Table III-10: Heavy-duty Diesel Engine Component Costs for Combination Tractorsa(2009$)

Technology 2014 2017

Cylinder Head $6 $6

Turbo efficiency $18 $17

EGR cooler $4 $3

Water pump $91 $84

Oil pump $5 $4

Fuel pump $5 $4

Fuel rail $10 $9

Fuel injector $11 $10

Piston $3 $3

Engine Friction Reduction of Valvetrain $82 $76

Turbo-compounding (engines placed in combination tractors only) $0 $875

MHHD and HHDD Total (combination tractors) $234 $1,091

Note:

a Costs for aftertreatment improvements for MH and HH diesel engines are covered via the 

engineering costs (see text). For LH diesel engines, we have included the cost of aftertreatment 

improvements as a technology cost.

The overall diesel engine technology package cost for an engine being placed in a 

combination tractor is $234 in the 2014 model year and $1,091in the 2017 model year. 

(v) Reasonableness of the Final Standards 

The final engine standards appear to be reasonable and consistent with the 

agencies’ respective statutory authorities. With respect to the 2014 and 2017 MY 

standards, all of the technologies on which the standards are predicated have already been 

demonstrated in some capacity and their effectiveness is well documented. The final

standards reflect a 100 percent application rate for these technologies. The costs of 

adding these technologies remain modest across the various engine classes as shown in 

Table III-10. Use of these technologies would add only a small amount to the cost of the 

vehicle,242 and the associated reductions are highly cost effective, an estimated $20 per 

ton of CO2eq per vehicle.243 This is even more cost effective than the estimated cost 

effectiveness for CO2eq removal under the light-duty vehicle rule, already considered by 

the agencies to be a highly cost effective reduction.244 Even the more expensive 2017 

MY final standard still represents only a small fraction of the vehicle’s total cost and is 

even more cost effective than the light-duty vehicle rule. Moreover, costs are more than 

offset by fuel savings. Accordingly, EPA and NHTSA view these standards as reflecting 

an appropriate balance of the various statutory factors under section 202(a) of the CAA 

and under NHTSA’s EISA authority at 49 U.S.C. 32902(k)(2).

 

242 Sample 2010 MY day cabs are priced at $89,000 while 2010 MY sleeper cabs are priced at $113,000. 

See page 3 of ICF’s “Investigation of Costs for Strategies to Reduce Greenhouse Gas Emissions for HeavyDuty On-Road Vehicles.” July 2010.

243 See Tractor CO2 savings and technology costs in Table 7-5 in RIA Chapter 7.

244 The light-duty rule had an estimated cost per ton of $50 when considering the vehicle program costs 

only and a cost of -$210 per ton considering the vehicle program costs along with fuel savings in 2030. See

75 FR 25515, Table III.H.3-1. 
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(vi) Temporary Alternative Standard for Certain Engine Families 

As discussed above in Section II.B (2)(b), notwithstanding the general 

reasonableness of the final standards, the agencies recognize that heavy-duty engines 

have never been subject to GHG or fuel consumption (or fuel economy) standards and 

that such control has not necessarily been an independent priority for manufacturers. The 

result is that there are a group of legacy engines with emissions higher than the industry

baseline for which compliance with the final 2014 MY standards may be more 

challenging and for which there may simply be inadequate lead time. The issue is not 

whether these engines’ GHG and fuel consumption performance cannot be improved by

utilizing the technology packages on which the final standards are based. Those 

technologies can be utilized by all diesel engines installed in tractors and the same degree 

of reductions obtained. Rather the underlying base engine components of these engines 

reflect designs that are decades old and therefore have base performance levels below 

what is typical for the industry as a whole today. Manufacturers have been gradually 

replacing these legacy products with new engines. Engine manufacturers have indicated 

to the agencies they will have to align their planned replacement of these products with 

our final standards and at the same time add additional technologies beyond those 

identified by the agencies as the basis for the final standard. Because these changes will 

reflect a larger degree of overall engine redesign, manufacturers may not be able to 

complete this work for all of their legacy products prior to model year 2014. To pull 

ahead these already planned engine replacements would be impossible as a practical 

matter given the engineering structure and lead-times inherent in the companies’ existing 

product development processes. We have also concluded that the use of fleet averaging 

would not address the issue of legacy engines because each manufacturer typically

produces only a limited line of MHDD and HHDD engines. Because there are ample 

fleetwide averaging opportunities for heavy-duty pickups and vans, the agencies do not 

perceive similar difficulties for these vehicles.

Facing a similar issue in the light-duty vehicle rule, EPA adopted a Temporary 

Lead Time Allowance provision whereby a limited number of vehicles of a subset of 

manufacturers would meet an alternative standard in the early years of the program, 

affording them sufficient lead time to meet the more stringent standards applicable in 

later model years. See 75 FR 25414-25418. The agencies are finalizing a similar 

approach here. As explained above in Section II. B.(2)(b), the agencies are finalizing a 

regulatory alternative whereby a manufacturer, for a limited period, would have the 

option to comply with a unique standard requiring the same level of reduction of 

emissions (i.e., percent removal) and fuel consumption as otherwise required, but the 

reduction would be measured from its own 2011 model year baseline. We are thus 

finalizing an optional standard whereby manufacturers would elect to have designated 

engine families meet a standard of 3 percent reduction from their 2011 baseline emission 

and fuel consumption levels for that engine family or engine subcategory. Our 

assessment is that this three percent reduction is appropriate based on use of similar

technology packages at similar cost as we have estimated for the primary program. In the 

NPRM, we solicited comment on extending this alternative (See 75 FR at 74202). As 

explained earlier, we have decided not to allow the alternative standard to continue past 

the 2016 MY. By this time, the engines should have gone through a redesign cycle which 
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will allow manufacturers to replace those legacy engines which resulted in abnormally

high baseline emission and fuel consumption levels and to achieve the MY 2017

standards which would be feasible using the technology package set out above (optimized 

NOX aftertreatment, improved EGR, reductions in parasitic losses, and turbocharging). 

Manufacturers would, of course, be free to adopt other technology paths which meet the 

final MY 2017 standards. 

Since the alternative standard is premised on the need for additional lead time, 

manufacturers would first have to utilize all available flexibilities which could otherwise 

provide that lead time. Thus, as proposed, the alternative would not be available unless 

and until a manufacturer had exhausted all available credits and credit opportunities, and 

engines under the alternative standard could not generate credits. See also 75 FR 25417-

25419 (similar approach for vehicles which are part of Temporary Lead Time Allowance 

under the light-duty vehicle rule). We are finalizing that manufacturers can select engine 

families for this alternative standard without agency approval, but are requiring that 

manufacturers notify the agency of their choice and also requiring manufacturers to 

include in that notification a demonstration that it has exhausted all available credits and 

credit opportunities. Manufacturers would also have to demonstrate their 2011 baseline 

calculations as part of the certification process for each engine family for which the 

manufacturer elects to use the alternative standard. See Section V.C.1(b)(i) below.

(vii) Other Engine Standards Considered

The agencies are not finalizing engine standards less stringent than the final 

standards because the agencies believe these final standards are appropriate, highly cost 

effective, and technologically feasible, as just described.

The agencies considered finalizing engine standards which are more stringent. 

Since the final standards reflect 100 percent utilization of the various technology

packages, some additional technology would have to be added. The agencies are 

finalizing 2017 model year standards based on the use of turbocompounding. As 

discussed above in Section III.A.2.b.iii, the agencies considered the inclusion of more 

advanced heat recovery systems, such as Rankine or bottoming cycles, which would 

provide further reductions. However, the agencies are not finalizing this level of 

stringency because our assessment is that these technologies would not be available for 

production by the 2017 model year. 

B. Heavy-Duty Pickup Trucks and Vans

This section describes the process the agencies used to develop the standards the 

agencies are finalizing for HD pickups and vans. We started by gathering available 

information about the fuel consumption and CO2 emissions from recent model year 

vehicles. The core portion of this information comes primarily from EPA’s certification 

databases, CFEIS and Verify, which contain the publicly available data245 regarding 

emission and fuel economy results. This information is not extensive because 

manufacturers have not been required to chassis test HD diesel vehicles for EPA’s 

 

245 http://www.epa.gov/otaq/certdata.htm
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criteria pollutant emissions standards, nor have they been required to conduct any testing 

of heavy-duty vehicles on the highway cycle. Nevertheless, enough certification activity

has occurred for diesels under EPA’s optional chassis-based program, and, due to a 

California NOX requirement for the highway test cycle, enough test results have been 

voluntarily reported for both diesel and gasoline vehicles using the highway test cycle, to 

yield a reasonably robust data set. To supplement this data set, for purposes of this 

rulemaking EPA initiated its own testing program using in-use vehicles. This program 

and the results from it thus far are described in a memorandum to the docket for this 

rulemaking.246

Heavy-duty pickup trucks and vans are sold in a variety of configurations to meet 

market demands. Among the differences in these configurations that affect CO2

emissions and fuel consumption are curb weight, GVWR, axle ratio, and drive wheels 

(two-wheel drive or four-wheel drive). Because the currently-available test data set does 

not capture all of these configurations, it is necessary to extend that data set across the 

product mix using adjustment factors. In this way a test result from, say a truck with 

two-wheel drive, 3.73:1 axle ratio, and 8000 lb test weight, can be used to model 

emissions and fuel consumption from a truck of the same basic body design, but with 

four-wheel drive, a 4.10:1 axle ratio, and 8,500 lb test weight. The adjustment factors are 

based on data from testing in which only the parameters of interest are varied. These 

parameterized adjustments and their basis are also described in a memorandum to the 

docket for this rulemaking.247

The agencies requested and received from each of the three major manufacturers 

confidential information for each model and configuration, indicating the values of each 

of these key parameters as well as the annual production (for the U.S. market). 

Production figures are useful because, under our final standards for HD pickups and vans, 

compliance is judged on the basis of production-weighted (corporate average) emissions 

or fuel consumption level, not individual vehicle levels. For consistency and to avoid 

confounding the analysis with data from unusual market conditions in 2009, the 

production and vehicle specification data is from the 2008 model year. We made the

simplifying assumption that these sales figures reasonably approximate future sales for 

purposes of this analysis.

One additional assessment was needed to make the data set useful as a baseline 

for the standards selection. Because the appropriate standards are determined by

applying efficiency-improving technologies to the baseline fleet, it is necessary to know 

the level of penetration of these technologies in the latest model year (2010). This 

information was also provided confidentially by the manufacturers. Generally, the 

agencies found that the HD pickup and van fleet was at a roughly consistent level of 

technology application, with (1) the transition from 4-speed to 5- or 6-speed automatic 

transmissions mostly accomplished, (2) coupled cam phasing to achieve variable valve 

 

246 Memorandum from Cleophas Jackson, U.S.EPA, to docket EPA-HQ-OAR-2010-0162, "Heavy-Duty 

Greenhouse Gas and Fuel Consumption Test Program Summary", September 20, 2010.

247 Memorandum from Anthony Neam and Jeff Cherry, U.S.EPA, to docket EPA-HQ-OAR-2010-0162, 

October 18, 2010.
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control on gasoline engines likewise mostly in place,248 and (3) substantial remaining 

potential for optimizing catalytic diesel NOX aftertreatment to improve fuel economy (the 

new heavy-duty NOX standards having taken effect in the 2010 model year).

Taking this 2010 baseline fleet, and applying the technologies determined to be 

feasible and appropriate by the 2018 model year, along with their effectiveness levels, the 

agencies could then make a determination of appropriate final standards. The assessment 

of feasibility, described immediately below, takes into account the projected costs of 

these technologies. The derivation of these costs, largely based on analyses developed in 

the light-duty GHG and fuel economy rulemaking, are described in Section III.B(3).

Our assessment concluded that the technologies that the agencies considered 

feasible and appropriate for HD pickups and vans could be consistently applied to 

essentially all vehicles across this sector by the 2018 model year. Therefore we did not 

apply varying penetration rates across vehicle types and models in developing and 

evaluating the final standards. 

Since the manufacturers of HD pickups and vans generally only have one basic 

pickup truck and van with different versions ((i.e., different wheel bases, cab sizes, twowheel drive, four-wheel drive, etc.) and do not have the flexibility of the light-duty fleet 

to coordinate model improvements over several years, changes to the HD pickups and 

vans to meet new standards must be carefully planned with the redesign cycle taken into 

account. The opportunities for large-scale changes (e.g., new engines, transmission, 

vehicle body and mass) thus occur less frequently than in the light-duty fleet, typically at 

spans of 8 or more years. However, opportunities for gradual improvements not 

necessarily linked to large scale changes can occur between the redesign cycles. 

Examples of such improvements are upgrades to an existing vehicle model’s engine, 

transmission and aftertreatment systems. Given this long redesign cycle and our 

understanding with respect to where the different manufacturers are in that cycle, the 

agencies have initially determined that the full implementation of the final standards 

would be feasible and appropriate by the 2018 model year. 

Although we did not determine a technological need for less than full 

implementation of any technology, we did decide that a phased implementation schedule 

would be appropriate to accommodate manufacturers’ redesign workload and product 

schedules, especially in light of this sector’s relatively low sales volumes and long 

product cycles. We did not determine a specific cost of implementing the final standards 

immediately in 2014 without a phase-in, but we assessed it to be much higher than the 

cost of the phase-in we are finalizing, due to the workload and product cycle disruptions 

it would cause, and also due to manufacturers’ resulting need to develop some of these 

technologies for heavy-duty applications sooner than or simultaneously with light-duty

development efforts. See generally 75 FR 25467-25468 explaining why attempting 

major changes outside the redesign cycle period raises very significant issues of both 

feasibility and cost. On the other hand, waiting until 2018 before applying any new 

 

248 See Section III.B(2)(a) for our response to comments arguing for inclusion of this technology in the list 

of technologies needed to meet the standards.
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standards could miss the opportunity to achieve meaningful and cost-effective early 

reductions not requiring a major product redesign.

The final phase-in schedule, 15-20-40-60-100 percent in 2014-2015-2016-2017-

2018, respectively, was chosen to strike a balance between meaningful reductions in the 

early years (reflecting the technologies’ penetration rates of 15 and 20 percent) and 

providing manufacturers with needed lead time via a gradually accelerating ramp-up of 

technology penetration. 249 By expressing the final phase-in in terms of increasing 

fleetwide stringency for each manufacturer, while also providing for credit generation 

and use (including averaging, carry-forward, and carry-back), we believe our program 

affords manufacturers substantial flexibility to satisfy the phase-in through a variety of 

pathways, among them, the gradual application of technologies across the fleet 

(averaging a fifth of total production in each year), greater application levels on only a 

portion of the fleet, or a mix of the two.

We considered setting more stringent standards that would require the application 

of additional technologies by 2018. We expect, in fact, that some of these technologies 

may well prove feasible and cost-effective in this time frame, and may even become 

technologies of choice for individual manufacturers. This dynamic has played out in 

EPA programs before and highlights the value of setting performance-based standards 

that leave engineers the freedom to find the most cost-effective solutions. 

However, the agencies do believe that at this stage there is not enough 

information to conclude that the additional technologies provide an appropriate basis for 

standard-setting. For example, we believe that 42V stop-start systems can be applied to 

gasoline vehicles with significant GHG and fuel consumption benefits, but we recognize 

that there is uncertainty at this time over the cost-effectiveness of these systems in heavyduty applications, and legitimate concern with customer acceptance of vehicles with high 

GCWR towing large loads that would routinely stop running at idle. Hybrid electric 

technology likewise could be applied to heavy-duty vehicles, and in fact has already been 

so applied on a limited basis. However, the development, design, and tooling effort 

needed to apply this technology to a vehicle model is quite large, and seems less likely to 

prove cost-effective in this time frame, due to the small sales volumes relative to the 

light-duty sector. Here again, potential customer acceptance would need to be better 

understood because the smaller engines that facilitate much of a hybrid’s benefit are 

typically at odds with the importance pickup trucks buyers place on engine horsepower 

and torque, whatever the vehicle’s real performance.

We also considered setting less stringent standards calling for a more limited set 

of applied technologies. However, our assessment concluded with a high degree of 

confidence that the technologies on which the final standards are premised are clearly 

available at reasonable cost in the 2014-2018 time frame, and that the phase-in and other 

 

249 The NHTSA program provides voluntary standards for model years 2014 and 2015. NHTSA and EPA 

are also providing an alternative standards phase-in that meets EISA’s requirement for three years of 

regulatory stability. See Section II.C.d.ii for a more detailed discussion.
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flexibility provisions allow for their application in a very cost-effective manner, as 

discussed in this section below.

More difficult to characterize is the degree to which more or less stringent 

standards might be appropriate because of under- or over-estimating effectiveness of the 

technologies whose performance is the basis of the final standards. Our basis for these 

estimates is described in the following Section III. B. (1) . Because for the most part 

these technologies have not yet been applied to HD pickups and vans, even on a limited 

basis, we are relying to some degree on engineering judgment in predicting their 

effectiveness. Even so, we believe that we have applied this judgment using the best 

information available, primarily from our recent rulemaking on light-duty vehicle GHGs 

and fuel economy, and have generated a robust set of effectiveness values. 

(1) What Technologies Did the Agencies Consider?

The agencies considered over 35 vehicle technologies that manufacturers could 

use to improve the fuel consumption and reduce CO2 emissions of their vehicles during 

MYs 2014-2018. The majority of the technologies described in this section is readily

available, well known, and could be incorporated into vehicles once production decisions 

are made. Several of the technologies have already been introduced into the heavy-duty

pickup and van market (i.e., variable valve timing, improved accessories, etc.) in a 

limited number of applications. Other technologies considered may not currently be in 

production, but are beyond the research phase and under development, and are expected 

to be in production in highway vehicles over the next few years. These are technologies 

which are capable of achieving significant improvements in fuel economy and reductions 

in CO2 emissions, at reasonable costs. The agencies did not consider technologies in the 

research stage because there is insufficient time for such technologies to move from 

research to production during the model years covered by this final action.

The agencies received comments regarding applicability of certain advanced 

technologies described in the TIAX 2009 report submitted to NAS. Specifically

mentioned were turbocharging and downsizing of gasoline vehicles and hydraulic hybrid 

systems. While turbocharging and downsizing of gasoline vehicles was a principal 

technology underlying the standards in the light-duty rule, the agencies determined that in 

the realm of heavy-duty vehicles, this approach provides much less benefit to vehicles 

which are required to regularly operate at high and sustained loads. In light-duty

applications, downsizing of a typically oversized engine largely results in benefits mainly 

under partial and light load conditions. This approach is more applicable to light-duty

vehicles because they infrequently require high or full power. Further, while turbo 

downsizing was already occurring in a portion of the light-duty fleet, it has not been 

demonstrated in the heavy-duty fleet, likely due to concerns with durability of this 

technology in the sustained high-load duty cycles frequently encountered. Similarly, 

other light-duty technologies (i.e., cylinder deactivation, engine start stop) were also 

determined to not be compatible with the duty cycle of heavy-duty vehicles for similar 

reasons. Due to the relatively aggressive implementation of this program and the lack of 

commercialization in the heavy-duty market, hydraulic hybrid systems were not 

considered a technology that could be implemented in the time frame of this program for 
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the HD pickup and van sector. The fact that no HD pickup or van hydraulic hybrids have 

been, or are the verge of being marketed makes their widespread introduction before the 

MY 2018 final year of the phase-in very unlikely. 

The technologies considered in the agencies’ analysis are briefly described below. 

They fall into five broad categories: engine technologies, transmission technologies, 

vehicle technologies, electrification/accessory technologies, and hybrid technologies.

In this class of trucks and vans, diesel engines are installed in about half of all 

vehicles. The ratio between gasoline and diesel engine purchases by consumers has 

tended to track changes in the overall cost of oil and the relative cost of gasoline and 

diesel fuels. When oil prices are higher, diesel sales tend to increase. This trend has 

reversed when oil prices fall or when diesel fuel prices are significantly higher than 

gasoline. In the context of our technology discussion for heavy-duty pickups and vans, 

we are treating gasoline and diesel engines separately so each has a set of baseline 

technologies. We discuss performance improvements in terms of changes to those 

baseline engines. Our cost and inventory estimates contained elsewhere reflect the 

current fleet baseline with an appropriate mix of gasoline and diesel engines. Note that 

we are not basing the final standards on a targeted switch in the mix of diesel and 

gasoline vehicles. We believe our final standards require similar levels of technology

development and cost for both diesel and gasoline vehicles. Hence the final program 

does not force, nor does it discourage, changes in a manufacturer’s fleet mix between 

gasoline and diesel vehicles. Although we considered setting a single standard based on 

the performance level possible for diesel vehicles, we are not finalizing such an approach 

because the potential disruption in the HD pickup and van market from a forced shift 

would not be justified. Types of engine technologies that improve fuel efficiency and 

reduce CO2 emissions include the following:

 Low-friction lubricants – low viscosity and advanced low friction lubricants oils 

are now available with improved performance and better lubrication. If 

manufacturers choose to make use of these lubricants, they would need to make 

engine changes and possibly conduct durability testing to accommodate the lowfriction lubricants. 

 Reduction of engine friction losses – can be achieved through low-tension piston 

rings, roller cam followers, improved material coatings, more optimal thermal 

management, piston surface treatments, and other improvements in the design of 

engine components and subsystems that improve engine operation. 

 Cylinder deactivation – deactivates the intake and exhaust valves and prevents 

fuel injection into some cylinders during light-load operation. The engine runs 

temporarily as though it were a smaller engine which substantially reduces 

pumping losses. 
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 Variable valve timing – alters the timing of the intake valve, exhaust valve, or 

both, primarily to reduce pumping losses, increase specific power, and control 

residual gases.

 Stoichiometric gasoline direct-injection technology – injects fuel at high pressure 

directly into the combustion chamber to improve cooling of the air/fuel charge 

within the cylinder, which allows for higher compression ratios and increased 

thermodynamic efficiency. 

 Diesel engine improvements and diesel aftertreatment improvements – improved 

EGR systems and advanced timing can provide more efficient combustion and, 

hence, lower fuel consumption. Aftertreatment systems are a relatively new 

technology on diesel vehicles and, as such, improvements are expected in coming 

years that allow the effectiveness of these systems to improve while reducing the 

fuel and reductant demands of current systems. 

Types of transmission technologies considered include:

 Improved automatic transmission controls – optimizes shift schedule to maximize 

fuel efficiency under wide ranging conditions, and minimizes losses associated 

with torque converter slip through lock-up or modulation.

 Six-, seven-, and eight-speed automatic transmissions – the gear ratio spacing and 

transmission ratio are optimized for a broader range of engine operating 

conditions specific to the mating engine. 

Types of vehicle technologies considered include:

 Low-rolling-resistance tires – have characteristics that reduce frictional losses 

associated with the energy dissipated in the deformation of the tires under load, 

therefore improving fuel efficiency and reducing CO2 emissions.

 Aerodynamic drag reduction – is achieved by changing vehicle shape or reducing 

frontal area, including skirts, air dams, underbody covers, and more aerodynamic 

side view mirrors.

 Mass reduction and material substitution – Mass reduction encompasses a variety 

of techniques ranging from improved design and better component integration to 

application of lighter and higher-strength materials. Mass reduction is further 

compounded by reductions in engine power and ancillary systems (transmission, 

steering, brakes, suspension, etc.). The agencies recognize there is a range of 

diversity and complexity for mass reduction and material substitution 

technologies and there are many techniques that automotive suppliers and 

manufacturers are using to achieve the levels of this technology that the agencies 

have modeled in our analysis for this program. 
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Types of electrification/accessory and hybrid technologies considered include:

 Electric power steering and Electro-Hydraulic power steering – are electricallyassisted steering systems that have advantages over traditional hydraulic power 

steering because it replaces a continuously operated hydraulic pump, thereby

reducing parasitic losses from the accessory drive.

 Improved accessories – may include high efficiency alternators, electrically

driven (i.e., on-demand) water pumps and cooling fans. This excludes other 

electrical accessories such as electric oil pumps and electrically driven air 

conditioner compressors.

 Air Conditioner Systems – These technologies include improved hoses, 

connectors and seals for leakage control. They also include improved 

compressors, expansion valves, heat exchangers and the control of these 

components for the purposes of improving tailpipe CO2 emissions as a result of 

A/C use.250

(2) How Did the Agencies Determine the Costs and Effectiveness of Each of 

These Technologies?

Building on the technical analysis underlying the light-duty 2012-2016 MY 

vehicle rule, the agencies took a fresh look at technology cost and effectiveness values 

for purposes of this final action. For costs, the agencies reconsidered both the direct or 

“piece” costs and indirect costs of individual components of technologies. For the direct 

costs, the agencies followed a bill of materials (BOM) approach employed by NHTSA 

and EPA in the light-duty rule. 

For two technologies, stoichiometric gasoline direct injection (SGDI) and 

turbocharging with engine downsizing, the agencies relied to the extent possible on the 

available tear-down data and scaling methodologies used in EPA’s ongoing study with 

FEV, Incorporated. This study consists of complete system tear-down to evaluate 

technologies down to the nuts and bolts to arrive at very detailed estimates of the costs 

associated with manufacturing them.251 

For the other technologies, considering all sources of information and using the 

BOM approach, the agencies worked together intensively to determine component costs 

for each of the technologies and build up the costs accordingly. Where estimates differ 

between sources, we have used engineering judgment to arrive at what we believe to be 

the best cost estimate available today, and explained the basis for that exercise of 

judgment.

 

250 See RIA Chapter 2.3 for more detailed technology descriptions.

251 U.S. Environmental Protection Agency, “Draft Report – Light-Duty Technology Cost Analysis Pilot 

Study,” Contract No. EP-C-07-069, Work Assignment 1-3, September 3, 2009.
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Once costs were determined, they were adjusted to ensure that they were all 

expressed in 2009 dollars using a ratio of gross domestic product (GDP) values for the 

associated calendar years,252 and indirect costs were accounted for using the new 

approach developed by EPA and used in the light-duty 2012-2016 MY vehicle rule. 

NHTSA and EPA also reconsidered how costs should be adjusted by modifying or 

scaling content assumptions to account for differences across the range of vehicle sizes 

and functional requirements, and adjusted the associated material cost impacts to account

for the revised content, although some of these adjustments may be different for each 

agency due to the different vehicle subclasses used in their respective models. 

Regarding estimates for technology effectiveness, NHTSA and EPA used the 

estimates from the light-duty rule as a baseline but adjusted them as appropriate, taking 

into account the unique requirement of the heavy-duty test cycles to test at curb weight 

plus half payload versus the light-duty requirement of curb plus 300 lb. The adjustments 

were made on an individual technology basis by assessing the specific impact of the 

added load on each technology when compared to the use of the technology on a lightduty vehicle. The agencies also considered other sources such as the 2010 NAS Report, 

recent CAFE compliance data, and confidential manufacturer estimates of technology

effectiveness. NHTSA and EPA engineers reviewed effectiveness information from the 

multiple sources for each technology and ensured that such effectiveness estimates were 

based on technology hardware consistent with the BOM components used to estimate 

costs. Together, the agencies compared the multiple estimates and assessed their validity, 

taking care to ensure that common BOM definitions and other vehicle attributes such as

performance and drivability were taken into account. 

The agencies note that the effectiveness values estimated for the technologies may

represent average values applied to the baseline fleet described earlier, and do not reflect 

the potentially-limitless spectrum of possible values that could result from adding the 

technology to different vehicles. For example, while the agencies have estimated an 

effectiveness of 0.5 percent for low friction lubricants, each vehicle could have a unique 

effectiveness estimate depending on the baseline vehicle’s oil viscosity rating. Similarly, 

the reduction in rolling resistance (and thus the improvement in fuel efficiency and the 

reduction in CO2 emissions) due to the application of LRR tires depends not only on the 

unique characteristics of the tires originally on the vehicle, but on the unique 

characteristics of the tires being applied, characteristics which must be balanced between 

fuel efficiency, safety, and performance. Aerodynamic drag reduction is much the 

same—it can improve fuel efficiency and reduce CO2 emissions, but it is also highly 

dependent on vehicle-specific functional objectives. For purposes of this NPRM, 

NHTSA and EPA believe that employing average values for technology effectiveness 

estimates is an appropriate way of recognizing the potential variation in the specific 

benefits that individual manufacturers (and individual vehicles) might obtain from adding 

a fuel-saving technology. 

 

252 NHTSA examined the use of the CPI multiplier instead of GDP for adjusting these dollar values, but 

found the difference to be exceedingly small – only $0.14 over $100.
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The following section contains a detailed description of our assessment of vehicle 

technology cost and effectiveness estimates. The agencies note that the technology costs 

included in this NPRM take into account only those associated with the initial build of 

the vehicle. 

(a) Engine Technologies

NHTSA and EPA have reviewed the engine technology estimates used in the 

light-duty rule. In doing so NHTSA and EPA reconsidered all available sources and 

updated the estimates as appropriate. The section below describes both diesel and 

gasoline engine technologies considered for this program.

(i) Low Friction Lubricants

One of the most basic methods of reducing fuel consumption in both gasoline and 

diesel engines is the use of lower viscosity engine lubricants. More advanced multiviscosity engine oils are available today with improved performance in a wider 

temperature band and with better lubricating properties. This can be accomplished by

changes to the oil base stock (e.g., switching engine lubricants from a Group I base oils to 

lower-friction, lower viscosity Group III synthetic) and through changes to lubricant 

additive packages (e.g., friction modifiers and viscosity improvers). The use of 5W-30 

motor oil is now widespread and auto manufacturers are introducing the use of even 

lower viscosity oils, such as 5W-20 and 0W-20, to improve cold-flow properties and 

reduce cold start friction. However, in some cases, changes to the crankshaft, rod and 

main bearings and changes to the mechanical tolerances of engine components may be 

required. In all cases, durability testing would be required to ensure that durability is not 

compromised. The shift to lower viscosity and lower friction lubricants will also improve 

the effectiveness of valvetrain technologies such as cylinder deactivation, which rely on a 

minimum oil temperature (viscosity) for operation.

Based on the light-duty 2012-2016 MY vehicle rule, and previously-received 

confidential manufacturer data, NHTSA and EPA estimated the effectiveness of low 

friction lubricants to be between 0 to 1 percent. 

In the light-duty rule, the agencies estimated the cost of moving to low friction 

lubricants at $3 per vehicle (2007$). That estimate included a markup of 1.11 for a low 

complexity technology. For HD pickups and vans, we are using the same base estimate 

but have marked it up to 2009 dollars using the GDP price deflator and have used a 

markup of 1.24 for a low complexity technology to arrive at a value of $4 per vehicle. As 

in the light-duty rule, learning effects are not applied to costs for this technology and, as 

such, this estimate applies to all model years.253,254

 

253 Note that throughout the cost estimates for this HD analysis, the agencies have used slightly higher 

markups than those used in the 2012-2016 MY light-duty vehicle rule. The new, slightly higher ICMs 

include return on capital of roughly 6%, a factor that was not included in the light-duty analysis. The 

markups are also higher than those used the in proposal for this action. That change has to do with our 

decision to base the ICMs solely on EPA internal work rather than averaging that work with earlier work 
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(ii) Engine Friction Reduction

In addition to low friction lubricants, manufacturers can also reduce friction and 

improve fuel consumption by improving the design of both diesel and gasoline engine 

components and subsystems. Approximately 10 percent of the energy consumed by a 

vehicle is lost to friction, and just over half is due to frictional losses within the engine.255 

Examples include improvements in low-tension piston rings, piston skirt design, roller 

cam followers, improved crankshaft design and bearings, material coatings, material 

substitution, more optimal thermal management, and piston and cylinder surface 

treatments. Additionally, as computer-aided modeling software continues to improve, 

more opportunities for evolutionary friction reductions may become available.

All reciprocating and rotating components in the engine are potential candidates 

for friction reduction, and minute improvements in several components can add up to a 

measurable fuel efficiency improvement. The light-duty 2012-2106 MY vehicle rule, the 

2010 NAS Report, and NESCCAF and Energy and Environmental Analysis reports, as 

well as confidential manufacturer data, indicate a range of effectiveness for engine 

friction reduction to be between 1 to 3 percent. NHTSA and EPA continue to believe 

that this range is accurate.

Consistent with the light-duty rule, the agencies estimate the cost of this 

technology at $15 per cylinder compliance cost (2008$), including the low complexity

ICM markup value of 1.24. Learning impacts are not applied to the costs of this 

technology and, as such, this estimate applies to all model years. This cost is multiplied 

by the number of engine cylinders.

(iii) Coupled Cam Phasing

Valvetrains with coupled (or coordinated) cam phasing can modify the timing of 

both the inlet valves and the exhaust valves an equal amount by phasing the camshaft of 

an overhead valve engine. For overhead valve engines, which have only one camshaft to 

actuate both inlet and exhaust valves, couple cam phasing is the only variable valve 

timing implementation option available and requires only one cam phaser. Based on the 

light-duty rule, previously-received confidential manufacturer data, and the NESCCAF 

report, NHTSA and EPA estimated the effectiveness of couple cam phasing to be 

between 1 and 4 percent. NHTSA and EPA reviewed this estimate for purposes of the 

NPRM, and continue to find it accurate.

The agencies received comments questioning the exclusion of cam phasing from 

the technology packages. During the rulemaking process, manufacturers introduced 

 

done under contract to EPA by RTI, International. That change is discussed in Section VIII.C of this 

preamble and is detailed in Chapter 2 of the RIA (See RIA 2.2.1)

254

 Note that the costs developed for low friction lubes for this analysis reflect the costs associated with any 

engine changes that would be required as well as any durability testing that may be required. 

255 “Impact of Friction Reduction Technologies on Fuel Economy,” Fenske, G. Presented at the March 

2009 Chicago Chapter Meeting of the ‘Society of Tribologists and Lubricated Engineers’ Meeting, March 

18th, 2009. Available at: http://www.chicagostle.org/program/2008-

2009/Impact%20of%20Friction%20Reduction%20Technologies%20on%20Fuel%20Economy%20-

%20with%20VGs%20removed.pdf (last accessed July 9, 2009).
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many new or updated gasoline engines resulting in the majority of the 2010 gasoline

heavy-duty engines including cam phasing, and so we now consider this technology to be 

in the baseline fleet. Because of this, the baseline analysis of technology for the 2010 

heavy-duty gasoline fleet already includes the benefits of cam phasing and therefore it is 

not appropriate for the agencies to include this as a technology that is available for most 

manufactures to add to their current gasoline engines. 

(iv) Cylinder Deactivation

In conventional spark-ignited engines throttling the airflow controls engine torque 

output. At partial loads, efficiency can be improved by using cylinder deactivation 

instead of throttling. Cylinder deactivation can improve engine efficiency by disabling or 

deactivating (usually) half of the cylinders when the load is less than half of the engine’s 

total torque capability – the valves are kept closed, and no fuel is injected – as a result, 

the trapped air within the deactivated cylinders is simply compressed and expanded as an 

air spring, with reduced friction and heat losses. The active cylinders combust at almost 

double the load required if all of the cylinders were operating. Pumping losses are 

significantly reduced as long as the engine is operated in this “part-cylinder” mode.

Cylinder deactivation control strategy relies on setting maximum manifold 

absolute pressures or predicted torque within a range in which it can deactivate the 

cylinders. Noise and vibration issues reduce the operating range to which cylinder 

deactivation is allowed, although manufacturers are exploring vehicle changes that enable 

increasing the amount of time that cylinder deactivation might be suitable. Some 

manufacturers may choose to adopt active engine mounts and/or active noise 

cancellations systems to address Noise Vibration and Harshness (NVH) concerns and to 

allow a greater operating range of activation. Cylinder deactivation is a technology

keyed to more lightly loaded operation, and so may be a less likely technology choice for 

manufacturers designing for effectiveness in the loaded condition required for testing, 

and in the real world that involves frequent operation with heavy loads. 

Cylinder deactivation has seen a recent resurgence thanks to better valvetrain 

designs and engine controls. General Motors and Chrysler Group have incorporated 

cylinder deactivation across a substantial portion of their light-duty V8-powered lineups.

Effectiveness improvements scale roughly with engine displacement-to-vehicle 

weight ratio: the higher displacement-to-weight vehicles, operating at lower relative loads 

for normal driving, have the potential to operate in part-cylinder mode more frequently. 

For heavy-duty vehicles tested and operated at loaded conditions, the power to weight 

ratio is considerably lower than the light-duty case greatly reducing the opportunity for 

“part-cylinder” mode and therefore was not considered in this rulemaking as an effective 

technology for heavy-duty pickup truck and van applications.

(v) Stoichiometric Gasoline Direct Injection

SGDI engines inject fuel at high pressure directly into the combustion chamber 

(rather than the intake port in port fuel injection). SGDI requires changes to the injector 

design, an additional high pressure fuel pump, new fuel rails to handle the higher fuel 
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pressures and changes to the cylinder head and piston crown design. Direct injection of

the fuel into the cylinder improves cooling of the air/fuel charge within the cylinder, 

which allows for higher compression ratios and increased thermodynamic efficiency 

without the onset of combustion knock. Recent injector design advances, improved 

electronic engine management systems and the introduction of multiple injection events 

per cylinder firing cycle promote better mixing of the air and fuel, enhance combustion 

rates, increase residual exhaust gas tolerance and improve cold start emissions. SGDI

engines achieve higher power density and match well with other technologies, such as 

boosting and variable valvetrain designs.

Several manufacturers have recently introduced vehicles with SGDI engines, 

including GM and Ford and have announced their plans to increase dramatically the 

number of SGDI engines in their portfolios.

The light-duty 2012-2016 MY vehicle rule estimated the range of 1 to 2 percent 

for SGDI. NHTSA and EPA reviewed this estimate for purposes of the NPRM, and 

continue to find it accurate. 

Consistent with the light-duty rule, NHTSA and EPA cost estimates for SGDI 

take into account the changes required to the engine hardware, engine electronic controls, 

ancillary and NVH mitigation systems. Through contacts with industry NVH suppliers, 

and manufacturer press releases, the agencies believe that the NVH treatments will be 

limited to the mitigation of fuel system noise, specifically from the injectors and the fuel 

lines. For this analysis, the agencies have estimated the costs at $481 (2009$) in the 2014 

model year. Flat-portion of the curve learning is applied to this technology. This 

technology was considered for gasoline engines only, as diesel engines already employ 

direct injection.

(b) Diesel Engine Technologies 

Diesel engines have several characteristics that give them superior fuel efficiency

compared to conventional gasoline, spark-ignited engines. Pumping losses are much 

lower due to lack of (or greatly reduced) throttling. The diesel combustion cycle operates 

at a higher compression ratio, with a very lean air/fuel mixture, and turbocharged lightduty diesels typically achieve much higher torque levels at lower engine speeds than 

equivalent-displacement naturally-aspirated gasoline engines. Additionally, diesel fuel 

has a higher energy content per gallon.256 However, diesel fuel also has a higher carbon 

to hydrogen ratio, which increases the amount of CO2 emitted per gallon of fuel used by 

approximately 15 percent over a gallon of gasoline.

Based on confidential business information and the 2010 NAS Report, two major 

areas of diesel engine design will be improved during the 2014-2018 time frame. These 

areas include aftertreatment improvements and a broad range of engine improvements.

 

256 Burning one gallon of diesel fuel produces about 15 percent more carbon dioxide than gasoline due to 

the higher density and carbon to hydrogen ratio.
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(i) Aftertreatment Improvements

The HD diesel pickup and van segment has largely adopted the SCR type of 

aftertreatment system to comply with criteria pollutant emission standards. As the 

experience base for SCR expands over the next few years, many improvements in this 

aftertreatment system such as construction of the catalyst, thermal management, and 

reductant optimization will result in a significant reduction in the amount of fuel used in 

the process. This technology was not considered in the light-duty rule. Based on 

confidential business information, EPA and NHTSA estimate the reduction in CO2 as a 

result of these improvements at 3 to 5 percent.

The agencies have estimated the cost of this technology at $25 for each 

percentage improvement in fuel consumption. This estimate is based on the agencies’ 

belief that this technology is, in fact, a very cost effective approach to improving fuel 

consumption. As such, $25 per percent improvement is considered a reasonable cost. 

This cost would cover the engineering and test cell related costs necessary to develop and 

implement the improved control strategies that would allow for the improvements in fuel 

consumption. Importantly, the engineering work involved would be expected to result in 

cost savings to the aftertreatment and control hardware (lower platinum group metal 

loadings, lower reductant dosing rates, etc.). Those savings are considered to be included 

in the $25 per percent estimate described here. Given the 4 percent average expected 

improvement in fuel consumption results in an estimated cost of $119 (2009$) for a 2014 

model year truck or van. This estimate includes a low complexity ICM of 1.24 and flatportion of the curve learning from 2012 forward.

(ii) Engine Improvements

Diesel engines in the HD pickup and van segment are expected to have several 

improvements in their base design in the 2014 – 2018 time frame. These improvements 

include items such as improved combustion management, optimal turbocharger design, 

and improved thermal management. This technology was not considered in the lightduty rule. Based on confidential business information, EPA and NHTSA estimate the 

reduction in CO2 as a result of these improvements at 4 to 6 percent.

The cost for this technology includes costs associated with low temperature 

exhaust gas recirculation, improved turbochargers and improvements to other systems 

and components. These costs are considered collectively in our costing analysis and 

termed “diesel engine improvements.” The agencies have estimated the cost of diesel 

engine improvements at $148 based on the cost estimates for several individual 

technologies. Specifically, the direct manufacturing costs we have estimated are: 

improved cylinder head, $9; turbo efficiency improvements, $16; EGR cooler 

improvements, $3; higher pressure fuel rail, $10; improved fuel injectors, $13; improved 

pistons, $2; and reduced valve train friction, $95. All values are in 2009 dollars and are 

applicable in the 2014 MY. Applying a low complexity ICM of 1.24 results in a cost of 

$184 (2009$) applicable in the 2014MY. We consider flat-portion of the curve learning 

to be appropriate for these technologies.
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(c) Transmission Technologies 

NHTSA and EPA have also reviewed the transmission technology estimates used 

in the light-duty rule. In doing so, NHTSA and EPA considered or reconsidered all 

available sources and updated the estimates as appropriate. The section below describes 

each of the transmission technologies considered for the final standards.

(i) Improved Automatic Transmission Control (Aggressive Shift Logic and Early 

Torque Converter Lockup)

Calibrating the transmission shift schedule to upshift earlier and quicker, and to 

lock-up or partially lock-up the torque converter under a broader range of operating 

conditions can reduce fuel consumption and CO2 emissions. However, this operation can 

result in a perceptible degradation in NVH. The degree to which NVH can be degraded 

before it becomes noticeable to the driver is strongly influenced by characteristics of the 

vehicle, and although it is somewhat subjective, it always places a limit on how much 

fuel consumption can be improved by transmission control changes. Given that the 

Aggressive Shift Logic and Early Torque Converter Lockup are best optimized 

simultaneously due to the fact that adding both of them primarily requires only minor 

modifications to the transmission or calibration software, these two technologies are 

combined in the modeling. We consider these technologies to be present in the baseline, 

since 6-speed automatic transmissions are installed in the majority of Class 2b and 3 

trucks in the 2010 model year time frame.

(ii) Automatic 6- and 8-Speed Transmissions

Manufacturers can also choose to replace 4- 5- and 6-speed automatic 

transmissions with 8-speed automatic transmissions. Additional ratios allow for further 

optimization of engine operation over a wider range of conditions, but this is subject to 

diminishing returns as the number of speeds increases. As additional planetary gear sets 

are added (which may be necessary in some cases to achieve the higher number of ratios), 

additional weight and friction are introduced. Also, the additional shifting of such a 

transmission can be perceived as bothersome or busy to some consumers, so 

manufacturers need to develop strategies for smooth shifts. Some manufacturers are 

replacing 4- and 5-speed automatics with 6-speed automatics already, and 7- and 8-speed 

automatics have entered production in light-duty vehicles, albeit in lower-volume 

applications in luxury and performance oriented cars.

As discussed in the light-duty rule, confidential manufacturer data projected that 

6-speed transmissions could incrementally reduce fuel consumption by 0 to 5 percent 

from a 4-speed automatic transmission, while an 8-speed transmission could 

incrementally reduce fuel consumption by up to 6 percent from a 4-speed automatic 

transmission. GM has publicly claimed a fuel economy improvement of up to 4 percent 

for its new 6-speed automatic transmissions.257 

 

257 General Motors, news release, “From Hybrids to Six-Speeds, Direct Injection And More, GM’s 2008 

Global Powertrain Lineup Provides More Miles with Less Fuel” (released Mar. 6, 2007). Available at 
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NHTSA and EPA reviewed and revised these effectiveness estimates based on 

actual usage statistics and testing methods for these vehicles along with confidential 

business information. When combined with improved automatic transmission control, 

the agencies estimate the effectiveness for a conversion from a 4 to a 6-speed 

transmission to be 5.3% and a conversion from a 6 to 8-speed transmission to be 1.7%. 

While 8-speed transmissions were not considered in the light-duty 2012-2016 MY

vehicle rule, they are considered as a technology of choice for this analysis in that 

manufacturers are expected to upgrade the 6-speed automatic transmissions being 

implemented today with 8-speed automatic transmissions in the 2014-2018 time frame. 

We are estimating the cost of an 8-speed automatic transmission at $281 (2009$) relative

to a 6-speed automatic transmission in the 2014 model year. This estimate is based from 

the 2010 NAS Report and we have applied a low complexity ICM of 1.24 and flatportion of the curve learning. This technology applies to both gasoline and diesel pickup 

trucks and vans.

(d) Electrification/Accessory Technologies

(i) Electrical Power Steering or Electrohydraulic Power Steering

Electric power steering (EPS) or Electrohydraulic power steering (EHPS) 

provides a potential reduction in CO2 emissions and fuel consumption over hydraulic 

power steering because of reduced overall accessory loads. This eliminates the parasitic 

losses associated with belt-driven power steering pumps which consistently draw load 

from the engine to pump hydraulic fluid through the steering actuation systems even 

when the wheels are not being turned. EPS is an enabler for all vehicle hybridization 

technologies since it provides power steering when the engine is off. EPS may be 

implemented on most vehicles with a standard 12V system. Some heavier vehicles may

require a higher voltage system which may add cost and complexity.

The light-duty rule estimated a one to two percent effectiveness based on the 2002 

NAS report for light-duty vehicle technologies, a Sierra Research report, and confidential 

manufacturer data. NHTSA and EPA reviewed these effectiveness estimates and found 

them to be accurate, thus they have been retained for purposes of this NPRM.

NHTSA and EPA adjusted the EPS cost for the current rulemaking based on a 

review of the specification of the system. Adjustments were made to include potentially

higher voltage or heavier duty system operation for HD pickups and vans. Accordingly, 

higher costs were estimated for systems with higher capability. After accounting for the 

differences in system capability and applying the ICM markup of low complexity

technology of 1.24, the estimated costs are $115 for a MY 2014 truck or van (2009$). As 

EPS systems are in widespread usage today, flat-portion of the curve learning is deemed 

applicable. EHPS systems are considered to be of equal cost and both are considered 

applicable to gasoline and diesel engines.

 

http://www.gm.com/experience/fuel_economy/news/2007/adv_engines/2008-powertrain-lineup-082707.jsp 

(last accessed Sept. 18, 2008).
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(ii) Improved Accessories

The accessories on an engine, including the alternator, coolant and oil pumps are 

traditionally mechanically-driven. A reduction in CO2 emissions and fuel consumption 

can be realized by driving the pumping accessories electrically, and only when needed 

(“on-demand”). Alternator improvements include internal changes resulting in lower 

mechanical and electrical losses combined with control logic that charges the battery at 

more efficient voltage levels and during conditions of available kinetic energy from the 

vehicle which would normally be wasted energy such as braking during vehicle 

decelerations. 

Electric water pumps and electric fans can provide better control of engine 

cooling. For example, coolant flow from an electric water pump can be reduced and the 

radiator fan can be shut off during engine warm-up or cold ambient temperature 

conditions which will reduce warm-up time, reduce warm-up fuel enrichment, and reduce 

parasitic losses.

Indirect benefit may be obtained by reducing the flow from the water pump 

electrically during the engine warm-up period, allowing the engine to heat more rapidly 

and thereby reducing the fuel enrichment needed during cold starting of the engine. 

Further benefit may be obtained when electrification is combined with an improved, 

higher efficiency engine alternator. Intelligent cooling can more easily be applied to 

vehicles that do not typically carry heavy payloads, so larger vehicles with towing 

capacity present a challenge, as these vehicles have high cooling fan loads.258

The agencies considered whether to include electric oil pump technology for the 

rulemaking. Because it is necessary to operate the oil pump any time the engine is 

running, electric oil pump technology has insignificant effect on efficiency. Therefore, 

the agencies decided to not include electric oil pump technology.

NHTSA and EPA jointly reviewed the estimates of 1 to 2 percent effectiveness 

estimates used in the light-duty rule and found them to be accurate for Improved 

Electrical Accessories. Consistent with the light-duty rule, the agencies have estimated 

the cost of this technology at $93 (2009$) including a low complexity ICM of 1.24. This 

cost is applicable in the 2014 model year. Improved accessory systems are in production 

currently and thus flat-portion of the curve learning is applied. This technology was 

considered for diesel pickup trucks and vans only.

(e) Vehicle Technologies

(i) Mass Reduction

Reducing a vehicle’s mass, or down-weighting the vehicle, decreases fuel 

consumption by reducing the energy demand needed to overcome forces resisting motion, 

and rolling resistance. Manufacturers employ a systematic approach to mass reduction, 

where the net mass reduction is the addition of a direct component or system mass 

 

258 In the CAFE model, improved accessories refer solely to improved engine cooling. However, EPA has 

included a high efficiency alternator in this category, as well as improvements to the cooling system.
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reduction plus the additional mass reduction taken from indirect ancillary systems and 

components, as a result of full vehicle optimization, effectively compounding or 

obtaining a secondary mass reduction from a primary mass reduction. For example, use 

of a smaller, lighter engine with lower torque-output subsequently allows the use of a 

smaller, lighter-weight transmission and drive line components. Likewise, the 

compounded weight reductions of the body, engine and drivetrain reduce stresses on the 

suspension components, steering components, wheels, tires and brakes, allowing further 

reductions in the mass of these subsystems. The reductions in unsprung masses such as 

brakes, control arms, wheels and tires further reduce stresses in the suspension mounting 

points. This produces a compounding effect of mass reductions.

Estimates of the synergistic effects of mass reduction and the compounding effect 

that occurs along with it can vary significantly from one report to another. For example, 

in discussing its estimate, an Auto-Steel Partnership report states that “These secondary

mass changes can be considerable—estimated at an additional 0.7 to 1.8 times the initial 

mass change.”259 This means for each one pound reduction in a primary component, up to 

1.8 pounds can be reduced from other structures in the vehicle (i.e., a 180 percent factor). 

The report also discusses that a primary variable in the realized secondary weight 

reduction is whether or not the powertrain components can be included in the mass 

reduction effort, with the lower end estimates being applicable when powertrain elements 

are unavailable for mass reduction. However, another report by the Aluminum 

Association, which primarily focuses on the use of aluminum as an alternative material 

for steel, estimated a factor of 64 percent for secondary mass reduction even though some 

powertrain elements were considered in the analysis.260 That report also notes that 

typical values for this factor vary from 50 to 100 percent. Although there is a wide 

variation in stated estimates, synergistic mass reductions do exist, and the effects result in 

tangible mass reductions. Mass reductions in a single vehicle component, for example a 

door side impact/intrusion system, may actually result in a significantly higher weight 

savings in the total vehicle, depending on how well the manufacturer integrates the 

modification into the overall vehicle design. Accordingly, care must be taken when 

reviewing reports on weight reduction methods and practices to ascertain if compounding 

effects have been considered or not.

Mass reduction is broadly applicable across all vehicle subsystems including the 

engine, exhaust system, transmission, chassis, suspension, brakes, body, closure panels, 

glazing, seats and other interior components, engine cooling systems and HVAC systems. 

It is estimated that up to 1.25 kilograms of secondary weight savings can be achieved for 

 

259 “Preliminary Vehicle Mass Estimation Using Empirical Subsystem Influence Coefficients,” Malen, 

D.E., Reddy, K. Auto-Steel Partnership Report, May 2007, Docket EPA-HQ-OAR-2009-0472-0169. 

Accessed on the Internet on May 30, 2009 at: http://www.asp.org/database/custom/Mass%20Compounding%20-%20Final%20Report.pdf

260

 “Benefit Analysis: Use of Aluminum Structures in Conjunction with Alternative Powertrain 

Technologies in Automobiles,” Bull, M. Chavali, R., Mascarin, A., Aluminum Association Research 

Report, May 2008, Docket EPA-HQ-OAR-2009-0472-0168. Accessed on the Internet on April 30, 2009 

at: http://www.autoaluminum.org/downloads/IBIS-Powertrain-Study.pdf
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every kilogram of weight saved on a light-duty vehicle when all subsystems are 

redesigned to take into account the initial primary weight savings.261,262 

Mass reduction can be accomplished by proven methods such as:

 Smart Design: Computer aided engineering (CAE) tools can be used to better 

optimize load paths within structures by reducing stresses and bending moments 

applied to structures. This allows better optimization of the sectional thicknesses 

of structural components to reduce mass while maintaining or improving the 

function of the component. Smart designs also integrate separate parts in a 

manner that reduces mass by combining functions or the reduced use of separate 

fasteners. In addition, some “body on frame” vehicles are redesigned with a 

lighter “unibody” construction. 

 Material Substitution: Substitution of lower density and/or higher strength 

materials into a design in a manner that preserves or improves the function of the 

component. This includes substitution of high-strength steels, aluminum, 

magnesium or composite materials for components currently fabricated from mild 

steel. 

 Reduced Powertrain Requirements: Reducing vehicle weight sufficiently allows 

for the use of a smaller, lighter and more efficient engine while maintaining or 

increasing performance. Approximately half of the reduction is due to these 

reduced powertrain output requirements from reduced engine power output and/or 

displacement, changes to transmission and final drive gear ratios. The subsequent 

reduced rotating mass (e.g., transmission, driveshafts/halfshafts, wheels and tires) 

via weight and/or size reduction of components are made possible by reduced 

torque output requirements.

 Automotive companies have largely used weight savings in some vehicle 

subsystems to offset or mitigate weight gains in other subsystems from increased 

feature content (sound insulation, entertainment systems, improved climate 

control, panoramic roof, etc.). 

 Lightweight designs have also been used to improve vehicle performance 

parameters by increased acceleration performance or superior vehicle handling 

and braking.

 

261 “Future Generation Passenger Compartment-Validation (ASP 241)” Villano, P.J., Shaw, J.R., 

Polewarczyk, J., Morgans, S., Carpenter, J.A., Yocum, A.D., in “Lightweighting Materials – FY 2008 

Progress Report,” U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Vehicle 

Technologies Program, May 2009, Docket EPA-HQ-OAR-2009-0472-0190.

262 “Preliminary Vehicle Mass Estimation Using Empirical Subsystem Influence Coefficients,” Malen, 

D.E., Reddy, K. Auto-Steel Partnership Report, May 2007, Docket EPA-HQ-OAR-2009-0472-0169. 

Accessed on the Internet on May 30, 2009 at: http://www.asp.org/database/custom/Mass%20Compounding%20-%20Final%20Report.pdf
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Many manufacturers have already announced final future products plans reducing 

the weight of a vehicle body through the use of high strength steel body-in-white, 

composite body panels, magnesium alloy front and rear energy absorbing structures 

reducing vehicle weight sufficiently to allow a smaller, lighter and more efficient engine. 

Nissan will be reducing average vehicle curb weight by 15% by 2015.263 Ford has 

identified weight reductions of 250 to 750 lb per vehicle as part of its implementation of 

known technology within its sustainability strategy between 2011 and 2020.264 Mazda 

plans to reduce vehicle weight by 220 pounds per vehicle or more as models are 

redesigned.265,266 Ducker International estimates that the average curb weight of lightduty vehicle fleet will decrease approximately 2.8% from 2009 to 2015 and 

approximately 6.5% from 2009 to 2020 via changes in automotive materials and 

increased change-over from previously used body-on-frame automobile and light-truck 

designs to newer unibody designs.263 While the opportunity for mass reductions available 

to the light-duty fleet may not in all cases be applied directly to the heavy-duty fleet due 

to the different designs for the expected duty cycles of a “work” vehicle, mass reductions 

are still available particularly to areas unrelated to the components and systems necessary

for the work vehicle aspects. 

Due to the payload and towing requirements of these heavy-duty vehicles, engine 

downsizing was not considered in the estimates for CO2 reduction in the area of mass 

reduction and material substitution. NHTSA and EPA estimate that a 3 percent mass 

reduction with no engine downsizing results in a 1 percent reduction in fuel consumption. 

In addition, a 5 and 10 percent mass reduction with no engine downsizing result in an 

estimated CO2 reduction of 1.6 and 3.2 percent respectively. These effectiveness values 

are 50% of the light-duty rule values due to the elimination of engine downsizing for this 

class of vehicle.

The agencies have recently completed work on an Interim Joint Technical 

Assessment Report (TAR) that considers light-duty GHG and fuel economy standards for 

the 2017 through 2025 MY and have continued this work for the proposed light-duty 

vehicle rule. Based on new information from various industry and literature sources, the 

TAR report modified the mass reduction/cost relationship used in the light-duty 2012-

2016 MY vehicle rule to begin at the origin (0% weight reduction) and to have increasing 

cost with increasing mass reduction.267 The resulting analysis showed costs for 5% mass 

reduction on light-duty vehicles to be near zero or cost parity. 

 

263 “Lighten Up!,” Brooke, L., Evans, H. Automotive Engineering International, Vol. 117, No. 3, March 

2009.

264 “2008/9 Blueprint for Sustainability,” Ford Motor Company. Available at: http:// 

www.ford.com/go/sustainability (last accessed February 8, 2010).

265 “Mazda to cut vehicle fuel consumption 30 percent by 2015,” Mazda press release, June 23, 2009. 

Available at: http://www.mazda.com/publicity/release/2008/200806/080623.html (last accessed February 

8, 2010).

266 “Mazda: Don’t believe hot air being emitted by hybrid hype,” Greimel, H. Automotive News, March 30, 

2009.

267 “Interim Joint Technical Assessment Report: Light-Duty Vehicle Greenhouse Gas Emission Standards 

and Corporate Average Fuel Economy Standards for Model Years 2017-2025;” September 2010; available 

at http://epa.gov/otaq/climate/regulations/ldv-ghg-tar.pdf and in the docket for this rule.
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In the proposal for heavy-duty vehicle standards, we estimated mass reduction 

costs based on the light-duty 2012-2016 analysis without accounting for the new work 

completed in the Interim Joint Technical Assessment. Since the proposal, we have been 

able to consider our cost estimates here in the context of both light-duty and heavy-duty 

vehicle bodies of work. For this final action, in aggregate, we estimate a 5 percent mass 

reduction at a cost of $80-100 per vehicle. We are estimating the following direct 

manufacturer costs for a 5% mass reduction: Class 2b gasoline, $85; Class 2b diesel,

$95; Class 3 gasoline, $90; and Class 3 diesel pickup trucks, $100. Including a low 

complexity ICM of 1.24 and using learning on the flat portion of the curve, these values 

become $103, $115, $109, and $121, respectively, applicable in the 2016 MY and 

expressed in 2009 dollars. This estimate is higher than our most recent estimate of mass 

reduction contained in the light-duty vehicle Interim Joint Technical Assessment Report 

because we do not believe that all of the weight reduction opportunities for light-duty

vehicles can be applied to heavy-duty trucks. However, we do believe reductions in the 

following components and systems can be found that do not affect the payload and 

towing requirements of these heavy-duty vehicles; body, closure panels, glazing, seats 

and other interior components, engine cooling systems and HVAC systems. 

(ii) Low Rolling Resistance Tires

Tire rolling resistance is the frictional loss associated mainly with the energy

dissipated in the deformation of the tires under load and thus influences fuel efficiency

and CO2 emissions. Other tire design characteristics (e.g., materials, construction, and 

tread design) influence durability, traction (both wet and dry grip), vehicle handling, and 

ride comfort in addition to rolling resistance. A typical LRR tire’s attributes would 

include: increased tire inflation pressure, material changes, and tire construction with less 

hysteresis, geometry changes (e.g., reduced aspect ratios), and reduction in sidewall and 

tread deflection. These changes would generally be accompanied with additional 

changes to suspension tuning and/or suspension design.

EPA and NHTSA estimated a 1 to 2 percent increase in effectiveness with a 10 

percent reduction in rolling resistance, which was based on the 2010 NAS Report 

findings and consistent with the light-duty rule. 

Based on the light-duty rule and the 2010 NAS Report, the agencies have 

estimated the cost for LRR tires to be $7 per Class 2b truck or van, and $10 per Class 3 

truck or van (both values in 2009$ and inclusive of a 1.24 low complexity markup).268 

The higher cost for the Class 3 trucks and vans is due to the predominant use of dual rear 

tires and, thus, 6 tires per truck. Due to the commodity-based nature of this technology, 

cost reductions due to learning are not applied. This technology is considered applicable 

to both gasoline and diesel.

 

268 “Tires and Passenger Vehicle Fuel Economy,” Transportation Research Board Special Report 286, 

National Research Council of the National Academies, 2006, Docket EPA-HQ-OAR-2009-0472-0146.
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(iii) Aerodynamic Drag Reduction

Many factors affect a vehicle’s aerodynamic drag and the resulting power 

required to move it through the air. While these factors change with air density and the 

square and cube of vehicle speed, respectively, the overall drag effect is determined by 

the product of its frontal area and drag coefficient, Cd. Reductions in these quantities can 

therefore reduce fuel consumption and CO2 emissions. Although frontal areas tend to be 

relatively similar within a vehicle class (mostly due to market-competitive size 

requirements), significant variations in drag coefficient can be observed. Significant 

changes to a vehicle’s aerodynamic performance may need to be implemented during a 

redesign (e.g., changes in vehicle shape). However, shorter-term aerodynamic 

reductions, with a somewhat lower effectiveness, may be achieved through the use of 

revised exterior components (typically at a model refresh in mid-cycle) and add-on 

devices that currently being applied. The latter list would include revised front and rear 

fascias, modified front air dams and rear valances, addition of rear deck lips and 

underbody panels, and lower aerodynamic drag exterior mirrors.

The light-duty 2012-2016 MY vehicle rule estimated that a fleet average of 10 to 

20 percent total aerodynamic drag reduction is attainable which equates to incremental 

reductions in fuel consumption and CO2 emissions of 2 to 3 percent for both cars and 

trucks. These numbers are generally supported by confidential manufacturer data and 

public technical literature. For the heavy-duty truck category, a 5 to 10 percent total aerodynamic drag 

reduction was considered due to the different structure and use of these vehicles equating 

to incremental reductions in fuel consumption and CO2 emissions of 1 to 2 percent.

Consistent with the light-duty rule, the agencies have estimated the cost for this 

technology at $58 (2009$) including a low complexity ICM of 1.24. This cost is 

applicable in the 2014 model year to both gasoline and diesel pickup trucks and vans.

(3) What Are the Projected Technology Packages’ Effectiveness and Cost?

The assessment of the final technology effectiveness was developed through the 

use of the EPA Lumped Parameter model developed for the light-duty rule. Many of the 

technologies were common with the light-duty assessment but the effectiveness of 

individual technologies was appropriately adjusted to match the expected effectiveness 

when implemented in a heavy-duty application. The model then uses the individual 

technology effectiveness levels but then takes into account technology synergies. The 

model is also designed to prevent double counting from technologies that may directly or 

indirectly impact the same physical attribute (e.g., pumping loss reductions).

To achieve the levels of the final standards for gasoline and diesel powered 

heavy-duty vehicles, the technology packages were determined to generally require the 

technologies previously discussed respective to unique gasoline and diesel technologies. 

Although some of the technologies may already be implemented in a portion of heavyduty vehicles, none of the technologies discussed are considered ubiquitous in the heavyduty fleet. Also, as would be expected, the available test data shows that some vehicle 

models will not need the full complement of available technologies to achieve the final 

standards. Furthermore, many technologies can be further improved (e.g., aerodynamic 
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improvements) from today’s best levels, and so allow for compliance without needing to 

apply a technology that a manufacturer might deem less desirable. 

Technology costs for HD pickup trucks and vans are shown in Table III-11.

Table III-11 Technology Costs for HD Pickup Trucks & Vans Inclusive of Indirect Cost Markups for 

the 2014MY (2009$)

Technology Class 2b 

Gasoline

Class 2b 

Diesel

Class 3 

Gasoline

Class 3 

Diesel

Low friction lubes $4 $4 $4 $4

Engine friction reduction $116 N/A $116 N/A

Stoichiometric gasoline direct 

injection

$481 N/A $481 N/A

Engine improvements N/A $184 N/A $184

8s automatic transmission 

(increment to 6s automatic 

transmission)

$281 $281 $281 $281

Improved accessories N/A $93 N/A $93

Low rolling resistance tires $7 $7 $10 $10

Aerodynamic improvements $58 $58 $58 $58

Electric (or electro/hydraulic) 

power steering

$115 $115 $115 $115

Aftertreatment improvements N/A $119 N/A $119

Mass reduction (5%) $108 $121 $115 $127

Air conditioning $21 $21 $21 $21

Total $1,190 $1,003 $1,209 $1,013

At 15% phase-in in 2014 $179 $150 $180 $152

(4) Reasonableness of the Final Standards

The final standards are based on the application of the control technologies 

described in this section. These technologies are available within the lead time provided, 

as discussed in RIA Chapter 2.3. These controls are estimated to add costs of 

approximately $1,048 for MY 2018 heavy-duty pickups and vans. Reductions associated 

with these costs and technologies are considerable, estimated at a 12 percent reduction of 

CO2eq emissions from the MY 2010 baseline for gasoline engine-equipped vehicles and 

17 percent for diesel engine equipped vehicles, estimated to result in reductions of 18 

MMT of CO2eq emissions over the lifetimes of 2014 through 2018 MY vehicles.269 The 

reductions are cost effective, estimated at $90 per ton of CO2eq removed in 2030.270 This 

cost is consistent with the light-duty rule which was estimated at $100 per ton of CO2eq 

removed in 2020 excluding fuel savings. Moreover, taking into account the fuel savings 

associated with the program, the cost becomes -$230 per ton of CO2eq (i.e. a savings of 

$230 per ton) in 2030. The cost of controls is fully recovered due to the associated fuel 

 

269 See Table VI-4 of this preamble.

270 See Table VIII-3 of this preamble.
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savings, with a payback period in the second year of ownership, as shown in Table VIII-9 

below in Section VIII. Given the large, cost effective emission reductions based on use 

of feasible technologies which are available in the lead time provided, plus the lack of 

adverse impacts on vehicle safety or utility, EPA and NHTSA regard these final

standards as appropriate and consistent with our respective statutory authorities under 

CAA section 202 (a) and NHTSA’s EISA authority under 49 U.S.C. 32902(k)(2). Based 

on the discussion above, NHTSA believes these standards are the maximum feasible 

under EISA.

(5) Alternative HD Pickup Truck and Van Standards Considered

The agencies rejected consideration of any less stringent standards given that the 

standards adopted are feasible at reasonable cost and cost-effectiveness within the lead 

time of the program. Furthermore, as explained above, because the standards are 

premised on 100 percent application of available technologies during this period, the 

agencies rejected adoption of more stringent standards. The agencies have also explained 

above why the phase-in period for the standards is reasonable and that attempting more 

aggressive phase-ins would start to force changes outside normal redesign cycles at likely 

exorbitant cost.

C. Class 2b-8 Vocational Vehicles

Vocational vehicles cover a wide variety of applications which influence both the 

body style and usage patterns. They also are built using a complex process, which 

includes additional entities such as body builders. These factors create special sensitivity

to concerns of needed lead time, as well as developing standards that do not interfere with 

vocational vehicles’ utility. The agencies are adopting a standard for vocational vehicles

for the first phase of the program that relies on less extensive addition of technology than 

do the other regulatory categories as well as making the chassis manufacturer the 

manufacturer subject to the standard. We intend that future rulemakings will consider 

increased stringency and possibly more application-specific standards. The agencies are 

also finalizing standards for the diesel and gasoline engines installed in vocational 

vehicles, similar to those discussed above for HD engines installed in Class 7 and 8 

tractors. 

(1) What Technologies Did the Agencies Consider to Reduce the CO2

Emissions and Fuel Consumption of Vocational Vehicles?

Similar to the approach taken with tractors, the agencies evaluated aerodynamic, 

tire, idle reduction, weight reduction, hybrid powertrain, and engine technologies and 

their impact on reducing fuel consumption and GHG emissions. The engines used in 

vocational vehicles include both gasoline and diesel engines, thus, each type is discussed 

separately below. As explained in Section II.D.1.b, the final regulatory structure for 

heavy-duty engines separates the compression ignition (or “diesel”) engines into three 

regulatory subcategories - light heavy, medium heavy, and heavy heavy diesel engines -- 

while spark ignition (or “gasoline”) engines are a single regulatory subcategory (an 

approach for which there was consensus in the public comments). Therefore, the 

subsequent discussion will assess each type of engine separately.
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(a) Vehicle Technologies

Vocational vehicles typically travel fewer miles than combination tractors. They

also tend to be used in more urban locations (with consequent stop and start drive cycles). 

Therefore the average speed of vocational vehicles is significantly lower than 

combination tractors. This has a significant effect on the types of technologies that are 

appropriate to consider for reducing CO2 emissions and fuel consumption.

The agencies considered the type of technologies for vocational vehicles based on 

the energy losses of a typical vocational vehicle. The technologies are similar to the ones 

considered for combination tractors. Argonne National Lab conducted an energy audit 

using simulation tools to evaluate the energy losses of vocational vehicles, such as a 

Class 6 pickup and delivery truck. Argonne found that 74 percent of the energy losses 

are attributed to the engine, 13 percent to tires, 9 percent to aerodynamics, two percent to 

transmission losses, and the remaining four percent of losses to axles and accessories for 

a medium-duty truck traveling at 30 mph.271 

Low Rolling Resistance Tires: Tires are the second largest contributor to energy

losses of vocational vehicles, as found in the energy audit conducted by Argonne 

National Lab (as just mentioned). The range of rolling resistance of tires used on 

vocational vehicles today is large. This is in part due to the fact that the competitive 

pressure to improve rolling resistance of vocational vehicle tires has been less than that 

found in the line haul tire market. In addition, the drive cycles typical for these 

applications often lead truck buyers to value tire traction and durability more heavily than 

rolling resistance. Therefore, the agencies concluded that a regulatory program that seeks 

to optimize tire rolling resistance in addition to traction and durability can bring about 

fuel consumption and CO2 emission reductions from this segment. The 2010 NAS report 

states that rolling resistance impact on fuel consumption reduces with mass of the vehicle 

and with drive cycles with more frequent starts and stops. The report found that the fuel 

consumption reduction opportunity for reduced rolling resistance ranged between one and 

three percent in the 2010 through 2020 time frame.

272

 The agencies estimate that average 

rolling resistance from tires in 2010 model year can be reduced by 10 percent for 50 

percent of the vehicles by 2014 model year based on the tire development achievements 

over the last several years in the line haul truck market.

Aerodynamics: The Argonne National lab work shows that aerodynamics has

less of an impact on vocational vehicle energy losses than do engines or tires. In 

addition, the aerodynamic performance of a complete vehicle is significantly influenced 

by the body of the vehicle. The agencies are not regulating body builders in this phase of 

regulations for the reasons discussed in Section II. Therefore, we are not basing any of 

the final standards for vocational vehicles on aerodynamic improvements. Nor would 

aerodynamic performance be input into GEM to demonstrate compliance. 

 

271 Argonne National Lab. Evaluation of Fuel Consumption Potential of Medium and Heavy-duty Vehicles 

through Modeling and Simulation. October 2009. Page 89.

272 See 2010 NAS Report, Note 197, page 146.
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Weight Reduction: NHTSA and EPA are also not basing any of the final 

vocational vehicle standards on use of vehicle weight reduction. Thus, vehicle mass 

reductions are not an input into GEM. The agencies are taking this approach despite 

comments suggesting that the agencies make use of weight reductions for this segment,

because we are unable to quantify the potential impact of weight reduction on vehicle 

utility in this broad segment. Vocational vehicles serve an incredibly diverse range of 

functions. Each of these unique vehicle functions is likely to have its own unique 

tradeoff between vehicle utility and the potential for vehicle mass reduction. The 

agencies have not been able at this time to determine the degree to which such tradeoffs 

exist nor the specific level of the tradeoff for each unique vehicle vocation. No 

commenter provided data to inform this question. Absent this information, the agencies 

cannot at this time project the potential for worthwhile weight reductions from vocational 

vehicles. 

Drivetrain: Optimization of vehicle gearing to engine performance through 

selection of transmission gear ratios, final drive gear ratios and tire size can play a 

significant role in reducing fuel consumption and GHGs. Optimization of gear selection 

versus vehicle and engine speed accomplished through driver training or automated 

transmission gear selection can provide additional reductions. The 2010 NAS report 

found that the opportunities to reduce fuel consumption in heavy-duty vehicles due to 

transmission and driveline technologies in the 2015 time frame ranged between 2 and 8 

percent.273 Initially, the agencies considered reflecting transmission choices and 

technology in our standard setting process for both tractors and vocational vehicles (see 

previous discussion above on automated manual and automatic transmissions for 

tractors). We have however decided not to do so for the following reasons. 

The primary factors that determine optimum gear selection are vehicle weight, 

vehicle aerodynamics, vehicle speed, and engine performance typically considered on a 

two dimensional map of engine speed and torque. For a given power demand 

(determined by speed, aerodynamics and vehicle mass) an optimum transmission and 

gearing setup will keep the engine power delivery operating at the best speed and torque 

points for highest engine efficiency. Since power delivery from the engine is the product 

of speed and torque a wide range of torque and speed points can be found that deliver 

adequate power, but only a smaller subset will provide power with peak efficiency. Said 

more generally, the design goal is for the transmission to deliver the needed power to the 

vehicle while maintaining engine operation within the engine’s “sweet spot” for most 

efficient operation. Absent information about vehicle mass and aerodynamics (which 

determines road load at highway speeds) it is not possible to optimize the selection of 

gear ratios for lowest fuel consumption. Truck and chassis manufacturers today offer a 

wide range of tire sizes, final gear ratios and transmission choices so that final 

bodybuilders can select an optimal combination given the finished vehicle weight, 

general aerodynamic characteristics and expected average speed. In order to set fuel 

efficiency and GHG standards that would reflect these optimizations, the agencies would 

need to regulate a wide range of small entities that are final bodybuilders, would need to 

set a large number of uniquely different standards to reflect the specific weight and 

 

273 See 2010 NAS Report, Note 197, pp 134 and 137.
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aerodynamic differences and finally would need test procedures to evaluate these 

differences that would not themselves be excessively burdensome. Finally, the agencies 

would need the underlying data regarding effectively all of the vocational trucks 

produced today in order to determine the appropriate standards. Because the market is 

already motivated to reach these optimizations themselves today, because we have 

insufficient data to determine appropriate standards, and finally, because we believe the 

testing burden would be unjustifiably high, we are not finalizing to reflect transmission 

and gear ratio optimization in our GEM or in our standard setting. 

Some commenters suggested that the agencies predicate the vocational vehicle

standard on the use of specific transmission technologies for example automated manual 

transmissions believing that these mechanically more efficient designs would inherently

provide better fuel efficiency and lower greenhouse gas emissions than conventional 

torque convertor automatic transmission designs. However as discussed above the 

agencies believe that the small mechanical efficiency differences between these 

transmission designs are relatively insignificant in the context of the dominant impact of 

proper gear ratio selection in determining a vehicle’s overall performance. In many 

cases, the mechanically more efficient design may prove less effective in use if other 

aspects of vehicle performance (such a vehicle launch under load) compromise the 

selection of gear ratios. This somewhat surprising outcome can be seen most readily by

looking at modern passenger cars where mechanically less efficient torque converter 

automatic models often produce equal or better fuel economy when compared to the 

more mechanically efficient manual transmission versions of the same vehicles. Given 

this reality, we do not believe it would be appropriate to base the vocational truck 

standard on the use of a particular transmission technology. In the future, if we develop a 

complete vehicle chassis test approach to regulating this segment, we would then be able 

to incorporate transmission performance as we already do for the heavy-duty pickup 

truck and van segment.

Idle Reduction: Episodic idling by vocational vehicles occurs during the 

workday, unlike the overnight idling of combination tractors (see discussion in Section 

III.A.2.a). Vocational vehicle idling can be divided into two typical types. The first type 

is idling while waiting – such as during a pickup or delivery. This type of idling can be 

reduced through automatic engine shut-offs. The second type of idling is to accomplish 

PTO operation, such as compacting garbage or operating a bucket. The agencies have 

found only one study that quantifies the emissions due to idling conducted by Argonne 

National Lab based on 2002 VIUS data.274 EPA conducted a work assignment to assist in 

characterizing PTO operations. The study of a utility truck used in two different 

environments (rural and urban) and a refuse hauler found that the PTO operated on 

average 28 percent of time relative to the total time spent driving and idling.275 The use 

of hybrid powertrains to reduce idling is discussed below.

 

274 Gaines, Linda, A. Vyas, J. Anderson (Argonne National Laboratory). Estimation of Fuel Use by Idling 

Commercial Trucks. January 2006.

275 Southwest Research Institute. Power Take Off Cycle Development and Testing. 2010. Docket EPAHQ-OAR-2010-0162-3335.
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Hybrid Powertrains: Several types of vocational vehicles are well suited for 

hybrid powertrains. Vehicles such as utility or bucket trucks, delivery vehicles, refuse 

haulers, and buses have operational usage patterns with either a significant amount of 

stop-and-go activity or spend a large portion of their operating hours idling the main 

engine to operate a PTO unit. The industry is currently developing many variations of 

hybrid powertrain systems. The hybrids developed to date have seen fuel consumption 

and CO2 emissions reductions between 20 and 50 percent in the field. However, there are 

still some key issues that are restricting the penetration of hybrids, including overall 

system cost, battery technology, and lack of cost-effective electrified accessories. We 

have not predicated the standards based on the use of hybrids reflecting the still nascent 

level of technology development and the very small fraction of vehicle sales they would 

be expected to account for in this time frame -- on the order of only a percent or two. 

Were we to overestimate the number of hybrids that could be produced, we would set a 

standard that is not feasible. We believe that it is more appropriate given the status of 

technology development and our hopes for future advancements in hybrid technologies to 

encourage their production through incentives. Thus, to create an incentive for early 

introduction of hybrid powertrains into the vocational vehicle fleet, the agencies are 

adopting the proposed advanced technology credits if hybrid powertrains are used as a 

technology to meet the vocational vehicle standard (or any other vehicle standard), as 

described in Section IV. 

(b) Gasoline Engine Technologies

The gasoline (or spark ignited) engines certified and sold as loose engines into the 

heavy-duty truck market are typically large V8 and V10 engines produced by General 

Motors and Ford. The basic architecture of these engines is the same as the versions used 

in the heavy-duty pickup trucks and vans. Therefore, the technologies analyzed by the 

agencies mirror the gasoline engine technologies used in the heavy-duty pickup truck 

analysis in Section III.B above. 

Building on the technical analysis underlying the light-duty 2012-2016 MY 

vehicle rule, the agencies took a fresh look at technology effectiveness values for 

purposes of this analysis using as a starting point the estimates from that rule. The 

agencies then considered the impact of test procedures (such as higher test weight of HD 

pickup trucks and vans) on the effectiveness estimates. The agencies also considered 

other sources such as the 2010 NAS Report, recent CAFE compliance data, and 

confidential manufacturer estimates of technology effectiveness. NHTSA and EPA 

engineers reviewed effectiveness information from the multiple sources for each 

technology and ensured that such effectiveness estimates were based on technology

hardware consistent with the BOM components used to estimate costs. 

The agencies note that the effectiveness values estimated for the technologies may

represent average values, and do not reflect the potentially-limitless spectrum of possible 

values that could result from adding the technology to different vehicles. For example, 

while the agencies have estimated an effectiveness of 0.5 percent for low friction 

lubricants, each vehicle could have a unique effectiveness estimate depending on the 

baseline vehicle’s oil viscosity rating. For purposes of this final rulemaking, NHTSA and 
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EPA believe that employing average values for technology effectiveness estimates is an 

appropriate way of recognizing the potential variation in the specific benefits that 

individual manufacturers (and individual engines) might obtain from adding a fuel-saving 

technology. 

Baseline Engine: Similar to the gasoline engine used as the baseline in the lightduty rule, the agencies assumed the baseline engine in this segment to be a naturally

aspirated, overhead valve V8 engine.276 The agencies did not receive any comments 

regarding the baseline engine assumptions in the proposal. The following discussion of 

effectiveness is generally in comparison to 2010 baseline engine performance.

For the final rulemaking, the agencies considered the same set of technologies for 

loose gasoline engines at proposal. The agencies received comments which suggested 

that the agencies consider electrification of accessories to reduce the fuel consumption 

and CO2 emissions from heavy-duty gasoline engines. Electrification may result in a 

reduction in power demand, because electrically powered accessories (such as the air 

compressor or power steering) operate only when needed if they are electrically powered, 

but they impose a parasitic demand all the time if they are engine driven. In other cases, 

such as cooling fans or an engine’s water pump, electric power allows the accessory to 

run at speeds independent of engine speed, which can reduce power consumption. 

However, technologies such as these improvements to accessories are not demonstrated 

using the engine dynamometer test procedures being adopted in this final rule because 

those systems are not installed on the engine during the testing. Thus, the technologies 

the agencies considered include the following:

Engine Friction Reduction: In addition to low friction lubricants, manufacturers 

can also reduce friction and improve fuel consumption by improving the design of engine 

components and subsystems. Examples include improvements in low-tension piston 

rings, piston skirt design, roller cam followers, improved crankshaft design and bearings, 

material coatings, material substitution, more optimal thermal management, and piston 

and cylinder surface treatments. The 2010 NAS, NESCCAF277 and EEA278 reports as 

well as confidential manufacturer data used in the light-duty vehicle rulemaking 

suggested a range of effectiveness for engine friction reduction to be between 1 to 3 

percent. NHTSA and EPA continue to believe that this range is accurate.

Coupled Cam Phasing: Valvetrains with coupled (or coordinated) cam phasing 

can modify the timing of both the inlet valves and the exhaust valves an equal amount by

phasing the camshaft of a single overhead cam engine or an overhead valve engine. 

Based on the light-duty 2012-2016 MY vehicle rule, previously-received confidential 

manufacturer data, and the NESCCAF report, NHTSA and EPA estimated the 

 

276 The agencies note that baseline did not include coupled cam phasing for loose HD gasoline engines. 

The HD loose engines are slightly different than the ones used in the HD pickup trucks. They tend to be 

the older versions of the same engine.

277 Northeast States Center for a Clean Air Future. “Reducing Greenhouse Gas Emissions from Light-Duty 

Motor Vehicles.” September 2004.

278 Energy and Environmental Analysis, Inc. “Technology to Improve the Fuel Economy of Light Duty 

Trucks to 2015.” May 2006.
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effectiveness of couple cam phasing CCP to be between 1 and 4 percent. NHTSA and 

EPA reviewed this estimate for purposes of the NPRM, and continue to find it accurate. 

Cylinder Deactivation: In conventional spark-ignited engines throttling the 

airflow controls engine torque output. At partial loads, efficiency can be improved by

using cylinder deactivation instead of throttling. Cylinder deactivation can improve 

engine efficiency by disabling or deactivating (usually) half of the cylinders when the 

load is less than half of the engine’s total torque capability – the valves are kept closed, 

and no fuel is injected – as a result, the trapped air within the deactivated cylinders is 

simply compressed and expanded as an air spring, with reduced friction and heat losses.

The active cylinders combust at almost double the load required if all of the cylinders 

were operating. Pumping losses are significantly reduced as long as the engine is 

operated in this “part cylinder” mode. Effectiveness improvements scale roughly with

engine displacement-to-vehicle weight ratio: the higher displacement-to-weight vehicles, 

operating at lower relative loads for normal driving, have the potential to operate in partcylinder mode more frequently. Cylinder deactivation is less effective on heavily-loaded 

vehicles because they require more power and spend less time in areas of operation where 

only partial power is required. The technology also requires proper integration into the 

vehicles which is difficult in the vocational vehicle segment where often the engine is 

sold to a chassis manufacturer or body builder without knowing the type of transmission 

or axle used in the vehicle or the precise duty cycle of the vehicle. The cylinder 

deactivation requires fine tuning of the calibration as the engine moves into and out of 

deactivation mode to achieve acceptable NVH. Additionally, cylinder deactivation 

would be difficult to apply to vehicles with a manual transmission because it requires 

careful gear change control. NHTSA and EPA adjusted the 2012-16 MY light-duty rule 

estimates using updated power to weight ratings of heavy-duty trucks and confidential 

business information and downwardly adjusted the effectiveness to 0 to 3 percent for 

these vehicles to reflect the differences in drive cycle and operational opportunities 

compared to light-duty vehicles. Because of the complexities associated with integrating 

cylinder deactivation in a non-integrated vehicle assembly process and the low 

effectiveness of the technology, the agencies did not include cylinder deactivation in the 

final gasoline engine technology package.

Stoichiometric gasoline direct injection: SGDI (also known as spark-ignition 

direct injection engines) inject fuel at high pressure directly into the combustion chamber 

(rather than the intake port in port fuel injection). Direct injection of the fuel into the 

cylinder improves cooling of the air/fuel charge within the cylinder, which allows for 

higher compression ratios and increased thermodynamic efficiency without the onset of 

combustion knock. Recent injector design advances, improved electronic engine 

management systems and the introduction of multiple injection events per cylinder firing 

cycle promote better mixing of the air and fuel, enhance combustion rates, increase 

residual exhaust gas tolerance and improve cold start emissions. SGDI engines achieve 

higher power density and match well with other technologies, such as boosting and 

variable valvetrain designs. The light-duty 2012-2016 MY vehicle rule estimated the 

effectiveness of SGDI to be between 2 and 3 percent. NHTSA and EPA revised these 

estimated accounting for the use and testing methods for these vehicles along with 

confidential business information estimates received from manufacturers while 
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developing the program. Based on these revisions, NHTSA and EPA estimate the range 

of 1 to 2 percent for SGDI. 

(c) Diesel Engine Technologies

Different types of diesel engines are used in vocational vehicles, depending on the 

application. They fall into the categories of Light, Medium, and Heavy Heavy-duty

Diesel engines. The Light Heavy-duty Diesel engines typically range between 4.7 and 

6.7 liters displacement. The Medium Heavy-duty Diesel engines typically have some 

overlap in displacement with the Light Heavy-duty Diesel engines and range between 6.7 

and 9.3 liters. The Heavy Heavy-duty Diesel engines typically are represented by

engines between 10.8 and 16 liters. 

Baseline Engine: There are three baseline diesel engines, a Light, Medium, and a 

Heavy Heavy-duty Diesel engine. The agencies developed the baseline diesel engine as a 

2010 model year engine with an aftertreatment system which meets EPA’s 0.2 grams of 

NOX/bhp-hr standard with an SCR system along with EGR and meets the PM emissions 

standard with a diesel particulate filter with active regeneration. The engine is 

turbocharged with a variable geometry turbocharger. As noted above in Section 

III.A.1.b, the agencies received comments from Navistar stating that the agencies used an 

artificially low baseline CO2 emissions level which was tilted toward the use of SCR 

aftertreatment system. As discussed in Section III.A.1.b, the agencies disagree with the 

statement that SCR is infeasible. Additional responses from the agencies are available in 

the Response to Comments document, Section 6.2.279 The following discussion of 

technologies describes improvements over the 2010 model year baseline engine 

performance, unless otherwise noted. Further discussion of the baseline engine and its 

performance can be found in Section III.C.2.(c)(i) below. The following discussion of 

effectiveness is generally in comparison to 2010 baseline engine performance, and is in 

reference to performance in terms of the Heavy-duty FTP that would be used for 

compliance for these engine standards. This is in comparison to the steady state SET 

procedure that would be used for compliance purposes for the engines used in Class 7 

and 8 tractors. See Section II.B.2.(i) above.

Turbochargers: Improved efficiency of a turbocharger compressor or turbine

could reduce fuel consumption by approximately 1 to 2 percent over today’s variable 

geometry turbochargers in the market today. The 2010 NAS report identified 

technologies such as higher pressure ratio radial compressors, axial compressors, and 

dual stage turbochargers as design paths to improve turbocharger efficiency.

Low Temperature Exhaust Gas Recirculation: Most LHDD, MHDD, and HHDD 

engines sold in the U.S. market today use cooled EGR, in which part of the exhaust gas is 

routed through a cooler (rejecting energy to the engine coolant) before being returned to 

the engine intake manifold. EGR is a technology employed to reduce peak combustion 

temperatures and thus NOX. Low-temperature EGR uses a larger or secondary EGR 

 

279 U.S. EPA. Greenhouse Gas Emissions Standards and Fuel Efficiency Standards for Medium- and 

Heavy-Duty Engines and Vehicles - EPA Response to Comments Document for Joint Rulemaking . EPA420-R-11-004. Docket EPA-HQ-OAR-2010-0162.
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cooler to achieve lower intake charge temperatures, which tend to further reduce NOX

formation. If the NOX requirement is unchanged, low-temperature EGR can allow 

changes such as more advanced injection timing that will increase engine efficiency

slightly more than one percent. Because low-temperature EGR reduces the engine’s 

exhaust temperature, it may not be compatible with exhaust energy recovery systems 

such as turbocompounding or a bottoming cycle.

Engine Friction Reduction: Reduced friction in bearings, valve trains, and the 

piston-to-liner interface will improve efficiency. Any friction reduction must be carefully

developed to avoid issues with durability or performance capability. Estimates of fuel 

consumption improvements due to reduced friction range from 0.5 to 1.5 percent.280

Selective catalytic reduction: This technology is common on 2010 heavy-duty

diesel engines. Because SCR is a highly effective NOX aftertreatment approach, it 

enables engines to be optimized to maximize fuel efficiency, rather than minimize 

engine-out NOX. 2010 SCR systems are estimated to result in improved engine 

efficiency of approximately 4 to 5 percent compared to a 2007 in-cylinder EGR-based 

emissions system and by an even greater percentage compared to 2010 in-cylinder 

approaches.281 As more effective low-temperature catalysts are developed, the NOX

conversion efficiency of the SCR system will increase. Next-generation SCR systems 

could then enable still further efficiency improvements; alternatively, these advances 

could be used to maintain efficiency while down-sizing the aftertreatment. We estimate 

that continued optimization of the catalyst could offer 1 to 2 percent reduction in fuel use 

over 2010 model year systems in the 2014 model year.282 The agencies also estimate that 

continued refinement and optimization of the SCR systems could provide an additional 2 

percent reduction in the 2017 model year.

Improved Combustion Process: Fuel consumption reductions in the range of 1 to 

4 percent are identified in the 2010 NAS report through improved combustion chamber 

design, higher fuel injection pressure, improved injection shaping and timing, and higher 

peak cylinder pressures.283

Reduced Parasitic Loads: Accessories that are traditionally gear or belt driven by

a vehicle’s engine can be optimized and/or converted to electric power. Examples include 

the engine water pump, oil pump, fuel injection pump, air compressor, power-steering 

pump, cooling fans, and the vehicle’s air-conditioning system. Optimization and 

improved pressure regulation may significantly reduce the parasitic load of the water, air 

and fuel pumps. Electrification may result in a reduction in power demand, because 

electrically powered accessories (such as the air compressor or power steering) operate 

only when needed if they are electrically powered, but they impose a parasitic demand all 

the time if they are engine driven. In other cases, such as cooling fans or an engine’s 

 

280 See TIAX, Note 198, pg 4-15

281 Stanton, D. “Advanced Diesel Engine Technology Development for High Efficiency, Clean 

Combustion.” Cummins, Inc. Annual Progress Report 2008 Vehicle Technologies Program: Advanced 

Combustion Engine Technologies, US Department of Energy. Pp 113-116. December 2008.

282 See TIAX, Note 198, pg. 4-9

283 See 2010 NAS Report, Note 197, page 56. 
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water pump, electric power allows the accessory to run at speeds independent of engine 

speed, which can reduce power consumption. The TIAX study used 2 to 4 percent fuel 

consumption improvement for accessory electrification, with the understanding that 

electrification of accessories will have more effect in short-haul/urban applications and 

less benefit in line-haul applications.284

(2) What Is the Projected Technology Package’s Effectiveness and Cost?

(a) Vocational Vehicles

(i) Baseline Vocational Vehicle Performance

The baseline vocational vehicle model is defined in the GEM, as described in RIA 

Chapter 4.4.6. At proposal, the agencies used a baseline rolling resistance coefficient for 

today’s vocational vehicle fleet of 9.0 kg/metric ton.285 As discussed in Section II.D.1, 

the agencies conducted a tire rolling resistance evaluation of tires used in vocational 

vehicles. The agencies found that the average rolling resistance of the tires was lower 

than the agencies’ assessment at proposal. Based on this new information and our 

understanding of the potential to improve tire rolling resistance by 2014, the agencies are 

setting the vocational truck standard premised on the use of tires with a rolling resistance 

coefficient of 7.7 kg/metric ton. This value is consistent with the average performance of 

the subset of tires the agencies tested. We are projecting this standard will drive a 5 

percent reduction in tire rolling resistance on average across the fleet. We are projecting 

this 5 percent reduction based on our expectation that manufacturers will desire to bring 

all of their tires below the standard (not just comply on average) and knowing 

manufacturers will need some degree of overcompliance to ensure despite manufacturing 

variability and test to test variability their products are compliant with the emission 

standards. In order to reflect both this tighter standard (based on 7.7) and the 5 percent 

reduction in rolling resistance we project it will accomplish, we are modeling the baseline 

performance of vocational truck tires as 8.1 kg/metric ton.

Further vehicle technology is not included in this baseline, as discussed below in 

the discussion of the baseline vocational vehicle. The baseline engine fuel consumption 

represents a 2010 model year diesel engine, as described in RIA Chapter 4. Using these 

values, the baseline performance of these vehicles is included in Table III-12. 

The agencies note that the baseline performance derived for the final rule slightly

differs from the values derived for the NPRM. The first difference is due to the change in 

rolling resistance from 9.0 to 8.1 kg/metric ton based on the agencies’ post-proposal test 

results. Second, there are minor differences in the fuel consumption and CO2 emissions 

 

284 See TIAX. Note 198, Pages 3-5.

285 The baseline tire rolling resistance for this segment of vehicles was derived for the proposal based on the 

current baseline tractor and passenger car tires. The baseline tractor drive tire has a rolling resistance of 8.2 

kg/metric ton based on SmartWay testing. The average passenger car has a tire rolling resistance of 9.75 

kg/metric ton based on a presentation made to CARB by the Rubber Manufacturer’s Association. As noted 

above, further analysis has resulted in an estimate of improved performance in the baseline fleet, which is 

based entirely on use of LRR tires on vocational vehicles (not cars). Additional details are available in the 

RIA Chapter 2. 
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due to the small modifications made to the GEM, as noted in RIA Chapter 4. In addition, 

the HHD vocational vehicle baseline performance for the final rule uses a revised 

payload assumption from 38,000 to 15,000 pounds, as described in Section II.D.3.c.iii. 

Table III-12: Baseline Vocational Vehicle Performance

Vocational Vehicle

Light HeavyDutyMedium 

Heavy-Duty

Heavy 

Heavy-Duty

Fuel Consumption Baseline 

(gallon/1,000 ton-mile)

40.0 24.3 23.2

CO2 Baseline (grams 

CO2/ton-mile)

408 247 236

(ii) Vocational Vehicle Technology Package

The final program for vocational vehicles for this phase of regulatory standards is 

based on the performance of tire and engine technologies. Aerodynamics technology, 

weight reduction, drive train improvement, and hybrid power trains are not included for 

the reasons discussed above in Section III.C (1) and Section II.D. 

The assessment of the final technology effectiveness was developed through the 

use of the GEM. To account for the two final engine standards, EPA is finalizing the use 

of a 2014 model year fuel consumption map in the GEM to derive the 2014 model year 

truck standard and a 2017 model year fuel consumption map to derive the 2017 model 

year truck standard. (These fuel consumption maps reflect the main standards for HD 

diesel engines, not the alternative engine standards.) The agencies estimate that the 

rolling resistance of 50 percent of the tires can be reduced by 10 percent in the 2014 

model year, for an overall reduction in rolling resistance of 5 percent. The vocational 

vehicle standards for all three regulatory categories were determined using a tire rolling 

resistance coefficient of 7.7 kg/metric ton in the 2014 model year. The set of input 

parameters which are modeled in GEM are shown in Table III-13. 

Table III-13: GEM Inputs for Final Vocational Vehicle Standards

2014 MY 2017 MY

Engine 2014 MY 7L for 

LHD/MHD and 15L for 

HHD Trucks 

2017 MY 7L for 

LHD/MHD and 15L for 

HHD Trucks

Tire Rolling Resistance 

(kg/metric ton)

7.7 7.7

The agencies developed the final standards by using the engine and tire rolling 

resistance inputs in the GEM, as shown in Table III-13. The percent reductions shown in 

Table III-14 reflect improvements over the 2010 model year baseline vehicle with a 2010 

model year baseline engine.
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Table III-14: Final Vocational Vehicle Standards and Percent Reductions

Vocational Vehicle

Light 

HeavyDuty

Medium 

HeavyDuty

Heavy 

HeavyDuty

2016 MY Fuel Consumption Standard 

(gallon/1,000 ton-mile)

38.1 23.0 22.2

2017 MY Fuel Consumption Standard 

(gallon/1,000 ton-mile)

36.7 22.1 21.8

2014 MY CO2 Standard (grams CO2/tonmile)388 234 226

2017 MY CO2 Standard (grams CO2/tonmile)373 225 222

Percent Reduction from 2010 baseline in 

2014 MY

5% 5% 4%

Percent Reduction from 2010 baseline in 

2017 MY

8% 9% 6%

(iii) Technology Package Cost

The agencies did not receive any substantial comments on the engine costs 

proposed. Thus the agencies are projecting the costs of the technologies used to develop 

the final standards based on the costs used in the proposal, but revised to reflect 2009$, 

new ICMs, and a 50 percent penetration rate of low rolling resistance tires (as explained 

above). EPA and NHTSA developed the costs of LRR tires based on the ICF report. The 

estimated cost per truck is $81 (2009$) for LHD and MHD trucks and $97 (2009$) for 

HHD trucks. These costs include a low complexity ICM of 1.18 and are applicable in the 

2014 model year. 

(iv) Reasonableness of the Final Vocational Vehicle Standards

The final standards would not only add only a small amount to the vehicle cost, 

but are highly cost effective, an estimated $20 ton of CO2eq per vehicle in 2030.286 This 

is even less than the estimated cost effectiveness for CO2eq removal under the light-duty 

vehicle rule, already considered by the agencies to be a highly cost effective reduction.287 

Moreover, the modest cost of controls is recovered almost immediately due to the 

associated fuel savings, as shown in the payback analysis included in Table VIII-7. 

Given that the standards are technically feasible within the lead time afforded by the 2014 

model year, are inexpensive and highly cost effective, and do not have other adverse 

potential impacts (e.g., there are no projected negative impacts on safety or vehicle 

utility), the final standards represent a reasonable choice under section 202(a) of the CAA

and NHTSA’s EISA authority under 49 U.S.C. 32902(k)(2), and the agencies believe that 

 

286 See Section VIII.D.

287 As noted above, the light-duty rule had an estimated cost per ton of $50 when considering the vehicle 

program costs only and a cost of -$210 per ton considering the vehicle program costs along with fuel 

savings in 2030. See 75 FR 25515, Table III.H.3-1.
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the standards are consistent with their respective authorities. Based on the discussion 

above, NHTSA believes these standards are the maximum feasible under EISA.

(v) Alternative Vehicle Standards Considered

The agencies are not finalizing vehicle standards less stringent than the final 

standards because the agencies believe these standards are highly cost effective, as just 

explained.

The agencies considered finalizing truck standards which are more stringent 

reflecting the inclusion of hybrid powertrains in those vocational vehicles where use of 

hybrid powertrains is appropriate. The agencies estimate that a 25 percent utilization rate 

of hybrid powertrains in MY 2017 vocational vehicles would add, on average, $30,000 to 

the cost of each vehicle and more than double the cost of the rule for this sector. See the 

RIA at Chapter 6.1.8. The emission reductions associated with these very high costs 

appear to be modest. See the RIA Table 6-14. In addition, the agencies are finalizing 

flexibilities in the form of generally applicable credit opportunities for advanced 

technologies, to encourage use of hybrid powertrains. See Section IV.C. 2 below. 

Several commenters recommended that in addition to hybrid powertrains, the agencies 

consider setting more stringent standards based on the use of aerodynamic improvements, 

weight reduction, idle shutdown technologies, vehicle speed limiters, and specific 

transmission technologies. As described above, we are not finalizing standards based on 

these technologies for reasons that related to the unique nature of the very diverse 

vocational vehicle segment. At this time, the agencies have no means to determine the 

current baseline aerodynamic performance of all vocational vehicles (ranging from 

concrete mixers to school buses), nor a means to project to what degree the aerodynamic 

performance could be improved without compromising the utility of the vehicle. Absent 

this information, the agencies cannot set a standard based on improvements in 

aerodynamic performance. The agencies face similar obstacles regarding our ability to 

project the utility tradeoffs that may exist between limitations on vehicle speed or 

reductions in vehicle mass and utility and safety of vocational vehicles. We are confident 

the answer to those questions will differ for a school bus compared to a concrete mixer 

compared to a fire truck compared to an ambulance. Absent an approach to set distinct 

standards for each of the vocational vehicle types and the information necessary to 

determine the appropriate level of performance for those vehicles, the agencies cannot set 

standards for vocational vehicles based on the use of these technologies. For these 

reasons, the agencies are not adopting more comprehensive standards for vocational 

vehicles. The agencies do agree that at least some vocational vehicles can be made more 

efficient through the use of technologies, including those technologies mentioned in the 

comments, and the agencies fully intend to take on the challenge of developing the data, 

test procedures and regulatory structures necessary to set more comprehensive standards 

for vocational trucks in the future.
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(b) Gasoline Engines

(i) Baseline Gasoline Engine Performance

EPA and NHTSA developed the reference heavy-duty gasoline engines to 

represent a 2010 model year engine compliant with the 0.20 g/bhp-hr NOX standard for 

on-highway heavy-duty engines. 

NHTSA and EPA developed the baseline fuel consumption and CO2 emissions 

for the gasoline engines from manufacturer reported CO2 values used in the certification 

of non-GHG pollutants. The baseline engine for the analysis was developed to represent 

a 2011 model year engine, because this is the most current information available. The 

average CO2 performance of the heavy-duty gasoline engines was 660 g/bhp-hour, which 

will be used as a baseline. The baseline gasoline engines are all stoichiometric port fuel 

injected V-8 engines without cam phasers or other variable valve timing technologies. 

While they may reflect some degree of static valve timing optimization for fuel efficiency

they do not reflect the potential to adjust timing with engine speed.

(ii) Gasoline Engine Technology Package Effectiveness

The gasoline engine technology package includes engine friction reduction, 

coupled cam phasing, and SGDI to produce an overall five percent reduction from the 

reference engine based on the Heavy-duty Lumped Parameter model. The agencies are 

projecting a 100 percent application rate of this technology package to the heavy-duty 

gasoline engines, which results in a CO2 standard of 627 g/bhp-hr and a fuel consumption 

standard of 7.05 gallon/100 bhp-hr. As discussed in Section II.D.b.ii, the agencies are 

adopting gasoline engine standards that begin in the 2016 model year based on the 

agencies’ projection of the engine redesign schedules for the small number of engines in 

this category.

(iii) Gasoline Engine Technology Package Cost

For the proposed costs, the agencies considered both the direct or “piece” costs 

and indirect costs of individual components of technologies. For the direct costs, the 

agencies followed a BOM approach employed by NHTSA and EPA in the light-duty 

2012-2016 MY vehicle rule. In this final action, the agencies are using marked up 

gasoline engine technology costs developed for the HD Pickup Truck and Van segment 

because these engines are made by the same manufacturers (primarily by Ford and GM) 

and are simply, sold as loose engines rather than as complete vehicles. Hence the engine 

cost estimates are fundamentally the same. The agencies did not receive any comments 

recommending adjustments to the proposed gasoline engine technology costs. The costs 

summarized in Table III-15 are consistent with the proposed values, but updated to reflect 

2009$ and new ICMs. The costs shown in Table III-15 include a low complexity ICM of 

1.24 and are applicable in the 2016 model year. No learning effects are applied to engine 

friction reduction costs, while flat-portion of the curve learning is considered applicable 

to both coupled cam phasing and SGDI.
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Table III-15: Heavy-duty Gasoline Engine Technology Costs inclusive of Indirect Cost Markups 

(2009$)

2016MY

Engine Friction Reduction $95

Coupled Cam Phasing $46

Stoichiometric Gas Direct Injection $452

Total $594

(iv) Reasonableness of the Final Standard

The final engine standards are reasonable and consistent with the agencies’ 

respective authorities. With respect to the 2016 MY standard, all of the technologies on 

which the standards are predicated have been demonstrated and their effectiveness is well 

documented. The final standards reflect a 100 percent application rate for these 

technologies. The costs of adding these technologies remain modest across the various 

engine classes as shown in Table III-15. Use of these technologies would add only a 

small amount to the cost of the vehicle,288 and the associated reductions are highly cost 

effective, an estimated $20 per ton of CO2eq per vehicle.289 This is even more cost 

effective than the estimated cost effectiveness for CO2eq removal and fuel economy 

improvement under the light-duty vehicle rule, already considered by the agencies to be a 

highly cost effective reduction.290 Accordingly, EPA and NHTSA view these standards 

as reflecting an appropriate balance of the various statutory factors under section 202(a) 

of the CAA and under NHTSA’s EISA authority at 49 U.S.C. 32902(k)(2). Based on the 

discussion above, NHTSA believes these standards are the maximum feasible under 

EISA. 

Several commenters suggested that the lead time provided by the agencies for 

heavy-duty pickups and vans and by extension the 2016 gasoline engine standards were 

unnecessarily long. The agencies do not agree with this assessment. The technologies 

that we are considering here cannot simply be bolted on to an existing engine but can 

only be effectively applied through an integrated design and development process. The 

four years lead time provided here is short in the context of engine redesigns and is only

possible in part because the standards align with engine manufacturers’ planned redesign 

processes that are either just starting or will be starting within the year. These standards 

set a clear metric of performance for those planned redesigns and we project will lead 

manufacturers to include a number of technologies that would not otherwise have been 

incorporated into those engines.

 

288 Sample 2010 MY vocational vehicles range in price between $40,000 for a Class 4 work truck to 

approximately $200,000 for a Class 8 refuse hauler. See pages 16-17 of ICF’s “Investigation of Costs for 

Strategies to Reduce Greenhouse Gas Emissions for Heavy-Duty On-Road Vehicles.” July 2010.

289 See Vocational Vehicle CO2 savings and technology costs in Table 7-4 in RIA Chapter 7.

290 The light-duty rule had an estimated cost per ton of $50 when considering the vehicle program costs 

only and a cost of -$210 per ton considering the vehicle program costs along with fuel savings in 2030. See

75 FR 25515, Table III.H.3-1. 
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(v) Alternative Gasoline Engine Standards Considered

The agencies are not finalizing gasoline standards less stringent than the final 

standards because the agencies believe these standards are feasible in the lead time 

provided, inexpensive, and highly cost effective. 

The final rule reflects 100 percent penetration of the technology package on 

whose performance the standard is based, so some additional technology would need to 

be added to obtain further improvements. The agencies considered finalizing gasoline 

engine standards which are more stringent reflecting the inclusion of cylinder 

deactivation and other advanced technologies. However, the agencies are not finalizing 

this level of stringency because our assessment is that these technologies cannot be 

adapted to the higher average engine loads of heavy-duty vehicles for production by the 

2017 model year. We intend to continue to evaluate the potential for further gasoline 

engine improvements building on the work done for light-duty passenger cars and trucks 

as we begin work on the next phase of heavy-duty regulations.

(c) Diesel Engines

(i) Baseline Diesel Engine Performance

EPA and NHTSA developed the baseline heavy-duty diesel engines to represent a 

2010 model year engine compliant with the 0.20 g/bhp-hr NOX standard for on-highway

heavy-duty engines. 

The agencies utilized 2007 through 2011 model year CO2 certification levels from 

the Heavy-duty FTP cycle as the basis for the baseline engine CO2 performance. The

pre-2010 data are subsequently adjusted to represent 2010 model year engine maps by

using predefined technologies including SCR and other systems that are being used in 

current 2010 production. The engine CO2 results were then sales weighted within each 

regulatory subcategory to develop an industry average 2010 model year reference engine, 

as shown in Table III-16. The level of CO2 emissions and fuel consumption of these 

engines varies significantly, where the engine with the highest CO2 emissions is 

estimated to be 20 percent greater than the sales weighted average. Details of this 

analysis are included in RIA Chapter 2.
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Table III-16: 2010 Model Year Reference Diesel Engine Performance Over the Heavy-duty FTP 

Cycle

CO2 Emissions (g/bhp-hr) Fuel Consumption 

(gallon/100 bhp-hr)

LHD Diesel 630 6.19

MHD Diesel 630 6.19

HHD Diesel 584 5.74

(ii) Diesel Engine Packages

The diesel engine technology packages for the 2014 model year include engine 

friction reduction, improved aftertreatment effectiveness, improved combustion 

processes, and low temperature EGR system optimization. The improvements in 

parasitic and friction losses come through piston designs to reduce friction, improved 

lubrication, and improved water pump and oil pump designs to reduce parasitic losses. 

The aftertreatment improvements are available through lower backpressure of the 

systems and optimization of the engine-out NOX levels. Improvements to the EGR 

system and air flow through the intake and exhaust systems, along with turbochargers can 

also produce engine efficiency improvements. It should be pointed out that individual 

technology improvements are not additive to each other due to the interaction of 

technologies. The agencies assessed the impact of each technology over the Heavy-duty

FTP and project an overall cycle improvement in the 2014 model year of 3 percent for 

HHD diesel engines and 5 percent for LHD and MHD diesel engines, as detailed in RIA 

Chapter 2.4.2.9 and 2.4.2.10. EPA used a 100 percent application rate of this technology

package to determine the level of the final 2014 MY standards

Recently, EPA’s heavy-duty highway engine program for criteria pollutants 

provided new emissions standards for the industry in three year increments. The heavyduty engine manufacturer product plans have fallen into three year cycles to reflect this 

environment. EPA is finalizing CO2 emission standards recognizing the opportunity for 

technology improvements over this time frame while reflecting the typical heavy-duty 

engine manufacturer product plan redesign cycles. Thus, the agencies are establishing

initial standards for the 2014 model year and a more stringent standard for these heavyduty engines beginning in the 2017 model year.

The 2017 model year technology package for LHD and MHD diesel engine 

includes continued development and refinement of the 2014 model year technology

package, in particular the additional improvement to aftertreatment systems. This 

package leads to a projected 9 percent reduction for LHD and MHD diesel engines in the 

2017 model year. The HHD diesel engine technology packages for the 2017 model year 

include the continued development of the 2014 model year technology package. A 

similar approach to evaluating the impact of individual technologies as taken to develop 

the overall reduction of the 2014 model year package was taken with the 2017 model 

year package. The Heavy-duty FTP cycle improvements lead to a 5 percent reduction on 

the cycle for HHDD, as detailed in RIA Chapter 2.4.2.13. The agencies used a 100 

percent application rate of the technology package to determine the final 2017 MY 
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standards. The agencies believe that bottom cycling technologies are still in the 

development phase and will not be ready for production by the 2017 model year.291 

Therefore, these technologies were not included in determining the stringency of the final 

standards. However, we do believe the bottoming cycle approach represents a significant 

opportunity to reduce fuel consumption and GHG emissions in the future for vehicles that 

operate under primarily steady-state conditions like line-haul tractors and some 

vocational vehicles. As discussed above, we also considered setting standards based on 

the use of hybrid powertrains that are a better match to many vocational vehicle duty

cycles but have decided for the reasons articulated above to not base the vocational 

vehicle standard on the use of hybrid technologies in this first regulation. However, EPA 

and NHTSA are both finalizing provisions described in Section IV to create incentives 

for manufacturers to continue to invest to develop these technologies in the believe that 

with further development these technologies can form the basis of future standards.

The overall projected improvements in CO2 emissions and fuel consumption over 

the baseline are included in Table III-17.

Table III-17: Percent Fuel Consumption and CO2 Emission Reductions Over the Heavy-duty FTP 

Cycle

2014 2017

LHD Diesel 5% 9%

MHD Diesel 5% 9%

HHD Diesel 3% 5%

(iii) Technology Package Costs

NHTSA and EPA jointly developed costs associated with the engine technologies 

to assess an overall package cost for each regulatory category. Our engine cost estimates 

for diesel engines used in vocational vehicles include a separate analysis of the 

incremental part costs, research and development activities, and additional equipment,

such as emissions equipment to measure N2O emissions. Our general approach used 

elsewhere in this action (for HD pickup trucks, gasoline engines, Class 7 and 8 tractors, 

and Class 2b-8 vocational vehicles) estimates a direct manufacturing cost for a part and 

marks it up based on a factor to account for indirect costs. See also 75 FR 25376. We 

believe that approach is appropriate when compliance with final standards is achieved 

generally by installing new parts and systems purchased from a supplier. In such a case, 

the supplier is conducting the bulk of the research and development on the new parts and 

systems and including those costs in the purchase price paid by the original equipment 

manufacturer. The indirect costs incurred by the original equipment manufacturer need 

not include much cost to cover research and development since the bulk of that effort is 

already done. For the MHD and HHD diesel engine segment, however, the agencies 

believe we can make a more accurate estimate of technology cost using this alternate 

approach because the primary cost is not expected to be the purchase of parts or systems 

 

291 TIAX noted in their report to the NAS panel that the engine improvements beyond 2015 model year 

included in their report are highly uncertain, though they include waste heat recovery in the engine package 

for 2016 through 2020 (page 4-29).
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from suppliers or even the production of the parts and systems, but rather the 

development of the new technology by the original equipment manufacturer itself. 

Therefore, the agencies believe it more accurate to directly estimate the indirect costs. 

EPA commonly uses this approach in cases where significant investments in research and 

development can lead to an emission control approach that requires no new hardware. 

For example, combustion optimization may significantly reduce emissions and cost a 

manufacturer millions of dollars to develop but will lead to an engine that is no more 

expensive to produce. Using a bill of materials approach would suggest that the cost of 

the emissions control was zero reflecting no new hardware and ignoring the millions of 

dollars spent to develop the improved combustion system. Details of the cost analysis are 

included in the RIA Chapter 2. To reiterate, we have used this different approach 

because the MHD and HHD diesel engines are expected to comply in large part via 

technology changes that are not reflected in new hardware but rather knowledge gained 

through laboratory and real world testing that allows for improvements in control system 

calibrations – changes that are more difficult to reflect through direct costs with indirect 

cost multipliers.

The agencies developed the engineering costs for the research and development of 

diesel engines with lower fuel consumption and CO2 emissions. The aggregate costs for 

engineering hours, technician support, dynamometer cell time, and fabrication of 

prototype parts are estimated at $6.8 million (2009$) per manufacturer per year over the 

five years covering 2012 through 2016. In aggregate, this averages out to $284 per 

engine during 2012 through 2016 using an annual sales value of 600,000 light, medium,

and heavy heavy-duty engines. The agencies received comments from Horriba regarding 

the assumption the agencies used in the proposal that said manufacturers would need to 

purchase new equipment for measuring N2O and the associated costs. Horriba provided 

information regarding the cost of stand-alone FTIR instrumentation (estimated at $50,000 

per unit) and cost of upgrading existing emission measurement systems with NDIR 

analyzers (estimated at $25,000 per unit). The agencies further analyzed our assumptions 

along with Horriba’s comments. Thus, we have revised the equipment costs estimates 

and assumed that 75 percent of manufacturers would update existing equipment while the 

other 25 percent would require new equipment. The agencies are estimating costs of 

$63,087 (2009$) per engine manufacturer per engine subcategory (light, medium, and 

heavy HD) to cover the cost of purchasing photo-acoustic measurement equipment for 

two engine test cells. This would be a one-time cost incurred in the year prior to 

implementation of the standard (i.e., the cost would be incurred in 2013). In aggregate, 

this averages out to less than $1 per engine in 2013 using an annual sales value of 

600,000 light, medium, and heavy HD engines.

EPA also developed the incremental piece cost for the components to meet each 

the 2014 and 2017 standards. These costs shown in Table III-18 which include a low 

complexity ICM of 1.15; flat-portion of the curve learning is considered applicable to 

each technology.
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Table III-18: Heavy-duty Diesel Engine Component Costs inclusive of Indirect Cost Markupsa

(2009$)

2014 Model Year 2017 Model 

Year

Cylinder Head (flow optimized, increased 

firing pressure, improved thermal 

management)

$6 (MHD & HH)

$11 (LHD)

$6 (MHD & 

HHD)

$10 (LHD)

Exhaust Manifold (flow optimized, 

improved thermal management)

$0 $0

Turbocharger (improved efficiency) $18 $17

EGR Cooler (improved efficiency) $4 $3

Water Pump (optimized, variable vane, 

variable speed)

$91 $84

Oil Pump (optimized) $5 $4

Fuel Pump (higher working pressure, 

increased efficiency, improved pressure 

regulation)

$5 $4

Fuel Rail (higher working pressure) $10 (MHD & 

HHD)

$12 (LHD)

$9 (MHD & 

HHD)

$11 (LHD)

Fuel Injector (optimized, improved multiple 

event control, higher working pressure)

$11 (MHD & 

HHD)

$15 (LHD)

$10 (MHD & 

HHD)

$13 (LHD)

Piston (reduced friction skirt, ring and pin) $3 $3

Aftertreatment system (improved 

effectiveness SCR, dosing, dpf)a

$0 (MHD & 

HHD)

$111 (LHD)

$0 (MHD & 

HHD)

$101 (LHD)

Valve Train (reduced friction, roller tappet) $82 (MHD)

$109 (LHD)

$76 (MHD)

$101 (LHD)

Note:

a Note that costs for aftertreatment improvements for MHD and HHD diesel engines are covered via 

the engineering costs (see text). For LH diesel engines, we have included the cost of aftertreatment 

improvements as a technology cost.

The overall costs for each diesel engine regulatory subcategory are included in 

Table III-19.
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Table III-19: Diesel Engine Technology Costs per Engine (2009$)

2014 2017

LHD Diesel $388 $358

MHD Diesel $234 $216

HHD Diesel $234 $216

(iv) Reasonableness of the Final Standards

The final engine standards appear to be reasonable and consistent with the 

agencies’ respective authorities. With respect to the 2014 and 2017 MY standards, all of 

the technologies on which the standards are based have already been demonstrated and 

their effectiveness is well documented. The final standards reflect a 100 percent 

application rate for these technologies. The costs of adding these technologies remain 

modest across the various engine classes as shown in Table III-19. Use of these 

technologies would add only a small amount to the cost of the vehicle,292 and the 

associated reductions are highly cost effective, an estimated $20 per ton of CO2eq per 

vehicle.293 This is even more cost effective than the estimated cost effectiveness for 

CO2eq removal and fuel economy improvement under the light-duty vehicle rule, already

considered by the agencies to be a highly cost effective reduction.294 Accordingly, EPA 

and NHTSA view these standards as reflecting an appropriate balance of the various 

statutory factors under section 202(a) of the CAA and under NHTSA’s EISA authority at 

49 U.S.C. 32902(k)(2). Based on the discussion above, NHTSA believes these standards 

are the maximum feasible under EISA.

(v) Alternative Diesel Engine Standards Considered

Other than the specific option related to legacy engine products, the agencies are 

not finalizing diesel engine standards less stringent than the final standards because the 

agencies believe these standards are highly cost effective. 

The agencies have not considered finalizing diesel engine standards which are 

more stringent because we have exhausted the list of engine technologies that we believe 

are directly applicable to medium- and heavy-duty diesel engines used in vocational 

applications. We are continuing to evaluate the potential for bottoming cycle 

technologies to be used in the future, however it is not clear today that this technology, 

although promising for more steady-state operation will provide any significant 

efficiency improvement under the more transient operating cycles typical of vocational 

vehicles. Moreover, as stated at II.D above, the agencies do not believe that this 

technology will be available in the time frame of this rule in any case.

 

292 Sample 2010 MY vocational vehicles range in price between $40,000 for a Class 4 work truck to 

approximately $200,000 for a Class 8 refuse hauler. See pages 16-17 of ICF’s “Investigation of Costs for 

Strategies to Reduce Greenhouse Gas Emissions for Heavy-Duty On-Road Vehicles.” July 2010.

293 See RIA Chapter 7, Table 7-4.

294 The light-duty rule had a cost per ton of $50 when considering the vehicle program costs only and a cost 

of -$210 per ton considering the vehicle program costs along with fuel savings in 2030. See 75 FR 25515, 

Table III.H.3-1. 
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IV. Final Regulatory Flexibility Provisions

This section describes flexibility provisions intended to advance the goals of the 

overall program while providing alternate pathways to achieve those goals, consistent 

with the agencies’ statutory authority, as well as with Executive Order 13563.295 The 

primary flexibility provisions for combination tractors and vocational vehicles and the 

engines installed in these vehicles are incorporated in a program of averaging, banking, 

and trading of credits. For HD pickups and vans, the primary flexibility provision is also 

an ABT program expressed in the fleet average form of the standards, along with 

provisions for credit and deficit carry-forward and for trading, patterned after the 

agencies’ light-duty vehicle GHG and CAFE programs. Furthermore, EPA will allow 

manufacturers to comply with the N2O and CH4 standards using CO2 credits and is 

providing an opportunity for engine manufacturers to earn N2O credits that can be used to 

comply with the CO2 standards. However, EPA is not adopting an emission credit 

program associated with the CH4 or HFC standards. This section also describes other 

flexibility provisions that apply, including advanced technology credits, innovative 

technology credits and early compliance credits.

A. Averaging, Banking, and Trading Program

Averaging, Banking, and Trading (ABT) of emissions credits have been an 

important part of many EPA mobile source programs under CAA Title II, including 

engine and vehicle programs. NHTSA has also long had an averaging and banking 

program for light-duty CAFE under EPCA, and recently gained authority to add a trading 

program for light-duty CAFE through EISA. ABT programs are useful because they can 

help to address many issues of technological feasibility and lead-time, as well as 

considerations of cost. They provide manufacturers flexibilities that assist the efficient

development and implementation of new technologies and therefore enable new 

technologies to be implemented at a more aggressive pace than without ABT. ABT 

programs are more than just add-on provisions included to help reduce costs, and can be, 

as in EPA’s Title II programs an integral part of the standard setting itself. A welldesigned ABT program can also provide important environmental and energy security 

benefits by increasing the speed at which new technologies can be implemented (which 

means that more benefits accrue over time than with slower-starting standards) and at the 

same time increase flexibility for, and reduce costs to, the regulated industry. American 

Council for an Energy-Efficient Economy (ACEEE) has commented that ABT and 

related flexibilities should not be offered for this program because the agencies are not 

promoting the use of new technologies but rather the use of existing technologies. 

However, without ABT provisions (and other related flexibilities), standards would 

typically have to be numerically less stringent since the numerical standard would have to 

be adjusted to accommodate issues of feasibility and available lead time. See 75 FR at 

 

295 Section 4 of EO 13563 states that “Where relevant, feasible, and consistent with regulatory 

objectives, and to the extent permitted by law, each agency shall identify and consider regulatory 

approaches that reduce burdens and maintain flexibility and freedom of choice for the public.” 76 FR 

3821 (Jan. 21, 2011).
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25412-13. By offering ABT credits and additional flexibilities the agencies can offer 

progressively more stringent standards that help meet our fuel consumption reduction and 

GHG emission goals at a faster pace.

Section II above describes EPA’s GHG emission standards and NHTSA’s fuel 

consumption standards. For each of these respective sets of standards, the agencies also 

offer ABT provisions, consistent with each agency’s statutory authority. The agencies 

worked closely to design these provisions to be essentially identical to each other in form 

and function. Because of this fundamental similarity, the remainder of this section refers 

to these provisions collectively as “the ABT program” except where agency-specific 

distinctions are required.

As discussed in detail below, the structure of the GHG and fuel consumption ABT 

program for HD engines was based closely on EPA’s earlier ABT programs for HD 

engines; the program for HD pickups and vans was built on the existing light-duty GHG 

program flexibility provisions; and the first-time ABT provisions for combination tractors 

and vocational vehicles are as consistent as possible with EPA’s other HD vehicle 

regulations. The flexibility provisions associated with this new regulatory category were

intended to build systematically upon the structure of the existing programs. 

As an overview, “averaging” means the exchange of emission or fuel 

consumption credits between engine families or truck families within a given 

manufacturer’s regulatory subcategories and averaging sets. For example, specific 

“engine families,” which manufacturers create by dividing their product lines into groups 

expected to have similar emission characteristics throughout their useful life, would be 

contained within an averaging set. Averaging allows a manufacturer to certify one or 

more engine families (or vehicle families, as appropriate) within the same averaging set 

at levels worse than the applicable emission or fuel consumption standard. The increased 

emissions or fuel consumption over the standard would need to be offset by one or more 

engine (or vehicle) families within that manufacturer’s averaging set that are certified 

better than the same emission or fuel consumption standard, such that the average 

emissions or fuel consumption from all the manufacturer’s engine families, weighted by 

engine power, regulatory useful life, and production volume, are at or below the level of 

the emission or fuel consumption standard 296 Total credits for each averaging set within 

each model year are determined by summing together the credits calculated for every

engine family within that specific averaging set. 

“Banking” means the retention of emission credits by the manufacturer for use in 

future model year averaging or trading. “Trading” means the exchange of emission 

credits between manufacturers, which can then be used for averaging purposes, banked 

for future use, or traded to another manufacturer. 

In EPA’s current HD engine program for criteria pollutants, manufacturers are 

restricted to averaging, banking and trading only credits generated by the engine families 

 

296 The inclusion of engine power, useful life, and production volume in the averaging calculations allows 

the emissions or fuel consumption credits or debits to be expressed in total emissions or consumption over 

the useful life of the credit-using or generating engine sales.
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within a regulatory subcategory, and EPA and NHTSA proposed to continue this 

restriction in the GHG and fuel consumption program for engines and vehicles. 

However, the agencies sought comment on potential alternative approaches in which 

fewer restrictions are placed on the use of credits for averaging, banking, and trading. 

Particularly, the agencies requested comment on removing prohibitions on averaging and 

trading between some or all regulatory categories in the proposal, and on removing 

restrictions between some or all regulatory subcategories that are within the same 

regulatory category (e.g., allowing trading of credits between Class 7 day cabs and Class 

8 sleeper cabs). 

The agencies received many comments on the restrictions proposed for the ABT 

program, namely on the proposal that credits could only be averaged within the specified 

vehicle and engine subcategories and not averaged across subcategories or between 

vehicle and engine categories. Many commenters, including Union of Concerned 

Scientist (UCS), NY Dept of Transportation, Natural Resources Defense Council, 

Oshkosh, and Autocar, requested that the agencies maintain the restrictions as proposed 

in the NPRM. UCS argued that allowing credits to be used across categories could 

undermine further technology advancements, and that manufacturers that have broad 

portfolios would have advantages over those manufacturers that do not. The Center for 

Biological Diversity (CBD) argued that because of the various credit opportunities in the 

ABT program and the potential that manufacturers will pay penalties rather than comply

with the standards, the program could actually cause an increase in emissions and a 

decrease in fuel efficiency. On the other hand, several commenters, including 

EMA/TMA, Cummins, Volvo, and ATA, requested that the agencies maintain the 

proposed restrictions of averaging credits between the engine and vehicle categories, but 

reduce the restrictions on credit averaging across vehicle subcategories or engine 

subcategories or averaging sets within similar vehicle and engine weight classes (LHD, 

MHD and HHD). Cummins requested that the agencies allow credit averaging between 

engine subcategories within the same weight classes (LHD, MHD and HHD). Cummins 

explained that tractor and vocational engines in the corresponding weight classes not only 

share the same useful life but also use the same emission and fuel consumption 

technologies and therefore should be placed into the same engine averaging set. 

EMA/TMA argued that the NPRM restrictions would inhibit a manufacturer’s ability to 

use credits to address market fluctuations, which would reduce the flexibility that the 

ABT program was intended to provide. As an example, EMA/TMA stated that if the 

line-haul market were depressed for a period of time a manufacturer could make up any

deficit selling more low-roof tractors with regional hauling operations. The same market 

shift could eliminate a manufacturer’s ability to generate credits using its aerodynamic 

high-roof sleeper cab tractors and could create a credit deficit if there is a demand for 

more of the less aerodynamic low-roof tractors. EMA/TMA argued that credit exchanges 

across vehicle categories within the same weight classes within the tractor subcategories 

and across vocational vehicle and tractor subcategories would allow a manufacturer more 

flexibility to deal with these types of market and customer demand situations. Finally, 

several commenters, including Ford, DTNA NADA, NTEA and Navistar, requested that 

the agencies reduce the proposed restrictions even further by allowing credit averaging 

between vehicle categories and engine categories. Navistar argued that more flexibility
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was necessary for manufacturers like itself to increase innovation at a reasonable cost, 

stating that that more restrictions would increase costs within a shorter time frame.

After considering these comments, the agencies continue to believe that the ABT 

program developed by the agencies increases and accelerates the technological feasibility

of the GHG and fuel consumption standards by providing manufacturers flexibility in 

implementing new technologies in a way that may be more consistent with their business 

practices and cost considerations. In response to the comments submitted by CBD, the 

agencies disagree with CBD’s statements that the ABT program will adversely affect the 

fuel efficiency and GHG emission goals of this regulation. This joint final action

requires vehicle and engine manufacturers to meet increasingly more stringent emission 

and fuel consumption standards which will result in emission reductions and fuel 

consumption savings. Manufacturers will not have the option of not meeting the 

standards. The ABT program simply provides each manufacture the flexibility to meet 

these standards based upon their individual products and implementation plans.

By assuming the use of credits for compliance, the agencies were able to set the 

fuel consumption/GHG standards at more stringent levels than would otherwise have 

been feasible. One reason is that use of ABT allows each manufacturer maximum 

flexibility to develop compliance strategies consistent with its redesign cycles and with 

its product plans generally, allowing the agencies, in turn, to adopt standards which are 

numerically more stringent in earlier model years than would be possible with a more 

rigid program since those rigidities would be associated with greater costs. Greater 

improvements in fuel efficiency will occur under more stringent standards; manufacturers 

will simply have greater flexibility to determine where and how to make those 

improvements than they would have without credit options. Further, this is consistent 

with the directive in EO 13563 to “seek to identify, as appropriate, means to achieve 

regulatory goals that are designed to promote innovation.” 

The agencies further agree that certain restrictions on use of ABT which were 

proposed are unnecessary. The proposed ABT program for engines was somewhat more 

restrictive, in its definition of averaging sets, than EPA’s parallel ABT program for 

criteria pollutant emissions from the same engines. The final rules conform to the ABT 

provisions for GHG heavy-duty engine emissions to be consistent with the parallel ABT 

provisions for criteria pollutants with same weight engines treated as a single averaging 

set regardless of the vehicles in which they are installed. We have applied this same 

principle with respect to combination tractors and vocational vehicles: treating like 

weight classes as an averaging set. The agencies have determined that these additional 

flexibilities will help to reduce manufacturing costs further and encourage technology

implementation without creating an unfair advantage for manufactures with vertically 

integrated portfolios including engines and vehicles. EPA’s experience in administering 

the ABT program for heavy-duty diesel engine criteria pollutant emissions supports this 

conclusion. Therefore, the agencies have decided to allow credit averaging within and 

across vocational vehicle and tractor subcategories within the same weight class groups, 

as well as credit averaging across the same weight class vocational and tractor engine 

groups. This added flexibility beyond what was proposed in the NPRM will not be 

extended to the HD pickup truck and van category because this group of vehicles is 
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comprised of only one subcategory and is not broken down like the other categories and 

corresponding subcategories into different weight classes, and the standard applies to the 

entire vehicle, so that there are no separate engine and vehicle standards. Put another 

way, the HD pickup truck and van category is one large averaging set that will remain as 

proposed. 

However, the agencies are maintaining the restrictions against averaging vehicle 

credits with engine credits or between vehicle weight classes or engine subcategories for 

this first phase of regulation. We believe averaging or trading credits between averaging 

sets would be problematic because of the diversity of applications involved. This 

diversity creates large differences in the real world conditions that impact lifetime 

emissions -- such as actual operating life, load cycles, and maintenance practices. In lieu 

of conducting extensive and burdensome real world tracking of these parameters, along 

with corrective measures to provide some assurance of parity between credits earned and 

credits redeemed, averaging sets provide a reasonable amount of confidence that typical 

engines or vehicles within each set have comparable enough real world experience to 

make such follow-up activity unnecessary. The agencies believe this approach will 

ensure that CO2 emissions are reduced and fuel consumption is improved in each engine 

subcategory without interfering with the ability of manufacturers to engage in free trade 

and competition. Again, EPA’s experience in administering its ABT program for criteria 

pollutant emissions from heavy-duty diesel engines confirms these views. The agencies 

also note that no commenter offered an explanation of why the restrictions on this ABT 

program should differ from the parallel ABT program respecting criteria pollutants. As 

explained earlier in this preamble, the agencies intend to re-evaluate the appropriateness 

of the ABT averaging sets and credit use restrictions we are adopting here for the HD 

GHG and fuel consumption program in the future based on information we gain 

implementing this first phase of regulation.

Under previous ABT programs for other rulemakings, EPA and NHTSA have 

allowed manufacturers to carry forward credit deficits for a set period of time – if a 

manufacturer cannot meet an applicable standard in a given model year, it may make up 

its shortfall by overcomplying in a subsequent year. In the NPRM the agencies proposed 

to allow manufacturers of engines, tractors, HD pickups and vans, and vocational 

vehicles to carry forward deficits for up to three years before reconciling the shortfall -

the same period allowed in numerous other EPA rules - but sought comments on 

alternative approaches for reconciling deficits. DTNA supported the three year period 

and stated that it was sufficient for reconciling deficits. CBD did not support the use of 

the carry forward of deficits because it would delay investments and technological 

innovation. The agencies respectfully disagree with CBD and believe this provision has 

enabled the agencies to consider overall standards that are more stringent and that will 

become effective sooner than we could consider with a more rigid program, one in which 

all of a manufacturer’s similar vehicles or engines would be required to achieve the same 

emissions or fuel consumption levels, and at the same time. Therefore the agencies 

included in the final rulemaking the proposed 3 year reconciliation period. However, the 

agencies’ respective credit programs require manufacturers to use credits to offset a 

shortfall before credits may be banked or traded for additional model years. This 
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restriction reduces the chance of manufacturers passing forward deficits before 

reconciling shortfalls and exhausting those credits before reconciling past deficits. 

For the heavy-duty pickup and van category, the agencies proposed a 5-year 

credit life provision, as adopted in the light-duty vehicle GHG /CAFE program. Navistar 

requested that the agencies drop the 5-year credit expiration date proposed for the heavyduty pickup and van category and not specify an expiration date for earned credits. 

Navistar stated that such credits are necessary to further improve the flexibilities of this 

program in order to meet the new stringent standards within the limited lead time 

provided. The agencies disagree. The 5-year credit life is substantial, and allows credits 

earned early in the phase-in to be held and used without discounting throughout the 

phase-in period. 

For engines, vocational vehicles and tractors, EPA also proposed that CO2 credits 

generated during this first phase of the HD National Program could not be used for later 

phases of standards, but NHTSA did not expressly specify the potential expiration of fuel 

consumption credits. DTNA and Cummins requested that the surplus credits from the 

first phase of the program not expire. DTNA suggested that the agencies drop any 

reference to credit expiration until the next rulemaking, at which time the agencies would 

have a better understanding of actual credit balances and what kind of lifespan for credits 

might be necessary or appropriate. DTNA argued that in some of EPA’s past programs, 

EPA had delayed a final decision about credit expiration until development of the 

subsequent rule when, EPA had a better understanding of associated credit balances, 

along with the stringency of the standards being proposed for future model years. EPA 

had proposed to limit the lifespan of credits earned to the first phase of standards in the 

interest of ensuring a level playing field before the next phase begins. Upon further 

consideration, the agencies recognize that this is a new program and it is unknown 

whether any manufacturers will have credit surpluses by the end of the first phase of 

standards, much less whether some manufacturers will have significantly larger credit 

surpluses that might create an unlevel playing field going into the next phase. The 

agencies are adopting a 5-year credit life provision for all regulatory categories, as 

adopted in the light-duty vehicle program and proposed for the HD pickup trucks and 

vans.

297

 

The following sections provide further discussions of the flexibilities provided in 

this action under the ABT program and the agencies’ rationale for providing them. 

(1) Heavy-duty Engines

For the heavy-duty engine ABT program, EPA and NHTSA proposed to use six 

averaging sets per 40 CFR 1036.740 for EPA and 49 CFR 535.7(d) for NHTSA, which 

aligned with the proposed regulatory engine subcategories. As described above, the 

agencies have decided that these engine averaging sets should be the same as for criteria 

pollutants under the EPA heavy-duty diesel engine rules, and agree with commenters that 

increasing the size of averaging sets from within subcategories to across subcategories 

 

297 Note, however, that manufacturers have no property right in these credits, so no issues of deprivation of 

property arise if later rules choose not to recognize those credits. See 69 FR at 39001-002 (June 29, 2004).
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within the same engine weight class would provide important additional flexibilities for 

engine manufacturers without negatively impacting fuel savings or emissions reductions. 

The agencies are therefore adopting four engine averaging sets rather than the proposed 

six. The four engine averaging sets are light heavy-duty (LHD) diesel, medium heavyduty (MHD) diesel, heavy heavy-duty (HHD) diesel, and gasoline or spark ignited 

engines without distinction for the type of vehicle in which the engine is installed. Thus, 

the final ABT program will allow for averaging, banking, and trading of credits between 

HHD diesel engines which are certified for use in vocational vehicles and HHD diesel 

engines which are certified for installation in tractors. Similarly, the MHD diesel engines 

certified for use in either vocational vehicles or tractors will be treated as a single

averaging set. As noted in Section I.G above, the agencies intend to monitor this 

program and consider possibilities of more widespread trading based on experience in 

implementing the program as the first engines and vehicles certified to the new standards 

are introduced. Credits generated by engine manufacturers under this ABT program are 

restricted for use only within their engine averaging set, based on performance against the 

standard as defined in Section II.B and II.D. Thus, LHD diesel engine manufacturers can 

only use their LHD diesel engine credits for averaging, banking and trading with LHD 

diesel engines, not with MHD diesel or HHD diesel engines. As noted, this limitation is 

consistent with ABT provisions in EPA’s existing criteria pollutant program for engines 

and will help avoid problems created by the diversity of applications that the broad 

spectrum of HD engines goes into, as discussed above. 

The compliance program for the final rules adopts the proposed method for 

generating a manufacturer’s CO2 emission and fuel consumption credit or deficit. The

manufacturer’s certification test results would serve as the basis for the generation of the 

manufacturer’s Family Certification Level (FCL). The agencies did not receive comment 

on this, and continue to believe that it is the best approach. The FCL is a new term we 

proposed for this program to differentiate the purpose of this credit generation technique 

from the Family Emission Limit (FEL) previously used in a similar context in other EPA 

rules. A manufacturer may define its FCL at any level at or above the certification test 

results. Credits for the ABT program are generated when the FCL is compared to its CO2

and fuel consumption standard, as discussed in Section II. Credit calculation for the 

Engine ABT program, either positive or negative, is based on Equation IV-1 and 

Equation IV-2:

Equation IV-1: Final HD Engine CO2 credit (deficit)

HD Engine CO2 credit (deficit) (metric tons) = (Std-FCL) x (CF) x (Volume) x (UL) x 

(10-6)

where:

Std = the standard associated with the specific engine regulatory subcategory

(g/bhp-hr)

FCL = Family Certification Level for the engine family
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CF = a transient cycle conversion factor in bhp-hr/mile which is the integrated 

total cycle brake horsepower-hour divided by the equivalent mileage of the Heavy-duty 

FTP cycle. For gasoline heavy-duty engines, the equivalent mileage is 6.3 miles. For 

diesel heavy-duty engines, the equivalent mileage is 6.5 miles. The CF determined by 

the Heavy-duty FTP cycle is used for engines certifying to the SET standard.

Volume = (projected or actual) production volume of the engine family

UL = useful life of the engine (miles)

10-6converts the grams of CO2 to metric tons

Equation IV-2: Final HD Engine Fuel Consumption credit (deficit) in gallons 

HD Engine Fuel Consumption credit (deficit) (gallons) = (Std – FCL) x (CF) x (Volume) 

x (UL) x 102

where:

Std = the standard associated with the specific engine regulatory subcategory

(gallon/100 bhp-hr)

FCL = Family Certification Level for the engine family (gallon/100 bhp-hr)

CF = a transient cycle conversion factor in bhp-hr/mile which is the integrated 

total cycle brake horsepower-hour divided by the equivalent mileage of the Heavy-duty 

FTP cycle. For gasoline heavy-duty engines, the equivalent mileage is 6.3 miles. For 

diesel heavy-duty engines, the equivalent mileage is 6.5 miles. The CF determined by 

the Heavy-duty FTP cycle is used for engines certifying to the SET standard.

Volume = (projected or actual) production volume of the engine family

UL = useful life of the engine (miles)

102= conversion to gallons

To calculate credits or deficits, manufacturers will determine an FCL for each 

engine family they have designated for the ABT program. The agencies have defined 

engine families in 40 CFR 1036.230 and 49 CFR 535.4 and manufacturers may designate 

how to group their engines for certification and compliance purposes. The FCL may be 

above or below its respective subcategory standard and is used to establish the CO2

credits earned in Equation IV-1 or the fuel consumption credits earned in Equation IV-2. 

The final CO2 and fuel consumption standards are associated with specific regulatory

subcategories as described in Sections II.B and II.D (gasoline, light heavy-duty diesel, 

medium heavy-duty diesel, and heavy heavy-duty diesel). In the ABT program, engines 

certified with an FCL below the standard generate positive credits and an FCL above the 

standard generates negative credits. As discussed in Section II.B and II.D, engine 

averaging sets that include engine families for which a manufacture elects to use the 

alternative standard of a percent reduction from the engine family’s 2011 MY baseline 
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are ineligible to either generate or use credits. Credit deficits accumulated in an 

averaging set where engine families have used the alternate standard can carry that deficit 

forward for three years following the model year for which that deficit was generated at 

which time the deficit must be reconciled with surplus credits. 

The volume used in Equations IV-1 and IV-2 refers to the total number of eligible

engines sold per family participating in the ABT program during that model year. The 

useful life values in Equation IV-1 and IV-2 are the same as the regulatory classifications 

previously used for the engine subcategories. Thus, for LHD diesel engines and gasoline 

engines, the useful life values are 110,000 miles; for MHD diesel engines, 185,000 miles; 

and for HHD diesel engines, 435,000 miles. 

As described in Section II.E above, for purposes of EPA’s standards, an engine 

manufacturer may choose to comply with the N2O or CH4 cap standards using CO2

credits. 298 A manufacturer choosing this option would convert its N2O or CH4 test 

results into CO2eq to determine the amount of CO2 credits required. This approach 

recognizes the correlation of these elements in impacting global climate change. To 

account for the different global warming potential of these GHGs, manufacturers will 

determine the amount of CO2 credits required by multiplying the shortfall by the GWP. 

For example, a manufacturer would use 25 kg of positive CO2 credits to offset 1 kg of 

negative CH4 credits. Or a manufacturer would use 298 kg of positive CO2 credits to 

offset 1 kg of negative N2O credits. In general the agencies do not expect manufacturers 

to use this provision, but are providing it as an alternative in the event an engine 

manufacturer has trouble meeting the CH4 and/or N2O emission caps. There are no ABT 

credits for performance that falls below the CH4 cap. As described below, EPA is 

adopting a provision applicable in MYs 2014 through 2016 to allow the creation of CO2

credits by demonstrating N2O below the current average baseline performance, a value 

that is well below the final N2O cap standard.

Manufacturers of engines that generate a credit deficit at the end of the model 

year for any of its averaging sets can carry that deficit forward for three years following 

the model year for which that deficit was generated at which time the deficit must be 

reconciled with surplus credits. Manufacturers must use credits once those credits have 

been generated to offset a shortfall before those credits can be banked or traded for 

additional model years. This restriction reduces the chance of an engine manufacturer 

passing forward deficits before reconciling their shortfalls and exhausting those credits 

before reconciling past deficits. Deficits will need to be reconciled at the reporting dates 

for model year three. Surplus credits earned in the engine categories will expire after five 

model years. As noted above, the agencies may reconsider 5 year credit life during the 

next phase of rulemaking. 

Under the EPA and NHTSA programs, engine manufacturers are provided 

flexibilities in complying with compression ignition (CI) engine standards. These 

flexibilities are provided in order to: 1) synchronize the implementation schedules for the 

 

298 This option does not apply to the NHTSA fuel consumption program, since NHTSA is not regulating 

N2O or CH4 emissions, since they are irrelevant to fuel consumption reductions. 
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upcoming EPA OBD regulatory changes with the GHG and fuel consumption regulatory

requirements; 2) aid manufacturers that produce legacy engines in the early years of the 

HD program; and 3) provide an opportunity for manufacturers to earn early credits as 

mentioned in sections II.B.(2)(b), II.D.(1)(b)(i) and IV.B.(1) of this document. The 

flexibilities provide manufacturers of CI engines with four different and distinct paths 

that can be followed to meet the EPA and NHTSA emission and fuel consumption 

standards. Manufacturers do not have these flexibility mechanisms for gasoline engines, 

since the standards for gasoline engines go into effect after the flexibility mechanisms 

have expired. As a general guideline applicable for each of these four compliance paths, 

if a manufacturer chooses to opt into the NHTSA program prior to MY 2017, which is 

the year the NHTSA compression ignition engine standards become mandatory, the path 

chosen must be the same path chosen to meet the EPA emission standards. Each of the 

four paths is discussed below.

The first path is for a manufacturer to meet the regular or “primary” standards that 

become mandatory in MY 2014 under the EPA regulations. These standards are 

voluntary in 2014, 2015, and 2016 under the NHTSA program, and become mandatory in 

2017 in the NHTSA program. The primary path standards become more stringent in 

model year 2017 in both the EPA and NHTSA regulations. For the NHTSA program, an 

engine manufacturer may choose to voluntarily opt into the program early, in any of the 

MYs 2014, 2015 or 2016 allowing that manufacturer to earn credits for those model 

years. In the NHTSA program however, once the manufacturer has made the decision to 

opt into the program early it must remain in the program during the subsequent model 

years. 

Path two allows manufacturers to earn early credits as part of the “primary” MY 

2014 emission standard path. Early credits can be earned in MY 2013, as discussed in 

section IV.B.(1). Under the NHTSA fuel consumption program, an engine manufacturer 

may also choose to opt into the primary standards program beginning in MY 2013 to 

obtain early credits, but once the decision has been made to opt into the program in MY 

2013 the manufacturer must remain in the program in the subsequent model years. If a 

manufacturer chooses to opt into the NHTSA program prior to the mandatory 2017 

model year it must follow that same path chosen to meet the EPA emission standards.

If a manufacturer produces “legacy” engines, which typically have 2011 baseline 

emissions that are significantly higher than the 2010 baseline for this regulation, the 

manufacturer may choose path three. This path allows a manufacturer to meet alternate 

CI engine standards in MYs 2014 through 2016 for specific engine families. More 

details about this path are provided in section II.B.(2)(b) and II.D.(1)(b)(i). This path can 

only be taken if all other credit opportunities have been exhausted and the manufacturer 

still cannot meet the primary standards under the first path. Again, if a manufacturer 

chooses this path to meet the EPA emission standards in MY 2014 – 2016, and wants to 

opt into the NHTSA fuel consumption program in these same MYs it must follow the 

exact path followed under the EPA program. 

The fourth path that a CI engine manufacturer can take is referred to as the 

alternative “OBD phase-in” path. Manufacturers that wish to “bundle” or combine 
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design changes needed for the 2013 and 2016 heavy-duty OBD requirements with design 

changes needed for the GHG and fuel consumption requirements may choose this path. 

The EPA standards in this path become mandatory in MY 2013 instead of 2014. In 

addition, in this path emission and fuel consumption standards increase in stringency in 

2016 rather than in 2017. While the OBD phase-in schedule requires engines built in 

MYs 2013 and 2016 to achieve greater reductions than those engines built in the model 

years under the primary program (path one above), it requires lower reductions for 

engines built in 2014 and 2015. Under the NHTSA program, an engine manufacturer 

may choose to opt into the “OBD phase-in” path only if this is the same path chosen 

under the EPA program and only if the manufacturer is opting into the program in MY 

2013 and staying in the program through MY 2016. If a manufacturer chooses the OBD 

phase-in path to meet the EPA emission standards and decides to opt into the NHTSA 

program prior to the mandatory MY 2017 requirement, the manufacturer must follow the 

same path under both the EPA and NHTSA programs. Under this path the early credit 

MY 2013 flexibility as discussed in path two above is not available. While it does not 

involve credits, the agencies consider the alternative “OBD phase-in” path to be an 

additional flexibility. 

 Additional flexibilities for engines, discussed later in Section IV.B, provide 

manufacturers the opportunity to generate early, advanced and innovative technology

credits. 

(2) Heavy-Duty Vocational Vehicles and Tractors

In addition to the engine ABT program described above, the agencies also 

proposed a heavy-duty vehicle ABT program to facilitate reductions in GHG emissions 

and fuel consumption based on heavy-duty vocational vehicle and tractor design changes 

and improvements. EPA and NHTSA had proposed averaging sets which aligned with 

the proposed twelve regulatory subcategories; however in response to the comments 

described, which requested that averaging sets be expanded across subcategories within 

similar weight classes, (analogous to the principle on which ABT is structured under 

EPA’s heavy-duty diesel engine program for criteria pollutants), the agencies are 

finalizing only three averaging sets – LHD, MHD, and HHD based upon the three weight 

classes. In other words, all HHD (Class 8) tractors, HHD vocational tractors, and HHD 

vocational vehicles will be treated as a single averaging set. Similarly, all MHD (Class 

7) tractors, MHD vocational tractors, and MHD (Class 6-7) vocational vehicles will be 

treated as a single averaging set, and LHD vocational vehicles (Class 2b-5) will be 

treated as a single averaging set. For this category, the structure of the final ABT 

program should create incentives for vehicle manufacturers to advance new, clean 

technologies, or existing technologies earlier than they otherwise would. ABT provides 

manufacturers the flexibility to deal with unforeseen shifts in the marketplace that affect 

sales volumes. At the same time, restricting trading to within these segments gives the 

agencies confidence that the reductions are truly offsetting given the similarity in 

products engaged in trading. This structure also allows for a straightforward compliance 

program for each sector, with aspects that are independently quantifiable and verifiable.
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Credit calculation for the final HD Vocational Vehicle and Tractor CO2 and fuel 

consumption credits, either positive or negative, will be generated according to Equation 

IV-3 and Equation IV-4:

Equation IV-3: The Final HD Vocational Vehicle and Tractor CO2 Credit (Deficit)

HD Vocational Vehicle and Tractor CO2 credit (deficit)(metric tons) = (Std-FEL) x 

(Payload Tons) x (Volume) x (UL) x (10-6)

where:

Std = the standard associated with the specific regulatory subcategory (g/ton-mile)

Payload tons = the prescribed payload for each class in tons (12.5 tons for Class 7 

tractors, 19 tons for Class 8 tractors, 2.85 tons for LHD vocational, 5.6 tons for MHD 

vocational, and 7.5 tons for HHD vocational vehicles)

FEL = Family Emission Limit for the vehicle family which is equal to the output 

from GEM (g/ton-mile)

Volume = (projected or actual) production volume of the vehicle family

UL = useful life of the vehicle (435,000 miles for HHD, 185,000 miles for MHD, 

and 110,000 miles for LHD)

10-6converts the grams of CO2 to metric tons

Equation IV-4:Final HD Vocational Vehicle and Tractor Fuel Consumption credit (deficit) in 

gallons: 

HD Vocational Vehicle and Tractor Fuel Consumption credit (deficit)(gallons) = (StdFEL) x (Payload Tons) x (Volume) x (UL) x 103

where:

Std = the standard associated with the specific regulatory subcategory

(gallons/1,000 ton-mile)

Payload tons = the prescribed payload for each class in tons (12.5 tons for Class 7 

tractors, 19 tons for Class 8 tractors, 2.85 tons for LHD vocational, 5.6 tons for MHD 

vocational, and 7.5 tons for HHD vocational vehicles)

FEL = Family Emission Limit for the vehicle family (gallons/1,000 ton-mile)

Volume = (projected or actual) production volume of the vehicle family

UL = useful life of the vehicle (435,000 miles for HHD, 185,000 miles for MHD, 

and 110,000 miles for LHD)

103= conversion to gallons
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Manufacturers of vocational vehicles and tractors that generate a credit deficit at 

the end of the model year for any of its averaging sets can carry that deficit forward for 

three years following the model year for which that deficit was generated at which time 

the deficit must be reconciled with surplus credits. Manufacturers must use credits once 

those credits have been generated to offset a shortfall before those credits can be banked 

or traded for additional model years. This restriction reduces the chance of a vehicle 

manufacturer passing forward deficits before reconciling their shortfalls and exhausting 

those credits before reconciling past deficits. Deficits will need to be reconciled at the 

reporting dates for model year three. Surplus credits earned in the vehicle categories will 

have a five year expiration date. The agencies may reconsider the 5 year credit life 

during the next phase of the rulemaking. 

Additional flexibilities for HD vocational vehicles and tractors, discussed later in 

Section IV.B, provide manufacturers the opportunity to generate early, advanced, and 

innovative technology credits.

(3) Heavy-Duty Pickup Truck and Van Flexibility Provisions

The NPRM included specific flexibility provisions for manufacturers of HD 

pickups and vans, similar to provisions adopted in the recent rulemaking for light-duty

car and truck GHGs and fuel economy. The agencies are finalizing the flexibilities as 

proposed. In the heavy-duty pickup and van category a manufacturer’s credit or debit 

balance will be determined by calculating their fleet average performance and comparing 

it to the manufacturer’s CO2 and fuel consumption standards, as determined by their fleet 

mix, for a given model year. A target standard is determined for each vehicle. These 

targets, weighted by their associated production volumes, are summed at the end of the 

model year to derive the production volume-weighted manufacturer annual fleet average 

standard. A manufacturer will generate credits if its fleet average CO2 or fuel 

consumption level is lower than its standard and will generate debits if its fleet average 

CO2 or fuel consumption level is above that standard. To receive the benefit of the 

advanced technology provisions, if the manufacturer’s fleet includes conventional and 

advanced technology vehicles, the manufacturer will divide this fleet of vehicles into two 

separate fleets for calculation of fleet average credits. The end-of-year reports will 

provide the appropriate data to reconcile pre-compliance estimates with final model year 

figures (see 40 CFR Part 1037.730 and 49 CFR Part 535.8). 

The EPA credit calculation is expressed in metric tons and considers production 

volumes, the fleet standards and performance, and a factor for the vehicle useful life, as 

in the light-duty GHG program. The NHTSA credit calculation uses the fleet standard 

and performance levels in fuel consumption units (gallons per 100 miles), as opposed to 

fuel economy units (mpg) as done in the light-duty program, along with the vehicle 

useful life, in miles, allowing the expression of credits in gallons. The total model year 

fleet credit (debit) calculations will use the following equations:

CO2 Credits (Mg) = [(CO2 Std – CO2 Act) × Volume × UL] ÷ 1,000,000

Fuel Consumption Credits (gallons) = (FC Std – FC Act) × Volume × UL × 100 
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Where: 

CO2 Std = Fleet average CO2 standard (g/mi) 

FC Std = Fleet average fuel consumption standard (gal/100 mile) 

CO2 Act = Fleet average actual CO2 value (g/mi) 

FC Act = Fleet average actual fuel consumption value (gal/100 mile) 

Volume = the total production of vehicles in the regulatory category

UL = the useful life for the regulatory category (miles)

As described above, HD pickup and van manufacturers will be able to carry

forward deficits from their fleet-wide average for three years before reconciling the 

shortfall. Manufacturers will be required to provide a plan in their pre-model year reports 

showing how they will resolve projected credit deficits. However, just as in the engine 

category, manufacturers will need to use credits earned once those credits have been 

generated to offset a shortfall before those credits can be banked or traded for additional 

model years. This restriction reduces the chance of vehicle manufacturers passing 

forward deficits before reconciling their shortfalls and exhausting those credits before 

reconciling past deficits. Deficits will need to be reconciled at the reporting dates for 

model year three. Surplus credits earned in the HD pickup and van categories (like 

surplus credits for all the other subcategories) will have a five year expiration date. The 

agencies may reconsider the 5 year credit life during the next phase of the rulemaking.

Additional flexibilities for heavy-duty pickup and van category are discussed 

below in Section IV.B which provides manufacturers the opportunity to generate early, 

advanced and innovative technology credits.

B. Additional Flexibility Provisions

The agencies proposed additional provisions to facilitate reductions in GHG 

emissions and fuel consumption beginning in the 2014 model year. While EPA and 

NHTSA believed the ABT and flexibility structure would be sufficient to encourage 

reduction efforts by heavy-duty highway engine and vehicle manufacturers, the agencies 

understood that other efforts could create additional opportunities for manufacturers to 

reduce their GHG emissions and fuel consumption. These provisions would provide 

additional incentives for manufacturers to innovate and to develop new strategies and 

cleaner technologies. The agencies requested comment on these provisions, as described 

below.

(1) Early Credit Option

The agencies proposed that manufacturers of HD engines, HD pickup trucks and 

vans, combination tractors, and vocational vehicles be eligible to generate early credits if 

they demonstrate improvements in excess of the standards prior to the model year the 
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standards become effective. As an example, if a manufacturer’s MY 2013 subcategory of 

tractors exceeds the EPA mandatory MY 2014 standard for those same vehicles, then 

that manufacturer could claim MY 2013 credits or “early credits” to utilize in its ABT 

program starting in the MY 2014. As noted in the NPRM, the start dates for EPA’s GHG 

standards and NHTSA’s fuel consumption standards vary by regulatory category (see 

Section II for the model years when the standards become effective), meaning that the 

early credits provision, if selected by a manufacturer, could begin during different model 

years. The NPRM stated that manufacturers would need to certify their engines or 

vehicles to the standards at least six months before the start of the first model year of the 

mandatory standards and that limitations on the use of credits in the ABT programs – i.e., 

limiting averaging to within each vehicle or engine averaging set – would apply for the 

early credits as well. In the NPRM, NHTSA and EPA requested comment on whether a 

credit multiplier, specifically a multiplier of 1.5, would be appropriate to apply to early

credits from HD engines, combination tractors, and vocational vehicles (but not to early

credits from HD pickups and vans), as a greater incentive for early compliance. See 75 

FR at 74255. 

The agencies received comments from Cummins, DTNA, EMA/TMA, Navistar, 

Eaton, Bosch, CBD and CALSTART relating to these early credit provisions. All of these 

commenters supported the early credit provision for the most part, but many requested 

that the agencies eliminate some of the restrictions relating to this provision. EMA/TMA

argued that MY 2012 should also be considered for early credits and that the requirement 

to certify six months before the start of the first model year would unnecessarily restrict 

manufacturers from earning credits for technology introduced within six months of the 

respective model year. In addition, EMA/TMA stated that requiring certification of the 

entire averaging set instead of individual vehicle configurations would not allow for early 

introduction of new technologies. Cummins stated that the six month lead time 

requirement should be removed and that manufacturers be allowed to earn early credits 

for individual engine families rather than only for the entire averaging set, stating that 

removal of these restrictions would further benefit the environment. CBD stated that 

early credits should only be granted if the emission and fuel consumption benefits are in 

addition to or above the existing performance levels and are quantifiable and verifiable. 

EPA and NHTSA have reviewed these comments and decided to clarify the 

proposed early credit provisions to account for the above concerns. Early credits are 

intended to be an incentive to manufacturers to introduce more efficient engines and 

vehicles earlier than they otherwise would be. However, the agencies do not want to 

provide a windfall of credits to manufacturers that may already have one or more 

products that meet the standards. Therefore, the final rules include the option for a 

manufacturer to obtain early credits for products if they certify their entire subcategory at 

GHG emissions and fuel consumption levels below the standards. See 75 FR at 74255. 

Thus, for example, early credits could be generated for all HHD engines installed in 

combination tractors. The agencies are making a clarification in this action that the 

manufacturers must certify their entire subcategory, not necessarily their entire averaging 

set, because the averaging sets are broadened under the final rulemaking from the 

categories proposed in the NPRM. In addition, the agencies are providing the flexibility

for combination tractor manufacturers to obtain early credits for their additional sales, as 
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compared to their 2012 model year sales, of SmartWay designated combination tractors 

(which includes high roof sleeper cabs only) in 2013 model year. The agencies view this 

subcategory of vehicles as the only segment of vehicles or engines where the true 

additional reductions due to the early credits can be quantified outside of certifying an 

entire subcategory, because the benefit is tied directly to the increase in the SmartWay

vehicles manufactured in MY 2013 in excess of those manufactured in MY 2012.

A manufacturer may opt to apply for early credits from their 2013 model year 

SmartWay designated combination tractor sales by first calculating the difference 

between the number of SmartWay designated combination tractors sold in 2012 MY

versus 2013 model year. The increment in sales determines the number of 2013 model 

year SmartWay designated tractors which can be used to certify for early credits, at the 

manufacturer’s choice of which vehicles to consider. The manufacturer would then 

determine each tractor configuration’s performance by modeling in GEM, using each 

vehicle configuration’s appropriate inputs for coefficient of drag, tire rolling resistance, 

idle reduction, weight reduction, and vehicle speed limiter. Next, the difference between 

a specific tractor configuration’s performance and the 2014 MY standard for the 

appropriate regulatory subcategory (e.g., Class 8 sleeper cab high roof tractors) would be 

calculated. The CO2 and fuel consumption credits are calculated using Equation IV-4

and IV-5. 

As discussed above and in Section II, manufacturers may opt into the NHTSA 

voluntary program prior to when the program becomes mandatory. Manufacturers that 

opt in become subject to NHTSA standards for all regulatory categories. This provides 

manufacturers the option of complying with NHTSA fuel consumption standards 

equivalent to the EPA emission standards in order to accumulate credits in the ABT 

program. If a manufacturer opts into the EPA early credit program, it may also opt into 

an equivalent NHTSA early credit program. In this case, the manufacturer must enter the 

program concurrently with the EPA program and will be subject to the full MY 2014-

2015/2016 NHTSA voluntary program. NHTSA would like to clarify that for the early 

credit provision, implementation must occur in MY 2013 exactly as implemented under 

the EPA emission program, and not in the model year immediately before the NHTSA 

standards become mandatory (since otherwise manufacturers would generate credits 

under the fuel consumption program as a result of complying with mandatory GHG 

standards – a windfall). Further, once a manufacturer opts into the NHTSA program it 

must stay in the program for all the optional MYs and remain standardized with the 

implementation approach being used to meet the EPA emission program. EPA and 

NHTSA intend for manufacturers’ ABT credit balances to remain equivalent wherever 

possible.

The agencies also received comments from EMA/TMA and Cummins opposing 

the requirement to certify six months prior to the first model year of the mandatory

standards for early credits. The commenters argued and the agencies agree that this 

restriction could cause some delays in technology rollout and are therefore not adopting 

this provision. The agencies reviewed the restriction and evaluated the light-duty 2012-

2016 MY vehicle early credit program. No such restriction exists for LD vehicles. We 

therefore believe that this requirement is not necessary for our implementation of the 
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program. In addition, we are adopting a provision which allows manufacturers to 

generate early credits for certifying less than a full model year early.

Several commenters, including DTNA, Edison Electric Institute, Eaton, and 

Bosch, supported using a 1.5 multiplier for early credits, stating that it would encourage 

early introduction of technology. Cummins and UCS opposed the multiplier stating that 

the opportunity to earn credits at their normal value should be sufficient incentive for 

early compliance. The agencies believe that this incentive will further encourage faster 

implementation of emission and fuel savings technology and help to reduce the costs 

manufacturers will incur in efforts to comply with these rules. The agencies have 

therefore decided to finalize a 1.5 multiplier for early credits earned in MY 2013.299 

However, the agencies note that manufacturers may not apply an additional 1.5 multiplier 

for advanced technology credits which are also certified as early credits.

With respect to heavy-duty pickups and vans, the agencies proposed that early

credits could be generated on a fleetwide basis by comparison of the manufacturer’s 2013 

heavy-duty pickup and van fleet with the manufacturer’s fleetwide targets, using the 

target standards equations for the 2014 model year. 75 FR at 74255. The agencies are 

finalizing these provisions as proposed. Under the structure for the fleet average 

standards, this credit opportunity entails certifying a manufacturer’s entire HD pickup 

and van fleet in model year 2013. Industry commenters argued that early credits should 

be calculated against a target curve that is less stringent than the 2014 curve. We 

disagree. Because it is the first year of a 5-year phase-in, the 2014 model year has quite 

modest emissions and fuel consumption reductions targets of only 15 percent of the 2018 

model year standards stringency. Targeting even less significant improvements over the 

baseline would unduly increase the prospect for windfall credits by individual 

manufacturers who may have better than average baseline fleets. On the other hand, we 

are confident that the early credit program, based as it is on full fleet compliance with the 

MY 2014 targets, will not result in windfall credits as it represents, in effect, a complete 

bringing forward of the program start date by one model year for manufacturers who 

choose to pursue it. Again, the agencies consider the availability of early credits to be a 

valuable complement to the overall program to the extent that they encourage early 

implementation of effective technologies.

(2) Advanced Technology Credits

The NPRM proposed targeted provisions that were expected to promote the 

implementation of advanced technologies. Specifically, manufacturers that incorporate 

these technologies would be eligible for special credits that could be applied to other 

heavy-duty vehicles or engines, including those in other heavy-duty categories. The 

credits are thus ‘special’ in that they can be applied across the entire heavy-duty sector, 

 

299 There is no multiplier for the early credit provisions in the light-duty vehicle rule. However, the 

situation there was more complicated, since early credits needed to be correlated with credit opportunities 

under the California GHG program for light-duty vehicle, and also needed to be integrated with statutory 

credits under EPCA/EISA for flexible fuel vehicles. See 75 FR at 25440-443. Thus, the light-duty vehicle 

rule early credit provisions are not analogous to those adopted in this rule for the heavy duty sector.
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unlike the ABT and early credits discussed above and the innovative technology credits 

discussed in the following subsection. The eligible technologies were: 

 Hybrid powertrain designs that include energy storage systems

 Rankine cycle engines300

 All-electric vehicles

 Fuel cell vehicles 

NHTSA and EPA requested comment on the list of technologies identified as 

advanced technologies and whether additional technologies should be added to the list. 

In addition to the increased fungibility of advanced technology credits, NHTSA and EPA 

requested comment on whether a credit multiplier, specifically a multiplier of 1.5, would 

be appropriate to apply to advanced technology credits, as a greater incentive for the 

technologies’ introduction. See 75 FR at 74255.

MEMA asked that the agencies expand the list of technologies that are eligible for 

Advanced Technology Credits to include advanced transmission and drivetrain 

technologies, tire and wheel accessories, and advanced engine accessories technologies 

(such as electronic air control systems and clutched turbocharged air compressor).

Bendix requested that weight reduction approaches, improved transmission and 

drivetrains, driver management and coaching, and tire and wheel improvements be 

allowed to receive credit through the Advanced Technology Credit Program.

The advanced technology credit program is intended to encourage development of 

technologies that are not yet commercially available. In order to provide incentives for 

the research and development needed to introduce these technologies, Advanced 

Technology Credits can be applied to any heavy-duty vehicle or engine and are not 

limited to the vehicle or engine categories generating the credit. Because of this 

flexibility in the application of these credits, it is important that the list of eligible 

technologies only include technologies that are not yet available in the market. In

addition, the technologies must lend themselves to straight forward methodologies for 

quantifying emissions and fuel consumption reductions. For some of the technologies 

that MEMA and Bendix asked be included in the program, such as electrified accessories 

and improved tires, the agencies have already established a mechanism for quantifying 

reductions associated with these approaches. For example, the agencies assumed in the 

regulatory impact analysis that some electrified accessories will be used to comply with 

the regulations. Specifically, improved water and oil pumps are assumed to be used for 

2014 LHD, MHD, and HHD FTP and SET diesel engines to comply with standards and if 

used, their performance would be assessed in the engine certification process. (See RIA 

Chapter 2.4). Any reductions in engine load and resulting emissions and fuel 

consumption resulting from accessory electrification thus will be accounted for in engine 

 

300 Although as noted in Section III above and in Chapter 2 of the RIA, this technology is still under 

development and so is not presently available.
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dynamometer testing. However, other electrified accessories, such as air conditioning do 

not impact engine operation over the FTP and SET cycles. As such, we are allowing 

credit for tailpipe AC emissions (as opposed to AC leakage) to be established through the 

Innovative Technology Credit Program described in section IV. B (3) below. With 

regard to tire rolling resistance improvements, light weight wheels, and weight reduction 

associated with the use of super single tires, these are already part of the technology basis 

for the standard for combination tractors and are accounted for in the GEM, and are also 

part of the technology basis for the standards for heavy-duty pickups and vans (See RIA 

Chapter 2.3). Some improved transmissions – such as automatic manuals - have been 

available commercially for ten years and as such, does not meet the criteria to be included 

on the list of advanced technologies. However, as described in Section IV.B. (3), 

advanced transmissions and drivetrains could be eligible for credits in the Innovative 

Technology Credit Program, and the agencies acknowledge the importance of including 

advanced transmissions and drivetrains in the program. With regard to weight reduction, 

the agencies are allowing additional weight reduction approaches to be used for tractors 

through modeling using GEM and through the innovative technology program. And 

finally, for driver management and coaching – while we recognize that there could be 

significant benefits to this, the difficulty in establishing a baseline condition for driver 

behavior limits the agencies’ ability to establish a reduction for this approach at this time.

The agencies have decided not to change the proposed list of technologies 

evaluated as advanced technologies, but are providing additional clarity in the advanced 

technology list. The agencies proposed that Rankine cycle engines be included, but the 

agencies are adopting the wording of Rankine cycle waste heat recovery system attached 

to an engine. 

The agencies received comments from Bendix, Bosch, MEMA, Navistar, Odyne, 

Green Truck Association, Eaton, ArvinMeritor and Calstart, which supported the 1.5 

multiplier for advanced technology credits. MEMA argued that these added flexibilities 

are absolutely necessary to help advanced technologies penetrate the marketplace and are 

the primary impetus to integrate these technologies onto vehicles. The agencies also 

received comments from several stakeholders, including ACEEE and Cummins opposing 

the 1.5 multiplier for advanced technology credits. ACEEE argued that multipliers should 

be avoided because they lessen the total emission reductions by allowing a greater 

increase in the emissions of other vehicles than they offset. After reviewing these 

comments, the agencies have determined that the relatively low volumes expected in this 

time frame are likely to mitigate any potential dilution of environmental benefits and be 

outweighed by the benefits of introduction of advanced technology into the heavy-duty

sector. Further, the credit multiplier will provide enough added benefit to the nascent 

heavy-duty hybrid community to help reduce barriers to market entry for new 

technologies. Therefore, the final rules include a multiplier of 1.5 for advanced 

technology credits. However, the agencies are also capping the amount of advanced 

credits that can be brought into any averaging set into any model year at 60,000 Mg to 

prevent market distortions. 
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(a) HD Pickup Truck and Van Hybrids and all Electric Vehicles

For HD pickup and van hybrids, the agencies proposed that testing would be done 

using adjustments to the test procedures developed for light-duty hybrids. See 75 FR at 

74255. NHTSA and EPA also proposed that all-electric and other zero tailpipe emission 

vehicles produced in model years before 2014 be able to earn credits for use in the 2014 

and later HD pickup and van compliance program, provided the vehicles are covered by 

an EPA certificate of conformity for criteria pollutants. These credits would be 

calculated based on the 2014 diesel standard targets corresponding to the vehicle’s work 

factor, and treated as though they were earned in 2014 for purposes of credit life. 

Manufacturers would not have to early-certify their entire HD pickup and van fleet in a 

model year as for other early-complying vehicles. 

NHTSA and EPA also proposed that model year 2014 and later EVs and other 

zero tailpipe emission vehicles be factored into the fleet average GHG and fuel 

consumption calculations based on the diesel standards targets for their model year and 

work factor. A manufacturer also has the option to subtract these vehicles out of its fleet 

and determine their performance as advanced technology credits that can be used for all 

other HD vehicle categories, but these credits would, of course, not then be reflected in 

the manufacturer’s pickup and van category credit balance. Commenters generally 

supported the introduction of hybrid and zero tailpipe emission vehicles, but did not 

comment on the specific provisions discussed above. The agencies also proposed in 

determining advanced technology credits for electric and zero emission vehicles that in 

the credits equation the actual emissions and fuel consumption performance be set to zero 

(i.e. that emissions be considered on a tailpipe basis exclusively). We are finalizing these 

provisions as proposed.

The proposal also solicited comment on the accounting of upstream GHG 

emissions. Some commenters argued that EPA should maintain its traditional focus in 

mobile source rulemakings on vehicle tailpipe emissions and leave the consideration of 

GHG emissions from upstream fuel production and distribution-related sources such as 

refineries and power plants to EPA regulatory programs which could focus specifically 

on those sources. Others argued that, since EPA accounts for upstream GHG emissions 

in its benefits assessments, the agency should reflect upstream GHG emissions impacts in 

vehicle compliance values as well. After considering these comments, the agencies have 

decided to base the credit accounting on tailpipe emissions only. The agencies believe 

that introduction of EV technology into the heavy-duty pickup and van sector in these 

model years will be limited and that incentives are important to encourage such 

introduction. Similarly, the agencies believe that use of EV technology for these vehicles 

in these model years will be infrequent so that there is no need to adopt a cap whereby 

upstream emissions would be counted after a certain volume of sales. See 75 FR at 

25434-438 (adopting such a cap for light-duty vehicles under the 2012-2016 MY GHG 

standards). We also recognize that the ongoing EPA/NHTSA rulemaking to reduce 

GHGs and fuel consumption in MY 2017 and later light-duty vehicles is examining this 

issue, and may yield information and policy direction relevant to the planned follow-on 

rulemaking for the heavy-duty sector.
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(b) Vocational Vehicle and Tractor Hybrids

For vocational vehicles or combination tractors incorporating hybrid powertrains, 

we proposed two methods for establishing the number of credits generated – chassis 

dynamometer and engine dynamometer testing - each of which is discussed next. As 

discussed in the NPRM the agencies are not aware of models that have been adequately 

peer reviewed with data that can assess this technology without the conclusion of a 

comparison test of the actual physical product.

(i) Chassis Dynamometer Evaluation

For hybrid certification to generate credits we proposed to use chassis testing as 

an effective way to compare the CO2 emissions and fuel consumption performance of 

conventional and hybrid vehicles. See 75 FR at 74256. We proposed that heavy-duty 

hybrid vehicles be certified using “A to B” vehicle chassis dynamometer testing. This 

concept allows a hybrid vocational vehicle manufacturer to directly quantify the benefit 

associated with use of its hybrid system on an application-specific basis. The concept 

would entail testing the conventional vehicle, identified as “A”, using the cycles as 

defined in Section V. The “B” vehicle would be the hybrid version of vehicle “A”. The 

“B” vehicle would need to be the same exact vehicle model as the “A” vehicle. As an 

alternative, if no specific “A” vehicle exists for the hybrid vehicle that is the exact vehicle 

model, the most similar vehicle model would need to be used for testing. We proposed to 

define the “most similar vehicle” as a vehicle with the same footprint, same payload, 

same testing capacity, the same engine power system, the same intended service class, 

and the same coefficient of drag. We did not receive any adverse comments to this 

approach and are therefore adopting the same criteria as proposed. 

To determine the benefit associated with the hybrid system for GHG performance, 

the weighted CO2 emissions results from the chassis test of each vehicle would define the 

benefit as described below:

1. (CO2_A – CO2_B)/ (CO2_A) = ______ (Improvement Factor)

2. Improvement Factor x GEM CO2 Result_B = ___ (g/ton mile benefit)

Similarly, the benefit associated with the hybrid system for fuel consumption 

would be determined from the weighted fuel consumption results from the chassis tests of 

each vehicle as described below:

3. (Fuel Consumption_A – Fuel Consumption_B)/ (Fuel Consumption_A)= 

______ (Improvement Factor)

4. Improvement Factor x GEM Fuel Consumption Result_B = ___ 

(gallon/1,000 ton mile benefit)

The credits for the hybrid vehicle would be calculated as described in the ABT 

program except that the result from Equation 2 and Equation 4 above replaces the (StdFEL) value. 
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The agencies proposed two sets of duty cycles to evaluate the benefit depending 

on the vehicle application to assess hybrid vehicle performance – without and with PTO 

systems. The key difference between these two sets of vehicles is that one set (e.g., 

delivery trucks) does not operate a PTO while the other set (e.g., bucket and refuse 

trucks) does.

The first set of duty cycles would apply to the hybrid powertrains used to improve the 

motive performance of the vehicles without a PTO system (such as pickup and delivery

trucks). The typical operation of these vehicles is very similar to the overall drive cycles 

final in Section II. Therefore, the agencies are finalizing to use the same vehicle drive 

cycle weightings for testing these vehicles, as shown in Table IV-1. 

Table IV-1: Final Drive Cycle Weightings for Hybrid Vehicles Without PTO

Transient 55 mph 65 mph

Vocational Vehicles 75% 9% 16%

Day Cab Tractors 19% 17% 64%

Sleeper Cab Tractors 5% 9% 86%

The second set of duty cycles apply to testing hybrid vehicles used in applications 

such as utility and refuse trucks which tend to have additional benefits associated with 

use of stored energy, in terms of avoiding main engine operation and related CO2

emissions and fuel consumption during PTO operation. To appropriately address 

benefits, exercising the conventional and hybrid vehicles using their PTO would help to 

quantify the benefit to GHG emissions and fuel consumption reductions. The duty cycle 

proposed to quantify the hybrid CO2 and fuel consumption impact over this broader set of 

operation was the three primary drive cycles plus a PTO duty cycle. The PTO duty cycle 

as proposed took into account the sales impact and population of utility trucks and refuse 

haulers. As described in RIA Chapter 3, the agencies proposed to add an additional PTO 

cycle to measure the improvement achieved for this type of hybrid powertrain 

application. The agencies welcomed comments on the final drive cycle weightings and 

the final PTO cycle. 

The agencies received comments from Cummins stating that the proposed 

weighting of the PTO cycle used a time-based weighting instead of a VMT-based 

weighting. For the final rules, the agencies derived new PTO cycle weighting by 

calculating the average speed of a vehicle during the motive portion of its operation, as 

detailed in RIA Chapter 3.7.1.1. The average speed is used in a conversion factor to 

convert the emissions from the PTO operation measured in grams per hour into grams per 

ton-mile. A number of comments were received on the proposed hybrid chassis testing 

approach. 

The agencies received comments from engine manufacturers, hybrid 

manufacturers, and industry associations, as well as non-governmental organizations 

related to proper characterization of hybrid performance. To address concerns raised by 

commenters regarding hybrid testing several updates have been made to clarify a hybrid 
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engine and / or system for pre-transmission, post-transmission, and chassis dynamometer 

testing. As described in 40 CFR 1036.801, a hybrid engine or hybrid power train means 

an engine or powertrain that includes energy storage features other than a conventional 

battery system or conventional flywheel. Supplemental electrical batteries and hydraulic 

accumulators are examples of hybrid energy storage systems. A hybrid vehicle is defined 

in 40 CFR 1037.801 and it means a vehicle that includes energy storage features (other 

than a conventional battery system or conventional flywheel) in addition to an internal 

combustion engine or other engine using consumable chemical fuel. The duty cycles 

used for testing hybrid systems as either the post-transmission or complete chassis 

configuration will be retained from the proposal, however the weighting factors have 

been adjusted so that the performance of applications expected to be hybridized in the 

near term is better reflected. The testing provisions for evaluating the performance 

including the driver model definition, vehicle model, and overall cycle performance have 

been enhanced as described in 40 CFR 1036.525 and 40 CFR 1037.525. Additionally, 

provisions for evaluating power take-off performance improvement have been addressed 

for charge-sustaining testing. For those hybrid systems which utilize shore power (e.g. 

plug-in hybrids), an innovative technology approach in which the certifier characterizes 

the performance associated with the operation of the system in a charge-depleting and 

charge-sustaining mode is most appropriate given the potential for variability in 

performance between applications and system designs. To address the issue of parity 

between methods it should be clarified that the approach taken for hybrid testing is 

consistent for chassis cycle based testing. This method used for both post-transmission 

and complete vehicle chassis testing is the development of an improvement factor which 

is then related to the base system performance. The pre-transmission approach relies on 

work based assessment of performance as with the current engine standards. 

Comments were received from EMA/TMA, ACEEE, stating that the hybrid 

definition and test methodology needs to be more clearly defined. Cummins and 

EMA/TMA asked that the control volumes for the chassis test procedure be specified. 

Allison stated that the baseline configuration in A to B testing needs clarification – as an 

example they said it is not clear if the baseline vehicle needs to be the same model year as 

the hybrid configuration. They added that it is unclear how to account for hotel or 

accessory loads. 

EMA/TMA, Allison, Odyne, and American Trucking Association said that the 

hybrid drive cycles do not match real world hybrid applications, and as such, will result 

in an underestimation of benefits resulting from hybrid use. Some or all of these 

commenters asked that a hybrid drive cycle be developed that consists mainly of transient 

cycle, increased idle time, low steady state operation, and high acceleration and 

deceleration rates. EMA/TMA said the proposed cycle – the CARB heavy-heavy duty 

truck transient mode cycle, was developed as a composite cycle based on a wide range of 

medium- and heavy-duty vehicles but does not reflect the high acceleration and 

deceleration of vehicles used in urban applications and which is typical for hybrid 

vehicles and does not reflect the level of acceleration and deceleration typical of hybrids. 

Eaton asked that the agencies establish four separate test cycles for hybrids rather than 

two that more closely match what actual hybrids do in use. Hino said that energy

recapture from regenerative braking needs to be built into the test cycle and as currently
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designed it is not. Hino also urged the agencies to create test cycles that capture 

variations in different types of hybrids. Cummins said that more representative vehicle 

test cycles should be developed based on the FTP and SET to ensure that the test cycles 

are functionally equivalent between vehicles and engines to ensure fair evaluation of the 

technology. ICCT articulated the same point on the need for parity between engine and 

vehicle test cycles. 

EMA/TMA, DTNA, and Cummins asked that manufacturers not be required to 

conduct coastdown testing for hybrid vehicles to establish road loads for each type of 

vehicle. Instead, they asked that the agencies define default road load values for 

manufacturers to use for hybrids. EMA/TMA said that conducting coastdown tests is 

expensive. They also argued that road load is irrelevant to determining hybrid 

performance since the chassis dynamometer method requires a comparison of a vehicle 

that is identical in all respects except those factors directly relating to the hybrid 

powertrain. 

Cummins, ICCT, and Center for Clean Air Policy expressed general support for 

chassis dynamometer testing. Allison said that the lack of dynamometer infrastructure 

could limit the ability of manufacturers to certify and get hybrids into the market place. 

BAE said that hybrids should not have to be tested on a chassis dynamometer.

Given the options available for certification of hybrid systems, the constraints on 

available infrastructure for traditional chassis testing and coastdown testing has been 

mitigated. Should a manufacturer contemplate chassis testing or powerpack testing to 

assess hybrid vehicle performance, coastdown testing will still be needed for vocational 

applications to develop the road load values. To address concerns regarding the baseline 

vehicle definition, the following clarifications are provided. The baseline vehicle must be 

identical to the hybrid, with the exception being the presence of the hybrid vehicle. 

Should an identical vehicle not be available as a baseline, the baseline vehicle and hybrid 

vehicle must have equivalent power or the hybrid vehicle must have greater power. 

Additionally, the sales volume of the conventional vehicle from the previous model year 

(the vehicle being displaced by the hybrid), must be substantially such that there can be a 

reasonable basis to believe the hybrid certification and related improvement factor are 

authentic. Should no previous year baseline or otherwise existing baseline vehicle exist, 

the manufacturer shall produce or provide a prototype equivalent test vehicle. For pretransmission hybrid certification, drivetrain components will not be included in the 

testing, as is the case for criteria pollutant engine certification today on a brake-specific 

basis. Manufacturers are expected to submit A to B test results for the hybrid vehicle 

certification being sought for each vehicle family. Manufacturers may choose the worst 

case performer as a basis for the entire family. The agencies continue to expect to use 

existing precedent regarding treatment of accessory loads for purposes of chassis testing. 

Accessory loads for A to B testing will not need to be accounted for differently for hybrid 

A to B chassis testing than for criteria pollutant chassis testing. Based on the description 

of the hybrid engines and vehicles as found in 40 CFR 1036 and 1037.801, the agencies 

will not restrict hybrid configuration certification. The expectation is that hybrid engines 

and vehicles certified under the provisions for GHG will use certified engines. As stated 

previously, based on data provided by commenters and industry associations, the 
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agencies have revised the duty cycles for complete vehicle and post-transmission 

powerpack testing by revising the weighting factors such that the performance of the 

hybrid system is more appropriately characterized. The new weighting factors result in a 

performance assessment that more closely matches performance seen in-use by many of 

the applications most likely to be hybridized in the near-term. At this time the 

requirement to conduct coastdown testing remains in place for the vehicle to be chassis 

tested or for the simulated vehicle in powertrain testing. Absent appropriate coefficients 

that accurately reflect vehicle performance, making an assumption about vehicle 

performance could lead to erroneous results and/or errors in the performance assessment. 

The agencies have provided numerous flexibilities, so the options available to those 

manufacturers who choose to certify hybrid engines or vehicles are not constrained to a 

single test method for which limited infrastructure may exist. 

(ii) Engine Dynamometer Evaluation

The engine test procedure proposed in the NPRM for hybrid evaluation involved 

exercising the conventional engine and hybrid-engine system based on an engine testing 

strategy. The basis for the system control volume, which serves to determine the valid 

test article, would need to be the most accurate representation of real world functionality. 

An engine test methodology would be considered valid to the extent the test is performed 

on a test article that does not mischaracterize criteria pollutant performance or actual 

system performance. Energy inputs should not be based on simulation data which is not 

an accurate reflection of actual real world operation. Pre-transmission test protocols will 

include both the engine and the hybrid system for assessing GHG performance, however 

EPA is not changing criteria pollutant certification at this time for engines. In effect, the 

engine will need to be certified for criteria pollutant performance, while the engine and 

hybrid system in combination may be certified for GHG performance. It is clearly 

important to be sure credits are generated based on known physical systems. This 

includes testing using the appropriate recovered vehicle kinetic energy. Additionally, the 

duty cycle over which this engine-hybrid system would be exercised would need to 

reflect the use of the application, while not promoting a proliferation of duty cycles 

which prevent a standardized basis for comparing hybrid system performance. The 

agencies proposed the use of the Heavy-duty FTP cycle for evaluation of hybrid vehicles, 

which is the same test cycle final for engines installed in vocational vehicles. For 

powerpack testing, which includes the engine and hybrid systems in a pre-transmission 

format, the engine based testing is applicable for determination of brake-specific 

emissions benefit versus the engine standard. For post-transmission powertrain systems 

and vehicles, the comparison evaluation based on the Improvement Factor and the GEM 

result based on a vehicle drive trace in a powertrain test cell or chassis dynamometer test 

cell seem to accurately reflect the performance improvements associated with these test 

configurations. It is important that introduction of clean technology be incentivized 

without compromising the program intent of real world improvements in GHG and fuel 

consumption performance. In the NPRM the agencies asked for comments on the most 

appropriate test procedures to accurately reflect the performance improvement associated 

with hybrid systems tested using these or other protocols. 75 FR at 74257.
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A number of comments were received on the proposed engine testing approaches. 

Comments were received from EMA/TMA, Cummins, Allison, Hino, and ICCT, stating 

that the hybrid test methodology needs to be more clearly defined. EMA/TMA, 

Cummins, and Allison stated that the agencies have not defined what they will accept as a 

“complete hybrid system” and a clearer definition for hybrids needs to be developed. For 

example, Allison stated that the DRIA says that a “complete hybrid system” can exclude 

the transmission. They added that a hybrid system must include a transmission. 

EMA/TMA stated that simulated engine dynamometer testing should include hybrid 

components. EMA/TMA stated that the agencies’ proposal that part 1065 may be 

amended, but did not provide specifics on how it might be amended. They suggested the 

following changes to part 1065: 1) all engine and hybrid components capable of 

providing or recovering traction power be included in the control volume; 2) use of 

hybrid system torque curves rather than engine torque curves; 3) reference to J2711 for 

management of energy storage devices; 4) adhere to conventional calculation of 

emissions with only positive work counted; and 5) provide an estimate of maximum 

available kinetic energy in 1065 to ensure that energy capture is consistent with real 

world operation of hybrids. 

Hino said that energy recapture from regenerative braking needs to be built into 

the test cycle and as currently designed it is not. Regenerative braking provides fuel 

consumption and GHG reduction benefits. Eaton said that the proposed powerpack 

testing does not capture true performance of hybrid vehicles. As noted above, ICCT 

commented on the need for parity between engine and vehicle test cycles. They 

supported hardware-in-the-loop post-transmission testing, but only if an equivalent cycle 

is used as for chassis testing. 

Concerns were raised by hybrid system manufacturers that the potential for a 

competitive advantage could exist for hybrids using different methods for certification 

based solely on the test method chosen. For determination of the allowable brake energy 

that may be used for the test cycle with hybrid engines, it is important to provide 

consistency between test methods. For that reason EPA is setting a brake energy fraction 

limit based on the engine FTP duty cycle which would apply to the pre-transmission 

hybrid and defining that as the limit for the post-transmission maximum available brake 

energy as well. The brake energy fraction will need to be determined based on the engine 

performance and the brake energy fraction limit will apply for all powertrain test cell 

(powerpack) testing. This limit on the brake energy fraction will be ratio of negative 

work to positive work as a function of engine rated power.

The agencies are also finalizing that the proposed duty cycles considered for the 

proposal will continue to be used with this final action. The agencies proposed a 

transient duty cycle, a 55 mile-per-hour steady state cruise and a 65 mile-per-hour steady

state cruise. The transient duty cycle, which has been corrected to address a concern 

related to shift events, is essentially the same transient cycle proposed in the NPRM with 

the exception that it minimizes inappropriate shift events. Additionally, the steady state 

cycles proposed by the Agencies remain essentially unchanged. The modification being 

adopted with today’s final action is to address the distribution of the emissions impact 

associated with each duty cycle. However, in response to the concerns detailed above 
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and raised by engine manufacturers, hybrid system manufacturers, environmental groups, 

and NGOs regarding the lack of transient operation in the hybrid cycles, the agencies are 

finalizing a change in the weighting of the hybrid vehicle cycles. The weighting factors 

will be changed such that a greater emphasis on the type of transient activity seen as more 

characteristic of hybrid applications will be evident. The new weighting factors between 

duty cycles for hybrid certification (without PTO) will be 75% for the transient, 9% for 

the 55 mph cruise cycle, and 16% for the 65 mph cruise cycle. The basis for this change 

may be seen in the memorandum to OAR Docket EPA-HQ-OAR- 2010-0162 which 

describes the data set used to describe real world vehicle performance. Additionally, 

provisions for addressing brake energy fraction have been provided in 40 CFR 1036.525 

for hybrid engine testing. The control volume for testing hybrid systems for GHG and 

fuel consumption assessment has included all hybrid power systems and for powertrain 

testing that is post-transmission, simulated components including tires and regenerative 

braking impacts. Additionally, provisions for accounting for the hybrid system and 

engine torque curve are available in the hybrid test procedures of 40 CFR 1036.525. 

In addition, the final rules allow manufacturers that want to certify a hybrid on a 

different test cycle than the cycles described above for chassis and engine dynamometer 

testing instead make a demonstration using the procedures set out in the Innovative 

Technology Credit provisions. Likewise, a manufacturer seeking to certify a hybrid 

using an alternative approach, such as simulation modeling, would need to follow the 

procedure described in the Innovative Technology Credit section. However, 

manufacturers whose alternative hybrid testing procedure is approved through the 

Innovative Technology Credit Program would receive credits through the Advanced 

Technology Credit Program so such credits would be fungible across all vehicle and 

engine categories and would receive the 1.5 multiplier. 

EMA/TMA also asked that in addition to the above-described engine, chassis, and 

powerpack testing, other yet-to-be-defined methods should be allowed so that a novel 

application of hybrids can be evaluated for credit. They included hydraulic, kinetic, 

electro-mechanical, and genset hybrids as examples of additional configurations that 

should be accommodated by additional test cycles. Allison asked how emissions and fuel 

consumption changes associated with ageing of hybrid systems will be accounted for. 

ACEEE encouraged the agencies to finalize the three approaches outlined in the NPRM 

for hybrid testing in the final rules.

Cummins supported three proposed options for evaluating hybrids. ICCT 

supported option 1 and 3, but not 2. ICCT stated that EPA and NHTSA need to ensure 

that: 1) each hybrid test method/test cycle combination requires the same amount of total 

energy to run the cycle (for a specific vehicle weight), 2) each test method/test cycle 

combination has the same amount of total energy available for capture as regeneration by

a hybrid system, and 3) that this available regeneration energy appears in similar 

increments in each test method/test cycle combination. 

In allowing for three options for certification of hybrids, two of those options 

require the use of a baseline vehicle. The post-transmission hybrid certification and the 

chassis dynamometer certification options are designed to allow for an assessment of the 
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improvement offered by incorporating a hybrid system into the vehicle. Determination of 

an improvement factor for hybrid vehicle performance is significantly influenced by the 

selection of the baseline vehicle, test article “A”. The Agencies received comments from 

engine and hybrid system manufacturers that the options for selection of the baseline 

should be carefully considered to avoid an unintended consequence of limited real world 

improvement due to selection of a baseline that was inappropriate. Several concerns 

regarding an inappropriate baseline were broached including selection of technology that 

is not actually available in the market, selection of baseline technology that is not 

representative of the application(s) either by sales volume or use, or selection of a 

baseline that in other ways provides an advantage to a manufacturer which creates an 

unfair competitive advantage. To address the concern of improvement factors that have a 

basis in reality and demonstrate real world improvements, as well as to continue to create 

incentives for the introduction of new technology the Agencies are addressing the issue 

of the baseline selection, as well as the determination of a “most similar” vehicle basis in 

the case where there may not be an existing production vehicle upon which the hybrid 

vehicle was based. 

In making the determination of an appropriate baseline, four options were 

considered by the agencies. These options included a fixed baseline weight and 

definition by vehicle class, a non-hybrid baseline intended for production vehicle and 

transmission system, a best in class conventional application, or vehicle based on highest 

sales volume. Each of these options has benefits and each raises potential concerns. The 

determination based solely on a single vehicle by class has the advantage of providing a 

fixed baseline the entire industry may easily target for assessing improvements. It raises 

concerns regarding the suitability of the vehicle selection for all applications in the 

weight class, as well as the appropriateness of the selection based on performance across 

the full range of vehicles and weights in the weight class. The “intended for production” 

conventional vehicle baseline ensures the baseline and hybrid vehicle pair will represent a 

real improvement for the specific application. The challenge exists when the 

conventional vehicle version of the hybrid may not exist. Another issue would exist if 

the conventional vehicle in the pair had performance characteristics such that the hybrid 

version does not represent significant improvements beyond other conventional vehicles. 

The best in class baseline vehicle approach provides some assurance that the 

improvement factor generated by the hybrid vehicle or system would in fact represent 

introduction of advanced technology with improvements beyond existing conventional 

technology. The opportunity for confusion that exists with a best in class determination 

includes matching all of the appropriate performance metrics with the appropriate 

applications in a way that is consistent with how the market values those improvements. 

This can become a moving target which could represent an ever evolving design target 

and eventually prove difficult for the Agencies to implement in a way that ensured a level 

playing field. The last option attempts to include the benefits of the previous options, 

while maintaining the clarity needed for manufacturers to design and build with a clear 

understanding of design targets. The highest sales volume application by weight class for 

the previous model year ensures benefits are measured based on how the market values 

performance. This has the potential to avoid ambiguity regarding which vehicle 

technology should serve as the baseline and it addresses a concern raised by some 

commenters regarding the use of a baseline vehicle that clearly is not a class leader. The 
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presumption being that the market will value the conventional technology that provides 

the best value over the lifetime of the vehicle for its intended service class and 

application. This approach is intended to be used in conjunction with the basic premise 

that the “A” vehicle will be the vehicle most similar to the hybrid “B” vehicle. 

Should no apparent baseline be available, the vehicle being displaced by the 

hybrid may be determined based on several characteristics including but not limited to 

vehicle class, vehicle application, and complete power system rated power (e.g. engine 

rated power for the base vehicle versus combined rated power for the engine-hybrid 

system). The agencies will continue to use the primary method of highest sales volume, 

by application and vehicle weight class in its assessment of the manufacturers selection 

of a baseline, however should there be a new application introduced with no apparent 

existing baseline, the closest baseline vehicle may be selected by the manufacturer and 

will be evaluated by the agencies. 

The commenters' concerns will continue to be reviewed by the agencies as the 

program is implemented; however, the approach suggested may not be appropriate across 

every method. To the extent that the pre-transmission testing is a work based assessment 

consistent with today's engine testing, we are remaining consistent with current practices 

in which the engine certification has applicability across applications. With that said we 

have defined a regenerative brake limit that will align the relative energy (regenerative to 

tractive) across all three methods. This can be found in 40 CFR 1036.525.

Given the use of the same duty cycles for both post-transmission and chassis 

dynamometer testing, we are capturing the performance of the powertrain by exercising it 

in the same manner for both methods, so the methods will be equivalent in all three 

aspects that were mentioned by the commenter.

(3) Innovative Technology Credits

The agencies proposed a credit opportunity intended to apply to new and 

innovative technologies that reduce fuel consumption and CO2 emissions, but for which 

the reduction benefits are not captured over the test procedure, including the GEM, used 

to determine compliance with the standards (i.e., the benefits are “off-cycle”). See 75 FR 

at 74257-58; see also 75 FR 25438-25440 where EPA adopted a similar credit program 

for MY 2012-2016 light-duty vehicles. 

The agencies explained in the NPRM that EPA and NHTSA are aware of some 

emerging and innovative technologies and concepts in various stages of development 

with CO2 emissions and fuel consumption reduction potential that might not be 

adequately captured on the final certification test cycles or are not inputs to the GEM, and 

that some of these technologies might merit some additional CO2 and fuel consumption 

credit generating potential for the manufacturer. Eligible innovative technologies are 

those technologies that are newly introduced in one or more vehicle models or engines, 

but that are not yet widely implemented in the heavy-duty fleet– and more specifically, 

not yet widely implemented in the averaging set for which the credit is sought. Examples 

of such technologies mentioned in the NPRM include predictive cruise control, gear-
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down protection, active aerodynamic features, and adjustable ride height. Innovative 

technologies can include known, commercialized technologies if they are not yet widely 

utilized in a particular heavy-duty sector subcategory. Any credits for these technologies 

would need to be based on real-world fuel consumption and GHG reductions that can be 

measured with verifiable test methods using representative driving conditions typical of 

the engine or vehicle application.

In the NPRM, the agencies stated that we would not consider technologies to be 

eligible for these credits if the technology has a significant impact on CO2 emissions and 

fuel consumption over the primary test cycles, or if it is one of the technologies on whose 

performance the various vehicle and engine standards are premised. The agencies 

believe it is appropriate to provide an incentive to encourage the introduction of these 

types of technologies and that a credit mechanism is an effective way to do so. Further, 

there needs to be a mechanism to account for the emission reductions and fuel 

efficiencies resulting when an innovative technology is used. The agencies proposed that 

this optional credit opportunity would be available through the 2018 model year

reflecting that technologies which are now uncommon may be more widely utilized by

then, but the agencies sought comment on the need to extend the ability to earn credits 

beyond the model year 2018. See generally 75 FR at 74257-258.

EPA and NHTSA also proposed that credits generated using innovative 

technologies be restricted within the subcategory averaging set where the credit was 

generated but requested comments on whether these innovative technology credits should 

be fungible across vehicle and engine categories. 

The agencies also proposed that manufacturers quantify CO2 and fuel 

consumption reductions associated with the use of the off-cycle technologies such that 

the credits could be applied based on the metrics (such as g/mile and gal/100 mile for 

pickup trucks, g/ton-mile and gal/1,000 ton-mile for tractors and vocational vehicles, and 

g/bhp-hr and gal/100 bhp-hr for engines). Credits would have to be based on real 

additional reductions of CO2 emissions and fuel consumption and would need to be 

quantifiable and verifiable with a repeatable methodology. Such data would be submitted 

to EPA and NHTSA, and would be subject to a public evaluation process in which the 

public would have opportunity for comment. See 75 FR at 74258. We proposed that the 

technologies upon which the credits are based would be subject to full useful life 

compliance provisions, as with other emissions controls. Unless the manufacturer can 

demonstrate that the technology would not be subject to in-use deterioration over the 

useful life of the vehicle, the manufacturer would have to account for deterioration in the 

estimation of the credits in order to ensure that the credits are based on real in-use 

emissions reductions over the life of the vehicle.

In cases where the benefit of a technological approach to reducing CO2 emissions 

and fuel consumption cannot be adequately represented using existing test cycles, it was 

proposed that EPA and NHTSA would review and approve as appropriate test procedures 

and analytical approaches to estimate the effectiveness of the technology for the purpose 

of generating credits. The demonstration program would have to be robust, verifiable, 
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and capable of demonstrating the real-world emissions benefit of the technology with 

strong statistical significance. 

Finally, the agencies explained in the NPRM that the CO2 and fuel consumption 

benefit of some technologies may have to be demonstrated with a modeling approach. In 

other cases manufacturers might have to design on-road test programs that are 

statistically robust and based on real world driving conditions. As with the similar 

procedure for alternative off-cycle credits under the light-duty 2012-2016 MY vehicle 

program, the agencies would include an opportunity for public comment as part of any 

approval process.

The agencies requested comments on the proposed approach for off-cycle 

innovative technology emissions credits, including comments on how best to structure the 

program. EPA and NHTSA particularly requested comments on how the case-by-case 

approach to assessing off-cycle innovative technology credits could best be designed, 

including ways to ensure the verification of real-world emissions benefits and to ensure 

transparency in the process of reviewing manufacturer’s proposed test methods.

The agencies received numerous comments relating to all aspects of the 

innovative technology credit flexibility provision. The vast majority of the commenters 

supported this provision as proposed, but requested that certain aspects be further 

clarified, so the agencies are adopting the full provision as proposed and providing 

further discussion that addresses and clarifies the provision in response to comments. We 

also note generally that many comments asserting that the GEM or certain of the engine 

standards failed to account for certain types of emission reductions associated with 

technology improvements did not consider the availability of innovative technologies for 

such technologies. These comments are addressed specifically in the Response to 

Comment Document or elsewhere in this preamble.

A number of organizations, including DTNA, MEMA, Navistar, Green Truck 

Association, Eaton, ACEEE, and NESCAUM, commented that technologies such as 

advanced transmissions, engine cooling strategies, idle reduction, light-weight 

components (including light-weight engines), and advanced drivelines should be able to 

receive credit through the innovative technology program. The agencies agree with these 

commenters. The NPRM did not provide a specific list of technologies that the agencies 

would consider “innovative” because the agencies intended that a innovative technology

could be any technology not in widespread use in the subcategory that can be proven to 

reduce CO2emissions and fuel consumption but for which the benefits are not captured 

utilizing the FTP procedures, SET procedures and GEM methodology used to determine 

compliance with the emission and fuel consumption standards. Any of the suggested 

technologies could be considered as an innovative technology if the associated emission 

and fuel consumption benefit has not already been considered to have widespread use in 

the subcategory, if the associated emission and fuel savings can be measured and 

validated, and if the technology and measurement methodology have been approved by 

the agencies. NHTSA and EPA will determine the impact of the technology and each 

agency in turn will accept the credits either jointly or independently depending upon 

whether the technology has a direct bearing upon GHG or fuel consumption performance. 
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A number of commenters, including Bendix, Bosch, Cummins, EMA/TMA, 

Eaton, DTNA, Navistar, Volvo, ArvinMeritor and USC requested that the innovative 

technology process and procedures be more clearly structured and defined. Bendix 

requested that the agencies prescribe specific processes and procedures in the final rules

by which innovative technologies can be submitted for review and approval. EMA/TMA 

requested that the agencies provide guidance on the certification process, and suggested 

that existing fuel consumption test procedures developed jointly by the Society of 

Automotive Engineers (SAE) and the Technology & Maintenance Council (TMC), 

specifically that the Type II and Type III procedures be used. Eaton requested that the 

agencies identify test methods that can be used for certification in order to provide 

transparency and certainty, and promote early technology introduction. In response to 

these comments, the agencies have further defined the process in the final action. 

In cases where the benefit of a technological approach to reducing CO2 emissions 

and fuel consumption cannot be adequately represented using existing test cycles, EPA

and NHTSA will review and approve test procedures and analytical approaches as 

appropriate to estimate the effectiveness of the technology for the purpose of generating 

credits. The innovative technologies will be evaluated in an A-to-B comparison. The 

baseline engine and/or vehicle configuration must represent a configuration which is 

equivalent to the engine and/or vehicle with the innovative technology in terms of the 

other aspects of the engine and/or vehicle to prevent double counting of emissions 

reductions or gaming. 

Since innovative credits will be available for use within the same averaging set as 

the engine or vehicle which employ the innovative technology (for reasons explained 

below), the agencies are defining innovative credit approaches by regulatory category.

(a) Heavy-Duty Pickup Truck and Van Innovative Technology Credits

For HD pickups and vans, EPA and NHTSA proposed that they would review and 

approve manufacturer-provided test procedures and analytical approaches to estimate the 

effectiveness of a technology for the purpose of generating credits. The proposal also 

expressed the view that the 5-cycle approach currently used in EPA’s fuel economy 

labeling program for light-duty vehicles may provide a suitable test regime, provided it 

can be reliably conducted on the dynamometer and can capture the impact of the offcycle technology (see 71 FR 77872, December 27, 2006). EPA established the 5-cycle 

test methods to better represent real-world factors impacting fuel economy, including 

higher speeds and more aggressive driving, colder temperature operation, and the use of 

air conditioning. Because we have not firmly established the suitability of the 5-cycle 

approach for HD pickups and vans at this time, and we received no comments or data 

helping to establish it, we are not adopting provisions to specify its use. However, it 

remains a candidate approach that manufacturers may pursue in making their 

demonstrations for innovative technology credits, described below.

Manufacturer data submitted to the agencies in pursuit of innovative technology

credits would be subject to a public evaluation process in which the public would have 
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opportunity for comment.301 Whether the approach involves on-road testing, modeling, 

or some other analytical approach, the manufacturer would be required to present a final 

methodology to EPA and NHTSA. EPA and NHTSA would approve the methodology

and credits only if certain criteria were met. Baseline emissions and fuel consumption302

and control emissions and fuel consumption would need to be clearly demonstrated over 

a wide range of real world driving conditions and over a sufficient number of vehicles to 

address issues of uncertainty with the data. Data would need to be on a vehicle modelspecific basis unless a manufacturer demonstrated model-specific data was not necessary. 

The agencies would publish a notice of availability in the Federal Register notifying the 

public of a manufacturer’s proposed alternative off-cycle credit calculation methodology

and provide opportunity for comment. The notice will include details regarding the 

methodology, but not include any Confidential Business Information.

The agencies did not receive any adverse comments on using the proposed 

approach for HD pickup trucks and vans. Consistent with the proposal, the agencies are 

adopting the proposed innovative technology credit provisions for HD pickup trucks and 

vans.

(b) Heavy-Duty Engine, Combination Tractor, and Vocational Vehicle Innovative 

Technology Credits

Innovative technology credits developed in the HD engine, combination tractor, 

and vocational vehicle categories will need to be applied to the subcategory in which they

were generated. The agencies are adopting provisions in §1037.610 to determine the 

separation of engine credits and vehicle credits based on the method which is selected by

the manufacturer to determine the effectiveness of the innovative technology. For 

example, improvements to the engine that are demonstrated in either the engine 

dynamometer test or powerpack test will clearly be engine credits. Improvements that 

are demonstrated using chassis dynamometer or on-road test will be considered vehicle 

credits. However, the agencies recognize that there may be exceptions to this approach, 

and will allow for the manufacturer to request an alternate classification of credits. A 

change in credit allocation will require approval from the agencies and would be subject 

to a public evaluation process. 

Furthermore, to address the concerns of some commenters mentioned above, the 

agencies are adopting an approach for HD engines and vehicles that provides two paths 

for approval of the test procedure to measure the CO2 emissions and fuel consumption 

reductions of an innovative off-cycle technology used in the HD engine or vehicle. These 

alternative approaches are similar to those adopted in the light-duty vehicle rule. The 

first path will not require a public approval process of the test method. The “preapproved” test methods for HD engines and vehicles will include the A-to-B chassis 

testing, powerpack testing, and on-road testing. The agencies are also adopting as 

proposed a second test method approval path that provides a manufacturer the ability to 

 

301 See 75 FR 25440. 

302

 Fuel consumption is derived from measured CO2 emissions using conversion factors of 8,887 g 

CO2/gallon for gasoline and 10,180 g CO2/gallon for diesel fuel.
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submit an alternative evaluation approach to EPA and NHTSA, which must be approved 

by the agencies prior to the demonstration program. As with HD pickup trucks and vans, 

such submissions of data should be submitted to the agencies and would be subject to a 

public evaluation process in which the public would have opportunity for comment.303 

Baseline emissions and control emissions would need to be clearly demonstrated over a 

wide range of real world driving conditions and over a sufficient number of vehicles to 

address issues of uncertainty with the data. The agencies will publish a notice of 

availability in the Federal Register notifying the public of a manufacturer’s proposed 

alternative off-cycle credit calculation methodology and provide opportunity for 

comment. The notice will include details regarding the methodology, but not include any 

Confidential Business Information. Approval of the approach to determining a CO2 and 

fuel consumption benefit would not imply approval of the results of the program or 

methodology; when the testing, modeling, or analyses are complete the results would 

likewise be subject to EPA and NHTSA review and approval. 

The pre-approved test procedures include engine dynamometer, powerpack, 

chassis dynamometer, and on-road testing. Each of the test procedures require the 

evaluation of a baseline and control engine or vehicle (A vs. B testing) to quantify the 

improvement. Manufacturers may use the engine dynamometer test procedures using the 

HD engine FTP or SET cycle. The chassis testing and powerpack testing would be 

conducted the same as described above for HD vocational vehicle and tractor hybrid 

testing in Section IV.B.2.b using the drive cycles and weightings finalized in this action 

for the primary program. If a manufacturer requires the use of an alternate duty cycle, 

then it will require prior approval from the agencies. 

The on-road testing would be tested according to SAE J1321 Joint TMC/SAE 

Fuel Consumption Test Procedure Type II Reaffirmed 1986-10 or SAE J1526 Joint 

TMC/SAE Fuel Consumption In-Service Test Procedure Type III Issues 1987-06, with 

additional constraints to improve the test repeatability. The first constraint requires that 

the minimum route distance be set at 100 miles. In addition, the route selected must be 

representative in terms of grade. The agencies will take into account published and 

relevant research in determining whether the grade is representative.304 Similarly, the 

speed of the route must be representative of the drive cycle weighting adopted for each 

regulatory subcategory. For example, if the route selected for an evaluation of a 

combination tractor with a sleeper cab contains only interstate driving, then the 

improvement factor would only apply to 86 percent of the weighted result. Lastly, the 

ambient air temperature must be between 5 and 35°C. The agencies also would allow the 

use of a Portable Emissions Measurement (PEMS) device for the measurement of CO2

emissions during the on-road testing. The agencies are not pre-approving any routes for 

 

303 See 75 FR 25440. 

304 The agencies would consider information such as the study conducted by Oak Ridge National Lab 

which found that 72 percent of their data records were driven on flat terrain of less than 1 percent grade to 

determine the representativeness of the route. See Capps, G., O. Franzes, B.Knee, M.B. Lascurain, and P. 

Otaduy. Class 8 Heavy Truck Duty Cycle Project Final Report. ORNL/TM-2008/122, Oak Ridge National 

Laboratory. Last accessed on April 14, 2011 at page 5-14 of 

http://cta.ornl.gov/data/tedb29/Edition29_Chapter05.pdf
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the on-road testing. Manufacturers will be required to submit the proposed route prior to 

testing for approval. 

 The agencies requested comments on whether credits generated using innovative 

technologies should be fungible across vehicle and engine categories and received 

comments both supporting and opposing the limited fungibility of these credits. Cummins 

did not support the fungibility of innovative technology credits across subcategories, 

arguing that it is not advisable given the large number and variability of different 

technology types and the uncertainty in this provision. DTNA stated that the credits 

should be fungible across engine and vehicle classes to be treated the same as advanced 

technology credits. EPA and NHTSA acknowledge that the HD program is a new 

program and, though the agencies continue to believe the credit provision is an important 

flexibility, the agencies are implementing innovative technology credits based on the 

ability to assign a value for future technologies and test methods that are as yet to be 

defined. Given the fact that the agencies cannot make a determination at this time of, 

what innovative technologies will be offered, and thus the impact of increased fungibility

to sectors outside the original application of the innovative technology might be, it is 

premature to allow that credit to be traded without restriction and with additional credit. 

Until such uncertainty can be understood and quantified, the agencies believe the final 

rules should continue to include restrictions on the fungibility of innovative technology

credits across service classes and categories. 

The agencies proposed that this credit opportunity be available through the 2018 

model year, reflecting that technologies may be common by then, but sought comment on 

the need to extend beyond model year 2018. The agencies received comments from 

DTNA, Navistar, Eaton, Cummins and Bosch supporting the extension of this provision 

beyond model year 2018. Eaton stated that though some technologies will be more 

common in 2018, new technologies will evolve facing the same difficulties concerning 

implementation and would benefit from this provision. Bosch explained that extension of 

the provision past 2018 is important because at the time of the final rule the GEM will 

not incorporate any newer technology until it is updated in phase two of the program, and 

manufactures will therefore continue to need the innovative technology provision for 

receiving credits for technologies not accounted for in GEM. The agencies have 

reviewed these concerns and believe that they are valid. Therefore, the final rule does not 

state that this provision ends in model year 2018. Any action taken on these credits in a 

subsequent rulemaking will be addressed by the agencies at that time in that future 

rulemaking.

(4) N2O Credit

EPA received a comment from an industry stakeholder requesting a provision to allow 

manufacturers of heavy-duty engine to gain credit for redesigning emission control

systems to reduce N2O emissions. The commenter argued that unlike CH4, N2O 

emissions from some NOX control technologies can vary in inverse proportion to CO2

emissions. Given such a tradoeff, it would be appropriate to allow manufacturers to 

exploit that tradeoff to achieve the lowest overall greenhouse gas emissions possible.

Thus, EPA is adopting a provision which allows engine manufacturers to generate CO2
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credits for very low N2O emissions. Specifically, manufacturers that certify engines with 

full useful life N2O FEL emissions which are less than 0.04 g/hp-hr could generate 2.98 

grams of CO2 credit for 0.01 grams of N2O reduced (consistent with the relative global 

warming potentials of CO2 and N2O). For example, where a manufacturer certifies an 

engine family to have low per-brake horsepower hour N2O emissions of 0.01 g/hp-hr and 

applies the 0.02 g/hp-hr assigned deterioration factor, it could certify the engine family to 

a 0.03 g/hp-hr N2O FEL and generate enough CO2 credits to offset CO2 emissions 2.98 

g/hp-hr above the standard. The 0.04 g/hp-hr level is less than the cap standard of 0.10 

g/bhp-hr (so credits generated would not be windfalls) and reflects EPA’s best estimate 

of average N2O performance for today’s engine technologies. See Table II-22 above. 

This value has been chosen to ensure the credit reflects improvements beyond today’s 

baseline performance level. EPA is limiting this provision to model years 2014 through 

2016, the same years that NHTSA’s program is voluntary, to maintain alignment between 

the CO2 emissions and fuel consumption standards. EPA considered allowing the 

provision to continue beyond 2016 but decided given its relatively small value (we expect 

this credit to be worth approximately 3 g/bhp-hr on a standard of 460 g/bhp-hr) and the 

ultimate desirability of alignment of the EPA and NHTSA programs to limit the period of 

this flexibility to the period of time when the NHTSA program will be voluntary.

V. NHTSA and EPA Compliance, Certification, and 

Enforcement Provisions

A. Overview

(1) Compliance Approach 

This section describes EPA’s and NHTSA’s final program to ensure compliance 

with EPA’s final emission standards for CO2, N2O, and CH4 and NHTSA’s final fuel 

consumption standards, as described in Section II. To achieve the goals projected in the 

proposal, it is important for the agencies to have an effective and coordinated compliance 

program for our respective standards. As is the case with the light-duty vehicle rule, the 

final compliance program for heavy-duty vehicles and engines has two central priorities: 

(1) to address the agencies’ respective statutory requirements; and (2) to streamline the 

compliance process for both manufacturers and the agencies by building on existing 

practice wherever possible, and by structuring the program such that manufacturers can 

use a single data set to satisfy the requirements of both agencies. It is also important to 

consider the provisions of EPA’s existing criteria pollutant program and NHTSA’s 

existing LD program in the development of the approach used for heavy-duty

certification and compliance. The existing EPA heavy-duty highway engine emissions 

program has an established infrastructure and methodology that will allow for an 

effective integration with this final GHG and fuel consumption program, without needing 

to create new unique processes in many instances. The HD compliance program will 

address the importance of the impact of new control methods for heavy-duty vehicles as 

well as other control systems and strategies that may extend beyond the traditional 

purview of the criteria pollutant program. 
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Section 202(b)(3)(A) of the Clean Air Act (CAA) defines “model year” to mean “ 

. . . the manufacturer’s annual production period (as determined by the Administrator) 

which includes January 1 of such calendar year” or to mean calendar year if the 

manufacturer has no annual production period. Section 32901(a)(16) of EISA defines 

“model year” with almost identical language. Section 202(b)(3)(A) of the CAA also 

allows the EPA Administrator to define model year differently to assure “. . . that 

vehicles and engines manufactured before the beginning of a model year were not 

manufactured for purposes of circumventing the effective date of a standard . . .” 

Consistent with this statutory language, the NPRM proposed regulatory text to define 

“model year,” in 40 CFR 1036.801, 40 CFR 1037.801 and 49 CFR 535.4. All three 

codified the primary CAA and EISA definition, but differed with respect to language 

intended to prevent circumvention of the standards. The proposed definition for engines 

was:

Model year means the manufacturer’s annual new model production period, except as 

restricted under this definition. It must include January 1 of the calendar year for which 

the model year is named, may not begin before January 2 of the previous calendar year, 

and it must end by December 31 of the named calendar year. Manufacturers may not 

adjust model years to circumvent or delay compliance with emission or standards or to 

avoid the obligation to certify annually.

The proposed definition for vehicles was:

Model year means the manufacturer’s annual new model production period, except as 

restricted under this definition and 40 CFR part 85, subpart X. It must include January 1 

of the calendar year for which the model year is named, may not begin before January 2 

of the previous calendar year, and it must end by December 31 of the named calendar 

year. Use the date on which a vehicle is shipped from the factory in which you finish 

your assembly process as the date of manufacture for determining your model year. For 

example, where a certificate holder sells a cab-complete vehicle to a secondary vehicle 

manufacturer, the model year is based on the date the vehicle leaves the factory as a cabcomplete vehicle.

EPA’s and NHTSA’s vehicle model year definitions differed slightly in wording 

but were essentially the same for §§ 1037.801 and 535.4. In creating the model year 

definition for vehicles, the agencies were mindful of the confusion chassis manufacturers 

may face in determining their model years in a given period of production, for example, 

due to manufacturing and shipping products at different levels of completion and 

involving multiple manufacturers. The agencies included the term “ship date” in order to 

provide chassis manufacturers a clear reference date (“in which you finish your assembly

process”), as well as to decrease the risk of gaming that might occur if no reference date 

was specified and there were therefore no parameters on the choice of model year. The 

engine definition was chosen based on consistency with prior EPA definitions for other 

mobile source programs.

The agencies received comments on the definitions from EMA/TMA and Navistar 

expressing concern over the potential for unintended consequences. The commenters 

argued that the use of “ship date” for vehicles could create difficulty and uncertainty for 
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manufacturers for whom the ship date can be delayed for reasons outside of their control, 

such as late-arriving components. They also argued that the differences between the 

vehicle and engine definitions would increase the likelihood that a single vehicle would 

be subject to different fuel efficiency requirements during certain years of transition in 

the standards, as it would not be unlikely that a vehicle would be a later model year than 

an engine. For example, during the 2016-2017 period, an engine may be model year 

2016 while the vehicle is model year 2017.

NHTSA and EPA have considered further whether there are benefits to 

maintaining separate definitions for “model year” for the engine and vehicle standards 

based on these comments. We continue to believe that differences in manufacturing 

practices for engines and vehicles support the use of separate definitions. However, for 

this final action, we have decided to modify the definitions to account for the above 

concerns, address circumstances of multiple manufacturers, and provide increased 

consistency and clarity. Thus, instead of “ship date,” the vehicle definition for model 

year will refer to the date when the certifying manufacturer’s “manufacturing operations 

were completed,” within the specified year. The final definition also specifies that each 

vehicle must be assigned a model year before introduction into U.S. commerce, but allow 

a manufacturer to redesignate a later model year if it does not complete its manufacturing 

operations for the vehicle within the initial model year.

To further standardize with EPA definitions, NHTSA will add the EPA engine 

model year definition to its corresponding regulation 49 CFR 535.4. We believe that this 

will address the concerns raised by commenters because it will provide standardization, 

more specificity and account for current manufacturer practices. 

The agencies are aware that the designation of a model year on a chassis for the 

purposes of this heavy-duty truck emission and fuel consumption program may result in a 

complete vehicle that has one model year associated with its chassis for emission/fuel 

consumption purposes and another model year designation in its vehicle identification 

number (VIN) for a motor vehicle’s certification to Federal motor vehicle safety 

standards. However, as the chassis model year designation would only be used on the 

certificate of conformity by the responsible manufacturer for the purpose of complying 

with these rules, it would not contradict other purposes for which a VIN model year may

be used. 

EMA/TMA also argued that the proposed dates used to specify the model year 

would shorten the lead time provided for manufacturers, because production for HD 

vehicles often begins in the early months of the year preceding the model year. We are 

addressing these concerns by finalizing January 1, 2014 as the date certain when 

manufacturers are required to comply. Prior to this date, certification of the vehicle 

would be optional. Thus, a manufacturer could produce uncertified model year 2014 

vehicles through December 31, 2013. The heavy-duty compliance program uses a variety 

of mechanisms to conduct compliance assessments, including preproduction certification 

and postproduction testing and in-use monitoring once vehicles enter customer service. 

Specifically, the agencies are establishing a compliance program that utilizes existing 

EPA testing protocols and certification procedures. Under the provisions of this program, 
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manufacturers will have significant opportunity to exercise implementation flexibility, 

based on the program schedule and design, as well as the credit provisions in the program 

for advanced technologies. This program includes a process to foster the use of 

innovative technologies, not yet contemplated in the current certification process. EPA 

and NHTSA will conduct compliance preview meetings which provide the agencies an 

opportunity to review a manufacturer’s new product plans and ABT projections. Given 

the nature of the final compliance program that involves both engine and vehicle 

compliance for some categories, it is necessary for manufacturers to begin precertification meetings with the agencies early enough to address issues of certification 

and compliance for both integrated and non-integrated product offerings. 

Based on feedback EPA and NHTSA received during the light-duty GHG 

comment period, both agencies are seeking to ensure transparency in the compliance 

process of this program. In addition to providing information in published reports 

annually regarding the status of credit balances and compliance on an industry basis, EPA 

and NHTSA sought comments in the NPRM on additional strategies for providing 

information useful to the public regarding industry’s progress toward reducing GHG 

emissions and fuel consumption from this sector while protecting sensitive business 

information. In response, commenters (Sierra Club and UCS) also had strong interests 

for the agencies to ensure that any collected data is made available to the public with an 

interest especially for providing details on the credit balances for each manufacturer and 

for data on specific vehicle configuration information data to better understand the 

market and help with the development of future programs. Additional requests (ALA and 

EDF) were also made for the agencies to expand consumer education and outreach for 

medium- and heavy-duty vehicles thereby empowering fleet purchasers to make better 

informed choices. Another commenter (ACEEE) specifically requested that the agencies 

publish a heavy-duty truck trend report describing vehicles and engines sold, including 

fuel efficiency and GHG performance and the use of advanced technology. It was further 

recommended (by ALA and EDF) that the agencies should create consumer education 

and outreach programs for medium and heavy-duty vehicles such as fuel consumption 

and GHG emissions information for all vehicles and engines covered by the rules, in 

buyers guide similar to the fuel economy guides that EPA and NHTSA provide for the 

light-duty CAFE program. ICCT and UCS also requested having a consumer based label 

for heavy-duty pickup trucks and vans providing fuel economy and emission information 

like in the light-duty CAFE program. 

The agencies agree that there is a need for sharing heavy-duty emissions and fuel 

consumption information and therefore will make information publically available under 

this program.

(a) Heavy-Duty Pickup Trucks and Vans 

The final compliance regulations (for certification, testing, reporting, and 

associated compliance activities) for heavy-duty pickup trucks and vans closely track 

both current practices and the recently adopted greenhouse gas regulations for light-duty 

vehicles and trucks. Thus they are familiar to manufacturers. EPA already oversees 

testing, collects and processes test data, and performs calculations to determine 
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compliance with both CAFE and CAA standards for Light-Duty. For Heavy-Duty

products that closely parallel light-duty pickups and vans, under a coordinated approach, 

the compliance mechanisms for both programs for NHTSA and EPA would be consistent 

and non-duplicative for GHG pollutant standards and fuel consumption requirements. 

Vehicle emission standards established under the CAA apply throughout a vehicle’s full 

useful life. 

Under EPA’s existing criteria pollutant emission standard program for heavy-duty 

pickup trucks and vans, vehicle manufacturers certify a group of vehicles called a test 

group. A test group typically includes multiple vehicle lines and model types that share 

critical emissions-related features. The manufacturer generally selects and tests a single 

vehicle, typically considered “worst case” for criteria pollutant emissions, which is 

allowed to represent the entire test group for certification purposes. The test vehicle is 

the one expected to be the worst case for the emission standard at issue. Emissions from 

the test vehicle are assigned as the value for the entire test group. However, the 

compliance program in the recent GHG regulations for light-duty vehicles, which is 

essentially the well-established CAFE compliance program, allows and may require 

manufacturers to perform additional testing at finer levels of vehicle models and 

configurations in order to get more precise model-level fuel economy and CO2 emission 

levels. The agencies are adopting this same approach for heavy-duty pickups and vans. 

Additionally, like the light-duty program’s use of analytically derived fuel economy 

(ADFE) data, we will allow manufacturers to predict CO2 levels (and corresponding fuel 

consumption) of some vehicles in lieu of testing, using a methodology deemed 

appropriate by the agencies. Based on manufacturer input, a method for calculating 

analytically derived carbon dioxide (ADCO2) is specified in § 1037.104 of this rule.305 

At a manufacturer’s request, EPA may approve analytical methods alternate to the 

method described in this rule if said alternate methods are deemed to be more accurate 

than the analytical method described in this rule. 

(b) Heavy-duty Engines

Heavy-duty engine certification and compliance for traditional criteria pollutants 

has been established by EPA in its current general form since 1985. In developing a 

program to address GHG pollutants, it is important to build upon the infrastructure for 

certification and compliance that exists today. At the same time, it is necessary to 

develop additional tools to address compliance with GHG emissions requirements, since 

the final standard reflect control strategies that extend beyond those of traditional criteria 

pollutants. In so doing, the agencies are finalizing use of EPA’s current engine test based 

strategy – currently used for criteria pollutant compliance -- to also measure compliance 

for GHG emissions. The agencies are also finalizing to add new strategies to address 

vehicle specific designs and hardware which impact GHG emissions. The traditional 

engine approach would largely match the existing criteria pollutant control strategy. This 

would allow the basic tools for certification and compliance, which have already been 

developed and implemented, to be expanded for carbon dioxide, methane, and nitrous 

 

305 Memorandum from Don Kopinski, U.S. EPA to docket EPA-HQ-OAR-2010-0162, July 7, 2011.
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oxide. Engines with similar emissions control technology may be certified in engine 

families, as with criteria pollutants. 

For EPA, the final approach for certification will follow the current process, 

which requires manufacturer submission of certification applications, approval of the 

application, and receipt of the certificate of conformity prior to introduction into 

commerce of any engines. EPA proposed the certificate of conformity be a single 

document that would be applicable for both criteria pollutants and greenhouse gas 

pollutants. For NHTSA, a manufacturer must submit certification applications with 

equivalent fuel consumption information. NHTSA will assess compliance with its fuel 

consumption standards based on the results of the EPA GHG emissions compliance 

process for each engine family. 

(c) Class 7 and 8 Combination Tractors and Class 2b-8 Vocational Vehicles

Currently, except for HD pickups and vans, EPA does not directly regulate 

exhaust emissions from heavy-duty vehicles as a complete entity. Instead, a compliance 

assessment of the engine is undertaken as described above. Vehicle manufacturers 

installing certified engines are required to do so in a manner that maintains all 

functionality of the emission control system. While no process exists for certifying these 

heavy-duty vehicles, the agencies believe that a process similar to the one we proposed to 

use for heavy-duty engines can be applied to the vehicles.

The agencies are finalizing related certification programs for heavy-duty 

vehicles. Manufacturers will divide their vehicles into families and submit applications 

to each agency for certification for each family. However, the demonstration of 

compliance will not require emission testing of the complete vehicle, but will instead 

involve a computer simulation model, GEM. This modeling tool uses a combination of 

manufacturer-specified and agency-defined vehicle parameters to estimate vehicle 

emissions and fuel consumption. This model is then exercised over certain drive cycles. 

EPA and NHTSA are finalizing the duty cycles over which Class 7 and 8 combination 

tractors would be exercised to be: 65 mile per hour steady state cruise cycle, the 55 mile 

per hour steady state cruise cycle, and the California ARB transient cycle. Additional 

details regarding these duty cycles will be addressed in Section V.D(1)(b) below. Over 

each duty cycle, the simulation tool will return the expected CO2 emissions, in g/tonmile, and fuel consumption, gal/1,000 ton-mile, which would then be compared to the 

standards.

B. Heavy-duty Pickup Trucks and Vans

(1) Compliance Approach

EPA and NHTSA are finalizing, largely as proposed, new emission standards to 

control greenhouse gases (GHGs) and reduce fuel consumption from heavy-duty vehicles 

with gross vehicle weight rating between 8,500 and 14,000 pounds that are not already 

covered under the MY 2012-2016 medium-duty passenger vehicle standards. In this 

section “trucks” refers to heavy-duty pickup trucks and vans between 8,500 and 14,000 

pounds not already covered under the light-duty rule. 
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First, EPA is finalizing fleet average emission standards for CO2 on a gram per 

mile (g/mile) basis and NHTSA is finalizing fuel consumption standards on a gal/100 

mile basis that would apply to a manufacturer’s fleet of heavy-duty trucks and vans with 

a GVWR from 8,500 pounds to14,000 pounds (Class 2b and 3). CO2 is the primary

pollutant resulting from the combustion of vehicular fuels, and the amount of CO2

emitted is highly correlated to the amount of fuel consumed. In addition, the EPA is 

finalizing separate emissions standards for three other GHG pollutants: CH4, N2O, and 

HFC. CH4 and N2O emissions relate closely to the design and efficient use of emission 

control hardware (i.e., catalytic converters). The standards for CH4 and N2O would be set 

as caps that would limit emissions increases and prevent backsliding from current 

emission levels. In lieu of meeting the caps, EPA is allowing manufacturers the option of 

offsetting any N2O emissions or any CH4 emissions above the cap by taking steps to 

further reduce CO2. Separately, EPA is finalizing to set standards to control the leakage 

of HFCs from air conditioning systems. 

Previously, complete vehicles with a Gross Vehicle Weight Rating of 8,500-

14,000 pounds could be certified according to 40 CFR part 86, subpart S. These heavyduty chassis certified vehicles were required to pass emissions on both the Light-duty 

FTP and HFET (California requirement)306. These rules will use the same testing 

procedures already required for heavy-duty chassis certification, namely the Light-duty 

FTP and the HFET. Using the data from these two tests, EPA and NHTSA will compare 

the CO2 emissions and fuel consumption results against the attribute-based target. The 

attribute upon which the CO2 standard is based is a function of vehicle payload, vehicle 

towing capacity and two-wheel versus four-wheel drive configuration. The attributebased standard targets will be used to determine a manufacturer fleet standard. As 

discussed in section IV above, manufacturers may use the ABT program and other 

flexibilities in achieving and demonstrating compliance. 

These rules will generally require complete HD pickups and vans to have CO2,

CH4 and N2O values assigned to them, either from actual chassis dynamometer testing or 

from the results of a representative vehicle in the test group with appropriate adjustments 

made for differences. Manufacturers will be allowed to exclude vehicles they sell to 

secondary manufacturers as incomplete vehicles, unless these vehicles are chassiscertified for criteria (non-GHG) pollutants. To the extent manufacturers are allowed to 

engine- or chassis-certify for criteria pollutant requirements today, they will be allowed 

to continue to do so under the final regulations. See subsection V.B(1)(e) for discussion 

of special provisions for chassis-certification to GHG and fuel consumption standards.

Because this program for heavy-duty pickup trucks and vans is so similar to the 

program recently adopted for light-duty trucks and codified in 40 CFR part 86, subpart S, 

EPA will apply most of those subpart S regulatory provisions to heavy-duty pickup 

trucks and vans and not recodify them in the new part 1037. Most of the new part 1037 

thus would not apply for heavy-duty pickup trucks and vans. How 40 CFR part 86 

applies, and which provisions of the new 40 CFR part 1037 apply for heavy-duty pickup 

 

306 Diesel engines are engine-certified with the option to chassis certification Federally and for California
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trucks and vans is described in §1037.104. Similarly NHTSA’s requirements for these 

vehicles in Part 535.6(a) are based on 40 CFR part 86.

(a) Certification Process

CAA section 203(a)(1) prohibits manufacturers from introducing a new motor 

vehicle into commerce unless the vehicle is covered by an EPA-issued certificate of 

conformity. Section 206(a)(1) of the CAA describes the requirements for EPA issuance 

of a certificate of conformity, based on a demonstration of compliance with the emission 

standards established by EPA under section 202 of the Act. The certification 

demonstration requires emission testing, and certification is required for each model 

year.307

Under existing heavy-duty chassis certification and other EPA emission standard 

programs, vehicle manufacturers certify a group of vehicles called a test group. A test 

group typically includes multiple vehicle car lines and model types that share critical 

emissions-related features.308

EPA requires the manufacturer to make a good faith demonstration in the 

certification application that vehicles in the test group will both 1) comply throughout 

their useful life within the emissions bin assigned, and 2) contribute to fleetwide 

compliance with the applicable emissions standards when the year is over. EPA issues a 

certificate for the vehicles included in the test group based on this demonstration, and 

includes a condition in the certificate that if the manufacturer does not comply with the 

fleet average, then production vehicles from that test group will be treated as not covered 

by the certificate to the extent needed to bring the manufacturer’s fleet average into 

compliance with the applicable standards. 

The certification process often occurs several months prior to production and 

manufacturer testing may occur months before the certificate is issued. The certification 

process for the existing heavy-duty chassis program is an efficient way for manufacturers 

to conduct the needed testing well in advance of certification, and to receive certificates 

in a time frame which allows for the orderly production of vehicles. The use of 

conditions on the certificate has been an effective way to ensure that manufacturers 

comply throughout their useful life and meet fleet standards when the model year is 

complete and the accounting for the individual model sales is performed. EPA has also 

adopted this approach as part of its light-duty vehicle GHG compliance program.

These rules will similarly condition each certificate of conformity for the GHG 

program upon a manufacturer’s good faith demonstration of compliance with the 

manufacturer’s fleetwide average CO2 standard. The following discussion explains how 

the agencies will integrate this new vehicle certification program into the existing 

certification program.

 

307 CAA Section 206(a)(1).

308 The specific test group criteria are described in 40 CFR 86.1827-01, car lines and model types have the 

meaning given in 40 CFR 86.1803-01.
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An integrated approach with NHTSA has been undertaken to allow manufacturers 

a single point of entry to address certification and compliance. Vehicle manufacturers 

will initiate the formal certification process with their submission of application for a 

certificate of conformity to EPA, similar to the light-duty program.

(b) Certification Test Groups and Test Vehicle Selection

For heavy-duty chassis certification to the criteria emission standards, 

manufacturers currently, as mentioned above, divide their fleet into "test groups" for 

certification purposes. The test group is EPA’s unit of certification; one certificate is 

issued per test group/ evaporative family combination. These groupings cover vehicles 

with similar emission control system designs expected to have similar emissions 

performance (see 40 CFR 86.1827-01). The factors considered for determining test 

groups include Gross Vehicle Weight, combustion cycle, engine type, engine 

displacement, number of cylinders and cylinder arrangement, fuel type, fuel metering 

system, catalyst construction and precious metal composition, among others. Vehicles 

having these features in common are generally placed in the same test group.309

This program will retain the current test group structure for heavy-duty pickups 

and vans in the certification requirements for CO2 and fuel consumption. At the time of 

certification, manufacturers will use the CO2 emission level from the Emission Data 

Vehicle as a surrogate to represent all of the models in the test group. However, 

following certification further testing will generally be allowed for compliance with the 

fleet average CO2 and fuel consumption standards as described below. EPA’s issuance of 

a certificate will be conditioned upon the manufacturer’s subsequent model level testing 

and attainment of the actual fleet average, much like light-duty CAFE and GHG 

compliance requires. Under the current program, complete heavy-duty Otto-cycle 

vehicles under 14,000 pounds Gross Vehicle Weight Rating are required to chassis 

certify (see 40 CFR 86.1801-01(a)). The current program allows complete heavy-duty 

diesel vehicles under 14,000 pounds GVWR to optionally chassis certify (see 40 CFR 

86.1863-07(a)). The new regulations we are adopting will not change these existing EPA 

certification options for complete (or incomplete) HD vehicles. EPA recognizes that the 

existing heavy-duty chassis test group criteria do not necessarily relate to CO2 emission 

levels. See 75 FR 25472 (addressing the same issue for light-duty vehicles). For 

instance, while some of the criteria, such as combustion cycle, engine type and 

displacement, and fuel metering, may have a relationship to CO2 emissions, others, such 

as those pertaining to the some exhaust aftertreatment features, may not. In fact, there are 

many vehicle design factors that impact CO2 generation and emissions but are not major 

factors included in EPA’s test group criteria.310 Most important among these may be 

vehicle weight, horsepower, aerodynamics, vehicle size, and performance features. To 

remedy this, EPA will allow manufacturers provisions that are similar to the light-duty

vehicle rule that would yield more accurate CO2 estimates than only using the test group 

emission data vehicle CO2 emissions. 

 

309 EPA provides for other groupings in certain circumstances, and can establish its own test groups in cases 

where the criteria do not apply. See 40 CFR 86.1827-01(b), (c) and (d).

310 EPA noted this potential lack of connection between fuel economy testing and testing for emissions 

standard purposes when it first adopted fuel economy test procedures. See 41 FR 38677, Sept. 10, 1976.
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EPA believes that the current test group concept is appropriate for N2O and CH4

because the technologies that would be employed to control N2O and CH4 emissions may

generally be the same as those used to control the criteria pollutants. However, 

manufacturers will determine if this approach is adequate method for N2O and CH4

emissions compliance or if testing on additional vehicles is required to ensure their entire 

fleet meets applicable standards. 

As just discussed, the “worst case” vehicle a manufacturer selects as the 

Emissions Data Vehicle to represent a test group under the existing regulations (40 CFR

86.1828-01) may not have the highest levels of CO2 in that group. For instance, there 

may be a heavier, more powerful configuration that would have higher CO2, but may, due 

to the way the catalytic converter has been matched to the engine, actually have lower 

NOX, CO, PM or HC emissions. Therefore, EPA is allowing the use of a single Emission 

Data Vehicle to represent the test group for both criteria pollutant and CO2 certification. 

The manufacturer will be allowed to initially apply the Emission Data Vehicle’s CO2

emissions value to all models in the test group, even if other models in the test group are 

expected to have higher CO2 emissions. However, as a condition of the certificate, this 

surrogate CO2 emissions value will generally be replaced with actual, model-level CO2

values based on results from additional testing that occurs later in the model year much 

like the light-duty CAFE program, or through the use of approved methods for 

analytically derived fuel economy. This model level data will become the official 

certification test results (as per the conditioned certificate) and will be used to determine 

compliance with the fleet average. If the test vehicle is in fact the worst case CO2 vehicle 

for the test group, the manufacturer may elect to apply the Emission Data Vehicle 

emission levels to all models in the test group for purposes of calculating fleet average 

emissions. Manufacturers may be unlikely to make this choice, because doing so would 

ignore the emissions performance of vehicle models in their fleet with lower CO2

emissions and would unnecessarily inflate their CO2 fleet average. Testing at the model 

level, in order to better represent the improved performance of vehicles within a test 

group other than the Emission Data Vehicle, will necessarily increase testing burden 

beyond the minimum EDV testing. 

As explained in earlier Sections, there are two standards that the manufacturer 

will be subject to, the fleet average standard and the in-use standard for the useful life of 

the vehicle. Compliance with the fleet average standard is based on production weighted 

averaging of the test data that applies for each model. To address commenter concerns 

regarding test variability due to facility and build variation for each model, the in-use and 

SEA standards are set at 10 percent higher than the level used for that model in 

calculating the fleet average. The certificate covers both of the fleet and in-use standards, 

and the manufacturer has to demonstrate compliance with both of these standards for 

purposes of receiving a certificate of conformity. The certification process for the in-use 

standard is discussed above. 
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(c) Demonstrating compliance 

(i) CO2 and Fuel Consumption Fleet Standards

 As noted, attribute-based CO2 and fuel consumption standards result in each 

manufacturer having fleet average CO2 and fuel consumption standards unique to its 

heavy-duty truck fleet of GVWR between 8,500-14,000 pounds and that standard will be 

separate from the standard for passenger cars, light-trucks, and other heavy-duty trucks.

The standards depend on those attributes corresponding to the relative capability, or 

“work factor”, of the vehicle models produced by that manufacturer. The final attributes 

used to determine the stringency of the CO2 and fuel consumption standards are payload 

and towing capacity as described in Section II. . Generally, fleets with a mix of vehicles 

with increased payloads or greater towing capacity (or utilizing four wheel drive 

configurations) will face numerically less stringent standards (i.e., higher CO2 grams/mile 

standards or fuel consumption gallons/100 miles standards) than fleets consisting of less 

powerful vehicles. (However, the standards will be expected to be equally challenging 

and achieve similar percent reductions.) Although a manufacturer’s fleet average 

standard could be estimated throughout the model year based on projected production

volume of its vehicle fleet, the final compliance values will be based on the final model 

year production figures. A manufacturer’s calculation of fleet average emissions and fuel 

consumption at the end of the model year will be based on the production-weighted 

average emissions and fuel consumption of each model in its fleet. The payload and 

towing capacity inputs used to determine manufacturer compliance will be the advertised 

values.

The agencies will use the same general vehicle category definitions that are used 

in the current EPA HD chassis certification (See 40 CFR 86.1816-05). The new vehicle 

category definitions differ slightly from the EPA definitions for Heavy-duty Vehicle 

definitions for the existing program, as well as other EPA vehicle programs. Mainly, 

manufacturers will be able to test, and possibly model, more configurations of vehicles 

than were historically possible. The existing criteria pollutant program requires the worst 

case configuration be tested for emissions certification. For HD chassis certification, this 

usually meant only testing the vehicle with the highest ALVW, road-load, and engine 

displacement within a given test group. This worst case configuration may only represent 

a small fraction of the test group production volume. By testing the worst case, albeit 

possibly small volume, vehicle configuration, the EPA had a reasonable expectation that 

all represented vehicles would pass the given emissions standards. Since CO2 standards 

are a fleet standard based on a combination of sales volume and work factor (i.e., payload 

and towing capability), it may be in a manufacturer’s best interest to test multiple 

configurations within a given test group to more accurately estimate the fleet average 

CO2 emission levels and not accept the worst case vehicle test results as representative of 

all models. Additionally, vehicle models for which a manufacturer desires to use 

analytically derived fuel economy (ADFE) to estimate CO2 emission levels may need 

additional actual test data for vehicle models of similar but not identical configurations. 

The agencies are allowing the use of ADFE similar to that allowed for light-duty vehicles 

in 40 CFR 600.006-08(e). Some commenters, including the American Automotive 

Policy Council, were concerned that adopting the light-duty ADFE program with its 
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current minimum test requirements would unduly increase testing burden. In addition to 

concerns over implementing the light-duty ADFE program for heavy-duty GHG 

compliance, commenters noted the need to develop a new HD ADFE methodology that 

addressed unique HD concerns. EPA and NHTSA have continued to work with 

stakeholders to address the above concerns with using a modified LD ADFE program. 

To address these concerns, the agencies will expand the allowed use of ADFE beyond 

that which is allowed in the LD program. Since ADFE equations are not final at the time 

of this action, updates to the HD ADFE program will be made through guidance or future 

rulemaking. The GHG and fuel economy rulemaking for light-duty vehicles adopted a

carbon balance methodology used historically to determine fuel consumption for the

light-duty labeling and CAFE programs, whereby the carbon-related combustion products 

HC and CO are included on an adjusted basis in the compliance calculations, along with 

CO2. The resulting carbon-related exhaust emissions (CREE) of each test vehicle are 

calculated and it is this value, rather than simply CO2 emissions, that is used in 

compliance determinations. The difference between the CREE and CO2 is typically very 

small. See generally 75 FR at 25472.

NHTSA and EPA are not adopting the CREE methodology for HD pickups and 

vans, and so will not adjust CO2 emissions to further account for additional HC and CO. 

The basis of the CREE methodology in historical labeling and CAFE programs is not 

relevant to HD pickups and vans, because these historical programs do not exist for HD 

vehicles. Furthermore, test data used in this rulemaking for standards-setting has not 

been adjusted for this effect, and so it would create an inconsistency, albeit a small one, 

to apply it for compliance with the numerical standards we are finalizing. Finally, it 

would add complexity to the program with little real world benefit. 

(ii) CO2 In-Use Standards and Testing

Section 202(a)(1) of the CAA requires emission standards to apply to vehicles 

throughout their statutory useful life. Section II discusses in-use standards.

Currently, EPA regulations require manufacturers to conduct in-use testing as a 

condition of certification for heavy-duty trucks between 8,500 and 14,000 gross vehicle 

weight that are chassis certified. The vehicles are tested to determine the in-use levels of 

criteria pollutants when they are in their first and third years of service. This testing is 

referred to as the In-Use Verification Program, which was first implemented as part of 

EPA’s CAP 2000 certification program (see 64 FR 23906, May 4, 1999). 

An in-use program was already set forth in the light-duty 2012 - 2016 MY vehicle 

rule similar to the heavy-duty pickups and vans. The In-Use Verification Program for 

heavy-duty pickups and vans will follow the same general provisions of the light-duty 

program in regard to testing, vehicle selection, and reporting. See 75 FR 25474-25476.

(d) Special Provisions for Chassis Certification

We proposed to include most cab-chassis Class 2b and 3 vehicles (vehicles sold 

as incomplete vehicles with the cab substantially in place but without the primary loadcarrying enclosure) in the complete HD pickup and van program. Because their numbers 
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are relatively small, and to reduce the testing and compliance tracking burden to 

manufacturers, we proposed to treat these vehicles as equivalent to the complete van or 

truck product from which they are derived. The manufacturer would determine which 

complete vehicle configuration it produces most closely matches the cab-chassis product 

leaving its facility, and would include each of these cab-chassis vehicles in the fleet 

averaging calculations as though it were identical to the corresponding complete “sister” 

vehicle. See 75 FR at 74263.

Commenters opposed this proposed requirement for a number of reasons: (1) it 

would have the unintended consequence of dual certification for some of these vehicles—

engine certification for criteria pollutants and vehicle certification for GHGs, and viceversa for some other vehicles, (2) it would be of modest benefit because most of these 

cab-chassis vehicles would receive the desired aerodynamic and other non-engine 

improvements even without chassis certification, in virtue of their derivation from 

complete vehicles, and (3) a readily-identifiable sister vehicle may not exist in every

case. Based on the comments, the agencies have re-evaluated the proposed approach for 

cab-chassis certification and are restructuring our compliance approach to provide 

significantly more flexibility while still ensuring comparable or better GHG and fuel 

consumption performance overall.

We are not requiring that cab-chassis vehicles be chassis-certified, but are 

retaining chassis-certification for them as an option using the proposed sister vehicle 

concept. We are instead requiring that vehicles that are chassis-certified for criteria 

pollutants be chassis-certified for GHGs and fuel consumption, and likewise that vehicles 

with engines certified for criteria pollutants (which in this case would be engines installed 

in vocational vehicles exclusively) be certified to the vocational vehicle standards for 

GHGs and fuel consumption, with minor exceptions detailed below. We believe that this 

approach involving consistent chassis- and engine-certification for criteria pollutants and 

GHG’s is the most sensible way to structure a program to minimize both the testing 

burden and the potential for gaming.

We are allowing use of the sister vehicle concept for incomplete vehicle 

certification to include the selection of sister vehicles not actually produced for sale by

the certifying manufacturer. For the great majority of vehicles this will not be an issue 

because the sister vehicle will obviously be the complete pickup truck or van from which 

the cab-chassis vehicle is derived. However if the complete sister vehicle ceases 

production but the corresponding incomplete vehicle does not, a manufacturer may

continue to use the sister vehicle emissions data through the carryover process that is 

already practiced today. If carryover is not appropriate because of, for example, an 

emissions-impacting recalibration of the engine, the manufacturer may conduct new 

emissions testing using the coastdown data collected on the original sister vehicle. This 

would still save substantial effort without sacrificing data quality because coastdowns are 

rather resource-intensive but are not much affected by engine changes. Another 

potentially inappropriate situation would exist where no sister vehicle exists because the 

manufacturer does not sell a related complete vehicle. In this case, the manufacturer may

coastdown a mocked-up vehicle made from its incomplete vehicle and an added open or 
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closed cargo box that simulates a complete van or pickup truck, or may coastdown one of 

its customers’ completed vehicles.

EPA and NHTSA requested comment on whether Class 4 vehicles that are very

similar to complete Class 3 pickup truck models should be chassis-certified and regulated 

as part of the HD pickup and van category, instead of as vocational vehicles. 

Commenters argued convincingly that there are a number of important differences 

between the Class 4 and Class 3 trucks that make such regulation inappropriate as a 

general matter. As a result, we are keeping Class 4 trucks in the vocational vehicle 

category. However, we are adding an optional provision that allows manufacturers to 

certify Class 4 or 5 (14,001 to 19,500 lb GVWR) complete or incomplete vehicles to 

GHG and fuel consumption standards, in the same way as Class 2b and 3 vehicles, and 

thus be included within the Class 2b/3 fleet average. The engines in these vehicles will 

continue to be engine-certified for criteria pollutants, but the manufacturers could include 

the vehicles in their fleet average standard and annual compliance calculations, using the 

same certification and compliance provisions as for the smaller vehicles, including the 

equations for determining work factors and target standards, in-use requirements, 

reporting requirements, credit generation and use, and sister vehicle provisions for 

incomplete vehicles. Such vehicles would not be required to meet the vocational vehicle 

standards. Because sales volumes of Class 4 and 5 trucks are relatively small, and 

because we expect these Class 4 and 5 and Class 2b and 3 trucks to generally use the 

same technologies and face roughly the same technology challenge in meeting their 

standards targets, we do not believe that this provision will dilute the stringency of the 

fleet average standards.

Any in-use testing of vehicles that are chassis-certified using the sister vehicle 

provisions would involve loading of the tested vehicle to a total weight equal to the 

ALVW of the corresponding complete vehicle configuration. If the secondary

manufacturer had altered or replaced any vehicle components in a way that would 

substantially affect CO2 emissions from the tested vehicle (e.g., axle ratio has been 

changed for a special purpose vehicle), the vehicle manufacturer could request that EPA 

not test the vehicle or invalidate a test result. Secondary (finisher) manufacturers who 

finish incomplete vehicles certified using the sister vehicle provisions would not be 

subject to requirements under these regulations, other than to comply with anti-tampering 

regulations. However, if they modify vehicle components in such a way that GHG 

emissions and fuel consumption are substantially affected, they become manufacturers 

subject to the standards we are establishing in these rules.

Finally, we are adopting a related special provision involving chassis-certification 

aimed at simplifying compliance for manufacturers of complete HD pickups and vans 

which also sell a relatively small number of engines that are designed for other 

manufacturers’ heavy duty pickups and vans – normally referred to as a ‘loose’ engine. . 

Today these loose engines must be engine-certified for criteria pollutants, even though 

most of the vehicles that use the engines are chassis-certified. Our new provision does 

not change this, but it does provide manufacturers with an option to focus their energy on 

improving the GHG and fuel consumption performance of their complete vehicle 
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products (including, most likely, significant engine improvements), rather than on 

concurrently calibrating for both vehicle and engine test compliance.

These loose engines would not be certified to engine-based GHG and fuel 

consumption standards, but instead would be treated as though they were additional sales 

of the manufacturer’s complete pickup and van products, on a one-for-one basis. The 

pickup/van vehicle so chosen must be the vehicle with the highest ETW that uses the 

engine (as this vehicle is likely to have the highest GHG emissions and fuel 

consumption). However, if this vehicle is a credit-generator under the HD pickup and 

van fleet averaging program, no credits would be generated by these engine-as-vehicle 

contributors to the fleet average; they would be treated as just achieving the target 

standard. If, on the other, the vehicle is a credit-user, the appropriate number of 

additional credits would be needed to offset the engine-as-vehicle contributors. The 

purchaser of the engine would treat it as any other certified engine, and would still need 

to meet applicable vocational vehicle standards for the vehicles in which the engine is 

installed. 

Because it is our intent that this loose engine provision simplify compliance for 

HD pickup/van manufacturers who sell a relatively small number of engines for other 

manufacturers’ applications, we are limiting its use to 10% of the total engines (15,000 

maximum) of the same design that a manufacturer produces in each model year for U.S.-

directed heavy-duty application-- including complete vehicles, incomplete vehicles, and 

the loose engines themselves. We are further limiting both this provision and the abovedescribed provision for chassis certification of Class 4/5 vehicles to spark-ignition 

(gasoline) engines, because we believe that the HD diesel engine business is more 

focused on designing for and marketing into a wide variety of vehicles products, instead 

of into the engine manufacturer’s own chassis-certified vehicle products with a small 

loose engine business on the side, as is common for HD gasoline engines. This dynamic 

is also reflected in the existing provision for criteria pollutants allowing complete HD 

vehicles to use certified diesel engines but not certified gasoline engines.

Together these provisions provide a robust approach to regulating these vehicles 

and engines. Although these certification options are not as straightforward as the 

certification provisions for complete Class 2b/3 pickups and vans, they are technically 

appropriate (for the reasons explained above) and should accomplish more improvement 

in GHG and fuel consumption performance than simply applying the vocational vehicle 

and engine standards,. 

(2) Labeling Provisions

HD pickups and vans currently have vehicle emission control information labels 

showing compliance with criteria pollutant standards, similar to emission control 

information labels for engines. As with engines, we believe this label is sufficient.
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(3) Other Certification Issues

(a) Carryover Certification Test Data

EPA’s final certification program for vehicles allows manufacturers to carry

certification test data over from one model year to the next, when no significant changes 

to models are made. EPA will also apply this policy to CO2, N2O and CH4 certification 

test data. 

(b) Compliance Fees

The CAA allows EPA to collect fees to cover the costs of issuing certificates of 

conformity for the classes of vehicles and engines covered by this rulemaking. On May

11, 2004, EPA updated its fees regulation based on a study of the costs associated with its 

motor vehicle and engine compliance program (69 FR 51402). At the time that cost study

was conducted the current rulemaking was not considered. 

At this time the extent of any added costs to EPA as a result of this rulemaking is

not known. EPA will assess its compliance testing and other activities associated with the 

program and may amend its fees regulations in the future to include any justifiable new 

costs.

(4) Compliance Reports

(a) Pre-Model Year Report 

In the NPRM, EPA and NHTSA proposed that manufacturers must submit early 

model year compliance reports demonstrating how their entire fleets of heavy-duty

pickup trucks and vans would comply with GHG emissions and fuel consumption 

standards. The agencies understood that early model year reports would contain 

estimates that may change over the course of a model year and that compliance 

information manufactures submit prior to the beginning of a new model year may not 

represent the final compliance outcome. The agencies viewed the necessity for requiring 

early model reports as a manufacturer’s good faith projection for demonstrating 

compliance with emission and fuel consumption standards. The preamble language 

indicated that the compliance reports would be submitted prior to the beginning of the 

model year and prior to the certification of any test group. Preferably, a manufacturer 

would submit its reports during its annual certification preview meeting. Precertification 

preview meetings are typically held with a manufacturer before the earliest date that the 

model year can begin which is January 2nd of the calendar year prior to the model year. 

Manufacturers voluntarily choose to participate in precertification compliance meetings 

but meetings are not required by EPA and NHTSA regulations. Manufacturers opt to 

participate in precertification meetings because of the advantage it gives to exploring 

with the agencies any possible compliance problems that may arise prior to seeking 

approval for certificates of conformity. The NPRM preamble text did not specify an 

exact date for manufacturers to submit early compliance reports to the agency. NHTSA 

attempted to adopt requirements in its regulatory text for manufactures to submit their 

early compliance reports no later than the end of December two years prior to the model 
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year. NHTSA also proposed for manufacturers to provide compliance information for 

the current model year and to the extent possible two years into the future. NHTSA 

chose its submission deadline and model years for reporting based upon the same dates 

required by EPA in its CAFE provisions for light-duty pickups and vans beginning in 

model year 2012. 

The NPRM included requirements for manufacturers to submit early model year 

compliance reports separately to each agency based upon limitations existing in the 

statutory authorities prescribed under EISA and CAA and the long-standing precedent set 

in the LD CAFE programs for receiving reports. The EPA report, called the pre-model 

year report, and NHTSA report, called the pre-certification compliance report, were 

proposed to include an estimate of the manufacturer’s attribute-based standards, along 

with a demonstration of compliance with the standards based on projected model-level 

and fleet CO2 emissions and fuel consumption results, and were to include an estimate of 

the manufacturer’s production volumes. The NPRM also included a proposal for 

submitting a credit plan for manufacturers seeking to take advantage of credit flexibilities 

and a credit deficit plan for manufacturers planning to accrue deficits during the model 

years. Additionally, NHTSA attempted to reduce the burden on manufacturers by 

allowing them to submit copies of EPA’s proposed pre-model year reports or applications 

for certifications of conformity, as a substitute to its own compliance report, so long as 

EPA’s reports were submitted with equivalent fuel consumption information. In either 

case, NHTSA reserved the right to ask manufacturers to provide additional information if 

necessary to verify its fuel consumption requirements under this program. EPA and 

NHTSA also proposed to review the compliance reports for technical viability and to 

conduct a certification preview discussion with the manufacturer. It was further proposed 

that the EPA Administrator would have to approve a manufacturer’s pre-model year 

report before it would consider issuing any certificate of compliance for the

manufacturer. 

Comments were received to the NPRM from EMA and TMA strongly opposing 

providing separate reports to EPA and NHTSA and requested that the agencies 

implement a single uniform reporting template that could be submitted to both agencies 

simultaneously. DTNA requested that NHTSA eliminate its pre-certification compliance 

report, arguing that report was overly burdensome. 

For the final rules, the agencies have decided to require manufacturers to submit a 

single report, hereafter referenced as the pre-model year report, to satisfy both agencies 

requirements for receiving compliance reports in advance of the model year. The 

agencies considered the commenters’ requests and determined that the benefit gained by 

receiving separate or distinct compliance reports would not outweigh the burden placed 

on manufacturers in reporting. Therefore, the final rules establish a harmonized approach 

by which manufacturers will submit a single report through the EPA database system as 

the single point of entry for all information required for this national program and both 

agencies will have access to the information. If by model year 2012, the agencies are not 

prepared to receive information through the EPA database system, manufacturers are 

expected to submit written reports to the agencies. EPA and NHTSA have determined 

that requiring manufacturers to submit a joint pre-model year report for their combined 
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fleet of heavy-duty pickup trucks containing both emissions and equivalent fuel 

consumption information falls within each agencies’ statutory authority. The final rules

require a manufacturer to submit the joint pre-model year report as early as the date of the 

manufacturer’s annual certification preview meeting, or prior to the manufacturer 

submitting its first application for a certificate for the given model year. Consequently, a 

manufacturer choosing to comply in model year 2014 could submit its pre-model year 

report during its precertification meeting, which could occur before January 2, 2013. 

Alternately, the manufacturer could provide its pre-model year report any time prior to 

submitting its first application. In either case, a manufacturer would not be able to certify

any of its test groups until the EPA Administrator approves its pre-model year report. 

NHTSA will use the pre-model year report as preliminary model year data. 

The agencies are adopting similar requirements for the pre-model year reports as 

proposed. As mentioned, the agencies proposed that reports would include an estimate of 

the manufacturer’s attribute-based standards, expected testing results and estimated 

production volumes. The agencies agree that this information is essential for tracking

compliance of manufacturers and is therefore adopted for the final rules. The final rules

require manufacturers to identify any vehicle exclusions and other flexibilities afforded

for heavy-duty pickups and vans. The summary of the required information for each premodel year report is as follows:

 A list of each unique vehicle configuration included in the manufacturer’s 

fleet describing the make and model designations, attribute based-values 

(GVWR, GCWR, Curb Weight and drive configurations) and standards.

 The emission and fuel consumption fleet average standard derived from 

the unique vehicle configurations;

 The estimated vehicle configuration, test group and fleet production 

volumes;

 The expected emissions and fuel consumption test group results and fleet 

average performance; 

 A statement declaring whether the manufacturer chooses to comply early 

in MY 2013 for EPA and NHTSA. The manufacturers must acknowledge

that once selected, the decision cannot be reversed and the manufacturer 

will continue to comply with the fuel consumption standards for 

subsequent model years;

 A statement declaring whether the manufacturer will use fixed or 

increasing standards; acknowledging that once selected, the decision 

cannot be reversed and the manufacturer must continue to comply with the 

same alternative for subsequent model years;

 A statement declaring whether the manufacturer chooses to comply

voluntarily with NHTSA’s fuel consumption standards for model years 

2014 through 2015. The manufacturers must acknowledge that once 

selected, the decision cannot be reversed and the manufacturer will 
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continue to comply with the fuel consumption standards for subsequent 

model years;

 The list of Class 2b-3 cab-complete vehicles and the method use to certify, 

as vocational vehicles and engines, or as complete pickups and vans 

identifying the most similar complete vehicles used to derive the target 

standards and performance test results;

 The list of Class 2b-3 incomplete vehicles and the method use to certify, 

as vocational vehicles and engines, or as complete pickups and vans 

identifying the most similar complete vehicles used to derive the target 

standards and performance test results;

 The list of Class 4 and 5 incomplete and complete vehicles and the method 

use to certify, as vocational vehicles and engines, or as complete pickups 

and vans identifying the most similar complete vehicles used to derive the 

target standards and performance test results;

 List of loose engines included in the heavy-duty pickup and van category 

and the list of vehicles used to derive target standards. 

 Copy of any notices a vehicle manufacturer sends to the engine 

manufacturer to notify the engine manufacturers that their engines are 

subject to emissions and fuel consumption standards and that it intends to 

use their engines in excluded vehicles; and 

 A credit plan identifying the manufacturers estimated credit balances, 

planned credit flexibilities (i.e., credit balances, planned credit trading, 

innovative, advanced and early credits and etc.) and if needed a credit 

deficit plan demonstrating how it plans to resolve any credit deficits that 

might occur for a model year within a period of up to three model years 

after that deficit has occurred.

(b) Final Reports

The NPRM proposed for manufacturers participating in the ABT program to 

provide two types of year end reports; end-of-the-year (EOY) reports and final reports. 

The EOY reports for the ABT program were required to be submitted by manufacturers 

no later than 90 days after the calendar year and final report no later than 270 days after 

the calendar year.311 Manufacturers not participating in the ABT program were required 

to provide an EOY report within 45 days after the calendar year but no final reports were 

required. The submission deadline of the final ABT report was established to coincide

with EPA’s existing criteria pollutant report for heavy-duty engines. The EOY report is 

used by the agencies to review a manufacturer’s preliminary final estimates and to 

identify manufacturers that might have a credit deficit for the given model year. 

Manufacturers with a credit surplus at the end of each model year could submit a request 

to the agencies to receive a waiver from providing EOY reports. As proposed, the 

 

311 Corresponding to the compliance model year
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remaining manufacturers were required to submit reports to EPA and send copies of 

those reports to NHTSA with equivalent fuel consumption values. Manufacturers 

requesting to exempt vehicles in accordance with the agencies’ off-road vehicle 

exemption were required to a submit EOY reports to the agencies identifying the vehicle 

applicable to each report within 90 days after the model year ended. 

Comments in response to the NPRM did not oppose providing EOY reports to the 

agencies but instead requested that they be allowed to consolidate the various EOY reports 

into one single submission to the agencies. 

Upon consideration of commenters’ requests, the agencies agree that only one 

consolidated EOY report should be submitted in place of the separate reports proposed in 

the NPRM. The consolidated EOY report should include the combination of all the 

required information that is applicable to a manufacturer’s fleet. The agencies also agree 

to allow manufacturers to no longer provide separate EOY reports to each agency

independently but rather to submit the single report through the EPA database system as 

the single point of entry for all information required for this national program. The 

consolidated EOY report is required to contain both GHG emissions and fuel 

consumption information. EPA will provide access to the information for both agencies. 

Likewise, manufacturers will be required to electronically provide one single final report 

through the EPA database system. If by model year 2012, the agencies are not prepared 

to receive information through the EPA database system, manufacturers are expected to 

submit written reports to the agencies. The required information for EOY and final 

reports that manufacturers must submit is as follows: A finalized list of each unique 

vehicle configuration included in the manufacturers fleet describing the designations, 

attribute based-values (GVWR, GCWR, Curb Weight and drive configurations) and 

standards.

 The final emission and fuel consumption fleet average standard derived 

from the unique vehicle configurations;

 The final vehicle configuration, test group and fleet production volumes;

 The final emissions and fuel consumption test group results and fleet 

average performance; 

 The final list of cab-complete vehicles and the method use to certify, as 

vocational vehicles and engine, or as complete pickups and vans 

identifying the most similar complete vehicles used to derive the target 

standards and performance test results;

 A final credit plan identifying the manufacturers estimated credit balances, 

planned credit flexibilities (i.e., credit balances, planned credit trading, 

innovative, advanced and early credits and etc.) and if needed a credit 

deficit plan demonstrating how it plans to resolve any credit deficits that 

might occur for a model year within a period of up to three model years 

after that deficit has occurred;
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 A plan describing the vehicles that were exempted such as for off-road or 

small business purposes; and

 A plan describing any alternative fueled vehicles that were produced for 

the model year identifying the approaches used to determinate compliance 

and the production volumes.

C. Heavy-Duty Engines

(1) Compliance Approach

Section 203 of the CAA requires that all motor vehicles and engines sold in the 

United States to carry a certificate of conformity issued by the US EPA. For heavy-duty 

engines, the certificate specifies that the engine meets all requirements as set forth in the 

regulations (40 CFR part 86, subpart N, for criteria pollutants) including the requirement 

that the engine be compliant with emission standards. This demonstration is completed 

through emission testing as well as durability testing to determine the level of emissions 

deterioration throughout the useful life of the engine. In addition to compliance with 

emission standards, manufacturers are also required to warrant their products against 

emission defects, and demonstrate that a service network is in place to correct any such 

conditions. The engine manufacturer also bears responsibility in the event that an 

emission-related recall is necessary. Finally, the engine manufacturer is responsible for 

tracking and ensuring correct installation of any emission related components installed by

a second party (i.e., vehicle manufacturer). EPA and NHTSA believe this compliance 

structure is also valid for administering the final GHG regulations for heavy-duty

engines.

(a) Certification Process

In order to obtain a certificate of conformity, engine manufacturers must complete 

a compliance demonstration, normally consisting of test data from relatively new (lowhour) engines as well as supporting documentation, showing that their product meets 

emission standards and other regulatory requirements. To account for aging effects, lowhour test results are coupled with testing-based deterioration factors (DFs), which provide 

a ratio (or offset) of end-of-life emissions to low-hour emissions for each pollutant being 

measured. These factors are then applied to all subsequent low-hour test data points to 

predict the emissions behavior at the end of the useful life. 

For purposes of this compliance demonstration and certification, engines with 

similar engine hardware and emission characteristics throughout their useful life may be 

grouped together in engine families, consistent with current criteria-pollutant certification 

procedures. Examples of such engine characteristics that are normally used to combine 

emissions families include similar combustion cycle, aspiration methods, and 

aftertreatment systems. Under this system, the worst-case engine (“parent rating”) is 

selected based on having the highest fuel feed per engine stroke, and all emissions testing 

is completed on this model. All other models within the family (“child ratings”) are 

expected to have emissions at or below the parent model and therefore in compliance 
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with emission standards. Any engine within the family can be subject to selective 

enforcement audits, in-use, confirmatory, or other compliance testing.

We are continuing the use of this approach for the selection of the worst-case 

engine (“parent rating”) for fuel consumption and GHG emissions as well. As at 

proposal, e believe this is appropriate because this worst case engine configuration would 

be expected to have the highest in-use fuel consumption and GHG emissions within the 

family. See 75 FR at 72264 for further information. We note that lower engine ratings 

contained within this family would be expected to have a higher fuel consumption rate 

when measured over the Federal Test Procedures as expressed in terms of fuel 

consumption per brake horsepower hour. However, this higher fuel consumption rate is 

misleading in the context of comparing engines within a single engine family. This 

apparent contradiction can be most easily understood in terms of an example. For a 

typical engine family a top rating could be 500 horsepower with a number of lower 

engine ratings down to 400 horsepower or lower included within the family. When 

installed in identical trucks the 400 and 500 horsepower engines would be expected to 

operate identically when the demanded power from the engines is 400 horsepower or 

less. So in the case where in-use driving never included acceleration rates leading to 

horsepower demand greater than 400 horsepower, the two trucks with the 400 and 500 

horsepower engines would give identical fuel consumption and GHG performance. 

When the desired vehicle acceleration rates were high enough to require more than 400 

horsepower, the 500 horsepower truck would accelerate faster than the 400 horsepower 

truck resulting in higher average speeds and higher fuel consumption and GHG emissions 

measured on a per mile or per ton-mile basis. Hence, the higher rated engine family

would be expected to have the highest in-use fuel consumption and CO2 emissions

consistent with our current approach requiring manufacturers to certify the worst case 

configuration. 

As explained at proposal, the reason that the lower engine ratings appear to have 

worse fuel consumption relates to our use of a brake specific work metric. The brake 

specific metric measures power produced from the engine and delivered to the vehicle 

ignoring the parasitic work internal to the engine to overcome friction and air pumping 

work within the engine. The fuel consumed and GHG emissions produced to overcome 

this internal work and to produce useful (brake) work are both measured in the test cycle

but only the brake work is reflected in the calculation of the fuel consumption rate. This 

is desirable in the context of reducing fuel consumption as this approach rewards engine 

designs that minimize this internal work through better engine designs. The less work 

that is needed internal to the engine, the lower the fuel consumption will be. If we 

included the parasitic work in the calculation of the rate, we would provide no incentive 

to reduce internal friction and pumping losses. However, when comparing two engines 

within the very same family with identical internal work characteristics, this approach 

gives a misleading comparison between two engines as described above. This is the case 

because both engines have an identical fuel consumption rate to overcome internal work 

but different rates of brake work with the higher horsepower rating having more brake 

work because the test cycle is normalized to 100 percent of the engine’s rated power. 

The fuel consumed for internal work can be thought of as a fixed offset identical between 

both engines. When this fixed offset is added to the fuel consumed for useful (brake) 
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work over the cycle, it increases the overall fuel consumption (the numerator in the rate) 

without adding any work to the denominator. This fixed offset identical between the two 

engines has a bigger impact on the lower engine rating. In the extreme this can be seen 

easily. As the engine ratings decrease and approach zero, the brake work approaches 

zero and the calculated brake specific fuel consumption approaches infinity. For these 

reasons, we are finalizing that the same selection criteria, as outlined in 40 CFR part 86, 

subpart N, be used to define a single engine family designation for both criteria pollutant 

and GHG emissions. Further, we are finalizing that for fuel consumption and CO2

emissions only any selective enforcement audits, in-use, confirmatory, or other 

compliance testing would be limited to the parent rating for the family. Consistent with 

the current regulations, manufacturers may electively subdivide a grouping of engines 

which would otherwise meet the criteria for a single family if they have evidence that the 

emissions are different over the useful life. The agencies received comments from engine 

and truck manufacturers which indicated the useful life provisions applicable to criteria 

pollutants seemed appropriate for GHG emissions. For that reason, the agencies are 

retaining many of the same provisions for GHG certification for family useful life 

provisions as developed for criteria pollutants. 

EPA utilizes a 12-digit naming convention for all mobile-source engine families 

(and test groups for light-duty vehicles). This convention is also shared by the California 

Air Resources Board which allows manufacturers to potentially use a single family name 

for both EPA and California ARB certification. Of the 12 digits, 9 are EPA-defined and 

provide identifying characteristics of the engine family. The first digit represents the 

model year, through use of a predefined code. For example, the code “A” corresponds to 

the 2010 model year and “B” corresponds to the 2011 model year. The 5th position 

corresponds to the industry sector code, which includes such examples as light-duty 

vehicle (V) and heavy-duty diesel engines (H). The next three digits are a unique 

alphanumeric code assigned to each manufacturer by EPA. The next four digits describe 

the displacement of the engine; the units of which are dependent on the industry segment 

and a decimal may be used when the displacement is in liters. For engine families with 

multiple displacements, the largest displacement is used for the family name. For onhighway vehicles and engines, the tenth character is reserved for use by California ARB. 

The final characters (including the 10th character in absence of California ARB guidance) 

left to the manufacturer to determine, such that the family name forms a unique 

identifying characteristic of the engine family.

This convention is well understood by the regulated industries, provides sufficient 

detail, and is flexible enough to be used across a wide spectrum of vehicle and engine 

categories. In addition, the current harmonization with other regulatory bodies reduces 

complications for affected manufacturers. For these reasons, we are not finalizing any

major changes to this naming convention for this rulemaking. There may be additional 

categories defined for the 5th character to address heavy-duty vehicle families, however 

that will be discussed later.

As with criteria pollutant standards, the heavy-duty diesel regulatory category is 

subdivided into three regulatory subcategories, depending on the GVW of the vehicle in 

which the engine will be used. These regulatory subcategories are defined as light-
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heavy-duty (LHD) diesel, medium heavy-duty (MHD) diesel, and heavy heavy-duty

(HHD) diesel engines. All heavy-duty gasoline engines are grouped into a single 

subcategory. Each of these regulatory subcategories are expected to be in service for 

varying amounts of time, so they each carry different regulatory useful lives. For this 

reason, expectations for demonstrating useful life compliance differ by subcategory, 

particularly as related to deterioration factors.

Light heavy-duty diesel engines (and all gasoline heavy-duty engines) have the 

same regulatory useful life as a light-duty vehicle (110,000 miles), which is significantly 

shorter than the other heavy-duty regulatory subcategories. Therefore, we believe it is 

appropriate to maintain commonality with the light-duty vehicle rule. During the lightduty vehicle rulemaking, the conclusion was reached that no significant deterioration 

would occur over the useful life. Therefore, EPA is recommending that manufacturers 

use assigned DFs for CO2. For this final action, we believe appropriate values are zero 

(for additive DFs) and one (for multiplicative DFs). EPA will continue to collect data 

regarding deterioration of CO2 emissions and may revisit these assigned values if 

necessary.

For the medium heavy-duty and heavy heavy-duty diesel engine segments, the 

regulatory useful lives are significantly longer (185,000 and 435,000 miles, respectively). 

For this reason, the EPA cannot rule out the possibility that engine/aftertreatment wear 

will have a negative impact on GHG emissions. To address useful life compliance for 

MHD and HHD diesel engines certified to GHG standards, EPA therefore believes that

the criteria pollutant approach for developing DFs is appropriate. Using CO2 as an 

example, many types of engine deterioration will affect CO2 emissions. Reduced 

compression, as a result of wear, will cause higher fuel consumption and increase CO2

production. In addition, as aftertreatment devices age (primarily particulate traps), 

regeneration events may become more frequent and take longer to complete. Since 

regeneration commonly requires an increase in fuel rate, CO2 emissions would likely

increase as well. Finally, any changes in EGR levels will affect heat release rates, peak 

combustion temperatures, and completeness of combustion. Since these factors could 

reasonably be expected to change fuel consumption, CO2 emissions would be expected to 

change accordingly. However, we expect engine manufacturers to consider performance 

degradation in the design of engine and aftertreatment systems given the market incentive 

to reduce fuel consumption and related CO2 emissions. For these reasons, EPA is not 

eliminating the DF from this program, but will allow for an assigned DF of zero. 

HHD diesel engines may also require some degree of aftertreatment maintenance 

throughout their useful life. For example, one major heavy-duty engine manufacturer 

specifies that their diesel particulate filters be removed and cleaned at intervals between 

200,000 and 400,000 miles, depending on the severity of service. Another major engine 

manufacturer requires servicing diesel particulate filters at 300,000 miles. This 

maintenance or lack thereof if service is neglected, could have serious negative 

implications to CO2 emissions. In addition, there may be emissions-related warranty

implications for manufacturers to ensure that if rebuilding or specific emissions related 

maintenance is necessary, it will occur at the prescribed intervals. Therefore, it is 

imperative that manufacturers provide detailed maintenance instructions. Lean-NOX
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aftertreatment devices may also facilitate GHG reductions by allowing engines to run 

with higher engine-out NOX levels in exchange for more efficient calibrations. In most 

cases, these aftertreatment devices require a consumable reductant, such as diesel exhaust 

fluid, which requires periodic maintenance by the vehicle operator. Without such 

maintenance, the emission control system may be compromised and compliance with 

emission standards may be jeopardized. Such maintenance is considered to be critical 

emission related maintenance and manufacturers must therefore demonstrate that it is 

likely to be completed at the required intervals. One example of such a demonstration is 

an engine power de-rating strategy that will limit engine power or vehicle speed in 

absence of this required maintenance.

If the manufacturer determines that maintenance is necessary on critical emissionrelated components within the useful life period, it must have a reasonable basis for 

ensuring that this maintenance will be completed as scheduled. This includes any

adjustment, cleaning, repair, or replacement of critical emission-related components. 

Typically, EPA has only allowed manufacturers to schedule such maintenance if the 

manufacturer can demonstrate that the maintenance is reasonably likely to be done at the 

recommended intervals. This demonstration may be in the form of survey data showing 

at least 80 percent of in-use engines get the prescribed maintenance at the correct 

intervals. Another possibility is to provide the maintenance free of charge. We see no 

reason to depart from this approach for GHG-related critical emission-related 

components. For reasons stated previously regarding the useful life provisions, EPA is 

retaining many of the same provisions for GHG certification for family useful life 

provisions as developed for criteria pollutants. 

(b) Demonstrating Compliance with the Standards

(i) CO2 Standards

The final test results (adjusted for deterioration, if applicable) form the basis for 

the Family Certification Limit (FCL), which the manufacturer must specify to be at or 

above the certification test results. This FCL becomes the emission standard for the 

family and any certification or confirmatory testing must show compliance with this 

limit. In addition, manufacturers may choose an FCL at any level above their certified 

emission level to provide a larger compliance margin. If subsequent certification or 

confirmatory testing reveals emissions above the FCL, the new, higher result becomes the 

FCL. 

As proposed, the FCL is also used to determine the Family Emission Limit (FEL), 

which serves as the emission limit for any subsequent field testing conducted after the 

time of certification. This would primarily include selective enforcement audits, but also 

may include in-use testing for GHGs. The FEL differs from the FCL in that it includes 

an EPA-defined compliance margin; which has been defined at 3 percent for the final 

rule. Our proposal included a two percent margin based on round-robin testing of the 

same engine at several laboratories. Since that time, additional confidential data provided 

by manufacturers has indicated that it may be more appropriate to use a three percent 
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margin to also account for production variability between engines.312 Under this final 

action, the FEL will always be three percent higher than the FCL. 

Engine Emission Testing

Under current non-GHG engine emissions regulations, manufacturers are required 

to demonstrate compliance using two test methods: the heavy-duty transient cycle and the 

heavy-duty steady state test. Each test is an engine speed versus engine torque schedule 

intended to be run on an engine dynamometer. Over each test, emissions are sampled 

using the equipment and procedures outlined in 40 CFR part 1065, which includes 

provisions for measuring CO2, N2O, and CH4. Emissions may be sampled continuously

or in a batch configuration (commonly known as “bag sampling”) and the total mass of 

emissions over each cycle are normalized by the engine power required to complete the 

cycle. Following each test, a validation check is made comparing actual engine speed 

and torque over the cycle to the commanded values. If these values do not align well, the 

test is deemed invalid.

The transient Heavy-duty FTP cycle is characteristic of typical urban stop-and-go 

driving. Also included is a period of more steady state operation that would be typical of 

short cruise intervals at 45 to 55 miles per hour. Each transient test consists of two 20 

minute tests separated by a “soak” period of 20 minutes. The first test is run with the 

engine in a “cold” state, which involves letting the engine cool to ambient conditions 

either by sitting overnight or by forced cooling provisions outlined in §86.1335-90 (or 40 

CFR part 1036). This portion of the test is meant to assess the ability of the engine to 

control emissions during the period prior to reaching normal operating temperature. This 

is commonly a challenging area in criteria pollutant emission control, as cold combustion 

chamber surfaces tend to inhibit mixing and vaporization of fuel and aftertreatment 

devices do not tend to function well at low temperatures. 

Following the first test, the engine is shut off for a period of 20 minutes, during 

which emission analyzer checks are performed and preparations are made for the second 

test (also known as the “hot” test). After completion of the second test, the results from 

the cold and hot tests are weighted and a single composite result is calculated for each 

pollutant. Based on typical in-use duty cycles, the cold test results are given a 1/7 

weighting and the hot test results are given a 6/7 weighting. Deterioration factors are 

applied to the final weighted results and the results are then compared to the emission 

standards.

Prior to 2007, compliance only needed to be demonstrated over the Heavy-duty

FTP. However, a number of events brought to light the fact that this transient cycle may

not be as well suited for engines which spend much of their duty cycle at steady cruise 

conditions, such as those used in line-haul semi-trucks. As a result, the steady-state SET 

procedure was added, consisting of 13 steady-state modes. During each mode, emissions 

were sampled for a period of five minutes. Weighting factors were then applied to each 

mode and the final weighted results were compared to the emission standards (including 

 

312 See discussion in RIA 3.1.2.3.
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deterioration factors). In addition, emissions at each mode could not exceed the NTE 

emission limits. Alternatively, manufacturers could run the test as a ramped-modal cycle. 

In this case, the cycle still consists of the same speed/torque modes, however linear 

progressions between points are added and instead of weighting factors, each mode is 

sampled for various amounts of time. The result is a continuous cycle lasting 

approximately 40 minutes. With the implementation of part 1065 test procedures in 2010, 

manufacturers are now required to run the modal test as a ramped-modal cycle. In 

addition, the order of the speed/torque modes in the ramped-modal cycle have changed 

for 2010 and later engines.

It is well known that fuel consumption, and therefore CO2 emissions, are highly 

dependent on the drive cycle over which they are measured. Steady cruise conditions, 

such as highway driving, tend to be more efficient, having lower fuel consumption and 

CO2 emissions. In contrast, highly transient operation, such as city driving, tends to lead 

to lower efficiency and therefore higher fuel consumption and CO2 emissions. One 

example of this is the difference between EPA-measured city and highway fuel economy 

ratings assigned to all new light-duty passenger vehicles.

For this heavy-duty engine and vehicle rule, we believe it is important to assess 

CO2 emissions and fuel consumption over both transient and steady state test cycles, as 

all vehicles will operate in conditions typical of each cycle at some point in their useful 

life. However, due to the drive cycle dependence of CO2 emissions, we do not believe it 

is reasonable to have a single CO2 standard which must be met for both cycles. As we 

discussed at proposal, a single CO2 standard would likely prove to be too lax for steadystate conditions while being too strict for transient conditions. Therefore, the agencies 

are finalizing that all heavy-duty engines be tested over both transient and steady-state 

tests. However, only the results from either the transient or steady-state test cycles will 

be used to assess compliance with GHG standards, depending on the type of vehicle in 

which the engine will be used. Engines that will be used in Class 7 and 8 combination 

tractors will use the ramped-modal cycle for GHG certification, and engines used in 

vocational vehicles will use the Heavy-duty FTP cycle. In both cases, results from the 

other test cycle will be reported but not used for a compliance decision. Engines will 

continue to be required to show criteria pollutant compliance over both cycles, in addition 

to NTE requirements.

The agencies proposed that manufacturers submit both data sets from the transient 

test at the time of certification. This includes providing both cold start and hot start 

transient heavy-duty FTP emissions results, as well as the composite emissions at the 

time of certification. The proposed rules also required that manufacturers submit modal 

data from the ramped-modal cycle test. This was proposed in an effort to improve the 

accuracy of the simulation model being used for assessing CO2 and fuel consumption 

performance and overall engine emissions performance. 

However several commenters were concerned that modal data was nondiscernable when batch sampling was used for certification testing. Thus, an additional 

certification test (or tests) would need to be done using either continuous analyzers or 

batch sampling at each mode; each option raising the cost and complexity of certification 
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testing. The agencies agree that (at this time) this raises practical issues for certification 

testing, however we also believe that manufacturers have significant data from these 

modal points which could be used to satisfy our model refinement goals. 

The agencies also recognize that even minor variations in test fuel properties can 

have an impact on measured CO2 emissions. Therefore, measured CO2 results are to be 

corrected using a reference energy content, which is defined in the regulations. This 

correction must be performed for each test and each batch of test fuel. However, 

manufacturers may develop robust testing procedures that reduce the variation in test fuel 

properties to within the level of measurement uncertainty of the fuel properties 

themselves. If this is the case, an annual review is still necessary to confirm the validity

of this constant value.

As explained above in Section II, the agencies are finalizing an alternative 

standard whereby manufacturers may elect that certain of their engine families meet an 

alternative percent reduction standard, measured from the engine family’s 2011 baseline, 

instead of the main 2014 MY standard. As part of the certification process, 

manufacturers electing this standard would not only have to notify the agency of the 

election but also demonstrate the derivation of the 2011 baseline CO2 emission level for 

the engine family. Manufacturers would also have to demonstrate that they have 

exhausted all credit opportunities.

Durability testing

Another element of the current certification process is the requirement to 

complete durability testing to establish DFs. As previously mentioned, manufacturers are 

required to demonstrate that their engines comply with emission standards throughout the 

regulatory compliance period of the engine. This demonstration is commonly made 

through the combination of low-hour test results and testing based deterioration factors.

For engines without aftertreatment devices, deterioration factors primarily 

account for engine wear as service is accumulated. This commonly includes wear of 

valves, valve seats, and piston rings, all of which reduce in-cylinder pressure. Oil control 

seals and gaskets also deteriorate with age, leading to higher lubricating oil consumption. 

Additionally, flow properties of EGR systems may change as deposits accumulate and 

therefore alter the mass of EGR inducted into the combustion chamber. These factors, 

amongst others, may serve to reduce power, increase fuel consumption, and change 

combustion properties; all of which affect pollutant emissions.

For engines equipped with aftertreatment devices, DFs take into account engine 

deterioration, as described above, in addition to aging affects on the aftertreatment 

devices. Oxidation catalysts and other catalytic devices rely on active precious metals to 

effectively convert and reduce harmful pollutants. These metals may become less active 

with age and therefore pollutant conversion efficiencies may decrease. Particulate filters 

may also experience reduced trapping efficiency with age due to ash accumulation and/or 

degradation of the filter substrate, which may lead to higher tailpipe PM measurements 

and/or increased regeneration frequency. If a pollutant is predominantly controlled by
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aftertreatment, deterioration of emission control depends on the continued operation of 

the aftertreatment device much more so than on consistent engine-out emissions. 

At this time, we anticipate that most engine component wear will not have a 

significant negative impact on CO2 emissions. However, wear and aging of aftertreatment 

devices may or may not have a significant negative impact on CO2 emissions. In 

addition, future engine or aftertreatment technologies may experience significant 

deterioration in CO2 emissions performance over the useful life of the engine. For these 

reasons, we believe that the use of DFs for CO2 emissions is both appropriate and 

necessary. As with criteria pollutant emissions, these DFs are preferably developed 

through testing the engine over a representative duty cycle for an extended period of 

time. This is typically either half or full useful life, depending on the regulatory category. 

The DFs are then calculated by comparing the high-hour to low-hour emission levels, 

either by division or subtraction (for multiplicative & additive DFs, respectively). 

This testing process may be a significant cost to an engine manufacturer, mainly

due to the amount of time and resources required to run the engine out to half or full 

useful life. For this reason, durability testing for the determination of DFs is not 

commonly repeated from model year to model year. In addition, some DFs may be 

allowed to carry over between families sharing a common architecture and aftertreatment 

system. EPA prefers to have manufacturers develop testing-based DFs for their products. 

However, we do understand that for the reasons stated above, it may be impractical to 

expect manufacturers to have testing-based deterioration factors available for these final 

rules. Therefore, we are allowing manufacturers to use EPA-assigned DFs for CO2. 

However, we also understand that CO2 is traditionally measured as part of normal engine 

dynamometer testing. Therefore, we are requiring that manufacturers include CO2 data 

over their criteria pollutant durability demonstrations (if available), which will aid the 

agency in developing more accurate assigned DFs. This action is being taken in the 

context of engine manufacturers’ concerns regarding the impact of deterioration of 

emissions components relative to the GHG standards. Engine manufacturers commented 

that there would be no deterioration of components used to reduce GHG emissions in 

Phase 1. As part of the Clean Air Act responsibility to demonstrate compliance 

throughout the useful life, manufacturer will need to provide data already collected 

during traditional criteria pollutant testing for full useful life performance. 

IRAFs/Regeneration Impacts on CO2

Heavy-duty engines may be equipped with exhaust aftertreatment devices which 

require periodic “regeneration” to return the device to a nominal state. A common 

example is a diesel particulate filter, which accumulates PM as the engine is operated. 

When the PM accumulation reaches a threshold such that exhaust backpressure is 

significantly increased, exhaust temperature is actively increased to oxidize the stored 

PM. The increase in exhaust temperature is commonly facilitated through late 

combustion phasing and/or raw fuel injection into the exhaust system upstream of the 

filter. Both methods impact emissions and therefore must be accounted for at the time of 

certification. In accordance with §86.004-28(i), this type of event would be considered 

infrequent because in most cases they only occur once every 30 to 50 hours of engine 
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operation (rather than once per transient test cycle), and therefore adjustment factors must 

be applied at certification to account for these effects.

Similar to DFs, these adjustment factors are based off of manufacturer testing; 

however this testing is far less time consuming. Emission results are measured from two

test cycles: with and without regeneration occurring. The differences in emission results 

are used, along with the frequency at which regeneration is expected to occur, to develop 

upward and downward adjustment factors. Upward adjustment factors are added to all 

emission results derived from a test cycle in which regeneration did not occur. Similarly, 

downward adjustment factors are subtracted from results based on a cycle which did 

experience a regeneration event. Each pollutant will have a unique set of adjustment 

factors and additionally, separate factors are commonly developed for transient and 

steady-state test cycles.

The impact of regeneration events on criteria pollutants varies by pollutant and 

the aftertreatment device(s) used. In general, the adjustment factor can have a very

significant impact on compliance with the NOX standard. For this reason, heavy-duty 

vehicle and engine manufacturers are already very well motivated to extend the 

regeneration frequency to as long an interval as possible and to reduce the duration of the 

regeneration as much as possible. Both of these actions significantly reduce the impact 

of regeneration on CO2 emissions and fuel consumption. We do not believe that adding 

an adjustment factor for infrequent regeneration to the CO2 or fuel efficiency standards 

would provide a significant additional motivation for manufacturers to reduce 

regenerations. Moreover, doing so would add significant and unnecessary uncertainty to 

our projections of CO2 and fuel consumption performance in 2014 and beyond. In 

addressing that uncertainty, the agencies would have to set less stringent fuel efficiency

and CO2 standards for heavy-duty trucks and engines. Therefore, we are not requiring 

the use of infrequent regeneration adjustment factors for CO2 or fuel efficiency in this 

program. This is consistent with comments received from engine manufacturers. 

Auxiliary Emission Control Devices

As part of the engine control strategy, there may be devices or algorithms which 

reduce the effectiveness of emission control systems under certain limited circumstances. 

These strategies are referred to as Auxiliary Emission Control Devices (AECDs). One 

example would be the reduced use of EGR during cold engine operation. In this case, low 

coolant temperatures may cause the electronic control unit to reduce EGR flow to 

improve combustion stability. Once the engine warms up, normal EGR rates are resumed 

and full NOX control is achieved. 

At the time of certification, manufacturers are required to disclose all AECDs and 

provide a full explanation of when the AECD is active, which sensor inputs effect AECD 

activation, and what aspect of the emission control system is affected by the AECD. 

Manufacturers are further required to attest that their AECDs are not “defeat-devices,” 

which are intentionally targeted at reducing emission control effectiveness. 
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Several common AECDs disclosed for criteria pollutant certification will have a 

similarly negative influence on GHG emissions as well. One such example is cold-start 

enrichment, with provides additional fueling to stabilize combustion shortly after initially

starting the engine. From a criteria pollutant perspective, HC emissions can reasonably 

be expected to increase as a result. From a GHG perspective, the extra fuel does not result 

in a similar increase in power output and therefore the efficiency of the engine is reduced, 

which has a negative impact on CO2 emissions. In addition, there may be AECDs that 

uniquely reduce GHG emission control effectiveness. Therefore, consistent with today’s 

certification procedures, we are finalizing that a comprehensive list of AECDs covering 

both criteria pollutant, as well as GHG emissions is required at the time of certification. 

(ii) EPA’s N2O and CH4 Standards

In 2009, EPA issued rules requiring manufacturers of mobile-source engines to 

report the emissions of CO2, N2O, and CH4 (74 FR 56260, October 30, 2009). Although 

CO2 is commonly measured during certification testing, CH4 and N2O are not. CH4 has 

traditionally not been included in criteria pollutant regulations because it is a relatively 

stable molecule and does not contribute significantly to ground-level ozone formation. In 

addition, N2O is commonly a byproduct of lean-NOX aftertreatment systems. Until 

recently, these types of systems were not widely used on heavy-duty engines and 

therefore N2O emissions were insignificant. As noted in section II above, both species, 

while emitted in small quantities relative to CO2, have much higher global warming 

potential than CO2 and therefore must be considered as part of a comprehensive GHG 

regulation.

EPA is requiring that CH4 and N2O be reported at the time of certification, 

however we will allow manufacturers to submit a compliance statement based on good 

engineering judgment for the first year of the program in lieu of direct measurement of 

N2O. However, beginning in the 2015 model year, the agency is requiring the direct 

measurement of N2O for certification. The intent of the CH4 and N2O standards are more 

focused on prevention of future increases in these compounds, rather than forcing 

technologies that reduce these pollutants. As one example, we envision manufacturers 

satisfying this requirement by continuing to use catalyst designs and formulations that 

appropriately control N2O emissions rather than pursuing a catalyst that may increase 

N2O. In many ways this becomes a design-based criterion in that the decision of one 

catalyst over another will effectively determine compliance with N2O standards over the 

useful life of the engine. As discussed above, in cases where N2O emissions directly

tradeoff with CO2 emissions, EPA is allowing manufacturers to exploit this relationship 

to produce engines with the lowest overall GHG emissions. Direct measurement of N2O

emissions is required in the case of engines utilizing this temporary credit program.

Since catalytic activity generally changes with age and service accumulation, it is 

not unreasonable to expect changes in N2O and CH4 emissions over the useful life of the 

engine. We also believe that low-hour test results coupled with deterioration factors 

provides an adequate representation of end-of-life emission levels for these pollutants. 

However, the requirement to measure N2O and CH4 during testing is relatively new and 

we do not expect that manufacturers have consistent durability data to formulate 
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deterioration factors for today’s action. We also do not believe it is appropriate to require 

all new durability testing to satisfy this requirement, as this would result in a nontrivial 

burden to engine manufacturers. Instead we will be assigning deterioration factors for 

N2O and CH4 for this action. If the use of assigned deterioration factors jeopardizes 

compliance with the emission standards, we will also allow manufacturers to propose 

unique testing-based deterioration factors for these pollutants. In response to comments 

received from engine manufacturers regarding the timing needed to generate deterioration 

factors the agencies are taking this approach. 

Concerns had also been raised by engine manufacturers regarding measurement 

techniques for quantifying N2O emissions. In an effort to expand testing options, we are 

adding an allowance to use laser infrared analyzers for N2O measurement in 40 CFR part 

1065.275. This is to reflect the recent development of this technology for N2O 

measurement. We would also like to serve notice that in an upcoming rulemaking, we 

will be tightening the interference tolerance (both positive and negative) for engines and 

vehicles that are required to certify to an N2O standard. This will consist of an 

interference limit based on interference as a percentage of the flow weighted mean 

concentration of N2O expected at the standard. For example we may set the interference 

limit at ±10 % of the flow weighted mean concentration of N2O expected at the standard 

and strongly recommend a lower interference that is within ±5 %.

(c) Additional Compliance Provisions

(i) Warranty & Defect Reporting

Under section 207 of the CAA, engine manufacturers are required to warrant that 

their product is free from defects that would cause the engine to not comply with 

emission standards. This warranty must be applicable from when the engine is 

introduced into commerce through a period generally defined as half of the regulatory

useful life (specified in hours and years, whichever comes first). The exact time of this 

warranty is dependent on the regulatory category of the engine. In addition, components 

that are considered “high cost” are required to have an extended warranty. Examples of 

such components would be exhaust aftertreatment devices and electronic control units.

Current warranty provisions in 40 CFR part 86 define the warranty periods and 

covered components for heavy-duty engines. The current list of components is comprised 

of any device or system whose failure would result in an increase in criteria pollutant 

emissions. We remain convinced that this list is adequate for addressing GHG emissions 

as well, based on comments received from the proposed rules. The following list 

identifies items commonly defined as critical emission-related components:

 Electronic control units

 Aftertreatment devices

 Fuel metering components

 EGR-System components

 Crankcase-ventilation valves
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 All components related to charge-air compression and cooling

 All sensors and actuators associated with any of these components

When a manufacturer experiences an elevated rate of failure of an emission 

control device, they are required to submit defect reports to the EPA. These reports will 

generally have an explanation of what is failing, the rate of failure, and any possible 

corrections taken by the manufacturer. Based on how successful EPA believes the 

manufacturer to be in addressing these failures, the manufacturer may need to conduct a 

product recall. In such an instance, the manufacturer is responsible for contacting all 

customers with affected units and repairing the defect at no cost to them. We believe this 

structure for the reporting of criteria pollutant defects, and recalls, is appropriate for 

components related to complying with GHG emissions as well. 

(ii) Maintenance

Engine manufacturers are required to outline maintenance schedules that ensure 

their product will remain in compliance with emission standards throughout the useful 

life of the engine. This schedule is required to be submitted as part of the application for 

certification. Maintenance that is deemed to be critical to ensuring compliance with 

emission standards is classified as “critical emission-related maintenance.” Generally, 

manufacturers are discouraged from specifying that critical emission-related maintenance 

is needed within the regulatory useful life of the engine. However, if such maintenance is 

unavoidable, manufacturers must have a reasonable basis for ensuring it is performed at 

the correct time. This may demonstrated through several methods including survey data 

indicating that at least 80% of engines receive the required maintenance in-use or 

manufacturers may provide the maintenance at no charge to the user. During durability

testing of the engine, manufacturers are required to follow their specified maintenance 

schedule.

Maintenance relating to components relating to reduction of GHG emissions is

not expected to present unique challenges. Therefore, we are not finalizing any changes 

to the provisions for the specification of emission-related maintenance as outlined in 40 

CFR part 86.

(2) Enforcement Provisions

(a) Emission Control Information Labels

Current provisions for engine certification require manufacturers to equip their 

product with permanent emission control information labels. These labels list important 

characteristics, parameters, and specifications related to the emissions performance of the 

engine. These include, but are not limited to, the manufacturer, model, displacement, 

emission control systems, and tune-up specifications. In addition, this label also provides 

a means for identifying the engine family name, which can then be referenced back to 

certification documents. This label provides essential information for field inspectors to 

determine that an engine is in fact in the certified configuration.
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We do not anticipate any major changes needing to be made to emission control 

information labels as a result of new GHG standards and a single label is appropriate for 

both criteria pollutant and GHG emissions purposes. Perhaps the most significant 

addition will be the inclusion of Family Certification Levels or Family Emission Limits 

for GHG pollutants, if the manufacturer is participating in averaging, banking, and 

trading. In addition, the label will need to indicate whether the engine is certified for use 

in vocational vehicles, tractors, or both. Finally, if an engine family is uniquely certified 

for use in hybrid powertrain applications, a compliance statement indicating this will 

need to be included on the emission control label.

In response to comments from engine and truck manufacturers that tractors should 

be allowed to obtain engines certified for vocational use and likewise a limited number of 

engines certified for tractor use should be available for the appropriate vocational 

applications, the agencies are allowing limited use of engines certified in other categories. 

To address compliance needs and to discourage abuse of the provisions, proper labeling 

of the engines is essential. 

(b) In-Use Standards

In-use testing of engines provides a number of benefits for ensuring useful life 

compliance. In addition to verifying compliance with emission standards at any given 

point in the useful life, it can be used along with manufacturer defect reporting, to 

indentify components failing at a higher than normal rate. In this case, a product recall or 

other service campaign can be initiated and the problem can be rectified. Another key

benefit of in-use testing is the discouragement of control strategies catered to the 

certification test cycles. In the past, engine manufacturers were found to be producing 

engines that performed acceptably over the certification test cycle, while changing to 

alternate operating strategies “off-cycle” which caused increases in criteria pollutant 

emissions. While these strategies are clearly considered defeat devices, in-use testing 

provides a meaningful way of ensuring that such strategies are not active under normal 

engine operation.

Currently, manufacturers of certified heavy-duty engines are required to conduct 

in-use testing programs. The intent of these programs is to ensure that their products are 

continuing to meet criteria pollutant emission standards at various points within the 

useful life of the engine. Since initial certification is based on engine dynamometer 

testing, and removing in-use engines from their respective vehicles is often impractical, a 

unique testing procedure was developed. This includes using portable emission 

measurement systems (PEMS) and testing the engine over typical in-situ drive routes 

rather than a prescribed test cycle. To assess compliance, emission results from a well 

defined area of the speed/torque map of the engine, known as the NTE zone, are 

compared to the emission standards. To account for potential increases in measurement 

and operational variability, certain allowances are applied to the standard which results in 

the standard for NTE measurements (NTE limit) to be at or above the duty cycle 

emission standards.
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In addition, EPA conducts an annual in-use testing program of heavy-duty 

engines. Testing procured vehicles with specific engines over well-defined drive routes 

using a constant trailer load allows for a consistent comparison of in-use emissions 

performance. If potential problems are identified in-situ, the engine may be removed 

from the vehicle and tested using an engine dynamometer over the certification test 

cycles. If deficiencies are confirmed the agency will either work with the manufacturer to 

take corrective action, possibly involving a product recall, or proceed with enforcement 

action against the manufacturer.

The GHG reporting rule requires manufacturers to submit CO2 data from all 

engine testing (beginning in the 2011 model year), which we believe is equally applicable 

to in-use measurements. Methods of CO2 in-situ measurement are well established and 

most, if not all, PEMS devices measure and record CO2 along with criteria pollutants. 

CH4 and N2O present in-situ measurement challenges that may be impractical to 

overcome for this testing, and therefore they are not included in in-use testing 

requirements at this time. While measurement of CO2 may be practical and important, 

implementing an NTE emission standard for CO2 is challenging. As previously

discussed, CO2 emissions are highly dependent on the drive cycle of the vehicle, which 

does not lend itself well to the NTE-based test procedure. Therefore, we proposed and are 

adopting that manufacturers be required to submit CO2 data from in-situ testing, in both 

g/bhp-hr and g/ton-mile, but these data will be used for reference purposes only (there 

would be no NTE limit/standard for CO2). For the purposes of calculating the g/ton-mile 

metric, we prefer that manufacturers use the measured vehicle weight. However it has 

been brought to our attention that this may not always be available, in which case an 

estimated vehicle weight can be used along with a written justification for the basis of the 

estimation. For engine-based (dynamometer) in-use testing, compliance with CO2

emission standards will be judged off of the FCL of the engine family.

(3) Other Certification Provisions

(a) Carryover/Carry Across Certification Test Data

EPA’s current certification program for heavy-duty engines allows manufacturers 

to carry certification test data over and across certification testing from one model year to 

the next, when no significant changes to models are made. EPA will also apply this 

policy to CO2, N2O and CH4 certification test data. 

(b) Certification Fees

The CAA allows EPA to collect fees to cover the costs of issuing certificates of 

conformity for the classes of engines covered by this rulemaking. On May 11, 2004, EPA 

updated its fees regulation based on a study of the costs associated with its motor vehicle 

and engine compliance program (69 FR 51402). At the time that cost study was

conducted, the current rulemaking was not considered. At this time the extent of any

added costs to EPA as a result of this program is not known. EPA will assess its

compliance testing and other activities associated with the rules and may amend its fees 

regulations in the future to include any justifiable new costs.
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(c) Onboard Diagnostics

(a) Onboard Diagnostics

Beginning with the 2010 model year, manufacturers have been phasing in onboard diagnostic (OBD) systems on heavy-duty engines pursuant to the heavy-duty OBD 

rulemaking finalized by the EPA in 2009.313 These systems monitor the activity of the 

emission control system and issue alerts when faults are detected. These diagnostic 

systems are currently being developed based around components and systems that 

influence criteria pollutant emissions. Consistent with the light-duty 2012-2016 MY 

vehicle rulemaking, we believe that monitoring of these components and systems for 

criteria pollutant emissions will have an equally beneficial effect on CO2 emissions.314 

Therefore, we have not finalized any additional unique onboard diagnostic provisions for 

heavy-duty GHG emissions. In the NPRM, EPA did not propose new or different 

diagnostic requirements from those finalized in the 2009 heavy-duty OBD rule.

The agencies received comments from engine manufacturers, hybrid system 

manufacturers, and related trade groups which broached concerns regarding the 

feasibility of applying on-board diagnostics to hybrid applications starting in 2013. The 

commenters stated that engine manufacturers would need several years to adapt their 

engine OBD systems to hybrids, and therefore requested a delay of OBD requirements 

for hybrid applications until 2020 with a phase-in of enforcement liability starting that 

same year. Details, which the agencies believe have merit, are set out below. In response, 

EPA is taking an approach that is consistent with certain provisions of the existing final 

action for heavy-duty OBD, finalized in 2009. To that end, manufacturers who certify 

hybrid systems will continue to have the responsibility of implementing compliant 

diagnostic systems, however, we are extending the OBD phase-in for engines with hybrid 

systems to allow time for manufacturers to be able to address communication protocol 

development concerns (e.g. SAE J1939, communication with diagnostic scantools), 

component development concerns (e.g. hardware and software), and to address the 

availability of heavy-duty OBD compliant engines with sufficient lead-time for additional 

hybrid diagnostic system development given resource constraints as engine 

manufacturers are focused on meeting the 2013 requirements for conventional products at 

this time.

Since publication of the NPRM, the EPA has undertaken extensive outreach to 

hybrid manufacturers, engine manufacturers, and related industry groups to further 

understand the technical issues involved with the implementation of full OBD on enginehybrid systems.315

 Hybrid manufacturers have indicated that the interaction between 

 

313 U.S. EPA, “Control of Air Pollution from New Motor Vehicles and New Motor Vehicles Engines; Final 

Rule Regulations Requiring Onboard Diagnostic Systems on 2010 and Later Heavy-Duty Engines Used in 

Highway Applications Over 14,000 Pounds; Revisions to Onboard Diagnostic Requirements for Diesel 

Highway Heavy-Duty Vehicles Under 14,000 Pounds,” published February 24, 2009. Available here: 

http://www.epa.gov/otaq/regs/im/obd/regtech/hd-obd-frm-02-24-09-notice-74-fr-8310.pdf

314 See the Light-Duty 2012-2016 Vehicle Rule, Note 5, above.

315

 See EPA Docket EPA-HQ-OAR-2010-0162 for memos describing meetings held as a part of this 

outreach.
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hybrid systems and OBD compliant engines is not well understood at this time, for 

example, if the system shuts down the vehicle at idle (as is common), the OBD idle 

diagnostics cannot run. In addition, there are many different hybrid systems being 

developed which make much of this technology both immature and low volume, and 

engine manufacturers are concerned that this will result in high costs due to frequent 

design changes that could occur as this technology develops and have asked for 

flexibility for unique hybrid applications. Consistent with the goal to incentivize the 

development of hybrid designs (systems designed to capture wasted energy and reduce 

fuel consumption) the EPA is allowing hybrid manufacturers time to develop their 

systems while simultaneously developing the capability to meet HD OBD requirements.

Communication protocol development is an integral part of developing hybrid 

OBD capability for the heavy-duty industry which is not vertically integrated. There are 

different protocols required to be used for OBD communication in a vehicle depending 

on the type of engine (gasoline or diesel). These protocols are developed in part to 

standardize the transmission of electronic signals and control information among vehicle 

components. The J1939 communication protocol is developed by committee through 

SAE and is required for use with diesel engines. J1939 defines communications 

messages, diagnostic messages for communications between a module and diagnostic 

scantool, and fault codes. Messages sent through a J1939 network contain a series of 

information (e.g. an identifier, message priority, data, etc.) and these parameters must be 

agreed upon through the SAE committee and tailored to work for all manufacturers. The 

development of this communication protocol includes developing criteria for the 

messages, and determining a single set of fault codes that can work for all manufacturers 

and all hybrid system configurations; this is expected to take a substantial amount of time 

and collaboration. OBD cannot exist without fault codes to report, therefore development 

of this protocol is critical. Hybrid manufacturers have stated that until such time as a 

‘plug and play scheme’ is available, hybrid volumes will not be able to increase 

significantly. At this time, there are only a few such messages that have been developed 

for use in hybrid systems, and there is much additional development that needs to take 

place. The type of messages needed must first be identified once 2013 HD OBD 

compliant engines are available for use in HD hybrid OBD system development. After 

needed messages are identified, the content of each message must be developed and 

agreed upon through a ballot process. Manufacturers have stated that this will be an 

iterative process and will likely take at least two years to develop the protocol for use 

with different variations of hybrid systems and architectures, different types of energy

storage systems, and for systems used in the wide variety of applications in the heavyduty market, and we agree with this assessment. While a level of communication exists 

today between engines and transmissions for this industry, the level of control and impact 

on engine system operation becomes much more significant once hybrid technology is 

introduced. The purpose of the hybrid energy system is to supplement overall vehicle 

power demands. As such, the methods used for integrating the energy from the hybrid 

system into overall vehicle operation vary from allowing additional internal combustion 

engine lower power operation to potentially decreasing the amount of engine “on” time. 

This range of performance impacts will serve to reduce GHG emissions by reducing 

demands on the engine. Conventional transmission systems and other powertrain 

components do not exercise the level of control the hybrid will need to exercise to 
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effectively reduce GHG emissions and improve fuel consumption performance for 

internal combustion engines; therefore, hybrid OBD systems can reasonably be expected 

to be more complicated as well.

Component development concerns raised by hybrid manufacturers include both 

changes that may be required to software and/or hardware systems on both existing 

hybrid products and on hybrid systems currently under development. Software systems 

in existing products have been developed that provide proprietary diagnostic capability

(as no standardized system such as J1939 had been developed for these systems), 

however, these software systems are not OBD complaint. These products will likely

require entirely new software systems developed for them which may result in hardware 

changes as well. Manufacturers have stated that a complete software system can take up 

to 2 years to develop and validate. Hardware may also need to be changed to 

accommodate OBD on hybrid systems. In particular, hardware changes would affect 

current production systems which may not have controllers that can support full OBD. 

The low volume sales and high cost of a controller program (which can reach into the 

millions of dollars) means that most companies cannot justify the cost of a hardware 

change for hybrids alone, rather, existing hybrid systems will have to wait until such a 

hardware upgrade is planned for other reasons. In addition, new hardware programs, 

such as developing a new ECU can take 3-4 years to complete. While it is possible for 

some of this work to be done concurrently, how much can be done this way is dependent 

on the configuration of each individual system. Finally, manufacturers may have 

contractual agreements with hardware and software suppliers that will have to be 

reconfigured to address a complete OBD program.

Hybrid manufacturers have stated that they will be unable to produce hybrid 

systems that will be OBD complaint in 2013. Given the concerns discussed above and 

the general lack of availability of OBD compliant engines until the completion of the HD 

OBD phase-in, to require manufacturers of systems that depend on the availability of 

those OBD compliant engines to then be able to immediately implement additional 

requirements may be impractical or infeasible in many instances. Given the phase-in of 

HD OBD requirements that already exists however, we do not believe a delay to 2019 or 

2020 is warranted. While not all of the engines that would potentially have hybrid 

systems incorporated into their design are available in their final OBD configuration at 

the time of this action, it is clear that some engine systems will be available. 

Additionally, there is an expectation that engine manufacturers, their suppliers and 

customers will have to continue to work cooperatively to deliver products for the market. 

This cooperation must include a level of concurrent engineering prior to products being 

brought to market. At this time we believe a delay to 2016 for the phase-in of OBD for 

heavy-duty engines equipped with hybrid systems should provide the requisite lead time 

from the date of this action to the date of implementation for development of components 

and protocols necessary for successful integration of complete OBD systems for engines 

equipped with hybrid systems. 

Manufacturers will be required to implement feasible controls for these hybrid 

systems that do not adversely impact emissions performance in 2013 and by 2016-17, all 

systems must be fully compliant with OBD requirements. The phase in period takes into 
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account that current production systems are likely to be smaller in terms of sales volumes 

than newly developed systems, and may require more hardware and software 

development as some of these systems have been in production for nearly a decade and 

have developed a proprietary system diagnostic capability that does not meet OBD 

requirements. Therefore, this extended phase-in provides them an additional year of time 

to comply with the heavy-duty OBD regulations. Hybrid systems put into production 

after January 1, 2013 will be required to meet the 2009 heavy-duty OBD requirements in 

2016 consistent with the next phase-in date for heavy-duty OBD, while those hybrid 

systems released prior to January 1, 2013 have until 2017 to be compliant with these 

OBD requirements. 

If a manufacturer certifies an engine-hybrid system with CARB OBD in 

California prior to the required phase-in date (2016 or 2017), and its diagnostics meet or 

exceed the requirements for full 2013 OBD, the manufacturer must either use the CARB 

certified package for Federal release or phase in the package and certify it with full EPA 

OBD. 

In the interim, engine system diagnostics must show that they meet or exceed 

CARB’s Engine Manufacturer Diagnostic Systems Requirements (EMD) including 

system monitoring requirements for NOX aftertreatment, fuel systems, exhaust gas 

recirculation, particulate matter traps, and emission-related electronic components.316 

Specific EMD requirements will be considered met if they are redundant due to the 

installed engine's fully functioning OBD content. Most manufacturers have already

certified their engines with EMD for the 2011 model year, and full OBD as required in 

2013 exceeds EMD requirements, therefore no new cost burden is expected as a result of 

this provision. In addition, new engines may be introduced in 2013 for hybrid-only use 

and, in lieu of meeting full OBD, meeting EMD would result in cost savings because of 

the flexibility in scan-tool reporting and diagnostic content. 

In addition, the engine-hybrid system must maintain existing OBD capability for 

engines where the same or equivalent engine (e.g. displacement) has been OBD certified. 

An equivalent engine is one produced by the same engine manufacturer with the same 

fundamental design, but that may have no more than minor hardware or calibration 

differences, such as slightly different displacement, rated power, or fuel system. Though 

the OBD capability must be maintained, it does not have to meet detection thresholds and 

in-use performance frequency requirements; for example, a manufacturer may modify

detection thresholds to prevent false detection.

As stated earlier, existing hybrid systems sold today have proprietary diagnostic 

capability that is non-OBD compliant, but nonetheless will notify the driver of potential 

problems with the system. Hybrid manufacturers must also continue to maintain this 

existing diagnostic capability to ensure proper function consistent with the performance 

for which the hybrid system is certified as well as, safe operation of the hybrid system.

 

316 California Air Resources Board, Final Regulation Order for EMD, Section 1971 of Title 13, California 

Code of Regulations, effective December 30, 2004. Available here; 

http://www.arb.ca.gov/regact/emd2004/fro.pdf
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Finally, during the interim part of the phase-in, manufacturers that are not fullyOBD compliant must also submit an annual pre-compliance report to the EPA for model 

years 2013 and later. The engine manufacturers must submit this report with their engine 

certification information. Hybrid manufacturers that are not certifying the engine-hybrid 

systems must also submit an annual pre-compliance report to the EPA. The report must 

include a description of the engine-hybrid system being certified and related product 

plans, information as to activities undertaken and progress made by the manufacturer in 

achieving full OBD certification including monitoring, diagnostics, and standardization; 

and deviations from an originally certified full-OBD package with engineering 

justification.

(d) Applicability of Current High Altitude Provisions to Greenhouse Gases

EPA is requiring that engines covered by this program must meet CO2, N2O and 

CH4 standards at elevated altitudes. The CAA requires emission standards under section 

202 for heavy-duty engines to apply at all altitudes. EPA does not expect engine CO2, 

CH4, or N2O emissions to be significantly different at high altitudes based on engine

calibrations commonly used at all altitudes. Therefore, EPA will retain its current high 

altitude regulations so manufacturers will not normally be required to submit engine CO2

test data for high altitude. Instead, they will be required to submit an engineering 

evaluation indicating that common calibration approaches will be utilized at high altitude. 

Any deviation in emission control practices employed only at altitude will need to be 

included in the AECD descriptions submitted by manufacturers at certification. In 

addition, any AECD specific to high altitude will be required to include emissions data to 

allow EPA to evaluate and quantify any emission impact and validity of the AECD.

(e) Emission-Related Installation Instructions

Engine manufacturers are currently required to provide detailed installation 

instructions to vehicle manufacturers. These instructions outline how to properly install 

the engine, aftertreatment, and other supporting systems, such that the engine will operate 

in its certified configuration. At the time of certification, manufacturers may be required 

to submit these instructions to EPA to verify that sufficient detail has been provided to 

the vehicle manufacturer. 

We do not anticipate any major changes to this documentation as a result of 

regulating GHG emissions. The most significant impact will be the addition of language 

prohibiting vehicle manufacturers from installing engines into vehicle categories in which 

they are not certified for. An example would be a tractor manufacturer installing an 

engine certified for only vocational vehicle use. Explicit instructions on behalf of the 

engine manufacturer that such acts are prohibited will serve as sufficient notice to the 

vehicle manufacturers and failure to follow such instructions will in the vehicle 

manufacturer being in non-compliance.
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(f) Alternate CO2 Emission and Fuel Consumption Standards

Under the final rules, engine manufacturers have the option of certifying to 

alternate CO2 emission and fuel consumption standards for model years 2014 through 

2016. These alternate standards are defined as a certain percentage below a baseline 

value established from their corresponding 2011 model-year products. For instance, the 

alternate emission standard for light and medium heavy duty FTP-certified (vocational) 

engines is equal to 0.975 times the baseline value. If a manufacturer elects to participate 

in this program it must indicate this on its certification application. In addition, sufficient 

details must be submitted regarding the baseline engine such that the agency can verify

that the correct optional CO2 emission and fuel consumption standards have been 

calculated. These data will need to include the engine family name of the baseline 

engine, so references to the original certification application can be made, as well as test 

data showing the CO2 emissions and fuel consumption of the baseline engine.

(4) Compliance Reports

(a) Early Model Year Data

NHTSA’s regulatory text in the NPRM included specifications for manufacturers 

to submit pre-certification compliance reports for heavy-duty engines. The precertification reports included requirements for manufactures to submit information to 

identify the types of engines, expected test results, production volumes and credits. The 

reporting requirements were general in nature despite there being an existing emissions 

program for heavy-duty engines. The existing ABT program for NOX and PM emissions 

for heavy-duty engines has existed since 2001 (see 66 FR 5002 signed on January 18, 

2001) but does not require reporting early model year compliance information. The 

agencies sought comments on the report provisions in the NPRM but commenters failed 

to offer recommendations on what content should be required. As a result, the agencies 

have decided to eliminate the pre-certification report because engine manufacturers have 

no experience in providing GHG information and the proposed information may not be 

available until subsequent model years. For the next phase of this GHG program, the 

agencies may adopt a pre-model year report for engines. 

As an alternative to receiving early compliance model year information in the 

precertification reports, the agencies have decided to use manufacturer’s application for 

certificates of conformity to obtain early model estimates. Currently, the applications for 

certificates are not required to include the fuel consumption information required by

NHTSA. Therefore, the agencies are adopting provisions in the final rules for 

manufacturers to provide emission and equivalent fuel consumption estimates in the 

manufacturer’s applications for certification. The agencies will treat information 

submitted in the applications as a manufacturer’s demonstration of providing early 

compliance information, similar to the pre-model year report submitted for heavy-duty 

pick trucks and vans. The final rules establish a harmonized approach by which 

manufacturers will submit applications through the EPA Verify database system as the 

single point of entry for all information required for this national program and both 

agencies will have access to the information. If by model year 2012, the agencies are not 
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prepared to receive information through the EPA Verify database system, manufacturers 

are expected to submit written applications to the agencies. This approach should 

streamline this process and reduce industry burden and provide sufficient information for 

the agencies to carry out their early compliance activities. 

(b) Final Reports

For engines, the agencies proposed that manufacturers would submit EOY reports 

and final reports. An EOY report for manufacturers using the ABT program was

required to be submitted no later than 90 days after the calendar year and final report no 

later than 270 days after the calendar year.317 Manufacturers not participating in the ABT 

program were required to provide an EOY report within 45 days after the calendar year 

but no final reports were required. The final ABT report due date was established 

coinciding with EPA’s existing criteria pollutant report for heavy-duty engines

complying with NOX and PM standards. Similar to that program, the proposed EOY and 

final reports required receiving engine type designation, engine family and credit plans 

for engine manufacturers. 

There were no comments received on the final reports for engines. For the final 

rules, the agencies will retain the provisions as proposed for the EOY and final reports. 

However, the agencies will consolidate the reporting as done for other vehicle categories

and will require emissions and equivalent fuel consumption information to be submitted 

to EPA. The final rules establish a harmonized approach by which manufacturers will 

submit applications to EPA as the single point of entry for all information required for 

this national program and both agencies will have access to the appropriate information. 

If by model year 2012, the agencies are not prepared to receive information through a 

database system, manufacturers are expected to submit written applications to the 

agencies. The agencies are also combining the EOY reports for manufacturers not using 

ABT to provide a product volume report due 90 days after the end of the model year and

the ABT report required 90 days after the model year. A summary of the required 

information in the final rules for EOY and final reports is as follows: 

 Engine family designation and averaging set.

 Engine emissions and fuel consumption standards including any alternative 

standards used

 Engine family FCLs.

 Final production volumes

 Certified test cycles

 Useful life values for engine families

 A credit plan identifying the manufacturers actual credit balances, credit 

flexibilities, credit trades and a credit deficit plan if needed demonstrating how it 

plans to resolve any credit deficits that might occur for a model year within a 

period of up to three model years after that deficit has occurred 

 

317 Corresponding to the compliance model year
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(c) Additional Required Information

Throughout the model year, manufacturers may be required to submit various 

reports to the agencies to comply with various aspects of the program. These reports

have differing criteria for submission and approval. 

Table V-1 below provides a summary of the types of submission, required 

submission dates and the EPA and NHTSA regulations that apply for engines and engine 

manufacturers. 

The agencies will review and grant any appropriate requests considering the 

timeliness of the submissions and the completeness of the requests. 
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Table V-1: Summary of Required Information for HD Engine Compliance

Submission Applies to Required Submissions 

Date

EPA 

Regulation 

Reference

NHTSA 

Regulation 

Reference

Small 

business 

exemptions

Engine manufacturers 

meeting the Small Business 

Administration (SBA) size 

criteria of a small business as 

described in 13 CFR 121.201.

Before introducing any 

excluded vehicle into 

U.S. for commerce

§1036.150 §535.8

Incentives 

for early

introduction

The provisions apply with 

respect to tractors and 

vocational vehicles produced 

in model years before 2014

EPA must be notified 

before the manufacturer 

submits it applications 

for certificates of 

conformity

§1036.150 §535.8

Voluntary

compliance 

for NHTSA 

standards

Engine manufacturers 

seeking early compliance in 

model years 2014 to 2016.

NHSAT must be 

notified before the 

manufacturer submits it 

applications for 

certificates of 

conformity

NA §535.8

Model year 

2014 N2O 

standards. 

Manufacturers that choose to 

show compliance with the 

MY 2014 N2O standards 

requesting to use an 

engineering analysis

EPA must be notified 

before the manufacturer 

submits it applications 

for certificates of 

conformity

§1036.150 NA

Exemption 

from EOY 

reports

Manufactures with surplus 

credits at the end of the 

model year

90-days after the 

calendar year ends

§1036.730 §535.8

Alternative 

engine 

standards

Engine manufacturers not 

able to comply with 1036.104 

and wanting to use the 

alternative engine standard.

EPA and NHTSA must 

be notified before the 

manufacturer submits it 

applications for 

certificates of 

conformity

§1036.150 §535.8

Alternate 

phase-in

Engine manufacturers want 

to comply with alternate

phase in standards.

EPA and NHTSA must 

be notified before the 

manufacturer submits it 

applications for 

certificates of 

conformity

§1036.150 §535.8
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D. Class 7 and 8 Combination Tractors

(1) Compliance Approach

In addition to requiring engine manufacturers to certify their engines, 

manufacturers of Class 7 and 8 combination tractors must also certify that their vehicles 

meet the CO2 emission and fuel consumption standards. This vehicle certification will 

ensure that efforts beyond just engine efficiency improvements are undertaken to reduce 

GHG emissions and fuel consumption. Some examples include aerodynamic 

improvements, rolling resistance reduction, idle reduction technologies, and vehicle 

speed limiting systems. 

Unlike engine certification however, this certification will be based on a loadspecific basis (g/ton-mile or gal/1,000 ton-mile as opposed to work-based, or g/bhp-hr). 

This would take into account the anticipated vehicle loading that would be experienced in 

use and the associated affects on fuel consumption and CO2 emissions. Vehicle 

manufacturers will also be required to warrant their products against emission control 

system defects, and demonstrate that a service network is in place to correct any such 

conditions. The vehicle manufacturer also bears responsibility in the event that an 

emission-related recall is necessary. 

(a) Certification Process

In order to obtain a certificate of conformity for the tractor, the tractor 

manufacturer will complete a compliance demonstration, showing that their product 

meets emission standards as well as other regulatory requirements. For purposes of this 

demonstration, vehicles with similar emission characteristics throughout their useful life 

are grouped together in vehicle families, which are defined primarily by the regulatory

subclass of the vehicle. Manufacturers may further classify vehicles together into subfamilies within a given vehicle family for a given regulatory subcategory. Examples of 

characteristics that would define a vehicle sub-family for heavy-duty vehicles are wheel 

and tire package, aerodynamic profile, tire rolling resistance, and vehicle speed limiting 

system. Compliance with the emission standards (or FEL) will be determined at the subfamily level.

Under this system, the worst-case vehicle configuration would be selected based 

on having the highest fuel consumption, and all other configurations within the family or 

sub-family are assumed to have emissions and fuel consumption at or below the parent 

model and therefore in compliance with CO2 emission an2d fuel consumption standards. 

Any vehicle within the family can be subject to selective enforcement auditing in 

addition to confirmatory or other administrator testing. 

Vehicle families for Class 7 and 8 combination tractors will utilize the 

standardized 12-digit naming convention, as described along with the engine certification 

process in Section V.C.1.a, above. As with engines, each certifying vehicle manufacturer 

will have a unique three digit code assigned to them. Currently, there is no 5th digit

(industry sector) code for this class of vehicles, for which we proposed to use the next 

available character, “2.” The agencies originally proposed that engine displacement be 
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included in the vehicle family name, however the wide range of engines available across 

most regulatory subcategories makes this requirement irrelevant and unnecessary at the 

time of this rulemaking. Therefore, we are reserving the remaining characters for 

California ARB and/or manufacturer use, such that the result is a unique vehicle family

name.

Class 7 and 8 tractors share several common traits, such as the trailer attachment 

provisions, number of wheels, and general construction. However, further inspection 

reveals key differences related to GHG emissions. Payloads hauled by Class 7 tractors 

are significantly less than Class 8 tractors. In addition, Class 8 vehicles may have 

provisions for hoteling (“sleeper cabs”), which results in an increase in size as well as the 

addition of comfort features like power and climate control for use while the truck is 

parked. Both segments may have various degrees of roof fairing to provide better 

aerodynamic matching to the trailer being pulled. This is a feature which can help reduce 

CO2 emissions significantly when properly matched to the trailer, but can also increase 

CO2 emissions if improperly matched. Based on these differences, it is reasonable to 

expect differences in CO2 emissions, and therefore these properties form the basis for the 

final combination tractor regulatory subcategories.

The various combinations of payload, cab size, and roof profile result in nine final 

regulatory subcategories for Class 7 and 8 tractors. Class 7 tractors are divided into three 

regulatory subcategories: one for low, one for mid roof height profiles, and one for high 

roof profiles. The Class 7 tractors are subject to a 10 year, 185,000 regulatory useful life. 

Class 8 tractors are split into six regulatory subcategories reflecting two cab sizes (day

and sleeper) and three roof height profiles (low, mid, and high). All Class 8 tractors are 

subject to a 10 year, 435,000 mile regulatory useful life. 

(b) Demonstrating Compliance with the Final Standards

(i) CO2 and Fuel Consumption Standards

As discussed at proposal, although whole-vehicle certification may be ultimately

desirable for these vehicles, it is essentially infeasible to require it now. See 75 FR at 

74270-71. Most commenters agreed, as did the NAS Report. Accordingly, again 

consistent with the NAS Report, the agencies have developed a predictive model for 

demonstrating compliance with these initial standards for combination tractors. The 

agencies will continue to work toward improved methods for whole vehicle performance 

characterization, as suggested by some commenters.

Model

Vehicle modeling will be conducted using the agencies’ simulation model, the 

GEM, which is described in detail in Chapter 4 of the RIA with responses to comments in 

the Summary and Analysis of Comments Document Section 7. Basically, this model 

functions by defining a vehicle configuration and then exercises the model over various 

drive cycles. Several initialization files are needed to define a vehicle, which include 

mechanical attributes, control algorithms, and driver inputs. The majority of these inputs 
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will be predetermined by EPA and NHTSA for the purposes of vehicle certification. The 

net results from the GEM are weighted CO2 emissions and fuel consumption values over 

the drive cycles. The CO2 emission result will be used for demonstrating compliance 

with vehicle CO2 standards while the fuel consumption result will be used for 

demonstrating compliance with the fuel consumption standards.

The vehicle manufacturer will be responsible for entering up to seven inputs 

relating to the GHG performance of a vehicle configuration although, depending on the 

regulatory category, fewer inputs may be required. These inputs include the regulatory

category, coefficient of drag, steer tire rolling resistance, drive tire rolling resistance, 

vehicle speed limit, vehicle weight reduction, and idle reduction credit. For the GEM 

inputs relating to aerodynamics, the agencies have finalized lookup tables for frontal area 

and coefficient of drag based on typical performance levels across the industry. 

Manufacturers are responsible for assessing the aerodynamic performance of their 

vehicles through testing or a combination of testing and modeling. This test data is then 

used to select the most appropriate agency-defined bin for entry into the GEM. 

Tire rolling resistance is simply the measured rolling resistance of the tire in kg 

per metric ton as described in ISO 28580:2009. This measured value is expected to be 

the result of three repeat measurements of three different tires of a given design, giving a 

total of nine data points. It is the average of these nine results that will be entered into the 

GEM. Tire rolling resistance may be determined by either the vehicle or tire 

manufacturer. In the latter case, a signed statement from the tire manufacturer confirming 

testing was conducted in accordance with this part is required.

As previously described, limiting vehicle speed can have a significant effect on 

fuel consumption and we believe that manufacturers should be recognized for including 

technology that facilitates these limits. Also as described, these vehicle speed limiters are 

not likely to be a simple device with a fixed top speed. “Soft top” limits based on driver 

behavior and limit expiration dates (or mileage) are two of the most common scenarios. 

To properly assess the GHG and fuel consumption benefits in light of these features, we 

are defining the proper methodology for entering the vehicle speed limit into the GEM.

This is based on an equation including terms for VSL expiration (expiration factor) and 

VSL soft-top (soft-top factor and soft-top VSL). The result will be an effective vehicle 

speed limit reflecting the expected mileage and time that the limit will be used for. 

Additional details regarding this equation and its derivation can be found in RIA Chapter 

2.

For vehicle weight reduction, the agencies are primarily addressing the reduction 

of weight and perhaps number of wheels. This reduction is assessed relative to a standard 

combination tractor configuration with dual-wide rear tires with conventional steel 

wheels. Manufacturers may elect to use single-wide tires/wheels and/or aluminum (or 

light-weight aluminum) wheels or other components to reduce the weight of their 

vehicles. The agencies have defined standard weight reduction levels associated with 

each weight reduction technology for entry into the GEM. These reductions are listed in 

pounds per component, so manufacturers will need to multiply this reduction by the 

number of affected components for their total weight reduction entry into the GEM.
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Manufacturers of sleeper cabs electing to limit idle time to 300 seconds or less 

can claim a GHG benefit of 5 g/ton-mile and should be entered into the GEM as such. 

This benefit cannot be scaled to reflect shorter or longer allowed idle times, but can be 

scaled based upon expiration date.

The agencies will utilize the appropriate engine map reflecting use of a certified 

engine in the truck (and will enter the same value even if an engine family is certified to 

the temporary percent reduction alternative standard, in order to evaluate vehicle 

performance independently of engine performance.) We believe this approach reduces 

the testing burden placed upon manufacturers, yet adequately assesses improvements 

associated with select technologies. The model will be publicly available and will be 

found on EPA’s website.

The agencies reserve the right to independently evaluate the inputs to the model 

by way of Administrator testing to validate those model inputs. The agencies also 

reserve the right to evaluate vehicle performance using the inputs to the model provided 

by the manufacturer to confirm the performance of the system using GEM. This could 

include generating emissions results using the GEM and the inputs as provided by the 

manufacturer based on the agency’s own runs. This could also include conducting 

comparable testing to verify the inputs provided by the manufacturer. In the event of 

such testing or evaluation, the Administrator’s results become the official certification 

results, the exception being that the manufacturer may continue to use their data as 

initially submitted, provided it represents a worst-case condition over the Administrator’s 

results.

To better facilitate the entry of only the appropriate parameters, the agencies will 

provide a graphical user interface in the model for entering data specific to each vehicle. 

In addition, EPA will provide a template that facilitates batch processing of multiple 

vehicle configurations within a given family. It is expected that this template will be 

submitted to EPA as part of the certification process for each certified vehicle family or 

subfamily.

For certification, the model will exercise the vehicle over three test cycles; one 

transient and two steady-state. For the transient test, we are using the heavy heavy-duty 

diesel truck (HHDDT) transient test cycle, which was developed by the California Air 

Resources Board and West Virginia University to evaluate heavy-duty vehicles. The 

transient mode simulates urban, start-stop driving, featuring 1.8 stops per mile over the 

2.9 mile duration. The two steady state test points are reflective of the tendency for some 

of these vehicles to operate for extended periods at highway speeds. Based on data from 

the EPA’s MOVES database, and common highway speed limits, we are finalizing these 

two points to be 55 and 65 mph. 

The model will predict the total emissions results from each configuration using 

the unique properties entered for each vehicle. These results are then normalized to the 

payload and distance covered, so as to yield a gram/ton-mile result, as well as a fuel 

consumption (gal/1,000 ton-mile) result for each test cycle. As with engine and vehicle 

testing, certification will be based on the worst-case configuration within a vehicle family 
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The results from all three tests are then combined using weighting factors, which 

reflect typical usage patterns. The typical usage characteristics of Class 7 and 8 tractors 

with day cabs differ significantly from Class 8 tractors with sleeper cabs. The trucks with 

day cabs tend to operate in more urban areas, have a limited travel range, and tend to 

return to a common depot at the end of each shift. Class 8 sleeper cabs, however, are 

typically used for long distance trips which consist of mostly highway driving in an effort 

to cover the highest mileage in the shortest time. For these reasons, we proposed that the 

cycles are weighted differently for these two groups of vehicles. For Class 7 and 8 trucks 

with day cabs, we propose weights of 64%, 17%, and 19% (65 mph, 55 mph, and 

transient, resp.). For Class 8 with sleeper cabs, the high speed cruise tendency results in 

final weights of 86%, 9%, and 5% (65 mph, 55 mph, and transient, respectively). These 

final, weighted emission results are compared to the emission standard to assess 

compliance. The agencies received comments regarding the duty cycles and the 

weighting factors used for assessing emissions compliance. In making final 

determination for the cycle weighting factors, the agencies considered those comments, 

as well as the agencies’ own data in determining the final weighting factors and duty

cycles to be used for determining emissions compliance. Demonstration of compliance is 

also available through the use of credits generated as part of the Averaging, Banking, and 

Trading Program (ABT) as described earlier in this Preamble. Additionally, compliance 

may be demonstrated through the use of a Vehicle Speed Limiter (VSL) and the 

application of the VSL is accounted for as another input to the GEM for assessing GHG 

and fuel consumption emissions performance. 

Durability Testing

As with engine certification, a manufacturer must provide evidence of compliance 

through the regulatory useful life of the vehicle. Factors influencing vehicle-level GHG 

performance over the life of the vehicle fall into two basic categories: vehicle attributes 

and maintenance items. Each category merits different treatment from the perspective of 

assessing useful life compliance, as each has varying degrees of manufacturer versus 

owner/operator responsibility.

The category of vehicle attributes generally refers to aerodynamic features, such 

as fairings, side-skirts, air dams, air foils, etc, which are installed by the manufacturer to 

reduce aerodynamic drag on the vehicle. These features have a significant impact on 

GHG emissions and their emission reduction properties are assessed early in the useful 

life (at the time of certification). These features are expected to last the full life of the 

vehicle without becoming detached, cracked/broken, misaligned, or otherwise not in a 

state which provides the original GHG emissions reduction. In the absence of the 

aforementioned failure modes, the performance of these features is not expected to 

degrade over time and the benefit to reducing GHG emissions is expected to last for the 

life of the vehicle with no special maintenance requirements. To assess useful life 

compliance, we are following a design-based approach which will ensure that the 

manufacturer has robustly designed these features so they can reasonably be expected to 

last the useful life of the vehicle.
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The category of maintenance items refers to items that are replaced, renewed, 

cleaned, inspected, or otherwise addressed in the preventative maintenance schedule 

specified by the vehicle manufacturer. Replacement items that have a direct influence on 

GHG emissions are primarily tires and lubricants. Synthetic engine oil may be used by 

vehicle manufacturers to reduce the GHG emissions of their vehicles. Manufacturers may

specify that these fluids be changed throughout the useful life of the vehicle. If this is the 

case, the manufacturer should have a reasonable basis that the owner/operator will use 

fluids having the same properties. This may be accomplished by requiring (in service 

documentation, labeling, etc) that only these fluids can be used as replacements. 

If the vehicle remains in its original certified condition throughout its useful life, 

it is not believed that GHG emissions would increase as a result of service accumulation. 

This is based on the assumption that as components such as tires wear, the rolling 

resistance due to friction is likely to stay the same or decrease. With all other components 

remaining equal (tires, aerodynamics, etc), the overall drag force would stay the same or 

decrease, thus not significantly changing GHG emissions at the end of useful life. It is 

important to remember however, that this vehicle assessment does not take into account 

any engine-related wear affects, which may in fact increase GHG emissions over time. 

The agencies received comments from engine and tractor manufacturers requesting an 

assigned deterioration factor of zero for GHG emissions. As discussed previously, the 

agencies will allow the use of an assigned deterioration factor of zero where appropriate 

in Phase 1, however this does not negate the responsibility of the manufacturer to ensure 

compliance with the emissions standards throughout the useful life. 

For the reasons explained above, we believe that for the first phase of this 

program, it is most important to ensure that the vehicle remain in its certified 

configuration throughout the useful life. This can most effectively be accomplished 

through engineering analysis and specific maintenance instructions provided by the 

vehicle manufacturer. The vehicle manufacturer would be primarily responsible for 

providing engineering analysis demonstrating that vehicle attributes will last for the full 

useful life of the vehicle. We anticipate this demonstration will show that components are 

constructed of sufficiently robust materials and design practices so as not to become 

dysfunctional under normal operating conditions. For instance, we expect aerodynamic 

fairings to be constructed of materials similar to that of the main body of the vehicle 

(fiberglass, steel, aluminum, etc) and have sufficient support and attachment mechanisms 

so as not to become detached or broken under normal, on-highway driving. 

(ii) EPA’s Air Conditioning Leakage Standards

Heavy-duty vehicle air conditioning systems contribute to GHG emissions in two 

ways. First, operation of the air conditioning unit places an accessory load on the engine, 

which increases fuel consumption. Second, most modern refrigerants are HFC-based, 

which have significant global warming potential (GWP=1430). For heavy-duty vehicles, 

the load added by the air conditioning system is comparatively small compared to other 

power requirements of the vehicle. Therefore, we are not targeting any GHG reduction 

due to decreased air conditioning usage or higher efficiency A/C units for this final 
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action. However, refrigerant leakage, even in very small quantities, can have significant 

adverse effects on GHG emissions. 

Refrigerant leakage is a concern for heavy-duty vehicles, similar to light-duty

vehicles. To address this, EPA is finalizing a design-based standard for reducing 

refrigerant leakage from heavy-duty pickups and vans and combination tractors. This 

standard is based off using the best practices for material selection and interface sealing, 

as outlined in SAE publication J2727. Based on design criteria in this publication, a 

leakage “score” can be assessed and an estimated annual leak rate can be made for the 

A/C system based on the refrigerant capacity. (There is no requirement for vocational 

vehicle AC leakage for reasons explained at 75 FR 74211.)

At the time of certification, manufacturers will be required to outline the design of 

their system, including the specification of materials and construction methods. They

will also need to supply the leakage score developed using SAE J2727 and the refrigerant 

volume of their system to determine the leakage rate per year. If the certifying 

manufacturer does not complete installation of the air conditioning unit, detailed 

instructions must be provided to the final installer who ensures that the A/C system is 

assembled to meet the low-leakage standards. These instructions will also need to be 

provided at the time of certification, and manufacturers must retain all records relating to 

auditing of the final assembler.

(c) In-Use Standards

As previously addressed, the drive-cycle dependence of CO2 emissions makes 

NTE-based in-use testing impractical. In addition, we believe the reporting of CO2 data 

from the criteria pollutant in-use testing program will be helpful in future rulemaking 

efforts. For these reasons, we are not finalizing an NTE-based in-use testing program for 

Class 7 and 8 combination tractors for this program.

In the absence of NTE-based in-use testing, provisions are necessary for verifying 

that production vehicles are in the certified configuration, and remain so throughout the 

useful life. Perhaps the easiest method for doing this is to verify the presence of installed 

emission-related components. This would basically consist of a vehicle audit against 

what is claimed in the certification application. This includes verifying the presence of 

aerodynamic components, such as fairings, side-skirts, and gap-reducers. In addition, the 

presence of idle-reduction and speed limiting devices would be verified. The presence of 

LRR tires could be verified at the point of initial sale; however verification at other points 

throughout the useful life would be non-enforceable for the reasons mentioned 

previously.

The category of wear items primarily relates to tires. It is expected that vehicle 

manufacturers will equip their trucks with LRR tires, as they may provide a reduction in 

GHG emissions. The tire replacement intervals for this class of vehicle is normally in the 

range of 50,000 to 100,000 miles, which means the owner/operator will be replacing the 

tires at several points within the useful life of the vehicle. We believe that as LRR tires 

become more common on new equipment, the aftermarket prices of these tires will also 
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decrease. The primary barrier to the introduction of more fuel efficient tire designs into 

the truck market is the upfront costs of tire development and upfront capital costs for new 

production machinery (e.g., new tire molds). Once manufacturers have sunk these costs 

into new tire designs and production facilities in order to meet our vehicle standards, 

there is little barrier for bringing these better products into the replacement tire market as 

well. Our regulations will effectively force OEMs to make these investments in tire 

designs and, having done so, should lead to better tires not only for new vehicles but in 

the replacement tire market as well. Along with decreasing tire prices, the fuel savings 

realized through use of LRR tires will ideally provide enough incentive for 

owner/operators to continue purchasing these tires. Thus, the inventory modeling in this 

final action reflects the continued use of LRR tires through the life of the vehicle. 

(2) Enforcement Provisions

As identified above, a significant amount of vehicle-level GHG reduction is 

anticipated to come from the use of components specifically designed to reduce GHG 

emissions. Examples of such components include LRR tires, aerodynamic fairings, idle 

reduction systems, and vehicle speed limiters. At the time of certification, vehicle 

manufacturers will specify which components will be on their vehicle when introduced 

into commerce. Based on this list of installed components, GHG emissions performance 

of the vehicle will be assessed using the GEM, and compliance with the family (or 

subfamily) emissions limit will need to be shown. Given the ability of manufacturers to 

demonstrate compliance through the use of flexibility provisions, as previously described, 

that will be taken into account when assessing the performance for purposes of 

enforcement. Additionally, should enforcement action be necessary against systems 

certified using the flexibility provisions, credit balances generated through the use of the 

provisions may be reduced as a consequence of enforcement activity. As described in the 

in-use testing section, it is important to have the ability to determine if the vehicle is in 

the certified configuration at the time of sale.

Perhaps the most practical and basic method of verifying that a vehicle is in its 

certified configuration is through a vehicle emissions control information label, similar to 

that used for engines and light-duty vehicles. We proposed that this label list identifying 

features of the vehicle, including model year, vehicle model, certified engine family, 

vehicle manufacturer, test group, and GHG emissions category. In addition, this label 

would list emission-related components that an inspector could reference in the event of a 

field inspection. Possible examples may include LRR (for LRR tires), ARF 

(aerodynamic roof fairing), and ARM (aerodynamic rearview mirrors). With this 

information, inspectors could verify the presence and condition of attributes listed as part 

of the certified configuration.

Several comments were received voicing concern that the large number of vehicle 

permutations within a given vehicle family (and perhaps vehicle subfamily) would lead to 

a large number of unique labels, at significant cost and labor burden to the manufacturer. 

In addition, including generic emission control system (EC) identifiers for vehicles would 

add a significant burden while providing little usable information for inspectors. A 

common example given in the comments was that simply identifying “ARF” for a roof 
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fairing would not be sufficiently detailed for an inspector to know whether the correct 

roof fairing is present. As a result of these concerns, commenters suggested that vehicle 

labels only include a minimal amount of information such as a compliance statement, 

vehicle family name, and date of manufacture.

The agencies generally agree with the concerns raised by the commenters and do 

not wish to add burdensome and arbitrary labeling requirements. Concurrently, we also 

remain committed to giving agency inspectors adequate tools to ensure a vehicle is in its 

certification at least at the time of sale. Therefore, we are finalizing a vehicle label 

requirement that includes:

-Compliance statement

-Vehicle manufacturer

-Vehicle family (and subfamily)

-Date of manufacture

-Regulatory subcategory

-Emission control system identifiers

To address the concerns from vehicle manufacturers identified above, particularly

related to emission control (EC) identifiers, we believe a combination of selectable 

information on the label as well as a set of EPA-defined EC identifiers will provide a 

useful, but not overly burdensome labeling scheme. Since the intent of these identifiers is 

to provide inspectors with a means for simply verifying the presence of a component, we 

do not believe overly detailed identifiers are necessary, particularly for tires and 

aerodynamic components. For instance, current engine regulations require that three-way

catalysts be identified on engine labels as “TWC.” However, unique details such as 

catalyst size, loading, location, and even the number of catalysts are not on the label. In 

similar fashion, we believe that identifying tires and aerodynamic components in a 

general sense will prove similarly effective in determining if a vehicle has been built as 

intended or if it has been modified prior to being offered for sale. 

EPA is requiring that components for which vehicle certification is dependent 

upon be identified on the label. This includes limited aerodynamic components (roof 

fairings, side skirts, & gap reducers), vehicle speed limiters, LRR tires, and idle reduction 

components. If vehicle certification also depends on the use of innovative or advanced 

technologies, this too must be included on the label. The following identifiers must be 

used for the emission control label:

Vehicle Speed Limiters

-VSL – Vehicle speed limiter 

-VSLS – “Soft-top” vehicle speed limiter
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-VSLE – Expiring vehicle speed limiter

-VSLD – Vehicle speed limiter with both “soft-top” and expiration

Idle Reduction Technology

-IRT5 – Engine shutoff after 5 minutes or less of idling

-IRTE – Expiring engine shutoff

Tires

-LRRD – Low rolling resistance tires – Drive (CRR of 8.2 kg/metric ton or less)

-LRRS – Low rolling resistance tires – Steer (CRR of 7.8 kg/metric ton or less)

-LRRA – Low rolling resistance tires – All (meeting appropriate criteria for steer 

& drive)

Aerodynamic Components

-ATS – Aerodynamic side skirt and/or fuel tank fairing

-ARF – Aerodynamic roof fairing

-ARFR – Adjustable height aerodynamic roof fairing

-TGR – Gap reducing fairing (tractor to trailer gap)

Other Components

-ADV – Vehicle includes advanced technology components

-ADVH – Vehicle includes hybrid powertrain

-INV – Vehicle includes innovative technology components

On the vehicle label, several (if not all), available EC identifiers available in a 

given subfamily can be listed and the appropriate selections can be made at the time of 

assembly based on each unique vehicle configuration. This practice is common on engine 

ECI labels (normally for month/year of manufacture) and selections are made using a 

punch, stamp, check mark or other permanent method. This provides inspectors with the 

information they need while still affording flexibility to manufacturers with several 

unique vehicle configurations.

At the time of certification, manufacturers will be required to submit an example 

of their vehicle emission control label such that EPA can verify that all critical elements 

mentioned above are present. In addition to the label, manufacturers will also need to 
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describe where the unique vehicle identification number and date of production can be 

found on the vehicle (if the date is not present on the label)

The agencies received several comments requesting the inclusion of consumerfocused labels for heavy-duty vehicles. These requests mainly involved labels similar to 

those found on passenger vehicles, allowing consumers to easily determine and compare 

fuel efficiency between vehicles. While we agree that such labels proven to be valuable 

to consumers in the light-duty market when shopping and comparing vehicles, the vast 

array of in-use drive cycles for heavy-duty vehicles and significant impact on GHG 

emissions reduce the intrinsic value of such fuel efficiency data to consumers. 

Additionally, many heavy-duty vehicles are unique and purpose-built which prevents 

direct comparison to other vehicles. The agencies may revisit this topic for future 

rulemaking activities, however there is no consumer label requirement in this final action.

(3) Other Certification Provisions

(a) Warranty

Section 207 of the CAA requires manufacturers to warrant their products to be 

free from defects that would otherwise cause non-compliance with emission standards. 

For purposes of this regulation, vehicle manufacturers must warrant all components 

which form the basis of the certification to the GHG emission standards. The emissionrelated warranty covers vehicle speed limiters, idle shutdown systems, fairings, hybrid 

system components, and other components to the extent such components are included in 

the certified emission controls. The emission-related warranty also covers tires and all 

components whose failure would increase a vehicle's evaporative emissions (for vehicles 

subject to evaporative emission standards, which could include components which 

received innovative or advanced technology credits). In addition, the manufacturer must 

ensure these components and systems remain functional for the warranty period defined 

in 40 CFR Part 86 for the engine used in the vehicle, generally defined as half of the 

regulatory useful life. As with heavy-duty engines, manufacturers may offer a more 

generous warranty, however the emissions related warranty may not be shorter than any 

other warranty offered without charge for the vehicle. If aftermarket components are 

installed (unrelated to emissions performance) which offer a longer warranty, this will 

not impact emission related warranty obligations of the vehicle manufacturer. NHTSA, 

for this phase of the program, is not finalizing any warranty requirements relating to its

fuel consumption rule. 

Several comments were received from vehicle manufacturers voicing concern that 

tire warranties should be the responsibility of the tire manufacturer, not the vehicle 

manufacturer. It has been, and remains, EPA policy to hold the certifying entities 

responsible for warranty obligations. In this case, tire manufacturers are not certificate 

holders and therefore we do not believe it is appropriate for them to independently

warrant their products. The agencies see this as no different than requiring turbocharger 

or fuel injector manufacturers to provide warranties related to heavy-duty engines. 

However, we do believe that vehicle manufacturers can and should hold tire 

manufacturers responsible for warranty of their products as part of their sourcing and 
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purchasing agreements. As proposed, tires are only required to be warranted for the first 

life of the tires (vehicle manufacturers are not expected to cover replacement tires). For 

heavy-duty pickups and vans and combination tractors, the vehicle manufacturer is also 

required to warrant the A/C system against design or manufacturing defects causing 

refrigerant leakage in excess of the standard. The warranty period for the A/C system is 

identical to the vehicle warranty period as described above.

At the time of certification, manufacturers must supply a copy of the warranty

statement that will be supplied to the end customer. This document should outline what 

is covered under the GHG emissions related warranty as well as the length of coverage. 

Customers must also have clear access to the terms of the warranty, the repair network, 

and the process for obtaining warranty service.

(b) Maintenance

Vehicle manufacturers are required to outline maintenance schedules that ensure 

their product will remain in compliance with emission standards throughout the useful 

life of the vehicle. For heavy-duty vehicles, such maintenance may include 

fluid/lubricant service, fairing adjustments, or service to the GHG emission control 

system. This schedule is required to be submitted as part of the application for

certification. Maintenance that is deemed to be critical to ensuring compliance with 

emission standards is classified as “critical emission-related maintenance.” Generally, 

manufacturers are discouraged from specifying that critical emission-related maintenance 

is needed within the regulatory useful life of the engine. However, if such maintenance is 

unavoidable, manufacturers must have a reasonable basis for ensuring it is performed at 

the correct time. This may be demonstrated through several methods including survey

data indicating that at least 80% of engines receive the required maintenance in-use or 

manufacturers may provide the maintenance at no charge to the user. 

Manufacturers will be required to submit the recommended emission-related 

maintenance schedule (and other service related documentation) at the time of 

certification. This documentation should provide sufficient detail to allow the 

owner/operator of the vehicle to maintain the emission control system in a way that will 

ensure functionality as intended. This would include items such as periodic inspection of 

aerodynamic components and maintenance unique to advanced or innovative 

technologies. In addition, these instructions should provide the owner/operator with 

adequate information to replace consumable components (such as tires) with comparable 

replacements.

Since low rolling resistance tires are key emission control components under this 

program, and will likely require replacement at multiple points within the life of a 

vehicle, it is logical to clarify how this fits into the emission-related maintenance 

requirements. While the agencies encourage the exclusive use of LRR tires throughout 

the life of heavy-duty vehicles, we recognize that it is inappropriate at this time to hold 

vehicle manufacturers responsible for ensuring that this occurs. Additionally, we believe 

that owner/operators have a legitimate financial motivation for ensuring their vehicles are 

as fuel efficient as possible, which includes purchasing LRR replacement tires. However 
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owner/operators may not have a sound knowledge of which replacement tires to purchase 

to retain the as-certified fuel efficiency of their vehicle. To address this concern and in 

response to comments from vehicle manufacturers, we are requiring that vehicle 

manufacturers supply adequate information in the owner’s manual to allow the 

owner/operator of the vehicle to purchase tires meeting or exceeding the rolling 

resistance performance of the original equipment tires. We expect that these instructions 

will be submitted to EPA as part of the application for certification.

(c) Certification Fees

Similar to engine certification, the agency will assess certification fees for heavyduty vehicles. The proceeds from these fees are used to fund the compliance and 

certification activities related to GHG regulation for this regulatory category. In addition 

to the certification process, other activities funded by certification fees include EPAadministered in-use testing, selective enforcement audits, and confirmatory testing. At 

this point, the exact costs associated with the heavy-duty vehicle GHG compliance are 

not well known. EPA will assess its compliance program cost associated with this 

program and assess the appropriate level of fees. We anticipate that fees will be applied 

based on vehicle families, following the light-duty vehicle approach. 

(d) Requirements for Conducting Aerodynamic Assessment Using the Modified 

Coastdown Reference Method and Alternative Aerodynamic Methods

The requirements for conducting aerodynamic assessment using the modified 

coastdown reference method and alternative aerodynamic methods includes two key

components: adherence to a minimum set of standardized criteria for each allowed 

method and submittal of aerodynamic values and supporting information on an annual 

basis for the purposes of certifying vehicles to a particular aerodynamic bin as discussed 

in Section II.

First, we are finalizing requirements for conducting the modified coastdown 

reference method and each of the alternative aerodynamic assessment methods. We will 

cite approved and published standards and practices, where feasible, but will define 

criteria where none exists or where more current research indicates otherwise. A 

description of the requirements for each method is discussed later in this section. The 

manufacturer will be required to provide performance data on its vehicles and attest to the 

accuracy of the information provided.

Second, to ensure continued compliance, manufacturers will be required to 

provide a minimum set of information on an annual basis at certification time 1) to 

support continued use of an aerodynamic assessment method and 2) to assign an 

aerodynamic value based on the applicable aerodynamic bins. The information supplied 

to the agencies should be based on an approved aerodynamic assessment method and 

adhere to the requirements for conducting aerodynamic assessment mentioned above.

The annual submission may be based on coastdown testing conducted consistent 

with the modified protocol detailed in this rulemaking or with an approved alternative 
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method. The coastdown testing must be conducted using the Modified Protocol which 

uses SAE J1263 as a basis with some elements of SAE J2263 (e.g., post-processing and 

analysis techniques), in addition to the modifications developed in response to industry

comments which raised concerns regarding test to test variability. 

In addition to 8 valid coastdown runs in each direction, manufacturers using inhouse test methods should provide an adjustment factor for relating their drag coefficient 

based on their in-house method to the reference method, modified coastdown. The basis 

for the adjustment factor is:

Adjustment Factor = Cd coastdown / Cd in-house

For the test article used for certification that differs from the test article used for 

reference method testing, determine Cd to use for aerodynamics bin determination as 

described below.

Cd certification BIN = Adjustment Factor x Cdin-house measured 

The specific requirements for the test article used in reference method testing 

using the coastdown procedures should meet the requirements listed in Table V-2 through 

Table V-5, below.
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Table V-2: Reference Method Test Vehicle Specifications

53’ Air Ride Dry Vans

Length: 53 feet (636 inches) +/- 1 inch

Width: 102 inches +/- 0.5 inches

Height: 102 inches (162 inches or 13 feet, 6 inches (+0.0 inch/-1 inch) 

from the ground)

Capacity: 3800 cubic feet

Assumed trailer 

load/capacity: 

45,000 lbs.

Suspension: Any (see “trailer ride height” below)

Corners: Rounded with a radius of 5.5 inches +/-0.5 inches

Bogie/Rear Axle Position: Tandem axle (std), 146 inches +/-3.0 inches from rear axle 

centerline to rear of trailer. set to California position

Skin: Generally smooth with flush rivets

Scuff band: Generally smooth, flush with sides (protruding ≤ 1/8 inch)

Wheels: 22.5 inches. Duals. Std mudflaps

Doors: Swing doors

Undercarriage/Landing 

Gear:

Std landing gear, no storage boxes, no tire storage, 105 inches +/-

4.0 inches from front of trailer to centerline of landing gear

Underride Guard Equipped in accordance with 49 CFR §393.86

Tires for the Standard Trailer and the Tractor:

a. Size: 295/75R22.5 or 275/80R22.5

b. CRR<5.1 kg/metric ton (In addition, the CRR for trailer tires in GEM should be updated to 5.0 

kg/metric ton.)

c. Broken in per section 8.1 of SAE J1263

d. Pressure per section 8.5 of SAE J1263

e. No uneven wear

f. No re-treads

g. Should these tires or appropriate Smart Way tires not be available, the Administrator testing

may include tires used by the manufacturer for certification.

Test Conditions:

1. Tractor-trailer gap: 45 inches +/- 2.0 inches

2. King pin setting: 36 inches +/- 0.5 inches from front of trailer to king pin center line

3. Trailer ride height: 115 inches +/-1.0 inches from top of trailer to fifth wheel plate, measured 

at the front of the trailer, and set within trailer height boundary from ground as described 

above

4. Mudflaps: Positioned immediately following wheels of last axle
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Table V-3: Reference Method Coastdown Test Track Condition Specifications

Parameter Range

Coastdown speed range 70 mph to 15 mph 

Average wind speed at the test site

(for each run in each direction)

< 10 mph

Maximum wind speed (for each run in 

each direction)

<12.3 mph

Average cross wind speed

(for each run in each direction at the site)

< 5 mph

All valid coastdown runs in one direction Within 2 standard deviations of the other 

valid coastdown runs in that same direction

Grade of the test track <0.02% or account for the impact of gravity

as described in SAE J2263 Equation 6.

Table V-4: Standard Tanker Trailer for Special Testing 

Tanker

Length: 42 feet ± 1 foot, overall

40 feet ± 1 foot, tank 

Width: 96 inches ± 2 

Height: 140 inches 

(overall, from ground)

Capacity: 7,000 gallons

Suspension: Any (see “trailer ride height” below)

Tank: Generally cylindrical with rounded ends.

Bogie: Tandem axle (std). Set to furthest rear position.

Skin: Generally smooth

Structures: (1) Centered, manhole (20 inch opening), (1) ladder generally 

centered on side, (1) walkway (extends lengthwise)

Wheels: 24.5 inches. Duals. 

Tanker Operation Empty
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Table V-5: Standard Flatbed Reference Trailer for Special Testing

Flatbed

Length: 53 feet

Width: 102 inches

Flatbed Deck Heights: Front: 60 inches ± 1⁄2 inch

Rear: 55 inches ± 1⁄2 inch

Wheels / Tires 22.5 inch diameter tire with steel or aluminum wheels

Bogie Tandem axles, may be in “spread” configuration up to 10 feet ± 2 

inches.

Air suspension 

Load Profile: 25 inches from the centerline to either side of the load; 

Mounted 4.5 inches above the deck.

Load height 31.5 inches above the load support. 

Regardless of the method, all testing using high-roof sleepers should be 

performed with a tractor-trailer combination to mimic real world usage. Accordingly, it 

is important to match the type of tractor with the correct trailer. Although, as discussed 

elsewhere in this rulemaking, the correct tractor-trailer combination is not always present 

or tractor-only operation may occur, the majority of operation in the real world involves 

correctly matched tractor-trailer combinations and we will attempt to reflect that here. 

Therefore, when performing an aerodynamic assessment for a Class 7 and 8 tractor with a 

high roof, a standard box trailer must be used.

The definitions of the standard trailer are further detailed in §1037.501(g). This 

ensures consistency and continuity in the aerodynamic assessments, and maintains the 

overlap with real world operation. As mid-roof and low-roof coastdown testing will be 

conducted without the trailer if the aerodynamic bin is not extrapolated from a high-roof 

version, then testing using other methods should also be conducted based on the tractor 

alone.

(e) Standardized Criteria for Aerodynamic Assessment Methods

(i) Coastdown Procedure Requirements

For coastdown testing, the test runs should be conducted in a manner consistent 

with SAE J1263 with additional modifications as described in the 40 CFR part 1066, 

subpart C, and in Chapter 3 of the RIA using the mixed model analysis method. Since 

the coastdown procedure is the primary aerodynamic assessment method, the 

manufacturer would be required to conduct the coastdown procedure according to the 

requirements in this final action and supply the following information to the agency for 

approval: 

 Facility information: name and location, description and/or 

background/history, equipment and capability, track and facility elevation, 

track grade and track size/length;
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 Test conditions for each test result including date and time, wind speed 

and direction, ambient temperature and humidity, vehicle speed, driving 

distance, manufacturer name, test vehicle/model type, model year, 

applicable model engine family, tire type and rolling resistance, test 

weight and driver name(s) and/or ID(s); 

 Average Cd result as calculated in 40 CFR 1037.520(b) from valid tests 

including, at a minimum, ten valid test results, with no maximum number, 

standard deviation, calculated error and error bands, and total number of 

tests, including number of voided or invalid tests. 

(ii) Wind Tunnel Testing Requirements

Wind tunnel testing would conform to the following procedures and 

modifications, where applicable, including: 

 SAE J1252, “SAE WIND TUNNEL TEST PROCEDURE FOR 

TRUCKS AND BUSES” (July 1981) shall be followed with the following 

exceptions: section 5.2 is modified to specify a minimum Reynold's 

number (Remin) of 1.0 x 106and your model frontal area at zero yaw angle 

may exceed the recommended 5 percent of the active test section area, 

provided it does not exceed 25 percent; section 6.0 is modified to add the 

requirement that, for reduced-scale wind tunnel testing, a one-eighth 

(1/8th) or larger scale model of a heavy-duty tractor and trailer must be 

used; for reduced-scale wind tunnel testing, section 6.1 is modified to add 

the requirement that the model be of sufficient design to simulate airflow 

through the radiator inlet grill and across an engine geometry

representative of those commonly in your test vehicle.;

 J1594, “VEHICLE AERODYNAMICS TERMINOLOGY” (December 

1994); and

 J2071, “AERODYNAMIC TESTING OF ROAD VEHICLES - OPEN 

THROAT WIND TUNNEL ADJUSTMENT” (June 1994).

In addition, the wind tunnel used for aerodynamic assessment would be a 

recognized facility by the Subsonic Aerodynamic Testing Association. If your wind 

tunnel is not capable of testing in accordance with these EPA modified SAE procedures, 

you may request EPA approval to use this wind tunnel and must demonstrate that your 

alternate test procedures produce data sufficiently accurate for compliance. This must be 

approved by EPA prior to method validation and correlation factor development. We are 

finalizing the provisions that manufacturers that perform wind tunnel testing do so based 

on the requirements detailed in this action. The wind tunnel tests should be conducted at 

a zero yaw angle and, if so equipped, utilizing the moving/rolling floor (i.e., the 

moving/rolling floor should be on during the test as opposed to static) for comparison to 

the coastdown procedure, which corrects to a zero yaw angle for the oncoming wind. 

However, manufacturers may be required to test at yaw angles other than zero (e.g., 
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positive and negative six) if they voluntarily seek to improve their GHG emissions score 

for a given model using additional yaw sweep. 

The manufacturer is required to supply the following:

 Facility information: name and location, description and 

background/history, layout, wind tunnel type, diagram of wind tunnel 

layout, structural and material construction;

 Wind tunnel design details: corner turning vane type and material, air 

settling, mesh screen specification, air straightening method, tunnel 

volume, surface area, average duct area, and circuit length;

 Wind tunnel flow quality: temperature control and uniformity, airflow 

quality, minimum airflow velocity, flow uniformity, angularity and 

stability, static pressure variation, turbulence intensity, airflow 

acceleration and deceleration times, test duration flow quality, and overall 

airflow quality achievement;

 Test/Working section information: test section type (e.g., open, closed, 

adaptive wall) and shape (e.g., circular, square, oval), length, contraction 

ratio, maximum air velocity, maximum dynamic pressure, nozzle width 

and height, plenum dimensions and net volume, maximum allowed model 

scale, maximum model height above road, strut movement rate (if 

applicable), model support, primary boundary layer slot, boundary layer 

elimination method and photos and diagrams of the test section;

 Fan section description: fan type, diameter, power, maximum rotational 

speed, maximum top speed, support type, mechanical drive, sectional total 

weight

 Data acquisition and control (where applicable): acquisition type, motor 

control, tunnel control, model balance, model pressure measurement, 

wheel drag balances, wing/body panel balances, and model exhaust 

simulation

 Moving ground plane or Rolling Road (if applicable): construction and 

material, yaw table and range, moving ground length and width, belt type, 

maximum belt speed, belt suction mechanism, platen instrumentation, 

temperature control, and steering; and

 Facility correction factors and purpose. 

(iii) CFD Requirements

Currently, there is no existing standard, protocol or methodology governing the 

use of CFD. Therefore, we are establishing a minimum set of criteria based on today’s 
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practices and coupling the use of CFD with empirical measurements from coastdown 

and, for gaining innovative technology credits, wind tunnel procedures. Since there are 

primarily two-types of CFD software code, Navier-Stokes based and Lattice-Boltzman 

based, we are outlining two sets of criteria to address both types. Therefore, the agencies 

are requiring that manufacturers use commercially-available CFD software code with a 

turbulence model included or available. . Further details and criteria for each type of 

commercially-available CFD software code follows immediately and general criteria for 

all CFD analysis are subsequently described.

For Navier-Stokes based CFD code, manufacturers must perform an unstructured, 

time-accurate analysis using a mesh grid size with total volume element count of at 

least fifty million cells of hexahedral and/or polyhedral mesh cell shape, surface 

elements representing the geometry consisting of no less than six million elements and a 

near wall cell size corresponding to a y+ value of less than three hundred with the 

smallest cell sizes applied to local regions of the tractor and trailer in areas of high flow 

gradients and smaller geometry features. Navier-Stokes-based analysis should be 

performed with a turbulence model (e.g., k-epsilon (k-ε), shear stress transport k-omega 

(SST k-ω) or other commercially-accepted method) and mesh deformation (if applicable)

enabled with boundary layer resolution of +/- 95 percent. Finally, Navier-Stokes based 

CFD analysis for the purposes of determining the Cd should be performed once result 

convergence is achieved. Manufacturers should demonstrate convergence by supplying 

multiple, successive convergence values.

For Lattice-Boltzman based CFD code, manufacturers must perform an 

unstructured, time-accurate analysis using a mesh grid size with total number of volume 

elements of at least fifty million with a near wall cell size of no greater than six 

millimeters on local regions of the tractor and trailer in areas of high flow gradients and 

smaller geometry features, with cell sizes in other areas of the mesh grid starting at 

twelve millimeters and increasing in size from this value as the distance from the tractortrailer model increases. 

In general for CFD, all analysis should be conducted using the following 

conditions: a tractor-trailer combination using the manufacturer’s tractor and the trailer 

according to the trailer specifications in this regulation, an environment with a blockage 

ratio of less than or equal to 0.2 percent to simulate open road conditions, a zero degree 

yaw angle between the oncoming wind and the tractor-trailer combination, ambient 

conditions consistent with the modified coastdown test procedures outlined in this 

regulation, open grill with representative back pressures based on data from the tractor 

model, turbulence model and mesh deformation enabled (if applicable), and tires and 

ground plane in motion consistent with and simulating a vehicle moving in the forward 

direction of travel. For any CFD analysis, the smallest cell size should be applied to local 

regions on the tractor and trailer in areas of high flow gradients and smaller geometry

features (e.g., the a-pillar, mirror, visor, grille and accessories, trailer leading and trailing 

edges, rear bogey, tires, tractor-trailer gap).

Finally, with administrator approval, a manufacturer may request and perform 

CFD analysis using parameters and criteria other than stated above if the manufacturer 
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can demonstrate that the conditions above are not feasible (e.g., insufficient computing 

power to conduct such analysis, inordinate length of time to conduct analysis, equivalent 

flow characteristics with more feasible criteria/parameters) or improved criteria may

yield better results (e.g., different mesh cell shape and size). A manufacturer must 

provide data and information that demonstrates that their parameters/criteria will provide 

a sufficient level of detail to yield an accurate analysis including comparison of key

characteristics between the manufacturer’s criteria/parameters and those stated above 

(e.g., pressure profiles, drag build-up, and/or turbulent/laminar flow at key points on the 

front of the tractor and/or over the length of the tractor-trailer combination).

Alternative Aerodynamic Method Comparison to the Coastdown Test Procedure 

Reference Method

If a manufacturer uses any alternative aerodynamic method, or any method other 

than the coastdown reference method, the manufacturer would have to provide a 

comparison to the coastdown test procedure reference method. The manufacturer would 

be required to perform the alternative aerodynamic method and the coastdown test 

procedure reference method on the same model and compare the Cd results. The 

alternative aerodynamic method, or any other method using good engineering judgment, 

and the coastdown test procedure reference method must be conducted under similar test 

conditions and adhere to the criteria discussed above for each aerodynamic assessment 

method.

This demonstration would be performed in the initial year of rule implementation 

and would require agency review and approval prior to use of the alternative 

aerodynamic method in future years and for other models. 

The comparison would occur on one model of the manufacturer’s highest sales 

volume, Class 8, high roof, sleeper cab family with a full aerodynamics package, either 

equipped at the factory or sold through a dealer specifically for that model as an OEM 

part. If the manufacturer does not have such a model, the manufacturer may select a 

comparable model in that family or a model from another highest sales volume family in 

the manufacturer’s fleet. 

For the comparison, the manufacturer would be required to provide information 

on the test conditions for each test result including but not limited to: test date and time, 

wind speed (if applicable), temperature, humidity, manufacturer and model, model year, 

applicable model engine family, tire type and rolling resistance for actual model, model 

test weight, equivalent vehicle test weight, actual and simulated or equivalent vehicle 

speed, Reynolds number (if applicable), yaw angle (if applicable), blockage ratio, either 

calculated or measured (if applicable), model mounting (if applicable), model geometry, 

body axis force and moments (if applicable), total test duration, test vehicle and type and 

operator name(s) and/or ID(s). In addition, the manufacturer must provide the Cd results 

from valid tests.

Once the comparison is performed in the initial year, the manufacturer is required

to perform this comparison every three years on the highest sales volume, Class 8, high 
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roof, sleeper cab family equipped with a full aerodynamics package unless any or all of 

the following occurs: the Class 8, high roof, sleeper cab family/model used for the 

original comparison is no longer commercially available, and/or significantly redesigned, 

with the meaning of “significantly” based on good engineering judgment, a fundamental 

change is made to the current alternative aerodynamic method (e.g., change from facility 

A to facility B as a source), and/or the alternative aerodynamic method is changed to 

something other than the coastdown test procedure reference method (e.g., switch to wind 

tunnel testing from coastdown, change wind tunnel testing facilities or CFD software 

code). However, the agency reserves the right and has the authority under the Clean Air 

Act (CAA) to request and have the manufacturer perform a comparison in any year and 

on any model that the manufacturer has certified.

Finally, the data generated for the purpose of this comparison can be used in 

annual certification for that model, also called the base model, and for determining Cd for 

other models and/or sub-families in the base model family, or other families in the 

manufacturer’s fleet. 

Annual Certification Data Submittal for Aerodynamic Assessment

For each model in the manufacturer’s fleet, the manufacturer is required to supply

aerodynamic information on an annual basis to the agencies in their certification 

application. Once the manufacturer has performed the coastdown test procedure or the 

comparison for an alternative aerodynamic method, the aerodynamic assessment method 

can be used to generate Cd values for all models the manufacturer plans to certify and 

introduce into commerce. For each model, the manufacturer would determine a predicted 

aerodynamic drag (Cd times the frontal area, A). This reduces burden on the 

manufacturer to perform aerodynamic assessment but provides data for all the models in 

a manufacturer’s fleet. If a manufacturer has previously performed aerodynamic 

assessment on the other models, the manufacturer may submit an experimental Cd in lieu 

of a predicted Cd.

The aerodynamic assessment data will be used in one of two ways: the 

manufacturer will use the Cd (times A) values to determine the correct GEM input 

according to agency-defined tables, or the agencies will use the manufacturer’s input data 

into the model and assign a GHG value/score.

Since the agencies may input the data into the model, manufacturers are required 

to provide the information from the coastdown test procedure, alternative aerodynamic 

method or the method comparison described above for annual certification. In addition, 

the manufacturer would supply manufacturer fleet information to the agency for annual 

certification purposes along with the acceptance demonstration parameters: manufacturer 

name, model year, model line (if different than manufacturer name), model name, engine 

family, engine displacement, transmission name and type, number of axles, axle ratio, 

vehicle dimensions, including frontal area, predicted or measured coefficient of drag, 

assumptions used in developing the predicted or measured Cd, justification for carryacross of aerodynamic assessment data, photos of the model line-up, if available, and 

model applications and usage options.
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Finally, the agencies reserve the right to request that a manufacturer generate or 

provide additional data, prior to certification, to support and receive annual certification 

approval.

(f) Aerodynamic Validation and Compliance Audit

The agencies reserve the right to perform aerodynamic validation and compliance 

audit of the manufacturer’s aerodynamic results. The agencies may conduct a vehicle 

confirmatory evaluation using a vehicle recruited from the in-use fleet and performing the 

reference method, coastdown test procedures, either at the manufacturer’s facility or an 

independent facility using the agencies equipment and tools. If there is a discrepancy

between the manufacturer’s data submitted for certification and the agencies’ validation 

results, the agency may perform a full audit of the manufacturer’s source data and 

aerodynamic assessment methods and tools used by the manufacturer to produce the data. 

The manufacturer would be required to make all equipment and tools available to the 

agencies to conduct the full audit.

Based on this audit, the agencies may require the manufacturer to make changes 

to their aerodynamic assessment methods ranging from minor adjustments to method 

criteria to switching allowed aerodynamic assessment methods. For the purposes of 

aerodynamic validation and compliance audit, manufacturers will be allowed an 

additional compliance margin of one bin from the certified bin for the model evaluated 

(e.g., if a manufacturer certifies a model to Bin IV, the results of the aerodynamic 

valid/compliance audit must fall within the next highest bin, in this case Bin III). In 

addition, the agencies may select any model from the manufacturer’s fleet/vehicle family 

to perform the aerodynamic validation and compliance.

(g) Aerodynamic Bin Category Adjustment Using Yaw Sweep Information

As discussed in Section II.B.2, the agencies are finalizing aerodynamic drag 

values which represent zero degree yaw (i.e., representing wind from directly in front of 

the vehicle, not from the side). We recognize that wind conditions, most notably wind 

direction, have a greater impact on real world CO2 emissions and fuel consumption of 

heavy-duty trucks than of light-duty vehicles. To provide additional incentive for 

manufacturers using aerodynamic techniques (i.e., techniques that use assessment at yaw 

angles more or less than zero degrees to capture the influence of side winds and calculate 

wind average drag coefficient), the agencies are defining an approach to allow 

manufacturers to account for improved aerodynamic performance in crosswind 

conditions similar to those experienced by vehicles in use. If a manufacturer can benefit 

from having a model that performs in regimes or conditions other than the scope of the 

test parameters in this rulemaking, this creates an incentive for the entire industry. As a 

result, we are allowing manufacturers to use the coefficient of drag values at positive six, 

negative six, and zero degrees yaw to improve their GHG score. 

The Yaw Sweep Adjustment would be determined using the following steps and 

equations:
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 Step 1: Determine your aero method adjustment factor as described above in 

paragraph (d) of this section and using the equation;

Adjustment Factor = Cd coastdown, model 

Cd in-house, model

 Step 2: Apply the aerodynamic method adjustment factor to the positive six, 

negative six and zero degrees yaw Cd values for that model using the 

equation;

Cd Adjusted = Adjustment Factor x Cd(+6 degrees/-6 degrees/0 degrees, model)

 Step 3: Calculate your Adjusted zero yaw Cd*A

Adjusted Zero Yaw Cd*A(model) = 

adjusted +/- Six Yaw Cd(average,model) *A(model) x Zero Yaw Cd*A (industry average) 

+/-Six Yaw Cd(average)*A 

(industry average)

 Step 4: Use the adjusted zero yaw Cd*A for the model to determine 

appropriate bin and the associated Cd input for the GEM to determine your 

Yaw Sweep Adjusted GHG score. 

Essentially, this equation becomes y = x * C where y is the adjusted zero yaw Cd, 

x is the corrected average of the +/- six degree yaw Cds for the manufacturer’s model, 

and C is a constant value based on the ratio of the zero yaw Cd and WACd ratio for the 

industry. The current default value for this industry baseline ratio for this is rulemaking 

is 0.8065 based on the Cd values of current Class 8, high-roof, aero sleeper cab models in 

the fleet. The agencies may periodically review this industry baseline ratio and adjust it, 

if necessary, with notification to the industry. 

The yaw sweep adjustment described above only applies to Class 7, high-roof day

cab and Class 8 high-roof day or sleeper cab tractors and a manufacturer seeking yaw 

sweep adjustment must use an approved, alternative aerodynamic method to generate the 

yaw sweep data. Manufacturers may use a more yaw sweep angles (e.g., zero, +/- 1, 3, 6, 

9) for their yaw sweep adjustment and, in this case, must calculate the wind-average Cd 

(WACd) according to SAE J1252 and use this value in lieu of the average of the +/- six 

degree yaw Cds in the equations above.

As stated elsewhere in this regulation, the Agencies reserve the right to review a 

manufacturer’s proposed adjustment and discuss the proposed adjustment with the 

manufacturer. The Agencies will notify the manufacturer of the need for a review and 
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the manufacturer must provide all information requested by the Agencies to support the 

review and subsequent discussion(s). The agencies also reserve the right to deny

aerodynamic bin category adjustment independent or as a result of the review/discussions 

with the manufacturer. In such case, the Agencies will notify the manufacturer of denial 

prior to certification to ensure the proper inputs to the GEM are used.

(4) Compliance Reports

(a) Early Model Year Data

The regulatory text of the NPRM included specifications for manufacturers to 

submit pre-certification compliance reports for each of a manufacturer’s fleet of heavyduty tractors. Navistar and Volvo commented that the requirements specified in the 

NHTSA pre-certification reports are overbroad and should be eliminated. The precertification reports included requirements for manufactures to submit a wide variety of 

information on these vehicles. The variety of information was believed to be necessary

given that these vehicles had no previous compliance information for meeting fuel 

efficiency and emission standards and the agencies wanted to ensure that enough 

information was obtain to ensure sufficient compliance with the program. The agencies

have since reviewed the level of detail required in the precertification reports and are in 

agreement with commenters that the required information may be overly broad for 

compliance purposes and given that this is the first time these manufacturers have been 

regulated, the level of information required may not be available until subsequent model 

years. Therefore, as discussed previously for pickup trucks and vans, the agencies have 

removed the requirement for manufactures to submit pre-certification compliances 

reports for these classes of vehicles. 

As an alternative to receiving early compliance model year information in the 

precertification reports, the agencies have decided to use manufacturer’s application for 

certificates of conformity to obtain early model estimates. Currently, the applications for 

certificates are not required to include the fuel consumption information required by

NHTSA. Therefore, the agencies are adopting provisions in the final rules for 

manufacturers to provide emission and equivalent fuel consumption estimates in the 

manufacturer’s applications for certification. The agencies will treat information 

submitted in the applications as a manufacturer’s demonstration of providing early 

compliance information, similar to the pre-model year report submitted for heavy-duty 

pickup trucks and vans. The final rule establishes a harmonized approach by which 

manufacturers will submit applications through an EPA-administered database, such as 

the Verify system, as the single point of entry for all information required for this 

national program and both agencies will have access to the information. If by model year 

2012, the agencies are not prepared to receive information through the EPA Verify

database system, manufacturers are expected to submit written applications to the 

agencies. This approach should streamline this process and reduce industry burden and 

provide sufficient information for the agencies to carry out their early compliance 

activities. 
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(b) Final Reports

The NPRM proposed for manufacturers participating in the ABT program to 

provide EOY and final reports. The EOY reports for the ABT program were required to 

be submitted by manufacturers no later than 90 days after the calendar year and final 

report no later than 270 days after the calendar year.318 Manufacturers not participating 

in the ABT program were required to provide an EOY report within 45 days after the 

calendar year but no final reports were required. The final ABT report due was 

established coinciding with EPA’s existing criteria pollutant report for heavy-duty 

engines. The EOY report was required in order to receive preliminary final estimates and 

identifies manufacturers that might have a credit deficit for the given model year. 

Manufacturers with a credit surplus at the end of each model could receive a waiver from 

providing EOY reports. As proposed, the remaining manufacturers were required to 

submit reports to EPA and send copies of those reports to NHTSA with equivalent fuel 

consumption values. 

In response to the NPRM, commenters recommended collecting additional data. 

One commenter requested collecting information to develop and refine test cycles that 

more accurately reflect actual driving cycles for medium- and heavy-duty trucks. Several 

other commenters (ACEE, Eaton, CALSTART, NRDC and UCS) recommended 

collecting advanced data on in-service vehicles and that the collected data be analyzed 

and characterized for each vocational application, especially for hybrid vehicles, in a 

cooperative government and industry effort. Commenters (ACEE, DTNA, NRGDC, 

UCS and Volvo) also requested that the agency’s data collection ensure to include 

information on actual vehicle configurations sold in the fleet. 

Many commenters argued against the burden placed upon the industry in meeting 

the agencies’ proposed required reporting provisions. One commenter argued against 

providing actual production information due to the variability that exists in building 

heavy-duty vehicles and in the influence of changing fleet interest each year indicating 

that only estimated information should have to be provided. Commenters (Volvo and 

Navistar) generally objected stating that the agency requirements in its reports are both 

unnecessary and overly burdensome. Comments in response to the NPRM requested that 

for manufacturers not using ABT provisions, the EOY report due 45 days after the end of 

the calendar year should be combined with the ABT report due 90 days after the same 

model year. Commenters also requested that the exempted off-road vehicle report be 

consolidated with the EOY report. Other concerns raised by commenters were for the 

agencies to remove any differences in reporting provisions and implement a single 

uniform reporting template that manufacturers can submit to both agencies. 

One commenter (Volvo) requested that the agencies simplify the reporting 

requirements for vehicle configurations in both the EOY and final reports, commenting 

that the proposal as outlined was extremely burdensome to vehicle manufacturers. The 

NPRM regulation stated that the manufacturer must identify each distinguishable vehicle 

configuration in the vehicle family or sub-family and identification of FELs for each 

 

318 Corresponding to the compliance model year
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subfamily. The regulation calls for reporting of results and modeling inputs for each 

subfamily. The commenter believed that the burden of meeting these requirements for 

the vast number of families/subfamilies is substantial and unjustified. For this 

commenter, there is a potential for almost 45 million sub-families in the vocational and 

tractor categories. This approach should reduce the number of vehicle families to an 

amount that is suitable for reporting. The BlueGreen Alliance and ACEEE also requested 

the agencies to implement a program as part of the final rule to collect data, actual 

vehicle configurations sold and their performance as estimated by simulation modeling, 

which will provide information required to develop a full-vehicle program in the future. 

For the final rules, the agencies are requiring EOY and final reports, as proposed. 

However, the agencies will consolidate the reporting as requested by comments and is 

requiring equivalent fuel consumption information for all reports submitted to EPA. The 

final rules establish a harmonized approach by which manufacturers will submit reports 

through an EPA-administered database, such as the Verify system, as the single point of 

entry for all information required for this national program and both agencies will have 

access to the information. If by model year 2012, the agencies are not prepared to receive 

information through the EPA Verify database system, manufacturers are expected to 

submit written reports to the agencies. The agencies are also combining the EOY reports 

for manufacturers not using ABT provisions with other EOY reports and are requiring a 

submission date 90 days after the calendar year. The agencies view the adopted 

requirements in the final rules for EOY and final reports will provide sufficient data 

requests to satisfy these requests. The agencies also agree with Volvo’s concerns and 

have adopted a new classification system for selecting vehicle families as described 

elsewhere in this section. A summary of the required information in the final rules for 

EOY and final reports is as follows: 

 Vehicle family designation and averaging set.

 Vehicle emissions and fuel consumption standards including any 

alternative standards used

 Vehicle family FELs

 Final production volumes

 Certified test cycles

 Useful life values for vehicle families

 A credit plan identifying the manufacturers actual credit balances, credit 

flexibilities, credit trades and a credit deficit plan if needed demonstrating 

how it plans to resolve any credit deficits that might occur for a model 

year within a period of up to three model years after that deficit has 

occurred 

 A plan describing the vehicles that were exempted such as for off-road or 

small business purposes

 A plan describing any alternative fueled vehicles that were produced for 

the model year identifying the approaches used to determinate compliance 

and the production volumes
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(c) Additional Required Information

Throughout the model year, manufacturers may be required to report various 

submissions to the agencies to comply with various aspects of the rules. These requests 

have differing criteria for submission and approval. Table V-6 below provides a 

summary of the types of submission, required submission dates and the EPA and NHTSA 

regulations that apply. The agencies will review and grant requests considering the 

timeliness of the submissions and the completeness of the requests.
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Table V-6: Summary of Required Information for Compliance

Submission Applies to Required Submissions 

Date

EPA 

Regulation 

Reference

NHTSA 

Regulation 

Reference

Small business 

exemptions

Vehicle manufacturers 

meeting the Small Business 

Administration (SBA) size 

criteria of a small business 

as described in 13 CFR 

121.201.

Before introducing any 

excluded vehicle into 

U.S. commerce

§1037.150 §535.8

Incentives for 

early 

introduction

The provisions apply with 

respect to tractors and 

vocational vehicles 

produced in model years 

before 2014

EPA must be notified 

before the manufacturer 

submits its applications 

for certificates of 

conformity

§1037.150 §535.8

Voluntary

compliance for 

NHTSA 

standards

Vehicle manufacturers 

seeking early compliance in 

model years 2014 to 2016.

NHSAT must be notified 

before the manufacturer 

submits its applications 

for certificates of 

conformity

NA §535.8

Approval of 

alternate 

methods to 

determine drag 

coefficients

Tractors meeting § 

1037.106

EPA must be notified 

before the manufacturer 

submits its applications

for certificates of 

conformity

§1037.150 §535.8

Off-road 

exemption

Manufacturers wanting to 

exclude tractors from 

vehicle standards

EPA must be notified 

before the manufacturer 

submits its applications

for certificates of 

conformity

§1037.150 §535.8

Vocational 

Tractor

Manufacturers wanting to 

reclassify tractor as 

vocational tractors making 

them applicable to 

vocational vehicle 

standards

EPA must be notified 

before the manufacturer 

submits it applications 

for certificates of 

conformity

§1037.150 §535.8

Exemption 

from EOY 

reports

Manufactures with surplus 

credits at the end of the 

model year

90-days after the 

calendar year ends

§1037.730 §535.8
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E. Class 2b-8 Vocational Vehicles

(1) Final Compliance Approach

Like Class 7 and 8 combination tractors, heavy-duty vocational vehicles will be 

required to have both engine and chassis certificates of conformity. As discussed in the 

engine certification section, engines that will be used in vocational vehicles would need 

to be certified using the heavy-duty FTP cycle for GHG pollutants and show compliance 

through the useful life of the engine. This certification is in addition to the current 

requirements for obtaining a certificate of conformity for criteria pollutant emissions.

For this final action, the majority of the GHG reduction for vocational vehicles is 

expected to come from the use of LRR tires as well as increased utilization of hybrid 

powertrain systems. Other technologies such as aerodynamic improvements and vehicle 

speed limiting systems are not as relevant for this class of vehicles, since the typical duty

cycle is much more urban, consisting of lower speeds and frequent stopping. Idle 

reduction strategies are expected to be encompassed by hybrid technology, which we 

anticipate will ultimately handle PTO operation as well. Therefore, for this final action, 

certification of heavy-duty vocational vehicles with conventional powertrains will focus 

on quantifying GHG benefits due to the use of LRR tires through the GEM.

(a) Certification Process

Vehicles will be divided into vehicle families for purposes of certification. As 

with Class 7 and 8 combination tractors, these are groups of vehicles within a given 

regulatory subcategory that are expected to share common emission characteristics. 

Vocational vehicle regulatory subcategories share the same structure as those used for 

heavy-duty engine criteria pollutant certification and are based on GVWR. This includes 

light-heavy (LHD) with a GVWR at or below 19,500 pounds, medium-heavy (MHD) 

with a GVWR above 19,500 pounds and at or below 33,000 pounds, and heavy-heavy

(HHD) with a GVWR above 33,000 pounds. We anticipate manufacturers will have one 

vehicle family per regulatory subcategory, however hybrid vehicles will need to be 

separated into additional unique vehicle families. Manufacturers may also subdivide 

families into sub-families if GHG emissions performance is expected to change 

significantly within the vehicle family. As with Class 7 and 8 combination tractors, we 

anticipate using the standardized 12-digit naming convention to identify vocational 

vehicle families. As with engines and Class 7 and 8 combination tractors, each certifying 

vehicle manufacturer would have a unique three digit code assigned to them. Currently, 

there is no 5th digit (industry sector) code for this class of vehicles and EPA will issue an 

update to the current guidance explaining which character(s) should be used for 

vocational vehicles. The agencies originally proposed that engine displacement be 

included in the vehicle family name, however the wide range of engines available across 

most regulatory subcategories makes this requirement irrelevant and unnecessary at the 

time of this rulemaking. Therefore, we are reserving the remaining characters for 

California ARB and/or manufacturer use, such that the result is a unique vehicle family

name.
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Each vehicle family must demonstrate compliance with emission standards using 

the GEM. GEM inputs for conventional (i.e. non-hybrid) vocational vehicles primarily

involves entering tire rolling resistance information. Additional provisions are available 

for certification of hybrid vehicles or vehicles using other advanced or innovative 

technologies, as detailed in Section IV. If the vehicle family consists of multiple 

configurations, only results from the worst-case configuration are necessary for 

certification in addition to an engineering evaluation demonstrating that the modeled 

configuration indeed reflects the worst-case configuration. If the vehicle family is 

divided into subfamilies, unique GEM results are required for at least one configuration 

per subfamily.

The agencies have received comments from engine manufacturers, truck 

manufacturers, and hybrid system manufacturers raising concerns regarding the duty 

cycles and the weighting factors proposed for evaluating transient applications. The 

agencies proposed three methods for evaluating hybrid system performance in an effort to 

generate credits. The proposed duty cycles considered for the proposal will continue to be 

used with this final action. The Agencies proposed a transient duty cycle, a 55 mile-perhour steady state cruise and a 65 mile per hour steady state cruise. The transient duty

cycle, is essentially the same transient cycle proposed in the NPRM with the exception 

that it minimizes inappropriate shift events. Additionally, the steady state cycles 

proposed by the Agencies remain essentially unchanged. In response to concerns raised 

by engine manufacturers and hybrid system manufacturers regarding the operation of 

vehicles most likely to be hybridized in the near term, we are modifying the weighting 

factors for each cycle to address the distribution of the emissions impact associated with 

each duty cycle. The weighting factors will be changed such that a greater emphasis on 

the type of transient activity seen as more characteristic of hybrid applications will be 

evident. The new weighting factors between duty cycles for hybrid certification will be 

75% for the transient, 9% for the 55 mph cruise cycle, and 16% for the 65 mph cruise 

cycle. The basis for this change may be seen in the memorandum to Docket EPA-HQOAR-2010-0162, which describes the data set used to describe real world vehicle 

performance. In addition to this modification, the Power-Take-Off (PTO) operation will 

be characterized for vehicles utilizing a PTO system for which there is a benefit for use of 

the hybrid technology. The testing provisions for the comparison in the A to B testing for 

complete vehicle or post-transmission powerpack testing may be seen in 40 CFR 

1037.525. The testing provisions for work-specific pre-transmission evaluation using an 

engine based approach may be seen in 40 CFR 1036.525. 

(b) Demonstrating Compliance with the Final Standards

(i) CO2 and Fuel Consumption Standards

Model

As stated above, the technology basis for the final standards for vocational 

vehicles is use of LRR tires. Similar to Class 7 and 8 combination tractors, compliance 

with the standards will be demonstrated using the GEM predictive model. However, the 

input parameters entered by the vehicle manufacturer would be limited to the properties 
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of the tires. The GEM will use the tire data, along with inputs reflecting a baseline truck 

and engine, to generate a complete vehicle model. The test weight used in the model will 

be based on the vehicle class, as identified above. Light-heavy-duty vehicles will have a 

test weight of 16,000 pounds; 25,150 pounds for medium heavy-duty vehicles; and heavy 

heavy-duty vocational vehicles will use a test weight of 67,000 pounds. The model would 

then be exercised over the HHDDT transient cycle as well as 55 and 65 mph steady-state 

cruise conditions. The results of each of the three tests would be weighted at 16%, 9%, 

and 75% for 65 mph, 55 mph, and transient tests, respectively. Innovative technology 

credits may be used to demonstrate compliance, however because the technology would

not be an input into GEM, alternative procedures would be needed to determine the value 

of the credit as described in Preamble Section IV.

It may seem more expedient and just as accurate to require manufacturers use 

tires meeting certain industry standards for qualifying tires as having LRR. In addition, 

CO2 and fuel consumption benefits could be quantified for different ranges of coefficients 

of rolling resistance to provide a means for comparison to the standard. However, we 

believe that as technology advances, other aspects of vocational vehicles may warrant 

inclusion in future rulemakings. For this reason, we remain committed to having the 

certification framework in place to accommodate such additions. While the modeling 

approach may seem to be overly complicated for this phase of the rules, it also serves to 

create a certification pathway for future rulemakings and therefore we believe this is the 

best approach. Moreover, a design standard would discourage use of alternative 

technologies to meet the standard, and otherwise impede desirable flexibility . 

In-use Standards

The category of wear items primarily relates to tires. It is expected that vehicle 

manufacturers will equip their trucks with LRR tires, since the final vehicle standard is 

predicated on LRR tire performance. The tire replacement intervals for this class of 

vehicle is normally in the range of 50,000 to 100,000 miles, which means the 

owner/operator will be replacing the tires at several points within the useful life of the 

vehicle. We believe that as LRR tires become more common on new equipment, the 

aftermarket prices of these tires will also decrease. Along with decreasing tire prices, the 

fuel savings realized through use of LRR tires will ideally provide enough incentive for 

owner/operators to continue purchasing these tires. The inventory modeling in this 

rulemaking package reflects the continued use of LRR tires through the life of the 

vehicle. 

(ii) Evaporative Emission Standards

Evaporative and refueling emissions from heavy-duty highway engines and 

vehicles are currently regulated under 40 CFR part 86. Even though these emission 

standards apply to the same engines and vehicles that must meet exhaust emission 

standards, we require a separate certificate for complying with evaporative and refueling 

emission standards. An important related point to note is that the evaporative and 

refueling emission standards always apply to the vehicle, while the exhaust emission 

standards may apply to either the engine or the vehicle. For vehicles other than pickups 
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and vans, the standards in this program to address greenhouse gas emissions apply

separately to engines and to vehicles. Since we will be applying both greenhouse gas 

standards and evaporative/refueling emission standards to vehicle manufacturers, we 

believe it will be advantageous to have the regulations related to their certification 

requirements written together as much as possible. EPA regards these final changes as 

discrete, minimal, and for the most part clarifications to the existing standards. We have 

not finalized any changes to the evaporative or refueling emission standards, but we have 

come across several provisions that warrant clarification or correction: 

 When adopting the most recent evaporative emission change we did not carry through 

the changes to the regulatory text applying evaporative emission standards for 

methanol-fueled compression-ignition engine. The final regulations correct this by

applying the new standards to all fuels that are subject to standards.

 We are finalizing provisions to address which standards apply when an auxiliary

(nonroad) engine is installed in a motor vehicle, which is currently not directly 

addressed in the highway regulation. The final approach requires testing complete 

vehicles with any auxiliary engines (and the corresponding fuel-system components). 

Incomplete vehicles must be tested without the auxiliary engines, but any such 

engines and the corresponding fuel system components will need to meet the 

standards that apply under our nonroad program as specified in 40 CFR part 1060.

 We have removed the option for secondary vehicle manufacturers to use a larger fuel 

tank capacity than is specified by the certifying manufacturer without re-certifying 

the vehicle. Secondary vehicle manufacturers needing a greater fuel tank capacity 

will need to either work with the certifying manufacturer to include the larger tank, or 

go through the effort to re-certify the vehicle itself. Our understanding is that this 

provision has not been used and would be better handled as part of certification rather 

than managing a separate process. We are also finalizing corresponding changes to 

the emission control information label.

 Rewriting the regulations in a new part in conjunction with the greenhouse gas 

standards allows for some occasions of improved organization and clarity, as well as 

updating various provisions. For example, we have finalized a leaner description of 

evaporative emission families that does not reference sealing methods for carburetors 

or air cleaners. We have also clarified how evaporative emission standards affect 

engine manufacturers and are finalizing more descriptive provisions related to 

certifying vehicles above 26,000 pounds GVWR using engineering analysis.

 Since we adopted evaporative emission standards for gaseous-fuel vehicles, we have 

developed new approaches for design-based certification (see, for example, 40 CFR 

1060.240). We request comment on changing the requirements related to certifying 

gaseous-fuel vehicles to design-based certification. This would allow for a simpler 

assessment for certifying these vehicles without changing the standards that apply.

(2) Final Labeling Provisions

It is crucial that a means exist for allowing field inspectors to identify whether a 

vehicle is certified, and if so, whether it is in the certified configuration. As with engines 
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and tractors, we believe an emission control information label is a logical first step in 

facilitating this identification. For vocational vehicles, the engine will have a label that is 

permanently affixed to the engine and identify the engine as certified for use in a certain 

regulatory subcategory of vehicle (i.e., MHD, etc). 

The vehicle will also have a label listing the manufacturer of the vehicle, vehicle 

family (and subfamily, if applicable), regulatory subcategory, date of manufacture, 

compliance statement, FEL, and emission control system identifiers. The required 

content of this label is consistent with the label description provided earlier for Class 7 

and 8 tractors. Since LRR tires are expected to be the primary means for vehicles to 

comply, it is expected that LRR tires will be the only component identified as part of the 

emission control system on the label. For tires to qualify as low rolling resistance (for 

purposes of this vocational vehicle label), they need to have a coefficient of rolling 

resistance at or below 7.7 kg/metric ton. In addition, if any other emission related 

components are present, such as hybrid powertrains, key components will also need to be 

specified on the label. Like the engine label, this will need to be permanently affixed to 

the vehicle in an area that is clearly visible to the owner/operator. At the time of 

certification, manufacturers will be required to submit an example of their vehicle 

emission control label such that EPA can verify that all critical elements are present. In 

addition to the label, manufacturers will also need to describe where the unique vehicle 

identification number and date of production can be found on the vehicle.

(3) Other Certification Issues

Warranty

As with other heavy-duty engine and vehicle regulatory categories, vocational 

vehicle chassis manufacturers would be required to warrant their product to be free from 

defects that would result in noncompliance with emission standards. This warranty also 

covers the failure of emission related components for the warranty period of the vehicle. 

For vocational vehicles, this primarily applies to tires. 

Manufacturers of chassis for vocational vehicles would be required to warrant 

tires to be free from defects at the time of initial sale. As with Class 7 and 8 combination 

tractors, we expect the chassis manufacturer to only warrant the original tires against 

manufacturing or design-related defects. This tire warranty would not cover replacement 

tires or damage from road hazards or improper inflation. 

As with Class 7 and 8 combination tractors, all warranty documentation would be 

submitted to EPA at the time of certification. This should include the warranty statement 

provided to the owner/operator, description of the service repair network, list of covered 

components (both conventional and high-cost), and length of coverage.

EPA Certification Fees

Similar to engine and tractor-trailer vehicle certification, the agency will assess 

certification fees for vocational vehicles. The proceeds from these fees are used to fund 

the compliance and certification activities related to GHG regulation for this industry
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segment. In addition to the certification process, other activities funded by certification 

fees include EPA-administered in-use testing, selective enforcement audits, and 

confirmatory testing. At this point, the exact costs associated with the heavy-duty vehicle 

GHG compliance are not well known. EPA will assess its compliance program associated 

with this program and assess the appropriate level of fees. We anticipate that fees will be 

applied based on certification families, following the light-duty vehicle approach.

Maintenance

Vehicle manufacturers are required to outline a maintenance schedule that ensures

the emission control system remains functional throughout the useful life of the vehicle. 

For vocational vehicles, this largely involves ensuring that customers have sufficient 

information to purchase replacement tires that meet or exceed original equipment 

specifications. As with Class 7 and 8 tractors, we believe that this information should be 

included in the owner’s manual to the vehicle. This statement must be submitted to EPA 

at the time of certification to verify that the customer indeed has enough information to 

purchase the correct replacement tires. 

F. General Regulatory Provisions

(1) Statutory Prohibited Acts

Section 203 of the CAA describes acts that are prohibited by law. This section 

and associated regulations apply equally to the greenhouse gas standards as to any other

regulated emission. Acts that are prohibited by section 203 of the CAA include the 

introduction into commerce or the sale of an engine or vehicle without a certificate of 

conformity, removing or otherwise defeating emission control equipment, the sale or

installation of devices designed to defeat emission controls, and other actions. In

addition, vehicle manufacturers, or any other party, may not make changes to the certified 

engine that would result in it not being in the certified configuration. 

EPA will apply §86.1854–12 to heavy-duty vehicles and engines; this codifies the 

prohibited acts spelled out in the statute. Although it is not legally necessary to repeat 

what is in the CAA, EPA believes that including this language in the regulations provides 

clarity and improves the ease of use and completeness of the regulations. Since this 

change merely codifies provisions that already apply, there is no burden associated with 

the change.

(2) Regulatory Amendments Related to Heavy-Duty Engine Certification

We are adopting the new engine-based greenhouse gas emissions standards in 40 

CFR part 1036 and the new vehicle-based standards in 40 CFR part 1037. We are 

continuing to rely on 40 CFR parts 85 and 86 for conventional certification and 

compliance provisions related to criteria pollutants, but the final regulations include a 

variety of amendments that will affect the provisions that apply with respect to criteria 

pollutants. We are not intending to change the stringency of, or otherwise substantively

change any existing standards.
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The introduction of new parts in the CFR is part of a long-term plan to migrate all 

the regulatory provisions related to highway and nonroad engine and vehicle emissions to 

a portion of the CFR called Subchapter U, which consists of 40 CFR parts 1000 through 

1299. We have already adopted emission standards, test procedures, and compliance 

provisions for several types of engines in 40 CFR parts 1033 through 1074. We intend 

eventually to capture all the regulatory requirements related to heavy-duty highway

engines and vehicles in these new parts. Moving regulatory provisions to the new parts 

allows us to publish the regulations in a way that is better organized, reflects updates to 

various certification and compliance procedures, provides consistency with other engine 

programs, and is written in plain language. We have already taken steps in this direction 

for heavy-duty highway engines by adopting the engine-testing procedures in 40 CFR 

part 1065 and the provisions for selective enforcement audits in 40 CFR part 1068.

EPA sought comment on drafting changes and additions. This solicitation related 

solely to the appropriate migration, translation, and enhancement of existing provisions. 

EPA did not solicit comment on the substance of these existing rules, and did not amend, 

reconsider, or otherwise re-examine these provisions’ substantive effect. 

The rest of this section describes the most significant of these final redrafting 

changes. The proposal includes several changes to the certification and compliance 

procedures, including the following:

 We are requiring that engine manufacturers provide installation 

instructions to vehicle manufacturers (see §1036.130). We expect this is 

already commonly done; however, the regulatory language spells out a 

complete list of information we believe is necessary to properly ensure 

that vehicle manufacturers install engines in a way that is consistent with 

the engine’s certificate of conformity.

 §1036.30, §1036.250, and §1036.825 spell out several detailed provisions 

related to keeping records and submitting information to us.

 We wrote the greenhouse gas regulations to divide heavy-duty engines 

into “spark-ignition” and “compression-ignition” engines, rather than 

“Otto-cycle” and “diesel” engines, to align with our terminology in all our 

nonroad programs. This will likely involve no effective change in 

categorizing engines except for natural gas engines. To address this 

concern, we are including a provision in §1036.150 to allow 

manufacturers to meet standards for spark-ignition engines if they were 

regulated as Otto-cycle engines in 40 CFR part 86, and vice versa. 

 §1036.205 describes a new requirement for imported engines to describe 

the general approach to importation (such as identifying authorized agents 

and ports of entry), and identifying a test lab in the United States where 

EPA can perform testing on certified engines. These steps are part of our 

ongoing effort to ensure that we have a compliance and enforcement 

program that is as effective for imported engines as for domestically 
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produced engines. We have already adopted these same provisions for 

several types of nonroad engines.

 §1036.210 specifies a process by which manufacturers are able to get 

preliminary approval for EPA decisions for questions that require lead 

time for preparing an application for certification. This might involve, for 

example, preparing a plan for durability testing, establishing engine 

families, identifying adjustable parameters, and creating a list of scheduled 

maintenance items.

 §1036.225 describes how to amend an application for certification.

 We are revising 40 CFR 85.1701 to apply the exemption provisions 

described in 40 CFR part 1068 to heavy-duty highway engines starting in 

2014. Manufacturers may optionally use the exemption provisions from 

part 1068 earlier. This involves only very minor changes in the terms and 

conditions associated with the various types of exemptions. This change 

will help us to implement a consistent compliance program for all engine 

and vehicle categories. We are similarly revising 40 CFR 85.1511 to 

reference the importation-related exemptions in part 1068 for all motor 

vehicles and motor vehicle engines.

 We are finalizing a provision allowing manufacturers to use the defect 

reporting provisions of 40 CFR part 1068 instead of those in 40 CFR part 

85. This involves setting thresholds for investigating and reporting defects 

based on defect rates rather than absolute numbers of defects. Once we 

gain more experience with applying the defect-reporting provisions in 40 

CFR part 1068 for motor vehicles, we will consider making those 

provisions mandatory, including any appropriate adjustments.

In addition, we are revising 40 CFR 1068.210 and 1068.325 to address a concern 

raised by engine manufacturers. The provisions for importing engines under a temporary 

exemption disallow selling exempted engines even though some of the situations 

addressed depend on engine sales (such as delegated assembly). We have added 

clarifying language to the individual exemptions to describe whether or how engines may

be sold or leased. In the case of the testing exemption in §1068.210, this involves a 

further change to specify how a manufacturer must track the status and final disposition

of exempted engines or equipment. We are also making a small change to the testing 

exemption to remove the administrative step of requiring an exchange of signed 

documents for the exemption to be effective. This will streamline the process for the 

testing exemption and make it more like that for other types of exemptions.

(3) Test Procedures for Measuring Emissions from Heavy-Duty Vehicles

We are finalizing a new part 1066 that contains general chassis-based test 

procedures for measuring emissions from a variety of vehicles, including vehicles over 

14,000 pounds GVWR. However, we are not finalizing application of these procedures 
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broadly at this time. The test procedures in 40 CFR part 86 continue to apply for vehicles 

under 14,000 pounds GVWR. The final part 1066 procedures applies only for any testing 

that would be required for larger vehicles. This could include “A to B” hybrid vehicle 

testing, coastdown testing, and potentially limited innovative technology testing. 

Nevertheless, we will likely consider in the future applying these procedures also for 

other heavy-duty vehicle testing and for light-duty vehicles, highway motorcycles, and/or 

nonroad recreational vehicles that rely on chassis-based testing.

As noted above, engine manufacturers are already using the test procedures in 40 

CFR part 1065 instead of those originally adopted in 40 CFR part 86. The new 

procedures are written to apply generically for any type of engine and include the current 

state of technology for measurement instruments, calibration procedures, and other 

practices. We are finalizing the chassis-based test procedures in part 1066 to have a 

similar structure. 

The final procedures in part 1066 reference large portions of part 1065 to align 

test specifications that apply equally to engine-based and vehicle-based testing, such as 

CVS and analyzer specifications and calibrations, test fuels, calculations, and definitions 

of many terms. Since several highway engine manufacturers were involved in 

developing the full range of specified procedures in part 1065, we are confident that 

many of these provisions are appropriate without modification for vehicle testing. 

The remaining test specifications needed in part 1066 are mostly related to setting 

up, calibrating, and operating a chassis dynamometer. This also includes the coastdown 

procedures that are required for establishing the dynamometer load settings to ensure that 

the dynamometer accurately simulates in-use driving.

Current testing requirements related to dynamometer specifications rely on a 

combination of regulatory provisions, EPA guidance documents, and extensive knowhow from industry experience that has led to a good understanding of best practices for 

operating a vehicle in the laboratory to measure emissions. We attempted in this 

rulemaking to capture this range of material, organizing these specifications and 

verification and calibration procedures to include a complete set of provisions to ensure 

that a dynamometer meeting these specifications would allow for carefully controlled 

vehicle operation such that emission measurements are accurate and repeatable.

The procedures are written with the understanding that heavy-duty highway 

manufacturers have, and need to have, single-roll electric dynamometers for testing. We 

are aware that this is not the case for other applications, such as all-terrain vehicles. We 

are not adopting specific provisions for testing with hydrokinetic dynamometers, we are 

already including a provision acknowledging that we may approve the use of 

dynamometers meeting alternative specifications if that is appropriate for the type of 

vehicle being tested and for the level of stringency represented by the corresponding 

emission standards.

Drafting a full set of test specifications highlights the mixed use of units for 

testing. Some chassis-based standards and procedures are written based largely on the 
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International System of Units (SI), such as gram per kilometer (g/km) standards and 

kilometers per hour (kph) driving, while others are written based largely on English units 

(g/mile standards and miles per hour driving). The proposal includes a mix of SI and 

English units with instructions about converting units appropriately. However, most of 

the specifications and examples are written in English units. While this seems to be the 

prevailing practice for testing in the United States, we understand that vehicle testing 

outside the United States is almost universally done in SI units. In any case, 

dynamometers are produced with the capability of operating in either English or SI units. 

We believe there would be a substantial advantage toward the goal of achieving globally 

harmonized test procedures if we would write the test procedures based on SI units. This 

would also in several cases allow for more straightforward calculations, and reduced risk 

of rounding errors. For comparison, part 1065 is written almost exclusively in SI units. 

We sought comment on the use of units throughout part 1066. At this time we are not 

finalizing changes from our current approach.

A fundamental obstacle toward using SI units is the fact that some duty cycles are 

specified based on speeds in miles per hour. To address this, it would be appropriate to 

convert the applicable driving schedules to meter-per-second (m/s) values. Converting 

speeds to the nearest 0.01 m/s would ensure that the prescribed driving cycle does not 

change with respect to driving schedules that are specified to the nearest 0.1 mph. The 

regulations would include the appropriate mph (or kph) speeds to allow for a ready 

understanding of speed values (see 40 CFR part 1037, Appendix I). This would, for 

example, allow for drivers to continue to follow a mph-based speed trace. The ±2 mph 

tolerance on driving speeds could be converted to ±1.0 m/s, which corresponds to an 

effective speed tolerance of ±2.2 mph. This may involve a tightening or loosening of the 

existing speed tolerance, depending on whether manufacturers used the full degree of 

flexibility allowed for a mph tolerance value that is specified without a decimal place. 

Similarly, the Cruise cycles for heavy-duty vehicles could be specified as 24.5±0.5 m/s 

(54.8±1.1 mph) and 29.0±0.5 m/s (64.9±1.1 mph).

(4) Compliance Reports

(a) Early Model Year Data

This information is the same as for tractors early model year data in Section V.D(4)(a).

(b) Final Reports

This information is the same as for tractors final reports in Section V.D(4)(b).

(c) Additional Required Information 

Table V-7 below provides a summary of the types of requests, required 

application submission dates and the EPA and NHTSA regulations that apply. 
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Table V-7: Summary of Required Information for Compliance

Submission Applies to Required 

Submissions Date

EPA 

Regulation 

Reference

NHTSA 

Regulation 

Reference

Small 

business 

exemptions

Vehicle or engine 

manufacturers meeting 

the Small Business 

Administration (SBA) 

size criteria of a small 

business as described in 

13 CFR 121.201.

Before introducing 

any excluded vehicle 

into U.S. commerce

§1037.150 §535.8

Incentives 

for early

introduction

The provisions apply

with respect to tractors 

and vocational vehicles 

produced in model 

years before 2014 

EPA must be notified 

before the 

manufacturer submits 

it applications for 

certificates of 

conformity

§1037.150 §535.8

Air condition 

leakage 

exemption 

for 

vocational 

vehicles

Vocational Vehicles 

excluded from § 

1037.115 

EPA must be notified 

before the 

manufacturer submits 

it applications for 

certificates of 

conformity

§1037.150 §535.8

Model year 

2014 N2O 

standards. 

Manufacturers that 

choose to show 

compliance with the 

MY 2014 N2O 

standards requesting to 

use an engineering 

analysis

EPA must be notified 

before the 

manufacturer submits 

it applications for 

certificates of 

conformity

§1037.150 §535.8

Exemption 

for electric 

vehicles

All electric vehicles are 

deemed to have zero 

exhaust emissions of 

CO2, CH4, and N2O

End of December 

prior to model year

§1037.150 §535.8

Off-road 

exemption

Manufacturers wanting 

to exclude vocational 

vehicles from vehicle 

standards

EPA must be notified 

before the 

manufacturer submits 

it applications for 

certificates of 

conformity

§1037.150 §535.8

Exemption 

from EOY 

reports

Manufactures with 

surplus credits at the 

end of the model year

90-days after the 

calendar year ends

§1037.730 §535.8
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G. Penalties

(1) Overview

In the NPRM, NHTSA proposed to assess civil penalties for non-compliance with 

fuel consumption standards. NHTSA’s authority under EISA, as codified at 49 U.S.C. 

32902(k), requires the agency to determine appropriate measurement metrics, test 

procedures, standards, and compliance and enforcement protocols for HD vehicles. 

NHTSA interprets its authority to develop an enforcement program to include the 

authority to determine and assess civil penalties for noncompliance that would impose 

penalties based on the following discussions. 

In cases of noncompliance, the agency explained in the NPRM that it would 

establish civil penalties based on consideration of the following factors:

 Gravity of the violation

 Size of the violator’s business

 Violator’s history of compliance with applicable fuel consumption standards

 Actual fuel consumption performance related to the applicable standard

 Estimated cost to comply with the regulation and applicable standard

 Quantity of vehicles or engines not complying

 Civil penalties paid under CAA section 205 (42 U.S.C. 7524) for noncompliance for the same vehicles or engines

NHTSA proposed to consider these factors in determining civil penalties in order 

to help ensure, given the agency’s wide discretion, that penalties would be fair and 

appropriate, and not duplicative of EPA penalties. The NPRM expressly stated that 

neither agency intended to impose duplicative civil penalties, and that both agencies 

would give consideration to civil penalties imposed by the other in the case of noncompliance with its own regulations. See NPRM at 74280. 

EMA, Volvo, the Truck Renting and Leasing Association (TRALA), and Navistar 

nevertheless commented that a dual enforcement scheme with separate NHTSA and EPA 

penalties could result in duplicative penalties, as manufacturers could be assessed 

penalties twice for the same violation. 

The possibility of more than one prosecution or enforcement action arising from 

the same overall body of facts does not present a novel issue. It commonly arises where 

there is overlapping jurisdiction, such as where the federal government and a state 

government have jurisdiction. The issue of multiple or sequential prosecutions may be 

addressed as a matter of administrative policy and discretion.319 

 

319 A well-known example is the Department of Justice’s petite policy, an internal guide on whether to 

pursue federal prosecution after a state prosecution. The petite policy is considered “merely a 
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Both NHTSA and EPA are charged with regulating medium-duty and heavy-duty 

trucks; NHTSA regulates them under EISA and EPA regulates them under the CAA. 

Both agencies also have compliance review and enforcement responsibilities for their 

respective regulatory requirements. The same set of underlying facts may result in a

violation of EISA and a violation of the CAA. The agencies recognize the above

concerns, and intend to address them through appropriate consultation. The details of the 

consultation and coordination between the agencies regarding enforcement will be set 

forth in a memorandum of understanding to be developed by EPA and NHTSA. 

NHTSA believes that the above description adequately describes the process by

which civil penalties may be assessed by both agencies. Therefore, for the final action, 

penalties for a violation of a fuel consumption standard will be based on the gravity of the 

violation, the size of the violator’s business, the violator’s history of compliance with 

applicable fuel consumption standards, the actual fuel consumption performance related 

to the applicable standard, the estimated cost to comply with the regulation and 

applicable standard, and the quantity of vehicles or engines not complying. The 

collaborative enforcement process will ensure that the total penalties assessed will not be 

duplicative or excessive. 

NHTSA would also like to clarify that the “estimated cost to comply with the 

regulation and applicable standard,” will be used to ensure that penalties for noncompliance will not be less than the cost of compliance. It would be contrary to the 

purpose of the regulation for the penalty scheme to incentivize noncompliance. 

The final civil penalty amount NHTSA could impose would not exceed the limit 

that EPA is authorized to impose under the CAA. The potential maximum civil penalty

for a manufacturer would be calculated as follows in Equation V-1:

Equation V-1: Aggregate Maximum Civil Penalty

Aggregate Maximum Civil Penalty for a Non-Compliant Regulatory Category = (CAA Limit) x 

(production volume within the regulatory category)

EPA has occasionally in the past conducted rulemakings to provide for 

nonconformance penalties-- monetary penalties that allow a manufacturer to sell engines 

or vehicles that do not meet an emissions standard. Nonconformance penalties are 

authorized for heavy-duty engines and vehicles under section 206(g) of the CAA. Three 

basic criteria have been established by rulemaking for determining the eligibility of 

emissions standards for nonconformance penalties in any given model year: (1) the 

emissions standard in question must become more difficult to meet, (2) substantial work 

must be required in order to meet the standard, and (3) a technological laggard must be 

likely to develop (40 CFR 86.1103-87). A technological laggard is a manufacturer who 

cannot meet a particular emissions standard due to technological (not economic) 

difficulties and who, in the absence of nonconformance penalties, might be forced from 

the marketplace. The process to determine if these criteria are met and to establish 

 

housekeeping provision,” and prosecution remains entirely within the Department’s discretion. U.S. v. 

Barrett, 496 F.3d 1079, 1120 (10th Cir. 2007).
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penalty amounts and conditions is carried out via rulemaking, as required by the CAA. 

The CAA (in section 205) also lays out requirements for the assessment of civil penalties 

for noncompliance with emissions standards.

As discussed in detail in Section III, the agencies have determined that the final 

GHG and fuel consumption standards are readily feasible, and we do not believe a 

technological laggard will emerge in any sector covered by these final standards. In 

addition to the standards being premised on use of already-existing, cost-effective 

technologies, there are a number of flexibilities and alternative standards built into the 

proposal. However, in the case of potential non-conformance, civil penalties will ensure 

that adequate deterrence for non-conformance exists. 

(2) NHTSA’s Penalty Process

NHTSA proposed a detailed enforcement process in the NPRM. As proposed, 

enforcement would begin with a notice of violation, after which the respondent may 

either pay the penalty proposed in the notice of violation or dispute it by requesting an 

agency hearing. For a party that did not pay the proposed penalty or request a hearing 

within 30 days of the notice of violation, a finding of default would be entered and the 

penalty set forth in the notice of violation assessed. If a hearing is timely requested, the 

respondent would receive written notice of the time, date and location of the hearing. 

The respondent would have the right to counsel and to examine, respond to and rebut 

evidence presented by the Chief Counsel. If civil penalties greater than $250,000,000 

were assessed in the Hearing Officer’s final order, that order would contain a statement 

advising the party of the right to appeal to the NHTSA Administrator. In the event of a 

timely appeal, the decision of the Administrator would be a final agency action. This 

structure was intended to ensure that a party was afforded ample opportunity to be heard.

Several manufacturers commented that NHTSA’s penalty procedures should be 

more formal than was proposed in the NPRM. EMA, Volvo and Navistar commented 

that the penalty procedures should be subject to the Administrative Procedure Act (APA) 

review requirements. EMA, Volvo and Navistar, and TRALA commented that the 

penalty procedures violated due process requirements. EMA argued that NHTSA must 

expressly grant a right to judicial review, and EMA and Navistar argued that the absence 

of an administrative appeals process for penalties under $250,000,000 would violate due 

process. Volvo faulted NHTSA for not classifying the hearing officer’s decision as a final 

agency action, and stated that specifications regarding who could be a hearing officer 

should align with those specified for the light-duty program, which was laid out in 49 

CFR Section 511.3.

As noted in the NPRM, the APA administrative hearing requirements of Sections 

554, 556, and 557 are not required where formal procedures are not required by statute 

(generally, the organic statute must provide that the administrative proceeding must be an 

adjudication, determined on the record after the opportunity for an agency hearing, 

sometimes referenced as an opportunity for hearing on the record). See e.g., 5 U.S.C. 

Section 554. Where a formal adjudication is not required by statute, in general, agencies 

adopt and apply informal processes. While the compliance, civil penalty and appeals 
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provisions of 49 U.S.C. Sections 32911 and 32914 require formal adjudication in 

accordance with APA requirements, those sections only apply to the light-duty fuel 

economy program. In contrast, for the heavy-duty program of Section 32902(k), the 

Congress did not require formal adjudication in accordance with the APA. Therefore, 

informal adjudication procedures may be applied. NHTSA will not adopt the procedures 

of by 5 U.S.C. Sections 554, 556, or 557 for the final rule.

While the APA requirements for formal hearing procedures do not apply to 

NHTSA’s enforcement under Section 32902(k), due process requirements do apply.

NHTSA believes that formal procedures are neither required by statute nor necessary for 

this enforcement process to meet due process requirements. NHTSA expects that the 

cases will not be complex. In general, there will be one or two issues: (1) compliance 

with the regulations and, if not, (2) the appropriate civil penalty. Compliance likely will 

involve narrow technical questions under the regulations being adopted today. Noncompliance with applicable fuel consumption standards will be determined by utilizing 

the certified and reported CO2 emissions and fuel consumption data provided by EPA as 

described in this part, and after considering all the flexibilities available under 

Section 535.7. Much of the evidence will be materials developed by the respondent. 

There likely will not be wide ranging issues. The parties will have ample opportunity to 

present their positions. A hearing officer can readily address the sorts of questions that 

are likely to arise. Second, if there is a noncompliance, there will be the question of the 

appropriate penalty. NHTSA’s regulations contain factors to be considered in assessing 

penalties. Again, the parties will have ample opportunity to present their positions. 

Ultimately, the agency’s final decision must be sufficiently reasoned to withstand judicial 

review, based on the arbitrary and capricious standard. 

To address commenters’ concerns about the process provided, NHTSA made 

several adjustments and clarifications in the final rule. The final rule provides that there 

will be a written decision of the Hearing Officer, and the assessment of a civil penalty by

a hearing officer shall be set forth in an accompanying final order. Together, these 

constitute the final agency action. NHTSA has also revisited the minimum penalty level 

for an administrative appeal to the NHTSA Administrator and decided to lower the level 

significantly, to $1,000,000. This provides a second level of review. NHTSA believes 

this will promote an efficient use of administrative remedies and a further opportunity to 

be heard at the administrative level. Of course, if a party files an appeal with the NHTSA 

Administrator, the Hearing Officer’s decision and order at that juncture shall no longer be 

final agency action. 

NHTSA has considered the specifications of the Hearing Officer and determined 

that they are adequate for informal agency hearings of this nature. However, the agency

will add a clarification to the final rule that specifies that the Hearing Officer will be 

appointed by the Administrator. Further, in addition to having no prior connection with 

the case and no responsibility, direct or supervisory, for the investigation of cases 

referred for the assessment of civil penalties, the Hearing Officer will have no duties 

related to the light-duty fuel economy or medium- and heavy-duty fuel efficiency

programs. 
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NHTSA has also considered EMA’s comment that a right to judicial review must 

be specified in the regulatory text. The agency does not agree with this concern. Parties, 

of course, cannot confer jurisdiction; only Congress can do so. Whitman v. Department 

of Transportation, 547 U.S. 512, 514 (2006); Weinberger v. Bentex Pharmaceuticals, 

Inc., 412 U.S. 645, 652 (1973). Moreover, judicial review of a final agency action is 

presumed. United States v. Fausto, 484 U.S. 439, 452 (1998), citing Abbot Laboratories 

v. Gardner, 387 U.S. 136, 140 (1967). See generally, 28 U.S.C. Section 1331. Therefore, 

NHTSA has determined that the right to judicial review does not need to be specified in 

the regulatory text.

VI. How Will This Program Impact Fuel Consumption, GHG 

Emissions, and Climate Change?

A. What Methodologies Did the Agencies Use to Project GHG 

Emissions and Fuel Consumption Impacts?

EPA and NHTSA used EPA’s official mobile source emissions inventory model 

named Motor Vehicle Emissions Simulator (MOVES2010),

320 to estimate emission and 

fuel consumption impacts of these final rules. MOVES has the capability to take in user 

inputs to modify default data to better estimate emissions for different scenarios, such as 

different regulatory alternatives, state implementation plans (SIPs), geographic locations, 

vehicle activity, and microscale projects. 

The agencies performed multiple MOVES runs to establish reference case and 

control case emission inventories and fuel consumption values. The agencies ran 

MOVES with user input databases that reflected characteristics of the final rules, such as 

emissions improvements and recent sales projections. Some post-processing of the model 

output was required to ensure proper results. The agencies ran MOVES for non-GHGs, 

CO2, CH4, and N2O for calendar years 2005, 2018, 2030, and 2050. Additional runs were 

performed for just the three greenhouse gases and for fuel consumption for every

calendar year from 2014 to 2050, inclusive, which fed the economy-wide modeling, 

monetized greenhouse gas benefits estimation, and climate impacts analyses.

The agencies also used MOVES to estimate emissions and fuel consumption 

impacts for the other alternatives considered and described in Section IX.

 

320 MOVES homepage: http://www.epa.gov/otaq/models/moves/index.htm. Version MOVES2010 was 

used for emissions impacts analysis for this action. Current version as of September 14, 2010 is an updated 

version named MOVES2010a, available directly from the MOVES homepage. To replicate results from 

this action, MOVES2010 must be used.
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B. MOVES Analysis

(1) Inputs and Assumptions

The analysis performed for the final action mirrors what was done for the 

proposal. The methods and models are the same, with differences lying primarily in the 

inputs, as a result of updates in the program, standards, and baseline data.

(a) Reference Run Updates

Since MOVES2010a vehicle sales and activity data were developed from 

AEO2009, EPA first updated these data using sales and activity estimates from 

AEO2011. MOVES2010a defaults were used for all other parameters to estimate the 

reference case emissions inventories. 

(b) Control Run Updates

EPA developed additional user input data for MOVES runs to estimate control 

case inventories. To account for improvements of engine and vehicle efficiency, EPA 

developed several user inputs to run the control case in MOVES. As explained at 

proposal, since MOVES does not operate based on Heavy-duty FTP cycle results, EPA 

used the percent reduction in engine CO2 emissions expected due to the final rules to 

develop energy inputs for the control case runs. 75 FR at 74280. Also, EPA used the 

percent reduction in aerodynamic drag and tire rolling resistance coefficients and 

reduction in average total running weight (gross combined weight) expected from the 

final rules to develop road load input for the control case. The sales and activity data 

updates used in the reference case were used in the control case. Details of all the 

MOVES runs, input data tables, and post-processing steps are available in the docket 

(EPA-HQ-OAR-2010-0162).

Table VI-1 and Table VI-2 describe the estimated expected reductions from these 

final rules, which were input into MOVES for estimating control case emissions 

inventories.

Table VI-1: Estimated Reductions in Engine CO2 Emission Rates321

GVWR Class Fuel Model Years CO2 Reduction from 

2010 MY

HHD (8a-8b) Diesel 2014-2016 3%

2017+ 6%

MHD (6-7) and LHD 4-5 Diesel 2014-2016 5%

2017+ 9%

Gasoline 2016+ 5%

 

321 Section II of this preamble discusses an alternative engine standard for the HD diesel engines in the 

2014, 2015, and 2016 model years. To the extent that engines using this alternative are expected to have 

baseline emissions greater than the industry average, the reduction from the industry average projected in 

this program would be reduced.
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Table VI-2: Estimated Reductions in Rolling Resistance Coefficient, Aerodynamic Drag Coefficient, 

and Gross Combined Weight

Truck type Reduction in Tire 

CRR from Baseline

Reduction in Cd

from Baseline

Weight 

reduction (lbs.)

Combination long-haul 9.6% 12.1% 400 

Combination shorthaul7.0% 5.9% 321

Straight trucks, refuse 

trucks, motor homes, 

transit buses, and other 

vocational vehicles

5.0% 0% 0

Since nearly all HD pickup trucks and vans will be certified on a chassis 

dynamometer, the CO2 reductions for these vehicles will not be represented as engine and 

road load reduction components, but rather as total vehicle CO2 reductions. These 

estimated reductions are described in Table VI-3.

Table VI-3: Estimated Total Vehicle CO2 Reductions for HD Pickup Trucks and Vans

GVWR Class Fuel Model year CO2 Reduction from 

Baseline

HD Pickup 

Trucks and Vans

Gasoline 2014 1.5%

2015 2%

2016 4%

2017 6%

2018+ 10%

Diesel 2014 2.3%

2015 3%

2016 6%

2017 9%

2018+ 15%

C. What Are the Projected Reductions in Fuel Consumption and GHG 

Emissions?

EPA and NHTSA expect significant reductions in GHG emissions and fuel 

consumption from these final rules – emission reductions from both downstream 

(tailpipe) and upstream (fuel production and distribution) sources, and fuel consumption 

reductions from more efficient vehicles. Increased vehicle efficiency and reduced vehicle 

fuel consumption will also reduce GHG emissions from upstream sources. The following 
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subsections summarize the GHG emissions and fuel consumption reductions expected 

from these final rules.

(1) Downstream (Tailpipe)

Consistent with the proposal, EPA used MOVES to estimate downstream GHG 

inventories from these final rules. We expect reductions in CO2 from all heavy-duty 

vehicle categories. The reductions come from engine and vehicle improvements. EPA 

expects N2O emissions to increase very slightly because of a rebound in vehicle miles 

traveled (VMT) and because significant vehicle emissions reductions are not expected 

from these final rules. In the proposal, we did not account for differences in methane 

emissions from use of auxiliary power units (APUs) during extended idling from sleeper 

cab combination tractors. After accounting for these differences, EPA expects methane 

emissions to decrease primarily due to differences in hydrocarbon emission 

characteristics between on-road diesel engines and APUs. The amount of methane 

emitted as a fraction of total hydrocarbons is significantly less for APUs than for diesel 

engines equipped with diesel particulate filters. Overall, downstream GHG emissions 

will be reduced significantly and are described in the following subsections. 

For CO2 and fuel consumption, the total energy consumption “pollutant” was run 

in MOVES rather than CO2 itself. The energy was converted to fuel consumption based 

on fuel heating values assumed in the Renewable Fuels Standard and used in the 

development of MOVES emission and energy rates. These values are 117,250 kJ/gallon 

for gasoline blended with ten percent ethanol (E10)322 and 138,451 kJ/gallon for diesel.323 

To calculate CO2, the agencies assumed a CO2 content of 8,576 g/gallon for E10 and 

10,180 g/gallon for diesel. Table VI-4 shows the fleet-wide GHG reductions and fuel 

savings from reference case to control case through the lifetime of model year 2014 

through 2018 heavy-duty vehicles. Table VI-5 shows the downstream GHG emissions 

reductions and fuel savings in 2018, 2030, and 2050. The analysis follows what was 

done for the proposal. We did not receive comments indicating that this analysis was 

inappropriate or insufficient for estimating downstream emissions impacts of this 

program.

 

322 Renewable Fuels Standards assumptions of 115,000 BTU/gallon gasoline (E0) and 76,330 BTU/gallon 

ethanol (E100) weighted 90% and 10%, respectively, and converted to kJ at 1.055 kJ/BTU.

323 MOVES2004 Energy and Emission Inputs. EPA420-P-05-003, March 2005. 

http://www.epa.gov/otaq/models/ngm/420p05003.pdf
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Table VI-4 Model Year 2014 through 2018 Lifetime GHG Reductions and Fuel Savings 

by Heavy-duty Truck Category 

Downstream GHG Reductions 

(MMT CO2eq)

Fuel Savings 

(billion gallons)

HD pickups/vans 18 1.9

Vocational 24 2.4

Combination short-haul 

(Day cabs)

50 4.9

Combination long-haul 

(Sleeper cabs)

135 12.9

Table VI-5: Annual Downstream GHG Emissions Reductions and Fuel Savings

in 2018, 2030, and 2050

Downstream GHG 

Reductions (MMT CO2eq)

Diesel Savings 

(million gallons)

Gasoline Savings 

(million gallons)

2018 22 2,123 59

2030 61 5,670 349

2050 89 8,158 522

(2) Upstream (Fuel Production and Distribution)

Using the same approach as used in the NPRM, the upstream GHG emission 

reductions associated with the production and distribution of fuel were projected using 

emission factors from DOE’s “Greenhouse Gases, Regulated Emissions, and Energy Use 

in Transportation” (GREET1.8) model, with some modifications consistent with the 

Light-Duty 2012-2016 MY vehicle rule. More information regarding these modifications 

can be found in the RIA Chapter 5. These estimates include both international and 

domestic emission reductions, since reductions in foreign exports of finished gasoline 

and/or crude make up a significant share of the fuel savings resulting from the GHG 

standards. Thus, significant portions of the upstream GHG emission reductions will 

occur outside of the United States; a breakdown and discussion of projected international 

versus domestic reductions is included in the RIA Chapter 5. GHG emission reductions 

from upstream sources can be found in Table VI-6.

Table VI-6: Annual Upstream GHG Emissions Reductions in 2018, 2030, and 2050

CO2 (MMT) CH4 (MMT 

CO2eq)

N2O (MMT 

CO2eq)

Total GHG (MMT 

CO2eq)

2018 5.1 0.9 0.02 6.0

2030 12.2 1.9 0.06 14.2

2050 16.4 2.5 0.08 19.0
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(3) HFC Emissions

Based on projected HFC emission reductions due to the final AC leakage 

standards, EPA estimates the HFC reductions to be 120,000 metric tons of CO2eq in 

2018, 440,000 metric tons of CO2eq emissions in 2030 and 600,000 metric tons CO2eq in 

2050, as detailed in RIA Chapter 5.3.4.

(4) Total (Upstream + Downstream + HFC)

Table VI-7 combines downstream results from Table VI-5, upstream results Table 

VI-6, and HFC results to show total GHG reductions for calendar years 2018, 2030, and 

2050.

Table VI-7: Annual Total GHG Emissions Reductions in 2018, 2030, and 2050

GHG Reductions (MMT CO2eq)

2018 29

2030 76

2050 108

D. Overview of Climate Change Impacts from GHG Emissions

Once emitted, GHGs that are the subject of this regulation can remain in the 

atmosphere for decades to millennia, meaning that 1) their concentrations become wellmixed throughout the global atmosphere regardless of emission origin, and 2) their 

effects on climate are long lasting. GHG emissions come mainly from the combustion of 

fossil fuels (coal, oil, and gas), with additional contributions from the clearing of forests 

and agricultural activities. Transportation activities, in aggregate, are the second largest 

contributor to total U.S. GHG emissions (27 percent of total emissions) despite a decline 

in emissions from this sector during 2008.

324

This section provides a summary of observed and projected changes in GHG 

emissions and associated climate change impacts. The source document for the section 

below is the Technical Support Document (TSD)325 for EPA’s Endangerment and Cause 

or Contribute Findings Under the Clean Air Act (74 FR 66496, December 15, 2009).

Below is the Executive Summary of the TSD which provides technical support for the 

endangerment and cause or contribute analyses concerning GHG emissions under section 

202(a) of the CAA. The TSD reviews observed and projected changes in climate based 

on current and projected atmospheric GHG concentrations and emissions, as well as the 

related impacts and risks from climate change that are projected in the absence of GHG 

mitigation actions, including this program and other U.S. and global actions. The TSD 

was updated and revised based on expert technical review and public comment as part of 

EPA’s rulemaking process for the final Endangerment Findings. The key findings 

 

324 U.S. EPA (2010) Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990–2007. EPA-430-R-10-

006, Washington, DC.

325 See Endangerment TSD, Note 10 above.
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synthesized here and the information throughout the TSD are primarily drawn from the 

assessment reports of the Intergovernmental Panel on Climate Change (IPCC), the U.S. 

Climate Change Science Program (CCSP), the U.S. Global Change Research Program 

(USGCRP), and NRC.326

In May 2010, the NRC published its comprehensive assessment, “Advancing the 

Science of Climate Change.”327 It concluded that “climate change is occurring, is caused 

largely by human activities, and poses significant risks for—and in many cases is already 

affecting—a broad range of human and natural systems.” Furthermore, the NRC stated 

that this conclusion is based on findings that are “consistent with the conclusions of 

recent assessments by the U.S. Global Change Research Program, the Intergovernmental 

Panel on Climate Change’s Fourth Assessment Report, and other assessments of the state 

of scientific knowledge on climate change.” These are the same assessments that served 

as the primary scientific references underlying the Administrator’s Endangerment 

Finding. Importantly, this recent NRC assessment represents another independent and 

critical inquiry of the state of climate change science, separate and apart from the 

previous IPCC and USGCRP assessments

(1) Observed Trends in Greenhouse Gas Emissions and Concentrations

The primary long-lived GHGs directly emitted by human activities include CO2, 

CH4, N2O, HFCs, PFCs, and SF6. Greenhouse gases have a warming effect by trapping 

heat in the atmosphere that would otherwise escape to space. In 2007, U.S. GHG 

emissions were 7,150 teragrams328 of CO2 equivalent329 (TgCO2eq). The dominant gas 

emitted is CO2, mostly from fossil fuel combustion. Methane is the second largest 

component of U.S. emissions, followed by N2O and the fluorinated gases (HFCs, PFCs, 

and SF6). Electricity generation is the largest emitting sector (34% of total U.S. GHG 

emissions), followed by transportation (27%) and industry (19%). 

Transportation sources under section 202(a)330 of the CAA (passenger cars, lightduty trucks, other trucks and buses, motorcycles, and passenger cooling) emitted 1,649 

TgCO2eq in 2007, representing 23% of total U.S. GHG emissions. U.S. transportation 

 

326 For a complete list of core references from IPCC, USGCRP/CCSP, NRC and others relied upon for 

development of the TSD for EPA’s Endangerment and Cause or Contribute Findings See section 1(b), 

specifically, Table 1.1 of the TSD Docket: EPA-HQ-OAR-2009-0171-11645. 

327 National Research Council (NRC) (2010). Advancing the Science of Climate Change. National 

Academy Press. Washington, DC.

328 One teragram (Tg) = 1 million metric tons. 1 metric ton = 1,000 kilograms = 1.102 short tons = 2,205 

pounds.

329 Long-lived GHGs are compared and summed together on a CO2-equivalent basis by multiplying each 

gas by its global warming potential (GWP), as estimated by IPCC. In accordance with United Nations 

Framework Convention on Climate Change (UNFCCC) reporting procedures, the U.S. quantifies GHG 

emissions in the official U.S. greenhouse gas inventory submission to the UNFCCC using the 100-year 

time frame values for GWPs established in the 1996 IPCC Second Assessment Report.

330 Source categories under Section 202(a) of the CAA are a subset of source categories considered in the 

transportation sector and do not include emissions from non-highway sources such as boats, rail, aircraft, 

agricultural equipment, construction/mining equipment, and other off-road equipment.
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sources under section 202(a) made up 4.3% of total global GHG emissions in 2005,331

which, in addition to the United States as a whole, ranked only behind total GHG 

emissions from China, Russia, and India but ahead of Japan, Brazil, Germany, and the 

rest of the world’s countries. In 2005, total U.S. GHG emissions were responsible for 

18% of global emissions, ranking only behind China, which was responsible for 19% of 

global GHG emissions. The scope of this final action focuses on GHG emissions under 

section 202(a) from heavy-duty source categories (see Section II). 

The global atmospheric CO2 concentration has increased about 38% from preindustrial levels to 2009, and almost all of the increase is due to anthropogenic emissions. 

The global atmospheric concentration of CH4 has increased by 149% since pre-industrial 

levels (through 2007); and the N2O concentration has increased by 23% (through 2007). 

The observed concentration increase in these gases can also be attributed primarily to 

anthropogenic emissions. The industrial fluorinated gases, HFCs, PFCs, and SF6, have 

relatively low atmospheric concentrations but the total radiative forcing due to these 

gases is increasing rapidly; these gases are almost entirely anthropogenic in origin. 

Historic data show that current atmospheric concentrations of the two most 

important directly emitted, long-lived GHGs (CO2 and CH4) are well above the natural 

range of atmospheric concentrations compared to at least the last 650,000 years. 

Atmospheric GHG concentrations have been increasing because anthropogenic emissions 

have been outpacing the rate at which GHGs are removed from the atmosphere by natural 

processes over timescales of decades to centuries.

(2) Observed Effects Associated With Global Elevated Concentrations of 

GHGs

Greenhouse gases, at current (and projected) atmospheric concentrations, remain 

well below published exposure thresholds for any direct adverse health effects and are 

not expected to pose exposure risks (i.e., from breathing/inhalation).

The global average net effect of the increase in atmospheric GHG concentrations, 

plus other human activities (e.g., land-use change and aerosol emissions), on the global 

energy balance since 1750 has been one of warming. This total net heating effect, 

referred to as forcing, is estimated to be +1.6 (+0.6 to +2.4) watts per square meter 

(W/m2), with much of the range surrounding this estimate due to uncertainties about the 

cooling and warming effects of aerosols. However, as aerosol forcing has more regional 

variability than the well-mixed, long-lived GHGs, the global average might not capture 

some regional effects. The combined radiative forcing due to the cumulative (i.e., 1750 to 

2005) increase in atmospheric concentrations of CO2, CH4, and N2O is estimated to be 

+2.30 (+2.07 to +2.53) W/m2. The rate of increase in positive radiative forcing due to 

these three GHGs during the industrial era is very likely to have been unprecedented in 

more than 10,000 years.

 

331 More recent emission data are available for the United States and other individual countries, but 2005 is 

the most recent year for which data for all countries and all gases are available.
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Warming of the climate system is unequivocal, as is now evident from 

observations of increases in global average air and ocean temperatures, widespread 

melting of snow and ice, and rising global average sea level. Global mean surface 

temperatures have risen by 1.3 ± 0.32F (0.74°C ± 0.18C) over the last 100 years. Nine

of the 10 warmest years on record have occurred since 2001. Global mean surface 

temperature was higher during the last few decades of the 20th century than during any

comparable period during the preceding four centuries. 

Most of the observed increase in global average temperatures since the mid-20th 

century is very likely due to the observed increase in anthropogenic GHG concentrations. 

Climate model simulations suggest natural forcing alone (i.e., changes in solar irradiance) 

cannot explain the observed warming. 

U.S. temperatures also warmed during the 20th and into the 21st century;

temperatures are now approximately 1.3°F (0.7°C) warmer than at the start of the 20th

century, with an increased rate of warming over the past 30 years. Both the IPCC332 and 

the CCSP reports attributed recent North American warming to elevated GHG 

concentrations. In the CCSP (2008) report,333 the authors find that for North America, 

“more than half of this warming [for the period 1951-2006] is likely the result of humancaused greenhouse gas forcing of climate change.” 

Observations show that changes are occurring in the amount, intensity, frequency

and type of precipitation. Over the contiguous United States, total annual precipitation 

increased by 6.1% from 1901 to 2008. It is likely that there have been increases in the 

number of heavy precipitation events within many land regions, even in those where 

there has been a reduction in total precipitation amount, consistent with a warming 

climate.

There is strong evidence that global sea level gradually rose in the 20th century

and is currently rising at an increased rate. It is not clear whether the increasing rate of 

sea level rise is a reflection of short-term variability or an increase in the longer-term 

trend. Nearly all of the Atlantic Ocean shows sea level rise during the last 50 years with 

the rate of rise reaching a maximum (over 2 millimeters [mm] per year) in a band along 

the U.S. east coast running east-northeast.

Satellite data since 1979 show that annual average Arctic sea ice extent has 

shrunk by 4.1% per decade. The size and speed of recent Arctic summer sea ice loss is 

highly anomalous relative to the previous few thousands of years.

 

332 Hegerl, G.C. et al. (2007) Understanding and Attributing Climate Change. In: Climate Change 2007: 

The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the 

Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, 

K.B. Averyt, M. Tignor, and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom 

and New York, NY, USA.

333 CCSP (2008) Reanalysis of Historical Climate Data for Key Atmospheric Features: Implications for 

Attribution of Causes of Observed Change. A Report by the U.S. Climate Change Science Program and the 

Subcommittee on Global Change Research [Randall Dole, Martin Hoerling, and Siegfried Schubert (eds.)]. 

National Oceanic and Atmospheric Administration, National Climatic Data Center, Asheville, NC, 156 pp.
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Widespread changes in extreme temperatures have been observed in the last 50 

years across all world regions, including the United States. Cold days, cold nights, and 

frost have become less frequent, while hot days, hot nights, and heat waves have become 

more frequent.

Observational evidence from all continents and most oceans shows that many

natural systems are being affected by regional climate changes, particularly temperature

increases. However, directly attributing specific regional changes in climate to emissions 

of GHGs from human activities is difficult, especially for precipitation.

Ocean CO2 uptake has lowered the average ocean pH (increased acidity) level by

approximately 0.1 since 1750. Consequences for marine ecosystems can include reduced 

calcification by shell-forming organisms, and in the longer term, the dissolution of 

carbonate sediments.

Observations show that climate change is currently affecting U.S. physical and 

biological systems in significant ways. The consistency of these observed changes in 

physical and biological systems and the observed significant warming likely cannot be 

explained entirely due to natural variability or other confounding non-climate factors.

(3) Projections of Future Climate Change with Continued Increases in 

Elevated GHG Concentrations

Most future scenarios that assume no explicit GHG mitigation actions (beyond 

those already enacted) project increasing global GHG emissions over the century, with 

climbing GHG concentrations. Carbon dioxide is expected to remain the dominant 

anthropogenic GHG over the course of the 21st century. The radiative forcing associated 

with the non-CO2 GHGs is still significant and increasing over time. 

Future warming over the course of the 21st century, even under scenarios of lowemission growth, is very likely to be greater than observed warming over the past 

century. According to climate model simulations summarized by the IPCC,

334 through 

about 2030, the global warming rate is affected little by the choice of different future 

emissions scenarios. By the end of the 21st century, projected average global warming 

(compared to average temperature around 1990) varies significantly depending on the 

emission scenario and climate sensitivity assumptions, ranging from 3.2 to 7.2F (1.8 to 

4.0C), with an uncertainty range of 2.0 to 11.5F (1.1 to 6.4C).

All of the United States is very likely to warm during this century, and most areas 

of the United States are expected to warm by more than the global average. The largest 

warming is projected to occur in winter over northern parts of Alaska. In western, central 

and eastern regions of North America, the projected warming has less seasonal variation 

 

334 Meehl, G.A. et al. (2007) Global Climate Projections. In: Climate Change 2007: The Physical Science 

Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel 

on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and 

H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
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and is not as large, especially near the coast, consistent with less warming over the 

oceans. 

It is very likely that heat waves will become more intense, more frequent, and 

longer lasting in a future warm climate, whereas cold episodes are projected to decrease 

significantly.

Increases in the amount of precipitation are very likely in higher latitudes, while 

decreases are likely in most subtropical latitudes and the southwestern United States, 

continuing observed patterns. The mid-continental area is expected to experience drying 

during summer, indicating a greater risk of drought. 

Intensity of precipitation events is projected to increase in the United States and 

other regions of the world. More intense precipitation is expected to increase the risk of 

flooding and result in greater runoff and erosion that has the potential for adverse water 

quality effects. 

It is likely that hurricanes will become more intense, with stronger peak winds 

and more heavy precipitation associated with ongoing increases of tropical sea surface 

temperatures. Frequency changes in hurricanes are currently too uncertain for confident 

projections.

By the end of the century, global average sea level is projected by IPCC335 to rise 

between 7.1 and 23 inches (18 and 59 centimeter [cm]), relative to around 1990, in the 

absence of increased dynamic ice sheet loss. Recent rapid changes at the edges of the 

Greenland and West Antarctic ice sheets show acceleration of flow and thinning. While 

an understanding of these ice sheet processes is incomplete, their inclusion in models 

would likely lead to increased sea level projections for the end of the 21st century. 

Sea ice extent is projected to shrink in the Arctic under all IPCC emissions 

scenarios. 

(4) Projected Risks and Impacts Associated With Future Climate Change

Risk to society, ecosystems, and many natural Earth processes increase with 

increases in both the rate and magnitude of climate change. Climate warming may 

increase the possibility of large, abrupt regional or global climatic events (e.g., 

disintegration of the Greenland Ice Sheet or collapse of the West Antarctic Ice Sheet). 

The partial deglaciation of Greenland (and possibly West Antarctica) could be triggered 

by a sustained temperature increase of 2 to 7F (1 to 4oC) above 1990 levels. Such 

warming would cause a 13 to 20 feet (4 to 6 meter) rise in sea level, which would occur 

over a time period of centuries to millennia. 

 

335 IPCC (2007) Summary for Policymakers. In: Climate Change 2007: The Physical Science Basis. 

Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on 

Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and 

H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
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The CCSP336 reports that climate change has the potential to accentuate the 

disparities already evident in the American health care system, as many of the expected 

health effects are likely to fall disproportionately on the poor, the elderly, the disabled, 

and the uninsured. The IPCC337 states with very high confidence that climate change 

impacts on human health in U.S. cities will be compounded by population growth and an 

aging population. 

Severe heat waves are projected to intensify in magnitude and duration over the 

portions of the United States where these events already occur, with potential increases in 

mortality and morbidity, especially among the elderly, young, and frail. 

Some reduction in the risk of death related to extreme cold is expected. It is not 

clear whether reduced mortality from cold will be greater or less than increased heatrelated mortality in the United States due to climate change. 

Increases in regional ozone pollution relative to ozone levels without climate 

change are expected due to higher temperatures and weaker circulation in the United 

States and other world cities relative to air quality levels without climate change. 

Climate change is expected to increase regional ozone pollution, with associated risks in 

respiratory illnesses and premature death. In addition to human health effects, 

tropospheric ozone has significant adverse effects on crop yields, pasture and forest 

growth, and species composition. The directional effect of climate change on ambient 

particulate matter levels remains uncertain. 

Within settlements experiencing climate change, certain parts of the population 

may be especially vulnerable; these include the poor, the elderly, those already in poor 

health, the disabled, those living alone, and/or indigenous populations dependent on one 

or a few resources. Thus, the potential impacts of climate change raise environmental 

justice issues.

The CCSP338 concludes that, with increased CO2 and temperature, the life cycle of 

grain and oilseed crops will likely progress more rapidly. But, as temperature rises, these 

crops will increasingly begin to experience failure, especially if climate variability

increases and precipitation lessens or becomes more variable. Furthermore, the 

 

336 Ebi, K.L., J. Balbus, P.L. Kinney, E. Lipp, D. Mills, M.S. O’Neill, and M. Wilson (2008) Effects of 

Global Change on Human Health. In: Analyses of the effects of global change on human health and welfare 

and human systems. A Report by the U.S. Climate Change Science Program and the Subcommittee on 

Global Change Research. [Gamble, J.L. (ed.), K.L. Ebi, F.G. Sussman, T.J. Wilbanks, (Authors)]. U.S. 

Environmental Protection Agency, Washington, DC, USA, pp. 2-1 to 2-78.

337 Field, C.B. et al. (2007) North America. In: Climate Change 2007: Impacts, Adaptation and 

Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental 

Panel on Climate Change [M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson 

(eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

338 Backlund, P., A. Janetos, D.S. Schimel, J. Hatfield, M.G. Ryan, S.R. Archer, and D. Lettenmaier (2008) 

Executive Summary. In: The Effects of Climate Change on Agriculture, Land Resources, Water Resources, 

and Biodiversity in the United States. A Report by the U.S. Climate Change Science Program and the 

Subcommittee on Global Change Research. Washington, DC., USA, 362 pp.
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marketable yield of many horticultural crops (e.g., tomatoes, onions, fruits) is very likely 

to be more sensitive to climate change than grain and oilseed crops.

Higher temperatures will very likely reduce livestock production during the 

summer season in some areas, but these losses will very likely be partially offset by

warmer temperatures during the winter season.

Cold-water fisheries will likely be negatively affected; warm-water fisheries will 

generally benefit; and the results for cool-water fisheries will be mixed, with gains in the 

northern and losses in the southern portions of ranges.

Climate change has very likely increased the size and number of forest fires, 

insect outbreaks, and tree mortality in the interior West, the Southwest, and Alaska, and 

will continue to do so. Over North America, forest growth and productivity have been 

observed to increase since the middle of the 20th century, in part due to observed climate 

change. Rising CO2 will very likely increase photosynthesis for forests, but the increased 

photosynthesis will likely only increase wood production in young forests on fertile soils. 

The combined effects of expected increased temperature, CO2, nitrogen deposition, 

ozone, and forest disturbance on soil processes and soil carbon storage remain unclear.

Coastal communities and habitats will be increasingly stressed by climate change 

impacts interacting with development and pollution. Sea level is rising along much of the 

U.S. coast, and the rate of change will very likely increase in the future, exacerbating the 

impacts of progressive inundation, storm-surge flooding, and shoreline erosion. Storm 

impacts are likely to be more severe, especially along the Gulf and Atlantic coasts. Salt 

marshes, other coastal habitats, and dependent species are threatened by sea level rise, 

fixed structures blocking landward migration, and changes in vegetation. Population 

growth and rising value of infrastructure in coastal areas increases vulnerability to 

climate variability and future climate change.

Climate change will likely further constrain already over-allocated water 

resources in some regions of the United States, increasing competition among 

agricultural, municipal, industrial, and ecological uses. Although water management 

practices in the United States are generally advanced, particularly in the West, the 

reliance on past conditions as the basis for current and future planning may no longer be 

appropriate, as climate change increasingly creates conditions well outside of historical 

observations. Rising temperatures will diminish snowpack and increase evaporation, 

affecting seasonal availability of water. In the Great Lakes and major river systems, 

lower water levels are likely to exacerbate challenges relating to water quality, 

navigation, recreation, hydropower generation, water transfers, and binational 

relationships. Decreased water supply and lower water levels are likely to exacerbate 

challenges relating to aquatic navigation in the United States. 

Higher water temperatures, increased precipitation intensity, and longer periods of 

low flows will exacerbate many forms of water pollution, potentially making attainment 

of water quality goals more difficult. As waters become warmer, the aquatic life they

now support will be replaced by other species better adapted to warmer water. In the 
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long term, warmer water and changing flow may result in deterioration of aquatic 

ecosystems. 

Ocean acidification is projected to continue, resulting in the reduced biological 

production of marine calcifiers, including corals. 

Climate change is likely to affect U.S. energy use and energy production and 

physical and institutional infrastructures. It will also likely interact with and possibly

exacerbate ongoing environmental change and environmental pressures in settlements, 

particularly in Alaska where indigenous communities are facing major environmental and 

cultural impacts. The U.S. energy sector, which relies heavily on water for hydropower 

and cooling capacity, may be adversely impacted by changes to water supply and quality

in reservoirs and other water bodies. Water infrastructure, including drinking water and 

wastewater treatment plants, and sewer and stormwater management systems, will be at 

greater risk of flooding, sea level rise and storm surge, low flows, and other factors that 

could impair performance.

Disturbances such as wildfires and insect outbreaks are increasing in the United 

States and are likely to intensify in a warmer future with warmer winters, drier soils, and 

longer growing seasons. Although recent climate trends have increased vegetation 

growth, continuing increases in disturbances are likely to limit carbon storage, facilitate 

invasive species, and disrupt ecosystem services. 

Over the 21st century, changes in climate will cause species to shift north and to 

higher elevations and fundamentally rearrange U.S. ecosystems. Differential capacities 

for range shifts and constraints from development, habitat fragmentation, invasive 

species, and broken ecological connections will alter ecosystem structure, function, and 

services.

(5) Present and Projected U.S. Regional Climate Change Impacts

Climate change impacts will vary in nature and magnitude across different 

regions of the United States. 

Sustained high summer temperatures, heat waves, and declining air quality are 

projected in the Northeast,339 Southeast,340 Southwest,341 and Midwest.342 Projected 

climate change would continue to cause loss of sea ice, glacier retreat, permafrost 

thawing, and coastal erosion in Alaska.

 

339 Northeast includes West Virginia, Maryland, Delaware, Pennsylvania, New Jersey, New York, 

Connecticut, Rhode Island, Massachusetts, Vermont, New Hampshire, and Maine.

340 Southeast includes Kentucky, Virginia, Arkansas, Tennessee, North Carolina, South Carolina, southeast 

Texas, Louisiana, Mississippi, Alabama, Georgia, and Florida.

341 Southwest includes California, Nevada, Utah, western Colorado, Arizona, New Mexico (except the 

extreme eastern section), and southwest Texas.

342 The Midwest includes Minnesota, Wisconsin, Michigan, Iowa, Illinois, Indiana, Ohio, and Missouri.
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Reduced snowpack, earlier spring snowmelt, and increased likelihood of seasonal 

summer droughts are projected in the Northeast, Northwest,343 and Alaska. More severe, 

sustained droughts and water scarcity are projected in the Southeast, Great Plains,344 and 

Southwest. 

The Southeast, Midwest, and Northwest in particular are expected to be impacted 

by an increased frequency of heavy downpours and greater flood risk. 

Ecosystems of the Southeast, Midwest, Great Plains, Southwest, Northwest, and 

Alaska are expected to experience altered distribution of native species (including local 

extinctions), more frequent and intense wildfires, and an increase in insect pest outbreaks 

and invasive species. 

Sea level rise is expected to increase storm surge height and strength, flooding, 

erosion, and wetland loss along the coasts, particularly in the Northeast, Southeast, and 

islands. 

Warmer water temperatures and ocean acidification are expected to degrade 

important aquatic resources of islands and coasts such as coral reefs and fisheries. 

A longer growing season, low levels of warming, and fertilization effects of 

carbon dioxide may benefit certain crop species and forests, particularly in the Northeast 

and Alaska. Projected summer rainfall increases in the Pacific islands may augment 

limited freshwater supplies. Cold-related mortality is projected to decrease, especially in 

the Southeast. In the Midwest in particular, heating oil demand and snow-related traffic 

accidents are expected to decrease.

Climate change impacts in certain regions of the world may exacerbate problems 

that raise humanitarian, trade, and national security issues for the United States. The 

IPCC345 identifies the most vulnerable world regions as the Arctic, because of the effects 

of high rates of projected warming on natural systems; Africa, especially the sub-Saharan 

region, because of current low adaptive capacity as well as climate change; small islands, 

due to high exposure of population and infrastructure to risk of sea level rise and 

increased storm surge; and Asian mega-deltas, such as the Ganges-Brahmaputra and the 

Zhujiang, due to large populations and high exposure to sea level rise, storm surge and 

river flooding. Climate change has been described as a potential threat multiplier with 

regard to national security issues.

 

343 The Northwest includes Washington, Idaho, western Montana, and Oregon.

344 The Great Plains includes central and eastern Montana, North Dakota, South Dakota, Wyoming, 

Nebraska, eastern Colorado, Nebraska, Kansas, extreme eastern New Mexico, central Texas, and 

Oklahoma

345 Parry, M.L. et al. (2007) Technical Summary. In: Climate Change 2007: Impacts, Adaptation and 

Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental 

Panel on Climate Change [M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden, and C.E. Hanson 

(eds.)], Cambridge University Press, Cambridge, United Kingdom, pp. 23S78.
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E. Changes in Atmospheric CO2 Concentrations, Global Mean 

Temperature, Sea Level Rise, and Ocean pH Associated with the 

Program’s GHG Emissions Reductions

EPA examined346 the reductions in CO2 and other GHGs associated with this

rulemaking and analyzed the projected effects on atmospheric CO2 concentrations, global 

mean surface temperature, sea level rise, and ocean pH which are common variables used 

as indicators of climate change. The analysis projects that the preferred alternative of this 

program will reduce atmospheric concentrations of CO2, global climate warming and sea 

level rise relative to the reference case. Although the projected reductions and 

improvements are small in comparison to the total projected climate change, they are 

quantifiable, directionally consistent, and will contribute to reducing the risks associated 

with climate change. Climate change is a global phenomenon and EPA recognizes that 

this one national action alone will not prevent it: EPA notes this would be true for any 

given GHG mitigation action when taken alone. EPA also notes that a substantial portion 

of CO2 emitted into the atmosphere is not removed by natural processes for millennia, 

and therefore each unit of CO2 not emitted into the atmosphere due to this program

avoids essentially permanent climate change on centennial time scales. The heavy-duty 

program makes a significant contribution towards addressing the challenge by producing 

substantial reductions in greenhouse gas emissions from a particularly large and 

important source of emissions. As the Supreme Court recognized in State of 

Massachusetts v. EPA, [A]agencies, like legislatures, do not generally resolve massive 

problems like climate change in one fell regulatory swoop. 549 U.S. 497, 524 (2008). 

They instead whittle away at them over time. Id. 

EPA determines that the projected reductions in atmospheric CO2, global mean 

temperature and sea level rise are meaningful in the context of this final action. In 

addition, EPA has conducted an analysis to evaluate the projected changes in ocean pH in 

the context of the changes in emissions from this rulemaking. The results of the analysis 

demonstrate that relative to the reference case, projected atmospheric CO2 concentrations 

are estimated to be reduced by 0.691 to 0.787 part per million by volume (ppmv), global 

mean temperature is estimated to be reduced by 0.0017 to 0.0042°C, and sea-level rise is 

projected to be reduced by approximately 0.017-0.040 cm by 2100, based on a range of 

climate sensitivities. The analysis also demonstrates that ocean pH will increase by

0.0003 pH units by 2100 relative to the reference case. 

(1) Estimated Projected Reductions in Atmospheric CO2 Concentration, 

Global Mean Surface Temperatures, Sea Level Rise, and Ocean pH

EPA estimated changes in the atmospheric CO2 concentration, global mean 

temperature, and sea level rise out to 2100 resulting from the emissions reductions in this 

rulemaking using the GCAM (Global Change Assessment Model, formerly MiniCAM),

 

346 Using the Model for the Assessment of Greenhouse Gas Induced Climate Change (MAGICC) 5.3v2, 

http://www.cgd.ucar.edu/cas/wigley/magicc/), EPA estimated the effects of this rulemaking’s greenhouse 

gas emissions reductions on global mean temperature and sea level. Please refer to Chapter 8.4 of the RIA 

for additional information.
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integrated assessment model347 coupled with the Model for the Assessment of 

Greenhouse Gas Induced Climate Change (MAGICC, version 5.3v2).348 GCAM was 

used to create the globally and temporally consistent set of climate relevant variables 

required for running MAGICC. MAGICC was then used to estimate the projected

change in these variables over time. Given the magnitude of the estimated emissions 

reductions associated with this action, a simple climate model such as MAGICC is 

reasonable for estimating the atmospheric and climate response. This widely-used, peer 

reviewed modeling tool was also used to project temperature and sea level rise under 

different emissions scenarios in the Third and Fourth Assessments of the IPCC. 

The integrated impact of the following pollutant and greenhouse gas emissions 

changes are considered: CO2, CH4, N2O, HFC-134a, NOX, CO2 and SO2, and volatile 

organic compounds (VOC). For CO2, CH4, HFC-134a, and N2O an annual time-series of 

(upstream + downstream) emissions reductions estimated from the rulemaking were input 

directly. The GHG emissions reductions, from Section VI.C, were applied as net 

reductions to a global reference case (or baseline) emissions scenario in GCAM to 

generate an emissions scenario specific to this rulemaking. For CO, VOCs, SO2, and 

NOX, emissions reductions were estimated for 2018, 2030, and 2050 (provided in Section 

VII.A). EPA then linearly scaled emissions reductions for these gases between a zero 

input value in 2013 and the value supplied for 2018 to produce the reductions for 2014-

2018. A similar scaling was used for 2019-2029 and 2031-2050. The emissions 

reductions past 2050 for all gases were scaled with total U.S. road transportation fuel 

consumption from the GCAM reference scenario. Road transport fuel consumption past 

2050 does not change significantly and thus emissions reductions remain relatively

constant from 2050 through 2100. Specific details about the GCAM reference case 

scenario can be found in Chapter 8.4 of the RIA that accompanies this preamble.

MAGICC calculates the forcing response at the global scale from changes in 

atmospheric concentrations of CO2, CH4, N2O, HFCs, and tropospheric ozone. It also 

includes the effects of temperature changes on stratospheric ozone and the effects of CH4

emissions on stratospheric water vapor. Changes in CH4, NOX, VOC, and CO emissions 

affect both O3 concentrations and CH4 concentrations. MAGICC includes the relative 

climate forcing effects of changes in sulfate concentrations due to changing SO2

emissions, including both the direct effect of sulfate particles and the indirect effects 

related to cloud interactions. However, MAGICC does not calculate the effect of changes 

in concentrations of other aerosols such as nitrates, black carbon, or organic carbon, 

 

347 GCAM is a long-term, global integrated assessment model of energy, economy, agriculture and land 

use, that considers the sources of emissions of a suite of GHG’s, emitted in 14 globally disaggregated 

regions, the fate of emissions to the atmosphere, and the consequences of changing concentrations of 

greenhouse related gases for climate change. GCAM begins with a representation of demographic and 

economic developments in each region and combines these with assumptions about technology 

development to describe an internally consistent representation of energy, agriculture, land-use, and 

economic developments that in turn shape global emissions. 

Brenkert A, S. Smith, S. Kim, and H. Pitcher, 2003: Model Documentation for the MiniCAM. PNNL14337, Pacific Northwest National Laboratory, Richland, Washington.

348 Wigley, T.M.L. 2008. MAGICC 5.3.v2 User Manual. UCAR – Climate and Global Dynamics Division, 

Boulder, Colorado. http://www.cgd.ucar.edu/cas/wigley/magicc/
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making the assumption that the sulfate cooling effect is a proxy for the sum of all the 

aerosol effects. Therefore, the climate effects of changes in PM2.5 emissions and 

precursors (besides SO2) which are presented in the RIA Chapter 5 were not included in 

the calculations in this section. MAGICC also calculates all climate effects at the global 

scale. This global scale captures the climate effects of the long-lived, well-mixed 

greenhouse gases, but does not address the fact that short-lived climate forcers such as 

aerosols and ozone can have effects that vary with location and timing of emissions. 

Black carbon in particular is known to cause a positive forcing or warming effect by 

absorbing incoming solar radiation, but there are uncertainties about the magnitude of 

that warming effect and the interaction of black carbon (and other co-emitted aerosol 

species) with clouds. While black carbon is likely to be an important contributor to 

climate change, it would be premature to include quantification of black carbon climate 

impacts in an analysis of the final standards at this time.

Changes in atmospheric CO2 concentration, global mean temperature, and sea

level rise for both the reference case and the emissions scenarios associated with this 

action were computed using MAGICC. To calculate the reductions in the atmospheric 

CO2 concentrations as well as in temperature and sea level resulting from this action, the 

output from the policy scenario associated with the preferred approach of this action was

subtracted from an existing Global Change Assessment Model (GCAM, formerly 

MiniCAM) reference emission scenario. To capture some key uncertainties in the climate 

system with the MAGICC model, changes in atmospheric CO2, global mean temperature 

and sea level rise were projected across the most current IPCC range of climate 

sensitivities, from 1.5°C to 6.0°C.

349

 This range reflects the uncertainty for equilibrium 

climate sensitivity for how much global mean temperature would rise if the concentration 

of carbon dioxide in the atmosphere were to double. The information for this range come 

from constraints from past climate change on various time scales, and the spread of 

results for climate sensitivity from ensembles of models.350 Details about this modeling 

analysis can be found in the RIA Chapter 8.4.

The results of this modeling, summarized in Table VI-8, show small, but 

quantifiable, reductions in atmospheric CO2 concentrations, projected global mean 

temperature and sea level resulting from this action, across all climate sensitivities. As a

result of the emission reductions from the final standards for this action, relative to the 

reference case the atmospheric CO2 concentration is projected to be reduced by 0.691-

0.787 ppmv, the global mean temperature is projected to be reduced by approximately

0.0017-0.0042°C by 2100, and global mean sea level rise is projected to be reduced by 

 

349 In IPCC reports, equilibrium climate sensitivity refers to the equilibrium change in the annual mean 

global surface temperature following a doubling of the atmospheric equivalent carbon dioxide 

concentration. The IPCC states that climate sensitivity is “likely” to be in the range of 2°C to 4.5°C, “very 

unlikely” to be less than 1.5°C, and “values substantially higher than 4.5°C cannot be excluded.” IPCC 

WGI, 2007, Climate Change 2007 - The Physical Science Basis, Contribution of Working Group I to the 

Fourth Assessment Report of the IPCC, http://www.ipcc.ch/

350 Meehl, G.A. et al. (2007) Global Climate Projections. In: Climate Change 2007: The Physical Science 

Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel

on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and 

H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
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approximately 0.017-0.040 cm by 2100. The range of reductions in global mean 

temperature and sea level rise is larger than that for CO2 concentrations because CO2

concentrations are only weakly coupled to climate sensitivity through the dependence on 

temperature of the rate of ocean absorption of CO2, whereas the magnitude of 

temperature change response to CO2 changes (and therefore sea level rise) is more tightly

coupled to climate sensitivity in the MAGICC model. 

Table VI-8: Impact of GHG Emissions Reductions on Projected Changes in Global Climate 

Associated with the Final Rulemaking (Based on a range of climate sensitivities from 1.5-6°C)

Variable Units Year Projected Change

Atmospheric CO2 Concentration ppmv 2100 -0.691 to -0.787

Global Mean Surface Temperature o C 2100 -0.0017 to -0.0042

Sea Level Rise cm 2100 -0.017 to -0.040

Ocean pH pH units 2100 0.0003a

Note:

a The value for projected change in ocean pH is based on a climate sensitivity of 3.0.

The projected reductions are small relative to the change in temperature (1.8 – 4.8

oC), sea level rise (27 – 51 cm), and ocean acidity (-0.30 pH units) from 1990 to 2100 

from the MAGICC simulations for the GCAM reference case. However, this is to be 

expected given the magnitude of emissions reductions expected from the program in the 

context of global emissions. This uncertainty range does not include the effects of 

uncertainty in future emissions. It should also be noted that the calculations in MAGICC 

do not include the possible effects of accelerated ice flow in Greenland and/or Antarctica: 

the recent NRC report estimated a likely sea level increase for the A1B SRES scenario of 

0.5 to 1.0 meters.351 Further discussion of EPA’s modeling analysis is found in the RIA, 

Chapter 8.

EPA used the Program CO2SYS,352 version 1.05 to estimate projected changes in 

ocean pH for tropical waters based on the atmospheric CO2 concentration change 

(reduction) resulting from this action. The program performs calculations relating 

parameters of the CO2 system in seawater. EPA used the program to calculate ocean pH 

as a function of atmospheric CO2 concentrations, among other specified input conditions. 

Based on the projected atmospheric CO2 concentration reductions resulting from this 

action, the program calculates an increase in ocean pH of 0.0003 pH units in 2100 

relative to the reference case (compared to a decrease of 0.3 pH units from 1990 to 2100 

in the reference case). Thus, this analysis indicates the projected decrease in atmospheric 

CO2 concentrations from the program will result in an increase in ocean pH. For 

additional validation, results were generated using different known constants from the 

literature. A comprehensive discussion of the modeling analysis associated with ocean 

pH is provided in the RIA, Chapter 8. 

 

351 National Research Council, 2011. Climate Stabilization Targets: Emissions, Concentrations, and 

Impacts over Decades to Millenia. Washington, DC: National Academies Press.

352 Lewis, E., and D. W. R. Wallace. 1998. Program Developed for CO2 System Calculations. 

ORNL/CDIAC-105. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. 

Department of Energy, Oak Ridge, Tennessee.
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(2) Program’s Effect on Climate

As a substantial portion of CO2 emitted into the atmosphere is not removed by

natural processes for millennia, each unit of CO2 not emitted into the atmosphere avoids 

essentially permanent climate change on centennial time scales. Reductions in emissions 

in the near-term are important in determining long-term climate stabilization and 

associated impacts experienced not just over the next decades but in the coming centuries 

and millennia.353 Though the magnitude of the avoided climate change projected here is 

small in comparison to the total projected changes, these reductions represent a reduction 

in the adverse risks associated with climate change (though these risks were not formally 

estimated for this action) across a range of equilibrium climate sensitivities.

EPA’s analysis of the program’s impact on global climate conditions is intended 

to quantify these potential reductions using the best available science. EPA’s modeling 

results show repeatable, consistent reductions relative to the reference case in changes of 

CO2 concentration, temperature, sea-level rise, and ocean pH over the next century.

VII. How Will This Final Action Impact Non-GHG Emissions 

and Their Associated Effects?

A. Emissions Inventory Impacts

(1) Upstream Impacts of the Program

Increasing efficiency in heavy-duty vehicles will result in reduced fuel demand 

and therefore reductions in the emissions associated with all processes involved in getting 

petroleum to the pump. These projected upstream emission impacts on criteria pollutants 

are summarized in Table VII-1. Table VII-2 shows the corresponding projected impacts 

on upstream air toxic emissions in 2030. 

Table VII-1: Overall estimated upstream impacts on criteria pollutants for calendar years 2018, 

2030, and 2050 (short tons)

Calendar Year NOX VOC CO PM2.5 

2018 -6,475 -1,765 -2,217 -971

2030 -9,975 -4,367 -3,331 -1,379

2050 -14,243 -6,379 -4,785 -1,998

 

353 See NRC 2011, Note 351.354 Although the net impact is small when aggregated to the national level, it 

is unlikely that the geographic location of increases in downstream PM2.5 emissions will coincide with the 

location of decreases in upstream PM2.5 emissions. Impacts of the emissions changes are included in the air 

quality modeling, discussed in Section VII.D of this preamble and in Chapter 8 of the RIA.
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Table VII-2: Overall estimated upstream impacts on air toxics for calendar years 2018, 2030, and 

2050 (short tons)

Calendar Year Benzene 1,3-butadiene Formaldehyde Acetaldehyde Acrolein

2018 -12 -0.6 -12 -1 -0.2

2030 -19 -0.9 -26 -3 -0.5

2050 -28 -1.2 -35 -5 -0.6

To project these impacts, EPA estimated the impact of reduced petroleum 

volumes on the extraction and transportation of crude oil as well as the production and 

distribution of finished gasoline and diesel. For the purpose of assessing domestic-only

emission reductions it was necessary to estimate the fraction of fuel savings attributable

to domestic finished gasoline and diesel, and of this fuel what fraction is produced from 

domestic crude. For this analysis EPA estimated that 50 percent of fuel savings is 

attributable to domestic finished gasoline and diesel and that 90 percent of this gasoline

and diesel originated from imported crude. Emission factors for most upstream emission 

sources are based on the GREET1.8 model, developed by DOE’s Argonne National 

Laboratory but in some cases the GREET values were modified or updated by EPA to be

consistent with the National Emission Inventory. These updates are consistent with those 

used for the upstream analysis included in the Light-Duty GHG rulemaking. More 

information on the development of the emission factors used in this analysis can be found 

in RIA Chapter 5.

(2) Downstream Impacts of the Program

While these final rules do not regulate non-GHG pollutants, EPA expects 

reductions in downstream emissions of most non-GHG pollutants. These pollutants 

include NOX, SO2, VOC, CO, and PM. The primary reasons for this are the 

improvements in road load (aerodynamics and tire rolling resistance) under the program 

and the agency’s anticipation of increased use of APUs in combination tractors for GHG 

reduction purposes during extended idling. APUs exhibit different non-GHG emissions 

characteristics compared to the on-road engines they would replace during extended 

idling. Another reason is that emissions from certain pollutants (e.g., SO2) are 

proportional to fuel consumption. For vehicle types not affected by road load 

improvements, non-GHG emissions may increase very slightly due to VMT rebound. 

EPA used MOVES to determine non-GHG emissions inventories for baseline and control 

cases. Further information about the MOVES analysis is available in Section VI and RIA 

Chapter 5. The improvements in road load, use of APUs, and VMT rebound were 

included in the MOVES runs and post-processing. Table VII-3 summarizes the 

downstream criteria pollutant impacts of this program. Most of the impacts shown are 

through projected increased APU use. Because APUs are required to meet much less 

stringent PM standards than on-road engines, the projected widespread use of APUs leads 

to higher PM2.5. Table VII-4 summarizes the downstream air toxics impacts of this 

program. 
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Table VII-3: Overall Estimated Downstream Impacts on Criteria Pollutants (short tons)

Calendar 

Year

Downstream 

NOX

Downstream 

VOC

Downstream 

SO2

Downstream 

CO

Downstream 

PM2.5 

a

2018 -107,135 -12,951 -145 -25,614 803

2030 -235,046 -25,502 -423 -52,212 1,751

2050 -326,413 -35,126 -614 -72,049 2,441

Note:

a

Positive number means emissions would increase from baseline to control case. PM2.5 from tire wear and 

brake wear is included. 

Table VII-4: Overall Estimated Downstream Impacts on Air Toxics (short tons)

Calendar Year Benzene 1,3-butadiene Formaldehyde Acetaldehyde Acrolein

2018 -158 -0.3 -2,853 -871 -120

2030 -341 0.4 -6,255 -1,908 -263

2050 -472 0.8 -8,689 -2,650 -365

(3) Total Impacts of the Program

As shown in Table VII-5 and 

Table VII-6, the agencies estimate that this program would result in reductions of 

NOX, VOC, CO, PM, and air toxics. For NOX, VOC, and CO, much of the net reductions 

are realized through the use of APUs, which emit these pollutants at a lower rate than onroad engines during extended idle operation. Additional reductions are achieved in all 

pollutants through reduced road load (improved aerodynamics and tire rolling resistance), 

which reduces the amount of work required to travel a given distance. For SOX, 

downstream emissions are roughly proportional to fuel consumption; therefore a decrease 

is seen in both upstream and downstream sources. The downstream increase in PM2.5 due 

to APU use is mostly negated by upstream PM2.5 reductions, though our calculations 

show a slight net increase in 2030 and 2050.354 

Table VII-5: Overall Estimated Total Impacts (Upstream Plus Downstream) on Criteria Pollutants 

Results are shown in both short tons and percent change from baseline to control case.

CY NOX VOC SO2 CO PM2.5

short 

tons

% short 

tons

% short 

tons

% short tons % short 

tons

%

2018 -113,610 -6.2 -14,715 -5.6 -4,566 c-4.5 -27,832 -1.0 -167 -0.2

2030 -245,129 -21.0 -29,932 -16.0 -6,888 -10.1 -55,579 -2.1 356 10.1

2050 -340,656 -23.7 -41,506 -18.3 -9,857 -11.0 -76,834 -2.2 443 10.1

 

354 Although the net impact is small when aggregated to the national level, it is unlikely that the geographic 

location of increases in downstream PM2.5 emissions will coincide with the location of decreases in 

upstream PM2.5 emissions. Impacts of the emissions changes are included in the air quality modeling, 

discussed in Section VII.D of this preamble and in Chapter 8 of the RIA.
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Table VII-6: Overall Estimated Total Impacts on Air Toxics (Upstream Plus Downstream) 

CY Benzene 1,3-butadiene Formaldehyde Acetaldehyde Acrolein

short 

tons

% short 

tons

% short 

tons

% short 

tons

% short 

tons

%

2018 -170 -4.8 -0.9 -0.1 -2,865 -18.3 -873 -13.9 -120.0 -12.4

2030 -359 -15.0 -0.5 -0.1 -6,282 -46.2 -1,912 -40.2 -263.0 -40.0

2050 -500 -17.4 -0.4 -0.1 -8,725 -49.5 -2,655 -44.2 -365.4 -44.5

B. Health Effects of Non-GHG Pollutants

In this section we discuss health effects associated with exposure to some of the 

criteria and air toxic pollutants impacted by the final heavy-duty vehicle standards. 

(1) Particulate Matter

(a) Background

Particulate matter is a generic term for a broad class of chemically and physically 

diverse substances. It can be principally characterized as discrete particles that exist in the 

condensed (liquid or solid) phase spanning several orders of magnitude in size. Since 

1987, EPA has delineated that subset of inhalable particles small enough to penetrate to 

the thoracic region (including the tracheobronchial and alveolar regions) of the 

respiratory tract (referred to as thoracic particles). Current National Ambient Air Quality

Standards (NAAQS) use PM2.5 as the indicator for fine particles (with PM2.5 referring to 

particles with a nominal mean aerodynamic diameter less than or equal to 2.5 μm), and 

use PM10 as the indicator for purposes of regulating the coarse fraction of PM10 (referred 

to as thoracic coarse particles or coarse-fraction particles; generally including particles 

with a nominal mean aerodynamic diameter greater than 2.5 μm and less than or equal to 

10 μm, or PM10-2.5). Ultrafine particles are a subset of fine particles, generally less than 

100 nanometers (0.1 μm) in aerodynamic diameter. 

Fine particles are produced primarily by combustion processes and by 

transformations of gaseous emissions (e.g., SOX, NOX, and VOC) in the atmosphere. The 

chemical and physical properties of PM2.5 may vary greatly with time, region, 

meteorology, and source category. Thus, PM2.5 may include a complex mixture of 

different pollutants including sulfates, nitrates, organic compounds, elemental carbon and 

metal compounds. These particles can remain in the atmosphere for days to weeks and 

travel hundreds to thousands of kilometers.

(b) Health Effects of PM

Scientific studies show ambient PM is associated with a series of adverse health 

effects. These health effects are discussed in detail in EPA’s Integrated Science 
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Assessment for Particulate Matter (ISA).

355

 Further discussion of health effects 

associated with PM can also be found in the RIA for this final action. The ISA 

summarizes evidence associated with PM2.5, PM10-2.5, and ultrafine particles.

The ISA concludes that health effects associated with short-term exposures (hours 

to days) to ambient PM2.5 include mortality, cardiovascular effects, such as altered 

vasomotor function and hospital admissions and emergency department visits for 

ischemic heart disease and congestive heart failure, and respiratory effects, such as 

exacerbation of asthma symptoms in children and hospital admissions and emergency

department visits for chronic obstructive pulmonary disease and respiratory infections.

356

 

The ISA notes that long-term exposure to PM2.5 (months to years) is associated with the 

development/progression of cardiovascular disease, premature mortality, and respiratory

effects, including reduced lung function growth, increased respiratory symptoms, and 

asthma development.357 The ISA concludes that the currently available scientific 

evidence from epidemiologic, controlled human exposure, and toxicological studies 

supports a causal association between short- and long-term exposures to PM2.5 and 

cardiovascular effects and mortality. Furthermore, the ISA concludes that the collective 

evidence supports likely causal associations between short- and long-term PM2.5 

exposures and respiratory effects. The ISA also concludes that the scientific evidence is 

suggestive of a causal association for reproductive and developmental effects and cancer, 

mutagenicity, and genotoxicity and long-term exposure to PM2.5.

358

For PM10-2.5, the ISA concludes that the current evidence is suggestive of a causal 

relationship between short-term exposures and cardiovascular effects, such as 

hospitalization for ischemic heart disease. There is also suggestive evidence of a causal 

relationship between short-term PM10-2.5 exposure and mortality and respiratory effects. 

Data are inadequate to draw conclusions regarding the health effects associated with 

long-term exposure to PM10-2.5.

359

For ultrafine particles, the ISA concludes that there is suggestive evidence of a 

causal relationship between short-term exposures and cardiovascular effects, such as 

changes in heart rhythm and blood vessel function. It also concludes that there is 

suggestive evidence of association between short-term exposure to ultrafine particles and 

respiratory effects. Data are inadequate to draw conclusions regarding the health effects 

associated with long-term exposure to ultrafine particles.360

 

355 U.S. EPA (2009) Integrated Science Assessment for Particulate Matter (Final Report). U.S. 

Environmental Protection Agency, Washington, DC, EPA/600/R-08/139F, Docket EPA-HQ-OAR-2010-

0162.

356 See U.S. EPA, 2009 Final PM ISA, Note 355, at Section 2.3.1.1.

357 See U.S. EPA 2009 Final PM ISA, Note 355, at page 2-12, Sections 7.3.1.1 and 7.3.2.1.

358 See U.S. EPA 2009 Final PM ISA, Note 355, at Section 2.3.2.

359 See U.S. EPA 2009 Final PM ISA, Note 355, at Section 2.3.4, Table 2-6.

360 See U.S. EPA 2009 Final PM ISA, Note 355, at Section 2.3.5, Table 2-6.
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(2) Ozone

(a) Background

Ground-level ozone pollution is typically formed by the reaction of VOC and 

NOX in the lower atmosphere in the presence of sunlight. These pollutants, often referred 

to as ozone precursors, are emitted by many types of pollution sources, such as highway

and nonroad motor vehicles and engines, power plants, chemical plants, refineries, 

makers of consumer and commercial products, industrial facilities, and smaller area 

sources.

The science of ozone formation, transport, and accumulation is complex. 

Ground-level ozone is produced and destroyed in a cyclical set of chemical reactions, 

many of which are sensitive to temperature and sunlight. When ambient temperatures 

and sunlight levels remain high for several days and the air is relatively stagnant, ozone 

and its precursors can build up and result in more ozone than typically occurs on a single 

high-temperature day. Ozone can be transported hundreds of miles downwind from 

precursor emissions, resulting in elevated ozone levels even in areas with low local VOC 

or NOX emissions.

(b) Health Effects of Ozone

The health and welfare effects of ozone are well documented and are assessed in 

EPA’s 2006 Air Quality Criteria Document and 2007 Staff Paper.361,362 People who are 

more susceptible to effects associated with exposure to ozone can include children, the 

elderly, and individuals with respiratory disease such as asthma. Those with greater 

exposures to ozone, for instance due to time spent outdoors (e.g., children and outdoor 

workers), are of particular concern. Ozone can irritate the respiratory system, causing 

coughing, throat irritation, and breathing discomfort. Ozone can reduce lung function 

and cause pulmonary inflammation in healthy individuals. Ozone can also aggravate 

asthma, leading to more asthma attacks that require medical attention and/or the use of 

additional medication. Thus, ambient ozone may cause both healthy and asthmatic 

individuals to limit their outdoor activities. In addition, there is suggestive evidence of a 

contribution of ozone to cardiovascular-related morbidity and highly suggestive evidence 

that short-term ozone exposure directly or indirectly contributes to non-accidental and 

cardiopulmonary-related mortality, but additional research is needed to clarify the 

underlying mechanisms causing these effects. In a recent report on the estimation of 

ozone-related premature mortality published by NRC, a panel of experts and reviewers 

concluded that short-term exposure to ambient ozone is likely to contribute to premature 

deaths and that ozone-related mortality should be included in estimates of the health 

 

361 U.S. EPA. (2006). Air Quality Criteria for Ozone and Related Photochemical Oxidants (Final). 

EPA/600/R-05/004aF-cF. Washington, DC: U.S. EPA. Docket EPA-HQ-OAR-2010-0162.

362 U.S. EPA. (2007). Review of the National Ambient Air Quality Standards for Ozone: Policy 

Assessment of Scientific and Technical Information, OAQPS Staff Paper. EPA-452/R-07-003. 

Washington, DC, U.S. EPA. Docket EPA-HQ-OAR-2010-0162.
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benefits of reducing ozone exposure.363 Animal toxicological evidence indicates that 

with repeated exposure, ozone can inflame and damage the lining of the lungs, which 

may lead to permanent changes in lung tissue and irreversible reductions in lung function. 

The respiratory effects observed in controlled human exposure studies and animal studies 

are coherent with the evidence from epidemiologic studies supporting a causal 

relationship between acute ambient ozone exposures and increased respiratory-related 

emergency room visits and hospitalizations in the warm season. In addition, there is 

suggestive evidence of a contribution of ozone to cardiovascular-related morbidity and 

non-accidental and cardiopulmonary mortality.

(3) Nitrogen Oxides and Sulfur Oxides

(a) Background

Nitrogen dioxide (NO2) is a member of the NOX family of gases. Most NO2 is 

formed in the air through the oxidation of nitric oxide (NO) emitted when fuel is burned 

at a high temperature. SO2, a member of the sulfur oxide (SOX) family of gases, is 

formed from burning fuels containing sulfur (e.g., coal or oil derived), extracting gasoline 

from oil, or extracting metals from ore. 

SO2 and NO2 can dissolve in water droplets and further oxidize to form sulfuric 

and nitric acid which react with ammonia to form sulfates and nitrates, both of which are 

important components of ambient PM. The health effects of ambient PM are discussed in 

Section VII. B. (1) (b) of this preamble. NOX and NMHC are the two major precursors 

of ozone. The health effects of ozone are covered in Section VII. B. (2) (b).

(b) Health Effects of NO2

Information on the health effects of NO2 can be found in the EPA Integrated 

Science Assessment (ISA) for Nitrogen Oxides.364 The EPA has concluded that the 

findings of epidemiologic, controlled human exposure, and animal toxicological studies 

provide evidence that is sufficient to infer a likely causal relationship between respiratory

effects and short-term NO2 exposure. The ISA concludes that the strongest evidence for 

such a relationship comes from epidemiologic studies of respiratory effects including 

symptoms, emergency department visits, and hospital admissions. The ISA also draws 

two broad conclusions regarding airway responsiveness following NO2 exposure. First, 

the ISA concludes that NO2 exposure may enhance the sensitivity to allergen-induced 

decrements in lung function and increase the allergen-induced airway inflammatory

response following 30-minute exposures of asthmatics to NO2 concentrations as low as 

0.26 ppm. In addition, small but significant increases in non-specific airway

hyperresponsiveness were reported following 1-hour exposures of asthmatics to 0.1 ppm 

NO2. Second, exposure to NO2 has been found to enhance the inherent responsiveness of 

the airway to subsequent nonspecific challenges in controlled human exposure studies of 

 

363 National Research Council (NRC), 2008. Estimating Mortality Risk Reduction and Economic Benefits 

from Controlling Ozone Air Pollution. The National Academies Press: Washington, D.C. Docket EPAHQ-OAR-2010-0162

364 U.S. EPA (2008). Integrated Science Assessment for Oxides of Nitrogen – Health Criteria (Final 

Report). EPA/600/R-08/071. Washington, DC: U.S.EPA. Docket EPA-HQ-OAR-2010-0162 .
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asthmatic subjects. Enhanced airway responsiveness could have important clinical 

implications for asthmatics since transient increases in airway responsiveness following 

NO2 exposure have the potential to increase symptoms and worsen asthma control. 

Together, the epidemiologic and experimental data sets form a plausible, consistent, and 

coherent description of a relationship between NO2 exposures and an array of adverse 

health effects that range from the onset of respiratory symptoms to hospital admission. 

Although the weight of evidence supporting a causal relationship is somewhat 

less certain than that associated with respiratory morbidity, NO2 has also been linked to 

other health endpoints. These include all-cause (nonaccidental) mortality, hospital 

admissions or emergency department visits for cardiovascular disease, and decrements in 

lung function growth associated with chronic exposure.

(c) Health Effects of SO2

Information on the health effects of SO2 can be found in the EPA Integrated 

Science Assessment for Sulfur Oxides.365 SO2 has long been known to cause adverse 

respiratory health effects, particularly among individuals with asthma. Other potentially

sensitive groups include children and the elderly. During periods of elevated ventilation, 

asthmatics may experience symptomatic bronchoconstriction within minutes of exposure. 

Following an extensive evaluation of health evidence from epidemiologic and laboratory

studies, the EPA has concluded that there is a causal relationship between respiratory

health effects and short-term exposure to SO2. Separately, based on an evaluation of the 

epidemiologic evidence of associations between short-term exposure to SO2 and 

mortality, the EPA has concluded that the overall evidence is suggestive of a causal 

relationship between short-term exposure to SO2 and mortality.

(4) Carbon Monoxide

Information on the health effects of CO can be found in the EPA Integrated 

Science Assessment (ISA) for Carbon Monoxide.

366

 The ISA concludes that ambient 

concentrations of CO are associated with a number of adverse health effects.367 This 

section provides a summary of the health effects associated with exposure to ambient 

concentrations of CO.

368

 

 

365 U.S. EPA. (2008). Integrated Science Assessment (ISA) for Sulfur Oxides – Health Criteria (Final 

Report). EPA/600/R-08/047F. Washington, DC: U.S. Environmental Protection Agency. Docket EPA-HQOAR-2010-0162.

366 U.S. EPA, 2010. Integrated Science Assessment for Carbon Monoxide (Final Report). U.S. 

Environmental Protection Agency, Washington, DC, EPA/600/R-09/019F, 2010. Available at 

http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=218686. Docket EPA-HQ-OAR-2010-0162

367 The ISA evaluates the health evidence associated with different health effects, assigning one of five 

“weight of evidence” determinations: causal relationship, likely to be a causal relationship, suggestive of a 

causal relationship, inadequate to infer a causal relationship, and not likely to be a causal relationship. For 

definitions of these levels of evidence, please refer to Section 1.6 of the ISA. 

368 Personal exposure includes contributions from many sources, and in many different environments. 

Total personal exposure to CO includes both ambient and nonambient components; and both components 

may contribute to adverse health effects.
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Human clinical studies of subjects with coronary artery disease show a decrease 

in the time to onset of exercise-induced angina (chest pain) and electrocardiogram 

changes following CO exposure. In addition, epidemiologic studies show associations 

between short-term CO exposure and cardiovascular morbidity, particularly increased 

emergency room visits and hospital admissions for coronary heart disease (including 

ischemic heart disease, myocardial infarction, and angina). Some epidemiologic 

evidence is also available for increased hospital admissions and emergency room visits 

for congestive heart failure and cardiovascular disease as a whole. The ISA concludes 

that a causal relationship is likely to exist between short-term exposures to CO and 

cardiovascular morbidity. It also concludes that available data are inadequate to conclude 

that a causal relationship exists between long-term exposures to CO and cardiovascular 

morbidity. 

Animal studies show various neurological effects with in-utero CO exposure. 

Controlled human exposure studies report inconsistent neural and behavioral effects 

following low-level CO exposures. The ISA concludes the evidence is suggestive of a 

causal relationship with both short- and long-term exposure to CO and central nervous 

system effects.

A number of epidemiologic and animal toxicological studies cited in the ISA have 

evaluated associations between CO exposure and birth outcomes such as preterm birth or 

cardiac birth defects. The epidemiologic studies provide limited evidence of a COinduced effect on preterm births and birth defects, with weak evidence for a decrease in 

birth weight. Animal toxicological studies have found associations between perinatal CO 

exposure and decrements in birth weight, as well as other developmental outcomes. The 

ISA concludes these studies are suggestive of a causal relationship between long-term 

exposures to CO and developmental effects and birth outcomes.

Epidemiologic studies provide evidence of effects on respiratory morbidity such 

as changes in pulmonary function, respiratory symptoms, and hospital admissions 

associated with ambient CO concentrations. A limited number of epidemiologic studies 

considered copollutants such as ozone, SO2, and PM in two-pollutant models and found 

that CO risk estimates were generally robust, although this limited evidence makes it 

difficult to disentangle effects attributed to CO itself from those of the larger complex air 

pollution mixture. Controlled human exposure studies have not extensively evaluated the 

effect of CO on respiratory morbidity. Animal studies at levels of 50-100 ppm CO show 

preliminary evidence of altered pulmonary vascular remodeling and oxidative injury. 

The ISA concludes that the evidence is suggestive of a causal relationship between shortterm CO exposure and respiratory morbidity, and inadequate to conclude that a causal 

relationship exists between long-term exposure and respiratory morbidity. 

Finally, the ISA concludes that the epidemiologic evidence is suggestive of a 

causal relationship between short-term exposures to CO and mortality. Epidemiologic 

studies provide evidence of an association between short-term exposure to CO and 

mortality, but limited evidence is available to evaluate cause-specific mortality outcomes 

associated with CO exposure. In addition, the attenuation of CO risk estimates which 

was often observed in copollutant models contributes to the uncertainty as to whether CO 
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is acting alone or as an indicator for other combustion-related pollutants. The ISA also 

concludes that there is not likely to be a causal relationship between relevant long-term 

exposures to CO and mortality.

(5) Air Toxics

Heavy-duty vehicle emissions contribute to ambient levels of air toxics known or 

suspected as human or animal carcinogens, or that have noncancer health effects. The 

population experiences an elevated risk of cancer and other noncancer health effects from 

exposure to the class of pollutants known collectively as “air toxics.”369 These 

compounds include, but are not limited to, benzene, 1,3-butadiene, formaldehyde, 

acetaldehyde, acrolein, diesel particulate matter and exhaust organic gases, polycyclic 

organic matter, and naphthalene. These compounds were identified as national or 

regional risk drivers or contributors in the 2005 National-scale Air Toxics Assessment 

and have significant inventory contributions from mobile sources.370 

(a) Diesel Exhaust

Heavy-duty diesel engines emit diesel exhaust, a complex mixture composed of 

carbon dioxide, oxygen, nitrogen, water vapor, carbon monoxide, nitrogen compounds, 

sulfur compounds and numerous low-molecular-weight hydrocarbons. A number of 

these gaseous hydrocarbon components are individually known to be toxic, including 

aldehydes, benzene and 1,3-butadiene. The diesel particulate matter present in diesel 

exhaust consists mostly of fine particles (< 2.5 μm), including a significant fraction of 

ultrafine particles (< 0.1 μm). These particles have a large surface area which makes 

them an excellent medium for adsorbing organics and their small size makes them highly 

respirable. Many of the organic compounds present in the gases and on the particles, such 

as polycyclic organic matter, are individually known to have mutagenic and carcinogenic 

properties. 

Diesel exhaust varies significantly in chemical composition and particle sizes 

between different engine types (heavy-duty, light-duty), engine operating conditions 

(idle, accelerate, decelerate), and fuel formulations (high/low sulfur fuel). Also, there are 

emissions differences between on-road and nonroad engines because the nonroad engines 

are generally of older technology. After being emitted in the engine exhaust, diesel 

exhaust undergoes dilution as well as chemical and physical changes in the atmosphere. 

The lifetime for some of the compounds present in diesel exhaust ranges from hours to 

days.371

 

369 U. S. EPA. 2002 National-Scale Air Toxics Assessment. 

http://www.epa.gov/ttn/atw/nata12002/risksum.html Docket EPA-HQ-OAR-2010-0162

370 U.S. EPA 2009. National-Scale Air Toxics Assessment for 2002. http://www.epa.gov/ttn/atw/nata2002/ 

Docket EPA-HQ-OAR-2010-0162

371 U.S. EPA (2002). Health Assessment Document for Diesel Engine Exhaust. EPA/600/8-90/057F Office 

of Research and Development, Washington DC. Retrieved on March 17, 2009 from 

http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=29060. Docket EPA-HQ-OAR-2010-0162
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(i) Diesel Exhaust: Potential Cancer Effects

In EPA’s 2002 Diesel Health Assessment Document (Diesel HAD),372 exposure 

to diesel exhaust was classified as likely to be carcinogenic to humans by inhalation from 

environmental exposures, in accordance with the revised draft 1996/1999 EPA cancer 

guidelines. A number of other agencies (National Institute for Occupational Safety and 

Health, the International Agency for Research on Cancer, the World Health Organization, 

California EPA, and the U.S. Department of Health and Human Services) have made 

similar classifications. However, EPA also concluded in the Diesel HAD that it is not 

possible currently to calculate a cancer unit risk for diesel exhaust due to a variety of 

factors that limit the current studies, such as limited quantitative exposure histories in 

occupational groups investigated for lung cancer.

For the Diesel HAD, EPA reviewed 22 epidemiologic studies on the subject of the 

carcinogenicity of workers exposed to diesel exhaust in various occupations, finding 

increased lung cancer risk, although not always statistically significant, in 8 out of 10 

cohort studies and 10 out of 12 case-control studies within several industries. Relative 

risk for lung cancer associated with exposure ranged from 1.2 to 1.5, although a few 

studies show relative risks as high as 2.6. Additionally, the Diesel HAD also relied on 

two independent meta-analyses, which examined 23 and 30 occupational studies 

respectively, which found statistically significant increases in smoking-adjusted relative 

lung cancer risk associated with exposure to diesel exhaust of 1.33 to 1.47. These metaanalyses demonstrate the effect of pooling many studies and in this case show the 

positive relationship between diesel exhaust exposure and lung cancer across a variety of 

diesel exhaust-exposed occupations.373,374

In the absence of a cancer unit risk, the Diesel HAD sought to provide additional 

insight into the significance of the diesel exhaust-cancer hazard by estimating possible 

ranges of risk that might be present in the population. An exploratory analysis was used 

to characterize a possible risk range by comparing a typical environmental exposure level 

for highway diesel sources to a selected range of occupational exposure levels. The 

occupationally observed risks were then proportionally scaled according to the exposure 

ratios to obtain an estimate of the possible environmental risk. A number of calculations 

are needed to accomplish this, and these can be seen in the EPA Diesel HAD. The 

outcome was that environmental risks from diesel exhaust exposure could range from a 

low of 10-4to 10-5to as high as 10-3, reflecting the range of occupational exposures that 

could be associated with the relative and absolute risk levels observed in the occupational 

studies. Because of uncertainties, the analysis acknowledged that the risks could be 

lower than 10-4or 10-5, and a zero risk from diesel exhaust exposure was not ruled out.

 

372 See U.S. EPA (2002) Diesel HAD, Note 371, at pp. 1-1, 1-2.

373 Bhatia, R., Lopipero, P., Smith, A. (1998). Diesel exposure and lung cancer. Epidemiology, 9(1), 84-91. 

Docket EPA-HQ-OAR-2010-0162

374 Lipsett, M. Campleman, S. (1999). Occupational exposure to diesel exhaust and lung cancer: a metaanalysis. Am J Public Health, 80(7), 1009-1017. Docket EPA-HQ-OAR-2010-0162
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(ii) Diesel Exhaust: Other Health Effects

Noncancer health effects of acute and chronic exposure to diesel exhaust 

emissions are also of concern to the EPA. EPA derived a diesel exhaust reference 

concentration (RfC) from consideration of four well-conducted chronic rat inhalation 

studies showing adverse pulmonary effects.375,376,377,378 The RfC is 5 μg/m3for diesel 

exhaust as measured by diesel particulate matter. This RfC does not consider allergenic 

effects such as those associated with asthma or immunologic effects. There is growing 

evidence, discussed in the Diesel HAD, that exposure to diesel exhaust can exacerbate 

these effects, but the exposure-response data are presently lacking to derive an RfC. The 

EPA Diesel HAD states, “With [diesel particulate matter] being a ubiquitous component 

of ambient PM, there is an uncertainty about the adequacy of the existing [diesel exhaust] 

noncancer database to identify all of the pertinent [diesel exhaust]-caused noncancer 

health hazards.” (p. 9-19). The Diesel HAD concludes “that acute exposure to [diesel 

exhaust] has been associated with irritation of the eye, nose, and throat, respiratory

symptoms (cough and phlegm), and neurophysiological symptoms such as headache, 

lightheadedness, nausea, vomiting, and numbness or tingling of the extremities.”379

(iii) Ambient PM2.5 Levels and Exposure to Diesel Exhaust PM

The Diesel HAD also briefly summarizes health effects associated with ambient 

PM and discusses the EPA’s annual PM2.5 NAAQS of 15 μg/m3. There is a much more 

extensive body of human data showing a wide spectrum of adverse health effects 

associated with exposure to ambient PM, of which diesel exhaust is an important 

component. The PM2.5 NAAQS is designed to provide protection from the noncancer 

and premature mortality effects of PM2.5 as a whole.

(iv) Diesel Exhaust PM Exposures

Exposure of people to diesel exhaust depends on their various activities, the time 

spent in those activities, the locations where these activities occur, and the levels of diesel 

exhaust pollutants in those locations. The major difference between ambient levels of 

diesel particulate and exposure levels for diesel particulate is that exposure accounts for a 

person moving from location to location, proximity to the emission source, and whether 

the exposure occurs in an enclosed environment.

 

375 Ishinishi, N. Kuwabara, N. Takaki, Y., et al. (1988). Long-term inhalation experiments on diesel 

exhaust. In: Diesel exhaust and health risks. Results of the HERP studies. Ibaraki, Japan: Research 

Committee for HERP Studies; pp.11-84. Docket EPA-HQ-OAR-2010-0162

376 Heinrich, U., Fuhst, R., Rittinghausen, S., et al. (1995). Chronic inhalation exposure of Wistar rats and 

two different strains of mice to diesel engine exhaust, carbon black, and titanium dioxide. Inhal Toxicol, 7,

553-556. Docket EPA-HQ-OAR-2010-0162

377 Mauderly, J.L., Jones, R.K., Griffith, W.C., et al. (1987). Diesel exhaust is a pulmonary carcinogen in 

rats exposed chronically by inhalation. Fundam. Appl. Toxicol., 9, 208-221. Docket EPA-HQ-OAR-2010-

0162

378 Nikula, K.J., Snipes, M.B., Barr, E.B., et al. (1995). Comparative pulmonary toxicities and 

carcinogenicities of chronically inhaled diesel exhaust and carbon black in F344 rats. Fundam. Appl. 

Toxicol, 25, 80-94. Docket EPA-HQ-OAR-2010-0162

379 See U.S. EPA (2002), Diesel HAD at Note 371, at p. 9-9.
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Occupational Exposures

Occupational exposures to diesel exhaust from mobile sources can be several 

orders of magnitude greater than typical exposures in the non-occupationally exposed 

population.

Over the years, diesel particulate exposures have been measured for a number of 

occupational groups. A wide range of exposures has been reported, from 2 μg/m3to 

1,280 μg/m3, for a variety of occupations. As discussed in the Diesel HAD, the National 

Institute of Occupational Safety and Health has estimated a total of 1,400,000 workers 

are occupationally exposed to diesel exhaust from on-road and nonroad vehicles.

Elevated Concentrations and Ambient Exposures in Mobile Source-Impacted Areas

Regions immediately downwind of highways or truck stops may experience 

elevated ambient concentrations of directly-emitted PM2.5 from diesel engines. Due to 

the unique nature of highways and truck stops, emissions from a large number of diesel 

engines are concentrated in a small area. Studies near roadways with high truck traffic 

indicate higher concentrations of components of diesel PM than other locations.380,381,382 

High ambient particle concentrations have also been reported near trucking terminals, 

truck stops, and bus garages.383,384,385 Additional discussion of exposure and health 

effects associated with traffic is included below in Section VII. B. (5) (j). 

(b) Benzene

The EPA’s Integrated Risk Information System (IRIS) database lists benzene as a 

known human carcinogen (causing leukemia) by all routes of exposure, and concludes

that exposure is associated with additional health effects, including genetic changes in 

both humans and animals and increased proliferation of bone marrow cells in 

mice.

386,387,388 EPA states in its IRIS database that data indicate a causal relationship 

 

380 Zhu, Y.; Hinds, W.C.; Kim, S.; Shen, S.; Sioutas, C. (2002) Study of ultrafine particles near a major 

highway with heavy-duty diesel traffic. Atmospheric Environment 36: 4323-4335. Docket EPA-HQOAR-2010-0162

381 Lena, T.S; Ochieng, V.; Holguín-Veras, J.; Kinney, P.L. (2002) Elemental carbon and PM2.5 levels in an 

urban community heavily impacted by truck traffic. Environ Health Perspect 110: 1009-1015. Docket 

EPA-HQ-OAR-2010-0162

382 Soliman, A.S.M.; Jacko, J.B.; Palmer, G.M. (2006) Development of an empirical model to estimate realworld fine particulate matter emission factors: the Traffic Air Quality model. J Air & Waste Manage 

Assoc 56: 1540-1549. Docket EPA-HQ-OAR-2010-0162

383 Davis, M.E.; Smith, T.J.; Laden, F.; Hart, J.E.; Ryan, L.M.; Garshick, E. (2006) Modeling particle 

exposure in U.S. trucking terminals. Environ Sci Techol 40: 4226-4232. Docket EPA-HQ-OAR-2010-

0162

384 Miller, T.L.; Fu, J.S.; Hromis, B.; Storey, J.M. (2007) Diesel truck idling emissions – measurements at a 

PM2.5 hot spot. Proceedings of the Annual Conference of the Transportation Research Board, paper no. 07-

2609. Docket EPA-HQ-OAR-2010-0162

385 Ramachandran, G.; Paulsen, D.; Watts, W.; Kittelson, D. (2005) Mass, surface area, and number metrics 

in diesel occupational exposure assessment. J Environ Monit 7: 728-735. Docket EPA-HQ-OAR-2010-

0162

386 U.S. EPA. 2000. Integrated Risk Information System File for Benzene. This material is available 

electronically at http://www.epa.gov/iris/subst/0276.htm. Docket EPA-HQ-OAR-2010-0162.
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between benzene exposure and acute lymphocytic leukemia and suggest a relationship 

between benzene exposure and chronic non-lymphocytic leukemia and chronic 

lymphocytic leukemia. The International Agency for Research on Carcinogens (IARC)

has determined that benzene is a human carcinogen and the U.S. Department of Health 

and Human Services (DHHS) has characterized benzene as a known human 

carcinogen.389,390

A number of adverse noncancer health effects including blood disorders, such as 

preleukemia and aplastic anemia, have also been associated with long-term exposure to 

benzene.391,392 The most sensitive noncancer effect observed in humans, based on current 

data, is the depression of the absolute lymphocyte count in blood.393, 394 In addition, 

recent work, including studies sponsored by the Health Effects Institute (HEI), provides 

evidence that biochemical responses are occurring at lower levels of benzene exposure 

than previously known.395,396,397,398 EPA’s IRIS program has not yet evaluated these new 

data.

 

387 International Agency for Research on Cancer. 1982. Monographs on the evaluation of carcinogenic risk 

of chemicals to humans, Volume 29. Some industrial chemicals and dyestuffs, World Health Organization, 

Lyon, France, p. 345-389. Docket EPA-HQ-OAR-2010-0162

388 Irons, R.D.; Stillman, W.S.; Colagiovanni, D.B.; Henry, V.A. 1992. Synergistic action of the benzene 

metabolite hydroquinone on myelopoietic stimulating activity of granulocyte/macrophage colonystimulating factor in vitro, Proc. Natl. Acad. Sci. 89:3691-3695. Docket EPA-HQ-OAR-2010-0162.

389 See IARC, Note 387, above.

390 U.S. Department of Health and Human Services National Toxicology Program 11th Report on 

Carcinogens available at: http://ntp.niehs.nih.gov/go/16183. Docket EPA-HQ-OAR-2010-0162

391 Aksoy, M. (1989). Hematotoxicity and carcinogenicity of benzene. Environ. Health Perspect. 82: 193-

197. Docket EPA-HQ-OAR-2010-0162.

392 Goldstein, B.D. (1988). Benzene toxicity. Occupational medicine. State of the Art Reviews. 3: 541-554. 

Docket EPA-HQ-OAR-2010-0162.

393 Rothman, N., G.L. Li, M. Dosemeci, W.E. Bechtold, G.E. Marti, Y.Z. Wang, M. Linet, L.Q. Xi, W. Lu, 

M.T. Smith, N. Titenko-Holland, L.P. Zhang, W. Blot, S.N. Yin, and R.B. Hayes (1996) Hematotoxicity 

among Chinese workers heavily exposed to benzene. Am. J. Ind. Med. 29: 236-246. Docket EPA-HQOAR-2010-0162.

394 U.S. EPA (2002) Toxicological Review of Benzene (Noncancer Effects). Environmental Protection 

Agency, Integrated Risk Information System, Research and Development, National Center for 

Environmental Assessment, Washington DC. This material is available electronically at 

http://www.epa.gov/iris/subst/0276.htm. Docket EPA-HQ-OAR-2010-0162.

395 Qu, O.; Shore, R.; Li, G.; Jin, X.; Chen, C.L.; Cohen, B.; Melikian, A.; Eastmond, D.; Rappaport, S.; Li, 

H.; Rupa, D.; Suramaya, R.; Songnian, W.; Huifant, Y.; Meng, M.; Winnik, M.; Kwok, E.; Li, Y.; Mu, 

R.; Xu, B.; Zhang, X.; Li, K. (2003) HEI Report 115, Validation & Evaluation of Biomarkers in Workers 

Exposed to Benzene in China. Docket EPA-HQ-OAR-2010-0162. 

396 Qu, Q., R. Shore, G. Li, X. Jin, L.C. Chen, B. Cohen, et al. (2002) Hematological changes among 

Chinese workers with a broad range of benzene exposures. Am. J. Industr. Med. 42: 275-285. Docket 

EPA-HQ-OAR-2010-0162.

397 Lan, Qing, Zhang, L., Li, G., Vermeulen, R., et al. (2004) Hematotoxically in Workers Exposed to Low

Levels of Benzene. Science 306: 1774-1776. Docket EPA-HQ-OAR-2010-0162.

398 Turtletaub, K.W. and Mani, C. (2003) Benzene metabolism in rodents at doses relevant to human 

exposure from Urban Air. Research Reports Health Effect Inst. Report No.113. Docket EPA-HQ-OAR2010-0162.
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(c) 1,3-Butadiene

EPA has characterized 1,3-butadiene as carcinogenic to humans by

inhalation.399,400 The IARC has determined that 1,3-butadiene is a human carcinogen and 

the U.S. DHHS has characterized 1,3-butadiene as a known human carcinogen.401,402 

There are numerous studies consistently demonstrating that 1,3-butadiene is metabolized 

into genotoxic metabolites by experimental animals and humans. The specific 

mechanisms of 1,3-butadiene-induced carcinogenesis are unknown; however, the 

scientific evidence strongly suggests that the carcinogenic effects are mediated by 

genotoxic metabolites. Animal data suggest that females may be more sensitive than 

males for cancer effects associated with 1,3-butadiene exposure; there are insufficient 

data in humans from which to draw conclusions about sensitive subpopulations. 1,3-

butadiene also causes a variety of reproductive and developmental effects in mice; no 

human data on these effects are available. The most sensitive effect was ovarian atrophy 

observed in a lifetime bioassay of female mice.403

(d) Formaldehyde

Since 1987, EPA has classified formaldehyde as a probable human carcinogen 

based on evidence in humans and in rats, mice, hamsters, and monkeys.404 EPA is 

currently reviewing recently published epidemiological data. For instance, research 

conducted by the National Cancer Institute found an increased risk of nasopharyngeal 

cancer and lymphohematopoietic malignancies such as leukemia among workers exposed 

to formaldehyde.405, 406 In an analysis of the lymphohematopoietic cancer mortality from

 

399 U.S. EPA (2002) Health Assessment of 1,3-Butadiene. Office of Research and Development, National 

Center for Environmental Assessment, Washington Office, Washington, DC. Report No. EPA600-P-98-

001F. This document is available electronically at http://www.epa.gov/iris/supdocs/buta-sup.pdf. Docket 

EPA-HQ-OAR-2010-0162.

400 U.S. EPA (2002) Full IRIS Summary for 1,3-butadiene (CASRN 106-99-0). Environmental Protection 

Agency, Integrated Risk Information System (IRIS), Research and Development, National Center for 

Environmental Assessment, Washington, DC http://www.epa.gov/iris/subst/0139.htm. Docket EPA-HQOAR-2010-0162

401 International Agency for Research on Cancer (1999) Monographs on the evaluation of carcinogenic risk 

of chemicals to humans, Volume 71, Re-evaluation of some organic chemicals, hydrazine and hydrogen 

peroxide and Volume 97 (in preparation), World Health Organization, Lyon, France. Docket EPA-HQOAR-2010-0162

402 U.S. Department of Health and Human Services (2005) National Toxicology Program 11th Report on 

Carcinogens available at: ntp.niehs.nih.gov/index.cfm?objectid=32BA9724-F1F6-975E7FCE50709CB4C932. Docket EPA-HQ-OAR-2010-0162

403 Bevan, C.; Stadler, J.C.; Elliot, G.S.; et al. (1996) Subchronic toxicity of 4-vinylcyclohexene in rats and 

mice by inhalation. Fundam. Appl. Toxicol. 32:1-10. Docket EPA-HQ-OAR-2010-0162.

404 U.S. EPA (1987) Assessment of Health Risks to Garment Workers and Certain Home Residents from 

Exposure to Formaldehyde, Office of Pesticides and Toxic Substances, April 1987. Docket EPA-HQ-OAR2010-0162.

405 Hauptmann, M.; Lubin, J. H.; Stewart, P. A.; Hayes, R. B.; Blair, A. 2003. Mortality from 

lymphohematopoetic malignancies among workers in formaldehyde industries. Journal of the National 

Cancer Institute 95: 1615-1623. Docket EPA-HQ-OAR-2010-0162.

406 Hauptmann, M.; Lubin, J. H.; Stewart, P. A.; Hayes, R. B.; Blair, A. 2004. Mortality from solid cancers 

among workers in formaldehyde industries. American Journal of Epidemiology 159: 1117-1130. Docket 

EPA-HQ-OAR-2010-0162.
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an extended follow-up of these workers, the National Cancer Institute confirmed an 

association between lymphohematopoietic cancer risk and peak exposures.407 A recent 

National Institute of Occupational Safety and Health study of garment workers also found 

increased risk of death due to leukemia among workers exposed to formaldehyde.408 

Extended follow-up of a cohort of British chemical workers did not find evidence of an 

increase in nasopharyngeal or lymphohematopoietic cancers, but a continuing statistically 

significant excess in lung cancers was reported.409 Recently, the IARC re-classified 

formaldehyde as a human carcinogen (Group 1).410 

Formaldehyde exposure also causes a range of noncancer health effects, including 

irritation of the eyes (burning and watering of the eyes), nose and throat. Effects from 

repeated exposure in humans include respiratory tract irritation, chronic bronchitis and 

nasal epithelial lesions such as metaplasia and loss of cilia. Animal studies suggest that 

formaldehyde may also cause airway inflammation – including eosinophil infiltration into 

the airways. There are several studies that suggest that formaldehyde may increase the 

risk of asthma – particularly in the young.411,412

(e) Acetaldehyde

Acetaldehyde is classified in EPA’s IRIS database as a probable human 

carcinogen, based on nasal tumors in rats, and is considered toxic by the inhalation, oral, 

and intravenous routes.

413

 Acetaldehyde is reasonably anticipated to be a human 

carcinogen by the U.S. DHHS in the 11th Report on Carcinogens and is classified as 

 

407 Beane Freeman, L. E.; Blair, A.; Lubin, J. H.; Stewart, P. A.; Hayes, R. B.; Hoover, R. N.; Hauptmann, 

M. 2009. Mortality from lymphohematopoietic malignancies among workers in formaldehyde industries: 

The National Cancer Institute cohort. J. National Cancer Inst. 101: 751-761. Docket EPA-HQ-OAR-2010-

0162.

408 Pinkerton, L. E. 2004. Mortality among a cohort of garment workers exposed to formaldehyde: an 

update. Occup. Environ. Med. 61: 193-200. Docket EPA-HQ-OAR-2010-0162.

409 Coggon, D, EC Harris, J Poole, KT Palmer. 2003. Extended follow-up of a cohort of British chemical 

workers exposed to formaldehyde. J National Cancer Inst. 95:1608-1615. Docket EPA-HQ-OAR-2010-

0162.

410 International Agency for Research on Cancer. 2006. Formaldehyde, 2-Butoxyethanol and 1-tertButoxypropan-2-ol. Volume 88. (in preparation), World Health Organization, Lyon, France. Docket EPAHQ-OAR-2010-0162

411 Agency for Toxic Substances and Disease Registry (ATSDR). 1999. Toxicological profile for 

Formaldehyde. Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service. 

http://www.atsdr.cdc.gov/toxprofiles/tp111.html Docket EPA-HQ-OAR-2010-0162.

412 WHO (2002) Concise International Chemical Assessment Document 40: Formaldehyde. Published 

under the joint sponsorship of the United Nations Environment Programme, the International Labour 

Organization, and the World Health Organization, and produced within the framework of the InterOrganization Programme for the Sound Management of Chemicals. Geneva. Docket EPA-HQ-OAR-2010-

0162.

413 U.S. EPA. 1991. Integrated Risk Information System File of Acetaldehyde. Research and Development, 

National Center for Environmental Assessment, Washington, DC. Available at

http://www.epa.gov/iris/subst/0290.htm. Docket EPA-HQ-OAR-2010-0162.
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possibly carcinogenic to humans (Group 2B) by the IARC.414,415 EPA is currently

conducting a reassessment of cancer risk from inhalation exposure to acetaldehyde.

The primary noncancer effects of exposure to acetaldehyde vapors include 

irritation of the eyes, skin, and respiratory tract.416 In short-term (4 week) rat studies, 

degeneration of olfactory epithelium was observed at various concentration levels of 

acetaldehyde exposure.

417, 418

 Data from these studies were used by EPA to develop an 

inhalation reference concentration. Some asthmatics have been shown to be a sensitive 

subpopulation to decrements in functional expiratory volume (FEV1 test) and 

bronchoconstriction upon acetaldehyde inhalation.419 The agency is currently conducting 

a reassessment of the health hazards from inhalation exposure to acetaldehyde. 

(f) Acrolein

Acrolein is extremely acrid and irritating to humans when inhaled, with acute 

exposure resulting in upper respiratory tract irritation, mucus hypersecretion and 

congestion. The intense irritancy of this carbonyl has been demonstrated during 

controlled tests in human subjects, who suffer intolerable eye and nasal mucosal sensory

reactions within minutes of exposure.420 These data and additional studies regarding 

acute effects of human exposure to acrolein are summarized in EPA’s 2003 IRIS Human 

Health Assessment for acrolein.421 Evidence available from studies in humans indicate 

that levels as low as 0.09 ppm (0.21 mg/m3) for five minutes may elicit subjective 

complaints of eye irritation with increasing concentrations leading to more extensive eye, 

nose and respiratory symptoms.422 Lesions to the lungs and upper respiratory tract of 

rats, rabbits, and hamsters have been observed after subchronic exposure to acrolein.423 

 

414 U.S. Department of Health and Human Services National Toxicology Program 11th Report on 

Carcinogens available at: ntp.niehs.nih.gov/index.cfm?objectid=32BA9724-F1F6-975E7FCE50709CB4C932. Docket EPA-HQ-OAR-2010-0162.

415 International Agency for Research on Cancer. 1999. Re-evaluation of some organic chemicals, 

hydrazine, and hydrogen peroxide. IARC Monographs on the Evaluation of Carcinogenic Risk of 

Chemical to Humans, Vol 71. Lyon, France. Docket EPA-HQ-OAR-2010-0162

416 See Integrated Risk Information System File of Acetaldehyde, Note 413, above.

417 Appleman, L. M., R. A. Woutersen, V. J. Feron, R. N. Hooftman, and W. R. F. Notten. 1986. Effects

of the variable versus fixed exposure levels on the toxicity of acetaldehyde in rats. J. Appl. Toxicol. 6: 331-

336. Docket EPA-HQ-OAR-2010-0162

418 Appleman, L.M., R.A. Woutersen, and V.J. Feron. 1982. Inhalation toxicity of acetaldehyde in rats. I. 

Acute and subacute studies. Toxicology. 23: 293-297. Docket EPA-HQ-OAR-2010-0162.

419 Myou, S.; Fujimura, M.; Nishi K.; Ohka, T.; and Matsuda, T. 1993. Aerosolized acetaldehyde induces 

histamine-mediated bronchoconstriction in asthmatics. Am. Rev. Respir.Dis.148(4 Pt 1): 940-3. Docket 

EPA-HQ-OAR-2010-0162

420 U.S. EPA (U.S. Environmental Protection Agency). (2003) Toxicological review of acrolein in support 

of summary information on Integrated Risk Information System (IRIS) National Center for Environmental 

Assessment, Washington, DC. EPA/635/R-03/003. p. 10. Available online at: 

http://www.epa.gov/ncea/iris/toxreviews/0364tr.pdf. Docket EPA-HQ-OAR-2010-0162

421 See U.S. EPA 2003 Toxicological review of acrolein, Note 420, above. 

422 See U.S. EPA 2003 Toxicological review of acrolein, Note 420, at p. 11.

423 Integrated Risk Information System File of Acrolein. Office of Research and Development, National 

Center for Environmental Assessment, Washington, DC. This material is available at 

http://www.epa.gov/iris/subst/0364.htm Docket EPA-HQ-OAR-2010-0162.
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Acute exposure effects in animal studies report bronchial hyper-responsiveness.424 In a 

recent study, the acute respiratory irritant effects of exposure to 1.1 ppm acrolein were 

more pronounced in mice with allergic airway disease by comparison to non-diseased 

mice which also showed decreases in respiratory rate.425 Based on these animal data and 

demonstration of similar effects in humans (e.g., reduction in respiratory rate), 

individuals with compromised respiratory function (e.g., emphysema, asthma) are 

expected to be at increased risk of developing adverse responses to strong respiratory

irritants such as acrolein. 

EPA determined in 2003 that the human carcinogenic potential of acrolein could 

not be determined because the available data were inadequate. No information was 

available on the carcinogenic effects of acrolein in humans and the animal data provided 

inadequate evidence of carcinogenicity.

426

 The IARC determined in 1995 that acrolein 

was not classifiable as to its carcinogenicity in humans.

427

(g) Polycyclic Organic Matter

The term polycyclic organic matter (POM) defines a broad class of compounds 

that includes the polycyclic aromatic hydrocarbon compounds (PAHs). One of these 

compounds, naphthalene, is discussed separately below. POM compounds are formed 

primarily from combustion and are present in the atmosphere in gas and particulate form. 

Cancer is the major concern from exposure to POM. Epidemiologic studies have 

reported an increase in lung cancer in humans exposed to diesel exhaust, coke oven 

emissions, roofing tar emissions, and cigarette smoke; all of these mixtures contain POM 

compounds.

428429

 Animal studies have reported respiratory tract tumors from inhalation 

exposure to benzo[a]pyrene and alimentary tract and liver tumors from oral exposure to 

benzo[a]pyrene. EPA has classified seven PAHs (benzo[a]pyrene, benz[a]anthracene, 

chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, dibenz[a,h]anthracene, and 

indeno[1,2,3-cd]pyrene) as Group B2, probable human carcinogens.430 Recent studies

have found that maternal exposures to PAHs in a population of pregnant women were 

 

424 See U.S. 2003 Toxicological review of acrolein, Note 420, at p. 15. 

425 Morris JB, Symanowicz PT, Olsen JE, et al. 2003. Immediate sensory nerve-mediated respiratory 

responses to irritants in healthy and allergic airway-diseased mice. J Appl Physiol 94(4):1563-1571. Docket 

EPA-HQ-OAR-2010-0162.

426 U.S. EPA. 2003. Integrated Risk Information System File of Acrolein. Research and Development, 

National Center for Environmental Assessment, Washington, DC. This material is available at 

http://www.epa.gov/iris/subst/0364.htm Docket EPA-HQ-OAR-2010-0162.

427 International Agency for Research on Cancer. 1995. Monographs on the evaluation of carcinogenic 

risk of chemicals to humans, Volume 63. Dry cleaning, some chlorinated solvents and other industrial 

chemicals, World Health Organization, Lyon, France. Docket EPA-HQ-OAR-2010-0162

428 Agency for Toxic Substances and Disease Registry (ATSDR). 1995. Toxicological profile for Polycyclic 

Aromatic Hydrocarbons (PAHs). Atlanta, GA: U.S. Department of Health and Human Services, Public 

Health Service. Available electronically at http://www.atsdr.cdc.gov/ToxProfiles/TP.asp?id=122&tid=25.

429 U.S. EPA (2002). Health Assessment Document for Diesel Engine Exhaust. EPA/600/8-90/057F Office 

of Research and Development, Washington DC. 

http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=29060. Docket EPA-HQ-OAR-2010-0162

430 U.S. EPA (1997). Integrated Risk Information System File of indeno(1,2,3-cd)pyrene. Research and 

Development, National Center for Environmental Assessment, Washington, DC. This material is available 

electronically at http://www.epa.gov/ncea/iris/subst/0457.htm.
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441 of 971

associated with several adverse birth outcomes, including low birth weight and reduced 

length at birth, as well as impaired cognitive development in preschool children (3 years 

of age).431,432 EPA has not yet evaluated these recent studies.

(h) Naphthalene

Naphthalene is found in small quantities in gasoline and diesel fuels. 

Naphthalene emissions have been measured in larger quantities in both gasoline and 

diesel exhaust compared with evaporative emissions from mobile sources, indicating it is 

primarily a product of combustion. EPA released an external review draft of a 

reassessment of the inhalation carcinogenicity of naphthalene based on a number of 

recent animal carcinogenicity studies.433 The draft reassessment completed external peer 

review.434 Based on external peer review comments received, additional analyses are 

being undertaken. This external review draft does not represent official agency opinion 

and was released solely for the purposes of external peer review and public comment. 

The National Toxicology Program listed naphthalene as "reasonably anticipated to be a 

human carcinogen" in 2004 on the basis of bioassays reporting clear evidence of 

carcinogenicity in rats and some evidence of carcinogenicity in mice.435 California EPA 

has released a new risk assessment for naphthalene, and the IARC has reevaluated 

naphthalene and re-classified it as Group 2B: possibly carcinogenic to humans.436 

Naphthalene also causes a number of chronic non-cancer effects in animals, including 

abnormal cell changes and growth in respiratory and nasal tissues.437

(i) Other Air Toxics

In addition to the compounds described above, other compounds in gaseous 

hydrocarbon and PM emissions from heavy-duty vehicles will be affected by this final 

action. Mobile source air toxic compounds that would potentially be impacted include 

 

431 Perera, F.P.; Rauh, V.; Tsai, W-Y.; et al. (2002) Effect of transplacental exposure to environmental 

pollutants on birth outcomes in a multiethnic population. Environ Health Perspect. 111: 201-205.

432 Perera, F.P.; Rauh, V.; Whyatt, R.M.; Tsai, W.Y.; Tang, D.; Diaz, D.; Hoepner, L.; Barr, D.; Tu, Y.H.; 

Camann, D.; Kinney, P. (2006) Effect of prenatal exposure to airborne polycyclic aromatic hydrocarbons 

on neurodevelopment in the first 3 years of life among inner-city children. Environ Health Perspect 114: 

1287-1292.

433 U. S. EPA. 2004. Toxicological Review of Naphthalene (Reassessment of the Inhalation Cancer Risk), 

Environmental Protection Agency, Integrated Risk Information System, Research and Development, 

National Center for Environmental Assessment, Washington, DC. This material is available electronically 

at http://www.epa.gov/iris/subst/0436.htm. Docket EPA-HQ-OAR-2010-0162.

434 Oak Ridge Institute for Science and Education. (2004). External Peer Review for the IRIS 

Reassessment of the Inhalation Carcinogenicity of Naphthalene. August 2004. 

http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=84403 Docket EPA-HQ-OAR-2010-0162.

435 National Toxicology Program (NTP). (2004). 11th Report on Carcinogens. Public Health Service, 

U.S. Department of Health and Human Services, Research Triangle Park, NC. Available from: http://ntpserver.niehs.nih.gov. Docket EPA-HQ-OAR-2010-0162.

436 International Agency for Research on Cancer. (2002). Monographs on the Evaluation of the 

Carcinogenic Risk of Chemicals for Humans. Vol. 82. Lyon, France. Docket EPA-HQ-OAR-2010-0162.

437 U. S. EPA. 1998. Toxicological Review of Naphthalene, Environmental Protection Agency, Integrated 

Risk Information System, Research and Development, National Center for Environmental Assessment, 

Washington, DC. This material is available electronically at http://www.epa.gov/iris/subst/0436.htm 

Docket EPA-HQ-OAR-2010-0162.
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ethylbenzene, propionaldehyde, toluene, and xylene. Information regarding the health 

effects of these compounds can be found in EPA’s IRIS database.438

(j) Exposure and Health Effects Associated with Traffic

Populations who live, work, or attend school near major roads experience 

elevated exposure concentrations to a wide range of air pollutants, as well as higher risks 

for a number of adverse health effects. While the previous sections of this preamble have 

focused on the health effects associated with individual criteria pollutants or air toxics, 

this section discusses the mixture of different exposures near major roadways, rather than 

the effects of any single pollutant. As such, this section emphasizes traffic-related air 

pollution, in general, as the relevant indicator of exposure rather than any particular 

pollutant.

Concentrations of many traffic-generated air pollutants are elevated for up to 300-

500 meters downwind of roads with high traffic volumes.

439

 Numerous sources on roads 

contribute to elevated roadside concentrations, including exhaust and evaporative 

emissions, and resuspension of road dust and tire and brake wear. Concentrations of 

several criteria and hazardous air pollutants are elevated near major roads. Furthermore, 

different semi-volatile organic compounds and chemical components of particulate 

matter, including elemental carbon, organic material, and trace metals, have been 

reported at higher concentrations near major roads.

 Populations near major roads experience greater risk of certain adverse health 

effects. The Health Effects Institute published a report on the health effects of trafficrelated air pollution.440

 It concluded that evidence is “sufficient to infer the presence of a

causal association” between traffic exposure and exacerbation of childhood asthma 

symptoms. The HEI report also concludes that the evidence is either “sufficient” or 

“suggestive but not sufficient” for a causal association between traffic exposure and new 

childhood asthma cases. A review of asthma studies by Salam et al. (2008) reaches 

similar conclusions.441 The HEI report also concludes that there is “suggestive” evidence 

for pulmonary function deficits associated with traffic exposure, but concluded that there 

is “inadequate and insufficient” evidence for causal associations with respiratory health 

care utilization, adult-onset asthma, chronic obstructive pulmonary disease symptoms, 

 

438 U.S. EPA Integrated Risk Information System (IRIS) database is available at: www.epa.gov/iris 

439 Zhou, Y.; Levy, J.I. (2007) Factors influencing the spatial extent of mobile source air pollution 

impacts: a meta-analysis. BMC Public Health 7: 89. doi:10.1186/1471-2458-7-89 Docket EPA-HQOAR-2010-0162.

440 HEI Panel on the Health Effects of Air Pollution. (2010) Traffic-related air pollution: a critical review 

of the literature on emissions, exposure, and health effects. [Online at www.healtheffects.org] Docket 

EPA-HQ-OAR-2010-0162.

441 Salam, M.T.; Islam, T.; Gilliland, F.D. (2008) Recent evidence for adverse effects of residential

proximity to traffic sources on asthma. Current Opin Pulm Med 14: 3-8. Docket EPA-HQ-OAR-2010-

0162
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and allergy. A review by Holguin (2008) notes that the effects of traffic on asthma may

be modified by nutrition status, medication use, and genetic factors.442

The HEI report also concludes that evidence is “suggestive” of a causal 

association between traffic exposure and all-cause and cardiovascular mortality. There is 

also evidence of an association between traffic-related air pollutants and cardiovascular 

effects such as changes in heart rhythm, heart attack, and cardiovascular disease. The 

HEI report characterizes this evidence as “suggestive” of a causal association, and an 

independent epidemiological literature review by Adar and Kaufman (2007) concludes 

that there is “consistent evidence” linking traffic-related pollution and adverse 

cardiovascular health outcomes.443

Some studies have reported associations between traffic exposure and other health 

effects, such as birth outcomes (e.g., low birth weight) and childhood cancer. The HEI 

report concludes that there is currently “inadequate and insufficient” evidence for a 

causal association between these effects and traffic exposure. A review by RaaschouNielsen and Reynolds (2006) concluded that evidence of an association between 

childhood cancer and traffic-related air pollutants is weak, but noted the inability to draw 

firm conclusions based on limited evidence.444

There is a large population in the United States living in close proximity of major 

roads. According to the Census Bureau’s American Housing Survey for 2007, 

approximately 20 million residences in the United States, 15.6% of all homes, are located 

within 300 feet (91 m) of a highway with 4+ lanes, a railroad, or an airport.445 Therefore, 

at current population of approximately 309 million, assuming that population and housing 

are similarly distributed, there are over 48 million people in the United States living near 

such sources. The HEI report also notes that in two North American cities, Los Angeles 

and Toronto, over 40% of each city’s population live within 500 meters of a highway or 

100 meters of a major road. It also notes that about 33% of each city’s population resides 

within 50 meters of major roads. Together, the evidence suggests that a large U.S. 

population lives in areas with elevated traffic-related air pollution.

People living near roads are often socioeconomically disadvantaged. According 

to the 2007 American Housing Survey, a renter-occupied property is over twice as likely 

as an owner-occupied property to be located near a highway with 4+ lanes, railroad or 

airport. In the same survey, the median household income of rental housing occupants 

was less than half that of owner-occupants ($28,921/$59,886). Numerous studies in 

 

442 Holguin, F. (2008) Traffic, outdoor air pollution, and asthma. Immunol Allergy Clinics North Am 28: 

577-588. Docket EPA-HQ-OAR-2010-0162.

443 Adar, S.D.; Kaufman, J.D. (2007) Cardiovascular disease and air pollutants: evaluating and improving 

epidemiological data implicating traffic exposure. Inhal Toxicol 19: 135-149. Docket EPA-HQ-OAR2010-0162.

444 Raaschou-Nielsen, O.; Reynolds, P. (2006) Air pollution and childhood cancer: a review of the 

epidemiological literature. Int J Cancer 118: 2920-2929. Docket EPA-HQ-OAR-2010-0162

445 U.S. Census Bureau (2008) American Housing Survey for the United States in 2007. Series H-150 

(National Data), Table 1A-7. [Accessed at 

http://www.census.gov/hhes/www/housing/ahs/ahs07/ahs07.html on January 22, 2009] Docket EPA-HQOAR-2010-0162.
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individual urban areas report higher levels of traffic-related air pollutants in areas with 

high minority or poor populations.446,447,448

Students may also be exposed in situations where schools are located near major 

roads. In a study of nine metropolitan areas across the United States, Appatova et al. 

(2008) found that on average greater than 33% of schools were located within 400 m of 

an Interstate, U.S., or state highway, while 12% were located within 100 m.449 The study

also found that among the metropolitan areas studied, schools in the Eastern United 

States were more often sited near major roadways than schools in the Western United 

States.

Demographic studies of students in schools near major roadways suggest that this 

population is more likely than the general student population to be of non-white race or 

Hispanic ethnicity, and more often live in low socioeconomic status locations. 450,451,452 

There is some inconsistency in the evidence, which may be due to different local 

development patterns and measures of traffic and geographic scale used in the studies.449 

C. Environmental Effects of Non-GHG Pollutants

In this section we discuss some of the environmental effects of PM and its 

precursors such as visibility impairment, atmospheric deposition, and materials damage 

and soiling, as well as environmental effects associated with the presence of ozone in the 

ambient air, such as impacts on plants, including trees, agronomic crops and urban 

ornamentals, and environmental effects associated with air toxics.

(1) Visibility

Visibility can be defined as the degree to which the atmosphere is transparent to 

visible light.453 Visibility impairment is caused by light scattering and absorption by suspended 

 

446 Lena, T.S.; Ochieng, V.; Carter, M.; Holguín-Veras, J.; Kinney, P.L. (2002) Elemental carbon and PM2.5

levels in an urban community heavily impacted by truck traffic. Environ Health Perspect 110: 1009-1015.

Docket EPA-HQ-OAR-2010-0162

447 Wier, M.; Sciammas, C.; Seto, E.; Bhatia, R.; Rivard, T. (2009) Health, traffic, and environmental 

justice: collaborative research and community action in San Francisco, California. Am J Public Health 99: 

S499-S504. Docket EPA-HQ-OAR-2010-0162

448 Forkenbrock, D.J. and L.A. Schweitzer, Environmental Justice and Transportation Investment Policy. 

Iowa City: University of Iowa, 1997. Docket EPA-HQ-OAR-2010-0162

449 Appatova, A.S.; Ryan, P.H.; LeMasters, G.K.; Grinshpun, S.A. (2008) Proximal exposure of public 

schools and students to major roadways: a nationwide U.S. survey. J Environ Plan Mgmt Docket EPAHQ-OAR-2010-0162

450 Green, R.S.; Smorodinsky, S.; Kim, J.J.; McLaughlin, R.; Ostro, B. (2004) Proximity of California 

public schools to busy roads. Environ Health Perspect 112: 61-66. Docket EPA-HQ-OAR-2010-0162

451 Houston, D.; Ong, P.; Wu, J.; Winer, A. (2006) Proximity of licensed child care facilities to nearroadway vehicle pollution. Am J Public Health 96: 1611-1617. Docket EPA-HQ-OAR-2010-0162

452 Wu, Y.; Batterman, S. (2006) Proximity of schools in Detroit, Michigan to automobile and truck traffic. 

J Exposure Sci Environ Epidemiol 16: 457-470. Docket EPA-HQ-OAR-2010-0162

453 National Research Council, 1993. Protecting Visibility in National Parks and Wilderness Areas. 

National Academy of Sciences Committee on Haze in National Parks and Wilderness Areas. National 

Academy Press, Washington, DC. Docket EPA-HQ-OAR-2010-0162. This book can be viewed on the 

National Academy Press Website at http://www.nap.edu/books/0309048443/html/
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particles and gases. Visibility is important because it has direct significance to people’s 

enjoyment of daily activities in all parts of the country. Individuals value good visibility

for the well-being it provides them directly, where they live and work, and in places 

where they enjoy recreational opportunities. Visibility is also highly valued in significant 

natural areas, such as national parks and wilderness areas, and special emphasis is given 

to protecting visibility in these areas. For more information on visibility see the final 

2009 PM ISA.454

EPA is pursuing a two-part strategy to address visibility impairment. First, EPA 

developed the regional haze program (64 FR 35714) which was put in place in July 1999 

to protect the visibility in Mandatory Class I Federal areas. There are 156 national parks, 

forests and wilderness areas categorized as Mandatory Class I Federal areas (62 FR 

38680-38681, July 18, 1997). These areas are defined in CAA section 162 as those 

national parks exceeding 6,000 acres, wilderness areas and memorial parks exceeding 

5,000 acres, and all international parks which were in existence on August 7, 1977. 

Second, EPA has concluded that PM2.5 causes adverse effects on visibility in other areas 

that are not protected by the Regional Haze Rule, depending on PM2.5 concentrations and 

other factors that control their visibility impact effectiveness such as dry chemical 

composition and relative humidity (i.e., an indicator of the water composition of the 

particles), and has set secondary PM2.5 standards to address these areas. The existing 

annual primary and secondary PM2.5 standards have been remanded by the D.C. Circuit 

(see American Farm Bureau v. EPA, 559 F. 3d 512 (D.C. Cir. 2009) and are being 

addressed in the currently ongoing PM NAAQS review. 

(2) Plant and Ecosystem Effects of Ozone

Elevated ozone levels contribute to environmental effects, with impacts to plants 

and ecosystems being of most concern. Ozone can produce both acute and chronic injury

in sensitive species depending on the concentration level and the duration of the 

exposure. Ozone effects also tend to accumulate over the growing season of the plant, so 

that even low concentrations experienced for a longer duration have the potential to 

create chronic stress on vegetation. Ozone damage to plants includes visible injury to 

leaves and impaired photosynthesis, both of which can lead to reduced plant growth and 

reproduction, resulting in reduced crop yields, forestry production, and use of sensitive 

ornamentals in landscaping. In addition, the impairment of photosynthesis, the process 

by which the plant makes carbohydrates (its source of energy and food), can lead to a 

subsequent reduction in root growth and carbohydrate storage below ground, resulting in 

other, more subtle plant and ecosystems impacts. 

These latter impacts include increased susceptibility of plants to insect attack, 

disease, harsh weather, interspecies competition and overall decreased plant vigor. The 

adverse effects of ozone on forest and other natural vegetation can potentially lead to 

species shifts and loss from the affected ecosystems, resulting in a loss or reduction in 

associated ecosystem goods and services. Lastly, visible ozone injury to leaves can result 

in a loss of aesthetic value in areas of special scenic significance like national parks and 

 

454 See U.S. EPA 2009 Final PM ISA, Note 355. 
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wilderness areas. The final 2006 Ozone Air Quality Criteria Document presents more 

detailed information on ozone effects on vegetation and ecosystems.

(3) Atmospheric Deposition

Wet and dry deposition of ambient particulate matter delivers a complex mixture 

of metals (e.g., mercury, zinc, lead, nickel, aluminum, cadmium), organic compounds 

(e.g., polycyclic organic matter, dioxins, furans) and inorganic compounds (e.g., nitrate, 

sulfate) to terrestrial and aquatic ecosystems. The chemical form of the compounds 

deposited depends on a variety of factors including ambient conditions (e.g., temperature, 

humidity, oxidant levels) and the sources of the material. Chemical and physical 

transformations of the compounds occur in the atmosphere as well as the media onto 

which they deposit. These transformations in turn influence the fate, bioavailability and 

potential toxicity of these compounds. Atmospheric deposition has been identified as a 

key component of the environmental and human health hazard posed by several 

pollutants including mercury, dioxin and PCBs.455

Adverse impacts on water quality can occur when atmospheric contaminants 

deposit to the water surface or when material deposited on the land enters a waterbody 

through runoff. Potential impacts of atmospheric deposition to waterbodies include those 

related to both nutrient and toxic inputs. Adverse effects to human health and welfare 

can occur from the addition of excess nitrogen via atmospheric deposition. The nitrogennutrient enrichment contributes to toxic algae blooms and zones of depleted oxygen, 

which can lead to fish kills, frequently in coastal waters. Deposition of heavy metals or 

other toxics may lead to the human ingestion of contaminated fish, impairment of 

drinking water, damage to the marine ecology, and limits to recreational uses. Several 

studies have been conducted in U.S. coastal waters and in the Great Lakes Region in 

which the role of ambient PM deposition and runoff is investigated.456,457,458,459,460 

Atmospheric deposition of nitrogen and sulfur contributes to acidification, 

altering biogeochemistry and affecting animal and plant life in terrestrial and aquatic 

ecosystems across the United States. The sensitivity of terrestrial and aquatic ecosystems 

to acidification from nitrogen and sulfur deposition is predominantly governed by

 

455 U.S. EPA (2000) Deposition of Air Pollutants to the Great Waters: Third Report to Congress. Office of 

Air Quality Planning and Standards. EPA-453/R-00-0005. Docket EPA-HQ-OAR-2010-0162.

456 U.S. EPA (2004) National Coastal Condition Report II. Office of Research and Development/ Office of 

Water. EPA-620/R-03/002. Docket EPA-HQ-OAR-2010-0162.

457 Gao, Y., E.D. Nelson, M.P. Field, et al. 2002. Characterization of atmospheric trace elements on PM2.5

particulate matter over the New York-New Jersey harbor estuary. Atmos. Environ. 36: 1077-1086. Docket 

EPA-HQ-OAR-2010-0162.

458 Kim, G., N. Hussain, J.R. Scudlark, and T.M. Church. 2000. Factors influencing the atmospheric 

depositional fluxes of stable Pb, 210Pb, and 7Be into Chesapeake Bay. J. Atmos. Chem. 36: 65-79. 

Docket EPA-HQ-OAR-2010-0162.

459 Lu, R., R.P. Turco, K. Stolzenbach, et al. 2003. Dry deposition of airborne trace metals on the Los 

Angeles Basin and adjacent coastal waters. J. Geophys. Res. 108(D2, 4074): AAC 11-1 to 11-24. Docket 

EPA-HQ-OAR-2010-0162.

460 Marvin, C.H., M.N. Charlton, E.J. Reiner, et al. 2002. Surficial sediment contamination in Lakes Erie 

and Ontario: A comparative analysis. J. Great Lakes Res. 28(3): 437-450. Docket EPA-HQ-OAR-2010-

0162.
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geology. Prolonged exposure to excess nitrogen and sulfur deposition in sensitive areas 

acidifies lakes, rivers and soils. Increased acidity in surface waters creates inhospitable 

conditions for biota and affects the abundance and nutritional value of preferred prey

species, threatening biodiversity and ecosystem function. Over time, acidifying

deposition also removes essential nutrients from forest soils, depleting the capacity of 

soils to neutralize future acid loadings and negatively affecting forest sustainability. 

Major effects include a decline in sensitive forest tree species, such as red spruce (Picea 

rubens) and sugar maple (Acer saccharum), and a loss of biodiversity of fishes, 

zooplankton, and macro invertebrates.

In addition to the role nitrogen deposition plays in acidification, nitrogen 

deposition also leads to nutrient enrichment and altered biogeochemical cycling. In 

aquatic systems increased nitrogen can alter species assemblages and cause 

eutrophication. In terrestrial systems nitrogen loading can lead to loss of nitrogen 

sensitive lichen species, decreased biodiversity of grasslands, meadows and other 

sensitive habitats, and increased potential for invasive species. For a broader explanation 

of the topics treated here, refer to the description in Section 7.1.2 of the RIA.

Adverse impacts on soil chemistry and plant life have been observed for areas 

heavily influenced by atmospheric deposition of nutrients, metals and acid species, 

resulting in species shifts, loss of biodiversity, forest decline and damage to forest 

productivity. Potential impacts also include adverse effects to human health through 

ingestion of contaminated vegetation or livestock (as in the case for dioxin deposition), 

reduction in crop yield, and limited use of land due to contamination. 

Atmospheric deposition of pollutants can reduce the aesthetic appeal of buildings 

and culturally important articles through soiling, and can contribute directly (or in 

conjunction with other pollutants) to structural damage by means of corrosion or erosion. 

Atmospheric deposition may affect materials principally by promoting and accelerating 

the corrosion of metals, by degrading paints, and by deteriorating building materials such 

as concrete and limestone. Particles contribute to these effects because of their 

electrolytic, hygroscopic, and acidic properties, and their ability to adsorb corrosive gases 

(principally sulfur dioxide). 

(4) Environmental Effects of Air Toxics

Emissions from producing, transporting and combusting fuel contribute to 

ambient levels of pollutants that contribute to adverse effects on vegetation. Volatile 

organic compounds, some of which are considered air toxics, have long been suspected to 

play a role in vegetation damage.461 In laboratory experiments, a wide range of tolerance 

to VOCs has been observed.462 Decreases in harvested seed pod weight have been 

reported for the more sensitive plants, and some studies have reported effects on seed 

 

461 U.S. EPA. 1991. Effects of organic chemicals in the atmosphere on terrestrial plants. EPA/600/3-91/001. 

Docket EPA-HQ-OAR-2010-0162.

462 Cape JN, ID Leith, J Binnie, J Content, M Donkin, M Skewes, DN Price AR Brown, AD Sharpe. 2003. 

Effects of VOCs on herbaceous plants in an open-top chamber experiment. Environ. Pollut. 124:341-343. 

Docket EPA-HQ-OAR-2010-0162. 
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germination, flowering and fruit ripening. Effects of individual VOCs or their role in 

conjunction with other stressors (e.g., acidification, drought, temperature extremes) have 

not been well studied. In a recent study of a mixture of VOCs including ethanol and 

toluene on herbaceous plants, significant effects on seed production, leaf water content 

and photosynthetic efficiency were reported for some plant species.463

Research suggests an adverse impact of vehicle exhaust on plants, which has in 

some cases been attributed to aromatic compounds and in other cases to nitrogen 

oxides.464, 465, 466 The impacts of VOCs on plant reproduction may have long-term 

implications for biodiversity and survival of native species near major roadways. Most of 

the studies of the impacts of VOCs on vegetation have focused on short-term exposure 

and few studies have focused on long-term effects of VOCs on vegetation and the 

potential for metabolites of these compounds to affect herbivores or insects.

D. Air Quality Impacts of Non-GHG Pollutants

Air quality modeling was performed to assess the impact of the heavy-duty 

vehicle standards on criteria and air toxic pollutants. In this section, we present 

information on current modeled levels of pollution as well as projections for 2030, with 

respect to ambient PM2.5, ozone, selected air toxics, visibility levels and nitrogen and 

sulfur deposition. The results are discussed in more detail in Section 8.2 of the RIA. 

We used the Community Multi-scale Air Quality (CMAQ) photochemical model, 

version 4.7.1, for our analysis. This version of CMAQ includes a number of 

improvements to previous versions of the model. These improvements are discussed in 

Section 8.2.2 of the RIA.

(1) Ozone

(a) Current Levels

8-hour ozone concentrations exceeding the level of the ozone NAAQS occur in 

many parts of the country. In 2008, the EPA amended the ozone NAAQS (73 FR 16436, 

March 27, 2008). The final 2008 ozone NAAQS rule set forth revisions to the previous 

1997 NAAQS for ozone to provide increased protection of public health and welfare. On 

January 6, 2010, EPA proposed to reconsider the 2008 ozone NAAQS to ensure that they

are requisite to protect public health with an ample margin of safety, and requisite to 

protect public welfare (75 FR 2938, January 19, 2010). EPA intends to complete the 

 

463 Cape JN, ID Leith, J Binnie, J Content, M Donkin, M Skewes, DN Price AR Brown, AD Sharpe. 2003. 

Effects of VOCs on herbaceous plants in an open-top chamber experiment. Environ. Pollut. 124:341-343. 

Docket EPA-HQ-OAR-2010-0162. 

464 Viskari E-L. 2000. Epicuticular wax of Norway spruce needles as indicator of traffic pollutant 

deposition. Water, Air, and Soil Pollut. 121:327-337. Docket EPA-HQ-OAR-2010-0162.

465 Ugrekhelidze D, F Korte, G Kvesitadze. 1997. Uptake and transformation of benzene and toluene by 

plant leaves. Ecotox. Environ. Safety 37:24-29. Docket EPA-HQ-OAR-2010-0162.

466 Kammerbauer H, H Selinger, R Rommelt, A Ziegler-Jons, D Knoppik, B Hock. 1987. Toxic 

components of motor vehicle emissions for the spruce Picea abies. Environ. Pollut. 48:235-243. Docket 

EPA-HQ-OAR-2010-0162.
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reconsideration by July 31, 2011. If, as a result of the reconsideration, EPA promulgates 

different ozone standards, the new 2011 ozone standards would replace the 2008 ozone 

standards and the requirement to designate areas for the replaced 2008 standards would 

no longer apply. 

As of April 21, 2011 there are 44 areas designated as nonattainment for the 1997 

8-hour ozone NAAQS, comprising 242 full or partial counties with a total population of 

over 118 million people. These numbers do not include the people living in areas where 

there is a future risk of failing to maintain or attain the 1997 8-hour ozone NAAQS. The 

numbers above likely underestimate the number of counties that are not meeting the 

ozone NAAQS because the nonattainment areas associated with the more stringent 2008 

8-hour ozone NAAQS have not yet been designated. Table VII-7 provides an estimate, 

based on 2006-08 air quality data, of the counties with design values greater than the 

2008 8-hour ozone NAAQS of 0.075 ppm. 

Table VII-7 Counties with Design Values Greater Than the Ozone NAAQS

Standard Number of 

Counties

Populationa

1997 Ozone Standard: counties within the 54 

areas currently designated as nonattainment 

(as of 1/6/10)

266 122,343, 799

2008 Ozone Standard: additional counties 

that would not meet the 2008 NAAQS (based 

on 2006-2008 air quality data)b

156 36,678,478

Total 422 159,022,277

Notes:

a

Population numbers are from 2000 census data.

b Area designations for the 2008 ozone NAAQS have not yet been made. Nonattainment for the 2008 

Ozone NAAQS would be based on three years of air quality data from later years. Also, the county 

numbers in this row include only the counties with monitors violating the 2008 Ozone NAAQS. The 

numbers in this table may be an underestimate of the number of counties and populations that will 

eventually be included in areas with multiple counties designated nonattainment.

(b) Projected Levels without this Final Action

States with 8-hour ozone nonattainment areas are required to take action to bring 

those areas into compliance in the future. Based on the final rule designating and 

classifying 8-hour ozone nonattainment areas for the 1997 standard (69 FR 23951, April 

30, 2004), most 8-hour ozone nonattainment areas will be required to attain the ozone 

NAAQS in the 2007 to 2013 time frame and then maintain the NAAQS thereafter. As 

noted, EPA is reconsidering the 2008 ozone NAAQS. If EPA promulgates different 

ozone NAAQS in 2011 as a result of the reconsideration, these standards would replace 

the 2008 ozone NAAQS and there would no longer be a requirement to designate areas 

for the 2008 NAAQS. Attainment dates for any 2011 ozone NAAQS would range from 3 

to 20 years from designation, depending on the area’s classification. 
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EPA has already adopted many emission control programs that are expected to 

reduce ambient ozone levels and assist in reducing the number of areas that fail to 

achieve the ozone NAAQS. Even so, our air quality modeling projects that in 2030, with 

all current controls but excluding the impacts of the heavy-duty standards, up to 10

counties with a population of over 30 million may not attain the 2008 ozone standard of 

0.075 ppm (75 ppb). These numbers do not account for those areas that are close to (e.g., 

within 10 percent of) the 2008 ozone standard. These areas, although not violating the 

standards, will also be impacted by changes in ozone as they work to ensure long-term 

maintenance of the ozone NAAQS.

(c) Projected Levels with this Final Action

Our modeling indicates ozone design value concentrations will decrease in many

areas of the country due to this action. The decreases in ozone design values are likely 

due to projected tailpipe reductions in NOX and projected upstream emissions decreases 

in NOX and VOCs from reduced gasoline production. The majority of the ozone design 

value decreases are less than 1 ppb. The maximum projected decrease in an 8-hour ozone 

design value is 1.57 ppb in Jefferson County, Tennessee. On a population-weighted 

basis, the average modeled 8-hour ozone design values are projected to decrease by 0.39 

ppb in 2030 and the design values for those counties that are projected to be above the 

2008 ozone standard in 2030 will see population-weighted decreases of 0.16 ppb due to 

the heavy-duty standards. 

(2) Particulate Matter

(a) Current Levels

PM2.5 concentrations exceeding the level of the PM2.5 NAAQS occur in many 

parts of the country. In 2005, EPA designated 39 nonattainment areas for the 1997 PM2.5

NAAQS (70 FR 943, January 5, 2005). These areas are composed of 208 full or partial 

counties with a total population exceeding 88 million. The 1997 PM2.5 NAAQS was 

revised in 2006 and the 2006 24-hour PM2.5 NAAQS became effective on December 18, 

2006. On October 8, 2009, the EPA issued final nonattainment area designations for the 

2006 24-hour PM2.5 NAAQS (74 FR 58688, November 13, 2009). These designations 

include 32 areas composed of 121 full or partial counties with a population of over 70 

million. In total, there are 54 PM2.5 nonattainment areas composed of 243 counties with a 

population of almost 102 million people.

(b) Projected Levels without this Final Action

States with PM2.5 nonattainment areas are required to take action to bring those 

areas into compliance in the future. Areas designated as not attaining the 1997 PM2.5

NAAQS will need to attain the 1997 standards in the 2010 to 2015 time frame, and then 

maintain them thereafter. The 2006 24-hour PM2.5 nonattainment areas will be required 

to attain the 2006 24-hour PM2.5 NAAQS in the 2014 to 2019 time frame and then be 

required to maintain the 2006 24-hour PM2.5 NAAQS thereafter. The heavy-duty 
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standards finalized in this action become effective in 2012 and therefore may be useful to 

states in attaining or maintaining the PM2.5 NAAQS.

EPA has already adopted many emission control programs that are expected to 

reduce ambient PM2.5 levels and which will assist in reducing the number of areas that 

fail to achieve the PM2.5 NAAQS. Even so, our air quality modeling projects that in 

2030, with all current controls but excluding the impacts of the heavy-duty standards 

adopted here, at least 4 counties with a population of almost 7 million may not attain the 

1997 annual PM2.5 standard of 15 μg/m3and 22 counties with a population of over 33 

million may not attain the 2006 24-hour PM2.5 standard of 35 μg/m3. These numbers do 

not account for those areas that are close to (e.g., within 10 percent of) the PM2.5

standards. These areas, although not violating the standards, will also benefit from any

reductions in PM2.5 ensuring long-term maintenance of the PM2.5 NAAQS. 

(c) Projected Levels with this Final Action

Air quality modeling performed for this final action shows that in 2030 the 

majority of the modeled counties will see decreases of less than 0.01 μg/m

3

in their 

annual PM2.5 design values. The decreases in annual PM2.5 design values that we see in 

some counties are likely due to emission reductions related to lower fuel production at 

existing oil refineries and/or reductions in PM2.5 precursor emissions (NOX, SOX, and 

VOCs) due to improvements in road load. The maximum projected decrease in an annual 

PM2.5 design value is 0.03 μg/m

3

in Allen County, Indiana and Canyon County, Idaho. 

On a population-weighted basis, the average modeled 2030 annual PM2.5 design value is 

projected to decrease by 0.01 μg/m

3

due to this final action. 

In addition to looking at annual PM2.5 design values, we also modeled the impact 

of the standards on 24-hour PM2.5 design values. Air quality modeling performed for this 

final action shows that in 2030 the majority of the modeled counties will see changes of 

between -0.05 μg/m

3

and 0 μg/m

3

in their 24-hour PM2.5 design values. The decreases in 

annual PM2.5 design values that we see in some counties are likely due to emission 

reductions related to lower fuel production at existing oil refineries and/or reductions in 

PM2.5 precursor emissions (NOX, SOX, and VOCs) due to improvements in road load. 

The maximum projected decrease in a 24-hour PM2.5 design value is 0.27 μg/m

3

in 

Canyon County, ID. There are also some counties that are projected to see increases of 

less than 0.1 μg/m

3

in their 24-hour PM2.5 design values. These small increases in 24-

hour PM2.5 design values are likely related to downstream emission increases from APUs. 

On a population-weighted basis, the average modeled 2030 24-hour PM2.5 design value is 

projected to decrease by 0.03 μg/m

3

due to this final action. Those counties that are 

projected to be above the 24-hour PM2.5 standard in 2030 will see slightly smaller 

population-weighted decreases of 0.01 μg/m

3

in their design values due to this final 

action. 
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(3) Air Toxics

(a) Current Levels

The majority of Americans continue to be exposed to ambient concentrations of 

air toxics at levels which have the potential to cause adverse health effects.467 The levels 

of air toxics to which people are exposed vary depending on where people live and work 

and the kinds of activities in which they engage, as discussed in detail in U.S. EPA’s 

most recent Mobile Source Air Toxics Rule.468 According to the National Air Toxic 

Assessment (NATA) for 2005,

469 mobile sources were responsible for 43 percent of 

outdoor toxic emissions and over 50 percent of the cancer risk and noncancer hazard. 

Benzene is the largest contributor to cancer risk of all 124 pollutants quantitatively

assessed in the 2002 NATA and mobile sources were responsible for 59 percent of 

benzene emissions in 2002. Over the years, EPA has implemented a number of mobile 

source and fuel controls resulting in VOC reductions, which also reduce benzene and 

other air toxic emissions. 

(b) Projected Levels 

Our modeling indicates that the heavy-duty standards have relatively little impact 

on national average ambient concentrations of the modeled air toxics. Additional detail 

on the air toxics results can be found in Section 8.2.3.3 of the RIA. 

(4) Nitrogen and Sulfur Deposition

(a) Current Levels

Over the past two decades, the EPA has undertaken numerous efforts to reduce 

nitrogen and sulfur deposition across the U.S. Analyses of long-term monitoring data for 

the U.S. show that deposition of both nitrogen and sulfur compounds has decreased over 

the last 17 years although many areas continue to be negatively impacted by deposition. 

Deposition of inorganic nitrogen and sulfur species routinely measured in the U.S. 

between 2005 and 2007 were as high as 9.6 kilograms of nitrogen per hectare (kg N/ha) 

averaged over three years and 20.8 kilograms of sulfur per hectare (kg S/ha) averaged 

over three years.

470 The data show that reductions were more substantial for sulfur 

compounds than for nitrogen compounds. These numbers are generated by the U.S. 

national monitoring network and they likely underestimate nitrogen deposition because 

 

467 U.S. Environmental Protection Agency (2007). Control of Hazardous Air Pollutants from Mobile 

Sources; Final Rule. 72 FR 8434, February 26, 2007.

468 U. S. Environmental Protection Agency (2007). Control of Hazardous Air Pollutants from Mobile 

Sources; Final Rule. 72 FR 8434, February 26, 2007. 

469 U. S. EPA. (2011) 2005 National-Scale Air Toxics Assessment. http://www.epa.gov/ttn/atw/nata2005/. 

Docket EPA-HQ-OAR-2010-0162. 

470 U.S. EPA. U.S. EPA's Report on the Environment (Final Report). U.S. Environmental Protection 

Agency, Washington, D.C., EPA/600/R-07/045F (NTIS PB2008-112484). Docket EPA-HQ-OAR-2010-

0162. Updated data available online at: 

http://cfpub.epa.gov/eroe/index.cfm?fuseaction=detail.viewInd&ch=46&subtop=341&lv=list.listByChapter

&r=201744 
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neither ammonia nor organic nitrogen is measured. In the eastern U.S., where data are 

most abundant, total sulfur deposition decreased by about 44% between 1990 and 2007,

while total nitrogen deposition decreased by 25% over the same time frame.471

(b) Projected Levels 

Our air quality modeling projects decreases in nitrogen deposition, especially in 

the Midwest, as a result of the heavy-duty standards required by this final action. The 

heavy-duty standards will result in annual percent decreases of 0.5% to more than 2% in 

some cities in the Midwest, Phoenix, Albuquerque, and some areas in Texas. The 

remainder of the country will see only minimal changes in nitrogen deposition, ranging 

from decreases of less than 0.5% to increases of less than 0.5%. For a map of 2030 

nitrogen deposition impacts and additional information on these impacts, see Section 

8.2.3.4 of the RIA. The impacts of the heavy-duty standards on sulfur deposition are 

minimal, ranging from decreases of up to 0.5% to increases of up to 0.5%.

(5) Visibility

(a) Current Levels

As mentioned in Section VII.D(1)(a), millions of people live in nonattainment 

areas for the PM2.5 NAAQS. These populations, as well as large numbers of individuals 

who travel to these areas, are likely to experience visibility impairment. In addition, 

while visibility trends have improved in mandatory class I federal areas, the most recent 

data show that these areas continue to suffer from visibility impairment. In summary, 

visibility impairment is experienced throughout the U.S., in multi-state regions, urban 

areas, and remote mandatory class I federal areas.

(b) Projected Levels 

Air quality modeling conducted for this final action was used to project visibility

conditions in 138 mandatory class I federal areas across the U.S. in 2030. The results 

show that all the modeled areas will continue to have annual average deciview levels 

above background in 2030.472 The results also indicate that the majority of the modeled 

mandatory class I federal areas will see very little change in their visibility, but some 

mandatory class I federal areas will see improvements in visibility due to the heavy-duty 

standards and a few mandatory class I federal areas will see visibility decreases. The 

 

471 U.S. EPA. U.S. EPA’s 2008 Report on the Environment (Final Report). U.S. Environmental Protection 

Agency, Washington, D.C., EPA/600/R-07/045F (NTIS PB2008-112484). Docket EPA-HQ-OAR-2010-

0162. Updated data available online at: 

http://cfpub.epa.gov/eroe/index.cfm?fuseaction=detail.viewInd&ch=46&subtop=341&lv=list.listByChapter

&r=201744 

472 The level of visibility impairment in an area is based on the light-extinction coefficient and a unitless 

visibility index, called a “deciview,” which is used in the valuation of visibility. The deciview metric 

provides a scale for perceived visual changes over the entire range of conditions, from clear to hazy. Under 

many scenic conditions, the average person can generally perceive a change of one deciview. The higher 

the deciview value, the worse the visibility. Thus, an improvement in visibility is a decrease in deciview 

value.
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average visibility at all modeled mandatory class I federal areas on the 20% worst days is 

projected to improve by 0.01 deciviews, or 0.06%, in 2030. Section 8.2.3.5 of the RIA 

contains more detail on the visibility portion of the air quality modeling.

VIII. What are the Agencies’ Estimated Cost, Economic, and 

Other Impacts of the Final Program?

In this section, we present the costs and impacts of the final HD National 

Program. It is important to note that NHTSA’s final fuel consumption standards and 

EPA’s final GHG emissions standards will both be in effect, and each will lead to 

average fuel efficiency increases and GHG emission reductions. The two agencies’ final 

standards comprise the HD National Program.

The net benefits of the final HD National Program consist of the effects of the 

program on: 

 the vehicle program costs (costs of complying with the vehicle CO2 standards)

 fuel savings associated with reduced fuel usage resulting from the program

 reductions in greenhouse gas emissions, 

 the reductions in other (non-GHG) pollutants, 

 costs associated with increases in noise, congestion, and accidents resulting from 

increased vehicle use, 

 improvements in U.S. energy security impacts,

 benefits associated with increased vehicle use due to the “rebound” effect. 

We also present the cost-effectiveness of the standards, or the cost per ton of 

emissions reduced. Where possible, we identify the uncertain aspects of these economic 

impacts and attempt to quantify them when and if possible (e.g., sensitivity ranges 

associated with quantified and monetized GHG impacts; probabilistic uncertainty

associated with non-GHG health benefits). For some impacts, however, there is a lack of 

adequate information to inform a probabilistic assessment of uncertainty. EPA continues 

to work toward developing a comprehensive strategy for characterizing the aggregate 

impact of uncertainty in key elements of its analyses and we will continue to work to 

refine these uncertainty analyses in the future as time and resources permit.

The program may have other effects that are not included here. The agencies 

sought comment on whether any costs or benefits were omitted from this analysis, so that 

they could be explicitly recognized in the final rules. In particular, as discussed in 

Section III and in Chapter 2 of the RIA, the technology cost estimates developed here 

take into account the costs to hold other vehicle attributes, such as size and performance, 

constant. In addition, the analysis assumes that the full technology costs are passed along 

to vehicle buyers. With these assumptions, because welfare losses are monetary

estimates of how much buyers would have to be compensated to be made as well off as in 
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the absence of the change,473 the price increase measures the loss to the buyer.474 

Assuming that the full technology cost gets passed along to the buyer as an increase in 

price, the technology cost thus measures the welfare loss to the buyer. Increasing fuel 

efficiency would have to lead to other changes in the vehicles that buyers find 

undesirable for there to be additional losses not included in the technology costs. 

The agencies sought comments, including supporting data and quantitative 

analyses, of any additional impacts of the final standards on vehicle attributes and 

performance, and other potential aspects that could positively or negatively affect the 

welfare implications of this final rulemaking, not addressed in this analysis. 

The comments received by the agencies did not provide any clear insights into 

this question. Some comments noted the diversity of the trucking industry and expressed 

a request that the program continue the great variety of options for the industry, because 

of the variation in needs for different customers. Additional comments noted that the 

separate engine and vehicle programs support the maintenance of variety and current 

market structure. Though a few commenters raised concerns, no information was offered 

to indicate that choice will in fact be limited by the program, or that other vehicle 

attributes are adversely affected.

The total monetized benefits (excluding fuel savings) under the program are 

projected to be $4.3 to $11.1 billion in 2030, depending on the value used for the social 

cost of carbon. These benefits are summarized below in Table VIII-31. The costs of the 

program in 2030, presented in Table VIII-29 are estimated to be approximately $2.2

billion for new engine and truck technology. The program is also estimated to provide

$20.6 billion in savings realized by trucking operations through fewer fuel expenditures 

(calculated using pre-tax fuel prices), as shown in Table VIII-30. The present value of 

the total monetized benefits (excluding fuel savings) under the program is expected to 

range from $48.7 billion to $180.1 billion with a 3% discount rate; with a 7% discount 

rate, the total monetized benefits are expected to range from $24.3 billion to $155.7 

billion. These values, summarized in Table VIII-31, depend on the value used for the 

social cost of carbon. The present value of costs of the program for new engine and truck 

technology, in Table VIII-29, are expected to be $47.4 billion using a 3% discount rate, 

and $24.7 billion with a 7% discount rate. The present value of fuel savings (calculated 

using pre-tax fuel prices) is estimated at $375.3 billion with a 3% discount rate, and 

$166.5 billion with a 7% discount rate, as shown in Table VIII-30. Total net present 

 

473 This approach describes the economic concept of compensating variation, a payment of money after a 

change that would make a consumer as well off after the change as before it. A related concept, equivalent 

variation, estimates the income change that would be an alternative to the change taking place. The 

difference between them is whether the consumer’s point of reference is her welfare before the change 

(compensating variation) or after the change (equivalent variation). In practice, these two measures are 

typically very close together. 

474 Indeed, it is likely to be an overestimate of the loss to the buyer, because the buyer has choices other 

than buying the same vehicle with a higher price; she could choose a different vehicle, or decide not to buy 

a new vehicle. The buyer would choose one of those options only if the alternative involves less loss than 

paying the higher price. Thus, the increase in price that the buyer faces would be the upper bound of loss 

of consumer welfare, unless there are other changes to the vehicle due to the fuel economy improvements 

that make the vehicle less desirable to buyers.
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benefits (in Table VIII-32) are thus expected to range from $376.6 billion to $508 billion 

with a 3% discount rate, and $166.1 billion to $297.5 billion with a 7% discount rate.

The estimates developed here are measured against a baseline fuel efficiency

associated with MY 2010 vehicles. The agencies also considered an alternate baseline 

associated with AEO 2011 projections, which is further discussed in Section IX. All 

calculations presented in Section VIII use the constant 2010 vehicle baseline. The extent 

to which fuel efficiency improvements may have occurred in the absence of the rules 

affects the net benefits associated with the program. If trucks were to install technologies 

to achieve the fuel savings and reduced GHG emissions in the absence of this program, 

then both the costs and benefits of these fuel savings could be attributed to market forces, 

not the rules. As a baseline for estimates of the extent of fuel-saving technologies that 

might have been adopted in the absence of the program, the proposal used the level of 

these technologies in MY 2010 vehicles. We sought comment on whether the agencies 

should use an alternative baseline based on data provided by commenters to estimate the 

degree to which the technologies discussed in the proposal would have been adopted in 

the absence of these rules. No comments were received on this issue. One comment cites 

the EPA draft RIA as noting a historic 1% per year improvement in fuel efficiency, and 

argues that the rules are therefore not needed; the actual figure in the draft RIA, however, 

was a 0.09% per year improvement.

EPA has undertaken an analysis of the economy-wide impacts of the final heavyduty truck fuel efficiency and GHG standards as an exploratory exercise that EPA 

believes could provide additional insights into the potential impacts of the program.475 

These results were not a factor regarding the appropriateness of the final standards. It is 

important to note that the results of this modeling exercise are dependent on the 

assumptions associated with how manufacturers would make fuel efficiency 

improvements and how trucking operations would respond to increases in higher vehicle 

costs and improved vehicle fuel efficiency as a result of the final program. 

Further information on these and other aspects of the economic impacts of our 

rules are summarized in the following sections and are presented in more detail in the 

RIA for this final rulemaking.

A. Conceptual Framework for Evaluating Impacts

This regulation is motivated primarily by the goals of reducing emissions of 

greenhouse gases and promoting U.S. energy security by reducing consumption and 

imports of petroleum-based fuels. These motivations involve classic externalities, 

meaning that private decisions do not incorporate all of the costs associated with these 

problems; these costs are not borne completely by the households or businesses whose 

actions are responsible for them. In the absence of some mechanism to “internalize” 

these costs – that is, to transfer their burden to individuals or firms whose decisions 

impose them – individuals and firms will consume more petroleum-based fuels than is 

 

475 See Memorandum to Docket, “Economy-Wide Impacts of Heavy-Duty Truck Greenhouse Gas 

Emissions and Fuel Efficiency Standards”, May 20, 2011. Docket EPA-HQ-OAR-2010-0162.
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socially optimal. Externalities are a classic motivation for government intervention in 

markets. These externalities, as well as effects due to changes in emissions of other 

pollutants and other impacts, are discussed in Sections VIII.H – VIII.K.

In some cases, these classic externalities are by themselves enough to justify the 

costs of imposing fuel efficiency standards. For some discount rates and some projected

social costs of carbon, however, the reductions in these external costs are less than the 

costs of new fuel saving technologies needed to meet the standards. (See Tables 9-18 and 

9-19 in the RIA.) Nevertheless, this regulation reduces trucking companies’ fuel costs; 

according to our estimates, these savings in fuel costs are by themselves sufficient to pay

for the technologies over periods of time considerably shorter than vehicles’ expected 

lifetimes under the assumptions used for this analysis (e.g., AEO 2011 projected fuel 

prices). If these estimates are correct, then the entire value of the reductions in external 

costs represents additional net benefits of the program, beyond those resulting from the 

fact that the value of fuel savings exceeds the costs of technologies necessary to achieve 

them.

It is often asserted that there are cost-effective fuel-saving technologies that 

markets do not take advantage of. This is commonly known as the “energy gap” or 

“energy paradox.” Standard economic theory suggests that in normally functioning 

competitive markets, interactions between vehicle buyers and producers would lead 

producers to incorporate all cost-effective technology into the vehicles that they offer, 

without government intervention. Unlike in the light-duty vehicle market, the vast 

majority of vehicles in the medium- and heavy-duty truck market are purchased and 

operated by businesses with narrow profit margins, and for which fuel costs represent a 

substantial operating expense. 

Even in the presence of uncertainty and imperfect information – conditions that 

hold to some degree in every market – we generally expect firms to attempt to minimize 

their costs in an effort to survive in a competitive marketplace, and therefore to make 

decisions that are in the best interest of the company and its owners and/or shareholders. 

In this case, the benefits of the rules would be due exclusively to reducing the economic 

costs of externalities resulting from fuel production and consumption. However, as 

discussed below in Section VIII.E, the agencies have estimated that the application of 

fuel-saving technologies in response to the final standards would, on average, yield 

private returns to truck owners of 140 percent to 420 percent (see Table VIII-21 below). 

The agencies have also estimated that the application of these technologies would be 

significantly lower in the absence of the final standards (i.e., under the “no action” 

regulatory alternative), meaning that truck buyers and operators ignore opportunities to 

make investments in higher fuel efficiency that appear to offer significant cost savings.

As discussed in the NPRM, there are several possible explanations in the 

economics literature for why trucking companies do not adopt technologies that would be 

expected to increase their profits: there could be a classic market failure in the trucking 

industry – market power, externalities, or asymmetric or incomplete (i.e., missing market)

information; there could be institutional or behavioral rigidities in the industry (union 

rules, standard operating procedures, statutory requirements, loss aversion, etc.), whereby 
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participants collectively do not minimize costs; or the engineering estimates of fuel 

savings and costs for these technologies might overstate their benefits or understate their 

costs in real-world applications. See 75 FR at 74303-307.

To try to understand why trucking companies have not adopted these seemingly 

cost-effective fuel-saving technologies, the agencies surveyed published literature about 

the energy paradox, and held discussions with numerous truck market participants. The 

proposal discussed five categories of possible explanations derived from these sources. 

Collectively, these five hypotheses may explain the apparent inconsistency between the 

engineering analysis, which finds a number of cost-effective methods of improving fuel 

efficiency, and the observation that many of these technologies are not widely adopted. 

These hypotheses include imperfect information in the original and resale 

markets, split incentives, uncertainty about future fuel prices, and adjustment and 

transactions costs. As the discussion indicated, some of these explanations suggest 

failures in the private market for fuel-saving technology in addition to the externalities 

caused by producing and consuming fuel that are the primary motivation for the rules. 

Other explanations suggest market-based behaviors that may imply additional costs of 

regulating truck fuel efficiency that are not accounted for in this analysis. As noted 

above, an additional explanation – adverse effects on other vehicle attributes -- did not 

elicit supporting information in the public comments. Anecdotal evidence from various 

segments of the trucking industry suggests that many of the hypotheses discussed here 

may play a role in explaining the puzzle of why truck purchasers appear to under-invest 

in fuel efficiency, although different explanations may apply to different segments, or 

even different companies. The published literature does not appear to include empirical 

analysis or data related to this question.

The agencies invited comment on these explanations, and on any data or 

information that could be used to investigate the role of any or all of these five 

hypotheses in explaining this energy paradox as it applies specifically to trucks. Some 

comments expressed dissatisfaction about the explanations presented; they argued that 

these arguments were not sufficient to explain the phenomenon. These comments argued 

that the truck owners and operators are better judges of the appropriate amount of fuel 

efficiency than are government agencies; they choose not to invest because of warranted 

skepticism about these technologies. The agencies also requested comment and 

information regarding any other hypotheses that could explain the appearance that costeffective fuel-saving technologies have not been widely incorporated into trucks. The 

following discussion summarizes the fuller discussion provided in the NPRM and 

includes discussion of the comments received.

(1) Information Issues in the Original Sale Markets

One potential hypothesis for why the trucking industry does not adopt what 

appear to be inexpensive fuel saving technologies is that there is inadequate or unreliable 

information available about the effectiveness of many fuel-saving technologies for new 

vehicles. If reliable information on the effectiveness of many new technologies is absent, 
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truck buyers will understandably be reluctant to spend additional money to purchase 

vehicles equipped with unproven technologies. 

This lack of information can manifest itself in multiple ways. For instance, the 

problem may arise purely because collecting reliable information on technologies is 

costly (also see Section VIII.A.5 below on transaction costs). Moreover, information has 

aspects of a public good, in that no single firm has the incentive to do the costly

experimentation to determine whether or not particular technologies are cost-effective, 

while all firms benefit from the knowledge that would be gained from that 

experimentation. Similarly, if multiple firms must conduct the same tests to get the same 

information, costs could be reduced by some form of coordination of information 

gathering.

While its effect on information is indirect, we expect the requirement for the use 

of new technologies included in this program will circumvent these information issues, 

resulting in their adoption, thus providing more readily available information about their 

benefits. The agencies appreciate, however, that the diversity of truck uses, driving 

situations, and driver behavior will lead to variation in the fuel savings that individual 

trucks or fleets experience from using specific technologies. 

One commenter noted that the SmartWay program targets combination tractor

owners and thus should have the largest impact on that sector, rather than vocational or 

medium-duty trucks. However, the gap between actual investment in fuel efficiency and 

the agencies’ estimates of optimal investment is largest for combination tractors. Some 

of the difference in magnitude is likely to be due to the higher vehicle miles traveled for 

combination tractors compared to medium-duty and vocational vehicles: more driving 

means more fuel savings. Additionally, not even a majority of semi-trucks are owned by

participants in SmartWay; non-participants are unlikely to get all the benefits of 

participants. Other explanations, noted below, are also likely to play a role. This 

observation may also suggest some limitations of improved information provision as a 

means of addressing the “efficiency gap.”

(2) Information Issues in the Resale Market

In addition to issues in the new vehicle market, a second hypothesis for why 

trucking companies may not adopt what appear to be cost-effective technologies to save 

fuel is that the resale market may not adequately reward the addition of fuel-saving 

technology to vehicles to ensure their original purchase by new truck buyers. This 

inadequate payback for users beyond the original owner may contribute to the short 

payback period that new purchasers appear to expect.476 The agencies requested data and 

information on the extent to which costs of fuel saving equipment can be recovered in the 

resale truck market. No data were received. One reviewer disputed this theory on the 

 

476 See NAS 2010, Note 197, at p. 188.
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basis that people are willing to pay more for better vehicles, new or used. It is not clear, 

however, whether buyers of used vehicles can tell which are the better vehicles.477

Some of this unwillingness to pay for fuel-saving technology may be due to the 

extension of the information problems in the new vehicle market into resale markets. 

Buyers in the resale market have no more reason to trust information on fuel-saving 

technologies than buyers in the original market. Because actual fuel efficiency of trucks 

on the road depends on many factors, including geography and driving styles or habits, 

even objective sources such as logs of truck performance for used vehicles may not 

provide reliable information about the fuel efficiency that potential purchasers of used 

trucks will experience.

A related possibility is that vehicles will be used for different purposes by their 

second owners than those for which they were originally designed, and the fuel-saving 

technology is therefore of less value. 

It is possible, though, that the fuel savings experienced by the secondary

purchasers may not match those experienced by their original owners if the optimal 

secondary new use of the vehicle does not earn as many benefits from the technologies. 

One commenter asks whether the fuel-saving technology is unvalued because it is 

unproven or overrated. In that case, the premium for fuel-saving technology in the 

secondary market should accurately reflect its value to potential buyers participating in 

that market, even if it is lower than its value in the original market, and the market has 

not failed. Because the information necessary to optimize use in the secondary market 

may not be readily available or reliable, however, buyers in the resale market may have 

less ability than purchasers of new vehicles to identify and gain the advantages of new 

fuel-saving technologies, and may thus be even less likely to pay a premium for them.

For these reasons, purchasers’ willingness to pay for fuel efficiency technologies 

may be even lower in the resale market than in the original equipment market. Even 

when fuel-saving technologies will provide benefits in the resale markets, purchasers of 

used vehicles may not be willing to compensate their original owners fully for their 

remaining value. As a result, the purchasers of original equipment may expect the resale 

market to provide inadequate appropriate compensation for the new technologies, even 

when those technologies would reduce costs for the new buyers. This information issue 

may partially explain what appears to be the very short payback periods required for new 

technologies in the new vehicle market.

(3) Split Incentives in the Medium- and Heavy-Duty Truck Industry

A third hypothesis explaining the energy paradox as applied to trucking involves 

split incentives. When markets work effectively, signals provided by transactions in one 

market are quickly transmitted to related markets and influence the decisions of buyers 

 

477 Akerlof, George A. “The Market for ‘Lemons’” Quality Uncertainty and the Market Mechanism,” 

Quarterly Journal of Economics 84(3) (1970): 488-500 points out that asymmetric information – the seller 

has better information than the buyer – can potentially lead to complete failure of a market, even when both 

buyers and sellers would benefit from trade.
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and sellers in those related markets. For instance, in a well-functioning market system, 

changes in the expected future price of fuel should be transmitted rapidly to those who 

purchase trucks, who will then reevaluate the amount of fuel-saving technology to 

purchase for new vehicles. If for some reason a truck purchaser will not be directly

responsible for future fuel costs, or the individual who will be responsible for fuel costs 

does not decide which truck characteristics to purchase, then those price signals may not 

be transmitted effectively, and incentives can be described as “split.” 

One place where such a split may occur is between the owners and operators of 

trucks. Because they are generally responsible for purchasing fuel, truck operators have 

strong incentives to economize on its use, and are thus likely to support the use of fuelsaving technology. However, the owners of trucks or trailers are often different from 

operators, and may be more concerned about their longevity or maintenance costs than 

about their fuel efficiency, when purchasing vehicles. As a result, capital investments by

truck owners may be channeled into equipment that improves vehicles’ durability or 

reduces their maintenance costs, rather than into fuel-saving technology. If operators can 

choose freely among the trucks they drive, competition among truck owners to employ

operators would encourage owners to invest in fuel-saving technology. However, if truck 

owners have more ability to choose among operators, then market signals for improved 

fuel savings that would normally be transmitted to truck owners may be muted. Truck 

fleets that rent their vehicles may provide an example: renters may observe the cost of 

renting the truck, but not its fuel efficiency; if so, then the purchasers will aim for 

vehicles with lower costs, to lower the cost of the rental. It might be possible to test this 

theory by comparing the fuel efficiency of trucks by owner-operators with those that are 

leased by operators. The agencies have not had the data to conduct such a test.

One commenter noted that there are always tradeoffs in an investment decision: a 

purchaser may prefer to invest in other vehicle attributes than fuel efficiency. In an 

efficient market, however, a purchaser should invest in fuel-saving technology as long as 

the increase in fuel-saving technology costs less than the expected fuel savings. This 

result should hold regardless of the level of investment in other attributes, unless there are 

constraints on a purchaser’s access to investment capital. The agencies believe that truck 

fleets do have an incentive to make investments in fuel efficiency, and that this 

assumption is reflected in the regulatory analysis. The agencies also believe, however, 

that sufficient evidence suggests that truck fleets are not availing themselves of all the 

opportunities for efficiency improvements. 

In addition, the NAS report notes that split incentives can arise between tractor 

and trailer operators.478 Trailers affect the fuel efficiency of shipping, but trailer owners 

do not face strong incentives to coordinate with truck owners. EPA and NHTSA are not 

regulating trailers in this action.

By itself, information provision may be inadequate to address the potential 

underinvestment in fuel efficiency resulting from such split incentives. In this setting, 

regulation may contribute to fuel savings that otherwise may be difficult to achieve.

 

478 See NAS 2010, Note 197, at p. 182.
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(4) Uncertainty About Future Cost Savings

Another hypothesis for the lack of adoption of seemingly fuel saving technologies 

may be uncertainty about future fuel prices or truck maintenance costs. When purchasers 

have less than perfect foresight about future operating expenses, they may implicitly

discount future savings in those costs due to uncertainty about potential returns from 

investments that reduce future costs. In contrast, the immediate costs of the fuel-saving 

or maintenance-reducing technologies are certain and immediate, and thus not subject to 

discounting. In this situation, both the expected return on capital investments in higher 

fuel efficiency and potential variance about its expected rate may play a role in a firm’s 

calculation of its payback period on such investments.

In the context of energy efficiency investments for the home, Metcalf and 

Rosenthal (1995) and Metcalf and Hassett (1995) observe that households weigh known, 

up-front costs that are essentially irreversible against an unknown stream of future fuel 

savings.479 Notably, in this situation, requiring households to adopt technologies more 

quickly may make them worse off by imposing additional risk on them.

Greene et al (2009) also finds support for this explanation in the context of lightduty fuel economy decisions: a loss-averse consumer’s expected net present value of 

increasing the fuel economy of a passenger car can be very close to zero, even if a riskneutral expected value calculation shows that its buyer can expect significant net benefits 

from purchasing a more fuel-efficient car.

480 Supporting this hypothesis is a finding by

Dasgupta et. al (2007) that consumers are more likely to lease than buy a vehicle with 

higher maintenance costs because it provides them with the option to return it before 

those costs become too high.481 However, the agencies know of no studies that have 

estimated the impact of uncertainty on perceived future savings for medium- and heavyduty vehicles.

Purchasers’ uncertainty about future fuel prices implies that mandating 

improvements in fuel efficiency can reduce the expected utility associated with truck 

purchases. This is because adopting such regulation requires purchasers to assume a 

greater level of risk than they would in its absence, even if the future fuel savings 

predicted by a risk-neutral calculation actually materialize. One commenter expressed 

support for this argument. Thus the mere existence of uncertainty about future savings in 

fuel costs does not by itself assure that regulations requiring improved fuel efficiency will 

necessarily provide economic benefits for truck purchasers and operators. On the other 

hand, because risk aversion reduces expected returns for businesses, competitive 

 

479 Metcalf, G., and D. Rosenthal (1995). “The ‘New’ View of Investment Decisions and Public Policy 

Analysis: An Application to Green Lights and Cold Refrigerators,” Journal of Policy Analysis and 

Management 14: 517–531. Hassett and Metcalf (1995). “Energy Tax Credits and Residential Conservation 

Investment: Evidence from Panel Data” Journal of Public Economics 57 (1995): 201-217. Metcalf, G., and 

K. Hassett (1999). “Measuring the Energy Savings from Home Improvement Investments: Evidence from 

Monthly Billing Data.” The Review of Economics and Statistics 81(3): 516-528.

480 Greene, D., J. German, and M. Delucchi (2009). “Fuel Economy: The Case for Market Failure” in 

Reducing Climate Impacts in the Transportation Sector, Sperling, D., and J. Cannon, eds. Springer Science.

481 Dasgupta, S., S. Siddarth, and J. Silva-Risso (2007). “To Lease or to Buy? A Structural Model of a 

Consumer’s Vehicle and Contract Choice Decisions.” Journal of Marketing Research 44: 490 – 502.
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pressures can reduce risk aversion: risk-neutral companies can make higher average 

profits over time. Thus, significant risk aversion is unlikely to survive competitive 

pressures.

(5) Adjustment and Transactions Costs

Another hypothesis is that transactions costs of changing to new technologies 

(how easily drivers will adapt to the changes, e.g.) may slow or prevent their adoption. 

Because of the diversity in the trucking industry, truck owners and fleets may like to see 

how a new technology works in the field, when applied to their specific operations, 

before they adopt it. One commenter expressed support for this argument. If a 

conservative approach to new technologies leads truck buyers to adopt new technologies 

slowly, then successful new technologies are likely to be adopted over time without 

market intervention, but with potentially significant delays in achieving fuel saving, 

environment, and energy security benefits.

In addition, there may be costs associated with training drivers to realize the 

potential fuel savings enabled by new technologies, or with accelerating fleet operators’ 

scheduled fleet turnover and replacement to hasten their acquisition of vehicles equipped 

with new fuel-saving technologies. Here, again, there may be no market failure; 

requiring the widespread use of these technologies may impose adjustment and 

transactions costs not included in this analysis. As in the discussion of the role of risk, 

these adjustment and transactions costs are typically immediate and undiscounted, while 

their benefits are future and uncertain; risk or loss aversion may further discourage 

companies from adopting new technologies.

To the extent that there may be transactions costs associated with the new 

technologies, then regulation gives all new truck purchasers a level playing field, because 

it will require all of them to adjust on approximately the same time schedule. If 

experience with the new technologies serves to reduce uncertainty and risk, the industry

as a whole may become more accepting of new technologies. This could increase 

demand for future new technologies and induce additional benefits in the legacy fleet 

through complementary efforts such as SmartWay.

(6) Additional Hypotheses

In the public comments, two additional ideas were raised for the lack of adoption of what 

appears to be cost-effective fuel-saving technology. The first suggestion is that tighter 

diesel emissions standards caused engine manufacturers to invest heavily (both 

financially and with personnel) in emissions reduction technologies, and hence, were 

unable to invest in fuel efficiency technologies. A second suggestion is that a truck may

be a “positional good” – that is, a good whose value depends on how it compares to the 

goods owned by others. If trucks confer status on their owners or operators, and if that 

status depends on easily observable characteristics, then owners may invest 

disproportionately in status-granting characteristics rather than less visible characteristics, 

such as fuel efficiency. Because status depends on comparisons to others, an “arms race” 

may develop in which all parties spend additional money on visible characteristics but 
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may not manage to make themselves better off. In this case, regulation may improve 

welfare: by increasing the requirements for non-positional fuel efficiency, regulation 

could reduce expenditures made purely for competition rather than actual increase in 

welfare. In a competitive business, cost reduction provides a major opportunity cost to 

investing in status rather than in fuel-saving technology; thus, this argument may play

less of a role in the heavy-duty market than in the consumer market for vehicles.

Both these hypotheses leave open the question, though, why additional 

investments were not made in fuel efficiency if they would provide rapid payback. Truck 

purchasers should, in principle, be willing to buy additional fuel-saving technology as 

long as it is cost-effective, regardless of other vehicle attributes. Limited access to 

capital, if it is a problem in this sector, might provide some reason for the “crowding out” 

of the purchase of fuel-saving technology. The agencies received no evidence indicating 

that constrained access to capital might explain the efficiency gap in this market.

(7) Summary

On the one hand, commercial vehicle operators are under competitive pressure to 

reduce operating costs, and thus their purchasers would be expected to pursue and rapidly 

adopt cost-effective fuel-saving technologies. On the other hand, the short payback 

period required by buyers of new trucks is a symptom that suggests some combination of 

uncertainty about future cost savings, transactions costs, and imperfectly functioning 

markets. In addition, widespread use of tractor-trailer combinations introduces the 

possibility that owners of trailers may have weaker incentives than truck owners or 

operators to adopt fuel-saving technology for their trailers. The market for medium- and 

heavy-duty trucks may face these problems, both in the new vehicle market and in the 

resale market.

Provision of information about fuel-saving technologies through voluntary

programs such as SmartWay will assist in the adoption of new cost-saving technologies, 

but diffusion of new technologies can still be obstructed. Those who are willing to 

experiment with new technologies expect to find cost savings, but those may be difficult 

to prove. As noted above, because individual results of new technologies vary, new truck 

purchasers may find it difficult to identify or verify the effects of fuel-saving 

technologies. Those who are risk-averse are likely to avoid new technologies out of 

concerns over the possibility of inadequate returns on the investment, or with other 

adverse impacts. Competitive pressures in the freight transport industry can provide a 

strong incentive to reduce fuel consumption and improve environmental performance. 

However, not every driver or trucking fleet operating today has the requisite ability or 

interest to access the technical information, some of which is already provided by 

SmartWay, nor the resources necessary to evaluate this information within the context of 

his or her own freight operation.

It is unclear, as discussed above, whether some or many of the technologies 

would be adopted in the absence of the program. To the extent that they would have been 

adopted, the costs and the benefits attributed to those technologies may not in fact be due 

to the program and may therefore be overstated. Both baselines used project substantially
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less adoption than the agencies consider to be cost-effective. The agencies will continue 

to explore reasons for this slow adoption of cost-effective technologies.

B. Costs Associated With the Final Program

In this section, the agencies present the estimated costs associated with the final 

program. The presentation here summarizes the costs associated with new technology

expected to be added to meet the new GHG and fuel consumption standards. The 

analysis summarized here provides the estimate of incremental costs on a per truck basis 

and on an annual total basis. 

The presentation here summarizes the best estimate by EPA and NHTSA staff as 

to the technology mix expected to be employed for compliance. For details behind the 

cost estimates associated with individual technologies, the reader is directed to Section III 

of this preamble and to Chapter 2 of the RIA. 

With respect to the cost estimates presented here, the agencies note that, because 

these estimates relate to technologies which are in most cases already available, these 

cost estimates are technically robust. 

(1) Costs per Truck

For the heavy-duty pickup trucks and vans, the agencies have used a methodology

consistent with that used for our recent light-duty joint rulemaking since most of the 

technologies expected for heavy-duty pickup trucks and vans is consistent with that 

expected for the larger light-duty trucks. The cost estimates presented in the recent lightduty joint rulemaking were then scaled upward to account for the larger weight, towing 

capacity, and work demands of the trucks in these heavier classes. For details on that 

scaling process and the resultant costs for individual technologies, the reader is directed 

to Section III of this preamble and to Chapter 2 of the RIA. Note also that all cost 

estimates have been updated to 2009 dollars for this analysis while the heavy-duty GHG 

emissions and fuel efficiency proposal was presented in 2008 dollars and the light-duty 

rule was presented in 2007 dollars. 

For the loose heavy-duty gasoline engines, we have generally used engine-related 

costs from the heavy-duty pickup truck and van estimates since the loose heavy-duty 

gasoline engines are essentially the same engines as those sold into the heavy-duty

pickup truck and van market. 

For heavy-duty diesel engines, the agencies have estimated costs using a different 

methodology than that employed in the recent light-duty joint rulemaking. In the lightduty 2012-2016 MY vehicle rule, the fixed costs were included in the hardware costs via 

an indirect cost multiplier. As such, the hardware costs presented in that analysis, and in 

the cost estimates for Class 2b and 3 trucks, included both the actual hardware and the 

associated fixed costs. For this analysis, some of the fixed costs are estimated separately 

for HD diesel engines and are presented separately from the hardware costs. For details, 

the reader is directed to Chapter 2 of the RIA. Importantly, both methodologies after the 
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figures are totaled account for all the costs associated with the program. As noted above, 

all costs are presented in 2009 dollars.

The estimates of vehicle compliance costs cover the years leading up to – 2012 

and 2013 – and including implementation of the program – 2014 through 2018. Also 

presented are costs for the years following implementation to shed light on the long term 

(2022 and later) cost impacts of the program. The year 2022 was chosen here consistent 

with the light-duty 2012-2016 MY vehicle rule. That year was considered long term in 

that analysis because the short-term and long-term markup factors described shortly

below are applied in five year increments with the 2012 through 2016 implementation 

span and the 2017 through 2021 span both representing the short-term. Since many of 

the costs used in this analysis are based on costs in the light-duty rule analysis, 

consistency with that analysis seems appropriate. 

Some of the individual technology cost estimates are presented in brief in Section 

III, and account for both the direct and indirect costs incurred in the manufacturing and 

dealer industries (for a complete presentation of technology costs, please refer to Chapter 

2 of the RIA). To account for the indirect costs on Class 2b and 3 pickup trucks and 

vans, the agencies have applied an ICM factor to all of the direct costs to arrive at the 

estimated technology cost. The ICM factor used was 1.24 in the short-term (2014 

through 2021) to account for differences in the levels of R&D, tooling, and other indirect 

costs that will be incurred. Once the program has been fully implemented, some of the 

indirect costs will no longer be attributable to these standards and, as such, a lower ICM 

factor is applied to direct costs in 2022 and later. The agencies have also applied ICM 

factors to Class 4 through 8 trucks and to heavy-duty diesel engine technologies. Markup 

factors in these categories range from 1.15 to 1.30 in the short term (2014 through 2021) 

depending on the complexity of the given technology. We have modified the manner in 

which ICMs are applied in that they are no longer applied as a simple multiplicative 

factor on top of the direct manufacturing costs. Instead, we have broken out the warranty

cost portion of the ICM and apply it in a multiplicative manner then add the non-warranty 

cost portion of the ICM to that. The latter portion, that for non-warranty costs, is 

determined for a given year and held constant rather than decreasing year-over-year. 

This new approach, which responds to criticisms from some that the multiplicative 

approach used in the past essentially double counts learning effects, is discussed in 

Section VIII.C and is detailed in Chapter 2 of the RIA. Note that, for the HD diesel 

engines, the agencies have applied the ICMs to ensure that our estimates are conservative 

since we have estimated fixed costs separately for technologies applied to these 

categories -- effectively making the use of markups a double counting of indirect costs. 

For the details on the background and the concept behind our use of ICMs to calculate 

indirect costs, please refer to the report that has been placed in the docket for this final 

action.482

The agencies have also considered the impacts of manufacturer learning on the 

technology cost estimates by reflecting the phenomenon of volume-based learning curve 

cost reductions in our modeling using two algorithms depending on where in the learning 

 

482 RTI International. Heavy-duty Truck Retail Price Equivalent and Indirect Cost Multipliers. July 2010.
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cycle (i.e., on what portion of the learning curve) we consider a technology to be –

“steep” portion of the curve for newer technologies and “flat” portion of the curve for 

mature technologies. The observed phenomenon in the economic literature which 

supports manufacturer learning cost reductions are based on reductions in costs as 

production volumes increase, and the economic literature suggests these cost reductions 

occur indefinitely, though the absolute magnitude of the cost reductions decrease as 

production volumes increase (with the highest absolute cost reduction occurring with the 

first doubling of production). The agencies use the terminology “steep” and “flat” 

portion of the curve to distinguish among newer technologies and more mature 

technologies, respectively, and how learning cost reductions are applied in cost analyses. 

The steep learning algorithm applies for the early, steep portion of the learning curve and 

is estimated to result in 20 percent lower costs after two full years of implementation (i.e., 

a 2016 MY cost would be 20 percent lower than the 2014 and 2015 model year costs for 

a new technology being implemented in 2014). The flat learning algorithm applies for 

the flatter portion of the learning curve and is estimated to result in 3 percent lower costs 

in each of the five years following first introduction of a mature technology added in 

response to this final action. Once two steep learning steps have occurred (for 

technologies having steep learning applied), flat learning would begin. For technologies 

to which flat learning is applied, learning would begin in year 2 at 3 percent per year for 

5 years. Beyond 5 years of flat learning at 3 percent per year, 5 years of flat learning at 2 

percent per year, then 5 at 1 percent per year become effective. 

Learning impacts have been considered on most but not all of the technologies 

expected to be used because some of the expected technologies are already used rather 

widely in the industry and, presumably, learning impacts have already occurred. The 

agencies have applied the steep learning algorithm for only a handful of technologies 

considered to be new or emerging technologies such as energy recovery systems and 

thermal storage units which might one day be used on big trucks. For most technologies, 

the agencies have considered them to be more established and, hence, the agencies have 

applied the lower flat learning algorithm. For more discussion of the learning approach 

and the technologies to which each type of learning has been applied the reader is 

directed to Chapter 2 of the RIA.

The technology cost estimates discussed in Section III and detailed in Chapter 2 

of the RIA are used to build up technology package cost estimates. For each engine and 

truck class, a single package for each was developed capable of complying with the final 

standards and the costs for each package was generated. The technology packages and 

package costs are discussed in more detail in Chapter 2 of the RIA. The compliance cost 

estimates take into account all credits and trading programs and include costs associated 

with air conditioning controls. Table VIII-1 presents the average incremental costs per 

truck for this final action. For HD pickup trucks and vans (Class 2b and 3), costs 

increase as the standards become more stringent in 2014 through 2018. Following 2018, 

costs then decrease going forward as learning effects result in decreased costs for 

individual technologies. By 2022, the long term ICMs take effect and costs decrease yet 

again. For vocational vehicles, cost trends are more difficult to discern as diesel engines 

begin adding technology in 2014, gasoline engines begin adding technology in 2016, and 

the trucks themselves begin adding technology in 2014. With learning effects the costs, 
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in general, decrease each year except for the heavy-duty gasoline engine changes in 2016. 

Long term ICMs take effect in 2022 to provide more cost reductions. For combination 

tractors, costs generally decrease each year due to learning effects with the exception of 

2017 when the engines placed in sleeper cab tractors add turbo compounding. Following 

that, learning impacts result in cost reductions and the long term ICMs take effect in 2022 

for further cost reductions. By 2030 and later, cost–per-truck estimates remain constant 

for all classes. Regarding the long term ICMs taking effect in 2022, the agencies 

consider this the point at which some indirect costs decrease or are no longer considered 

attributable to the program (e.g., warranty costs go down). Costs per truck remain 

essentially constant thereafter. 

Table VIII-1: Estimated Cost per Truck (2009 dollars)

HD Pickups & Vans Vocational Combination

2014 $165 $329 $6,019

2015 $215 $320 $5,871

2016 $422 $397 $5,677

2017 $631 $387 $6,413

2018 $1,048 $378 $6,215

2020 $985 $366 $6,004

2030 $977 $311 $5,075

2040 $977 $305 $5,075

2050 $977 $304 $5,075

These costs would, presumably, have some impact on new truck prices, although 

the agencies make no attempt at determining what the impact of increased costs would be 

on new truck prices. Nonetheless, on a percentage basis, the costs shown in Table VIII-1

for 2018 MY trucks (when all final requirements are fully implemented) would be 

roughly three percent for a typical HD pickup truck or van, less than one percent for a

typical vocational vehicle, and roughly six percent for a typical combination truck/tractor 

using new truck prices of $40,000, $100,000 and $100,000, respectively. The costs 

would represent lower or higher percentages of new truck prices for new trucks with 

higher or lower prices, respectively. Given the wide range of new truck prices in these 

categories—a Class 4 vocational work truck might be $40,000 when new while a Class 8 

refuse truck (i.e., a large vocational vehicle) might be as much as $200,000 when new—it 

is very difficult to reflect incremental costs as percentages of new truck prices for all 

trucks. What is presented here is the average cost (Table VIII-1) compared with typical 

new truck prices.

As noted above, the fixed costs were estimated separately from the hardware 

costs for HD diesel engines that are placed in vocational vehicles and combination 

tractors. Those fixed costs are not included in Table VIII-1. The agencies have 

estimated the R&D costs at $6.8 million per manufacturer per year for five years and the 

new test cell costs (to accommodate measurement of N2O emissions) at $63,087 per 

manufacturer. The test cell costs of N2O emissions measurement has been adjusted for 

the final rulemaking to reflect comments which stated approximately 75 percent of 

manufacturers would be required to update existing equipment while the other 25 percent 
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would require new equipment. These costs apply individually for LHD, MHD and HHD 

engines. Given the 14 manufacturers impacted by the final standards, 11 of which are 

estimated to sell both MHD and HHD engines and 3 of which are estimated to sell LHD 

engines, we have estimated a five year annual R&D cost of $170.3 million dollars (2 x 11 

x $6.8 million plus 3 x $7.75 million for each year 2012-2016) and a one-time test cell 

cost of $1.6 million dollars (2 x 11 x $63,087 plus 3 x $63,087 in 2013). Estimating 

annual sales of HD diesel engines at roughly 600,000 units results in roughly $284 per 

engine per year for five years beginning in 2012 and ending in 2016. Again, these costs 

are not reflected in Table VIII-1, but are included in Table VIII-2 as “Other Engineering 

Costs.” 

The certification and compliance program costs, for all engine and truck types, are 

estimated at $6.5 million in the first year dropping to $2.3 million in each year thereafter 

and continuing indefinitely. These costs are detailed in the “Draft Supporting Statement 

for Information Collection Request” which is contained in the docket for this final 

action.483 The costs are higher in the first year due to capital expenses required to comply

with new reporting burdens (facility upgrade costs are included in engineering costs as 

described above). Estimating annual sales of heavy-duty trucks at roughly 1.5 million 

units would result in just over $4 per engine/truck in the first year and less than $2 per 

engine/truck per year thereafter. These costs are not reflected in Table VIII-1, but are 

included in Table VIII-2 below as “Compliance Program” costs. 

(2) Annual Costs of the HD National Program

The costs presented here represent the incremental costs for newly added 

technology to comply with the program. Together with the projected increases in truck 

sales, the increases in per-truck average costs shown in Table VIII-1, above result in the 

total annual costs presented in Table VIII-2 below. Note that the costs presented in Table 

VIII-2 do not include the savings that will occur as a result of the improvements to fuel 

consumption. Those impacts are presented in Section VIII. E. Note also that the costs 

presented here represent costs estimated to occur presuming that the final standards will 

continue in perpetuity. Any changes to the final standards would be considered as part of 

a future rulemaking. In other words, the final standards do not apply only to 2014-2018 

model year trucks - they do, in fact, apply to all 2014 and later model year trucks. We 

present more detail regarding the 2014-2018 model year trucks in Sections VIII.L, where 

we summarize all monetized costs and benefits.

 

483 “Draft Supporting Statement for Information Collection Request,” Control of Greenhouse Gas 

Emissions from New Motor Vehicles: Proposed Heavy-Duty Engine and Vehicle Standards, EPA ICR 

Tracking Number 2394.01.
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Table VIII-2: Annual Costs Associated with the Program ($Millions of 2009 dollars)

Year HD Pickup 

and Vans

Vocational

Vehicles

Combination

Tractors

Other

Engineering

Costs

Compliance 

Program 

Costs

Annual

Costs

2012a$0 $0 $0 $170 $0 $170

2013 $0 $0 $0 $172 $0 $172

2014 $130 $185 $1,078 $170 $6.5 $1,569

2015 $157 $170 $922 $170 $2.3 $1,422

2016 $300 $202 $820 $170 $2.3 $1,495

2017 $447 $198 $951 $0 $2.3 $1,598

2018 $751 $201 $1,000 $0 $2.3 $1,955

2020 $754 $202 $1,001 $0 $2.3 $1,959

2030 $918 $216 $1,076 $0 $2.3 $2,212

2040 $1,024 $281 $1,372 $0 $2.3 $2,679

2050 $1,156 $354 $1,777 $0 $2.3 $3,290

NPV, 3% $17,070 $4,950 $24,487 $793 $52 $47,352

NPV, 7% $8,467 $2,588 $12,855 $724 $30 $24,665

Note:

a As explained in the text, “Other Engineering Costs” are estimated for years 2012 through 2016. These 

costs represent facility related costs and engineering development costs, much of which will have to begin 

prior to implementation of the new standards.

C. Indirect Cost Multipliers

(1) Markup Factors to Estimate Indirect Costs

For all segments in this analysis, indirect costs are estimated by applying indirect 

cost multipliers (ICM) to direct cost estimates. ICMs were calculated by EPA as a basis 

for estimating the impact on indirect costs of individual vehicle technology changes that 

would result from regulatory actions. Separate ICMs were derived for low, medium, and 

high complexity technologies, thus enabling estimates of indirect costs that reflect the 

variation in research, overhead, and other indirect costs that can occur among different 

technologies. ICMs were also applied in the light-duty rule. 

Prior to developing the ICM methodology, EPA and NHTSA both applied a retail 

price equivalent (RPE) factor to estimate indirect costs. RPEs are estimated by dividing 

the total revenue of a manufacturer by the direct manufacturing costs. As such, it 

includes all forms of indirect costs for a manufacturer and assumes that the ratio applies 

equally for all technologies. ICMs are based on RPE estimates that are then modified to 

reflect only those elements of indirect costs that would be expected to change in response 

to a regulatory-induced technology change. For example, warranty costs would be 

reflected in both RPE and ICM estimates, while marketing costs might only be reflected 

in an RPE estimate but not an ICM estimate for a particular technology, if the new 

regulatory-induced technology change is not one expected to be marketed to consumers. 

Because ICMs calculated by EPA are for individual technologies, many of which are 

small in scale, they often reflect a subset of RPE costs; as a result, the RPE is typically 

higher than an ICM. This is not always the case, as ICM estimates for complex 
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technologies may reflect higher than average indirect costs, with the resulting ICM larger 

than the averaged RPE for the industry. 

There is some level of uncertainty surrounding both the ICM and RPE markup 

factors. The ICM estimates used in this final action group all technologies into three 

broad categories and treat them as if individual technologies within each of the three 

categories (low, medium, and high complexity) will have the same ratio of indirect costs 

to direct costs. This simplification means it is likely that the direct cost for some 

technologies within a category will be higher and some lower than the estimate for the 

category in general. More importantly, the ICM estimates have not been validated 

through a direct accounting of actual indirect costs for individual technologies. Rather, 

the ICM estimates were developed using adjustment factors developed in two separate 

occasions: the first, a consensus process, was reported in the RTI report; the second, a 

modified Delphi method, was conducted separately and reported in an EPA memo.484 

Both these panels were composed of EPA staff members with previous background in the 

automobile industry; the memberships of the two panels overlapped but were not the 

same.485 The panels evaluated each element of the industry’s RPE estimates and 

estimated the degree to which those elements would be expected to change in proportion 

to changes in direct manufacturing costs. The method and estimates in the RTI report 

were peer reviewed by three industry experts and subsequently by reviewers for the 

International Journal of Production Economics.486 RPEs themselves are inherently

difficult to estimate because the accounting statements of manufacturers do not neatly

categorize all cost elements as either direct or indirect costs. Hence, each researcher 

developing an RPE estimate must apply a certain amount of judgment to the allocation of 

the costs. Moreover, RPEs for heavy- and medium-duty trucks and for engine 

manufacturers are not as well studied as they are for the light-duty automobile industry. 

Since empirical estimates of ICMs are ultimately derived from the same data used to 

measure RPEs, this affects both measures. However, the value of RPE has not been 

measured for specific technologies, or for groups of specific technologies. Thus applying 

a single average RPE to any given technology by definition overstates costs for very

simple technologies, or understates them for advanced technologies.

In the proposal, we requested comment on our ICM factors and whether it was 

most appropriate to use ICMs or RPEs. We received no comment on the issue 

specifically, other than basic comments that perhaps our ICM factors were low. In 

response, for this final action, we have adjusted our ICM factors such that they are 

slightly higher and, importantly, we have changed the way in which the factors are 

applied. The first change—increased ICM factors—has been done as a result of further 

thought among the EPA and NHTSA team that the ICM factors presented in the original 

 

484 Helfand, Gloria, and Sherwood, Todd. “Documentation of the Development of Indirect Cost Multipliers 

for Three Automotive Technologies.” Memorandum, Assessment and Standards Division, Office of 

Transportation and Air Quality, U.S. Environmental Protection Agency, August 2009.

485 NHTSA staff participated in the development of the process for the second, modified Delphi panel, and 

reviewed the results as they were developed, but did not serve on the panel.

486 The results of the RTI report were published in Alex Rogozhin, Michael Gallaher, Gloria Helfand, and 

Walter McManus, “Using Indirect Cost Multipliers to Estimate the Total Cost of Adding New Technology 

in the Automobile Industry.” International Journal of Production Economics 124 (2010): 360-368.
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RTI report487 for low and medium complexity technologies should no longer be used and 

that we should rely solely on the modified-Delphi values for these complexity levels.488 

For that reason, we have eliminated the averaging of original RTI values with modifiedDelphi values and instead are relying solely on the modified-Delphi values for low and 

medium complexity technologies. The second change—the way the factors are applied—

results in the warranty portion of the indirect costs being applied as a multiplicative factor 

(thereby decreasing going forward as direct manufacturing costs decrease due to 

learning), and the remainder of the indirect costs being applied as an additive factor 

(thereby remaining constant year-over-year and not being reduced due to learning). This 

second change has a comparatively large impact on the resultant technology costs and, 

we believe, more appropriately estimates costs over time. In addition to these changes, a 

secondary-level change was also made as part of this ICM recalculation to the light-duty

ICMs and, therefore, to the ICMs used in this analysis for heavy-duty pickups and vans. 

That change was to revise upward the RPE level reported in the original RTI report from 

an original value of 1.46 to 1.5 to reflect the long term average RPE. The original RTI 

study was based on 2008 data. However, an analysis of historical RPE data indicates that, 

although there is year to year variation, the average RPE has remained constant at 

roughly 1.5. ICMs will be applied to future year’s data and therefore NHTSA and EPA 

staff believe that it would be appropriate to base ICMs on the historical average rather 

than a single year’s result. Therefore, ICMs were adjusted to reflect this average level 

since the original value excluded net income. As a result, even the High 1 and High 2 

ICMs used for heavy-duty pickups and vans have also changed. These changes to our 

ICMs and the methodology are described in greater detail in Chapter 2 of the final RIA. 

D. Cost per Ton of Emissions Reductions

The agencies have calculated the cost per ton of GHG reductions associated with 

this program on a CO2eq basis using the above costs and the emissions reductions 

described in Sections VI and VII. These values are presented in Table VIII-3 through 

Table VIII-5 for HD pickups & vans, vocational vehicles and combination 

trucks/tractors, respectively. The cost per metric ton of GHG emissions reductions has 

been calculated in the years 2020, 2030, 2040, and 2050 using the annual vehicle 

compliance costs and emission reductions for each of those years. The value in 2050 

represents the long-term cost per ton of the emissions reduced. The agencies have also 

calculated the cost per metric ton of GHG emission reductions including the savings 

associated with reduced fuel consumption (presented below in Section VIII. E. ). This 

latter calculation does not include the other benefits associated with this program such as 

those associated with energy security benefits as discussed later in Section VIII.I. By

including the fuel savings, the cost per ton is generally less than $0 since the estimated 

value of fuel savings outweighs the program costs. The results for CO2eq costs per ton 

 

487

 Rogozhin, Alex, Michael Gallaher, and Walter McManus. “Automobile Industry Retail Price 

Equivalent and Indirect Cost Multipliers.” Report prepared for EPA by RTI International. EPA Report 

EPA-420-R-09-003, February 2009.

488 Helfand, Gloria, and Sherwood, Todd. “Documentation of the Development of Indirect Cost Multipliers 

for Three Automotive Technologies.” Memorandum, Assessment and Standards Division, Office of 

Transportation and Air Quality, U.S. Environmental Protection Agency, August 2009.
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under the HD National Program across all regulated categories are shown in Table 

VIII-6.

Table VIII-3: Annual Cost per Metric Ton of CO2eq Reduced – HD Pickup Trucks & Vans (2009

dollars)

Year Program 

Cost

Fuel 

Savings 

(post-tax)

CO2eq 

Reduced

Cost per Ton 

(without Fuel 

Savings)

Cost per Ton 

(with Fuel 

Savings)

2020 $800 $1,000 3 $240 -$60

2030 $900 $3,300 10 $90 -$230

2040 $1,000 $4,700 14 $70 -$270

2050 $1,200 $5,900 16 $80 -$300

Table VIII-4: Annual Cost per Metric Ton of CO2eq Reduced – Vocational Vehicles

a

(2009 dollars)

Year Program 

Cost

Fuel 

Savings 

(post-tax)

CO2eq 

Reduced

Cost per Ton 

(without Fuel 

Savings)

Cost per Ton 

(with Fuel 

Savings)

2020 $200 $1,200 4 $50 -$240

2030 $200 $2,600 9 $20 -$270

2040 $300 $3,800 12 $30 -$300

2050 $400 $5,000 14 $30 -$330

Note:

a The program costs, fuel savings, and CO2eq reductions of the engines installed in vocational vehicles 

are embedded in the vehicle standards and analysis.

Table VIII-5: Annual Cost per Metric Ton of CO2eq Reduced – Combination Tractorsa(2009

dollars)

Year Program 

Cost

Fuel 

Savings 

(post-tax)

CO2eq 

Reduced

Cost per Ton 

(without Fuel 

Savings)

Cost per Ton 

(with Fuel 

Savings)

2020 $1,000 $8,700 32 $30 -$240

2030 $1,100 $17,000 57 $20 -$280

2040 $1,400 $22,100 68 $20 -$300

2050 $1,800 $28,500 78 $20 -$340

Note:

a The program costs, fuel savings, and CO2eq reductions of the engines installed in tractors are 

embedded in the tractor standards and analysis.
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Table VIII-6: Annual Cost per Metric Ton of CO2eq Reduced – Final (2009 dollars)

Year Program 

Cost

Fuel 

Savings 

(post-tax)

CO2eq 

Reduced

Cost per Ton 

(without Fuel 

Savings)

Cost per Ton 

(with Fuel 

Savings)

2020 $2,000 $10,900 39 $50 -$230

2030 $2,200 $23,000 76 $30 -$270

2040 $2,700 $30,600 94 $30 -$300

2050 $3,300 $39,500 108 $30 -$340

E. Impacts of Reduction in Fuel Consumption

(1) What are the Projected Changes in Fuel Consumption

The new CO2 standards will result in significant improvements in the fuel 

efficiency of affected trucks. Drivers of those trucks will see corresponding savings 

associated with reduced fuel expenditures. The agencies have estimated the impacts on 

fuel consumption for the tailpipe CO2 standards. To do this, fuel consumption is 

calculated using both current CO2 emission levels and the new CO2 standards. The 

difference between these estimates represents the net savings from the CO2 standards. 

Note that the total number of miles that vehicles are driven each year is different under 

the control case scenario than in the reference case due to the “rebound effect,” which is 

discussed in Section VIII. E. (5) . EPA also notes that drivers who drive more than our 

average estimates for vehicle miles traveled (VMT) will experience more fuel savings; 

drivers who drive less than our average VMT estimates will experience less fuel savings. 

The expected impacts on fuel consumption are shown in Table VIII-7. The 

gallons shown in the tables reflect impacts from the new fuel consumption and CO2

standards and include increased consumption resulting from the rebound effect.

Table VIII-7: Fuel Consumption Reductions of the Program (Million gallons)

Year Gasoline Diesel

2014 1 473

2015 3 846

2016 14 1,171

2017 31 1,643

2018 58 2,123

2020 114 2,986

2030 348 5,670

2040 453 7,046

2050 522 8,158

(2) Potential Impacts on Global Fuel Use and Emissions 

EPA’s quantified reductions in fuel consumption focus on the gains from 

reducing fuel used by heavy-duty vehicles within the United States. However, as 
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discussed in Section VIII.I, EPA also recognizes that this regulation will lower the world 

price of oil (the “monopsony” effect). Lowering oil prices could lead to an uptick in oil 

consumption globally, leading to a corresponding increase in GHG emissions in other 

countries. This global increase in emissions could slightly offset some of the emission 

reductions achieved domestically as a result of the regulation. 

(3) What are the Monetized Fuel Savings?

Using the fuel consumption estimates presented in Table VIII-7, the agencies can 

calculate the monetized fuel savings associated with the final standards. To do this, 

reduced fuel consumption is multiplied in each year by the corresponding estimated 

average fuel price in that year, using the reference case taken from the AEO 2011. These 

estimates do not account for the significant uncertainty in future fuel prices; the 

monetized fuel savings will be understated if actual fuel prices are higher (or overstated if 

fuel prices are lower) than estimated. AEO is a standard reference used by NHTSA and 

EPA and many other government agencies to estimate the projected price of fuel. This

has been done using both the pre-tax and post-tax fuel prices. Since the post-tax fuel 

prices are the prices paid at fuel pumps, the fuel savings calculated using these prices 

represent the savings consumers would see. The pre-tax fuel savings are those savings 

that society would see. These results are shown in Table VIII-8. Note that in Section 

VIII.L, the overall benefits and costs of the rules are presented and, for that reason, only 

the pre-tax fuel savings are presented there.

Table VIII-8: Estimated Monetized Fuel Savings ($Millions of 2009 dollars)

Year Fuel Savings 

(pre-tax)

Fuel Savings 

(post-tax)

2014 $1,200 $1,400

2015 $2,200 $2,600

2016 $3,300 $3,800

2017 $4,800 $5,500

2018 $6,400 $7,400

2020 $9,600 $10,900

2030 $20,600 $23,000

2040 $28,000 $30,600

2050 $36,500 $39,500

NPV, 3% $375,300 $415,300

NPV, 7% $166,500 $185,400

As shown in Table VIII-8, the agencies are projecting that truck consumers would 

realize very large fuel savings as a result of the final standards. As discussed further in 

the introductory paragraphs of Section VIII, it is a conundrum from an economic 

perspective that these large fuel savings have not been provided by manufacturers and 

purchased by consumers of these products. Unlike in the light-duty vehicle market, the 

vast majority of vehicles in the medium- and heavy-duty truck market are purchased and 

operated by businesses; for them, fuel costs may represent substantial operating expenses. 
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Even in the presence of uncertainty and imperfect information – conditions that hold to 

some degree in every market – we generally expect firms to be cost-minimizing to 

survive in a competitive marketplace and to make decisions that are therefore in the best 

interest of the company and its owners and/or shareholders.

A number of behavioral and market phenomena may lead to a disconnect between 

how businesses account for fuel savings in their decisions and the way in which we 

account for the full stream of fuel savings for these rules, including imperfect information 

in the original and resale markets, split incentives, uncertainty in future fuel prices, and 

adjustment or transactions costs (see Section VIII.A for a more detailed discussion). As 

discussed below in the context of rebound in Section VIII.E.5, the nature of the 

explanation for this gap may influence the actual magnitude of the fuel savings. 

(4) Payback Period and Lifetime Savings on New Truck Purchases

Another factor of interest is the payback period on the purchase of a new truck 

that complies with the new standards. In other words, how long would it take for the 

expected fuel savings to outweigh the increased cost of a new vehicle? For example, a 

new 2018 MY HD pickup truck and van is estimated to cost $1,473 more, a vocational 

vehicle $419 more, and a combination tractor $6,215 more (all values are on average, and 

relative to the reference case vehicle) due to the addition of new GHG reducing 

technology. This new technology will result in lower fuel consumption and, therefore, 

savings in fuel expenditures. But how many months or years would pass before the fuel 

savings exceed the upfront costs? Table VIII-9 shows the payback period analysis for 

HD pickup trucks and vans. The table shows fuel consumed under the reference case and 

fuel consumed by a 2018 model year truck under the program, inclusive of fuel 

consumed due to rebound miles. The decrease in fuel consumed under the program is 

then monetized by multiplying by the fuel price reported by AEO (reference case) for 

2018 and later. This value represents the fuel savings expected under the program for a 

HD pickup or van. These savings are then discounted each year since future savings are 

considered to be of less value than current savings. Shown next are estimated increased 

costs (costs do not necessarily reflect increased prices which may be higher or lower than 

costs) for the new truck (refer to Table VIII-1). The next columns of Table VIII-9 show 

the period required for the fuel savings to exceed the new truck costs. As seen in the 

table, in the second year of ownership, the discounted fuel savings (at both 3% and 7% 

discount rates) have begun to outweigh the increased cost of the truck. As shown in the 

table, the full life savings using 3% discounting would be $6,138 and at 7% discounting 

would be $4,459.
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Table VIII-9: Payback Period for a 2018 Model Year HD Pickup or Van (2009$)

Year of 

Ownership

Reduced Fuel Use 

(gallons)b

Fuel SavingsaIncreased 

Cost

Cumulative Savings

Gasoline Diesel 3% 

Discount 

7% 

Discount

3% 

Discount 

7% 

Discount

1 67 122 $627 $616 -$1,048 -$421 -$433

2 67 122 $617 $583 $196 $151

3 66 120 $600 $546 $796 $696

4 64 117 $570 $499 $1,366 $1,196

5 62 113 $544 $458 $1,910 $1,654

6 59 108 $507 $411 $2,417 $2,065

7 56 102 $474 $370 $2,890 $2,435

Full Life 894 1,617 $7,187 $5,507 -$1,048 $6,138 $4,459

Notes:

a

Fuel savings calculated using the AEO 2011 reference case fuel prices through 2035. Fuel prices beyond 

2035 were extrapolated from an average growth rate for the years 2017 to 2035. Gasoline and diesel fuel 

prices have been weighted by gasoline and diesel fuel reductions estimated for all 2018 MY heavy-duty 

trucks during their lifetimes.

b Gallons under the control case include gallons consumed during rebound driving.

The story is somewhat different for vocational vehicles and combination tractors. 

These cases are shown in Table VIII-10 and Table VIII-11, respectively. Since these 

trucks travel more miles in a given year, their payback periods are shorter and are 

expected to occur within the second year of ownership under both the 3% and 7% 

discounting cases. As can be seen in Table VIII-10 and Table VIII-11, the lifetime fuel 

savings are estimated to be considerable with savings of $5,494 (3%) and $4,268 (7%) 

for the vocational vehicles and $72,875 (3%) and $58,162 (7%) for the combination 

tractors.

Table VIII-10: Payback Period for a 2018 Model Year Vocational Vehicle (2009$)

Year of 

Ownership

Reduced Fuel Use 

(gallons)b

Fuel SavingsaIncreased 

Cost

Cumulative Savings

Gasoline Diesel 3% 

Discount 

7% 

Discount

3% 

Discount 

7% 

Discount

1 51 161 $702 $690 -$378 $325 $312

2 47 146 $637 $602 $962 $914

3 44 134 $576 $524 $1,538 $1,438

4 41 122 $516 $452 $2,054 $1,889

5 38 110 $463 $390 $2,516 $2,279

6 34 98 $404 $328 $2,921 $2,607

7 31 87 $359 $280 $3,279 $2,887

Full Life 550 1,458 $5,872 $4,646 -$378 $5,494 $4,268

Notes:

a

Fuel savings calculated using the AEO 2011 reference case fuel prices through 2035. Fuel prices beyond 

2035 were extrapolated from an average growth rate for the years 2017 to 2035. Gasoline and diesel fuel 

prices have been weighted by gasoline and diesel fuel reductions estimated for all 2018 MY heavy-duty 

trucks during their lifetimes.

b Gallons under the control case include gallons consumed during rebound driving.
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Table VIII-11: Payback Period for a 2018 Model Year Combination Tractor (2009$)

Year of 

Ownership

Reduced Fuel Use 

(gallons)b

Fuel SavingsaIncreased 

Cost

Cumulative Savings

Gasoline Diesel 3% 

Discount 

7% 

Discount

3% 

Discount 

7% 

Discount

1 0 3,223 $10,736 $10,539 -$6,215 $4,522 $4,324

2 0 2,897 $9,619 $9,089 $14,141 $13,413

3 0 2,619 $8,564 $7,790 $22,705 $21,203

4 0 2,359 $7,532 $6,595 $30,237 $27,797

5 0 2,096 $6,626 $5,585 $36,863 $33,382

6 0 1,842 $5,684 $4,611 $42,546 $37,993

7 0 1,617 $4,951 $3,867 $47,497 $41,860

Full Life 0 26,148 $79,089 $64,376 -$6,215 $72,875 $58,162

Notes:

a

Fuel savings calculated using the AEO 2011 reference case fuel prices through 2035. Fuel prices beyond 

2035 were extrapolated from an average growth rate for the years 2017 to 2035. Gasoline and diesel fuel 

prices have been weighted by gasoline and diesel fuel reductions estimated for all 2018 MY heavy-duty 

trucks during their lifetimes.

b Gallons under the control case include gallons consumed during rebound driving.

All of these payback analyses include fuel consumed during rebound VMT in the 

control case but not in the reference case, consistent with other parts of the analysis. 

Further, this analysis does not include other societal impacts such as reduced time spent 

refueling or noise, congestion and accidents since the focus is meant to be on those 

factors buyers think about most while considering a new truck purchase. Note also that 

operators that drive more miles per year than the average would realize greater fuel 

savings than estimated here, and those that drive fewer miles per year would realize

lesser savings. The same holds true for operators that keep their vehicles longer (i.e., 

more years) than average in that they would realize greater lifetime fuel savings than 

operators that keep their vehicles for fewer years than average. Likewise, should fuel 

prices be higher than the AEO 2011 reference case, operators will realize greater fuel 

savings than estimated here while they would realize lesser fuel savings were fuel prices 

to be lower than the AEO 2011 reference case.

(5) Rebound Effect

The VMT rebound effect refers to the fraction of fuel savings expected to result 

from an increase in fuel efficiency that is offset by additional vehicle use. If truck 

shipping costs decrease as a result of lower fuel costs, an increase in truck VMT may

occur. Unlike the light-duty rebound effect, the heavy-duty (HD) rebound effect has not 

been extensively studied. Because the factors influencing the HD rebound effect are 

generally different from those affecting the light-duty rebound effect, much of the 

research on the light-duty rebound effect is not likely to apply to the HD sectors. One of 

the major differences between the HD rebound effect and the light-duty rebound effect is 

that HD vehicles are used primarily for business purposes. Since these businesses are 

profit driven, decision makers are highly likely to be aware of the costs and benefits of 

different shipping decisions, both in the near term and long term. Therefore, shippers are 
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much more likely to take into account changes in the overall operating costs per mile 

when making shipping decisions that affect VMT. 

Another difference from the light-duty case is that, as discussed in the recent NAS 

Report489, when calculating the percentage change in trucking costs to determine the 

rebound effect, all changes in the operating costs should be considered. The cost of labor 

and fuel generally constitute the top two shares of truck operating costs, depending on the 

price of petroleum,490, distance traveled, type of truck, and commodity.491 Finally, the 

equipment costs associated with the purchase or lease of the truck is also a significant 

component of total operating costs. Even though vehicle costs are lump-sum purchases, 

they can be considered operating costs for trucking firms, and these costs are, in many

cases, expected to be passed onto the final consumers of shipping services on a variable 

basis. This shipping cost increase could help temper the rebound effect relative to the 

case of light-duty vehicles, in which vehicle costs are not considered an operating cost by

vehicle owners.

When calculating the net change in operating costs, both the increase in new 

vehicle costs and the decrease in fuel costs per mile should be taken into consideration. 

The higher the net cost savings, the higher the expected rebound effect. Conversely, if 

the upfront vehicle costs outweighed future cost savings and total costs increased, 

shipping costs would rise, which would likely result in a decrease in truck VMT. In 

theory, other changes such as maintenance costs and insurance rates would also be taken 

into account, although information on these potential cost changes is extremely limited. 

In the proposal, we invited comments on the most appropriate methodology for factoring 

new vehicle purchase or leasing costs into the per-mile operating costs. We also invited 

comment or data on how these regulations could affect maintenance, insurance, or other 

operating costs. We did not receive any comments on these assumptions.

The following sections describe the factors affecting the rebound effect, different 

methodologies for estimating the rebound effect, and examples of different estimates of 

the rebound effect to date. According to the NAS study, it is “not possible to provide a 

confident measure of the rebound effect,” yet NAS concluded that a rebound effect likely

exists and that “estimates of fuel savings from regulatory standards will be somewhat 

misestimated if the rebound effect is not considered.” While we believe the HD rebound 

effect needs to be studied in more detail, we have attempted to capture the potential 

impact of the rebound effect in our analysis. In the proposal, we solicited data on the 

rebound effect and input on the most appropriate estimates to use for the rebound effect. 

However, we did not receive any new data or substantive comments. Therefore, for this 

final action, we continue to use a rebound effect for vocational vehicles of 15 percent, a 

rebound effect for HD pickup trucks and vans of 10 percent, and a rebound effect for 

 

489 See NAS Report, Note 197

490 American Transportation Research Institute, An Analysis of the Operational Costs of Trucking, 

December 2008 (Docket ID: EPA-HQ-OAR-2010-0162-0007). 

491 Transport Canada, Operating Cost of Trucks, 2005. See http://www.tc.gc.ca/eng/policy/report-acgoperatingcost2005-2005-e-2-1727.htm, accessed on July 16, 2010 (Docket ID: EPA-HQ-OAR-2010-0162-

0006). See also ATRI, 2008.
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combination tractors of 5 percent. These VMT impacts are reflected in the estimates of 

total GHG and other air pollution reductions presented in Chapter 5 of the RIA. 

(a) Factors Affecting the Magnitude of the Rebound Effect

The HD vehicle rebound effect is driven by the interaction of several different 

factors. In the short-run, decreasing the fuel cost per mile of driving could lead to a 

decrease in end product prices. Lower prices could stimulate additional demand for those 

products, which would then result in an increase in VMT. In the long run, shippers could 

reorganize their logistics and distribution networks to take advantage of lower truck 

shipping costs. For example, shippers may shift away from other modes of shipping such 

as rail, barge, or air. In addition, shippers may also choose to reduce the number of 

warehouses, reduce load rates, and make smaller, more frequent shipments, all of which 

could also lead to an increase in HD VMT. Finally, the benefits of the fuel savings could 

ripple through the economy, which could in turn increase overall demand for goods and 

services shipped by trucks, and therefore increase HD VMT. 

Conversely, if a fuel efficiency regulation leads to net increases in the cost of 

trucking because fuel savings do not fully offset the increase in upfront vehicle costs, 

then the price of trucking services could rise, spurring a decrease in HD VMT and a shift 

to alternative shipping modes. These effects would also ripple through the economy.

(b) Options for Quantifying the Rebound Effect

As described in the previous section, the fuel efficiency rebound effect for HD 

vehicles has not been studied as extensively as the rebound effect for light-duty vehicles, 

and virtually no research has been conducted on the HD pickup truck and van rebound 

effect. In the proposal, we discussed four options for quantifying the rebound effect and 

requested comments. We did not receive any substantive comments on the described 

methodologies. 

(i) Aggregate Estimates

The aggregate approximation approach quantifies the overall change in truck 

VMT as a result of a percentage change in freight rates. It is important to note that most 

of the aggregate estimates measure the change in freight demanded (tons or ton-miles), 

rather than a change in fuel consumption or VMT. The change in tons or ton-miles is 

more accurately characterized as a freight elasticity. Therefore, it may not be entirely 

appropriate to interpret these freight elasticities as measures of the rebound effect, 

although these terms are sometimes used interchangeably in the literature.492 Given these 

caveats, freight elasticity estimates rely on estimates of aggregate price elasticity of 

demand for trucking services, given a percentage change in trucking prices, which is 

generally referred to as an “own-price elasticity.” Estimates of trucking own-price 

elasticities vary widely from positive 1.72 to negative 7.92), and there is no general 

consensus on the most appropriate values to use, though a 2004 literature survey found 

 

492 Memo from Energy and Environmental Research Associates, LLC Regarding HDV Rebound Effect, 

dated June 8, 2011.
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aggregate elasticity estimates generally fall in the range of -0.5 to -1.5.493 In other words, 

given an own-price elasticity of -1.5, a 10 percent decrease in trucking prices leads to a 

15% increase in truck shipping demand. 

Another challenge of estimating the rebound effect using freight elasticities is that 

these values appear to vary substantially based on the demand elasticity measure (e.g., 

ton or ton-mile), the model specification (e.g., linear functional form or log linear), the 

length of the trip, and the type of cargo. In general, elasticity estimates of longer trips 

tend to be larger than elasticity estimates for shorter trips. In addition, elasticities tend to 

be larger for lower-value commodities compared to higher-value commodities. Although 

these factors explain some of the differences in estimates, much of the observed variation 

cannot be explained quantitatively. For example, a recent study that controlled for these 

variables only accounted for about half of the observed variation.494 

Another important variable influencing freight elasticity estimates is whether 

potential mode shifting is taken into account. Although the total demand for freight 

transport is generally determined by economic activity, there is often the choice of 

shipping freight on modes other than truck. This is because the United States has 

extensive rail, waterway and air transport networks in addition to an extensive highway

network; these networks closely parallel each other and are often both viable choices for 

freight transport for long-distance routes within the continent. If rates go down for one 

mode, there will be an increase in demand for that mode and some demand will be shifted 

from other modes. This “cross-price elasticity” is a measure of the percentage change in 

demand for shipping by another mode (e.g., rail) given a percentage change in the price 

of trucking. Aggregate estimates of cross-price elasticities also vary widely, and there is 

no general consensus on the most appropriate value to use for analytical purposes. The 

NAS report cites values ranging from 0.35 to 0.59.495 Other reports provide significantly

different cross-price elasticities, ranging from 0.1496 to 2.0.497 

When considering intermodal shift, the most relevant kinds of shipments are those 

that are competitive between rail and truck modes. These trips generally include longhaul shipments greater than 500 miles, which weigh between 50,000 and 80,000 pounds 

(the legal road limit in many states). Special kinds of cargo like coal and short-haul 

deliveries are of less interest because they are generally not economically transferable 

between truck and rail modes, and they would not be expected to shift modes except 

 

493 Graham and Glaister, “Road Traffic Demand Elasticity Estimates: A Review,” Transport Reviews 

Volume 24, 3, pp. 261-274, 2004 (Docket ID: EPA-HQ-OAR-2010-0162-0005). 

494 Li, Z., D.A. Hensher, and J.M. Rose, Identifying sources of systematic variation in direct price 

elasticities from revealed preference studies of inter-city freight demand. Transport Policy, 2011.

495 See 2010 NAS Report, Note 197. See also 2009 Cambridge Systematics, Inc., Draft Final Paper 

commissioned by the NAS in support of the medium-duty and heavy-duty report. Assessment of Fuel 

Economy Technologies for Medium and Heavy-duty Vehicles: Commissioned Paper on Indirect Costs and 

Alternative Approaches Docket ID: EPA-HQ-OAR-2010-0162-0009). 

496 Friedlaender, A. and Spady, R. (1980) A derived demand function for freight transportation, Review of

Economics and Statistics, 62, pp. 432–441 (Docket ID: EPA-HQ-OAR-2010-0162-0004).

497 Christidis and Leduc, “Longer and Heavier Vehicles for freight transport,” European Commission Joint 

Research Center’s Institute for Prospective Technology Studies, 2009 (Docket ID: EPA-HQ-OAR-2010-

0162-0010). 
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under an extreme price change. However, the total amount of freight that could 

potentially be subject to mode shifting has also not been studied extensively. 

(ii) Sector-Specific Estimates

Given the limited data available regarding the HD rebound effect, the aggregate 

approach greatly simplifies many of the assumptions associated with calculations of the 

rebound effect. In reality, however, responses to changes in fuel efficiency and new 

vehicle costs will vary significantly based on the commodities affected. A detailed, 

sector-specific approach would be expected to more accurately reflect changes in the 

trucking market in response to the standards in this program. For example, input-output 

tables could be used to determine the trucking cost share of the total delivered price of a 

commodity. Using the change in trucking prices described in the aggregate approach, the 

product-specific demand elasticities could be used to calculate the change in sales and 

shipments for each product. The change in shipment increases could then be weighted by 

the share of the trucking industry total, and then summed to get the total increase in 

trucking output. A simplifying assumption could then be made that the increase in output 

results in an increase in VMT. To the best of our knowledge, this type of data has not yet 

been collected. We did not receive any new information in response to our request for 

comments in the proposal, therefore we were unable to use this methodology for 

estimating the rebound effect for this final action. 

(iii) Econometric Estimates 

Similar to the methodology used to estimate the light-duty rebound effect, the HD 

rebound effect could be modeled econometrically by estimating truck demand as a 

function of economic activity (e.g., GDP) and different input prices (e.g., vehicle prices, 

driver wages, and fuel costs per mile). This type of econometric model could be 

estimated for either truck VMT or ton-miles as a measure of demand. The resulting 

elasticity estimates could then be used to determine the change in trucking demand, given 

the change in fuel cost and truck prices per mile from these standards. One of the 

challenges associated with an econometric analysis is the potential for omitted variable 

bias, which could either overstate or understate the potential rebound effect if the omitted 

variable is correlated with the controlled variables.

(iv) Other Modeling Approaches

Regulation of the heavy-duty industry has been studied in more detail in Europe, 

as the European Commission (EC) has considered allowing longer and heavier trucks for 

freight transport. Part of the analysis considered by the EC relies on country-specific 

modeling of changes in the freight sector that would result from changes in regulations.498 

This approach attempts to explicitly calculate modal shift decisions and impacts on GHG 

emissions. Although similar types of analysis have not been conducted extensively in the 

United States, research is currently underway that explores the potential for intermodal 

shifting in the United States. For example, Winebrake and Corbett have developed the 

Geospatial Intermodal Freight Transportation model, which evaluates the potential for 

 

498 Christidis and Leduc, “Longer and Heavier Vehicles for freight transport,” European Commission Joint 

Research Center’s Institute for Prospective Technology Studies, 2009. 
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GHG emissions reductions based on mode shifting, given existing limitations of 

infrastructure and other route characteristics in the United States. 499 This model 

connects multiple road, rail, and waterway transportation networks and embeds activitybased calculations in the model. Within this intermodal network, the model assigns 

various economic, time-of-delivery, energy, and environmental attributes to real-world 

goods movement routes. The model can then calculate different network optimization 

scenarios, based on changes in prices and policies.500 However, more work is needed in 

this area to determine whether this type of methodology is appropriate for the purposes of 

capturing the rebound effect. Therefore, we have not been able to use this methodology

for estimating the rebound effect for this final action. 

(c) Estimates of the Rebound Effect

The aggregate methodology was used by Cambridge Systematics, Inc. (CSI) to 

show several examples of the magnitude of the rebound effect. 501 In their paper 

commissioned by the NAS in support of the recent HD report, CSI calculated an effective 

rebound effect for two different technology cost and fuel savings scenarios associated 

with an example Class 8 truck. Scenario 1 increased average fuel economy from 5.59 

mpg to 6.8 mpg, with an additional cost of $22,930. Scenario 2 increased the average 

fuel economy to 9.1 mpg, at an incremental cost of $71,630 per vehicle. The CSI

examples provided estimates using a range of own-price elasticities (-0.5 to -1.5) and 

cross-price elasticities (0.35 to 0.59) from the literature. Based on these two scenarios 

and a number of simplifying assumptions to aid the calculations, CSI found a rebound 

effect of 11-31% for Scenario 1 and 5-16% for Scenario 2 when the fuel savings from 

reduced rail usage were not taken into account (“First rebound effect”). When the fuel 

savings from reduced rail usage were included in the calculations, the overall rebound 

effect was between 9-13% for Scenario 1 and 3-15% for Scenario 2 (“Second Rebound 

Effect”). See Table VIII-12.

CSI included a number of caveats associated with these calculations. Namely, the 

elasticity estimates derived from the literature are “heavily reliant on factors including the 

type of demand measures analyzed (vehicle-miles of travel, ton-miles, or tons), analysis 

geography, trip lengths, markets served, and commodities transported.” Furthermore, the 

CSI example only focused on Class 8 combination tractors and did not attempt to 

quantify the potential rebound effect for any other truck classes. Finally, these scenarios 

were characterized as “sketches” and were not included in the final NAS report. In fact, 

the NAS report asserted that it is “not possible to provide a confident measure of the 

rebound effect,” yet concluded that a rebound effect likely exists and that “estimates of 

 

499 Winebrake, James and Corbett, James J. (2010). “Improving the Energy Efficiency and Environmental 

Performance of Goods Movement,” in Sperling, Daniel and James S. Cannon (2010) Climate and 

Transportation Solutions: Findings from the 2009 Asilomar Conference on Transportation and Energy 

Policy. See http://www.its.ucdavis.edu/events/2009book/Chapter13.pdf (Docket ID: EPA-HQ-OAR-2010-

0162-0011)

500 Winebrake, J. J.; Corbett, J. J.; Falzarano, A.; Hawker, J. S.; Korfmacher, K.; Ketha, S.; Zilora, S., 

Assessing Energy, Environmental, and Economic Tradeoffs in Intermodal Freight Transportation, Journal 

of the Air & Waste Management Association, 58(8), 2008 (Docket ID: EPA-HQ-OAR-2010-0162-0008).

501 Cambridge Systematics, Inc., 2009. 
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fuel savings from regulatory standards will be somewhat misestimated if the rebound 

effect is not considered.” 

Table VIII-12: Range of Rebound Effect Estimates from Cambridge Systematics Aggregate 

Assessment

Scenario 1 

(6.8 mpg, $22,930)

Scenario 2

(9.1 mpg, $71,630)

“First Rebound Effect” (increase in truck 

VMT resulting from decrease in 

operating costs)

11-31% 5-16%

“Second Rebound Effect” (net fuel 

savings when decreases from rail are 

taken into account)

9-13 % 3-15%

As an alternative, using the econometric approach, NHTSA has estimated the 

rebound effect in the short run and long run for single unit (Class 4-7) and (Class 8) 

combination tractors. As shown in Table VIII-13, the estimates for the long-run rebound 

effect are larger than the estimates in the short run, which is consistent with the theory

that shippers have more flexibility to change their behavior (e.g., restructure contracts or 

logistics) when they are given more time. In addition, the estimates derived from the 

national data also showed larger rebound effects compared to the state data.502 One 

possible explanation for the difference in the estimates is that the national rebound 

estimates are capturing some of the impacts of changes in economic activity. 

Historically, large increases in fuel prices are highly correlated with economic 

downturns, and there may not be enough variation in the national data to differentiate the 

impact of fuel price changes from changes in economic activity. In contrast, some states 

may see an increase in output when energy prices increase (e.g., large oil producing states 

such as Texas and Alaska); therefore, the state data may be more accurately isolating the 

individual impact of fuel price changes.

 

502 NHTSA’s estimates of the rebound effect are derived from econometric analysis of national and state 

VMT data reported in Federal Highway Administration, Highway Statistics, various editions, Tables VM-1 

and VM-4. Specifically, the estimates of the rebound effect reported in Table VIII-10 are ranges of the 

estimated short-run and long-run elasticities of annual VMT by single-unit and combination trucks with 

respect to fuel cost per mile driven. (Fuel cost per mile driven during each year is equal to average fuel 

price per gallon during that year divided by average fuel economy of the truck fleet during that same year.) 

These estimates are derived from time-series regression of annual national aggregate VMT for the period 

1970-2008 on measures of nationwide economic activity, including aggregate GDP, the value of durable 

and nondurable goods production, and the volume of U.S. exports and imports of goods, and variables 

affecting the price of trucking services (driver wage rates, truck purchase prices, and fuel costs), and from 

regression of VMT for each individual state over the period 1994-2008 on similar variables measured at the 

state level.
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Table VIII-13: Range of Rebound Effect Estimates from NHTSA Econometric Analysis

Truck Type National Data State Data

Short Run Long Run Short Run Long Run

Single Unit 13-22% 28-45% 3-8% 12-21%

Combination N/A 12-14% N/A 4-5%

As discussed throughout this section, there are multiple methodologies for 

quantifying the rebound effect, and these different methodologies produce a large range 

of potential values of the rebound effect. However, for the purposes of quantifying the 

rebound effect for this program, we have used a rebound effect with respect to changes in 

fuel costs per mile on the lower range of the long-run estimates. Given the fact that the 

long-run state estimates are generally more consistent with the aggregate estimates, for 

this program we have chosen a rebound effect for vocational vehicles (single unit trucks) 

of 15% that is within the range of estimates from both methodologies. Similarly, we 

have chosen a rebound effect for combination tractors of 5%. 

To date, no estimates of the HD pickup truck and van rebound effect have been 

cited in the literature. Since these vehicles are used for very different purposes than 

heavy-duty vehicles, it does not necessarily seem appropriate to apply one of the heavyduty estimates to the HD pickup trucks and vans. These vehicles are more similar in use 

to large light-duty vehicles, so for the purposes of our analysis, we have chosen to apply

the light-duty rebound effect of 10 percent to this class of vehicles. 

For the purposes of this program, we have not taken into account any potential 

fuel savings or GHG emission reductions from the rail sector due to mode shifting. We 

requested comments on this assumption in the proposal, but we did not receive any new 

data or input. 

Furthermore, we have made a number of simplifying assumptions in our 

calculations, which are discussed in more detail in the RIA. Specifically, we have not 

attempted to capture how current market failures might impact the rebound effect. The 

direction and magnitude of the rebound effect in the HD market are expected to vary

depending on the existence and types of market failures affecting the fuel efficiency of 

the trucking fleet. If firms are already accurately accounting for the costs and benefits of 

these technologies and fuel savings, then these regulations would increase their net costs, 

because trucks would already include all the cost-effective technologies. As a result, the 

rebound effect would actually be negative and truck VMT would decrease as a result of 

these final regulations. However, if firms are not optimizing their behavior today due to 

factors such as lack of reliable information (see Section VIII.A. for further discussion), it 

is more likely that truck VMT would increase. If firms recognize their lower net costs as 

a result of these regulations and pass those costs along to their customers, then the 

rebound effect would increase truck VMT. This response assumes that trucking rates 

include both truck purchase costs and fuel costs, and that the truck purchase costs 

included in the rates spread those costs over the full expected lifetime of the trucks. If 

those costs are spread over a shorter period, as the expected short payback period implies, 
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then those purchase costs will inhibit reduction of freight rates, and the rebound effect 

will be smaller. 

As discussed in more detail in Section VIII.A, if there are market failures such as 

split incentives, estimating the rebound effect may depend on the nature of the failures. 

For example, if the original purchaser cannot fully recoup the higher upfront costs 

through fuel savings before selling the vehicle nor pass those costs onto the resale buyer, 

the firm would be expected to raise shipping rates. A firm purchasing the truck secondhand might lower shipping rates if the firm recognizes the cost savings after operating the 

vehicle, leading to an increase in VMT. Similarly, if there are split incentives and the 

vehicle buyer isn’t the same entity that purchases the fuel, than there would theoretically 

be a positive rebound effect. In this scenario, fuel savings would lower the net costs to 

the fuel purchaser, which would result in a larger increase in truck VMT. 

If all of these scenarios occur in the marketplace, the net effect will depend on the 

extent and magnitude of their relative effects, which are also likely to vary across truck 

classes (for instance, split incentives may be a much larger problem for Class 7 and 8 

tractors than they are for HD pickup trucks). Additional details on the rebound effect are 

included in the RIA. 

F. Class Shifting and Fleet Turnover Impacts

The agencies considered two additional potential indirect costs, benefits, effects, 

and externalities which may lead to unintended consequences of the program to improve

the fuel efficiency and reduce GHG emissions from HD trucks. The next sections cover 

the agencies’ qualitative discussions on potential class shifting and fleet turnover effects.

(1) Class Shifting

Heavy-duty vehicles are typically configured and purchased to perform a 

function. For example, a concrete mixer truck is purchased to transport concrete, a 

combination tractor is purchased to move freight with the use of a trailer, and a Class 3 

pickup truck could be purchased by a landscape company to pull a trailer carrying 

lawnmowers. The purchaser makes decisions based on many attributes of the vehicle, 

including the gross vehicle weight rating of the vehicle which in part determines the 

amount of freight or equipment that can be carried. If the final HD National Program 

impacts either the performance of the vehicle or the marginal cost of the vehicle relative 

to the other vehicle classes, then consumers may choose to purchase a different vehicle, 

resulting in the unintended consequence of increased fuel consumption and GHG 

emissions in-use.

The agencies, along with the NAS panel, found that there is little or no literature 

which evaluates class shifting between trucks.503 NHTSA and EPA qualitatively

evaluated the final rules in light of potential class shifting. The agencies looked at four 

potential cases of shifting: - from light-duty pickup trucks to heavy-duty pickup trucks; 

 

503 See 2010 NAS Report, Note 197, page 152.
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from sleeper cabs to day cabs; from combination tractors to vocational vehicles; and 

within vocational vehicles.

Light-duty pickup trucks, those with a GVWR of less than 8,500 pounds, are 

currently regulated under the existing CAFE program and will meet GHG emissions 

standards beginning in 2012. The increased stringency of the light-duty 2012-2016 MY 

vehicle rule has led some to speculate that vehicle consumers may choose to purchase 

heavy-duty pickup trucks that are currently unregulated if the cost of the light-duty

regulation is high relative to the cost to buy the larger heavy-duty pickup trucks. Since 

fuel consumption and GHG emissions rise significantly with vehicle mass, a shift from 

light-duty trucks to heavy-duty trucks would likely lead to higher fuel consumption and 

GHG emissions, an untended consequence of the regulations. Given the significant price 

premium of a heavy-duty truck (often five to ten thousand dollars more than a light-duty 

pickup), we believe that such a class shift would be unlikely even absent this program. 

With these final regulations, any incentive for such a class shift is significantly

diminished. The final regulations for the HD pickup trucks, and similarly for vans, are 

based on similar technologies and therefore reflect a similar expected increase in cost 

when compared to the light-duty GHG regulation. Hence, the combination of the two 

regulations provides little incentive for a shift from light-duty trucks to HD trucks. To 

the extent that our final regulation of heavy-duty pickups and vans could conceivably 

encourage a class shift towards lighter pickups, this unintended consequence would in 

fact be expected to lead to lower fuel consumption and GHG emissions as the smaller 

light-duty pickups are significantly more efficient than heavy-duty pickup trucks.

The projected cost increases for this final action differ significantly between Class 

8 day cabs and Class 8 sleeper cabs, reflecting our expectation that compliance with the 

final standards will lead truck consumers to specify sleeper cabs equipped with APUs 

while day cab consumers will not. Since Class 8 day cab and sleeper cab trucks perform 

essentially the same function when hauling a trailer, this raises the possibility that the 

higher cost for an APU equipped sleeper cab could lead to a shift from sleeper cab to day

cab trucks. We do not believe that such an intended consequence will occur for the 

following reasons. The addition of a sleeper berth to a tractor cab is not a consumerselectable attribute in quite the same way as other vehicle features. The sleeper cab 

provides a utility that long-distance trucking fleets need to conduct their operations -- an 

on-board sleeping berth that lets a driver comply with federally-mandated rest periods, as 

required by the Department of Transportation Federal Motor Carrier Safety 

Administration's hours-of-service regulations. The cost of sleeper trucks is already 

higher than the cost of day cabs, yet the fleets that need this utility purchase them.504 A 

day cab simply cannot provide this utility. The need for this utility would not be changed 

even if the marginal costs to reduce greenhouse gas emissions from sleeper cabs exceed 

the marginal costs to reduce greenhouse gas emissions from day cabs.505 A trucking fleet

 

504 A baseline tractor price of a new day cab is $89,500 versus $113,000 for a new sleeper cab based on 

information gathered by ICF in the “Investigation of Costs for Strategies to Reduce Greenhouse Gas 

Emissions for Heavy-Duty On-Road Vehicles”, July 2010. Page 3. Docket Identification Number EPAHQ-OAR-2010-0162-0044.

505 The average marginal cost difference between sleeper cabs and day cabs in the proposal is nearly 

$6,000.
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could decide to put its drivers in hotels in lieu of using sleeper berths, and switch to day

cabs. However, this is unlikely to occur in any great number, since the added cost for the 

hotel stays would far overwhelm differences in the marginal cost between day and 

sleeper cabs. Even if some fleets do opt to buy hotel rooms and switch to day cabs, they

would be highly unlikely to purchase a day cab that was aerodynamically worse than the 

sleeper cab they replaced, since the need for features optimized for long-distance hauling 

would not have changed. So in practice, there would likely be little difference to the 

environment for any switching that might occur. Further, while our projected costs 

assume the purchase of an APU for compliance, in fact our regulatory structure would 

allow compliance using a near zero cost software utility that eliminates tractor idling after 

five minutes. Using this compliance approach, the cost difference between a Class 8 

sleeper cab and day cab due to our final regulations is small. We are providing this 

alternative compliance approach reflecting that some sleeper cabs are used in team 

driving situations where one driver sleeps while the other drives. In that situation, an 

APU is unnecessary since the tractor is continually being driven when occupied. When it 

is parked, it will automatically eliminate any additional idling through the shutdown 

software. If trucking companies choose this option, then costs based on purchase of 

APUs may overestimate the costs of this program to this sector.

Class shifting from combination tractors to vocational vehicles may occur if a 

customer deems the additional marginal cost of tractors due to the regulation to be greater 

than the utility provided by the tractor. The agencies initially considered this issue when 

deciding whether to include Class 7 tractors with the Class 8 tractors or regulate them as 

vocational vehicles. The agencies’ evaluation of the combined vehicle weight rating of 

the Class 7 shows that if these vehicles were treated significantly differently from the 

Class 8 tractors, then they could be easily substituted for Class 8 tractors. Therefore, the 

agencies are finalizing to include both classes in the tractor category. The agencies 

believe that a shift from tractors to vocational vehicles would be limited because of the 

ability of tractors to pick up and drop off trailers at locations which cannot be done by

vocational vehicles.

The agencies do not envision that the final regulatory program will cause class 

shifting within the vocational class. The marginal cost difference due to the regulation of 

vocational vehicles is minimal. The cost of LRR tires on a per tire basis is the same for 

all vocational vehicles so the only difference in marginal cost of the vehicles is due to the 

number of axles. The agencies believe that the utility gained from the additional load 

carrying capability of the additional axle will outweigh the additional cost for heavier 

vehicles.506

In conclusion, NHTSA and EPA believe that the final regulatory structure for HD 

trucks does not significantly change the current competitive and market factors that 

determine purchaser preferences among truck types. Furthermore, even if a small amount 

of shifting does occur, any resulting GHG impacts are likely to be negligible because any

vehicle class that sees an uptick in sales is also being regulated for fuel efficiency. 

 

506 The final rule projects the difference in costs between the HHD and MHD vocational vehicle 

technologies is approximately $30.
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Therefore, the agencies did not include an impact of class shifting on the vehicle 

populations used to assess the benefits of the program. 

(2) Fleet Turnover Effect

A regulation that increases the cost to purchase and/or operate trucks could impact 

whether a consumer decides to purchase a new truck and the timing of that purchase. 

The term pre-buy refers to the idea that truck purchases may occur earlier than otherwise 

planned to avoid the additional costs associated with a new regulatory requirement. 

Slower fleet turnover, or low-buys, may occur when owners opt to keep their existing 

truck rather than purchase a new truck due to the incremental cost of the regulation. 

The NAS panel discusses the topics associated with HD truck fleet turnover. 

NAS noted that there is some empirical evidence of pre-buy behavior in response to the 

2004 and 2007 heavy-duty engine emission standards, with larger impacts occurring in 

response to higher costs.507 However, those regulations increased upfront costs to firms 

without any offsetting future cost savings from reduced fuel purchases. In summary, NAS 

stated that

...during periods of stable or growing demand in the freight sector, prebuy behavior may have significant impact on purchase patterns, especially

for larger fleets with better access to capital and financing. Under these 

same conditions, smaller operators may simply elect to keep their current 

equipment on the road longer, all the more likely given continued 

improvements in diesel engine durability over time. On the other hand, to 

the extent that fuel economy improvements can offset incremental 

purchase costs, these impacts will be lessened. Nevertheless, when it 

comes to efficiency investments, most heavy-duty fleet operators require 

relatively quick payback periods, on the order of two to three years.508 

The final regulations are projected to return fuel savings to the truck owners that 

offset the cost of the regulation within a few years for vocational vehicles and Class 7 and 

8 tractors, the categories where the potential for prebuy and delayed fleet turnover are 

concerns. In the case of vocational vehicles, the added cost is small enough that it is 

unlikely to have a substantial effect on purchasing behavior. In the case of Class 7 and 8 

trucks, the effects of the regulation on purchasing behavior will depend on the nature of 

the market failures and the extent to which firms consider the projected future fuel 

savings in their purchasing decisions. 

If trucking firms account for the rapid payback, they are unlikely to strategically 

accelerate or delay their purchase plans at additional cost in capital to avoid a regulation 

that will lower their overall operating costs. As discussed in Section VIII.A, this scenario 

may occur if this final program reduces uncertainty about fuel-saving technologies. More 

reliable information about ways to reduce fuel consumption allows truck purchasers to 

 

507 See NAS Report, Note 197, pp. 150-151

508 See NAS Report, Note 197, page 151.
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evaluate better the benefits and costs of additional fuel savings, primarily in the original 

vehicle market, but possibly in the resale market as well. 

Other market failures may leave open the possibility of some pre-buy or delayed 

purchasing behavior. Firms may not consider the full value of the future fuel savings for 

several reasons. For instance, truck purchasers may not want to invest in fuel efficiency

because of uncertainty about fuel prices. Another explanation is that the resale market 

may not fully recognize the value of fuel savings, due to lack of trust of new technologies 

or changes in the uses of the vehicles. Lack of coordination (also called split 

incentives—see Section VIII.A) between truck purchasers (who emphasize the up-front 

costs of the trucks) and truck operators, who would like the fuel savings, can also lead to 

pre-buy or delayed purchasing behavior. If these market failures prevent firms from fully

internalizing fuel savings when deciding on vehicle purchases, then pre-buy and delayed 

purchase could occur and could result in a slight decrease in the GHG benefits of the 

regulation. 

Thus, whether pre-buy or delayed purchase is likely to play a significant role in 

the truck market depends on the specific behaviors of purchasers in that market. Without 

additional information about which scenario is more likely to be prevalent, the Agencies 

are not projecting a change in fleet turnover characteristics due to this regulation. 

G. Benefits of Reducing CO2 Emissions

(1) Social Cost of Carbon

EPA has assigned a dollar value to reductions in CO2 emissions using recent 

estimates of the social cost of carbon (SCC). The SCC is an estimate of the monetized 

damages associated with an incremental increase in carbon emissions in a given year. It

is intended to include (but is not limited to) changes in net agricultural productivity, 

human health, property damages from increased flood risk, and the value of ecosystem 

services due to climate change. The SCC estimates used in this analysis were developed 

through an interagency process that included EPA, DOT/NHTSA, and other executive 

branch entities, and concluded in February 2010. We first used these SCC estimates in 

the benefits analysis for the light-duty 2012-2016 MY vehicle rule; see that rule’s 

preamble for a discussion of application of the SCC.

509

 The SCC Technical Support 

Document (SCC TSD) provides a complete discussion of the methods used to develop 

these SCC estimates.510

The interagency group selected four SCC values for use in regulatory analyses, 

which we have applied in this analysis: $5, $22, $36, and $67 per metric ton of CO2

 

509 See 2010 Light-DutyFinal Rule, Note 5, docket ID EPA-HQ-OAR-2009-0472-11424.

510 Docket ID EPA-HQ-OAR-2009-0472-114577, Technical Support Document: Social Cost of Carbon for 

Regulatory Impact Analysis Under Executive Order 12866, Interagency Working Group on Social Cost of 

Carbon, with participation by Council of Economic Advisers, Council on Environmental Quality, 

Department of Agriculture, Department of Commerce, Department of Energy, Department of 

Transportation, Environmental Protection Agency, National Economic Council, Office of Energy and 

Climate Change, Office of Management and Budget, Office of Science and Technology Policy, and 

Department of Treasury (February 2010). Also available at http://epa.gov/otaq/climate/regulations.htm
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emissions in 2010, in 2009 dollars.511,512 The first three values are based on the average 

SCC from three integrated assessment models, at discount rates of 5, 3, and 2.5 percent, 

respectively. SCCs at several discount rates are included because the literature shows 

that the SCC is quite sensitive to assumptions about the discount rate, and because no 

consensus exists on the appropriate rate to use in an intergenerational context. The fourth 

value is the 95th percentile of the SCC from all three models at a 3 percent discount rate. 

It is included to represent higher-than-expected impacts from temperature change further 

out in the tails of the SCC distribution. Low probability, high impact events are 

incorporated into all of the SCC values through explicit consideration of their effects in 

two of the three models as well as the use of a probability density function for 

equilibrium climate sensitivity. Treating climate sensitivity probabilistically results in 

more high temperature outcomes, which in turn lead to higher projections of damages.

The SCC increases over time because future emissions are expected to produce 

larger incremental damages as physical and economic systems become more stressed in 

response to greater climatic change. Note that the interagency group estimated the 

growth rate of the SCC directly using the three integrated assessment models rather than 

assuming a constant annual growth rate. This helps to ensure that the estimates are 

internally consistent with other modeling assumptions. Table VIII-14 presents the SCC 

estimates used in this analysis.

When attempting to assess the incremental economic impacts of carbon dioxide 

emissions, the analyst faces a number of serious challenges. A recent report from the 

National Academies of Science points out that any assessment will suffer from 

uncertainty, speculation, and lack of information about (1) future emissions of 

greenhouse gases, (2) the effects of past and future emissions on the climate system, (3) 

the impact of changes in climate on the physical and biological environment, and (4) the 

translation of these environmental impacts into economic damages.513 As a result, any

effort to quantify and monetize the harms associated with climate change will raise 

serious questions of science, economics, and ethics and should be viewed as provisional. 

The interagency group noted a number of limitations to the SCC analysis, 

including the incomplete way in which the integrated assessment models capture 

catastrophic and non-catastrophic impacts, their incomplete treatment of adaptation and 

technological change, uncertainty in the extrapolation of damages to high temperatures, 

and assumptions regarding risk aversion. The limited amount of research linking climate 

impacts to economic damages makes the interagency modeling exercise even more 

difficult. The interagency group hopes that over time researchers and modelers will work 

 

511 The interagency group decided that these estimates apply only to CO2 emissions. Given that warming 

profiles and impacts other than temperature change (e.g., ocean acidification) vary across GHGs, the group 

concluded “transforming gases into CO2-equivalents using GWP, and then multiplying the carbonequivalents by the SCC, would not result in accurate estimates of the social costs of non-CO2 gases” (SCC 

TSD, pg 13).

512 The SCC estimates were converted from 2007 dollars to 2008 dollars using a GDP price deflator (1.021) 

and again to 2009 dollars using a GDP price deflator (1.009) obtained from the Bureau of Economic 

Analysis, National Income and Product Accounts Table 1.1.4, Prices Indexes for Gross Domestic Product.

513

 National Research Council (2009). Hidden Costs of Energy: Unpriced Consequences of Energy 

Production and Use. National Academies Press. See docket ID EPA-HQ-OAR-2009-0472-11486.
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to fill these gaps and that the SCC estimates used for regulatory analysis by the Federal 

government will continue to evolve with improvements in modeling. Additional details 

on these limitations are discussed in the SCC TSD.

We received several comments regarding the SCC estimates used to analyze the 

proposed standards. In particular, these commenters discussed the incomplete treatment 

of impacts as well as discount rate selection. EPA has reviewed these comments in detail 

and responded to them in the EPA Response to Comments Document for the Joint 

Rulemaking. As noted in that document, the U.S. government intends to revise these 

estimates, taking into account new research findings that were not included in the first 

round, and has set a preliminary goal of revisiting the SCC values in the next few years or 

at such time as substantially updated models become available, and to continue to support 

research in this area. The EPA Response to Comments Document for the Joint 

Rulemaking discusses ongoing research in greater detail.

Applying the global SCC estimates, shown in Table VIII-14, to the estimated 

domestic reductions in CO2 emissions under this final program, we estimate the dollar 

value of the climate related benefits for each analysis year. For internal consistency, the 

annual benefits are discounted back to net present value terms using the same discount 

rate as each SCC estimate (i.e., 5%, 3%, and 2.5%) rather than 3% and 7%.514 These 

estimates are provided in Table VIII-15.

Table VIII-14: Social Cost of CO2, 2012 – 2050a(in 2009 dollars per Metric Ton)

Year Discount Rate and Statistic

5% Average 3% Average 2.5% Average 3%

95th Percentile

2012 $5.28 $23.06 $37.53 $70.14 

2015 $5.93 $24.58 $39.57 $75.03 

2020 $7.01 $27.10 $42.98 $83.17 

2025 $8.53 $30.43 $47.28 $93.11 

2030 $10.05 $33.75 $51.58 $103.06 

2035 $11.57 $37.08 $55.88 $113.00 

2040 $13.09 $40.40 $60.19 $122.95 

2045 $14.63 $43.34 $63.59 $131.66 

2050 $16.18 $46.27 $66.99 $140.37 

Note:

a The SCC values are dollar-year and emissions-year specific.

 

514 It is possible that other benefits or costs of final regulations unrelated to CO2 emissions will be 

discounted at rates that differ from those used to develop the SCC estimates.
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Table VIII-15: Monetized CO2 Benefits of Vehicle Program, CO2 Emissionsa(Million 2009$)

YEAR CO2

EMISSIONS 

REDUCTIO

N (MMT)

BENEFITS

Avg SCC at 

5% ($5-$16)a

Avg SCC at 

3% ($23-$46)a

Avg SCC at 

2.5% ($38-

$67)a

95th

percentile 

SCC at 3% 

($70-$140)a

2020 37.7 $264 $1,021 $1,619 $3,133

2030 73.1 $734 $2,467 $3,770 $7,532

2040 90.3 $1,182 $3,650 $5,437 $11,108

2050 103.9 $1,682 $4,810 $6,963 $14,590

Net Present 

Valueb

$9,045 $46,070 $78,037 $140,432

Notes:

a Except for the last row (net present value), the SCC values are dollar-year and emissions-year specific.

b Net present value of reduced CO2 emissions is calculated differently from other benefits. The same 

discount rate used to discount the value of damages from future emissions (SCC at 5, 3, 2.5 percent) is used 

to calculate net present value of SCC for internal consistency. Refer to the SCC TSD for more detail.

H. Non-GHG Health and Environmental Impacts

This section presents EPA’s analysis of the non-GHG health and environmental 

impacts that can be expected to occur as a result of the HD National Program. GHG 

emissions are predominantly the byproduct of fossil fuel combustion processes that also 

produce criteria and hazardous air pollutants. The vehicles that are subject to the 

standards are also significant sources of mobile source air pollution such as direct PM, 

NOX, VOCs and air toxics. The standards will affect exhaust emissions of these 

pollutants from vehicles. They will also affect emissions from upstream sources related 

to changes in fuel consumption. Changes in ambient ozone, PM2.5, and air toxics that 

will result from the standards are expected to affect human health in the form of 

premature deaths and other serious human health effects, as well as other important 

public health and welfare effects. 

As many commenters noted, it is important to quantify the health and 

environmental impacts associated with the final rules because a failure to adequately 

consider these ancillary co-pollutant impacts could lead to an incorrect assessment of 

their net costs and benefits. Moreover, co-pollutant impacts tend to accrue in the near 

term, while any effects from reduced climate change mostly accrue over a time frame of 

several decades or longer. 

This section is organized as follows: the first presents the PM- and ozone-related 

health and environmental impacts associated with final program in calendar year (CY) 

2030; the second discusses the related co-benefits associated with the model year (MY) 

analysis of the program.

515

 

 

515 EPA typically analyzes rule impacts (emissions, air quality, costs and benefits) in the year in which they 

occur; for this analysis, we selected 2030 as a representative future year. We refer to this analysis as the 
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(1) Quantified and Monetized Non-GHG Human Health Benefits of the 2030 

Calendar Year Analysis

This analysis reflects the impact of the HD National Program in 2030 compared 

to a future-year reference scenario without the program in place.516 Overall, we estimate 

that the final rules will lead to a net decrease in PM2.5-related health impacts. See Section 

VII.D of this preamble for more information about the air quality modeling results. 

While the PM-related air quality impacts are relatively small, the decrease in populationweighted national average PM2.5 exposure results in a net decrease in adverse PM-related 

human health impacts (the decrease in national population-weighted annual average 

PM2.5 is 0.005 μg/m3). 

The air quality modeling also projects decreases in ozone concentrations in many 

areas. While the ozone-related impacts are relatively small, the decrease in populationweighted national average ozone exposure results in a net decrease in ozone-related 

health impacts (population-weighted maximum 8-hour average ozone decreases by 0.164

ppb).

We base our analysis of the program’s impact on human health in 2030 on peerreviewed studies of air quality and human health effects.517,518

 These methods are 

described in more detail in the RIA that accompanies this action. Our benefits methods 

are also consistent with recent rulemaking analyses such as the final Transport Rule,519

the light-duty 2012-2016 MY vehicle rule,520 and the final Portland Cement National 

Emissions Standards for Hazardous Air Pollutants (NESHAP) RIA.521 To model the 

 

“Calendar Year” (CY) analysis. EPA also conducted a separate analysis of the impacts over the model year 

lifetimes of the 2012 through 2016 model year vehicles. We refer to this analysis as the “Model Year” 

(MY) analysis. In contrast to the CY analysis, the MY lifetime analysis shows the lifetime impacts of the 

program on each of these MY fleets over the course of its lifetime.

516 The future-year reference scenario to which the program impacts are compared in this section assumes 

no future gains in mpg (a “flat” scenario). For the final rulemaking, the agencies have also conducted a 

sensitivity analysis relative to the baseline assumptions. The alternative baseline assumes annual mpg 

projections, in the absence of the program, which were developed by the U.S. Energy Information 

Administration (EIA) for the Annual Energy Outlook (AEO). A description of the alternative baseline can 

be found in RIA Chapter 6. Due to time and resource constraints, EPA was unable to conduct full-scale 

photochemical air quality modeling to reflect the final rule impacts relative to this alternative baseline.

517 U.S. Environmental Protection Agency. (2006). Final Regulatory Impact Analysis (RIA) for the 

Proposed National Ambient Air Quality Standards for Particulate Matter. Prepared by: Office of Air and 

Radiation. Retrieved March, 26, 2009 at http://www.epa.gov/ttn/ecas/ria.html

518 U.S. Environmental Protection Agency. (2008). Final Ozone NAAQS Regulatory Impact Analysis. 

Prepared by: Office of Air and Radiation, Office of Air Quality Planning and Standards. Retrieved March, 

26, 2009 at http://www.epa.gov/ttn/ecas/ria.html

519 Final Federal Implementation Plans to Reduce Interstate Transport of Fine Particulate Matter and 

Ozone. Signed July 6, 2011. Available at http://epa.gov/airtransport/

520 U.S. Environmental Protection Agency. (2010). Regulatory Impact Analysis: Final Rulemaking to 

Establish Light-Duty Vehicle Greenhouse Gas Emission Standards and Corporate Average Fuel Economy 

Standards, EPA-420-R-10-009, April 2010. Available on the internet: 

http://www.epa.gov/otaq/climate/regulations/420r10009.pdf

521 U.S. Environmental Protection Agency (U.S. EPA). 2010. Regulatory Impact Analysis: National 

Emission Standards for Hazardous Air Pollutants from the Portland Cement Manufacturing Industry. 

Office of Air Quality Planning and Standards, Research Triangle Park, NC. Augues. Available on the 
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ozone and PM air quality impacts of this final action, we used the Community Multiscale 

Air Quality (CMAQ) model (see Chapter 8.2.2 of the RIA that accompanies this 

preamble). The modeled ambient air quality data serves as an input to the Environmental 

Benefits Mapping and Analysis Program version 4.0 (BenMAP).522 BenMAP is a 

computer program developed by the U.S. EPA that integrates a number of the modeling 

elements used in previous analyses (e.g., interpolation functions, population projections, 

health impact functions, valuation functions, analysis and pooling methods) to translate 

modeled air concentration estimates into health effects incidence estimates and monetized 

benefits estimates.

The range of total monetized ozone- and PM-related health impacts is presented 

in Table VIII-16 . We present total benefits based on the PM- and ozone-related 

premature mortality function used. The benefits ranges therefore reflect the addition of 

each estimate of ozone-related premature mortality (each with its own row in Table 

VIII-16) to estimates of PM-related premature mortality. These estimates represent 

EPA’s preferred approach to characterizing a best estimate of benefits. As is the nature 

of Regulatory Impact Analyses (RIAs), the assumptions and methods used to estimate air 

quality benefits evolve to reflect the agency’s most current interpretation of the scientific 

and economic literature. 

Table VIII-16: Estimated 2030 Monetized PM-and Ozone-Related Health Benefitsa

2030 Total Ozone and PM Benefits – PM Mortality Derived from American Cancer Society Analysis and 

Six-Cities Analysisa

Premature Ozone 

Mortality Function

Reference Total Benefits

(Billions, 2009$, 3% 

Discount Rate)b,c

Total Benefits

(Billions, 2009$, 7% 

Discount Rate) b,c

Multi-city analyses Bell et al., 2004 Total: $1.3 - $2.4

PM: $0.74 - $1.8

Ozone: $0.55

Total: $1.2 - $2.2

PM: $0.67 - $1.6

Ozone: $0.55

Huang et al., 2005 Total: $1.6 - $2.7

PM: $0.74 - $1.8

Ozone: $0.91

Total: $1.6 - $2.5

PM: $0.67 - $1.6

Ozone: $0.91

Schwartz, 2005 Total: $1.6 - $2.6

PM: $0.74 - $1.8

Ozone: $0.83

Total: $1.5 - $2.5

PM: $0.67 - $1.6

Ozone: $0.83

Meta-analyses Bell et al., 2005 Total: $2.4 - $3.5

PM: $0.74 - $1.8

Ozone: $1.7

Total: $2.4 - $3.3

PM: $0.67 - $1.6

Ozone: $1.7

Ito et al., 2005 Total: $3.1 - $4.2

PM: $0.74 - $1.8

Ozone: $2.4

Total: $3.0 - $4.0

PM: $0.67 - $1.6

Ozone: $2.4

Levy et al., 2005 Total: $3.1 - $4.2

PM: $0.74 - $1.8

Ozone: $2.4

Total: $3.1 - $4.0

PM: $0.67 - $1.6

Ozone: $2.4

Notes:

 

Internet at < http://www.epa.gov/ttn/ecas/regdata/RIAs/portlandcementfinalria.pdf >. EPA-HQ-OAR-2009-

0472-0241

522 Information on BenMAP, including downloads of the software, can be found at 

http://www.epa.gov/ttn/ecas/ benmodels.html.
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a Total includes premature mortality-related and morbidity-related ozone and PM2.5 benefits. Range was 

developed by adding the estimate from the ozone premature mortality function to the estimate of PM2.5-

related premature mortality derived from either the ACS study (Pope et al., 2002) or the Six-Cities study 

(Laden et al., 2006).

b Note that total benefits presented here do not include a number of unquantified benefits categories. A 

detailed listing of unquantified health and welfare effects is provided in Table VIII-17.

c Results reflect the use of both a 3 and 7 percent discount rate, as recommended by EPA’s Guidelines for 

Preparing Economic Analyses and OMB Circular A-4. Results are rounded to two significant digits for 

ease of presentation and computation.

The benefits in Table VIII-16 include all of the human health impacts we are able 

to quantify and monetize at this time. However, the full complement of human health 

and welfare effects associated with PM and ozone remain unquantified because of current 

limitations in methods or available data. We have not quantified a number of known or 

suspected health effects linked with ozone and PM for which appropriate health impact 

functions are not available or which do not provide easily interpretable outcomes (e.g., 

changes in heart rate variability). Additionally, we are unable to quantify a number of 

known welfare effects, including reduced acid and particulate deposition damage to 

cultural monuments and other materials, and environmental benefits due to reductions of 

impacts of eutrophication in coastal areas. These are listed in Table VIII-17. As a result, 

the health benefits quantified in this section are likely underestimates of the total benefits 

attributable to this final action.

Table VIII-17: Unquantified and Non-Monetized Potential Effects

Pollutant/Effects Effects Not Included in Analysis - Changes in:

Ozone Healtha Chronic respiratory damageb

Premature aging of the lungsb

Non-asthma respiratory emergency room visits

Exposure to UVb (+/-)

e

Ozone Welfare Yields for 

-commercial forests

-some fruits and vegetables

-non-commercial crops

Damage to urban ornamental plants

Impacts on recreational demand from damaged forest aesthetics

Ecosystem functions

Exposure to UVb (+/-)

e

PM HealthcPremature mortality - short term exposuresd

Low birth weight

Pulmonary function

Chronic respiratory diseases other than chronic bronchitis

Non-asthma respiratory emergency room visits

Exposure to UVb (+/-)

e

PM Welfare Residential and recreational visibility in non-Class I areas

Soiling and materials damage

Damage to ecosystem functions

Exposure to UVb (+/-)

e
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Nitrogen and 

Sulfate Deposition 

Welfare

Commercial forests due to acidic sulfate and nitrate deposition 

Commercial freshwater fishing due to acidic deposition 

Recreation in terrestrial ecosystems due to acidic deposition 

Existence values for currently healthy ecosystems 

Commercial fishing, agriculture, and forests due to nitrogen deposition 

Recreation in estuarine ecosystems due to nitrogen deposition

Ecosystem functions

Passive fertilization

CO Health Behavioral effects

HC/Toxics Healthf Cancer (benzene, 1,3-butadiene, formaldehyde, acetaldehyde)

Anemia (benzene)

Disruption of production of blood components (benzene)

Reduction in the number of blood platelets (benzene)

Excessive bone marrow formation (benzene)

Depression of lymphocyte counts (benzene)

Reproductive and developmental effects (1,3-butadiene)

Irritation of eyes and mucus membranes (formaldehyde)

Respiratory irritation (formaldehyde)

Asthma attacks in asthmatics (formaldehyde)

Asthma-like symptoms in non-asthmatics (formaldehyde)

Irritation of the eyes, skin, and respiratory tract (acetaldehyde)

Upper respiratory tract irritation and congestion (acrolein)

HC/Toxics Welfare Direct toxic effects to animals

Bioaccumulation in the food chain

Damage to ecosystem function

Odor

Notes:

a

The public health impact of biological responses such as increased airway responsiveness to stimuli, 

inflammation in the lung, acute inflammation and respiratory cell damage, and increased susceptibility to 

respiratory infection are likely partially represented by our quantified endpoints.

b The public health impact of effects such as chronic respiratory damage and premature aging of the lungs 

may be partially represented by quantified endpoints such as hospital admissions or premature mortality, 

but a number of other related health impacts, such as doctor visits and decreased athletic performance, 

remain unquantified.

c

In addition to primary economic endpoints, there are a number of biological responses that have been 

associated with PM health effects including morphological changes and altered host defense mechanisms. 

The public health impact of these biological responses may be partly represented by our quantified 

endpoints.

d While some of the effects of short-term exposures are likely to be captured in the estimates, there may be 

premature mortality due to short-term exposure to PM not captured in the cohort studies used in this 

analysis. However, the PM mortality results derived from the expert elicitation do take into account 

premature mortality effects of short term exposures.

e May result in benefits or disbenefits.

f Many of the key hydrocarbons related to this action are also hazardous air pollutants listed in the CAA.

While there will be impacts associated with air toxic pollutant emission changes 

that result from this final action, we do not attempt to monetize those impacts. This is 

primarily because currently available tools and methods to assess air toxics risk from 

mobile sources at the national scale are not adequate for extrapolation to incidence 

estimations or benefits assessment. The best suite of tools and methods currently
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available for assessment at the national scale are those used in the National-Scale Air 

Toxics Assessment (NATA). The EPA Science Advisory Board specifically commented 

in their review of the 1996 NATA that these tools were not yet ready for use in a 

national-scale benefits analysis, because they did not consider the full distribution of 

exposure and risk, or address sub-chronic health effects.523 While EPA has since 

improved these tools, there remain critical limitations for estimating incidence and 

assessing benefits of reducing mobile source air toxics. 

As part of the second prospective analysis of the benefits and costs of the Clean 

Air Act,

524 EPA conducted a case study analysis of the health effects associated with 

reducing exposure to benzene in Houston from implementation of the Clean Air Act. 

While reviewing the draft report, EPA’s Advisory Council on Clean Air Compliance 

Analysis concluded that “the challenges for assessing progress in health improvement as 

a result of reductions in emissions of hazardous air pollutants (HAPs) are daunting...due 

to a lack of exposure-response functions, uncertainties in emissions inventories and 

background levels, the difficulty of extrapolating risk estimates to low doses and the 

challenges of tracking health progress for diseases, such as cancer, that have long latency

periods.”525 EPA continues to work to address these limitations; however, we did not 

have the methods and tools available for national-scale application in time for the 

analysis of the final action.

526

 

EPA is also unaware of specific information identifying any effects on listed 

endangered species from the small fluctuations in pollutant concentrations associated

with this program (see Section VII.D). Furthermore, our current modeling tools are not 

designed to trace fluctuations in ambient concentration levels to potential impacts on 

particular endangered species. 

(a) Quantified Human Health Impacts

Table VIII-18 and Table VIII-19 present the annual PM2.5 and ozone health 

impacts, respectively, in the 48 contiguous U.S. states associated with the HD National 

Program for 2030. For each endpoint presented in Table VIII-18 and Table VIII-19, we 

provide both the mean estimate and the 90% confidence interval. 

 

523 Science Advisory Board. 2001. NATA – Evaluating the National-Scale Air Toxics Assessment for 

1996 – an SAB Advisory. http://www.epa.gov/ttn/atw/sab/sabrev.html.

524 U.S. Environmental Protection Agency (U.S. EPA). 2011. The Benefits and Costs of the Clean Air Act 

from 1990 to 2020. Office of Air and Radiation, Washington, DC. March. Available on the Internet at 

<http://www.epa.gov/air/sect812/feb11/fullreport.pdf>.

525 U.S. Environmental Protection Agency—Science Advisory Board (U.S. EPA-SAB). 2008. Benefits of 

Reducing Benzene Emissions in Houston, 1990–2020. EPA-COUNCIL-08-001. July. Available at 

<http://yosemite.epa.gov/sab/sabproduct.nsf/D4D7EC9DAEDA8A548525748600728A83/$File/EPACOUNCIL-08-001-unsigned.pdf>.

526 In April, 2009, EPA hosted a workshop on estimating the benefits or reducing hazardous air pollutants. 

This workshop built upon the work accomplished in the June 2000 Science Advisory Board/EPA 

Workshop on the Benefits of Reductions in Exposure to Hazardous Air Pollutants, which generated 

thoughtful discussion on approaches to estimating human health benefits from reductions in air toxics 

exposure, but no consensus was reached on methods that could be implemented in the near term for a broad 

selection of air toxics. Please visit http://epa.gov/air/toxicair/2009workshop.html for more information 

about the workshop and its associated materials.
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Using EPA’s preferred estimates, based on the American Cancer Society (ACS)

and Six-Cities studies and no threshold assumption in the model of mortality, we estimate 

that the final rules will result in between 78 and 200 cases of avoided PM2.5-related 

premature mortalities annually in 2030. As a sensitivity analysis, when the range of 

expert opinion is used, we estimate between 26 and 260 fewer premature mortalities in 

2030 (see Table 8-14in the RIA that accompanies this action). For ozone-related 

premature mortality in 2030, we estimate a range of between 54 to 240 fewer premature 

mortalities.

Table VIII-18: Estimated PM2.5-Related Health Impactsa

Health Effect 2030 Annual Reduction 

in Incidence

(5th% - 95th%ile)

Premature Mortality – Derived from epidemiology 

literatureb

 Adult, age 30+, ACS Cohort Study (Pope et al., 2002)

 Adult, age 25+, Six-Cities Study (Laden et al., 2006)

 Infant, age <1 year (Woodruff et al., 1997)

78

(30 – 130)

200

(110 – 290)

0

(0 – 1)

Chronic bronchitis (adult, age 26 and over) 53

(10 – 97)

Non-fatal myocardial infarction (adult, age 18 and over) 150

(54 – 240)

Hospital admissions - respiratory (all ages)c20

(10 – 30)

Hospital admissions - cardiovascular (adults, age >18)d45

(32 – 52)

Emergency room visits for asthma (age 18 years and 

younger) 

81

(48 – 120)

Acute bronchitis, (children, age 8-12) 130

(0 – 270)

Lower respiratory symptoms (children, age 7-14) 1,600

(750 – 2,400)

Upper respiratory symptoms (asthmatic children, age 9-

18)

1,200

(370 – 2,000)

Asthma exacerbation (asthmatic children, age 6-18) 1,400

(160 – 4,000)

Work loss days 9,700

(8,500 – 11,000)
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Minor restricted activity days (adults age 18-65) 57,000

(48,000 – 66,000)

Notes:

a

Incidence is rounded to two significant digits. Estimates represent incidence within the 48 

contiguous United States. 

b

PM-related adult mortality based upon the American Cancer Society (ACS) Cohort Study (Pope et 

al., 2002) and the Six-Cities Study (Laden et al., 2006). Note that these are two alternative estimates 

of adult mortality and should not be summed. PM-related infant mortality based upon a study by 

Woodruff, Grillo, and Schoendorf, (1997).527

c Respiratory hospital admissions for PM include admissions for chronic obstructive pulmonary 

disease (COPD), pneumonia and asthma.

d Cardiovascular hospital admissions for PM include total cardiovascular and subcategories for 

ischemic heart disease, dysrhythmias, and heart failure.

Table VIII-19: Estimated Ozone-Related Health Impactsa

Health Effect 2030 Annual Reduction in 

Incidence

(5th% - 95th%ile)

Premature Mortality, All agesb

Multi-City Analyses 

 Bell et al. (2004) – Non-accidental

 Huang et al. (2005) – Cardiopulmonary

 Schwartz (2005) – Non-accidental

Meta-analyses:

 Bell et al. (2005) – All cause

 Ito et al. (2005) – Non-accidental

 Levy et al. (2005) – All cause

54

(23 – 84)

90

(43 – 140)

82

(34 – 130)

170

(96 – 250)

240

(160 – 320)

240

(180 – 310)

Hospital admissions- respiratory causes (adult, 65 

and older)c

510

(69 – 870)

Hospital admissions -respiratory causes (children, 

under 2)

320

(160 – 470)

Emergency room visit for asthma (all ages) 230

(0 – 630)

Minor restricted activity days (adults, age 18-65) 300,000

(150,000 – 450,000)

School absence days 120,000

(52,000 – 170,000

Notes:

a

Incidence is rounded to two significant digits. Estimates represent incidence within the 48 

contiguous U.S. 

b Estimates of ozone-related premature mortality are based upon incidence estimates derived from 

 

527 Woodruff, T.J., J. Grillo, and K.C. Schoendorf. 1997. “The Relationship Between Selected Causes of 

Postneonatal Infant Mortality and Particulate Air Pollution in the United States.” Environmental Health 

Perspectives 105(6):608-612.
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several alternative studies: Bell et al. (2004); Huang et al. (2005); Schwartz (2005) ; Bell et al. 

(2005); Ito et al. (2005); Levy et al. (2005). The estimates of ozone-related premature mortality 

should therefore not be summed.

c Respiratory hospital admissions for ozone include admissions for all respiratory causes and 

subcategories for COPD and pneumonia. 

(b) Monetized Benefits

Table VIII-20 presents the estimated monetary value of changes in the incidence 

of ozone and PM2.5-related health effects. All monetized estimates are stated in 2009$. 

These estimates account for growth in real gross domestic product (GDP) per capita 

between the present and 2030. Our estimate of total monetized benefits in 2030 for the 

program, using the ACS and Six-Cities PM mortality studies and the range of ozone 

mortality assumptions, is between $1.3 and $4.2 billion, assuming a 3 percent discount 

rate, or between $1.2 and $4.0 billion, assuming a 7 percent discount rate.

Table VIII-20: Estimated Monetary Value of Changes in Incidence of Health and Welfare Effects in 

2030 (Millions of 2009$) a,b

PM2.5-Related Health Effect (5th and 95th %ile)

Premature Mortality –

Derived from 

Epidemiology Studiesc,d,

Adult, age 30+ - ACS study 

(Pope et al., 2002)

 3% discount rate

 7% discount rate

$680

($87 - $1,800)

$620

($79 - $1,600)

Adult, age 25+ - Six-Cities 

study (Laden et al., 2006)

 3% discount rate

 7% discount rate

$1,800

($250 - $4,300)

$1,600

($220 - $3,900)

Infant Mortality, <1 year –

(Woodruff et al. 1997)

$2.5

($0 - $9.4)

Chronic bronchitis (adults, 26 and over) $29

($2.4 - $96)

Non-fatal acute myocardial infarctions 

 3% discount rate

 7% discount rate

$16

($3.7 - $38)

$16

($3.4 - $38)

Hospital admissions for respiratory causes $0.31

($0.15 - $0.45)
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Hospital admissions for cardiovascular causes $1.3

($0.83 - $1.8)

Emergency room visits for asthma $0.03

($0.02 - $0.05)

Acute bronchitis (children, age 8–12) $0.01

($0 - $0.03)

Lower respiratory symptoms (children, 7–14) $0.03

($0.01 - $0.06)

Upper respiratory symptoms (asthma, 9–11) $0.04

($0.01 - $0.08)

Asthma exacerbations $0.08

($0.009 - $0.23)

Work loss days $1.6

($1.4 - $1.8)

Minor restricted-activity days (MRADs) $3.6

($2.1 - $5.2)

Ozone-related Health Effect

Premature Mortality, All ages –

Derived from Multi-city analyses

Bell et al., 2004 $520

($69 - $1,300)

Huang et al., 2005 $880

($120 - $2,200)

Schwartz, 2005 $800

($100 - $2,000)

Premature Mortality, All ages –

Derived from Meta-analyses

Bell et al., 2005 $1,700

($240 - $4,100)

Ito et al., 2005 $2,300

($350 - $5,500)

Levy et al., 2005 $2,400

($350 - $5,500)

Hospital admissions- respiratory causes (adult, 65 and 

older)

$13

($1.7 - $22)

Hospital admissions- respiratory causes (children, under 

2)

$3.4

($1.8 - $5.0)

Emergency room visit for asthma (all ages) $0.09

($0 - $0.23)

Minor restricted activity days (adults, age 18-65) $19

($8.6 - $32)

School absence days $11

($5.0 - $16)

Notes:

a Monetary benefits are rounded to two significant digits for ease of presentation and computation. 

PM and ozone benefits are nationwide. 

b Monetary benefits adjusted to account for growth in real GDP per capita between 1990 and the 

analysis year (2030).

c Valuation assumes discounting over the SAB recommended 20 year segmented lag structure. 

Results reflect the use of 3 percent and 7 percent discount rates consistent with EPA and OMB 

guidelines for preparing economic analyses.
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(c) What Are the Limitations of the Benefits Analysis?

Every benefit-cost analysis examining the potential effects of a change in 

environmental protection requirements is limited to some extent by data gaps, limitations 

in model capabilities (such as geographic coverage), and uncertainties in the underlying 

scientific and economic studies used to configure the benefit and cost models. 

Limitations of the scientific literature often result in the inability to estimate quantitative 

changes in health and environmental effects, such as potential decreases in premature 

mortality associated with decreased exposure to carbon monoxide. Deficiencies in the 

economics literature often result in the inability to assign economic values even to those 

health and environmental outcomes which can be quantified. These general uncertainties 

in the underlying scientific and economics literature, which can lead to valuations that are 

higher or lower, are discussed in detail in the RIA and its supporting references. Key

uncertainties that have a bearing on the results of the benefit-cost analysis of the final 

rules include the following:

 The exclusion of potentially significant and unquantified benefit categories (such as 

health, odor, and ecological benefits of reduction in air toxics, ozone, and PM);

 Errors in measurement and projection for variables such as population growth;

 Uncertainties in the estimation of future year emissions inventories and air quality;

 Uncertainty in the estimated relationships of health and welfare effects to changes in 

pollutant concentrations including the shape of the C-R function, the size of the effect 

estimates, and the relative toxicity of the many components of the PM mixture; 

 Uncertainties in exposure estimation; and

 Uncertainties associated with the effect of potential future actions to limit emissions.

As Table VIII-20 indicates, total benefits are driven primarily by the reduction in 

premature mortalities each year. Some key assumptions underlying the premature 

mortality estimates include the following, which may also contribute to uncertainty:

 Inhalation of fine particles is causally associated with premature death at 

concentrations near those experienced by most Americans on a daily basis. Although 

biological mechanisms for this effect have not yet been completely established, the 

weight of the available epidemiological, toxicological, and experimental evidence 

supports an assumption of causality. The impacts of including a probabilistic 

representation of causality were explored in the expert elicitation-based results of the 

PM NAAQS RIA. 

 All fine particles, regardless of their chemical composition, are equally potent in 

causing premature mortality. This is an important assumption, because PM produced 

via transported precursors emitted from heavy-duty engines may differ significantly

from PM precursors released from electric generating units and other industrial 

sources. However, no clear scientific grounds exist for supporting differential effects 

estimates by particle type.

 The C-R function for fine particles is approximately linear within the range of 

ambient concentrations under consideration. Thus, the estimates include health 
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benefits from reducing fine particles in areas with varied concentrations of PM, 

including both regions that may be in attainment with PM2.5 standards and those that 

are at risk of not meeting the standards.

 There is uncertainty in the magnitude of the association between ozone and premature 

mortality. The range of ozone benefits associated with the coordinated strategy is 

estimated based on the risk of several sources of ozone-related mortality effect 

estimates. In a report on the estimation of ozone-related premature mortality

published by the National Research Council, a panel of experts and reviewers 

concluded that short-term exposure to ambient ozone is likely to contribute to 

premature deaths and that ozone-related mortality should be included in estimates of 

the health benefits of reducing ozone exposure.528 EPA has requested advice from the 

National Academy of Sciences on how best to quantify uncertainty in the relationship 

between ozone exposure and premature mortality in the context of quantifying 

benefits.

Despite the uncertainties described above, we believe this analysis provides a 

conservative estimate of the estimated non-GHG health and environmental benefits of the 

standards in future years because of the exclusion of potentially significant benefit 

categories that are not quantifiable at this time. Acknowledging benefits omissions and 

uncertainties, we present a best estimate of the total benefits based on our interpretation 

of the best available scientific literature and methods supported by EPA’s technical peer 

review panel, the Science Advisory Board’s Health Effects Subcommittee (SAB-HES). 

The National Academies of Science (NRC, 2002) has also reviewed EPA’s methodology

for analyzing the health benefits of measures taken to reduce air pollution. EPA 

addressed many of these comments in the analysis of the final PM NAAQS.529,530 This 

analysis incorporates this work to the extent possible. 

(2) Non-GHG Human Health Benefits of the Model Year (MY) Analysis

As described in Section VII, the final standards will reduce emissions of several 

criteria and toxic pollutants and precursors. EPA typically analyzes rule impacts 

(emissions, air quality, costs and benefits) in the year in which they occur; for the 

analysis of non-GHG ambient air quality and health impacts, we selected 2030 as a 

representative future year since resource and time constraints precluded EPA from 

considering multiple calendar years. We refer to this analysis as the “Calendar Year” 

(CY) analysis because the benefits of the program reflect impacts across all regulated 

vehicles in a calendar year. 

EPA also conducted a separate analysis of the impacts over the model year 

lifetimes of the 2014 through 2018 model year vehicles. We refer to this analysis as the 

 

528 National Research Council (NRC), 2008. Estimating Mortality Risk Reduction and Economic Benefits 

from Controlling Ozone Air Pollution. The National Academies Press: Washington, D.C.

529 National Research Council (NRC). 2002. Estimating the Public Health Benefits of Proposed Air 

Pollution Regulations. The National Academies Press: Washington, D.C.

530 U.S. Environmental Protection Agency. October 2006. Final Regulatory Impact Analysis (RIA) for the 

Proposed National Ambient Air Quality Standards for Particulate Matter. Prepared by: Office of Air and 

Radiation. Available at http://www.epa.gov/ttn/ecas/ria.html.
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505 of 971

“Model Year” (MY) analysis (See Chapter 6 of the RIA that accompanies this preamble). 

In contrast to the CY analysis, the MY analysis estimates the impacts of the program on 

each MY fleet over the course of its lifetime. Due to analytical and resource limitations, 

however, MY non-GHG emissions (direct PM, VOCs, NO2 and SO2) were not estimated 

for this analysis. Because MY impacts are measured in relation to only the lifetime of a 

particular vehicle model year (2014, 2015, 2016, 2017, and 2018), and assumes no 

additional controls to model year vehicles beyond 2018, the impacts are smaller than if 

the impacts of all regulated vehicles were considered. We therefore expect that the nonGHG health-related benefits associated with the MY analysis will be smaller than those 

estimated for the CY analysis, both in a given year (such as 2030) and in present value 

terms across a given time period (such as 2014 – 2050). 

I. Energy Security Impacts

The HD National Program is designed to reduce fuel consumption and GHG 

emissions in medium and heavy-duty (HD) vehicles, which will result in improved fuel 

efficiency and, in turn, help to reduce U.S. petroleum imports. A reduction of U.S. 

petroleum imports reduces both financial and strategic risks caused by potential sudden 

disruptions in the supply of imported petroleum to the U.S. This reduction in risk is a 

measure of improved U.S. energy security. This section summarizes the agencies’ 

estimates of U.S. oil import reductions and energy security benefits of the final HD 

National Program. Additional discussion of this issue can be found in Chapter 9.7 of the 

RIA.

(1) Implications of Reduced Petroleum Use on U.S. Imports

In 2008, U.S. petroleum import expenditures represented 21 percent of total U.S. 

imports of all goods and services.531 In 2008, the United States imported 66 percent of 

the petroleum it consumed, and the transportation sector accounted for 70 percent of total 

U.S. petroleum consumption. This compares to approximately 37 percent of petroleum 

from imports and 55 percent of consumption from petroleum in the transportation sector 

in 1975.532 It is clear that petroleum imports have a significant impact on the U.S. 

economy.

Requiring lower GHG vehicle technology and fuel efficient technology in HD 

vehicles in the U.S. is expected to lower U.S. oil imports. EPA used the MOVES model 

to estimate the fuel savings due to this program. A detailed explanation of the MOVES 

model can be found in Chapter 5 of the RIA.

Based on a detailed analysis of differences in fuel consumption, petroleum 

imports, and imports of refined petroleum products and crude oil using the Reference 

Case presented in the Energy Information Administration’s Annual Energy Outlook 

(AEO) 2011 Early Release, EPA and NHTSA estimate that approximately 50 percent of 

 

531 Source: U.S. Bureau of Economic Analysis, U.S. International Transactions Accounts Data, as shown on 

June 24, 2009.

532 Source: U.S. Department of Energy, Annual Energy Review 2008, Report No. DOE/EIA-0384(2008), 

Tables 5.1 and 5.13c, June 26, 2009.
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the reduction in fuel consumption resulting from adopting improved GHG emissions 

standards and fuel efficiency standards is likely to be reflected in reduced U.S. imports of 

refined fuel, while the remaining 50 percent is expected to be reflected in reduced 

domestic fuel refining. Of this latter figure, 90 percent is anticipated to reduce U.S. 

imports of crude petroleum for use as a refinery feedstock, while the remaining 10 

percent is expected to reduce U.S. domestic production of crude petroleum. Thus, on 

balance, each gallon of fuel saved as a consequence of the HD GHG and fuel efficiency

standards is anticipated to reduce total U.S. imports of petroleum by 0.95 gallons.533 The 

agencies’ estimates of the reduction in U.S. oil imports from this program for selected 

years, in millions of barrels per day, are presented in Table VIII-21 below. These 

estimates assume that the fuel efficiency of HD vehicles remains constant in the baseline. 

Table VIII-21: U.S. Oil Import Reductions from the HD National Program for Selected Years 

(Millions of Barrels per Day, mmbd)

Year mmbd

2020 0.202

2030 0.393

2040 0.489

2050 0.566

(2) Energy Security Implications

In order to understand the energy security implications of reducing U.S. 

petroleum imports, EPA worked with Oak Ridge National Laboratory (ORNL), which 

has developed approaches for evaluating the economic costs and energy security

implications of oil use. The energy security estimates provided below are based upon a 

methodology developed in a peer-reviewed study entitled ”The Energy Security Benefits 

of Reduced Oil Use, 2006-2015,” completed in March 2008. This study is included as 

part of the docket for this final action.

534,535

When conducting this analysis, ORNL considered the full economic cost of 

importing petroleum into the United States. The economic cost of importing petroleum 

into the U.S. is defined to include two components in addition to the purchase price of 

petroleum itself. These are: (1) the higher costs for oil imports resulting from the effect 

of increasing U.S. import demand on the world oil price and on the market power of the 

Organization of the Petroleum Exporting Countries (i.e., the “demand” or “monopsony”

costs); and (2) the risk of reductions in U.S. economic output and disruption of the U.S. 

economy caused by sudden disruptions in the supply of imported petroleum to the U.S. 

(i.e., macroeconomic disruption/adjustment costs). Maintaining a U.S. military presence 

 

533 This figure is calculated as 0.50 + 0.50*0.9 = 0.50 + 0.45 = 0.95.

534 Leiby, Paul N., "Estimating the Energy Security Benefits of Reduced U.S. Oil Imports" Oak Ridge 

National Laboratory, ORNL/TM-2007/028, Final Report, 2008. (Docket EPA-HQ-OAR-2010-0162)

535 The ORNL study “The Energy Security Benefits of Reduced Oil Use, 2006-2015," completed in March

2008, is an update version of the approach used for estimating the energy security benefits of U.S. oil 

import reductions developed in an ORNL 1997 Report by Leiby, Paul N., Donald W. Jones, T. Randall 

Curlee, and Russell Lee, entitled “Oil Imports: An Assessment of Benefits and Costs." (Docket EPA-HQOAR-2010-0162)
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to help secure stable oil supply from potentially vulnerable regions of the world was not 

included in this analysis because its attribution to particular missions or activities is hard 

to quantify.

For this action, ORNL estimated energy security premiums by incorporating the 

most recent available AEO 2011 Early Release oil price forecasts and market trends. 

Energy security premiums for the years 2020, 2030, 2040, and 2050 are presented in 

Table VIII-22, as well as a breakdown of the components of the energy security

premiums for each of these years.536 The components of the energy security premiums

and their values are discussed in detail in Chapter 9.7 of the RIA.

Table VIII-22: Energy Security Premiums in Selected Years (2009$/Barrel)

Year

(range)

Monopsony Macroeconomic 

Disruption/Adjustment Costs

Total Mid-Point

2020 $11.29

($3.86 - $21.32)

$7.11

($3.50 - $11.40)

$18.41

($9.70 - $28.94)

2030 $11.17

($3.92 - $20.58) 

$8.32

($4.04 - $13.33)

$19.49

($10.49 -$29.63)

2035 $10.56

($3.69 - $19.62)

$8.71

($3.86 - $14.35)

$19.27

($10.32 - $29.13)

The literature on the energy security for the last two decades has routinely 

combined the monopsony and the macroeconomic disruption components when 

calculating the total value of the energy security premium. However, in the context of 

using a global SCC value, the question arises: how should the energy security premium 

be determined when a global perspective is taken? Monopsony benefits represent 

avoided payments by the United States to oil producers in foreign countries that result 

from a decrease in the world oil price as the U.S. decreases its consumption of imported 

oil. 

Several commenters commented on the agencies’ energy security analysis of this 

program. The Conservative Law Foundation, Interfaith Care for Creation, Environmental 

Defense Fund and American Lung Association (EDF/ALA) and R. Desjardin noted that 

the standards in this program will increase our national security by decreasing U.S. 

dependence on foreign oil imports. The Competitive Enterprise Institute (CEI) felt that 

there is no relationship between reduced U.S. oil imports and U.S. energy security; the 

commenter sees no relationship between reduced oil imports and, for example, the 

number of hijackings, bombings, and other terrorist-related activities that have occurred 

through time. CBD commented that the benefit of the reduction of military costs 

associated with maintaining a secure oil supply should be fully accounted for, and EDF 

recommended a more extensive analysis of the external security costs of oil dependence. 

The agencies recognize that potential national and energy security risks exist due 

to the possibility of tension over oil supplies. Much of the world’s oil and gas supplies 

 

536 AEO 2011 forecasts energy market trends and values only to 2035. The energy security premium 

estimates post-2035 were assumed to be the 2035 estimate.
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are located in countries facing social, economic, and demographic challenges, thus

making them even more vulnerable to potential local instability. For example, in 2010 

just over 40 percent of world oil supply came from OPEC nations, and this share is not 

expected to decline in the AEO 2011 projections through 2030. Approximately 28

percent of global supply is from Persian Gulf countries alone. As another measure of 

concentration, of the 137 countries/principalities that export either crude oil or refined 

petroleum product, the top 12 have recently accounted for over 55 percent of exports.537 

Eight of these countries are members of OPEC, and a 9th is Russia.538 In a market where 

even a 1-2 percent supply loss raises prices noticeably, and where a 10 percent supply

loss could lead to a significant price shock, this regional concentration is of concern.

Historically, the countries of the Middle East have been the source of eight of the ten

major world oil disruptions539 with the 9th originating in Venezuela, an OPEC member. 

Because of U.S. dependence on oil, the military could be called on to protect 

energy resources through such measures as securing shipping lanes from foreign oil 

fields. To maintain such military effectiveness and flexibility, the Department of Defense 

identified in the Quadrennial Defense Review that it is “increasing its use of renewable 

energy supplies and reducing energy demand to improve operational effectiveness, 

reduce greenhouse gas emissions in support of U.S. climate change initiatives, and 

protect the Department from energy price fluctuations.”540 The Department of the Navy 

has also stated that the Navy and Marine Corps rely far too much on petroleum, which 

“degrades the strategic position of our country and the tactical performance of our forces. 

The global supply of oil is finite, it is becoming increasingly difficult to find and exploit, 

and over time cost continues to rise.”541 

In remarks given to the White House Energy Security Summit on April 26, 2011, 

Deputy Security of Defense William J. Lynn, III noted the direct impact of energy

security on military readiness and flexibility. According to Deputy Security Lynn, 

“Today, energy technology remains a critical element of our military superiority. 

Addressing energy needs must be a fundamental part of our military planning.”542 

Thus, to the degree to which the final rules reduce reliance upon imported energy

supplies or promotes the development of technologies that can be deployed by either 

consumers or the nation’s defense forces, the United States could expect benefits related 

to national security, reduced energy costs, and increased energy supply. These benefits

are why President Obama has identified this program as a key component for improving 

 

537 Based on data from the CIA, combining various recent years, 

https://www.cia.gov/library/publications/the-world-factbook/rankorder/2176rank.html.

538 The other three are Norway, Canada, and the EU, an exporter of product.

539 IEA 2011 “IEA Response System for Oil Supply Emergencies”

540 U.S. Department of Defense. 2010. Quadrennial Defense Review Report. Secretary of Defense: 

Washington, D.C. 128 pages.

541 The Department of the Navy’s Energy Goals (http://www.navy.mil/features/Navy_EnergySecurity.pdf) 

(Last accessed May 31, 2011).

542 U.S. Department of Defense, Speech: Remarks at the White House Energy Security Summit. Tuesday, 

April 26, 2011. (http://www.defense.gov/speeches/speech.aspx?speechid=1556) (Last accessed May 31, 

2011).
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energy efficiency and putting America on a path to reducing oil imports in the Blueprint 

for a Secure Energy Future.543

Although the agencies recognize that there clearly is a benefit to the United States 

from reducing dependence on foreign oil, the agencies have been unable to calculate the 

monetary benefit that the United States will receive from the improvements in national 

security expected to result from this program. In contrast, the other portion of the energy

security premium, the U.S. macroeconomic disruption and adjustment cost that arises 

from U.S. petroleum imports, is included in the energy security benefits estimated for this 

program. To summarize, the agencies have included only the macroeconomic disruption 

portion of the energy security benefits to estimate the monetary value of the total energy

security benefits of this program. The agencies have calculated energy security in very

specific terms, as the reduction of both financial and strategic risks caused by potential 

sudden disruptions in the supply of imported petroleum to the U.S. Reducing the amount 

of oil imported reduces those risks, and thus increases the nation’s energy security. 

Another commenter, citing Administration guidelines (OMB Circular A-4) for 

conducting economic analyses, felt that the agency should include the monopsony benefit 

as part of its overall costs and benefits analysis. After reviewing the guidelines cited by

the commenter, the agencies have concluded that excluding the monopsony benefit from 

its overall costs and benefits analysis continues to be appropriate when a global 

perspective is taken. However, the agencies recognize that the monopsony benefit has 

distributional impacts for the U.S., and continue to describe and discuss the monopsony

benefit in this section of the Preamble.

The total annual energy security benefits for the final HD National Program are 

reported in Table VIII-23 for the years 2020, 2030, 2040 and 2050. 

Table VIII-23: Total Annual Energy Security Benefits from the HD National Program

in 2020, 2030, 2040 and 2050 (Millions, 2009$)

Year Benefits

2020 $499

2030 $1,132

2040 $1,477

2050 $1,710

J. Other Impacts

(1) Noise, Congestion and Accidents

Increased vehicle use associated with a positive rebound effect also contributes to 

increased traffic congestion, motor vehicle accidents, and highway noise. Depending on 

 

543 The White House, Blueprint for a Secure Energy Future (March 30, 2011) 

(http://www.whitehouse.gov/sites/default/files/blueprint_secure_energy_future.pdf) (Last accessed May 27, 

2011).
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how the additional travel is distributed throughout the day and on where it takes place, 

additional vehicle use can contribute to traffic congestion and delays by increasing traffic 

volumes on facilities that are already heavily traveled during peak periods. These added 

delays impose higher costs on drivers and other vehicle occupants in the form of 

increased travel time and operating expenses, increased costs associated with traffic 

accidents, and increased traffic noise. Because drivers do not take these added costs into 

account in deciding when and where to travel, they must be accounted for separately as a 

cost of the added driving associated with the rebound effect.

EPA and NHTSA rely on estimates of congestion, accident, and noise costs 

caused by pickup trucks and vans, single unit trucks, buses, and combination tractors

developed by the Federal Highway Administration to estimate the increased external 

costs caused by added driving due to the rebound effect.544 The Federal Highway

Administration (FHWA) estimates are intended to measure the increases in costs from 

added congestion, property damages and injuries in traffic accidents, and noise levels 

caused by various types of trucks that are borne by persons other than their drivers (or 

“marginal” external costs). EPA and NHTSA employed estimates from this source 

previously in the analysis accompanying the light-Duty 2012-16 MY vehicle rule. The 

agencies continue to find them appropriate for this analysis after reviewing the 

procedures used by FHWA to develop them and considering other available estimates of 

these values. 

FHWA’s congestion cost estimates for trucks, which are weighted averages based 

on the estimated fractions of peak and off-peak freeway travel for each class of trucks, 

already account for the fact that trucks make up a smaller fraction of peak period traffic 

on congested roads because they try to avoid peak periods when possible. FHWA’s 

congestion cost estimates focus on freeways because non-freeway effects are less serious 

due to lower traffic volumes and opportunities to re-route around the congestion. The 

agencies, however, applied the congestion cost to the overall VMT increase, though the 

fraction of VMT on each road type used in MOVES range from 27 to 29 percent of the 

vehicle miles on freeways for vocational vehicles and 53 percent for combination 

tractors. The results of this analysis potentially overestimate the costs and provide a 

conservative estimate. 

The agencies are using FHWA’s “Middle” estimates for marginal congestion, 

accident, and noise costs caused by increased travel from trucks. This approach is 

consistent with the current methodology used in the Light-Duty GHG rulemaking 

analysis. These costs are multiplied by the annual increases in vehicle miles travelled

from the positive rebound effect to yield the estimated cost increases resulting from 

increased congestion, accidents, and noise during each future year. The values the 

agencies used to calculate these increased costs are included in Table VIII-24.

 

544 These estimates were developed by FHWA for use in its 1997 Federal Highway Cost Allocation Study; 

See http://www.fhwa.dot.gov/policy/hcas/final/index.htm (last accessed July 21, 2010).
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Table VIII-24: Noise, Accident, and Congestion Costs per Mile (2009$)

External 

Costs

Pickup Trucks and 

Vans ($/VMT)

Vocational 

Vehicles ($/VMT)

Combination 

Tractors ($/VMT)

Congestion $0.049 $0.111 $0.108

Accidents $0.027 $0.019 $0.022

Noise $0.001 $0.009 $0.020

In aggregate, the increased costs due to noise, accidents, and congestion from the 

additional truck driving are presented in Table VIII-25.

Table VIII-25: Accident, Noise, and Congestion Costs (Millions, 2009$)

Year Pickup Trucks 

and Vans

Vocational

Vehicles

Combination

Tractors

Total Costs

2012 $0 $0 $0 $0

2013 $0 $0 $0 $0

2014 $8 $21 $18 $46

2015 $15 $38 $31 $84

2016 $22 $55 $43 $120

2017 $29 $71 $54 $153

2018 $36 $85 $64 $186

2020 $51 $112 $83 $246

2030 $105 $195 $138 $437

2040 $130 $256 $166 $551

2050 $148 $298 $191 $638

NPV, 3% $1,818 $3,620 $2,492 $7,929

NPV, 7% $832 $1,680 $1,184 $3,695

(2) Savings Due to Reduced Refueling Time

Reducing the fuel consumption of heavy-duty trucks may either increase their 

driving range before they require refueling, or motivate truck purchasers to buy, and 

manufacturers to offer, smaller fuel tanks. Keeping the fuel tank the same size allows 

truck operators to reduce the frequency with which drivers typically refuel their vehicles; 

it thus extends the upper limit of the range they can travel before requiring refueling. 

Alternatively, if purchasers and manufacturers respond to improved fuel efficiency by

reducing the size of fuel tanks to maintain a constant driving range, the smaller tank will 

require less time in actual refueling. 

Because refueling time represents a time cost of truck operation, these time 

savings should be incorporated into truck purchasers’ decisions over how much fuelsaving technology they want in their vehicles. The savings calculated here thus raise the 

same questions discussed in Preamble VIII.A and RIA Section 9.1 does the apparent 

existence of these savings reflect failures in the market for fuel efficiency, or does it 
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reflect costs not addressed in this analysis? The response to these questions could vary

across truck segment. See those sections for further analysis of this question.

This analysis estimates the reduction in the annual time spent filling the fuel tank; 

this reduced time could come either from fewer refueling events, if the fuel tank stays the 

same size, or less time spent during each refueling event, if the fuel tank is made 

proportionately smaller. The refueling savings are calculated as the savings in the 

amount of time that would have been necessary to pump the fuel. The calculation does 

not include time spent searching for a fuel station or other time spent at the station; it is 

assumed that the time savings occur only during refueling. The value of the time saved is 

estimated at the hourly rate recommended for truck operators ($22.36 in 2009 dollars) in 

DOT guidance for valuing time savings.545

The refueling savings include the increased fuel consumption resulting from 

additional mileage associated with the rebound effect. However, the estimate of the 

rebound effect does not account for any reduction in net operating costs from lower 

refueling time. As discussed earlier, the rebound effect should be a measure of the change 

in VMT with respect to the net change in overall operating costs. Ideally, changes in 

refueling time would factor into this calculation, although the effect is expected to be 

minor because refueling time savings are small relative to the value of reduced fuel 

expenditures.

The details of this calculation are discussed in the RIA Chapter 9.3.2. The 

savings associated with reduced refueling time for a truck of each type throughout its 

lifetime are shown in Table VIII-26. The aggregate savings associated with reduced 

refueling time are shown in Table VIII-27 for vehicles sold in 2014 through 2050. 

 

545 U.S. Department of Transportation, “Revised Departmental Guidance for Valuation of Travel Time in 

Economic Analysis,” February 11, 2003, Table 4 (which shows a value of $18.10 in 2000 dollars); 

available at http://ostpxweb.dot.gov/policy/Data/VOTrevision1_2-11-03.pdf (last accessed September 9, 

2010).
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Table VIII-26: Lifetime Refueling Savings for a 2018 MY Truck of Each Type (2009$)

Pickup Trucks 

and Vans

Vocational Vehicles Combination 

Tractor

3% Discount Rate $31 $34 $341

7% Discount Rate $19 $22 $223

Table VIII-27: Annual Refueling Savings (Millions, 2009$) 

Year Pickup Trucks 

and Vans

Vocational 

Vehicles

Combination 

Tractor

Total

2012 $0.0 $0.0 $0.0 $0.0

2013 $0.0 $0.0 $0.0 $0.0

2014 $0.2 $1.4 $8.0 $9.6

2015 $0.5 $2.6 $14.3 $17.3

2016 $1.3 $3.8 $19.6 $24.6

2017 $2.7 $6.2 $26.7 $35.6

2018 $5.2 $8.5 $33.8 $47.5

2020 $10.5 $12.7 $46.2 $69.3

2030 $32.6 $25.8 $82.9 $141

2040 $43.4 $35.1 $100.5 $179

2050 $50.1 $41.3 $116.1 $207

NPV, 3% $541 $468 $1,467 $2,476

NPV, 7% $231 $210 $685 $1,126

K. The Effect of Safety Standards and Voluntary Safety Improvements

on Vehicle Weight

Safety standards developed by NHTSA in previous rulemakings may make 

compliance with the fuel efficiency and CO2 emissions standards more difficult or may

reduce the projected benefits of the program. The primary way that safety regulations 

can impact fuel efficiency and CO2 emissions is through increased vehicle weight, which 

reduces the fuel efficiency (and thus increases the CO2 emissions) of the vehicle. Using 

MY 2010 as a baseline, this section discusses the effects of other government regulations 

on MYs 2014-2016 medium and heavy-duty vehicle fuel efficiency and CO2 emissions. 

At this time, no known safety standards will affect new models in MY 2017 or 2018. 

NHTSA’s estimates are based on cost and weight tear-down studies of a few vehicles and 

cannot possibly cover all the variations in the manufacturers’ fleets. NHTSA also 

requested, and various manufacturers provided, confidential estimates of increases in 

weight resulting from safety improvements. Those increases are shown in subsequent 

tables. 

We have broken down our analysis of the impact of safety standards that might 

affect the MYs 2014-2016 fleets into three parts: 1) those NHTSA final rules with 

known effective dates, 2) proposed rules or soon-to-be proposed rules by NHTSA with or 
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without final effective dates, and 3) currently voluntary safety improvements planned by

the manufacturers. 

(1) Weight Impacts of Required Safety Standards 

NHTSA has undertaken several rulemakings in which several standards would 

become effective for medium- and heavy-duty (MD/HD) vehicles between MY 2014 and 

MY 2016. We will examine the potential impact on MD/HD vehicle weights for MYs

2014-2016 using MY 2010 as a baseline. 

 FMVSS 119, Heavy Truck Tires Endurance and High Speed Tests

 FMVSS 121, Air Brake Systems Stopping Distance 

 FMVSS 214, Motor Coach Lap/Shoulder Belts

 MD/HD Vehicle Electronic Stability Control Systems

(a) FMVSS 119, Heavy Truck Tires Endurance and High Speed Tests

NHTSA tentatively determined that the FMVSS No. 119 performance tests 

developed in 1973 should be updated to reflect the increased operational speeds and 

duration of truck tires in commercial service. A Notice of Proposed Rulemaking (NPRM) 

was issued December 7, 2010 (75 FR 60036). It proposed to increase significantly the 

stringency of the endurance test and to add a new high speed test. The data in the large 

truck crash causation study (LTCCS) that preceded that NPRM found that J and L load 

range tires were having proportionately more problems than the other sizes and the 

agency’s test results indicate that H, J, and L load range tires are more likely to fail the 

proposed requirements among the targeted F, G, H, J and L load range tires.546 To 

address these problems, the H and J load range tires could potentially use improved 

rubber compounds, which would add no weight to the tires, to reduce heat retention and 

improve the durability of the tires. The L load range tires, in contrast, appear to need to 

use high tensile strength steel chords in the tire bead, carcass and belt areas, which would 

enable a weight reduction with no strength penalties. Thus, if the update to FMVSS No. 

119 was finalized, we anticipate no change in weight for H and J load range tires and a 

small reduction in weight for L load range tires. This proposal could become a final rule 

with an effective date of MY 2016.

(b) FMVSS No. 121, Airbrake Systems Stopping Distance

FMVSS No. 121 contains performance and equipment requirements for braking 

systems on vehicles with air brake systems. The most recent major final rule affecting 

FMVSS No. 121 was published on July 27, 2009, and became effective on November 24, 

2009 (MY 2009). The final rule requires the vast majority of new heavy truck tractors 

(approximately 99 percent of the fleet) to achieve a 30 percent reduction in stopping 

distance compared to currently required levels. Three-axle tractors with a gross vehicle 

weight rating (GVWR) of 59,600 pounds or less must meet the reduced stopping distance 

 

546 “Preliminary Regulatory Impact Analysis, FMVSS No. 119, New Pneumatic Tires for Motor Vehicles 

with a GVWR of More Than 4,536 kg (10,000 pounds), June 2010. 
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requirements by August 1, 2011 (MY 2011), while two-axle tractors and tractors with a 

GVWR above 59,600 pounds must meet the reduced stopping distance requirements by 

the later date of August 1, 2013 (MY 2013). NHTSA determined that there are several 

brake systems that can meet the requirements established in the final rule, including

installation of larger S-cam drum brakes or disc brake systems at all positions, or hybrid 

disc and larger rear S-cam drum brake systems. 

According to data provided by a manufacturer (Bendix) in response to the NPRM, 

the heaviest drum brakes weigh more than the lightest disc brakes, while the heaviest disc 

brakes weigh more than the lightest drum brakes. For a three-axle tractor equipped with 

all disc brakes, then, the total weight could increase by 212 pounds or could decrease by

134 pounds compared to an all-drum-braked tractor, depending on which disc or drum 

brakes are used for comparison. The improved brakes may add a small amount of weight 

to the affected vehicles for MYs 2014-2016, resulting in a slight increase in fuel 

consumption. 

(c) FMVSS No. 208, Motor coach Lap/Shoulder Belts

NHTSA is proposing lap/shoulder belts for all motorcoach seats. About 2,000 

motorcoaches are sold per year in the United States. Based on preliminary results from 

the agency’s cost/weight teardown studies of motor coach seats,547 NHTSA estimates that 

the weight added by 3-point lap/shoulder belts ranges from 5.96 to 9.95 pounds per 2-

person seat. This is the weight only of the seat belt assembly itself, and does not include 

changing the design of the seat, reinforcing the floor, walls or other areas of the motor 

coach. Few current production motor coaches have been installed with lap/shoulder belts 

on their seats, and the number of vehicles with these belts already installed could be 

negligible. Assuming a 54 passenger motor coach, the added weight for the 3-point 

lap/shoulder belt assembly would be in the range of 161 to 269 pounds (27 * (5.96 to 

9.95)) per vehicle. This proposal could become a final rule with an effective date of MY

2016. 

(d) Electronic Stability Control Systems (ESC) for Medium- and Heavy-Duty 

(MD/HD) Vehicles

The purpose of an ESC system for MD/HD vehicles is to reduce crashes caused 

by rollover or by directional loss-of-control. ESC monitors a vehicle’s rollover threshold 

and lateral stability using vehicle speed, wheel speed, steering wheel angle, lateral 

acceleration, side slip and yaw rate data and upon sensing an impending rollover or loss 

of directional control situation automatically reduces engine throttle and applies braking 

forces to individual wheels or sets of wheel to slow the vehicle down and regain 

directional control. ESC is not currently required in MD/HD vehicles, but could be 

proposed to be required in these vehicles by NHTSA. FMVSS No. 105, Hydraulic and 

electric brake systems, requires multipurpose passenger vehicles, trucks and buses with a 

GVWR greater than 4,536 kg (10,000 pounds) to be equipped with an antilock brake 

 

547 Cost and Weight Analysis of Two Motorcoach Seating Systems: One With and One Without ThreePoint Lap/Shoulder Belt Restraints, Ludtke and Associates, July 2010.
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system (ABS). All MD/HD vehicles having a GVWR of more than 10,000 pounds, are 

required to have ABS installed by that standard.

In addition to the existing ABS functionality, ESC requires sensors including a 

yaw rate sensor, lateral acceleration sensor, steering angle sensor and brake pressure 

sensor along with a brake solenoid valve. According to data provided by Meritor 

WABCO, the weight of an ESC system for the model 4S4M tractor is estimated to be 

around 55.5 pounds, and the weight of the ABS only is estimated to be 45.5 pounds. 

Thus, we estimate the added weight for the ESC for the vehicle to be 10 (55.5 – 45.5) 

pounds. 

(2) Summary – Overview of Anticipated Weight Increases

Table VIII-28 summarizes estimates made by NHTSA regarding the weight added 

by the above discussed standards or likely rulemakings. NHTSA estimates that weight 

additions required by final rules and likely NHTSA regulations effective in MY 2016 

compared to the MY 2010 fleet will increase motor coach vehicle weight by 171 to 279 

pounds and will increase other heavy-duty truck weights by 10 pounds.

Table VIII-28: Weight Additions Due to Final Rules or Likely NHTSA Regulations: Comparing MY 

2016 to the MY 2010 Baseline Fleet

Standard Number Added Weight in 

pounds

MD/HD Vehicle

Added Weight in 

kilograms

MD/HD Vehicle

119 0 0

121 0 (?) 0 (?)

208

Motor coaches only

161-269 73-122

MD/HD Vehicle Electronic 

Stability Control Systems

10 4.5

Total

Motor coaches

171- 279 77.5-126.5

Total

All other MD/HD vehicles

10 4.5

(3) Effects of Vehicle Mass Reduction on Safety

NHTSA and EPA have been considering the effect of vehicle weight on vehicle 

safety for the past several years in the context of our joint rulemaking for light-duty 

vehicle CAFE and GHG standards, consistent with NHTSA’s long-standing 

consideration of safety effects in setting CAFE standards. Combining all modes of 

impact, the latest analysis by NHTSA for the light-duty 2012-2016 MY vehicle rule548

found that reducing the weight of the heavier light trucks (LT > 3,870) had a positive 

overall effect on safety, reducing societal fatalities. 

 

548 “Final Regulatory Impact Analysis, Corporate Average Fuel Economy for MY 2012 - MY 2016 

Passenger Cars and Light Trucks”, NHTSA, March 2010, (Docket No. NHTSA-2009-0059-0344.1).
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In the context of the current rulemaking for HD fuel consumption and GHG 

standards, one would expect that reducing the weight of medium-duty trucks similarly

would, if anything, have a positive impact on safety. However, given the large difference 

in weight between light-duty vehicles and medium-duty trucks, and even larger 

difference between light-duty vehicles and heavy-duty vehicles with loads, the agencies 

believe that the impact of weight reductions of medium- and heavy-duty trucks would not 

have a noticeable impact on safety for any of these classes of vehicles.

However, the agencies recognize that it is important to conduct further study and 

research into the interaction of mass, size and safety to assist future rulemakings, and we 

expect that the collaborative interagency work currently on-going to address this issue for 

the light-duty vehicle context may also be able to inform our evaluation of safety effects 

for the final HD program. We intend to continue monitoring this issue going forward, 

and may take steps in a future rulemaking if it appears that the MD/HD fuel efficiency

and GHG standards have unforeseen safety consequences. The American Chemistry

Council stated in comments to the agencies that plastics and plastic composite materials 

provide a new way to lighten vehicles while maintaining passenger safety. They added 

that properties of plastics including strength to weight ratio, energy absorption, and 

flexible design make these materials well suited for the manufacture of medium- and 

heavy-duty vehicles. They submitted supporting analyses with their comments. The 

National School Transportation Association stated that added structural integrity 

requirements increase weight of school buses, and thus decrease fuel economy. They

asked that if there are safety and fuel economy trade-offs, manufacturers should be able 

to receive a waiver from the regulation’s requirements. Since no weight reduction is

required for school buses – or any other vocational vehicle – the agencies do not believe 

this is an issue with the current regulation.

L. Summary of Costs and Benefits 

In this section, the agencies present a summary of costs, benefits, and net benefits 

of the HD National program. 

Table VIII-29 shows the estimated annual monetized costs of the final program 

for the indicated calendar years. The table also shows the net present values of those 

costs for the calendar years 2012-2050 using both 3 percent and 7 percent discount 

rates.549 Table VIII-30 shows the estimated annual monetized fuel savings of the final 

program. The table also shows the net present values of those fuel savings for the same 

calendar years using both 3 percent and 7 percent discount rates. In this table, the 

aggregate value of fuel savings is calculated using pre-tax fuel prices since savings in fuel 

taxes do not represent a reduction in the value of economic resources utilized in 

producing and consuming fuel. Note that fuel savings shown here result from reductions 

in fleet-wide fuel use. Thus, they grow over time as an increasing fraction of the fleet 

meets the 2018 standards. 

 

549 For the estimation of the stream of costs and benefits, we assume that after implementation of the final 

MY 2014-2017 standards, the 2017 standards apply to each year out to 2050.
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Table VIII-29: Estimated Monetized Costs of the Final Program (Millions, 2009$ )

a

2020 2030 2040 2050 NPV, Years

2012-2050, 3% 

Discount Rate

NPV, Years

2012-2050, 

7% Discount

Rate

Technolog

y Costs

$2,000 $2,200 $2,700 $3,300 $47,400 $24,700

Note:

a Technology costs for separate truck segments can be found in Section VIII.B.1.

Table VIII-30: Estimated Fuel Savings of the Final Program (Millions, 2009$ )

a

2020 2030 2040 2050 NPV, Years

2012-2050, 3% 

Discount Rate

NPV, Years

2012-2050, 

7% Discount

Rate

Fuel 

Savings 

(pre-tax)

$9,600 $20,600 $28,000 $36,500 $375,300 $166,500

Note:

a

Fuel savings for separate truck segments can be found in Section VIII.B.1.

Table VIII-31 presents estimated annual monetized benefits for the indicated 

calendar years. The table also shows the net present values of those benefits for the 

calendar years 2012-2050 using both 3 percent and 7 percent discount rates. The table 

shows the benefits of reduced CO2 emissions—and consequently the annual quantified 

benefits (i.e., total benefits)—for each of four SCC values estimated by the interagency

working group. As discussed in the RIA Section 9.3, there are some limitations to the 

SCC analysis, including the incomplete way in which the integrated assessment models 

capture catastrophic and non-catastrophic impacts, their incomplete treatment of 

adaptation and technological change, uncertainty in the extrapolation of damages to high 

temperatures, and assumptions regarding risk aversion. 

In addition, these monetized GHG benefits exclude the value of net reductions in 

non-CO2 GHG emissions (CH4, N2O, HFC) expected under this action. Although EPA 

has not monetized the benefits of reductions in non-CO2 GHGs, the value of these 

reductions should not be interpreted as zero. Rather, the net reductions in non-CO2

GHGs will contribute to this program’s climate benefits, as explained in Section VI.C. 
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Table VIII-31: Monetized Benefits Associated with the Final Program (Millions, 2009$)

2020 2030 2040 2050 NPV, Years 

2012-2050, 

3% 

Discount 

Ratea

NPV, Years 

2012-2050, 

7% 

Discount 

Ratea

Reduced CO2 Emissions at each assumed SCC value b

5% (avg SCC) $300 $700 $1,200 $1,700 $9,000 $9,000

3% (avg SCC) $1,000 $2,500 $3,600 $4,800 $46,100 $46,100

2.5% (avg SCC) $1,600 $3,800 $5,400 $7,000 $78,000 $78,000

3% (95th 

percentile)

$3,100 $7,500 $11,100 $14,600 $140,400 $140,400

Energy Security 

Impacts (price 

shock)

$500 $1,100 $1,500 $1,700 $19,800 $8,800

Accidents, 

Congestion, Noisef

-$200 -$400 -$600 -$600 -$7,900 -$3,700

Refueling Savings $100 $100 $200 $200 $2,500 $1,100

Non-GHG Impacts 

c,d

B $2,800 $2,800 $2,800 $25,300 $9,100

Non-CO2 GHG 

Impactse

n/a n/a n/a n/a n/a n/a

Total Annual Benefits at each assumed SCC value b

5% (avg SCC) $700 $4,300 $5,100 $5,800 $48,700 $24,300

3% (avg SCC) $1,400 $6,100 $7,500 $8,900 $85,800 $61,400

2.5% (avg SCC) $2,000 $7,400 $9,300 $11,100 $117,700 $93,300

3% (95th

percentile)

$3,500 $11,100 $15,000 $18,700 $180,100 $155,700

Notes:

a Net present value of reduced CO2 emissions is calculated differently than other benefits. The same 

discount rate used to discount the value of damages from future emissions (SCC at 5, 3, 2.5 percent) is used 

to calculate net present value of SCC for internal consistency. Refer to the SCC TSD for more detail. 

b

Section VIII.G notes that SCC increases over time. Corresponding to the years in this table, the SCC 

estimates range as follows: for Average SCC at 5%: $5-$16; for Average SCC at 3%: $22-$46; for 

Average SCC at 2.5%: $36-$66; and for 95th percentile SCC at 3%: $66-$139. See Section VIII.F.

c Note that “B” indicates unquantified criteria pollutant benefits in the year 2020. For the analysis of the 

final program, we only modeled the rule’s PM2.5- and ozone-related impacts in the calendar year 2030. For 

the purposes of estimating a stream of future-year criteria pollutant benefits, we assume that the benefits 

out to 2050 are equal to, and no less than, those modeled in 2030 as reflected by the stream of estimated 

future emission reductions. The NPV of criteria pollutant-related benefits should therefore be considered a 

conservative estimate of the potential benefits associated with the final program.

d Non-GHG-related health and welfare impacts (related to PM2.5 and ozone exposure) range between $1,300 

and $4,200 million in 2030, 2040, and 2050. $2,800 was chosen as the mid-point of this range for the 

purposes of estimating total benefits across all monetized categories.

e The monetized GHG benefits presented in this analysis exclude the value of changes in non-CO2 GHG 

emissions expected under this program (See RIA Chapter 5). Although EPA has not monetized changes in 

non-CO2 GHGs, the value of any increases or reductions should not be interpreted as zero. 

f Negative sign represents an increase in Accidents, Congestion, and Noise.
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Table VIII-32 presents estimated annual net benefits for the indicated calendar 

years. The table also shows the net present values of those net benefits for the calendar 

years 2012-2050 using both 3 percent and 7 percent discount rates. The table includes 

the benefits of reduced CO2 emissions (and consequently the annual net benefits) for each 

of four SCC values considered by EPA. 

Table VIII-32: Monetized Net Benefits Associated with the Final Program (Millions, 2009$)

2020 2030 2040 2050 NPV, 3%a NPV, 7%a

Technology

Costs

$2,000 $2,200 $2,700 $3,300 $47,400 $24,700

Fuel Savings $9,600 $20,600 $28,000 $36,500 $375,300 $166,500

Total Annual Benefits at each assumed SCC value b

5% (avg SCC) $700 $4,300 $5,100 $5,800 $48,700 $24,300

3% (avg SCC) $1,400 $6,100 $7,500 $8,900 $85,800 $61,400

2.5% (avg SCC) $2,000 $7,400 $9,300 $11,100 $117,700 $93,300

3% (95th 

percentile)

$3,500 $11,100 $15,000 $18,700 $180,100 $155,700

Monetized Net Benefits at each assumed SCC value c

5% (avg SCC) $8,300 $22,700 $30,400 $39,000 $376,600 $166,100

3% (avg SCC) $9,000 $24,500 $32,800 $42,100 $413,700 $203,200

2.5% (avg SCC) $9,600 $25,800 $34,600 $44,300 $445,600 $235,100

3% (95th 

percentile)

$11,100 $29,500 $40,300 $51,900 $508,000 $297,500

Notes: 

a Net present value of reduced CO2 emissions is calculated differently than other benefits. The same 

discount rate used to discount the value of damages from future emissions (SCC at 5, 3, 2.5 percent) is used 

to calculate net present value of SCC for internal consistency. Refer to the SCC TSD for more detail.

b

Section VIII.G notes that SCC increases over time. Corresponding to the years in this table, the SCC 

estimates range as follows: for Average SCC at 5%: $5-$16; for Average SCC at 3%: $22-$46; for 

Average SCC at 2.5%: $36-$66; and for 95th percentile SCC at 3%: $66-$139. Section VIII.G also 

presents these SCC estimates.

c Net Benefits equal Fuel Savings minus Technology Costs plus Benefits.

EPA also conducted a separate analysis of the total benefits over the model year 

lifetimes of the 2014 through 2018 model year trucks. In contrast to the calendar year 

analysis presented above in Table VIII-29 through Table VIII-32, the model year lifetime 

analysis below shows the impacts of the final program on vehicles produced during each 

of the model years 2014 through 2018 over the course of their expected lifetimes. The 

net societal benefits over the full lifetimes of vehicles produced during each of the five 

model years from 2014 through 2018 are shown in Table VIII-33 and Table VIII-34 at 

both 3 percent and 7 percent discount rates, respectively. 
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Table VIII-33: Monetized Technology Costs, Fuel Savings, Benefits, and Net Benefits Associated with 

the Lifetimes of 2014-2018 Model Year Trucks (Millions, 2009$; 3% Discount Rate)

2014

MY

2015

MY

2016

MY

2017

MY

2018

MY

Sum

Technology Costs $1,600 $1,400 $1,500 $1,600 $2,000 $8,100

Fuel Savings (pre-tax) $9,300 $8,300 $8,100 $11,500 $12,900 $50,100

Energy Security 

Impacts (price shock)

$500 $400 $400 $600 $700 $2,700

Accidents, 

Congestion, Noise e

-$300 -$300 -$300 -$300 -$300 -$1,500

Refueling Savings $60 $60 $60 $80 $100 $400

Non-CO2 GHG 

Impacts and NonGHG Impacts c,d

n/a n/a n/a n/a n/a n/a

Reduced CO2 Emissions at each assumed SCC value a, b

5% (avg SCC) $200 $200 $200 $300 $300 $1,200

3% (avg SCC) $1,100 $900 $900 $1,300 $1,500 $5,700

2.5% (avg SCC) $1,800 $1,600 $1,500 $2,100 $2,400 $9,400

3% (95th percentile) $3,300 $2,900 $2,800 $4,000 $4,500 $17,000

Monetized Net Benefits at each assumed SCC value a, b

5% (avg SCC) $8,200 $7,300 $7,000 $10,600 $11,700 $44,800

3% (avg SCC) $9,100 $8,000 $7,700 $11,600 $12,900 $49,300

2.5% (avg SCC) $9,800 $8,700 $8,300 $12,400 $13,800 $53,000

3% (95th percentile) $11,300 $10,000 $9,600 $14,300 $15,900 $60,600

Notes: 

a Net present value of reduced CO2 emissions is calculated differently than other benefits. The same 

discount rate used to discount the value of damages from future emissions (SCC at 5, 3, 2.5 percent) is used 

to calculate net present value of SCC for internal consistency. Refer to the SCC TSD for more detail. 

b

Section VIII.G notes that SCC increases over time. Corresponding to the years in this table, the SCC 

estimates range as follows: for Average SCC at 5%: $5-$16; for Average SCC at 3%: $22-$46; for 

Average SCC at 2.5%: $36-$66; and for 95th percentile SCC at 3%: $66-$139. Section VIII.G also 

presents these SCC estimates.

c The monetized GHG benefits presented in this analysis exclude the value of changes in non-CO2 GHG 

emissions expected under this action (See RIA Chapter 5). Although EPA has not monetized changes in 

non-CO2 GHGs, the value of any increases or reductions should not be interpreted as zero. 

d Due to analytical and resource limitations, MY non-GHG emissions (direct PM, VOCs, NO2 and SO2) 

were not estimated for this analysis.

e

 Negative sign represents an increase in Accidents, Congestion, and Noise.
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Table VIII-34: Monetized Technology Costs, Fuel Savings, Benefits, and Net Benefits Associated with 

the Lifetimes of 2014-2018 Model Year Trucks (Millions, 2009$; 7% Discount Rate)

2014 

MY

2015 

MY

2016 

MY

2017 

MY

2018 

MY

Sum

Technology Costs $1,600 $1,400 $1,500 $1,600 $2,000 $8,100

Fuel Savings (pre-tax) $6,900 $5,900 $5,600 $7,600 $8,300 $34,400

Energy Security Impacts 

(price shock)

$400 $300 $300 $400 $400 $1,800

Accidents, Congestion, 

Noise e

-$200 -$200 -$200 -$200 -$200 -$1,000

Refueling Savings $50 $40 $40 $60 $60 $200

Non-CO2 GHG Impacts and 

Non-GHG Impacts c,d

n/a n/a n/a n/a n/a n/a

Reduced CO2 Emissions at each assumed SCC value a, b

5% (avg SCC) $200 $200 $200 $300 $300 $1,200

3% (avg SCC) $1,100 $900 $900 $1,300 $1,500 $5,700

2.5% (avg SCC) $1,800 $1,600 $1,500 $2,100 $2,400 $9,400

3% (95th percentile) $3,300 $2,900 $2,800 $4,000 $4,500 $17,000

Monetized Net Benefits at each assumed SCC value a, b

5% (avg SCC) $5,800 $4,800 $4,400 $6,600 $6,900 $28,500

3% (avg SCC) $6,700 $5,500 $5,100 $7,600 $8,100 $33,000

2.5% (avg SCC) $7,400 $6,200 $5,700 $8,400 $9,000 $36,700

3% (95th percentile) $8,900 $7,500 $7,000 $10,300 $11,100 $44,300

Notes: 

a Net present value of reduced CO2 emissions is calculated differently than other benefits. The same 

discount rate used to discount the value of damages from future emissions (SCC at 5, 3, 2.5 percent) is used 

to calculate net present value of SCC for internal consistency. Refer to the SCC TSD for more detail. 

b

Section VIII.G notes that SCC increases over time. Corresponding to the years in this table, the SCC 

estimates range as follows: for Average SCC at 5%: $5-$16; for Average SCC at 3%: $22-$46; for 

Average SCC at 2.5%: $36-$66; and for 95th percentile SCC at 3%: $66-$139. Section VIII.G also 

presents these SCC estimates.

c The monetized GHG benefits presented in this analysis exclude the value of changes in non-CO2 GHG 

emissions expected under this action (See RIA Chapter 5). Although EPA has not monetized changes in 

non-CO2 GHGs, the value of any increases or reductions should not be interpreted as zero. 

d Due to analytical and resource limitations, MY non-GHG emissions (direct PM, VOCs, NO2 and SO2) 

were not estimated for this analysis.

e

 Negative sign represents an increase in Accidents, Congestion, and Noise.

Table VIII-35 and Table VIII-36 show similar model year estimates to those 

provided above in Table VIII-33 and Table VIII-34, but reflect specific differences in the 

NHTSA HD program over the 3 mandatory model years of that program. These include 

no HD diesel engine impacts prior to MY 2017, assumption of the NHTSA phase-in 

schedule for HD pickup trucks and vans which achieves 3 year phase-in stability (67%-

67%-67%-100% in MY 2016-2019 respectively), the inclusion of combination tractors 

from MY 2016 forward, and the exclusion of RVs, which are not regulated by NHTSA.
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Table VIII-35: Monetized Technology Costs, Fuel Savings, Benefits, and Net Benefits Associated with 

the Lifetimes of 2016-2018 Model Year Trucks (Millions, 2009$; 3% Discount Rate)

2016 MY 2017 MY 2018 MY Sum

Technology Costs $1,500 $1,600 $1,700 $5,200

Fuel Savings (pre-tax) $5,500 $10,900 $11,500 $27,900

Energy Security Impacts (price 

shock)

$300 $600 $600 $1,500

Accidents, Congestion, Noise e-$300 -$300 -$300 -$900

Refueling Savings $40 $80 $80 $200

Non-CO2 GHG Impacts and NonGHG Impacts c,dn/a n/a n/a n/a

Reduced CO2 Emissions at each assumed SCC value a, b

5% (avg SCC) $100 $300 $300 $700

3% (avg SCC) $600 $1,200 $1,300 $3,100

2.5% (avg SCC) $1,000 $2,000 $2,200 $5,200

3% (95th percentile) $1,900 $3,800 $4,000 $9,700

Monetized Net Benefits at each assumed SCC value a, b

5% (avg SCC) $4,100 $10,000 $10,500 $24,200

3% (avg SCC) $4,600 $10,900 $11,500 $26,600

2.5% (avg SCC) $5,000 $11,700 $12,400 $28,700

3% (95th percentile) $5,900 $13,500 $14,200 $33,200

Notes: 

a Net present value of reduced CO2 emissions is calculated differently than other benefits. The same 

discount rate used to discount the value of damages from future emissions (SCC at 5, 3, 2.5 percent) is used 

to calculate net present value of SCC for internal consistency. Refer to the SCC TSD for more detail. 

b

Section VIII.G notes that SCC increases over time. Corresponding to the years in this table, the SCC 

estimates range as follows: for Average SCC at 5%: $5-$16; for Average SCC at 3%: $22-$46; for 

Average SCC at 2.5%: $36-$66; and for 95th percentile SCC at 3%: $66-$139. Section VIII.G also 

presents these SCC estimates.

c The monetized GHG benefits presented in this analysis exclude the value of changes in non-CO2 GHG 

emissions expected under this program (See RIA Chapter 5). Although EPA has not monetized changes in 

non-CO2 GHGs, the value of any increases or reductions should not be interpreted as zero. 

d Due to analytical and resource limitations, MY non-GHG emissions (direct PM, VOCs, NO2 and SO2) 

were not estimated for this analysis.

e

 Negative sign represents an increase in Accidents, Congestion, and Noise.

Table VIII-36: Monetized Technology Costs, Fuel Savings, Benefits, and Net Benefits Associated with 

the Lifetimes of 2016-2018 Model Year Trucks (Millions, 2009$; 7% Discount Rate)

2016 MY 2017 MY 2018 MY Sum

Technology Costs $1,500 $1,600 $1,700 $5,200

Fuel Savings (pre-tax) $3,800 $7,200 $7,300 $18,300

Energy Security Impacts (price 

shock)

$200 $400 $400 $1,000

Accidents, Congestion, Noise e-$200 -$200 -$200 -$600
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Refueling Savings $30 $50 $50 $130

Non-CO2 GHG Impacts and 

Non-GHG Impacts c,d

n/a n/a n/a n/a

Reduced CO2 Emissions at each assumed SCC value a, b

5% (avg SCC) $100 $300 $300 $700

3% (avg SCC) $600 $1,200 $1,300 $3,100

2.5% (avg SCC) $1,000 $2,000 $2,200 $5,200

3% (95th percentile) $1,900 $3,800 $4,000 $9,700

Monetized Net Benefits at each assumed SCC value a, b

5% (avg SCC) $2,400 $6,200 $6,200 $14,300

3% (avg SCC) $2,900 $7,100 $7,200 $16,700

2.5% (avg SCC) $3,300 $7,900 $8,100 $18,800

3% (95th percentile) $4,200 $9,700 $9,900 $23,300

Notes: 

a Net present value of reduced CO2 emissions is calculated differently than other benefits. The same 

discount rate used to discount the value of damages from future emissions (SCC at 5, 3, 2.5 percent) is used 

to calculate net present value of SCC for internal consistency. Refer to the SCC TSD for more detail. 

b

Section VIII.G notes that SCC increases over time. Corresponding to the years in this table, the SCC 

estimates range as follows: for Average SCC at 5%: $5-$16; for Average SCC at 3%: $22-$46; for 

Average SCC at 2.5%: $36-$66; and for 95th percentile SCC at 3%: $66-$139. Section VIII.G also 

presents these SCC estimates.

c The monetized GHG benefits presented in this analysis exclude the value of changes in non-CO2 GHG 

emissions expected under this program (See RIA Chapter 5). Although EPA has not monetized changes in 

non-CO2 GHGs, the value of any increases or reductions should not be interpreted as zero.

d Due to analytical and resource limitations, MY non-GHG emissions (direct PM, VOCs, NO2 and SO2) 

were not estimated for this analysis.

e Negative sign represents an increase in Accidents, Congestion, and Noise.

M. Employment Impacts

(1) Introduction

Although analysis of employment impacts is not part of a cost-benefit analysis 

(except to the extent that labor costs contribute to costs), employment impacts of federal 

rules are of particular concern in the current economic climate of sizeable unemployment. 

The recently issued Executive Order 13563, “Improving Regulation and Regulatory 

Review” (January 18, 2011), states, “Our regulatory system must protect public health, 

welfare, safety, and our environment while promoting economic growth, innovation, 

competitiveness, and job creation” (emphasis added). Although EPA and NHTSA did 

not undertake an employment analysis of the proposed rules, several commenters 

suggested that we undertake an employment analysis for the final rulemaking. Consistent 

with Executive order 13563, we have provided a discussion of the potential employment 

impacts of the Heavy-Duty National Program. 

Our general conclusion is that employment impacts in the regulated sector (truck 

and engine manufacturing) and the parts sectors depend on a combination of factors, 

some of which are positive, and some of which can be positive or negative; effects on

employment in the transport and shipping sectors are ambiguous; the fuel supplying 
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sectors may face reduced employment; and there may be increased general employment 

due to reduction in costs that may be passed along to the transport industry and thus to 

the public. Because measuring employment effects depends on a variety of inputs and 

assumptions, some of which are known with more certainty than others, and because we 

did not include an employment analysis in the NPRM and provide opportunity for public 

comment on the methods, we here present a qualitative discussion. Because the 

discussion is qualitative, we do not sum the net effects on employment in the economy. 

We also note that the employment effects may be different in the immediate 

implementation phase than in the ongoing compliance phase; this analysis focuses on the 

longer-term effects rather than the immediate effects.

When the economy is at full employment, an environmental regulation is unlikely 

to have much impact on net overall U.S. employment; instead, labor would primarily be 

shifted from one sector to another. These shifts in employment impose an opportunity

cost on society, approximated by the wages of the employees, as regulation diverts 

workers from other activities in the economy.

550

 In this situation, any effects on net 

employment are likely to be transitory as workers change jobs. (For example, some 

workers may need to be retrained or require time to search for new jobs, while shortages 

in some sectors or regions could bid up wages to attract workers).551

It is also true that, if a regulation comes into effect during a period of high 

unemployment, a change in labor demand due to regulation may affect net overall U.S. 

employment because the labor market is not in equilibrium. Either negative or positive 

effects are possible. Schmalansee and Stavins552 point out that net positive employment 

effects are possible in the near term when the economy is at less than full employment 

due to the potential hiring of idle labor resources by the regulated sector to meet new 

requirements (e.g., to install new equipment) and new economic activity in sectors related 

to the regulated sector. In the longer run, the net effect on employment is more difficult to 

predict and will depend on the way in which the related industries respond to the 

regulatory requirements. As Schmalansee and Stavins note, it is possible that the 

magnitude of the effect on employment could vary over time, region, and sector, and 

positive effects on employment in some regions or sectors could be offset by negative 

effects in other regions or sectors. For this reason, they urge caution in reporting partial 

employment effects since it can “paint an inaccurate picture of net employment impacts if 

not placed in the broader economic context.” 

This rulemaking is expected to have a relatively small effect on net employment 

in the United States through the regulated sector – the truck and engine manufacturer 

industry – and several related sectors, specifically, industries that supply the truck and 

engine manufacturing industry (e.g., truck parts), the trucking industry itself, other 

industries involved in transporting goods (e.g., rail and shipping), the petroleum refining 

 

550 Schmalensee, Richard, and Robert N. Stavins. “A Guide to Economic and Policy Analysis of EPA’s 

Transport Rule.” White paper commissioned by Excelon Corporation, March 2011.

551 Although the employment level would not change substantially, there would be costs to the workers 

associated with shifting from one activity to another. Jacobson, Louis S., Robert J. LaLonde, and Daniel G. 

Sullivan, “Earnings Losses of Displaced Workers.” American Economic Review 83(4) (1993): 685-709.

552 Ibid.
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sector, and the retail sector. According to the U.S. Bureau of Labor Statistics, about 1.25 

million people were employed in the truck transportation industry and about 675,000 

people were employed in the motor vehicle parts industry between 2010 and 2011.553 

Although heavy-duty vehicles (HD) account for approximately 4% of the vehicles on the 

road, these vehicles consume more than 20% of on-road gasoline and diesel fuel use. As 

discussed in Chapter 5 of the RIA, this rulemaking is predicted to reduce the amount of 

fuel these vehicles use, and thus affect the petroleum refinery industry. The petroleum 

refinery industry employed about 65,000 people in the U.S. in 2009, the most recent year 

that employment estimates are available for this sector.554 Finally, since the net reduction 

in cost associated with these rules is expected to lead to lower transportation and shipping 

costs, in a competitive market a substantial portion of those cost savings will be passed 

along to consumers, who then will have additional discretionary income (how much of 

the cost is passed along to consumers depends on market structure and the relative price 

elasticities). 

Several commenters suggested that the HD vehicle rules would lead to an increase 

in employment in affected sectors by offering the potential for new employment 

opportunities in the design and production of new vehicle technologies. Also, these 

commenters suggested that since the U.S. manufacturers and suppliers are leaders in 

certain advanced truck technologies, this program has the potential to help them 

consolidate their leadership and thrive in a global market. In this context, several 

commenters referred to an assessment by the Union of Concerned Scientists (UCS) and 

CalStart of the economic and employment benefits of the improved efficiency in HD 

vehicles.555 The study predicts an increase in tens of thousands of jobs between 2020 and 

2030, as result of higher fuel efficiency for HD vehicles.

While the commenters find unambiguous employment increases as a result of this 

program, we find employment impacts to involve some complexity, as the discussion that 

follows shows. In addition, these quantitative estimates were derived using a standard 

input-output model, though the estimates themselves have not yet been peer reviewed. 

Input-output (I/O) models do not account for opportunity costs of labor – that is, all 

employment needs due to the regulatory change will be met by unemployed workers. In 

addition, I/O models assume no changes in the average use of labor per dollar of output 

in the affected sectors. For these and other reasons, these may at best be considered an 

imprecise upper bound on actual employment impacts.556

Determining the direction of employment effects even in the regulated industry

may be difficult due to the presence of competing effects that lead to an ambiguous 

adjustment in employment as a result of environmental regulation. Morgenstern, Pizer 

 

553 U.S. Bureau of Labor Statistics seasonally-adjusted Current Employment Statistics Survey for the Truck 

Transportation Industry (NAICS 484) and the Motor Vehicle Parts Manufacturing Industry (NAICS 3363).

554 U.S. Census Bureau, 2009 Annual Survey of Manufactures, Published December 3, 2010.

555 Union of Concerned Scientists and CalStart, Delivering Jobs: The Economic Costs and Benefits of 

Improving Fuel Economy of Heavy Duty Vehicles, July, 2010. http://www.ucsusa.org/deliveringjobs.

556 Berck, Peter, and Sandra Hoffman. “Assessing the Employment Impacts of Environmental and Natural 

Resource Policy.” Environmental and Resource Economics 22 (2002): 133-156.
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and Shih557 identify three separate ways that employment levels may change in the 

regulated industry in response to a new (or more stringent) regulation. 

 Demand effect: higher production costs due to the regulation will lead to 

higher market prices; higher prices in turn reduce demand for the good, 

reducing the demand for labor to make that good. In the authors’ words, 

the “extent of this effect depends on the cost increase passed on to 

consumers as well as the demand elasticity of industry output”. 

 Cost effect: As costs go up, plants add more capital and labor (holding 

other factors constant), with potentially positive effects on employment; in 

the authors’ words, as “production costs rise, more inputs, including labor, 

are used to produce the same amount of output”. 

 Factor-shift effect: post-regulation production technologies may be more 

or less labor-intensive (i.e., more/less labor is required per dollar of 

output) (“factor-shift effect”). In the authors’ words, “environmental 

activities may be more labor intensive than conventional production,” 

meaning that “the amount of labor per dollar of output will rise,” though it

is also possible that “cleaner operations could involve automation and less 

employment, for example”.

The “demand effect” is expected to have a negative effect on employment, the “cost 

effect” to have a positive effect on employment, and the “factor-shift effect” has an 

ambiguous effect on employment. Without more information with respect to the 

magnitudes of these competing effects, it is not possible to predict the total effect 

environmental regulation will have on employment levels in a regulated sector

Morgenstern et al. estimated the effects on employment of spending on pollution 

abatement for four highly polluting/regulated industries (pulp and paper, plastics, steel, 

and petroleum refining). They conclude that increased abatement expenditures generally 

have not caused a significant change in employment in those sectors. More specifically, 

their results show that, on average across the industries studied, each additional $1 

million spent on pollution abatement results in a (statistically insignificant) net increase 

of 1.5 jobs. While the specific sectors Morgenstern et al. examined are different that the 

sectors considered here, the methodology that Morgenstern et al. developed is still useful 

in this context.

(2) Overview of Affected Sectors

The above discussion focuses on employment changes in the regulated sector, but 

the regulated sector is not the only source of changes in employment. In these rules, the 

regulated sectors are truck and engine manufacturers; they are responsible for meeting the 

standards set in these rules. The effects of these rules are also likely to have impacts 

beyond the directly regulated sector. Some of the related sectors which these rules are 

 

557 Morgenstern, Richard D., William A. Pizer, and Jhih-Shyang Shih. “Jobs Versus the Environment: An 

Industry-Level Perspective.” Journal of Environmental Economics and Management 43 (2002): 412-436.
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also likely to impact include: motor vehicle parts producers, to the extent that the truck 

and engine industries purchase components rather than manufacture them in-house; 

shipping and transport, because many companies in this sector purchase trucks and their 

operating costs will be affected by both higher truck prices and fuel savings; oil refineries 

due to reduced demand for petroleum-based fuels; and the final retail market, which is 

where any net cost reductions due to fuel savings are ultimately expected to be 

experienced. We acknowledge that there may be impacts in other sectors that are not 

discussed here, but we have sought to include the sectors where we think the impacts are 

most direct. The following discussion describes the direction of impacts on employment 

in these industries. The effects of the HD National Program on net U.S. employment 

depend, not only on their relative magnitudes, but also on employment levels in the 

overall economy. As previously discussed, in a full-employment economy these sectorspecific impacts will be mostly offset by employment changes elsewhere in the economy 

and would not be expected to result in a net change in jobs. However, in an economy 

with significant unemployment these changes may affect net employment in the U.S.

(a) Truck and Engine Manufacturers

The regulated sector consists of truck and engine manufacturers. Employment 

associated with manufacturing trucks and engines may be affected by the demand, cost, 

and factor-shift effects. 

Demand Effect

The demand effect depends on the effects of this rulemaking on HD vehicle sales. 

If vehicle sales increase, then more people will be required to assemble trucks and their 

components. If vehicle sales decrease, employment associated with these activities will 

unambiguously decrease. The effects of this rulemaking on HD vehicle sales depend on 

the perceived desirability of the new vehicles. Unlike in Morgenstern et al.’s study, 

where the demand effect decreased employment, there are countervailing possibilities in 

the HD market due to the fuel savings resulting from this program. On one hand, this 

rulemaking will increase vehicle costs; by itself, this effect would reduce vehicle sales. 

In addition, while decreases in vehicle performance would also decrease sales, this 

program is not expected to have any negative effect on vehicle performance. On the 

other hand, this rulemaking will reduce the fuel costs of operating the vehicle; by itself, 

this effect would increase vehicle sales, especially if potential buyers have an expectation 

of higher fuel prices. The agencies have not made an estimate of the potential change in 

vehicle sales. However as discussed in Preamble Section VIII.E.5 the agencies have 

estimated an increase in vehicle miles traveled (i.e., VMT rebound) due to the reduced 

operating costs of trucks meeting these new standards. Since increased VMT is most 

likely to be met with more drivers and more trucks, our projection of VMT rebound is 

suggestive of an increase in vehicle sales and truck driver employment (recognizing that 

these increases may be partially offset by a decrease in manufacturing and sales for 

equipment of other modes of transportation such as rail cars or barges). 

As discussed above in Section VIII.A, the agencies find that the reduction in fuel 

costs associated with this rulemaking outweigh the increase in vehicle cost. This finding 
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is puzzling: market forces should lead truck manufacturers and buyers to install all costeffective fuel-saving technology, but the agencies find that they have not. Section VIII.A 

discusses various hypotheses that have been suggested to explain this phenomenon. 

Some of the explanations suggest that vehicle manufacturers and buyers will benefit from 

the rulemaking, and vehicle sales will increase; others suggest that the opposite might 

occur. The agencies do not have strong evidence supporting one specific explanation 

over another. However, some in the heavy-duty industry indicate the potential for an 

increase in jobs. As stated by Tom Linebarger (President and Chief Operating Officer of 

Cummins) and Fred Krupp (President of the Environmental Defense Fund), “Finally, 

strong environmental standards play a crucial role in getting innovations to market that 

will create economic opportunity for American companies and jobs for American 

workers. . . . It helps that Cummins and other forward-thinking businesses view this as an 

opportunity to innovate and increase international market share.”

558

One commenter raised the issue of whether there could be a loss of recreation 

vehicle (RV) industry jobs due to a reduction in the sales of motor homes and towable 

RVs. As mentioned above, the effects of this rulemaking on HD vehicle sales depend on 

the desirability of the new vehicles. 

Cost Effect

The truck and engine manufacturing sector has great flexibility in how to respond 

to the requirement for reduced greenhouse gases and increasing fuel efficiency, with a 

broad suite of technologies being available to achieve the standards. These technologies 

are described in detail in Chapter 2 of the RIA. Among these technologies, a distinction 

can be made between technologies that can be “added on” to conventional trucks versus 

those that replace features of a conventional truck. “Added on” features, such as 

auxiliary power units, require additional labor to install the technologies on trucks, thus 

clearly increasing labor demand (the “cost effect”). The pure cost effect always increases 

employment, though the net effect on the regulated industry depends on its effects in 

combination with the demand and factor-shift effects.

Factor-Shift Effect

For “replacement” technologies, the predicted impact on labor demand from 

regulation depends on the change in the amount of labor used to build and install one type 

of technology compared to another. In some cases, the new technologies are predicted to 

be more complex than the existing technologies and may therefore require additional 

labor installation inputs. In other cases, the opposite may be true: labor intensity may be

lower for some replacement technologies.

Most of the technologies that are expected to be used to meet these standards are 

replacement technologies. For example, almost all of the engine improvements involve 

 

558 Tom Linebarger (President and Chief Operating Officer of Cummins) and Fred Krupp (President of the 

Environmental Defense Fund), "Clear rules can create better engines, clean air," Indianapolis Star, October 

28, 2010, p. 19; included as part of Cummins' comments on the rule, Docket Number EPA-HQ-OAR-2010-

0162-1765.1[1]
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replacement technologies that are not expected to significantly change the labor 

requirements. Similarly, regulations of the chassis on vocational vehicles will only

require the installation of a different type of tire, which is also not expected to have large 

labor intensity impacts. Therefore, the potential magnitude of the factor shift effect is 

expected to be relatively small, though slightly positive due to the additional labor needed 

to install more complex technologies. 

Summary for the Truck and Engine Manufacturing Sector

For the truck and engine manufacturing sector, the demand effect may result in 

either increased or decreased employment; the cost effect is expected to increase 

employment; and the factor-shift effect is expected to have a small, possibly slightly

positive effect on employment in this sector. The net effect on employment in this sector 

depends on the sum of these factors.

(b) Motor Vehicle Parts Manufacturing Sector

Some vehicle parts are made in-house and would be included directly in the 

regulated sector. Others are made by independent suppliers and are not directly

regulated, but they will be affected by the rules as well. The parts manufacturing sector 

will be involved primarily in providing “add-on” parts, or components for replacement 

parts built internally. If demand for these parts increases due to the increased use of these 

parts, employment effects in this sector are expected to be positive. If the demand effect 

in the regulated sectors is significantly negative enough, it is possible that demand for 

other parts may decrease. As noted, the agencies do not predict a direction for the 

demand effect.

(c) Transport and Shipping Sectors

Although not directly regulated by these rules, employment effects in the 

transport and shipping sector are likely to result from these regulations. If the overall 

cost of shipping a ton of freight decreases because of increased fuel efficiency (taking 

into account the increase in upfront purchasing costs), in a perfectly competitive industry

these costs savings will be passed along to customers. With lower prices, demand for 

shipping would lead to an increase in demand for truck shipping services (consistent with 

the VMT rebound effect analysis) and therefore an increase in employment in the truck 

shipping sector. In addition, if the relative cost of shipping freight via trucks becomes 

cheaper than shipping by other modes (e.g., rail or barge), then employment in the truck 

transport industry is likely to increase. If the trucking industry is more labor intensive 

than other modes, we would expect this effect to lead to an overall increase in 

employment in the transport and shipping sectors.559,560 Such a shift would, however, be 

at the expense of employment in the sectors that are losing business to trucking. The first 

 

559 American Transportation Research Institute, “An Analysis of the Operational Costs of Trucking: 2011 

Update.” See http://www.atrionline.org/research/results/Op_Costs_2011_Update_one_page_summary.pdf.

560 Association of American Railroads, “All Inclusive Index and Rail Adjustment Factor.” June 3, 2011. 

See http://www.aar.org/~/media/aar/RailCostIndexes/AAR-RCAF-2011-Q3.ashx
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effect – a gain due to lower shipping costs – is likely to lead to a net increase in 

employment. The second effect, due to mode-shifting, may increase employment in 

trucking, but decreases in other shipping sectors.

(d) Fuel Suppliers

In addition to the effects on the trucking industry and related truck parts sector, 

these rules will result in reductions in fuel use that lower GHG emissions. Fuel saving, 

principally reductions in liquid fuels such as diesel and gasoline, will affect employment 

in the fuel suppliers industry sectors, principally the Petroleum Refinery sector.561 

Expected fuel consumption reductions by fuel type, and by heavy-duty vehicle 

type, can be found in Table VIII-7. These reductions reflect impacts from the new fuel 

efficiency and GHG standards and include increased consumption from the rebound 

effect. These fuel savings are monetized in Table VIII-8 by multiplying the reduced fuel 

consumption in each year by the corresponding estimated average fuel price in that year, 

using the Reference Case from the AEO 2011. In 2014, the pre-tax fuel savings is $1.2 

billion (2009$). While these figures represent a level of fuel savings for purchasers of 

fuel, it also represents a loss in value of output for the petroleum refinery industry. Since 

50 percent of the fuel would have been refined in the U.S., the loss in output to the U.S. 

Petroleum Refinery sector is $600 million (2009$), which will result in reduced sectoral 

employment.562 Because this sector is very capital-intensive, the employment effect is 

not expected to be large.

(e) Fuel Savings

As a result of this rulemaking, it is anticipated that trucking firms will experience 

fuel savings. Fuel savings lower the costs of transportation goods and services. In a 

competitive market, the fuel savings that initially accrue to trucking firms are likely to be 

passed along as lower transportation costs that, in turn, could result in lower prices for 

final goods and services. Alternatively, the savings could be kept internally in firms for 

investments or for returns to firm owners. In either case, the savings will accrue to some 

segment of consumers: either owners of trucking firms or the general public. In both 

cases, the effect will be increased spending by consumers in other sectors of the 

economy, creating jobs in a diverse set of sectors, including retail and service industries. 

As mentioned above, the value of fuel savings from this rulemaking is projected 

to be $1.2 billion (2009$) in 2014, according to Table VIII-8. If all those savings are 

 

561 North American Industry Classification System (NAICS) Code 32411.

562 EPA and NHTSA estimate that approximately 50 percent of the reduction in fuel consumption resulting 

from adopting improved fuel GHG standards and fuel efficiency standards is likely to be reflected in 

reduced U.S. imports of refined fuel, while the remaining 50 percent is expected to be reflected in reduced 

domestic fuel refining. Of this latter figure, 90 percent is anticipated to reduce U.S. imports of crude 

petroleum for use as a refinery feedstock, while the remaining 10 percent is expected to reduce U.S. 

domestic production of crude petroleum. Because we do not expect to see a significant reduction in crude 

oil production in the U.S., we do not expect this rule to have a significant impact on the Oil and Gas 

Extraction industry sector in the U.S. (NAICS 211000). For more information, refer to Section VIII-I on 

the energy security impacts from the program.
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spent, the fuel savings will stimulate increased employment in the economy through 

those expenditures. If the fuel savings accrue primarily to firm owners, they may either 

reinvest the money or take it as profit. Reinvesting the money in firm operations would 

increase employment directly. If they take the money as profit, to the extent that these 

owners are wealthier than the general public, they may spend less of the savings, and the 

resulting employment impacts would be smaller than if the savings went to the public. 

Thus, while fuel savings are expected to decrease employment in the refinery sector, they

are expected to increase employment through increased consumer expenditures.

(3) Summary

The net employment effects of this rulemaking are expected to be found 

throughout several key sectors: truck and engine manufacturers, the trucking industry, 

truck parts manufacturing, fuel production, and consumers. For the regulated sector, the 

demand effect may result in either increased or decreased employment, depending on the 

net effect on HD vehicle sales; the cost effect is expected to increase employment in the 

regulated sector; and the factor-shift effect is expected to have a small, possibly slightly 

positive effect on employment, though we cannot definitively say this is the case without 

quantification. The net effect depends on the combination of these effects. Increased 

expenditures by truck and engine parts manufacturers are expected to require increased 

labor to build parts, though this effect also depends on any changes in overall demand 

and on the labor intensity of production of new parts; increased complexity of 

technologies may imply increased labor inputs for some parts, though others might be 

less labor-intensive. It is possible, if access to capital markets is limited, that this rule 

might displace other HD sector investment, which would reduce employment associated 

with those activities. Lower prices for shipping are expected to lead to an increase in 

demand for truck shipping services and, therefore, an increase in employment in that 

sector, though this effect may be offset somewhat by changes in employment in other 

shipping sectors. Reduced fuel production implies less employment in the fuel provision 

sectors. Finally, any net cost savings would be expected to be passed along to some 

segment of consumers: either the general public or the owners of trucking firms, who are 

expected then to increase employment through their expenditures. Given the job creation 

as a result of the $1.2B (2009$) in fuel savings in 2014 and the possible employment 

increases in the manufacturing and parts sectors, we find it highly unlikely that there 

would be significant net job losses related to this policy. Given the current level of 

unemployment, net positive employment effects are possible, especially in the near term, 

due to the potential hiring of idle labor resources by the regulated sector to plan for and 

meet new requirements. In the future, when full employment is expected to return, any

changes in employment levels in the regulated sector due to this program are mostly

expected to be offset by changes in employment in other sectors.

IX. Analysis of the Alternatives 

The heavy-duty truck segment is very complex. The sector consists of a diverse 

group of impacted parties, including engine manufacturers, chassis manufacturers, truck 

manufacturers, trailer manufacturers, truck fleet owners and the public. The final 

standards that the agencies have adopted today maximize the environmental and fuel 
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savings benefits of the program while taking into consideration the unique and varied 

nature of the regulated industries. In developing this final rulemaking, we considered a 

number of alternatives that could have resulted in potentially fewer or greater GHG and 

fuel consumption reductions than the program we are finalizing. This section 

summarizes the alternatives we considered and presents assessments of technology costs, 

CO2 reductions, and fuel savings associated with each alternative. The agencies reduced 

the number of alternatives analyzed in this final rulemaking compared to the proposal 

because we did not receive any comments supporting standard setting for a smaller subset 

than HD pickup trucks, combination tractors, and vocational vehicles (as well as engines 

installed in vocational vehicles and combination tractors). As discussed below, the 

agencies have also refined some of the alternatives analyzed in response to the comments 

received.

A. What Are the Alternatives that the Agencies Considered?

In developing alternatives, NHTSA must consider EISA's requirement for the 

MD/HD fuel efficiency program noted above. 49 U.S.C. 32902(k)(2) and (3) contain the 

following three requirements specific to the MD/HD vehicle fuel efficiency improvement 

program: (1) The program must be “designed to achieve the maximum feasible 

improvement”; (2) the various required aspects of the program must be appropriate, costeffective, and technologically feasible for MD/HD vehicles; and (3) the standards 

adopted under the program must provide not less than four model years of lead time and 

three model years of regulatory stability. In considering these various requirements, 

NHTSA will also account for relevant environmental and safety considerations.

The alternatives below represent a broad range of approaches for a HD vehicle 

fuel efficiency and GHG emissions program. Details regarding the modeling of each 

alternative are included in RIA Chapter 6. The alternatives in order of increasing fuel 

efficiency and GHG emissions reductions are:

(1) Alternative 1: No Action

A “no action” alternative assumes that the agencies would not issue rules 

regarding a MD/HD fuel efficiency improvement program. This alternative is presented 

in order for NHTSA to comply with the National Environmental Policy Act (NEPA) and 

to provide an analytical baseline against which to compare environmental impacts of the 

other regulatory alternatives.563 The agencies refer to this as the “No Action Alternative” 

 

563 NEPA requires agencies to consider a “no action” alternative in their NEPA analyses and to compare the 

effects of not taking action with the effects of the reasonable action alternatives to demonstrate the different 

environmental effects of the action alternatives. See 40 CFR 1502.2(e), 1502.14(d).CEQ has explained that 

“[T]he regulations require the analysis of the no action alternative even if the agency is under a court order 

or legislative command to act. This analysis provides a benchmark, enabling decision makers to compare 

the magnitude of environmental effects of the action alternatives. [See 40 CFR 1502.14(c).] * * * Inclusion 

of such an analysis in the EIS is necessary to inform Congress, the public, and the President as intended by 

NEPA. [See 40 CFR 1500.1(a).]'' Forty Most Asked Questions Concerning CEQ’s National Environmental 

Policy Act Regulations, 46 FR 18026 (1981) (emphasis added).
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or as a “no increase” or “baseline” alternative. As described in RIA Chapter 5, this noaction alternative is considered the reference case. 

The no action alternative first presented in this final action is based on the 

assumption that the new vehicle fleet continues to perform at the same level as new 2010 

vehicles. In this way, it provides a comparison between today’s new trucks and the 

increased cost and reduced fuel consumption of future compliant vehicles. 

The agencies recognize that there is substantial uncertainty in determining an 

appropriate baseline against which to compare the effects of the proposed action. The 

lack of prior regulation of HD fuel efficiency means that there is a lack of historic data 

regarding trends in this sector. Therefore, in this final action, the agencies have also 

included an analysis using a baseline derived from annual projections developed by the 

U.S. Energy Information Administration (EIA) for the Annual Energy Outlook (AEO). 

For this alternative baseline, the agencies analyzed the new truck fuel economy

projections for the Light Commercial Trucks, along with the Medium- and Heavy-Duty

Freight Vehicles developed in AEO 2011.564 The agencies converted the fuel economy 

improvements into CO2 emissions reductions relative to a 2010 model year (See RIA 

Chapter 6).

The baseline derived from the AEO forecast provides a comparison between the 

impacts of the proposed standards and EIA’s projection of future new truck performance 

absent regulation. This alternative baseline is informative in showing one possible 

projection of future vehicle performance based on other factors beyond the regulation the 

agencies are finalizing today. The AEO forecast makes a number of assumptions that 

should be noted. AEO 2011 assumes improved fuel efficiency for 8,500-10,000 lb. 

GVWR heavy-duty pickups due to the light-duty 2012-2016 MY regulations. We project 

a similar capability for fuel economy improvement as AEO does for this class of 

vehicles; however, the agencies recognize that absent regulation manufacturers may

decline to add the necessary technologies to reach the level of our proposed standards. 

For medium and heavy-duty vocational vehicles, AEO 2011 projects a small reduction in 

fuel efficiency over time (an increase in fuel consumption), similar to that achieved under 

the MY 2010 baseline. For Class 8 combination tractors, the AEO 2011 baseline 

projections an annual improvement of approximately 0.3 percent.

We are not able to make an estimate of the cost of the AEO 2011 alternative 

baseline because we are not able to accurately determine the technology mix used in the 

AEO 2011 analysis to achieve the projected improvements in fuel efficiency. We do 

know they differ significantly from our own analysis as the EIA projections do not 

include the full range of technologies considered by the agencies (e.g. EIA’s analysis 

does not consider the use of idle reduction technologies and diesel auxiliary power units 

to reduce fuel consumption associated with vehicle hoteling). If one were to assume that 

the cost of the AEO2011 baseline was proportional to projected improvement relative to 

 

564 U.S. Energy Information Administration. Annual Energy Outlook 2011 Early Release. Last viewed on 

March 29, 2011 at http://www.eia.doe.gov/forecasts/aeo/. See Supplemental Tables 7, 63, and 68.
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our preferred alternative, the total AEO2011 baseline cost estimate would be 

approximately equal to the total cost of the preferred case, but would vary by category.

(2) Alternative 2: 12 Percent Less Stringent than the Preferred Alternative

Alternative 2 represents an alternative stringency level to the agencies’ preferred 

approach. Alternative 2 represents a stringency level which is approximately 12 percent 

less stringent than the preferred approach. The agencies calculated the Alternative 2 

stringency level in order to meet two goals. First, we sought to create an alternative that 

regulated the same engine and vehicle categories as the preferred alternative, but at lower 

stringency (10-20 percent lower) than the preferred alternative. Second we wanted an 

alternative that reflected removal of the least cost effective technology that we believed 

manufacturers would add last in order to meet the preferred alternative. In other words, 

we wanted an alternative that as closely as possible reflected the last increment in 

stringency prior to reaching our preferred alternative. Please see Table 2-39 in RIA 

Chapter 2 for a list of all of the technologies, as well as their cost and relative 

effectiveness. The resulting Alternative 2 is based on the same technologies used in 

Alternative 3 except as follows for each of the three categories.

The combination tractor standard would be based on the removal of the Advanced 

SmartWay aerodynamic package and weight reduction technologies, which decreases the 

average combination tractor GHG emissions and fuel consumption reduction by

approximately 1 percent. 

The HD pickup truck and van standard would be based on removal of the 5 

percent mass reduction technology, which decreases the average truck reduction of fuel 

consumption and GHG emissions by approximately 1.6 percent. 

The vocational vehicle standard would be based on removal of low rolling 

resistance tires – in essence meaning that there would be no expected improvement in 

performance from vocational vehicles, only from engines used to power them. This 

alternative would also reduce the amount of technologies applied to diesel engines used 

in vocational vehicles such that the engines achieve a 3 percent reduction in 2014 model 

year and a 5 percent reduction in 2017 model year, both compared to a 2010 model year 

baseline, 

The agencies have decided not to finalize Alternative 2, because as shown below,

Alternative 3 is more stringent, is technically feasible, highly cost effective, and results in 

a greater net benefit to society. 

(3) Alternative 3: Preferred Alternative and Final Standards

Alternative 3 represents the agencies’ preferred approach. This alternative 

consists of the finalized fuel efficiency and GHG standards for HD engines, HD pickup 

trucks and vans, Class 2b through Class 8 vocational vehicles, and Class 7 and 8 

combination tractors. Details regarding modeling of this alternative are included in RIA 

Chapter 5 as the control case. 
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The agencies selected Alternative 3 over Alternatives 4 and 5 described below 

because the agencies concluded that alternatives 4 and 5 were not technically feasible to 

achieve given the leadtime provided in these final rules. Hence, we have concluded that 

Alternative 3 represents the maximum feasible improvement. Section II of this preamble 

provides an explanation of the consideration that agencies gave to setting more stringent 

standards based on the application of additional technologies and our reasons for 

concluding that the identified technologies for each of the vehicle and engine standards 

that constitute Alternative 3 represented the maximum feasible improvement based on 

technological feasibility. In general, for advanced technologies, we reached this 

conclusion for one of two reasons. For some technologies such as Rankine Waste Heat 

Recovery engine technologies, the agencies have concluded that the technology is still in 

the research phase and will not be developed fully for new engine production in the time

frame of this first regulatory action. In other cases, the agencies concluded that the 

manufacturing capacity for technologies such as advanced battery systems for heavy-duty 

hybrid drivetrains could not be expanded quickly enough to allow for significant vehicle 

production volume in the time frame of this program. Section III also details the 

agencies’ reasons for not basing standard stringencies on other technologies 

(4) Alternative 4: 20 Percent More Stringent than the Preferred Alternative

Alternative 4 represents a modeled alternative which is 20 percent more stringent 

than the preferred approach. The agencies derived the stringency level based on similar 

goals as for Alternative 2. Specifically, we wanted an alternative that would reflect an 

incremental improvement over the preferred alternative based on adding the next most 

cost effective technology in each of the categories. We believed these were the 

technologies most likely to be attempted by manufacturers if a more stringent standard 

were established. As discussed above and in the feasibility discussion in Section III, we 

are not finalizing Alternative 4 because we do not believe that the technologies used in 

this alternative can be developed and introduced in the time frame of this rulemaking. 

We note that the estimated costs for this alternative are denoted as ‘+c.’ The +c is 

intended to make clear that the cost estimates we are showing do not include additional 

costs related to pulling ahead the development and expanding manufacturing base for the

additional technologies (for example, building new factories in the next few years). The 

resulting Alternative 4 is based on the same technologies used in Alternative 3 except as 

follows for each of the three categories.

The combination tractor standard would be based on the addition of Rankine 

waste heat recovery systems and 100 percent application of advanced aerodynamic 

technologies, such as underbody airflow treatment, advanced gap reduction, rearview 

cameras to replace mirrors, and wheel system streamlining, to high roof sleeper cab 

combination tractors. The agencies do not believe that either advanced aerodynamic 

technologies or Rankine waste heat recovery systems should be used to set the standard 

for HD engines in 2017 MY because this technology is still in the research phase. The 

agencies assumed 59 percent of all combination tractors are sleeper cabs and of those, 80 

percent are high roof sleeper cabs. The agencies assumed a 12 kWh waste heat recovery
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system would reduce CO2 emissions by 6 percent at a cost of $8,400 per truck.565 The 

estimated reduction in CO2 emissions from the engine for this alternative is included in 

RIA Chapter 6. The impact of 100 percent application of the advanced aerodynamic 

technology package would lead to a total 20.7 percent reduction in Cd values for high 

roof sleeper cabs over a 2010 MY baseline tractor. The incremental cost of this 

technology over the preferred case is $1,027 per vehicle. 

The HD pickup truck and van standard would be based on the addition of the 

turbocharged, downsized technology to gasoline engines which would bring the total 

reduction for gasoline HD pickup trucks and vans to 15 percent and match the level of 

reduction for the diesel pickup trucks. The agencies do not consider this to be a 

technology from which the 2017MY gasoline HD pickup truck standards should be 

premised on because we are not yet convinced that turbocharged downsized gasoline 

engines can be applied to heavy-duty truck applications in a durable manner. We are 

aware that manufacturers are testing such engines and that in pickup trucks with a duty

cycle representing a mix of passenger vehicle and work applications the engines can be 

durable. However, we are unable to conclude today that such engines will be durable and 

hence technically feasible when applied in heavy-duty truck applications with an 

expected higher average load factor. The estimated incremental cost increase to HD 

pickup trucks and vans to replace a stoichiometric gasoline direct injected V8 engine with 

coupled cam phasing used in Alternative 3 with a V6 stoichiometric gasoline direct 

injection DOHC with dual cam phasing, discrete valve lift, and twin turbochargers is 

estimated to be $1,743.566

The vocational vehicle standard would be based on the addition hybrid 

powertrains to 6 percent of the vehicles. The agencies assumed a 32 percent per vehicle 

reduction in GHG emissions and fuel consumption due to the hybrid with a cost of 

$26,667 per vehicle based on the average effectiveness and costs developed in the NAS 

report for box trucks, bucket trucks, and refuse haulers.567 

(5) Alternative 5: Trailers Plus Accelerated Hybrid

Alternative 5 builds on Alternative 4 through additional hybrid powertrain 

application rates in the HD sector and by adding a performance standard for fuel 

efficiency and GHG emissions to commercial trailers. This alternative includes all 

elements of Alternative 4 (some of which we already regard as infeasible in the model 

years covered by the final rules), plus the application of additional hybrid powertrains to 

the pickup trucks, vans, vocational vehicles, and tractors. In addition, the agencies 

applied aerodynamic technologies to commercial box trailers, along with tire 

technologies for all commercial trailers. 

 

565 TIAX. 2009. Note 198, Page 4-20.

566 See RIA Chapter 2, Table 2.35.

567 Committee to Assess Fuel Economy Technologies for Medium- and Heavy-Duty Vehicles; National 

Research Council; Transportation Research Board (2010). “Technologies and Approaches to Reducing the 

Fuel Consumption of Medium- and Heavy-Duty Vehicles,” (“NAS Report”). Washington, D.C. The 

National Academies Press. Available electronically from the National Academies Press Website at 

http://www.nap.edu/catalog.php?record_id=12845. Page 146.
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The agencies set the hybrid penetration for each category such that it represents 

50 percent of the HD pickup truck and van segment, 50 percent of vocational vehicles, 

and 5 percent of tractors in 2017 model year. The agencies have concluded that it is not 

feasible to achieve hybrid technology penetration rates at or even near these levels in the 

time frame of this rulemaking. As with Alternative 4, we include a +c in our cost 

estimates for this alternative to reflect additional costs not estimated by the agencies. The 

agencies assumed that a hybrid powertrain would provide a 32 percent reduction in CO2

emissions and fuel consumption of a vocational vehicle at a projected cost of $26,667 per 

vehicle, based on the average of the NAS report findings for box trucks, bucket trucks, 

and refuse vehicles.568 The agencies are projecting a cost of $9,000 per vehicle for the 

HD pickup trucks and vans with an effectiveness of 18 percent, again based on the NAS 

report.569 Lastly, the effectiveness of hybrid powertrains installed in tractors was 

assumed to be 10 percent at a cost of $25,000 based on the NAS report.570

The combination tractor technology package for Alternative 5 includes the 

preferred alternative technologies, waste heat recovery and Advanced SmartWay

aerodynamic package used in Alternative 4, and application of hybrid powertrains 

discussed above, in addition to a regulation for commercial trailers pulled by combination 

tractors. The agencies assumed a box trailer program would mirror the SmartWay

program and include tire and aerodynamic requirements. The agencies added low rolling 

resistance tires to all commercial trailers, which are assumed to have 15 percent lower 

rolling resistance than the baseline trailer tire which is equivalent to the target value 

required by SmartWay. The aerodynamics of the box trailers were assumed to improve 

the coefficient of drag for the combination tractor-trailer by 10 percent through the 

application of technologies such as trailer skirts and gap reducers.571 These technologies 

would result in further reductions in drag coefficient and rolling resistance coefficient 

from the MY 2010 baseline. As stated above for hybrids, the agencies do not believe that 

it is possible to achieve technology penetration rates at or even near these levels in the 

time frame of this rulemaking. 

The combination tractor costs for this alternative are equal to the costs in 

Alternative 4, plus $25,000 for hybrid powertrains in ten percent of tractors, plus the 

costs of trailers. The costs for the trailer program of Alternative 5 were derived based on 

the assumption that trailer aerodynamic improvements would cost $2,150 per trailer. 

This cost assumes side fairings and gap reducers and is based on the ICF cost estimate.572 

The agencies applied the aerodynamic improvement to only box trailers, which represent 

approximately 60 percent of the trailer sales. The agencies used $528 per trailer (2014 

MY cost) for low rolling resistance based on the agencies’ estimate of $66 per tire in the 

tractor program. Lastly, the agencies assumed the trailer volume is equal to three times 

the tractor volume based on the 3:1 ratio of trailers to tractors in the market today. 

 

568 NAS Report. Page 146.

569 NAS Report. Page 146.

570 NAS Report. Page 146.

571 The Cd improvement of 10 percent for trailer improvements was derived from the TIAX report, Table 4-

26 on page 4-50.

572 Assumed retail prices of $1,300 for side skirts and $850 for gap reducers based on the ICF Cost Report, 

page 90.
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B. How Do These Alternatives Compare in Overall GHG Emissions 

Reductions and Fuel Efficiency and Cost?

The agencies analyzed all five alternatives through the MOVES model to evaluate 

the impact of each alternative, as shown in Table IX-1. The table contains the annual 

CO2 and fuel savings in 2030 and 2050 for each alternative (relative to the reference 

scenario of Alternative 1), presenting both the total savings across all regulatory

categories, and for each regulatory category. 

Table IX-2 presents the annual technology costs associated with each alternative 

(relative to the reference scenario of Alternative 1) in 2030 and 2050 for each regulatory

category. In addition, the total annual downstream impacts of NOX, CO, PM, and VOC 

emissions in 2030 for each of the alternatives are included in Table IX-3. 

Lastly, the agencies project the monetized net benefits associated with each 

alternative in 2030 and 2050 as shown in Table IX-4 and Table IX-5.

Table IX-1: Annual CO2 and Oil Reductions Relative to Alternative 1 in 2030 and 2050

DOWNSTREAM CO2

REDUCTIONS (MMT)

OIL REDUCTIONS 

(BILLION GALLONS)

2030 2050 2030 2050

Alt. 1 Baseline 0 0 0 0

Alt. 1a AEO 2011 Baseline- Total 39 90 3.9 9.0

Tractors 29 73 2.9 7.1

HD Pickup Trucks 9 16 0.9 1.7

Vocational Vehicles 1 2 0.1 0.2

Alt. 2 Less Stringent- Total 54 78 5.4 7.7

Tractors 42 59 4.2 5.8

HD Pickup Trucks 7 11 0.8 1.2

Vocational Vehicles 5 7 0.4 0.7

Alt. 3 Preferred – Total 61 88 6.0 8.7

Tractors 45 63 4.4 6.2

HD Pickup Trucks 8 13 0.9 1.3

Vocational Vehicles 7 11 0.7 1.1

Alt. 4 More Stringent– Total 74 107 7.4 10.7

Tractors 53 74 5.2 7.3

HD Pickup Trucks 10 15 1.0 1.6

Vocational Vehicles 11 18 1.1 1.8

Alt. 5 Max Technology– Total 99 146 9.8 14.5

Tractors 61 85 6.0 8.3

HD Pickup Trucks 15 24 1.6 2.5

Vocational Vehicles 23 37 2.2 3.6
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Table IX-2: Technology Cost Projections Relative to Alternative 1 for Each Alternativea

TECHNOLOGY COSTS (2009$ 

MILLIONS)

2030 2050

Alt. 1 Baseline $0 $0

Alt. 1a AEO 2011 Baseline – Total b-- --

Tractors -- --

HD Pickup Trucks -- --

Vocational Vehicles -- --

Alt. 2 Less Stringent – Total $1,676 $2,440

Tractors $743 $1,227

HD Pickup Trucks $817 $1,029

Vocational Vehicles $117 $185

Alt. 3 Preferred – Total $2,210 $3,287

Tractors $1,076 $1,777

HD Pickup Trucks $918 $1,156

Vocational Vehicles $216 $354

Alt. 4 More Stringent – Total $5,211+c $6,996+c

Tractors $1,953+c $3,225+c

HD Pickup Trucks $1,442+c $1,816+c

Vocational Vehicles $1,816+c $1,954+c

$17,909+c $27,306+c Alt. 5 Max Technology – Total $2,747+c $4,292+c

Tractors $5,669+c $7,142+c

HD Pickup Trucks $9,493+c $15,873+c

Vocational Vehicles $5,211+c $6,996+c

Notes:

a The +c is intended to make clear that the cost estimates we are showing do not include 

additional costs related to pulling ahead the development and expanding manufacturing 

base for these technologies.

b The agencies did not conduct a cost analysis for the AEO2011 baseline.
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Table IX-3: Downstream Impacts Relative to Alternative 1 of Key Non-GHGs for Each Alternative 

in 2030

NOX CO PM2.5 VOC

Alt. 1 Baseline 0% 0% 0% 0%

Alt. 1a AEO 2011 

Baseline

8.8% 1.0% -3.8% 7.2%

Alt. 2 Less Stringent -21.9% -2.0% 8.4% -19.0%

Alt. 3 Preferred -22.0% -2.0% 8.5% -19.1%

Alt. 4 More Stringent -22.5% -2.0% 8.7% -19.5%

Alt. 5 Max Technology -22.9% -2.1% 8.4% (1) -

20.0%

Table IX-4: Monetized Net Benefits Associated with Each Alternative Relative to Alternative 1 for 

Lifetime of 2014 through 2018 Model Year Vehicles(3% discount rate, Million 2009 dollars)

Alt.1 

Baseline

Alt.2 

Less 

Stringent

Alt.3 

Preferre

d

Alt.4 More 

Stringent

Alt.5 Max 

Technolog

y

Truck Program Costs d$0 $5,900 $8,100 $20,700+c $37,200+c

Fuel Savings (pre-tax) $0 $45,000 $50,100 $63,900 $79,100

Reduced CO2 Emissions at Each Assumed SCC Value a,b

5% (avg SCC) $0 $1,100 $1,200 $1,600 $1,900

3% (avg SCC) $0 $5,100 $5,700 $7,200 $9,000

2.5% (avg SCC) $0 $8,400 $9,400 $12,000 $15,000

3% (95th percentile) $0 $16,000 $17,000 $22,000 $27,000

Energy Security Impacts (price 

shock)

$0 $2,400 $2,700 $3,400 $4,200

Accidents, Congestion, Noise e$0 -$1,300 -$1,500 -$1,600 -$1,600

Refueling Savings $0 $300 $400 $500 $600

Non-CO2 GHG Impacts and 

Non-GHG Impacts c

N/A N/A N/A N/A N/A

Monetized Net Benefits at Each Assumed SCC Value a,b

5% (avg SCC) $0 $41,600 $44,800 $47,100+c $47,000+c

3% (avg SCC) $0 $45,600 $49,300 $52,700+c $54,100+c

2.5% (avg SCC) $0 $48,900 $53,000 $57,500+c $60,100+c

3% (95th percentile) $0 $56,500 $60,600 $67,500+c $72,100+c

Notes: 

a Net present value of reduced CO2 emissions is calculated differently than other benefits. The same 

discount rate used to discount the value of damages from future emissions (SCC at 5, 3, and 2.5 

percent) is used to calculate net present value of SCC for internal consistency. Refer to the SCC TSD 

for more detail. 

b

Section VIII.G notes that SCC increases over time. Corresponding to the years in this table, the SCC 

estimates range as follows: for Average SCC at 5%: $5-$16; for Average SCC at 3%: $22-$46; for 

Average SCC at 2.5%: $36-$66; and for 95th percentile SCC at 3%: $66-$139. Section VIII.G also 

presents these SCC estimates.

c The monetized GHG benefits presented in this analysis exclude the value of changes in non-CO2 GHG 

emissions expected under this rulemaking (See RIA Chapter 5). Although EPA has not monetized 

changes in non-CO2 GHGs, the value of any increases or reductions should not be interpreted as zero. 

d “+c” indicates additional costs not estimated in this rulemaking.
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e Negative sign represents an increase in Accidents, Congestion, and Noise.

Table IX-5 Monetized Net Benefits Associated with Each Alternative Relative to Alternative 1 for 

Lifetime of 2014 through 2018 Model Year Vehicles(7% discount rate, Million 2009 dollars)

Alt.1 

Baseline

Alt.2 Less 

Stringent

Alt.3 

Preferre

d

Alt.4 

More 

Stringent

Alt.5 Max 

Technology

Truck Program Costs d$0 $5,900 $8,100 $20,700+

c

$37,200+c

Fuel Savings (pre-tax) $0 $30,900 $34,400 $43,800 $53,900

Reduced CO2 Emissions at Each Assumed SCC Value a,b

5% (avg SCC) $0 $1,100 $1,200 $1,600 $1,900

3% (avg SCC) $0 $5,100 $5,700 $7,200 $9,000

2.5% (avg SCC) $0 $8,400 $9,400 $12,000 $15,000

3% (95th percentile) $0 $16,000 $17,000 $22,000 $27,000

Energy Security Impacts (price 

shock)

$0 $1,600 $1,800 $2,300 $2,900

Accidents, Congestion, Noise e$0 -$900 -$1,000 -$1,100 -$1,100

Refueling Savings $0 $200 $200 $300 $400

Non-CO2 GHG Impacts and 

Non-GHG Impacts c

N/A N/A N/A N/A N/A

Monetized Net Benefits at Each Assumed SCC Value a,b

5% (avg SCC) $0 $27,000 $28,500 $26,200+

c

$20,800+c

3% (avg SCC) $0 $31,000 $33,000 $31,800+

c

$27,900+c

2.5% (avg SCC) $0 $34,300 $36,700 $36,600+

c

$33,900+c

3% (95th percentile) $0 $41,900 $44,300 $46,600+

c

$45,900+c

Notes: 

a Net present value of reduced CO2 emissions is calculated differently than other benefits. The same 

discount rate used to discount the value of damages from future emissions (SCC at 5, 3, and 2.5 

percent) is used to calculate net present value of SCC for internal consistency. Refer to the SCC TSD 

for more detail. 

b

Section VIII.G notes that SCC increases over time. Corresponding to the years in this table, the SCC 

estimates range as follows: for Average SCC at 5%: $5-$16; for Average SCC at 3%: $22-$46; for 

Average SCC at 2.5%: $36-$66; and for 95th percentile SCC at 3%: $66-$139. Section VIII.G also 

presents these SCC estimates.

c The monetized GHG benefits presented in this analysis exclude the value of changes in non-CO2 GHG 

emissions expected under this rulemaking (See RIA Chapter 5). Although EPA has not monetized 

changes in non-CO2 GHGs, the value of any increases or reductions should not be interpreted as zero. 

d “+c” indicates additional costs not estimated in this rulemaking.

e Negative sign represents an increase in Accidents, Congestion, and Noise.

The agencies also project the monetized net benefits associated with each 

alternative by vehicle class for the 2014 through 2018 MY vehicles over their lifetimes as 

shown in Table IX-6 through Table IX-8 at a three percent discount rate for HD pickup 

trucks & vans, vocational vehicles and combination tractors, respectively, and in Table 
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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IX-9 through Table IX-11 at a seven percent discount rate for HD pickup trucks and vans, 

vocational vehicles and combination tractors, respectively.

Table IX-6: Monetized Net Benefits Associated with Each Alternative Relative to Alternative 1 for 

Lifetime of 2014 through 2018 Model Year HD Pickup Trucks & Vans (3% discount rate, Million 

2009$)

Alt.1

Baseline

Alt.2 Less 

Stringent

Alt.3

Preferred

Alt.4 More 

Stringent

Alt.5 Max 

Technology

Truck Program Costs d$0 $1,780 $1,970 $3,220+c $9,890+c

Fuel Savings (pre-tax) $0 $3,480 $4,060 $4,910 $7,700

Energy Security Impacts (price 

shock)

$0 $190 $220 $270 $420

Accidents, Congestion, Noise e$0 -$330 -$350 -$370 -$350

Refueling Savings $0 $40 $50 $60 $90

Non-CO2 GHG Impacts and 

Non-GHG Impacts c

N/A N/A N/A N/A N/A

Reduced CO2 Emissions at Each Assumed SCC Value a,b

5% (avg SCC) $0 $100 $100 $100 $200

3% (avg SCC) $0 $500 $500 $600 $900

2.5% (avg SCC) $0 $800 $900 $1,100 $1,500

3% (95th percentile) $0 $1,400 $1,600 $1,900 $2,800

Monetized Net Benefits at Each Assumed SCC Value a,b

5% (avg SCC) $0 $1,700 $2,110 $1,750+c -$1,830+c

3% (avg SCC) $0 $2,100 $2,510 $2,250+c -$1,130+c

2.5% (avg SCC) $0 $2,400 $2,910 $2,750+c -$530+c

3% (95th percentile) $0 $3,000 $3,610 $3,550+c $770+c

Notes: 

a Net present value of reduced CO2 emissions is calculated differently than other benefits. The same 

discount rate used to discount the value of damages from future emissions (SCC at 5, 3, and 2.5 percent) is 

used to calculate net present value of SCC for internal consistency. Refer to the SCC TSD for more detail. 

b

Section VIII.G notes that SCC increases over time. Corresponding to the years in this table, the SCC 

estimates range as follows: for Average SCC at 5%: $5-$16; for Average SCC at 3%: $22-$46; for 

Average SCC at 2.5%: $36-$66; and for 95th percentile SCC at 3%: $66-$139. Section VIII.G also 

presents these SCC estimates.

c Due to analytical and resource limitations, MY non-GHG emissions (direct PM, VOCs, NO2 and SO2) 

were not estimated for this analysis. Although EPA has not monetized changes in non-CO2 GHGs, the 

value of any increases or reductions should not be interpreted as zero.

d “+c” indicates additional costs not estimated in this rulemaking.

e Negative sign represents an increase in Accidents, Congestion, and Noise.
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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Table IX-7 Monetized Net Benefits Associated with Each Alternative Relative to Alternative 1 for 

Lifetime of 2014 through 2018 Model Year Vocational Vehicles (3% discount rate, Million 2009$)

Alt.1

Baseline

Alt.2 Less 

Stringent

Alt.3

Preferred

Alt.4 More 

Stringent

Alt.5 Max 

Technology

Truck Program Costs d$0 $670 $1,140 $9,140+c $15,840+c

Fuel Savings (pre-tax) $0 $3,420 $5,420 $8,930 $14,270

Energy Security Impacts (price 

shock)

$0 $180 $290 $480 $760

Accidents, Congestion, Noise e$0 -$540 -$650 -$670 -$500

Refueling Savings $0 $40 $60 $110 $170

Non-CO2 GHG Impacts and 

Non-GHG Impacts c

N/A N/A N/A N/A N/A

Reduced CO2 Emissions at Each Assumed SCC Value a,b

5% (avg SCC) $0 $100 $100 $200 $300

3% (avg SCC) $0 $400 $600 $1,000 $1,500

2.5% (avg SCC) $0 $700 $1,100 $1,700 $2,600

3% (95th percentile) $0 $1,300 $1,900 $3,100 $4,700

Monetized Net Benefits at Each Assumed SCC Value a,b

5% (avg SCC) $0 $2,530 $4,080 -$90+c -$840+c

3% (avg SCC) $0 $2,830 $4,580 $710+c $360+c

2.5% (avg SCC) $0 $3,130 $5,080 $1,410+c $1,460+c

3% (95th percentile) $0 $3,730 $5,880 $2,810+c $3,560+c

Notes: 

a Net present value of reduced CO2 emissions is calculated differently than other benefits. The 

same discount rate used to discount the value of damages from future emissions (SCC at 5, 3, and 

2.5 percent) is used to calculate net present value of SCC for internal consistency. Refer to the 

SCC TSD for more detail.

b

Section VIII.G notes that SCC increases over time. Corresponding to the years in this table, the 

SCC estimates range as follows: for Average SCC at 5%: $5-$16; for Average SCC at 3%: $22-

$46; for Average SCC at 2.5%: $36-$66; and for 95th percentile SCC at 3%: $66-$139. Section 

VIII.G also presents these SCC estimates.

c Due to analytical and resource limitations, MY non-GHG emissions (direct PM, VOCs, NO2 and 

SO2) were not estimated for this analysis. Although EPA has not monetized changes in non-CO2

GHGs, the value of any increases or reductions should not be interpreted as zero.

d “+c” indicates additional costs not estimated in this rulemaking.

e Negative sign represents an increase in Accidents, Congestion, and Noise.
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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Table IX-8 Monetized Net Benefits Associated with Each Alternative Relative to Alternative 1 for 

Lifetime of 2014 through 2018 Model Year Combination Tractors (3% discount rate, Million 2009$)

Alt.1

Baseline

Alt.2 Less 

Stringent

Alt.3

Preferred

Alt.4 More 

Stringent

Alt.5 Max 

Technology

Truck Program Costs d$0 $3,300 $4,950 $8,430+c $11,540+c

Fuel Savings (pre-tax) $0 $38,140 $40,650 $50,030 $57,190

Energy Security Impacts (price 

shock)

$0 $2,030 $2,160 $2,660 $3,040

Accidents, Congestion, Noise e$0 -$450 -$480 -$590 -$770

Refueling Savings $0 $230 $250 $300 $350

Non-CO2 GHG Impacts and 

Non-GHG Impacts c

N/A N/A N/A N/A N/A

Reduced CO2 Emissions at Each Assumed SCC Value a,b

5% (avg SCC) $0 $900 $1,000 $1,200 $1,400

3% (avg SCC) $0 $4,200 $4,500 $5,600 $6,500

2.5% (avg SCC) $0 $7,000 $7,500 $9,300 $11,000

3% (95th percentile) $0 $13,000 $14,000 $17,000 $20,000

Monetized Net Benefits at Each Assumed SCC Value a,b

5% (avg SCC) $0 $37,550 $38,630 $45,170+c $49,670+c

3% (avg SCC) $0 $40,850 $42,130 $49,570+c $54,770+c

2.5% (avg SCC) $0 $43,650 $45,130 $53,270+c $59,270+c

3% (95th percentile) $0 $49,650 $51,630 $60,970+c $68,270+c

Notes: 

a Net present value of reduced CO2 emissions is calculated differently than other benefits. The same 

discount rate used to discount the value of damages from future emissions (SCC at 5, 3, and 2.5 percent) is 

used to calculate net present value of SCC for internal consistency. Refer to the SCC TSD for more detail. 

b

Section VIII.G notes that SCC increases over time. Corresponding to the years in this table, the SCC 

estimates range as follows: for Average SCC at 5%: $5-$16; for Average SCC at 3%: $22-$46; for 

Average SCC at 2.5%: $36-$66; and for 95th percentile SCC at 3%: $66-$139. Section VIII.G also 

presents these SCC estimates.

c Due to analytical and resource limitations, MY non-GHG emissions (direct PM, VOCs, NO2 and SO2) 

were not estimated for this analysis. Although EPA has not monetized changes in non-CO2 GHGs, the 

value of any increases or reductions should not be interpreted as zero.

d “+c” indicates additional costs not estimated in this rulemaking.

e Negative sign represents an increase in Accidents, Congestion, and Noise.
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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Table IX-9: Monetized Net Benefits Associated with Each Alternative Relative to Alternative 1 for 

Lifetime of 2014 through 2018 Model Year HD Pickup Trucks & Vans (7% discount rate, Million 

2009$)

Alt.1

Baseline

Alt.2 Less 

Stringent

Alt.3

Preferred

Alt.4 More 

Stringent

Alt.5 Max 

Technology

Truck Program Costs d$0 $1,780 $1,970 $3,220+c $9,890+c

Fuel Savings (pre-tax) $0 $2,180 $2,550 $3,090 $4,830

Energy Security Impacts (price 

shock)

$0 $120 $140 $170 $260

Accidents, Congestion, Noise e$0 -$220 -$230 -$250 -$230

Refueling Savings $0 $30 $30 $40 $60

Non-CO2 GHG Impacts and 

Non-GHG Impacts c

N/A N/A N/A N/A N/A

Reduced CO2 Emissions at Each Assumed SCC Value a,b

5% (avg SCC) $0 $100 $100 $100 $200

3% (avg SCC) $0 $500 $500 $600 $900

2.5% (avg SCC) $0 $800 $900 $1,100 $1,500

3% (95th percentile) $0 $1,400 $1,600 $1,900 $2,800

Monetized Net Benefits at Each Assumed SCC Value a,b

5% (avg SCC) $0 $430 $620 -$70+c -$4,770+c

3% (avg SCC) $0 $830 $1,020 $430+c -$4,070+c

2.5% (avg SCC) $0 $1,130 $1,420 $930+c -$3,470+c

3% (95th percentile) $0 $1,730 $2,120 $1,730+c -$2,170+c

Notes: 

a Net present value of reduced CO2 emissions is calculated differently than other benefits. The same 

discount rate used to discount the value of damages from future emissions (SCC at 5, 3, and 2.5 percent) is 

used to calculate net present value of SCC for internal consistency. Refer to the SCC TSD for more detail. 

b

Section VIII.G notes that SCC increases over time. Corresponding to the years in this table, the SCC 

estimates range as follows: for Average SCC at 5%: $5-$16; for Average SCC at 3%: $22-$46; for 

Average SCC at 2.5%: $36-$66; and for 95th percentile SCC at 3%: $66-$139. Section VIII.G also 

presents these SCC estimates.

c Due to analytical and resource limitations, MY non-GHG emissions (direct PM, VOCs, NO2 and SO2) 

were not estimated for this analysis. Although EPA has not monetized changes in non-CO2 GHGs, the 

value of any increases or reductions should not be interpreted as zero.

d “+c” indicates additional costs not estimated in this rulemaking.

e Negative sign represents an increase in Accidents, Congestion, and Noise.
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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Table IX-10 Monetized Net Benefits Associated with Each Alternative Relative to Alternative 1 for 

Lifetime of 2014 through 2018 Model Year Vocational Vehicles (7% discount rate, Million 2009$)

Alt.1

Baseline

Alt.2 Less 

Stringent

Alt.3

Preferred

Alt.4 More 

Stringent

Alt.5 Max 

Technology

Truck Program Costs d$0 $670 $1,140 $9,140+c $15,840+c

Fuel Savings (pre-tax) $0 $2,280 $3,630 $5,970 $9,410

Energy Security Impacts (price 

shock)

$0 $120 $190 $320 $500

Accidents, Congestion, Noise e$0 -$380 -$450 -$460 -$350

Refueling Savings $0 $30 $40 $70 $110

Non-CO2 GHG Impacts and 

Non-GHG Impacts c

N/A N/A N/A N/A N/A

Reduced CO2 Emissions at Each Assumed SCC Value a,b

5% (avg SCC) $0 $100 $100 $200 $300

3% (avg SCC) $0 $400 $600 $1,000 $1,500

2.5% (avg SCC) $0 $700 $1,100 $1,700 $2,600

3% (95th percentile) $0 $1,300 $1,900 $3,100 $4,700

Monetized Net Benefits at Each Assumed SCC Value a,b

5% (avg SCC) $0 $1,480 $2,370 -$3,040+c -$5,870+c

3% (avg SCC) $0 $1,780 $2,870 -$2,240+c -$4,670+c

2.5% (avg SCC) $0 $2,080 $3,370 -$1,540+c -$3,570+c

3% (95th percentile) $0 $2,680 $4,170 -$140+c -$1,470+c

Notes: 

a Net present value of reduced CO2 emissions is calculated differently than other benefits. The same 

discount rate used to discount the value of damages from future emissions (SCC at 5, 3, and 2.5 percent) is 

used to calculate net present value of SCC for internal consistency. Refer to the SCC TSD for more detail. 

b

Section VIII.G notes that SCC increases over time. Corresponding to the years in this table, the SCC 

estimates range as follows: for Average SCC at 5%: $5-$16; for Average SCC at 3%: $22-$46; for 

Average SCC at 2.5%: $36-$66; and for 95th percentile SCC at 3%: $66-$139. Section VIII.G also 

presents these SCC estimates.

c Due to analytical and resource limitations, MY non-GHG emissions (direct PM, VOCs, NO2 and SO2) 

were not estimated for this analysis. Although EPA has not monetized changes in non-CO2 GHGs, the 

value of any increases or reductions should not be interpreted as zero.

d “+c” indicates additional costs not estimated in this rulemaking.

e Negative sign represents an increase in Accidents, Congestion, and Noise.
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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Table IX-11 Monetized Net Benefits Associated with Each Alternative Relative to Alternative 1 for 

Lifetime of 2014 through 2018 Model Year Combination Tractors (7% discount rate, Million 2009$)

Alt.1

Baseline

Alt.2 Less 

Stringent

Alt.3

Preferred

Alt.4 More 

Stringent

Alt.5 Max 

Technology

Truck Program Costs d$0 $3,300 $4,950 $8,430+c $11,540+c

Fuel Savings (pre-tax) $0 $26,420 $28,170 $34,710 $39,680

Energy Security Impacts (price 

shock)

$0 $1,410 $1,500 $1,850 $2,110

Accidents, Congestion, Noise e$0 -$320 -$340 -$420 -$550

Refueling Savings $0 $160 $170 $210 $240

Non-CO2 GHG Impacts and 

Non-GHG Impacts c

N/A N/A N/A N/A N/A

Reduced CO2 Emissions at Each Assumed SCC Value a,b

5% (avg SCC) $0 $900 $1,000 $1,200 $1,400

3% (avg SCC) $0 $4,200 $4,500 $5,600 $6,500

2.5% (avg SCC) $0 $7,000 $7,500 $9,300 $11,000

3% (95th percentile) $0 $13,000 $14,000 $17,000 $20,000

Monetized Net Benefits at Each Assumed SCC Value a,b

5% (avg SCC) $0 $25,270 $25,550 $29,120+c $31,340+c

3% (avg SCC) $0 $28,570 $29,050 $33,520+c $36,440+c

2.5% (avg SCC) $0 $31,370 $32,050 $37,220+c $40,940+c

3% (95th percentile) $0 $37,370 $38,550 $44,920+c $49,940+c

Notes: 

a Net present value of reduced CO2 emissions is calculated differently than other benefits. The same 

discount rate used to discount the value of damages from future emissions (SCC at 5, 3, and 2.5 percent) is 

used to calculate net present value of SCC for internal consistency. Refer to the SCC TSD for more detail. 

b

Section VIII.G notes that SCC increases over time. Corresponding to the years in this table, the SCC 

estimates range as follows: for Average SCC at 5%: $5-$16; for Average SCC at 3%: $22-$46; for 

Average SCC at 2.5%: $36-$66; and for 95th percentile SCC at 3%: $66-$139. Section VIII.G also 

presents these SCC estimates.

c Due to analytical and resource limitations, MY non-GHG emissions (direct PM, VOCs, NO2 and SO2) 

were not estimated for this analysis. Although EPA has not monetized changes in non-CO2 GHGs, the 

value of any increases or reductions should not be interpreted as zero.

d “+c” indicates additional costs not estimated in this rulemaking.

e Negative sign represents an increase in Accidents, Congestion, and Noise.

C. What Is the Agencies’ Decision Regarding Trailer Standards?

A central theme throughout our HD Program is the recognition of the diversity

and complexity of the heavy-duty vehicle segment. Trailers are an important part of this 

segment and are no less diverse in the range of functions and applications they serve. 

They are the primary vehicle for moving freight in the United States. The type of freight 

varies from retail products to be sold in stores, to bulk goods such as stones, to industrial 

liquids such as chemicals, to equipment such as bulldozers. Semi-trailers come in a large 

variety of styles – box, refrigerated box, flatbed, tankers, bulk, dump, grain, and many

others. The most common type of trailer is the box trailer, but even box trailers come in 

many different lengths ranging from 28 feet to 53 feet or greater, and in different widths, 

heights, depths, materials (wood, composites, and/or aluminum), construction (curtain 

side or hard side), axle configuration (sliding tandem or fixed tandem), and multiple other 

distinct features. NHTSA and EPA believe trailers impact the fuel consumption and CO2
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emissions from combination tractors and the agencies see opportunities for reductions. 

Unlike our experience with trucks and engines, the agencies have very limited experience 

related to regulating trailers for fuel efficiency or emissions. Likewise, the trailer 

manufacturing industry has only the most limited experience complying with regulations 

related to emissions and none with regard to EPA or NHTSA certification and 

compliance procedures.

The agencies broadly solicited comments on controlling fuel efficiency and GHG 

emissions through eventual trailer regulations as we described in the notice of proposed 

rulemaking which could set the foundation of a future rulemaking for trailers. 75 FR at 

74345-351 (although this was a solicitation for comment regarding future action outside 

the present rulemaking). 

The general theme of the comments received was that technologies exist today

that can improve trailer efficiency. We received several comments from stakeholders 

which encouraged the agencies to set fuel efficiency and GHG emissions standards for 

trailers in this rulemaking. The agencies also received comments supporting a delay in 

trailer regulations. Specifically, IPI commented that the agencies should regulate trailers 

at least to some degree, arguing that the agencies’ reasoning for not doing so was 

insufficient and requesting a plan and schedule in the final rule for the future regulation 

of trailers. One commenter recognized that there are well over 100 trailer manufacturers 

in the U.S., with almost all being small businesses. They stressed the need for the 

agencies to reach out to the trailer industry and associations prior to developing a 

regulatory program for this industry. In addition, they stated that time is needed to 

develop sufficient research into the area. None of the commenters that supported trailer 

regulation in this action addressed the complexities of the trailer industry, nor a method 

to measure trailer aerodynamic improvements

In the NPRM, the agencies discussed relatively conceptual approaches to how a 

future trailer regulation could be developed; however, we did not provide a proposed test

procedure or proposed standard. The agencies proposed to delay the regulation of 

trailers, as the inclusion would not be feasible at this time due to the lack of a test 

procedure and the myriad of technical and policy issues not teed up in the NPRM or 

addressed in comments. Additionally, since a number of trailer manufacturing entities 

are small businesses, EPA and NHTSA need to allow sufficient time to convene a 

SBREFA panel to conduct the proper outreach to the potentially impacted stakeholders. 

As noted earlier, the agencies do not believe it warranted to delay the combination tractor 

and vocational vehicle standards for the years it will take to resolve these issues. NHTSA 

and EPA agree that the regulation of trailers, when appropriate, is likely to provide fuel 

efficiency benefits. We continue to believe that both agencies must perform a more 

comprehensive assessment of the trailer industry, and therefore that their inclusion at this 

time is not feasible. Until that time, the SmartWay Transport Partnership Program will 

continue to encourage the development and use of technologies to reduce fuel 

consumption and CO2 emissions from trailers.
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X. Public Participation 

The agencies proposed their respective rules on November 30, 2010 (75 FR 

74152). Two public hearings were held to provide interested parties the opportunity to 

present data, views, or arguments concerning the proposal; the first hearing was held in 

Chicago, IL on November 15, 2010, and the second in Cambridge, MA on November 18, 

2010. The public was invited to submit written comments on the proposal during the 

formal comment period, which ended on January 31, 2011. The agencies received over 

41,000 comments - over 3,000 of them unique - from industry, environmental 

organizations, states, and individuals.

The vast majority of commenters supported the central tenets of the proposed HD 

National Program. That is, there was broad support for a national program which would 

reduce fuel consumption and GHG emissions from the three heavy-duty regulatory

categories – heavy-duty pickup trucks and vans, vocational vehicles, and combination 

tractors. The agencies received specific comments on many aspects of the proposal. 

Throughout this notice, the agencies discuss many of the key issues arising from 

the public comments and the agencies’ responses. In addition, the agencies have 

addressed all of the public comments in the Response to Comments document associated 

with this final action and located in the docket (Docket ID EPA–HQ–OAR–2010–0162, 

or NHTSA-2010-0079). 

XI. NHTSA’s Record of Decision

On May 21, 2010, President Obama issued a memorandum entitled “Improving 

Energy Security, American Competitiveness and Job Creation, and Environmental 

Protection through a Transformation of our Nation’s Fleet of Cars and Trucks” to the 

Secretary of Transportation, the Administrator of NHTSA, the Administrator of EPA, and 

the Secretary of Energy.

573 The memorandum requested that the Administrators of EPA 

and NHTSA begin work on a Joint Rulemaking under EISA and the Clean Air Act and 

establish fuel efficiency and GHG emission standards for commercial medium- and 

heavy-duty vehicles beginning with MY 2014. The President requested that NHTSA

implement fuel efficiency standards and EPA implement GHG emission standards that 

take into account the market structure of the trucking industry and the unique demands of 

heavy-duty vehicle applications; seek harmonization with applicable State standards; 

consider the findings and recommendations published in the National Academy of 

Sciences (NAS) report on medium- and heavy-duty truck regulation; strengthen the 

industry and enhance job creation in the United States; and seek input from all 

stakeholders, while recognizing the continued leadership role of California and other 

States.

 

573 The White House, Office of the Press Secretary, Presidential Memorandum Regarding Fuel Efficiency 

Standards (May 21, 2010); The White House, Office of the Press Secretary, President Obama Directs 

Administration to Create First-Ever National Efficiency and Emissions Standards for Medium- and HeavyDuty Trucks (May 21, 2010). 
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In accordance with this policy, this Final Rule promulgates fuel efficiency

standards for HD vehicles built in MYs 2014-2018. This Final Rule constitutes the 

Record of Decision (ROD) for NHTSA’s HD vehicle Fuel Efficiency Improvement 

Program, pursuant to the National Environmental Policy Act (NEPA) and the Council on 

Environmental Quality’s (CEQ) implementing regulations.574 See 40 CFR § 1505.2. 

As required by CEQ regulations, this Final Rule and ROD sets forth the

following: (1) the agency’s decision; (2) alternatives considered by NHTSA in reaching 

its decision, including the environmentally preferable alternative; (3) the factors balanced 

by NHTSA in making its decision, including considerations of national policy; (4) how 

these factors and considerations entered into its decision; and (5) the agency’s 

preferences among alternatives based on relevant factors, including economic and 

technical considerations and agency statutory missions. This Final Rule also briefly

addresses mitigation.

A. The Agency’s Decision

In the Draft Environmental Impact Statement (DEIS) and the Final Environmental 

Impact Statement (FEIS), the agency identified a Preferred Alternative which would set 

overall fuel consumption standards for HD vehicles and engines. The Preferred 

Alternative, identified as Alternative 3 in the FEIS, would include standards for engines 

used in Classes 2b-8 vocational vehicles (except engines in HD pickups and vans, which 

are regulated as complete vehicles), fuel consumption standards for HD pickups and vans 

by work factor, overall vehicle fuel consumption standards for Classes 2b-8 vocational 

vehicles (in gal/1,000 ton-miles), and overall fuel consumption standards for Classes 7 

and 8 tractors. 

The Preferred Alternative identified in the NPRM, DEIS, and FEIS assumed that 

the vocational vehicle standards would lead to a 10 percent reduction in the tire rolling 

resistance levels of the tires installed in vocational vehicles. After carefully reviewing 

and analyzing all of the information in the public record including technical support 

documents, the FEIS, and public and agency comments submitted on the DEIS, the FEIS, 

and the NPRM, NHTSA has decided to finalize a standard that includes slightly more 

stringent requirements for vocational vehicles than those included in the Preferred 

Alternative analyzed in the FEIS. Subsequent to issuing the proposed rule, NHTSA and 

EPA conducted a tire testing program to evaluate the tire rolling resistance of 156 

different tires across a wide range of truck applications. The results of the study indicate 

that the baseline tire rolling resistance of this segment of vehicles was better than the 

level assumed during the proposal. In the final action, therefore, the agencies made the 

vocational truck standards slightly more stringent than those included as part of the 

Preferred Alternative for the FEIS, reflecting the better overall performance of tires in 

this segment. In addition, the agencies have reduced the projected improvement in 

average tire performance from 10 percent to 5 percent, reflecting the better than expected 

baseline performance. NHTSA’s analysis indicates that the Agency’s Decision will 

 

574 NEPA is codified at 42 U.S.C. §§ 4321-47. CEQ NEPA implementing regulations are codified at 40 

Code of Federal Regulations (CFR) Parts 1500-08. 
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result in slightly less fuel savings and CO2 emissions reductions than those noted in the 

EIS.575 For environmental impacts associated with the final rule, see Sections VI.C and 

VII of this Final Rule.576

B. Alternatives Considered by NHTSA in Reaching its Decision, 

Including the Environmentally Preferable Alternative

When preparing an EIS, NEPA requires an agency to compare the potential 

environmental impacts of its proposed action and a reasonable range of alternatives. In 

the FEIS, NHTSA identified alternatives that represent the spectrum of potential actions 

the agency could take. The environmental impacts of these alternatives, in turn, represent 

the spectrum of potential environmental impacts that could result from NHTSA’s chosen 

action in setting fuel efficiency standards for HD vehicles. 

The FEIS analyzed the impacts of four “action” alternatives, each of which would 

separately regulate segments of the HD vehicle fleet.577 Three of the action alternatives 

(Alternatives 2, 3 and 4) would regulate the same vehicle categories, but at increasing 

levels of stringency, with Alternative 2 being the least stringent alternative and 

Alternative 4 being the most stringent. Alternatives 2 and 4 were constructed by starting 

with the Preferred Alternative (Alternative 3) and either removing the least cost effective 

technology in each of the vehicle categories or adding the next most cost effective 

technology in each of the vehicle categories.578 

Alternative 5 built on the Preferred Alternative by adding a performance standard 

for the commercial trailers pulled by tractors and by specifying more stringent standards 

based on accelerated adoption of hybrid powertrains for HD vehicles. The DEIS and 

FEIS also analyzed the impacts that would be expected if NHTSA adopted no HD vehicle 

standards (the No Action Alternative). For a discussion of the environmental impacts 

associated with each of the alternatives, see Chapters 3 and 4 of the FEIS.

Along with the FEIS, the agency conducted a national-scale photochemical air 

quality modeling and health risk assessment for a subset of the DEIS alternatives to 

 

575 The agencies’ analysis indicates that the change results in a decrease in total 2014-2050 fuel savings of 

about 1.05% percent compared to the Preferred Alternative modeled in the EIS and a corresponding 

increase in CO2 emissions.

576 The environmental impacts of this decision fall within the spectrum of impacts analyzed in the DEIS 

and the FEIS. There are no “substantial changes to the proposed action” and there are no “significant new 

circumstances or information relevant to environmental concerns and bearing on the proposed action or its 

impacts.” Therefore, consistent with 40 CFR § 1502.9(c), no supplement to the EIS is required.

577 In the DEIS, NHTSA analyzed several alternatives that applied only to specific components and/or 

segments of the HD vehicle fleet. Many commenters urged the agency to consider alternatives that applied 

to the entire HD vehicle fleet, reasoning that such an approach would be more consistent with EISA 

requirements. After careful consideration, NHTSA decided that those alternatives that would set standards 

for the whole fleet—that is, the engine as well as the entire vehicle for pickup trucks and vans, vocational 

vehicles, and tractors—best met the purpose and need for this action. It also allows for the achievement of 

the “maximum feasible improvement” in HD fuel efficiency. Therefore, the FEIS examined impacts 

associated with four of the action alternatives analyzed in the DEIS. 

578 See Section 2.3.2 of the FEIS.
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support and confirm the health effects and health-related economic estimates of the EIS. 

The photochemical air quality study is included as Appendix F to the FEIS. The study

used air quality modeling and health benefits analysis tools to quantify the air quality and 

health-related benefits associated with the alternative HD standards. 

NHTSA’s environmental analysis indicates that Alternative 5 (Trailers and 

Accelerated Hybrid) is the overall Environmentally Preferable Alternative because it 

would result in the largest reductions in fuel use and GHG emissions among the 

alternatives considered. Under each action alternative the agency considered, the 

reduction in fuel consumption resulting from higher fuel efficiency causes emissions that 

occur during fuel refining and distribution to decline. For most pollutants, this decline is 

more than sufficient to offset the increase in tailpipe emissions that results from increased 

driving due to the fuel efficiency rebound effect, leading to a net reduction in total 

emissions from fuel production, distribution, and use. Because it leads to the largest 

reductions in fuel refining, distribution, and consumption among the alternatives 

considered, Alternative 5 would also lead to the lowest total emissions of CO2 and other 

GHGs, as well as most criteria air pollutants and mobile source air toxics (MSATs).

579

NHTSA’s environmental analysis indicates that emissions of carbon monoxide 

(CO), acrolein, acetaldehyde, and formaldehyde are slightly (less than one percent)

higher under Alternative 5 than under some other action alternatives and analysis years. 

This occurs when increased tailpipe emissions are forecast to exceed the reductions in 

emissions due to reduced fuel refining and distribution. Thus, while Alternative 5 is the 

environmentally preferable alternative on the basis of CO2 and other GHGs, and on the 

basis of most criteria air pollutants and MSATs, other alternatives are environmentally

preferable from the standpoint of some criteria air pollutants and MSATs in some years. 

Overall, NHTSA considers Alternative 5 to be the Environmentally Preferable 

Alternative.

For additional discussion regarding the alternatives considered by the agency in 

reaching its decision, including the Environmentally Preferable Alternative, see Section 

IX of this Final Rule. For a discussion of the environmental impacts associated with each 

alternative, see Chapters 3 and 4 of the FEIS.

C. Factors Balanced by NHTSA in Making its Decision

For discussion of the factors balanced by NHTSA in making its decision, see 

Sections III, VIII and IX of this Final Rule.

 

579 Emissions of fine particulate matter (PM2.5) and diesel particulate matter (DPM) for Alternative 5 are 

forecast to be lower than under other action alternatives under all analysis years, but slightly higher than 

under the No Action Alternative in analysis years 2030 and 2050. See FEIS Tables 3.5.2-1 and 3.5.2-5. 

This anomaly results from the agencies’ assumptions regarding the percent of all long-haul tractors that use 

an APU rather than the truck’s engine as a power source during extended idling (discussed further in FEIS 

Section 3.2.4.1). 
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D. How the Factors and Considerations Balanced by NHTSA Entered 

into its Decision

For discussion of how the factors and considerations balanced by the agency

entered into NHTSA’s Decision, see Sections III, VIII and IX of this Final Rule.

E. The Agency’s Preferences among Alternatives Based on Relevant 

Factors, Including Economic and Technical Considerations and

Agency Statutory Missions

For discussion of the agency’s preferences among alternatives based on relevant 

factors, including economic and technical considerations, see Section VIII and IX of this 

Final Rule.

F. Mitigation

The CEQ regulations specify that a ROD must “state whether all practicable 

means to avoid or minimize environmental harm from the alternative selected have been 

adopted, and if not, why they were not.” 49 CFR § 1505.2(c). The majority of the 

environmental effects of NHTSA’s action are positive, i.e., beneficial environmental 

impacts, and would not raise issues of mitigation. Emissions of criteria and toxic air 

pollutants are generally projected to decrease under the final standards under all analysis 

years as compared to their levels under the No Action Alternative. Analysis of the 

environmental trends reported in the FEIS indicates that the only exceptions to this 

decline are emissions of PM2.5, DPM, and 1,3-butadiene in some analysis years. See 

Chapter 5 of the FEIS. The agency forecasts these emissions increases because, under all 

the alternatives analyzed in the EIS, increase in vehicle use due to improved fuel 

efficiency is projected to result in growth in total miles traveled by HD vehicles. The 

growth in travel outpaces emissions reductions for some pollutants, resulting in projected 

increases for these pollutants. In addition, NHTSA’s NEPA analysis predicted increases 

in emissions of air toxic and criteria pollutants to occur under certain alternatives based 

on assumptions about the use of Auxiliary Power Units (APUs). For example, NHTSA’s 

NEPA analysis assumes that some manufacturers will install anti-idling technologies 

(including APUs) on some vehicle classes to meet the requirements of the rule and that 

drivers’ subsequent use of those APUs will result in an increase in emissions of some 

criteria and toxic air pollutants.

NHTSA’s authority to promulgate new fuel efficiency standards for HD vehicles 

is limited and does not allow regulation of vehicle emissions or of factors affecting 

vehicle emissions, including driving habits and APU usage. Consequently, under the HD 

Fuel Efficiency Improvement Program, NHTSA must set standards but is unable to take 

steps to mitigate the impacts of these standards. Chapter 5 of the FEIS outlines a number 

of other initiatives across government that could ameliorate the environmental impacts of 

motor vehicle use, including the use of HD vehicles.
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XII. Statutory and Executive Order Reviews

(1) Executive Order 12866: Regulatory Planning and Review

Under section 3(f)(1) of Executive Order 12866 (58 FR 51735, October 4, 1993), 

this action is an “economically significant regulatory action” because it is likely to have 

an annual effect on the economy of $100 million or more. Accordingly, the agencies

submitted this action to the Office of Management and Budget (OMB) for review under 

Executive Order 12866 and any changes made in response to OMB recommendations 

have been documented in the docket for this action.

The agencies are also subject to Executive Order 13563 (76 FR 3821, January 21, 

2011) and NHTSA is subject to the Department of Transportation’s Regulatory Policies 

and Procedures. These final rules are also significant within the meaning of the DOT 

Regulatory Policies and Procedures. Executive Order 12866 additionally requires

NHTSA to submit this action to OMB for review and document any changes made in 

response to OMB recommendations.

In addition, the agencies prepared an analysis of the potential costs, fuel savings,

and benefits associated with this action. This analysis is contained in the Regulatory

Impact Analysis, which is available in the docket for these rules and at the docket internet 

address listed under ADDRESSES above and is briefly summarized in Table XII-1.

Table XII-1: Estimated Lifetime Discounted Costs, Benefits, and Net Benefits

for 2014-2018 Model Year HD Vehicles a,b (Billion 2009$)

Lifetime Present Valuec– 3% Discount Rate

Program Costs $8.1

Fuel Savings $50

Benefits $7.3

Net Benefitsd$49

Annualized Valuee– 3% Discount Rate

Annualized Costs $0.4

Fuel Savings $2.2

Annualized Benefits $0.4

Net Benefitsd$2.2

Lifetime Present Valuec- 7% Discount Rate

Program Costs $8.1

Fuel Savings $34

Benefits $6.7

Net Benefitsd$33

Annualized Valuee– 7% Discount Rate

Annualized Costs $0.6

Fuel Savings $2.6

Annualized Benefits $0.5

Net Benefitsd$2.5

Notes:
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a The agencies estimated the benefits associated with four different values of a one ton 

CO2 reduction (model average at 2.5% discount rate, 3%, and 5%; 95th percentile at 3%), 

which each increase over time. For the purposes of this overview presentation of 

estimated costs and benefits, however, we are showing the benefits associated with the 

marginal value deemed to be central by the interagency working group on this topic: the 

model average at 3% discount rate, in 2009 dollars. Section VIII.F provides a complete 

list of values for the 4 estimates.

b Note that net present value of reduced GHG emissions is calculated differently than

other benefits. The same discount rate used to discount the value of damages from future 

emissions (SCC at 5, 3, and 2.5 percent) is used to calculate net present value of SCC for 

internal consistency. Refer to Section VIII.F for more detail.

c

Present value is the total, aggregated amount that a series of monetized costs or benefits 

that occur over time is worth now (in year 2009 dollar terms), discounting future values 

to the present.

d Net benefits reflect the fuel savings plus benefits minus costs.

e The annualized value is the constant annual value through a given time period (2012 

through 2050 in this analysis) whose summed present value equals the present value from 

which it was derived.

(2) National Environmental Policy Act

Under NEPA, a Federal agency must prepare an Environmental Impact Statement 

(EIS) on proposed actions that could significantly impact the quality of the human 

environment. The requirement is designed to serve three major functions: (1) to provide 

the decisionmaker(s) with a detailed description of the potential environmental impacts of 

a proposed action prior to its adoption, (2) to rigorously explore and evaluate all 

reasonable alternatives, and (3) to inform the public of, and allow comment on, such 

efforts. 

In addition, the CEQ regulations emphasize agency cooperation early in the 

NEPA process and allow a lead agency (in this case, NHTSA) to request the assistance of 

other agencies that either have jurisdiction by law or have special expertise regarding

issues considered in an EIS.580 At NHTSA’s request, both EPA and the Federal Motor 

Carrier Safety Administration (FMCSA) agreed to act as cooperating agencies in the 

preparation of the EIS. EPA has special expertise in climate change and air quality, and 

FMCSA has special expertise regarding HD vehicles. 

NHTSA, in cooperation with EPA and FMCSA, prepared a DEIS, solicited public 

comments in writing and in public hearings, and prepared an FEIS responding to those 

comments. Specifically, in June 2010, NHTSA published a Notice of Intent to prepare an 

EIS for proposed HD fuel efficiency standards.581 See 40 CFR § 1501.7. On October 29, 

2010, EPA issued its Notice of Availability of the DEIS,582 triggering a public comment 

period. See 40 CFR § 1506.10. The public was invited to submit written comments on 

 

580 40 CFR § 1501.6.

581 See Notice of Intent to Prepare an Environmental Impact Statement for New Medium- and Heavy-Duty 

Fuel Efficiency Improvement Program, 75 FR 33565 (June 14, 2010).

582 Environmental Impact Statements; Notice of Availability, 75 FR 66756 (Oct. 29, 2010); NHTSA also 

published a separate Notice of Availability describing the program in greater detail, 75 FR 68312 (Nov. 5, 

2010). 
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the DEIS until January 3, 2011. NHTSA mailed (both electronically and through regular 

U.S. mail) copies of the DEIS to interested parties, including federal, state, and local 

officials and agencies; elected officials; environmental and public interest groups; Native 

American tribes; and other interested individuals. NHTSA and EPA held two hearings 

on the proposed rules and the EIS, the first on November 15, 2010 in Chicago, Illinois, 

and the second on November 18, 2010 in Cambridge, Massachusetts. 

NHTSA received 3,048 written comments to the DEIS and the NPRM. The 

transcript from the public hearing and written comments submitted to NHTSA are part of 

the administrative record and are available on the Federal Docket, which can be found 

online at http://www.regulations.gov, Reference Docket No. NHTSA-2010-0079. 

NHTSA reviewed and analyzed all comments received during the public comment period 

and revised the FEIS in response to comments on the EIS where appropriate.583 

On June 20, 2011, NHTSA submitted the FEIS to EPA. NHTSA also mailed 

(both electronically and through regular U.S. mail) the FEIS to interested parties and 

posted the FEIS on its website, http://www.nhtsa.gov/fuel-economy. On June 24, 2011, 

EPA published a Notice of Availability of the FEIS in the Federal Register.

584

 

The FEIS analyzes and discloses the potential environmental impacts of the 

proposed HD fuel efficiency standards pursuant to the National Environmental Policy

Act (NEPA), the CEQ regulations implementing NEPA, DOT Order 5610.1C, and 

NHTSA regulations.585 The FEIS compares the potential environmental impacts of 

alternative standards considered by NHTSA for the final rule. It also analyzes direct, 

indirect, and cumulative impacts and analyzes impacts in proportion to their significance. 

See the FEIS and the FEIS Summary for a discussion of the environmental impacts 

analyzed. Docket No. NHTSA-2011-0079.

The standards adopted in this Final Rule have been informed by analyses 

contained in the Medium- and Heavy-Duty Fuel Efficiency Improvement Program, Final 

Environmental Impact Statement, Docket No. NHTSA-2010-0079 (FEIS). For purposes 

of this rulemaking, the agency referred to an extensive compilation of technical and 

policy documents available in NHTSA’s EIS/Rulemaking docket and EPA’s docket. 

NHTSA’s EIS and rulemaking docket and EPA’s rulemaking docket can be found online

at http://www.regulations.gov, Reference Docket Nos.: NHTSA-2010-0079 (EIS and 

Rulemaking) and EPA-HQ-OAR-2010-0162 (EPA Rulemaking). 

Based on the foregoing, the agency concludes that the environmental analysis and 

public involvement process complies with NEPA implementing regulations issued by

CEQ, DOT Order 5610.1C, and NHTSA regulations.

 

583 The agency also changed the FEIS as a result of updated information that became available after 

issuance of the DEIS. 

584 76 FR 37111 (June 24, 2011).

585 NEPA is codified at 42 U.S.C. 4321-4347. CEQ NEPA implementing regulations are codified at 40 

Code of Federal Regulations (CFR) Parts 1500-1508. NHTSA NEPA implementing regulations are 

codified at 49 CFR Part 520. 
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(a) Clean Air Act (CAA)

The CAA (42 U.S.C. § 7401) is the primary Federal legislation that addresses air 

quality. Under the authority of the CAA and subsequent amendments, the EPA has 

established National Ambient Air Quality Standards (NAAQS) for six criteria pollutants, 

which are relatively commonplace pollutants that can accumulate in the atmosphere as a 

result of normal levels of human activity. The EPA is required to review each NAAQS 

every five years and to change the standards if warranted by new scientific information.

The air quality of a geographic region is usually assessed by comparing the levels 

of criteria air pollutants found in the atmosphere to the applicable NAAQS. 

Concentrations of criteria pollutants within the air mass of a region are measured in parts 

of a pollutant per million parts of air (ppm) or in micrograms of a pollutant per cubic 

meter (μg/m3) of air present in repeated air samples taken at designated monitoring 

locations. These ambient concentrations of each criteria pollutant are compared to the 

permissible levels specified by the NAAQS in order to assess whether the region’s air 

quality attains the standard.

When the measured concentrations of a criteria pollutant within a geographic 

region are below those permitted by the NAAQS, the region is designated by the EPA as 

an attainment area for that pollutant, while regions where concentrations of criteria 

pollutants exceed the NAAQS are called nonattainment areas (NAAs). Former NAAs 

that have attained the NAAQS are designated as maintenance areas. Each NAA is 

required to develop and implement a State Implementation Plan (SIP), which documents 

how the region will reach attainment levels within time periods specified in the CAA. In 

maintenance areas, the SIP documents how the State intends to maintain compliance with 

the NAAQS. When EPA changes a NAAQS, States must revise their SIPs to address 

how they will attain the new standard.

Section 176(c) of the CAA prohibits Federal agencies from taking actions in 

nonattainment or maintenance areas that do not “conform” to the State Implementation 

Plan (SIP). The purpose of this conformity requirement is to ensure that Federal activities 

do not interfere with meeting the emissions targets in the SIPs, do not cause or contribute 

to new violations of the NAAQS, and do not impede the ability to attain or maintain the 

NAAQS. The EPA has issued two sets of regulations to implement CAA Section 176(c):

 The Transportation Conformity Rules (40 CFR Part 93, Subpart A), which 

apply to transportation plans, programs, and projects funded or approved 

under U.S.C. Title 23 or the Federal Transit Laws (49 U.S.C. Chapter 53). 

Projects funded by the Federal Highway Administration (FHWA) or the 

Federal Transit Administration (FTA) usually are subject to transportation 

conformity. See 40 CFR § 93.102. 

 The General Conformity Rules (40 CFR Part 93, Subpart B) apply to all other 

federal actions not covered under transportation conformity. The General 

Conformity Rule established emissions thresholds, or de minimis levels, for 

use in evaluating the conformity of a project. If the net emissions increases 

attributable to the project are less than these thresholds, then the project is 
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presumed to conform and no further conformity evaluation is required. If the 

emissions increases exceed any of these thresholds, then a conformity

determination is required. The conformity determination can entail air quality

modeling studies, consultation with EPA and state air quality agencies, and 

commitments to revise the SIP or to implement measures to mitigate air 

quality impacts.

The final fuel consumption standards and associated program activities are not 

funded or approved under U.S.C. Title 23 or the Federal Transit Act. Further, NHTSA’s 

HD Fuel Efficiency Improvement Program is not a highway or transit project funded or 

approved by FHWA or FTA. Accordingly, the standards and associated rulemakings are 

not subject to transportation conformity.

Under the General Conformity Rule, a conformity determination is required 

where a Federal action would result in total direct and indirect emissions of a criteria 

pollutant or precursor equaling or exceeding the rates specified in 40 CFR § 93.153(b)(1) 

and (2) for nonattainment and maintenance areas. As explained below, NHTSA’s action 

results in neither direct nor indirect emissions as defined in 40 CFR § 93.152. 

The General Conformity Rule defines direct emissions as those of “a criteria 

pollutant or its precursors that are caused or initiated by the Federal action and originate 

in a nonattainment or maintenance area and occur at the same time and place as the action 

and are reasonably foreseeable.” 40 CFR § 93.152. Because NHTSA’s action only sets 

fuel consumption standards for HD vehicles, it causes no direct emissions within the 

meaning of the General Conformity Rule. 

Indirect emissions under the General Conformity Rule include emissions or 

precursors: (1) that are caused or initiated by the Federal action and originate in the same 

nonattainment or maintenance area but occur at a different time or place than the action; 

(2) that are reasonably foreseeable; (3) that the agency can practically control; and (4) for 

which the agency has continuing program responsibility. 40 CFR § 93.152. Each 

element of the definition must be met to qualify as an indirect emission. NHTSA has 

determined that, for the purposes of general conformity, emissions that occur as a result 

of the fuel consumption standards are not caused by NHTSA’s action, but rather occur 

due to subsequent activities that the agency cannot practically control. “[E]ven if a 

Federal licensing, rulemaking, or other approving action is a required initial step for a 

subsequent activity that causes emissions, such initial steps do not mean that a Federal 

agency can practically control any resulting emissions” (75 FR 17254, 17260; 40 CFR § 

93.152). NHTSA cannot control vehicle manufacturers’ production of HD vehicles and 

consumer purchasing and driving behavior. For the purposes of analyzing the 

environmental impacts of this action under NEPA, NHTSA has made assumptions 

regarding the technologies manufacturers will install and how companies will react to 

increased fuel efficiency standards. Specifically, NHTSA’s NEPA analysis predicted 

increases in air toxic and criteria pollutants to occur in some nonattainment areas under 

certain alternatives based on assumptions about the use of APUs and the rebound effect. 

For example, NHTSA’s NEPA analysis assumes that some manufacturers will install 

anti-idling technologies (including APUs) on some vehicle classes to meet the 
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requirements of the program and that drivers’ subsequent use of those APUs will result in 

an increase in some criteria pollutants. However, neither NHTSA’s nor EPA’s rules

mandate this specific manufacturer decision or driver behavior – the program does not 

require that manufacturers install APUs to meet the requirements of the rule, and it does 

not require drivers to use anti-idling technologies instead of, for example, shutting off all 

power when parked. Similarly, NHTSA’s NEPA analysis assumes a rebound effect, 

wherein the standards could create an incentive for additional vehicle use by reducing the 

cost of fuel consumed per mile driven. This rebound effect is an estimate of how 

NHTSA assumes some drivers will react to the rule and is useful for estimating the costs 

and benefits of the rule, but the agency does not have the statutory authority, or the 

program responsibility, to control, among other items discussed above, the actual vehicle 

miles traveled by drivers. Accordingly, changes in any emissions that result from 

NHTSA’s HD vehicle Fuel Efficiency Improvement Program are not changes that the 

agency can practically control; therefore, this action causes no indirect emissions and a 

general conformity determination is not required. 

(b) National Historic Preservation Act (NHPA)

The NHPA (16 U.S.C. § 470) sets forth government policy and procedures 

regarding “historic properties”—that is, districts, sites, buildings, structures, and objects 

included in or eligible for the National Register of Historic Places (NRHP). See also 36 

CFR Part 800. Section 106 of the NHPA requires federal agencies to “take into account” 

the effects of their actions on historic properties. The agency concludes that the NHPA is 

not applicable to NHTSA’s Decision because it does not directly involve historic 

properties. The agency has, however, conducted a qualitative review of the related direct, 

indirect, and cumulative impacts, positive or negative, of the alternatives on potentially

affected resources, including historic and cultural resources. See Section 4.5 of the FEIS.

(c) Executive Order 12898 (Environmental Justice)

Under Executive Order 12898, Federal agencies are required to identify and 

address any disproportionately high and adverse human health or environmental effects 

of its programs, policies, and activities on minority populations and low-income 

populations. NHTSA complied with this order by identifying and addressing the 

potential effects of the alternatives on minority and low-income populations in Sections

3.6 and 4.6 of the FEIS, where the agency set forth a qualitative analysis of the 

cumulative effects of the alternatives on these populations. 

(d) Fish and Wildlife Conservation Act (FWCA)

The FWCA (16 U.S.C. § 2900) provides financial and technical assistance to 

States for the development, revision, and implementation of conservation plans and 

programs for nongame fish and wildlife. In addition, the Act encourages all Federal 

agencies and departments to utilize their authority to conserve and to promote 

conservation of nongame fish and wildlife and their habitats. The agency concludes that 

the FWCA is not applicable to NHTSA’s Decision because it does not directly involve 

fish and wildlife. 
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(e) Coastal Zone Management Act (CZMA)

The Coastal Zone Management Act (16 U.S.C. § 1450) provides for the 

preservation, protection, development, and (where possible) restoration and enhancement 

of the nation’s coastal zone resources. Under the statute, States are provided with funds 

and technical assistance in developing coastal zone management programs. Each 

participating State must submit its program to the Secretary of Commerce for approval. 

Once the program has been approved, any activity of a Federal agency, either within or 

outside of the coastal zone, that affects any land or water use or natural resource of the 

coastal zone must be carried out in a manner that is consistent, to the maximum extent 

practicable, with the enforceable policies of the State’s program. 

The agency concludes that the CZMA is not applicable to NHTSA’s Decision 

because it does not involve an activity within, or outside of, the nation’s coastal zones. 

The agency has, however, conducted a qualitative review of the related direct, indirect, 

and cumulative impacts, positive or negative, of the alternatives on potentially affected 

resources, including coastal zones. See Section 4.5 of the FEIS. 

(f) Endangered Species Act (ESA)

Under Section 7(a)(2) of the Endangered Species Act (ESA) federal agencies 

must ensure that actions they authorize, fund, or carry out are “not likely to jeopardize” 

federally listed threatened or endangered species or result in the destruction or adverse 

modification of the designated critical habitat of these species. 16 U.S.C. § 1536(a)(2). 

If a federal agency determines that an agency action may affect a listed species or 

designated critical habitat, it must initiate consultation with the appropriate Service – the 

U.S. Fish and Wildlife Service (FWS) of the Department of the Interior and/ or National 

Oceanic and Atmospheric Administration’s National Marine Fisheries Service (NOAA 

Fisheries Service) of the Department of Commerce, depending on the species involved—

in order to ensure that the action is not likely to jeopardize the species or destroy or 

adversely modify designated critical habitat. See 50 CFR § 402.14. Under this standard, 

the federal agency taking action evaluates the possible effects of its action and determines 

whether to initiate consultation. See 51 FR 19926, 19949 (Jun. 3, 1986). 

NHTSA received one comment to the Scoping notice for the HD program 

indicating that the agency should engage in consultation under Section 7 of the ESA 

when analyzing the overall impact of GHG emissions and other air pollutants. NHTSA 

has reviewed applicable ESA regulations, case law, guidance, and rulings in assessing the 

potential for impacts to threatened and endangered species from the HD fuel efficiency

standards. Consistent with NHTSA’s determination under the agency’s most recent lightduty fuel economy rule, NHTSA believes that the agency’s action, which will result in 

nationwide fuel savings and, consequently, emissions reductions from what would 

otherwise occur in the absence of the agency’s action, does not require consultation with 

NOAA Fisheries Service or the FWS under Section 7(a)(2) of the ESA. For discussion of 

the agency’s rationale in the context of the CAFE program, see Appendix G of the FEIS

for MYs 2012-2016, available at: http://www.nhtsa.gov/fuel-economy. Accordingly, 

NHTSA has concluded its review of this action under Section 7 of the ESA. 
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(g) Floodplain Management (Executive Order 11988 & DOT Order 5650.2)

These Orders require Federal agencies to avoid the long- and short-term adverse 

impacts associated with the occupancy and modification of floodplains, and to restore 

and preserve the natural and beneficial values served by floodplains. Executive Order 

11988 also directs agencies to minimize the impact of floods on human safety, health and 

welfare, and to restore and preserve the natural and beneficial values served by

floodplains through evaluating the potential effects of any actions the agency may take in 

a floodplain and ensuring that its program planning and budget requests reflect 

consideration of flood hazards and floodplain management. DOT Order 5650.2 sets forth 

DOT policies and procedures for implementing Executive Order 11988. The DOT Order 

requires that the agency determine if a proposed action is within the limits of a base 

floodplain, meaning it is encroaching on the floodplain, and whether this encroachment is 

significant. If significant, the agency is required to conduct further analysis of the 

proposed action and any practicable alternatives. If a practicable alternative avoids 

floodplain encroachment, then the agency is required to implement it. 

In this rulemaking, the agency is not occupying, modifying and/or encroaching on 

floodplains. The agency, therefore, concludes that the Orders are not applicable to 

NHTSA’s Decision. The agency has, however, conducted a review of the alternatives on 

potentially affected resources, including floodplains. See Section 4.5 of the FEIS.

(h) Preservation of the Nation’s Wetlands (Executive Order 11990 & DOT Order 

5660.1a)

These Orders require Federal agencies to avoid, to the extent possible, 

undertaking or providing assistance for new construction located in wetlands unless the 

agency head finds that there is no practicable alternative to such construction and that the 

proposed action includes all practicable measures to minimize harms to wetlands that 

may result from such use. Executive Order 11990 also directs agencies to take action to 

minimize the destruction, loss or degradation of wetlands in “conducting Federal 

activities and programs affecting land use, including but not limited to water and related 

land resources planning, regulating, and licensing activities.” DOT Order 5660.1a sets 

forth DOT policy for interpreting Executive Order 11990 and requires that transportation 

projects “located in or having an impact on wetlands” should be conducted to assure 

protection of the Nation’s wetlands. If a project does have a significant impact on 

wetlands, an EIS must be prepared.

The agency is not undertaking or providing assistance for new construction 

located in wetlands. The agency, therefore, concludes that these Orders do not apply to 

NHTSA’s Decision. The agency has, however, conducted a review of the alternatives on 

potentially affected resources, including wetlands. See Section 4.5 of the FEIS.
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(i) Migratory Bird Treaty Act (MBTA), Bald and Golden Eagle Protection Act 

(BGEPA), Executive Order 13186

The MBTA provides for the protection of migratory birds that are native to the 

United States by making it illegal for anyone to pursue, hunt, take, attempt to take, kill, 

capture, collect, possess, buy, sell, trade, ship, import, or export any migratory bird 

covered under the statute. The statute prohibits both intentional and unintentional acts. 

Therefore, the statute is violated if an agency acts in a manner that harms a migratory

bird, whether it was intended or not. See, e.g., United States v. FMC Corp., 572 F.2d 902 

(2nd Cir. 1978).

The BGEPA (16 U.S.C. § 668) prohibits any form of possession or taking of both 

bald and golden eagles. Under the BGEPA, violators are subject to criminal and civil 

sanctions as well as an enhanced penalty provision for subsequent offenses.

Executive Order 13186, “Responsibilities of Federal Agencies to Protect 

Migratory Birds,” helps to further the purposes of the MBTA by requiring a Federal 

agency to develop a Memorandum of Understanding (MOU) with the Fish and Wildlife 

Service when it is taking an action that has (or is likely to have) a measurable negative 

impact on migratory bird populations.

The agency concludes that the MBTA, BGEPA, and Executive Order 13186 do 

not apply to NHTSA’s Decision because there is no disturbance and/or take involved in 

NHTSA’s Decision. 

(j) Department of Transportation Act (Section 4(f))

Section 4(f) of the Department of Transportation Act of 1966 (49 U.S.C. § 303), 

as amended by Pub. Law § 109-59, is designed to preserve publicly owned parklands, 

waterfowl and wildlife refuges, and significant historic sites. Specifically, Section 4(f) of 

the Department of Transportation Act provides that DOT agencies cannot approve a 

transportation program or project that requires the use of any publicly owned land from a 

significant public park, recreation area, or wildlife and waterfowl refuge, or any land 

from a significant historic site, unless a determination is made that: 

 There is no feasible and prudent alternative to the use of land, and 

 The program or project includes all possible planning to minimize harm to the 

property resulting from use, or

 A transportation use of Section 4(f) property results in a de minimis impact. 

The agency concludes that the Section 4(f) is not applicable to NHTSA’s 

Decision because this rulemaking does not require the use of any publicly owned land. 

For a more detailed discussion, please see Section 3.1 of the FEIS.
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(3) Paperwork Reduction Act

The information collection requirements in these rules have been submitted for 

approval to OMB under the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. The 

information collection requirements are not enforceable until OMB approves them.

The agencies propose to collect information to ensure compliance with the 

provisions in these rules. This includes a variety of testing, reporting and recordkeeping

requirements for vehicle manufacturers. Section 208(a) of the CAA requires that vehicle 

manufacturers provide information the Administrator may reasonably require to 

determine compliance with the regulations; submission of the information is therefore 

mandatory. We will consider confidential all information meeting the requirements of 

section 208(c) of the CAA. 

It is estimated that this collection affects approximately 34 engine and vehicle 

manufacturers. The information that is subject to this collection is collected whenever a 

manufacturer applies for a certificate of conformity. Under section 206 of the CAA (42 

U.S.C. 7521), a manufacturer must have a certificate of conformity before a vehicle or 

engine can be introduced into commerce. 

The burden to the manufacturers affected by these rules has a range based on the 

number of engines and vehicles a manufacturer produces. The total estimated burden 

associated with these rules is 58,064 hours annually (See Table XII-2). This estimated 

burden for engine and vehicle manufacturers is a total estimate for new reporting 

requirements. Burden is defined at 5 CFR 1320.3(b).

Table XII-2: Burden for Reporting and Recordkeeping Requirements

Number of Affected Manufacturers 34

Annual Labor Hours for Each Manufacturer to Prepare and Submit 

Required Information

Varies 

Total Annual Information Collection Burden 58,064 Hours 

An agency may not conduct or sponsor, and a person is not required to respond to 

a collection of information unless it displays a currently valid OMB control number. The 

OMB control numbers for EPA’s regulations are listed in 40 CFR part 9. When this ICR 

is approved by OMB, the agency will publish a technical amendment to 40 CFR part 9 in 

the Federal Register to display the OMB control number for the approved information 

collection requirements contained in this final action.

(4) Regulatory Flexibility Act

(a) Overview

The Regulatory Flexibility Act generally requires an agency to prepare a 

regulatory flexibility analysis of any rule subject to notice and comment rulemaking 

requirements under the Administrative Procedure Act or any other statute unless the 

agency certifies that the rule will not have a significant economic impact on a substantial 
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number of small entities. Small entities include small businesses, small organizations, 

and small governmental jurisdictions.

For purposes of assessing the impacts of these rules on small entities, small entity

is defined as: (1) a small business as defined by SBA regulations at 13 CFR 121.201; (2) 

a small governmental jurisdiction that is a government of a city, county, town, school 

district or special district with a population of less than 50,000; and (3) a small 

organization that is any not-for-profit enterprise which is independently owned and 

operated and is not dominant in its field.

(b) Summary of Potentially Affected Small Entities

The agencies have not conducted a Regulatory Flexibility Analysis for this action

because the agencies are certifying that these rules would not have a significant economic 

impact on a substantial number of small entities. As proposed, the agencies are deferring

standards for manufacturers meeting SBA’s definition of small business as described in 

13 CFR 121.201 due to the extremely small fuel savings and emissions contribution of 

these entities, and the short lead time to develop these rules, especially with our

expectation that the program would need to be structured differently for them (which 

would require more time). The agencies are instead envisioning fuel consumption and 

GHG emissions standards for these entities as part of a future regulatory action. This 

includes small entities in several distinct categories of businesses for heavy-duty engines 

and vehicles: chassis manufacturers, combination tractor manufacturers, and alternative 

fuel engine converters. 

Based on a preliminary assessment, the agencies have identified a total of about 

17 engine manufacturers, 3 complete pickup truck and van manufacturers, 11 

combination tractor manufacturers and 43 heavy-duty chassis manufacturers. Notably, 

several of these manufacturers produce vehicles in more than just one regulatory category

(HD pickup trucks/vans, combination tractors, or vocational vehicles (i.e. heavy-duty 

chassis manufacturers)). Based on the types of vehicles they manufacture, these 

companies, however, would be subject to slightly different testing and reporting 

requirements. Taking this feature of the heavy-duty trucking sector into account, the 

agencies estimate that although there are fewer than 30 manufacturers covered by the 

program, there close to 60 divisions with these companies that will be subject to the final

regulations. Of these, about 15 entities fit the SBA criteria of a small business. There are 

approximately three engine converters, two tractor manufacturers, and ten heavy-duty 

chassis manufacturers in the heavy-duty engine and vehicle market that are small 

businesses. (No major heavy-duty engine manufacturers, heavy-duty chassis 

manufacturers, or tractor manufacturers meet the small-entity criteria as defined by

SBA). The agencies estimate that these small entities comprise less than 0.35 percent of 

the total heavy-duty vehicle sales in the United States, and therefore the deferment will 

have a negligible impact on the fuel consumption and GHG emissions reductions from 

the final standards. 

To ensure that the agencies are aware of which companies are being deferred, the 

agencies are requiring that such entities submit a declaration to the agencies containing a 
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detailed written description of how that manufacturer qualifies as a small entity under the 

provisions of 13 CFR 121.201. Some small entities, such as heavy-duty tractor and 

chassis manufacturers, are not currently covered under criteria pollutant motor vehicle 

emissions regulations. Small engine entities are currently covered by a number of EPA 

motor vehicle emission regulations, and they routinely submit information and data on an 

annual basis as part of their compliance responsibilities. Because such entities are not 

automatically exempted from other EPA regulations for heavy-duty engines and vehicles, 

absent such a declaration, EPA would assume that the entity was subject to the 

greenhouse gas control requirements in this program. The declaration to the agencies 

will need to be submitted at the time of either engine or vehicle emissions certification 

under the HD highway engine program for criteria pollutants. The agencies expect that 

the additional paperwork burden associated with completing and submitting a small 

entity declaration to gain deferral from the final GHG and fuel consumption standards 

will be negligible and easily done in the context of other routine submittals to the 

agencies. However, the agencies have accounted for this cost with a nominal estimate 

included in the Information Collection Request completed under the Paperwork 

Reduction Act. Additional information can be found in the Paperwork Reduction Act 

discussion in Section XII. (3) Paperwork Reduction Act. Based on this, the agencies are

certifying that the rules will not have a significant economic impact on a substantial 

number of small entities. 

(5) Unfunded Mandates Reform Act

Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Pub. L. 104-4, 

establishes requirements for Federal agencies to assess the effects of their regulatory

actions on State, local, and tribal governments and the private sector. Under section 202 

of the UMRA, the agencies generally must prepare a written statement, including a costbenefit analysis, for proposed and final rules with “Federal mandates” that may result in 

expenditures to State, local, and tribal governments, in the aggregate, or to the private 

sector, of $100 million or more in any one year. Before promulgating a rule for which a 

written statement is needed, section 205 of the UMRA generally requires the agencies to 

identify and consider a reasonable number of regulatory alternatives and adopt the least 

costly, most cost-effective or least burdensome alternative that achieves the objectives of 

the rule. The provisions of section 205 do not apply when they are inconsistent with 

applicable law. Moreover, section 205 allows the agencies to adopt an alternative other 

than the least costly, most cost-effective or least burdensome alternative if the 

Administrator (of either agency) publishes with the final rule an explanation why that 

alternative was not adopted. 

Before the agencies establish any regulatory requirements that may significantly

or uniquely affect small governments, including tribal governments, they must have 

developed under section 203 of the UMRA a small government agency plan. The plan 

must provide for notifying potentially affected small governments, enabling officials of 

affected small governments to have meaningful and timely input in the development of 

EPA and NHTSA regulations with significant Federal intergovernmental mandates, and 

informing, educating, and advising small governments on compliance with the regulatory

requirements. 
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These rules contain no Federal mandates (under the regulatory provisions of Title 

II of the UMRA) for State, local, or tribal governments. The rules impose no enforceable 

duty on any State, local or tribal governments. The agencies have determined that these 

rules contain no regulatory requirements that might significantly or uniquely affect small 

governments. The agencies have determined that these rules contain a Federal mandate 

that may result in expenditures of $134 million or more for the private sector in any one 

year. The agencies believe that the program represents the least costly, most costeffective approach to achieve the statutory requirements of the rules. Section VIII.L, 

above, explains why the agencies believe that the fuel savings that will result from these 

rules will lead to lower prices economy-wide, improving U.S. international 

competitiveness. The costs and benefits associated with the program are discussed in 

more detail above in Section VIII and in the Regulatory Impact Analysis, as required by 

the UMRA.

Table XII-1, above, presents the rule-related benefits, fuel savings, costs and net 

benefits in both present value terms and in annualized terms. In both cases, the 

discounted values are based on an underlying time varying stream of cost and benefit 

values that extend into the future (2012 through 2050). The distribution of each 

monetized economic impact over time can be viewed in the RIA that accompanies these 

rules. 

Present values represent the total amount that a stream of monetized 

costs/benefits/net benefits that occur over time are worth now (in year 2009 dollar terms

for this analysis), accounting for the time value of money by discounting future values 

using either a 3 or 7 percent discount rate, per OMB Circular A-4 guidance. An 

annualized value takes the present value and converts it into a constant stream of annual 

values through a given time period (2012 through 2050 in this analysis) and thus averages 

(in present value terms) the annual values. The present value of the constant stream of 

annualized values equals the present value of the underlying time varying stream of 

values. The ratio of benefits to costs is identical whether it is measured with present 

values or annualized values. 

It is important to note that annualized values cannot simply be summed over time 

to reflect total costs/benefits/net benefits; they must be discounted and summed. 

Additionally, the annualized value can vary substantially from the time varying stream of 

cost/benefit/net benefit values that occur in any given year. 

(6) Executive Order 13132 (Federalism)

This action does not have federalism implications. It will not have substantial 

direct effects on the States, on the relationship between the national government and the 

States, or on the distribution of power and responsibilities among the various levels of 

government, as specified in Executive Order 13132. These rules will apply to 

manufacturers of motor vehicles and not to state or local governments. Thus, Executive 

Order 13132 does not apply to this action. Although section 6 of Executive Order 13132 

does not apply to this action, the agencies did consult with representatives of state 

governments in developing this action.
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NHTSA notes that EPCA contains a provision (49 U.S.C. 32919(a)) that 

expressly preempts any State or local government from adopting or enforcing a law or 

regulation related to fuel economy standards or average fuel economy standards for 

automobiles covered by an average fuel economy standard under 49 U.S.C. Chapter 329. 

However, commercial medium- and heavy-duty on-highway vehicles and work trucks are 

not “automobiles,” as defined in 49 U.S.C. 32901(a)(3). Accordingly, NHTSA has 

tentatively concluded that EPCA’s express preemption provision would not reach the fuel 

efficiency standards to be established in this rulemaking. 

NHTSA also considered the issue of implied or conflict preemption. The 

possibility of such preemption is dependent upon there being an actual conflict between a 

standard established by NHTSA in this rulemaking and a State or local law or regulation. 

See Spriestma v. Mercury Marine, 537 U.S. 51, 64-65 (2002). At present, NHTSA has 

no knowledge of any State or local law or regulation that would actually conflict with one 

of the fuel efficiency standards being established in this rulemaking. 

(7) Executive Order 13175 (Consultation and Coordination with Indian Tribal 

Governments)

These final rules do not have tribal implications, as specified in Executive Order 

13175 (65 FR 67249, November 9, 2000). These rules will be implemented at the 

Federal level and impose compliance costs only on vehicle manufacturers. Tribal 

governments would be affected only to the extent they purchase and use regulated 

vehicles. Thus, Executive Order 13175 does not apply to these rules.

(8) Executive Order 13045: “Protection of Children from Environmental 

Health Risks and Safety Risks”

This action is subject to Executive Order 13045 (62 FR 19885, April 23, 1997) 

because it is an economically significant regulatory action as defined by Executive Order

12866, and the agencies believe that the environmental health or safety risk addressed by 

this action may have a disproportionate effect on children. A synthesis of the science and 

research regarding how climate change may affect children and other vulnerable 

subpopulations is contained in the Technical Support Document for Endangerment or 

Cause or Contribute Findings for Greenhouse Gases under section 202(a) of the Clean 

Air Act, which can be found in the public docket for these rules.

586

 A summary of the 

analysis is presented below.

With respect to GHG emissions, the effects of climate change observed to date 

and projected to occur in the future include the increased likelihood of more frequent and 

intense heat waves. Specifically, EPA’s analysis of the scientific assessment literature has 

determined that severe heat waves are projected to intensify in magnitude, frequency, and 

duration over the portions of the United States where these events already occur, with 

potential increases in mortality and morbidity, especially among the young, elderly, and 

frail. EPA has estimated reductions in projected global mean surface temperatures as a 

result of reductions in GHG emissions associated with the final standards in this action 

 

586 See Endangerment TSD, Note 10, above.
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(Section II). Children may receive benefits from reductions in GHG emissions because 

they are included in the segment of the population that is most vulnerable to extreme 

temperatures.

For non-GHG pollutants, EPA has determined that climate change is expected to 

increase regional ozone pollution, with associated risks in respiratory infection, 

aggravation of asthma, and premature death. The directional effect of climate change on 

ambient PM levels remains uncertain. However, disturbances such as wildfires are 

increasing in the United States and are likely to intensify in a warmer future with drier 

soils and longer growing seasons. PM emissions from forest fires can contribute to acute 

and chronic illnesses of the respiratory system, particularly in children, including 

pneumonia, upper respiratory diseases, asthma and chronic obstructive pulmonary

diseases.

(9) Executive Order 13211 (Energy Effects)

This rulemaking is not a “significant energy action” as defined in Executive Order 

13211, “Actions Concerning Regulations That Significantly Affect Energy Supply, 

Distribution, or Use” (66 FR 28355, May 22, 2001) because it is not likely to have a 

significant adverse effect on the supply, distribution, or use of energy. In fact, these rules

have a positive effect on energy supply and use. Because the final GHG emission and 

fuel consumption standards will result in significant fuel savings, these rules encourage 

more efficient use of fuels. Therefore, we have concluded that these rules are not likely

to have any adverse energy effects. Our energy effects analysis is described above in 

Section VIII.I.

(10) National Technology Transfer Advancement Act

Section 12(d) of the National Technology Transfer and Advancement Act of 1995 

(“NTTAA”), Public Law No. 104-113, 12(d) (15 U.S.C. 272 note) directs the agencies to 

use voluntary consensus standards in its regulatory activities unless to do so would be 

inconsistent with applicable law or otherwise impractical. Voluntary consensus standards 

are technical standards (e.g., materials, specifications, test methods, sampling procedures, 

and business practices) that are developed or adopted by voluntary consensus standards 

bodies. NTTAA directs the agencies to provide Congress, through OMB, explanations 

when the agencies decide not to use available and applicable voluntary consensus 

standards.

For CO2, N2O, and CH4 emissions and fuel consumption from heavy-duty 

engines, the agencies will collect data over the same tests that are used for the heavy-duty 

highway engine program for criteria pollutants. This will minimize the amount of testing 

done by manufacturers, since manufacturers are already required to run these tests. 

For CO2, N2O, and CH4 emissions and fuel consumption from complete pickup 

trucks and vans, the agencies will collect data over the same tests that are used for EPA’s

heavy-duty highway engine program for criteria pollutants and for the California Air 

Resources Board. This will minimize the amount of testing done by manufacturers, since 

manufacturers are already required to run these tests.
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For CO2 emissions and fuel consumption from heavy-duty combination tractors 

and vocational vehicles, the agencies will collect data through the use of a simulation 

model instead of a full-vehicle chassis dynamometer testing. This will minimize the 

amount of testing done by manufacturers. EPA’s compliance assessment tool is based 

upon well-established engineering and physics principals that are the basis of general 

academic understanding in this area, and the foundation of any dynamic vehicle 

simulation model, including the models cited by ICCT in its study.

587

 Therefore, the 

EPA’s compliance assessment tool satisfies the description of a consensus. For the 

evaluation of tire rolling resistance input to the model, EPA is finalizing to use the ISO 

28580 test, a voluntary consensus methodology. EPA is adopting several alternatives for 

the evaluation of aerodynamics which allows the industry to continue to use their own 

evaluation tools because EPA does not know of a single consensus standard available for 

heavy-duty truck aerodynamic evaluation.

For air conditioning standards, EPA is finalizing a consensus methodology

developed by the Society of Automotive Engineers (SAE). 

(11) Executive Order 12898: Federal Actions to Address Environmental 

Justice in Minority Populations and Low-Income Populations

Executive Order 12898 (59 FR 7629, February 16, 1994) establishes federal 

executive policy on environmental justice. Its main provision directs federal agencies, to 

the greatest extent practicable and permitted by law, to make environmental justice part 

of their mission by identifying and addressing, as appropriate, disproportionately high 

and adverse human health or environmental effects of their programs, policies, and 

activities on minority populations and low-income populations in the United States. 

With respect to GHG emissions, EPA has determined that these final rules will 

not have disproportionately high and adverse human health or environmental effects on 

minority or low-income populations because they increase the level of environmental 

protection for all affected populations without having any disproportionately high and 

adverse human health or environmental effects on any population, including any minority 

or low-income population. The reductions in CO2 and other GHGs associated with the 

standards will affect climate change projections, and EPA has estimated reductions in 

projected global mean surface temperatures (Section VI). Within communities 

experiencing climate change, certain parts of the population may be especially

vulnerable; these include the poor, the elderly, those already in poor health, the disabled, 

those living alone, and/or indigenous populations dependent on one or a few resources.588 

In addition, the U.S. Climate Change Science Program stated as one of its conclusions: 

“The United States is certainly capable of adapting to the collective impacts of climate 

change. However, there will still be certain individuals and locations where the adaptive 

capacity is less and these individuals and their communities will be disproportionally

 

587 ICCT. ICCT Evaluation of Vehicle Simulation Tools. 2009. 

588 See Endangerment TSD, Note 10, above.
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impacted by climate change.” 589 Therefore, these specific sub-populations may receive 

benefits from reductions in GHGs. 

For non-GHG co-pollutants such as ozone, PM2.5, and toxics, EPA has concluded 

that it is not practicable to determine whether there would be disproportionately high and 

adverse human health or environmental effects on minority and/or low income 

populations from these rules. 

(12) Congressional Review Act

The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the Small 

Business Regulatory Enforcement Fairness Act of 1996, generally provides that before a 

rule may take effect, the agency promulgating the rule must submit a rule report, which 

includes a copy of the rule, to each House of the Congress and to the Comptroller 

General of the United States. The agencies will submit a report containing these rules

and other required information to the U.S. Senate, the U.S. House of Representatives, and 

the Comptroller General of the United States prior to publication of the rules in the 

Federal Register. A Major rule cannot take effect until 60 days after it is published in the 

Federal Register. This action is a “major rule” as defined by 5 U.S.C. 804(2). These rules 

will be effective [Insert date 60 days after publication in the Federal Register], sixty

days after date of publication in the Federal Register.

(13) Privacy Act

Anyone is able to search the electronic form of all comments received into any of 

our dockets by the name of the individual submitting the comment (or signing the 

comment, if submitted on behalf of an organization, business, labor union, etc.). You may

review DOT’s complete Privacy Act statement in the Federal Register (65 FR 19477–78, 

April 11, 2000) or you may visit http://www.dot.gov/privacy.html.

XIII. Statutory Provisions and Legal Authority

A. EPA

Statutory authority for the vehicle controls in these rules is found in CAA section 

202(a) (which requires EPA to establish standards for emissions of pollutants from new 

motor vehicles and engines which emissions cause or contribute to air pollution which 

may reasonably be anticipated to endanger public health or welfare), sections 202(d), 

203-209, 216, and 301 of the CAA, 42 U.S.C. 7521 (a), 7521 (d), 7522, 7523, 7524, 

7525, 7541, 7542, 7543, 7550, and 7601.

 

589 CCSP (2008) Analyses of the effects of global change on human health and welfare and human systems. 

A Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research. 

[Gamble, J.L. (ed.), K.L. Ebi, F.G. Sussman, T.J. Wilbanks, (Authors)]. U.S. Environmental Protection 

Agency, Washington, DC, USA.
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B. NHTSA

Statutory authority for the fuel consumption standards in these rules is found in 

EISA section 103 (which authorizes a fuel efficiency improvement program, designed to 

achieve the maximum feasible improvement to be created for commercial medium- and 

heavy-duty on-highway vehicles and work trucks, to include appropriate test methods, 

measurement metrics, standards, and compliance and enforcement protocols that are 

appropriate, cost-effective and technologically feasible) of the Energy Independence and 

Security Act of 2007, 49 U.S.C. 32902(k).

List of Subjects

40 CFR Part 85

Confidential business information, Imports, Labeling, Motor vehicle pollution, Reporting 

and recordkeeping requirements, Research, Warranties.

40 CFR Part 86

Administrative practice and procedure, Confidential business information, Incorporation 

by reference, Labeling, Motor vehicle pollution, Reporting and recordkeeping 

requirements.

40 CFR Part 600

Administrative practice and procedure, Electric power, Fuel economy, Incorporation by

reference, Labeling, Reporting and recordkeeping requirements.

40 CFR Parts 1033

Administrative practice and procedure, Air pollution control.

40 CFR Parts 1036 and 1037

Administrative practice and procedure, Air pollution control, Confidential business 

information, Environmental protection, Incorporation by reference, Labeling, Motor 

vehicle pollution, Reporting and recordkeeping requirements, Warranties.

40 CFR Part 1039

Environmental protection, Administrative practice and procedure, Air pollution control, 

Confidential business information, Imports, Labeling, Penalties, Reporting and 

recordkeeping requirements, Warranties.

40 CFR Parts 1065 and 1066

Administrative practice and procedure, Air pollution control, Reporting and 

recordkeeping requirements, Research.

40 CFR Part 1068

Environmental protection, Administrative practice and procedure, Confidential business 

information, Imports, Incorporation by reference, Motor vehicle pollution, Penalties, 

Reporting and recordkeeping requirements, Warranties.
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49 CFR Parts 523, 534, and 535

Fuel Efficiency

Environmental Protection Agency

40 CFR Chapter I

For the reasons set forth in the preamble, the Environmental Protection Agency is 

amending 40 CFR chapter I of the Code of Federal Regulations as follows: 

PART 85-- CONTROL OF AIR POLLUTION FROM MOBILE SOURCES

1. The authority citation for part 85 continues to read as follows:

Authority: 42 U.S.C. 7401-7671q.

Subpart F—[Amended]

2. Section 85.525 is revised to read as follows:

§ 85.525 Applicable standards.

To qualify for an exemption from the tampering prohibition, vehicles/engines that have 

been converted to operate on a different fuel must meet emission standards and related 

requirements as follows:

(a) The modified vehicle/engine must meet the requirements that applied for the OEM 

vehicle/engine, or the most stringent OEM vehicle/engine standards in any allowable 

grouping. Fleet average standards do not apply unless clean alternative fuel conversions 

are specifically listed as subject to the standards.

(1) If the vehicle/engine was certified with a Family Emission Limit for NOX, 

NOX+HC, or particulate matter, as noted on the vehicle/engine emission control 

information label, the modified vehicle/engine may not exceed this Family Emission 

Limit.

(2) Compliance with greenhouse gas emission standards is demonstrated as follows:

(i) Subject to the following exceptions and special provisions, compliance with 

light-duty vehicle greenhouse gas emission standards is demonstrated by

complying with the N2O and CH4 standards and provisions set forth in 40 CFR 

86.1818–12(f)(1) and the in-use CO2 exhaust emission standard set forth in 40 

CFR 86.1818–12(d) as determined by the OEM for the subconfiguration that is 

identical to the fuel conversion emission data vehicle (EDV). 

(A) If the OEM complied with the light-duty greenhouse gas standards using 

the fleet averaging option for N2O and CH4, as allowed under 40 CFR 

86.1818–12(f)(2), the calculations of the carbon-related exhaust emissions 
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require the input of grams/mile values for N2O and CH4, and you are not 

required to demonstrate compliance with the standalone CH4 and N2O 

standards. 

(B) If the OEM complied with alternate standards for N2O and/or CH4, as 

allowed under 40 CFR 86.1818–12(f)(3), you may demonstrate compliance 

with the same alternate standards.

(C) If the OEM complied with the nitrous oxide (N2O) and methane (CH4) 

standards and provisions set forth in 40 CFR 86.1818–12(f)(1) or 40 CFR 

86.1818–12(f)(3), and the fuel conversion CO2 measured value is lower than 

the in-use CO2 exhaust emission standard, you also have the option to convert 

the difference between the in-use CO2 exhaust emission standard and the fuel 

conversion CO2 measured value into GHG equivalents of CH4 and/or N2O, 

using 298 g CO2 to represent 1 g N2O and 25 g CO2 to represent 1 g CH4. 

You may then subtract the applicable converted values from the fuel 

conversion measured values of CH4 and/or N2O to demonstrate compliance 

with the CH4 and/or N2O standards.

(ii) Compliance with heavy-duty engine greenhouse gas emission standards is 

demonstrated by complying with the CO2, N2O, and CH4 standards (or FELs, as 

applicable) and provisions set forth in 40 CFR 1036.108 for the engine family that 

is represented by the fuel conversion emission data engine (EDE). If the fuel 

conversion CO2 measured value is lower than the CO2 standard (or FEL, as 

applicable), you have the option to convert the difference between the CO2

standard (or FEL, as applicable) and the fuel conversion CO2 measured value into 

GHG equivalents of CH4 and/or N2O, using 298 g/hp-hr CO2 to represent 1 g/hphr N2O and 25 g/hp-hr CO2 to represent 1 g/hp-hr CH4. You may then subtract 

the applicable converted values from the fuel conversion measured values of CH4

and/or N2O to demonstrate compliance with the CH4 and/or N2O standards (or 

FEL, as applicable).

(3) Conversion systems for engines that would have qualified for chassis certification 

at the time of OEM certification may use those procedures, even if the OEM did not. 

Conversion manufacturers choosing this option must designate test groups using the 

appropriate criteria as described in this subpart and meet all vehicle chassis 

certification requirements set forth in 40 CFR part 86, subpart S.

(b) [Reserved]

Subpart P—[Amended]

3. Section 85.1511 is revised to read as follows:

§ 85.1511 Exemptions and exclusions.

(a) Individuals, as well as certificate holders, shall be eligible for importing vehicles into 

the United States under the provisions of this section, unless otherwise specified.
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(b) Notwithstanding any other requirements of this subpart, a motor vehicle or motor 

vehicle engine entitled to a temporary exemption under this paragraph (b) may be 

conditionally admitted into the United States if prior written approval for such 

conditional admission is obtained from the Administrator. Conditional admission shall be 

under bond. A written request for approval from the Administrator shall contain the 

identification required in § 85.1504(a)(1) (except for § 85.1504(a)(1)(v)) and information 

that indicates that the importer is entitled to the exemption. Noncompliance with 

provisions of this section may result in the forfeiture of the total amount of the bond or 

exportation of the vehicle or engine. The following temporary exemptions are permitted 

by this paragraph (b):

(1) Exemption for repairs or alterations. Vehicles and engines may qualify for a 

temporary exemption under the provisions of 40 CFR 1068.325(a). Such vehicles or 

engines may not be registered or licensed in the United States for use on public roads 

and highways. 

(2) Testing exemption. Vehicles and engines may qualify for a temporary exemption 

under the provisions of 40 CFR 1068.325(b). Test vehicles or engines may be 

operated on and registered for use on public roads or highways provided that the 

operation is an integral part of the test. 

(3) Precertification exemption. Prototype vehicles for use in applying to EPA for 

certification may be imported by independent commercial importers subject to 

applicable provisions of 40 CFR 85.1706 and the following requirements:

(i) No more than one prototype vehicle for each engine family for which an 

independent commercial importer is seeking certification shall be imported by

each independent commercial importer.

(ii) Unless a certificate of conformity is issued for the prototype vehicle, the total 

amount of the bond shall be forfeited or the vehicle must be exported within 180 

days from the date of entry.

(4) Display exemptions. Vehicles and engines may qualify for a temporary exemption 

under the provisions of 40 CFR 1068.325(c). Display vehicles or engines may not be 

registered or licensed for use or operated on public roads or highways in the United 

States, unless an applicable certificate of conformity has been received.

(c) Notwithstanding any other requirements of this subpart, a motor vehicle or motor 

vehicle engine may be finally admitted into the United States under this paragraph (c) if 

prior written approval for such final admission is obtained from the Administrator. 

Conditional admission of these vehicles is not permitted for the purpose of obtaining 

written approval from the Administrator. A request for approval shall contain the 

identification information required in § 85.1504(a)(1) (except for § 85.1504(a)(1)(v)) and 

information that indicates that the importer is entitled to the exemption or exclusion. The 

following exemptions or exclusions are permitted by this paragraph (c):
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(1) National security exemption. Vehicles may be imported under the national 

security exemption found at 40 CFR 1068.315(a). Only persons who are 

manufacturers may import a vehicle under a national security exemption.

(2) Hardship exemption. The Administrator may exempt on a case-by-case basis

certain motor vehicles from Federal emission requirements to accommodate 

unforeseen cases of extreme hardship or extraordinary circumstances. Some examples 

are as follows:

(i) Handicapped individuals who need a special vehicle unavailable in a certified 

configuration;

(ii) Individuals who purchase a vehicle in a foreign country where resale is 

prohibited upon the departure of such an individual;

(iii) Individuals emigrating from a foreign country to the U.S. in circumstances of 

severe hardship.

(d) Foreign diplomatic and military personnel may import nonconforming vehicles 

without bond. At the time of admission, the importer shall submit to the Administrator 

the written report required in § 85.1504(a)(1) (except for information required by 

§ 85.1504(a)(1)(v)). Such vehicles may not be sold in the United States.

(e) Racing vehicles may be imported by any person provided the vehicles meet one or 

more of the exclusion criteria specified in § 85.1703. Racing vehicles may not be 

registered or licensed for use on or operated on public roads and highways in the United 

States.

(f) The following exclusions and exemptions apply based on date of original 

manufacture:

(1) Notwithstanding any other requirements of this subpart, the following motor 

vehicles or motor vehicle engines are excluded from the requirements of the Act in 

accordance with section 216(3) of the Act and may be imported by any person:

(i) Gasoline-fueled light-duty vehicles and light-duty trucks originally 

manufactured prior to January 1, 1968.

(ii) Diesel-fueled light-duty vehicles originally manufactured prior to January 1, 

1975.

(iii) Diesel-fueled light-duty trucks originally manufactured prior to January 1, 

1976.

(iv) Motorcycles originally manufactured prior to January 1, 1978.

(v) Gasoline-fueled and diesel-fueled heavy-duty engines originally manufactured 

prior to January 1, 1970.
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(2) Notwithstanding any other requirements of this subpart, a motor vehicle or motor 

vehicle engine not subject to an exclusion under paragraph (f)(1) of this section but 

greater than twenty OP years old is entitled to an exemption from the requirements of 

the Act, provided that it is imported into the United States by a certificate holder. At 

the time of admission, the certificate holder shall submit to the Administrator the 

written report required in § 85.1504(a)(1) (except for information required by

§ 85.1504(a)(1)(v)).

(g) Applications for exemptions and exclusions provided for in paragraphs (b) and (c) of 

this section shall be mailed to the Designated Compliance Officer (see 40 CFR 1068.30).

(h) Vehicles conditionally or finally admitted under this section must still comply with all 

applicable requirements, if any, of the Energy Tax Act of 1978, the Energy Policy and 

Conservation Act and any other Federal or state requirements.

Subpart R—[Amended]

4. Section 85.1701 is revised to read as follows: 

§ 85.1701 General applicability.

(a) The provisions of this subpart regarding exemptions are applicable to new and in-use 

motor vehicles and motor vehicle engines, except as specified in this paragraph (a). 

(1) Beginning January 1, 2014 the exemption provisions of 40 CFR part 1068, 

subpart C, apply for heavy-duty motor vehicles and engines, except that the 

competition exemption of 40 CFR 1068.235 and the hardship exemption provisions 

of 40 CFR 1068.245, 1068.250, and 1068.255 do not apply for motor vehicle engines. 

(2) Prior to January 1, 2014, the provisions of §§85.1706, 85.1707, 85.1708, and 

85.1709 apply for heavy-duty motor vehicle engines.

(b) The provisions of this subpart regarding exclusion are applicable after the effective 

date of these regulations.

(c) References in this subpart to engine families and emission control systems shall be 

deemed to apply to durability groups and test groups as applicable for manufacturers 

certifying new light-duty vehicles, light-duty trucks, and Otto-cycle complete heavy-duty

vehicles under the provisions of 40 CFR part 86, subpart S.

(d) In a given model year, manufacturers of motor vehicles and motor vehicle engines 

may ask us to approve the use of administrative or compliance procedures specified in 40 

CFR part 1068 instead of the comparable procedures that apply for vehicles or engines 

certified under this part or 40 CFR part 86. 

Subpart T—[Amended]

5. Section 85.1901 is revised to read as follows:
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§ 85.1901 Applicability.

Except as specified in this section, the requirements of this subpart shall be applicable to 

all 1972 and later model year vehicles and engines. The requirement to report emissionrelated defects affecting a given class or category of vehicles or engines shall remain 

applicable for five years from the end of the model year in which such vehicles or 

engines were manufactured. Manufacturers of heavy-duty motor vehicle engines may

comply with the defect reporting requirements of 40 CFR 1068.501 instead of the 

requirements of this subpart.

PART 86--CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY 

VEHICLES AND ENGINES

6. The authority citation for part 86 continues to read as follows:

Authority: 42 U.S.C. 7401-7671q.

7. Section 86.1 is amended by adding paragraphs (b)(2)(xli) and (b)(2)(xlii) and 

removing and reserving paragraph (b)(4)(i)(A) to read as follows:

§ 86.1 Reference materials.

* * * * *

(b) * * *

(2) * * *

(xli) SAE J1711, Recommended Practice for Measuring the Exhaust Emissions and Fuel 

Economy of Hybrid-Electric Vehicles, Including Plug-In Hybrid Vehicles, June 2010, 

IBR approved for § 86.1811-04(n). 

(xlii) SAE J1634, Electric Vehicle Energy Consumption and Range Test Procedure, 

Cancelled October 2002, IBR approved for § 86.1811-04(n). 

* * * * *

(4) * * *

(i) * * *

(A) [Reserved] 

* * * * *

Subpart A – [Amended]

8. Section 86.010-18 is amended by adding paragraphs (j)(1)(ii)(E) and (q) to read as 

follows:

§ 86.010-18 On-board Diagnostics for engines used in applications greater than 14,000 

pounds GVWR.

* * * * *

(j) * * *

(1) * * *
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(ii) * * *

(E) For hybrid engine families with projected U.S.-directed production volume of less 

than 5,000 engines, the manufacturers are only required to test one engine-hybrid 

combination per family. 

* * * * *

(q) Optional phase-in for hybrid vehicles. This paragraph (q) applies for model year 

2013 - 2015 engines when used with hybrid powertrain systems. It also applies for model 

year 2016 engines used with hybrid powertrain systems that were offered for sale prior to 

January 1, 2013, as specified in paragraph (q)(4) of this section. Manufacturers choosing 

to use the provisions of this paragraph (q) must submit an annual pre-compliance report 

to EPA for model years 2013 and later, as specified in paragraph (q)(5) of this section. 

Note that all hybrid powertrain systems must be fully compliant with the OBD 

requirements of this section no later than model year 2017.

(1) If an engine-hybrid system has been certified by the California Air Resources Board 

with respect to its OBD requirements and it effectively meets the full OBD requirements 

of this section, all equivalent systems must meet those same requirements and may not be

certified under this paragraph (q). For purposes of this paragraph (q)(1), an enginehybrid system is considered to be equivalent to the certified system if it uses the same 

basic design (e.g. displacement) for the engine and primary hybrid components (see 

paragraph (q)(4) of this section). Equivalent systems may have minor hardware or 

calibration differences.

(2) As of 2013, if an engine-hybrid system has not been certified to meet the full OBD 

requirements of this section, it must comply with the following requirements:

(i) The engine in its installed configuration must meet the EMD and EMD+ 

requirements in 13 CCR §1971.1(d)(7.1.4) of the California Code of Regulations. 

For purposes of this paragraph (q), a given EMD requirement is deemed to be met 

if the engine’s OBD system addresses the same function. This allowance does not 

apply for OBD monitors or diagnostics that have been modified under paragraph 

(q)(2)(ii) of this section.

(ii) The engine-hybrid system must maintain existing OBD capability for engines 

where the same or equivalent engine has been OBD certified. An equivalent 

engine is one produced by the same engine manufacturer with the same 

fundamental design, but that may have hardware or calibration differences that do 

not impact OBD functionality, such as slightly different displacement, rated 

power, or fuel system. (Note that engines with the same fundamental design will 

be presumed to be equivalent unless the manufacturer demonstrates that the 

differences effectively preclude applying equivalent OBD systems.) Though the 

OBD capability must be maintained, it does not have to meet detection thresholds 

(as described in Tables 1 and 2 of this section) and in-use performance frequency

requirements (as described in paragraph (d) of this section). A manufacturer may
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modify detection thresholds to prevent false detection, and must indicate all 

deviations from the originally certified package with engineering justification in 

the certification documentation.

(iii) This paragraph (q)(2)(iii) applies for derivatives of hybrid powertrain system 

designs that were offered for sale prior to January 1, 2013. Until these systems 

achieve full OBD certification, they must at a minimum maintain all faultdetection and diagnostic capability included on similar systems offered for sale 

prior to 2013. Manufacturers choosing to use the provisions of this paragraph 

(q)(2) must keep copies of the service manuals (and similar documents) for these 

previous model years to show the technical description of the system’s fault 

detection and diagnostic capabilities.

(iv) You must submit an annual pre-compliance report to EPA for model years 

2013 and later, as specified in paragraph (q)(5) of this section.

(3) Engine-hybrid systems may be certified to the requirements of paragraph (q)(2) of 

this section by the engine manufacturer, the hybrid system manufacturer, or the vehicle 

manufacturer. If engine manufacturers certify the engine hybrid system, they must 

provide detailed installation instructions. Where the engine manufacturer does not 

specifically certify its engines for use in hybrid vehicles under this paragraph (q), the 

hybrid system manufacturer and vehicle manufacturer must install the engine to conform 

to the requirements of this section (i.e., full OBD) or recertify under paragraph (q)(2) of 

this section.

(4) The provisions of this paragraph (q) apply for model year 2016 engines where you 

demonstrate that the hybrid powertrain system used is a derivative of a design that was 

offered for sale prior to January 1, 2013. In this case, you may ask us to consider the 

original system and the later system to be the same model for purposes of this paragraph 

(q), unless the systems are fundamentally different. In determining whether such systems 

are derivative or fundamentally different, we will consider factors such as the similarity

of the following:

(i) Transmissions.

(ii) Hybrid machines (where “hybrid machine” means any system that is the part 

of a hybrid vehicle system that captures energy from and returns energy to the 

powertrain).

(iii) Hybrid architecture (such as parallel or series).

(iv) Motor/generator size, controller/CPU (memory or inputs/outputs), control 

algorithm, and batteries. This paragraph (q)(4)(iv) applies only if all of these are 

modified simultaneously.

(5) Manufacturers choosing to use the provisions of this paragraph (q) must submit an 

annual pre-compliance report to EPA for model years 2013 and later. Engine 

manufacturers must submit this report with their engine certification information. Hybrid 
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manufacturers that are not certifying the engine-hybrid system must submit their report 

by June 1 of the model year, or at the time of certification if they choose to certify. 

Include the following in the report:

(i) A description of the manufacturer’s product plans and of the engine-hybrid 

systems being certified. 

(ii) A description of activities undertaken and progress made by the manufacturer 

towards achieving full OBD certification, including monitoring, diagnostics, and 

standardization.

(iii) For model year 2016 engines, a description of your basis for applying the 

provision of this paragraph (q) to the engines.

9. A new § 86.012-2 is added to subpart A to read as follows:

§ 86.012-2 Definitions. 

The definitions of §86.010–2 continue to apply to model year 2010 and later model year 

vehicles. The definitions listed in this section apply beginning with model year 2012.

Urban bus means a passenger-carrying vehicle with a load capacity of fifteen or more 

passengers and intended primarily for intracity operation, i.e., within the confines of a 

city or greater metropolitan area. Urban bus operation is characterized by short rides and 

frequent stops. To facilitate this type of operation, more than one set of quick-operating 

entrance and exit doors would normally be installed. Since fares are usually paid in cash 

or tokens, rather than purchased in advance in the form of tickets, urban buses would 

normally have equipment installed for collection of fares. Urban buses are also typically 

characterized by the absence of equipment and facilities for long distance travel, e.g., rest 

rooms, large luggage compartments, and facilities for stowing carry-on luggage. 

10. A new § 86.016-1 is added to subpart A to read as follows:

§ 86.016-1 General applicability.

(a) Applicability. The provisions of this subpart generally apply to 2005 and later model 

year new Otto-cycle heavy-duty engines used in incomplete vehicles and vehicles above 

14,000 pounds GVWR and 2005 and later model year new diesel-cycle heavy-duty

engines. In cases where a provision applies only to a certain vehicle group based on its 

model year, vehicle class, motor fuel, engine type, or other distinguishing characteristics, 

the limited applicability is cited in the appropriate section or paragraph. The provisions of 

this subpart continue to generally apply to 2000 and earlier model year new Otto-cycle 

and diesel-cycle light-duty vehicles, 2000 and earlier model year new Otto-cycle and 

diesel-cycle light-duty trucks, and 2004 and earlier model year new Otto-cycle complete 

heavy-duty vehicles at or below 14,000 pounds GVWR. Provisions generally applicable 

to 2001 and later model year new Otto-cycle and diesel-cycle light-duty vehicles, 2001 

and later model year new Otto-cycle and diesel-cycle light-duty trucks, and 2005 and 
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later model year Otto-cycle complete heavy-duty vehicles at or below 14,000 pounds 

GVWR are located in subpart S of this part.

(b) Optional applicability. A manufacturer may request to certify any incomplete Ottocycle heavy-duty vehicle of 14,000 pounds Gross Vehicle Weight Rating or less in 

accordance with the provisions for Otto-cycle complete heavy-duty vehicles located in 

subpart S of this part. Heavy-duty engine or heavy-duty vehicle provisions of this subpart 

A do not apply to such a vehicle. 

(c) Otto-cycle heavy-duty engines and vehicles. The following requirements apply to 

Otto-cycle heavy-duty engines and vehicles:

(1) Exhaust emission standards according to the provisions of § 86.008-10 or 

§ 86.1816, as applicable.

(2) On-board diagnostics requirements according to the provisions of § 86.007–17 or 

§ 86.1806, as applicable.

(3) Evaporative emission standards as follows:

(i) Evaporative emission standards for complete vehicles according to the 

provisions of §§ 86.1810 and 86.1816.

(ii) For 2013 and earlier model years, evaporative emission standards for 

incomplete vehicles according to the provisions of § 86.008-10, or §§ 86.1810 

and 86.1816, as applicable.

(iii) For 2014 and later model years, evaporative emission standards for 

incomplete vehicles according to the provisions of §§ 86.1810 and 86.1816, or 40 

CFR part 1037, as applicable.

(4) Refueling emission requirements for Otto-cycle complete vehicles according to 

the provisions of §§ 86.1810 and 86.1816.

(d) Non-petroleum fueled vehicles. The standards and requirements of this part apply to 

model year 2016 and later non-petroleum fueled motor vehicles as follows:

(1) The standards and requirements of this part apply as specified for vehicles fueled 

with methanol, natural gas, and LPG.

(2) The standards and requirements of subpart S of this part apply as specified for 

light-duty vehicles and light-duty trucks.

(3) The standards and requirements of this part applicable to methanol-fueled heavyduty vehicles and engines (including flexible fuel vehicles and engines) apply to 

heavy-duty vehicles and engines fueled with any oxygenated fuel (including flexible 

fuel vehicles and engines). Most significantly, this means that the hydrocarbon 

standards apply as NMHCE and the vehicles and engines must be tested using the 
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applicable oxygenated fuel according to the test procedures in 40 CFR part 1065 

applicable for oxygenated fuels. For purposes of this paragraph (d), oxygenated fuel 

means any fuel containing at least 50 volume percent oxygenated compounds. For 

example, a fuel mixture of 85 gallons of ethanol and 15 gallons of gasoline is an 

oxygenated fuel, while a fuel mixture of 15 gallons of ethanol and 85 gallons of 

gasoline is not an oxygenated fuel.

(4) The standards and requirements of subpart S of this part applicable to heavy-duty

vehicles under 14,000 pounds GVWR apply to all heavy-duty vehicles powered 

solely by electricity, including plug-in electric vehicles and solar-powered vehicles. 

Use good engineering judgment to apply these requirements to these vehicles, 

including applying these provisions to vehicles over 14,000 pounds GVWR. Electric 

heavy-duty vehicles may not generate NOX or PM emission credits. Heavy-duty

vehicles powered solely by electricity are deemed to have zero emissions of regulated 

pollutants.

(5) The standards and requirements of this part applicable to diesel-fueled heavy-duty 

vehicles and engines apply to all other heavy-duty vehicles and engines not otherwise 

addressed in this paragraph (d).

(6) See 40 CFR parts 1036 and 1037 for requirements related to greenhouse gas 

emissions.

(7) Manufacturers may voluntarily certify to the standards of paragraphs (d)(3) 

through (5) of this section before model year 2016. Note that other provisions in this 

part require compliance with the standards described in paragraphs (d)(1) and (2) of 

this section for model years before 2016.

(e) Small volume manufacturers. Special certification procedures are available for any

manufacturer whose projected combined U.S. sales of light-duty vehicles, light-duty 

trucks, heavy-duty vehicles, and heavy-duty engines in its product line (including all 

vehicles and

engines imported under the provisions of 40 CFR 85.1505 and 85.1509 of this chapter) 

are fewer than 10,000 units for the model year in which the manufacturer seeks 

certification. To certify its product line under these optional procedures, the smallvolume manufacturer must first obtain the Administrator's approval. The manufacturer 

must meet the eligibility criteria specified in § 86.098-14(b) before the Administrator's 

approval will be granted. The small-volume manufacturer's certification procedures are 

described in § 86.098-14.

(f) Optional procedures for determining exhaust opacity. (1) The provisions of 

subpart I of this part apply to tests which are performed by the Administrator, and 

optionally, by the manufacturer.

(2) Measurement procedures, other than those described in subpart I of this part, may

be used by the manufacturer provided the manufacturer satisfies the requirements of 

§ 86.007-23(f).
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(3) When a manufacturer chooses to use an alternative measurement procedure, it has 

the responsibility to determine whether the results obtained by the procedure will 

correlate with the results which would be obtained from the measurement procedure 

in subpart I of this part. Consequently, the Administrator will not routinely approve or 

disapprove any alternative opacity measurement procedure or any associated 

correlation data which the manufacturer elects to use to satisfy the data requirements 

for subpart I of this part.

(4) If a confirmatory test is performed and the results indicate there is a systematic 

problem suggesting that the data generated under an optional alternative measurement 

procedure do not adequately correlate with data obtained in accordance with the 

procedures described in subpart I of this part, EPA may require that all certificates of 

conformity not already issued be based on data obtained from procedures described in 

subpart I of this part.

11. Section 86.090-2 is amended by revising the definition of “primary intended service 

class” to read as follows:

§ 86.090-2 Definitions.

* * * * *

Primary intended service class has the meaning given in 40 CFR 1036.140.

* * * * *

Subpart B – [Amended]

12. Section 86.144-94 is amended by adding paragraphs (b)(11) and (c)(10) to read as 

follows:

§ 86.144-94 Calculations; exhaust emissions.

* * * * *

(b) * * *

(11) Nitrous Oxide Mass: Vmix x DensityN2O x (N2Oconc/1,000,000)

(c) * * *

(10)(i) N2Omass=Nitrous oxide emissions, in grams per test phase.

(ii) DensityN2O=Density of nitrous oxide is 51.81 g/ft3(1.83 kg/m3), at 68 °F (20 °C) and 

760 mm Hg (101.3kPa) pressure.

(iii)(A) N2Oconc=Nitrous oxide concentration of the dilute exhaust sample corrected for 

background, in ppm.

(B) N2Oconc=N2Oe-N2Od(1-(1/DF)).

Where:
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N2Oe=Nitrous oxide concentration of the dilute exhaust sample as measured, in ppm.

N2Od= Nitrous oxide concentration of the dilution air as measured, in ppm.

* * * * *

Subpart F – [Amended]

13. Section 86.544-90 is amended by adding paragraphs (b)(8) and (c)(8) to read as 

follows:

§ 86.544-90 Calculations; exhaust emissions.

* * * * *

(b) * * *

(8) Nitrous Oxide Mass: Vmix x DensityN2O x (N2Oconc/1,000,000)

(c) * * *

(8)(i) N2Omass=Nitrous oxide emissions, in grams per test phase.

(ii) DensityN2O=Density of nitrous oxide is 51.81 g/ft3(1.83 kg/m3), at 68 °F (20 °C) and 

760 mm Hg (101.3kPa) pressure.

(iii)(A) N2Oconc=Nitrous oxide concentration of the dilute exhaust sample corrected for 

background, in ppm.

(B) N2Oconc=N2Oe-N2Od(1-(1/DF)).

Where:

N2Oe=Nitrous oxide concentration of the dilute exhaust sample as measured, in ppm.

N2Od= Nitrous oxide concentration of the dilution air as measured, in ppm.

* * * * *

Subpart N – [Amended]

14. Section 86.1305-2010 is amended by revising paragraph (b) to read as follows:

§ 86.1305-2010 Introduction; structure of subpart.

* * * * *

(b) Use the applicable equipment and procedures for spark-ignition or compressionignition engines in 40 CFR part 1065 to determine whether engines meet the duty-cycle 

emission standards in subpart A of this part. Measure the emissions of all regulated 
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pollutants as specified in 40 CFR part 1065. Use the duty cycles and procedures specified 

in §§86.1333–2010, 86.1360–2007, and 86.1362–2010. Adjust emission results from 

engines using aftertreatment technology with infrequent regeneration events as described 

in §86.004–28.

* * * * *

Subpart S – [Amended]

§ 86.1806-01—[Amended]

15. Section 86.1806-01 is amended by removing and reserving paragraph (b)(8)(ii).

§ 86.1806-05—[Amended]

16. Section 86.1806-05 is amended by removing and reserving paragraph (b)(8)(ii).

17. Section 86.1811-04 is amended by revising paragraph (n) to read as follows:

§ 86.1811-04 Emission standards for light-duty vehicles, light-duty trucks and 

medium-duty passenger vehicles.

* * * * *

(n) Hybrid electric vehicle (HEV) and Zero Emission Vehicle (ZEV) requirements. For 

FTP and SFTP exhaust emissions, manufacturers must measure emissions from all HEVs 

and ZEVs according to the procedures specified in SAE J1711 and SAE J1634, 

respectively (incorporated by reference in § 86.1).

* * * * *

18. Section 86.1818-12 is amended by revising paragraph (f) to read as follows:

§ 86.1818-12 Greenhouse gas emission standards for light-duty vehicles, light-duty 

trucks, and medium-duty passenger vehicles.

* * * * *

(f) Nitrous oxide (N2O) and methane (CH4) exhaust emission standards for passenger 

automobiles and light trucks. Each manufacturer's fleet of combined passenger 

automobile and light trucks must comply with N2O and CH4 standards using either the 

provisions of paragraph (f)(1), (f)(2), or (f)(3) of this section. Except with prior EPA 

approval, a manufacturer may not use the provisions of both paragraphs (f)(1) and (f)(2) 

of this section in a model year. For example, a manufacturer may not use the provisions 

of paragraph (f)(1) of this section for their passenger automobile fleet and the provisions 

of paragraph (f)(2) for their light truck fleet in the same model year. The manufacturer 

may use the provisions of both paragraphs (f)(1) and (f)(3) of this section in a model 

year. For example, a manufacturer may meet the N2O standard in paragraph (f)(1)(i) of 
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this section and an alternative CH4 standard determined under paragraph (f)(3) of this 

section. Use of the provisions in paragraph (f)(3) is limited to the 2012 through 2016 

model years.

(1) Standards applicable to each test group. (i) Exhaust emissions of nitrous oxide (N2O) 

shall not exceed 0.010 grams per mile at full useful life, as measured according to the 

Federal Test Procedure (FTP) described in subpart B of this part. Manufacturers may

optionally determine an alternative N2O standard under paragraph (f)(3) of this section. 

(ii) Exhaust emissions of methane (CH4) shall not exceed 0.030 grams per mile at full 

useful life, as measured according to the Federal Test Procedure (FTP) described in 

subpart B of this part. Manufacturers may optionally determine an alternative CH4

standard under paragraph (f)(3) of this section.

(2) Include N2O and CH4 in fleet averaging program. Manufacturers may elect to not 

meet the emission standards in paragraph (f)(1) of this section. Manufacturers making 

this election shall include N2O and CH4 emissions in the determination of their fleet 

average carbon-related exhaust emissions, as calculated in subpart F of part 600 of this 

chapter. Manufacturers using this option must include both N2O and CH4 full useful life 

values in the fleet average calculations for passenger automobiles and light trucks. Use of 

this option will account for N2O and CH4 emissions within the carbon-related exhaust 

emission value determined for each model type according to the provisions of part 600 of 

this chapter. This option requires the determination of full useful life emission values for 

both the Federal Test Procedure and the Highway Fuel Economy Test. Manufacturers 

selecting this option are not required to demonstrate compliance with the standards in 

paragraph (f)(1) of this section. 

(3) Optional use of alternative N2O and/or CH4 standards. Manufacturers may select an 

alternative standard applicable to a test group, for either N2O, CH4, or both. For example, 

a manufacturer may choose to meet the N2O standard in paragraph (f)(1)(i) of this section 

and an alternative CH4 standard in lieu of the standard in paragraph (f)(1)(ii) of this 

section. The alternative standard for each pollutant must be greater than the applicable 

exhaust emission standard specified in paragraph (f)(1) of this section. Alternative N2O 

and CH4 standards apply to emissions measured according to the Federal Test Procedure 

(FTP) described in Subpart B of this part for the full useful life, and become the 

applicable certification and in-use emission standard(s) for the test group. Manufacturers 

using an alternative standard for N2O and/or CH4 must calculate emission debits 

according to the provisions of paragraph (f)(4) of this section for each test 

group/alternative standard combination. Debits must be included in the calculation of 

total credits or debits generated in a model year as required under § 86.1865-12(k)(5). 

For flexible fuel vehicles (or other vehicles certified for multiple fuels) you must meet 

these alternative standards when tested on any applicable test fuel type. 

(4) CO2-equivalent debits. CO2-equivalent debits for test groups using an alternative 

N2Oand/or CH4 standard as determined under paragraph (f)(3) of this section shall be 

calculated according to the following equation and rounded to the nearest megagram:
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Debits = [GWP x (Production) x (AltStd – Std) x VLM] / 1,000,000

Where:

Debits = N2O or CH4 CO2-equivalent debits for a test group using an alternative N2O or 

CH4 standard;

GWP = 25 if calculating CH4 debits and 298 if calculating N2O debits;

Production = The number of vehicles of that test group domestically produced plus those 

imported as defined in §600.511–80 of this chapter;

AltStd = The alternative standard (N2O or CH4) selected by the manufacturer under 

paragraph (f)(3) of this section;

Std = The exhaust emission standard for N2O or CH4 specified in paragraph (f)(1) of this 

section; and

VLM = 195,264 for passenger automobiles and 225,865 for light trucks.

19. Section 86.1823-08 is amended by revising paragraphs (m)(1)(i), (m)(2), (m)(3), and 

(m)(4) to read as follows:

§ 86.1823-08 Durability demonstration procedures for exhaust emissions.

* * * * *

(m) * * *

(1) * * *

(i) Unless otherwise specified under paragraph (m)(1)(ii) of this section, manufacturers 

may use a multiplicative CO2 deterioration factor of one or an additive deterioration 

factor of zero to determine full useful life emissions for the FTP and HFET tests.

* * * * *

(2) N2O and CH4. (i) For manufacturers complying with the FTP emission standards for 

N2O and CH4 specified in §86.1818–12(f)(1) or determined under §86.1818–12 (f)(3), 

FTP-based deterioration factors for N2O and CH4 shall be determined according to the 

provisions of paragraphs (a) through (l) of this section.

(ii) For manufacturers complying with the fleet averaging option for N2O and CH4 as 

allowed under §86.1818–12(f)(2), deterioration factors based on FTP testing shall be 

determined and may be used to determine full useful life emissions for the FTP and 

HFET tests. The manufacturer may at its option determine separate deterioration factors 

for the FTP and HFET test cycles, in which case each FTP test performed on the 

durability data vehicle selected under §86.1822–01 of this part must also be accompanied 

by an HFET test.

(iii) For the 2012 through 2014 model years only, manufacturers may use alternative 

deterioration factors. For N2O, the alternative deterioration factor to be used to adjust 
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FTP and HFET emissions is the deterioration factor determined for NOX emissions 

according to the provisions of this section. For CH4, the alternative deterioration factor to 

be used to adjust FTP and HFET emissions is the deterioration factor determined for 

NMOG or NMHC emissions according to the provisions of this section.

(3) Other carbon-related exhaust emissions. FTP-based deterioration factors shall be 

determined for carbon-related exhaust emissions (CREE), hydrocarbons, and CO 

according to the provisions of paragraphs (a) through (l) of this section. The FTP-based 

deterioration factor shall be used to determine full useful life emissions for both the FTP 

(city) and HFET (highway) test cycles. The manufacturer may at its option determine 

separate deterioration factors for the FTP and HFET test cycles, in which case each FTP 

test performed on the durability data vehicle selected under §86.1822 of this part must 

also be accompanied by an HFET test. In lieu of determining emission-specific 

deterioration factors for the specific hydrocarbons of CH3OH (methanol), HCHO 

(formaldehyde), C2H5OH (ethanol), and C2H4O (acetaldehyde) as may be required for 

some alternative fuel vehicles, manufacturers may use the additive or multiplicative 

deterioration factor determined for (or derived from, using good engineering judgment) 

NMOG or NMHC emissions according to the provisions of this section.

(4) Air Conditioning leakage and efficiency or other emission credit requirements to 

comply with exhaust CO2 standards. Manufactures will attest to the durability of 

components and systems used to meet the CO2 standards. Manufacturers may submit 

engineering data to provide durability demonstration. Deterioration factors do not apply

to emission-related components and systems used to generate air conditioning leakage 

and/or efficiency credits. 

20. Section 86.1844-01 is amended by revising paragraph (d)(15) to read as follows:

§ 86.1844-01 Information requirements: Application for certification and submittal 

of information upon request.

* * * * *

(d) * * *

(15)(i) For HEVs and EVs, describe the recharging procedures and methods for 

determining battery performance, such as state of charge and charging capacity.

(ii) For vehicles with fuel-fired heaters, include the information specified in this 

paragraph (d)(15)(ii). Describe the control system logic of the fuel-fired heater, 

including an evaluation of the conditions under which it can be operated and an 

evaluation of the possible operational modes and conditions under which evaporative 

emissions can exist. Use good engineering judgment to establish an estimated 

exhaust emission rate from the fuel-fired heater in grams per mile. Describe the 

testing used to establish the exhaust emission rate.

* * * * *

21. Section 86.1863-07 is revised to read as follows:
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§ 86.1863-07 Chassis certification for diesel vehicles.

(a) A manufacturer may optionally certify heavy-duty diesel vehicles 14,000 pounds 

GVWR or less to the standards specified in § 86.1816. Such vehicles must meet all the 

requirements of this subpart S that are applicable to Otto-cycle vehicles, except for 

evaporative, refueling, and OBD requirements where the diesel-specific OBD 

requirements would apply.

(b) For OBD, diesel vehicles optionally certified under this section are subject to the 

OBD requirements of § 86.1806.

(c) Diesel vehicles certified under this section may be tested using the test fuels, sampling 

systems, or analytical systems specified for diesel engines in subpart N of this part or in 

40 CFR part 1065.

(d) Diesel vehicles optionally certified under this section to the standards of this subpart 

may not be included in any averaging, banking, or trading program for criteria emissions 

under this part.

(e) The provisions of § 86.004–40 apply to the engines in vehicles certified under this 

section.

(f) Diesel vehicles may be certified under this section to the standards applicable to 

model year 2008 in earlier model years.

(g) Diesel vehicles optionally certified under this section in model years 2007, 2008, or 

2009 shall be included in phase-in calculations specified in § 86.007–11(g).

(h) Diesel vehicles subject to the standards of 40 CFR 1037.104 are subject to the 

provisions of this subpart as specified in 40 CFR 1037.104.

(i) Non-petroleum fueled complete vehicles subject to the standards and requirements of 

this part under §86.016-01(d)(5) are subject to the provisions of this section applicable to 

diesel-fueled heavy-duty vehicles.

22. Section 86.1865-12 is amended by adding paragraphs (k)(5)(iv), and by revising 

paragraphs (l)(1)(ii)(F), and (l)(2)(i) to read as follows:

§ 86.1865-12 How to comply with the fleet average CO2 standards.

* * * * *

(k) * * *

(5) * * *

(iv) N2O and/or CH4 CO2-equivalent debits accumulated according to the provisions of § 

86.1818-12(f)(4).

* * * * *
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(l) * * *

(1) * * * 

(ii) * * *

(F) Carbon-related exhaust emission standard, N2O emission standard, and CH4 emission 

standard to which the passenger car or light truck is certified.

* * * * *

(2) * * *

(i) Each manufacturer must submit an annual report. The annual report must contain for 

each applicable CO2 standard, the calculated fleet average CO2 value, all values required 

to calculate the CO2 emissions value, the number of credits generated or debits incurred, 

all the values required to calculate the credits or debits, and the resulting balance of 

credits or debits. For each applicable alternative N2O and/or CH4 standard selected under 

the provisions of § 86.1818-12(f)(3), the report must contain the N2O and/or CH4 CO2-

equivalent debits calculated according to § 86.1818-12(f)(4) for each test group and all 

values required to calculate the number of debits incurred.

* * * * *

PART 600— FUEL ECONOMY AND GREENHOUSE GAS EXHAUST 

EMISSIONS OF MOTOR VEHICLES 

23. The authority citation for part 600 continues to read as follows:

Authority: 49 U.S.C. 32901—23919q, Pub. L. 109–58.

Subpart A—[Amended]

24. Section 600.011 is amended by revising paragraph (c)(3) to read as follows:

§ 600.011 Incorporation by reference.

* * * * *

(c) * * *

(3) SAE J1711, Recommended Practice for Measuring the Exhaust Emissions and Fuel 

Economy of Hybrid-Electric Vehicles, Including Plug-In Hybrid Vehicles, June 2010, 

IBR approved for §§ 600.114-12(c) and (f), 600.116–12(b), and 600.311-12(d), (j), and 

(k).

* * * * *

Subpart B—[Amended]

25. Section 600.114-12 is amended by revising paragraphs (c), (e)(2)(ii), and (f) to read 

as follows:
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§ 600.114-12 Vehicle-specific 5-cycle fuel economy and carbon-related exhaust 

emission calculations.

* * * * *

(c) Fuel economy calculations for hybrid electric vehicles. Test hybrid electric vehicles 

as described in SAE J1711 (incorporated by reference in § 600.011). For FTP testing, this 

generally involves emission sampling over four phases (bags) of the UDDS (cold-start, 

transient, warm-start, transient); however, these four phases may be combined into two 

phases (phases 1 + 2 and phases 3 + 4). Calculations for these sampling methods follow:

* * * * *

(e) * * *

(2) * * *

(ii) Determine the 5-cycle highway carbon-related exhaust emissions according to the 

following formula: 

StartCREE RunningCREE HighwayCREE

0.905





Where: 

  

60

0.005515 A 1.13637 StartCREE StartCREE 0.33   75  

  75 75 CREE 75 Start CREE  3.6  Bag 1CREE  Bag 3

   

0.377 0.133 0.00540 A  0.1357 US06 CREE 

Running CREE 1.007 0.79 US06 Highway CREE 0.21 HFET CREE

    

     

* * * * *

(f) CO2 and carbon-related exhaust emissions calculations for hybrid electric vehicles.

Test hybrid electric vehicles as described in SAE J1711 (incorporated by reference in 

§ 600.011). For FTP testing, this generally involves emission sampling over four phases 

(bags) of the UDDS (cold-start, transient, warm-start, transient); however, these four 

phases may be combined into two phases (phases 1 + 2 and phases 3 + 4). Calculations 

for these sampling methods follow:

* * * * *

26. Section 600.115-11 is amended by revising the introductory text to read as follows:

§ 600.115-11 Criteria for determining the fuel economy label calculation method.

This section provides the criteria to determine if the derived 5-cycle method for 

determining fuel economy label values, as specified in § 600.210–08(a)(2) or (b)(2) or § 

600.210–12(a)(2) or (b)(2), as applicable, may be used to determine label values. 

Separate criteria apply to city and highway fuel economy for each test group. The 
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provisions of this section are optional. If this option is not chosen, or if the criteria 

provided in this section are not met, fuel economy label values must be determined 

according to the vehicle-specific 5-cycle method specified in § 600.210–08(a)(1) or 

(b)(1) or § 600.210–12(a)(1) or (b)(1), as applicable. However, dedicated alternative-fuel 

vehicles, dual fuel vehicles when operating on the alternative fuel, plug-in hybrid electric 

vehicles while operating in charge-depleting mode, MDPVs, and vehicles imported by

Independent Commercial Importers may use the derived 5-cycle method for determining 

fuel economy label values whether or not the criteria provided in this section are met. 

Manufacturers may alternatively account for this effect by multiplying 2-cycle fuel 

economy values by 0.7 and dividing 2-cycle CO2 emission values by 0.7.

* * * * *

27. Section 600.116-12 is amended by adding paragraph (a)(6) and revising the equation 

for UFi in paragraph (b)(4) to read as follows:

§ 600.116-12 Special procedures related to electric vehicles and plug-in hybrid 

electric vehicles.

(a) * * *

(6) All label values related to fuel economy, energy consumption, and range must be 

based on 5-cycle testing or on values adjusted to be equivalent to 5-cycle results.

(b) * * *

(4) ** *

1

1 1

1 exp

j

k n

i

i j i

j i

d

UF C UF

ND 

 

       

            

           

 

* ** * *

Subpart C—[Amended]

28. Section 600.210-12 is amended by revising paragraph (d)(3)(ii) to read as follows:

§ 600.210-12 Calculation of fuel economy and CO2 emission values for labeling.

* ** * *

(d) ** *

(3) ** *

(ii) Multiply 2-cycle fuel economy values by 0.7 and divide 2-cycle CO2 emission values 

by 0.7. 

* ** * *
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Subpart D—[Amended]

29. Section 600.302-12 is amended by revising paragraph (e)(4) to read as follows:

§ 600.302-12 Fuel economy label—general provisions.

(e) ** *

(4) Insert a slider bar in the right portion of the field to characterize the vehicle’s level of 

emission control for ozone-related air pollutants relative to that of all vehicles. Position a 

box with a downward-pointing wedge above the slider bar positioned to show where that 

vehicle's emission rating falls relative to the total range. Include the vehicle’s emission 

rating (as described in § 600.311) inside the box. Include the number 1 in the border at 

the left end of the slider bar; include the number 10 in the border at the right end of the 

slider bar and add the term “Best” below the slider bar, directly under the number. EPA 

will periodically calculate and publish updated range values as described in § 600.311. 

Add color to the slider bar such that it is blue at the left end of the range, white at the 

right end of the range, and shaded continuously across the range.

* ** * *

30. Section 600.311-12 is amended by revising paragraph (f) to read as follows:

§ 600.311–12 Determination of values for fuel economy labels.

* * * * *

(f) Fuel savings. Calculate an estimated five-year cost increment relative to an average 

vehicle by multiplying the annual fuel cost from paragraph (e) of this section by 5 and 

subtracting this value from the average five-year fuel cost. We will calculate the average 

five-year fuel cost from the annual fuel cost equation in paragraph (e) of this section 

based on a gasoline-fueled vehicle with a mean fuel economy value, consistent with the 

value dividing the 5 and 6 ratings under paragraph (d) of this section. The average fiveyear fuel cost for model year 2012 is $12,600 for a 22-mpg vehicle that drives 15,000 

miles per year with gasoline priced at $3.70 per gallon. We may periodically update this 

five year reference fuel cost for later model years to better characterize the fuel economy 

for an average vehicle. Round the calculated five-year cost increment to the nearest $50. 

Negative values represent a cost increase compared to the average vehicle. 

* * * * * 

PART 1033— CONTROL OF EMISSIONS FROM LOCOMOTIVES

31. The authority citation for part 1033 continues to read as follows: 

Authority: 42 U.S.C. 7401-7671q.
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Subpart G—[Amended]

32. Section 1033.625 is amended by revising paragraph (a)(2) to read as follows: 

§ 1033.625 Special certification provisions for non-locomotive-specific engines.

* * * * *

(a) * * *

(2) The engines were certified to PM, NOX, and hydrocarbon standards that are 

numerically lower than the applicable locomotive standards of this part.

* * * * *

33. A new part 1036 is added to subchapter U to read as follows: 

PART 1036--CONTROL OF EMISSIONS FROM NEW AND IN-USE HEAVYDUTY HIGHWAY ENGINES

Subpart A—Overview and Applicability

Sec.

1036.1 Does this part apply for my engines?

1036.2 Who is responsible for compliance?

1036.5 Which engines are excluded from this part’s requirements?

1036.10 How is this part organized?

1036.15 Do any other regulation parts apply to me?

1036.30 Submission of information.

Subpart B—Emission Standards and Related Requirements 

1036.100 Overview of exhaust emission standards.

1036.108 Greenhouse gas emission standards.

1036.115 Other requirements.

1036.130 Installation instructions for vehicle manufacturers.

1036.135 Labeling.

1036.140 Primary intended service class.
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1036.150 Interim provisions. 

Subpart C—Certifying Engine Families

1036.205 What must I include in my application?

1036.210 Preliminary approval before certification.

1036.225 Amending my application for certification.

1036.230 Selecting engine families.

1036.235 Testing requirements for certification.

1036.241 Demonstrating compliance with greenhouse gas pollutant standards.

1036.250 Reporting and recordkeeping for certification. 

1036.255 What decisions may EPA make regarding my certificate of conformity?

Subpart D—[Reserved]

Subpart E—In-use Testing

1036.401 In-use testing. 

Subpart F—Test Procedures

1036.501 How do I run a valid emission test?

1036.525 Hybrid engines. 

1036.530 Calculating greenhouse gas emission rates. 
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Subpart G—Special Compliance Provisions

1036.601 What compliance provisions apply to these engines?

1036.610 Innovative technology credits and adjustments for reducing greenhouse gas 

emissions.

1036.615 Engines with Rankine cycle waste heat recovery and hybrid powertrains.

1036.620 Alternate CO2 standards based on model year 2011 compression ignition 

engines.

Subpart H—Averaging, Banking, and Trading for Certification

1036.701 General provisions.

1036.705 Generating and calculating emission credits.

1036.710 Averaging.

1036.715 Banking.

1036.720 Trading.

1036.725 What must I include in my application for certification?

1036.730 ABT reports.

1036.735 Recordkeeping.

1036.740 Restrictions for using emission credits.

1036.745 End-of-year CO2 credit deficits.

1036.750 What can happen if I do not comply with the provisions of this subpart?

1036.755 Information provided to the Department of Transportation.

Subpart I—Definitions and Other Reference Information
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1036.801 Definitions.

1036.805 Symbols, acronyms, and abbreviations.

1036.810 Incorporation by reference.

1036.815 What provisions apply to confidential information?

1036.820 Requesting a hearing.

1036.825 Reporting and recordkeeping requirements.

Authority: 42 U.S.C. 7401 - 7671q.

Subpart A—Overview and Applicability

§ 1036.1 Does this part apply for my engines?

(a) Except as specified in § 1036.5, the provisions of this part apply to all new 2014 

model year and later heavy-duty engines. This includes engines fueled by conventional 

and alternative fuels.

(b) This part does not apply with respect to exhaust emission standards for HC, CO, NOX, 

or PM except that the provisions of §1036.601 apply. 

§ 1036.2 Who is responsible for compliance?

The regulations in this part 1036 contain provisions that affect both engine manufacturers 

and others. However, the requirements of this part are generally addressed to the engine 

manufacturer. The term "you" generally means the engine manufacturer, especially for 

issues related to certification.

§ 1036.5 Which engines are excluded from this part’s requirements?

(a) The provisions of this part do not apply to engines used in medium-duty passenger 

vehicles that are subject to regulation under 40 CFR part 86, subpart S, except as 

specified in 40 CFR part 86, subpart S and §1036.108(a)(4). For example, this exclusion 

applies for engines used in vehicles certified to the standards of 40 CFR 1037.104.
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(b) Engines installed in heavy-duty vehicles that do not provide motive power are 

nonroad engines. The provisions of this part therefore do not apply to these engines. See 

40 CFR parts 1039, 1048, or 1054 for other requirements that apply for these auxiliary

engines. See 40 CFR part 1037 for requirements that may apply for vehicles using these 

engines, such as the evaporative emission requirements of 40 CFR 1037.103.

(c) The provisions of this part do not apply to aircraft or aircraft engines. Standards 

apply separately to certain aircraft engines, as described in 40 CFR part 87.

(d) The provisions of this part do not apply to engines that are not internal combustion 

engines. For example, the provisions of this part do not apply to fuel cells.

(e) The provisions of this part do not apply to engines used in heavy-duty vehicles that 

are subject to light-duty greenhouse gas standards under 40 CFR part 86, subpart S, 

except as specified in 40 CFR part 86, subpart S and §1036.108(a)(4).

§ 1036.10 How is this part organized?

This part 1036 is divided into the following subparts:

(a) Subpart A of this part defines the applicability of this part 1036 and gives an overview 

of regulatory requirements.

(b) Subpart B of this part describes the emission standards and other requirements that 

must be met to certify engines under this part. Note that § 1036.150 describes certain

interim requirements and compliance provisions that apply only for a limited time.

(c) Subpart C of this part describes how to apply for a certificate of conformity.

(d) [Reserved]

(e) Subpart E of this part describes provisions for testing in-use engines.

(f) Subpart F of this part describes how to test your engines (including references to other 

parts of the Code of Federal Regulations). 

(g) Subpart G of this part describes requirements, prohibitions, and other provisions that 

apply to engine manufacturers, vehicle manufacturers, owners, operators, rebuilders, and 

all others.

(h) Subpart H of this part describes how you may generate and use emission credits to 

certify your engines.

(i) [Reserved] 

(j) Subpart J of this part contains definitions and other reference information.
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§ 1036.15 Do any other regulation parts apply to me?

(a) Part 86 of this chapter describes additional requirements that apply to engines that are 

subject to this part 1036. This part extensively references portions of 40 CFR part 86. 

For example, the regulations of part 86 specify emission standards and certification 

procedures related to criteria pollutants.

(b) Part 1037 of this chapter describes requirements for controlling evaporative emissions 

and greenhouse gas emissions from heavy-duty vehicles, whether or not they use engines 

certified under this part. It also includes standards and requirements that apply instead of 

the standards and requirements of this part in some cases.

(c) Part 1065 of this chapter describes procedures and equipment specifications for 

testing engines to measure exhaust emissions. Subpart F of this part 1036 describes how 

to apply the provisions of part 1065 of this chapter to determine whether engines meet the 

exhaust emission standards in this part.

(d) Certain provisions of part 1068 of this chapter apply as specified in § 1036.601 to 

everyone, including anyone who manufactures, imports, installs, owns, operates, or 

rebuilds any of the engines subject to this part 1036, or vehicles containing these engines. 

Part 1068 of this chapter describes general provisions that apply broadly, but do not 

necessarily apply for all engines or all persons. The issues addressed by these provisions 

include these seven areas:

(1) Prohibited acts and penalties for engine manufacturers, vehicle manufacturers, and 

others.

(2) Rebuilding and other aftermarket changes.

(3) Exclusions and exemptions for certain engines.

(4) Importing engines.

(5) Selective enforcement audits of your production.

(6) Recall.

(7) Procedures for hearings.

(e) Other parts of this chapter apply if referenced in this part. 

§ 1036.30 Submission of information.

Send all reports and requests for approval to the Designated Compliance Officer (see 

§ 1036.801). See § 1036.825 for additional reporting and recordkeeping provisions.
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Subpart B—Emission Standards and Related Requirements 

§ 1036.100 Overview of exhaust emission standards.

Engines used in vehicles certified to the applicable chassis standards for greenhouse gas 

pollutants described in 40 CFR 1037.104 are not subject to the standards specified in this 

part. All other engines subject to this part must meet the greenhouse gas standards in 

§ 1036.108 in addition to the criteria pollutant standards of 40 CFR part 86.

§ 1036.108 Greenhouse gas emission standards.

This section contains standards and other regulations applicable to the emission of the air 

pollutant defined as the aggregate group of six greenhouse gases: carbon dioxide, nitrous 

oxide, methane, hydrofluorocarbons, perflurocarbons, and sulfur hexafluoride. This 

section describes the applicable CO2, N2O, and CH4 standards for engines. Except as 

specified in paragraph (a)(4) of this section, these standards do not apply for engines used 

in vehicles subject to (or voluntarily certified to) the CO2, N2O, and CH4 standards for 

vehicles specified in 40 CFR 1037.104.

(a) Emission standards. Emission standards apply for engines measured using the test 

procedures specified in subpart F of this part as follows: 

(1) CO2 emission standards apply as specified in this paragraph (a)(1). The 

applicable test cycle for measuring CO2 emissions differs depending on the engine 

family’s primary intended service class and the extent to which the engines will be (or 

were designed to be) used in tractors. For medium and heavy heavy-duty engines 

certified as tractor engines, measure CO2 emissions using the steady-state duty cycle 

specified in 40 CFR 86.1362 (referred to as the SET cycle). This is intended for 

engines designed to be used primarily in tractors and other line-haul applications. 

Note that the use of some SET-certified tractor engines in vocational applications 

does not affect your certification obligation under this paragraph; see other provisions 

of this part and 40 CFR part 1037 for limits on using engines certified to only one 

cycle. For medium and heavy heavy-duty engines certified as both tractor and 

vocational engines, measure CO2 emissions using the steady-state duty cycle and the 

transient duty cycle (sometimes referred to as the FTP engine cycle), both of which 

are specified in 40 CFR part 86, subpart N. This is intended for engines that are 

designed for use in both tractor and vocational applications. For all other engines 

(including all spark-ignition engines), measure CO2 emissions using the transient duty

cycle specified in 40 CFR part 86, subpart N.

(i) The CO2 standard for model year 2016 and later spark-ignition engines is 627 

g/hp-hr.
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(ii) The following CO2 standards apply for compression-ignition engines and all 

other engines (in g/hp-hr):

Model Years Light 

HeavyDuty

Medium HeavyDuty –

Vocational

Heavy HeavyDuty –VocationalMedium HeavyDuty –TractorHeavy HeavyDuty – Tractor

2014-2016 600 600 567 502 475

2017 and 

later

576 576 555 487 460

(2) The CH4 emission standard is 0.10 g/hp-hr when measured over the transient duty

cycle specified in 40 CFR part 86, subpart N. This standard begins in model year 

2014 for compression ignition engines and in model year 2016 for spark-ignition 

engines. Note that this standard applies for all fuel types just as the other standards of 

this section do. 

(3) The N2O emission standard for all model year 2014 and later engines is 0.10 

g/hp-hr when measured over the transient duty cycle specified in 40 CFR part 86, 

subpart N. This standard begins in model year 2014 for compression ignition engines 

and in model year 2016 for spark-ignition engines.

(4) This paragraph (a)(4) describes alternate emission standards for engines certified 

under 40 CFR 1037.150(m). The standards of paragraphs (a)(1) through (3) do not 

apply for these engines. The standards in this paragraph (a)(4) apply for emissions 

measured with the engine installed in a complete vehicle consistent with the 

provisions of 40 CFR 1037.150(m)(6). The CO2 standard for the engines equals the 

test result specified in 40 CFR 1037.150(m)(6) multiplied by 1.10 and rounded to the 

nearest 0.1 g/mile. The N2O and CH4 standards are both 0.05 g/mile (or any alternate 

standards that apply to the corresponding vehicle test group). The only requirements 

of this part that apply to these engines are those in this paragraph (a)(4) and those in 

§§1036.115 through 1036.135.

(b) Family certification levels. You must specify a CO2 Family Certification Level 

(FCL) for each engine family. The FCL may not be less than the certified emission level 

for the engine family. The CO2 Family Emission Limit (FEL) for the engine family is 

equal to the FCL multiplied by 1.03. 

(c) Averaging, banking, and trading. You may generate or use emission credits under the 

averaging, banking, and trading (ABT) program described in subpart H of this part for 

demonstrating compliance with CO2 emission standards. Credits (positive and negative) 

are calculated from the difference between the FCL and the applicable emission standard. 

As described in §1036.705, you may use CO2 credits to certify your engine families to 

FELs for N2O and/or CH4, instead of the N2O/CH4 standards of this section that 

otherwise apply. Except as specified in § 1036.150 and 1036.705, you may not generate 

or use credits for N2O or CH4 emissions. 
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(d) Useful life. Your engines must meet the exhaust emission standards of this section 

throughout their full useful life, expressed in service miles or calendar years, whichever 

comes first. The useful life values applicable to the criteria pollutant standards of 40 

CFR part 86 apply for the standards of this section.

(e) Applicability for testing. The emission standards in this subpart apply as specified in 

this paragraph (e) to all duty-cycle testing (according to the applicable test cycles) of 

testable configurations, including certification, selective enforcement audits, and in-use 

testing. The CO2 FCLs serve as the CO2 emission standards for the engine family with 

respect to certification and confirmatory testing instead of the standards specified in 

paragraph (a)(1) of this section. The FELs serve as the emission standards for the engine 

family with respect to all other testing. See §§1036.235 and 1036.241 to determine 

which engine configurations within the engine family are subject to testing. 

(f) Multi-fuel engines. For dual-fuel, multi-fuel, and flexible-fuel engines, perform 

exhaust testing on each fuel type (for example, gasoline and E85). 

(1) This paragraph (f)(1) applies where you demonstrate the relative amount of each 

fuel type that your engines consume in actual use. Based on your demonstration, we 

will specify a weighting factor and allow you to submit the weighted average of your 

emission results. For example, if you certify an E85 flexible-fuel engine and we 

determine the engine will produce one-half of its work from E85 and one-half of its 

work from gasoline, you may average your E85 and gasoline emission results.

(2) If you certify your engine family to N2O and/or CH4 FELs the FELs apply for 

testing on all fuel types for which your engine is designed, to the same extent as 

criteria emission standards apply.

§ 1036.115 Other requirements.

(a) The warranty and maintenance requirements, adjustable parameter provisions, and 

defeat device prohibition of 40 CFR part 86 apply with respect to the standards of this 

part.

(b) [Reserved.]

§ 1036.130 Installation instructions for vehicle manufacturers.

(a) If you sell an engine for someone else to install in a vehicle, give the engine installer 

instructions for installing it consistent with the requirements of this part. Include all 

information necessary to ensure that an engine will be installed in its certified 

configuration.

(b) Make sure these instructions have the following information:

(1) Include the heading: “Emission-related installation instructions”.
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(2) State: “Failing to follow these instructions when installing a certified engine in a 

heavy-duty motor vehicle violates federal law, subject to fines or other penalties as 

described in the Clean Air Act.”

(3) Provide all instructions needed to properly install the exhaust system and any

other components.

(4) Describe any necessary steps for installing any diagnostic system required under 

40 CFR part 86.

(5) Describe how your certification is limited for any type of application. For 

example, if you certify heavy heavy-duty engines to the CO2 standards using only 

steady-state testing, you must make clear that the engine may be installed only in 

tractors.

(6) Describe any other instructions to make sure the installed engine will operate 

according to design specifications in your application for certification. This may

include, for example, instructions for installing aftertreatment devices when installing 

the engines.

(7) State: “If you install the engine in a way that makes the engine’s emission control 

information label hard to read during normal engine maintenance, you must place a 

duplicate label on the vehicle, as described in 40 CFR 1068.105.”

(c) You do not need installation instructions for engines that you install in your own 

vehicles. 

(d) Provide instructions in writing or in an equivalent format. For example, you may post 

instructions on a publicly available website for downloading or printing. If you do not 

provide the instructions in writing, explain in your application for certification how you 

will ensure that each installer is informed of the installation requirements. 

§ 1036.135 Labeling.

Label your engines as described in 40 CFR 86.007-35(a)(3), with the following additional 

information:

(a) [Reserved.]

(b) Identify the emission control system. Use terms and abbreviations as described in 40 

CFR 1068.45 or other applicable conventions. 

(c) Identify any limitations on your certification. For example, if you certify heavy

heavy-duty engines to the CO2 standards using only transient cycle testing, include the 

statement “VOCATIONAL VEHICLES ONLY”. 
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(d) You may ask us to approve modified labeling requirements in this part 1036 if you 

show that it is necessary or appropriate. We will approve your request if your alternate 

label is consistent with the requirements of this part. We may also specify modified 

labeling requirement to be consistent with the intent of 40 CFR part 1037. 

§ 1036.140 Primary intended service class.

You must identify a single primary intended service class for each compression-ignition 

engine family. Select the class that best describes vehicles for which you design and 

market the engine. The three primary intended service classes are light heavy-duty, 

medium heavy-duty, and heavy heavy-duty. Note that provisions that apply based on 

primary intended service class often treat spark-ignition engines as if they were a separate

service class. 

(a) Light heavy-duty engines usually are not designed for rebuild and do not have 

cylinder liners. Vehicle body types in this group might include any heavy-duty vehicle 

built for a light-duty truck chassis, van trucks, multi-stop vans, motor homes and other 

recreational vehicles, and some straight trucks with a single rear axle. Typical 

applications would include personal transportation, light-load commercial delivery, 

passenger service, agriculture, and construction. The GVWR of these vehicles is 

normally below 19,500 pounds.

(b) Medium heavy-duty engines may be designed for rebuild and may have cylinder 

liners. Vehicle body types in this group would typically include school buses, straight 

trucks with dual rear axles, city tractors, and a variety of special purpose vehicles such as 

small dump trucks, and refuse trucks. Typical applications would include commercial 

short haul and intra-city delivery and pickup. Engines in this group are normally used in 

vehicles whose GVWR ranges from 19,500 to 33,000 pounds.

(c) Heavy heavy-duty engines are designed for multiple rebuilds and have cylinder liners. 

Vehicles in this group are normally tractors, trucks, and buses used in inter-city, longhaul applications. These vehicles normally exceed 33,000 pounds GVWR.

§ 1036.150 Interim provisions.

The provisions in this section apply instead of other provisions in this part. 

(a) Early banking of greenhouse gas emissions. You may generate CO2 emission credits 

for engines you certify in model year 2013 (2015 for spark-ignition engines) to the 

standards of § 1036.108. 

(1)Except as specified in paragraph (a)(2) of this section, to generate early credits, 

you must certify your entire U.S.-directed production volume within that averaging 

set to these standards. This means that you may not generate early credits while you 
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produce engines in the averaging set that are certified to the criteria pollutant 

standards but not to the greenhouse gas standards. Calculate emission credits as 

described in subpart H of this part relative to the standard that would apply for model 

year 2014 (2016 for spark-ignition engines). 

(2) You may generate early credits for an individual compression-ignition engine 

family where you demonstrate that you have improved a model year 2013 engine 

model’s CO2 emissions relative to its 2012 baseline level and certify it to an FCL

below the applicable standard. Calculate emission credits as described in subpart H 

of this part relative to the lesser of the standard that would apply for model year 2014 

engines or the baseline engine’s CO2 emission rate. Use the smaller U.S.-directed 

production volume of the 2013 engine family or the 2012 baseline engine family. We 

will not allow you to generate emission credits under this paragraph (a)(2) unless we 

determine that your 2013 engine is the same engine as the 2012 baseline or that it 

replaces it.

(3) You may bank credits equal to the surplus credits you generate under this 

paragraph multiplied by 1.50. For example, if you have 10 Mg of surplus credits for 

model year 2013, you may bank 15 Mg of credits. Credit deficits for an averaging set 

prior to model year 2014 (2016 for spark-ignition engines) do not carry over to model 

year 2014 (2016 for spark-ignition engines). We recommend that you notify us of 

your intent to use this provision before submitting your applications.

(b) Model year 2014 N2O standards. In model year 2014 and earlier, manufacturers may 

show compliance with the N2O standards using an engineering analysis. This allowance 

also applies for later families certified using carryover CO2 data from model 2014 

consistent with §1036.235(d).

(c) Engine cycle classification. Engines meeting the definition of spark-ignition, but 

regulated as diesel engines under 40 CFR part 86, must be certified to the requirements 

applicable to compression-ignition engines under this part. Such engines are deemed to 

be compression-ignition engines for purposes of this part. Similarly, engines meeting the 

definition of compression-ignition, but regulated as Otto-cycle under 40 CFR part 86 

must be certified to the requirements applicable to spark-ignition engines under this part. 

Such engines are deemed to be spark-ignition engines for purposes of this part.

(d) Small manufacturers. Manufacturers meeting the small business criteria specified for 

“Gasoline Engine and Engine Parts Manufacturing” or “Other Engine Equipment 

Manufacturers” in 13 CFR 121.201 are not subject to the greenhouse gas emission 

standards in § 1036.108. Qualifying manufacturers must notify the Designated 

Compliance Officer before importing or introducing into U.S. commerce excluded 

engines. This notification must include a description of the manufacturer’s qualification 

as a small business under 13 CFR 121.201. You must label your excluded vehicles with 

the statement: “THIS ENGINE IS EXCLUDED UNDER 40 CFR 1037.150(c).” 

(e) Alternate phase-in standards. Where a manufacturer certifies all of its model year 

2013 compression-ignition engines within a given primary intended service class to the 

applicable alternate standards of this paragraph (e), its compression-ignition engines 
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within that primary intended service class are subject to the standards of this paragraph 

for model years 2013 through 2016. This means that once a manufacturer chooses to 

certify a primary intended service class to the standards of this paragraph (e), it is not 

allowed to opt out of these standards. Engines certified to these standards are not eligible 

for early credits under paragraph (a) of this section.

Tractors LHD Engines MHD Engines HHD Engines

Model Years 2013-

2015

NA 512 g/hp-hr 485 g/hp-hr

Model Years 2016 

and latera

NA 487 g/hp-hr 460 g/hp-hr

Vocational LHD Engines MHD Engines HHD Engines

Model Years 2013-

2015

618 g/hp-hr 618 g/hp-hr 577 g/hp-hr

Model Years 2016 

and later†

576 g/hp-hr 576 g/hp-hr 555 g/hp-hr

a Note: these alternate standards for 2016 and later are the same as the otherwise 

applicable standards for 2017 and later.

(f) Separate OBD families. This paragraph (f) applies where you separately certify

engines for the purpose of applying OBD requirements (for engines used in vehicles 

under 14,000 pounds GVWR) from non-OBD engines that could be certified as a single 

engine family. You may treat the two engine families as a single engine family in certain 

respects for the purpose of this part, as specified in this paragraph (f).

(1) This paragraph applies only where the two families are identical in all respects 

except for the engine ratings offered and the inclusion of OBD.

(2) For purposes of this part and 40 CFR part 86, the two families remain two 

separate families except for the following:

(i) Specify the testable configurations of the non-OBD engine family as the 

testable configurations for the OBD family.
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(ii) Submit the same CO2, N2O, and CH4 emission data for both engine families. 

(g) Assigned deterioration factors. You may use assigned deterioration factors (DFs) 

without performing your own durability emission tests or engineering analysis as 

described in this paragraph (g).

(1) You may use an assigned additive DF of 0.0 g/hp-hr for CO2 emissions from 

engines that do not use advanced or innovative technologies. If we determine it to be 

consistent with good engineering judgment, we may allow you to use an assigned 

additive DF of 0.0 g/hp-hr for CO2 emissions from your engines with advanced or 

innovative technologies. 

(2) You may use an assigned additive DF of 0.02 g/hp-hr for N2O emissions from any 

engine. 

(3) You may use an assigned additive DF of 0.02 g/hp-hr for CH4 emissions from any 

engine.

(h) Advanced technology credits. If you generate credits from engines certified for 

advanced technology you may multiply these credits by 1.5, except that you may not 

apply this multiplier and the early-credit multiplier of paragraph (a) of this section.

(i) CO2 credits for low N2O emissions. If you certify your model year 2014, 2015, or 

2016 engines to an N2O FEL less than 0.04 g/hp-hr (provided you measure N2O 

emissions from your emission-data engines), you may generate additional CO2 credits 

under this paragraph (i). Calculate the additional CO2 credits from the following 

equation instead of the equation in §1036.705:

CO2 Credits (Mg) = (0.04 – FELN2O) · (CF) · (Volume) · (UL) · (10-6) · (298)

Subpart C—Certifying Engine Families

§ 1036.205 What must I include in my application?

Submit an application for certification as described in 40 CFR 86.007-21, with the 

following additional information:

(a) Describe the engine family’s specifications and other basic parameters of the engine’s 

design and emission controls with respect to compliance with the requirements of this 

part. Describe in detail all system components for controlling greenhouse gas emissions, 

including all auxiliary emission control devices (AECDs) and all fuel-system components 

you will install on any production or test engine. Identify the part number of each 

component you describe. For this paragraph (a), treat as separate AECDs any devices 

that modulate or activate differently from each other. 
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(b) Describe any test equipment and procedures that you used if you performed any tests 

that did not also involve measurement of criteria pollutants. Describe any special or 

alternate test procedures you used (see 40 CFR 1065.10(c)). 

(c) Include the emission-related installation instructions you will provide if someone else 

installs your engines in their vehicles (see § 1036.130).

(d) Describe the label information specified in § 1036.135. We may require you to 

include a copy of the label.

(e) Identify the FCLs with which you are certifying engines in the engine family. The 

actual U.S.-directed production volume of configurations that have emission rates at or 

below the FCL must be at least one percent of your total actual (not projected) U.S.-

directed production volume for the engine family. Identify configurations within the 

family that have emission rates at or below the FCL and meet the one percent 

requirement. For example, if your total U.S.-directed production volume for the engine 

family is 10,583, and the U.S.-directed production volume for the tested rating is 75 

engines, then you can comply with this provision by setting your FCL so that one more 

rating with a U.S.-directed production volume of at least 31 engines meets the FCL. 

Where applicable, also identify other testable configurations required under 

§1036.230(b)(2).

(f) Identify the engine family’s deterioration factors and describe how you developed 

them (see § 1036.241). Present any test data you used for this.

(g) Present emission data to show that you meet emission standards, as follows:

(1) Present exhaust emission data for CO2, CH4, and N2O on an emission-data engine 

to show that your engines meet the applicable emission standards we specify in 

§ 1036.108. Show emission figures before and after applying deterioration factors for 

each engine. In addition to the composite results, show individual measurements for 

cold-start testing and hot-start testing over the transient test cycle. 

(2) Note that § 1036.235 allows you to submit an application in certain cases without 

new emission data.

(h) State whether your certification is limited for certain engines. For example, if you 

certify heavy heavy-duty engines to the CO2 standards using only transient testing, the 

engines may be installed only in vocational vehicles.

(i) Unconditionally certify that all the engines in the engine family comply with the 

requirements of this part, other referenced parts of the CFR, and the Clean Air Act. Note 

that § 1036.235 specifies which engines to test to show that engines in the entire family 

comply with the requirements of this part. 

(j) Include the information required by other subparts of this part. For example, include 

the information required by § 1036.725 if you participate in the ABT program.
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(k) Include the warranty statement and maintenance instructions if we request them. 

(l) Include other applicable information, such as information specified in this part or 40 

CFR part 1068 related to requests for exemptions.

(m) For imported engines or equipment, identify the following:

(1) Describe your normal practice for importing engines. For example, this may

include identifying the names and addresses of any agents you have authorized to 

import your engines. Engines imported by nonauthorized agents are not covered by

your certificate.

(2) The location of a test facility in the United States where you can test your engines 

if we select them for testing under a selective enforcement audit, as specified in 40 

CFR part 1068, subpart E.

§ 1036.210 Preliminary approval before certification.

If you send us information before you finish the application, we may review it and make 

any appropriate determinations, especially for questions related to engine family

definitions, auxiliary emission control devices, adjustable parameters, deterioration 

factors, testing for service accumulation, and maintenance. Decisions made under this 

section are considered to be preliminary approval, subject to final review and approval. 

We will generally not reverse a decision where we have given you preliminary approval, 

unless we find new information supporting a different decision. If you request 

preliminary approval related to the upcoming model year or the model year after that, we 

will make best-efforts to make the appropriate determinations as soon as practicable. We 

will generally not provide preliminary approval related to a future model year more than 

two years ahead of time.

§ 1036.225 Amending my application for certification.

Before we issue you a certificate of conformity, you may amend your application to 

include new or modified engine configurations, subject to the provisions of this section. 

After we have issued your certificate of conformity, but before the end of the model year, 

you may send us an amended application requesting that we include new or modified 

engine configurations within the scope of the certificate, subject to the provisions of this 

section. You must amend your application if any changes occur with respect to any

information that is included or should be included in your application.

(a) You must amend your application before you take any of the following actions:

(1) Add an engine configuration to an engine family. In this case, the engine 

configuration added must be consistent with other engine configurations in the engine 
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family with respect to the criteria listed in § 1036.230.

(2) Change an engine configuration already included in an engine family in a way that 

may affect emissions, or change any of the components you described in your 

application for certification. This includes production and design changes that may

affect emissions any time during the engine's lifetime.

(3) Modify an FEL and FCL for an engine family as described in paragraph (f) of this 

section. 

(b) To amend your application for certification, send the relevant information to the 

Designated Compliance Officer.

(1) Describe in detail the addition or change in the engine model or configuration you 

intend to make.

(2) Include engineering evaluations or data showing that the amended engine family

complies with all applicable requirements. You may do this by showing that the 

original emission-data engine is still appropriate for showing that the amended family

complies with all applicable requirements.

(3) If the original emission-data engine for the engine family is not appropriate to 

show compliance for the new or modified engine configuration, include new test data 

showing that the new or modified engine configuration meets the requirements of this 

part.

(c) We may ask for more test data or engineering evaluations. You must give us these 

within 30 days after we request them. 

(d) For engine families already covered by a certificate of conformity, we will determine 

whether the existing certificate of conformity covers your newly added or modified 

engine. You may ask for a hearing if we deny your request (see § 1036.820).

(e) For engine families already covered by a certificate of conformity, you may start 

producing the new or modified engine configuration anytime after you send us your 

amended application and before we make a decision under paragraph (d) of this section. 

However, if we determine that the affected engines do not meet applicable requirements, 

we will notify you to cease production of the engines and may require you to recall the 

engines at no expense to the owner. Choosing to produce engines under this paragraph 

(e) is deemed to be consent to recall all engines that we determine do not meet applicable 

emission standards or other requirements and to remedy the nonconformity at no expense 

to the owner. If you do not provide information required under paragraph (c) of this 

section within 30 days after we request it, you must stop producing the new or modified 

engines.

(f) You may ask us to approve a change to your FEL in certain cases after the start of 

production, but before the end of the model year. If you change an FEL for CO2, your 

FCL for CO2 is automatically set to your new FEL divided by 1.03. The changed FEL 
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may not apply to engines you have already introduced into U.S. commerce, except as 

described in this paragraph (f). If we approve a changed FEL after the start of 

production, you must include the new FEL on the emission control information label for 

all engines produced after the change. You may ask us to approve a change to your FEL 

in the following cases:

(1) You may ask to raise your FEL for your engine family at any time. In your 

request, you must show that you will still be able to meet the emission standards as 

specified in subparts B and H of this part. Use the appropriate FELs/FCLs with 

corresponding production volumes to calculate emission credits for the model year, as 

described in subpart H of this part.

(2) You may ask to lower the FEL for your engine family only if you have test data 

from production engines showing that emissions are below the proposed lower FEL 

(or below the proposed FCL for CO2). The lower FEL/FCL applies only to engines 

you produce after we approve the new FEL/FCL. Use the appropriate FELs/FCLs 

with corresponding production volumes to calculate emission credits for the model 

year, as described in subpart H of this part.

§ 1036.230 Selecting engine families.

See 40 CFR 86.001-24 for instructions on how to divide your product line into families of 

engines that are expected to have similar emission characteristics throughout the useful 

life. You must certify your engines to the standards of § 1036.108 using the same engine 

families you use for criteria pollutants under 40 CFR part 86. The following provisions 

also apply:

(a) Engines certified as hybrid engines or power packs may not be included in an engine 

family with engines with conventional powertrains. Note that this does not prevent you 

from including engines in a conventional family if they are used in hybrid vehicles, as 

long as you certify them conventionally.

(b) If you certify engines in the family for use as both vocational and tractor engines, you 

must split your family into two separate subfamilies. Indicate in the application for 

certification that the engine family is to be split. 

(1) Calculate emission credits relative to the vocational engine standard for the 

number of engines sold into vocational applications and relative to the tractor engine 

standard for the number of engines sold into non-vocational tractor applications. You 

may assign the numbers and configurations of engines within the respective 

subfamilies at any time before submitting the end-of-year report required by 

§ 1036.730. If the family participates in averaging, banking, or trading, you must 

identify the type of vehicle in which each engine is installed; we may alternatively

allow you to use statistical methods to determine this for a fraction of your engines.

Keep records to document this determination. 
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(2) If you restrict use of the test configuration for your split family to only tractors, or 

only vocational vehicles, you must identify a second testable configuration for the 

other type of vehicle (or an unrestricted configuration). Identify this configuration in 

your application for certification. The FCL for the engine family applies for this 

configuration as well as the primary test configuration. 

(c) If you certify in separate engine families engines that could have been certified in 

vocational and tractor engine subfamilies in the same engine family, count the two 

families as one family for purposes of determining your obligations with respect to the 

OBD requirements and in-use testing requirements of 40 CFR part 86. Indicate in the 

applications for certification that the two engine families are covered by this paragraph 

(c).

(d) Engine configurations within an engine family must use equivalent greenhouse gas 

emission controls. Unless we approve it, you may not produce nontested configurations 

without the same emission control hardware included on the tested configuration. We 

will only approve it if you demonstrate that the exclusion of the hardware does not 

increase greenhouse gas emissions.

§ 1036.235 Testing requirements for certification.

This section describes the emission testing you must perform to show compliance with 

the greenhouse gas emission standards in § 1036.108.

(a) Select a single emission-data engine from each engine family as specified in 40 CFR 

part 86. The standards of this part apply only with respect to emissions measured from 

this tested configuration and other configurations identified in §1036.205(e). Note that 

configurations identified in §1036.205(e) are considered to be “tested configurations” 

whether or not you actually tested them for certification. However, you must apply the 

same (or equivalent) emission controls to all other engine configurations in the engine 

family. 

(b) Test your emission-data engines using the procedures and equipment specified in 

subpart F of this part. In the case of dual-fuel and flexible-fuel engines, measure 

emissions when operating with each type of fuel for which you intend to certify the 

engine. Measure CO2 , CH4, and N2O emissions using the specified duty cycle(s), 

including cold-start and hot-start testing as specified in 40 CFR part 86, subpart N. If 

you are certifying the engine for use in tractors, you must measure CO2 emissions using 

the SET cycle and measure CH4, and N2O emissions using the transient cycle. If you are 

certifying the engine for use in vocational applications, you must measure CO2 , CH4, and 

N2O emissions using the specified transient duty cycle, including cold-start and hot-start 

testing as specified in 40 CFR part 86, subpart N. Engines certified for use in tractors 

may also be used in vocational vehicles; however, you may not knowingly circumvent 

the intent of this part (to reduce in-use emissions of CO2) by certifying engines designed 

for vocational vehicles (and rarely used in tractors) to the SET and not the transient cycle. 
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For example, we would generally not allow you to certify all your engines to the SET 

without certifying any to the transient cycle. You may certify your engine family for 

both tractor and vocational use by submitting CO2 emission data from both SET and 

transient cycle testing and specifying FCLs for both.

(c) We may measure emissions from any of your emission-data engines.

(1) We may decide to do the testing at your plant or any other facility. If we do this, 

you must deliver the engine to a test facility we designate. The engine you provide 

must include appropriate manifolds, aftertreatment devices, electronic control units, 

and other emission-related components not normally attached directly to the engine 

block. If we do the testing at your plant, you must schedule it as soon as possible and 

make available the instruments, personnel, and equipment we need.

(2) If we measure emissions on your engine, the results of that testing become the 

official emission results for the engine. Unless we later invalidate these data, we may

decide not to consider your data in determining if your engine family meets 

applicable requirements.

(3) Before we test one of your engines, we may set its adjustable parameters to any

point within the physically adjustable ranges.

(4) Before we test one of your engines, we may calibrate it within normal production 

tolerances for anything we do not consider an adjustable parameter. For example, 

this would apply for an engine parameter that is subject to production variability

because it is adjustable during production, but is not considered an adjustable 

parameter (as defined in § 1036.801) because it is permanently sealed.

(d) You may ask to use carryover emission data from a previous model year instead of 

doing new tests, but only if all the following are true:

(1) The engine family from the previous model year differs from the current engine 

family only with respect to model year or other characteristics unrelated to emissions.

(2) The emission-data engine from the previous model year remains the appropriate 

emission-data engine under paragraph (b) of this section.

(3) The data show that the emission-data engine would meet all the requirements that 

apply to the engine family covered by the application for certification.

(e) We may require you to test a second engine of the same configuration in addition to 

the engine tested under paragraph (a) of this section.

(f) If you use an alternate test procedure under 40 CFR 1065.10 and later testing shows 

that such testing does not produce results that are equivalent to the procedures specified 

in subpart F of this part, we may reject data you generated using the alternate procedure.
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§ 1036.241 Demonstrating compliance with greenhouse gas pollutant standards.

(a) For purposes of certification, your engine family is considered in compliance with the 

emission standards in § 1036.108 if all emission-data engines representing the tested 

configuration of that engine family have test results showing official emission results and 

deteriorated emission levels at or below the standards. Note that your FCLs are 

considered to be the applicable emission standards with which you must comply for 

certification.

(b) Your engine family is deemed not to comply if any emission-data engine representing 

the tested configuration of that engine family has test results showing an official emission 

result or a deteriorated emission level for any pollutant that is above an applicable 

emission standard (generally the FCL). Note that you may increase your FCL if any 

certification test results exceed your initial FCL.

(c) Apply deterioration factors to the measured emission levels for each pollutant to show 

compliance with the applicable emission standards. Your deterioration factors must take 

into account any available data from in-use testing with similar engines. Apply

deterioration factors as follows:

(1) Additive deterioration factor for greenhouse gas emissions. Except as specified in 

paragraph (c)(2) of this section, use an additive deterioration factor for exhaust 

emissions. An additive deterioration factor is the difference between exhaust 

emissions at the end of the useful life and exhaust emissions at the low-hour test 

point. In these cases, adjust the official emission results for each tested engine at the 

selected test point by adding the factor to the measured emissions. If the factor is less 

than zero, use zero. Additive deterioration factors must be specified to one more 

decimal place than the applicable standard. 

(2) Multiplicative deterioration factor for greenhouse gas emissions. Use a 

multiplicative deterioration factor for a pollutant if good engineering judgment calls 

for the deterioration factor for that pollutant to be the ratio of exhaust emissions at the 

end of the useful life to exhaust emissions at the low-hour test point. Adjust the 

official emission results for each tested engine at the selected test point by

multiplying the measured emissions by the deterioration factor. If the factor is less 

than one, use one. A multiplicative deterioration factor may not be appropriate in 

cases where testing variability is significantly greater than engine-to-engine 

variability. Multiplicative deterioration factors must be specified to one more 

significant figure than the applicable standard. 

(3) Sawtooth deterioration patterns. The deterioration factors described in paragraphs 

(c)(1) and (2) of this section assume that the highest useful life emissions occur either 

at the end of useful life or at the low-hour test point. The provisions of this paragraph 

(c)(3) apply where good engineering judgment indicates that the highest useful life 

emissions will occur between these two points. For example, emissions may increase 

with service accumulation until a certain maintenance step is performed, then return 

to the low-hour emission levels and begin increasing again. Such a pattern may occur 
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with battery-based electric hybrid engines. Base deterioration factors for engines 

with such emission patterns on the difference between (or ratio of) the point at which 

the highest emissions occur and the low-hour test point. Note that this applies for 

maintenance-related deterioration only where we allow such critical emission-related 

maintenance. 

(d) Collect emission data using measurements to one more decimal place than the 

applicable standard. Apply the deterioration factor to the official emission result, as 

described in paragraph (c) of this section, then round the adjusted figure to the same 

number of decimal places as the emission standard. Compare the rounded emission 

levels to the emission standard for each emission-data engine.

(e) If you identify more than one configuration in §1036.205(e), we may test (or require 

you to test) any of the identified configurations. We may also require you to provide an 

engineering analysis that demonstrates that untested configurations listed in §1036.205(e) 

comply with their FCL.

§ 1036.250 Reporting and recordkeeping for certification.

(a) Within 90 days after the end of the model year, send the Designated Compliance 

Officer a report including the total U.S.-directed production volume of engines you 

produced in each engine family during the model year (based on information available at 

the time of the report). Report the production by serial number and engine configuration. 

Small manufacturers may omit this requirement. You may combine this report with 

reports required under subpart H of this part.

(b) Organize and maintain the following records:

(1) A copy of all applications and any summary information you send us.

(2) Any of the information we specify in § 1036.205 that you were not required to 

include in your application.

(c) Keep routine data from emission tests required by this part (such as test cell 

temperatures and relative humidity readings) for one year after we issue the associated 

certificate of conformity. Keep all other information specified in this section for eight 

years after we issue your certificate.

(d) Store these records in any format and on any media, as long as you can promptly send 

us organized, written records in English if we ask for them. You must keep these records 

readily available. We may review them at any time. 

§ 1036.255 What decisions may EPA make regarding my certificate of conformity?
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(a) If we determine your application is complete and shows that the engine family meets 

all the requirements of this part and the Act, we will issue a certificate of conformity for 

your engine family for that model year. We may make the approval subject to additional 

conditions. 

(b) We may deny your application for certification if we determine that your engine 

family fails to comply with emission standards or other requirements of this part or the 

Clean Air Act. We will base our decision on all available information. If we deny your 

application, we will explain why in writing.

(c) In addition, we may deny your application or suspend or revoke your certificate if you 

do any of the following:

(1) Refuse to comply with any testing or reporting requirements.

(2) Submit false or incomplete information (paragraph (e) of this section applies if 

this is fraudulent). This includes doing anything after submission of your application 

to render any of the submitted information false or incomplete.

(3) Render inaccurate any test data.

(4) Deny us from completing authorized activities despite our presenting a warrant or 

court order (see 40 CFR 1068.20). This includes a failure to provide reasonable 

assistance. However, you may ask us to reconsider our decision by showing that your 

failure under this paragraph (c)(4) did not involve engines related to the certificate or 

application in question to a degree that would justify our decision. 

(5) Produce engines for importation into the United States at a location where local 

law prohibits us from carrying out authorized activities.

(6) Fail to supply requested information or amend your application to include all 

engines being produced.

(7) Take any action that otherwise circumvents the intent of the Act or this part, with 

respect to your engine family.

(d) We may void the certificate of conformity for an engine family if you fail to keep 

records, send reports, or give us information as required under this part or the Act. Note 

that these are also violations of 40 CFR 1068.101(a)(2).

(e) We may void your certificate if we find that you intentionally submitted false or 

incomplete information. This includes rendering submitted information false or 

incomplete after submission.

(f) If we deny your application or suspend, revoke, or void your certificate, you may ask 

for a hearing (see § 1036.820).
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Subpart D—[Reserved]

Subpart E—In-use Testing

§ 1036.401 In-use testing.

We may perform in-use testing of any engine family subject to the standards of this part, 

consistent with the provisions of § 1036.235. Note that this provisions does not affect 

your obligation to test your in-use engines as described in 40 CFR part 86, subpart T.

Subpart F—Test Procedures

§ 1036.501 How do I run a valid emission test?

(a) Use the equipment and procedures specified in 40 CFR 86.1305 to determine whether 

engines meet the emission standards in § 1036.108. 

(b) You may use special or alternate procedures to the extent we allow them under 40 

CFR 1065.10.

(c) This subpart is addressed to you as a manufacturer, but it applies equally to anyone 

who does testing for you, and to us when we perform testing to determine if your engines 

meet emission standards.

(d) For engines that use aftertreatment technology with infrequent regeneration events, 

invalidate any test interval in which such a regeneration event occurs with respect to CO2, 

N2O, and CH4 measurements.

(e) Test hybrid engines as described in 40 CFR part 1065 and § 1036.525.

(f) [Reserved.] 

(g) If your engine requires special components for proper testing, you must provide any 

such components to us if we ask for them.

§ 1036.525 Hybrid engines. 

(a) If your engine system includes features that recover and store energy during engine 

motoring operation test the engine as described in paragraph (d) of this section. See 

§ 1036.615(a)(2) for engine systems intended to include features that recover and store 

energy from braking unrelated to engine motoring operation. For purposes of this 

paragraph, features that recover energy between the engine and transmission are 
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considered “related to engine motoring”.

(b) If you produce a hybrid engine designed with power take-off capability and sell the 

engine coupled with a transmission, you may calculate a reduction in CO2 emissions 

resulting from the power take-off operation as described in 40 CFR 1037.525. Use good 

engineering judgment to use the vehicle-based procedures to quantify the CO2 reduction 

for your engines.

(c) The hardware that must be included in these tests is the engine, the hybrid electric 

motor, the rechargeable energy storage system (RESS) and the power electronics between 

the hybrid electric motor and the RESS. You may ask us to modify the provisions of this 

section to allow testing non-electric hybrid vehicles, consistent with good engineering 

judgment.

(d) Measure emissions using the same procedures that apply for testing non-hybrid 

engines under this part, except as specified otherwise in this part and/or 40 CFR part 

1065. If you test hybrid engines using the SET, deactivate the hybrid features unless we 

have specified otherwise. The five differences that apply under this section are related to 

engine mapping, engine shutdown during the test cycle, calculating work, limits on 

braking energy, and state of charge constraints.

(1) Map the engine as specified in 40 CFR 1065.510. This requires separate torque 

maps for the engine with and without the hybrid features active. For transient testing, 

denormalize the test cycle using the map generated with the hybrid feature active. 

For steady-state testing, denormalize the test cycle using the map generated with the 

hybrid feature inactive.

(2) This paragraph applies if the engine will be configured in actual use such that the 

engine will automatically shutdown during idle operation, you may let the engine 

speed equal zero during the idle portions of the test cycle.

(3) Follow 1065.650(d) to calculate the work done over the cycle except as specified 

in this paragraph (d)(3). For the positive work over the cycle set negative power from 

hybrid to zero. For the negative work over the cycle set the positive power to zero 

and the set the non-hybrid power to zero. 

(4)(i) Calculate brake energy fraction, xb, as the integrated negative work over the 

cycle divided by the integrated positive work over the cycle according to equation 

1036.525-1. Calculate the brake energy limit for the engine, xbl, according to 

equation 1036.525-2. If xb is less than xbl, use the integrated positive work for 

your emission calculations. If the xb is greater than xbl use equation 1036.525-3 to 

calculate the positive work done over the cycle. Use Wcycle as the integrated 

positive work when calculating brake-specific emissions. To avoid the need to 

delete extra brake work from positive work you may set an instantaneous brake 

target that will prevent xb from being larger than xbl.

neg

b

pos

W

x

W

 Eq. 1036.525-1

4

max 4.158 10 0.2247 bl x P 

   

 

Eq. 1036.525-2
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W W cycle   pos  W x neg   bl Wpos 

 Eq. 1036.525-3

(ii) The following definitions of terms apply for this paragraph (d)(4):

xb = the brake energy fraction.

Wneg = the negative work over the cycle.

Wpos = the positive work over the cycle.

xbl = the brake energy fraction limit.

Pmax = the maximum power of the engine with the hybrid system engaged (kW).

Wcycle = the work over the cycle when xb is greater than xbl.

(iii) Note that these calculations are specified with SI units (such as kW), 

consistent with 40 CFR part 1065. Emission results are converted to g/hp-hr at 

the end of the calculations.

(5) Correct for the net energy change of the energy storage device as described in 40 

CFR 1066.501.

§ 1036.530 Calculating greenhouse gas emission rates.

This section describes how to calculate official emission results for CO2, CH4, and N2O.

(a) Calculate brake-specific emission rates for each applicable duty cycle as specified in 

40 CFR 1065.650. Do not apply infrequent regeneration adjustment factors to your 

results.

(b) Adjust CO2 emission rates calculated under paragraph (a) of this section for measured 

test fuel properties as specified in this paragraph (b) to obtain the official emission 

results. You are not required to apply this adjustment for fuels containing at least 75 

percent pure alcohol, such as E85. The purpose of this adjustment is to make official 

emission results independent of differences in test fuels within a fuel type. Use good 

engineering judgment to develop and apply testing protocols to minimize the impact of 

variations in test fuels. 

(1) For liquid fuels, determine the net energy content (Btu per pound of fuel) 

according to ASTM D4809 or ASTM D240 (both incorporated by reference in 

§ 1036.810) and carbon weight fraction (dimensionless) of your test fuel according to 

ASTM D5291 (incorporated by reference in § 1036.810). (Note that we recommend 

using ASTM D4809.) For gaseous fuels, use good engineering judgment to determine

the fuel’s net energy content and carbon weight fraction. (Note: Net energy content is 
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also sometimes known as lower heating value.) Calculate the test fuel’s carbonspecific net energy content (Btu/lbC) by dividing the net energy content by the carbon 

fraction, expressed to at least five significant figures. You may perform these 

calculations using SI units with the following conversion factors: one Btu equals 

1055.06 Joules and one Btu/lb equals 0.0023260 MJ/kg.

(2) If you control test fuel properties so that variations in the actual carbon-specific 

energy content are the same as or smaller than the repeatability of measuring carbonspecific energy content, you may use a constant value equal to the average carbonspecific energy content of your test fuel. Otherwise, use the measured value for the 

specific test fuel used for a given test. If you use a constant value, you must update or 

verify the value at least once per year, or after changes in test fuel suppliers or 

specifications.

(3) Calculate the adjustment factor for carbon-specific net energy content by dividing 

the carbon-specific net energy content of your test fuel by the reference level in the 

following table, expressed to at least five decimal places. Note that as used in this 

section, the unit lbC means pound of carbon and kgC means kilogram of carbon.

Fuel Type Reference carbon-specific net 

energy content (Btu/lbC)

Reference carbon-specific net 

energy content (MJ/kgC)

Diesel fuel 21,200 49.3112

Gasoline 21,700 50.4742

Natural Gas 28,500 66.2910

LPG 24,300 56.5218

(4) Your official emission result equals your calculated brake-specific emission rate 

multiplied by the adjustment factor specified in paragraph (b)(2) of this section. For 

example, if the net energy content and carbon fraction of your diesel test fuel are 

18,400 Btu/lb and 0.870, the carbon-specific net energy content of the test fuel would 

be 21,149 Btu/lbC. The adjustment factor in the example above would be 0.99759 

(21,149/21,200). If your brake-specific CO2 emission rate was 630.0 g/hp-hr, your 

official emission result would be 628.5 g/hp-hr. 

Subpart G—Special Compliance Provisions

§ 1036.601 What compliance provisions apply to these engines?

(a) Engine and equipment manufacturers, as well as owners, operators, and rebuilders of 

engines subject to the requirements of this part, and all other persons, must observe the 

provisions of this part, the provisions of the Clean Air Act, and the following provisions 

of 40 CFR part 1068:

(1) The exemption and importation provisions of 40 CFR part 1068, subparts C and 

D, apply for engines subject to this part 1036, except that the hardship exemption 

provisions of 40 CFR 1068.245, 1068.250, and 1068.255 do not apply for motor 
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vehicle engines.

(2) Manufacturers may comply with the defect reporting requirements of 40 CFR 

1068.501 instead of the defect reporting requirements of 40 CFR part 85.

(b) Engines exempted from the applicable standards of 40 CFR part 86 are exempt from 

the standards of this part without request.

§ 1036.610 Innovative technology credits and adjustments for reducing greenhouse 

gas emissions.

(a) You may ask us to apply the provisions of this section for CO2 emission reductions 

resulting from powertrain technologies that were not in common use with heavy-duty 

vehicles before model year 2010 that are not reflected in the specified test procedure. We 

will apply these provisions only for technologies that will result in a measurable, 

demonstrable, and verifiable real-world CO2 reduction. 

(b) The provisions of this section may be applied as either an improvement factor (used 

to adjust emission results) or as a separate credit, consistent with good engineering 

judgment. We recommend that you base your credit/adjustment on A to B testing of 

pairs of engines/vehicles differing only with respect to the technology in question. 

(1) Calculate improvement factors as the ratio of in-use emissions with the 

technology divided by the in-use emissions without the technology. Adjust the 

emission results by multiplying by the improvement factor. Use the improvementfactor approach where good engineering judgment indicates that the actual benefit 

will be proportional to emissions measured over the test procedures specified in this 

part. For example, the benefits from technologies that reduce engine operation would 

generally be proportional to the engine’s emission rate.

(2) Calculate separate credits based on the difference between the in-use emission rate 

(g/ton-mile) with the technology and the in-use emission rate without the technology. 

Multiply this difference by the number of engines, standard payload, and useful life. 

We may also allow you to calculate the credits based on g/hp-hr emission rates. Use 

the separate-credit approach where good engineering judgment indicates that the 

actual benefit will not be proportional to emissions measured over the test procedures 

specified in this part.

(3) We may require you to discount or otherwise adjust your improvement factor or 

credit to account for uncertainty or other relevant factors.

(c) Send your request to the Designated Compliance Officer. Include a detailed 

description of the technology and a recommended test plan. Also state whether you 

recommend applying these provisions using the improvement-factor method or the 

separate-credit method. We recommend that you do not begin collecting test data (for 
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submission to EPA) before contacting us. For technologies for which the vehicle 

manufacturer could also claim credits (such as transmissions in certain circumstances), 

we may require you to include a letter from the vehicle manufacturer stating that it will 

not seek credits for the same technology.

(d) We may seek public comment on your request, consistent with the provisions of 40 

CFR 86.1866-12(d)(3). However, we will generally not seek public comment on 

credits/adjustments based on A to B engine dynamometer testing, chassis testing, or inuse testing. 

§ 1036.615 Engines with Rankine cycle waste heat recovery and hybrid 

powertrains.

This section specifies how to generate advanced technology-specific emission credits for 

hybrid powertrains that include energy storage systems and regenerative braking 

(including regenerative engine braking) and for engines that include Rankine-cycle (or 

other bottoming cycle) exhaust energy recovery systems. 

(a) Hybrid powertrains. This paragraph (a) applies for pre-transmission and posttransmission hybrid powertrains.

(1) Pre-transmission hybrid powertrains are those engine systems that include 

features that recover and store energy during engine motoring operation but not from 

the vehicle wheels. These powertrains are tested using the hybrid engine test 

procedures of 40 CFR part 1065 or using the post-transmission test procedures in 40 

CFR 1037.550.

(2) Post-transmission hybrid powertrains are those powertrains that include features 

that recover and store energy from braking but that cannot function as hybrids 

without the transmission. These powertrains must have a single output shaft to the 

final drive and are tested by simulating the chassis test procedure applicable for 

hybrid vehicles under 40 CFR 1037.550. You need our approval before you begin 

testing.

(b) Rankine engines. Test engines that include Rankine-cycle exhaust energy recovery

systems according to the test procedures specified in subpart F of this part unless we 

approve alternate procedures.

(c) Calculating credits. Calculate credits as specified in subpart H of this part. Credits 

generated from engines and powertrains certified under this section may be used in other 

averaging sets as described in § 1036.740(d). Credits may not be generated under this 

section and 40 CFR 1037.615 for the same technology on the same vehicle.

(d) Innovative technologies. You may certify using both provisions of this section and 

the innovative technology provisions of §1036.610, provided you do not double count 

emission benefits.
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§ 1036.620 Alternate CO2 standards based on model year 2011 compressionignition engines.

For model years 2014 through 2016, you may certify your compression-ignition engines 

to the CO2 standards of this section instead of the CO2 standards in § 1036.108. 

However, you may not certify engines to these alternate standards if they are part of an 

averaging set in which you carry a balance of banked credits. You may submit 

applications for certifications before using up banked credits in the averaging set, but 

such certificates will not become effective until you have used up (or retired) your 

banked credits in the averaging set. For purposes of this section, you are deemed to carry

credits in an averaging set if you carry credits from advanced technology that are allowed 

to be used in that averaging set.

(a) The standards of this section are determined from the measured emission rate of the 

test engine of the applicable baseline 2011 engine family(ies) as described in paragraphs 

(b) and (c) of this section. Calculate the CO2 emission rate of the baseline test engine 

using the same equations used for showing compliance with the otherwise applicable 

standard. The alternate CO2 standard for light and medium heavy-duty vocationalcertified engines (certified for CO2 using the transient cycle) is equal to the baseline 

emission rate multiplied by 0.975. The alternate CO2 standard for tractor-certified 

engines (certified for CO2 using the SET cycle) and all other heavy heavy-duty engines is 

equal to the baseline emission rate multiplied by 0.970. The in-use FEL for these engines 

is equal to the alternate standard multiplied by 1.03. 

(b) This paragraph (b) applies if you do not certify all your engine families in the 

averaging set to the alternate standards of this section. Identify separate baseline engine 

families for each engine family that you are certifying to the alternate standards of this 

section. For an engine family to be considered the baseline engine family, it must meet 

the following criteria:

(1) It must have been certified to all applicable emission standards in model year 

2011. If the baseline engine was certified to a NOX FEL above the standard and 

incorporated the same emission control technologies as the new engine family, you 

may adjust the baseline CO2 emission rate to be equivalent to an engine meeting the 

0.20 g/hp-hr NOX standard (or your higher FEL as specified in this paragraph (b)(1)), 

using certification results from model years 2009 through 2011, consistent with good 

engineering judgment. 

(i) Use the following equation to relate model year 2009-2011 NOX and CO2

emission rates (g/hp-hr): CO2 = a×log(NOX)+b. 

(ii) For model year 2014-2016 engines certified to NOX FELs above 0.20 g/hp-hr, 

correct the baseline CO2 emissions to the actual NOX FELs of the 2014-2016 

engines. 

(iii) Calculate separate adjustments for transient and SET emissions.
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(2) The baseline configuration tested for certification must have the same engine 

displacement as the engines in the engine family being certified to the alternate 

standards, and its rated power must be within five percent of the highest rated power 

in the engine family being certified to the alternate standards.

(3) The model year 2011 U.S.-directed production volume of the configuration tested 

must be at least one percent of the total 2011 U.S.-directed production volume for the 

engine family.

(4) The tested configuration must have cycle-weighted BSFC equivalent to or better 

than all other configurations in the engine family.

(c) This paragraph (c) applies if you certify all your engine families in the primary

intended service class to the alternate standards of this section. For purposes of this 

section, you may combine light heavy-duty and medium heavy-duty engines into a single 

averaging set. Determine your baseline CO2 emission rate as the production-weighted 

emission rate of the certified engine families you produced in the 2011 model year. If 

you produce engines for both tractors and vocational vehicles, treat them as separate 

averaging sets. Adjust the CO2 emission rates to be equivalent to an engine meeting the 

average NOX FEL of new engines (assuming engines certified to the 0.20 g/hp-hr NOX

standard have a NOX FEL equal to 0.20 g/hp-hr), as described in paragraph (b)(1) of this 

section.

(d) Include the following statement on the emission control information label: “THIS 

ENGINE WAS CERTIFIED TO AN ALTERNATE CO2 STANDARD UNDER 

§ 1036.620.” 

(e) You may not bank CO2 emission credits for any engine family in the same averaging 

set and model year in which you certify engines to the standards of this section. You may

not bank any advanced technology credits in any averaging set for the model year you 

certify under this section (since such credits would be available for use in this averaging 

set). Note that the provisions of §1036.745 apply for deficits generated with respect to 

the standards of this section.

(f) You need our approval before you may certify engines under this section, especially 

with respect to the numerical value of the alternate standards. We will not approve your 

request if we determine that you manipulated your engine families or test engine 

configurations to certify to less stringent standards, or that you otherwise have not acted 

in good faith. You must keep and provide to us any information we need to determine 

that your engine families meet the requirements of this section. Keep these records for at 

least five years after you stop producing engines certified under this section.

1036.625 In-use compliance with family emission limits (FELs).
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You may ask us to apply a higher in-use FEL for certain in-use engines, subject to the 

provisions of this section. Note that §1036.225 contains provisions related to changing 

FELs during a model year.

(a) Purpose. This section is intended to address circumstances in which it is in the public 

interest to apply a higher in-use FEL based on forfeiting an appropriate number of 

emission credits. 

(b) FELs. When applying higher in-use FELs to your engines, we would intend to 

accurately reflect the actual in-use performance of your engines, consistent with the 

specified testing provisions of this part.

(c) Equivalent families. We may apply the higher FELs to other families in other model 

years if they used equivalent emission controls.

(d) Credit forfeiture. Where we specify higher in-use FELs under this section, you must 

forfeit CO2 emission credits based on the difference between the in-use FEL and the 

otherwise applicable FEL. Calculate the amount of credits to be forfeited using the 

applicable equation in §1036.705, by substituting the otherwise applicable FEL for the 

standard and the in-use FEL for the otherwise applicable FEL.

(e) Requests. Submit your request to the Designated Compliance Officer. Include the 

following in your request:

(1) The engine family name and model year of the engines affected.

(2) A list of other engine families/model years that may be affected.

(3) The otherwise applicable FEL for the engine families along with your 

recommendations for higher in-use FELs.

(4) Your source of credits for forfeiture. 

(f) Relation to recall. You may not request higher in-use FELs for any engine families 

for which we have made a determination of nonconformance and ordered a recall. You 

may, however, make such requests for engine families for which you are performing a 

voluntary emission recall.

(g) Approval. We may approve your request if we determine that you meet the 

requirements of this section and such approval is in the public interest. We may include 

appropriate conditions with our approval or we may approve your request with 

modifications.

Subpart H—Averaging, Banking, and Trading for Certification
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§ 1036.701 General provisions.

(a) You may average, bank, and trade (ABT) emission credits for purposes of 

certification as described in this subpart and in subpart B of this part to show compliance 

with the standards of § 1036.108. Participation in this program is voluntary. (Note: As 

described in subpart B of this part, you must assign an FCL to all engine families, 

whether or not they participate in the ABT provisions of this subpart.)

(b) [Reserved]

(c) The definitions of subpart I of this part apply to this subpart. The following 

definitions also apply: 

(1) Actual emission credits means emission credits you have generated that we have 

verified by reviewing your final report.

(2) Averaging set means a set of engines in which emission credits may be 

exchanged. Credits generated by one engine may only be used by other engines in 

the same averaging set. See § 1036.740.

(3) Broker means any entity that facilitates a trade of emission credits between a 

buyer and seller.

(4) Buyer means the entity that receives emission credits as a result of a trade.

(5) Reserved emission credits means emission credits you have generated that we 

have not yet verified by reviewing your final report.

(6) Seller means the entity that provides emission credits during a trade.

(7) Standard means the emission standard that applies under subpart B of this part for 

engines not participating in the ABT program of this subpart. 

(8) Trade means to exchange emission credits, either as a buyer or seller.

(d) Emission credits may be exchanged only within an averaging set as specified in 

§ 1036.740.

(e) You may not use emission credits generated under this subpart to offset any emissions 

that exceed an FCL or standard. This applies for all testing, including certification 

testing, in-use testing, selective enforcement audits, and other production-line testing. 

However, if emissions from an engine exceed an FCL or standard (for example, during a 

selective enforcement audit), you may use emission credits to recertify the engine family 

with a higher FCL that applies only to future production.

(f) Emission credits may be used in the model year they are generated. Surplus emission 

credits may be banked for future model years. Surplus emission credits may sometimes 

be used for past model years, as described in §1036.745. 
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(g) You may increase or decrease an FCL during the model year by amending your 

application for certification under § 1036.225. The new FCL may apply only to engines

you have not already introduced into commerce. 

(h) You may trade emission credits generated from any number of your engines to the 

engine purchasers or other parties to retire the credits. Identify any such credits in the 

reports described in § 1036.730. Engines must comply with the applicable FELs even if 

you donate or sell the corresponding emission credits under this paragraph (h). Those 

credits may no longer be used by anyone to demonstrate compliance with any EPA 

emission standards.

(i) See §1036.740 for special credit provisions that apply for credits generated under 

§1036.615 or 40 CFR 1037.104(d)(7) or 1037.615.

(j) Unless the regulations explicitly allow it, you may not calculate credits more than 

once for any emission reduction. For example, if you generate CO2 emission credits for a 

hybrid engine under this part for a given vehicle, no one may generate CO2 emission 

credits for that same hybrid engine and vehicle under 40 CFR part 1037. However, 

credits could be generated for identical vehicles using engines that did not generate 

credits under this part.

§ 1036.705 Generating and calculating emission credits.

(a) The provisions of this section apply separately for calculating emission credits for 

each pollutant.

(b) For each participating family, calculate positive or negative emission credits relative 

to the otherwise applicable emission standard based on the engine family’s FCL for 

greenhouse gases. If your engine family is certified to both the vocational and tractor

engine standards, calculate credits separately for the vocational engines and the tractor 

engines (as specified in paragraph (b)(3) of this section). Calculate positive emission 

credits for a family that has an FCL below the standard. Calculate negative emission 

credits for a family that has an FCL above the standard. 

Sum your positive and negative credits for the model year before rounding. Round the 

sum of emission credits to the nearest megagram (Mg), using consistent units throughout 

the following equations:

(1) For vocational engines:

Emission credits (Mg) = (Std – FCL) · (CF) · (Volume) · (UL) · (10-6)

Where: 

Std = the emission standard, in g/hp-hr, that applies under subpart B of this 

part for engines not participating in the ABT program of this subpart (the 

“otherwise applicable standard”).

FCL = the Family Certification Level for the engine family, in g/hp-hr, 
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measured over the transient duty cycle, rounded to the same number of 

decimal places as the emission standard. 

CF = a transient cycle conversion factor (hp-hr/mile), calculated by dividing 

the total (integrated) horsepower-hour over the duty cycle (average of 

vocational engine configurations weighted by their production volumes) by 

6.3 miles for spark-ignition engines and 6.5 miles for compression-ignition 

engines. This represents the average work performed by vocational engines in 

the family over the mileage represented by operation over the duty cycle. 

Volume = the number of vocational engines eligible to participate in the 

averaging, banking, and trading program within the given engine family

during the model year, as described in paragraph (c) of this section. 

UL = the useful life for the given engine family, in miles.

(2) For tractor engines:

Emission credits (Mg) = (Std – FCL) · (CF) · (Volume) · (UL) · (10-6)

Where: 

Std = the emission standard, in g/hp-hr, that applies under subpart B of this 

part for engines not participating in the ABT program of this subpart (the 

“otherwise applicable standard”).

FCL = the Family Certification Level for the engine family, in g/hp-hr, 

measured over the SET duty cycle rounded to the same number of decimal 

places as the emission standard. 

CF = a transient cycle conversion factor (hp-hr/mile), calculated by dividing 

the total (integrated) horsepower-hour over the duty cycle (average of tractorengine configurations weighted by their production volumes) by 6.3 miles for 

spark-ignition engines and 6.5 miles for compression-ignition engines. This 

represents the average work performed by tractor engines in the family over 

the mileage represented by operation over the duty cycle. Note that this 

calculation requires you to use the transient cycle conversion factor even for 

engines certified to SET-based standards. Volume = the number of tractor 

engines eligible to participate in the averaging, banking, and trading program 

within the given engine family during the model year, as described in 

paragraph (c) of this section.

UL = the useful life for the given engine family, in miles.

(3) For engine families certified to both the vocational and tractor engine standards, 

we may allow you to use statistical methods to estimate the total production volumes 

where a small fraction of the engines cannot be tracked precisely. 
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(4) You may not generate emission credits for tractor engines (i.e., engines not 

certified to the transient cycle for CO2) installed in vocational vehicles (including 

vocational tractors certified pursuant to 40 CFR 1037.630 or exempted pursuant to 40 

CFR 1037.631). We will waive this requirement where you demonstrate that less 

than five percent of the engines in your tractor family were installed in vocational 

vehicles. For example, if you know that 96 percent of your tractor engines were 

installed in non-vocational tractors, but cannot determine the vehicle type for the 

remaining four percent, you may generate credits for all the engines in the family. 

(c) As described in § 1036.730, compliance with the requirements of this subpart is 

determined at the end of the model year based on actual U.S.-directed production 

volumes. Keep appropriate records to document these production volumes. Do not 

include any of the following engines to calculate emission credits:

(1) Engines that you do not certify to the CO2 standards of this part because they are 

permanently exempted under subpart G of this part or under 40 CFR part 1068.

(2) Exported engines.

(3) Engines not subject to the requirements of this part, such as those excluded under 

§ 1036.5. For example, do not include engines used in vehicles certified to the 

greenhouse gas standards of 40 CFR 1037.104.

(4) [Reserved]

(5) Any other engines if we indicate elsewhere in this part 1036 that they are not to be 

included in the calculations of this subpart. 

(d) You may use CO2 emission credits to show compliance with CH4 and/or N2O FELs 

instead of the otherwise applicable emission standards. To do this, calculate the CH4

and/or N2O emission credits needed (negative credits) using the equation in paragraph (b) 

of this section, using the FEL(s) you specify for your engines during certification instead 

of the FCL. You must use 25 Mg of positive CO2 credits to offset 1 Mg of negative CH4

credits. You must use 298 Mg of positive CO2 credits to offset 1 Mg of negative N2O 

credits.

§ 1036.710 Averaging.

(a) Averaging is the exchange of emission credits among your engine families. You may

average emission credits only within the same averaging set.

(b) You may certify one or more engine families to an FCL above the applicable 

standard, subject to any applicable FEL caps and other the provisions in subpart B of this 

part, if you show in your application for certification that your projected balance of all 

emission-credit transactions in that model year is greater than or equal to zero, or that a 

negative balance is allowed under § 1036.745. 
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(c) If you certify an engine family to an FCL that exceeds the otherwise applicable 

standard, you must obtain enough emission credits to offset the engine family’s deficit by

the due date for the final report required in § 1036.730. The emission credits used to 

address the deficit may come from your other engine families that generate emission 

credits in the same model year (or from later model years as specified in § 1036.745), 

from emission credits you have banked, or from emission credits you obtain through 

trading.

§ 1036.715 Banking.

(a) Banking is the retention of surplus emission credits by the manufacturer generating 

the emission credits for use in future model years for averaging or trading. 

(b) You may designate any emission credits you plan to bank in the reports you submit 

under § 1036.730 as reserved credits. During the model year and before the due date for 

the final report, you may designate your reserved emission credits for averaging or 

trading.

(c) Reserved credits become actual emission credits when you submit your final report. 

However, we may revoke these emission credits if we are unable to verify them after 

reviewing your reports or auditing your records.

(d) Banked credits retain the designation of the averaging set in which they were 

generated.

§ 1036.720 Trading.

(a) Trading is the exchange of emission credits between manufacturers, or the transfer of 

credits to another party to retire them. You may use traded emission credits for 

averaging, banking, or further trading transactions. Traded emission credits remain 

subject to the averaging-set restrictions based on the averaging set in which they were 

generated.

(b) You may trade actual emission credits as described in this subpart. You may also 

trade reserved emission credits, but we may revoke these emission credits based on our 

review of your records or reports or those of the company with which you traded 

emission credits. You may trade banked credits within an averaging set to any certifying 

manufacturer.

(c) If a negative emission credit balance results from a transaction, both the buyer and 

seller are liable, except in cases we deem to involve fraud. See § 1036.255(e) for cases 

involving fraud. We may void the certificates of all engine families participating in a 

trade that results in a manufacturer having a negative balance of emission credits. See 

§ 1036.745.
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§ 1036.725 What must I include in my application for certification?

(a) You must declare in your application for certification your intent to use the provisions 

of this subpart for each engine family that will be certified using the ABT program. You 

must also declare the FELs/FCL you select for the engine family for each pollutant for 

which you are using the ABT program. Your FELs must comply with the specifications 

of subpart B of this part, including the FEL caps. FELs/FCL must be expressed to the 

same number of decimal places as the applicable standards.

(b) Include the following in your application for certification:

(1) A statement that, to the best of your belief, you will not have a negative balance of 

emission credits for any averaging set when all emission credits are calculated at the 

end of the year; or a statement that you will have a negative balance of emission 

credits for one or more averaging sets, but that it is allowed under § 1037.745.

(2) Detailed calculations of projected emission credits (positive or negative) based on 

projected U.S.-directed production volumes. We may require you to include similar 

calculations from your other engine families to project your net credit balances for the 

model year. If you project negative emission credits for a family, state the source of 

positive emission credits you expect to use to offset the negative emission credits. 

§ 1036.730 ABT reports.

(a) If any of your engine families are certified using the ABT provisions of this subpart, 

you must send an end-of-year report within 90 days after the end of the model year and a 

final report within 270 days after the end of the model year. 

(b) Your end-of-year and final reports must include the following information for each 

engine family participating in the ABT program:

(1) Engine-family designation and averaging set.

(2) The emission standards that would otherwise apply to the engine family.

(3) The FCL for each pollutant. If you change the FCL after the start of production, 

identify the date that you started using the new FCL and/or give the engine 

identification number for the first engine covered by the new FCL. In this case, 

identify each applicable FCL and calculate the positive or negative emission credits 

as specified in § 1036.225.

(4) The projected and actual U.S.-directed production volumes for the model year. If 

you changed an FCL during the model year, identify the actual production volume 

associated with each FCL.
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(5) The transient cycle conversion factor for each engine configuration as described in 

§ 1036.705.

(6) Useful life.

(7) Calculated positive or negative emission credits for the whole engine family. 

Identify any emission credits that you traded, as described in paragraph (d)(1) of this 

section.

(c) Your end-of-year and final reports must include the following additional information:

(1) Show that your net balance of emission credits from all your participating engine 

families in each averaging set in the applicable model year is not negative, except as 

allowed under § 1036.745.

(2) State whether you will reserve any emission credits for banking.

(3) State that the report’s contents are accurate.

(d) If you trade emission credits, you must send us a report within 90 days after the 

transaction, as follows:

(1) As the seller, you must include the following information in your report:

(i) The corporate names of the buyer and any brokers.

(ii) A copy of any contracts related to the trade.

(iii) The engine families that generated emission credits for the trade, 

including the number of emission credits from each family.

(2) As the buyer, you must include the following information in your report:

(i) The corporate names of the seller and any brokers.

(ii) A copy of any contracts related to the trade.

(iii) How you intend to use the emission credits, including the number of 

emission credits you intend to apply to each engine family (if known).

(e) Send your reports electronically to the Designated Compliance Officer using an 

approved information format. If you want to use a different format, send us a written 

request with justification for a waiver.

(f) Correct errors in your end-of-year report or final report as follows:

(1) You may correct any errors in your end-of-year report when you prepare the final 

report, as long as you send us the final report by the time it is due.
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(2) If you or we determine within 270 days after the end of the model year that errors 

mistakenly decreased your balance of emission credits, you may correct the errors 

and recalculate the balance of emission credits. You may not make these corrections 

for errors that are determined more than 270 days after the end of the model year. If 

you report a negative balance of emission credits, we may disallow corrections under 

this paragraph (f)(2).

(3) If you or we determine anytime that errors mistakenly increased your balance of 

emission credits, you must correct the errors and recalculate the balance of emission 

credits.

§ 1036.735 Recordkeeping.

(a) You must organize and maintain your records as described in this section. We may

review your records at any time.

(b) Keep the records required by this section for at least eight years after the due date for 

the end-of-year report. You may not use emission credits for any engines if you do not 

keep all the records required under this section. You must therefore keep these records to 

continue to bank valid credits. Store these records in any format and on any media, as 

long as you can promptly send us organized, written records in English if we ask for 

them. You must keep these records readily available. We may review them at any time.

(c) Keep a copy of the reports we require in §§ 1036.725 and 1036.730.

(d) Keep records of the engine identification number (usually the serial number) for each 

engine you produce that generates or uses emission credits under the ABT program. You 

may identify these numbers as a range. If you change the FEL after the start of 

production, identify the date you started using each FCL and the range of engine 

identification numbers associated with each FCL. You must also identify the purchaser 

and destination for each engine you produce to the extent this information is available.

(e) We may require you to keep additional records or to send us relevant information not 

required by this section in accordance with the Clean Air Act.

§ 1036.740 Restrictions for using emission credits.

The following restrictions apply for using emission credits:

(a) Averaging sets. Except as specified in paragraph (c) of this section, emission credits 

may be exchanged only within an following averaging sets There are four principal 

averaging sets for engines subject to this subpart:

(1) Spark-ignition engines.
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(2) Compression-ignition light heavy-duty engines.

(3) Compression-ignition medium heavy-duty engines.

(4) Compression-ignition heavy heavy-duty engines.

(b) Applying credits to prior year deficits. Where your credit balance for the previous 

year is negative, you may apply credits to that credit deficit only after meeting your credit 

obligations for the current year. 

(c) Credits from hybrid engines and other advanced technologies. The averaging set 

restrictions of paragraph (a) of this section do not apply for credits generated under 

§1036.615 or 40 CFR 1037.104(d)(7) or 1037.615 from hybrid power systems with 

regenerative braking, or from other advanced technologies. Such credits may also be 

used under 40 CFR part 1037. 

(1)The maximum amount of credits you may bring into the following service class 

groups is 60,000 Mg per model year: 

(i) Spark-ignition engines, light heavy-duty compression-ignition engines, and 

light heavy-duty vehicles. This group comprises the averaging sets listed in 

paragraphs(a)(1) and (2) of this section and the averaging set listed in 40 CFR 

1037.740(a)(1). 

(ii) Medium heavy-duty compression-ignition engines and medium heavy-duty

vehicles. This group comprises the averaging sets listed in paragraph (a)(3) of 

this section and 40 CFR 1037.740(a)(2).

(iii) Heavy heavy-duty compression-ignition engines and heavy heavy-duty

vehicles. This group comprises the averaging sets listed in paragraph (a)(4) of 

this section and 40 CFR 1037.740(a)(3).

(2) The limit specified in paragraph (c)(1) of this section does not limit the amount of 

advanced technology credits that can be used within a service class group if they were 

generated in that same service class group.(d) Credit life. Credits expire after five 

years.

(e) Other restrictions. Other sections of this part specify additional restrictions for using 

emission credits under certain special provisions.

§ 1036.745 End-of-year CO2 credit deficits.

Except as allowed by this section, we may void the certificate of any engine family

certified to an FCL above the applicable standard for which you do not have sufficient 

credits by the deadline for submitting the final report. 
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(a) Your certificate for an engine family for which you do not have sufficient CO2 credits 

will not be void if you remedy the deficit with surplus credits within three model years. 

For example, if you have a credit deficit of 500 Mg for an engine family at the end of 

model year 2015, you must generate (or otherwise obtain) a surplus of at least 500 Mg in 

that same averaging set by the end of model year 2018.

(b) You may not bank or trade away CO2 credits in the averaging set in any model year in 

which you have a deficit.

(c) You may apply only surplus credits to your deficit. You may not apply credits to a 

deficit from an earlier model year if they were generated in a model year for which any of 

your engine families for that averaging set had an end-of-year credit deficit.

(d) If you do not remedy the deficit with surplus credits within three model years, we 

may void your certificate for that engine family. We may void the certificate based on 

your end-of-year report. Note that voiding a certificate applies ab initio. Where the net 

deficit is less than the total amount of negative credits originally generated by the family, 

we will void the certificate only with respect to the number of engines needed to reach 

the amount of the net deficit. For example, if the original engine family generated 500 

Mg of negative credits, and the manufacturer’s net deficit after three years was 250 Mg, 

we would void the certificate with respect to half of the engines in the family. 

§ 1036.750 What can happen if I do not comply with the provisions of this subpart?

(a) For each engine family participating in the ABT program, the certificate of 

conformity is conditioned upon full compliance with the provisions of this subpart during 

and after the model year. You are responsible to establish to our satisfaction that you 

fully comply with applicable requirements. We may void the certificate of conformity 

for an engine family if you fail to comply with any provisions of this subpart.

(b) You may certify your engine family to an FCL above an applicable standard based on 

a projection that you will have enough emission credits to offset the deficit for the engine 

family. See §1036.745 for provisions specifying what happens if you cannot show in 

your final report that you have enough actual emission credits to offset a deficit for any

pollutant in an engine family.

(c) We may void the certificate of conformity for an engine family if you fail to keep 

records, send reports, or give us information we request. Note that failing to keep 

records, send reports, or give us information we request is also a violation of 42 U.S.C. 

7522(a)(2).

(d) You may ask for a hearing if we void your certificate under this section (see 

§ 1036.820).
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§ 1036.755 Information provided to the Department of Transportation.

After receipt of each manufacturer’s final report as specified in § 1036.730 and 

completion of any verification testing required to validate the manufacturer’s submitted 

final data, we will issue a report to the Department of Transportation with CO2 emission 

information and will verify the accuracy of each manufacturer’s equivalent fuel 

consumption data that required by NHTSA under 49 CFR 535.8. We will send a report 

to DOT for each engine manufacturer based on each regulatory category and 

subcategory, including sufficient information for NHTSA to determine fuel consumption 

and associated credit values. See 49 CFR 535.8 to determine if NHTSA deems 

submission of this information to EPA to also be a submission to NHTSA.

Subpart I—Definitions and Other Reference Information

§ 1036.801 Definitions.

The following definitions apply to this part. The definitions apply to all subparts 

unless we note otherwise. All undefined terms have the meaning the Act gives to them. 

The definitions follow:

Act means the Clean Air Act, as amended, 42 U.S.C. 7401 - 7671q.

Adjustable parameter has the meaning given in 40 CFR part 86.

Advanced technology means technology certified under §1036.615, 40 CFR 

1037.104(d)(7) or 1037.615.

Aftertreatment means relating to a catalytic converter, particulate filter, or any other 

system, component, or technology mounted downstream of the exhaust valve (or exhaust 

port) whose design function is to decrease emissions in the engine exhaust before it is 

exhausted to the environment. Exhaust-gas recirculation (EGR) and turbochargers are 

not aftertreatment.

Aircraft means any vehicle capable of sustained air travel above treetop heights.

Alcohol-fueled engine mean an engine that is designed to run using an alcohol fuel. 

For purposes of this definition, alcohol fuels do not include fuels with a nominal alcohol 

content below 25 percent by volume. 

Auxiliary emission control device means any element of design that senses 

temperature, motive speed, engine RPM, transmission gear, or any other parameter for 

the purpose of activating, modulating, delaying, or deactivating the operation of any part 

of the emission control system.
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Averaging set has the meaning given in § 1036.740.

Calibration means the set of specifications and tolerances specific to a particular 

design, version, or application of a component or assembly capable of functionally

describing its operation over its working range.

Carryover means relating to certification based on emission data generated from an 

earlier model year as described in § 1036.235(d).

Certification means relating to the process of obtaining a certificate of conformity for 

an engine family that complies with the emission standards and requirements in this part. 

Certified emission level means the highest deteriorated emission level in an engine 

family for a given pollutant from the applicable transient and/or steady-state testing, 

rounded to the same number of decimal places as the applicable standard. Note that you 

may have two certified emission levels for CO2 if you certify a family for both vocational 

and tractor use.

Complete vehicle means a vehicle meeting the definition of complete vehicle in 40 

CFR 1037.801 when it is first sold as a vehicle. For example, where a vehicle 

manufacturer sells an incomplete vehicle to a secondary manufacturer, the vehicle is not a 

complete vehicle under this part, even after its final assembly. 

Compression-ignition means relating to a type of reciprocating, internal-combustion 

engine that is not a spark-ignition engine.

Crankcase emissions means airborne substances emitted to the atmosphere from any 

part of the engine crankcase’s ventilation or lubrication systems. The crankcase is the 

housing for the crankshaft and other related internal parts.

Criteria pollutants means emissions of NOX, HC, PM, and CO. Note that these 

pollutants are also sometimes described collectively as “non-greenhouse gas pollutants”, 

although they do not necessarily have negligible global warming potentials.

Designated Compliance Officer means the Manager, Heavy-Duty and Nonroad 

Engine Group (6405-J), U.S. Environmental Protection Agency, 1200 Pennsylvania Ave., 

NW., Washington, DC 20460.

Designated Enforcement Officer means the Director, Air Enforcement Division 

(2242A), U.S. Environmental Protection Agency, 1200 Pennsylvania Ave., NW., 

Washington, DC 20460.

Deteriorated emission level means the emission level that results from applying the 

appropriate deterioration factor to the official emission result of the emission-data engine. 

Note that where no deterioration factor applies, references in this part to the deteriorated 

emission level mean the official emission result.

Deterioration factor means the relationship between emissions at the end of useful life 
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(or point of highest emissions if it occurs before the end of useful life) and emissions at 

the low-hour/low-mileage test point, expressed in one of the following ways:

(1) For multiplicative deterioration factors, the ratio of emissions at the end of useful life 

(or point of highest emissions) to emissions at the low-hour test point.

(2) For additive deterioration factors, the difference between emissions at the end of 

useful life (or point of highest emissions) and emissions at the low-hour test point.

Dual-fuel means relating to an engine designed for operation on two different types of 

fuel but not on a continuous mixture of those fuels.

Emission control system means any device, system, or element of design that controls 

or reduces the emissions of regulated pollutants from an engine.

Emission-data engine means an engine that is tested for certification. This includes 

engines tested to establish deterioration factors.

Emission-related maintenance means maintenance that substantially affects emissions 

or is likely to substantially affect emission deterioration.

Engine configuration means a unique combination of engine hardware and calibration 

(related to the emission standards) within an engine family. Engines within a single 

engine configuration differ only with respect to normal production variability or factors 

unrelated to compliance with emission standards.

Engine family has the meaning given in § 1036.230.

Excluded means relating to engines that are not subject to some or all of the 

requirements of this part as follows:

(1) An engine that has been determined not to be a heavy-duty engine is excluded from 

this part.

(2) Certain heavy-duty engines are excluded from the requirements of this part under 

§ 1036.5.

(3) Specific regulatory provisions of this part may exclude a heavy-duty engine generally

subject to this part from one or more specific standards or requirements of this part.

Exempted has the meaning given in 40 CFR 1068.30.

Exhaust-gas recirculation means a technology that reduces emissions by routing 

exhaust gases that had been exhausted from the combustion chamber(s) back into the 

engine to be mixed with incoming air before or during combustion. The use of valve 

timing to increase the amount of residual exhaust gas in the combustion chamber(s) that 

is mixed with incoming air before or during combustion is not considered exhaust-gas 

recirculation for the purposes of this part.
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Family certification level (FCL) means a CO2 emission level declared by the 

manufacturer that is at or above emission test results for all emission-data engines. The 

FCL serves as the emission standard for the engine family with respect to certification 

testing if it is different than the otherwise applicable standard. The FCL must be 

expressed to the same number of decimal places as the emission standard it replaces. 

Family emission limit (FEL) means an emission level declared by the manufacturer to 

serve in place of an otherwise applicable emission standard (other than CO2 standards) 

under the ABT program in subpart H of this part. The FEL must be expressed to the 

same number of decimal places as the emission standard it replaces. The FEL serves as 

the emission standard for the engine family with respect to all required testing except 

certification testing for CO2. The CO2 FEL is equal to the CO2 FCL multiplied by 1.03 

and rounded to the same number of decimal places as the standard (e.g., the nearest 

whole g/hp-hr for the 2016 CO2 standards). 

Flexible-fuel means relating to an engine designed for operation on any mixture of 

two or more different types of fuels.

Fuel type means a general category of fuels such as diesel fuel, gasoline, or natural 

gas. There can be multiple grades within a single fuel type, such as premium gasoline, 

regular gasoline, or gasoline with 10 percent ethanol.

Good engineering judgment has the meaning given in 40 CFR 1068.30. See 40 CFR 

1068.5 for the administrative process we use to evaluate good engineering judgment.

Greenhouse gas pollutants and greenhouse gases means compounds regulated under 

this part based primarily on their impact on the climate. This includes CO2, CH4, and 

N2O. 

Gross vehicle weight rating (GVWR) means the value specified by the vehicle 

manufacturer as the maximum design loaded weight of a single vehicle, consistent with 

good engineering judgment.

Heavy-duty engine means any engine which the engine manufacturer could 

reasonably expect to be used for motive power in a heavy-duty vehicle. For purposes of 

this definition in this part, the term “engine” includes internal combustion engines and 

other devices that convert chemical fuel into motive power. For example, a fuel cell used 

in a heavy-duty vehicle is a heavy-duty engine.

Heavy-duty vehicle means any motor vehicle above 8,500 pounds GVWR or that has 

a vehicle curb weight above 6,000 pounds or that has a basic vehicle frontal area greater 

than 45 square feet. Curb weight has the meaning given in 40 CFR 86.1803, consistent 

with the provisions of 40 CFR 1037.140. Basic vehicle frontal area has the meaning 

given in 40 CFR 86.1803.

Hybrid engine or hybrid powertrain means an engine or powertrain that includes 

energy storage features other than a conventional battery system or conventional 

flywheel. Supplemental electrical batteries and hydraulic accumulators are examples of 
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hybrid energy storage systems. Note that certain provisions in this part treat hybrid 

engines and powertrains intended for vehicles that include regenerative braking different 

than those intended for vehicles that do not include regenerative braking. 

Hydrocarbon (HC) means the hydrocarbon group on which the emission standards are 

based for each fuel type. For alcohol-fueled engines, HC means nonmethane 

hydrocarbon equivalent (NMHCE). For all other engines, HC means nonmethane 

hydrocarbon (NMHC).

Identification number means a unique specification (for example, a model 

number/serial number combination) that allows someone to distinguish a particular 

engine from other similar engines.

Incomplete vehicle means a vehicle meeting the definition of incomplete vehicle in 

40 CFR 1037.801 when it is first sold as a vehicle. 

Innovative technology means technology certified under §1036.610.

Liquefied petroleum gas (LPG) means a liquid hydrocarbon fuel that is stored under 

pressure and is composed primarily of nonmethane compounds that are gases at 

atmospheric conditions.

Low-hour means relating to an engine that has stabilized emissions and represents the 

undeteriorated emission level. This would generally involve less than 125 hours of 

operation.

Manufacture means the physical and engineering process of designing, constructing, 

and/or assembling a heavy-duty engine or a heavy-duty vehicle. 

Manufacturer has the meaning given in section 216(1) of the Act. In general, this 

term includes any person who manufactures an engine, vehicle, or piece of equipment for 

sale in the United States or otherwise introduces a new engine into commerce in the 

United States. This includes importers who import engines or vehicles for resale. 

Medium-duty passenger vehicle has the meaning given in 40 CFR 86.1803.

Model year means the manufacturer’s annual new model production period, except as 

restricted under this definition. It must include January 1 of the calendar year for which 

the model year is named, may not begin before January 2 of the previous calendar year, 

and it must end by December 31 of the named calendar year. Manufacturers may not 

adjust model years to circumvent or delay compliance with emission standards or to 

avoid the obligation to certify annually. 

Motor vehicle has the meaning given in 40 CFR 85.1703. 

Natural gas means a fuel whose primary constituent is methane.

New motor vehicle engine means a motor vehicle engine meeting the criteria of either 
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paragraph (1) or (2) of this definition. 

(1) A motor vehicle engine for which the ultimate purchaser has never received the 

equitable or legal title is a new motor vehicle engine. This kind of engine might 

commonly be thought of as "brand new" although a new motor vehicle engine may

include previously used parts. Under this definition, the engine is new from the time 

it is produced until the ultimate purchaser receives the title or places it into service, 

whichever comes first.

(2) An imported motor vehicle engine is a new motor vehicle engine if it was 

originally built on or after January 1, 1970.

Noncompliant engine means an engine that was originally covered by a certificate of 

conformity, but is not in the certified configuration or otherwise does not comply with the 

conditions of the certificate.

Nonconforming engine means an engine not covered by a certificate of conformity

that would otherwise be subject to emission standards.

Nonmethane hydrocarbons (NMHC) means the sum of all hydrocarbon species 

except methane, as measured according to 40 CFR part 1065. 

Official emission result means the measured emission rate for an emission-data 

engine on a given duty cycle before the application of any deterioration factor, but after 

the applicability of any required regeneration adjustment factors.

Owners manual means a document or collection of documents prepared by the engine 

or vehicle manufacturer for the owner or operator to describe appropriate engine 

maintenance, applicable warranties, and any other information related to operating or 

keeping the engine. The owners manual is typically provided to the ultimate purchaser at 

the time of sale.

Oxides of nitrogen has the meaning given in 40 CFR 1065.1001.

Percent has the meaning given in 40 CFR 1065.1001. Note that this means 

percentages identified in this part are assumed to be infinitely precise without regard to 

the number of significant figures. For example, one percent of 1,493 is 14.93.

Petroleum means gasoline or diesel fuel or other fuels normally derived from crude 

oil. This does not include methane or LPG. 

Placed into service means put into initial use for its intended purpose.

Primary intended service class has the meaning given in § 1036.140.

Rated power has the meaning given in 40 CFR part 86.

Rechargeable Energy Storage System (RESS) means the component(s) of a hybrid 
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engine or vehicle that store recovered energy for later use, such as the battery system in 

an electric hybrid vehicle.

Revoke has the meaning given in 40 CFR 1068.30.

Round has the meaning given in 40 CFR 1065.1001.

Scheduled maintenance means adjusting, repairing, removing, disassembling, 

cleaning, or replacing components or systems periodically to keep a part or system from 

failing, malfunctioning, or wearing prematurely. It also may mean actions you expect are 

necessary to correct an overt indication of failure or malfunction for which periodic 

maintenance is not appropriate.

Small manufacturer means a manufacturer meeting the criteria specified in 13 CFR 

121.201. For manufacturers owned by a parent company, the employee and revenue 

limits apply to the total number of employees and total revenue of the parent company

and all its subsidiaries.

Spark-ignition means relating to a gasoline-fueled engine or any other type of engine 

with a spark plug (or other sparking device) and with operating characteristics 

significantly similar to the theoretical Otto combustion cycle. Spark-ignition engines 

usually use a throttle to regulate intake air flow to control power during normal operation. 

Steady-state has the meaning given in 40 CFR 1065.1001.

Suspend has the meaning given in 40 CFR 1068.30.

Test engine means an engine in a test sample.

Test sample means the collection of engines selected from the population of an 

engine family for emission testing. This may include testing for certification, productionline testing, or in-use testing.

Tractor means a vehicle meeting the definition of “tractor” in 40 CFR 1037.801, but 

not classified as a “vocational tractor” under 40 CFR 1037.630, or relating to such a 

vehicle.

Tractor engine means an engine certified for use in tractors. Where an engine family

is certified for use in both tractors and vocational vehicles, “tractor engine” means an 

engine that the engine manufacturer reasonably believes will be (or has been) installed in 

a tractor. Note that the provisions of this part may require a manufacturer to document 

how it determines that an engine is a tractor engine.

Ultimate purchaser means, with respect to any new engine or vehicle, the first person 

who in good faith purchases such new engine or vehicle for purposes other than resale.

United States has the meaning given in 40 CFR 1068.30.
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Upcoming model year means for an engine family the model year after the one 

currently in production.

U.S.-directed production volume means the number of engines, subject to the 

requirements of this part, produced by a manufacturer for which the manufacturer has a 

reasonable assurance that sale was or will be made to ultimate purchasers in the United 

States. This does not include engines certified to state emission standards that are 

different than the emission standards in this part.

Vehicle has the meaning given in 40 CFR 1037.801.

Vocational engine means an engine certified for use in vocational vehicles. Where an 

engine family is certified for use in both tractors and vocational vehicles, “vocational 

engine” means an engine that the engine manufacturer reasonably believes will be (or has 

been) installed in a vocational vehicle. Note that the provisions of this part may require a 

manufacturer to document how it determines that an engine is a vocational engine.

Vocational vehicle means a vehicle meeting the definition of “vocational” vehicle in 

40 CFR 1037.801.

Void has the meaning given in 40 CFR 1068.30.

We (us, our) means the Administrator of the Environmental Protection Agency and 

any authorized representatives.

§ 1036.805 Symbols, acronyms, and abbreviations.

The following symbols, acronyms, and abbreviations apply to this part:

ABT averaging, banking, and trading.

AECD auxiliary emission control device.

ASTM American Society for Testing and Materials.

BTU British thermal units.

CFR Code of Federal Regulations.

CH4 methane.

CO carbon monoxide.

CO2 carbon dioxide.

DF deterioration factor.

DOT Department of Transportation.

E85 gasoline blend including nominally 85 percent ethanol.

EPA Environmental Protection Agency.

FCL Family Certification Level.

FEL Family Emission Limit.

g/hp-hr grams per brake horsepower-hour.

GVWR gross vehicle weight rating.

HC hydrocarbon.

kg kilogram.

kgC kilogram carbon.

kW kilowatts.
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lb pound.

lbC pound carbon.

LPG liquefied petroleum gas.

Mg megagrams (106grams, or one metric ton).

MJ megajoules.

N2O nitrous oxide.

NARA National Archives and Records Administration.

NHTSA National Highway Traffic Safety Administration.

NOx oxides of nitrogen (NO and NO2).

NTE not-to-exceed.

PM particulate matter.

RESS rechargeable energy storage system.

RPM revolutions per minute.

SET Supplemental Emission Test (see 40 CFR 86.1362). 

U.S. United States.

U.S.C. United States Code.

§ 1036.810 Incorporation by reference.

(a) Certain material is incorporated by reference into this part with the approval of the 

Director of the Federal Register under 5 U.S.C. 552(a) and 1 CFR part 51. To enforce any 

edition other than that specified in this section, the Environmental Protection Agency

must publish a notice of the change in the Federal Register and the material must be 

available to the public. All approved material is available for inspection at U.S. EPA, Air 

and Radiation Docket and Information Center, 1301 Constitution Ave., NW., Room 

B102, EPA West Building, Washington, DC 20460, (202) 202-1744, and is available 

from the sources listed below. It is also available for inspection at the National Archives 

and Records Administration (NARA). For information on the availability of this material 

at NARA, call 202–741–6030, or go to 

http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.

(b) American Society for Testing and Materials, 100 Barr Harbor Drive, P.O. Box C700, 

West Conshohocken, PA, 19428-2959, (610) 832-9585, http://www.astm.org/.

(1) ASTM D 240–09 Standard Test Method for Heat of Combustion of Liquid 

Hydrocarbon Fuels by Bomb Calorimeter, approved July 1, 2009, IBR approved for § 

1036.530(b).

(2) ASTM D4809-09a Standard Test Method for Heat of Combustion of Liquid 

Hydrocarbon Fuels by Bomb Calorimeter (Precision Method), approved September 1, 

2009, IBR approved for § 1036.530(b).

(3) ASTM D5291-10 Standard Test Methods for Instrumental Determination of 

Carbon, Hydrogen, and Nitrogen in Petroleum Products and Lubricants, approved 

May 1, 2010, IBR approved for § 1036.530(b).

§ 1036.815 What provisions apply to confidential information?

The provisions of 40 CFR 1068.10 apply for information you consider confidential.

§ 1036.820 Requesting a hearing.
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(a) You may request a hearing under certain circumstances, as described elsewhere in this 

part. To do this, you must file a written request, including a description of your objection 

and any supporting data, within 30 days after we make a decision.

(b) For a hearing you request under the provisions of this part, we will approve your 

request if we find that your request raises a substantial factual issue.

(c) If we agree to hold a hearing, we will use the procedures specified in 40 CFR part 

1068, subpart G.

§ 1036.825 Reporting and recordkeeping requirements.

(a) This part includes various requirements to submit and record data or other 

information. Unless we specify otherwise, store required records in any format and on 

any media and keep them readily available for eight years after you send an associated 

application for certification, or eight years after you generate the data if they do not 

support an application for certification. You may not rely on anyone else to meet 

recordkeeping requirements on your behalf unless we specifically authorize it. We may 

review these records at any time. You must promptly send us organized, written records 

in English if we ask for them. We may require you to submit written records in an 

electronic format. 

(b) The regulations in § 1036.255, 40 CFR 1068.25, and 40 CFR 1068.101 describe your 

obligation to report truthful and complete information. This includes information not 

related to certification. Failing to properly report information and keep the records we 

specify violates 40 CFR 1068.101(a)(2), which may involve civil or criminal penalties. 

(c) Send all reports and requests for approval to the Designated Compliance Officer (see 

§ 1036.801).

(d) Any written information we require you to send to or receive from another company 

is deemed to be a required record under this section. Such records are also deemed to be 

submissions to EPA. Keep these records for eight years unless the regulations specify a 

different period. We may require you to send us these records whether or not you are a 

certificate holder.

(e) Under the Paperwork Reduction Act (44 U.S.C. 3501 et seq.), the Office of 

Management and Budget approves the reporting and recordkeeping specified in the 

applicable regulations. The following items illustrate the kind of reporting and 

recordkeeping we require for engines and equipment regulated under this part: 

(1) We specify the following requirements related to engine certification in this part 

1036:

(i) In § 1036.135 we require engine manufacturers to keep certain records related 

to duplicate labels sent to equipment manufacturers.
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(ii) In subpart C of this part we identify a wide range of information required to 

certify engines.

(iii) In subpart G of this part we identify several reporting and recordkeeping 

items for making demonstrations and getting approval related to various special 

compliance provisions. 

(iv) In § 1036.725, 1036.730, and 1036.735 we specify certain records related to 

averaging, banking, and trading.

(2) We specify the following requirements related to testing in 40 CFR part 1066:

(i) In 40 CFR 1066.2 we give an overview of principles for reporting information.

(ii) [Reserved]

34. A new part 1037 is added to subchapter U to read as follows: 

PART 1037—CONTROL OF EMISSIONS FROM NEW HEAVY-DUTY MOTOR 

VEHICLES 

Subpart A—Overview and Applicability

Sec.

1037.1 Applicability

1037.5 Excluded vehicles.

1037.10 How is this part organized?

1037.15 Do any other regulation parts apply to me?

1037.30 Submission of information.

Subpart B—Emission Standards and Related Requirements 

1037.101 Overview of emission standards for heavy-duty vehicles.

1037.102 Exhaust emission standards for NOX, HC, PM, and CO.

1037.104 Exhaust emission standards for CO2, CH4, and N2O for heavy-duty vehicles at 

or below 14,000 pounds GVWR.

1037.105 Exhaust emission standards for CO2 for vocational vehicles.

1037.106 Exhaust emission standards for CO2 for tractors above 26,000 pounds GVWR.

1037.115 Other requirements. 

1037.120 Emission-related warranty requirements.

1037.125 Maintenance instructions and allowable maintenance.

1037.135 Labeling.
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1037.140 Curb weight and roof height.

1037.150 Interim provisions.

Subpart C—Certifying Vehicle families

1037.201 General requirements for obtaining a certificate of conformity.

1037.205 What must I include in my application?

1037.210 Preliminary approval before certification.

1037.220 Amending maintenance instructions.

1037.225 Amending applications for certification.

1037.230 Vehicle families, sub-families, and configurations.

1037.241 Demonstrating compliance with exhaust emission standards for greenhouse 

gas pollutants.

1037.250 Reporting and recordkeeping.

1037.255 What decisions may EPA make regarding my certificate of conformity?

Subpart D—[Reserved]

Subpart E—In-use Testing

1037.401 General provisions.

Subpart F—Test and Modeling Procedures

1037.501 General testing and modeling provisions.

1037.510 Duty-cycle testing.

1037.520 Modeling CO2 emissions to show compliance.

1037.521 Aerodynamic measurements.

1037.525 Special procedures for testing hybrid vehicles with power take-off. 

1037.550 Special procedures for testing post-transmission hybrid systems. 

Subpart G—Special Compliance Provisions

1037.601 What compliance provisions apply to these vehicles?

1037.610 Vehicles with innovative technologies.

1037.615 Hybrid vehicles and other advanced technologies.

1037.620 Shipment of incomplete vehicles to secondary vehicle manufacturers.

1037.630 Special purpose tractors.
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1037.631 Exemption for vocational vehicles intended for offroad use.

1037.640 Variable vehicle speed limiters. 

1037.645 In-use compliance with family emission limits (FELs).

1037.650 Tire manufacturers.

1037.655 Post-useful life vehicle modifications.

1037.660 Automatic engine shutdown systems.

Subpart H—Averaging, Banking, and Trading for Certification

1037.701 General provisions.

1037.705 Generating and calculating emission credits.

1037.710 Averaging.

1037.715 Banking.

1037.720 Trading.

1037.725 What must I include in my application for certification?

1037.730 ABT reports.

1037.735 Recordkeeping.

1037.740 Restrictions for using emission credits.

1037.745 End-of-year CO2 credit deficits.

1037.750 What can happen if I do not comply with the provisions of this subpart?

1037.755 Information provided to the Department of Transportation.

Subpart I—Definitions and Other Reference Information

1037.801 Definitions. 
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1037.805 Symbols, acronyms, and abbreviations. 

1037.810 Incorporation by reference.

1037.815 What provisions apply to confidential information?

1037.820 Requesting a hearing.

1037.825 Reporting and recordkeeping requirements. 

Appendix I to part 1037 — Heavy-duty Transient Chassis Test Cycle

Appendix II to part 1037 — Power Take-Off Test Cycle

Appendix III to part 1037 —Emission Control Identifiers

Authority: 42 U.S.C. 7401 - 7671q.

Subpart A—Overview and Applicability

§ 1037.1 Applicability

This part contains standards and other regulations applicable to the emission of the air 

pollutant defined as the aggregate group of six greenhouse gases: carbon dioxide, nitrous 

oxide, methane, hydrofluorocarbons, perflurocarbons, and sulfur hexafluoride. The 

regulations in this part 1037 apply for all new heavy-duty vehicles, except as provided in 

§1037.5. This includes electric vehicles and vehicles fueled by conventional and 

alternative fuels.

§ 1037.5 Excluded vehicles.

Except for the definitions specified in §1037.801, this part does not apply to the 

following vehicles:

(a) Vehicles not meeting the definition of “motor vehicle”.

(b) Vehicles excluded from the definition of “heavy-duty vehicle” in §1037.801 because 

of vehicle weight, weight rating, and frontal area (such as light-duty vehicles and lightduty trucks).
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(c) Medium-duty passenger vehicles. 

(d) Vehicles produced in model years before 2014, unless they are certified under 

§ 1037.150. 

(e) Vehicles subject to the light-duty greenhouse gas standards of 40 CFR part 86. See 

40 CFR 86.1818 for greenhouse gas standards that apply for these vehicles. An example 

of such a vehicle would be a vehicle meeting the definition of “heavy-duty vehicle” in 

§1037.801 and 40 CFR 86.1803, but also meeting the definition of “light truck” in 40 

CFR 86.1818-12(b)(2).

§ 1037.10 How is this part organized?

This part 1037 is divided into subparts as described in this section. Note that only

subparts A, B, and I of this part apply for vehicles subject to the standards of § 1037.104, 

as described in that section.

(a) Subpart A of this part defines the applicability of part 1037 and gives an overview of 

regulatory requirements.

(b) Subpart B of this part describes the emission standards and other requirements that 

must be met to certify vehicles under this part. Note that § 1037.150 discusses certain 

interim requirements and compliance provisions that apply only for a limited time.

(c) Subpart C of this part describes how to apply for a certificate of conformity for 

vehicles subject to the standards of § 1037.105 or § 1037.106.

(d) [Reserved]

(e) Subpart E of this part addresses testing of in-use vehicles.

(f) Subpart F of this part describes how to test your vehicles and perform emission 

modeling (including references to other parts of the Code of Federal Regulations) for 

vehicles subject to the standards of § 1037.105 or § 1037.106. 

(g) Subpart G of this part and 40 CFR part 1068 describe requirements, prohibitions, and 

other provisions that apply to manufacturers, owners, operators, rebuilders, and all others. 

Section 1037.601 describes how 40 CFR part 1068 applies for heavy-duty vehicles.

(h) Subpart H of this part describes how you may generate and use emission credits to 

certify vehicles that are subject to the standards of § 1037.105 or § 1037.106.

(i) Subpart I of this part contains definitions and other reference information.

§ 1037.15 Do any other regulation parts apply to me?
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(a) Parts 1065 and 1066 of this chapter describe procedures and equipment specifications 

for testing engines and vehicles to measure exhaust emissions. Subpart F of this part 

1037 describes how to apply the provisions of part 1065 and part 1066 of this chapter to 

determine whether vehicles meet the exhaust emission standards in this part. 

(b) As described in § 1037.601, certain requirements and prohibitions of part 1068 of this 

chapter apply to everyone, including anyone who manufactures, imports, installs, owns, 

operates, or rebuilds any of the vehicles subject to this part 1037. Part 1068 of this 

chapter describes general provisions that apply broadly, but do not necessarily apply for 

all vehicles or all persons. The issues addressed by these provisions include these seven 

areas:

(1) Prohibited acts and penalties for manufacturers and others.

(2) Rebuilding and other aftermarket changes.

(3) Exclusions and exemptions for certain vehicles.

(4) Importing vehicles.

(5) Selective enforcement audits of your production.

(6) Recall.

(7) Procedures for hearings.

(c) Part 86 of this chapter applies for certain vehicles as specified in this part. For 

example, the test procedures and most of part 86, subpart S, applies for vehicles subject 

to § 1037.104. 

(d) Other parts of this chapter apply if referenced in this part.

§ 1037.30 Submission of information.

Send all reports and requests for approval to the Designated Compliance Officer (see 

§ 1037.801). See § 1037.825 for additional reporting and recordkeeping provisions.

Subpart B—Emission Standards and Related Requirements 

§ 1037.101 Overview of emission standards for heavy-duty vehicles.

(a) This part specifies emission standards for certain vehicles and for certain pollutants. 

It also summarizes other standards that apply under 40 CFR part 86. This part contains 
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standards and other regulations applicable to the emission of the air pollutant defined as 

the aggregate group of six greenhouse gases: carbon dioxide, nitrous oxide, methane, 

hydrofluorocarbons, perflurocarbons, and sulfur hexafluoride. 

(b) The regulated emissions are addressed in four groups:

(1) Exhaust emissions of NOX, HC, PM, and CO. These pollutants are sometimes 

described collectively as “criteria pollutants” because they are either criteria 

pollutants under the Clean Air Act or precursors to the criteria pollutant ozone. These 

pollutants are also sometimes described collectively as “non-greenhouse gas 

pollutants”, although they do not necessarily have negligible global warming 

potential. As described in § 1037.102, standards for these pollutants are provided in 

40 CFR part 86. 

(2) Exhaust emissions of CO2, CH4, and N2O. These pollutants are described 

collectively in this part as “greenhouse gas pollutants” because they are regulated 

primarily based on their impact on the climate. These standards are provided in 

§§ 1037.104 through 1037.106.

(3) Hydrofluorocarbons. These pollutants are also “greenhouse gas pollutants” but are 

treated separately from exhaust greenhouse gas pollutants listed in paragraph (b)(2) of 

this section. These standards are provided in § 1037.115.

(4) Fuel evaporative emissions. These requirements are described in 40 CFR part 86.

(c) The regulated heavy-duty vehicles are addressed in different groups as follows: 

(1) For criteria pollutants, vehicles are regulated based on gross vehicle weight rating 

(GVWR), whether they are considered “spark-ignition” or “compression-ignition,” 

and whether they are first sold as complete or incomplete vehicles. These groupings 

apply as described in 40 CFR part 86.

(2) For greenhouse gas pollutants, vehicles are regulated in the following groups:

(i) Complete and certain incomplete vehicles at or below 14,000 pounds GVWR 

(see § 1037.104 for further specification). Certain provisions of 40 CFR part 86 

apply for these vehicles; see § 1037.104(h) for a list of provisions in this part 

1037 that also apply for these vehicles. These provisions may also be optionally

applied to certain other vehicles, as described in §1037.104.

(ii) Tractors above 26,000 pounds GVWR.

(iii) All other vehicles subject to standards under this part. These other vehicles 

are referred to as “vocational” vehicles.

§ 1037.102 Exhaust emission standards for NOX, HC, PM, and CO.

See 40 CFR part 86 for the exhaust emission standards for NOX, HC, PM, and CO that 

apply for heavy-duty vehicles.

§ 1037.104 Exhaust emission standards for CO2, CH4, and N2O for heavy-duty 

vehicles at or below 14,000 pounds GVWR.

This section applies for heavy-duty vehicles at or below 14,000 pounds GVWR. See 
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paragraph (f) and §1037.150 of this section for provisions excluding certain vehicles 

from this section, and allowing other vehicles to be certified under this section. 

(a) Fleet-average CO2 emission standards. Fleet-average CO2 emission standards apply 

for each manufacturer as follows:

(1) Calculate a work factor, WF, for each vehicle subconfiguration (or group of 

subconfigurations allowed under paragraph (a)(4) of this section), rounded to the 

nearest pound, using the following equation:

WF = 0.75× (GVWR - Curb Weight + xwd) + 0.25 × (GCWR – GVWR)

Where:

xwd = 500 pounds if the vehicle has four-wheel drive or all-wheel drive; xwd = 0 

pounds for all other vehicles.

(2) Using the appropriate work factor, calculate a target value for each vehicle 

subconfiguration (or group of subconfigurations allowed under paragraph (a)(4) of 

this section) you produce using one of the following equations, rounding to the 

nearest 0.1 g/mile:

(i) For spark-ignition vehicles: CO2 Target (g/mile) = 0.0440 × WF + 339

(ii) For compression-ignition vehicles and vehicles that operate without engines 

(such as electric vehicles and fuel cell vehicles): CO2 Target (g/mile) = 0.0416 × 

WF + 320

(3) Calculate a production-weighted average of the target values and round it to the 

nearest 0.1 g/mile. This is your fleet-average standard. All vehicles subject to the 

standards of this section form a single averaging set. Use the following equation to 

calculate your fleet-average standard from the target value for each vehicle 

subconfiguration (Targeti) and U.S.-directed production volume of each vehicle 

subconfiguration for the given model year (Volumei):

 

 

Target Volume

Fleet-Average Standard

Volume

i i

i



 



(4) You may group subconfigurations within a configuration together for purposes of 

calculating your fleet-average standard as follows:

(i) You may group together subconfigurations that have the same equivalent test 

weight (ETW), GVWR, and GCWR. Calculate your work factor and target value 

assuming a curb weight equal to two times ETW minus GVWR. 

(ii) You may group together other subconfigurations if you use the lowest target 

value calculated for any of the subconfigurations.
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(b) Production and in-use CO2 standards. Each vehicle you produce that is subject to the 

standards of this section has an “in-use” CO2 standard that is calculated from your test 

result and that applies for selective enforcement audits and in-use testing. This in-use 

CO2 standard for each vehicle is equal to the applicable deteriorated emission level 

multiplied by 1.10 and rounded to the nearest 0.1 g/mile.

(c) N2O and CH4 standards. Except as allowed under this paragraph (c), all vehicles 

subject to the standards of this section must comply with an N2O standard of 0.05 g/mile 

and a CH4 standard of 0.05 g/mile. You may specify CH4 and/or N2O alternate standards 

using CO2 emission credits instead of these otherwise applicable emission standards for 

one or more test groups, consistent with the provisions of 40 CFR 86.1818. To do this, 

calculate the CH4 and/or N2O emission credits needed (negative credits) using the 

equation in this paragraph (c) based on the FEL(s) you specify for your vehicles during 

certification. You must adjust the calculated emissions by the global warming potential 

(GWP): GWP equals 25 for CH4 and 298 for N2O. This means you must use 25 Mg of 

positive CO2 credits to offset 1 Mg of negative CH4 credits and 298 Mg of positive CO2

credits to offset 1 Mg of negative N2O credits. Note that 40 CFR 86.1818-12(f) does not 

apply for vehicles subject to the standards of this section. Calculate credits using the 

following equation:

CO2 Credits Needed (Mg) = [(FEL - Std) × (U.S.-directed production volume) × (Useful 

Life)] × (GWP) ÷ 1,000,000 

(d) Compliance provisions. Except as specified in this paragraph (d) or elsewhere in this 

section, the provisions of 40 CFR part 86, describing compliance with the greenhouse gas 

standards of 40 CFR part 86, subpart S, apply with respect to the standards of paragraphs 

(a) through (c) of this section.

(1) The CO2 standards of this section apply with respect to CO2 emissions, not with 

respect to carbon-related exhaust emissions (CREE).

(2) Vehicles subject to the standards of this section are included in a single 

greenhouse gas averaging set separate from any averaging sets otherwise included in 

40 CFR part 86. 

(3) Special credit and incentive provisions related to flexible fuel vehicles and air 

conditioning in 40 CFR part 86 do not apply for vehicles subject to the standards of 

this section.

(4) The CO2, N2O, and CH4 standards apply for a weighted average of the city (55%) 

and highway (45%) test cycle results as specified for light-duty vehicles in 40 CFR 

part 86, subpart S. Note that this differs from the way the criteria pollutant standards 

apply for heavy-duty vehicles. 

(5) Apply an additive deterioration factor of zero to measured CO2 emissions unless 

good engineering judgment indicates that emissions are likely to deteriorate in use. 

Use good engineering judgment to develop separate deterioration factors for N2O and 

CH4.
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(6) Credits are calculated using the useful life value (in miles) in place of the “vehicle 

lifetime miles” specified in 40 CFR part 86, subpart S.

(7) Credits generated from hybrid vehicles with regenerative braking or from vehicles 

with other advanced technologies may be used to show compliance with any

standards of this part or 40 CFR part 1036, subject to the service class restrictions in 

§1037.740. Include these vehicles in a separate fleet-average calculation (and 

exclude them from your conventional fleet-average calculation). You must first apply

these advanced technology vehicle credits to any deficits for other vehicles in the 

averaging set before applying them to other averaging sets.

(8) The provisions of 40 CFR 86.1818 do not apply.

(9) Calculate your fleet-average emission rate consistent with good engineering 

judgment and the provisions of 40 CFR 86.1865. The following additional provisions 

apply:

(i) Unless we approve a lower number, you must test at least ten 

subconfigurations. If you produce more than 100 subconfigurations in a given 

model year, you must test at least ten percent of your subconfigurations. For 

purposes of this paragraph (9)(i), count carryover tests, but do not include 

analytically derived CO2 emission rates, data substitutions, or other untested 

allowances. We may approve a lower number of tests for manufacturers that have 

limited product offerings, or low sales volumes. Note that good engineering 

judgment and other provisions of this part may require you to test more 

subconfigurations than these minimum values.

(ii) The provisions of paragraph (g) of this section specify how you may use 

analytically derived CO2 emission rates.

(iii) At least 90 percent of final production volume at the configuration level must 

be represented by test data (real, data substituted, or analytical).

(10) For dual fuel, multi-fuel, and flexible fuel vehicles, perform exhaust testing on 

each fuel type (for example, gasoline and E85). 

(i) For your fleet-average calculations, use either the conventional-fueled CO2

emission rate or a weighted average of your emission results as specified in 40 

CFR 600.510–12(k) for light-duty trucks. 

(ii) If you certify to an alternate standard for N2O or CH4 emissions, you may not 

exceed the alternate standard when tested on either fuel.

(11) Test your vehicles with an equivalent test weight based on its Adjusted Loaded 

Vehicle Weight (ALVW). Determine equivalent test weight from the ALVW as 

specified in 40 CFR 86.129, except that you may round values to the nearest 500 

pound increment for ALVW above 14,000 pounds).
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(12) The following definitions apply for purposes of this section: 

(i) Configuration means a subclassification within a test group which is based on 

engine code, transmission type and gear ratios, final drive ratio, and other 

parameters which we designate. Note that this differs from the definition in 40 

CFR 86.1803 because it excludes inertia weight class as a criterion.

(ii) Subconfiguration means a unique combination within a vehicle configuration 

(as defined in this paragraph (d)(12)) of equivalent test weight, road-load 

horsepower, and any other operational characteristics or parameters that we 

determine may significantly affect CO2 emissions within a vehicle configuration.

(iii) The terms “complete vehicle” and “incomplete vehicle” have the meanings 

given for “complete heavy-duty vehicle” and “incomplete heavy-duty vehicle” in 

40 CFR 86.1803.

(13) This paragraph (d)(13) applies for CO2 reductions resulting from technologies 

that were not in common use before 2010 that are not reflected in the specified test 

procedures. We may allow you to generate emission credits consistent with the 

provisions of 40 CFR 86.1866-12(d). You do not need to provide justification for not 

using the 5-cycle methodology option.

(14) You must submit pre-model year reports before you submit your applications for 

certification for a given model year. Unless we specify otherwise, include the 

information specified for pre-model year reports in 49 CFR 535.8.

(e) Useful life. Your vehicles must meet the exhaust emission standards of this section 

throughout their full useful life, expressed in service miles or calendar years, whichever 

comes first. The useful life values for the standards of this section are those that apply

for criteria pollutants under 40 CFR part 86.

(f) Exclusion of vehicles not certified as complete vehicles. The standards of this section 

apply for each vehicle that is chassis-certified with respect to criteria pollutants under 40 

CFR part 86, subpart S. The standards of this section do not apply for other vehicles, 

except as noted in §1037.150. Note that vehicles excluded under this paragraph (f) are 

not considered to be “subject to the standards of this section.” The vehicle standards and 

requirements of § 1037.105 apply for the excluded vehicles. The GHG standards of 40 

CFR part 1036 also apply for engines used in these excluded vehicles. If you are not the 

engine manufacturer, you must notify the engine manufacturer that its engines are subject 

to 40 CFR part 1036 because you intend to use their engines in your excluded vehicles. 

(g) Analytically derived CO2 emission rates (ADCs). This paragraph (g) describes an 

allowance to use estimated (i.e., analytically derived) CO2 emission rates based on 

baseline test data instead of measured emission rates for calculating fleet-average 

emissions. Note that these ADCs are similar to ADFEs used for light-duty vehicles. 

Note also that F terms used in this paragraph (g) represent coefficients from the following 

road load equation:
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 − ()() = 0 + 1 ∙ () + 2 ∙ ()



(1) Except as specified in paragraph (g)(2) of this section, use the following equation 

to calculate the ADC of a new vehicle from road load force coefficients (F0, F1, F2), 

axle ratio, and test weight :

 = 2 + 2.18 ∙ ∆0 + 37.4 ∙ ∆1 + 2257 ∙ ∆2 + 189 ∙ ∆ + 0.0222

∙ ∆

Where:

ADC = Analytically derived combined city/highway CO2 emission rate (g/mile) for a 

new vehicle.

CO2base= Combined city/highway CO2 emission rate (g/mile) of a baseline vehicle.

ΔF0 = F0 of the new vehicle – F0 of the baseline vehicle.

ΔF1 = F1 of the new vehicle – F1 of the baseline vehicle.

ΔF2 = F2 of the new vehicle – F2 of the baseline vehicle.

ΔAR = Axle ratio of the new vehicle – axle ratio of the baseline vehicle.

ΔETW = ETW of the new vehicle – ETW of the baseline vehicle.

(2) The purpose of this section is to accurately estimate CO2 emission rates. You 

must apply the provisions of this section consistent with good engineering judgment. 

For example, do not use the equation in paragraph (g)(1) of this section where good 

engineering judgment indicates that it will not accurately estimate emissions. You 

may ask us to approve alternate equations that allow you to estimate emissions more 

accurately.

(3) You may select, without our prior approval, baseline test data that meet all the 

following criteria:

(i) Vehicles considered for selection for the baseline test must comply with all 

applicable emission standards in the model year associated with the ADC.

(ii) You must include in the pool of tests which will be considered for baseline 

selection all official tests of the same or equivalent basic engine, transmission 

class, engine code, transmission code, engine horsepower, dynamometer drive 
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wheels, and compression ratio as the ADC subconfiguration. Do not include 

tests in which emissions exceed any applicable standards.

(iii) Where necessary to minimize the CO2 adjustment, you may supplement 

the pool with tests associated with worst-case engine or transmission codes 

and carryover or carry-across engine families. If you do, all the data that 

qualify for inclusion using the elected worst-case substitution (or carryover or 

carry-across) must be included in the pool as supplemental data (i.e., 

individual test vehicles may not be selected for inclusion). You must also 

include the supplemental data in all subsequent pools, where applicable.

(iv) Tests previously used during the subject model year as baseline tests in 

ten other ADC subconfigurations must be eliminated from the pool. (v) Select 

the tested subconfiguration with the smallest absolute difference between the 

ADC and the test CO2 emission rate for combined emissions. Use this as the 

baseline test for the target ADC subconfiguration.

(4) You may ask us to allow you use baseline test data not fully meeting the 

provisions of paragraph (g)(3) of this section.

(5) Calculate the ADC rounded to the nearest 0.1 g/mile. The downward adjustment 

of ADC from the baseline is limited to ADC values 20 percent below the baseline 

emission rate (i.e., baseline emission rate × 0.80). The upward adjustment is not 

limited.

(6) You may not submit an ADC if an actual test has been run on the target 

subconfiguration during the certification process or on a development vehicle that is 

eligible to be declared as an emission-data vehicle.

(7) No more than 40 percent of the subconfigurations tested in your final CO2

submission may be represented by ADCs.

(8) You must retain for five years the pool of tests, the vehicle description and tests 

chosen as the baseline and the basis for its selection, the target ADC 

subconfiguration, and the calculated emission rates. We may ask to see these records 

at any time. 

(9) We may perform or order a confirmatory test of any subconfiguration covered by 

an ADC.

(10) Where we determine that you did not fully comply with the provisions of this 

paragraph (g), we may rescind the use of ADC data, require generation of actual test 

data, and require recalculation of your fleet-average emission rate. 

(h) Applicability of part 1037 provisions. Except as specified in this section, the 

requirements of this part do not apply to vehicles certified to the standards of this section. 

The following provisions are the only provisions of this part that apply to vehicles 

certified under this section:
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(1) The provisions of this section.

(2) [Reserved]

(3) The air conditioning standards in § 1037.115.

(4) The interim provisions of § 1037.150(a), (b), (c), (e) - (i), (l), and (m).

(5) The definitions of § 1037.801, to the extent such terms are used relative to 

vehicles subject to standards under this section. 

§ 1037.105 Exhaust emission standards for CO2 for vocational vehicles.

(a) The standards of this section apply for the following vehicles:

(1) Vehicles above 14,000 pounds GVWR and at or below 26,000 pounds GVWR, 

but not certified to the vehicle standards §1037.104.

(2) Vehicles above 26,000 pounds GVWR that are not tractors.

(3) Vocational tractors.

(4) Vehicles at or below 14,000 pounds GVWR that are excluded from the standards 

in § 1037.104 under § 1037.104 (f) or use engines certified under §1037.150(m). 

(b) The CO2 standards of this section are given in Table 1 to this section. The provisions 

of § 1037.241 specify how to comply with these standards.

Table 1 to § 1037.105—CO2 Standards for Vocational Vehicles

GVWR 

(pounds)

CO2 Standard (g/ton-mile) 

for

Model Years 2014-2016

CO2 Standard (g/ton-mile) 

for

Model Year 2017 and later

GVWR < 19,500 388 373

19,500 < GVWR < 33,000 234 225

33,000 < GVWR 226 222

(c) No CH4 or N2O standards apply under this section. See 40 CFR part 1036 for CH4 or 

N2O standards that apply to engines used in these vehicles.

(d) You may generate or use emission credits under the ABT program as described in 

subpart H of this part. This requires that you specify a Family Emission Limit (FEL) for 

CO2 for each vehicle subfamily. The FEL may not be less than the result of emission 

modeling from § 1037.520. These FELs serve as the emission standards for the vehicle 

subfamily instead of the standards specified in paragraph (b) of this section. 
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(e) Your vehicles must meet the exhaust emission standards of this section throughout 

their full useful life, expressed in service miles or calendar years, whichever comes first. 

The following useful life values apply for the standards of this section: 

(1) 110,000 miles or 10 years, whichever comes first, for vehicles at or below 19,500 

pounds GVWR.

(2) 185,000 miles or 10 years, whichever comes first, for vehicles above 19,500 

pounds GVWR and at or below 33,000 pounds GVWR.

(3) 435,000 miles or 10 years, whichever comes first, for vehicles above 33,000 

pounds GVWR.

(f) See § 1037.631 for provisions that exempt certain vehicles used in off-road operation 

from the standards of this section.

(g) You may optionally certify a vocational vehicle to the standards and useful life 

applicable to a higher vehicle service class (such as medium heavy-duty instead of light 

heavy-duty), provided you do not generate credits with the vehicle. If you include 

smaller vehicles in a credit-generating subfamily (with an FEL below the standard), 

exclude its production volume from the credit calculation. 

§ 1037.106 Exhaust emission standards for CO2 for tractors above 26,000 pounds 

GVWR.

(a) The CO2standards of this section apply for tractors above 26,000 pounds GVWR. 

Note that the standards of this section do not apply for vehicles classified as “vocational 

tractors” under §1037.630, 

(b) The CO2 standards for tractors above 26,000 pounds GVWR are given in Table 1 to 

this section. The provisions of § 1037.241 specify how to comply with these standards.
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Table 1 to § 1037.106—CO2 Standards for Tractors above 26,000 Pounds GVWR

GVWR 

(pounds)

Sub-category CO2 Standard 

(g/ton-mile) for 

Model Years 

2014-2016

CO2 Standard 

(g/ton-mile) for 

Model Year 

2017 and later

26,000 < GVWR < 33,000

Low-Roof 

(all cab styles)

107 104

Mid-Roof

(all cab styles)

119 115

High-Roof

(all cab styles)

124 120

GVWR > 33,000

Low-Roof Day Cab 81 80

Low-Roof Sleeper Cab 68 66

Mid-Roof Day Cab 88 86

Mid-Roof Sleeper Cab 76 73

High-Roof Day Cab 92 89

High-Roof Sleeper Cab 75 72

(c) No CH4 or N2O standards apply under this section. See 40 CFR part 1036 for CH4 or 

N2O standards that apply to engines used in these vehicles.

(d) You may generate or use emission credits under the ABT program, as described in 

subpart H of this part. This requires that you specify a Family Emission Limit (FEL) for 

each pollutant you include in the ABT program for each vehicle subfamily. The FEL 

may not be less than the result of emission modeling from § 1037.520. These FELs serve 

as the emission standards for the specific vehicle subfamily instead of the standards 

specified in paragraph (a) of this section. 

(e) Your vehicles must meet the exhaust emission standards of this section throughout 

their full useful life, expressed in service miles or calendar years, whichever comes first. 

The following useful life values apply for the standards of this section: 

(1) 185,000 miles or 10 years, whichever comes first, for vehicles at or below 33,000 

pounds GVWR.

(2) 435,000 miles or 10 years, whichever comes first, for vehicles above 33,000 

pounds GVWR.

(f) You may optionally certify a tractor to the standards and useful life applicable to a 

higher vehicle service class (such as heavy heavy-duty instead of medium heavy-duty), 

provided you do not generate credits with the vehicle. If you include smaller vehicles in a 

credit-generating subfamily (with an FEL below the standard), exclude its production 

volume from the credit calculation. 

§ 1037.115 Other requirements. 
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Vehicles required to meet the emission standards of this part must meet the following 

additional requirements, except as noted elsewhere in this part:

(a) Adjustable parameters. Vehicles that have adjustable parameters must meet all the 

requirements of this part for any adjustment in the physically adjustable range. We may 

require that you set adjustable parameters to any specification within the adjustable range 

during any testing. See 40 CFR part 86 for information related to determining whether or 

not an operating parameter is considered adjustable. You must ensure safe vehicle 

operation throughout the physically adjustable range of each adjustable parameter, 

including consideration of production tolerances. Note that adjustable roof fairings are 

deemed not to be adjustable parameters.

(b) Prohibited controls. You may not design your vehicles with emission control devices, 

systems, or elements of design that cause or contribute to an unreasonable risk to public 

health, welfare, or safety while operating. For example, this would apply if the vehicle 

emits a noxious or toxic substance it would otherwise not emit that contributes to such an 

unreasonable risk.

(c) Air conditioning leakage. Loss of refrigerant from your air conditioning systems may

not exceed 1.50 percent per year, except as allowed by paragraphs (c)(2) and (3) of this 

section. Calculate the total leakage rate in g/year as specified in 40 CFR 86.166. 

Calculate the percent leakage rate as: [total leakage rate (g/yr)] ÷ [total refrigerant 

capacity (g)] × 100. Round your leakage rate to the nearest one-hundredth of a percent. 

See § 1037.150 for vocational vehicles.

(1) For purpose of this requirement, “refrigerant capacity” is the total mass of 

refrigerant recommended by the vehicle manufacturer as representing a full charge. 

Where full charge is specified as a pressure, use good engineering judgment to 

convert the pressure and system volume to a mass.

(2) If your system uses a refrigerant other than HFC–134a, adjust your leakage rate 

by multiplying it by the global warming potential of your refrigerant and dividing the 

product by 1430 (which is the global warming potential of HFC–134a). Apply this 

adjustment before comparing your leakage rate to the standard. Determine global 

warming potentials consistent with 40 CFR 86.1866. Note that global warming 

potentials represent the equivalent grams of CO2 that would have the same global 

warming impact (over 100 years) as one gram of the refrigerant.

(3) If your total refrigerant capacity is less than 734 grams, your leakage rate may 

exceed 1.50 percent, as long as the total leakage rate does not exceed 11.0 g/yr. If 

your system uses a refrigerant other than HFC–134a, you may adjust your leakage 

rate as specified in paragraph (c)(2) of this section.

§ 1037.120 Emission-related warranty requirements.

(a) General requirements. You must warrant to the ultimate purchaser and each 

subsequent purchaser that the new vehicle, including all parts of its emission control 

system, meets two conditions:

(1) It is designed, built, and equipped so it conforms at the time of sale to the ultimate 

purchaser with the requirements of this part.
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(2) It is free from defects in materials and workmanship that cause the vehicle to fail 

to conform to the requirements of this part during the applicable warranty period.

(b) Warranty period. (1) Your emission-related warranty must be valid for at least:

(i) 5 years or 50,000 miles for spark-ignition vehicles and light heavy-duty 

vehicles.

(ii) 5 years or 100,000 miles for medium and heavy heavy-duty vehicles.

(iii) 2 years or 24,000 miles for tires.

(2) You may offer an emission-related warranty more generous than we require. The 

emission-related warranty for the vehicle may not be shorter than any basic 

mechanical warranty you provide to that owner without charge for the vehicle. 

Similarly, the emission-related warranty for any component may not be shorter than 

any warranty you provide to that owner without charge for that component. This 

means that your warranty for a given vehicle may not treat emission-related and 

nonemission-related defects differently for any component. The warranty period 

begins when the vehicle is placed into service. 

(c) Components covered. The emission-related warranty covers vehicle speed limiters, 

idle shutdown systems, fairings, and hybrid system components, to the extent such 

emission-related components are included in the certified emission controls. The 

emission-related warranty covers tires and all components whose failure would increase a 

vehicle's evaporative emissions (for vehicles subject to evaporative emission standards). 

The emission-related warranty covers these components even if another company

produces the component. Your emission-related warranty does not need to cover 

components whose failure would not increase a vehicle's emissions of any regulated 

pollutant.

(d) Limited applicability. You may deny warranty claims under this section if the 

operator caused the problem through improper maintenance or use, as described in 40 

CFR 1068.115.

(e) Owners manual. Describe in the owners manual the emission-related warranty 

provisions from this section that apply to the vehicle.

§ 1037.125 Maintenance instructions and allowable maintenance.

Give the ultimate purchaser of each new vehicle written instructions for properly 

maintaining and using the vehicle, including the emission control system. The 

maintenance instructions also apply to service accumulation on any of your emission-data 

vehicles. See paragraph (i) of this section for requirements related to tire replacement.

(a) Critical emission-related maintenance. Critical emission-related maintenance 
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includes any adjustment, cleaning, repair, or replacement of critical emission-related 

components. This may also include additional emission-related maintenance that you 

determine is critical if we approve it in advance. You may schedule critical emissionrelated maintenance on these components if you demonstrate that the maintenance is 

reasonably likely to be done at the recommended intervals on in-use vehicles. We will 

accept scheduled maintenance as reasonably likely to occur if you satisfy any of the 

following conditions:

(1) You present data showing that, if a lack of maintenance increases emissions, it 

also unacceptably degrades the vehicle’s performance.

(2) You present survey data showing that at least 80 percent of vehicles in the field 

get the maintenance you specify at the recommended intervals.

(3) You provide the maintenance free of charge and clearly say so in your 

maintenance instructions. 

(4) You otherwise show us that the maintenance is reasonably likely to be done at the 

recommended intervals.

(b) Recommended additional maintenance. You may recommend any additional amount 

of maintenance on the components listed in paragraph (a) of this section, as long as you 

state clearly that these maintenance steps are not necessary to keep the emission-related 

warranty valid. If operators do the maintenance specified in paragraph (a) of this section, 

but not the recommended additional maintenance, this does not allow you to disqualify

those vehicles from in-use testing or deny a warranty claim. Do not take these 

maintenance steps during service accumulation on your emission-data vehicles.

(c) Special maintenance. You may specify more frequent maintenance to address 

problems related to special situations, such as atypical vehicle operation. You must 

clearly state that this additional maintenance is associated with the special situation you 

are addressing. We may disapprove your maintenance instructions if we determine that 

you have specified special maintenance steps to address vehicle operation that is not 

atypical, or that the maintenance is unlikely to occur in use. If we determine that certain 

maintenance items do not qualify as special maintenance under this paragraph (c), you 

may identify this as recommended additional maintenance under paragraph (b) of this 

section. 

(d) Noncritical emission-related maintenance. Subject to the provisions of this paragraph 

(d), you may schedule any amount of emission-related inspection or maintenance that is 

not covered by paragraph (a) of this section (that is, maintenance that is neither explicitly

identified as critical emission-related maintenance, nor that we approve as critical 

emission-related maintenance). Noncritical emission-related maintenance generally 

includes maintenance on the components we specify in 40 CFR part 1068, Appendix I, 

that is not covered in paragraph (a) of this section. You must state in the owners manual 

that these steps are not necessary to keep the emission-related warranty valid. If 

operators fail to do this maintenance, this does not allow you to disqualify those vehicles 
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from in-use testing or deny a warranty claim. Do not take these inspection or 

maintenance steps during service accumulation on your emission-data vehicles.

(e) Maintenance that is not emission-related. For maintenance unrelated to emission 

controls, you may schedule any amount of inspection or maintenance. You may also take 

these inspection or maintenance steps during service accumulation on your emission-data 

vehicles, as long as they are reasonable and technologically necessary. You may perform 

this nonemission-related maintenance on emission-data vehicles at the least frequent 

intervals that you recommend to the ultimate purchaser (but not the intervals 

recommended for severe service).

(f) Source of parts and repairs. State clearly on the first page of your written maintenance 

instructions that a repair shop or person of the owner's choosing may maintain, replace, 

or repair emission control devices and systems. Your instructions may not require 

components or service identified by brand, trade, or corporate name. Also, do not 

directly or indirectly condition your warranty on a requirement that the vehicle be 

serviced by your franchised dealers or any other service establishments with which you 

have a commercial relationship. You may disregard the requirements in this paragraph 

(f) if you do one of two things:

(1) Provide a component or service without charge under the purchase agreement. 

(2) Get us to waive this prohibition in the public’s interest by convincing us the 

vehicle will work properly only with the identified component or service.

(g) [Reserved]

(h) Owners manual. Explain the owner’s responsibility for proper maintenance in the 

owners manual.

(i) Tire maintenance and replacement. Include instructions that will enable the owner to 

replace tires so that the vehicle conforms to the original certified vehicle configuration.

§ 1037.135 Labeling.

(a) Assign each vehicle a unique identification number and permanently affix, engrave, or 

stamp it on the vehicle in a legible way. The vehicle identification number (VIN) serves 

this purpose.

(b) At the time of manufacture, affix a permanent and legible label identifying each 

vehicle. The label must be–

(1) Attached in one piece so it is not removable without being destroyed or defaced.

(2) Secured to a part of the vehicle needed for normal operation and not normally

requiring replacement.
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(3) Durable and readable for the vehicle’s entire life.

(4) Written in English.

(c) The label must—

(1) Include the heading "VEHICLE EMISSION CONTROL INFORMATION".

(2) Include your full corporate name and trademark. You may identify another 

company and use its trademark instead of yours if you comply with the branding 

provisions of 40 CFR 1068.45.

(3) Include EPA’s standardized designation for the vehicle family.

(4) State the regulatory sub-category that determines the applicable emission 

standards for the vehicle family (see definition in § 1037.801). 

(5) State the date of manufacture [DAY (optional), MONTH, and YEAR]. You may

omit this from the label if you stamp, engrave, or otherwise permanently identify it 

elsewhere on the engine, in which case you must also describe in your application for 

certification where you will identify the date on the engine.

(6) Identify the emission control system. Use terms and abbreviations as described 

in Appendix III to this part or other applicable conventions. 

(7) Identify any requirements for fuel and lubricants that do not involve fuel-sulfur 

levels.

(8) State: "THIS VEHICLE COMPLIES WITH U.S. EPA REGULATIONS FOR 

[MODEL YEAR] HEAVY-DUTY VEHICLES."

(9) Include the following statement, if applicable: “THIS VEHICLE IS DESIGNED 

TO COMPLY WITH EVAPORATIVE EMISSION STANDARDS WITH UP TO x 

GALLONS OF FUEL TANK CAPACITY.” Complete this statement by identifying 

the maximum specified fuel tank capacity associated with your certification.

(d) You may add information to the emission control information label to identify other 

emission standards that the vehicle meets or does not meet (such as European standards). 

You may also add other information to ensure that the vehicle will be properly

maintained and used. 

(e) You may ask us to approve modified labeling requirements in this part 1037 if you 

show that it is necessary or appropriate. We will approve your request if your alternate 

label is consistent with the requirements of this part.

§ 1037.140 Curb weight and roof height.
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(a) Where applicable, a vehicle’s curb weight and roof height are determined from 

nominal design specifications, as provided in this section. Round the weight to the 

nearest pound and height to the nearest inch. Base roof height on fully inflated tires 

having a static loaded radius equal to the arithmetic mean of the largest and smallest 

static loaded radius of tires you offer or a standard tire we approve.

(b) The nominal design specifications must be within the range of the actual weights and 

roof heights of production vehicles considering normal production variability. If after 

production begins it is determined that your nominal design specifications do not 

represent production vehicles, we may require you to amend your application for 

certification under § 1037.225.

(c) If your vehicle is equipped with an adjustable roof fairing, measure the roof height 

with the fairing in its lowest setting.

§ 1037.150 Interim provisions.

The provisions in this section apply instead of other provisions in this part. 

(a) Incentives for early introduction. The provisions of this paragraph (a) apply with 

respect to vehicles produced in model years before 2014 Manufacturers may voluntarily 

certify in model year 2013 (or earlier model years for electric vehicles) to the greenhouse 

gas standards of this part. 

(1) This paragraph (a)(1) applies for regulatory sub-categories subject to the standards 

of §1037.105 or 1037.106. Except as specified in paragraph (a)(3) of this section, to 

generate early credits under this paragraph for any vehicles other than electric 

vehicles, you must certify your entire U.S.-directed production volume within the 

regulatory sub-category to these standards. Except as specified in paragraph(a)(4) of 

this section, if some vehicle families within a regulatory sub-category are certified 

after the start of the model year, you may generate credits only for production that 

occurs after all families are certified. For example, if you produce three vehicle 

families in an averaging set and you receive your certificates for those families on 

January 4, 2013, March 15, 2013, and April 24, 2013, you may not generate credits 

for model year 2013 production in any of the families that occurs before April 24, 

2013. Calculate credits relative to the standard that would apply in model year 2014 

using the equations in subpart H of this part. You may bank credits equal to the 

surplus credits you generate under this paragraph (a) multiplied by 1.50. For 

example, if you have 1.0 Mg of surplus credits for model year 2013, you may bank 

1.5 Mg of credits. Credit deficits for an averaging set prior to model year 2014 do not 

carry over to model year 2014. These credits may be used to show compliance with 

the standards of this part for 2014 and later model years. We recommend that you 

notify EPA of your intent to use this provision before submitting your applications.

(2) This paragraph (a)(2) applies for regulatory sub-categories subject to the standards 

of §1037.104. To generate early credits under this paragraph for any vehicles other 
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than electric vehicles, you must certify your entire U.S.-directed production volume 

within the regulatory sub-category to these standards. If you calculate a separate fleet 

average for advanced-technology vehicles under §1037.104(c)(7), you must certify

your entire U.S.-directed production volume of both advanced and conventional 

vehicles within the regulatory sub-category. Except as specified in paragraph(a)(4) of 

this section, if some test groups are certified after the start of the model year, you may 

generate credits only for production that occurs after all test groups are certified. For 

example, if you produce three test groups in an averaging set and you receive your 

certificates for those test groups on January 4, 2013, March 15, 2013, and April 24, 

2013, you may not generate credits for model year 2013 production in any of the test 

groups that occurs before April 24, 2013. Calculate credits relative to the standard 

that would apply in model year 2014 using the applicable equations in 40 CFR part 

86 and your model year 2013 U.S.-directed production volumes. These credits may

be used to show compliance with the standards of this part for 2014 and later model 

years. We recommend that you notify EPA of your intent to use this provision before 

submitting your applications.

(3) You may generate emission credits for the number of additional SmartWay

designated tractors (relative to your 2012 production), provided you do not generate 

credits for those vehicles under paragraph (a)(1) of this section. Calculate credits for 

each regulatory sub-category relative to the standard that would apply in model year 

2014 using the equations in subpart H of this part. Use a production volume equal to 

the number of designated model year 2013 SmartWay tractors minus the number of 

designated model year 2012 SmartWay tractors. You may bank credits equal to the 

surplus credits you generate under this paragraph multiplied by 1.50. Your 2012 and 

2013 model years must be equivalent in length. 

(4) This paragraph (a)(4) applies where you do not receive your final certificate in a 

regulatory sub-category within 30 days of submitting your final application for that 

sub-category. Calculate your credits for all production that occurs 30 days or more 

after you submit your final application for the sub-category. 

(b) Phase-in provisions. Each manufacturer must choose one of the following options for 

phasing in the standards of § 1037.104:

(1) To implement the phase-in under this paragraph (b)(1), the standards in 

§ 1037.104 apply as specified for model year 2018, with compliance for vehicles in 

model years 2014 through 2017 based on the CO2 target values specified in the 

following table: 
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Table 1 to § 1037.150

Model Year and Engine Cycle Alternate CO2 Target (g/mile)

2014 Spark-Ignition [0.0482 × (WF)] + 371

2015 Spark-Ignition [0.0479 × (WF)] + 369

2016 Spark-Ignition [0.0469 × (WF)] + 362

2017 Spark-Ignition [0.0460 × (WF)] + 354

2014 Compression-Ignition [0.0478 × (WF)] + 368

2015 Compression-Ignition [0.0474 × (WF)] + 366

2016 Compression-Ignition [0.0460 × (WF)] + 354

2017 Compression-Ignition [0.0445 × (WF)] + 343

(2) To implement the phase in under this paragraph (b)(2), the standards in 

§ 1037.104 apply as specified for model year 2019, with compliance for vehicles in 

model years 2014 through 2018 based on the CO2 target values specified in the 

following table: 

Table 2 to § 1037.150

Model Year and Engine Cycle Alternate CO2 Target (g/mile)

2014 Spark-Ignition [0.0482 × (WF)] + 371

2015 Spark-Ignition [0.0479 × (WF)] + 369

2016-2018 Spark-Ignition [0.0456 × (WF)] + 352

2014 Compression-Ignition [0.0478 × (WF)] + 368

2015 Compression-Ignition [0.0474 × (WF)] + 366

2016-2018 Compression-Ignition [0.0440 × (WF)] + 339

(c) Provisions for small manufacturers. Manufacturers meeting the small business 

criteria specified in 13 CFR 121.201 for “Heavy Duty Truck Manufacturing” are not 

subject to the greenhouse gas standards of §§ 1037.104 through 1037.106, as specified in 

this paragraph (c). Qualifying manufacturers must notify the Designated Compliance 

Officer each model year before introducing these excluded vehicles into U.S. commerce. 

This notification must include a description of the manufacturer’s qualification as a small 

business under 13 CFR 121.201. You must label your excluded vehicles with the 

following statement: “THIS VEHICLE IS EXCLUDED UNDER 40 CFR 1037.150(c).”.

(d) Air conditioning leakage for vocational vehicles. The air conditioning leakage 

standard of § 1037.115 does not apply for vocational vehicles. 

(e) Model year 2014 N2O standards. In model year 2014 and earlier, manufacturers may

show compliance with the N2O standards using an engineering analysis. This allowance 

also applies for later test groups families carried over from model 2014 consistent with 

the provisions of 40 CFR 86.1839. You may not certify to an N2O FEL different than the 

standard without measuring N2O emissions.

(f) Electric vehicles. All electric vehicles are deemed to have zero emissions of CO2, 
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CH4, and N2O. No emission testing is required for electric vehicles.

(g) Compliance date. Compliance with the standards of this part is optional prior to 

January 1, 2014. This means that if your 2014 model year begins before January 1, 2014, 

you may certify for a partial model year that begins on January 1, 2014 and ends on the 

day your model year would normally end. You must label model year 2014 vehicles 

excluded under this paragraph (g) with the following statement: “THIS VEHICLE IS

EXCLUDED UNDER 40 CFR 1037.150(g).” 

(h) Off-road vehicle exemption. In unusual circumstances, vehicle manufacturers may

ask us to exempt vehicles under §1037.631 based on other criteria that are equivalent to 

those specified in §1037.631(a). For example, we would normally not grant relief in 

cases where the vehicle manufacturer had credits or other compliant tires were available.

(i) Credit multiplier for advanced technology. If you generate credits from vehicles 

certified with advanced technology, you may multiply these credits by 1.50, except that 

you may not apply this multiplier in addition to the early-credit multiplier of paragraph 

(a) of this section.

(j) Limited prohibition related to early model year engines. The prohibition in §1037.601 

against introducing into U.S. commerce a vehicle containing an engine not certified to the 

standards of this part does not apply for vehicles using model year 2014 or 2015 sparkignition engines, or any model year 2013 or earlier engines.

(k) Verifying drag areas from in-use vehicles. We may measure the drag area of your 

vehicles after they have been placed into service. Your vehicle conforms to the 

regulations of this part with respect to aerodynamic performance if we measure its drag 

area to be at or below the maximum drag area allowed for the bin to which that 

configuration was certified. To account for measurement variability, your vehicle is also 

deemed to conform to the regulations of this part with respect to aerodynamic 

performance if we measure its drag area to at or below the maximum drag area allowed 

for the bin above the bin to which you certified (for example, Bin II if you certified the 

vehicle to Bin III), unless we determine that you knowingly produced the vehicle to have 

a higher drag area than is allowed for the bin to which it was certified. 

(l) Optional certification under §1037.104. You may certify certain complete or cabcomplete vehicles to the standards of §1037.104. All vehicles optionally certified under 

this paragraph (l) are deemed to be subject to the standards of §1037.104. Note that 

certification under this paragraph (l) does not affect how you may or may not certify with 

respect to criteria pollutants. For example, certifying a Class 4 vehicle under this 

paragraph does not allow you to chassis-certify these vehicles with respect to criteria 

emissions.

(1) You may certify complete or cab-complete spark-ignition vehicles to the 

standards of §1037.104. 

(2) You may apply the provisions of §1037.104 to cab-complete vehicles based on a 

complete sister vehicle. In unusual circumstances, you may ask us to apply these 
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provisions to Class 2b or 3 incomplete vehicles that do not meet the definition of cabcomplete. Except as specified in paragraph (l)(3) of this section, for purposes of 

§1037.104, a complete sister vehicle is a complete vehicle of the same vehicle 

configuration (as defined in §1037.104) as the cab-complete vehicle. Calculate the 

target value under §1037.104(a) based on the same work factor value that applies for 

the complete sister vehicle. Test these cab-complete vehicles using the same 

equivalent test weight and other dynamometer settings that apply for the complete 

vehicle from which you used the work factor value. For certification, you may 

submit the test data from that complete sister vehicle instead of performing the test on 

the cab-complete vehicle. You are not required to produce the complete sister vehicle 

for sale to use the provisions of this paragraph (l)(2). This means the complete sister 

vehicle may be a carryover vehicle from a prior model year or a vehicle created solely

for the purpose of testing.

(3) You may use as complete sister vehicle a complete vehicle that is not of the same 

vehicle configuration as the cab-complete vehicle as specified in this paragraph (l)(3). 

This allowance applies where the complete vehicle is not of the same vehicle 

configuration as the cab-complete vehicle only because of factors unrelated to 

coastdown performance. If your complete sister vehicle is covered by this paragraph 

(l)(3), you may not submit the test data from that complete sister vehicle and must 

perform the test on the cab-complete vehicle.

(m) Loose engine sales. This paragraph (m) applies for spark-ignition engines identical 

to engines used in vehicles certified to the standards of §1037.104, where you sell such 

engines as loose engines or as engines installed in incomplete vehicles that are not cabcomplete vehicles. For purposes of this paragraph (m), engines would not be considered 

to be identical if they used different engine hardware. You may include such engines in a 

test group certified to the standards of §1037.104, subject to the following provisions:

(1) Engines certified under this paragraph (m) are deemed to be certified to the 

standards of 40 CFR 1036.108 as specified in 40 CFR 1036.108(a)(4).

(2) The U.S.-directed production volume of engines you sell as loose engines or 

installed in incomplete heavy-duty vehicles that are not cab-complete vehicles in any 

given model year may not exceed ten percent of the total U.S-directed production 

volume of engines of that design that you produce for heavy-duty applications for that 

model year, including engines you produce for complete vehicles, cab-complete 

vehicles, and other incomplete vehicles. The total number of engines you may

certify under this paragraph (m), of all engine designs, may not exceed 15,000 in any

model year. Engines produced in excess of either of these limits are not covered by

your certificate. For example, if you produce 80,000 complete model year 2017 Class 

2b pickup trucks with a certain engine and 10,000 incomplete model year 2017 Class 

3 vehicles with that same engine, and you do not apply the provisions of this 

paragraph (m) to any other engine designs, you may produce up to 10,000 engines of 

that design for sale as loose engines under this paragraph (m). If you produced 

11,000 engines of that design for sale as loose engines, the last 1,000 of them that you 

produced in that model year 2017 would be considered uncertified. 
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(3) This paragraph (m) does not apply for engines certified to the standards of 40 

CFR 1036.108(a)(1).

(4) Label the engines as specified in 40 CFR 1036.135 including the following 

compliance statement: “THIS ENGINE WAS CERTIFIED TO THE ALTERNATE 

GREENHOUSE GAS EMISSION STANDARDS OF 40 CFR 1036.108(a)(4).” List 

the test group name instead of an engine family name.

(5) Vehicles using engines certified under this paragraph (m) are subject to the 

emission standards of §1037.105.

(6) For certification purposes, your engines are deemed to have a CO2 target value 

and test result equal to the CO2 target value and test result for the complete vehicle in 

the applicable test group with the highest equivalent test weight, except as specified 

in paragraph (m)(6)(ii) of this section. Use these values to calculate your target value, 

fleet-average emission rate, and in-use emission standard. Where there are multiple 

complete vehicles with the same highest equivalent test weight, select the CO2 target 

value and test result as specified in paragraphs (m)(6)(i) and (ii) of this section:

(i) If one or more of the CO2 test results exceed the applicable target value, use 

the CO2 target value and test result of the vehicle that exceeds its target value by 

the greatest amount.

(ii) If none of the CO2 test results exceed the applicable target value, select the 

highest target value and set the test result equal to it. This means that you may

not generate emission credits from vehicles certified under this paragraph (m).

(7) State in your applications for certification that your test group and engine family

will include engines certified under this paragraph (m). This applies for your 

greenhouse gas vehicle test group and your criteria pollutant engine family. List in 

each application the name of the corresponding test group/engine family.

Subpart C—Certifying Vehicle families

§ 1037.201 General requirements for obtaining a certificate of conformity.

(a) You must send us a separate application for a certificate of conformity for each 

vehicle family. A certificate of conformity is valid from the indicated effective date until 

the end of the model year for which it is issued, which may not extend beyond December 

31 of that year. You must renew your certification annually for any vehicles you 

continue to produce.

(b) The application must contain all the information required by this part and must not 

include false or incomplete statements or information (see § 1037.255). 
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(c) We may ask you to include less information than we specify in this subpart, as long as 

you maintain all the information required by § 1037.250.

(d) You must use good engineering judgment for all decisions related to your application 

(see 40 CFR 1068.5).

(e) An authorized representative of your company must approve and sign the application.

(f) See § 1037.255 for provisions describing how we will process your application.

(g) We may perform confirmatory testing on your vehicles; for example, we may test 

vehicles to verify drag areas or other GEM inputs. We may require you to deliver your 

test vehicles to a facility we designate for our testing. Alternatively, you may choose to 

deliver another vehicle that is identical in all material respects to the test vehicle. Where 

certification is based on testing components such as tires, we may require you to deliver 

test components to a facility we designate for our testing.

§ 1037.205 What must I include in my application?

This section specifies the information that must be in your application, unless we ask you 

to include less information under § 1037.201(c). We may require you to provide 

additional information to evaluate your application. Note that references to testing and 

emission-data vehicles refer to testing vehicles to measure aerodynamic drag, assess 

hybrid vehicle performance, and/or measure evaporative emissions. 

(a) Describe the vehicle family’s specifications and other basic parameters of the 

vehicle’s design and emission controls. List the fuel type on which your vehicles are 

designed to operate (for example, ultra low-sulfur diesel fuel). 

(b) Explain how the emission control system operates. As applicable, describe in detail 

all system components for controlling greenhouse gas and evaporative emissions, 

including all auxiliary emission control devices (AECDs) and all fuel-system components 

you will install on any production vehicle. Identify the part number of each component 

you describe. For this paragraph (b), treat as separate AECDs any devices that modulate 

or activate differently from each other.

(c) For vehicles subject to air conditioning standards, include:

(1) The refrigerant leakage rates (leak scores).

(2) The refrigerant capacity of the air conditioning systems.

(3) The corporate name of the final installer of the air conditioning system.

(d) Describe any vehicles you selected for testing and the reasons for selecting them.
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(e) Describe any test equipment and procedures that you used, including any special or 

alternate test procedures you used (see § 1037.501). 

(f) Describe how you operated any emission-data vehicle before testing, including the 

duty cycle and the number of vehicle operating miles used to stabilize emission levels. 

Explain why you selected the method of service accumulation. Describe any scheduled 

maintenance you did.

(g) List the specifications of any test fuel to show that it falls within the required ranges 

we specify in 40 CFR part 1065.

(h) Identify the vehicle family’s useful life.

(i) Include the maintenance instructions and warranty statement you will give to the 

ultimate purchaser of each new vehicle (see §§ 1037.120 and 1037.125).

(j) Describe your emission control information label (see § 1037.135).

(k) Identify the emission standards or FELs to which you are certifying vehicles in the 

vehicle family. For families containing multiple subfamilies, this means that you must 

identify multiple CO2 FELs. For example, you may identify the highest and lowest 

FELs to which any of your subfamilies will be certified and also list all possible FELs in 

between (which will be in 1 g/ton-mile increments).

(l) Where applicable, identify the vehicle family’s deterioration factors and describe how 

you developed them. Present any emission test data you used for this (see §1037.241(c)).

(m) Where applicable, state that you operated your emission-data vehicles as described in 

the application (including the test procedures, test parameters, and test fuels) to show you 

meet the requirements of this part.

(n) Present evaporative test data to show your vehicles meet the evaporative emission 

standards we specify in subpart B of this part, if applicable. Report all valid test results 

from emission-data vehicles and indicate whether there are test results from invalid tests 

or from any other tests of the emission-data vehicle, whether or not they were conducted 

according to the test procedures of subpart F of this part. We may require you to report 

these additional test results. We may ask you to send other information to confirm that 

your tests were valid under the requirements of this part and 40 CFR part 86. 

(o) Report modeling results for ten configurations. Include modeling inputs and detailed 

descriptions of how they were derived. Unless we specify otherwise, include the 

configuration with the highest modeling result, the lowest modeling result, and the 

configurations with the highest projected sales. 

(p) Describe all adjustable operating parameters (see § 1037.115), including production 

tolerances. You do not need to include parameters that do not affect emissions covered 

by your application. Include the following in your description of each parameter:
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(1) The nominal or recommended setting.

(2) The intended physically adjustable range.

(3) The limits or stops used to establish adjustable ranges.

(4) Information showing why the limits, stops, or other means of inhibiting 

adjustment are effective in preventing adjustment of parameters on in-use vehicles to 

settings outside your intended physically adjustable ranges. 

(q) [Reserved]

(r) Unconditionally certify that all the vehicles in the vehicle family comply with the 

requirements of this part, other referenced parts of the CFR, and the Clean Air Act.

(s) Include good-faith estimates of U.S.-directed production volumes by subfamily. We 

may require you to describe the basis of your estimates.

(t) Include the information required by other subparts of this part. For example, include 

the information required by § 1037.725 if you participate in the ABT program.

(u) Include other applicable information, such as information specified in this part or 40 

CFR part 1068 related to requests for exemptions.

(v) Name an agent for service located in the United States. Service on this agent 

constitutes service on you or any of your officers or employees for any action by EPA or 

otherwise by the United States related to the requirements of this part.

§ 1037.210 Preliminary approval before certification.

If you send us information before you finish the application, we may review it and make 

any appropriate determinations. Decisions made under this section are considered to be 

preliminary approval, subject to final review and approval. We will generally not reverse 

a decision where we have given you preliminary approval, unless we find new 

information supporting a different decision. If you request preliminary approval related to 

the upcoming model year or the model year after that, we will make best-efforts to make 

the appropriate determinations as soon as practicable. We will generally not provide 

preliminary approval related to a future model year more than two years ahead of time.

§ 1037.220 Amending maintenance instructions.

You may amend your emission-related maintenance instructions after you submit your 

application for certification as long as the amended instructions remain consistent with 

the provisions of § 1037.125. You must send the Designated Compliance Officer a 
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written request to amend your application for certification for a vehicle family if you 

want to change the emission-related maintenance instructions in a way that could affect 

emissions. In your request, describe the proposed changes to the maintenance 

instructions. If operators follow the original maintenance instructions rather than the 

newly specified maintenance, this does not allow you to disqualify those vehicles from 

in-use testing or deny a warranty claim.

(a) If you are decreasing or eliminating any specified maintenance, you may distribute the 

new maintenance instructions to your customers 30 days after we receive your request, 

unless we disapprove your request. This would generally include replacing one 

maintenance step with another. We may approve a shorter time or waive this 

requirement.

(b) If your requested change would not decrease the specified maintenance, you may

distribute the new maintenance instructions anytime after you send your request. For 

example, this paragraph (b) would cover adding instructions to increase the frequency of 

filter changes for vehicles in severe-duty applications.

(c) You need not request approval if you are making only minor corrections (such as 

correcting typographical mistakes), clarifying your maintenance instructions, or changing 

instructions for maintenance unrelated to emission control. We may ask you to send us 

copies of maintenance instructions revised under this paragraph (c).

§ 1037.225 Amending applications for certification.

Before we issue you a certificate of conformity, you may amend your application to 

include new or modified vehicle configurations, subject to the provisions of this section. 

After we have issued your certificate of conformity, you may send us an amended 

application requesting that we include new or modified vehicle configurations within the 

scope of the certificate, subject to the provisions of this section. You must amend your 

application if any changes occur with respect to any information that is included or 

should be included in your application.

(a) You must amend your application before you take any of the following actions:

(1) Add a vehicle configuration to a vehicle family. In this case, the vehicle 

configuration added must be consistent with other vehicle configurations in the 

vehicle family with respect to the criteria listed in § 1037.230.

(2) Change a vehicle configuration already included in a vehicle family in a way that 

may affect emissions, or change any of the components you described in your 

application for certification. This includes production and design changes that may

affect emissions any time during the vehicle's lifetime.

(3) Modify an FEL for a vehicle family as described in paragraph (f) of this section.
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(b) To amend your application for certification, send the relevant information to the 

Designated Compliance Officer.

(1) Describe in detail the addition or change in the vehicle model or configuration you 

intend to make.

(2) Include engineering evaluations or data showing that the amended vehicle family 

complies with all applicable requirements. You may do this by showing that the 

original emission-data vehicle is still appropriate for showing that the amended

family complies with all applicable requirements.

(3) If the original emission-data vehicle or emission modeling for the vehicle family

is not appropriate to show compliance for the new or modified vehicle configuration, 

include new test data or emission modeling showing that the new or modified vehicle 

configuration meets the requirements of this part.

(c) We may ask for more test data or engineering evaluations. You must give us these 

within 30 days after we request them. 

(d) For vehicle families already covered by a certificate of conformity, we will determine 

whether the existing certificate of conformity covers your newly added or modified 

vehicle. You may ask for a hearing if we deny your request (see § 1037.820).

(e) For vehicle families already covered by a certificate of conformity, you may start 

producing the new or modified vehicle configuration anytime after you send us your 

amended application and before we make a decision under paragraph (d) of this section. 

However, if we determine that the affected vehicles do not meet applicable requirements, 

we will notify you to cease production of the vehicles and may require you to recall the 

vehicles at no expense to the owner. Choosing to produce vehicles under this paragraph 

(e) is deemed to be consent to recall all vehicles that we determine do not meet applicable 

emission standards or other requirements and to remedy the nonconformity at no expense 

to the owner. If you do not provide information required under paragraph (c) of this 

section within 30 days after we request it, you must stop producing the new or modified 

vehicles.

(f) You may ask us to approve a change to your FEL in certain cases after the start of 

production. The changed FEL may not apply to vehicles you have already introduced 

into U.S. commerce, except as described in this paragraph (f). You may ask us to 

approve a change to your FEL in the following cases:

(1) You may ask to raise your FEL for your vehicle subfamily at any time. In your 

request, you must show that you will still be able to meet the emission standards as 

specified in subparts B and H of this part. Use the appropriate FELs with 

corresponding production volumes to calculate emission credits for the model year, as 

described in subpart H of this part.

(2) Where testing applies, you may ask to lower the FEL for your vehicle subfamily

only if you have test data from production vehicles showing that emissions are below 
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the proposed lower FEL. Otherwise, you may ask to lower your FEL for your vehicle 

subfamily at any time. The lower FEL applies only to vehicles you produce after we 

approve the new FEL. Use the appropriate FELs with corresponding production 

volumes to calculate emission credits for the model year, as described in subpart H of 

this part.

(3) You may ask to add an FEL for your vehicle family at any time.

§ 1037.230 Vehicle families, sub-families, and configurations.

(a) For purposes of certifying your vehicles to greenhouse gas standards, divide your 

product line into families of vehicles as specified in this section. Your vehicle family is 

limited to a single model year. Group vehicles in the same vehicle family if they are the 

same in all the following aspects:

(1) The regulatory sub-category (or equivalent in the case of vocational tractors), as 

follows:

(i) Vocational vehicles at or below 19,500 pounds GVWR. 

(ii) Vocational vehicles (other than vocational tractors) above 19,500 pounds 

GVWR and at or below 33,000 pounds GVWR.

(iii) Vocational vehicles (other than vocational tractors) above 33,000 pounds 

GVWR.

(iv) Low-roof tractors above 26,000 pounds GVWR and at or below 33,000 

pounds GVWR

(v) Mid-roof tractors above 26,000 pounds GVWR and at or below 33,000 pounds 

GVWR.

(vi) High-roof tractors above 26,000 pounds GVWR and at or below 33,000 

pounds GVWR.

(vii) Low-roof day cab tractors above 33,000 pounds GVWR.

(viii) Low-roof sleeper cab tractors above 33,000 pounds GVWR.

(ix) Mid-roof day cab tractors above 33,000 pounds GVWR.

(x) Mid-roof sleeper cab tractors above 33,000 pounds GVWR.

(xi) High-roof day cab tractors above 33,000 pounds GVWR.

(xii) High-roof sleeper cab tractors above 33,000 pounds GVWR.
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(xiii) Vocational tractors. 

(2) Vehicle technology as follows:

(i) Group together vehicles that do not contain advanced or innovative 

technologies.

(ii) Group together vehicles that contain the same advanced/innovative 

technologies.

(b) If the vehicles in your family are being certified to more than one FEL, subdivide 

your greenhouse gas vehicle families into subfamilies that include vehicles with identical 

FELs. Note that you may add subfamilies at any time during the model year. 

(c) Group vehicles into configurations consistent with the definition of “vehicle 

configuration” in §1037.801. Note that vehicles with hardware or software differences 

that are related to measured or modeled emissions are considered to be different vehicle 

configurations even if they have the same GEM inputs and FEL. Note also, that you are 

not required to separately identify all configurations for certification See paragraph (g) 

of this section for provisions allowing you to group certain hardware differences into the 

same configuration. Note that you are not required to identify all possible configurations 

for certification; also, you are required to include in your end-of year report only those 

configurations you produced.

(d) For a vehicle model that straddles a roof-height, cab type, or GVWR division, you 

may include all the vehicles in the same vehicle family if you certify the vehicle family to 

the more stringent standards. For roof height, this means you must certify to the taller 

roof standards. For cab-type and GVWR, this means you must certify to the numerically 

lower standards. 

(e) [Reserved.]

(f) You may divide your families into more families than specified in this section.

(g) You may ask us to allow you to group into the same configuration vehicles that have 

very small body hardware differences that do not significantly affect drag areas. Note 

that this allowance does not apply for substantial differences, even if the vehicles have 

the same measured drag areas. 

§ 1037.241 Demonstrating compliance with exhaust emission standards for 

greenhouse gas pollutants.

(a) For purposes of certification, your vehicle family is considered in compliance with the 

emission standards in § 1037.105 or § 1037.106 if all vehicle configurations in that 

family have modeled CO2 emission rates (as specified in subpart F of this part) at or 

below the applicable standards. See 40 CFR part 86, subpart S, for showing compliance 
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with the standards of § 1037.104. Note that your FELs are considered to be the 

applicable emission standards with which you must comply if you participate in the ABT 

program in subpart H of this part.

(b) Your vehicle family is deemed not to comply if any vehicle configuration in that 

family has a modeled CO2 emission rate that is above its FEL. 

(c) We may require you to provide an engineering analysis showing that the performance 

of your emission controls will not deteriorate during the useful life with proper 

maintenance. If we determine that your emission controls are likely to deteriorate during 

the useful life, we may require you to develop and apply deterioration factors consistent 

with good engineering judgment. For example, you may need to apply a deterioration 

factor to address deterioration of battery performance for an electric hybrid vehicle. 

Where the highest useful life emissions occur between the end of useful life and at the 

low-hour test point, base deterioration factors for the vehicles on the difference between 

(or ratio of) the point at which the highest emissions occur and the low-hour test point. 

§ 1037.250 Reporting and recordkeeping.

(a) Within 90 days after the end of the model year, send the Designated Compliance 

Officer a report including the total U.S.-directed production volume of vehicles you 

produced in each vehicle family during the model year(based on information available at 

the time of the report). Report by vehicle identification number and vehicle configuration 

and identify the subfamily identifier. Report uncertified vehicles sold to secondary

vehicle manufacturers. Small manufacturers may omit the reporting requirements of this 

paragraph (a). 

(b) Organize and maintain the following records:

(1) A copy of all applications and any summary information you send us.

(2) Any of the information we specify in § 1037.205 that you were not required to 

include in your application.

(3) A detailed history of each emission-data vehicle, if applicable.

(4) Production figures for each vehicle family divided by assembly plant.

(5) Keep a list of vehicle identification numbers for all the vehicles you produce 

under each certificate of conformity. 

(c) Keep routine data from emission tests required by this part (such as test cell 

temperatures and relative humidity readings) for one year after we issue the associated 

certificate of conformity. Keep all other information specified in this section for eight 

years after we issue your certificate.
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(d) Store these records in any format and on any media, as long as you can promptly send 

us organized, written records in English if we ask for them. You must keep these records 

readily available. We may review them at any time. 

§ 1037.255 What decisions may EPA make regarding my certificate of conformity?

(a) If we determine your application is complete and shows that the vehicle family meets 

all the requirements of this part and the Act, we will issue a certificate of conformity for 

your vehicle family for that model year. We may make the approval subject to additional 

conditions. 

(b) We may deny your application for certification if we determine that your vehicle 

family fails to comply with emission standards or other requirements of this part or the 

Clean Air Act. We will base our decision on all available information. If we deny your 

application, we will explain why in writing.

(c) In addition, we may deny your application or suspend or revoke your certificate if you 

do any of the following:

(1) Refuse to comply with any testing or reporting requirements.

(2) Submit false or incomplete information (paragraph (e) of this section applies if 

this is fraudulent). This includes doing anything after submission of your application 

to render any of the submitted information false or incomplete.

(3) Render any test data inaccurate.

(4) Deny us from completing authorized activities despite our presenting a warrant or 

court order (see 40 CFR 1068.20). This includes a failure to provide reasonable 

assistance.

(5) Produce vehicles for importation into the United States at a location where local 

law prohibits us from carrying out authorized activities.

(6) Fail to supply requested information or amend your application to include all 

vehicles being produced.

(7) Take any action that otherwise circumvents the intent of the Act or this part, with 

respect to your engine family.

(d) We may void the certificate of conformity for a vehicle family if you fail to keep 

records, send reports, or give us information as required under this part or the Act. Note 

that these are also violations of 40 CFR 1068.101(a)(2). 

(e) We may void your certificate if we find that you intentionally submitted false or 

incomplete information. This includes rendering submitted information false or 
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incomplete after submission.

(f) If we deny your application or suspend, revoke, or void your certificate, you may ask 

for a hearing (see § 1037.820).

Subpart D—[Reserved]

Subpart E—In-use Testing

§ 1037.401 General provisions.

We may perform in-use testing of any vehicle subject to the standards of this part. For 

example, we may test vehicles to verify drag areas or other GEM inputs.

Subpart F—Test and Modeling Procedures

§ 1037.501 General testing and modeling provisions.

This subpart specifies how to perform emission testing and emission modeling required 

elsewhere in this part. 

(a) [Reserved] 

(b) Where exhaust emission testing is required, use the equipment and procedures in 40 

CFR part 1066 to determine whether your vehicles meet the duty-cycle emission 

standards in subpart B of this part. Measure the emissions of all the exhaust constituents 

subject to emission standards as specified in 40 CFR part 1066. Use the applicable duty

cycles specified in § 1037.510.

(c) [Reserved]

(d) Use the applicable fuels specified 40 CFR part 1065 to perform valid tests.

(1) For service accumulation, use the test fuel or any commercially available fuel that 

is representative of the fuel that in-use vehicles will use.

(2) For diesel-fueled vehicles, use the appropriate diesel fuel specified for emission 

testing. Unless we specify otherwise, the appropriate diesel test fuel is ultra lowsulfur diesel fuel. 
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(3) For gasoline-fueled vehicles, use the gasoline specified for “General Testing”.

(e) You may use special or alternate procedures as specified in 40 CFR 1065.10. 

(f) This subpart is addressed to you as a manufacturer, but it applies equally to anyone 

who does testing for you, and to us when we perform testing to determine if your vehicles 

meet emission standards.

(g) Apply this paragraph (g) whenever we specify use of standard trailers. Unless 

otherwise specified, a tolerance of ±2 inches applies for all nominal trailer dimensions.

(1) The standard trailer for high-roof tractors must meet the following criteria: 

(i) It is an unloaded two-axle dry van box trailer 53.0 feet long, 102 inches wide, 

and 162 inches high (measured from the ground with the trailer level). 

(ii) It has a king pin located with its center 36±0.5 inches from the front of the 

trailer and a minimized trailer gap (no greater than 45 inches).

(iii) It has a smooth surface with nominally flush rivets and does not include any 

aerodynamic features such as side fairings, boat tails, or gap reducers. It may 

have a scuff band of no more than 0.13 inches in thickness. 

(iv) It includes dual 22.5 inch wheels, standard mudflaps, and standard landing 

gear. The centerline of the rear-most axle must be 146 inches from the rear of the 

trailer.

(2) The standard trailer for mid-roof tractors is an empty two-axle tanker trailer 42±1 

feet long by 140 inches high. 

(i) It has a 40±1 feet long cylindrical tank with a 7000±7 gallon capacity, smooth 

surface, and rounded ends. 

(ii) The standard tanker trailer does not include any aerodynamic features such as 

side fairings, but does include a centered 20 inch manhole, side-centered ladder, 

and lengthwise walkway. It includes dual 24.5 inch wheels.

(3) The standard trailer for low-roof tractors is an unloaded two-axle flat bed trailer 

53±1 feet long and 102 inches wide. 

(i) The deck height is 60.0±0.5 inches in the front and 55.0±0.5 inches in the rear. 

The standard trailer does not include any aerodynamic features such as side 

fairings. 

(ii) It includes an air suspension and dual 22.5 inch wheels on tandem axles 

spread up to 122 inches apart between axle centerlines, measured along the length 

of the trailer. 
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§ 1037.510 Duty-cycle exhaust testing.

This section applies where exhaust emission testing is required, such as when applying 

the provisions of § 1037.615. Note that for most vehicles, testing under this section is not 

required.

(a) Where applicable, measure emissions by testing the vehicle on a chassis dynamometer 

with the applicable test cycles. Each test cycle consists of a series of speed commands 

over time: variable speeds for the transient test and constant speeds for the cruise tests. 

None of these cycles include vehicle starting or warmup; each test cycle begins with a 

running, warmed-up vehicle. Start sampling emissions at the start of each cycle. The 

transient cycle is specified in Appendix I to this part. For the 55 mph and 65 mph cruise 

cycles, sample emissions for 300 second cycles with constant vehicle speeds of 55.0 mph 

and 65.0 mph, respectively. The tolerance around these speed setpoints is ±1.0 mph. 

(b) Calculate the official emission result from the following equation:

55 55 65 65

55 65

1

( )

transient transient

transient

g w m w m w m Emissions

ton mile payload tons D D D

      

           

Where: 

payload = the standard payload, in tons, as specified in §1037.705.

w = weighting factor for the appropriate test cycle, as described in paragraph (c) of this 

section.

m = grams of CO2 emitted over the appropriate test cycle.

D = miles driven over the appropriate test cycle.

(c) Apply weighting factors specific to each type of vehicle and for each duty cycle as 

described in the following table:

Table 1 to § 1037.510—Weighting Factors for Duty Cycles

Transient 55 mph Cruise 65 mph Cruise

Vocational 42% 21% 37%

Vocational Hybrid 

Vehicles

75% 9% 16%

Day Cabs 19% 17% 64%

Sleeper Cabs 5% 9% 86%

(d) For transient testing, compare actual second-by-second vehicle speed with the speed 

specified in the test cycle and ensure any differences are consistent with the criteria as 

specified in 40 CFR part 1066. If the speeds do not conform to these criteria, the test is 
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not valid and must be repeated.

(e) Run test cycles as specified in 40 CFR part 86. For cruise cycle testing of vehicles 

equipped with cruise control, use the vehicle’s cruise control to control the vehicle speed. 

For vehicles equipped with adjustable VSLs, test the vehicle with the VSL at its highest 

setting.

(f) Test the vehicle using its adjusted loaded vehicle weight, unless we determine this 

would be unrepresentative of in-use operation as specified in 40 CFR 1065.10(c)(1).

(g) For hybrid vehicles, correct for the net energy change of the energy storage device as 

described in 40 CFR 1066.501.

§ 1037.520 Modeling CO2 emissions to show compliance.

This section describes how to use the GEM simulation tool (incorporated by reference in 

§ 1037.810) to show compliance with the CO2 standards of §§ 1037.105 and 1037.106. 

Use good engineering judgment when demonstrating compliance using the GEM.

(a) General modeling provisions. To run the GEM, enter all applicable inputs as 

specified by the model. All seven of the following inputs apply for sleeper cab tractors, 

while some do not apply for other regulatory subcategories:

(1) Regulatory subcategory (such as “Class 8 Combination – Sleeper Cab – High 

Roof”).

(2) Coefficient of aerodynamic drag, as described in paragraph (b) of this section. 

Leave this field blank for vocational vehicles.

(3) Steer tire rolling resistance, as described in paragraph (c) of this section.

(4) Drive tire rolling resistance, as described in paragraph (c) of this section.

(5) Vehicle speed limit, as described in paragraph (d) of this section. Leave this field 

blank for vocational vehicles.

(6) Vehicle weight reduction, as described in paragraph (e) of this section. Leave this 

field blank for vocational vehicles.

(7) Extended idle reduction credit, as described in paragraph (f) of this section. Leave 

this field blank for vehicles other than Class 8 sleeper cabs.

(b) Coefficient of aerodynamic drag and drag area. Determine the appropriate drag area 

as follows: 

(1) Use the recommended method or an alternate method to establish a value for the 

vehicle’s drag area, expressed in m2and rounded to two decimal places. Where we 

allow you to group multiple configurations together, measure the drag area of the 

worst-case configuration. Measure drag areas specified in §1037.521.

(2) Determine the bin level for your vehicle based on the drag area from paragraph 

(b)(1) of this section as shown in the following tables:
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High-Roof Day Cabs

Bin Level If your measured CDA (m2) 

is . . . 

Then your CD input is . . .

Bin I ≥ 8.0 0.79

Bin II 7.1-7.9 0.72

Bin III 6.2-7.0 0.63

Bin IV 5.6-6.1 0.56

Bin V ≤ 5.5 0.51

High-Roof Sleeper Cabs

Bin Level If your measured CDA (m2) 

is . . . 

Then your CD input is . . .

Bin I ≥ 7.6 0.75

Bin II 6.7-7.5 0.68

Bin III 5.8-6.6 0.60

Bin IV 5.2-5.7 0.52

Bin V ≤ 5.1 0.47

Low-Roof Day and Sleeper Cabs
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Bin Level If your measured CDA (m2) 

is . . . 

Then your CD input is . . .

Bin I ≥ 5.1 0.77

Bin II ≤ 5.0 0.71

Mid-Roof Day and Sleeper Cabs

Bin Level If your measured CDA (m2) 

is . . . 

Then your CD input is . . .

Bin I ≥ 5.6 0.87

Bin II ≤ 5.5 0.82

(3) For low- and mid-roof tractors, you may determine your drag area bin based on 

the drag area bin of an equivalent high-roof tractor. If the high-roof tractor is in Bin I

or Bin II, then you may assume your equivalent low- and mid-roof tractors are in Bin 

I. If the high-roof tractor is in Bin III, Bin IV, or Bin V, then you may assume your 

equivalent low- and mid-roof tractors are in Bin II.

(c) Steer and drive tire rolling resistance. You must have a tire rolling resistance level 

(TRRL) for each tire configuration. For purposes of this section, you may consider tires 

with the same SKU number to be the same configuration.

(1) Measure tire rolling resistance in kg per metric ton as specified in ISO 28580 

(incorporated by reference in § 1037.810), except as specified in this paragraph (c). 

Use good engineering judgment to ensure that your test results are not biased low. 

You may ask us to identify a reference test laboratory to which you may correlate 

your test results. Prior to beginning the test procedure in Section 7 of ISO 28580 for 

a new bias-ply tire, perform a break-in procedure by running the tire at the specified 

test speed, load, and pressure for 60±2 minutes.

(2) For each tire design tested, measure rolling resistance of at least three different 

tires of that specific design and size. Perform the test at least once for each tire. Use 

the arithmetic mean of these results as your test result. You may use this value as 

your GEM input or select a higher TRRL. You must test at least one tire size for each 

tire model, and may use engineering analysis to determine the rolling resistance of 

other tire sizes of that model. Note that for tire sizes that you do not test, we will treat 

your analytically derived rolling resistances the same as test results, and we may 

perform our own testing to verify your values. We may require you to test a small 

sub-sample of untested tire sizes that we select.

(3) If you obtain your test results from the tire manufacturer or another third party, 
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you must obtain a signed statement from them verifying the tests were conducted 

according to the requirements of this part. Such statements are deemed to be 

submissions to EPA.

(4) For tires marketed as light truck tires and that have load ranges C, D, or E, use as 

the GEM input TRRL at or above the measured rolling resistance multiplied by 0.87. 

(d) Vehicle speed limit. If the vehicles will be equipped with a vehicle speed limiter, 

input the maximum vehicle speed to which the vehicle will be limited (in miles per hour 

rounded to the nearest 0.1 mile per hour) as specified in §1037.640. Otherwise leave this 

field blank. Use good engineering judgment to ensure the limiter is tamper resistant. We 

may require you to obtain preliminary approval for your designs.

(e) Vehicle weight reduction. For purposes of this paragraph (e), high-strength steel is

steel with tensile strength at or above 350 MPa. 

(1) Vehicle weight reduction inputs for wheels are specified relative to dual-wide tires 

with conventional steel wheels. For purposes of this paragraph (e)(1), a light-weight 

aluminum wheel is one that weighs at least 21 lb less than a comparable conventional 

steel wheel. The inputs are listed in Table 4 to this section. For example, a tractor 

with aluminum steer wheels and eight (4×2) dual-wide aluminum drive wheels would 

have an input of 210 lb (2×21 + 8×21). 

Table 4 to § 1037.520—Wheel-Related Weight Reductions

Weight Reduction Technology Weight Reduction 

(lb per tire or wheel)

Single-Wide Drive Tire with . . . Steel Wheel 84

Aluminum Wheel 139

Light-Weight Aluminum Wheel 147

Steer Tire or Dual-wide Drive 

Tire with . . .

High-Strength Steel Wheel 8

Aluminum Wheel 21

Light-Weight Aluminum Wheel 30

(2) Vehicle weight reduction inputs for components other than wheels are specified 

relative to mild steel components as specified in the following table: 
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Table 5 to § 1037.520—Nonwheel-Related Weight Reductions

Weight Reduction Technologies Aluminum Weight 

Reduction (lb)

High-Strength Steel 

Weight Reduction (lb)

Door 20 6

Roof 60 18

Cab rear wall 49 16

Cab floor 56 18

Hood Support Structure System 15 3

Fairing Support Structure System 35 6

Instrument Panel Support Structure 5 1

Brake Drums – Drive (4) 140 11

Brake Drums – Non Drive (2) 60 8

Frame Rails 440 87

Crossmember - Cab 15 5

Crossmember – Suspension 25 6

Crossmember – Non Suspension (3) 15 5

Fifth Wheel 100 25

Radiator Support 20 6

Fuel Tank Support Structure 40 12

Steps 35 6

Bumper 33 10

Shackles 10 3

Front Axle 60 15

Suspension Brackets, Hangers 100 30

Transmission Case 50 12

Clutch Housing 40 10

Drive Axle Hubs (8) 160 4

Non Drive Front Hubs (2) 40 5

Driveshaft 20 5

Transmission/Clutch Shift Levers 20 4

(3) You may ask to apply the innovative technology provisions of §1037.610 for 

weight reductions not covered by this paragraph (e).

(f) Extended idle reduction credit. If your tractor is equipped with idle reduction 

technology meeting the requirements of §1037.660 that will automatically shut off the 

main engine after 300 seconds or less, use 5.0 g/ton-mile as the input (or a lesser value 

specified in §1037.660).Otherwise leave this field blank. 

§1037.521 Aerodynamic measurements.

This section describes how to determine the aerodynamic drag area (CDA) of your vehicle 

using the coastdown procedure in 40 CFR part 1066 or an alternative method correlated 

to it.

(a) General. The primary method for measuring the aerodynamic drag area of vehicles is 

specified in paragraph (b) of this section. You may determine the drag area using an 

alternate method, consistent with the provisions of this section and good engineering 
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judgment, based on wind tunnel testing, computational fluid dynamic modeling, or 

constant-speed road load testing. See 40 CFR 1068.5 for provisions describing how we 

may evaluate your engineering judgment. All drag areas measured using an alternative 

method (CDAalt) must be adjusted to be equivalent to the corresponding drag areas that 

would have been measured using the coastdown procedure as follows: 

(1) Unless good engineering judgment requires otherwise, assume that coastdown 

drag areas are proportional to drag areas measured using alternative methods. This 

means you may apply a single constant adjustment factor (Falt-aero) for a given 

alternate drag area method using the following equation: 

CDA = CDAalt × Falt-aero

(2) Determine Falt-aero by performing coastdown testing and applying your alternate 

method on the same vehicle. Unless we approve another vehicle, the vehicle must be 

a Class 8, high-roof, sleeper cab with a full aerodynamics package, pulling a 

standards trailer. Where you have more than one model meeting these criteria, use 

the model with the highest projected sales. If you do not have such a model you may 

use your most comparable model with prior approval. If good engineering judgment 

allows the use of a single, constant value of Falt-aero, calculate it from this coastdown 

drag area (CDAcoast) divided by alternative drag area (CDAalt):

Falt-aero = CDAcoast ÷ CDAalt

(3) Calculate Falt-aero to at least three decimal places. For example, if your coastdown 

testing results in a drag area of 6.430, but your wind tunnel method results in a drag 

area of 6.200, Falt-aero would be 1.037.

(b) Recommended method. Perform coastdown testing as described in 40 CFR part 

1066, subpart D, subject to the following additional provisions:

(1) The specifications of this paragraph (b)(1) apply when measuring drag areas for 

tractors. Test high-roof tractors with a standard box trailer. Test low- and mid-roof 

tractors without a trailer (sometimes referred to as in a “bobtail configuration”). You 

may test low- and mid-roof tractors with a trailer to evaluate innovative technologies.

(2) The specifications of this paragraph (b)(2) apply for tractors and standard trailers. 

Use tires mounted on steel rims in a dual configuration (except for steer tires). The 

tires must–

(i) Be SmartWay-Verified tires or have a rolling resistance below 5.1 kg/ton.

(ii) Have accumulated at least 2,175 miles of prior use but have no less than 50 

percent of their original tread depth (as specified for truck cabs in SAE J1263).

(iii) Not be retreads or have any apparent signs of chunking or uneven wear.

(iv) Be size 295/75R22.5 or 275/80R22.5.

(3) Calculate the drag area (CDA) in m2from the coastdown procedure specified in 40 

CFR part 1066.
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(c) Approval. You must obtain preliminary approval before using any methods other 

than coastdown testing to determine drag coefficients. Send your request for approval to 

the Designated Compliance Officer. Keep records of the information specified in this 

paragraph (c). Unless we specify otherwise, include this information with your request. 

You must provide any information we require to evaluate whether you are apply the 

provisions of this section consistent with good engineering judgment. 

(1) Include all of the following for your coastdown results:

(i) The name, location, and description of your test facilities, including 

background/history, equipment and capability, and track and facility elevation, 

along with the grade and size/length of the track.

(ii) Test conditions for each test result, including date and time, wind speed and 

direction, ambient temperature and humidity, vehicle speed, driving distance, 

manufacturer name, test vehicle/model type, model year, applicable model engine 

family, tire type and rolling resistance, weight of tractor-trailer (as tested), and 

driver identifier(s).

(iii) Average drag area result as calculated in 40 CFR 1066, subpart D) and all of 

the individual run results (including voided or invalid runs). 

(2) Identify the name and location of the test facilities for your wind tunnel method (if 

applicable). Also include the following things to describe the test facility:

(i) Background/history.

(ii) The layout (with diagram), type, and construction (structural and material) of 

the wind tunnel.

(iii) Wind tunnel design details: corner turning vane type and material, air 

settling, mesh screen specification, air straightening method, tunnel volume, 

surface area, average duct area, and circuit length.

(iv) Wind tunnel flow quality: temperature control and uniformity, airflow 

quality, minimum airflow velocity, flow uniformity, angularity and stability, static 

pressure variation, turbulence intensity, airflow acceleration and deceleration 

times, test duration flow quality, and overall airflow quality achievement.

(v) Test/working section information: test section type (e.g., open, closed, 

adaptive wall) and shape (e.g., circular, square, oval), length, contraction ratio, 

maximum air velocity, maximum dynamic pressure, nozzle width and height, 

plenum dimensions and net volume, maximum allowed model scale, maximum 

model height above road, strut movement rate (if applicable), model support, 

primary boundary layer slot, boundary layer elimination method, and photos and 

diagrams of the test section.
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(vi) Fan section description: fan type, diameter, power, maximum rotational 

speed, maximum top speed, support type, mechanical drive, and sectional total 

weight.

(vii) Data acquisition and control (where applicable): acquisition type, motor 

control, tunnel control, model balance, model pressure measurement, wheel drag 

balances, wing/body panel balances, and model exhaust simulation.

(viii) Moving ground plane or rolling road (if applicable): construction and 

material, yaw table and range, moving ground length and width, belt type, 

maximum belt speed, belt suction mechanism, platen instrumentation, 

temperature control, and steering.

(ix) Facility correction factors and purpose. 

(3) Include all of the following for your computational fluid dynamics (CFD) method 

(if applicable):

(i) Official name/title of the software product.

(ii) Date and version number for the software product.

(iii) Manufacturer/company name, address, phone number and web address for 

software product.

(iv) Identify if the software code is Navier-Stokes or Lattice-Boltzmann based.

(4) Include all of the following for any other method (if applicable):

(i) Official name/title of the procedure(s).

(ii) Description of the procedure.

(iii) Cited sources for any standardized procedures that the method is based on.

(iv) Modifications/deviations from the standardized procedures for the method 

and rational for modifications/deviations.

(v) Data comparing this requested procedure to the coastdown reference 

procedure.

(vi) Information above from the other methods as applicable to this method (e.g., 

source location/address, background/history).

(d) Wind tunnel methods. (1) You may measure drag areas consistent with the 

modified SAE procedures described in the paragraph (d) using any wind tunnel 

recognized by the Subsonic Aerodynamic Testing Association. If your wind tunnel is 

not capable of testing in accordance with these modified SAE procedures, you may

ask us to approve your alternate test procedures if you demonstrate that your 
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procedures produce equivalent data. For purposes of this paragraph (d), data are 

equivalent if they are the same or better with respect to repeatability and unbiased 

correlation with coastdown testing. Note that, for wind tunnels not capable of these 

modified SAE procedures, good engineering judgment may require you to base your 

alternate method adjustment factor on more than one vehicle. You may not develop 

your correction factor until we have approved your alternate method. The applicable 

SAE procedures are SAE J1252, SAE J1594, and SAE J2071(incorporated by

reference in §1037.810). The following modifications apply for SAE J1252: 

(i) The minimum Reynold's number (Remin) is 1.0 x 106instead of the value 

specified in section 5.2 of the SAE procedure. Your model frontal area at zero 

yaw angle may exceed the recommended 5 percent of the active test section area, 

provided it does not exceed 25 percent.

(ii) For full-scale wind tunnel testing, use good engineering judgment to select a 

test article (tractor and trailer) that is a reasonable representation of the test article 

used for the reference method testing. For example, where your wind tunnel is 

not long enough to test the tractor with a standard 53 foot trailer, it may be 

appropriate to use shorter box trailer. In such a case, the correlation developed 

using the shorter trailer would only be valid for testing with the shorter trailer.

(iii) For reduced-scale wind tunnel testing, a one-eighth (1/8th) or larger scale 

model of a heavy-duty tractor and trailer must be used, and the model must be of 

sufficient design to simulate airflow through the radiator inlet grill and across an 

engine geometry representative of those commonly used in your test vehicle.

(2) You must perform wind tunnel testing and the coastdown procedure on the same 

tractor model and provide the results for both methods. Conduct the wind tunnel tests 

at a zero yaw angle and, if so equipped, utilizing the moving/rolling floor (i.e., the 

moving/rolling floor should be on during the test, as opposed to static) for comparison 

to the coastdown procedure, which corrects to a zero yaw angle for the oncoming 

wind. 

(e) Computational fluid dynamics (CFD). You may determine drag areas using a CFD 

method, consistent with good engineering judgment and the requirements of this 

paragraph (e) using commercially available CFD software code. Conduct the analysis 

assuming zero yaw angle, and ambient conditions consistent with coastdown procedures. 

For simulating a wind tunnel test, the analysis should accurately model the particular 

wind tunnel and assume a wind tunnel blockage ratio consistent with SAE J1252 

(incorporated by reference in §1037.810) or one that matches the selected wind tunnel, 

whichever is lower. For simulation of open road conditions similar to that experienced 

during coastdown test procedures, the CFD analysis should assume a blockage ratio at or 

below 0.2 percent. 

(1) Take the following steps for CFD code with a Navier-Stokes formula solver:
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(i) Perform an unstructured, time-accurate, analysis using a mesh grid size with 

total volume element count of at least 50 million cells of hexahedral and/or 

polyhedral mesh cell shape, surface elements representing the geometry

consisting of no less than 6 million elements, and a near-wall cell size 

corresponding to a y+ value of less than 300, with the smallest cell sizes applied 

to local regions of the tractor and trailer in areas of high flow gradients and 

smaller geometry features. 

(ii) Perform the analysis with a turbulence model and mesh deformation enabled 

(if applicable) with boundary layer resolution of ±95 percent. Once result 

convergence is achieved, demonstrate the convergence by supplying multiple, 

successive convergence values for the analysis. The turbulence model may use kepsilon (k-ε), shear stress transport k-omega (SST k-ω), or other commercially

accepted methods.

(2) For Lattice-Boltzman based CFD code, perform an unstructured, time-accurate 

analysis using a mesh grid size with total surface elements of at least 50 million cells 

using cubic volume elements and triangular and/or quadrilateral surface elements 

with a near wall cell size of no greater than 6 mm on local regions of the tractor and 

trailer in areas of high flow gradients and smaller geometry features, with cell sizes in 

other areas of the mesh grid starting at twelve millimeters and increasing in size from 

this value as the distance from the tractor-trailer model increases. 

(3) All CFD analysis should be conducted using the following conditions: 

(i) A tractor-trailer combination using the manufacturer’s tractor and the standard 

trailer, as applicable.

(ii) An environment with a blockage ratio at or below 0.2 percent to simulate open 

road conditions, a zero degree yaw angle between the oncoming wind and the 

tractor-trailer combination.

(iii) Ambient conditions consistent with the coastdown test procedures specified 

in this part.

(iv) Open grill with representative back pressures based on data from the tractor 

model,

(v) Turbulence model and mesh deformation enabled (if applicable). 

(vi) Tires and ground plane in motion consistent with and simulating a vehicle 

moving in the forward direction of travel.

(vii) The smallest cell size should be applied to local regions on the tractor and 

trailer in areas of high flow gradients and smaller geometry features (e.g., the apillar, mirror, visor, grille and accessories, trailer leading and trailing edges, rear 

bogey, tires, and tractor-trailer gap).

(viii) Simulate a speed of 55 mph. 

(4) You may ask us to allow you to perform CFD analysis using parameters and 

criteria other than those specified in this paragraph (e), consistent with good 

engineering judgment, if you can demonstrate that the specified conditions are not 

feasible (e.g., insufficient computing power to conduct such analysis, inordinate 

length of time to conduct analysis, equivalent flow characteristics with more feasible 

criteria/parameters) or improved criteria may yield better results (e.g., different mesh 

cell shape and size). To support this request, we may require that you supply data 

demonstrating that your selected parameters/criteria will provide a sufficient level of 
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detail to yield an accurate analysis, including comparison of key characteristics 

between your criteria/parameters and the criteria specified in paragraphs (e)(1) and 

(2) of this section (e.g., pressure profiles, drag build-up, and/or turbulent/laminar flow 

at key points on the front of the tractor and/or over the length of the tractor-trailer 

combination).

(f) Yaw sweep corrections. You may optionally apply this paragraph (f) for vehicles with 

aerodynamic features that are more effective at reducing wind-averaged drag than is 

predicted by zero-yaw drag. You may correct your zero-yaw drag area as follows if the 

ratio of the zero-yaw drag area divided by yaw sweep drag area for your vehicle is greater 

than 0.8065 (which represents the ratio expected for a typical aerodynamic Class 8 highroof sleeper cab tractor):

(1) Determine the zero-yaw drag area and the yaw sweep drag area for your vehicle 

using the same alternate method as specified in this subpart. Measure drag area for 

0°, -6°, and +6°. Use the arithmetic mean of the -6° and +6° drag areas as the ±6° 

drag area.

(2) Calculate your yaw sweep correction factor (CFys) using the following equation:

 =

(±°  ) × . 

(   )

(3) Calculate your corrected drag area for determining the aerodynamic bin by 

multiplying the measured zero-yaw drag area by CFys. The correction factor may be 

applied to drag areas measured using other procedures. For example, we would apply

CFys to drag areas measured using the recommended coastdown method. If you use 

an alternative method, you would also need to apply an alternative correction (Falt-aero) 

and calculate the final drag area using the following equation:

CDA = Falt-aero · CFys · (CDA)zero-alt

(4) You may ask us to apply CFys to similar vehicles incorporating the same design 

features.

(5) As an alternative, you may choose to calculate the wind-averaged drag area 

according to SAE J1252 (incorporated by reference in §1037.810) and substitute this 

value into the equation in paragraph (f)(2) of this section for the ±6° yaw-averaged 

drag area.

§1037.525 Special procedures for testing hybrid vehicles with power take-off. 

This section describes the procedure for quantifying the reduction in greenhouse gas 

emissions as a result of running power take-off (PTO) devices with a hybrid powertrain. 

The procedures are written to test the PTO so that all the energy is produced with the 

engine. The full test for the hybrid vehicle is from a fully charged renewable energy

storage system (RESS) to a depleted RESS and then back to a fully charged RESS. 

These procedures may be used for whole vehicles or with a post-transmission hybrid 

system. When testing just the post-transmission hybrid system, you must include all 
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hardware for the PTO system. You may ask us to modify the provisions of this section to 

allow testing hybrid vehicles other than electric-battery hybrids, consistent with good 

engineering judgment.

(a) Select two vehicles for testing as follows:

(1) Select a vehicle with a hybrid powertrain to represent the vehicle family. If your 

vehicle family includes more than one vehicle model, use good engineering judgment 

to select the vehicle type with the maximum number of PTO circuits that has the 

smallest potential reduction in greenhouse gas emissions.

(2) Select an equivalent conventional vehicle as specified in §1037.615.

(b) Measure PTO emissions from the fully warmed-up conventional vehicle as follows:

(1) Without adding any additional restrictions, instrument the vehicle with pressure 

transducers at the outlet of the hydraulic pump for each circuit.

(2) Operate the PTO system with no load for at least 15 seconds. Measure the 

pressure and record the average value over the last 10 seconds (pmin). Apply 

maximum operator demand to the PTO system until the pressure relief valve opens 

and pressure stabilizes; measure the pressure and record the average value over the 

last 10 seconds (pmax). 

(3) Denormalize the PTO duty cycle in Appendix II of this part using the following 

equation: 

refi i m  ax min m  in p N  P p   p p

Where:

prefi = the reference pressure at each point i in the PTO cycle.

NPi= the normalized pressure at each point i in the PTO cycle.

pmax= the maximum pressure measured in paragraph (b)(2) of this section.

pmin= the minimum pressure measured in paragraph (b)(2) of this section.

(4) If the PTO system has two circuits, repeat paragraph (b)(2) and (3) of this section 

for the second PTO circuit.

(5) Install a system to control pressures in the PTO system during the cycle.

(6) Start the engine.
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(7) Operate the vehicle over one or both of the denormalized PTO duty cycles, as 

applicable. Collect CO2 emissions during operation over each duty cycle.

(8) Use the provisions of 40 CFR part 1066 to collect and measure emissions. 

Calculate emission rates in grams per test without rounding.

(9) For each test, validate the pressure in each circuit with the pressure specified from 

the cycle according to 40 CFR 1065.514. Measured pressures must meet the 

specifications in the following table for a valid test:

Table 1 of §1037.525 – Statistical criteria for validating duty cycles

Parameter Pressure

Slope, a1 0.950 < a1 < 1.030

Absolute value of intercept, |a0| < 2.0 % of maximum mapped pressure

Standard error of estimate, SEE < 10 % of maximum mapped pressure

Coefficient of determination, r

2

> 0.970

(10) Continue testing over the three vehicle drive cycles, as otherwise required by this 

part.

(11) Calculate combined cycle-weighted emissions of the four cycles as specified in 

paragraph (d) of this section.

(c) Measure PTO emissions from the fully warmed-up hybrid vehicle as follows:

(1) Perform the steps in paragraphs (b)(1) through (5) of this section.

(2) Prepare the vehicle for testing by operating it as needed to stabilize the battery at a 

full state of charge. For electric hybrid vehicles, we recommend running back-toback PTO tests until engine operation is initiated to charge the battery. The battery

should be fully charged once engine operation stops. The ignition should remain in 

the “on” position. 

(3) Turn the vehicle and PTO system off while the sampling system is being 

prepared. 

(4) Turn the vehicle and PTO system on such that the PTO system is functional, 

whether it draws power from the engine or a battery. 

(5) Operate the vehicle over the PTO cycle(s) without turning the vehicle off, until 

the engine starts and then shuts down. The test cycle is completed once the engine 

shuts down. Measure emissions as described in paragraphs (b)(2) and (3) of this 

section. Use good engineering judgment to minimize the variability in testing 

between the two types of vehicles. 
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(6) Refer to paragraph (b)(9) of this section for cycle validation.

(7) Continue testing over the three vehicle drive cycles, as otherwise required by this 

part.

(8) Calculate combined cycle-weighted emissions of the four cycles as specified in 

paragraph (d) of this section.

(d) Calculate combined cycle-weighted emissions of the four cycles for vocational 

vehicles as follows:

(1) Calculate the g/ton-mile emission rate for the driving portion of the test specified 

in §1037.510.

(2) Calculate the g/hr emission rate for the PTO portion of the test by dividing the 

total mass emitted over the cycle (grams) by the time of the test (hours). For testing 

where fractions of a cycle were run (for example, where three cycles are completed 

and the halfway point of a fourth PTO cycle is reached before the engine starts and 

shuts down again), use the following procedures to calculate the time of the test: 

(i) Add up the time run for all complete tests.

(ii) For fractions of a test, use the following equation to calculate the time:

 

 

circuit_1,i circuit_2,i

1

cycle

circuit_1,i circuit_2,i

1

N

i

test N

i

NP NP t

t t

NP NP t





 

 

 





Where:

ttest = time of the incomplete test.

i = the number of each measurement interval.

N = the total number of measurement intervals.

NPcircuit_1 = Normalized pressure command from circuit 1 of the PTO cycle.

NPcircuit_2 = Normalized pressure command from circuit 2 of the PTO cycle. Let 

NPcircuit_2=1 if there is only one circuit.

tcycle = time of a complete cycle.

(iii) Sum the time from complete cycles (paragraph (d)(2)(i) of this section) and 

from partial cycles (paragraph (d)(2)(ii) of this section).
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(3) Convert the g/hr PTO result to an equivalent g/mi value based on the assumed 

fraction of engine operating time during which the PTO is operating (28 percent) and 

an assumed average vehicle speed while driving (27.1 mph). The conversion factor 

is: Factor = (0.280)/(1.000-0.280)/(27.1 mph) = 0.0144 hr/mi. Multiply the g/hr 

emission rate by 0.0144 hr/mi. 

(4) Divide the g/mi PTO emission rate by the standard payload and add this value to 

the g/ton-mile emission rate for the driving portion of the test.

(e) Follow the provisions of §1037.615 to calculate improvement factors and benefits for 

advanced technologies.

§1037.550 Special procedures for testing post-transmission hybrid systems. 

This section describes the procedure for simulating a chassis test with a post-transmission 

hybrid system for A to B testing. The hardware that must be included in these tests is the 

engine, the transmission, the hybrid electric motor, the power electronics between the 

hybrid electric motor and the RESS, and the RESS. You may ask us to modify the 

provisions of this section to allow testing non-electric hybrid vehicles, consistent with 

good engineering judgment.

(a) Set up the engine according to 40 CFR 1065.110 to account for work inputs and 

outputs and accessory work.

(b) Collect CO2 emissions while operating the system over the test cycles specified in 

§1037.510.

(c) Collect and measure emissions as described in 40 CFR part 1066. Calculate emission 

rates in grams per ton-mile without rounding. Determine values for A, B, C, and M for 

the vehicle being simulated as specified in 40 CFR part 1066. If you will apply an 

improvement factor or test results to multiple vehicle configurations, use values of A, B, 

C, M, kd, and r that represent the vehicle configuration with the smallest potential 

reduction in greenhouse gas emissions as a result of the hybrid capability. 

(d) Calculate the transmission output shaft’s angular speed target for the driver model, 

fnref,driver, from the linear speed associated with the vehicle cycle using the following 

equation:

, d

nrefi,driver 2

S k i cycle f

 r





 

Where:

Scyclei = vehicle speed of the test cycle for each point i.
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kd = final drive ratio (the angular speed of the transmission output shaft divided by the 

angular speed of the drive axle), as declared by the manufacturer.

r = radius of the loaded tires, as declared by the manufacturer.

(e) Use either speed control or torque control to program the dynamometer to follow the 

test cycle, as follows: 

(1) Speed control. Program dynamometers using speed control as described in this 

paragraph (e)(1). We recommend speed control for automated manual transmissions 

or other designs where there is a power interrupt during shifts. Calculate the 

transmission output shaft’s angular speed target for the dynamometer, fnref,dyno, from 

the measured linear speed at the dynamometer rolls using the following equation:

i,ref d

nrefi,dyno 2

S k

f

 r





 

Where:

  

2 i i-1

i,ref meas,i i i i,ref-1

t t S FR A B S C S S

M



      

t = elapsed time in the driving schedule as measured by the dynamometer, in seconds. 

Let ti-1 = 0.

d i

meas,i

k T FR

r





n,i

i

d

2 r f

S

k

   



Where:

Ti = instantaneous measured torque at the transmission output shaft.

fn,i = instantaneous measured angular speed of the transmission output shaft.

(2) Torque control. Program dynamometers using torque control as described in this 

paragraph (e)(2). 

(i) Calculate the transmission output shaft’s torque target, Trefi, using the 

following equation:
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i

ref,i

d

r FR

T

k





Where:

FRi = total road load force at the surface of the roll, calculated using the equation 

in 40 CFR 1066.210(d)(4), as specified in paragraph (e)(2)(ii) of this section.

(ii) Calculate the total road load force based on instantaneous speed values, Si, 

calculated from the equation in paragraph (e)(1) of this section.

(3) For each test, validate the measured transmission output shaft’s speed or torque 

with the corresponding reference values according to 40 CFR 1065.514(e). You may 

delete points when the vehicle is braking or stopped. Perform the validation based on 

speed and torque values at the transmission output shaft. For steady-state tests (55 

mph and 65 mph cruise), apply cycle-validation criteria by treating the sampling 

periods from the two tests as a continuous sampling period. Perform this validation 

based on the following parameters for either speed-control or torque-control, as 

applicable:

Table 1 of §1037.550 – Statistical criteria for validating duty cycles

Parameter Speed Control Torque Control

Slope, a1 0.950 < a1 < 1.030 0.950 < a1 < 1.030

Absolute value of intercept, 

|a0|

< 2.0 % of maximum test 

speed

< 2.0 % of maximum 

torque

Standard error of estimate, 

SEE

< 5 % of maximum test 

speed < 10 % of maximum torque

Coefficient of 

determination, r

2 > 0.970 > 0.850

(f) Send a brake signal when throttle position is equal to zero and vehicle speed is greater 

than the reference vehicle speed from the test cycle. The brake signal should be turned 

off when the torque measured at the transmission output shaft is less than the reference 

torque. Set a delay before changing the brake state using good engineering judgment to 

prevent the brake signal from dithering.
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(g) The driver model should be designed to follow the cycle as closely as possible and 

must meet the requirements of 40 CFR 1066.430 (e) for transient testing and §1037.510 

for steady-state testing.

(h) Correct for the net energy change of the energy storage device as described in 40 CFR 

1066.501.

(i) Follow the provisions of §1037.510 to weight the cycle results and §1037.615 to 

calculate improvement factors and benefits for advanced technologies.

Subpart G—Special Compliance Provisions

§ 1037.601 What compliance provisions apply to these vehicles?

(a) Engine and vehicle manufacturers, as well as owners and operators of vehicles subject 

to the requirements of this part, and all other persons, must observe the provisions of this 

part, the provisions of the Clean Air Act, and the following provisions of 40 CFR part 

1068:

(1) The exemption and importation provisions of 40 CFR part 1068, subparts C and 

D, apply for vehicles subject to this part 1037, except that the hardship exemption 

provisions of 40 CFR 1068.245, 1068.250, and 1068.255 do not apply for motor 

vehicles.

(2) Manufacturers may comply with the defect reporting requirements of 40 CFR 

1068.501 instead of the defect reporting requirements of 40 CFR part 85.

(b) Vehicles exempted from the applicable standards of 40 CFR part 86 are exempt from 

the standards of this part without request. Similarly, vehicles are exempt without request 

if the installed engine is exempted from the applicable standards in 40 CFR part 86.

(c) The prohibitions of 40 CFR 86.1854 apply for vehicles subject to the requirements of 

this part. The actions prohibited under this provision include the introduction into U.S. 

commerce of a complete or incomplete vehicle subject to the standards of this part where 

the vehicle is not covered by a valid certificate of conformity or exemption.

(d) Except as specifically allowed by this part, it is a violation of section 203(a)(1) of the 

Clean Air Act (42 U.S.C. 7522(a)(1)) to introduce into U.S. commerce a tractor 

containing an engine not certified for use in tractors; or to introduce into U.S. commerce 

a vocational vehicle containing a light heavy-duty or medium heavy-duty engine not 

certified for use in vocational vehicles. This prohibition applies especially to the vehicle 

manufacturer.
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(e) A vehicle manufacturer that completes assembly of a vehicle at two or more facilities 

may ask to use as the date of manufacture for that vehicle the date on which 

manufacturing is completed at the place of main assembly, consistent with provisions of 

49 CFR 567.4. Note that such staged assembly is subject to the provisions of 40 CFR 

1068.260(c). Include your request in your application for certification, along with a 

summary of your staged-assembly process. You may ask to apply this allowance to some

or all of the vehicles in your vehicle family. Our approval is effective when we grant 

your certificate. We will not approve your request if we determine that you intend to use 

this allowance to circumvent the intent of this part. 

 

§ 1037.610 Vehicles with innovative technologies.

(a) You may ask us to apply the provisions of this section for CO2 emission reductions 

resulting from vehicle technologies that were not in common use with heavy-duty 

vehicles before model year 2010 that are not reflected in the GEM simulation tool. These 

provisions may be applied for CO2 emission reductions reflected using the specified test 

procedures, provided they are not reflected in the GEM. We will apply these provisions 

only for technologies that will result in measurable, demonstrable, and verifiable realworld CO2 emission reductions. 

(b) The provisions of this section may be applied as either an improvement factor or as a 

separate credit, consistent with good engineering judgment. We recommend that you 

base your credit/adjustment on A to B testing of pairs of vehicles differing only with 

respect to the technology in question. 

(1) Calculate improvement factors as the ratio of in-use emissions with the 

technology divided by the in-use emissions without the technology. Use the 

improvement-factor approach where good engineering judgment indicates that the 

actual benefit will be proportional to emissions measured over the test procedures 

specified in this part. 

(2) Calculate separate credits (g/ton-mile) based on the difference between the in-use 

emission rate with the technology and the in-use emission rate without the 

technology. Multiply this difference by the number of vehicles, standard payload, 

and useful life. Use the separate-credit approach where good engineering judgment 

indicates that the actual benefit will be not be proportional to emissions measured 

over the test procedures specified in this part.

(3) We may require you to discount or otherwise adjust your improvement factor or 

credit to account for uncertainty or other relevant factors.

(c) You may perform A to B testing by measuring emissions from the vehicles during 

chassis testing or from in-use on-road testing. We recommend that you perform on-road 

testing according to SAE J1321 Joint TMC/SAE Fuel Consumption Test Procedure Type 

II Reaffirmed 1986-10 or SAE J1526 Joint TMC/SAE Fuel Consumption In-Service Test 

Procedure Type III Issued 1987-06 (see §1037.810 for information availability of SAE 
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standards), subject to the following provisions:

(1) The minimum route distance is 100 miles. 

(2) The route selected must be representative in terms of grade. We will take into 

account published and relevant research in determining whether the grade is 

representative. 

(3) The vehicle speed over the route must be representative of the drive-cycle 

weighting adopted for each regulatory subcategory. For example, if the route selected 

for an evaluation of a combination tractor with a sleeper cab contains only interstate 

driving, the improvement factor would apply only to 86 percent of the weighted 

result. 

(4) The ambient air temperature must be between 5 and 35°C, unless the technology

requires other temperatures for demonstration. 

(5) We may allow you to use a Portable Emissions Measurement System (PEMS) 

device for measuring CO2 emissions during the on-road testing.

(d) Send your request to the Designated Compliance Officer. Include a detailed 

description of the technology and a recommended test plan. Also state whether you 

recommend applying these provisions using the improvement-factor method or the 

separate-credit method. We recommend that you do not begin collecting test data (for 

submission to EPA) before contacting us. For technologies for which the engine 

manufacturer could also claim credits (such as transmissions in certain circumstances), 

we may require you to include a letter from the engine manufacturer stating that it will 

not seek credits for the same technology.

(e) We may seek public comment on your request, consistent with the provisions of 40 

CFR 86.1866. However, we will generally not seek public comment on credits or 

adjustments based on A to B chassis testing performed according to the duty-cycle testing 

requirements of this part or in-use testing performed according to paragraph (c) of this 

section.

§ 1037.615 Hybrid vehicles and other advanced technologies.

(a) This section applies for hybrid vehicles with regenerative braking, vehicles equipped 

with Rankine-cycle engines, electric vehicles, and fuel cell vehicles. You may not 

generate credits for engine features for which the engines generate credits under 40 CFR 

part 1036. 

(b) Generate advanced technology emission credits for hybrid vehicles that include 

regenerative braking (or the equivalent) and energy storage systems, fuel cell vehicles, 

and vehicles equipped with Rankine-cycle engines as follows: 
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(1) Measure the effectiveness of the advanced system by chassis testing a vehicle 

equipped with the advanced system and an equivalent conventional vehicle. Test the 

vehicles as specified in subpart F of this part. For purposes of this paragraph (b), a 

conventional vehicle is considered to be equivalent if it has the same footprint (as 

defined in 40 CFR 86.1803), vehicle service class, aerodynamic drag, and other 

relevant factors not directly related to the hybrid powertrain. If you use § 1037.525 to 

quantify the benefits of a hybrid system for PTO operation, the conventional vehicle 

must have same number of PTO circuits and have equivalent PTO power. If you do 

not produce an equivalent vehicle, you may create and test a prototype equivalent 

vehicle. The conventional vehicle is considered Vehicle A and the advanced vehicle 

is considered Vehicle B. We may specify an alternate cycle if your vehicle includes a 

power take-off.

(2) Calculate an improvement factor and g/ton-mile benefit using the following 

equations and parameters:

(i) Improvement Factor = [(Emission Rate A) – (Emission Rate B)]/(Emission 

Rate A)

(ii) g/ton-mile benefit = Improvement Factor × (GEM Result B)

(iii) Emission Rates A and B are the g/ton-mile CO2 emission rates of the 

conventional and advanced vehicles, respectively, as measured under the test 

procedures specified in this section. GEM Result B is the g/ton-mile CO2

emission rate resulting from emission modeling of the advanced vehicle as 

specified in § 1037.520.

(3) Use the equations of § 1037.705 to convert the g/ton-mile benefit to emission 

credits (in Mg). Use the g/ton-mile benefit in place of the (Std-FEL) term. 

(c) See § 1037.525 for special testing provisions related to hybrid vehicles equipped with 

power take-off units.

(d) You may use an engineering analysis to calculate an improvement factor for fuel cell 

vehicles based on measured emissions from the fuel cell vehicle.

(e) For electric vehicles, calculate CO2 credits using an FEL of 0 g/ton-mile.

(f) As specified in subpart H of this part, credits generated under this section may be used 

under this part 1037 outside of the averaging set in which they were generated or used 

under 40 CFR part 1036. 

(g) You may certify using both provisions of this section and the innovative technology

provisions of §1037.610, provided you do not double count emission benefits. 

§ 1037.620 Shipment of incomplete vehicles to secondary vehicle manufacturers.
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This section specifies how manufacturers may introduce partially complete vehicles into 

U.S. commerce.

(a) The provisions of this section allow manufacturers to ship partially complete vehicles 

to secondary vehicle manufacturers or otherwise introduce them into U.S. commerce in 

the following circumstances:

(1) Tractors. Manufacturers may introduce partially complete tractors into U.S. 

commerce if they are covered by a certificate of conformity for tractors and will be in 

their certified tractor configuration before they reach the ultimate purchasers. For 

example, this would apply for sleepers initially shipped without the sleeper 

compartments attached. Note that delegated assembly provisions may apply (see 40 

CFR 1068.261).

(2) Vocational vehicles. Manufacturers may introduce partially complete vocational 

vehicles into U.S. commerce if they are covered by a certificate of conformity for 

vocational vehicles and will be in their certified vocational configuration before they

reach the ultimate purchasers. Note that delegated assembly provisions may apply 

(see 40 CFR 1068.261).

(3) Uncertified vehicles that will be certified by secondary vehicle manufacturers. 

Manufacturers may introduce into U.S. commerce partially complete vehicles for 

which they do not hold a certificate of conformity only as allowed by paragraph (b) of 

this section.

(b) The provisions of this paragraph (b) generally apply where the secondary vehicle 

manufacturer has substantial control over the design and assembly of emission controls. 

In determining whether a manufacturer has substantial control over the design and 

assembly of emission controls, we would consider the degree to which the secondary

manufacturer would be able to ensure that the engine and vehicle will conform to the 

regulations in their final configurations. 

(1) A secondary manufacturer may finish assembly of partially complete vehicles in 

the following cases:

(i) It obtains a vehicle that is not fully assembled with the intent to manufacture a 

complete vehicle in a certified configuration.

(ii) It obtains a vehicle with the intent to modify it to a certified configuration 

before it reaches the ultimate purchaser. For example, this may apply for 

converting a gasoline-fueled vehicle to operate on natural gas under the terms of a 

valid certificate.

(2) Manufacturers may introduce partially complete vehicles into U.S. commerce as 

described in this paragraph (b) if they have a written request for such vehicles from a 

secondary vehicle manufacturer that will finish the vehicle assembly and has certified 

the vehicle. (or the vehicle has been exempted or excluded from the requirements of 

this part). The written request must include a statement that the secondary
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manufacturer has a certificate of conformity (or exemption/exclusion) for the vehicle 

and identify a valid vehicle family name associated with each vehicle model ordered 

(or the basis for an exemption/exclusion). The original vehicle manufacturer must 

apply a removable label meeting the requirements of 40 CFR 1068.45 that identifies 

the corporate name of the original manufacturer and states that the vehicle is exempt 

under the provisions of § 1037.620. The name of the certifying manufacturer must 

also be on the label or, alternatively, on the bill of lading that accompanies the 

vehicles during shipment. The original manufacturer may not apply a permanent 

emission control information label identifying the vehicle's eventual status as a 

certified vehicle.

(3) If you are the secondary manufacturer and you will hold the certificate, you must 

include the following information in your application for certification:

(i) Identify the original manufacturer of the partially complete vehicle or of the 

complete vehicle you will modify.

(ii) Describe briefly how and where final assembly will be completed. Specify

how you have the ability to ensure that the vehicles will conform to the 

regulations in their final configuration. (Note: This section prohibits using the 

provisions of this paragraph (b) unless you have substantial control over the 

design and assembly of emission controls.)

(iii) State unconditionally that you will not distribute the vehicles without 

conforming to all applicable regulations.

(4) If you are a secondary manufacturer and you are already a certificate holder for 

other families, you may receive shipment of partially complete vehicles after you 

apply for a certificate of conformity but before the certificate's effective date. This 

exemption allows the original manufacturer to ship vehicles after you have applied 

for a certificate of conformity. Manufacturers may introduce partially complete 

vehicles into U.S. commerce as described in this paragraph (b)(4) if they have a 

written request for such vehicles from a secondary manufacturer stating that the 

application for certification has been submitted (instead of the information we specify

in paragraph (b)(2) of this section). We may set additional conditions under this 

paragraph (b)(4) to prevent circumvention of regulatory requirements. 

(5) Both original and secondary manufacturers must keep the records described in this 

section for at least five years, including the written request for exempted vehicles and 

the bill of lading for each shipment (if applicable). The written request is deemed to 

be a submission to EPA.

(6) These provisions are intended only to allow secondary manufacturers to obtain or 

transport vehicles in the specific circumstances identified in this section so any

exemption under this section expires when the vehicle reaches the point of final 

assembly identified in paragraph (b)(3)(ii) of this section.
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(7) For purposes of this section, an allowance to introduce partially complete vehicles 

into U.S. commerce includes a conditional allowance to sell, introduce, or deliver 

such vehicles into commerce in the United States or import them into the United 

States. It does not include a general allowance to offer such vehicles for sale because 

this exemption is intended to apply only for cases in which the certificate holder 

already has an arrangement to purchase the vehicles from the original manufacturer. 

This exemption does not allow the original manufacturer to subsequently offer the 

vehicles for sale to a different manufacturer who will hold the certificate unless that 

second manufacturer has also complied with the requirements of this part. The 

exemption does not apply for any individual vehicles that are not labeled as specified 

in this section or which are shipped to someone who is not a certificate holder.

(8) We may suspend, revoke, or void an exemption under this section, as follows:

(i) We may suspend or revoke your exemption if you fail to meet the requirements 

of this section. We may suspend or revoke an exemption related to a specific 

secondary manufacturer if that manufacturer sells vehicles that are in not in a 

certified configuration in violation of the regulations. We may disallow this 

exemption for future shipments to the affected secondary manufacturer or set 

additional conditions to ensure that vehicles will be assembled in the certified

configuration.

(ii) We may void an exemption for all the affected vehicles if you intentionally

submit false or incomplete information or fail to keep and provide to EPA the 

records required by this section.

(iii) The exemption is void for a vehicle that is shipped to a company that is not a 

certificate holder or for a vehicle that is shipped to a secondary manufacturer that 

is not in compliance with the requirements of this section.

(iv) The secondary manufacturer may be liable for penalties for causing a

prohibited act where the exemption is voided due to actions on the part of the 

secondary manufacturer.

(d) Provide instructions along with partially complete vehicles including all information 

necessary to ensure that an engine will be installed in its certified configuration. 

§1037.630 Special purpose tractors.

(a) General provisions. This section allows a vehicle manufacturer to reclassify certain 

tractors as vocational tractors. Vocational tractors are treated as vocational vehicles and 

are exempt from the standards of §1037.106. Note that references to “tractors” outside of 

this section mean non-vocational tractors.

(1) This allowance is intended only for vehicles that do not typically operate at 

highway speeds, or would otherwise not benefit from efficiency improvements 
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designed for line-haul tractors. This allowance is limited to the following vehicle and 

application types:

(i) Low-roof tractors intended for intra-city pickup and delivery, such as those 

that deliver bottled beverages to retail stores.

(ii) Tractors intended for off-road operation (including mixed service operation), 

such as those with reinforced frames and increased ground clearance. 

(iii) Tractors with a GCWR over 120,000 pounds.

(2) Where we determine that a manufacturer is not applying this allowance in good 

faith, we may require the manufacturer to obtain preliminary approval before using 

this allowance. 

(b) Requirements. The following requirements apply with respect to tractors reclassified 

under this section:

(1) The vehicle must fully conform to all requirements applicable to vocational 

vehicles under this part. 

(2) Vehicles reclassified under this section must be certified as a separate vehicle 

family. However, they remain part of the vocational regulatory sub-category and 

averaging set that applies for their weight class.

(3) You must include the following additional statement on the vehicle’s emission 

control information label under §1037.135: “THIS VEHICLE WAS CERTIFIED AS 

A VOCATIONAL TRACTOR UNDER 40 CFR 1037.630.”.

(4) You must keep records for three years to document your basis for believing the 

vehicles will be used as described in paragraph (a)(1) of this section. Include in your 

application for certification a brief description of your basis.

(c) Production limit. No manufacturer may produce more than 21,000 vehicles under this 

section in any consecutive three model year period. This means you may not exceed 

6,000 in a given model year if the combined total for the previous two years was 15,000. 

The production limit applies with respect to all Class 7 and Class 8 tractors certified or 

exempted as vocational tractors. Note that in most cases, the provisions of paragraph (a) 

of this section will limit the allowable number of vehicles to be a number lower than the 

production limit of this paragraph (c). 

(d) Off-road exemption. All the provisions of this section apply for vocational tractors 

exempted under §1037.631, except as follows:

(1) The vehicles are required to comply with the requirements of §1037.631 instead 

of the requirements that would otherwise apply to vocational vehicles. Vehicles 

complying with the requirements of §1037.631 and using an engine certified to the 

standards of 40 CFR part 1036 are deemed to fully conform to all requirements 
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applicable to vocational vehicles under this part. 

(2) The vehicles must be labeled as specified under §1037.631 instead of as specified 

in paragraph (b)(3) of this section.

§ 1037.631 Exemption for vocational vehicles intended for off-road use.

This section provides an exemption from the greenhouse gas standards of this part for 

certain vocational vehicles intended to be used extensively in off-road environments such 

as forests, oil fields, and construction sites. This section does not exempt the engine used 

in the vehicle from the standards of 40 CFR part 86 or part 1036. Note that you may not 

include these exempted vehicles in any credit calculations under this part.

(a) Qualifying criteria. Vocational vehicles intended for off-road use meeting either the 

criteria of paragraph (a)(1) or (2) of this section are exempt without request, subject to the 

provisions of this section. 

(1) Vehicles are exempt if the tires installed on the vehicle have a maximum speed 

rating at or below 55 mph. 

(2) Vehicles are exempt if they were primarily designed to perform work off-road 

(such as in oil fields, forests, or construction sites), and they meet at least one of the 

criteria of paragraph (a)(2)(i) of this section and at least one of the criteria of 

paragraph (a)(2)(ii) of this section. 

(i) The vehicle must have affixed components designed to work in an off-road 

environment (i.e., hazardous material equipment or off-road drill equipment) or 

be designed to operate at low speeds such that it is unsuitable for normal highway

operation.

(ii) The vehicle must meet one of the following criteria:

(A) Have an axle that has a gross axle weight rating (GAWR) of 29,000 

pounds.

(B) Have a speed attainable in 2 miles of not more than 33 mph. 

(C) Have a speed attainable in 2 miles of not more than 45 mph, an unloaded 

vehicle weight that is not less than 95 percent of its gross vehicle weight 

rating (GVWR), and no capacity to carry occupants other than the driver and 

operating crew.

(b) Tractors. The provisions of this section may apply for tractors only if each tractor 

qualifies as a vocational tractor under §1037.630.

(c) Recordkeeping and reporting. (1) You must keep records to document that your 
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exempted vehicle configurations meet all applicable requirements of this section. 

Keep these records for at least eight years after you stop producing the exempted 

vehicle model. We may review these records at any time. 

(2) You must also keep records of the individual exempted vehicles you produce,

including the vehicle identification number and a description of the vehicle 

configuration. 

(3) Within 90 days after the end of each model year, you must send to the Designated 

Compliance Officer a report with the following information:

(i) A description of each exempted vehicle configuration, including an 

explanation of why it qualifies for this exemption.

(ii) The number of vehicles exempted for each vehicle configuration. 

(d) Labeling. You must include the following additional statement on the vehicle’s 

emission control information label under §1037.135: “THIS VEHICLE WAS 

EXEMPTED UNDER 40 CFR 1037.631.”.

§1037.640 Variable vehicle speed limiters. This section specifies provisions that apply

for vehicle speed limiters (VSLs) that you model under §1037.520. This does not apply

for VSLs that you do not model under §1037.520.

(a) General. The regulations of this part do not constrain how you may design VSLs for 

your vehicles. For example, you may design your VSL to have a single fixed speed limit 

or a soft-top speed limit. You may also design your VSL to expire after accumulation of 

a predetermined number of miles. However, designs with soft tops or expiration features 

are subject to proration provisions under this section that do not apply to fixed VSLs that 

do not expire.

(b) Definitions. The following definitions apply for purposes of this section:

(1) Default speed limit means the speed limit that normally applies for the vehicle, 

except as follows:

(i) The default speed limit for adjustable VSLs must represent the speed limit that 

applies when the VSL is adjusted to its highest setting under paragraph (c) of this 

section.

(ii) For VSLs with soft tops, the default speed does not include speeds possible 

only during soft-top operation.

(iii) For expiring VSLs, the default does not include speeds that are possible only

after expiration.
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(2) Soft-top speed limit means the highest speed limit that applies during soft-top 

operation.

(3) Maximum soft-top duration means the maximum amount of time that a vehicle 

could operate above the default speed limit. 

(4) Certified VSL means a VSL configuration that applies when a vehicle is new and 

until it expires.

(5) Expiration point means the mileage at which a vehicle’s certified VSL expires (or 

the point at which tamper protections expire). 

(6) Effective speed limit has the meaning given in paragraph (d) of this section. 

(c) Adjustments. You may design your VSL to be adjustable; however, this may affect 

the value you use in the GEM.

(1) Except as specified in paragraph (c)(2) of this section, any adjustments that can be 

made to the engine, vehicle, or their controls that change the VSL’s actual speed limit 

are considered to be adjustable operating parameters. Compliance is based on the 

vehicle being adjusted to the highest speed limit within this range.

(2) The following adjustments are not adjustable parameters:

(i) Adjustments made only to account for changing tire size or final drive ratio.

(ii) Adjustments protected by encrypted controls or passwords.

(iii) Adjustments possible only after the VSL’s expiration point.

(d) Effective speed limit. (1) For VSLs without soft tops or expiration points that 

expire before 1,259,000 miles, the effective speed limit is the highest speed limit that 

results by adjusting the VSL or other vehicle parameters consistent with the 

provisions of paragraph (c) of this section.

(2) For VSLs with soft tops and/or expiration points, the effective speed limit is 

calculated as specified in this paragraph (d)(2), which is based on 10 hours of 

operation per day (394 miles per day for day cabs and 551 miles per day for sleeper 

cabs). Note that this calculation assumes that a fraction of this operation is speedlimited (3.9 hours and 252 miles for day cabs, and 7.3 hours and 474 miles for sleeper 

cabs). Use the following equation to calculate the effective speed limit, rounded to 

the nearest 0.1 mph:

Effective speed = ExF * [STF* STSL + (1-STF) * DSL] + (1-ExF)*65 mph 

Where:
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ExF = expiration point miles/1,259,000 miles

STF = maximum number of allowable soft top operation hours per day / 3.9 hours for 

day cabs (or maximum miles per day / 252)

STF = maximum number of allowable soft top operation hours per day / 7.3 hours for 

sleeper cabs (or maximum miles per day / 474)

STSL = the soft top speed limit

DSL = the default speed limit

1037.645 In-use compliance with family emission limits (FELs).

You may ask us to apply a higher in-use FEL for certain in-use vehicles, subject to the 

provisions of this section. Note that §1037.225 contains provisions related to changing 

FELs during a model year.

(a) Purpose. This section is intended to address circumstances in which it is in the public 

interest to apply a higher in-use FEL based on forfeiting an appropriate number of 

emission credits. 

(b) FELs. We may apply higher in-use FELs to your vehicles as follows:

(1) Where your vehicle family includes more than one sub-family with different 

FELs, we may apply a higher FEL within the family than was applied to the 

vehicle’s configuration in your final ABT report. For example, if your vehicle 

family included three sub-families with FELs of 200 g/ton-mile, 210 g/ton-mile, 

and 220 g/ton-mile, we may apply a 220 g/ton-mile in-use FEL to vehicles that 

were originally designated as part of the 200 g/ton-mile or 210 g/ton-mile subfamilies.

(2) Without regard to the number of sub-families in your certified vehicle family, 

we may specify new sub-families with higher FELs than were included in your 

final ABT report. We may apply these higher FELs as in-use FELs for your 

vehicles. For example, if your vehicle family included three sub-families with 

FELs of 200 g/ton-mile, 210 g/ton-mile, and 220 g/ton-mile, we may specify a 

new 230 g/ton-mile sub-family.

(3) In specifying sub-families and in-use FELs, we would intend to accurately

reflect the actual in-use performance of your vehicles, consistent with the 

specified testing and modeling provisions of this part.

(c) Equivalent families. We may apply the higher FELs to other families in other model 

years if they used equivalent emission controls.
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(d) Credit forfeiture. Where we specify higher in-use FELs under this section, you must 

forfeit CO2 emission credits based on the difference between the in-use FEL and the 

otherwise applicable FEL. Calculate the amount of credits to be forfeited using the 

applicable equation in §1037.705, by substituting the otherwise applicable FEL for the 

standard and the in-use FEL for the otherwise applicable FEL.

(e) Requests. Submit your request to the Designated Compliance Officer. Include the 

following in your request:

(1) The vehicle family name, model year, and name/description of the 

configuration(s) affected.

(2) A list of other vehicle families/configurations/model years that may be 

affected.

(3) The otherwise applicable FEL for each configuration along with your 

recommendations for higher in-use FELs.

(4) Your source of credits for forfeiture. 

(f) Relation to recall. You may not request higher in-use FELs for any vehicle families 

for which we have made a determination of nonconformance and ordered a recall. You 

may, however, make such requests for vehicle families for which you are performing a 

voluntary emission recall.

(g) Approval. We may approve your request if we determine that you meet the 

requirements of this section and such approval is in the public interest. We may include 

appropriate conditions with our approval or we may approve your request with 

modifications.

§1037.650 Tire manufacturers.

This section describes how the requirements of this part apply with respect to tire 

manufacturers that choose to provide test data or emission warranties for purposes of this 

part.

(a) Testing. You are responsible as follows for test tires and emission test results that you 

provide to vehicle manufacturers for the purpose of the manufacturer submitting them to 

EPA for certification under this part: 

(1) Such test results are deemed under §1037.825 to be submissions to EPA. This 

means that you may be subject to criminal penalties under 18 U.S.C. 1001 if you 

knowingly submit false test results to the manufacturer.

(2) You may not cause a vehicle manufacturer to violate the regulations by rendering 

inaccurate emission test results you provide (or emission test results from testing of 

test tires you provide) to the vehicle manufacturer. 

(3) Your provision of test tires and emission test results to vehicle manufacturers for 

the purpose of certifying under this part is deemed to be an agreement to provide tires 

to EPA for confirmatory testing under §1037.201.

(b) Warranty. You may contractually agree to process emission warranty claims on 
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behalf of the manufacturer certifying the vehicle with respect to tires you produce. 

(1) Your fulfillment of the warranty requirements of this part is deemed to fulfill the 

vehicle manufacturer’s warranty obligations under this part with respect to tires you 

warrant.

(2) You may not cause a vehicle manufacturer to violate the regulations by failing to 

fulfill the emission warranty requirements that you contractually agreed to fulfill. 

§1037.655 Post-useful life vehicle modifications.

This section specifies vehicle modifications that may occur after a vehicle reaches the 

end of its regulatory useful life. It does not apply with respect to modifications that occur 

within the useful life period. It also does not apply with respect to engine modifications 

or recalibrations. Note that many such modifications to the vehicle during the useful life 

and to the engine at any time are presumed to violate 42 U.S.C 7522(a)(3)(A).

(a) General. Except as allowed by this section, it is prohibited for any person to remove 

or render inoperative any emission control device installed to comply with the 

requirements of this part 1037.

(b) Allowable modifications. You may modify a vehicle for the purpose of reducing 

emissions, provided you have a reasonable technical basis for knowing that such 

modification will not increase emissions of any other pollutant. Reasonable technical 

basis has the meaning given in 40 CFR 1068.30. This generally requires you to have 

information that would lead an engineer or other person familiar with engine and vehicle 

design and function to reasonably believe that the modifications will not increase 

emissions of any regulated pollutant.

(c) Examples of allowable modifications. The following are examples of allowable 

modifications:

(1) It is generally allowable to remove tractor roof fairings after the end of the 

vehicle’s useful life if the vehicle will no longer be used primarily to pull box 

trailers.

(2) Other fairings may be removed after the end of the vehicle’s useful life if the 

vehicle will no longer be used significantly on highways with vehicle speed of 55 

miles per hour or higher.

(d) Examples of prohibited modifications. The following are examples of modifications 

that are not allowable:

(1) No person may disable a vehicle speed limiter prior to its expiration point.

(2) No person may remove aerodynamic fairings from tractors that are used 

primarily to pull box trailers on highways.
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§1037.660 Automatic engine shutdown systems.

This section specifies requirements that apply for certified automatic engine shutdown 

systems (AES) that are modeled under §1037.520. It does not apply for AES systems 

that you do not model under §1037.520.

(a) Minimum requirements. Your AES system must meet all of the requirements of this 

paragraph (a) to be modeled under §1037.520. The system must shut down the engine 

within 300 seconds when all the following conditions are met:

(1) The transmission is set in neutral with the parking brake engaged (or the 

transmission is set to park if so equipped).

(2) The operator has not reset the system timer within the 300 seconds by

changing the position of the accelerator, brake, or clutch pedal; or by some other 

mechanism we approve.

(3) None of the override conditions of paragraph (b) of this section are met.

(b) Override conditions. The system may delay shutting the engine down while any of 

the conditions of this paragraph (b) apply. Engines equipped with auto restart may restart 

during override conditions. Note that these conditions allow the system to delay

shutdown or restart, but do not allow it to reset the timer. The system may delay

shutdown—

(1) While an exhaust emission control device is regenerating. The period 

considered to be regeneration for purposes of this allowance must be consistent 

with good engineering judgment and may differ in length from the period 

considered to be regeneration for other purposes. For example, in some cases it 

may be appropriate to include a cool down period for this purpose but not for 

infrequent regeneration adjustment factors.

(2) If necessary while servicing the vehicle, provided the deactivation of the AES 

system is accomplished using a diagnostic scan tool. The system must be 

automatically reactivated when the engine is shutdown for more than 60 minutes.

(3) If the vehicle’s main battery state-of-charge is not sufficient to allow the main 

engine to be restarted. 

(4) If the external ambient temperature reaches a level below which or above 

which the cabin temperature cannot be maintained within reasonable heat or cold 

exposure threshold limit values for the health and safety of the operator (not 

merely comfort). 

(5) If the vehicle’s engine coolant temperature is too low according to the 

manufacturer's engine protection guidance. This may also apply for fuel or oil 

temperatures. This allows the engine to continue operating until it reaches a 
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predefined temperature at which the shutdown sequence of paragraph (a) of this 

section would resume.

(6) The system may delay shutdown while the vehicle's main engine is operating 

in power take-off (PTO) mode. For purposes of this paragraph (b)(6), an engine 

is considered to be in PTO mode when a switch or setting designating PTO mode 

is enabled. 

(c) Expiration of AES systems. The AES system may include an expiration point (in 

miles) after which the AES system may be disabled. If your vehicle is equipped with an 

expiring AES system that expires before 1,259,000 miles adjust the model input as 

follows:

Input = 5 g CO2/ton-mile × (miles at expiration / 1,259,000 miles)

(d) Adjustable parameters. Provisions that apply generally with respect to adjustable 

parameters also apply to the AES system operating parameters, except the following are 

not considered to be adjustable parameters:

(1) Accelerator, brake, and clutch pedals, with respect to resetting the idle timer. 

Parameters associated with other timer reset mechanisms we approve are also not 

adjustable parameters.

(2) Bypass parameters allowed for vehicle service under paragraph (b)(2) of this 

section.

(3) Parameters that are adjustable only after the expiration point.

Subpart H—Averaging, Banking, and Trading for Certification

§ 1037.701 General provisions.

(a) You may average, bank, and trade (ABT) emission credits for purposes of 

certification as described in this subpart and in subpart B of this part to show compliance 

with the standards of §§ 1037.105 and 1037.106. Participation in this program is 

voluntary.

(b) The definitions of Subpart I of this part apply to this subpart. The following 

definitions also apply: 

(1) Actual emission credits means emission credits you have generated that we have 

verified by reviewing your final report.

(2) Averaging set means a set of vehicles in which emission credits may be 
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exchanged. Credits generated by one vehicle may only be used by other vehicles in 

the same averaging set. Note that an averaging set may comprise more than one 

regulatory subcategory. See § 1037.740.

(3) Broker means any entity that facilitates a trade of emission credits between a 

buyer and seller.

(4) Buyer means the entity that receives emission credits as a result of a trade.

(5) Reserved emission credits means emission credits you have generated that we 

have not yet verified by reviewing your final report.

(6) Seller means `the entity that provides emission credits during a trade.

(7) Standard means the emission standard that applies under subpart B of this part for 

vehicles not participating in the ABT program of this subpart. 

(8) Trade means to exchange emission credits, either as a buyer or seller.

(c) Emission credits may be exchanged only within an averaging set as specified in 

§ 1037.740.

(d) You may not use emission credits generated under this subpart to offset any emissions 

that exceed an FEL or standard, except as allowed by §1037.645. 

(e) You may trade emission credits generated from any number of your vehicles to the 

vehicle purchasers or other parties to retire the credits. Identify any such credits in the 

reports described in § 1037.730. Vehicles must comply with the applicable FELs even if 

you donate or sell the corresponding emission credits under this paragraph (e). Those 

credits may no longer be used by anyone to demonstrate compliance with any EPA 

emission standards.

(f) Emission credits may be used in the model year they are generated. Surplus emission 

credits may be banked for future model years. Surplus emission credits may sometimes 

be used for past model years, as described in §1037.745. 

(g) You may increase or decrease an FEL during the model year by amending your 

application for certification under § 1037.225. The new FEL may apply only to vehicles 

you have not already introduced into commerce. 

(h) See §1037.740 for special credit provisions that apply for credits generated under 

§1037.104(d)(7), §1037.615 or 40 CFR 1036.615.

(i) Unless the regulations explicitly allow it, you may not calculate credits more than 

once for any emission reduction. For example, if you generate CO2 emission credits for a 

given hybrid vehicle under this part, no one may generate CO2 emission credits for the 

hybrid engine under 40 CFR part 1036. However, credits could be generated for identical 

engine used in vehicles that did not generate credits under this part.
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§ 1037.705 Generating and calculating emission credits.

(a) The provisions of this section apply separately for calculating emission credits for 

each pollutant.

(b) For each participating family or subfamily, calculate positive or negative emission 

credits relative to the otherwise applicable emission standard. Calculate positive 

emission credits for a family or subfamily that has an FEL below the standard. Calculate 

negative emission credits for a family or subfamily that has an FEL above the standard. 

Sum your positive and negative credits for the model year before rounding. Round the 

sum of emission credits to the nearest megagram (Mg), using consistent units throughout 

the following equations:

(1) For vocational vehicles:

Emission credits (Mg) = (Std-FEL) × (Payload Tons) × (Volume) × (UL) × (10-6)

Where:

Std = the emission standard associated with the specific tractor regulatory

subcategory (g/ton-mile).

FEL = the family emission limit for the vehicle subfamily (g/ton-mile).

Payload tons = the prescribed payload for each class in tons (2.85 tons for light 

heavy-duty vehicles, 5.6 tons for medium heavy-duty vehicles, and 7.5 tons for heavy

heavy-duty vehicles).

Volume = U.S.-directed production volume of the vehicle subfamily. For example, if 

you produce three configurations with the same FEL, the subfamily production 

volume would be the sum of the production volumes for these three configurations.

UL = useful life of the vehicle (110,000 miles for light heavy-duty vehicles, 185,000 

miles for medium heavy-duty vehicles, and 435,000 miles for heavy heavy-duty

vehicles).

(2) For tractors: 

Emission credits (Mg) = (Std-FEL) × (Payload tons) × (Volume) × (UL) × (10-6)

Where:
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Std = the emission standard associated with the specific tractor regulatory

subcategory (g/ton-mile).

FEL = the family emission limit for the vehicle subfamily (g/ton-mile).

Payload tons = the prescribed payload for each class in tons (12.5 tons for Class 7 and 

19 tons for Class 8).

Volume = U.S.-directed production volume of the vehicle subfamily.

UL = useful life of the tractor (435,000 miles for Class 8 and 185,000 miles for Class 

7).

(c) As described in § 1037.730, compliance with the requirements of this subpart is 

determined at the end of the model year based on actual U.S.-directed production 

volumes. Keep appropriate records to document these production volumes. Do not 

include any of the following vehicles to calculate emission credits:

(1) Vehicles that you do not certify to the CO2 standards of this part because they are 

permanently exempted under subpart G of this part or under 40 CFR part 1068.

(2) Exported vehicles.

(3) Vehicles not subject to the requirements of this part, such as those excluded under 

§ 1037.5.

(4) Any other vehicles, where we indicate elsewhere in this part 1037 that they are not 

to be included in the calculations of this subpart. 

§ 1037.710 Averaging.

(a) Averaging is the exchange of emission credits among your vehicle families. You may

average emission credits only within the same averaging set.

(b) You may certify one or more vehicle families (or subfamilies) to an FEL above the 

applicable standard, subject to any applicable FEL caps and other provisions in subpart B 

of this part, if you show in your application for certification that your projected balance 

of all emission-credit transactions in that model year is greater than or equal to zero or 

that a negative balance is allowed under § 1037.745. 

(c) If you certify a vehicle family to an FEL that exceeds the otherwise applicable 

standard, you must obtain enough emission credits to offset the vehicle family’s deficit 

by the due date for the final report required in § 1037.730. The emission credits used to 

address the deficit may come from your other vehicle families that generate emission 
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credits in the same model year (or from later model years as specified in § 1037.745), 

from emission credits you have banked, or from emission credits you obtain through 

trading.

§ 1037.715 Banking.

(a) Banking is the retention of surplus emission credits by the manufacturer generating 

the emission credits for use in future model years for averaging or trading. 

(b) You may designate any emission credits you plan to bank in the reports you submit 

under § 1037.730 as reserved credits. During the model year and before the due date for 

the final report, you may designate your reserved emission credits for averaging or 

trading.

(c) Reserved credits become actual emission credits when you submit your final report. 

However, we may revoke these emission credits if we are unable to verify them after 

reviewing your reports or auditing your records.

(d) Banked credits retain the designation of the averaging set in which they were 

generated.

§ 1037.720 Trading.

(a) Trading is the exchange of emission credits between manufacturers, or the transfer of 

credits to another party to retire them. You may use traded emission credits for 

averaging, banking, or further trading transactions. Traded emission credits remain 

subject to the averaging-set restrictions based on the averaging set in which they were 

generated.

(b) You may trade actual emission credits as described in this subpart. You may also 

trade reserved emission credits, but we may revoke these emission credits based on our 

review of your records or reports or those of the company with which you traded 

emission credits. You may trade banked credits within an averaging set to any certifying 

manufacturer.

(c) If a negative emission credit balance results from a transaction, both the buyer and 

seller are liable, except in cases we deem to involve fraud. See § 1037.255(e) for cases 

involving fraud. We may void the certificates of all vehicle families participating in a 

trade that results in a manufacturer having a negative balance of emission credits. See 

§ 1037.745.

§ 1037.725 What must I include in my application for certification?
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(a) You must declare in your application for certification your intent to use the provisions 

of this subpart for each vehicle family that will be certified using the ABT program. You 

must also declare the FELs you select for the vehicle family or subfamily for each 

pollutant for which you are using the ABT program. Your FELs must comply with the 

specifications of subpart B of this part, including the FEL caps. FELs must be expressed 

to the same number of decimal places as the applicable standards.

(b) Include the following in your application for certification:

(1) A statement that, to the best of your belief, you will not have a negative balance of 

emission credits for any averaging set when all emission credits are calculated at the 

end of the year; or a statement that you will have a negative balance of emission 

credits for one or more averaging sets but that it is allowed under § 1037.745.

(2) Calculations of projected emission credits (positive or negative) based on 

projected U.S.-directed production volumes. We may require you to include similar 

calculations from your other vehicle families to project your net credit balances for 

the model year. If you project negative emission credits for a family or subfamily, 

state the source of positive emission credits you expect to use to offset the negative 

emission credits.

§ 1037.730 ABT reports.

(a) If any of your vehicle families are certified using the ABT provisions of this subpart, 

you must send an end-of-year report within 90 days after the end of the model year and a 

final report within 270 days after the end of the model year. 

(b) Your end-of-year and final reports must include the following information for each 

vehicle family participating in the ABT program:

(1) Vehicle-family and subfamily designations.

(2) The regulatory subcategory and emission standards that would otherwise apply to 

the vehicle family.

(3) The FEL for each pollutant. If you change the FEL after the start of production, 

identify the date that you started using the new FEL and/or give the vehicle 

identification number for the first vehicle covered by the new FEL. In this case, 

identify each applicable FEL and calculate the positive or negative emission credits as 

specified in § 1037.225.

(4) The projected and actual U.S.-directed production volumes for the model year. If 

you changed an FEL during the model year, identify the actual production volume 

associated with each FEL.

(5) Useful life.
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(6) Calculated positive or negative emission credits for the whole vehicle family. 

Identify any emission credits that you traded, as described in paragraph (d)(1) of this 

section.

(7) If you have a negative credit balance for the averaging set in the given model 

year, specify whether the vehicle family (or certain subfamilies with the vehicle 

family) have a credit deficit for the year. Consider for example, a manufacturer with 

three vehicle families (“A”, “B”, and “C”) in a given averaging set. If family A 

generates enough credits to offset the negative credits of family B but not enough to 

also offset the negative credits of family C (and the manufacturer has no banked 

credits in the averaging set), the manufacturer may designate families A and B as 

having no deficit for the model year, provided it designates family C as having a 

deficit for the model year.

(c) Your end-of-year and final reports must include the following additional information:

(1) Show that your net balance of emission credits from all your participating vehicle 

families in each averaging set in the applicable model year is not negative, except as 

allowed under § 1037.745.

(2) State whether you will reserve any emission credits for banking.

(3) State that the report’s contents are accurate.

(d) If you trade emission credits, you must send us a report within 90 days after the 

transaction, as follows:

(1) As the seller, you must include the following information in your report:

(i) The corporate names of the buyer and any brokers.

(ii) A copy of any contracts related to the trade.

(iii) The vehicle families that generated emission credits for the trade, 

including the number of emission credits from each family.

(2) As the buyer, you must include the following information in your report:

(i) The corporate names of the seller and any brokers.

(ii) A copy of any contracts related to the trade.

(iii) How you intend to use the emission credits, including the number of 

emission credits you intend to apply to each vehicle family (if known).

(e) Send your reports electronically to the Designated Compliance Officer using an 

approved information format. If you want to use a different format, send us a written 

request with justification for a waiver.
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(f) Correct errors in your end-of-year report or final report as follows:

(1) You may correct any errors in your end-of-year report when you prepare the final 

report, as long as you send us the final report by the time it is due.

(2) If you or we determine within 270 days after the end of the model year that errors 

mistakenly decreased your balance of emission credits, you may correct the errors 

and recalculate the balance of emission credits. You may not make these corrections 

for errors that are determined more than 270 days after the end of the model year. If 

you report a negative balance of emission credits, we may disallow corrections under 

this paragraph (f)(2).

(3) If you or we determine anytime that errors mistakenly increased your balance of 

emission credits, you must correct the errors and recalculate the balance of emission 

credits.

§ 1037.735 Recordkeeping.

(a) You must organize and maintain your records as described in this section. We may

review your records at any time.

(b) Keep the records required by this section for at least eight years after the due date for 

the end-of-year report. You may not use emission credits for any vehicles if you do not 

keep all the records required under this section. You must therefore keep these records to 

continue to bank valid credits. Store these records in any format and on any media, as 

long as you can promptly send us organized, written records in English if we ask for 

them. You must keep these records readily available. We may review them at any time.

(c) Keep a copy of the reports we require in §§ 1037.725 and 1037.730.

(d) Keep records of the vehicle identification number for each vehicle you produce that 

generates or uses emission credits under the ABT program. You may identify these 

numbers as a range. If you change the FEL after the start of production, identify the date 

you started using each FEL and the range of vehicle identification numbers associated 

with each FEL. You must also identify the purchaser and destination for each vehicle 

you produce to the extent this information is available.

(e) We may require you to keep additional records or to send us relevant information not 

required by this section in accordance with the Clean Air Act.

§ 1037.740 Restrictions for using emission credits.

The following restrictions apply for using emission credits:
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(a) Averaging sets. Except as specified in paragraph (b) of this section, emission credits 

may be exchanged only within an averaging set. There are three principal averaging sets 

for vehicles subject to this subpart. 

(1) Vehicles at or below 19,500 pounds GVWR that are subject to the standards of 

§1037.105. 

(2) Vehicles above 19,500 pounds GVWR but at or below 33,000 pounds GVWR.

(3) Vehicles over 33,000 pounds GVWR.

(4) Note that other separate averaging sets also apply for emission credits not related 

to this subpart. For example, under § 1037.104, an additional averaging set 

comprises all vehicles subject to the standards of that section. Separate averaging sets 

also apply for engines under 40 CFR part 1036, including engines used in vehicles 

subject to this subpart. 

(b) Credits from hybrid vehicles and other advanced technologies. The averaging set 

restrictions of paragraph (a) of this section do not apply for credits generated under 

§1037.104(d)(7), §1037.615 or 40 CFR 1036.615 from hybrid vehicles with regenerative 

braking, or from other advanced technologies. 

(1) The maximum amount of credits you may bring into the following service class 

groups is 60,000 Mg per model year: 

(i) Spark-ignition engines, light heavy-duty compression-ignition engines, and 

light heavy-duty vehicles. This group comprises the averaging set listed in 

paragraphs(a)(1) of this section and the averaging set listed in 40 CFR 

1036.740(a)(1) and (2).

(ii) Medium heavy-duty compression-ignition engines and medium heavy-duty

vehicles. This group comprises the averaging sets listed in paragraph (a)(2) of this 

section and 40 CFR 1036.740(a)(3).

(iii) Heavy heavy-duty compression-ignition engines and heavy heavy-duty

vehicles. This group comprises the averaging sets listed in paragraph (a)(3) of this 

section and 40 CFR 1036.740(a)(4).

(2) The limit specified in paragraph (b)(1) of this section does not limit the amount of 

advanced technology credits that can be used within a service class group if they were 

generated in that same service class group.

(c) Credit life. Credits expire after five years.

(d) Other restrictions. Other sections of this part specify additional restrictions for using 

emission credits under certain special provisions.
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§ 1037.745 End-of-year CO2 credit deficits.

Except as allowed by this section, we may void the certificate of any vehicle family

certified to an FEL above the applicable standard for which you do not have sufficient 

credits by the deadline for submitting the final report. 

(a) Your certificate for a vehicle family for which you do not have sufficient CO2 credits 

will not be void if you remedy the deficit with surplus credits within three model years. 

For example, if you have a credit deficit of 500 Mg for a vehicle family at the end of 

model year 2015, you must generate (or otherwise obtain) a surplus of at least 500 Mg in 

that same averaging set by the end of model year 2018.

(b) You may apply only surplus credits to your deficit. You may not apply credits to a 

deficit from an earlier model year if they were generated in a model year for which any of 

your vehicle families for that averaging set had an end-of-year credit deficit.

(c) If you do not remedy the deficit with surplus credits within three model years, we may

void your certificate for that vehicle family. Note that voiding a certificate applies ab 

initio. Where the net deficit is less than the total amount of negative credits originally 

generated by the family, we will void the certificate only with respect to the number of 

vehicles needed to reach the amount of the net deficit. For example, if the original 

vehicle family generated 500 Mg of negative credits, and the manufacturer’s net deficit 

after three years was 250 Mg, we would void the certificate with respect to half of the 

vehicles in the family.

§ 1037.750 What can happen if I do not comply with the provisions of this subpart?

(a) For each vehicle family participating in the ABT program, the certificate of 

conformity is conditioned upon full compliance with the provisions of this subpart during 

and after the model year. You are responsible to establish to our satisfaction that you 

fully comply with applicable requirements. We may void the certificate of conformity 

for a vehicle family if you fail to comply with any provisions of this subpart.

(b) You may certify your vehicle family or subfamily to an FEL above an applicable 

standard based on a projection that you will have enough emission credits to offset the 

deficit for the vehicle family. See §1036.745 for provisions specifying what happens if 

you cannot show in your final report that you have enough actual emission credits to 

offset a deficit for any pollutant in a vehicle family.

(c) We may void the certificate of conformity for a vehicle family if you fail to keep 

records, send reports, or give us information we request. Note that failing to keep 

records, send reports, or give us information we request is also a violation of 42 U.S.C. 

7522(a)(2).

(d) You may ask for a hearing if we void your certificate under this section (see 

§ 1037.820).
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§ 1037.755 Information provided to the Department of Transportation.

After receipt of each manufacturer’s final report as specified in § 1037.730 and 

completion of any verification testing required to validate the manufacturer’s submitted 

final data, we will issue a report to the Department of Transportation with CO2 emission 

information and will verify the accuracy of each manufacturer’s equivalent fuel 

consumption data required by NHTSA under 49 CFR 535.8. We will send a report to 

DOT for each vehicle manufacturer based on each regulatory category and subcategory, 

including sufficient information for NHTSA to determine fuel consumption and 

associated credit values. See 49 CFR 535.8 to determine if NHTSA deems submission of 

this information to EPA to also be a submission to NHTSA. 

Subpart I—Definitions and Other Reference Information

§ 1037.801 Definitions.

The following definitions apply to this part. The definitions apply to all subparts unless 

we note otherwise. All undefined terms have the meaning the Act gives to them. The 

definitions follow:

A to B testing means testing performed in pairs to allow comparison of vehicle A to 

vehicle B.

Act means the Clean Air Act, as amended, 42 U.S.C. 7401 - 7671q.

Adjustable parameter means any device, system, or element of design that someone 

can adjust (including those which are difficult to access) and that, if adjusted, may affect 

measured or modeled emissions (as applicable). You may ask us to exclude a parameter 

that is difficult to access if it cannot be adjusted to affect emissions without significantly 

degrading vehicle performance, or if you otherwise show us that it will not be adjusted in 

a way that affects emissions during in-use operation.

Adjusted Loaded Vehicle Weight means the numerical average of vehicle curb 

weight and GVWR. 

Advanced technology means vehicle technology certified under §1037.615, 

§1037.104(d)(7), or 40 CFR 1036.615.

Aftertreatment means relating to a catalytic converter, particulate filter, or any other 

system, component, or technology mounted downstream of the exhaust valve (or exhaust 

port) whose design function is to decrease emissions in the vehicle exhaust before it is 

exhausted to the environment. Exhaust-gas recirculation (EGR) and turbochargers are 
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not aftertreatment.

Alcohol-fueled vehicle means a vehicle that is designed to run using an alcohol fuel. 

For purposes of this definition, alcohol fuels do not include fuels with a nominal alcohol 

content below 25 percent by volume.

Auxiliary emission control device means any element of design that senses 

temperature, motive speed, engine RPM, transmission gear, or any other parameter for 

the purpose of activating, modulating, delaying, or deactivating the operation of any part 

of the emission control system.

Averaging set has the meaning given in § 1037.701.

Cab-complete vehicle means a vehicle that is first sold as an incomplete vehicle that 

substantially includes its cab. Vehicles known commercially as chassis-cabs, cabchassis, box-deletes, bed-deletes, cut-away vans are considered cab-complete vehicles. 

For purposes of this definition, a cab includes a steering column and passenger 

compartment. Note a vehicle lacking some components of the cab is a cab-complete 

vehicle if it substantially includes the cab.

Calibration means the set of specifications and tolerances specific to a particular 

design, version, or application of a component or assembly capable of functionally

describing its operation over its working range.

Carbon-related exhaust emissions (CREE) has the meaning given in 40 CFR 600.002. 

Note that CREE represents the combined mass of carbon emitted as HC, CO, and CO2, 

expressed as having a molecular weight equal to that of CO2. 

Carryover means relating to certification based on emission data generated from an 

earlier model year.

Certification means relating to the process of obtaining a certificate of conformity for 

a vehicle family that complies with the emission standards and requirements in this part. 

Certified emission level means the highest deteriorated emission level in a vehicle 

family for a given pollutant from either transient or steady-state testing. 

Class means relating to GVWR classes, as follows:

(1) Class 2b means heavy-duty motor vehicles at or below 10,000 pounds GVWR. 

(2) Class 3 means heavy-duty motor vehicles above 10,000 pounds GVWR but at or 

below 14,000 pounds GVWR. 

(3) Class 4 means heavy-duty motor vehicles above 14,000 pounds GVWR but at or 

below 16,000 pounds GVWR.

(4) Class 5 means heavy-duty motor vehicles above 16,000 pounds GVWR but at or 
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below 19,500 pounds GVWR.

(5) Class 6 means heavy-duty motor vehicles above 19,500 pounds GVWR but at or 

below 26,000 pounds GVWR.

(6) Class 7 means heavy-duty motor vehicles above 26,000 pounds GVWR but at or 

below 33,000 pounds GVWR.

(7) Class 8 means heavy-duty motor vehicles above 33,000 pounds GVWR.

Complete vehicle has the meaning given in the definition of vehicle in this section.

Compression-ignition means relating to a type of reciprocating, internal-combustion 

engine that is not a spark-ignition engine.

Curb weight has the meaning given in 40 CFR 86.1803, consistent with the 

provisions of § 1037.140. 

Date of manufacture means the date on which the certifying vehicle manufacturer 

completes its manufacturing operations, except as follows:

(1) Where the certificate holder is an engine manufacturer that does not manufacture the 

chassis, the date of manufacture of the vehicle is based on the date assembly of the 

vehicle is completed.

(2) We may approve an alternate date of manufacture based on the date on which the 

certifying (or primary) manufacturer completes assembly at the place of main assembly, 

consistent with the provisions of §1037.601 and 49 CFR 567.4.

Day cab means a type of tractor cab that is not a sleeper cab.

Designated Compliance Officer means the Manager, Heavy-Duty and Nonroad 

Engine

Group (6405-J), U.S. Environmental Protection Agency, 1200 Pennsylvania Ave., NW., 

Washington, DC 20460.

Designated Enforcement Officer means the Director, Air Enforcement Division 

(2242A), U.S. Environmental Protection Agency, 1200 Pennsylvania Ave., NW., 

Washington, DC 20460.

Deteriorated emission level means the emission level that results from applying the 

appropriate deterioration factor to the official emission result of the emission-data 

vehicle. Note that where no deterioration factor applies, references in this part to the 

deteriorated emission level mean the official emission result.

Deterioration factor means the relationship between emissions at the end of useful life 

and emissions at the low-hour test point, expressed in one of the following ways:
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(1) For multiplicative deterioration factors, the ratio of emissions at the end of useful life 

to emissions at the low-hour test point.

(2) For additive deterioration factors, the difference between emissions at the end of 

useful life and emissions at the low-hour test point.

Driver model means an automated controller that simulates a person driving a 

vehicle.

Electric vehicle means a vehicle that does not include an engine, and is powered 

solely by an external source of electricity and/or solar power. Note that this does not 

include electric hybrid or fuel-cell vehicles that use a chemical fuel such as gasoline, 

diesel fuel, or hydrogen. Electric vehicles may also be referred to as all-electric vehicles 

to distinguish them from hybrid vehicles. 

Emission control system means any device, system, or element of design that controls 

or reduces the emissions of regulated pollutants from a vehicle.

Emission-data vehicle means a vehicle that is tested for certification. This includes 

vehicle tested to establish deterioration factors.

Emission-related maintenance means maintenance that substantially affects emissions 

or is likely to substantially affect emission deterioration.

Excluded means relating to vehicles that are not subject to some or all of the 

requirements of this part as follows:

(1) A vehicle that has been determined not to be a motor vehicle is excluded from this 

part.

(2) Certain vehicles are excluded from the requirements of this part under § 1037.5.

(3) Specific regulatory provisions of this part may exclude a vehicle generally subject to 

this part from one or more specific standards or requirements of this part.

Exempted has the meaning given in 40 CFR 1068.30.

Family emission limit (FEL) means an emission level declared by the manufacturer to 

serve in place of an otherwise applicable emission standard under the ABT program in 

subpart H of this part. The family emission limit must be expressed to the same number 

of decimal places as the emission standard it replaces. Note that an FEL may apply as a 

“subfamily” emission limit.

Fuel system means all components involved in transporting, metering, and mixing the 

fuel from the fuel tank to the combustion chamber(s), including the fuel tank, fuel pump, 

fuel filters, fuel lines, carburetor or fuel-injection components, and all fuel-system vents. 

It also includes components for controlling evaporative emissions, such as fuel caps, 

purge valves, and carbon canisters.
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Fuel type means a general category of fuels such as diesel fuel or natural gas. There 

can be multiple grades within a single fuel type, such as high-sulfur or low-sulfur diesel 

fuel.

Good engineering judgment has the meaning given in 40 CFR 1068.30. See 40 CFR 

1068.5 for the administrative process we use to evaluate good engineering judgment.

Gross vehicle weight rating (GVWR) means the value specified by the vehicle 

manufacturer as the maximum design loaded weight of a single vehicle, consistent with 

good engineering judgment. 

Gross combination weight rating (GCWR) means the value specified by the vehicle 

manufacturer as the maximum weight of a loaded vehicle and trailer, consistent with 

good engineering judgment. For example, compliance with SAE J2807 is generally 

considered to be consistent with good engineering judgment, especially for Class 3 and 

smaller vehicles.

Heavy-duty engine means any engine used for (or for which the engine manufacturer 

could reasonably expect to be used for) motive power in a heavy-duty vehicle.

Heavy-duty vehicle means any motor vehicle above 8,500 pounds GVWR or that has 

a vehicle curb weight above 6,000 pounds or that has a basic vehicle frontal area greater 

than 45 square feet.

Hybrid engine or hybrid powertrain means an engine or powertrain that includes 

energy storage features other than a conventional battery system or conventional 

flywheel. Supplemental electrical batteries and hydraulic accumulators are examples of 

hybrid energy storage systems Note that certain provisions in this part treat hybrid 

engines and powertrains intended for vehicles that include regenerative braking different 

than those intended for vehicles that do not include regenerative braking.

Hybrid vehicle means a vehicle that includes energy storage features (other than a 

conventional battery system or conventional flywheel) in addition to an internal 

combustion engine or other engine using consumable chemical fuel. Supplemental 

electrical batteries and hydraulic accumulators are examples of hybrid energy storage 

systems Note that certain provisions in this part treat hybrid vehicles that include 

regenerative braking different than those that do not include regenerative braking.

Hydrocarbon (HC) means the hydrocarbon group on which the emission standards are 

based for each fuel type. For alcohol-fueled vehicles, HC means nonmethane 

hydrocarbon equivalent (NMHCE) for exhaust emissions and total hydrocarbon 

equivalent (THCE) for evaporative emissions. For all other vehicles, HC means 

nonmethane hydrocarbon (NMHC) for exhaust emissions and total hydrocarbon (THC) 

for evaporative emissions.

Identification number means a unique specification (for example, a model 

number/serial number combination) that allows someone to distinguish a particular 

vehicle from other similar vehicles. 
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Incomplete vehicle has the meaning given in the definition of vehicle in this section.

Innovative technology means technology certified under §1037.610.

Light-duty truck means any motor vehicle rated at or below 8,500 pounds GVWR 

with a curb weight at or below 6,000 pounds and basic vehicle frontal area at or below 45 

square feet, which is:

(1) Designed primarily for purposes of transportation of property or is a derivation of 

such a vehicle; or

(2) Designed primarily for transportation of persons and has a capacity of more than 12 

persons; or

(3) Available with special features enabling off-street or off-highway operation and use.

Light-duty vehicle means a passenger car or passenger car derivative capable of 

seating 12 or fewer passengers.

Low-mileage means relating to a vehicle with stabilized emissions and represents the 

undeteriorated emission level. This would generally involve approximately 4000 miles 

of operation.

Low rolling resistance tire means a tire on a vocational vehicle with a TRRL at or 

below of 7.7 kg/metric ton, a steer tire on a tractor with a TRRL at or below 7.7 kg/metric 

ton, or a drive tire on a tractor with a TRRL at or below 8.1 kg/metric ton.

Manufacture means the physical and engineering process of designing, constructing, 

and/or assembling a vehicle. 

Manufacturer has the meaning given in section 216(1) of the Act. In general, this 

term includes any person who manufactures a vehicle or vehicle for sale in the United 

States or otherwise introduces a new motor vehicle into commerce in the United States. 

This includes importers who import vehicles or vehicles for resale. 

Medium-duty passenger vehicle (MDPV) has the meaning given in 40 CFR 86.1803.

Model year means the manufacturer’s annual new model production period, except as 

restricted under this definition and 40 CFR part 85, subpart X. It must include January 1 

of the calendar year for which the model year is named, may not begin before January 2 

of the previous calendar year, and it must end by December 31 of the named calendar 

year. 

(1) The manufacturer who holds the certificate of conformity for the vehicle must 

assign the model year based on the date when its manufacturing operations are 

completed relative to its annual model year period. In unusual circumstances where 

completion of your assembly is delayed, we may allow you to assign a model year 

one year earlier, provided it does not affect which regulatory requirements will apply.
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(2) Unless a vehicle is being shipped to a secondary manufacturer that will hold the 

certificate of conformity, the model year must be assigned prior to introduction of the 

vehicle into U.S. commerce. The certifying manufacturer must redesignate the model 

year if it does not complete its manufacturing operations within the originally

identified model year. A vehicle introduced into U.S. commerce without a model 

year is deemed to have a model year equal to the calendar year of its introduction into 

U.S. commerce unless the certifying manufacturer assigns a later date.

Motor vehicle has the meaning given in 40 CFR 85.1703. 

New motor vehicle means a motor vehicle meeting the criteria of either paragraph (1) 

or (2) of this definition. New motor vehicles may be complete or incomplete.

(1) A motor vehicle for which the ultimate purchaser has never received the equitable or 

legal title is a new motor vehicle. This kind of vehicle might commonly be thought of as 

"brand new" although a new motor vehicle may include previously used parts. Under 

this definition, the vehicle is new from the time it is produced until the ultimate purchaser 

receives the title or places it into service, whichever comes first.

(2) An imported heavy-duty motor vehicle originally produced after the 1969 model year 

is a new motor vehicle.

Noncompliant vehicle means a vehicle that was originally covered by a certificate of 

conformity, but is not in the certified configuration or otherwise does not comply with the 

conditions of the certificate.

Nonconforming vehicle means a vehicle not covered by a certificate of conformity 

that would otherwise be subject to emission standards.

Nonmethane hydrocarbons (NMHC) means the sum of all hydrocarbon species 

except methane, as measured according to 40 CFR part 1065.

Official emission result means the measured emission rate for an emission-data 

vehicle on a given duty cycle before the application of any required deterioration factor, 

but after the applicability of regeneration adjustment factors.

Owners manual means a document or collection of documents prepared by the 

vehicle manufacturer for the owners or operators to describe appropriate vehicle 

maintenance, applicable warranties, and any other information related to operating or 

keeping the vehicle. The owners manual is typically provided to the ultimate purchaser 

at the time of sale.

Oxides of nitrogen has the meaning given in 40 CFR 1065.1001.

Particulate trap means a filtering device that is designed to physically trap all 

particulate matter above a certain size. 

Percent has the meaning given in 40 CFR 1065.1001. Note that this means 
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percentages identified in this part are assumed to be infinitely precise without regard to 

the number of significant figures. For example, one percent of 1,493 is 14.93.

Placed into service means put into initial use for its intended purpose.

Power take-off (PTO) means a secondary engine shaft (or equivalent) that provides 

substantial auxiliary power for purposes unrelated to vehicle propulsion or normal 

vehicle accessories such as air conditioning, power steering, and basic electrical 

accessories. A typical PTO uses a secondary shaft on the engine to transmit power to a 

hydraulic pump that powers auxiliary equipment, such as a boom on a bucket truck. You 

may ask us to consider other equivalent auxiliary power configurations (such as those 

with hybrid vehicles) as power take-off systems.

Rechargeable Energy Storage System (RESS) means the component(s) of a hybrid 

engine or vehicle that store recovered energy for later use, such as the battery system in 

an electric hybrid vehicle. 

Regulatory sub-category means one of following groups:

(1) Spark-ignition vehicles subject to the standards of § 1037.104. Note that this category

includes most gasoline-fueled heavy-duty pickup trucks and vans.

(2) All other vehicles subject to the standards of § 1037.104. Note that this category

includes most diesel-fueled heavy-duty pickup trucks and van.

(3)Vocational vehicles at or below 19,500 pounds GVWR. 

(4) Vocational vehicles at or above 19,500 pounds GVWR but below 33,000 pounds 

GVWR.

(5) Vocational vehicles over 33,000 pounds GVWR.

(6) Low- -roof tractors at or above 26,000 pounds GVWR but below 33,000 pounds 

GVWR.

(7) Mid-roof tractors at or above 26,000 pounds GVWR but below 33,000 pounds 

GVWR.

(8) High-roof tractors at or above 26,000 pounds GVWR but below 33,000 pounds 

GVWR.

(9) Low-roof day cab tractors at or above 33,000 pounds GVWR.

(10) Low-roof sleeper cab tractors at or above 33,000 pounds GVWR.

(11) Mid-roof day cab tractors at or above 33,000 pounds GVWR.

(12) Mid-roof sleeper cab tractors at or above 33,000 pounds GVWR.
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(13) High-roof day cab tractors at or above 33,000 pounds GVWR.

(14) High-roof sleeper cab tractors at or above 33,000 pounds GVWR.

Relating to as used in this section means relating to something in a specific, direct 

manner. This expression is used in this section only to define terms as adjectives and not 

to broaden the meaning of the terms.

Revoke has the meaning given in 40 CFR 1068.30.

Roof height means the maximum height of a vehicle (rounded to the nearest inch), 

excluding narrow accessories such as exhaust pipes and antennas, but including any wide 

accessories such as roof fairings. Measure roof height of the vehicle configured to have 

its maximum height that will occur during actual use, with properly inflated tires and no 

driver, passengers, or cargo onboard. Roof height may also refer to the following 

categories:

(1) Low-roof means relating to a vehicle with a roof height of 120 inches or less.

(2) Mid-roof means relating to a vehicle with a roof height of 121 to 147 inches. 

(3) High-roof means relating to a vehicle with a roof height of 148 inches or more. 

Round has the meaning given in 40 CFR 1065.1001.

Scheduled maintenance means adjusting, repairing, removing, disassembling, 

cleaning, or replacing components or systems periodically to keep a part or system from 

failing, malfunctioning, or wearing prematurely. It also may mean actions you expect are 

necessary to correct an overt indication of failure or malfunction for which periodic 

maintenance is not appropriate.

Sleeper cab means a type of tractor cab that has a compartment behind the driver’s 

seat intended to be used by the driver for sleeping. This includes cabs accessible from 

the driver’s compartment and those accessible from outside the vehicle.

Small manufacturer means a manufacturer meeting the criteria specified in 13 CFR 

121.201. For manufacturers owned by a parent company, the employee and revenue 

limits apply to the total number employees and total revenue of the parent company and 

all its subsidiaries.Spark-ignition means relating to a gasoline-fueled engine or any other 

type of engine with a spark plug (or other sparking device) and with operating 

characteristics significantly similar to the theoretical Otto combustion cycle. Sparkignition engines usually use a throttle to regulate intake air flow to control power during 

normal operation. 

Standard payload means the vehicle payload assumed for each class in tons for 

modeling and calculating emission credits. There are three standard payloads:

(1) 2.85 tons for light heavy-duty vehicles.
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(2) 5.6 tons for medium heavy-duty vehicles.

(3) 7.5 tons for heavy heavy-duty vehicles. 

Standard trailer has the meaning given in § 1037.501.

Suspend has the meaning given in 40 CFR 1068.30.

Test sample means the collection of vehicles selected from the population of a vehicle 

family for emission testing. This may include testing for certification, production-line 

testing, or in-use testing.

Test vehicle means a vehicle in a test sample.

Test weight means the vehicle weight used or represented during testing. 

Tire rolling resistance level (TRRL) means a value with units of kg/metric ton that 

represents that rolling resistance of a tire configuration. TRRLs are used as inputs to the 

GEM model under §1037.520. Note that a manufacturer may assign a value higher than 

the measured rolling resistance of a tire configuration. 

Total hydrocarbon has the meaning given in 40 CFR 1065.1001. This generally 

means the combined mass of organic compounds measured by the specified procedure for 

measuring total hydrocarbon, expressed as a hydrocarbon with an atomic hydrogen-tocarbon ratio of 1.85:1.

Total hydrocarbon equivalent has the meaning given in 40 CFR 1065.1001. This 

generally means the sum of the carbon mass contributions of non-oxygenated 

hydrocarbons, alcohols and aldehydes, or other organic compounds that are measured 

separately as contained in a gas sample, expressed as exhaust hydrocarbon from 

petroleum-fueled vehicles. The atomic hydrogen-to-carbon ratio of the equivalent 

hydrocarbon is 1.85:1.

Tractor has the meaning given for “truck tractor” in 49 CFR 571.3. This includes 

most heavy-duty vehicles specifically designed for the primary purpose of pulling 

trailers, but does not include vehicles designed to carry other loads. For purposes of this 

definition “other loads” would not include loads carried in the cab, sleeper compartment, 

or toolboxes. Examples of vehicles that are similar to tractors but that are not tractors

under this part include dromedary tractors, automobile haulers, straight trucks with 

trailers hitches, and tow trucks. Note that the provisions of this part that apply for 

tractors do not apply for tractors that are classified as vocational tractors under 

§1037.630. 

Ultimate purchaser means, with respect to any new vehicle, the first person who in 

good faith purchases such new vehicle for purposes other than resale.

United States has the meaning given in 40 CFR 1068.30.
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Upcoming model year means for a vehicle family the model year after the one 

currently in production.

U.S.-directed production volume means the number of vehicle units, subject to the 

requirements of this part, produced by a manufacturer for which the manufacturer has a 

reasonable assurance that sale was or will be made to ultimate purchasers in the United 

States This does not include vehicles certified to state emission standards that are 

different than the emission standards in this part. 

Useful life means the period during which a vehicle is required to comply with all 

applicable emission standards. 

Vehicle means equipment intended for use on highways that meets the criteria of 

paragraph (1)(i) or (ii) of this definition, as follows:

(1) The following equipment are vehicles:

(i) A piece of equipment that is intended for self-propelled use on highways becomes 

a vehicle when it includes at least an engine, a transmission, and a frame. (Note: For 

purposes of this definition, any electrical, mechanical, and/or hydraulic devices 

attached to engines for the purpose of powering wheels are considered to be 

transmissions.) 

(ii) A piece of equipment that is intended for self-propelled use on highways becomes 

a vehicle when it includes a passenger compartment attached to a frame with axles.

(2) Vehicles may be complete or incomplete vehicles as follows:

(i) A complete vehicle is a functioning vehicle that has the primary load carrying 

device or container (or equivalent equipment) attached. Examples of equivalent 

equipment would include fifth wheel trailer hitches, firefighting equipment, and 

utility booms. 

(ii) An incomplete vehicle is a vehicle that is not a complete vehicle. Incomplete 

vehicles may also be cab-complete vehicles. This may include vehicles sold to 

secondary vehicle manufacturers.

(iii) The primary use of the terms “complete vehicle” and “incomplete vehicle” are to 

distinguish whether a vehicle is complete when it is first sold as a vehicle.

(iv) You may ask us to allow you to certify a vehicle as incomplete if you 

manufacture the engines and sell the unassembled chassis components, as long as you 

do not produce and sell the body components necessary to complete the vehicle.

(3) Equipment such as trailers that are not self-propelled are not “vehicles” under this part 

1037.

Vehicle configuration means a unique combination of vehicle hardware and 
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calibration (related to measured or modeled emissions) within a vehicle family. Vehicles 

with hardware or software differences, but that have no hardware or software differences 

related to measured or modeled emissions may be included in the same vehicle 

configuration. Note that vehicles with hardware or software differences related to 

measured or modeled emissions are considered to be different configurations even if they

have the same GEM inputs and FEL. Vehicles within a vehicle configuration differ only 

with respect to normal production variability or factors unrelated to measured or modeled 

emissions.

Vehicle family has the meaning given in § 1037.230.

Vehicle service class means a vehicle’s weight class as specified in this definition. 

Note that, while vehicle service class is similar to primary intended service class for 

engines, they are not necessarily the same. For example, a medium heavy-duty vehicle 

may include a light heavy-duty engine. Note also that while spark-ignition engines do 

not have a primary intended service class, vehicles using spark-ignition engines have a 

vehicle service class.

(1) Light heavy-duty vehicles are those vehicles with GVWR below 19,500 pounds. 

Vehicles In this class include heavy-duty pickup trucks and vans, motor homes and

other recreational vehicles, and some straight trucks with a single rear axle. Typical 

applications would include personal transportation, light-load commercial delivery, 

passenger service, agriculture, and construction.

(2) Medium heavy-duty vehicles are those vehicles with GVWR from 19,500 to 

33,000 pounds. Vehicles in this class include school buses, straight trucks with a 

single rear axle, city tractors, and a variety of special purpose vehicles such as small 

dump trucks, and refuse trucks. Typical applications would include commercial short 

haul and intra-city delivery and pickup. 

(3) Heavy heavy-duty vehicles are those vehicles with GVWR above 33,000 pounds. 

Vehicles in this class include tractors, urban buses, and other heavy trucks. 

Vehicle subfamily or subfamily means a subset of a vehicle family including vehicles 

subject to the same FEL(s).

Vocational means relating to a vehicle subject to the standards of § 1037.105 

(including vocational tractors).

Vocational tractor means a vehicle classified as a vocational tractor under §1037.630.

Void has the meaning given in 40 CFR 1068.30.

Volatile liquid fuel means any fuel other than diesel or biodiesel that is a liquid at 

atmospheric pressure and has a Reid Vapor Pressure higher than 2.0 pounds per square 

inch.

We (us, our) means the Administrator of the Environmental Protection Agency and 
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any authorized representatives.

§ 1037.805 Symbols, acronyms, and abbreviations.

The following symbols, acronyms, and abbreviations apply to this part:

ABT Averaging, banking, and trading.

AECD auxiliary emission control device.

CD drag coefficient.

CDA drag area.

CFD computational fluid dynamics.

CFR Code of Federal Regulations.

CH4 methane.

CO carbon monoxide.

CO2 carbon dioxide.

CREE carbon-related exhaust emissions.

DOT Department of Transportation.

EPA Environmental Protection Agency.

ETW equivalent test weight.

FEL Family Emission Limit.

g grams.

GAWR gross axle weight rating.

GCWR gross combination weight rating.

GVWR gross vehicle weight rating.

GWP global-warming potential.

HC hydrocarbon.

ISO International Organization for Standardization.

kg kilograms.

m meter.

mm millimeter

mph miles per hour.

N2O nitrous oxide.

NARA National Archives and Records Administration.

NHTSA National Highway Transportation Safety Administration.

NOx oxides of nitrogen (NO and NO2).

PM particulate matter.

PTO power take-off.

RESS rechargeable energy storage system.

RPM revolutions per minute.

SAE Society of Automotive Engineers.

SKU Stock-keeping unit.

TRRL Tire rolling resistance level.

U.S.C. United States Code.

VSL vehicle speed limiter.

WF work factor.

§ 1037.810 Incorporation by reference.

(a) Certain material is incorporated by reference into this part with the approval of the 

Director of the Federal Register under 5 U.S.C. 552(a) and 1 CFR part 51. To enforce any 

edition other than that specified in this section, the Environmental Protection Agency

must publish a notice of the change in the Federal Register and the material must be 
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available to the public. All approved material is available for inspection at U.S. EPA, Air 

and Radiation Docket and Information Center, 1301 Constitution Ave., NW., Room 

B102, EPA West Building, Washington, DC 20460, (202) 202-1744, and is available 

from the sources listed below. It is also available for inspection at the National Archives 

and Records Administration (NARA). For information on the availability of this material 

at NARA, call 202–741–6030, or go to 

http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.

(b) International Organization for Standardization, Case Postale 56, CH-1211 Geneva 

20, Switzerland, (41) 22749 0111, www.iso.org, or central@iso.org.

(1) ISO 28580:2009(E) “Passenger car, truck and bus tyres – Methods of measuring 

rolling resistance – Single point test and correlation of measurement results”, First 

Edition, July 1, 2009; IBR approved for § 1037.520(c). 

(2) [Reserved]

(c) U.S. EPA, Office of Air and Radiation, 2565 Plymouth Road, Ann Arbor, MI 48105, 

www.epa.gov/:

(1) GEM simulation tool, Version 2.0, [Insert signature date]; IBR approved for 

§ 1037.520. The computer code for this model is available as noted in paragraph (a) 

of this section. A working version of this software is also available for download at 

www.epa.gov/otaq/climate/gemodel.htm. 

(2) [Reserved]

(d) SAE Material. The following material is available from the Society of Automotive 

Engineers. Copies of these materials may be obtained from Society of Automotive 

Engineers World Headquarters, 400 Commonwealth Dr., Warrendale, PA 15096–0001, 

phone (877) 606–7323 (U.S. and Canada) or (724) 776–4970 (outside the U.S. and 

Canada), or at http://www.sae.org. 

(1) SAE J1252, SAE Wind Tunnel Test Procedure for Trucks and Buses, Revised 

July 1981, IBR approved for § 1037.521(d), (e), and (f). 

(2) SAE J1594, Vehicle Aerodynamics Terminology, Revised July 2010, IBR 

approved for § 1037.521(d).

(3) SAE J2071, Aerodynamic Testing of Road Vehicles - Open Throat Wind Tunnel 

Adjustment, Revised June 1994, IBR approved for § 1037.521(d).

§ 1037.815 What provisions apply to confidential information?

The provisions of 40 CFR 1068.10 apply for information you consider confidential.

§ 1037.820 Requesting a hearing.

(a) You may request a hearing under certain circumstances, as described elsewhere in this 

part. To do this, you must file a written request, including a description of your objection 

and any supporting data, within 30 days after we make a decision.

(b) For a hearing you request under the provisions of this part, we will approve your 

request if we find that your request raises a substantial factual issue.
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(c) If we agree to hold a hearing, we will use the procedures specified in 40 CFR part 

1068, subpart G.

§ 1037.825 Reporting and recordkeeping requirements.

(a) This part includes various requirements to submit and record data or other 

information. Unless we specify otherwise, store required records in any format and on 

any media and keep them readily available for eight years after you send an associated 

application for certification, or eight years after you generate the data if they do not 

support an application for certification. You may not rely on anyone else to meet 

recordkeeping requirements on your behalf unless we specifically authorize it. We may 

review these records at any time. You must promptly send us organized, written records 

in English if we ask for them. We may require you to submit written records in an 

electronic format. 

(b) The regulations in § 1037.255, 40 CFR 1068.25, and 40 CFR 1068.101 describe your 

obligation to report truthful and complete information. This includes information not 

related to certification. Failing to properly report information and keep the records we 

specify violates 40 CFR 1068.101(a)(2), which may involve civil or criminal penalties. 

(c) Send all reports and requests for approval to the Designated Compliance Officer (see 

§ 1037.801).

(d) Any written information we require you to send to or receive from another company 

is deemed to be a required record under this section. Such records are also deemed to be 

submissions to EPA. Keep these records for eight years unless the regulations specify a 

different period. We may require you to send us these records whether or not you are a 

certificate holder.

(e) Under the Paperwork Reduction Act (44 U.S.C. 3501 et seq), the Office of 

Management and Budget approves the reporting and recordkeeping specified in the 

applicable regulations. The following items illustrate the kind of reporting and 

recordkeeping we require for vehicles regulated under this part:

(1) We specify the following requirements related to vehicle certification in this part 

1037:

(i) In subpart C of this part we identify a wide range of information required to 

certify vehicles.

(ii) In subpart G of this part we identify several reporting and recordkeeping items 

for making demonstrations and getting approval related to various special 

compliance provisions. 

(iii) In § 1037.725, 1037.730, and 1037.735 we specify certain records related to 

averaging, banking, and trading.
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(2) We specify the following requirements related to testing in 40 CFR part 1066:

(i) In 40 CFR 1065.2 we give an overview of principles for reporting information.

(ii) In 40 CFR 1065.10 and 1065.12 we specify information needs for establishing 

various changes to published test procedures.

(iii) In 40 CFR 1065.25 we establish basic guidelines for storing test information.

(iv) In 40 CFR 1065.695 we identify data that may be appropriate for collecting 

during testing of in-use vehicles using portable analyzers.

Appendix I to part 1037 — Heavy-duty Transient Chassis Test Cycle
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Time Speed Speed

sec. mph m/s

1 0.00 0.00

2 0.00 0.00

3 0.00 0.00

4 0.00 0.00

5 0.00 0.00

6 0.00 0.00

7 0.41 0.18

8 1.18 0.53

9 2.26 1.01

10 3.19 1.43

11 3.97 1.77

12 4.66 2.08

13 5.32 2.38

14 5.94 2.66

15 6.48 2.90

16 6.91 3.09

17 7.28 3.25

18 7.64 3.42

19 8.02 3.59

20 8.36 3.74

21 8.60 3.84

22 8.74 3.91

23 8.82 3.94

24 8.82 3.94

25 8.76 3.92

26 8.66 3.87

27 8.58 3.84

28 8.52 3.81

29 8.46 3.78

30 8.38 3.75

31 8.31 3.71

32 8.21 3.67

33 8.11 3.63

34 8.00 3.58

35 7.94 3.55

36 7.94 3.55

37 7.80 3.49

38 7.43 3.32

39 6.79 3.04

40 5.81 2.60

41 4.65 2.08

42 3.03 1.35

43 1.88 0.84

44 1.15 0.51

45 1.14 0.51

46 1.12 0.50

47 1.11 0.50

48 1.19 0.53

49 1.57 0.70

50 2.31 1.03

51 3.37 1.51

52 4.51 2.02

53 5.56 2.49

54 6.41 2.87

55 7.09 3.17

56 7.59 3.39

57 7.99 3.57

58 8.32 3.72

59 8.64 3.86

60 8.91 3.98

61 9.13 4.08

62 9.29 4.15

63 9.40 4.20

64 9.39 4.20

65 9.20 4.11

66 8.84 3.95

67 8.35 3.73

68 7.81 3.49

69 7.22 3.23

70 6.65 2.97

71 6.13 2.74

72 5.75 2.57

73 5.61 2.51

74 5.65 2.53

75 5.80 2.59

76 5.95 2.66

77 6.09 2.72

78 6.21 2.78

79 6.31 2.82

80 6.34 2.83

81 6.47 2.89

82 6.65 2.97

83 6.88 3.08

84 7.04 3.15

85 7.05 3.15

86 7.01 3.13

87 6.90 3.08

88 6.88 3.08

89 6.89 3.08

90 6.96 3.11

91 7.04 3.15

92 7.17 3.21

93 7.29 3.26

94 7.39 3.30

95 7.48 3.34

96 7.57 3.38

97 7.61 3.40

98 7.59 3.39

99 7.53 3.37

100 7.46 3.33

101 7.40 3.31

102 7.39 3.30

103 7.38 3.30

104 7.37 3.29

105 7.37 3.29

106 7.39 3.30

107 7.42 3.32

108 7.43 3.32

109 7.40 3.31

110 7.39 3.30

111 7.42 3.32

112 7.50 3.35

113 7.57 3.38

114 7.60 3.40

115 7.60 3.40

116 7.61 3.40

117 7.64 3.42

118 7.68 3.43

119 7.74 3.46

120 7.82 3.50

121 7.90 3.53

122 7.96 3.56

123 7.99 3.57

124 8.02 3.59

125 8.01 3.58

126 7.87 3.52

127 7.59 3.39

128 7.20 3.22

129 6.52 2.91

130 5.53 2.47

131 4.36 1.95

132 3.30 1.48

133 2.50 1.12

134 1.94 0.87

135 1.56 0.70

136 0.95 0.42

137 0.42 0.19

138 0.00 0.00
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139 0.00 0.00

140 0.00 0.00

141 0.00 0.00

142 0.00 0.00

143 0.00 0.00

144 0.00 0.00

145 0.00 0.00

146 0.00 0.00

147 0.00 0.00

148 0.00 0.00

149 0.00 0.00

150 0.00 0.00

151 0.00 0.00

152 0.00 0.00

153 0.00 0.00

154 0.00 0.00

155 0.00 0.00

156 0.00 0.00

157 0.00 0.00

158 0.00 0.00

159 0.00 0.00

160 0.00 0.00

161 0.00 0.00

162 0.00 0.00

163 0.00 0.00

164 0.00 0.00

165 0.00 0.00

166 0.00 0.00

167 0.00 0.00

168 0.00 0.00

169 0.00 0.00

170 0.00 0.00

171 0.00 0.00

172 1.11 0.50

173 2.65 1.18

174 4.45 1.99

175 5.68 2.54

176 6.75 3.02

177 7.59 3.39

178 7.75 3.46

179 7.63 3.41

180 7.67 3.43

181 8.70 3.89

182 10.20 4.56

183 11.92 5.33

184 12.84 5.74

185 13.27 5.93

186 13.38 5.98

187 13.61 6.08

188 14.15 6.33

189 14.84 6.63

190 16.49 7.37

191 18.33 8.19

192 20.36 9.10

193 21.47 9.60

194 22.35 9.99

195 22.96 10.26

196 23.46 10.49

197 23.92 10.69

198 24.42 10.92

199 24.99 11.17

200 25.91 11.58

201 26.26 11.74

202 26.38 11.79

203 26.26 11.74

204 26.49 11.84

205 26.76 11.96

206 27.07 12.10

207 26.64 11.91

208 25.99 11.62

209 24.77 11.07

210 24.04 10.75

211 23.39 10.46

212 22.73 10.16

213 22.16 9.91

214 21.66 9.68

215 21.39 9.56

216 21.43 9.58

217 20.67 9.24

218 17.98 8.04

219 13.15 5.88

220 7.71 3.45

221 3.30 1.48

222 0.88 0.39

223 0.00 0.00

224 0.00 0.00

225 0.00 0.00

226 0.00 0.00

227 0.00 0.00

228 0.00 0.00

229 0.00 0.00

230 0.00 0.00

231 0.00 0.00

232 0.00 0.00

233 0.00 0.00

234 0.00 0.00

235 0.00 0.00

236 0.00 0.00

237 0.00 0.00

238 0.00 0.00

239 0.00 0.00

240 0.00 0.00

241 0.00 0.00

242 0.00 0.00

243 0.00 0.00

244 0.00 0.00

245 0.00 0.00

246 0.00 0.00

247 0.00 0.00

248 0.00 0.00

249 0.00 0.00

250 0.00 0.00

251 0.00 0.00

252 0.00 0.00

253 0.00 0.00

254 0.00 0.00

255 0.00 0.00

256 0.00 0.00

257 0.00 0.00

258 0.00 0.00

259 0.50 0.22

260 1.57 0.70

261 3.07 1.37

262 4.57 2.04

263 5.65 2.53

264 6.95 3.11

265 8.05 3.60

266 9.13 4.08

267 10.05 4.49

268 11.62 5.19

269 12.92 5.78

270 13.84 6.19

271 14.38 6.43

272 15.64 6.99

273 17.14 7.66

274 18.21 8.14

275 18.90 8.45

276 19.44 8.69

277 20.09 8.98

278 21.89 9.79

279 24.15 10.80
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280 26.26 11.74

281 26.95 12.05

282 27.03 12.08

283 27.30 12.20

284 28.10 12.56

285 29.44 13.16

286 30.78 13.76

287 32.09 14.35

288 33.24 14.86

289 34.46 15.40

290 35.42 15.83

291 35.88 16.04

292 36.03 16.11

293 35.84 16.02

294 35.65 15.94

295 35.31 15.78

296 35.19 15.73

297 35.12 15.70

298 35.12 15.70

299 35.04 15.66

300 35.08 15.68

301 35.04 15.66

302 35.34 15.80

303 35.50 15.87

304 35.77 15.99

305 35.81 16.01

306 35.92 16.06

307 36.23 16.20

308 36.42 16.28

309 36.65 16.38

310 36.26 16.21

311 36.07 16.12

312 35.84 16.02

313 35.96 16.08

314 36.00 16.09

315 35.57 15.90

316 35.00 15.65

317 34.08 15.24

318 33.39 14.93

319 32.20 14.39

320 30.32 13.55

321 28.48 12.73

322 26.95 12.05

323 26.18 11.70

324 25.38 11.35

325 24.77 11.07

326 23.46 10.49

327 22.39 10.01

328 20.97 9.37

329 20.09 8.98

330 18.90 8.45

331 18.17 8.12

332 16.48 7.37

333 15.07 6.74

334 12.23 5.47

335 10.08 4.51

336 7.71 3.45

337 7.32 3.27

338 8.63 3.86

339 10.77 4.81

340 12.65 5.66

341 13.88 6.20

342 15.03 6.72

343 15.64 6.99

344 16.99 7.60

345 17.98 8.04

346 19.13 8.55

347 18.67 8.35

348 18.25 8.16

349 18.17 8.12

350 18.40 8.23

351 19.63 8.78

352 20.32 9.08

353 21.43 9.58

354 21.47 9.60

355 21.97 9.82

356 22.27 9.96

357 22.69 10.14

358 23.15 10.35

359 23.69 10.59

360 23.96 10.71

361 24.27 10.85

362 24.34 10.88

363 24.50 10.95

364 24.42 10.92

365 24.38 10.90

366 24.31 10.87

367 24.23 10.83

368 24.69 11.04

369 25.11 11.23

370 25.53 11.41

371 25.38 11.35

372 24.58 10.99

373 23.77 10.63

374 23.54 10.52

375 23.50 10.51

376 24.15 10.80

377 24.30 10.86

378 24.15 10.80

379 23.19 10.37

380 22.50 10.06

381 21.93 9.80

382 21.85 9.77

383 21.55 9.63

384 21.89 9.79

385 21.97 9.82

386 21.97 9.82

387 22.01 9.84

388 21.85 9.77

389 21.62 9.67

390 21.62 9.67

391 22.01 9.84

392 22.81 10.20

393 23.54 10.52

394 24.38 10.90

395 24.80 11.09

396 24.61 11.00

397 23.12 10.34

398 21.62 9.67

399 19.90 8.90

400 18.86 8.43

401 17.79 7.95

402 17.25 7.71

403 16.91 7.56

404 16.75 7.49

405 16.75 7.49

406 16.87 7.54

407 16.37 7.32

408 16.37 7.32

409 16.49 7.37

410 17.21 7.69

411 17.41 7.78

412 17.37 7.77

413 16.87 7.54

414 16.72 7.47

415 16.22 7.25

416 15.76 7.05

417 14.72 6.58

418 13.69 6.12

419 12.00 5.36

420 10.43 4.66
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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421 8.71 3.89

422 7.44 3.33

423 5.71 2.55

424 4.22 1.89

425 2.30 1.03

426 1.00 0.45

427 0.00 0.00

428 0.61 0.27

429 1.19 0.53

430 1.61 0.72

431 1.53 0.68

432 2.34 1.05

433 4.29 1.92

434 7.25 3.24

435 10.20 4.56

436 12.46 5.57

437 14.53 6.50

438 16.22 7.25

439 17.87 7.99

440 19.74 8.82

441 21.01 9.39

442 22.23 9.94

443 22.62 10.11

444 23.61 10.55

445 24.88 11.12

446 26.15 11.69

447 26.99 12.07

448 27.56 12.32

449 28.18 12.60

450 28.94 12.94

451 29.83 13.34

452 30.78 13.76

453 31.82 14.22

454 32.78 14.65

455 33.24 14.86

456 33.47 14.96

457 33.31 14.89

458 33.08 14.79

459 32.78 14.65

460 32.39 14.48

461 32.13 14.36

462 31.82 14.22

463 31.55 14.10

464 31.25 13.97

465 30.94 13.83

466 30.71 13.73

467 30.56 13.66

468 30.79 13.76

469 31.13 13.92

470 31.55 14.10

471 31.51 14.09

472 31.47 14.07

473 31.44 14.05

474 31.51 14.09

475 31.59 14.12

476 31.67 14.16

477 32.01 14.31

478 32.63 14.59

479 33.39 14.93

480 34.31 15.34

481 34.81 15.56

482 34.20 15.29

483 32.39 14.48

484 30.29 13.54

485 28.56 12.77

486 26.45 11.82

487 24.79 11.08

488 23.12 10.34

489 20.73 9.27

490 18.33 8.19

491 15.72 7.03

492 13.11 5.86

493 10.47 4.68

494 7.82 3.50

495 5.70 2.55

496 3.57 1.60

497 0.92 0.41

498 0.00 0.00

499 0.00 0.00

500 0.00 0.00

501 0.00 0.00

502 0.00 0.00

503 0.00 0.00

504 0.00 0.00

505 0.00 0.00

506 0.00 0.00

507 0.00 0.00

508 0.00 0.00

509 0.00 0.00

510 0.00 0.00

511 0.00 0.00

512 0.00 0.00

513 0.00 0.00

514 0.00 0.00

515 0.00 0.00

516 0.00 0.00

517 0.00 0.00

518 0.00 0.00

519 0.00 0.00

520 0.00 0.00

521 0.00 0.00

522 0.50 0.22

523 1.50 0.67

524 3.00 1.34

525 4.50 2.01

526 5.80 2.59

527 6.52 2.91

528 6.75 3.02

529 6.44 2.88

530 6.17 2.76

531 6.33 2.83

532 6.71 3.00

533 7.40 3.31

534 7.67 3.43

535 7.33 3.28

536 6.71 3.00

537 6.41 2.87

538 6.60 2.95

539 6.56 2.93

540 5.94 2.66

541 5.45 2.44

542 5.87 2.62

543 6.71 3.00

544 7.56 3.38

545 7.59 3.39

546 7.63 3.41

547 7.67 3.43

548 7.67 3.43

549 7.48 3.34

550 7.29 3.26

551 7.29 3.26

552 7.40 3.31

553 7.48 3.34

554 7.52 3.36

555 7.52 3.36

556 7.48 3.34

557 7.44 3.33

558 7.28 3.25

559 7.21 3.22

560 7.09 3.17

561 7.06 3.16
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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562 7.29 3.26

563 7.75 3.46

564 8.55 3.82

565 9.09 4.06

566 10.04 4.49

567 11.12 4.97

568 12.46 5.57

569 13.00 5.81

570 14.26 6.37

571 15.37 6.87

572 17.02 7.61

573 18.17 8.12

574 19.21 8.59

575 20.17 9.02

576 20.66 9.24

577 21.12 9.44

578 21.43 9.58

579 22.66 10.13

580 23.92 10.69

581 25.42 11.36

582 25.53 11.41

583 26.68 11.93

584 28.14 12.58

585 30.06 13.44

586 30.94 13.83

587 31.63 14.14

588 32.36 14.47

589 33.24 14.86

590 33.66 15.05

591 34.12 15.25

592 35.92 16.06

593 37.72 16.86

594 39.26 17.55

595 39.45 17.64

596 39.83 17.81

597 40.18 17.96

598 40.48 18.10

599 40.75 18.22

600 41.02 18.34

601 41.36 18.49

602 41.79 18.68

603 42.40 18.95

604 42.82 19.14

605 43.05 19.25

606 43.09 19.26

607 43.24 19.33

608 43.59 19.49

609 44.01 19.67

610 44.35 19.83

611 44.55 19.92

612 44.82 20.04

613 45.05 20.14

614 45.31 20.26

615 45.58 20.38

616 46.00 20.56

617 46.31 20.70

618 46.54 20.81

619 46.61 20.84

620 46.92 20.98

621 47.19 21.10

622 47.46 21.22

623 47.54 21.25

624 47.54 21.25

625 47.54 21.25

626 47.50 21.23

627 47.50 21.23

628 47.50 21.23

629 47.31 21.15

630 47.04 21.03

631 46.77 20.91

632 45.54 20.36

633 43.24 19.33

634 41.52 18.56

635 39.79 17.79

636 38.07 17.02

637 36.34 16.25

638 34.04 15.22

639 32.45 14.51

640 30.86 13.80

641 28.83 12.89

642 26.45 11.82

643 24.27 10.85

644 22.04 9.85

645 19.82 8.86

646 17.04 7.62

647 14.26 6.37

648 11.52 5.15

649 8.78 3.93

650 7.17 3.21

651 5.56 2.49

652 3.72 1.66

653 3.38 1.51

654 3.11 1.39

655 2.58 1.15

656 1.66 0.74

657 0.67 0.30

658 0.00 0.00

659 0.00 0.00

660 0.00 0.00

661 0.00 0.00

662 0.00 0.00

663 0.00 0.00

664 0.00 0.00

665 0.00 0.00

666 0.00 0.00

667 0.00 0.00

668 0.00 0.00
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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Appendix II to part 1037 — Power Take-Off Test Cycle

Cycle 

Simulation

Mode Start 

Time 

of 

Mode

Normalized 

Pressure, Circuit 1 

(%)

Normalized 

Pressure, Circuit 2 

(%)

Utility 0 0 0.0 0.0

Utility 1 33 80.5 0.0

Utility 2 40 0.0 0.0

Utility 3 145 83.5 0.0

Utility 4 289 0.0 0.0

Refuse 5 361 0.0 13.0

Refuse 6 363 0.0 38.0

Refuse 7 373 0.0 53.0

Refuse 8 384 0.0 73.0

Refuse 9 388 0.0 0.0

Refuse 10 401 0.0 13.0

Refuse 11 403 0.0 38.0

Refuse 12 413 0.0 53.0

Refuse 13 424 0.0 73.0

Refuse 14 442 11.2 0.0

Refuse 15 468 29.3 0.0

Refuse 16 473 0.0 0.0

Refuse 17 486 11.2 0.0

Refuse 18 512 29.3 0.0

Refuse 19 517 0.0 0.0

Refuse 20 530 12.8 11.1

Refuse 21 532 12.8 38.2

Refuse 22 541 12.8 53.4

Refuse 23 550 12.8 73.5

Refuse 24 553 0.0 0.0

Refuse 25 566 12.8 11.1

Refuse 26 568 12.8 38.2

Refuse 27 577 12.8 53.4

Refuse 28 586 12.8 73.5

Refuse 29 589 0.0 0.0

Refuse 30 600 0.0 0.0
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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Appendix III to part 1037 —Emission Control Identifiers

This appendix identifies abbreviations for emission control information labels, as 

required under §1037.135.

Vehicle Speed Limiters

-VSL – Vehicle speed limiter 

-VSLS – “Soft-top” vehicle speed limiter

-VSLE – Expiring vehicle speed limiter

-VSLD – Vehicle speed limiter with both “soft-top” and expiration

Idle Reduction Technology

-IRT5 – Engine shutoff after 5 minutes or less of idling

-IRTE – Expiring engine shutoff

Tires

-LRRA – Low rolling resistance tires (all)

 -LRRD – Low rolling resistance tires (drive)

 -LRRS – Low rolling resistance tires (steer)

Aerodynamic Components

-ATS – Aerodynamic side skirt and/or fuel tank fairing

-ARF – Aerodynamic roof fairing

-ARFR – Adjustable height aerodynamic roof fairing

-TGR – Gap reducing fairing (tractor to trailer gap)
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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Other Components

-ADVH – Vehicle includes advanced hybrid technology components 

-ADVO – Vehicle includes other advanced technology components (i.e., non-hybrid 

system)

-INV – Vehicle includes innovative technology components

PART 1039— CONTROL OF EMISSIONS FROM NEW AND IN-USE 

NONROAD COMPRESSION-IGNITION ENGINES

35. The authority citation for part 1039 continues to read as follows: 

Authority: 42 U.S.C. 7401-7671q.

Subpart F—[Amended]

36. Section 1039.510 is amended by revising paragraph (b) before the equation to read as 

follows: 

§1039.510 Which duty cycles do I use for transient testing?

* ** * *

(b) The transient test sequence consists of an initial run through the transient duty cycle 

from a cold start, 20 minutes with no engine operation, then a final run through the same 

transient duty cycle. Calculate the official transient emission result from the following 

equation:

* * * * *

PART 1065—ENGINE-TESTING PROCEDURES

37. The authority citation for part 1065 continues to read as follows: 

Authority: 42 U.S.C. 7401-7671q.
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Subpart A—[Amended]

38. Section 1065.1 is amended by adding paragraph (h) to read as follows: 

§1065.1 Applicability.

* ** * *

(h) 40 CFR part 1066 describes how to measure emissions from vehicles that are subject 

to standards in g/mile or g/kilometer. Those vehicle testing provisions extensively

reference portions of this part 1065. See 40 CFR part 1066 and the standard-setting part 

for additional information.

39. Section 1065.15 is amended by revising paragraph (e) to read as follows: 

§1065.15 Overview of procedures for laboratory and field testing.

* ** * *

(e) The following figure illustrates the allowed measurement configurations described in 

this part 1065:
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Figure 1 of §1065.15—Default test procedures and other specified procedures.

Power

Continuous Fuel

& BSFC 

Torque

& Speed 

Total Emissions

Batch 

Constant

Dilution Ratio

Partial Flow 

Dilute 

Varying

Dilution Ratio

Full Flow 

Brake- specific Emissions for

Transient Duty Cycle Testing

Emissions Rate Total Work

Raw Gaseous 

Default procedures

Other specified procedures

Alternate procedure

approval required

Alternate procedure

approval required for PM

Power

Continuous Fuel

& BSFC 

Torque

& Speed 

Total Emissions

Batch 

Constant

Dilution Ratio

Partial Flow 

Dilute 

Varying

Dilution Ratio

Full Flow 

Brake- specific Emissions for

Transient Duty Cycle Testing

Emissions Rate Total Work

Raw Gaseous 

Default procedures

Other specified procedures

Alternate procedure 

approval required for PM

Power

Continuous Fuel

& BSFC 

Torque

& Speed 

Total Emissions

Batch 

Constant

Dilution Ratio

Partial Flow 

Dilute 

Varying

Dilution Ratio

Full Flow 

Brake- specific Emissions for

Transient Duty Cycle Testing

Emissions Rate Total Work

Raw Gaseous 

Default procedures

Other specified procedures

Alternate procedure

approval required

Alternate procedure

approval required for PM

Power

Continuous Fuel

& BSFC 

Torque

& Speed 

Total Emissions

Batch 

Constant

Dilution Ratio

Partial Flow 

Dilute 

Varying

Dilution Ratio

Full Flow 

Brake- specific Emissions for

Transient Duty Cycle Testing

Emissions Rate Total Work

Raw Gaseous 

Default procedures

Other specified procedures

Alternate procedure 

approval required for PM

Power

Continuous

Raw Gaseous 

Fuel

& BSFC 

Torque

& Speed 

Total Emissions

Batch 

Constant

Dilution Ratio

Partial Flow 

Dilute 

Varying

Dilution Ratio

Full Flow 

Brake-specific Emissions for

Steady-state Duty Cycle Testing

Emissions Rate Total Work

Default procedures

Other specified procedures

Alternate procedure

approval required

Power

Continuous

Raw Gaseous 

Fuel

& BSFC 

Torque

& Speed 

Total Emissions

Batch 

Constant

Dilution Ratio

Partial Flow 

Dilute 

Varying

Dilution Ratio

Full Flow 

Brake-specific Emissions for

Steady-state Duty Cycle Testing

Emissions Rate Total Work

Default procedures

Other specified procedures

Power

Continuous

Raw Gaseous 

Fuel

& BSFC 

Torque

& Speed 

Total Emissions

Batch 

Constant

Dilution Ratio

Partial Flow 

Dilute 

Varying

Dilution Ratio

Full Flow 

Brake-specific Emissions for

Steady-state Duty Cycle Testing

Emissions Rate Total Work

Default procedures

Other specified procedures

Alternate procedure

approval required

Power

Continuous

Raw Gaseous 

Fuel

& BSFC 

Torque

& Speed 

Total Emissions

Batch 

Constant

Dilution Ratio

Partial Flow 

Dilute 

Varying

Dilution Ratio

Full Flow 

Brake-specific Emissions for

Steady-state Duty Cycle Testing

Emissions Rate Total Work

Default procedures

Other specified procedures

Power

Continuous Fuel

& BSFC 

Torque

& Speed 

Total Emissions

Batch 

Constant

Dilution Ratio

Partial Flow 

Dilute 

Varying

Dilution Ratio

Full Flow 

Brake- specific Emissions for

Field Testing

Emissions Rate Total Work

Raw Gaseous 

Default procedures

Other specified procedures

Alternate procedure

approval required

Power

Continuous Fuel

& BSFC 

Torque

& Speed 

Total Emissions

Batch 

Constant

Dilution Ratio

Partial Flow 

Dilute 

Varying

Dilution Ratio

Full Flow 

Brake- specific Emissions for

Field Testing

Emissions Rate Total Work

Raw Gaseous 

Default procedures

Other specified procedures

Power

Continuous Fuel

& BSFC 

Torque

& Speed 

Total Emissions

Batch 

Constant

Dilution Ratio

Partial Flow 

Dilute 

Varying

Dilution Ratio

Full Flow 

Brake- specific Emissions for

Field Testing

Emissions Rate Total Work

Raw Gaseous 

Default procedures

Other specified procedures

Alternate procedure

approval required

Power

Continuous Fuel

& BSFC 

Torque

& Speed 

Total Emissions

Batch 

Constant

Dilution Ratio

Partial Flow 

Dilute 

Varying

Dilution Ratio

Full Flow 

Brake- specific Emissions for

Field Testing

Emissions Rate Total Work

Raw Gaseous 

Default procedures

Other specified procedures
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38. Section 1065.20 is amended by revising paragraphs (a) introductory text, (a)(1), and 

(e) to read as follows: 

§1065.20 Units of measure and overview of calculations.

(a) System of units. The procedures in this part generally follow the International System 

of Units (SI), as detailed in NIST Special Publication 811, “Guide for the Use of the 

International System of Units (SI),” which we incorporate by reference in §1065.1010. 

The following exceptions apply:

(1) We designate angular speed, fn, of an engine’s crankshaft in revolutions per minute 

(r/min), rather than the SI unit of radians per second (rad/s). This is based on the 

commonplace use of r/min in many engine dynamometer laboratories.

* * * * *

(e) Rounding. You are required to round certain final values, such as final emission 

values. You may round intermediate values when transferring data as long as you 

maintain at least six significant digits (which requires more than six decimal places for 

values less than 0.1), or all significant digits if fewer than six digits are available. Unless 

the standard-setting part specifies otherwise, do not round other intermediate values. 

Round values to the number of significant digits necessary to match the number of 

decimal places of the applicable standard or specification as described in this paragraph 

(e). Note that specifications expressed as percentages have infinite precision (as 

described in paragraph (e)(7) of this section). Use the following rounding convention, 

which is consistent with ASTM E29 and NIST SP 811 (incorporated by reference in 

§1065.1010):

(1) If the first (left-most) digit to be removed is less than five, remove all the appropriate 

digits without changing the digits that remain. For example, 3.141593 rounded to the 

second decimal place is 3.14.

(2) If the first digit to be removed is greater than five, remove all the appropriate digits 

and increase the lowest-value remaining digit by one. For example, 3.141593 rounded to 

the fourth decimal place is 3.1416.

(3) If the first digit to be removed is five with at least one additional non-zero digit 

following the five, remove all the appropriate digits and increase the lowest-value 

remaining digit by one. For example, 3.141593 rounded to the third decimal place is 

3.142.

(4) If the first digit to be removed is five with no additional non-zero digits following the 

five, remove all the appropriate digits, increase the lowest-value remaining digit by one if 

it is odd and leave it unchanged if it is even. For example, 1.75 and 1.750 rounded to the 

first decimal place are 1.8; while 1.85 and 1.850 rounded to the first decimal place are 
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also 1.8. Note that this rounding procedure will always result in an even number for the 

lowest-value digit.

(5) This paragraph (e)(5) applies if the regulation specifies rounding to an increment 

other than decimal places or powers of ten (to the nearest 0.01, 0.1, 1, 10, 100, etc.). To 

round numbers for these special cases, divide the quantity by the specified rounding 

increment. Round the result to the nearest whole number as described in paragraphs 

(e)(1) through (4) of this section. Multiply the rounded number by the specified rounding 

increment. This value is the desired result. For example, to round 0.90 to the nearest 0.2, 

divide 0.90 by 0.2 to get a result of 4.5, which rounds to 4. Multiplying 4 by 0.2 gives 

0.8, which is the result of rounding 0.90 to the nearest 0.2.

(6) The following tables further illustrate the rounding procedures specified in this 

paragraph (e):

Quantity

Rounding Increment

10 1 0.1 0.01

3.141593 0 3 3.1 3.14

123,456.789 123,460 123,457 123,456.8 123,456.79

5.500 10 6 5.5 5.50

4.500 0 4 4.5 4.50

Quantity

Rounding Increment

25 3 0.5 0.02

229.267 225 228 229.5 229.26

62.500 50 63 62.5 62.50

87.500 100 87 87.5 87.50

7.500 0 6 7.5 7.50

(7) This paragraph (e)(7) applies where we specify a limit or tolerance as some 

percentage of another value (such as ±2 % of a maximum concentration). You may show 

compliance with such specifications either by applying the percentage to the total value 

to calculate an absolute limit, or by converting the absolute value to a percentage by

dividing it by the total value. 

(i) Do not round either value (the absolute limit or the calculated percentage), except as 

specified in paragraph (e)(7)(ii) of this section. For example, assume we specify that an 

analyzer must have a repeatability of ±1 % of the maximum concentration or better, the 

maximum concentration is 1059 ppm, and you determine repeatability to be ±6.3 ppm. 

In this example, you could calculate an absolute limit of ±10.59 ppm (1059 ppm × 0.01) 

or calculate that the 6.3 ppm repeatability is equivalent to a repeatability of 

0.5949008498584 %.

(ii) Prior to July 1, 2013, you may treat tolerances (and equivalent specifications) 

specified in percentages as having fixed rather than infinite precision. For example, 2 % 

would be equivalent to 1.51 % to 2.50 % and 2.0 % would be equivalent to 1.951 % to 
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2.050 %. Note that this allowance applies whether or not the percentage is explicitly

specified as a percentage of another value.

(8) You may use measurement devices that incorporate internal rounding, consistent with 

the provisions of this paragraph (e)(8). You may use devices that use any rounding 

convention if they report six or more significant digits. You may use devices that report 

fewer than six digits, consistent with good engineering judgment and the accuracy, 

repeatability, and noise specifications of this part. Note that this provision does not 

necessarily require you to perform engineering analysis or keep records.

* * * * *

Subpart B—[Amended]

39. Section 1065.125 is amended by revising paragraph (e)(1) introductory text to read 

as follows:

§1065.125 Engine intake air.

* * * * *

(e) * * *

(1) Use a charge-air cooling system with a total intake-air capacity that represents 

production engines’ in-use installation. Design any laboratory charge-air cooling system 

to minimize accumulation of condensate. Drain any accumulated condensate. Before 

starting a duty cycle (or preconditioning for a duty cycle), completely close all drains that 

would normally be closed during in-use operation. Keep those drains closed during the 

emission test. Maintain coolant conditions as follows:

* * * * *

40. Section 1065.140 is amended by revising paragraphs (c)(6)(ii)(C) and (D) to read as 

follows:

§1065.140 Dilution for gaseous and PM constituents.

* * * * *

(c) * * *

(6) * * *

(ii) * * *

(C) Identify the maximum potential mole fraction of dilute exhaust lost on a continuous 

basis during the entire test interval. This value must be less than or equal to 0.02. 

Calculate on a continuous basis the mole fraction of water that would be in equilibrium 

with liquid water at the measured minimum surface temperature. Subtract this mole 

fraction from the mole fraction of water that would be in the exhaust without 

condensation (either measured or from the chemical balance), and set any negative values 
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to zero. This difference is the potential mole fraction of the dilute exhaust that would be 

lost due to water condensation on a continuous basis. 

(D) Integrate the product of the molar flow rate of the dilute exhaust and the potential 

mole fraction of dilute exhaust lost, and divide by the totalized dilute exhaust molar flow 

over the test interval. This is the potential mole fraction of the dilute exhaust that would 

be lost due to water condensation over the entire test interval. Note that this assumes no 

re-evaporation. This value must be less than or equal to 0.005.

* * * * *

41. Section 1065.170 is amended by revising paragraph (c)(1)(vi) to read as follows:

§1065.170 Batch sampling for gaseous and PM constituents.

* * * * *

(c) * * *

(1) * * *

(vi) Maintain a filter face velocity near 100 cm/s with less than 5% of the recorded flow 

values exceeding 100 cm/s, unless you expect the net PM mass on the filter to exceed 400 

μg, assuming a 38 mm diameter filter stain area. Measure face velocity as the volumetric 

flow rate of the sample at the pressure upstream of the filter and temperature of the filter 

face as measured in §1065.140(e), divided by the filter's exposed area. You may use the 

exhaust stack or CVS tunnel pressure for the upstream pressure if the pressure drop 

through the PM sampler up to the filter is less than 2 kPa.

* * * * *

42. Section 1065.190 is amended by revising Table 1 to read as follows:

§1065.190 PM-stabilization and weighing environments for gravimetric analysis.

* * * * *

(d) * * *

Table 1 of §1065.190—Dewpoint tolerance

as a function of % PM change and % sulfuric acid PM

Expected sulfuric

acid fraction of PM

±0.5 % PM

mass change

±1 % PM

mass change

±2 % PM

mass change

5 % ±3 C ±6 C ±12 C

50 % ±0.3 C ±0.6 C ±1.2 C

100 % ±0.15 C ±0.3 C ±0.6 C

* * * * *

Subpart C—[Amended]
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43. Section 1065.205 is amended by revising Table 1 to read as follows:

§1065.205 Performance specifications for measurement instruments.

Your test system as a whole must meet all the applicable calibrations, verifications, and 

test-validation criteria specified in subparts D and F of this part or subpart J of this part 

for using PEMS and for performing field testing. We recommend that your instruments 

meet the specifications in Table 1 of this section for all ranges you use for testing. We 

also recommend that you keep any documentation you receive from instrument 

manufacturers showing that your instruments meet the specifications in Table 1 of this 

section.
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Table 1 of §1065.205–Recommended performance specifications for measurement instruments

Measurement Instrument

Measured 

quantity 

symbol

Complete System

Rise time (t10-90) and 

Fall time (t90-10)

a

Recording

update frequency

Accuracyb Repeatabilityb Noiseb

Engine speed transducer fn 1 s 1 Hz means

2 % of pt. or

0.5 % of max.

1 % of pt. or

0.25 % of max.

0.05 % of max

Engine torque transducer T 1 s 1 Hz means

2 % of pt. or

1 % of max.

1 % of pt. or

0.5 % of max

0.05 % of max.

Electrical work (active-power 

meter) W 1 s 1 Hz means

2 % of pt. or

0.5 % of max.

1 % of pt. or

0.25 % of max.

0.05 % of max

General pressure transducer (not a 

part of another instrument) p 5 s 1 Hz

2 % of pt. or

1.0 % of max.

1 % of pt. or

0.5 % of max.

0.1 % of max

Atmospheric pressure meter used 

for PM-stabilization and balance 

environments

patmos 50 s 5 times per hour 50 Pa 25 Pa 5 Pa

General purpose atmospheric 

pressure meter patmos 50 s 5 times per hour 250 Pa 100Pa 50 Pa

Temperature sensor for PMstabilization and balance 

environments

T 50 s 0.1 Hz 0.25 K 0.1 K 0.1 K
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Other temperature sensor (not a 

part of another instrument) T 10 s 0.5 Hz

0.4 % of pt. K or

0.2 % of max. K

0.2 % of pt. K or

0.1 % of max. K

0.1 % of max

Dewpoint sensor for intake air, 

PM-stabilization and balance 

environments

Tdew 50 s 0.1 Hz 0.25 K 0.1 K 0.02 K

Other dewpoint sensor Tdew 50 s 0.1 Hz 1 K 0.5 K 0.1 K

Fuel flow meterc

(Fuel totalizer)

m

5 s

(N/A)

1 Hz

(N/A)

2 % of pt. or

1.5 % of max.

1 % of pt. or

0.75 % of max.

0.5 % of max.

Total diluted exhaust meter (CVS) c

(With heat exchanger before meter)

n

1 s

(5 s)

1 Hz means

(1 Hz)

2 % of pt. or

1.5 % of max.

1 % of pt. or

0.75 % of max.

1 % of max.

Dilution air, inlet air, exhaust, and 

sample flow metersc n 1 s 1 Hz means of 5 Hz samples

2.5 % of pt. or

1.5 % of max.

1.25 % of pt. or

0.75 % of max.

1 % of max.

Continuous gas analyzer x 5 s 1 Hz

2 % of pt. or

2 % of meas.

1 % of pt. or

1 % of meas.

1 % of max.

Batch gas analyzer x N/A N/A

2 % of pt. or

2 % of meas.

1 % of pt. or

1 % of meas.

1 % of max.

Gravimetric PM balance mPM N/A N/A See §1065.790 0.5 g N/A

Inertial PM balance mPM 5 s 1 Hz 2 % of pt. or 1 % of pt. or 0.2 % of max.
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2 % of meas. 1 % of meas.

a The performance specifications identified in the table apply separately for rise time and fall time.

b Accuracy, repeatability, and noise are all determined with the same collected data, as described in §1065.305, and based on absolute values. “pt.” refers to the overall flowweighted mean value expected at the standard; “max.” refers to the peak value expected at the standard over any test interval, not the maximum of the instrument’s range; “meas” 

refers to the actual flow-weighted mean measured over any test interval.

c The procedure for accuracy, repeatability and noise measurement described in §1065.305 may be modified for flow meters to allow noise to be measured at the lowest calibrated 

value instead of zero flow rate.
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4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.

16.

17.

18.

19.

20.

21.

22.

23.

24.

25.

26.

27.

28.

29.

30.

31.

32.

33.

34.

35.

36.

37.

38.

39.

40.

41.

42.

43.

44. Section 1065.220 is amended by revising paragraph (a) and adding a new paragraph 

(a)(1)(iii) to read as follows:

§1065.220 Fuel flow meter.

* ** * *
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(a) Application. You may use fuel flow in combination with a chemical balance of fuel, 

inlet air, and raw exhaust to calculate raw exhaust flow as described in §1065.655(e), as 

follows: 

(1) * * *

(i) * * *

(ii) * * *

(iii) For calculating the dilution air flow for background correction as described in 

§1065.667.

* ** * *

45. Section 1065.225 is amended by revising paragraph (a) and adding new paragraphs 

(a)(1)(iii) and (a)(1)(iv) to read as follows:

§1065.225 Intake-air flow meter.

* ** * *

(a) Application. You may use an intake-air flow meter in combination with a chemical 

balance of fuel, inlet air, and raw exhaust to calculate raw exhaust flow as described in 

§1065.655(e) and (f), as follows:

(1) * * *

(i) * * *

(ii) * * *

(iii) For validating minimum dilution ratio for PM batch sampling as described in 

§1065.546.

(iv) For calculating the dilution air flow for background correction as described in 

§1065.667.

* ** * *

46. Section 1065.250 is amended by revising the introductory heading and paragraphs 

(a) and (b) to read as follows:

§1065.250 Nondispersive infrared analyzer.
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(a) Application. Use a nondispersive infrared (NDIR) analyzer to measure CO and CO2

concentrations in raw or diluted exhaust for either batch or continuous sampling.

(b) Component requirements. We recommend that you use an NDIR analyzer that meets 

the specifications in Table 1 of §1065.205. Note that your NDIR-based system must 

meet the calibration and verifications in §1065.350 and §1065.355 and it must also meet 

the linearity verification in §1065.307. You may use an NDIR analyzer that has 

compensation algorithms that are functions of other gaseous measurements and the 

engine’s known or assumed fuel properties. The target value for any compensation 

algorithm is 0 % (that is, no bias high and no bias low), regardless of the uncompensated 

signal’s bias.

* ** * *

47. Section 1065.260 is amended by revising paragraphs (a), (b), (c), and (e) and adding 

paragraph (f) to read as follows:

§1065.260 Flame-ionization detector.

* ** * *

(a) Application. Use a flame-ionization detector (FID) analyzer to measure hydrocarbon 

concentrations in raw or diluted exhaust for either batch or continuous sampling. 

Determine hydrocarbon concentrations on a carbon number basis of one, C1. For 

measuring THC or THCE you must use a FID analyzer. For measuring CH4 you must 

meet the requirements of paragraph (f) of this section. See subpart I of this part for 

special provisions that apply to measuring hydrocarbons when testing with oxygenated 

fuels.

(b) Component requirements. We recommend that you use a FID analyzer that meets the 

specifications in Table 1 of §1065.205. Note that your FID-based system for measuring 

THC, THCE, or CH4 must meet all the verifications for hydrocarbon measurement in 

subpart D of this part, and it must also meet the linearity verification in §1065.307. You 

may use a FID analyzer that has compensation algorithms that are functions of other 

gaseous measurements and the engine’s known or assumed fuel properties. The target 

value for any compensation algorithm is 0 % (that is, no bias high and no bias low), 

regardless of the uncompensated signal’s bias.

(c) Heated FID analyzers. For measuring THC or THCE from compression-ignition 

engines, two-stroke spark-ignition engines, and four-stroke spark-ignition engines below 

19 kW, you must use heated FID analyzers that maintain all surfaces that are exposed to 

emissions at a temperature of (191 ±11) °C.

(d) * * *
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(e) NMHC. For demonstrating compliance with NMHC standards, you may either 

measure THC and CH4 and determine NMHC as described in §1065.660(b)(2) or (3), or 

you may measure THC and determine NMHC as described in §1065.660(b)(1).

(f) CH4. For reporting CH4 or for demonstrating compliance with CH4 standards, you 

may use a FID analyzer with a nonmethane cutter as described in §1065.265 or you may

use a GC-FID as described in §1065.267. Determine CH4 as described in §1065.660(c).

48. Section 1065.265 is amended by revising paragraph (b) to read as follows:

§1065.265 Nonmethane cutter.

* ** * *

(b) System performance. Determine nonmethane-cutter performance as described in 

§1065.365 and use the results to calculate CH4 or NMHC emissions in §1065.660.

* ** * *

49. Section 1065.267 is amended by revising paragraphs (a) and (b) to read as follows:

§1065.267 Gas chromatograph with a flame ionization detector.

* ** * *

(a) Application. You may use a gas chromatograph with a flame ionization detector (GCFID)to measure CH4 concentrations of diluted exhaust for batch sampling. While you 

may also use a nonmethane cutter to measure CH4, as described in §1065.265, use a 

reference procedure based on a gas chromatograph for comparison with any proposed 

alternate measurement procedure under §1065.10.

(b) Component requirements. We recommend that you use a GC-FID that meets the 

specifications in Table 1 of §1065.205, and it must also meet the linearity verification in 

§1065.307.

50. Section 1065.267 is amended by revising paragraphs (a) and (b) to read as follows:

§1065.270 Chemiluminescent detector.

* ** * *

(b) Component requirements. We recommend that you use a CLD that meets the 

specifications in Table 1 of §1065.205. Note that your CLD-based system must meet the 

quench verification in §1065.370 and it must also meet the linearity verification in 
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§1065.307. You may use a heated or unheated CLD, and you may use a CLD that 

operates at atmospheric pressure or under a vacuum. You may use a CLD that has 

compensation algorithms that are functions of other gaseous measurements and the 

engine’s known or assumed fuel properties. The target value for any compensation 

algorithm is 0 % (that is, no bias high and no bias low), regardless of the uncompensated 

signal’s bias.

* ** * *

51. Section 1065.272 is amended by revising paragraph (b) to read as follows:

§1065.272 N2O measurement devices.

* ** * *

(b) Component requirements. We recommend that you use an NDUV analyzer that 

meets the specifications in Table 1 of §1065.205. Note that your NDUV-based system 

must meet the verifications in §1065.372 and it must also meet the linearity verification 

in §1065.307. You may use a NDUV analyzer that has compensation algorithms that are 

functions of other gaseous measurements and the engine’s known or assumed fuel 

properties. The target value for any compensation algorithm is 0 % (that is, no bias high 

and no bias low), regardless of the uncompensated signal’s bias.

* ** * *

52. Section 1065.275 is amended by revising paragraphs (b)(1), (b)(2), (b)(3), (b)(4), 

and (c) and adding a new paragraphs (b)(5) and (b)(6) to read as follows:

§1065.275 N2O measurement devices.

* ** * *

(b) * * *

(1) Nondispersive infrared (NDIR) analyzer. You may use an NDIR analyzer that has 

compensation algorithms that are functions of other gaseous measurements and the 

engine’s known or assumed fuel properties. The target value for any compensation 

algorithm is 0 % (that is, no bias high and no bias low), regardless of the uncompensated 

signal’s bias.

(2) Fourier transform infrared (FTIR) analyzer. You may use an FTIR analyzer that has 

compensation algorithms that are functions of other gaseous measurements and the 

engine’s known or assumed fuel properties. The target value for any compensation 

algorithm is 0 % (that is, no bias high and no bias low), regardless of the uncompensated 

signal’s bias. Use appropriate analytical procedures for interpretation of infrared spectra. 
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For example, EPA Test Method 320 is considered a valid method for spectral 

interpretation (see http://www.epa.gov/ttn/emc/methods/method320.html).

(3) Laser infrared analyzer. You may use a laser infrared analyzer that has compensation 

algorithms that are functions of other gaseous measurements and the engine’s known or 

assumed fuel properties. The target value for any compensation algorithm is 0 % (that is, 

no bias high and no bias low), regardless of the uncompensated signal’s bias. Examples 

of laser infrared analyzers are pulsed-mode high-resolution narrow band mid-infrared 

analyzers, and modulated continuous wave high-resolution narrow band mid-infrared 

analyzers.

(4) Photoacoustic analyzer. You may use a photoacoustic analyzer that has compensation 

algorithms that are functions of other gaseous measurements. The target value for any 

compensation algorithm is 0 % (that is, no bias high and no bias low), regardless of the 

uncompensated signal’s bias. Use an optical wheel configuration that gives analytical 

priority to measurement of the least stable components in the sample. Select a sample 

integration time of at least 5 seconds. Take into account sample chamber and sample line 

volumes when determining flush times for your instrument.

(5) Gas chromatograph analyzer. You may use a gas chromatograph with an electroncapture detector (GC-ECD) to measure N2O concentrations of diluted exhaust for batch 

sampling.

(i)You may use a packed or porous layer open tubular (PLOT) column phase of suitable 

polarity and length to achieve adequate resolution of the N2O peak for analysis. 

Examples of acceptable columns are a PLOT column consisting of bonded polystyrenedivinylbenzene or a Porapack Q packed column. Take the column temperature profile 

and carrier gas selection into consideration when setting up your method to achieve 

adequate N2O peak resolution.

(ii) Use good engineering judgment to zero your instrument and correct for drift. You do 

not need to follow the specific procedures in §1065.530 and §1065.550(b) that would 

otherwise apply. For example, you may perform a span gas measurement before and 

after sample analysis without zeroing and use the average area counts of the pre-span and 

post-span measurements to generate a response factor (area counts/span gas 

concentration), which you then multiply by the area counts from your sample to generate 

the sample concentration.

(c) Interference verification. Perform interference verification for NDIR, FTIR, laser 

infrared analyzers, and photoacoustic analyzers using the procedures of §1065.375. 

Interference verification is not required for GC-ECD. Certain interference gases can 

positively interfere with NDIR, FTIR, and photoacoustic analyzers by causing a response 

similar to N2O. When running the interference verification for these analyzers, use 

interference gases as follows: 

(1) The interference gases for NDIR analyzers are CO, CO2, H2O, CH4, and SO2. Note 

that interference species, with the exception of H2O, are dependent on the N2O infrared 
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absorption band chosen by the instrument manufacturer. For each analyzer determine the 

N2O infrared absorption band. For each N2O infrared absorption band, use good 

engineering judgment to determine which interference gases to use in the verification.

(2) Use good engineering judgment to determine interference gases for FTIR, and laser 

infrared analyzers. Note that interference species, with the exception of H2O, are 

dependent on the N2O infrared absorption band chosen by the instrument manufacturer. 

For each analyzer determine the N2O infrared absorption band. For each N2O infrared 

absorption band, use good engineering judgment to determine interference gases to use in 

the verification.

(3) The interference gases for photoacoustic analyzers are CO, CO2, and H2O.

* * * * *

53. Section 1065.280 is amended by revising paragraph (b) to read as follows:

§1065.280 Paramagnetic and magnetopneumatic O2 detection analyzers.

* ** * *

(b) Component requirements. We recommend that you use a PMD or MPD analyzer that 

meets the specifications in Table 1 of §1065.205. Note that it must meet the linearity 

verification in §1065.307. You may use a PMD or MPD that has compensation 

algorithms that are functions of other gaseous measurements and the engine’s known or 

assumed fuel properties. The target value for any compensation algorithm is 0 % (that is, 

no bias high and no bias low), regardless of the uncompensated signal’s bias.

* * * * *

54. Section 1065.284 is amended by revising paragraph (b) to read as follows:

§1065.284 Zirconia (ZrO2) analyzer.

* ** * *

(b) Component requirements. We recommend that you use a ZrO2 analyzer that meets 

the specifications in Table 1 of §1065.205. Note that your ZrO2-based system must meet 

the linearity verification in §1065.307. You may use a Zirconia analyzer that has 

compensation algorithms that are functions of other gaseous measurements and the 

engine’s known or assumed fuel properties. The target value for any compensation 

algorithm is 0 % (that is, no bias high and no bias low), regardless of the uncompensated 

signal’s bias.
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* ** * *

55. Section 1065.290 is amended by revising paragraph (b) to read as follows:

§1065.295 PM inertial balance for field-testing analysis.

* ** * *

(b) Component requirements. We recommend that you use a balance that meets the 

specifications in Table 1 of §1065.205. Note that your balance-based system must meet 

the linearity verification in §1065.307. If the balance uses an internal calibration process 

for routine spanning and linearity verifications, the process must be NIST-traceable. You 

may use an inertial PM balance that has compensation algorithms that are functions of 

other gaseous measurements and the engine’s known or assumed fuel properties. The 

target value for any compensation algorithm is 0 % (that is, no bias high and no bias 

low), regardless of the uncompensated signal’s bias.

* * * * *

Subpart D—[Amended]

56. Section 1065.303 is amended by revising Table 1 of 1065.303 to read as follows:

§1065.303 Summary of required calibration and verifications.

The following table summarizes the required and recommended calibrations and 

verifications described in this subpart and indicates when these have to be performed:

Table 1 of §1065.303–Summary of required calibration and verifications.

Type of calibration or verification Minimum frequencya

§1065.305: Accuracy, repeatability and noise

Accuracy: Not required, but recommended for initial installation.

Repeatability: Not required, but recommended for initial 

installation.

Noise: Not required, but recommended for initial installation.

§1065.307: Linearity verification

Speed: Upon initial installation, within 370 days before testing 

and after major maintenance.

Torque: Upon initial installation, within 370 days before testing 
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and after major maintenance.

Electrical power: Upon initial installation, within 370 days before 

testing and after major maintenance.

Fuel flow rate: Upon initial installation, within 370 days before 

testing, and after major maintenance.

Intake-air, dilution air, diluted exhaust, and batch sampler flow 

rates: Upon initial installation, within 370 days before testing and 

after major maintenance, unless flow is verified by propane check 

or by carbon or oxygen balance.

Raw exhaust flow rate: Upon initial installation, within 185 days 

before testing and after major maintenance, unless flow is verified 

by propane check or by carbon or oxygen balance.

Gas dividers: Upon initial installation, within 370 days before 

testing, and after major maintenance.

Gas analyzers (unless otherwise noted): Upon initial installation, 

within 35 days before testing and after major maintenance.

FTIR and photoacoustic analyzers: Upon initial installation, 

within 370 days before testing and after major maintenance.

GC-ECD: Upon initial installation and after major maintenance.

PM balance: Upon initial installation, within 370 days before 

testing and after major maintenance.

Pressure, temperature, and dewpoint: Upon initial installation, 

within 370 days before testing and after major maintenance.

§1065.308: Continuous gas analyzer system 

response and updating-recording verification—

for gas analyzers not continuously compensated 

for other gas species

Upon initial installation or after system modification that would 

affect response.

§1065.309: Continuous gas analyzer systemresponse and updating-recording verification—

for gas analyzers continuously compensated for 

other gas species

Upon initial installation or after system modification that would 

affect response.

§1065.310: Torque Upon initial installation and after major maintenance.

§1065.315: Pressure, temperature, dewpoint Upon initial installation and after major maintenance.

§1065.320: Fuel flow Upon initial installation and after major maintenance.

§1065.325: Intake flow Upon initial installation and after major maintenance.
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§1065.330: Exhaust flow Upon initial installation and after major maintenance.

§1065.340: Diluted exhaust flow (CVS) Upon initial installation and after major maintenance.

§1065.341: CVS and batch sampler verificationb Upon initial installation, within 35 days before testing, and after 

major maintenance.

§1065.342 Sample dryer verification

For thermal chillers: upon installation and after major 

maintenance.

For osmotic membranes; upon installation, within 35 days of 

testing, and after major maintenance.

§1065.345: Vacuum leak

For laboratory testing: upon initial installation of the sampling 

system, within 8 hours before the start of the first test interval of 

each duty-cycle sequence, and after maintenance such as pre-filter 

changes.

For field testing: after each installation of the sampling system on 

the vehicle, prior to the start of the field test, and after 

maintenance such as pre-filter changes.

§1065.350: CO2 NDIR H2O interference Upon initial installation and after major maintenance.

§1065.355: CO NDIR CO2 and H2O interference Upon initial installation and after major maintenance.

§1065.360: FID calibration

THC FID optimization, and THC FID 

verification.

Calibrate all FID analyzers: upon initial installation and after 

major maintenance.

Optimize and determine CH4response for THC FID analyzers:

upon initial installation and after major maintenance.

Verify CH4response for THC FID analyzers: upon initial 

installation, within 185 days before testing, and after major 

maintenance.

§1065.362: Raw exhaust FID O2interference

For all FID analyzers: upon initial installation, and after major 

maintenance.

For THC FID analyzers: upon initial installation, after major 

maintenance, and after FID optimization according to §1065.360.

§1065.365: Nonmethane cutter penetration Upon initial installation, within 185 days before testing, and after 

major maintenance.
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§1065.370: CLD CO2 and H2O quench Upon initial installation and after major maintenance.

§1065.372: NDUV HC and H2O interference Upon initial installation and after major maintenance.

§1065.375: N2O analyzer interference Upon initial installation and after major maintenance.

§1065.376: Chiller NO2 penetration Upon initial installation and after major maintenance.

§1065.378: NO2-to-NO converter conversion Upon initial installation, within 35 days before testing, and after 

major maintenance.

§1065.390: PM balance and weighing

Independent verification: upon initial installation, within 370 days 

before testing, and after major maintenance.

Zero, span, and reference sample verifications: within 12 hours of 

weighing, and after major maintenance.

§1065.395: Inertial PM balance and weighing

Independent verification: upon initial installation, within 370 days 

before testing, and after major maintenance.

Other verifications: upon initial installation and after major 

maintenance.

a

Perform calibrations and verifications more frequently, according to measurement system manufacturer instructions 

and good engineering judgment.

bThe CVS verification described in §1065.341 is not required for systems that agree within ±2 % based on a chemical 

balance of carbon or oxygen of the intake air, fuel, and diluted exhaust.

* ** * *

57. Section 1065.307 is amended by revising paragraph (a) and Table 1 of 1065.307 to 

read as follows:

§1065.307 Linearity verification.

(a) Scope and frequency. Perform a linearity verification on each measurement system 

listed in Table 1 of this section at least as frequently as indicated in Table 1 of §1065.303, 

consistent with measurement system manufacturer recommendations and good 

engineering judgment. Note that this linearity verification may replace requirements we 

previously referred to as “calibrations”. The intent of a linearity verification is to 

determine that a measurement system responds proportionally over the measurement 

range of interest. A linearity verification generally consists of introducing a series of at 

least 10 reference values to a measurement system. The measurement system quantifies 

each reference value. The measured values are then collectively compared to the 
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reference values by using a least squares linear regression and the linearity criteria 

specified in Table 1 of this section.

(b) * * *
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Table 1 of §1065.307–Measurement systems that require linearity verifications.

Measurement 

system Quantity

Linearity criteria

| xmin(a1-1)+a0| a1 SEE r

2

Speed fn

≤ 0.05 % · nmax f 0.98-1.02 ≤ 2 % · nmax f ≥ 0.990

Torque T ≤ 1 % · Tmax 0.98-1.02 ≤ 2 % · Tmax ≥ 0.990

Electrical power P ≤ 1 % · Pmax 0.98-1.02 ≤ 2 % · Pmax ≥ 0.990

Fuel flow rate m ≤ 1 % · mmax

 0.98-1.02 ≤ 2 % · mmax ≥ 0.990

Intake-air

flow rate

n ≤ 1 % · max

n 0.98-1.02 ≤ 2 % · maxn ≥ 0.990

Dilution air

flow rate

n ≤ 1 % · max

n 0.98-1.02 ≤ 2 % · max

n ≥ 0.990

Diluted exhaust

flow rate

n ≤ 1 % · max

n 0.98-1.02 ≤ 2 % · maxn ≥ 0.990

Raw exhaust

flow rate

n ≤ 1 % · max

n 0.98-1.02 ≤ 2 % · maxn ≥ 0.990

Batch sampler

flow rates

n ≤ 1 % · max

n 0.98-1.02 ≤ 2 % · maxn ≥ 0.990

Gas dividers x/xspan ≤ 0.5 % · xmax/xspan 0.98-1.02 ≤ 2 % · xmax/xspan ≥ 0.990

Gas analyzers for 

laboratory testing x ≤ 0.5 % · max

x 0.99-1.01 ≤ 1 % · maxx ≥ 0.998
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Gas analyzers for 

field testing x ≤ 1 % · max

x 0.99-1.01 ≤ 1 % · maxx ≥ 0.998

PM balance m ≤ 1 % · mmax 0.99-1.01 ≤ 1 % · mmax ≥ 0.998

Pressures p ≤ 1 % · max

p 0.99-1.01 ≤ 1 % · maxp ≥ 0.998

Dewpoint for 

intake air, PMstabilization and 

balance 

environments

Tdew

≤ 0.5 % · 

Tdewmax

0.99-1.01 ≤ 0.5 % · Tdewmax ≥ 0.998

Other dewpoint 

measurements Tdew ≤ 1 % · Tdewmax 0.99-1.01 ≤ 1 % · Tdewmax ≥ 0.998

Analog-to-digital 

conversion of 

temperature 

signals

T ≤ 1 % · Tmax 0.99-1.01 ≤ 1 % · Tmax ≥ 0.998

58. Section 1065.340 is amended by revising paragraphs (b), (c), (d), (e), (f), (g) and (h) 

and adding paragraph (i) to read as follows:

§1065.340 Diluted exhaust flow (CVS) calibration.

* ** * *

(b) Scope and frequency. Perform this calibration while the flow meter is installed in its 

permanent position, except as allowed in paragraph (c) of this section. Perform this 

calibration after you change any part of the flow configuration upstream or downstream 

of the flow meter that may affect the flow-meter calibration. Perform this calibration 

upon initial CVS installation and whenever corrective action does not resolve a failure to 

meet the diluted exhaust flow verification (i.e., propane check) in §1065.341.

(c) Ex-situ CFV and SSV calibration. You may remove a CFV or SSV from its 

permanent position for calibration as long as it meets the following requirements when 

installed in the CVS:

(1) Upon installation of the CFV or SSV into the CVS, use good engineering judgment to 

verify that you have not introduced any leaks between the CVS inlet and the venturi.
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(2) After ex-situ venturi calibration, you must verify all venturi flow combinations for 

CFVs or at minimum of 10 flow points for an SSV using the propane check as described 

in §1065.341. Your propane check result for each venturi flow point may not exceed the 

tolerance in §1065.341(f)(5).

(3) To verify your ex-situ calibration for a CVS with more than a single CFV, perform 

the following check to verify that there are no flow meter entrance effects that can 

prevent you from passing this verification.

(i) Use a constant flow device like a CFO kit to deliver a constant flow of propane to the 

dilution tunnel. 

(ii) Measure hydrocarbon concentrations at a minimum of 10 separate flow rates for an 

SSV flow meter, or at all possible flow combinations for a CFV flow meter, while 

keeping the flow of propane constant. We recommend selecting CVS flow rates in a 

random order.

(iii) Measure the concentration of hydrocarbon background in the dilution air at the

beginning and end of this test. Subtract the average background concentration from each 

measurement at each flow point before performing the regression analysis in paragraph 

(c)(3)(iv) of this section.

(iv) Perform a power regression using all the paired values of flow rate and corrected 

concentration to obtain a relationship in the form of y = a · x

b

. Use concentration as the 

independent variable and flow rate as the dependent variable. For each data point, 

calculate the difference between the measured flow rate and the value represented by the 

curve fit. The difference at each point must be less than ±1 % of the appropriate 

regression value. The value of b must be between –1.005 and –0.995. If your results do 

not meet these limits, take corrective action consistent with §1065.341(a).

(d) Reference flow meter. Calibrate a CVS flow meter using a reference flow meter such 

as a subsonic venturi flow meter, a long-radius ASME/NIST flow nozzle, a smooth 

approach orifice, a laminar flow element, a set of critical flow venturis, or an ultrasonic 

flow meter. Use a reference flow meter that reports quantities that are NIST-traceable 

within ±1 % uncertainty. Use this reference flow meter’s response to flow as the 

reference value for CVS flow-meter calibration.

(e) Configuration. Do not use an upstream screen or other restriction that could affect the 

flow ahead of the reference flow meter, unless the flow meter has been calibrated with 

such a restriction.

(f) PDP calibration. Calibrate a positive-displacement pump (PDP) to determine a flowversus-PDP speed equation that accounts for flow leakage across sealing surfaces in the 

PDP as a function of PDP inlet pressure. Determine unique equation coefficients for 

each speed at which you operate the PDP. Calibrate a PDP flow meter as follows:

(1) Connect the system as shown in Figure 1 of this section.
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(2) Leaks between the calibration flow meter and the PDP must be less than 0.3 % of the 

total flow at the lowest calibrated flow point; for example, at the highest restriction and 

lowest PDP-speed point. 

(3) While the PDP operates, maintain a constant temperature at the PDP inlet within ±2 

% of the mean absolute inlet temperature, Tin .

(4) Set the PDP speed to the first speed point at which you intend to calibrate.

(5) Set the variable restrictor to its wide-open position.

(6) Operate the PDP for at least 3 min to stabilize the system. Continue operating the 

PDP and record the mean values of at least 30 seconds of sampled data of each of the 

following quantities:

(i) The mean flow rate of the reference flow meter, ref n . This may include several 

measurements of different quantities, such as reference meter pressures and temperatures, 

for calculating ref n .

(ii) The mean temperature at the PDP inlet, Tin .

(iii) The mean static absolute pressure at the PDP inlet, in p .

(iv) The mean static absolute pressure at the PDP outlet, out p .

(v) The mean PDP speed, nPDP f .

(7) Incrementally close the restrictor valve to decrease the absolute pressure at the inlet to 

the PDP, in p .

(8) Repeat the steps in paragraphs (e)(6) and (7) of this section to record data at a 

minimum of six restrictor positions ranging from the wide open restrictor position to the 

minimum expected pressure at the PDP inlet.

(9) Calibrate the PDP by using the collected data and the equations in §1065.640.

(10) Repeat the steps in paragraphs (e)(6) through (9) of this section for each speed at 

which you operate the PDP.

(11) Use the equations in §1065.642 to determine the PDP flow equation for emission 

testing.

(12) Verify the calibration by performing a CVS verification (i.e., propane check) as 

described in §1065.341.

(13) Do not use the PDP below the lowest inlet pressure tested during calibration.
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(g) CFV calibration. Calibrate a critical-flow venturi (CFV) to verify its discharge 

coefficient, Cd, at the lowest expected static differential pressure between the CFV inlet 

and outlet. Calibrate a CFV flow meter as follows:

(1) Connect the system as shown in Figure 1 of this section.

(2) Verify that any leaks between the calibration flow meter and the CFV are less than 

0.3 % of the total flow at the highest restriction.

(3) Start the blower downstream of the CFV.

(4) While the CFV operates, maintain a constant temperature at the CFV inlet within ±2 

% of the mean absolute inlet temperature, Tin .

(5) Set the variable restrictor to its wide-open position. Instead of a variable restrictor, 

you may alternately vary the pressure downstream of the CFV by varying blower speed 

or by introducing a controlled leak. Note that some blowers have limitations on 

nonloaded conditions.

(6) Operate the CFV for at least 3 min to stabilize the system. Continue operating the 

CFV and record the mean values of at least 30 seconds of sampled data of each of the 

following quantities:

(i) The mean flow rate of the reference flow meter, ref n . This may include several 

measurements of different quantities, such as reference meter pressures and temperatures, 

for calculating ref n .

(ii) The mean dewpoint of the calibration air, Tdew . See §1065.640 for permissible 

assumptions during emission measurements.

(iii) The mean temperature at the venturi inlet, Tin .

(iv) The mean static absolute pressure at the venturi inlet, in p .

(v) The mean static differential pressure between the CFV inlet and the CFV outlet, 

CFV p .

(7) Incrementally close the restrictor valve or decrease the downstream pressure to 

decrease the differential pressure across the CFV, CFV p .

(8) Repeat the steps in paragraphs (f)(6) and (7) of this section to record mean data at a 

minimum of ten restrictor positions, such that you test the fullest practical range of CFV p

expected during testing. We do not require that you remove calibration components or 

CVS components to calibrate at the lowest possible restrictions.
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(9) Determine Cd and the lowest allowable pressure ratio, r, according to §1065.640.

(10) Use Cd to determine CFV flow during an emission test. Do not use the CFV below 

the lowest allowed r, as determined in §1065.640.

(11) Verify the calibration by performing a CVS verification (i.e., propane check) as 

described in §1065.341.

(12) If your CVS is configured to operate more than one CFV at a time in parallel, 

calibrate your CVS by one of the following:

(i) Calibrate every combination of CFVs according to this section and §1065.640. Refer 

to §1065.642 for instructions on calculating flow rates for this option.

(ii) Calibrate each CFV according to this section and §1065.640. Refer to §1065.642 for 

instructions on calculating flow rates for this option.

(h) SSV calibration. Calibrate a subsonic venturi (SSV) to determine its calibration 

coefficient, Cd, for the expected range of inlet pressures. Calibrate an SSV flow meter as 

follows:

(1) Connect the system as shown in Figure 1 of this section.

(2) Verify that any leaks between the calibration flow meter and the SSV are less than 0.3 

% of the total flow at the highest restriction.

(3) Start the blower downstream of the SSV.

(4) While the SSV operates, maintain a constant temperature at the SSV inlet within ±2 

% of the mean absolute inlet temperature, Tin .

(5) Set the variable restrictor or variable-speed blower to a flow rate greater than the 

greatest flow rate expected during testing. You may not extrapolate flow rates beyond 

calibrated values, so we recommend that you make sure the Reynolds number, Re#, at the 

SSV throat at the greatest calibrated flow rate is greater than the maximum Re#expected 

during testing.

(6) Operate the SSV for at least 3 min to stabilize the system. Continue operating the 

SSV and record the mean of at least 30 seconds of sampled data of each of the following 

quantities:

(i) The mean flow rate of the reference flow meter ref n . This may include several 

measurements of different quantities, such as reference meter pressures and temperatures, 

for calculating ref n .

(ii) Optionally, the mean dewpoint of the calibration air, Tdew . See §1065.640 for 

permissible assumptions.
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(iii) The mean temperature at the venturi inlet, Tin .

(iv) The mean static absolute pressure at the venturi inlet, in p .

(v) Static differential pressure between the static pressure at the venturi inlet and the 

static pressure at the venturi throat, SSV p .

(7) Incrementally close the restrictor valve or decrease the blower speed to decrease the 

flow rate.

(8) Repeat the steps in paragraphs (g)(6) and (7) of this section to record data at a 

minimum of ten flow rates.

(9) Determine a functional form of Cd versus Re#by using the collected data and the 

equations in §1065.640.

(10) Verify the calibration by performing a CVS verification (i.e., propane check) as 

described in §1065.341 using the new Cd versus Re#equation.

(11) Use the SSV only between the minimum and maximum calibrated flow rates.

(12) Use the equations in §1065.642 to determine SSV flow during a test.

(i) Ultrasonic flow meter calibration. [Reserved]

* * * * *

59. Section 1065.341 is amended by revising paragraphs (a)(5), (a)(6), and (f)(5) and 

adding paragraph (a)(7) to read as follows:

§1065.341 CVS and batch sampler verification (propane check).

* ** * *

(a) * * *

(5) Change in CVS calibration. Perform a calibration of the CVS flow meter as described 

in §1065.340.

(6) Flow meter entrance effects. Inspect the CVS tunnel to determine whether the 

entrance effects from the piping configuration upstream of the flow meter adversely 

affect the flow measurement.

(7) Other problems with the CVS or sampling verification hardware or software. Inspect 

the CVS system, CVS verification hardware, and software for discrepancies.
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* ** * *

(f) * * *

(5) Subtract the reference C3H8 mass from the calculated mass. If this difference is 

within 2 % of the reference mass, the CVS passes this verification. If not, take 

corrective action as described in paragraph (a) of this section.

* ** * *

60. Section 1065.350 is amended by revising paragraph (d)(7) to read as follows:

§1065.350 H2O interference verification for CO2 NDIR analyzers.

* ** * *

(d) * * *

(7) While the analyzer measures the sample’s concentration, record 30 seconds of 

sampled data. Calculate the arithmetic mean of this data. The analyzer meets the 

interference verification if this value is within (0.0 ±0.4) mmol/mol.

* ** * *

61. Section 1065.360 is amended by revising paragraph (e) to read as follows:

§1065.360 FID optimization and verification.

* ** * *

(e) THC FID methane (CH4) response verification. This procedure is only for FID 

analyzers that measure THC. If the value of RFCH4[THC-FID] from paragraph (d) of this 

section is within 5 % of its most recent previously determined value, the THC FID 

passes the methane response verification. For example, if the most recent previous value 

for RFCH4[THC-FID] was 1.05 and it changed by 0.05 to become 1.10 or it changed by -

0.05 to become 1.00, either case would be acceptable because 4.8 % is less than 5 %. 

Verify RFCH4[THC-FID] as follows:

* ** * *

62. Section 1065.370 is amended by revising paragraph (g)(1) to read as follows:

§1065.370 CLD CO2 and H2O quench verification.
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* ** * *

(g) * * *

(1) You may omit this verification if you can show by engineering analysis that for your 

NOx sampling system and your emission calculation procedures, the combined CO2 and 

H2O interference for your NOx CLD analyzer always affects your brake-specific NOx

emission results within no more than 1 % of the applicable NOx standard. If you certify

to a combined emission standard (such as a NOx + NMHC standard), scale your NOx

results to the combined standard based on the measured results (after incorporating 

deterioration factors, if applicable). For example, if your final NOx + NMHC value is 

half of the emission standard, double the NOx result to estimate the level of NOx

emissions corresponding to the applicable standard.

* ** * *

63. Section 1065.372 is amended by revising paragraph (e)(1) to read as follows:

§1065.372 NDUV analyzer HC and H2O interference verification.

* ** * *

(e) * * *

(1) You may omit this verification if you can show by engineering analysis that for your 

NOx sampling system and your emission calculation procedures, the combined HC and 

H2O interference for your NOx NDUV analyzer always affects your brake-specific NOx

emission results by less than 0.5 % of the applicable NOx standard.

* ** * *

64. Section 1065.378 is amended by revising paragraph (d)(3)(iv) to read as follows:

§1065.378 NO2-to-NO converter conversion verification.

* ** * *

(d) * * *

(3) * * *

(iv) Switch the ozonator on and adjust the ozone generation rate so the NO measured by 

the analyzer is 20 percent of xNOref or a value which would simulate the maximum 

concentration of NO2 expected during testing, while maintaining at least 10 percent 

unreacted NO. This ensures that the ozonator is generating NO2 at the maximum 
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concentration expected during testing. Record the concentration of NO by calculating the 

mean of 30 seconds of sampled data from the analyzer and record this value as xNOmeas.

* * * * *

Subpart F—[Amended]

65. Section 1065.510 is amended by revising paragraphs (a) introductory text, (b)(5)(i), 

(b)(6), (c)(2), (c)(4), (d)(5), (f)(3)(i), (f)(5), and (g) and adding paragraphs (b)(7), 

(f)(3)(iii), and (h) to read as follows:

§1065.510 Engine mapping.

(a) Applicability, scope, and frequency. An engine map is a data set that consists of a 

series of paired data points that represent the maximum brake torque versus engine speed, 

measured at the engine's primary output shaft. Map your engine if the standard-setting 

part requires engine mapping to generate a duty cycle for your engine configuration. Map 

your engine while it is connected to a dynamometer or other device that can absorb work 

output from the engine's primary output shaft according to §1065.110. To establish speed 

and torque values for mapping, we generally recommend that you stabilize an engine for 

at least 15 seconds at each setpoint and record the mean feedback speed and torque of the 

last (4 to 6) seconds. Configure any auxiliary work inputs and outputs such as hybrid, 

turbo-compounding, or thermoelectric systems to represent their in-use configurations,

and use the same configuration for emission testing. See Figure 1 of §1065.210. This may

involve configuring initial states of charge and rates and times of auxiliary-work inputs 

and outputs. We recommend that you contact the Designated Compliance Officer before 

testing to determine how you should configure any auxiliary-work inputs and outputs. 

Use the most recent engine map to transform a normalized duty cycle from the standardsetting part to a reference duty cycle specific to your engine. Normalized duty cycles are 

specified in the standard-setting part. You may update an engine map at any time by

repeating the engine-mapping procedure. You must map or re-map an engine before a test 

if any of the following apply:

* ** * *

(b) * * *

(5) * * *

(i) For any engine subject only to steady-state duty cycles, you may perform an engine 

map by using discrete speeds. Select at least 20 evenly spaced setpoints from 95% of 

warm idle speed to the highest speed above maximum power at which 50% of maximum 

power occurs. We refer to this 50% speed as the check point speed as described in 

paragraph (b)(5)(iii) of this section. At each setpoint, stabilize speed and allow torque to 
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stabilize. Record the mean speed and torque at each setpoint. Use linear interpolation to 

determine intermediate speeds and torques. Use this series of speeds and torques to 

generate the power map as described in paragraph (e) of this section.

* * * * *

(6) Use one of the following methods to determine warm high-idle speed for engines with 

a high-speed governor if they are subject to transient testing with a duty cycle that 

includes reference speed values above 100 %:

(i) You may use a manufacturer-declared warm high-idle speed if the engine is 

electronically governed. For engines with a high-speed governor that shuts off torque 

output at a manufacturer-specified speed and reactivates at a lower manufacturerspecified speed (such as engines that use ignition cut-off for governing), declare the 

middle of the specified speed range as the warm high-idle speed.

(ii) Measure the warm high-idle speed using the following procedure:

(A) Set operator demand to maximum and use the dynamometer to target zero torque on 

the engine’s primary output shaft. If the mean feedback torque is within ±1 % of Tmax 

mapped, you may use the observed mean feedback speed at that point as the measured warm 

high-idle speed.

(B) If the engine is unstable as a result of in-use production components (such as engines 

that use ignition cut-off for governing, as opposed to unstable dynamometer operation), 

you must use the mean feedback speed from paragraph (b)(6)(ii)(A) of this section as the 

measured warm high-idle speed. The engine is considered unstable if any of the 1 Hz 

speed feedback values are not within ±2 % of the calculated mean feedback speed. We 

recommend that you determine the mean as the value representing the midpoint between 

the observed maximum and minimum recorded feedback speed. 

(C) If your dynamometer is not capable of achieving a mean feedback torque within ±1 

% of Tmax mapped, operate the engine at a second point with operator demand set to 

maximum with the dynamometer set to target a torque equal to the recorded mean 

feedback torque on the previous point plus 20 % of Tmax mapped. Use this data point and 

the data point from paragraph (b)(6)(ii)(A) of this section to extrapolate the engine speed 

where torque is equal to zero. 

(D) You may use a manufacturer-declared Tmax instead of the measured Tmax mapped. If you 

do this, or if you are able to determine mean feedback speed as described in paragraphs 

(b)(6)(ii)(A) and (B) of this section, you may measure the warm high-idle speed before 

running the speed sweep specified in paragraph (b)(5) of this section. 

(7) For engines with a low-speed governor, if a nonzero idle torque is representative of 

in-use operation, operate the engine at warm idle with the manufacturer-declared idle 

torque. Set the operator demand to minimum, use the dynamometer to target the declared 

idle torque, and allow the engine to govern the speed. Measure this speed and use it as 

the warm idle speed for cycle generation in §1065.512. We recommend recording at 
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least 30 values of speed and using the mean of those values. If you identify multiple 

warm idle torques under paragraph (f)(4)(i) of this section, measure the warm idle speed 

at each torque. You may map the idle governor at multiple load levels and use this map 

to determine the measured warm idle speed at the declared idle torque(s).

(c) * * *

(2) Map the amount of negative torque required to motor the engine by repeating 

paragraph (b) of this section with minimum operator demand. You may start the negative 

torque map at either the minimum or maximum speed from paragraph (b) of this section.

* * * * *

(4) For engines with an electric hybrid system, you may create a negative torque map that 

would include the full negative torque of the electric hybrid system, so operator demand 

will be at a minimum when the reference duty cycle specifies negative torque values. 

(d) * * *

(5) Perform one of the following:

(i) For constant-speed engines subject only to steady-state testing, you may perform an 

engine map by using a series of discrete torques. Select at least five evenly spaced torque 

setpoints from no-load to 80 % of the manufacturer-declared test torque or to a torque 

derived from your published maximum power level if the declared test torque is 

unavailable. Starting at the 80 % torque point, select setpoints in 2.5 % intervals, 

stopping at the endpoint torque. The endpoint torque is defined as the first discrete 

mapped torque value greater than the torque at maximum observed power where the 

engine outputs 90 % of the maximum observed power; or the torque when engine stall 

has been determined using good engineering judgment (i.e. sudden deceleration of engine 

speed while adding torque). You may continue mapping at higher torque setpoints. At 

each setpoint, allow torque and speed to stabilize. Record the mean feedback speed and 

torque at each setpoint. From this series of mean feedback speed and torque values, use 

linear interpolation to determine intermediate values. Use this series of mean feedback 

speeds and torques to generate the power map as described in paragraph (e) of this 

section.

(ii) For any constant-speed engine, you may perform an engine map with a continuous 

torque sweep by continuing to record the mean feedback speed and torque at 1 Hz or 

more frequently. Use the dynamometer to increase torque. Increase the reference torque 

at a constant rate from no-load to the endpoint torque as defined in paragraph (d)(5)(i) of 

this section. You may continue mapping at higher torque setpoints. Unless the standardsetting part specifies otherwise, target a torque sweep rate equal to the manufacturerdeclared test torque (or a torque derived from your published power level if the declared 

test torque is not known) divided by 180 s. Stop recording after you complete the sweep. 

Verify that the average torque sweep rate over the entire map is within ±7 % of the target 

torque sweep rate. Use linear interpolation to determine intermediate values from this 

series of mean feedback speed and torque values. Use this series of mean feedback 
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speeds and torques to generate the power map as described in paragraph (e) of this 

section.

(iii) For electric power generation applications in which normal engine operation is 

limited to a specific speed range, map the engine with two points as described in this 

paragraph (d)(5)(iii). After stabilizing at the no-load governed speed in §1065.510(d)(4), 

record the mean feedback speed and torque. Continue to operate the engine with the 

governor or simulated governor controlling engine speed using operator demand, and 

control the dynamometer to target a speed of 97.5 % of the recorded mean no-load 

governed speed. If the in-use performance class of the electric power generation 

application is known, you may use those values in place of 97.5 % (e.g., for ISO 8528-5 

G3 Performance Class, the steady-state frequency band is less than or equal to 0.5 %, so 

use 99.75 % instead of 97.5 %). Allow speed and torque to stabilize. Record the mean 

feedback speed and torque. Record the target speed. The absolute value of the speed 

error (the mean feedback speed minus the target speed) must be no greater than 20 % of 

the difference between the recorded mean no-load governed speed and the target speed. 

From this series of two mean feedback speed and torque values, use linear interpolation 

to determine intermediate values. Use this series of two mean feedback speeds and 

torques to generate a power map as described in paragraph (e) of this section. Note that 

the measured maximum test torque determined in §1065.610(b)(1), will be the mean 

feedback torque recorded on the second point.

* * * * *

(f) * * *

(3) * * *

(i) You may use a declared value for maximum test speed for variable-speed engines if it 

is within (97.5 to 102.5) % of the corresponding measured value. You may use a higher 

declared speed if the length of the “vector” at the declared speed is within 2 % of the

length of the “vector” at the measured value. The term vector refers to the square root of 

the sum of normalized engine speed squared and the normalized full-load power (at that 

speed) squared, consistent with the calculations in §1065.610.

(ii) * * *

(iii) For electronically governed engines, you may use a declared warm high-idle speed 

for calculating the alternate maximum test speed as specified in §1065.610.

(4) * * *

(5) Optional declared torques. (i) For variable-speed engines you may declare a 

maximum torque over the engine operating range. You may use the declared value for 

measuring warm high-idle speed as specified in §1065.510.

(ii) For constant-speed engines you may declare a maximum test torque. You may use 

the declared value for cycle generation if it is within (95 to 100) % of the measured value.
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(g) Mapping variable-speed engines with an electric hybrid system. Map variable-speed 

engines that include electric hybrid systems as described in this paragraph (g). You may

ask to apply these provisions to other types of hybrid engines, consistent with good 

engineering judgment. However, do not use this procedure for engines used in hybrid 

vehicles where the hybrid system is certified as part of the vehicle rather than the engine. 

Follow the steps for mapping a variable-speed engine as given in paragraph (b)(5) of this 

section except as noted in this paragraph (g). You must generate one engine map with 

the hybrid system inactive as described in paragraph (g)(1) of this section, and a separate

map with the hybrid system active as described in paragraph (g)(2) of this section. See 

the standard-setting part to determine how to use these maps. The map with the system 

inactive is typically used to generate steady-state duty cycles, but may also be used to 

generate transient cycles, such as those that do not involve engine motoring. This hybridinactive map is also used for generating the hybrid-active map. The hybrid-active map is 

typically used to generate transient duty cycles that involve engine motoring. 

(1) Prepare the engine for mapping by either deactivating the hybrid system or by

operating the engine as specified in paragraph (b)(4) of this section and remaining at this 

condition until the rechargeable energy storage system (RESS) is depleted. Once the 

hybrid has been disabled or the RESS is depleted, perform an engine map as specified in 

paragraph (b)(5) of this section. If the RESS was depleted instead of deactivated, ensure 

that instantaneous power from the RESS remains less than 2 % of the instantaneous 

measured power from the engine (or engine-hybrid system) at all engine speeds. 

(2) The purpose of the mapping procedure in this paragraph (g) is to determine the 

maximum torque available at each speed, such as what might occur during transient 

operation with a fully charged RESS. Use one of the following methods to generate a 

hybrid-active map:

(i) Perform an engine map by using a series of continuous sweeps to cover the engine’s 

full range of operating speeds. Prepare the engine for hybrid-active mapping by ensuring 

that the RESS state of charge is representative of normal operation. Perform the sweep as 

specified in paragraph (b)(5)(ii) of this section, but stop the sweep to charge the RESS 

when the power measured from the RESS drops below the expected maximum power 

from the RESS by more than 2 % of total system power (including engine and RESS 

power). Unless good engineering judgment indicates otherwise, assume that the expected 

maximum power from the RESS is equal to the measured RESS power at the start of the 

sweep segment. For example, if the 3-second rolling average of total engine-RESS 

power is 200 kW and the power from the RESS at the beginning of the sweep segment is 

50 kW, once the power from the RESS reaches 46 kW, stop the sweep to charge the 

RESS. Note that this assumption is not valid where the hybrid motor is torque-limited. 

Calculate total system power as a 3-second rolling average of instantaneous total system 

power. After each charging event, stabilize the engine for 15 seconds at the speed at 

which you ended the previous segment with operator demand set to maximum before 

continuing the sweep from that speed. Repeat the cycle of charging, mapping, and 

recharging until you have completed the engine map. You may shut down the system or 

include other operation between segments to be consistent with the intent of this 

paragraph (g)(2)(i). For example, for systems in which continuous charging and 
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discharging can overheat batteries to an extent that affects performance, you may operate 

the engine at zero power from the RESS for enough time after the system is recharged to 

allow the batteries to cool. Use good engineering judgment to smooth the torque curve to 

eliminate discontinuities between map intervals.

(ii) Perform an engine map by using discrete speeds. Select map setpoints at intervals 

defined by the ranges of engine speed being mapped. From 95 % of warm idle speed to 

90 % of the expected maximum test speed, select setpoints that result in a minimum of 13 

equally spaced speed setpoints. From 90 % to 110 % of expected maximum test speed,

select setpoints in equally spaced intervals that are nominally 2 % of expected maximum 

test speed. Above 110 % of expected maximum test speed, select setpoints based on the 

same speed intervals used for mapping from 95 % warm idle speed to 90 % maximum 

test speed. You may stop mapping at the highest speed above maximum power at which 

50 % of maximum power occurs. We refer to the speed at 50 % power as the check point 

speed as described in paragraph (b)(5)(iii) of this section. Stabilize engine speed at each 

setpoint, targeting a torque value at 70 % of peak torque at that speed without hybridassist. Make sure the engine is fully warmed up and the RESS state of charge is within 

the normal operating range. Snap the operator demand to maximum, operate the engine 

there for at least 10 seconds, and record the 3-second rolling average feedback speed and 

torque at 1 Hz or higher. Record the peak 3-second average torque and 3-second average 

speed at that point. Use linear interpolation to determine intermediate speeds and 

torques. Follow §1065.610 (a) to calculate the maximum test speed. Verify that the 

measured maximum test speed falls in the range from 92 to 108 % of the estimated 

maximum test speed. If the measured maximum test speed does not fall in this range, 

rerun the map using the measured value of maximum test speed.

(h) Other mapping procedures. You may use other mapping procedures if you believe 

the procedures specified in this section are unsafe or unrepresentative for your engine. 

Any alternate techniques you use must satisfy the intent of the specified mapping 

procedures, which is to determine the maximum available torque at all engine speeds that 

occur during a duty cycle. Identify any deviations from this section’s mapping 

procedures when you submit data to us.

66. Section 1065.514 is amended by revising paragraph (f)(3) and Table 2 as follows:

§1065.514 Cycle-validation criteria for operation over specified duty cycles.

* ** * *

(f) * * *

(3) For discrete-mode steady-state testing, apply cycle-validation criteria by treating the 

sampling periods from the series of test modes as a continuous sampling period, 

analogous to ramped-modal testing and apply statistical criteria as described in paragraph 

(f)(1) or (2) of this section. Note that if the gaseous and particulate test intervals are 
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different periods of time, separate validations are required for the gaseous and particulate 

test intervals.

Table 2 of §1065.514—Default statistical criteria for validating duty cycles

Parameter Speed Torque Power

Slope, a1 0.950 ≤ a1 ≤ 1.030 0.830 ≤ a1 ≤ 1.030 0.830 ≤ a1 ≤ 1.030

Absolute value of 

intercept, |a0|

≤ 10 % of warm idle ≤ 2 % of maximum 

mapped torque

≤ 2 % of maximum 

mapped power

Standard error of 

estimate, SEE

≤ 5 % of maximum 

test speed

≤ 10 % of maximum 

mapped torque

≤ 10 % of maximum 

mapped power

Coefficient of 

determination, r

2 ≥ 0.970 ≥ 0.850 ≥ 0.910

* * * * *

67. Section 1065.520 is amended by revising paragraph (g) introductory paragraph, 

paragraphs (g)(5), (g)(7) and (g)(8) adding paragraph (g)(9) to read as follows:

§1065.520 Pre-test verification procedures and pre-test data collection.

* ** * *

(g) Verify the amount of nonmethane hydrocarbon contamination in the exhaust and 

background HC sampling systems within 8 hours before the start of the first test interval 

of each duty-cycle sequence for laboratory tests. You may verify the contamination of a 

background HC sampling system by reading the last bag fill and purge using zero gas. 

For any NMHC measurement system that involves separately measuring methane and 

subtracting it from a THC measurement or for any CH4 measurement system that uses an 

NMC, verify the amount of THC contamination using only the THC analyzer response. 

There is no need to operate any separate methane analyzer for this verification; however, 

you may measure and correct for THC contamination in the CH4 sample train for the 

cases where NMHC is determined by subtracting CH4 from THC or, where CH4 is 

determined, using an NMC as configured in §1065.365(d), (e), and (f); and using the 

calculations in §1065.660(b)(2). Perform this verification as follows:
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(1) * * *

(5) Measure the THC concentration in the sampling and background systems as follows:

(i) For continuous sampling, record the mean THC concentration as overflow zero gas 

flows.

(ii) For batch sampling, fill the sample medium (e.g., bag) and record its mean THC 

concentration.

(6) * * *

(7) You may correct the measured initial THC concentration for drift as follows:

(i) For batch and continuous HC analyzers, after determining the initial THC 

concentration, flow zero gas to the analyzer zero or sample port. When the analyzer 

reading is stable, record the mean analyzer value.

(ii) Flow span gas to the analyzer span or sample port. When the analyzer reading is 

stable, record the mean analyzer value.

(iii) Use mean analyzer values from paragraphs (g)(2), (3), (7)(i), and (7)(ii) of this 

section to correct the initial THC concentration recorded in paragraph (g)(6) of this 

section for drift, as described in §1065.550.

(8) If any of the xTHC[THC-FID]init values exceed the greatest of the following values, 

determine the source of the contamination and take corrective action, such as purging the 

system during an additional preconditioning cycle or replacing contaminated portions:

(i) 2 % of the flow-weighted mean wet, net concentration expected at the HC (THC or 

NMHC) standard.

(ii) 2 % of the flow-weighted mean wet, net concentration of HC (THC or NMHC) 

measured during testing.

(iii) 2 mol/mol.

(9) If corrective action does not resolve the deficiency, you may request to use the 

contaminated system as an alternate procedure under §1065.10.

* * * * *

68. Section 1065.525 is amended by revising paragraph (a) and removing paragraph 

(c)(4).

§1065.525 Engine starting, restarting, and shutdown.
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(a) For test intervals that require emission sampling during engine starting, start the 

engine using one of the following methods:

(1) Start the engine as recommended in the owners manual using a production starter 

motor or air-start system and either an adequately charged battery, a suitable power 

supply, or a suitable compressed air source.

(2) Use the dynamometer to start the engine. To do this, motor the engine within ±25 % 

of its typical in-use cranking speed. Stop cranking within 1 second of starting the engine.

(3) In the case of hybrid engines, activate the system such that the engine will start when 

its control algorithms determine that the engine should provide power instead of or in 

addition to power from the RESS. Unless we specify otherwise, engine starting 

throughout this part generally refers to this step of activating the system on hybrid 

engines, whether or not that causes the engine to start running.

* * * * *

(c) * * *

(4) DELETE

* * * * *

69. Section 1065.530 is amended by revising paragraph (b)(13) to read as follows:

§1065.530 Emission test sequence.

* ** * *

(b) * * *

(13) Drain any accumulated condensate from the intake air system before starting a duty

cycle, as described in §1065.125(e)(1). If engine and aftertreatment preconditioning 

cycles are run before the duty cycle, treat the preconditioning cycles and any associated 

soak period as part of the duty cycle for the purpose of opening drains and draining 

condensate. Note that you must close any intake air condensate drains that are not 

representative of those normally open during in-use operation. 

* * * * *

70. Section 1065.546 is amended by revising paragraph (a) to read as follows:

§1065.546 Validation of minimum dilution ratio for PM batch sampling, and drift 

correction.
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* ** * *

(a) Determine minimum dilution ratio based on molar flow data. This involves 

determination of at least two of the following three quantities: raw exhaust flow (or 

previously diluted flow), dilution air flow, and dilute exhaust flow. You may determine 

the raw exhaust flow rate based on the measured intake air or fuel flow rate and the raw 

exhaust chemical balance terms as given in §1065.655(e). You may determine the raw 

exhaust flow rate based on the measured intake air and dilute exhaust molar flow rates 

and the dilute exhaust chemical balance terms as given in §1065.655(f). You may 

alternatively estimate the molar raw exhaust flow rate based on intake air, fuel rate 

measurements, and fuel properties, consistent with good engineering judgment.

* ** * *

71. Section 1065.550 is amended by revising the section title and paragraph (b) to read 

as follows:

§1065.550 Gas analyzer range validation and drift validation.

* ** * *

(b) Drift validation and drift correction. Gas analyzer drift validation is required for all 

gaseous exhaust constituents for which an emission standard applies. It is also required 

for CO2 even if there is no CO2 emission standard. It is not required for other gaseous 

exhaust constituents for which only a reporting requirement applies (such as CH4 and 

N2O).

(1) Validate drift using one of the following methods:

(i) For regulated exhaust constituents determined from the mass of a single component, 

perform drift validation based on the regulated constituent. For example, when NOx

mass is determined with a dry sample measured with a CLD and the removed water is 

corrected based on measured CO2, CO, THC, and NOx concentrations, you must validate 

the calculated NOx value.

(ii) For regulated exhaust constituents determined from the masses of multiple 

subcomponents, perform the drift validation based on either the regulated constituent or 

all the mass subcomponents. For example, when NOx is measured with separate NO and 

NO2 analyzers, you must validate either the NOx value or both the NO and NO2 values.

(iii) For regulated exhaust constituents determined from the concentrations of multiple 

gaseous emission subcomponents prior to performing mass calculations, perform drift 

validation on the regulated constituent. You may not validate the concentration 

subcomponents (e.g., THC and CH4 for NMHC) separately. For example, for NMHC 

measurements, perform drift validation on NMHC; do not validate THC and CH4

separately.
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(2) Drift validation requires two sets of emission calculations. For each set of 

calculations, include all the constituents in the drift validation. Calculate one set using 

the data before drift correction and calculate the other set after correcting all the data for 

drift according to §1065.672. Note that for purposes of drift validation, you must leave 

unaltered any negative emission results over a given test interval (i.e., do not set them to 

zero). These unaltered results are used when validating either test interval results or 

composite brake-specific emissions over the entire duty cycle for drift. For each 

constituent to be validated, both sets of calculations must include the following:

(i) Calculated mass (or mass rate) emission values over each test interval.

(ii) If you are validating each test interval based on brake-specific values, calculate brakespecific emission values over each test interval.

(iii) If you are validating over the entire duty cycle, calculate composite brake-specific 

emission values.

(3) Validation Criteria. The duty cycle is validated for drift if you satisfy the following 

criteria:

(i) For each regulated gaseous exhaust constituent, you must satisfy one of the following:

(A) For each test interval of the duty cycle, the difference between the uncorrected and 

the corrected brake-specific emission values of the regulated constituent must be within 

±4 % of the uncorrected value or the applicable emissions standard, whichever is greater. 

Alternatively, the difference between the uncorrected and the corrected emission mass (or 

mass rate) values of the regulated constituent must be within 4 % of the uncorrected 

value or the composite work (or power) multiplied by the applicable emissions standard, 

whichever is greater. For purposes of validating each test interval, you may use either the 

reference or actual composite work (or power).

(B) For each test interval of the duty cycle and for each subcomponent of the regulated 

constituent, the difference between the uncorrected and the corrected brake-specific 

emission values must be within ±4 % of the uncorrected value. Alternatively, the 

difference between the uncorrected and the corrected emissions mass (or mass rate) 

values must be within ±4 % of the uncorrected value.

(C) For the entire duty cycle, the difference between the uncorrected and the corrected 

composite brake-specific emission values of the regulated constituent must be within ±4 

% of the uncorrected value or applicable emission standard, whichever is greater.

(D) For the entire duty cycle and for each subcomponent of the regulated constituent, the 

difference between the uncorrected and the corrected composite brake-specific emission 

values must be within ±4 % of the uncorrected value.

(ii) Where no emission standard applies for CO2, you must satisfy one of the following:
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(A) For each test interval of the duty cycle, the difference between the uncorrected and 

the corrected brake-specific CO2 values must be within ±4 % of the uncorrected value; or 

the difference between the uncorrected and the corrected CO2 mass (or mass rate) values 

must be within ±4 % of the uncorrected value.

(B) For the entire duty cycle, the difference between the uncorrected and the corrected 

composite brake-specific CO2 values must be within ±4 % of the uncorrected value.

(2) If the test is not validated for drift as described in paragraph (b)(1) of this section, you 

may consider the test results for the duty cycle to be valid only if, using good engineering 

judgment, the observed drift does not affect your ability to demonstrate compliance with 

the applicable emission standards. For example, if the drift-corrected value is less than 

the standard by at least two times the absolute difference between the uncorrected and 

corrected values, you may consider the data to be valid for demonstrating compliance 

with the applicable standard.

* * * * *

Subpart G—[Amended]

72. Section 1065.602 is amended by revising paragraph (f)(3) before the table, 

paragraph (h), and paragraphs (l)(1)(ii) and (iii) as follows:

§1065.602 Statistics.

* ** * *

(f) * * *

(3) Use Table 1 of this section to compare t to the tcrit values tabulated versus the number 

of degrees of freedom. If t is less than tcrit, then t passes the t-test. The Microsoft Excel 

software has a TINV function that returns equivalent results and may be used in place of 

Table 1, which follows:

* * * * *

(h) Slope. Calculate a least-squares regression slope, a1y, as follows:

  i refi ref

i 1

1y

2

refi ref

i 1

( )

( )

N

N

y y y y

a

y y





  









Eq. 1065.602-9
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Example:

N = 6000

y1 = 2045.8

y = 1050.1

yref 1 = 2045.0

ref y = 1055.3

       

   

6000 ref6000

1y 2 2

ref6000

2045.8 1050.1 2045.0 1055.3 ... 1050.1 1055.3

2045.0 1055.3 ... 1055.3

y y

a

y

       



   

a1y = 1.0110

* * * * *

(l) * * *

(1) * * *

(ii) Based on your engine design, estimate maximum power, Pmax, the design speed at 

maximum power, fnmax, the design maximum intake manifold boost pressure, pinmax, and 

temperature, Tinmax. Also, estimate a mean fraction of power that is lost due to friction 

and pumping, Pfrict . Use this information along with the engine displacement volume, 

Vdisp, an approximate volumetric efficiency, V, and the number of engine strokes per 

power stroke (2-stroke or 4-stroke), Nstroke, to estimate the maximum raw exhaust molar 

flow rate, exhmax n .

(iii) Use your estimated values as described in the following example calculation:

 

std ref

exp

ref frict max

exhmax duty cycle

max

e W

x

P P P

M n t

P





   

   

 



Eq. 1065.602-13

max disp nmax V

stroke

exhmax

max

2

p V f

N

n

R T

   







Eq. 1065.602-14
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Example:

eNOx = 2.5 g/(kW·hr)

Wref = 11.883 kW·hr

MNOx = 46.0055 g/mol = 46.0055·10-6g/mol

tdutycycle = 20 min = 1200 s

Pref = 35.65 kW

Pfrict = 15 %

Pmax = 125 kW

pmax = 300 kPa = 300000 Pa

Vdisp = 3.0 l = 0.0030 m3/r

fnmax = 2800 r/min = 46.67 r/s

Nstroke = 4

V= 0.9

R = 8.314472 J/(mol·K)

Tmax = 348.15 K

exhmax

2

300000 0.0030 46.67 0.9

4

8.314472 348.15

n

   







exhmax n = 6.53 mol/s

 

exp

6

2.5 11.883

35.65 0.15 125

46.0055 10 6.53 1200

125

x







   

      

exp x = 189.4 μmol/mol
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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73. Section 1065.610 is amended by revising paragraphs (a)(1), (a)(2), (a)(3), (b)(1), 

(c)(1), (c)(2), and (c)(3) and adding a new (a)(4) as follows:

§1065.610 Duty cycle generation.

* ** * *

(a) * * *

(1) Based on the map, determine maximum power, Pmax, and the speed at which 

maximum power occurred, fnPmax. If maximum power occurs at multiple speeds, take 

fnPmax as the lowest of these speeds. Divide every recorded power by Pmax and divide 

every recorded speed by fnPmax. The result is a normalized power-versus-speed map. 

Your measured fntest is the speed at which the sum of the squares of normalized speed and 

power is maximum. Note that if multiple maximum values are found, fntest should be 

taken as the lowest speed of all points with the same maximum sum of squares. 

Determine fntest as follows:

 

2 2

ntest ni nnormi normi f f   at the maximum of f P

Eq. 1065.610-1

Where: 

fntest = maximum test speed.

i = an indexing variable that represents one recorded value of an engine map.

fnnormi = an engine speed normalized by dividing it by fnPmax.

Pnormi = an engine power normalized by dividing it by Pmax.

Example:

(fnnorm1 = 1.002, Pnorm1 = 0.978, fn1 = 2359.71)

(fnnorm2 = 1.004, Pnorm2 = 0.977, fn2 = 2364.42)

(fnnorm3 = 1.006, Pnorm3 = 0.974, fn3 = 2369.13)

(fnnorm1

2

+ Pnorm1

2

) = (1.0022+ 0.9782) = 1.960

(fnnorm2

2

+ Pnorm2

2

) = (1.0042+ 0.9772) = 1.963

(fnnorm3

2

+ Pnorm3

2

) = (1.0062+ 0.9742) = 1.961
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maximum = 1.963 at i = 2

fntest = 2364.42 r/min

(2) For engines with a high-speed governor that will be subject to a reference duty cycle 

that specifies normalized speeds greater than 100 %, calculate an alternate maximum test 

speed, fntest,alt, as specified in this paragraph (a)(2). If fntest,alt is less than the measured 

maximum test speed, fntest, determined in paragraph (a)(1) of this section, replace fntest

with fntest,alt. In this case, fntest,alt becomes the “maximum test speed” for that engine. Note 

that §1065.510 allows you to apply an optional declared maximum test speed to the final 

measured maximum test speed determined as an outcome of the comparison between 

fntest, and fntest,alt in this paragraph (a)(2). Determine fntest,alt as follows:

fntest,alt = (fnhi,idle – fnidle)/% speedmax + fnidle

Eq. 1065.610-2

Where:

fntest,alt = alternate maximum test speed

fnhi,idle = warm high-idle speed

fnidle = warm idle speed

% speedmax = maximum normalized speed from duty cycle

Example:

fnhi,idle = 2200 r/min

fnidle = 800 r/min

% speedmax = 105 % (Nonroad CI Transient Cycle)

fntest,alt = (2200 – 800)/105 % + 800

fntest,alt = 2133 r/min

(3) For variable-speed engines, transform normalized speeds to reference speeds 

according to paragraph (c) of this section by using the measured maximum test speed 

determined according to paragraphs (a)(1) and (2) of this section—or use your declared 

maximum test speed, as allowed in §1065.510.
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(4) For constant-speed engines, transform normalized speeds to reference speeds 

according to paragraph (c) of this section by using the measured no-load governed 

speed—or use your declared maximum test speed, as allowed in §1065.510

(b) * * *

(1) Based on the map, determine maximum power, Pmax, and the speed at which 

maximum power occurs, fnPmax. If maximum power occurs at multiple speeds, take fnPmax

as the lowest of these speeds. Divide every recorded power by Pmax and divide every

recorded speed by fnPmax. The result is a normalized power-versus-speed map. Your 

measured Ttest is the torque at which the sum of the squares of normalized speed and 

power is maximum. Note that that if multiple maximum values are found, Ttest should be 

taken as the highest torque of all points with the same maximum sum of squares. 

Determine Ttest as follows:

 

2 2

test i nnormi normi T T   at the maximum of f P

Eq. 1065.610-3

Where: 

Ttest = maximum test torque.

Example:

(fnnorm1 = 1.002, Pnorm1 = 0.978, T1 = 722.62 N·m)

(fnnorm2 = 1.004, Pnorm2 = 0.977, T2 = 720.44 N·m)

(fnnorm3 = 1.006, Pnorm3 = 0.974, T3 = 716.80 N·m)

(fnnorm1

2

+ Pnorm1

2

) = (1.0022+ 0.9782) = 1.960

(fnnorm1

2

+ Pnorm1

2

) = (1.0042+ 0.9772) = 1.963

(fnnorm1

2

+ Pnorm1

2

) = (1.0062+ 0.9742) = 1.961

maximum = 1.963 at i = 2

Ttest = 720.44 N·m

(2) * * *

(c) * * *
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(1) % speed. If your normalized duty cycle specifies % speed values, use your warm idle 

speed and your maximum test speed to transform the duty cycle, as follows:

fnref = % speed · (fntest – fnidle) + fnidle

Eq. 1065.610-4

Example:

% speed = 85 %

fntest = 2364 r/min

fnidle = 650 r/min

fnref = 85 % · (2364 – 650 ) + 650

fnref = 2107 r/min 

(2) A, B, and C speeds. If your normalized duty cycle specifies speeds as A, B, or C 

values, use your power-versus-speed curve to determine the lowest speed below 

maximum power at which 50 % of maximum power occurs. Denote this value as nlo. 

Take nlo to be warm idle speed if all power points at speeds below the maximum power 

speed are higher than 50 % of maximum power. Also determine the highest speed above 

maximum power at which 70 % of maximum power occurs. Denote this value as nhi. If 

all power points at speeds above the maximum power speed are higher than 70% of 

maximum power, take nhi to be the declared maximum safe engine speed or the declared 

maximum representative engine speed, whichever is lower. Use nhi and nlo to calculate 

reference values for A, B, or C speeds as follows:

fnrefA = 0.25 · (nhi – nlo) + nlo

Eq. 1065.610-5

fnrefB = 0.50 · (nhi – nlo) + nlo

Eq. 1065.610-6

fnrefC = 0.75 · (nhi – nlo) + nlo

Eq. 1065.610-7

Example:

nlo = 1005 r/min

nhi = 2385 r/min

fnrefA = 0.25 · (2385 – 1005) + 1005
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fnrefB = 0.50 · (2385 – 1005) + 1005

fnrefC = 0.75 · (2385 – 1005) + 1005

fnrefA = 1350 r/min

fnrefB = 1695 r/min

fnrefC = 2040 r/min

(3) Intermediate speed. If your normalized duty cycle specifies a speed as “intermediate 

speed,” use your torque-versus-speed curve to determine the speed at which maximum 

torque occurs. This is peak torque speed. If maximum torque occurs in a flat region of 

the torque-versus-speed curve, your peak torque speed is the midpoint between the lowest 

and highest speeds at which the trace reaches the flat region. For purposes of this 

paragraph (c)(3), a flat region is one in which measured torque values are within 2 % of 

the maximum recorded value. Identify your reference intermediate speed as one of the 

following values:

* ** * *

74. Section 1065.640 is amended by revising paragraphs (b)(1), (b)(2), (b)(5), (e)(3), 

(e)(4), and (e)(7) as follows:

§1065.640 Flow meter calibration calculations.

* ** * *

(b) * * *

(1) PDP volume pumped per revolution, Vrev (m3/r):

ref in

rev

in nPDP

n R T

V

P f

 







Eq. 1065.640-2 

Example:

ref n& = 25.096 mol/s

R = 8.314472 J/(mol·K)

Tin = 299.5 K

Pin = 98290 Pa
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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nPDP f = 1205.1 r/min = 20.085 r/s

25.096 8.314472 299.5

98290 20.085

Vrev

 





Vrev = 0.03166 m3/r

(2) PDP slip correction factor, Ks (s/r):

out in

s

nPDP out

1 P P K

f P



 

Eq. 1065.640-3

Example:

nPDP f = 1205.1 r/min = 20.085 r/s

Pout = 100.103 kPa

Pin = 98.290 kPa

s

1 100.103 98.290

20.085 100.103

K



 

Ks = 0.006700 s/r

(3) * * *

(4) * * *

(5) The following example illustrates these calculations:

Table 1 of §1065.640–

Example of PDP calibration data

nPDP f

(r/min)

a1 

(m3/min)

a0 

(m3/r)
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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755.0 50.43 0.056

987.6 49.86 -0.013

1254.5 48.54 0.028

1401.3 47.30 -0.061

(e) * * *

(3) If the standard deviation of all the Cd values is less than or equal to 0.3 % of the mean 

Cd, use the mean Cd in Eq 1065.642-6, and use the CFV only up to the highest r

measured during calibration using the following equation:

CFV

in

1

p

r

p



 

Eq. 1065.640-13

Where:

pCFV = Differential static pressure; venturi inlet minus venturi outlet.

(4) If the standard deviation of all the Cd values exceeds 0.3 % of the mean Cd, omit the 

Cd values corresponding to the data point collected at the highest r measured during 

calibration.

* ** * *

(7) If the standard deviation of the remaining Cd values is less than or equal to 0.3 % of 

the mean of the remaining Cd, use that mean Cd in Eq 1065.642-6, and use the CFV 

values only up to the highest r associated with the remaining Cd.

* * * * *

75. Section 1065.642 is amended by revising paragraph (a) as follows:

§1065.642 SSV, CFV, and PDP molar flow rate calculations.
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* ** * *

(a) PDP molar flow rate. Based upon the speed at which you operate the PDP for a test 

interval, select the corresponding slope, a1, and intercept, a0, as calculated in §1065.640, 

to calculate molar flow rate, n as follows:

nPDP

in rev

in

p V n f

R T



 





Eq. 1065.642-1

Where:

nPDP

1 out in

rev 0

out

a p p

V a

f p



  

Eq. 1065.642-2

Example:

a1 = 50.43 (m3/min) = 0.8405 (m3/s)

nPDP f = 755.0 r/min = 12.58 r/s

pout = 99950 Pa

pin = 98575 Pa 

a0 = 0.056 (m3/r)

R = 8.314472 J/(mol·K)

Tin = 323.5 K

Cp = 1000 (J/m3)/kPa

Ct = 60 s/min

rev

0.8405 99950 98575 0.056

12.58 99950

V



  

Vrev = 0.06383 m3/r
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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98575 0.06383 12.58

8.314472 323.5

n



 





n&= 29.428 mol/s

* ** * *

76. Section 1065.645 is amended by revising the introductory paragraph and paragraph 

(a) as follows:

§1065.645 Amount of water in an ideal gas.

This section describes how to determine the amount of water in an ideal gas, which you 

need for various performance verifications and emission calculations. Use the equation 

for the vapor pressure of water in paragraph (a) of this section or another appropriate 

equation and, depending on whether you measure dewpoint or relative humidity, perform 

one of the calculations in paragraph (b) or (c) of this section. The equations for the vapor 

pressure of water as presented in this section are derived from equations in “Saturation 

Pressure of Water on the New Kelvin Temperature Scale” (Goff, J.A., Transactions 

American Society of Heating and Air-Conditioning Engineers, Vol. 63, No. 1607, pages 

347 – 354). Note that the equations were originally published to derive vapor pressure in 

units of atmospheres and have been modified to derive results in units of kPa by

converting the last term in each equation.

(a) Vapor pressure of water. Calculate the vapor pressure of water for a given saturation 

temperature condition, Tsat, as follows, or use good engineering judgment to use a 

different relationship of the vapor pressure of water to a given saturation temperature 

condition:

(1) For humidity measurements made at ambient temperatures from (0 to 100) °C, or for 

humidity measurements made over super-cooled water at ambient temperatures from (–

50 to 0) °C, use the following equation:

sat

sat

8 2969 1

sat 4 273.16

10 H2O 10

sat

273.16 4.76955 1

3

. 273.16 log ( ) 10.79574 1 5.02800 log 1.50475 10 1 10

273.16

0.42873 10 10 1 0.2138602

T

T

T

p

T

 

    

  

 

   

  

     

                     

 

      

 

Eq. 1065.645-1

Where:

pH20 = vapor pressure of water at saturation temperature condition, kPa.

Tsat = saturation temperature of water at measured conditions, K.
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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Example:

Tsat = 9.5 °C

Tsat = 9.5 + 273.15 = 282.65 K

282.65 8.2969 1

4 273.16

10 H2O 10

273.16 4.76955 1

3 282.65

273.16 282.65 log ( ) 10.79574 1 5.02800 log 1.50475 10 1 10

282.65 273.16

0.42873 10 10 1 0.2138602

p

 

   

  

 

   

  

     

            

     

 

      

 

log10(pH20) = 0.074297

pH20 = 100.074297 = 1.186581 kPa

(2) For humidity measurements over ice at ambient temperatures from (–100 to 0) °C, use 

the following equation:

10 H2O 10

sat sat

sat

273.16 273.16 log ( ) 9.096853 1 3.566506 log

0.876812 1 0.2138602

273.16

p

T T

T

   

             

 

       

Eq. 1065.645-2

Example:

Tice = –15.4 °C

Tice = –15.4+ 273.15 = 257.75 K

10 H2O 10

273.16 273.16 log ( ) 9.096853 1 3.566506 log

257.75 257.75

257.75 0.876812 1 0.2138602

273.16

p

   

             

 

      

log10(pH20) = –0.798207

pH20 = 10 –0.79821 = 0.159145 kPa
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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* ** * *

77. Section 1065.650 is amended by revising paragraphs (c) introductory text, (c)(1), 

(c)(4), (d)(7), (e)(4), (f)(4), and adding paragraph (c)(5) to read as follows:

§1065.650 Emission calculations.

* ** * *

(c) Total mass of emissions over a test interval. To calculate the total mass of an 

emission, multiply a concentration by its respective flow. For all systems, make 

preliminary calculations as described in paragraph (c)(1) of this section to correct 

concentrations. Next, use the method in paragraphs (c)(2) through (4) of this section that 

is appropriate for your system. Finally, if necessary, calculate the mass of NMHC as 

described in paragraph (c)(5) of this section for all systems. Calculate the total mass of 

emissions as follows:

(1) Concentration corrections. Perform the following sequence of preliminary 

calculations on recorded concentrations:

(i) Correct all gaseous emission analyzer concentration readings, including continuous 

readings, sample bag readings, and dilution air background readings, for drift as 

described in §1065.672. Note that you must omit this step where brake-specific 

emissions are calculated without the drift correction for performing the drift validation 

according to §1065.550(b). When applying the initial THC and CH4 contamination 

readings according to §1065.520(g), use the same values for both sets of calculations. 

You may also use as-measured values in the initial set of calculations and corrected 

values in the drift-corrected set of calculations as described in §1065.520(g)(7).

(ii) Correct all THC and CH4 concentrations, including continuous readings, sample bags 

readings, and dilution air background readings, for initial contamination, as described in 

§1065.660(a).

(iii) Correct all concentrations measured on a “dry” basis to a “wet” basis, including 

dilution air background concentrations, as described in §1065.659.

(iv) Calculate all NMHC and CH4 concentrations, including dilution air background 

concentrations, as described in §1065.660.

(v) For emission testing with an oxygenated fuel, calculate any HC concentrations, 

including dilution air background concentrations, as described in §1065.665. See subpart 

I of this part for testing with oxygenated fuels.

(vi) Correct all the NOx concentrations, including dilution air background concentrations, 

for intake-air humidity as described in §1065.670.
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* ** * *

(4) Additional provisions for diluted exhaust sampling; continuous or batch. The 

following additional provisions apply for sampling emissions from diluted exhaust:

(i) For sampling with a constant dilution ratio, DR, of diluted exhaust versus exhaust flow 

(e.g., secondary dilution for PM sampling), calculate m using the following equation:

mPM = mPMdil · DR

Eq. 1065.650-9

Example:

mPMdil = 6.853 g

DR = 6:1

mPM = 6.853 · 6

mPM = 41.118 g

(ii) For continuous or batch sampling, you may measure background emissions in the 

dilution air. You may then subtract the measured background emissions, as described in 

§1065.667.

(5) Mass of NMHC. Compare the corrected mass of NMHC to corrected mass of THC. 

If the corrected mass of NMHC is greater than 0.98 times the corrected mass of THC, 

take the corrected mass of NMHC to be 0.98 times the corrected mass of THC. If you 

omit the NMHC calculations as described in §1065.660(b)(1), take the corrected mass of 

NMHC to be 0.98 times the corrected mass of THC.

* ** * *

(d) * * *

(7) Integrate the resulting values for power over the test interval. Calculate total work as 

follows:

i

i 1

N

W P t



   

Eq. 1065.650-10

Where:

W = total work from the primary output shaft
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Pi = instantaneous power from the primary output shaft over an interval i.

Pi = fni · Ti

Eq. 1065.650-11

Example:

N = 9000

fn1 = 1800.2 r/min

fn2 = 1805.8 r/min

T1 = 177.23 N·m

T2 = 175.00 N·m

Crev = 2· rad/r

Ct1 = 60 s/min

Cp = 1000 (N·m·rad/s)/kW

frecord = 5 Hz

Ct2 = 3600 s/hr

1

1800.2 177.23 2 3.14159

60 1000

P

  





P1 = 33.41 kW

P2 = 33.09 kW

Using Eq. 1065.650-5,

t = 1/5 = 0.2 s

9000 (33.41 33.09 ... ) 0.2

3600

P

W

   



W = 16.875 kW·hr

* ** * *
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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(e) * * *

(4) The following example shows how to calculate mass of emissions using mean mass 

rate and mean power:

MCO = 28.0101 g/mol 

CO x = 12.00 mmol/mol = 0.01200 mol/mol

n = 1.530 mol/s

n

f = 3584.5 r/min = 375.37 rad/s

T = 121.50 N·m

m   28.0101 0.01200 1.530

m = 0.514 g/s = 1850.4 g/hr

P   121.5 375.37

P = 45607 W

P = 45.607 kW

eCO = 1850.4/45.61

eCO = 40.57 g/(kW·hr)

* ** * *

(f) * * *

(4) Example. The following example shows how to calculate mass of emissions using 

proportional values:

N = 3000

frecord = 5 Hz

efuel = 285 g/(kW·hr)

wfuel = 0.869 g/g

Mc = 12.0107 g/mol

1

n

 = 3.922 mol/s = 14119.2 mol/hr
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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xCcombdry1 = 91.634 mmol/mol = 0.091634 mol/mol

xH2Oexh1 = 27.21 mmol/mol = 0.02721 mol/mol

Using Eq. 1065.650-5,

t = 0.2 s

2 Ccombdry2 3000 Ccombdry3000

H2Oexh2 H2Oexh3000

3.922 0.091634 12.0107 ... 0.2

1 0.02721 1 1

285 0.869

n x n x

x x

W

    

     

    





   



W = 5.09 (kW·hr)

* ** * *

78. Section 1065.655 is amended by adding a new paragraph (f) and revising paragraphs 

(b)(1), (b)(2), (b)(3), (c)(5), (d), and (e)(3) as follows:

§1065.655 Chemical balances of fuel, intake air, and exhaust.

* ** * *

(b) * * *

(1) A value proportional to total work, W when you choose to determine brake-specific 

emissions as described in §1065.650(f).

(2) The amount of water in a raw or diluted exhaust flow, xH2Oexh, when you do not 

measure the amount of water to correct for the amount of water removed by a sampling 

system. Correct for removed water according to §1065.659.

(3) The calculated dilution air flow when you do not measure dilution air flow to correct 

for background emissions as described in §1065.667(c) and (d). 

(c) * * *

(5) The following example is a solution for xdil/exh, xH2Oexh, and xCcombdry using the 

equations in paragraph (c)(4) of this section:

dil/exh

0.184 1 0.822 35.37 1

1000

x m = - = ol mol

+
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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H2Oexh

35.37 34.16 35.37 1+

1000

x m = = mol mol

Ccombdry

29.3 47.6 0.371 0.369 0.0252 0.851 0.172 0.0249

1000000 1000000 1000 1000

x m         ol mol

 

H2dry

29.3 0.034 0.012 0.851

8.5

25.2 0.371 3.5 0.851

1000 1000

x m ol mol

  

   

      

H2Oexhdry

1.8 47.6 8.5 0.0249 0.012 0.851 0.017 0.172 0.0353

2 1000000 1000000

x mol mol             

dil/exhdry

0.822 0.851

1-0.034

x m = = ol mol

int/exhdry

1.8 47.6 0.050 2 2 0.0003 0.0249

1 2 1000000

0.172

2 0.206 29.3 50.4 12.1 8.5 2

1000000 1000000 1000000 1000000

x mol mol

                   

 

        

   

raw/exhdry

1.8 47.6 0.050 0.0001 0.0249

1 2 1000000

0.172 0.184

2 47.6 29.3 12.1 8.5 2

1000000 1000000 1000000 1000000

x mol mol

                 

  

       

   

O2int

0.209820 0.000375 0.206 17.22 1

1000

x mol mol -= =

+

CO2int

0.000375 1000 0.369 17.22 1

1000

x mmol mol  



H2Ointdry

16.93 17.22 16.93 1

1000

x m = = mol mol

-
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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CO2dil

0.375 0.371 12.01 1

1000

x m = = mol mol

+

H2Odildry

11.87 =12.01 11.87 1

1000

x m = mol mol

-

COdry

29.0 = 29.3 8.601 1

1000

x m = m ol mol

-

CO2dry

24.98 = 25.2 8.601 1

1000

x m = mol mol

-

NOdry

50.0 = 50.4 8.601 1

1000

x m = m ol mol

-

NO2dry

12.0 = 12.1 8.601 1

1000

x m = m ol mol

-

THCdry

46 = 47.6 34.16 1

1000

x m = m ol mol

-

 = 1.8

 = 0.05

 = 0.0003

= 0.0001

* ** * *
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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(d) * * *

(1) You may calculate wc as described in this paragraph (d)(1) based on measured fuel 

properties. To do so, you must determine values for  and  in all cases, but you may set 

 and  to zero if the default value listed in Table 1 of this section is zero. Calculate wc

using the following equation:

C

c

C H O S N

1

1

M

w

M M   M M   M





        

Eq. 1065.655-19

Where:

wc = carbon mass fraction of fuel.

MC = molar mass of carbon.

 = atomic hydrogen-to-carbon ratio of the mixture of fuel(s) being combusted, weighted 

by molar consumption.

MH = molar mass of hydrogen.

 = atomic oxygen-to-carbon ratio of the mixture of fuel(s) being combusted, weighted 

by molar consumption.

MO = molar mass of oxygen.

 = atomic sulfur-to-carbon ratio of the mixture of fuel(s) being combusted, weighted by 

molar consumption.

MS = molar mass of sulfur.

 = atomic nitrogen-to-carbon ratio of the mixture of fuel(s) being combusted, weighted 

by molar consumption.

MN = molar mass of nitrogen.

Example:

 = 1.8

 = 0.05

 = 0.0003
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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= 0.0001

MC = 12.0107

MH = 1.01

MO = 15.9994

MS = 32.065

MN = 14.0067

c

1 12.0107

1 12.0107 1.8 1.01 0.05 15.9994 0.0003 32.065 0.0001 14.0067

w





        

wc = 0.8205
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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(2) You may use the default values in the following table to determine wc for a given fuel:

Table 1 of §1065.655–Default values of , , , , and wc, for various fuels

Fuel

Atomic hydrogen,

oxygen, sulfur, and 

nitrogen-to-carbon ratios

CHαOβSN

Carbon mass 

fraction, wc

g/g

Gasoline CH1.85O0S0N0 0.866

E10 Gasoline CH1.92O0.03S0N0 0.833

E15 Gasoline CH1.95O0.05S0N0 0.817

E85 Gasoline CH2.73O0.38S0N0 0.576

#1 Diesel CH1.93O0S0N0 0.861

#2 Diesel CH1.80O0S0N0 0.869

Liquefied Petroleum Gas CH2.64O0S0N0 0.819

Natural gas CH3.78 O0.016S0N0 0.747

E100 Ethanol CH3O0.5S0N0 0.521

M100 Methanol CH4O1S0N0 0.375

Residual fuel blends Must be determined by measured fuel properties as 

described in paragraph (d)(1) of this section.
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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(e) * * *

(3) Fuel mass flow rate calculation. Based on mfuel  , calculate exh n as follows:

fuel c H  2Oexhdry 

exh

c Ccombdry

m w 1 x

n

M x

  









Eq. 1065.655-21

Where:

exh n = raw exhaust molar flow rate from which you measured emissions.

mfuel  = fuel flow rate including humidity in intake air.

Example:

mfuel  = 7.559 g/s

wc = 0.869 g/g

MC = 12.0107 g/mol

xCcombdry = 99.87 mmol/mol = 0.09987 mol/mol

xH20exhdry = 107.64 mmol/mol = 0.10764 mol/mol

 

exh

7.559 0.869 1 0.10764

12.0107 0.09987

n

  







exh n = 6.066 mol/s

(f) Calculated raw exhaust molar flow rate from measured intake air molar flow rate, 

dilute exhaust molar flow rate, and dilute chemical balance. You may calculate the raw 

exhaust molar flow rate, exh n , based on the measured intake air molar flow rate, int n , the 

measured dilute exhaust molar flow rate, dexh n , and the values calculated using the 

chemical balance in paragraph (c) of this section. Note that the chemical balance must be 

based on dilute exhaust gas concentrations. For continuous-flow calculations, solve for 

the chemical balance in paragraph (c) of this section at the same frequency that you 

update and record int n and dexh n . This calculated exh n may be used for the PM dilution 
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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ratio verification in §1065.546; the calculation of dilution air molar flow rate in the 

background correction in §1065.667; and the calculation of mass of emissions in 

§1065.650(c) for species that are measured in the raw exhaust.

(1) Crankcase flow rate. If engines are not subject to crankcase controls under the 

standard-setting part, calculate raw exhaust flow as described in paragraph (e)(1) of this 

section.

(2) Dilute exhaust and intake air molar flow rate calculation. Calculate nexh  as follows:

    exh raw/exhdry int/exhdry H2Oexh dexh int n x     x x  1   n n

Eq. 1065.655-22

Example:

int n  7.930 mol/s

raw/exhdry x  0.1544 mol/mol

0.1451mol/mol xint/exhdry 

H2Oexh x   32.46 mmol/mol 0.03246 mol/mol

dexh n  49.02 mol/s

n

exh   0.1544 0.1451  1 0.03246  49.02 7.930   0.4411 7.930 8  .371mol/s

* * * * *

79. Section 1065.659 is amended by revising paragraphs (a), (b), and (c) to read as 

follows:

§1065.659 Removed water correction.

(a) If you remove water upstream of a concentration measurement, x, or upstream of a 

flow measurement, n, correct for the removed water. Perform this correction based on 

the amount of water at the concentration measurement, xH2O[emission]meas, and at the flow 

meter, xH2Oexh, whose flow is used to determine the mass emission rate or total mass over 

a test interval. For continuous analyzers downstream of a sample dryer for transient and 

ramped-modal cycles, you must apply this correction on a continuous basis over the test 

interval, even if you use one of the options in §1065.145(e)(2) that results in a constant 
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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value for xH2O[emission]meas because xH2Oexh varies over the test interval. For batch 

analyzers, determine the flow-weighted average based on the continuous xH2Oexh values 

determined as described in paragraph (c) of this section. For batch analyzers, you may

determine the flow-weighted average xH2Oexh based on a single value of xH2Oexh

determined as described in paragraphs (c)(2) and (3) of this section, using flow-weighted 

average or batch concentration inputs.

(b) Determine the amount of water remaining downstream of a sample dryer and at the 

concentration measurement using one of the methods described in §1065.145(e)(2). If 

you use a sample dryer upstream of an analyzer and if the calculated amount of water 

remaining downstream of the sample dryer and at the concentration measurement, 

xH2O[emission]meas, is higher than the amount of water at the flow meter, xH2Oexh, set 

xH2O[emission]meas equal to xH2Oexh. If you use a sample dryer upstream of storage media, 

you must be able to demonstrate that the sample dryer is removing water continuously

(i.e., xH2Oexh is higher than xH2O[emission]meas throughout the test interval).

(c) For a concentration measurement where you did not remove water, you may set 

xH2O[emission]meas equal to xH2Oexh. You may determine the amount of water at the flow 

meter, xH2Oexh, using any of the following methods:

(1) Measure the dewpoint and absolute pressure and calculate the amount of water as 

described in §1065.645.

(2) If the measurement comes from raw exhaust, you may determine the amount of water 

based on intake-air humidity, plus a chemical balance of fuel, intake air, and exhaust as 

described in§1065.655.

(3) If the measurement comes from diluted exhaust, you may determine the amount of 

water based on intake-air humidity, dilution air humidity, and a chemical balance of fuel, 

intake air, and exhaust as described in §1065.655.

(d) * * *

80. Section 1065.660 is amended by revising paragraphs all paragraphs to read as 

follows:

§1065.660 THC, NMHC, and CH4 determination.

(a) THC determination and initial THC/CH4 contamination corrections. (1) If we require 

you to determine THC emissions, calculate xTHC[THC-FID]cor using the initial THC 

contamination concentration xTHC[THC-FID]init from §1065.520 as follows:

xTHC[THC-FID]cor = xTHC[THC-FID]uncor – xTHC[THC-FID]init

Eq. 1065.660-1
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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Example:

xTHCuncor = 150.3 μmol/mol

xTHCinit = 1.1 μmol/mol

xTHCcor = 150.3 – 1.1

xTHCcor = 149.2 μmol/mol

(2) For the NMHC determination described in paragraph (b) of this section, correct 

xTHC[THC-FID] for initial THC contamination using Eq. 1065.660-1. You may correct

xTHC[NMC-FID] for initial contamination of the CH4 sample train using Eq. 1065.660-1, 

substituting in CH4 concentrations for THC.

(3) For the CH4 determination described in paragraph (c) of this section, you may correct

xTHC[NMC-FID] for initial THC contamination of the CH4 sample train using Eq. 1065.660-

1, substituting in CH4 concentrations for THC.

(b) NMHC determination. Use one of the following to determine NMHC 

concentration, xNMHC:

(1) If you do not measure CH4, you may omit the calculation of NMHC concentrations 

and calculate the mass of NMHC as described in §1065.650(c)(5).

(2) For nonmethane cutters, calculate xNMHC using the nonmethane cutter’s penetration 

fraction (PF) of CH4 and the response factor penetration fraction (RFPF) of C2H6 from 

§1065.365, the response factor (RF) of the THC FID to CH4 from §1065.360, the initial 

THC contamination and dry-to-wet corrected THC concentration xTHC[THC-FID]cor as 

determined in paragraph (a) of this section, and the dry-to-wet corrected CH4

concentration xTHC[NMC-FID]cor optionally corrected for initial THC contamination as 

determined in paragraph (a) of this section. 

(i) Use the following equation for penetration fractions determined using an NMC 

configuration as outlined in §1065.365(d):

THC[THC-FID]cor THC[NMC-FID]cor CH4[THC-FID]

NMHC

C2H6[NMC-FID] CH4[THC-FID] 1

x x RF

x

RFPF RF

 



 

Eq. 1065.660-2

Where:

xNMHC = concentration of NMHC.

xTHC[THC-FID]cor = concentration of THC, initial THC contamination and dry-to-wet 
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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corrected, as measured by the THC FID during sampling while bypassing the NMC.

xTHC[NMC-FID]cor = concentration of THC, initial THC contamination (optional) and dry-towet corrected, as measured by the NMC FID during sampling through the NMC.

RFCH4[THC-FID] = response factor of THC FID to CH4, according to §1065.360(d).

RFPFC2H6[NMC-FID] = nonmethane cutter combined ethane response factor and penetration 

fraction, according to §1065.365(d).

Example:

xTHC[THC-FID]cor = 150.3 μmol/mol

xTHC[NMC-FID]cor = 20.5 μmol/mol

RFPFC2H6[NMC-FID] = 0.019

RFCH4[THC-FID] = 1.05

NMHC

150.3 20.5 1.05

1 0.019 1.05

x

 



 

xNMHC = 131.4 μmol/mol

(ii) For penetration fractions determined using an NMC configuration as outlined in 

section §1065.365(e), use the following equation:

THC[THC-FID]cor CH4[NMC-FID] THC[NMC-FID]cor

NMHC

CH4[NMC-FID] C2H6[NMC-FID]

x PF x

x

PF PF

 





Eq. 1065.660-3

Where:

xNMHC = concentration of NMHC.

xTHC[THC-FID]cor = concentration of THC, initial THC contamination and dry-to-wet 

corrected, as measured by the THC FID during sampling while bypassing the NMC.

PFCH4[NMC-FID] = nonmethane cutter CH4 penetration fraction, according to §1065.365(e).

xTHC[NMC-FID]cor = concentration of THC, initial THC contamination (optional) and dry-towet corrected, as measured by the THC FID during sampling through the NMC.
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

822 of 971

PFC2H6[NMC-FID] = nonmethane cutter ethane penetration fraction, according to 

§1065.365(e).

Example: 

xTHC[THC-FID]cor = 150.3 μmol/mol

PFCH4[NMC-FID] = 0.990

xTHC[NMC-FID]cor = 20.5 μmol/mol

PFC2H6[NMC-FID] = 0.020

NMHC

150.3 0.990 20.5

0.990 0.020

x

 





xNMHC = 132.3 μmol/mol

(iii) For penetration fractions determined using an NMC configuration as outlined in 

section §1065.365(f), use the following equation:

THC[THC-FID]cor CH4[NMC-FID] THC[NMC-FID]cor CH4[THC-FID]

NMHC

CH4[NMC-FID] C2H6[NMC-FID] CH4[THC-FID]

x PF x RF

x

PF RFPF RF

  



 

Eq. 1065.660-4

Where:

xNMHC = concentration of NMHC.

xTHC[THC-FID]cor = concentration of THC, initial THC contamination and dry-to-wet 

corrected, as measured by the THC FID during sampling while bypassing the NMC.

PFCH4[NMC-FID] = nonmethane cutter CH4 penetration fraction, according to §1065.365(f).

xTHC[NMC-FID]cor = concentration of THC, initial THC contamination (optional) and dry-towet corrected, as measured by the THC FID during sampling through the NMC.

RFPFC2H6[NMC-FID] = nonmethane cutter CH4 combined ethane response factor and 

penetration fraction, according to §1065.365(f).

RFCH4[THC-FID] = response factor of THC FID to CH4, according to §1065.360(d).
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

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Example: 

xTHC[THC-FID]cor = 150.3 μmol/mol

PFCH4[NMC-FID] = 0.990

xTHC[NMC-FID]cor = 20.5 μmol/mol

RFPFC2H6[NMC-FID] = 0.019

RFCH4[THC-FID] = 0.980

NMHC

150.3 0.990 20.5 0.980

0.990 0.019 0.980

x

  



 

xNMHC = 132.5 μmol/mol

(3) For a GC-FID, calculate xNMHC using the THC analyzer’s response factor (RF) for 

CH4, from §1065.360, and the initial THC contamination and dry-to-wet corrected THC 

concentration xTHC[THC-FID]cor as determined in paragraph (a) of this section as follows:

NMHC THC[THC-FID]cor CH4[THC-FID] CH4 x x   RF  x

Eq. 1065.660-5

Where:

xNMHC = concentration of NMHC.

xTHC[THC-FID]cor = concentration of THC, initial THC contamination and dry-to-wet 

corrected, as measured by the THC FID.

xCH4= concentration of CH4, dry-to-wet corrected, as measured by the GC-FID.

RFCH4[THC-FID] = response factor of THC-FID to CH4.

Example:

xTHC[THC-FID[cor = 145.6 μmol/mol

RFCH4[THC-FID] = 0.970

xCH4 = 18.9 μmol/mol

xNMHC = 145.6 – 0.970 · 18.9

xNMHC = 127.3 μmol/mol
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

824 of 971

(c) CH4 determination. Use one of the following methods to determine CH4

concentration, xCH4:

(1) For nonmethane cutters, calculate xCH4 using the nonmethane cutter’s penetration 

fraction (PF) of CH4 and the response factor penetration fraction (RFPF) of C2H6 from 

§1065.365, the response factor (RF) of the THC FID to CH4 from §1065.360, the initial 

THC contamination and dry-to-wet corrected THC concentration xTHC[THC-FID]cor as 

determined in paragraph (a) of this section, and the dry-to-wet corrected CH4

concentration xTHC[NMC-FID]cor optionally corrected for initial THC contamination as 

determined in paragraph (a) of this section. 

(i) Use the following equation for penetration fractions determined using an NMC 

configuration as outlined in §1065.365(d):

THC[NMC-FID]cor THC[THC-FID]cor C2H6[NMC-FID]

CH4

C2H6[NMC-FID] CH4[THC-FID] 1

x x RFPF

x

RFPF RF

 



 

Eq. 1065.660-6

Where:

xCH4 = concentration of CH4.

xTHC[NMC-FID]cor = concentration of THC, initial THC contamination (optional) and dry-towet corrected, as measured by the NMC FID during sampling through the NMC.

xTHC[THC-FID]cor = concentration of THC, initial THC contamination and dry-to-wet 

corrected, as measured by the THC FID during sampling while bypassing the NMC.

RFPFC2H6[NMC-FID] = the combined ethane response factor and penetration fraction of the 

nonmethane cutter, according to §1065.365(d).

RFCH4[THC-FID] = response factor of THC FID to CH4, according to §1065.360(d).

Example:

xTHC[NMC-FID]cor = 10.4 μmol/mol

xTHC[THC-FID]cor = 150.3 μmol/mol

RFPFC2H6[NMC-FID] = 0.019

RFCH4[THC-FID] = 1.05
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

825 of 971

CH4

10.4 150.3 0.019

1 0.019 1.05

x

 



 

xCH4 = 7.69 μmol/mol

(ii) For penetration fractions determined using an NMC configuration as outlined in 

§1065.365(e), use the following equation:

 

THC[NMC-FID]cor THC[THC-FID]cor C2H6[NMC-FID]

CH4

CH4[THC-FID] CH4[NMC-FID] C2H6[NMC-FID]

x x PF

x

RF PF PF

 



 

Eq. 1065.660-7

Where:

xCH4 = concentration of CH4.

xTHC[NMC-FID]cor = concentration of THC, initial THC contamination (optional) and dry-towet corrected, as measured by the NMC FID during sampling through the NMC.

xTHC[THC-FID]cor = concentration of THC, initial THC contamination and dry-to-wet 

corrected, as measured by the THC FID during sampling while bypassing the NMC.

PFC2H6[NMC-FID] = nonmethane cutter ethane penetration fraction, according to 

§1065.365(e).

RFCH4[THC-FID] = response factor of THC FID to CH4, according to §1065.360(d).

PFCH4[NMC-FID] = nonmethane cutter CH4 penetration fraction, according to §1065.365(e).

Example: 

xTHC[NMC-FID]cor = 10.4 μmol/mol

xTHC[THC-FID]cor = 150.3 μmol/mol

PFC2H6[NMC-FID] = 0.020

RFCH4[THC-FID] = 1.05

PFCH4[NMC-FID] = 0.990

 

CH4

10.4 150.3 0.020

1.05 0.990 0.020

x

 



 
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xCH4 = 7.25 μmol/mol

(iii) For penetration fractions determined using an NMC configuration as outlined in 

§1065.365(f), use the following equation:

THC[NMC-FID]cor THC[THC-FID]cor C2H6[NMC-FID]

CH4

CH4[NMC-FID] C2H6[NMC-FID] CH4[THC-FID]

x x RFPF

x

PF RFPF RF

 



 

Eq. 1065.660-8

Where:

xCH4 = concentration of CH4.

xTHC[NMC-FID]cor = concentration of THC, initial THC contamination (optional) and dry-towet corrected, as measured by the NMC FID during sampling through the NMC.

xTHC[THC-FID]cor = concentration of THC, initial THC contamination and dry-to-wet 

corrected, as measured by the THC FID during sampling while bypassing the NMC.

RFPFC2H6[NMC-FID] = the combined ethane response factor and penetration fraction of the 

nonmethane cutter, according to §1065.365(f).

PFCH4[NMC-FID] = nonmethane cutter CH4 penetration fraction, according to §1065.365(f).

RFCH4[THC-FID] = response factor of THC FID to CH4, according to §1065.360(d).

Example: 

xTHC[NMC-FID]cor = 10.4 μmol/mol

xTHC[THC-FID]cor = 150.3 μmol/mol

RFPFC2H6[NMC-FID] = 0.019

PFCH4[NMC-FID] = 0.990

RFCH4[THC-FID] = 1.05

CH4

10.4 150.3 0.019

0.990 0.019 1.05

x

 



 

xCH4 = 7.78 μmol/mol
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(2) For a GC-FID, xCH4 is the actual dry-to-wet corrected CH4 concentration as measured 

by the analyzer.

* ** * *

81. Section 1065.667 is amended by adding a new paragraph (f) and revising paragraphs 

(a), (b), (c), (d), and (e) to read as follows:

§1065.667 Dilution air background emission correction.

(a) To determine the mass of background emissions to subtract from a diluted exhaust 

sample, first determine the total flow of dilution air, ndil, over the test interval. This may

be a measured quantity or a calculated quantity. Multiply the total flow of dilution air 

by the mean mole fraction (i.e., concentration) of a background emission. This may be 

a time-weighted mean or a flow-weighted mean (e.g., a proportionally sampled 

background). Finally, multiply by the molar mass, M, of the associated gaseous 

emission constituent. The product of ndil and the mean molar concentration of a 

background emission and its molar mass, M, is the total background emission mass, m. 

In the case of PM, where the mean PM concentration is already in units of mass per 

mole of sample, MPM , multiply it by the total amount of dilution air flow, and the result 

is the total background mass of PM, mPM. Subtract total background mass from total 

mass to correct for background emissions.

(b) You may determine the total flow of dilution air by a direct flow measurement.

(c) You may determine the total flow of dilution air by subtracting the calculated raw 

exhaust molar flow as described in §1065.655(f) from the measured dilute exhaust flow. 

This may be done by totaling continuous calculations or by using batch results.

(d) You may determine the total flow of dilution air from the measured dilute exhaust 

flow and a chemical balance of the fuel, intake air, and dilute exhaust as described in 

§1065.655. For this option, the molar flow of dilution air is calculated by multiplying 

the dilute exhaust flow by the mole fraction of dilution gas to dilute exhaust, dil/exh x ,

from the dilute chemical balance. This may be done by totaling continuous calculations 

or by using batch results. For example, to use batch results, the total flow of dilution air 

is calculated by multiplying the total flow of diluted exhaust, ndexh, by the flow-weighted 

mean mole fraction of dilution air in diluted exhaust, dil/exh x . Calculate dil/exh x using 

flow-weighted mean concentrations of emissions in the chemical balance, as described 

in §1065.655. The chemical balance in §1065.655 assumes that your engine operates 

stoichiometrically, even if it is a lean-burn engine, such as a compression-ignition 

engine. Note that for lean-burn engines this assumption could result in an error in 

emission calculations. This error could occur because the chemical balance in 

§1065.655 treats excess air passing through a lean-burn engine as if it was dilution air. 

If an emission concentration expected at the standard is about 100 times its dilution air 

background concentration, this error is negligible. However, if an emission 
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concentration expected at the standard is similar to its background concentration, this 

error could be significant. If this error might affect your ability to show that your 

engines comply with applicable standards, we recommend that you either determine the 

total flow of dilution air using one of the more accurate methods in paragraphs (b) or (c) 

of this section, or remove background emissions from dilution air by HEPA filtration, 

chemical adsorption, or catalytic scrubbing. You might also consider using a partialflow dilution technique such as a bag mini-diluter, which uses purified air as the dilution 

air.

(e) The following is an example of using the flow-weighted mean fraction of dilution air 

in diluted exhaust, dil/exh x , and the total mass of background emissions calculated using 

the total flow of diluted exhaust, ndexh, as described in §1065.650(c):

m x bkgnd   dil/exh mbkgnddexh

Eq. 1065.667-1

m M bkgnddexh bkgnd dexh   x n

Eq. 1065.667-2

Example:

MNOx = 46.0055 g/mol

bkgnd x = 0.05 μmol/mol = 0.0510-6 mol/mol

ndexh = 23280.5 mol

dil/exh x = 0.843 mol/mol

6

bkgndNOxdexh m 46.0055 0.05 10 23280.5 

   

mbkgndNOxdexh = 0.0536 g

mbkgndNOx = 0.843 · 0.0536

mbkgndNOx = 0.0452 g

(f) The following is an example of using the fraction of dilution air in diluted exhaust, 

xdil/exh, and the mass rate of background emissions calculated using the flow rate of 

diluted exhaust, dexh n , as described in §1065.650(c) :

m x bkgnd   dil/exh mbkgnddexh  
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Eq. 1065.667-3

m M bkgnddexh bkgnd dexh     x n

Eq. 1065.667-4

Example:

MNOx = 46.0055 g/mol

xbkgnd = 0.05 μmol/mol = 0.0510-6 mol/mol

dexh n = 23280.5 mol/s

xdil/exh = 0.843 mol/mol

6

bkgndNOxdexh m 46.0055 0.05 10 23280.5 

    

mbkgndNOxdexh  = 0.0536 g/hr

mbkgndNOx  = 0.843 · 0.0536

mbkgndNOx  = 0.0452 g/hr

82. Section 1065.670 is amended by revising the introductory paragraph to read as 

follows:

§1065.670 NOx intake-air humidity and temperature corrections.

See the standard-setting part to determine if you may correct NOx emissions for the 

effects of intake-air humidity or temperature. Use the NOx intake-air humidity and 

temperature corrections specified in the standard-setting part instead of the NOx intakeair humidity correction specified in this part 1065. If the standard-setting part does not 

prohibit correcting NOx emissions for intake-air humidity according to this part 1065, 

correct NOx concentrations for intake-air humidity as described in this section. See 

§1065.650(c)(1) for the proper sequence for applying the NOx intake-air humidity and 

temperature corrections. You may use a time-weighted mean combustion air humidity to 

calculate this correction if your combustion air humidity remains within a tolerance of 

±0.0025 mol/mol of the mean value over the test interval. For intake-air humidity

correction, use one of the following approaches:

* ** * *
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83. Section 1065.675 is amended by revising paragraph (d) to read as follows:

§1065.675 CLD quench verification calculations.

* ** * *

(d) Calculate quench as follows:

NOwet

H2Omeas H2Oexp NOmeas CO2exp

NOdry H2Omeas NOact CO2act

1

1 1 100 %

x

x x x x

quench

x x x x

          

               

   

Eq. 1065.675-1

Where:

quench = amount of CLD quench.

xNOdry = concentration of NO upstream of a bubbler, according to §1065.370(e)(4).

xNOwet = measured concentration of NO downstream of a bubbler, according to 

§1065.370(e)(9).

xH2Oexp = maximum expected mole fraction of water during emission testing, according to 

paragraph (b) of this section.

xH2Omeas = measured mole fraction of water during the quench verification, according to 

§1065.370(e)(7).

xNOmeas = measured concentration of NO when NO span gas is blended with CO2 span 

gas, according to §1065.370(d)(10).

xNOact = actual concentration of NO when NO span gas is blended with CO2 span gas, 

according to §1065.370(d)(11) and calculated according to Equation 1065.675-2.

xCO2exp = maximum expected concentration of CO2 during emission testing, according to 

paragraph (c) of this section.

xCO2act = actual concentration of CO2 when NO span gas is blended with CO2 span gas, 

according to §1065.370(d)(9).

CO2act

NOact NOspan

CO2span

1

x

x x

x

 

   

 
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Eq. 1065.675-2

Where:

xNOspan = the NO span gas concentration input to the gas divider, according to 

§1065.370(d)(5).

xCO2span = the CO2 span gas concentration input to the gas divider, according to 

§1065.370(d)(4).

Example:

xNOdry = 1800.0 μmol/mol

xNOwet = 1739.6 μmol/mol

xH2Oexp = 0.030 mol/mol

xH2Omeas = 0.030 mol/mol

xNOmeas = 1515.2 μmol/mol

xNOspan = 3001.6 μmol/mol

xCO2exp = 3.2 %

xCO2span = 6.1 %

xCO2act = 2.98 %

NOact

2.98 1 3001.6 1535.24459 μmol/mol

6.1

x

 

      

1739.6

1 0.030 0.030 1515.2 3.2 1 1 100 %

1800.0 0.030 1535.24459 2.98

quench

          

               

   

quench = (–0.0036655 – 0. 014020171)100 % = –1.7685671 %

Subpart H—[Amended]
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84. Section 1065.750 is amended by revising paragraphs (a)(3) and (a)(4) to read as 

follows:

§1065.750 Analytical Gases.

* ** * *

(a) * * *

(3) Use the following gas mixtures, with gases traceable within ±1 % of the NISTaccepted value or other gas standards we approve:

* ** * *

(4) You may use gases for species other than those listed in paragraph (a)(3) of this 

section (such as methanol in air, which you may use to determine response factors), as 

long as they are traceable to within ±3 % of the NIST-accepted value or other similar 

standards we approve, and meet the stability requirements of paragraph (b) of this 

section.

* ** * *

85. Section 1065.790 is amended by revising paragraph (a) to read as follows:

§1065.790 Mass standards.

(a) PM balance calibration weights. Use PM balance calibration weights that are certified 

as NIST-traceable within 0.1 % uncertainty. Calibration weights may be certified by any 

calibration lab that maintains NIST-traceability. Make sure your highest calibration 

weight has no greater than ten times the mass of an unused PM-sample medium.

Subpart J—[Amended]

86. Section 1065.915 is amended by revising Table 1 to read as follows:

§1065.915 PEMS instruments.

* ** * *

(a) * * *
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Table 1 of §1065.915–Recommended minimum PEMS measurement instrument performance

Measurement Measured 

quantity symbol

Rise time, t10-90, 

and

Fall time, t90-10

Recording update 

frequency Accuracy1 Repeatability1 Noise1

Engine speed transducer fn 1 s 1 Hz means

5 % of pt. or

1 % of max.

2 % of pt. or

1 % of max.

0.5 % of max

Engine torque estimator, BSFC

(This is a signal from an engine’s ECM)

T or BSFC 1 s 1 Hz means

8 % of pt. or

5 % of max.

2 % of pt. or

1 % of max.

1 % of max.

General pressure transducer

(not a part of another instrument)

p 5 s 1 Hz

5 % of pt. or

5 % of max.

2 % of pt. or

0.5 % of max.

1 % of max

Atmospheric pressure meter patmos 50 s 0.1 Hz 250 Pa 200 Pa 100 Pa

General temperature sensor

(not a part of another instrument)

T 5 s 1 Hz

1 % of pt. K or

5 K

0.5 % of pt. K or

2 K

0.5 % of max

0.5 K

General dewpoint sensor Tdew 50 s 0.1 Hz 3 K 1 K 1 K

Exhaust flow meter n 1 s 1 Hz means

5 % of pt. or

3 % of max.

2 % of pt. 2 % of max.
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Dilution air, inlet air, exhaust, and sample 

flow meters n 1 s 1 Hz means

2.5 % of pt. or

1.5 % of max.

1.25 % of pt. or

0.75 % of max.

1 % of max.

Continuous gas analyzer x 5 s 1 Hz

4 % of pt. or

4 % of meas.

2 % of pt. or

2 % of meas.

1 % of max.

Gravimetric PM balance mPM N/A N/A See §1065.790 0.5 g N/A

Inertial PM balance mPM N/A N/A

4 % of pt. or

4 % of meas.

2 % of pt. or

2 % of meas.

1 % of max

1Accuracy, repeatability, and noise are all determined with the same collected data, as described in §1065.305, and based on absolute values. “pt.” refers to the overall 

flow-weighted mean value expected at the standard; “max.” refers to the peak value expected at the standard over any test interval, not the maximum of the instrument’s 

range; “meas” refers to the actual flow-weighted mean measured over any test interval.

* ** * *
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87. Section 1065.925 is amended by revising paragraphs (h)(1), (h)(2), and (h)(3) to 

read as follows: 

§1065.925 PEMS preparation for field testing.

* ** * *

(h) * * *

(1) Select the HC analyzer range for measuring the maximum concentration expected at 

the HC standard.

(2) Zero the HC analyzers using a zero gas or ambient air introduced at the analyzer port. 

When zeroing a FID, use the FID’s burner air that would be used for in-use 

measurements (generally either ambient air or a portable source of burner air).

(3) Span the HC analyzer using span gas introduced at the analyzer port.

* ** * *

Subpart K—[Amended]

88. Section 1065.1001 is amended by revising the introductory text to read as follows: 

§1065.1001 Definitions.

* ** * *

Electric power generation application means an application whose purpose is to 

generate a precise frequency of electricity, which is characterized by an engine that 

controls engine speed very precisely. This would generally not apply to welders or 

portable home generators.

* ** * *

High-idle speed means the engine speed at which an engine governor function 

controls engine speed with operator demand at maximum and with zero load applied. 

“Warm high-idle speed” is the high-idle speed of a warmed-up engine.

High-speed governor means any device, system, or element of design that modulates the 

engine output torque for the purpose of limiting the maximum engine speed.

* ** * *
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Idle speed means the engine speed at which an engine governor function controls 

engine speed with operator demand at minimum and with minimum load applied (greater 

than or equal to zero). For engines without a governor function that controls idle speed, 

idle speed means the manufacturer-declared value for lowest engine speed possible with 

minimum load. This definition does not apply for operation designated as “high-idle 

speed.” “Warm idle speed” is the idle speed of a warmed-up engine.

* ** * *

Percent (%) means a representation of exactly 0.01. Numbers expressed as percentages 

in this part (such as a tolerance of ±2 %) have infinite precision, so 2 % and 2.000000000 

% have the same meaning. This means that where we specify some percentage of a total 

value, the calculated value has the same number of significant digits as the total value. 

For example, 2 % of a span value where the span value is 101.3302 is 2.026604.

* * * * *

Round means to apply the rounding convention specified in §1065.20(e), unless 

otherwise specified.

* * * * *

89. Section 1065.1005 is amended by revising the introductory text, paragraphs (a), (e), 

(f)(2), and (g) to read as follows: 

§1065.1005 Symbols, abbreviations, acronyms, and units of measure.

The procedures in this part generally follow the International System of Units (SI), as 

detailed in NIST Special Publication 811, “Guide for the Use of the International System 

of Units (SI),” which we incorporate by reference in §1065.1010. See §1065.20 for 

specific provisions related to these conventions. This section summarizes the way we use 

symbols, units of measure, and other abbreviations.

(a) Symbols for quantities. This part uses the following symbols and units of measure for 

various quantities:

Symbol Quantity Unit Unit symbol Units in terms of SI 

base units

 atomic hydrogen to carbon ratio mole per mole mol/mol 1

A area square meter m

2 m2

A0intercept of least squares regression
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A1 slope of least squares regression

 ratio of diameters meter per meter m/m 1

 atomic oxygen to carbon ratio mole per mole mol/mol 1

C

#

number of carbon atoms in a molecule

d Diameter meter m m

DR dilution ratio mole per mol mol/mol 1



error between a quantity and its 

reference

e

brake-specific emission or fuel 

consumption gram per kilowatt hour g/(kW·hr) g·3.6-1

·106·m-2·kg·s2

F F-test statistic

f frequency hertz Hz s

-1

fn angular speed (shaft) revolutions per minute r/min 2·π·60-1· m·m-1·s-1

 ratio of specific heats

(joule per kilogram 

kelvin) per (joule per 

kilogram kelvin) 

(J/(kg·K))/(J/(kg·K)) 1

K correction factor 1

l length meter m m

 viscosity, dynamic pascal second Pa·s m

-1

·kg·s-1

M molar mass1gram per mole g/mol 10-3·kg·mol-1

m mass kilogram kg kg
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m mass rate kilogram per second kg/s kg·s-1

 viscosity, kinematic meter squared per 

second m

2

/s m

2

·s-1

N total number in series

n amount of substance mole mol mol

n amount of substance rate mole per second mol/s mol·s-1

P power kilowatt kW 103·m2·kg·s-3

PF penetration fraction

p pressure pascal Pa m

-1

·kg·s-2

 mass density kilogram per cubic 

meter kg/m3

kg·m-3

r ratio of pressures pascal per pascal Pa/Pa 1

R

2

coefficient of determination

Ra average surface roughness micrometer m 10-6 m

Re# Reynolds number

RF response factor

RH relative humidity

 non-biased standard deviation

S Sutherland constant kelvin K K
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SEE standard estimate of error

T absolute temperature kelvin K K

T Celsius temperature degree Celsius °C K-273.15

T torque (moment of force) newton meter N·m m

2

·kg·s-2

t time second s s

t time interval, period, 1/frequency second s s

V volume cubic meter m

3 m3

V volume rate cubic meter per second m

3

/s m

3

·s-1

W work kilowatt hour kW·hr 3.6·10-6·m2·kg·s-2

wc carbon mass fraction gram per gram g/g 1

x amount of substance mole fraction 2 mole per mole mol/mol 1

x flow-weighted mean concentration mole per mole mol/mol 1

y generic variable

1

See paragraph (f)(2) of this section for the values to use for molar masses. Note that in the cases of NOx and HC, the 

regulations specify effective molar masses based on assumed speciation rather than actual speciation. 

2 Note that mole fractions for THC, THCE, NMHC, NMHCE, and NOTHC are expressed on a C1 equivalent basis. 

* ** * *

(e) Subscripts. This part uses the following subscripts to define a quantity:

Subscript Quantity
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abs absolute quantity

act actual condition

air air, dry

atmos atmospheric

cal calibration quantity

CFV critical flow venturi

cor corrected quantity

dil dilution air

dexh diluted exhaust

exh raw exhaust

exp expected quantity

hi,idle condition at high-idle

i an individual of a series

idle condition at idle

in quantity in

init initial quantity, typically before an emission test

j an individual of a series

max

the maximum (i.e., peak) value expected at the standard over a 

test interval; not the maximum of an instrument range
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meas measured quantity

out quantity out

part partial quantity

PDP positive-displacement pump

ref reference quantity

rev revolution

sat saturated condition

slip PDP slip

span span quantity

SSV subsonic venturi

std standard condition

test test quantity

test,alt alternate test quantity

uncor uncorrected quantity

zero zero quantity

(f) * * *

(2) This part uses the following molar masses or effective molar masses of chemical 

species:
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Symbol Quantity

g/mol

(10-3.kg.mol-1)

Mair molar mass of dry air128.96559

MAr molar mass of argon 39.948

MC molar mass of carbon 12.0107

MC3H8 molar mass of propane 44.09562

MCH4 molar mass of methane 16.043

MCO molar mass of carbon monoxide 28.0101

MCO2 molar mass of carbon dioxide 44.0095

MH molar mass of atomic hydrogen 1.00794

MH2 molar mass of molecular hydrogen 2.01588

MH2O molar mass of water 18.01528

MHe molar mass of helium 4.002602

MN molar mass of atomic nitrogen 14.0067

MN2 molar mass of molecular nitrogen 28.0134

MNMHC effective molar mass of nonmethane hydrocarbon213.875389

MNMHCE effective molar mass of nonmethane equivalent hydrocarbon213.875389

MNOx effective molar mass of oxides of nitrogen346.0055
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MN2O molar mass of nitrous oxide 44.0128

MO molar mass of atomic oxygen 15.9994

MO2 molar mass of molecular oxygen 31.9988

MS molar mass of sulfur 32.065

MTHC effective molar mass of total hydrocarbon213.875389

MTHCE effective molar mass of total hydrocarbon equivalent213.875389

1

See paragraph (f)(1) of this section for the composition of dry air.

2The effective molar masses of THC, THCE, NMHC, and NMHCE are defined by an atomic 

hydrogen-to-carbon ratio, , of 1.85.

3The effective molar mass of NOx

is defined by the molar mass of nitrogen dioxide, NO2.

(g) Other acronyms and abbreviations. This part uses the following additional 

abbreviations and acronyms: 

ASTM American Society for Testing and Materials

BMD bag mini-diluter

BSFC brake-specific fuel consumption

CARB California Air Resources Board

CFR Code of Federal Regulations

CFV critical-flow venturi

CI compression-ignition
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CITT Curb Idle Transmission Torque

CLD chemiluminescent detector

CVS constant-volume sampler

DF deterioration factor

ECM electronic control module

EFC electronic flow control

EGR exhaust gas recirculation

EPA Environmental Protection Agency

FEL Family Emission Limit

FID flame-ionization detector

GC gas chromatograph

GC-ECD gas chromatograph with an electron-capture detector

GC-FID gas chromatograph with a flame ionization detector

IBP initial boiling point

ISO International Organization for Standardization

LPG liquefied petroleum gas

NDIR nondispersive infrared

NDUV nondispersive ultraviolet
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NIST National Institute for Standards and Technology

NMC nonmethane cutter

PDP positive-displacement pump

PEMS portable emission measurement system

PFD partial-flow dilution

PMP Polymethylpentene

pt. a single point at the mean value expected at the standard.

PTFE polytetrafluoroethylene (commonly known as TeflonTM)

RE rounding error

RESS rechargeable energy storage system

RMC ramped-modal cycle

RMS root-mean square

RTD resistive temperature detector

SSV subsonic venturi

SI spark-ignition

UCL upper confidence limit

UFM ultrasonic flow meter

U.S.C. United States Code
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* ** * *

90. Section 1065.1010 is amended by revising paragraph (c) to read as follows: 

§1065.1010 Reference materials.

* * * * *

(c) NIST material. Table 3 of this section lists material from the National Institute of 

Standards and Technology that we have incorporated by reference. The first column lists 

the number and name of the material. The second column lists the section of this part 

where we reference it. Anyone may purchase copies of these materials from the 

Government Printing Office, Washington, DC 20402 or download them free from the 

Internet at www.nist.gov. Table 3 follows:

Table 3 of §1065.1010–NIST materials

Document number and name Part 1065 reference

NIST Special Publication 811, 2008 Edition, Guide for the Use of the International 

System of Units (SI), Barry N. Taylor, Physics Laboratory, and Ambler Thompson, 

Technology Services, March 2008

1065.20(a) and (e), 

1065.1005

NIST Technical Note 1297, 1994 Edition, Guidelines for Evaluating and Expressing 

the Uncertainty of NIST Measurement Results, Barry N. Taylor and Chris E. Kuyatt 1065.1001

* ** * *
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91. A new part 1066 is added to subchapter U to read as follows: 

Part 1066—Vehicle-Testing Procedures

Subpart A—Applicability and General Provisions 

Sec.

1066.1 Applicability.

1066.2 Submitting information to EPA under this part.

1066.5 Overview of this part 1066 and its relationship to the standard-setting part.

1066.10 Other procedures.

1066.15 Overview of test procedures.

1066.20 Units of measure and overview of calculations.

1066.25 Recordkeeping.

Subpart B—Equipment, Fuel, and Gas Specifications

1066.101 Overview.

Subpart C—Dynamometer Specifications 

1066.201 Dynamometer overview.

1066.210 Dynamometers.

1066.215 Summary of verification and calibration procedures for chassis dynamometers.

1066.220 Linearity verification.
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1066.225 Roll runout and diameter verification procedure.

1066.230 Time verification procedure.

1066.235 Speed verification procedure.

1066.240 Torque transducer verification and calibration.

1066.245 Response time verification.

1066.250 Base inertia verification.

1066.255 Parasitic loss verification.

1066.260 Parasitic friction compensation evaluation.

1066.265 Acceleration and deceleration verification.

1066.270 Unloaded coastdown verification.

1066.280 Driver’s aid.

Subpart D—Coastdown 

1066.301 Overview of coastdown procedures.

1066.310 Coastdown procedures for heavy-duty vehicles.

Subpart E—Vehicle Preparation and Running a Test

1066.401 Overview.

1066.407 Vehicle preparation and preconditioning.

1066.410 Dynamometer test procedure.

1066.420 Pre-test verification procedures and pre-test data collection.

1066.425 Engine starting and restarting.

1066.430 Performing emission tests
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Subpart F—Hybrids

1066.501 Overview.

Subpart G—Calculations

1066.601 Overview.

1066.610 Mass-based and molar-based exhaust emission calculations.

Subpart H—Definitions and Other Reference Material

1066.701 Definitions.

1066.705 Symbols, abbreviations, acronyms, and units of measure.

1066.710 Reference materials.

Authority: 42 U.S.C. 7401 - 7671q.

Subpart A—Applicability and General Provisions 

§1066.1 Applicability.

(a) This part describes the procedures that apply to testing we require for the following 

vehicles:

(1) Model year 2014 and later heavy-duty highway vehicles we regulate under 40 CFR 

part 1037 that are not subject to chassis testing for exhaust emissions under 40 CFR part 

86.

(2) [Reserved]
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(b) The procedures of this part may apply to other types of vehicles, as described in this 

part and in the standard-setting part.

(c) The term “you” means anyone performing testing under this part other than EPA. 

(1) This part is addressed primarily to manufacturers of vehicles, but it applies equally to 

anyone who does testing under this part for such manufacturers. 

(2) This part applies to any manufacturer or supplier of test equipment, instruments, 

supplies, or any other goods or services related to the procedures, requirements, 

recommendations, or options in this part. 

(d) Paragraph (a) of this section identifies the parts of the CFR that define emission 

standards and other requirements for particular types of vehicles. In this part, we refer to 

each of these other parts generically as the ''standard-setting part.'' For example, 40 CFR 

part 1037 is the standard-setting part for heavy-duty highway vehicles.

(e) Unless we specify otherwise, the terms “procedures” and “test procedures” in this part 

include all aspects of vehicle testing, including the equipment specifications, calibrations, 

calculations, and other protocols and procedural specifications needed to measure 

emissions.

(f) For additional information regarding these test procedures, visit our Web site at 

www.epa.gov, and in particular http://www.epa.gov/nvfel/testing/regulations.htm.

§1066.2 Submitting information to EPA under this part.

(a) You are responsible for statements and information in your applications for 

certification, requests for approved procedures, selective enforcement audits, laboratory

audits, production-line test reports, field test reports, or any other statements you make to 

us related to this part 1066. If you provide statements or information to someone for 

submission to EPA, you are responsible for these statements and information as if you 

had submitted them to EPA yourself.

(b) In the standard-setting part and in 40 CFR 1068.101, we describe your obligation to 

report truthful and complete information and the consequences of failing to meet this 

obligation. See also 18 U.S.C. 1001 and 42 U.S.C. 7413(c)(2). This obligation applies 

whether you submit this information directly to EPA or through someone else.

(c) We may void any certificates or approvals associated with a submission of 

information if we find that you intentionally submitted false, incomplete, or misleading 

information. For example, if we find that you intentionally submitted incomplete 

information to mislead EPA when requesting approval to use alternate test procedures, 

we may void the certificates for all engine families certified based on emission data 

collected using the alternate procedures. This would also apply if you ignore data from 

incomplete tests or from repeat tests with higher emission results.
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(d) We may require an authorized representative of your company to approve and sign 

the submission, and to certify that all the information submitted is accurate and complete. 

This includes everyone who submits information, including manufacturers and others.

(e) See 40 CFR 1068.10 for provisions related to confidential information. Note however 

that under 40 CFR 2.301, emission data is generally not eligible for confidential 

treatment.

(f) Nothing in this part should be interpreted to limit our ability under Clean Air Act 

section 208 (42 U.S.C. 7542) to verify that vehicles conform to the regulations.

§1066.5 Overview of this part 1066 and its relationship to the standard-setting part.

(a) This part specifies procedures that can apply generally to testing various categories of 

vehicles. See the standard-setting part for directions in applying specific provisions in 

this part for a particular type of vehicle. Before using this part's procedures, read the 

standard-setting part to answer at least the following questions:

(1) What drive schedules must I use for testing?

(2) Should I warm up the test vehicle before measuring emissions, or do I need to 

measure cold-start emissions during a warm-up segment of the duty cycle?

(3) Which exhaust constituents do I need to measure? Measure all exhaust constituents 

that are subject to emission standards, any other exhaust constituents needed for 

calculating emission rates, and any additional exhaust constituents as specified in the 

standard-setting part. We may approve your request to omit measurement of N2O and 

CH4 for a vehicle, provided it is not subject to an N2O or CH4 emission standard and we 

determine that other information is available to give us a reasonable basis for estimating 

or approximating the vehicle’s emission rates.

(4) Do any unique specifications apply for test fuels?

(5) What maintenance steps may I take before or between tests on an emission-data 

vehicle?

(6) Do any unique requirements apply to stabilizing emission levels on a new vehicle?

(7) Do any unique requirements apply to test limits, such as ambient temperatures or 

pressures?

(8) Is field testing required or allowed, and are there different emission standards or 

procedures that apply to field testing? 

(9) Are there any emission standards specified at particular operating conditions or 

ambient conditions?
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(10) Do any unique requirements apply for durability testing?

(b) The testing specifications in the standard-setting part may differ from the 

specifications in this part. In cases where it is not possible to comply with both the 

standard-setting part and this part, you must comply with the specifications in the 

standard-setting part. The standard-setting part may also allow you to deviate from the 

procedures of this part for other reasons.

(c) The following table shows how this part divides testing specifications into subparts:

Table 1 of §1066.5—Description of Part 1066 subparts.

This subpart Describes these specifications or procedures

Subpart A Applicability and general provisions.

Subpart B Equipment for testing.

Subpart C Dynamometer specifications.

Subpart D Coastdowns for testing.

Subpart E How to prepare your vehicle and run an emission test.

Subpart F How to test hybrid vehicles.

Subpart G Test procedure calculations.

Subpart H Definitions and reference material.

§1066.10 Other procedures.

(a) Your testing. The procedures in this part apply for all testing you do to show 

compliance with emission standards, with certain exceptions listed in this section. In 

some other sections in this part, we allow you to use other procedures (such as less 
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precise or less accurate procedures) if they do not affect your ability to show that your 

vehicles comply with the applicable emission standards. This generally requires emission 

levels to be far enough below the applicable emission standards so that any errors caused 

by greater imprecision or inaccuracy do not affect your ability to state unconditionally

that the engines meet all applicable emission standards.

(b) Our testing. These procedures generally apply for testing that we do to determine if 

your vehicles comply with applicable emission standards. We may perform other testing 

as allowed by the Act.

(c) Exceptions. We may allow or require you to use procedures other than those 

specified in this part for laboratory testing, field testing, or both, as described in 40 CFR 

1065.10(c). All the test procedures noted as exceptions to the specified procedures are 

considered generically as "other procedures." Note that the terms "special procedures" 

and "alternate procedures" have specific meanings; "special procedures" are those 

allowed by 40 CFR 1065.10(c)(2) and "alternate procedures" are those allowed by 40 

CFR 1065.10(c)(7). If we require you to request approval to use other procedures under 

this paragraph (c), you may not use them until we approve your request.

§1066.15 Overview of test procedures.

This section outlines the procedures to test vehicles that are subject to emission standards.

(a) In the standard-setting part, we set emission standards in g/mile (or g/km), for the 

following constituents:

(1) Total oxides of nitrogen, NOx.

(2) Hydrocarbons (HC), which may be expressed in the following ways:

(i) Total hydrocarbons, THC.

(ii) Nonmethane hydrocarbons, NMHC, which results from subtracting methane (CH4) 

from THC.

(iii) Total hydrocarbon-equivalent, THCE, which results from adjusting THC 

mathematically to be equivalent on a carbon-mass basis.

(iv) Nonmethane hydrocarbon-equivalent, NMHCE, which results from adjusting NMHC 

mathematically to be equivalent on a carbon-mass basis.

(3) Particulate mass, PM.

(4) Carbon monoxide, CO.
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(b) Note that some vehicles may not be subject to standards for all the emission 

constituents identified in paragraph (a) of this section.

(c) We generally set emission standards over test intervals and/or drive schedules, as 

follows:

(1) Vehicle operation. Testing may involve measuring emissions and miles travelled in a 

laboratory-type environment or in the field. The standard-setting part specifies how test 

intervals are defined for field testing. Refer to the definitions of “duty cycle” and “test 

interval” in §1066.701. Note that a single drive schedule may have multiple test intervals 

and require weighting of results from multiple test phases to calculate a composite 

distance-based emission value to compare to the standard.

(2) Constituent determination. Determine the total mass of each constituent over a test 

interval by selecting from the following methods:

(i) Continuous sampling. In continuous sampling, measure the constituent’s 

concentration continuously from raw or dilute exhaust. Multiply this concentration by

the continuous (raw or dilute) flow rate at the emission sampling location to determine 

the constituent’s flow rate. Sum the constituent’s flow rate continuously over the test 

interval. This sum is the total mass of the emitted constituent.

(ii) Batch sampling. In batch sampling, continuously extract and store a sample of raw or 

dilute exhaust for later measurement. Extract a sample proportional to the raw or dilute 

exhaust flow rate, as applicable. You may extract and store a proportional sample of 

exhaust in an appropriate container, such as a bag, and then measure HC, CO, and NOx

concentrations in the container after the test phase. You may deposit PM from 

proportionally extracted exhaust onto an appropriate substrate, such as a filter. In this 

case, divide the PM by the amount of filtered exhaust to calculate the PM concentration. 

Multiply batch sampled concentrations by the total (raw or dilute) flow from which it was 

extracted during the test interval. This product is the total mass of the emitted 

constituent.

(iii) Combined sampling. You may use continuous and batch sampling simultaneously

during a test interval, as follows:

(A) You may use continuous sampling for some constituents and batch sampling for 

others.

(B) You may use continuous and batch sampling for a single constituent, with one being 

a redundant measurement, subject to the provisions of 40 CFR 1065.201. 

(d) Refer to the standard-setting part for calculations to determine g/mile emission rates.

(e) The regulation highlights several specific cases where good engineering judgment is 

especially relevant. You must use good engineering judgment for all aspects of testing 

under this part, not only for those provisions where we specifically re-state this 

requirement.
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§1066.20 Units of measure and overview of calculations.

(a) System of units. The procedures in this part follows both conventional English Units 

and the International System of Units (SI), as detailed in NIST Special Publication 811, 

“Guide for the Use of the International System of Units (SI),” which we incorporate by

reference in §1066.710.

(b) Units conversion. Use good engineering judgment to convert units between 

measurement systems as needed. The following conventions are used throughout this 

document and should be used to convert units as applicable:

(1) 1 hp = 33,000 ft·lbf/min = 550 ft·lbf/s = 0.7457 kW.

(2) 1 lbf = 32.174 ft·lbm/s2 = 4.4482 N.

(3) 1 inch = 25.4 mm.

(c) Rounding. The rounding provisions of 40 CFR 1065.20 apply for calculations in this 

part. This generally specifies that you round final values but not intermediate values. 

Use good engineering judgment to record the appropriate number of significant digits for 

all measurements.

(d) Interpretation of ranges. Interpret a range as a tolerance unless we explicitly identify

it as an accuracy, repeatability, linearity, or noise specification. See 40 CFR 1065.1001 

for the definition of tolerance. In this part, we specify two types of ranges:

(1) Whenever we specify a range by a single value and corresponding limit values above 

and below that value, target any associated control point to that single value. Examples 

of this type of range include “±10 % of maximum pressure”, or “(30 ±10) kPa”.

(2) Whenever we specify a range by the interval between two values, you may target any 

associated control point to any value within that range. An example of this type of range 

is “(40 to 50) kPa”. 

(e) Scaling of specifications with respect to an applicable standard. Because this part 

1066 applies to a wide range of vehicles and emission standards, some of the 

specifications in this part are scaled with respect to a vehicle’s applicable standard or 

weight. This ensures that the specification will be adequate to determine compliance, but 

not overly burdensome by requiring unnecessarily high-precision equipment. Many of 

these specifications are given with respect to a “flow-weighted mean” that is expected at 

the standard or during testing. Flow-weighted mean is the mean of a quantity after it is 

weighted proportional to a corresponding flow rate. For example, if a gas concentration 

is measured continuously from the raw exhaust of an engine, its flow-weighted mean 

concentration is the sum of the products of each recorded concentration times its 

respective exhaust flow rate, divided by the sum of the recorded flow rates. As another 

example, the bag concentration from a CVS system is the same as the flow-weighted 
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mean concentration, because the CVS system itself flow-weights the bag concentration. 

Refer to 40 CFR 1065.602 for information needed to estimate and calculate flowweighted means.

§1066.25 Recordkeeping.

The procedures in this part include various requirements to record data or other 

information. Refer to the standard-setting part regarding recordkeeping requirements. If 

the standard-setting part does not specify recordkeeping requirements, store these records 

in any format and on any media and keep them readily available for one year after you 

send an associated application for certification, or one year after you generate the data if 

they do not support an application for certification. You must promptly send us 

organized, written records in English if we ask for them. We may review them at any

time.

Subpart B—Equipment, Fuel, and Gas Specifications 

§1066.101 Overview.

(a) This subpart addresses equipment related to emission testing, as well as test fuels and 

analytical gases. This section addresses emission sampling and analytical equipment, test 

fuels, and analytical gases.

(b) The provisions of 40 CFR part 1065 specify engine-based procedures for measuring 

emissions. Except as specified otherwise in this part, the provisions of 40 CFR part 1065 

apply for testing required by this part as follows:

(1) The provisions of 40 CFR 1065.140 through 1065.195 specify equipment for exhaust 

dilution and sampling systems. 

(2) The provisions of 40 CFR part 1065, subparts C and D, specify measurement 

instruments and their calibrations.

(3) The provisions of 40 CFR part 1065, subpart H, specify fuels, engine fluids, and 

analytical gases. 

(4) The provisions of 40 CFR part 1065, subpart J, describe how to measure emissions 

from vehicles operating outside of a laboratory, except that provisions related to 

measuring engine work do not apply.

(c) The provisions of this subpart are intended to specify systems that can very accurately 

and precisely measure emissions from motor vehicles. We may waive or modify the 
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specifications and requirements of this part for testing highway motorcycles or nonroad 

vehicles, consistent with good engineering judgment. For example, it may be appropriate 

to allow the use of a hydrokinetic dynamometer that is not able to meet all the 

performance specifications described in this subpart.

Subpart C—Dynamometer Specifications 

§1066.201 Dynamometer overview.

This subpart addresses chassis dynamometers and related equipment.

§1066.210 Dynamometers.

(a) General requirements. A chassis dynamometer typically uses electrically generated 

load forces combined with its rotational inertia to recreate the mechanical inertia and 

frictional forces that a vehicle exerts on road surfaces (known as “road load”). Load 

forces are calculated using vehicle-specific coefficients and response characteristics. The 

load forces are applied to the vehicle tires by rolls connected to intermediate 

motor/absorbers. The dynamometer uses a load cell to measure the forces the 

dynamometer rolls apply to the vehicle’s tires. 

(b) Accuracy and precision. The dynamometer’s output values for road load must be 

NIST-traceable. We may determine traceability to a specific international standards 

organization to be sufficient to demonstrate NIST-traceability. The force-measurement 

system must be capable of indicating force readings to a resolution of ±0.05 % of the 

maximum forces simulated by the dynamometer or ±0.9 N (±0.2 lbf), whichever is 

greater, during a test.

(c) Test cycles. The dynamometer must be capable of fully simulating applicable test 

cycles for the vehicles being tested as referenced in the corresponding standard-setting 

part.

(1) For vehicles with a gross vehicle weight rating (GVWR) at or below 14,000 lbs, the 

dynamometer must be able to fully simulate a driving schedule with a maximum speed of 

36 m/s (80 mph) and a maximum acceleration rate of 3.6 m/s2(8 mph/s) in two-wheel 

drive and four-wheel drive configurations.

(2) For vehicles with GVWR above 14,000 lbs, the dynamometer must be able to fully

simulate a driving schedule with a maximum speed of 29 m/s (65 mph) and a maximum 

acceleration rate of 1.3 m/s2(3 mph/s) in either two-wheel drive or four-wheel drive 

configurations.
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(d) Component requirements. The dynamometer must meet the following specifications:

(1) For vehicles with GVWR at or below 14,000 lbs, the nominal roll diameter must be 

1.20 to 1.25 meters. The dynamometer must have an independent drive roll for each axle 

being driven by the vehicle during an emission test.

(2) For vehicles with GVWR above 14,000 lbs, the nominal roll diameter must be at least 

1.20 meters and no greater than 3.10 meters. The dynamometer must have an 

independent drive roll for each axle, except that two drive axles may share a single drive 

roll. Use good engineering judgment to ensure that the dynamometer roll diameter is 

large enough to provide sufficient tire-roll contact area to avoid tire overheating and 

power losses from tire-roll slippage.

(3) If you measure force and speed at 10 Hz or faster, you may use good engineering 

judgment to convert those measurements to 1-Hz, 2-Hz, or 5-Hz values.

(4) The load applied by the dynamometer simulates forces acting on the vehicle during 

normal driving according to the following equation:

2 i i-1

i i i

i i-1

S S FR A B S C S M

t t



      



Where:

FR = total road-load force to be applied at the surface of the roll. The total force is the 

sum of the individual tractive forces applied at each roll surface.

i = a counter to indicate a point in time over the driving schedule. For a dynamometer 

operating at 10-Hz intervals over a 600-second driving schedule, the maximum value of i

is 6,000.

A = constant value representing the vehicle’s frictional load in lbf or newtons. See 

subpart C of this part.

B = coefficient representing load from drag and rolling resistance, which are a function of 

vehicle speed, in lbf/mph or N·s/m. See subpart C of this part.

S = linear speed at the roll surfaces as measured by the dynamometer, in mph or m/s. Let 

Si-1 = 0.

C = coefficient representing aerodynamic effects, which are a function of vehicle speed 

squared, in lbf/mph2or N·s

2

/m2. See subpart C of this part.

M = mass of vehicle in lbm or kg. Determine the vehicle’s mass based on the test weight, 

taking into account the effect of rotating axles, as specified in §1066.310(b)(7) and 
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dividing the weight by the acceleration due to gravity as specified in 40 CFR 1065.630, 

consistent with good engineering judgment.

t = elapsed time in the driving schedule as measured by the dynamometer, in seconds. 

Let ti-1 = 0.

(5) The dynamometer must be designed to generally apply an actual road-load force 

within ±1 % or ±9.8 N (±2.2 lbf) of the reference value, whichever is greater. 

Dynamometers that do not fully meet this specification may be used consistent with good 

engineering judgment. For example, slightly higher errors may be permissible during 

highly transient operation.

(e) Dynamometer manufacturer instructions. This part specifies that you follow the 

dynamometer manufacturer’s recommended procedures for things such as calibrations 

and general operation. If you perform testing with a dynamometer that you manufactured 

or if you otherwise do not have these recommended procedures, use good engineering 

judgment to establish the additional procedures and specifications we specify in this part, 

unless we specify otherwise. Keep records to describe these recommended procedures 

and how they are consistent with good engineering judgment. 

§1066.215 Summary of verification and calibration procedures for chassis 

dynamometers.

(a) Overview. This section describes the overall process for verifying and calibrating the 

performance of chassis dynamometers.

(b) Scope and frequency. The following table summarizes the required and 

recommended calibrations and verifications described in this subpart and indicates when 

they must occur:

Table 1 of §1066.215–Summary of required dynamometer calibrations and verifications.

Type of calibration or verification Minimum frequencya

§1066.220: Linearity verification

Speed: Upon initial installation, within 370 days before testing, and after 

major maintenance.

Torque (load): Upon initial installation, within 370 days before testing, and 

after major maintenance.
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§1066.225: Roll runout and diameter Upon initial installation and after major maintenance.

§1066.230: Time Upon initial installation and after major maintenance.

§1066.235: Speed measurement Upon initial installation, within 370 days before testing, and after major 

maintenance.

§1066.240: Torque (load) transducer Upon initial installation and after major maintenance.

§1066.245: Response time Upon initial installation and after major maintenance.

§1066.250: Base inertia Upon initial installation and after major maintenance.

§1066.255: Parasitic loss Upon initial installation, within 7 days before testing, and after major 

maintenance.

§1066.260: Parasitic friction 

compensation evaluation

Upon initial installation, within 7 days before testing, and after major 

maintenance.

§1066.265: Acceleration and 

deceleration Upon initial installation and after major maintenance.

§1066.270: Unloaded coastdown Upon initial installation, within 7 days before testing, and after major 

maintenance.

a

Perform calibrations and verifications more frequently, according to measurement system manufacturer instructions 

and good engineering judgment.

(c) Automated dynamometer verifications and calibrations. In some cases, dynamometers 

are designed with internal diagnostic and control features to accomplish the verifications 

and calibrations specified in this subpart. You may use these automated functions instead 

of following the procedures we specify in this subpart to demonstrate compliance with 

applicable requirements, consistent with good engineering judgment. 

(d) Sequence of verifications and calibrations. Upon initial installation and after major 

maintenance, perform the verifications and calibrations in the same sequence as noted in 

Table 1 of this section. At other times, you may need to perform specific verifications or 

calibration in a certain sequence, as noted in this subpart.
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(e) Corrections. Unless the regulation directs otherwise, if the dynamometer fails to meet 

any specified calibration or verification, make any necessary adjustments or repairs such 

that the dynamometer meets the specification before running a test. Repairs required to 

meet specifications are generally considered major maintenance under this part. 

§1066.220 Linearity verification.

(a) Scope and frequency. Perform linearity verifications upon initial installation, within 

370 days before testing, and after major maintenance. Note that these linearity

verifications may replace requirements previously referred to as calibrations. The intent 

of linearity verification is to determine that a measurement system responds accurately 

and proportionally over the measurement range of interest. Linearity verification 

generally consists of introducing a series of at least 10 reference values (or the 

manufacturer’s recommend number of reference values) to a measurement system. The 

measurement system quantifies each reference value. The measured values are then 

collectively compared to the reference values by using a least-squares linear regression 

and the linearity criteria specified in Table 1 of this section.

(b) Performance requirements. If a measurement system does not meet the applicable 

linearity criteria in Table 1 of this section, correct the deficiency by re-calibrating, 

servicing, or replacing components as needed. Repeat the linearity verification after 

correcting the deficiency to ensure that the measurement system meets the linearity

criteria. Before you may use a measurement system that does not meet linearity criteria, 

you must demonstrate to us that the deficiency does not adversely affect your ability to 

demonstrate compliance with the applicable standards.

(c) Procedure. Use the following linearity verification protocol, or use good engineering 

judgment to develop a different protocol that satisfies the intent of this section, as 

described in paragraph (a) of this section:

(1) In this paragraph (c), the letter “y” denotes a generic measured quantity, the 

superscript over-bar denotes an arithmetic mean (such as y ), and the subscript “ref” 

denotes the known or reference quantity being measured.

(2) Operate a dynamometer system at the specified temperatures and pressures. This may

include any specified adjustment or periodic calibration of the dynamometer system.

(3) Set dynamometer speed and torque to zero and apply the dynamometer brake to 

ensure a zero-speed condition.

(4) Span the dynamometer speed or torque signal. 

(5) After spanning, check for zero speed and torque. Use good engineering judgment to 

determine whether or not to rezero or re-span before continuing. 
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(6) For both speed and torque, use the dynamometer manufacturer’s recommendations 

and good engineering judgment to select reference values, yrefi, that cover a range of 

values that you expect would prevent extrapolation beyond these values during emission 

testing. We recommend selecting zero speed and zero torque as reference values for the 

linearity verification.

(7) Use the dynamometer manufacturer’s recommendations and good engineering 

judgment to select the order in which you will introduce the series of reference values. 

For example, you may select the reference values randomly to avoid correlation with 

previous measurements or the influence of hysteresis; you may select reference values in 

ascending or descending order to avoid long settling times of reference signals; or you 

may select values to ascend and then descend to incorporate the effects of any instrument 

hysteresis into the linearity verification.

(8) Set the dynamometer to operate at a reference condition. 

(9) Allow time for the dynamometer to stabilize while it measures the reference values.

(10) At a recording frequency of at least 1 Hz, measure speed and torque values for 30 

seconds and record the arithmetic mean of the recorded values, i

y . Refer to 40 CFR 

1065.602 for an example of calculating an arithmetic mean.

(11) Repeat the steps in paragraphs (c)(8) though (10) of this section until you measure 

speeds and torques at each of the reference conditions.

(12) Use the arithmetic means, i

y , and reference values, yrefi , to calculate least-squares 

linear regression parameters and statistical values to compare to the minimum 

performance criteria specified in Table 1 of this section. Use the calculations described 

in 40 CFR 1065.602. Using good engineering judgment, you may weight the results of 

individual data pairs (i.e., (yrefi, i

y )), in the linear regression calculations.

Table 1 of §1066.220–

Dynamometer measurement systems that require linearity verifications

Measurement 

system Quantity

Linearity criteria

| xmin(a1-1)+a0| a1 SEE r

2

Speed S <0.05 % · max

S 0.98-1.02 <2 % · max S >0.990

Torque (load) T <1 % · Tmax 0.98-1.02 <2 % · Tmax >0.990
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§1066.225 Roll runout and diameter verification procedure.

(a) Overview. This section describes the verification procedure for roll runout and roll 

diameter. Roll runout is a measure of the variation in roll radius around the 

circumference of the roll.

(b) Scope and frequency. Perform these verifications upon initial installation and after 

major maintenance.

(c) Roll runout procedure. Verify roll runout as follows:

(1) Perform this verification with laboratory and dynamometer temperatures stable and at 

equilibrium. Release the roll brake and shut off power to the dynamometer. Remove any 

dirt, rubber, rust, and debris from the roll surface. Mark measurement locations on the 

roll surface using a permanent marker. Mark the roll at a minimum of four equally

spaced locations across the roll width; we recommend taking measurements every 150 

mm across the roll. Secure the marker to the deck plate adjacent to the roll surface and 

slowly rotate the roll to mark a clear line around the roll circumference. Repeat this 

process for all measurement locations.

(2) Measure roll runout using a dial indicator with a probe that allows for measuring the 

position of the roll surface relative to the roll centerline as it turns through a complete 

revolution. The dial indicator must have a magnetic base assembly or other means of 

being securely mounted adjacent to the roll. The dial indicator must have sufficient range 

to measure roll runout at all points, with a minimum accuracy and precision of ±0.025 

mm. Calibrate the dial indicator according to the instrument manufacturer’s instructions.

(3) Position the dial indicator adjacent to the roll surface at the desired measurement 

location. Position the shaft of the dial indicator perpendicular to the roll such that the 

point of the dial indicator is slightly touching the surface of the roll and can move freely

through a full rotation of the roll. Zero the dial indicator according to the instrument 

manufacturer’s instructions. Avoid distortion of the runout measurement from the weight 

of a person standing on or near the mounted dial indicator.

(4) Slowly turn the roll through a complete rotation and record the maximum and 

minimum values from the dial indicator. Calculate runout as the difference between 

these maximum and minimum values. 

(5) Repeat the steps in paragraphs (c)(3) and (4) of this section for all measurement 

locations.

(6) The roll runout must be less than 0.25 mm at all measurement locations.

(d) Diameter procedure. Verify roll diameter based on the following procedure, or an 

equivalent procedure based on good engineering judgment: 

(1) Prepare the laboratory and the dynamometer as specified in paragraph (c)(1) of this 

section. 
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(2) Measure roll diameter using a Pi Tape®. Orient the Pi Tape® to the marker line at 

the desired measurement location with the Pi Tape® hook pointed outward. Temporarily 

secure the Pi Tape® to the roll near the hook end with adhesive tape. Slowly turn the 

roll, wrapping the Pi Tape® around the roll surface. Ensure that the Pi Tape® is flat and 

adjacent to the marker line around the full circumference of the roll. Attach a 2.26-kg 

weight to the hook of the Pi Tape® and position the roll so that the weight dangles freely. 

Remove the adhesive tape without disturbing the orientation or alignment of the Pi 

Tape®.

(3) Overlap the gage member and the vernier scale ends of the Pi Tape® to read the 

diameter measurement to the nearest 0.01 mm. Follow the manufacturer’s 

recommendation to correct the measurement to 20 °C, if applicable. 

(4) Repeat the steps in paragraphs (d)(2) and (3) of this section for all measurement 

locations.

(5) The measured roll diameter must be within ±0.25 mm of the specified nominal value 

at all measurement locations. You may revise the nominal value to meet this 

specification, as long as you use the corrected nominal value for all calculations in this 

subpart. 

§1066.230 Time verification procedure.

(a) Overview. This section describes how to verify the accuracy of the dynamometer’s 

timing device.

(b) Scope and frequency. Perform this verification upon initial installation and after 

major maintenance.

(c) Procedure. Perform this verification using one of the following procedures:

(1) WWV method. You may use the time and frequency signal broadcast by NIST from 

radio station WWV as the time standard if the trigger for the dynamometer timing circuit 

has a frequency decoder circuit, as follows:

(i) Dial station WWV at (303) 499-7111 and listen for the time announcement. Verify

that the trigger started the dynamometer timer. Use good engineering judgment to 

minimize error in receiving the time and frequency signal.

(ii) After at least 1000 seconds, re-dial station WWV and listen for the time 

announcement. Verify that the trigger stopped the dynamometer timer.

(iii) Compare the measured elapsed time, yact, to the corresponding time standard, yref, to 

determine the time error, yerror, using the following equation:
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act ref

error

ref

100 %

y y

y

y



 

Eq. 1066.230-1

(2) Ramping method. You may set up an operator-defined ramp function in the signal 

generator to serve as the time standard as follows:

(i) Set up the signal generator to output a marker voltage at the peak of each ramp to 

trigger the dynamometer timing circuit. Output the designated marker voltage to start the 

verification period.

(ii) After at least 1000 seconds, output the designated marker voltage to end the 

verification period.

(iii) Compare the measured elapsed time between marker signals, yact, to the 

corresponding time standard, yref, to determine the time error, yerror, using Equation 

1066.230-1.

(3) Dynamometer coastdown method. You may use a signal generator to output a known 

speed ramp signal to the dynamometer controller to serve as the time standard as follows:

(i) Generate upper and lower speed values to trigger the start and stop functions of the 

coastdown timer circuit. Use the signal generator to start the verification period. 

(ii) After at least 1000 seconds, use the signal generator to end the verification period. 

(iii) Compare the measured elapsed time between trigger signals, yact, to the 

corresponding time standard, yref, to determine the time error, yerror, using Equation 

1066.230-1.

(d) Performance evaluation. The time error determined in paragraph (c) of this section 

may not exceed ±0.001 %. 

§1066.235 Speed verification procedure.

(a) Overview. This section describes how to verify the accuracy and resolution of the 

dynamometer speed determination.

(b) Scope and frequency. Perform this verification upon initial installation, within 370 

days before testing, and after major maintenance.

(c) Procedure. Use one of the following procedures to verify the accuracy and resolution 

of the dynamometer speed simulation:
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(1) Pulse method. Connect a universal frequency counter to the output of the 

dynamometer’s speed-sensing device in parallel with the signal to the dynamometer 

controller. The universal frequency counter must be calibrated according to the 

instrument manufacturer’s instructions and be capable of measuring with enough 

accuracy to perform the procedure as specified in this paragraph (c)(1). Make sure the 

instrumentation does not affect the signal to the dynamometer control circuits. 

Determine the speed error as follows:

(i) Set the dynamometer to speed-control mode. Set the dynamometer speed to a value 

between 4.2 m/s and the maximum speed expected during testing; record the output of 

the frequency counter after 10 seconds. Determine the roll speed, Sact, using the 

following equation:

roll

act

f d S

n

 



Eq. 1066.235-1

Where:

f = frequency of the dynamometer speed sensing device, in s-1, accurate to at least four 

significant figures.

droll = nominal roll diameter, in m, accurate to the nearest 0.01 mm, consistent with 

§1066.225(d).

n = the number of pulses per revolution from the dynamometer roll speed sensor.

Example:

f = 2.9231 Hz = 2.9231 s-1

droll = 904.40 mm = 0.90440 m

n = 1 pulse/rev

act

2.9231 0.90440

1

S

 



Sact = 8.3053 m/s
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(ii) Compare the calculated roll speed, Sact, to the corresponding speed set point, Sref, to 

determine a value for speed error, Serror, using the following equation:

Serror = Sact - Sref

Eq. 1066.235-2

Example:

Sact = 8.3053 m/s

Sref = 8.3000 m/s

Serror = 8.3053 – 8.3000 = 0.0053 m/s

(2) Frequency method. Use the method described in this paragraph (c)(2) only if the 

dynamometer does not have a readily available output signal for speed sensing. Install a 

single piece of tape in the shape of an arrowhead on the surface of the dynamometer roll 

near the outer edge. Put a reference mark on the deck plate in line with the arrow. Install 

a stroboscope or photo tachometer on the deck plate and direct the flash toward the tape 

on the roll. The stroboscope or photo tachometer must be calibrated according to the 

instrument manufacturer’s instructions and be capable of measuring with enough 

accuracy to perform the procedure as specified in this paragraph (c)(2). Determine the 

speed error as follows:

(i) Set the dynamometer to speed control mode. Set the dynamometer speed to a value 

between 15 kph and the maximum speed expected during testing. Tune the stroboscope 

or photo tachometer until the signal matches the dynamometer roll speed. Record the 

frequency. Determine the roll speed, yact, using Equation 1066.235-1, using the 

stroboscope or photo tachometer’s frequency for f.

(ii) Compare the calculated roll speed, yact, to the corresponding speed set point, yref, to 

determine a value for speed error, yerror, using Equation 1066.235-2.

(d) Performance evaluation. The speed error determined in paragraph (c) of this section 

may not exceed ±0.02 m/s. 

§1066.240 Torque transducer verification and calibration.

Calibrate torque-measurement systems as described in 40 CFR 1065.310.
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§1066.245 Response time verification.

(a) Overview. This section describes how to verify the dynamometer’s response time.

(b) Scope and frequency. Perform this verification upon initial installation and after 

major maintenance.

(c) Procedure. Use the dynamometer’s automated process to verify response time. 

Perform this test at two different inertia settings corresponding approximately to the 

minimum and maximum vehicle weights you expect to test. Use good engineering 

judgment to select road-load coefficients representing vehicles of the appropriate weight. 

Determine the dynamometer’s settling response time, ts, based on the point at which there 

are no measured results more than 10 % above or below the final equilibrium value, as 

illustrated in Figure 1 of this section. The observed settling response time must be less 

than 100 milliseconds for each inertia setting. 
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Figure 1 of §1066.245—Example of a settling response time diagram.

§1066.250 Base inertia verification.

(a) Overview. This section describes how to verify the dynamometer’s base inertia.

(b) Scope and frequency. Perform this verification upon initial installation and after 

major maintenance. 

(c) Procedure. Verify the base inertia using the following procedure:

(1) Warm up the dynamometer according to the dynamometer manufacturer’s 

instructions. Set the dynamometer’s road-load inertia to zero and motor the rolls to 5 

mph. Apply a constant force to accelerate the roll at a nominal rate of 1 mph/s. Measure 

the elapsed time to accelerate from 10 to 40 mph, noting the corresponding speed and 

time points to the nearest 0.01 mph and 0.01 s. Also determine average force over the 

measurement interval.

(2) Starting from a steady roll speed of 45 mph, apply a constant force to the roll to 

decelerate the roll at a nominal rate of 1 mph/s. Measure the elapsed time to decelerate 

from 40 to 10 mph, noting the corresponding speed and time points to the nearest 0.01 

mph and 0.01 s. Also determine average force over the measurement interval.
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(3) Repeat the steps in paragraphs (c)(1) and (2) of this section for a total of five sets of 

results at the nominal acceleration rate and the nominal deceleration rate.

(4) Use good engineering judgment to select two additional acceleration and deceleration 

rates that cover the middle and upper rates expected during testing. Repeat the steps in 

paragraphs (c)(1) through (3) of this section at each of these additional acceleration and 

deceleration rates.

(5) Determine the base inertia, Ib, for each measurement interval using the following 

equation:

b

final initial

F

I

S S

t







Eq. 1066.250-1

Where:

F = average dynamometer force over the measurement interval as measured by the 

dynamometer, in ft·lbm/s2.

Sfinal = roll surface speed at the end of the measurement interval to the nearest 0.01 mph.

Sinitial = roll surface speed at the start of the measurement interval to the nearest 0.01 mph.

t = elapsed time during the measurement interval to the nearest 0.01 s.

Example:

F = 1.500 lbf = 48.26 ft·lbm/s2

Sfinal = 40.00 mph = 58.67 ft/s

Sinitial = 10.00 mph = 14.67 ft/s

t = 30.00 s

b

48.26

58.67 14.67

30.00

I 



Ib = 32.90 lbm
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(6) Determine the arithmetic mean value of base inertia from the five measurements at 

each acceleration and deceleration rate. Calculate these six mean values as described in 

40 CFR 1065.602(b). 

(7) Calculate the base inertia error, Iberror, for each measured base inertia, Ib, by

comparing it to the manufacturer’s stated base inertia, Ibref, using the following equation:

bref bact

berror

bref

100 % I I I

I



 

Eq. 1066.250-2

Example:

Ibref = 32.96 lbm

bact I = 33.01 lbm

berror

32.96 33.01 100 %

32.96

I



 

Iberror = –0.15 %

(8) Calculate the inertia error for each mean value of base inertia from paragraph (c)(6) of 

this section. Use Equation 1066.265-2, substituting the mean base inertias associated 

with each acceleration and deceleration rate for the individual base inertias.

(d) Performance evaluation. The dynamometer must meet the following specifications to 

be used for testing under this part:

(1) The base inertia error determined under paragraph (c)(7) of this section may not 

exceed ±0.50 % relative to any individual value. 

(2) The base inertia error determined under paragraph (c)(8) of this section may not 

exceed ±0.20 % relative to any mean value. 

§1066.255 Parasitic loss verification.

(a) Overview. Verify and correct the dynamometer’s parasitic loss. This procedure 

determines the dynamometer’s internal losses that it must overcome to simulate road 
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load. These losses are characterized in a parasitic loss curve that the dynamometer uses to 

apply compensating forces to maintain the desired road-load force at the roll surface.

(b) Scope and frequency. Perform this verification upon initial installation, within 7 days 

of testing, and after major maintenance. 

(c) Procedure. Perform this verification by following the dynamometer manufacturer’s 

specifications to establish a parasitic loss curve, taking data at fixed speed intervals to 

cover the range of vehicle speeds that will occur during testing. You may zero the load 

cell at the selected speed if that improves your ability to determine the parasitic loss. 

Parasitic loss forces may never be negative. Note that the torque transducers must be 

zeroed and spanned prior to performing this procedure.

(d) Performance evaluation. In some cases, the dynamometer automatically updates the 

parasitic loss curve for further testing. If this is not the case, compare the new parasitic 

loss curve to the original parasitic loss curve from the dynamometer manufacturer or the 

most recent parasitic loss curve you programmed into the dynamometer. You may

reprogram the dynamometer to accept the new curve in all cases, and you must 

reprogram the dynamometer if any point on the new curve departs from the earlier curve 

by more than ±4.5 N (±1.0 lbf). 

§1066.260 Parasitic friction compensation evaluation.

(a) Overview. This section describes how to verify the accuracy of the dynamometer’s 

friction compensation.

(b) Scope and frequency. Perform this verification upon initial installation, within 7 days 

before testing, and after major maintenance. Note that this procedure relies on proper 

verification or calibration of speed and torque, as described in §§1066.235 and1066.240. 

You must also first verify the dynamometer’s parasitic loss curve as specified in 

§1066.255.

(c) Procedure. Use the following procedure to verify the accuracy of the dynamometer’s 

friction compensation:

(1) Warm up the dynamometer as specified by the dynamometer manufacturer. 

(2) Perform a torque verification as specified by the dynamometer manufacturer. For 

torque verifications relying on shunt procedures, if the results do not conform to 

specifications, recalibrate the dynamometer using NIST-traceable standards as 

appropriate until the dynamometer passes the torque verification. Do not change the 

dynamometer’s base inertia to pass the torque verification.

(3) Set the dynamometer inertia to the base inertia with the road-load coefficients A, B, 

and C set to 0. Set the dynamometer to speed-control mode with a target speed of 10 

mph or a higher speed recommended by the dynamometer manufacturer. Once the speed 
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stabilizes at the target speed, switch the dynamometer from speed control to torque 

control and allow the roll to coast for 60 seconds. Record the initial and final speeds and 

the corresponding start and stop times. If friction compensation is executed perfectly, 

there will be no change in speed during the measurement interval.

(4) Calculate the friction compensation error, FCerror, using the following equation:

 

2 2

error final init 2

I

FC S S

t

  



Eq. 1066.260-5

Where:

I = dynamometer inertia setting, in lbf·s2/ft.

t = duration of the measurement interval, accurate to at least 0.01 s.

Sfinal = the roll speed corresponding to the end of the measurement interval, accurate to at 

least 0.1 mph.

Sinit = the roll speed corresponding to the start of the measurement interval, accurate to at 

least 0.1 mph.

Example:

I = 2000 lbm = 62.16 lbf· s2/ft

t = 60.0 s

Sfinal = 9.2 mph = 13.5 ft/s

Sinit = 10.0 mph = 14.7 ft/s

 

2 2

error

62.16 13.5 14.7

2 60.00

FC   



FCerror = –16.5 ft·lbf/s = –0.031 hp

(5) The friction compensation error may not exceed ±0.1 hp. 

§1066.265 Acceleration and deceleration verification.
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(a) Overview. This section describes how to verify the dynamometer’s ability to achieve 

targeted acceleration and deceleration rates. Paragraph (c) of this section describes how 

this verification applies when the dynamometer is programmed directly for a specific 

acceleration or deceleration rate. Paragraph (d) of this section describes how this 

verification applies when the dynamometer is programmed with a calculated force to 

achieve a targeted acceleration or deceleration rate.

(b) Scope and frequency. Perform this verification upon initial installation and after 

major maintenance.

(c) Verification of acceleration and deceleration rates. Activate the dynamometer’s 

function generator for measuring roll revolution frequency. If the dynamometer has no 

such function generator, set up a properly calibrated external function generator 

consistent with the verification described in this paragraph (c). Use the function 

generator to determine actual acceleration and deceleration rates as the dynamometer 

traverses speeds between 10 and 40 mph at various nominal acceleration and deceleration 

rates. Verify the dynamometer’s acceleration and deceleration rates as follows:

(1) Set up start and stop frequencies specific to your dynamometer by identifying the rollrevolution frequency, f, in revolutions per second (or Hz) corresponding to 10 mph and 

40 mph vehicle speeds, accurate to at least four significant figures, using the following 

equation:

roll

S n f

d 







Eq. 1066.265-1

Where:

S = the target roll speed, in inches per second (corresponding to drive speeds of 10 mph 

or 40 mph).

n = the number of pulses from the dynamometer’s roll-speed sensor per roll revolution.

droll = roll diameter, in inches.

(2) Program the dynamometer to accelerate the roll at a nominal rate of 1 mph/s from 10 

mph to 40 mph. Measure the elapsed time to reach the target speed, to the nearest 0.01 s. 

Repeat this measurement for a total of five runs. Determine the actual acceleration rate 

for each run, aact, using the following equation:

final init

act

S S

a

t




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Eq. 1066.265-2

Where:

aact = acceleration rate (decelerations have negative values).

Sfinal = the target value for the final roll speed.

Sinit = the setpoint value for the initial roll speed.

t = time to accelerate from Sinit to Sfinal.

Example:

Sinal = 40 mph

Sinit = 10 mph

t = 30.003 s

act

40.00 10.00

30.03

a





aact = 0.999 mph/s

(3) Program the dynamometer to decelerate the roll at a nominal rate of 1 mph/s from 40 

mph to 10 mph. Measure the elapsed time to reach the target speed, to the nearest 0.01 s. 

Repeat this measurement for a total of five runs. Determine the actual acceleration rate, 

aact, using Equation 1066.265-2

(4) Repeat the steps in paragraphs (c)(2) and (3) of this section for additional acceleration 

and deceleration rates in 1 mph/s increments up to and including one increment above the 

maximum acceleration rate expected during testing. Average the five repeat runs to 

calculate a mean acceleration rate, act a , at each setting.

(5) Compare each mean acceleration rate, act a , to the corresponding nominal acceleration 

rate, aref, to determine values for acceleration error, aerror, using the following equation:

act ref

error

ref

100 % a aa

a



 

Eq. 1066.265-4
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Example:

act a = 0.999 mph/s

aref = 1 mph/s

aerror = –0.100 %

(d) Verification of forces for controlling acceleration and deceleration. Program the 

dynamometer with a calculated force value and determine actual acceleration and 

deceleration rates as the dynamometer traverses speeds between 10 and 40 mph at 

various nominal acceleration and deceleration rates. Verify the dynamometer’s ability to 

achieve certain acceleration and deceleration rates with a given force as follows:

(1) Calculate the force setting, F, using the following equation:

F Ib   a

Eq. 1066.265-5

Where:

Ib = the dynamometer manufacturer’s stated base inertia, in lbf·s2/ft.

a = nominal acceleration rate, in ft/s2.

Example:

Ib = 2967 lbm = 92.217 lbf· s2/ft

a = 1 mph/s = 1.4667 ft/s2

F = 135.25 lbf

(2) Set the dynamometer to road-load mode and program it with a calculated force to 

accelerate the roll at a nominal rate of 1 mph/s from 10 mph to 40 mph. Measure the 

elapsed time to reach the target speed, to the nearest 0.01 s. Repeat this measurement for 

a total of five runs. Determine the actual acceleration rate, aact, for each run using 

Equation 1066.265-2. Repeat this step to determine measured “negative acceleration” 

rates using a calculated force to decelerate the roll at a nominal rate of 1 mph/s from 40 

mph to 10 mph. Average the five repeat runs to calculate a mean acceleration rate, act a , 

at each setting.
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(3) Repeat the steps in paragraph (d)(2) of this section for additional acceleration and 

deceleration rates as specified in paragraph (c)(4) of this section.

(4) Compare each mean acceleration rate, act a , to the corresponding nominal acceleration 

rate, aref, to determine values for acceleration error, aerror, using Equation 1066.265-4

(e) Performance evaluation. The acceleration error from paragraphs (c)(5) and (d)(4) of 

this section may not exceed ±1.0 %.

§1066.270 Unloaded coastdown verification.

(a) Overview. Use force measurements to verify the dynamometer’s settings based on 

coastdown procedures.

(b) Scope and frequency. Perform this verification upon initial installation, within 7 days 

of testing, and after major maintenance.

(c) Procedure. This procedure verifies the dynamometer’s settings derived from 

coastdown testing. For dynamometers that have an automated process for this procedure, 

perform this evaluation by setting the initial speed and final speed and the inertial and 

road-load coefficients as required for each test, using good engineering judgment to 

ensure that these values properly represent in-use operation. Use the following procedure 

if your dynamometer does not perform this verification with an automated process:

(1) Warm up the dynamometer as specified by the dynamometer manufacturer.

(2) With the dynamometer in coastdown mode, set the dynamometer inertia for the 

smallest vehicle weight that you expect to test and set A, B, and C road-load coefficients 

to values typical of those used during testing. Program the dynamometer to operate at 10 

mph. Perform a coastdown two times at this speed setting. Repeat these coastdown steps 

in 10 mph increments up to and including one increment above the maximum speed 

expected during testing. You may stop the verification before reaching 0 mph, with any

appropriate adjustments in calculating the results.

(3) Repeat the steps in paragraph (c)(2) of this section with the dynamometer inertia set 

for the largest vehicle weight that you expect to test.

(4) Determine the average coastdown force, F, for each speed and inertia setting using the 

following equation:

si I S F

t





Eq. 1066.270-1

Where:
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F = the average force measured during the coastdown for each speed and inertia setting, 

expressed in lbf· s2/ft and rounded to four significant figures.

I = the dynamometer’s inertia setting, in lbf· s2/ft.

Ssi = the speed setting at the start of the coastdown, expressed in ft/s and rounded to four 

significant figures.

t = coastdown time for each speed and inertia setting, accurate to at least 0.01 s.

Example:

I = 2000 lbm = 65.17 lbf · s2/ft

Ssi = 10 mph = 14.66 ft/s

t = 5.00 s

65.17 14.66

5.00

F





F = 191 lbf

(5) Calculate the target value of coastdown force, Fref, based on the applicable 

dynamometer parameters for each speed and inertia setting.

(6) Compare the mean value of the coastdown force measured for each speed and inertia 

setting, Fact , to the corresponding Fref to determine values for coastdown force error, 

Ferror, using the following equation:

act ref

error

ref

100 % F F F

F



 

Eq. 1066.270-2

Example:

Fref = 192 lbf

Fact = 191 lbf
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error

191 192 100 %

192

F



 

Ferror = –0.5 %

(7) The maximum allowable error, Ferrormax, for all speed and inertia settings is calculated 

from the following formula, except that Ferrormax for vehicles with GVWR above 14,000 

lbs may be up to ±1.0 %:

Ferrormax (%) = (2.2 lbf/Fref)·100

§1066.280 Driver’s aid.

Use good engineering judgment to provide a driver’s aid that facilitates compliance with 

the requirements of §1066.430.

Subpart D—Coastdown 

§1066.301 Overview of coastdown procedures.

(a) The coastdown procedures described in this subpart are used to determine the load 

coefficients (A, B, and C) for the simulated road-load equation in §1066.210(d)(3).

(b) The general procedure for performing coastdown tests and calculating load 

coefficients is described in SAE J1263 and SAE J2263 (incorporated by reference in 

§1066.710). This subpart specifies certain deviations from those procedures for certain 

applications.

(c) Use good engineering judgment for all aspects of coastdown testing. For example, 

minimize the effects of grade by performing coastdown testing on reasonably level 

surfaces and determining coefficients based on average values from vehicle operation in 

opposite directions over the course.

§1066.310 Coastdown procedures for heavy-duty vehicles.

This section describes coastdown procedures that are unique to heavy-duty motor 

vehicles. Note as specified in the standard setting parts, this section does not apply for 

certain heavy-duty vehicles, such as those regulated under 40 CFR part 86, Subpart S.
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(a) Determine load coefficients by performing a minimum of 16 valid coastdown runs (8 

in each direction). 

(b) Follow the provisions of Sections 1 through 9 of SAE J1263, and SAE J2263 

(incorporated by reference in §1066.710), except as described in this paragraph (b). The 

terms and variables identified in this paragraph (b) have the meaning given in SAE J1263 

or J2263 unless specified otherwise.

(1) The test condition specifications of SAE J1263 apply except as follows for wind and 

road conditions:

(i) We recommend that you do not perform coastdown testing on days for which winds 

are forecast to exceed 6.0 mph.

(ii) The grade of the test track or road must not be excessive (considering factors such 

asroad safety standards and effects on the coastdown results). Road conditions should 

follow Section 7.4 of SAE J1263, except that road grade may exceed 0.5%. If road grade 

is greater than 0.02% over the length of the test surface, then the road grade as a function 

of distance along the length of the test surface must be incorporated in the analysis. To 

calculate the force due to grade use Section 11.5 of SAE J2263.

(2) You must reach a top speed of greater than 70 mph such that data collection of the 

coastdown can start at or above 70 mph. Data collection must occur through a minimum 

speed at or below 15 mph. Data analysis for valid coastdown runs must include a 

maximum speed of 70 mph and a minimum speed of 15 mph.

(3) Gather data regarding wind speed and direction, in coordination with time-of-day

data, using at least one stationary electro-mechanical anemometer and suitable data 

loggers meeting the specifications of SAE J1263, as well as the following additional 

specifications for the anemometer placed adjacent to the test surface:

(i) Run the zero-wind and zero-angle calibration data collection.

(ii) The anemometer must have had its outputs recorded at a wind speed of 0.0 mph 

within 24 hours before each coastdown test in which it is used.

(iii) Record the location of the anemometer using a GPS measurement device adjacent to 

the test surface (approximately) at the midway distance along the test surface used for 

coastdowns.

(iv) Position the anemometer such that it will be at least 2.5 but not more than 3.0 vehicle 

widths from the test vehicle’s centerline as the test vehicle passes the location of that 

anemometer.

(v) Mount the anemometer at a height that is within 6 inches of half the test vehicle’s 

maximum height.
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(vi) Place the anemometer at least 50 feet from the nearest tree and at least 25 feet from 

the nearest bush (or equivalent roadside features).

(vii) The height of the grass surrounding the stationary anemometer may not exceed 10% 

of the anemometer’s mounted height, within a radius equal to the anemometer’s mounted 

height.

(4) You may split runs as per Section 9.3.1 of SAE J2263, but we recommend whole 

runs. If you split a run, analyze each portion separately, but count the split runs as one 

run with respect to the minimum number of runs required.

(5) You may perform consecutive runs in a single direction, followed by consecutive runs 

in the opposite direction, consistent with good engineering judgment. Harmonize starting 

and stopping points to the extent practicable to allow runs to be paired.

(6) All valid coastdown run times in each direction must be within 2.0 standard 

deviations of the mean of the valid coastdown run times (from 70 mph down to 15 mph) 

in that direction. Eliminate runs outside this range. After eliminating these runs you 

must have at least eight valid runs each direction.

(7) Determine drag area, CDA, as follows instead of using the procedure specified in SAE 

J1263, Section 10:

(i) Measure vehicle speed at fixed intervals over the coastdown run (generally at 10 Hz), 

including speeds at or above 15 mph and at or below 70 mph. Establish the height or 

altitude corresponding to each interval as described in SAE J2263 if you need to 

incorporate the effects of road grade.

(ii) Calculate the vehicle’s effective mass, Me, in kg by adding 56.7 kg to the vehicle 

mass for each tire making road contact. This accounts for the rotational inertia of the 

wheels and tires.

(iii) Calculate the road-load force for each measurement interval, Fi, using the following 

equation:

i i 1

i e

v v F M

t

    



Eq. 1066.310-1

Where:

v = Vehicle speed at the beginning and end of the measurement interval. Let v0 = 0.

Δt = Elapsed time over the measurement interval.
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(iv) Plot the data from all the coastdown runs on a single plot of Fi vs. vi

2

to determine the 

slope correlation, D, based on the following equation:

2

i e m i

h

F M g A D v

s



     



Eq. 1066.310-2

Where:

g = Gravitational acceleration = 9.81 m/s2.

Δh = Change in height or altitude over the measurement interval, in m. Assume Δh = 0 if 

you are not correcting for grade. 

Δs = Distance the vehicle travels down the road during the measurement interval, in m.

Am = the calculated value of the y-intercept based on the curve-fit.

(v) Calculate drag area, CDA, in m2 using the following equation:

adj

D

2 D

C A







Eq. 1066.310-3

Where:

ρ = Air density at reference conditions = 1.17 kg/m3.

adj

B

98.21

293

T

D D

P

   

          

Eq. 1066.310-4

T = Average ambient temperature during testing, in K.

PB = Average ambient pressuring during the test, in kPa.

(8) Determine the A, B, and C coefficients identified in §1066.210 as follows:

A= Am

B= 0

C= Dadj
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Subpart E—Vehicle Preparation and Running a Test

§1066.401 Overview.

(a) Use the procedures detailed in this subpart to measure vehicle emissions over a 

specified drive schedule. This subpart describes how to:

(1) Determine road-load power, test weight, and inertia class.

(2) Prepare the vehicle, equipment, and measurement instruments for an emission test.

(3) Perform pre-test procedures to verify proper operation of certain equipment and 

analyzers and to prepare them for testing.

(4) Record pre-test data.

(5) Sample emissions.

(6) Record post-test data.

(7) Perform post-test procedures to verify proper operation of certain equipment and 

analyzers.

(8) Weigh PM samples.

(b) An emission test generally consists of measuring emissions and other parameters 

while a vehicle follows the drive schedules specified in the standard-setting part. There 

are two general types of test cycles:

(1) Transient cycles. Transient test cycles are typically specified in the standard-setting 

part as a second-by-second sequence of vehicle speed commands. Operate a vehicle over 

a transient cycle such that the speed follows the target values. Proportionally sample 

emissions and other parameters and use the calculations in 40 CFR part 86, subpart B, or 

40 CFR part 1065, subpart G, to calculate emissions. The standard-setting part may

specify three types of transient testing based on the approach to starting the measurement, 

as follows:

(i) A cold-start transient cycle where you start to measure emissions just before starting 

an engine that has not been warmed up.

(ii) A hot-start transient cycle where you start to measure emissions just before starting a 

warmed-up engine.

(iii) A hot running transient cycle where you start to measure emissions after an engine is 

started, warmed up, and running.
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(2) Cruise cycles. Cruise test cycles are typically specified in the standard-setting part as 

a discrete operating point that has a single speed command.

(i) Start a cruise cycle as a hot running test, where you start to measure emissions after 

the engine is started and warmed up and the vehicle is running at the target test speed.

(ii) Sample emissions and other parameters for the cruise cycle in the same manner as a 

transient cycle, with the exception that the reference speed value is constant. Record 

instantaneous and mean speed values over the cycle.

§1066.407 Vehicle preparation and preconditioning.

This section describes steps to take before measuring exhaust emissions for those 

vehicles that are subject to evaporative or refueling emission tests as specified in the 

standard setting part. Other preliminary procedures may apply as specified in the 

standard-setting part.

(a) Prepare the vehicle for testing as described in 40 CFR 86.131.

(b) If testing will include measurement of refueling emissions, perform the vehicle 

preconditioning steps as described in 40 CFR 86.153. Otherwise, perform the vehicle 

preconditioning steps as described in 40 CFR 86.132.

§1066.410 Dynamometer test procedure.

(a) Dynamometer testing may consist of multiple drive cycles with both cold-start and 

hot-start portions, including prescribed soak times before each test phase. See the 

standard-setting part for test cycles and soak times for the appropriate vehicle category. 

A test phase consists of engine startup (with accessories operated according to the 

standard-setting part), operation over the drive cycle, and engine shutdown.

(b) During dynamometer operation, position a cooling fan that appropriately directs 

cooling air to the vehicle. This generally requires squarely positioning the fan within 30 

centimeters of the front of the vehicle and directing the airflow to the vehicle’s radiator. 

(1) For vehicles with GVWR at or below 14,000 lbs, you may use either of the following 

cooling fan configurations:

(i) Use a fixed-speed fan to appropriately direct cooling air to the vehicle with the engine 

compartment cover open. The fan capacity may not exceed 2.50 m3/s. If you determine 

that additional cooling is needed to properly represent in-use operation, use good 

engineering judgment to increase the fan’s capacity or use additional fans, subject to our 

approval.

(ii) Use a road-speed modulated fan system that achieves a linear speed of cooling air at 

the blower outlet that is within ±3.0 mph (±1.3 m/s) of the corresponding roll speed when 

vehicle speeds are between 5 and 30 mph (2.2 to 13.4 m/s), and within ±6.5 mph (±2.9 

m/s) of the corresponding roll speed at higher vehicle speeds. The fan must provide no 

cooling air for vehicle speeds below 5 mph, unless we approve your request to provide 

cooling during low-speed operation based on a demonstration that this is appropriate to 
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simulate cooling for in-use vehicles. We recommend that the cooling fan have a 

minimum opening of 0.2 m2and a minimum width of 0.8 m.

(2) For vehicles with GVWR above 14,000 lbs, use a road-speed modulated fan system 

that achieves a linear speed of cooling air at the blower outlet that is within ±3.0 mph 

(±1.3 m/s) of the corresponding roll speed when vehicle speeds are between 5 and 30 

mph (2.2 to 13.4 m/s), and within ±10 mph (±4.5 m/s) of the corresponding roll speed at 

higher vehicle speeds. The fan must provide no cooling air for vehicle speeds below 5 

mph, unless we approve your request to provide cooling during low-speed operation 

based on a demonstration that this is appropriate to simulate the cooling experienced by 

in-use vehicles. We recommend that the cooling fan have a minimum opening of 2.75 

m

2

, a minimum flow rate of 3,600 m3/min at 50 mph, and that it maintain a minimum 

speed profile across the duct, in the free stream flow, of ±15 % of the target flow rate.

(3) If the cooling specifications in this paragraph (b) are impractical for special vehicle 

designs, such as vehicles with rear-mounted engines, you may arrange for an alternative 

fan configuration that allows for proper simulation of vehicle cooling during in-use 

operation, subject to our approval. 

(c) Record the vehicle’s speed trace based on the time and speed data from the 

dynamometer. Record speed to at least the nearest 0.01 m/s or 0.1 mph and time to at 

least the nearest 0.1 s.

(d) You may perform practice runs to for operating the vehicle and the dynamometer 

controls to meet the driving tolerances specified in §1066.430 or adjust the emission 

sampling equipment. Verify that the accelerator pedal allows for enough control to 

closely follow the prescribed driving schedule. You may not measure emissions during a 

practice run.

(e) Inflate the drive wheel tires according to the vehicle manufacturer’s specifications. 

The drive wheels’ tire pressure must be the same for dynamometer operation and for 

coastdown procedures for determining road-load coefficients. Report these tire pressure 

values with the test results. 

(f) For vehicles with GVWR above 14,000 lbs, you must use a vehicle pull down 

mechanism that allows simulation of the actual normal forces that the tire and 

dynamometer roll interface would see if a loaded vehicle were actually being tested. Use 

of this mechanism will ensure that wheel slip does not occur when trying to accelerate the 

loaded vehicle.

(g) Use good engineering judgment when testing vehicles in four-wheel drive or allwheel drive mode. This may involve testing on a dynamometer with a separate 

dynamometer roll for each drive axle. This may also involve operation on a single roll, 

which may require disengaging the second set of drive wheels, either with a switch 

available to the driver or by some other means; however, operating such a vehicle on a 

single roll may occur only if this does not decrease emissions or energy consumption 
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relative to normal in-use operation. Alternatively, for heavy-duty motor vehicles, up to 

two drive axles may use a single drive roll, as described in §1066.210(d)(2).

(h) Warm up the dynamometer as recommended by the dynamometer manufacturer.

(i) Following the test, determine the actual driving distance by counting the number of 

dynamometer roll or shaft revolutions, or by integrating speed over the course of testing 

from a high-resolution encoder system.

§1066.420 Pre-test verification procedures and pre-test data collection.

(a) Follow the procedures for PM sample preconditioning and tare weighing as described 

in 40 CFR 1065.590 if your engine must comply with a PM standard.

(b) Unless the standard-setting part specifies different tolerances, verify at some point 

before the test that ambient conditions are within the tolerances specified in this 

paragraph (b). For purposes of this paragraph (b), “before the test” means any time from 

a point just prior to engine starting (excluding engine restarts) to the point at which 

emission sampling begins.

(1) Ambient temperature must be (20 to 30) °C. See §1066.430(m) for circumstances 

under which ambient temperatures must remain within this range during the test. 

(2) Atmospheric pressure must be (80.000 to 103.325) kPa. You are not required to 

verify atmospheric pressure prior to a hot-start test interval for testing that also includes a 

cold start.

(3) Dilution air conditions must meet the specifications in 40 CFR 1065.140, except in 

cases where you preheat your CVS before a cold-start test. We recommend verifying 

dilution air conditions just before starting each test phase.

(c) You may test vehicles at any intake-air humidity.

(d) You may perform a final calibration of proportional-flow control systems, which may

include performing practice runs.

(e) You may perform the following procedure to precondition sampling systems:

(1) Operate the vehicle over the test cycle.

(2) Operate any dilution systems at their expected flow rates. Prevent aqueous 

condensation in the dilution systems. 

(3) Operate any PM sampling systems at their expected flow rates.
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(4) Sample PM for at least 10 min using any sample media. You may change sample 

media during preconditioning. You must discard preconditioning samples without 

weighing them.

(5) You may purge any gaseous sampling systems during preconditioning.

(6) You may conduct calibrations or verifications on any idle equipment or analyzers 

during preconditioning.

(7) Proceed with the test sequence described in §1066.430.

(f) Verify the amount of nonmethane hydrocarbon (or equivalent) contamination in the 

exhaust and background HC sampling systems within 8 hours before the start of the first 

test drive cycle for each individual vehicle tested as described in 40 CFR 1065.520(g).

§1066.425 Engine starting and restarting.

(a) Start the vehicle’s engine as follows:

(1) At the beginning of the test cycle, start the engine according to the procedure you 

describe in your owners manual. In the case of hybrid vehicles, this would generally 

involve activating vehicle systems such that the engine will start when the vehicle’s 

control algorithms determine that the engine should provide power instead of or in 

addition to power from the rechargeable energy storage system (RESS). Unless we 

specify otherwise, engine starting throughout this part generally refers to this step of 

activating the system on hybrid vehicles, whether or not that causes the engine to start 

running.

(2) Place the transmission in gear as described by the test cycle in the standard-setting 

part. During idle operation, you may apply the brakes if necessary to keep the drive 

wheels from turning.

(b) If the vehicle does not start after your recommended maximum cranking time, wait 

and restart cranking according to your recommended practice. If you don’t recommend 

such a cranking procedure, stop cranking after 10 seconds, wait for 10 seconds, then start 

cranking gain for up to 10 seconds. You may repeat this for up to three start attempts. If 

the vehicle does not start after three attempts, you must determine and record the reason 

for failure to start. Shut off sampling systems and either turn the CVS off, or disconnect 

the exhaust tube from the tailpipe during the diagnostic period. Reschedule the vehicle 

for testing from a cold start.

(c) Repeat the recommended starting procedure if the engine has a “false start”.

(d) Take the following steps if the engine stalls:
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(1) If the engine stalls during an idle period, restart the engine immediately and continue 

the test. If you cannot restart the engine soon enough to allow the vehicle to follow the 

next acceleration, stop the driving schedule indicator and reactivate it when the vehicle 

restarts.

(2) If the engine stalls during operation other than idle, stop the driving schedule 

indicator, restart the engine, accelerate to the speed required at that point in the driving 

schedule, reactivate the driving schedule indicator, and continue the test.

(3) Void the test if the vehicle will not restart within one minute. If this happens, remove 

the vehicle from the dynamometer, take corrective action, and reschedule the vehicle for 

testing. Record the reason for the malfunction (if determined) and any corrective action. 

See the standard-setting part for instructions about reporting these malfunctions. 

§1066.430 Performing emission tests.

The overall test consists of prescribed sequences of fueling, parking, and driving at 

specified test conditions.

(a) Vehicles are tested for criteria pollutants and greenhouse gas emissions as described 

in the standard-setting part.

(b) Take the following steps before emission sampling begins:

(1) For batch sampling, connect clean storage media, such as evacuated bags or tareweighed filters.

(2) Start all measurement instruments according to the instrument manufacturer’s 

instructions and using good engineering judgment.

(3) Start dilution systems, sample pumps, and the data-collection system.

(4) Pre-heat or pre-cool heat exchangers in the sampling system to within their operating 

temperature tolerances for a test.

(5) Allow heated or cooled components such as sample lines, filters, chillers, and pumps 

to stabilize at their operating temperatures.

(6) Verify that there are no significant vacuum-side leaks according to 40 CFR 1065.345.

(7) Adjust the sample flow rates to desired levels using bypass flow, if desired. 

(8) Zero or re-zero any electronic integrating devices before the start of any test interval.

(9) Select gas analyzer ranges. You may automatically or manually switch gas analyzer 

ranges during a test only if switching is performed by changing the span over which the 

digital resolution of the instrument is applied. During a test you may not switch the gains 

of an analyzer’s analog operational amplifier(s).
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(10) Zero and span all continuous gas analyzers using NIST-traceable gases that meet the 

specifications of 40 CFR 1065.750. Span FID analyzers on a carbon number basis of one 

(C1). For example, if you use a C3H8 span gas of concentration 200 mol/mol, span the 

FID to respond with a value of 600 mol/mol. Span FID analyzers consistent with the 

determination of their respective response factors, RF, and penetration fractions, PF, 

according to 40 CFR 1065.365.

(11) We recommend that you verify gas analyzer responses after zeroing and spanning by

sampling a calibration gas that has a concentration near one-half of the span gas 

concentration. Based on the results and good engineering judgment, you may decide 

whether or not to re-zero, re-span, or re-calibrate a gas analyzer before starting a test.

(12) If you correct for dilution air background concentrations of associated engine 

exhaust constituents, start sampling and recording background concentrations.

(13) Turn on cooling fans immediately before starting the test.

(c) Operate vehicles during testing as follows:

(1) Where we do not give specific instructions, operate the vehicle according to your 

recommendations in the owners manual, unless those recommendations are 

unrepresentative of what may reasonably be expected for in-use operation.

(2) If vehicles have features that preclude dynamometer testing, modify these features as 

necessary to allow testing, consistent with good engineering judgment.

(3) Operate vehicles during idle as follows:

(i) For a vehicle with an automatic transmission, operate at idle with the transmission in 

“Drive” with the wheels braked, except that you may shift to “Neutral” for the first idle 

period and for any idle period longer than one minute. If you put the vehicle in “Neutral” 

during an idle, you must shift the vehicle into “Drive” with the wheels braked at least 5 

seconds before the end of the idle period. 

(ii) For vehicles with manual transmission, operate at idle with the transmission in gear 

with the clutch disengaged, except that you may shift to “Neutral” with the clutch 

disengaged for the first idle period and for any idle period longer than one minute. If you 

put the vehicle in “Neutral” during idle, you must shift to first gear with the clutch 

disengaged at least 5 seconds before the end of the idle period.

(4) Operate the vehicle with the appropriate accelerator pedal movement necessary to 

achieve the speed versus time relationship prescribed by the driving schedule. Avoid 

smoothing speed variations and excessive accelerator pedal perturbations.

(5) Operate the vehicle smoothly, following representative shift speeds and procedures. 

For manual transmissions, the operator shall release the accelerator pedal during each 

shift and accomplish the shift with minimum time. If the vehicle cannot accelerate at the 
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specified rate, operate it at maximum available power until the vehicle speed reaches the 

value prescribed for that time in the driving schedule.

(6) Decelerate without changing gears, using the brakes or accelerator pedal as necessary

to maintain the desired speed. Keep the clutch engaged on manual transmission vehicles 

and do not change gears after the end of the acceleration event. Depress manual 

transmission clutches when the speed drops below 6.7 m/s (15 mph), when engine 

roughness is evident, or when engine stalling is imminent.

(7) For test vehicles equipped with manual transmissions, shift gears in a way that 

represents reasonable shift patterns for in-use operation, considering vehicle speed, 

engine speed, and any other relevant variables. You may recommend a shift schedule in 

your owners manual that differs from your shift schedule during testing as long as you 

include both shift schedules in your application for certification. In this case, we may use 

the shift schedule you describe in your owners manual.

(d) See the standard-setting part for drive schedules. These are defined by a smooth trace 

drawn through the specified speed vs. time sequence.

(e) The driver must attempt to follow the target schedule as closely as possible, consistent 

with the specifications in paragraph (b) of this section. Instantaneous speeds must stay

within the following tolerances:

(1) The upper limit is 1.0 m/s (2 mph) higher than the highest point on the trace within 

1.0 s of the given point in time.

(2) The lower limit is 1.0 m/s (2 mph) lower than the lowest point on the trace within 1.0 

s of the given time.

(3) The same limits apply for vehicle preconditioning, except that the upper and lower 

limits for speed values are ±2.0 m/s (±4 mph).

(4) Void the test if you do not maintain speed values as specified in this paragraph (e)(4). 

Speed variations (such as may occur during gear changes or braking spikes) may occur as 

follows, provided that such variations are clearly documented, including the time and 

speed values and the reason for the deviation:

(i) Speed variations greater than the specified limits are acceptable for up to 2.0 seconds 

on any occasion.

(ii) For vehicles that are not able to maintain acceleration as specified in paragraph (c)(5) 

of this section, do not count the insufficient acceleration as being outside the specified 

limits.

(f) Figure 1 and Figure 2 of this section show the range of acceptable speed tolerances for 

typical points during testing. Figure 1 of this section is typical of portions of the speed 

curve that are increasing or decreasing throughout the 2-second time interval. Figure 2 of 
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this section is typical of portions of the speed curve that include a maximum or minimum 

value.
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(i) Figure 1 of §1066.430—Example of the allowable ranges for the driver’s trace.

(ii) Figure 2 of §1066.430—Example of the allowable ranges for the driver’s trace.

1.0 s

Time

S

p

e

e

d

Allowable 

Range

1.0

m

/s

1.0

m

/s

1.0 s

1.0 s

Time

S

p

e

e

d

Allowable 

Range

1.0

m

/s

1.0

m

/s

1.0 s
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(g) Start testing as follows:

(1) If a vehicle is already running and warmed up, and starting is not part of the test 

cycle, operate the vehicle as follows:

(i) For transient test cycles, control vehicle speeds to follow a drive schedule consisting 

of a series of idles, accelerations, cruises, and decelerations.

(ii) For cruise test cycles, control the vehicle operation to match the speed of the first 

phase of the test cycle. Follow the instructions in the standard-setting part to determine 

how long to stabilize the vehicle during each phase, how long to sample emissions at 

each phase, and how to transition between phases.

(2) If engine starting is part of the test cycle, initiate data logging, sampling of exhaust 

gases, and integrating measured values before starting the engine. Initiate the driver’s 

trace when the engine starts.

(h) At the end of each test interval, continue to operate all sampling and dilution systems 

to allow the response times to elapse. Then stop all sampling and recording, including 

the recording of background samples. Finally, stop any integrating devices and indicate 

the end of the duty cycle in the recorded data.

(i) Shut down the vehicle if it is part of the test cycle or if testing is complete.

(j) If testing involves engine shutdown followed by another test phase, start a timer for 

the vehicle soak when the engine shuts down.

(k) Take the following steps after emission sampling is complete:

(1) For any proportional batch sample, such as a bag sample or PM sample, verify that 

proportional sampling was maintained according to 40 CFR 1065.545. Void any samples 

that did not maintain proportional sampling according to specifications.

(2) Place any used PM samples into covered or sealed containers and return them to the 

PM-stabilization environment. Follow the PM sample post-conditioning and total 

weighing procedures in 40 CFR 1065.595. 

(3) As soon as practical after the test cycle is complete, or optionally during the soak 

period if practical, perform the following:

(i) Drift check all continuous gas analyzers and zero and span all batch gas analyzers no 

later than 30 minutes after the test cycle is complete, or during the soak period if 

practical.

(ii) Analyze any conventional gaseous batch samples no later than 30 minutes after a test 

phase is complete, or during the soak period if practical. Analyze nonconventional 
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gaseous batch samples, such as NMHCE sampling with ethanol, as soon as practicable 

using good engineering judgment.

(iii) Analyze background samples no later than 60 minutes after the test cycle is 

complete.

(4) After quantifying exhaust gases, verify drift as follows:

(i) For batch and continuous gas analyzers, record the mean analyzer value after 

stabilizing a zero gas to the analyzer. Stabilization may include time to purge the 

analyzer of any sample gas, plus any additional time to account for analyzer response. 

(ii) Record the mean analyzer value after stabilizing the span gas to the analyzer. 

Stabilization may include time to purge the analyzer of any sample gas, plus any

additional time to account for analyzer response. 

(iii) Use these data to validate and correct for drift as described in 40 CFR 1065.550.

(l) [Reserved]

(m) Measure and record ambient temperature and pressure. Also measure humidity, as 

required, such as for correcting NOx emissions. For testing vehicles with the following 

engines, you must record ambient temperature continuously to verify that it remains 

within the temperature range specified in §1066.420(b)(1) throughout the test:

(1) Air-cooled engines.

(2) Engines equipped with emission control devices that sense and respond to ambient 

temperature.

(3) Any other engine for which good engineering judgment indicates that this is 

necessary to remain consistent with 40 CFR 1065.10(c)(1).

Subpart F—Hybrids

§1066.501 Overview.

To correct fuel economy or emission results for Net Energy Change of the RESS, use the 

procedures specified for charge-sustaining operation in SAE J2711 (incorporated by 

reference in §1066.710).

Subpart G—Calculations
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§1066.601 Overview.

(a) This subpart describes how to–

(1) Use the signals recorded before, during, and after an emission test to calculate 

distance-specific emissions of each regulated pollutant.

(2) Perform calculations for calibrations and performance checks.

(3) Determine statistical values.

(b) You may use data from multiple systems to calculate test results for a single emission 

test, consistent with good engineering judgment. You may also make multiple 

measurements from a single batch sample, such as multiple weighing of a PM filter or 

multiple readings from a bag sample. You may not use test results from multiple 

emission tests to report emissions. We allow weighted means where appropriate. You 

may discard statistical outliers, but you must report all results.

§1066.610 Mass-based and molar-based exhaust emission calculations.

(a) Calculate your total mass of emissions over a test cycle as specified in 40 CFR 86.144 

or 40 CFR part 1065, subpart G.

(b) For composite emission calculations over multiple test phases and corresponding 

weighting factors, see the standard-setting part.

Subpart H—Definitions and Other Reference Material

§1066.701 Definitions.

The definitions in this section apply to this part. The definitions apply to all subparts 

unless we note otherwise. Other terms have the meaning given in 40 CFR part 1065. 

The definitions follow:

Base inertia means a value expressed in mass units to represent the rotational inertia 

of the rotating dynamometer components between the vehicle driving tires and the 

dynamometer torque-measuring device, as specified in §1066.250.

Driving schedule means a series of vehicle speeds that a vehicle must follow during a 

test. Driving schedules are specified in the standard-setting part. A driving schedule may

consist of multiple test phases.
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Duty cycle means a set of weighting factors and the corresponding test cycles, where the 

weighting factors are used to combine the results of multiple test phases into a composite 

result.

Road-load coefficients means sets of A, B, and C road-load force coefficients that are 

used in the dynamometer road-load simulation, where road-load force at speed S equals A 

+ B·S + C·S

2

.

Test phase means a duration over which a vehicle’s emission rates are determined for 

comparison to an emission standard. For example, the standard-setting part may specify

a complete duty cycle as a cold-start test phase and a hot-start test phase. In cases where 

multiple test phases occur over a duty cycle, the standard-setting part may specify

additional calculations that weight and combine results to arrive at composite values for 

comparison against the applicable standards.

Test weight has the meaning given in the standard-setting part.

Unloaded coastdown means a dynamometer coastdown run with the vehicle wheels 

off the roll surface.

§1066.705 Symbols, abbreviations, acronyms, and units of measure.

The procedures in this part generally follow either the International System of Units (SI) 

or the United States customary units, as detailed in NIST Special Publication 811, “Guide 

for the Use of the International System, of Units (SI),” which we incorporate by reference 

in §1066.710. See 40 CFR 1065.20 for specific provisions related to these conventions. 

This section summarizes the way we use symbols, units of measure, and other 

abbreviations.

(a) Symbols for quantities. This part uses the following symbols and units of measure for 

various quantities:

Symbol Quantity Unit Unit symbol Unit in terms of SI 

base units

a acceleration feet per second squared or 

meters per second squared ft/s2

or m/s2 m·s-2

d diameter meters m m

F force pound force or newton lbf or N kg·s-2
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f frequency hertz Hz s

-1

I inertia pound mass or kilogram lbm or kg kg

i indexing variable

M mass pound mass or kilogram lbm or kg kg

N total number in series

n total number of pulses in a series

R dynamometer roll revolutions revolutions per minute rpm 2·π·60-1· m·m-1·s-1

RL road-load coefficient horsepower or kilowatt hp or kW 103·m2·kg·s-3

S speed miles per hour or meters per 

second mph or m/s m·s-1

T Celsius temperature degree Celsius °C K-273.15

T torque (moment of force) newton meter N·m m

2

·kg·s-2

t time second s s

t time interval, period, 1/frequency second s s

y generic variable

(b) Symbols for chemical species. This part uses the following symbols for chemical 

species and exhaust constituents:

Symbol Species
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CH4 methane

CO carbon monoxide

CO2 carbon dioxide

NMHC nonmethane hydrocarbon

NMHCE nonmethane hydrocarbon equivalent

NO nitric oxide

NO2 nitrogen dioxide

NOx oxides of nitrogen

N2O nitrous oxide

O2 molecular oxygen

PM particulate mass

THC total hydrocarbon

THCE total hydrocarbon equivalent

(c) Superscripts. This part uses the following superscripts to define a quantity:

Superscript Quantity

overbar (such as y ) arithmetic mean
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(d) Subscripts. This part uses the following subscripts to define a quantity:

Subscript Quantity

int speed interval

abs absolute quantity

act actual or measured condition

actint actual or measured condition over the speed interval

atmos atmospheric

b base

c coastdown

e effective

error error

exp expected quantity

i an individual of a series

final final

init initial quantity, typically before an emission test

max

the maximum (i.e., peak) value expected at the standard over a 

test interval; not the maximum of an instrument range

meas measured quantity

ref reference quantity
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rev revolution

roll dynamometer roll

s settling

sat saturated condition

si speed interval

span span quantity

test test quantity

uncor uncorrected quantity

zero zero quantity

(e) Other acronyms and abbreviations. This part uses the following additional 

abbreviations and acronyms: 

CFR Code of Federal Regulations

EPA Environmental Protection Agency

FID flame-ionization detector

GVWR gross vehicle weight rating

NIST National Institute for Standards and Technology

RESS rechargeable energy storage system

SAE Society of Automotive Engineers
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U.S.C. United States Code

§1066.710 Reference materials.

(a) Certain material is incorporated by reference into this part with the approval of the 

Director of the Federal Register under 5 U.S.C. 552(a) and 1 CFR part 51. To enforce any 

edition other than that specified in this section, the Environmental Protection Agency

must publish a notice of the change in the Federal Register and the material must be 

available to the public. All approved material is available for inspection at U.S. EPA, Air 

and Radiation Docket and Information Center, 1301 Constitution Ave., NW., Room 

B102, EPA West Building, Washington, DC 20460, (202) 202-1744, and is available 

from the sources listed below. It is also available for inspection at the National Archives 

and Records Administration (NARA). For information on the availability of this material 

at NARA, call 202–741–6030, or go to 

http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.

(b) Society of Automotive Engineers, 400 Commonwealth Dr., Warrendale, PA 15096–

0001, (877) 606–7323 (U.S. and Canada) or (724) 776–4970 (outside the U.S. and 

Canada), http://www.sae.org. 

(1) SAE J1263, Road Load Measurement and Dynamometer Simulation Using 

Coastdown Techniques, Revised March 2010, IBR approved for §§ 1066.301(b) and 

1066.310(b). 

(2) SAE J2263, Road Load Measurement Using On-Board Anemometry and 

Coastdown Techniques, Revised December 2008, IBR approved for §§ 1066.301(b), 

and 1066.310(b).

(3) SAE J2711, Recommended Practice for Measuring Fuel Economy and Emissions 

of Hybrid-Electric and Conventional Heavy-Duty Vehicles, Issued September 2002, 

IBR approved for § 1066.501.

(c) National Institute of Standards and Technology, 100 Bureau Drive, Stop 1070, 

Gaithersburg, MD 20899-1070, (301) 975-6478, www.nist.gov, or inquiries@nist.gov.

(1) NIST Special Publication 811, 2008 Edition, Guide for the Use of the 

International System of Units (SI), Barry N. Taylor, Physics Laboratory, and Ambler 

Thompson, Technology Services, March 2008, IBR approved for §§ 1066.20(a) and 

1066.705.

(2) [Reserved]
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PART 1068—GENERAL COMPLIANCE PROVISIONS FOR HIGHWAY, 

STATIONARY, AND NONROAD PROGRAMS

92. The authority citation for part 1068 continues to read as follows:

Authority: 42 U.S.C. 7401-7671q.

93. The heading of part 1068 is revised to read as set forth above.

Subpart A – [Amended]

94. Section 1068.1 is revised to read as follows:

§ 1068.1 Does this part apply to me?

(a) The provisions of this part apply to everyone with respect to the following engines 

and to equipment using the following engines (including owners, operators, parts 

manufacturers, and persons performing maintenance):

(1) Locomotives we regulate under 40 CFR part 1033.

(2) Heavy-duty motor vehicles and motor vehicle engines to the extent and in the 

manner specified in 40 CFR parts 85, 86, 1036 and 1037.

(3) Land-based nonroad compression-ignition engines we regulate under 40 CFR part 

1039.

(4) Stationary compression-ignition engines certified using the provisions of 40 CFR 

part 1039, as indicated in 40 CFR part 60, subpart IIII.

(5) Marine compression-ignition engines we regulate under 40 CFR part 1042.

(6) Marine spark-ignition engines we regulate under 40 CFR part 1045.

(7) Large nonroad spark-ignition engines we regulate under 40 CFR part 1048.

(8) Stationary spark-ignition engines certified using the provisions of 40 CFR parts 

1048 or 1054, as indicated in 40 CFR part 60, subpart JJJJ.

(9) Recreational engines and vehicles we regulate under 40 CFR part 1051 (such as 

snowmobiles and off-highway motorcycles).
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(10) Small nonroad spark-ignition engines we regulate under 40 CFR part 1054.

(b) This part does not apply to any of the following engine or vehicle categories, except 

as specified in paragraph (d) of this section or as specified in other parts:

(1) Light-duty motor vehicles (see 40 CFR part 86).

(2) Highway motorcycles (see 40 CFR part 86).

(3) Aircraft engines (see 40 CFR part 87).

(4) Land-based nonroad compression-ignition engines we regulate under 40 CFR part 

89.

(5) Small nonroad spark-ignition engines we regulate under 40 CFR part 90.

(c) Paragraph (a) of this section identifies the parts of the CFR that define emission 

standards and other requirements for particular types of engines and equipment. This part 

1068 refers to each of these other parts generically as the “standard-setting part.” For 

example, 40 CFR part 1051 is always the standard-setting part for snowmobiles. Follow 

the provisions of the standard-setting part if they are different than any of the provisions 

in this part.

(d) Specific provisions in this part 1068 start to apply separate from the schedule for 

certifying engines to new emission standards, as follows:

(1) The provisions of §§ 1068.30 and 1068.310 apply for stationary spark-ignition 

engines built on or after January 1, 2004, and for stationary compression-ignition 

engines built on or after January 1, 2006.

(2) The provisions of §§ 1068.30 and 1068.235 apply for the types of 

engines/equipment listed in paragraph (a) of this section beginning January 1, 2004, if 

they are used solely for competition.

Subpart C – [Amended]

95. Section 1068.210 is revised to read as follows:

§1068.210 What are the provisions for exempting test engines/equipment?

(a) We may exempt engines/equipment that you will use for research, investigations, 

studies, demonstrations, or training. Note that you are not required to get an exemption 

under this section for engines that are exempted under other provisions of this part, such 

as the manufacturer-owned exemption in §1068.215.
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(b) Anyone may ask for a testing exemption. 

(c) If you are a certificate holder, you may request an exemption for engines/equipment 

you intend to include in test programs over a two-year period. 

(1) In your request, tell us the maximum number of engines/equipment involved and 

describe how you will make sure exempted engines/equipment are used only for this 

testing. For example, if the exemption will involve other companies using your 

engines/equipment, describe your plans to track individual units so you can properly 

report on their final disposition. 

(2) Give us the information described in paragraph (d) of this section if we ask for it.

(d) If you are not a certificate holder, do all the following things: 

(1) Show that the proposed test program has a valid purpose under paragraph (a) of 

this section.

(2) Show you need an exemption to achieve the purpose of the test program (time 

constraints may be a basis for needing an exemption, but the cost of certification 

alone is not).

(3) Estimate the duration of the proposed test program and the number of 

engines/equipment involved.

(4) Allow us to monitor the testing.

(5) Describe how you will ensure that you stay within this exemption’s purposes. 

Address at least the following things:

(i) The technical nature of the test.

(ii) The test site.

(iii) The duration and accumulated engine/equipment operation associated with 

the test.

(iv) Ownership and control of the engines/equipment involved in the test.

(v) The intended final disposition of the engines/equipment.

(vi) How you will identify, record, and make available the engine/equipment 

identification numbers.

(vii) The means or procedure for recording test results.

(e) If we approve your request for a testing exemption, we will send you a letter or a 

memorandum describing the basis and scope of the exemption. It will also include any 

necessary terms and conditions, which normally require you to do the following:
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(1) Stay within the scope of the exemption.

(2) Create and maintain adequate records that we may inspect.

(3) Add a permanent label to all engines/equipment exempted under this section, 

consistent with §1068.45, with at least the following items: 

(i) The label heading "EMISSION CONTROL INFORMATION".

(ii) Your corporate name and trademark.

(iii) Engine displacement, family identification, and model year of the 

engine/equipment (as applicable), or whom to contact for further information.

(iv) One of these statements (as applicable):

(A) “THIS ENGINE IS EXEMPT UNDER 40 CFR 1068.210 OR 1068.215 

FROM EMISSION STANDARDS AND RELATED REQUIREMENTS.” 

(B) “THIS EQUIPMENT IS EXEMPT UNDER 40 CFR 1068.210 OR 

1068.215 FROM EMISSION STANDARDS AND RELATED 

REQUIREMENTS.”

(4) Tell us when the test program is finished.

(5) Tell us the final disposition of the engines/equipment.

(6) Send us a written confirmation that you meet the terms and conditions of this 

exemption.

96. Section 1068.235 is revised to read as follows:

§ 1068.235 What are the provisions for exempting engines/equipment used solely 

for competition?

(a) New engines/equipment you produce that are used solely for competition are 

generally excluded from emission standards. See the standard-setting parts for specific 

provisions where applicable.

(b) If you modify any nonroad engines/equipment after they have been placed into 

service in the United States so they will be used solely for competition, they are exempt 

without request. This exemption applies only to the prohibition in §1068.101(b)(1) and is 

valid only as long as the engine/equipment is used solely for competition. You may not 

use the provisions of this paragraph (b) to circumvent the requirements that apply to the 

sale of new competition engines under the standard-setting part.
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(c) If you modify any nonroad engines/equipment under paragraph (b) of this section, you 

must destroy the original emission labels. If you loan, lease, sell, or give any of these 

engines/equipment to someone else, you must tell the new owner (or operator, if 

applicable) in writing that they may be used only for competition.

Subpart D – [Amended]

97. Section 1068.325 is revised to read as follows:

§1068.325 What are the temporary exemptions for imported engines/equipment?

You may import engines/equipment under certain temporary exemptions, subject to the 

conditions in this section. We may ask U.S. Customs and Border Protection to require a 

specific bond amount to make sure you comply with the requirements of this subpart. 

You may not sell or lease one of these engines/equipment while it is in the United States 

except as specified in this section or §1068.201(i). You must eventually export the 

engine/equipment as we describe in this section unless it conforms to a certificate of 

conformity or it qualifies for one of the permanent exemptions in §1068.315. 

(a) Exemption for repairs or alterations. You may temporarily import nonconforming 

engines/equipment under bond solely for repair or alteration, subject to our advance 

approval as described in paragraph (j) of this section. You may operate the 

engine/equipment in the United States only as necessary to repair it, alter it, or ship it to 

or from the service location. Export the engine/equipment directly after servicing is

complete.

(b) Testing exemption. You may temporarily import nonconforming engines/equipment 

under bond for testing if you follow the requirements of §1068.210, subject to our 

advance approval as described in paragraph (j) of this section. You may operate the 

engines/equipment in the United States only as needed to perform tests. This exemption 

expires one year after you import the engine/equipment unless we approve an extension. 

The engine/equipment must be exported before the exemption expires. You may sell or 

lease the engines/equipment consistent with the provisions of §1068.210.

(c) Display exemption. You may temporarily import nonconforming engines/equipment 

under bond for display if you follow the requirements of§1068.220, subject to our 

advance approval as described in paragraph (j) of this section. This exemption expires 

one year after you import the engine/equipment, unless we approve your request for an 

extension. We may approve an extension of up to one more year for each request, but no 

more than three years total. The engine/equipment must be exported by the time the 

exemption expires or directly after the display concludes, whichever comes first. 

(d) Export exemption. You may temporarily import nonconforming engines/equipment 

to export them, as described in §1068.230. You may operate the engine/equipment in the 
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United States only as needed to prepare it for export. Label the engine/equipment as 

described in §1068.230. You may sell or lease the engines/equipment for operation 

outside the United States consistent with the provisions of §1068.230.

(e) Diplomatic or military exemption. You may temporarily import nonconforming 

engines/equipment without bond if you represent a foreign government in a diplomatic or 

military capacity. In your request to the Designated Compliance Officer (see §1068.305), 

include either written confirmation from the U.S. State Department that you qualify for 

this exemption or a copy of your orders for military duty in the United States. We will 

rely on the State Department or your military orders to determine when your diplomatic 

or military status expires, at which time you must export your exempt engines/equipment.

(f) Delegated-assembly exemption. You may import a nonconforming engine for final 

assembly under the provisions of §1068.261. You may sell or lease the 

engines/equipment consistent with the provisions of §1068.261.

(g) Exemption for partially complete engines. You may import an engine if another 

company already has a certificate of conformity and will be modifying the engine to be in 

its final certified configuration or a final exempt configuration under the provisions of 

§1068.262. You may also import a partially complete engine by shipping it from one of 

your facilities to another under the provisions of §1068.260(c). If you are importing a 

used engine that becomes new as a result of importation, you must meet all the 

requirements that apply to original engine manufacturers under §1068.262. You may sell 

or lease the engines consistent with the provisions of §1068.262.

(h) [Reserved]

(i) [Reserved]

(j) Approvals. For the exemptions in this section requiring our approval, you must send a 

request to the Designated Compliance Officer before importing the engines/equipment. 

We will approve your request if you meet all the applicable requirements and conditions. 

If another section separately requires that you request approval for the exemption, you 

may combine the information requirements in a single request. Include the following 

information in your request:

(1) Identify the importer of the engine/equipment and the applicable postal address, email address, and telephone number.

(2) Identify the engine/equipment owner and the applicable postal address, e-mail 

address, and telephone number.

(3) Identify the engine/equipment by model number (or name), serial number, and 

original production year.

(4) Identify the specific regulatory provision under which you are seeking an 

exemption.
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(5) Authorize EPA enforcement officers to conduct inspections or testing as allowed 

under the Clean Air Act.

(6) Include any additional information we specify for demonstrating that you qualify

for the exemption. 

Department of Transportation 

National Highway Traffic Safety Administration

49 CFR Chapter V

In consideration of the foregoing, under the authority of 49 U.S.C. 32901 and 32902 and 

delegation of authority at 49 CFR 1.50, NHTSA proposes to amend 49 CFR chapter V as 

follows:

PART 523 — VEHICLE CLASSIFICATION

98. The authority for part 523 continues to read as follows:

Authority: 49 U.S.C. 32901; delegation of authority at 49 CFR 1.50.

99. Revise § 523.2 to read as follows:

§ 523.2 Definitions.

Approach angle means the smallest angle, in a plane side view of an automobile, formed 

by the level surface on which the automobile is standing and a line tangent to the front 

tire static loaded radius arc and touching the underside of the automobile forward of the 

front tire. 

Axle clearance means the vertical distance from the level surface on which an automobile 

is standing to the lowest point on the axle differential of the automobile.

Base tire means the tire specified as standard equipment by a manufacturer on each 

subconfiguration of a model type.

Basic vehicle frontal area is used as defined in 40 CFR 86.1803-01.

Breakover angle means the supplement of the largest angle, in the plan side view of an 

automobile that can be formed by two lines tangent to the front and rear static loaded 

radii arcs and intersecting at a point on the underside of the automobile.

Cab-complete vehicle means a vehicle that is first sold as an incomplete vehicle that 

substantially includes the vehicle cab section as defined in 40 CFR 1037.801. For 

example, vehicles known commercially as chassis-cabs, cab-chassis, box-deletes, beddeletes, cut-away vans are considered cab-complete vehicles. A cab includes a steering 
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column and passenger compartment. Note a vehicle lacking some components of the cab 

is a cab-complete vehicle if it substantially includes the cab. 

Cargo-carrying volume means the luggage capacity or cargo volume index, as 

appropriate, and as those terms are defined in 40 CFR 600.315, in the case of automobiles 

to which either of those terms apply. With respect to automobiles to which neither of 

those terms apply “cargo-carrying volume” means the total volume in cubic feet rounded 

to the nearest 0.1 cubic feet of either an automobile's enclosed nonseating space that is 

intended primarily for carrying cargo and is not accessible from the passenger 

compartment, or the space intended primarily for carrying cargo bounded in the front by 

a vertical plane that is perpendicular to the longitudinal centerline of the automobile and 

passes through the rearmost point on the rearmost seat and elsewhere by the automobile's 

interior surfaces.

Class 2b vehicles are vehicles with a gross vehicle weight rating (GVWR) ranging from 

8,501 to 10,000 pounds.

Class 3 through Class 8 vehicles are vehicles with a gross vehicle weight rating (GVWR) 

of 10,001 pounds or more as defined in 49 CFR 565.15.

Commercial medium- and heavy-duty on-highway vehicle means an on-highway vehicle 

with a gross vehicle weight rating of 10,000 pounds or more as defined in 49 U.S.C. 

32901(a)(7). 

Complete vehicle means a vehicle that requires no further manufacturing operations to 

perform its intended function and is a functioning vehicle that has the primary load 

carrying device or container (or equivalent equipment) attached or that is designed to pull 

a trailer. Examples of equivalent equipment would include fifth wheel trailer hitches, 

firefighting equipment, and utility booms.

Curb weight is defined the same as vehicle curb weight in 40 CFR 86.1803-01.

Departure angle means the smallest angle, in a plane side view of an automobile, formed 

by the level surface on which the automobile is standing and a line tangent to the rear tire 

static loaded radius arc and touching the underside of the automobile rearward of the rear 

tire.

Final stage manufacturer has the meaning given in 49 CFR 567.3.

Footprint is defined as the product of track width (measured in inches, calculated as the 

average of front and rear track widths, and rounded to the nearest tenth of an inch) times 

wheelbase (measured in inches and rounded to the nearest tenth of an inch), divided by

144 and then rounded to the nearest tenth of a square foot. For purposes of this definition, 

track width is the lateral distance between the centerlines of the base tires at ground, 

including the camber angle. For purposes of this definition, wheelbase is the longitudinal 

distance between front and rear wheel centerlines.
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Gross combination weight rating or GCWR means the value specified by the 

manufacturer as the maximum allowable loaded weight of a combination vehicle (e.g. 

tractor plus trailer).

Gross vehicle weight rating or GVWR means the value specified by the vehicle 

manufacturer as the maximum design loaded weight of a single vehicle (e.g. vocational 

vehicle). 

Heavy-duty engine means any engine used for (or for which the engine manufacturer 

could reasonably expect to be used for) motive power in a heavy-duty vehicle. For 

purposes of this definition in this part, the term “engine” includes internal combustion 

engines and other devices that convert chemical fuel into motive power. For example, a 

fuel cell and motor used in a heavy-duty vehicle is a heavy-duty engine.

Heavy-duty vehicle means a vehicle that as defined in § 523.6.

Heavy-duty off-road vehicle means a heavy-duty vocational vehicle or vocational tractor 

that is intended for off-road use meeting either the criteria of paragraph (1) or (2). 

(1) Vehicles with tires installed having a maximum speed rating at or below 55 mph. 

(2) Vehicles primarily designed to perform work off-road (such as in oil fields, forests, or 

construction sites), and meeting at least one of the criteria of paragraph (2)(i) of this 

section and at least one of the criteria of paragraph (2)(ii) of this section. 

(i) Vehicle must have affixed components designed to work in an off-road environment 

(for example, hazardous material equipment or drilling equipment) or was designed to 

operate at low speeds making them unsuitable for normal highway operation.

(ii) Vehicles must:

(A) Have an axle that has a gross axle weight rating (GAWR) of 29,000 pounds or more;

(B) Have a speed attainable in 2 miles of not more than 33 mph; or 

(C) Have a speed attainable in 2 miles of not more than 45 mph, an unloaded vehicle 

weight that is not less than 95 percent of its gross vehicle weight rating (GVWR), and no 

capacity to carry occupants other than the driver and operating crew.

Incomplete vehicle means a vehicle which does not have the primary load carrying device 

or container attached when it is first sold as a vehicle or any vehicle that does not meet 

the definition of a complete vehicle. This may include vehicles sold to secondary vehicle 

manufacturers. Incomplete vehicles include cab-complete vehicles. 

Innovative technology means technology certified under 40 CFR part 1037.610.

Light truck means a non-passenger automobile meeting the criteria in § 523.5.
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Medium duty passenger vehicle means a vehicle which would satisfy the criteria in 

§ 523.5 (relating to light trucks) but for its gross vehicle weight rating or its curb weight, 

which is rated at more than 8,500 lbs GVWR or has a vehicle curb weight of more than 

6,000 pounds or has a basic vehicle frontal area in excess of 45 square feet, and which is 

designed primarily to transport passengers, but does not include a vehicle that:

(1) Is an “incomplete vehicle”' as defined in this subpart; or

(2) Has a seating capacity of more than 12 persons; or

(3) Is designed for more than 9 persons in seating rearward of the driver's seat; or

(4) Is equipped with an open cargo area (for example, a pick-up truck box or bed) of 72.0 

inches in interior length or more. A covered box not readily accessible from the 

passenger compartment will be considered an open cargo area for purposes of this 

definition.

Motor home has the meaning given in 49 CFR 571.3.

Motor vehicle has the meaning given in 40 CFR 85.1703.

Passenger-carrying volume means the sum of the front seat volume and, if any, rear seat 

volume, as defined in 40 CFR 600.315, in the case of automobiles to which that term 

applies. With respect to automobiles to which that term does not apply, ``passengercarrying volume'' means the sum in cubic feet, rounded to the nearest 0.1 cubic feet, of 

the volume of a vehicle's front seat and seats to the rear of the front seat, as applicable, 

calculated as follows with the head room, shoulder room, and leg room dimensions 

determined in accordance with the procedures outlined in Society of Automotive 

Engineers Recommended Practice J1100a, Motor Vehicle Dimensions (Report of Human 

Factors Engineering Committee, Society of Automotive Engineers, approved September 

1973 and last revised September 1975).

(1) For front seat volume, divide 1,728 into the product of the following SAE 

dimensions, measured in inches to the nearest 0.1 inches, and round the quotient to the 

nearest 0.001 cubic feet.

(i) H61-Effective head room--front.

(ii) W3-Shoulder room--front.

(iii) L34-Maximum effective leg room-accelerator.

(2) For the volume of seats to the rear of the front seat, divide 1,728 into the product of 

the following SAE dimensions, measured in inches to the nearest 0.1 inches, and rounded 

the quotient to the nearest 0.001 cubic feet.

(i) H63-Effective head room--second.
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(ii) W4-Shoulder room--second.

(iii) L51-Minimum effective leg room--second.

Pickup truck means a non-passenger automobile which has a passenger compartment and 

an open cargo area (bed). 

Recreational vehicle or RV means a motor vehicle equipped with living space and 

amenities found in a motor home.

Running clearance means the distance from the surface on which an automobile is 

standing to the lowest point on the automobile, excluding unsprung weight.

Static loaded radius arc means a portion of a circle whose center is the center of a 

standard tire-rim combination of an automobile and whose radius is the distance from 

that center to the level surface on which the automobile is standing, measured with the 

automobile at curb weight, the wheel parallel to the vehicle's longitudinal centerline, and 

the tire inflated to the manufacturer's recommended pressure.

Temporary living quarters means a space in the interior of an automobile in which people 

may temporarily live and which includes sleeping surfaces, such as beds, and household 

conveniences, such as a sink, stove, refrigerator, or toilet.

Van means a vehicle with a body that fully encloses the driver and a cargo carrying or 

work performing compartment. The distance from the leading edge of the windshield to 

the foremost body section of vans is typically shorter than that of pickup trucks and sport 

utility vehicles. 

Vocational vehicle means a vehicle that is equipped for a particular industry, trade or 

occupation such as construction, heavy hauling, mining, logging, oil fields, refuse and 

includes vehicles such as school buses, motorcoaches and RVs.

Vocational tractor means a tractor that is classified as a vocational vehicle according to 

40 CFR part 1037.630

Work truck means a vehicle that is rated at more than 8,500 pounds and less than or equal 

to 10,000 pounds gross vehicle weight, and is not a medium-duty passenger vehicle as 

defined in 40 CFR 86.1803-01 effective as of December 20, 2007.

100. Add a new § 523.6 to read as follows: 

§ 523.6 Heavy-duty vehicle.

(a) A heavy-duty vehicle is any commercial medium- and heavy-duty on highway vehicle 

or a work truck, as defined in 49 U.S.C. 32901(a)(7) and (19). For the purpose of this 
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regulation heavy-duty vehicles are divided into three regulatory categories as follows: 

(1) Heavy-duty pickup trucks and vans; 

(2) Heavy-duty vocational vehicles; and 

(3) Truck tractors with a GVWR above 26,000 pounds.

(b) The heavy-duty vehicle classification does not include:

(1) Vehicles defined as medium duty passenger vehicles.

(2) Vehicles excluded from the definition of “heavy-duty vehicle” because of vehicle 

weight or weight rating (such as light duty vehicles as defined in § 523.5).

(3) Vehicles excluded from the definition of motor vehicle in 40 CFR part 85.1703.

101. Add a new § 523.7 to read as follows: 

§ 523.7 Heavy-duty pickup trucks and vans.

Heavy-duty pickup trucks and vans are pickup trucks and vans with a gross vehicle 

weight rating between 8,501 pounds and 14,000 pounds (Class 2b through 3 vehicles) 

manufactured as complete vehicles by a single or final stage manufacturer or 

manufactured as incomplete vehicles as designated by a manufacturer. A manufacturer 

may also optionally designate incomplete or complete Class 4 or 5 vehicles as heavy-duty 

pickup trucks or vans or spark ignition (or gasoline) engines certified and sold as loose 

engines manufactured for use in heavy-duty pickup trucks or vans. See references in 40 

CFR part 1037.104 and 40 CFR part 1037.150. 

102. Add a new § 523.8 to read as follows: 

§ 523.8 Heavy-duty vocational vehicle.

Heavy-duty vocational vehicles are vehicles with a gross vehicle weight rating (GVWR) 

above 8,500 pounds excluding:
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(a) Heavy-duty pickup trucks and vans defined in § 523.7;

(b) Medium duty passenger vehicles; and 

(c) Truck tractors, except vocational tractors, with a GVWR above 26,000 pounds; 

103. Add a new § 523.9 to read as follows: 

§ 523.9 Truck tractors.

Truck tractors for the purpose of this part are considered as any truck tractor as defined in 

49 CFR part 571 having a GVWR above 26,000 pounds. 

PART 534—RIGHTS AND RESPONSIBILITIES OF MANUFACTURERS IN 

THE CONTEXT OF CHANGES IN CORPORATE RELATIONSHIPS

104. The authority for part 534 continues to read as follows:

Authority: 49 U.S.C. 32901; delegation of authority at 49 CFR 1.50.

105. Revise § 534.1 to read as follows:

§ 534.1 Scope.

This part defines the rights and responsibilities of manufacturers in the context of 

changes in corporate relationships for purposes of the fuel economy and fuel 

consumption programs established by 49 U.S.C. chapter 329. 

106. Revise § 534.2 to read as follows:

§ 534.2 Applicability.

This part applies to manufacturers of passenger automobiles, light trucks, heavy-duty 

vehicles and the engines manufactured for use in heavy-duty vehicles as defined in 49 

CFR part 523.
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107. Revise § 534.4 to read as follows.

§ 534.4 Successors and predecessors.

For purposes of the fuel economy and fuel consumption programs, ‘‘manufacturer’’ 

includes ‘‘predecessors’’ and ‘‘successors’’ to the extent specified in paragraphs (a) 

through (d) of this section.

(a) Successors are responsible for any civil penalties that arise out of fuel economy and 

fuel consumption shortfalls incurred and not satisfied by predecessors.

(b) If one manufacturer has become the successor of another manufacturer during a 

model year, all of the vehicles or engines produced by those manufacturers during the 

model year are treated as though they were manufactured by the same manufacturer. A 

manufacturer is considered to have become the successor of another manufacturer during 

a model year if it is the successor on September 30 of the corresponding calendar year 

and was not the successor for the preceding model year.

(c)(1) For passenger automobiles and light trucks, fuel economy credits earned by a 

predecessor before or during model year 2007 may be used by a successor, subject to the 

availability of credits and the general three-year restriction on carrying credits forward 

and the general three-year restriction on carrying credits backward. Fuel economy credits 

earned by a predecessor after model year 2007 may be used by a successor, subject to the 

availability of credits and the general five-year restriction on carrying credits forward and 

the general three-year restriction on carrying credits backward. 

(2) For heavy-duty vehicles and heavy-duty vehicle engines, available fuel consumption 

credits earned by a predecessor after model year 2015, and in model years 2013, 2014 

and 2015 if a manufacturer voluntarily complies in those model years, may be used by a 

successor, subject to the availability of credits and the general five-year restriction on 

carrying credits forward and the general three year restriction on carrying credits 

backward.

(d)(1) For passenger automobiles and light trucks, fuel economy credits earned by a 

successor before or during model year 2007 may be used to offset a predecessor’s 

shortfall, subject to the availability of credits and the general three-year restriction on 

carrying credits forward and the general three-year restriction on carrying credits 

backward. Credits earned by a successor after model year 2007 may be used to offset a 

predecessor’s shortfall, subject to the availability of credits and the general five-year 

restriction on carrying credits forward and the general three-year restriction on carrying 

credits backward. 

(2) For heavy-duty vehicles and heavy-duty vehicle engines, available credits earned by a 

successor after model year 2015, and in model years 2013, 2014 and 2015, if a 

manufacturer voluntarily complies in those model years, may be used by a predecessor 

subject to the availability of credits and the general five-year restriction on carrying 

credits forward and the general three year restriction on carrying credits backward. 
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108. Amend § 534.5 by revising paragraphs (a), (c), and (d) to read as follows:

§ 534.5 Manufacturers within control relationships.

(a) If a civil penalty arises out of a fuel economy or fuel consumption shortfall incurred 

by a group of manufacturers within a control relationship, each manufacturer within that 

group is jointly and severally liable for the civil penalty.

* * * * *

(c)(1) For passenger automobiles and light trucks, fuel economy credits of a manufacturer 

within a control relationship may be used by the group of manufacturers within the 

control relationship to offset shortfalls, subject to the agreement of the other 

manufacturers, the availability of the credits, and the general three year restriction on 

carrying credits forward or backward prior to or during model year 2007, or the general 

five year restriction on carrying credits forward and the general three-year restriction on 

carrying credits backward after model year 2007. 

(2) For heavy-duty vehicles and heavy-duty engines, credits of a manufacturer within a 

control relationship may be used by the group of manufacturers within the control 

relationship to offset shortfalls, subject to the agreement of the other manufacturers, the 

availability of the credits, the general 5-year restriction on carrying credits forward, and 

the general three year restriction on offsetting past credit shortfalls as specified in the 

requirements of 49 CFR 535.7.

(d)(1) For passenger automobiles and light trucks, if a manufacturer within a group of 

manufacturers is sold or otherwise spun off so that it is no longer within that control 

relationship, the manufacturer may use credits that were earned by the group of 

manufacturers within the control relationship while the manufacturer was within that 

relationship, subject to the agreement of the other manufacturers, the availability of the 

credits, and the general three-year restriction on carrying credits forward or backward 

prior to or during model year 2007, or the general five-year restriction on carrying credits 

forward and the general three-year restriction on carrying credits backward after model 

year 2007. 

(2) For heavy-duty vehicles and heavy-duty vehicle engines, if a manufacturer within a 

group of manufacturers is sold or otherwise spun off so that it is no longer within that 

control relationship, the manufacturer may use credits that were earned by the group of 

manufacturers within the control relationship while the manufacturer was within that 

relationship, subject to the agreement of the other manufacturers, the availability of the 

credits, the general 5-year restriction on carrying credits forward, and the general three 

year restriction on offsetting past credit shortfalls as specified in the requirements of 49 

CFR 535.7.

* * * * *
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109. Revise § 534.6 to read as follows.

§ 534.6 Reporting corporate transactions.

Manufacturers who have entered into written contracts transferring rights and 

responsibilities such that a different manufacturer owns the controlling stock or exerts 

control over the design, production or sale of automobiles or heavy-duty vehicles to 

which Corporate Average Fuel Economy or Fuel Consumption standards apply shall 

report the contract to the agency as follows:

(a) The manufacturers must file a certified report with the agency affirmatively stating 

that the contract transfers rights and responsibilities between them such that one 

manufacturer has assumed a controlling stock ownership or control over the design, 

production or sale of vehicles. The report must also specify the first full model year to 

which the transaction will apply.

(b) Each report shall—

(1) Identify each manufacturer;

(2) State the full name, title, and address of the official responsible for preparing the 

report;

(3) Identify the production year being reported on;

(4) Be written in the English language; and

(5) Be submitted to: Administrator, National Highway Traffic Safety Administration, 

1200 New Jersey Avenue, SE, Washington, DC 20590.

(c) The manufacturers may seek confidential treatment for information provided in the 

certified report in accordance with 49 CFR part 512.

110. A new part 535 is added to chapter V to read as follows: 

PART 535 MEDIUM- AND HEAVY-DUTY VEHICLE FUEL EFFICIENCY 

PROGRAM

Sec.

535.1 Scope.

535.2 Purpose.

535.3 Applicability.

535.4 Definitions.

535.5 Standards.
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535.6 Measurement and calculation procedures.

535.7 Averaging, banking, and trading (ABT) program.

535.8 Reporting requirements. 

535.9 Enforcement approach.

Authority: 49 U.S.C. 32902; delegation of authority at 49 CFR 1.50.

§ 535.1 Scope.

This part establishes fuel consumption standards pursuant to 49 U.S.C. 32902(k) for work 

trucks and commercial medium-duty and heavy-duty on-highway vehicles (hereafter 

referenced as heavy-duty vehicles) and engines manufactured for sale in the United States 

and establishes a credit program manufacturers may use to comply with standards and 

requirements for manufacturers to provide reports to the National Highway Traffic Safety 

Administration regarding their efforts to reduce the fuel consumption of these vehicles.

§ 535.2 Purpose.

The purpose of this part is to reduce the fuel consumption of new heavy-duty vehicles by 

establishing maximum levels for fuel consumption standards while providing a flexible 

credit program to assist manufacturers in complying with standards.

§ 535.3 Applicability.

(a) This part applies to complete vehicle and chassis manufacturers of all new heavy-duty 

vehicles, as defined in 49 CFR part 523, and to the manufacturers of all heavy-duty 

engines manufactured for use in the applicable vehicles for each given model year. 

(b) Complete vehicle manufacturers, for the purpose of this part, include manufacturers 

that produce heavy-duty pickup trucks and vans or truck tractors as complete vehicles 

and that hold the EPA certificate of conformity. 

(c) Chassis manufacturers, for the purpose of this part, include manufacturers that 

produce incomplete vehicles constructed for use as heavy-duty pickup trucks or vans or 

heavy-duty vocational vehicles and that hold the EPA certificate of conformity. Some 

vocational vehicle manufacturers are both chassis and complete vehicle manufacturers. 

These manufacturers will be regulated as chassis manufacturers under this program. 

(d) Engine manufacturer, for the purpose of this part, means a manufacturer that 

manufacturers engines for heavy-duty vehicles and holds the EPA certificate of 

conformity.

(e) The heavy-duty vehicles, chassis and engines excluded from the requirements of this 

part include:

(1) Recreational vehicles, including motor homes.

(2) Vehicles and engines exempted by EPA in accordance with 40 CFR part 1036 and 40 

CFR 1037. 

(f) Vehicles and engines produced by small business manufacturers as defined by the 

Small Business Administration at 13 CFR 121.201 are exempted as specified in § 

535.8(h). 
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(g) Heavy-duty off-road vehicles meeting the criteria in 49 CFR part 523 are exempt 

without request from vehicle standards of § 535.5(b). Manufacturers of vehicles not 

meeting the criteria for the heavy-duty off-road vehicle exclusion may submit a petition 

as specified in § 535.8(h) to EPA and NHTSA for an exclusion from the vehicle 

standards of § 535.5(b).

(h) A vehicle manufacturer that completes assembly of a vehicle at two or more facilities 

may ask to use as the date of manufacture for that vehicle the date on which 

manufacturing is completed at the place of main assembly, consistent with provisions of 

49 CFR 567.4, as the model year. Note that such staged assembly is subject to the 

provisions of 40 CFR 1068.260(c). NHTSA’s allowance of this provision is effective 

when EPA approves the manufacturer’s certificates of conformity for these vehicles. 

§ 535.4 Definitions.

The terms manufacture and manufacturer are used as defined in section 501 of the Act 

and the terms commercial medium-duty and heavy-duty on highway vehicle, fuel and 

work truck are used as defined in 49 U.S.C. 32901.

A to B testing means testing performed in pairs to allow comparison of vehicle A to 

vehicle B.

Act means the Motor Vehicle Information and Cost Savings Act, as amended by Pub. L. 

94–163 and 96–425.

Administrator means the Administrator of the National Highway Traffic Safety

Administration (NHTSA) or the Administrator's delegate.

Advanced technology means vehicle technology certified under 40 CFR part 1036.615 

and 40 CFR part 1037.615.

Averaging set means, a set of engines or vehicles in which fuel consumption credits may

be exchanged. Credits generated by one engine or vehicle family may only be used by 

other respective engine or vehicle families in the same averaging set. Note that an 

averaging set may comprise more than one regulatory subcategory. The averaging sets 

for this HD program are defined as follows:

(1) Heavy-duty pickup trucks and vans.

(2) Vocational light-heavy vehicles at or below 19,500 pounds GVWR. 

(3) Vocational and tractor medium-heavy vehicles above 19,500 pounds GVWR but at 

or below 33,000 pounds GVWR.

(4) Vocational and tractor heavy-heavy vehicles above 33,000 pounds GVWR.

(5) Compression-ignition light heavy-duty engines for Class 2b to 5 vehicles with a 

GVWR above 8,500 pounds but at or below 19,500 pounds.
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(6) Compression-ignition medium heavy-duty engines for Class 6 and 7 vehicles with a 

GVWR above 19,500 but at or below 33,000 pounds.

(7) Compression-ignition heavy heavy-duty engines for Class 8 vehicles with a GVWR 

above 33,000 pounds.

(8) Spark ignition engines in Class 2b to 8 vehicles with a GVWR above 8,500 pounds. 

Cab-complete vehicle has the meaning given in 49 CFR part 523.

Carryover means relating to certification based on emission data generated from an 

earlier model year. 

Certification means process of obtaining a certificate of conformity for a vehicle family 

that complies with the emission standards and requirements in this part. 

Certificate of Conformity means an approval document granted by the EPA to a 

manufacturer that submits an application for a vehicle or engine emissions family in 40 

CFR part 1036.205 and 40 CFR part 1037.205. A certificate of conformity is valid from 

the indicated effective date until December 31 of the model year for which it is issued. 

The certificate must be renewed annually for any vehicle a manufacturer continues to 

produce.

Certified emission level means the highest deteriorated emission level in an engine family 

for a given pollutant from the applicable transient and/or steady-state testing rounded to 

the same number of decimal places as the applicable standard. Note that you may have 

two certified emission levels for CO2 if you certify a family for both vocational and 

tractor use.

Certificate holder means the manufacturer who holds the certificate of conformity for the 

vehicle or engine and that assigns the model year based on the date when its 

manufacturing operations are completed relative to its annual model year period.

Chassis-cab means the incomplete part of a vehicle that includes a frame, a completed 

occupant compartment and that requires only the addition of cargo-carrying, workperforming, or load-bearing components to perform its intended functions.

Chief Counsel means the NHTSA Chief Counsel, or his or her designee.

Complete sister vehicle is a complete vehicle of the same configuration as a cab-complete 

vehicle.

Complete vehicle has the meaning given in 49 CFR part 523. 

Compression-ignition means relating to a type of reciprocating, internal-combustion 

engine, such as a diesel engine, that is not a spark-ignition engine.
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Configuration means a subclassification within a test group which is based on engine 

code, transmission type and gear ratios, final drive ratio, and other parameters which the 

EPA designates. 

Credits (or fuel consumption credits) in this part means an earned allowance recognizing 

the fuel consumption of a particular manufacturer’s vehicles or engines within a 

particular averaging set exceeds (credit surplus or positive credits) or falls below (credit 

shortfall, deficit or negative credits) that manufacturer’s fuel consumption standard(s) for 

the regulatory subcategory(s) that make-up the averaging set for a given model year, or 

purchased allowance. The value of an earned credit is calculated according to § 535.7. 

Curb weight has the meaning given in 40 CFR 86.1803-01. 

Date of manufacture means the date on which the certifying vehicle manufacturer 

completes its manufacturing operations, except as follows:

(1) Where the certificate holder is an engine manufacturer that does not manufacture the 

chassis, the date of manufacture of the vehicle is based on the date assembly of the 

vehicle is completed.

(2) EPA and NHTSA may approve an alternate date of manufacture based on the date on 

which the certifying (or primary) vehicle manufacturer completes assembly at the place 

of main assembly, consistent with the provisions of §1037.601 and 49 CFR 567.4.

Day cab means a type of truck tractor cab that is not a “sleeper cab”, as defined in this 

section. 

Dedicated vehicle has the same meaning as dedicated automobile as defined in 49 U.S.C. 

32901(a)(8). A dedicated automobile means an automobile that operates only on 

alternative fuels like E85 or natural gas, etc.

Dual fueled (multi-fuel or flexible-fuel vehicle) has the same meaning as dual fueled 

automobile as defined in 49 U.S.C. 32901(a)(9). For example, a vehicle that operates on 

gasoline and E85 or a plug-in hybrid electric vehicle is considered a dual fueled vehicle.

Electric vehicle means a vehicle that does not include an engine, and is powered solely by 

an external source of electricity and/or solar power. Note that this does not include 

electric hybrid or fuel-cell vehicles that use a chemical fuel such as gasoline, diesel fuel, 

or hydrogen. Electric vehicles may also be referred to as all-electric vehicles to 

distinguish them from hybrid vehicles.

Engine family has the meaning given in 40 CFR 1036.230.

Family certification level (FCL) means the family certification limit for an engine family 

as defined in 40 CFR 1036.801. 

Family emission limit (FEL) means the family emission limit for a vehicle family as 

defined in 40 CFR 1037.801. 
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Fuel cell electric vehicle means a motor vehicle propelled solely by an electric motor 

where energy for the motor is supplied by a fuel cell.

Fuel cell means an electrochemical cell that produces electricity via the non-combustion 

reaction of a consumable fuel, typically hydrogen.

Final-stage manufacturer has the meaning given in 49 CFR part 567.3. 

Fleet in this part means all the heavy-duty vehicles or engines within each of the 

regulatory sub-categories that are manufactured by a manufacturer in a particular model 

year and that are subject to fuel consumption standards under § 535.5. 

Fleet average fuel consumption is the calculated average fuel consumption performance 

value for a manufacturer’s fleet derived from the production weighted fuel consumption 

values of the unique vehicle configurations within each vehicle model type that makes up 

that manufacturer’s vehicle fleet in a given model year. In this part, the fleet average fuel 

consumption value is determined for each manufacturer’s fleet of heavy-duty pickup 

trucks and vans. 

Fleet average fuel consumption standard is the actual average fuel consumption standard 

for a manufacturer’s fleet derived from the production weighted fuel consumption 

standards of each unique vehicle configuration, based on payload, tow capacity and drive 

configuration (2, 4 or all-wheel drive), of the model types that makes up that 

manufacturer’s vehicle fleet in a given model year. In this part, the fleet average fuel 

consumption standard is determined for each manufacturer’s fleet of heavy-duty pickup 

trucks and vans. 

Fuel efficiency means the amount of work performed for each gallon of fuel consumed.

Good engineering judgment has the meaning given in 40 CFR 1068.30. See 40 CFR 

1068.5 for the administrative process used to evaluate good engineering judgment.

Gross combination weight rating (GCWR) has the meaning given in 49 CFR part 523.

Gross vehicle weight rating (GVWR) has the meaning given in 49 CFR part 523.

Heavy-duty vehicle has the meaning given in 49 CFR part 523.

Hybrid engine or hybrid powertrain means an engine or powertrain that includes energy

storage features other than a conventional battery system or conventional flywheel. 

Supplemental electrical batteries and hydraulic accumulators are examples of hybrid 

energy storage systems Note that certain provisions in this part treat hybrid engines and 

powertrains intended for vehicles that include regenerative braking different than those 

intended for vehicles that do not include regenerative braking.

Hybrid vehicle means a vehicle that includes energy storage features (other than a 

conventional battery system or conventional flywheel) in addition to an internal 

combustion engine or other engine using consumable chemical fuel. Supplemental 
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electrical batteries and hydraulic accumulators are examples of hybrid energy storage 

systems Note that certain provisions in this part treat hybrid vehicles that include 

regenerative braking different than those that do not include regenerative braking.

Innovative technology means technology certified under 40 CFR part 1037.610.

Incomplete vehicle has the meaning given in 49 CFR 523. For the purpose of this 

regulation, a manufacturer may request EPA and NHTSA to allow the certification of a 

vehicle as an incomplete vehicle if it manufactures the engine and sells the unassembled 

chassis components, provided it does not produce and sell the body components 

necessary to complete the vehicle.

Liquefied petroleum gas (LPG) has the meaning given in 40 CFR 1036.801. 

Low rolling resistance tire means a tire on a vocational vehicle with a tire rolling 

resistance level (TRRL) of 7.7 kg/metric ton or lower, a steer tire on a tractor with a 

TRRL of 7.7 kg/metric ton or lower, or a drive tire on a tractor with a TRRL of 8.1 

kg/metric ton or lower. 

Model type has the meaning given in 40 CFR 600.002.

Model year as it applies to engines means the manufacturer’s annual new model 

production period, except as restricted under this definition. It must include January 1 of 

the calendar year for which the model year is named, may not begin before January 2 of 

the previous calendar year, and it must end by December 31 of the named calendar year. 

Manufacturers may not adjust model years to circumvent or delay compliance with 

standards. 

Model year as it applies to vehicles means the manufacturer’s annual new model 

production period, except as restricted under this definition and 40 CFR part 85, subpart 

X. It must include January 1 of the calendar year for which the model year is named, 

may not begin before January 2 of the previous calendar year, and it must end by

December 31 of the named calendar year. 

(1) The manufacturer who holds the certificate of conformity for the vehicle must assign 

the model year based on the date when its manufacturing operations are completed 

relative to its annual model year period. 

(2) Unless a vehicle is being shipped to a secondary manufacturer that will hold the 

certificate of conformity, the model year must be assigned prior to introduction of the 

vehicle into U.S. commerce. The certifying manufacturer must redesignate the model 

year if it does not complete its manufacturing operations within the originally identified 

model year. A vehicle introduced into U.S. commerce without a model year is deemed to 

have a model year equal to the calendar year of its introduction into U.S. commerce 

unless the certifying manufacturer assigns a later date.
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Natural gas has the meaning given in 40 CFR 1036.801. Vehicles that use a pilot-ignited 

natural gas engine (which uses a small diesel fuel ignition system), are still considered 

natural gas vehicles.

NHTSA Enforcement means the NHTSA Associate Administrator for Enforcement, or his 

or her designee.

Party means the person alleged to have committed a violation of § 535.9, and includes 

manufacturers of vehicles and manufacturers of engines. 

Payload means in this part the resultant of subtracting the curb weight from the gross 

vehicle weight rating.

Petroleum has the meaning given in 40 CFR 1036.801. 

Pickup truck has the meaning given in 49 CFR part 523.

Plug-in hybrid electric vehicle (PHEV) means a hybrid electric vehicle that has the 

capability to charge the battery or batteries used for vehicle propulsion from an offvehicle electric source, such that the off-vehicle source cannot be connected to the 

vehicle while the vehicle is in motion.

Power take-off (PTO) means a secondary engine shaft or other system on a vehicle that 

provides substantial auxiliary power for purposes unrelated to vehicle propulsion or 

normal vehicle accessories such as air conditioning, power steering, and basic electrical 

accessories. A typical PTO uses a secondary shaft on the engine to transmit power to a 

hydraulic pump that powers auxiliary equipment such as a boom on a bucket truck. 

Primary intended service class has the meaning for engines as specified in 40 CFR part 

1036.140.

Rechargeable Energy Storage System (RESS) means the component(s) of a hybrid engine 

or vehicle that store recovered energy for later use, such as the battery system in a electric 

hybrid vehicle.

Regulatory category means each of the three types of heavy-duty vehicles defined in 49 

CFR 523.6 and the heavy-duty engines used in these heavy-duty vehicles.

Regulatory subcategory means the sub-groups in each regulatory category to which fuel 

consumption requirements apply, and are defined as follows:

(1) Heavy-duty pick-up trucks and vans

(2) Vocational light-heavy vehicles at or below 19,500 pounds GVWR. 

(3) Vocational medium-heavy vehicles above 19,500 pounds GVWR but at or below 

33,000 pounds GVWR.
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(4) Vocational heavy-heavy vehicles above 33,000 pounds GVWR.

(5) Low roof day cab tractors with a GVWR above 26,000 pounds but at or below 

33,000 pounds.

(6) Mid roof day cab tractors with a GVWR above 26,000 pounds but at or below 33,000 

pounds.

(7) High roof day cab tractors with a GVWR above 26,000 pounds but at or below 

33,000 pounds.

(8) Low roof day cab tractors above 33,000 pounds GVWR.

(9) Mid roof day cab tractors above 33,000 pounds GVWR.

(10) High roof day cab tractors above 33,000 pounds GVWR.

(11) Low roof sleeper cab tractors above 33,000 pounds GVWR.

(12) Mid roof sleeper cab tractors above 33,000 pounds GVWR. 

(13) High roof sleeper cab tractors above 33,000 pounds GVWR.

(14) Compression-ignition light heavy-duty engines in Class 2b to 5 vehicles with a 

GVWR above 8,500 pounds but at or below 19,500 pounds.

(15) Compression-ignition medium heavy-duty engines in Class 6 and 7 vocational 

vehicles with a GVWR above 19,500 but at or below 33,000 pounds.

(16) Compression-ignition heavy heavy-duty engines in Class 8 vocational vehicles with 

a GVWR above 33,000 pounds.

(17) Compression-ignition medium heavy-duty engines in Class 7 tractors with a GVWR 

above 26,000 pounds but at or below 33,000 pounds.

(18) Compression-ignition heavy heavy-duty engines in Class 8 tractors with a GVWR 

above 33,000 pounds.

(19) Spark ignition engines in Class 2b to 8 vehicles with a GVWR above 8,500 pounds. 

Roof height means the maximum height of a vehicle (rounded to the nearest inch), 

excluding narrow accessories such as exhaust pipes and antennas, but including any wide 

accessories such as roof fairings. Measure roof height of the vehicle configured to have 

its maximum height that will occur during actual use, with properly inflated tires and no 

driver, passengers, or cargo onboard. Determine the base roof height on fully inflated 

tires having a static loaded radius equal to the arithmetic mean of the largest and smallest 

static loaded radius of tires a manufacturer offers or a standard tire EPA approves. If a 

vehicle is equipped with an adjustable roof fairing, measure the roof height with the 
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fairing in its lowest setting. Once the maximum height is determined, roof heights are 

divided into the following categories:

(A) Low-roof means a vehicle with a roof height of 120 inches or less 

(B) Mid-roof means a vehicle with a roof height between 121 and 147 inches. 

(C) High-roof means a vehicle with a roof height of 148 inches or more. 

Service class group means a group of engine and vehicle averaging sets defined as 

follows: 

(A) Spark-ignition engines, light heavy-duty compression-ignition engines, light heavyduty vocational vehicles and heavy-duty pickup trucks and vans. 

(B) Medium heavy-duty compression-ignition engines and medium heavy-duty

vocational vehicles and tractors. 

(C) Heavy heavy-duty compression-ignition engines and heavy heavy-duty vocational 

vehicles and tractors. 

Sleeper cab means a type of truck cab that has a compartment behind the driver’s seat

intended to be used by the driver for sleeping. This includes both cabs accessible from 

the driver’s compartment and those accessible from outside the vehicle. 

Spark-ignition engines means relating to a gasoline-fueled engine or any other type of 

engine with a spark plug (or other sparking device) and with operating characteristics 

significantly similar to the theoretical Otto combustion cycle. Spark-ignition engines 

usually use a throttle to regulate intake air flow to control power during normal operation. 

Subconfiguration means a unique combination within a vehicle configuration of 

equivalent test weight, road-load horsepower, and any other operational characteristics or 

parameters that EPA determines may significantly affect CO2 emissions within a vehicle 

configuration. 

Test group means the multiple vehicle lines and model types that share critical emissions 

and fuel consumption related features and that are certified as a group by a common 

certificate of conformity issued by EPA and is used collectively with other test groups 

within an averaging set or regulatory subcategory and is used by NHTSA for 

determining the fleet average fuel consumption.

Tire rolling resistance level (TRRL) means a value with units of kg/metric ton that 

represents that rolling resistance of a tire configuration. TRRLs are used as inputs to the 

GEM model under 40 CFR part 1037.520. Note that a manufacturer may assign a value 

higher than a measured rolling resistance of a tire configuration.

Towing capacity in this part is equal to the resultant of subtracting the gross vehicle 

weight rating from the gross combined weight rating.
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Trade means to exchange fuel consumption credits, either as a buyer or a seller. 

Truck tractor has the meaning given in 49 CFR 571.3. This includes most heavy-duty 

vehicles specifically designed for the primary purpose of pulling trailers, but does not 

include vehicles designed to carry other loads. For purposes of this definition “other 

loads” would not include loads carried in the cab, sleeper compartment, or toolboxes. 

Examples of vehicles that are similar to tractors but that are not tractors under this part 

include dromedary tractors, automobile haulers, straight trucks with trailers hitches, and 

tow trucks. 

U.S.-directed production volume means the number of vehicle units, subject to the 

requirements of this part, produced by a manufacturer for which the manufacturer has a 

reasonable assurance that sale was or will be made to ultimate purchasers in the United 

States. Useful life has the meaning given in 40 CFR 1037.801.

Vehicle configuration means a unique combination of vehicle hardware and calibration 

(related to measured or modeled emissions) within a vehicle family. Vehicles with 

hardware or software differences, but that have no hardware or software differences 

related to measured or modeled emissions or fuel consumption can be included in the 

same vehicle configuration. Note that vehicles with hardware or software differences 

related to measured or modeled emissions or fuel consumption are considered to be 

different configurations even if they have the same GEM inputs and FEL. Vehicles 

within a vehicle configuration differ only with respect to normal production variability or 

factors unrelated to measured or modeled emissions and fuel consumption for EPA and 

NHTSA.

Vehicle family has the meaning given in 40 CFR part 1037.230.

Vehicle service class has the meaning for vehicles as specified in the 40 CFR part 

1037.801. Vocational tractor has the meaning given in 40 CFR part 1037.630.

Zero emissions vehicle means an electric vehicle or a fuel cell vehicle.

§ 535.5 Standards.

(a) Heavy-duty pickup trucks and vans. Each manufacturer of a fleet of heavy-duty 

pickup trucks and vans shall comply with the fuel consumption standards in this 

paragraph (a) expressed in gallons per 100 miles. If the manufacturer’s fleet includes 

conventional vehicles (gasoline, diesel and alternative fueled vehicles) and advanced 

technology vehicles (hybrids with regenerative braking, vehicles equipped with Rankinecycle engines, electric and fuel cell vehicles), it should divide its fleet into two separate 

fleets each with its own separate fleet average fuel consumption standard which a 

manufacturer must comply with the requirements of this paragraph (a). 

(1) For model years 2016 and later. Each manufacturer must comply with the fleet 

average standard derived from the unique subconfiguration target standards (or groups of 

subconfigurations approved by EPA in accordance with 40 CFR part 1037.104) of the 

model types that make up the manufacturer’s fleet in a given model year. Each 
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subconfiguration has a unique attribute-based target standard, defined by each group of 

vehicles having the same payload, towing capacity and whether the vehicles are equipped 

with a 2-wheel or 4-wheel drive configuration. 

(2) Subconfiguration target standards. (i) Two alternatives exist for determining the 

subconfiguration target standards for model years 2016 and later. For each alternative, 

separate standards exist for compression-ignition and spark-ignition vehicles: 

(A) The first alternative allows manufacturers to determine a fixed fuel consumption

standard that is constant over the model years; and 

(B) The second alternative allows manufacturers to determine standards that are phasedin gradually each year. 

(ii) Calculate the subconfiguration target standards as specified in this paragraph 

(a)(2)(ii), using the appropriate coefficients from Table 1 choosing between the 

alternatives in paragraphs (a)(2)(i)(A) and (B) of this section. For electric or fuel cell 

heavy-duty vehicles, use compression-ignition vehicle coefficients “c and d” and for 

hybrid (including plug-in hybrid), dedicated and dual-fueled vehicles, use coefficients “c 

and d” appropriate for the engine type used. Round each standard to the nearest 0.01 

gallons per 100 miles and specify all weights in pounds rounded to the nearest pound. 

Calculate the subconfiguration target standards using the following equation:

 Subconfiguration Target Standard (gallons per 100 miles) = [c × (WF)] + d 

Where:

WF = Work Factor = [0.75 x (Payload Capacity + Xwd)] + [0.25 x Towing Capacity]

Xwd = 4wd Adjustment = 500 lbs if the vehicle group is equipped with 4wd and allwheel drive, otherwise equals 0 lbs for 2wd.

Payload Capacity = GVWR (lbs) - Curb Weight (lbs) (for each vehicle group)

Towing Capacity = GCWR (lbs) - GVWR (lbs) (for each vehicle group)

Table 1– Equation Coefficients for Subconfiguration Target Standards 

Alternative 1 – Fixed Target Standards

Compression-ignition Vehicle Coefficients for Model Years 2016 and later

Model Year c d

2016 – 2018 0.000432 3.33

2019 and later 0.000409 3.14

Spark-ignition Vehicle Coefficients for Model Years 2016 and later

2016 -- 2018 0.000513 3.96

2019 and later 0.000495 3.81

Alternative 2 – Phased-in Target Standards

Compression-ignition Vehicle Coefficients for Model Years 2016 and later

Model Year c d

2016 0.000452 3.48

2017 0.000437 3.37

2018 and later 0.000409 3.14
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Spark-ignition Vehicle Coefficients for Model Years 2016 and later

2016 0.000528 4.07

2017 0.000518 3.98

2018 and later 0.000495 3.18

(3) Fleet average fuel consumption standard. (i) Calculate each manufacturer’s fleet 

average fuel consumption standard for conventional and advanced technology fleets 

separately based on the subconfiguration target standards specified in paragraph (a)(2) of 

this section, weighted to production volumes and averaged using the following equation 

combining all the applicable vehicles in a manufacturer’s U.S. directed fleet 

(compression-ignition, spark-ignition and advanced technology vehicles) for a given 

model year, rounded to the nearest 0.01 gallons per 100 miles: 

 

 

 



i

i i

Volume

Subconfiguration Target Standard Volume

Fleet AverageStandard

Where:

Subconfiguration Target Standardi = fuel consumption standard for each group of 

vehicles with same payload, towing capacity and drive configuration (gallons per 100 

miles).

Volumei = production volume of each unique subconfiguration of a model type based 

upon payload, towing capacity and drive configuration.

(A) A manufacturer may group together subconfigurations that have the same test weight 

(ETW), GVWR, and GCWR. Calculate work factor and target value assuming a curb 

weight equal to two times ETW minus GVWR. 

(B) A manufacturer may group together other subconfigurations if it uses the lowest 

target value calculated for any of the subconfigurations.

(C) The fleet average shall also be derived in accordance with 40 CFR 86.1865-12 and 40 

CFR part 1037.104(d).

(ii) A manufacturer complies with the requirements of this part if it provides reports, as 

specified in § 535.8, by the required deadlines and meets one of the following conditions:

(A) The manufacturer’s fleet average performance, as determined in § 535.6, is less than 

the fleet average standard; or 

(B) The manufacturer uses one or more of the credit flexibilities provided under 

NHTSA’s Averaging, Banking and Trading Program, as specified in § 535.7, to comply

with standards. 

(iii) Manufacturers must select an alternative for subconfiguration target standards at the 

same time they submit the model year 2016 Pre-Model year Report, specified in § 535.8. 
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Once selected, the decision cannot be reversed and the manufacturer must continue to 

comply with the same alternative for subsequent model years.

(iv) A manufacturer failing to comply with the provisions specified in paragraph 

(a)(3)(ii) of this section is liable to pay civil penalties in accordance with § 535.9.

(4) Voluntary standards. (i) Manufacturers may choose voluntarily to comply early

with fuel consumption standards for model years 2013 through 2015, as determined in 

paragraphs (a)(4)(iii) and (iv) in this section, for example, in order to begin accumulating 

credits through over-compliance with the applicable standard. A manufacturer choosing 

early compliance must comply with all the vehicles and engines it manufactures in each 

regulatory category for a given model year. 

(ii) A manufacturer must declare its intent to voluntarily comply with fuel consumption 

standards at the same time it submits a Pre-Model Report, prior to the compliance model 

year beginning as specified in § 535.8; and, once selected, the decision cannot be 

reversed and the manufacturer must continue to comply for each subsequent model year 

for all the vehicles and engines it manufactures in each regulatory category for a given 

model year.

(iii) Calculate separate subconfiguration target standards for compression-ignition and 

spark-ignition vehicles for model years 2013 through 2015 using the equation in 

paragraph (a)(2)(ii) in this section, substituting the appropriate values for the coefficients 

in Table 2 of this section as appropriate.

Table 2 – Voluntary Compliance Equation Coefficients for Vehicle Fuel Consumption Standards

Compression-ignition Vehicle Coefficients 

for Voluntary Compliance in Model Years 2013 through 2015

Model Year c d

2013 and 14 0.000470 3.61

2015 0.000466 3.60

Spark-ignition Vehicle Coefficients 

for Voluntary Compliance in Model Years 2013 through 2015

Model Year c d

2013 and 14 0.000542 4.17

2015 0.000539 4.15

(iv) Calculate the fleet average fuel consumption standards for model years 2013 through 

2015 using the equation in paragraph (a)(3) of this section.

(5) Exclusion of vehicles not certified as complete vehicles. The vehicle standards § 

535.5(a) do not apply for vehicles that are chassis-certified with respect to EPA’s criteria 

pollutant test procedure in 40 CFR part 86, subpart S. Any chassis-certified vehicles 

must comply with the vehicle standards and requirements of § 535.5(b) and the engine 

standards of § 535.5(d) for engines used in these vehicles. A vehicle manufacturer 

choosing to comply with this paragraph and that is not the engine manufacturer is 
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required to notify the engine manufacturers that their engines are subject to 535.5(d) and 

that it intends to use their engines in excluded vehicles. 

(6) Optional certification under this section. Manufacturers may certify any complete or 

cab-complete Class 2b through 5 vehicles weighing at or below 19,500 pounds GVWR 

and any incomplete vehicles approved by EPA for inclusion under this paragraph to the 

same testing and standard that applies to a comparable complete sister vehicles as 

determined in accordance in 40 CFR part 1037.150(l). Calculate the target standard 

value under paragraph (a)(2) of this section based on the same work factor value that 

applies for the complete sister vehicle. 

(7) Loose engines. This paragraph applies for spark-ignition engines identical to engines 

used in vehicles certified to the standards of this section § 535.5(a), where manufacturers 

sell such engines as loose engines or installed in incomplete vehicles that are not cabcomplete vehicles in accordance with 40 CFR part 1037.150(m). A manufacturer’s 

engines are deemed to have fuel consumption target values and test results based upon 

the complete vehicle in the applicable test group with the highest equivalent test weight 

in accordance with 40 CFR part 1037.150(m). The fuel consumption subconfiguration 

standard for a loose engines equals the test group result of the complete vehicle as 

specified in 40 CFR 1037.150(m)(6) multiplied by 1.10 and rounded to the nearest 0.01 

gallon per 100 miles. The U.S.-directed production volume of engines manufactured for 

sale as loose engines or installed in incomplete heavy-duty vehicles that are not cabcomplete vehicles in any given model year may not exceed ten percent of the total U.Sdirected production volume of engines of that design that the manufacturer produces for 

heavy-duty applications for that model year, including engines the manufacturer produces 

for complete vehicles, cab-complete vehicles, and other incomplete vehicles. The total 

number of engines a manufacturer may certify under this paragraph (7), of all engine 

designs, may not exceed 15,000 in any model year as specified in 40 CFR part 

1037.150(m). Engines produced in excess of the number cannot be certified to the 

standard in this paragraph (7). 

(b) Heavy-duty vocational vehicles. Each chassis manufacturer of heavy-duty vocational 

vehicles shall comply with the fuel consumption standards in this paragraph (b) expressed 

in gallons per 1000 ton-miles. Manufacturers of engines used in heavy-duty vocational 

vehicles shall comply with the standards in paragraph (d) of this section. 

(1) For model years 2016 and later. Each chassis manufacturer of heavy-duty

vocational vehicles must comply with the fuel consumption standards in paragraph (b)(3) 

of this section. 

(i) The heavy-duty vocational vehicle chassis category is subdivided by GVWR into 

three regulatory subcategories as defined in § 535.4, each with its own assigned standard. 

(ii) For purposes of certifying vehicles to fuel consumption standards, manufacturers 

must divide their product lines into vehicle families that have similar emissions and fuel 

consumption features, as specified by EPA in 40 CFR part 1037, subpart C, and these 
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families will be subject to the applicable standards. Each vehicle family is limited to a 

single model year. 

(iii) A manufacturer complies with the requirements of this part, if it provides 

information as specified in § 535.8, by the required deadlines and meets one of the 

following conditions:

(A) The manufacturer’s fuel consumption performance for each vehicle family, as 

determined in § 535.6, is lower than the applicable standard; or 

(B) The manufacturer uses one or more of the credit flexibilities provided under 

NHTSA’s Averaging, Banking and Trading Program, specified in § 535.7, to comply

with standards. 

(iv) A manufacturer failing to comply with the provisions specified in paragraph 

(b)(1)(iii) of this section is liable to pay civil penalties in accordance with § 535.9.

(2) Voluntary compliance. (i) For model years 2013 through 2015, a manufacturer may

choose voluntarily to comply early with the fuel consumption standards provided in 

paragraph (b)(3) of this section. For example, a manufacturer may choose to comply

early in order to begin accumulating credits through over-compliance with the applicable 

standards. A manufacturer choosing early compliance must comply with all the 

vehicles and engines it manufacturers in each regulatory category for a given model year. 

(ii) A manufacturer must declare its intent to voluntarily comply with fuel consumption 

standards and identify its plans to comply before it submits its first application for a 

certificate of conformity for the respective model year as specified in § 535.8; and, once 

selected, the decision cannot be reversed and the manufacturer must continue to comply

for each subsequent model year for all the vehicles and engines it manufacturers in each 

regulatory category for a given model year.

(3) Regulatory subcategory standards. The fuel consumption standards for heavy-duty 

vocational vehicles are given in the following table: 
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Table 3 – Heavy-Duty Vocational Vehicle Fuel Consumption Standards 

Fuel Consumption Mandatory Standards (gallons per 1000 ton-miles)

Effective for Model Years 2017 and later

Regulatory 

Subcategories

Light Heavy Vehicles 

Class 2b – 5

Medium Heavy 

Vehicles Class 6 - 7

Heavy Heavy Vehicles 

Class 8

Fuel Consumption 

Standard

36.7 22.1 21.8

Effective for Model Years 2016

Fuel Consumption 

Standard

38.1 23.0 22.2

Fuel Consumption Voluntary Standards (gallons per 1000 ton-miles)

Effective for Model Years 2013 to 2015

Regulatory 

Subcategories

Light Heavy Vehicles 

Class 2b – 5

Medium Heavy 

Vehicles Class 6 - 7

Heavy Heavy Vehicles 

Class 8

Fuel Consumption 

Standard

38.1 23.0 22.2

(4) A manufacturer may optionally certify a vocational vehicle to the standards and 

useful life applicable to a higher vehicle service class (or regulatory subcategory changes 

such as complying with the heavy heavy-duty standard instead of medium heavy-duty 

standard), provided the manufacturer does not generate credits with the vehicle. If a 

manufacturer includes smaller vehicles in a credit-generating subfamily (with an FEL 

below the standard), exclude their production volume from the credit calculation.

(5) Heavy-duty vocational vehicles including vocational tractors meeting the off-road 

criteria in 49 CFR part 523.2 are exempted from the requirements in paragraph (b) of this 

section but the engines in these vehicles must meet the requirements of paragraph (d) of 

this section. 

(c) Truck tractors. Each manufacturer of truck tractors, except vocational tractors, with a 

GVWR above 26,000 pounds shall comply with the fuel consumption standards in this 

paragraph (c) expressed in gallons per 1000 ton-miles. 

(1) For model years 2016 and later. Each manufacturer of truck tractors must comply

with the fuel consumption standards in paragraph (c)(3) of this section. 

(i) The truck tractor category is subdivided by roof height and cab design into nine 

regulatory subcategories as shown in Table 4 of this section, each with its own assigned 

standard. 

(ii) For purposes of certifying vehicles to fuel consumption standards, manufacturers 

must divide their product lines into vehicles families that have similar emissions and fuel 

consumption features, as specified by EPA in 40 CFR part 1037, subpart C, and these 

families will be subject to the applicable standards. Each vehicle family is limited to a 

single model year.

(iii) Standards for truck tractor engines are given in paragraph (d) of this section. 
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(iv) A manufacturer complies with the requirements of this part, if at the end of the 

model year, it provides reports, as specified in § 535.8, by the required deadlines and 

meets one of the following conditions:

(A) The manufacturer’s fuel consumption performance for each vehicle family, as 

determined in § 535.6, is lower than the applicable standard; or 

(B) The manufacturer uses one or more of the credit flexibilities provided under 

NHTSA’s Averaging, Banking and Trading Program, specified in § 535.7, to comply

with standards. 

(v) A manufacturer failing to comply with the provisions specified in paragraph 

(c)(1)(iv) of this section is liable to pay civil penalties in accordance with § 535.9.

(2) Voluntary compliance. (i) For model years 2013 through 2015, a manufacturer may

choose voluntarily to comply early with the fuel consumption standards provided in 

paragraph (c)(3) of this section. For example, a manufacturer may choose to comply

early in order to begin accumulating credits through over-compliance with the applicable 

standards. A manufacturer choosing early compliance must comply with all the 

vehicles and engines it manufacturers in each regulatory category for a given model year. 

(ii) A manufacturer must declare its intent to voluntarily comply with fuel consumption 

standards and identify its plans to comply before it submits its first application for a 

certificate of conformity for the respective model year as specified in § 535.8; and, once 

selected, the decision cannot be reversed and the manufacturer must continue to comply

for each subsequent model year for all the vehicles and engines it manufacturers in each 

regulatory category for a given model year.

(3) Regulatory subcategory standards. The fuel consumption standards for truck tractors, 

except for vocational tractors, are given in the following table:
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Table 4 – Truck Tractor Fuel Consumption Standards

Fuel Consumption Mandatory Standards (gallons per 1000 ton-miles)

Effective for Model Years 2017 and later

Regulatory 

Subcategories

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 10.2 7.8 6.5

Mid Roof 11.3 8.4 7.2

High Roof 11.8 8.7 7.1

Effective for Model Years 2016

Low Roof 10.5 8.0 6.7

Mid Roof 11.7 8.7 7.4

High Roof 12.2 9.0 7.3

Fuel Consumption Voluntary Standards (gallons per 1000 ton-miles)

Effective for Model Years 2013 to 2015

Regulatory 

Subcategories

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 10.5 8.0 6.7

Mid Roof 11.7 8.7 7.4

High Roof 12.2 9.0 7.3

(4) A manufacturer may optionally certify a tractor to the standards and useful life 

applicable to a higher vehicle service class (or regulatory subcategory changes such as 

complying with the Class 8 day-cab tractor standard instead of Class 7 day-cab tractor), 

provided the manufacturer does not generate credits with the vehicle. If a manufacturer 

includes smaller vehicles in a credit-generating subfamily (with an FEL below the 

standard), exclude their production volume from the credit calculation.

(5) Tractors meeting the definition of vocational tractors in 49 CFR part 523.2 must 

comply with requirements for heavy-duty vocational vehicles specified in paragraphs (b) 

and (d) of this section. Class 7 and Class 8 tractors certified or exempted as vocational 

tractors are limited in production to no more than 21,000 vehicles in any three 

consecutive model years. If a manufacturer is determined as not applying this allowance 

in good faith by the EPA in its applications for certification in accordance with 40 CFR 

part 1037.205 and 40 CFR part 1037.610, a manufacturer must comply with the tractor 

fuel consumption standards in paragraph (3) of this section. 

(d) Heavy-duty engines. Each manufacturer of heavy-duty engines shall comply with the 

fuel consumption standards in this paragraph (d) expressed in gallons per 100 brakehorsepower-hours. Each engine must be certified to the primary intended service class 

that it is designed for in accordance with 40 CFR part 1036.108; 

(1) For model years 2017 and later compression-ignition engines and for model years 

2016 and later spark-ignition engines. Each manufacturer must comply with the fuel 

consumption standard in paragraph (d)(3) of this section. 

(i) The heavy-duty engine regulatory category is divided into six regulatory 

subcategories, five compression-ignition subcategories and one spark-ignition 

subcategory, as shown in Table 5 of this section. 
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(ii) Separate standards exist for engines manufactured for use in heavy-duty vocational 

vehicles and in truck tractors.

(iii) For purposes of certifying engines to fuel consumption standards, manufacturers 

must divide their product lines into engine families that have similar fuel consumption 

features, as specified by EPA in 40 CFR part 1036, subpart C, and these families will be 

subject to the same standards. Each engine family is limited to a single model year.

(iv) A manufacturer complies with the requirements of this part, if at the end of the 

model year, it provides reports, as specified in § 535.8, by the required deadlines and 

meets one of the following conditions:

(A) The manufacturer’s fuel consumption performance of each engine family as 

determined in § 535.6 is less than the applicable standard; or 

(B) The manufacturer uses one or more of the flexibilities provided under NHTSA’s 

Averaging, Banking and Trading Program, specified in § 535.7, to comply with 

standards. 

(v) A manufacturer failing to comply with the provisions specified in paragraph 

(d)(1)(iv) of this section is liable to pay civil penalties in accordance with § 535.9.

(2) Voluntary compliance. (i) For model years 2013 through 2016 for compressionignition engines, and for model year 2015 for spark-ignition engines, a manufacturer may

choose voluntarily to comply with the fuel consumption standards provided in paragraph 

(d)(3), (d)(4) and (5) of this section. For example, a manufacturer may choose to comply

early in order to begin accumulating credits through over-compliance with the applicable 

standards. A manufacturer choosing early compliance must comply with all the vehicles 

and engines it manufacturers in each regulatory category for a given model year except in 

model year 2013 the manufacturer may comply with individual engine families as 

specified in 40 CFR part 1036.150(a)(2). 

(ii) A manufacturer must declare its intent to voluntarily comply with fuel consumption 

standards and identify its plans to comply before it submits its first application for a 

certificate of conformity for the respective model year as specified in § 535.8; and, once 

selected, the decision cannot be reversed and the manufacturer must continue to comply

for each subsequent model year for all the vehicles and engines it manufacturers in each 

regulatory category for a given model year. 

(3) Regulatory subcategory standards. The fuel consumption standards for heavy-duty 

engines are given in the following: 
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Table 5 – Primary Heavy-Duty Engine Standards

Fuel Consumption Mandatory Standards (gallons per100 bhp-hr)

Regulatory 

Subcategory

Light Heavy-Duty 

CompressionIgnition Engine

Medium Heavy-Duty 

Compression-Ignition 

Engine 

Heavy Heavy-Duty 

Compression-Ignition 

Engine

Spark-ignition 

Engines

Truck 

Application

Vocational Vocational Tractor Vocational Tractor All

Effective Model 

Years

2017 and later 2016 and later

Fuel 

Consumption 

Standard

5.66 5.66 4.78 5.45 4.52 7.06

Fuel Consumption Standards for Voluntary Compliance (gallons per100 bhp-hr)

Regulatory 

Subcategory

Light Heavy-Duty 

CompressionIgnition Engine

Medium Heavy-Duty 

Compression-Ignition 

Engine 

Heavy Heavy-Duty 

Compression-Ignition 

Engine

Spark-ignition 

Engine

Truck 

Application

Vocational Vocational Tractor Vocational Tractor All

Effective Model 

Years

2013 through 2016 2015

Voluntary Fuel 

Consumption 

Standard 

5.89 5.89 4.93 5.57 4.67 7.06

(4) Alternate subcategory standards. The alternative fuel consumption standards for 

heavy-duty compression-ignition engines are as follows: 

(i) Manufacturers entering the voluntary program in model years 2014 through 2016, 

may choose to certify compression-ignition engine families unable to meet standards 

provided in paragraph (3) of this part to the alternative fuel consumption standards of this 

section. 

(ii) Manufacturers may not certify engines to these alternate standards if they are part of 

an averaging set in which they carry a balance of banked credits. For purposes of this 

section, manufacturers are deemed to carry credits in an averaging set if they carry credits 

from advance technology that are allowed to be used in that averaging set in accordance 

with § 535.7(d)(12).

(iii) The emission standards of this section are determined as specified in EPA 40 CFR 

part 1036.620 (a) through (c) and should be converted to equivalent fuel consumption 

values.

(5) Alternate Phase-In Standards. Manufacturers have the option to comply with EPA 

emissions standards for compression-ignition engines using an alternative phase-in 

schedule that correlates with the EPA OBD standards. If a manufacturer chooses to use 

the alternative phase-in schedule for meeting EPA standards and optionally chooses to 

comply early with the NHTSA fuel consumption program, it must use the same phase-in 

schedule beginning in model year 2013 for fuel consumption standards and must remain 

in the program for each model year thereafter. The fuel consumption standard for each 

model year of the alternative phase-in schedule is provided in Table 6 of this section. 

Note that engines certified to these standards are not eligible for early credits under 

§ 535.7.
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Table 6 – Alternative Phase-in Compression Ignition Engine Standards

Tractors LHD Engines MHD Engines HHD Engines

Model Years 2013-

2015

NA 5.03gals/100 hp-hr 4.76 gals./100 hp-hr

Model Years 2016 

and later†

NA 4.78 gals./100 hp-hr 4.52 gals/100 hp-hr

Vocational LHD Engines MHD Engines HHD Engines

Model Years 2013-

2015

6.07gals/100hp-hr 6.07 gals/100 hp-hr 5.67 gals/100 hp-hr

Model Years 2016 

and later†

5.66 gals/100 hp-hr 5.66 gals/100 hp-hr 5.45 gals/100 hp-hr

† Note: these alternate standards for 2016 and later are the same as the otherwise applicable standards for 

2017 and later.

§ 535.6 Measurement and calculation procedures.

(a) Heavy-duty pickup trucks and vans. This section describes the testing a manufacturer 

must perform for each model year and the method for determining the fleet fuel 

consumption performance to show compliance with the fleet average fuel consumption 

standard for heavy-duty pickup trucks and vans in § 535.5(a). 

(1) For each model year, the heavy-duty pickup trucks and vans selected by a 

manufacturer to comply with fuel consumption standards in § 535.5(a) must be used to 

determine the manufacturer’s fleet average fuel consumption performance. If the

manufacturer’s fleet includes conventional and advanced technology heavy-duty pickup 

trucks and vans, the fleet should be sub-divided into two separate vehicle fleets, with all 

of the conventional vehicles in one fleet and all of the advanced technology vehicles in 

the other fleet.

(2) Vehicles in each fleet should be divided into test groups or subconfigurations 

according to EPA in 40 CFR part 1037.104 and 40 CFR part 86, subpart S. 

(3) Test and measure the CO2 emissions test results for the selected vehicles and 

determine the CO2 emissions test group result, in grams per mile in accordance with 40 

CFR Part 86, subpart S. 

(i) Perform exhaust testing on vehicles fueled by conventional and alternative fuels, 

including dedicated and dual fueled (multi-fueled and flexible fueled) vehicles and 

measure the CO2 emissions test result.

(ii) Adjust the CO2 emissions test result of dual fueled vehicles using a weighted average 

of your emission results as specified in 40 CFR 600.510–12(k) for light-duty trucks. 

(iii) All electric vehicles are deemed to have zero emissions of CO2, CH4, and N2O. No 

emission testing is required for such electric vehicles. Assign the fuel consumption test 

group result to a value of zero gallons per 100 miles in paragraph (4) of this section. 
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(iv) Test cab-complete and incomplete vehicles using the applicable complete sister 

vehicles as determined in 40 CFR part 1037.104(g).

(v) Test loose engines using applicable complete vehicles as determined in 40 CFR part 

1037.104(h).

(vi) Manufacturers can choose to analytically derive CO2 emission rates (ADCs) for test 

groups or subconfigurations. Calculate the ADCs for test groups or subconfigurations in 

accordance with 40 CFR part 1037.104(g). 

(4) Calculate equivalent fuel consumption test group results, in gallons per 100 miles, 

from CO2 emissions test group results, in grams per miles, and round to the nearest 0.01 

gallon per 100 miles. 

(i) Calculate the equivalent fuel consumption test group results as follows for 

compression-ignition vehicles and alternative fuel compression-ignition vehicles. CO2

emissions test group result (grams per mile) / 10,180 grams per gallon of diesel fuel) x 

(102) = Fuel consumption test group result (gallons per 100 mile).

(ii) Calculate the equivalent fuel consumption test group results as follows for sparkignition vehicles and alternative fuel spark-ignition vehicles. CO2 emissions test group 

result (grams per mile) / 8,877 grams per gallon of gasoline fuel) x (102) = Fuel 

consumption test group result (gallons per 100 mile).

(5) Calculate the fleet average fuel consumption result, in gallons per 100 miles, from 

the equivalent fuel consumption test group results and round the fuel consumption result 

to the nearest 0.01 gallon per 100 miles. Calculate the fleet average fuel consumption 

result using the following equation.

 

 

 



i

i i

Volume

FuelConsumption Test GroupResult Volume

Fleet AverageFuelConsumption

Where:

Fuel Consumption Test Group Resulti = fuel consumption performance for each test 

group as defined in § 523.4.

Volumei = production volume of each test group.

(6) Compare the fleet average fuel consumption standard to the fleet average fuel 

consumption performance. The fleet average fuel consumption performance must be less 

than or equal to the fleet fuel consumption standard to comply with standards in § 

535.5(a). 

(b) Heavy-duty vocational vehicles and tractors. This section describes the testing a 

manufacturer must perform and the method for determining fuel consumption 
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performance to show compliance with the fuel consumption standards for vocational 

vehicles and tractors in § 535.5(b) and (c). 

(1) Select vehicles and vehicle family configurations to test as specified in 40 CFR part 

1037.230 for vehicles that make up each of the manufacture’s regulatory subcategories of 

vocational vehicles and tractors.

(2) Determine the CO2 emissions and fuel consumption results for all vehicle chassis 

(conventional, alternative fueled and advanced technology vehicles) using the 

Greenhouse Emissions Model (GEM) in accordance with 40 CFR part 1037 subpart F. 

Vocational vehicles and tractor chassis are modeled using the following inputs in the 

GEM model. All seven of the following inputs apply for sleeper cab tractors, while some 

do not apply for vocational vehicles and other tractor regulatory subcategories:

(i) Identification of vehicles using regulatory subcategories (such as “Class 8 

Combination – Sleeper Cab – High Roof”).

(ii) Coefficient of aerodynamic drag in accordance with 40 CFR part 1037.520 and 40 

CFR part 1037.521. Do not use for vocational vehicles.

(iii) Steer tire rolling resistance for low rolling resistance tires in accordance with 40 

CFR part 1037.520 and 40 CFR part 1037.650.

(iv) Drive tire rolling resistance for low rolling resistance tires in accordance with 40 

CFR part 1037.520 and 40 CFR part 1037.650.

(v) Vehicle speed limit as governed by vehicles speed limiters in accordance with 40 

CFR part 1037.520 and 40 CFR part 1037.640. Do not use for vocational vehicles.

(vi) Vehicle weight reduction as provided in accordance with 40 CFR part 1037.520. 

Do not use for vocational vehicles.

(vii) Extended idle reduction credit using automatic engine shutdown systems in 

accordance with 40 CFR part 1037.520 and 40 CFR part 1037.660. Do not use for 

vehicles other than Class 8 sleeper cabs.

 (3) From the GEM results, select the CO2 family emissions level (FEL) and 

equivalent fuel consumption values for vocational vehicle and tractor families in each 

regulatory subcategories for each model year. Equivalent fuel consumption FELs are 

derived in GEM and expressed to the nearest 0.1 gallons per 1000 ton-mile. For families 

containing multiple subfamilies, identify the FELs for each subfamily. 

(4) The above sections address vocational vehicle and tractor chassis testing only. 

Engine performance and the advanced technologies equipped on vocational vehicles and 

tractors are tested separately as follows:

(i) Vocational vehicle and tractor engine test results for conventional and alternative 

fueled vehicles are determined in accordance with § 535.6(c). 

(ii) Improvements for advanced technologies are determined as follows:

(A) Test hybrid vehicles with power take-off in accordance with 40 CFR part 

1037.525 and vehicles with post-transmission hybrid systems in accordance with 40 CFR 

part 1037.550. 
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(B) All electric vehicles are deemed to have zero CO2 emissions and fuel consumption. 

No emission testing is required for such electric vehicles. Assign the vehicle family with 

a fuel consumption FEL result to a value of zero gallons per 1000-ton miles in paragraph 

(3) of this section. 

(c) Heavy-duty engines. This section describes the testing a manufacturer must perform 

and the method for determining fuel consumption performance to show compliance with 

the fuel consumption standards for engines in § 535.5(d). Each engine must be tested to 

the primary intended service class that it is designed for in accordance with 40 CFR part 

1036.108

(1) Select emission-data engines and engine family configurations to test as specified in 

40 CFR part 86 and 40 CFR part 1036 subpart C for engines installed in vehicles that 

make up each of the manufacture’s regulatory subcategory.

(2) Test the CO2 emissions for each emissions-data engine subject to the standards in § 

535.5(d) using the procedures and equipment specified in 40 CFR part 1036 subpart F. 

Measure the CO2 emissions in grams per bhp-hr as specified in 40 CFR part 86, subpart 

N and 40 CFR Part 1036 subpart C. 

(i) Perform exhaust testing on each fuel type for conventional, dedicated, dual fuel 

(multi-fuel, and flexible fuel) vehicles and measure the CO2 emissions level.

(ii) Adjust the CO2 emissions result of dual fueled vehicles using a weighted average of 

the demonstrated emission results as specified in 40 CFR part 1036.225. If EPA 

disapproves a manufacturer’s dual fuel vehicle demonstrated use submission, NHTSA 

will require the manufacturer to only use the test results with 100 percent conventional 

fuel to determine the fuel consumption of the engine. 

(iii) All electric vehicles are deemed to have zero emissions of CO2 and zero fuel 

consumption. No emission or fuel consumption testing is required for such electric 

vehicles. 

(3) Determine the CO2 emissions for the family certification level (FCL) from the 

emissions test results in paragraph (2) of this section for engine families within the 

heavy-duty engine regulatory subcategories for each model year. 

(i) If a manufacturer certifies an engine family for use both as a vocational engine and as 

a tractor engine, the manufacturer must split the family into two separate subfamilies in 

accordance with 40 CFR part 1036.230. The manufacturer may assign the numbers and 

configurations of engines within the respective subfamilies at any time prior to the 

submission of the end-of-year report required by 40 CFR 1036.730 and § 535.8. The 

manufacturer must track into which type of vehicle each engine is installed, although 

EPA may allow the manufacturer to use statistical methods to determine this for a 

fraction of its engines.
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(ii) The following engines are excluded from the engine families used to determined FCL 

values and the benefit for these engines is determined as an advanced technology credits 

under the ABT provisions provided in § 535.7(e):

(A) Engines certified as hybrid engines or power packs. 

(B) Engines certified as hybrid engines designed with PTO capability and that are sold 

with the engine coupled to a transmission.

(C) Engines with Rankine cycle waste heat recovery. 

(4) Calculate equivalent fuel consumption values for emissions FCLs and the CO2 levels 

for certified engines, in gallons per 100 bhp-hr and round each fuel consumption value to 

the nearest 0.01 gallon per 100 bhp-hr.

(i) Calculate equivalent fuel consumption FCL values for compression-ignition engines 

and alternative fuel compression-ignition engines. CO2 FCL value (grams per bhp-hr) / 

10,180 grams per gallon of diesel fuel) x (102) = Fuel consumption FCL value (gallons 

per 100 bhp-hr).

(ii) Calculate equivalent fuel consumption FCL values for spark-ignition engines and 

alternative fuel spark-ignition engines. CO2 FCL value (grams per bhp-hr) / 8,877 grams 

per gallon of gasoline fuel) x (102) = Fuel consumption FCL value (gallons per 100 bhphr).

(iii) Manufacturers may carryover fuel consumption data from a previous model year if 

allowed to carry over emissions data for EPA in accordance with 40 CFR Part 1036.235.

(iv) If a manufacturer uses an alternate test procedure under 40 CFR 1065.10 and 

subsequently the data is rejected by the EPA, NHTSA will also reject the data.

§ 535.7 Averaging, banking, and trading (ABT) Program.

(a) Fuel consumption credits (FCC). At the end of each model year, manufacturers may

earn credits for heavy-duty vehicles and engines exceeding the fuel consumption 

standards in § 535.5 or by using one or more of the flexibilities in this paragraph (a) to 

gain credits. Manufacturers may average, bank, and trade fuel consumption credits for 

purposes of complying with fuel consumption standards. The following criteria and 

restrictions apply to averaging, banking and trading FCC (hereafter reference as the 

NHTSA ABT program). 

(1) Averaging. Averaging is the exchange of FCC among a manufacturer’s engines or 

vehicle families or test groups within an averaging set. With the exception of FCC 

earned for advance technologies as further clarified below, a manufacturer may average 

FCC only within the same averaging set. The principle averaging sets are defined in 

535.4. 
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(2) Banking. Banking is the retention of surplus FCC by the manufacturer generating the 

credits for use in future model years for averaging or trading. Banked FCC retain the 

designation from the averaging set and model year in which they were generated and 

expire after five model years. 

(3) Trading. Trading is a transaction that transfers FCC between manufacturers or other 

entities. A manufacturer may use traded FCC for averaging, banking, or further trading 

transactions. Traded FCC, other than advanced technology credits, may be used only

within the averaging set in which they were generated.

(b) ABT provisions for heavy-duty pickup trucks and vans. (1) This regulatory category

consists of one regulatory subcategory, heavy-duty pickup trucks and vans. This one 

regulatory subcategory makes up one averaging set. 

(2) Manufacturers that manufacture vehicles within this regulatory subcategory shall 

calculate credits at the end of each model year based upon the final average fleet fuel 

consumption standard and final average fleet fuel consumption performance value within 

this one regulatory subcategory as identified in paragraph (b)(8) of this section. If the 

manufacturer’s fleet includes conventional vehicles (gasoline, diesel and alternative fuel) 

and advanced technology vehicles (hybrids with regenerative braking, vehicles equipped 

with Rankine-cycle engines, electric and fuel cell vehicles) it should be divided into two 

separate fleets each with its own final average fleet fuel consumption standard and final 

average fleet fuel consumption performance value. Credits shall be calculated for each of 

the two fleets.

(3) Fuel consumption levels below the standard create a “credit surplus,” while fuel 

consumption levels above the standard create a “credit shortfall.”

(4) Surplus credits, other than advanced technology credits, generated and calculated 

within this averaging set may only be used to offset a credit shortfall in this same 

averaging set. 

(5) Advanced technology credits can be used to offset a credit shortfall in this same 

averaging set or other averaging sets. However, a manufacturer must first apply

advanced technology credits to any deficits in the same averaging set before applying 

them to other averaging sets.

(6) Surplus credits, other than advanced technology credits, may be traded among credit 

holders but must stay within the same averaging set. Advanced technology credits can be 

traded across averaging sets. 

(7) Surplus credits, if not used to offset a credit shortfall may be banked by the 

manufacturer for use in future model years, or traded, given the restriction that the credits 

have an expiration date of five model years after the year in which the credits are earned. 

For example, credits earned in model year 2014 may be utilized through model year 

2019. 
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(8) Credit shortfalls must be offset by an available credit surplus within three model 

years after the shortfall was incurred. If the shortfall cannot be offset, the manufacturer is 

liable for civil penalties as discussed in § 535.9.

(9) Calculate the value of credits generated in a model year for this regulatory

subcategory or averaging set using the following equation: 

Total MY Fleet FCC (gallons) = (Std –Act)x(Volume)x(UL)x(102)

 Where: 

Std = Fleet average fuel consumption standard (gal/100 mile). 

Act = Fleet average actual fuel consumption value (gal/100 mile). 

Volume = the total U.S. directed production of vehicles in the regulatory

subcategory.

UL = the useful life for the regulatory subcategory (120,000 miles).

(10) If a manufacturer generates credits from its fleet of advanced technology vehicles in 

accordance with 535.7(e)(1) a multiplier of 1.5 can be used. Advanced technology

credits can be used in other averaging sets different from the one they are generated 

within with the following restrictions. 

(i)The maximum amount of credits a manufacturer may bring into the service class group 

that contains the heavy-duty pickup and van averaging set is 5.89 Mgallons (for advanced 

technology credits based upon compression ignition engines) or 6.76 Mgallons (for 

advanced technology credits based upon spark ignition engines) per model year as 

specified in 40 CFR part 1037.104: 

(ii) The limit specified in paragraph (b)(10)(i) of this section does not limit the amount of 

advanced technology credits that can be used across averaging sets within the same 

service class group. 

(11) Early credit provisions. If a manufacturer chooses to generate CO2 emission credits 

under EPA provisions of 1037.150(a), it may also voluntarily generate early credits under 

the NHTSA fuel consumption program. Fuel consumption credits may be generated for 

vehicles certified in model year 2013 to the model year 2014 standards in § 535.5 (a). To 

do so a manufacturer must certify its entire U. S. directed production volume of vehicles 

in its fleet. The same production volume restrictions specified in §1037.150 (a)(2) 

relating to when test groups are certified apply to the NHTSA early credit provisions. 

Credits are calculated as specified in paragraph (b)(9) of this section relative to the fleet 

standard that would apply for model year 2014 using the model year 2013 production 

volumes. Surplus credits generated under this paragraph are available credits for banking 

or trading. Credit deficits for an averaging set prior to model year 2014 do not carry over 

to model year 2014. These credits may be used to show compliance with the standards of 

this part for 2014 and later model years. Once a manufacturer opts into the NHTSA 
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program they must stay in the program for all of the optional model years and remain 

standardized with the same implementation approach being followed to meet the EPA 

CO2 emission program. 

(c) ABT provisions for vocational vehicles and tractors. (1) The two regulatory

categories for vocational vehicles and tractors consist of 12 regulatory subcategory as 

follows:

(i) Vocational vehicles with a GVWR up to and including 19,500 pounds (Light HeavyDuty (LHD));

(ii) Vocational vehicles with a GVWR above 19,500 pounds and no greater than 33,000 

pounds (Medium Heavy-Duty (MHD));

(iii) Vocational vehicles with a GVWR over 33,000 pounds (Heavy Heavy-Duty

(HHD));

(iv) Low roof day cab tractors with a GVWR above 26,000 pounds and no greater than 

33,000 pounds; 

(v) Mid roof day cab tractors with a GVWR above 26,000 pounds and no greater than 

33,000 pounds;

(vi) High roof day cab tractors with a GVWR above 26,000 pounds and no greater than 

33,000 pounds;

(vii) Low roof day cab tractors with a GVWR above 33,000 pounds; 

(viii) Mid roof day cab tractors with a GVWR above 33,000 pounds; 

(ix) High roof day cab tractors with a GVWR above 33,000 pounds; 

(x) Low roof sleeper cab tractors with a GVWR above 33,000 pounds; 

(xi) Mid roof sleeper cab tractors with a GVWR above 33,000 pounds; and 

(xii) High roof sleeper cab tractors with a GVWR above 33,000 pounds.

(2) The 12 regulatory subcategories consist of three averaging sets as follows:

(i) Vocational light-heavy vehicles at or below 19,500 pounds GVWR. 

(ii) Vocational and tractor medium-heavy vehicles above 19,500 pounds GVWR but at 

or below 33,000 pounds GVWR.

(iii) Vocational and tractor heavy-heavy vehicles above 33,000 pounds GVWR.

(3) Manufacturers that manufacture vehicles within either of these two vehicle 

categories, in one or more of the regulatory subcategories, shall calculate a total credit 

balance within each applicable averaging set at the end of each model year based upon 

final production volumes and the sum of the credit balances derived for each of the 

vehicle family groups within each averaging set.

(4) Each designated vehicle family group has a “family emissions limit” (FEL) which is

compared to the associated regulatory subcategory standard. A FEL that falls below the 

regulatory subcategory standard creates “positive credits,” while fuel consumption level 

of a family group above the standard creates a “credit shortfall.”

(5) Manufacturers shall sum all shortfalls and surplus credits for each vehicle family 

within each applicable averaging set to obtain the total credit balance for the model year 
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before rounding. The sum of fuel consumptions credits must be rounded to the nearest 

gallon.

(6) Surplus credits, other than advanced technology credits, generated and calculated 

within this averaging set may only be used to offset a credit shortfall in this same 

averaging set. 

(7) Advanced technology credits can be used to offset a credit shortfall in this same 

averaging set or other averaging sets. However, a manufacturer must first apply

advanced technology credits to any deficits in the same averaging set before applying 

them to other averaging sets.

(8) Surplus credits, other than advanced technology credits, may be traded among credit 

holders but must stay within the same averaging set. Advanced technology credits can be 

traded across averaging sets. 

(9) Surplus credits, if not used to offset a credit shortfall may be banked by the 

manufacturer for use in future model years, or traded, given the restriction that the credits 

have an expiration date of five model years after the year in which the credits are earned. 

For example, credits earned in model year 2014 may be utilized through model year 

2019. 

(10) Credit shortfalls must be offset by an available credit surplus within three model 

years after the shortfall was incurred. If the shortfall cannot be offset, the manufacturer is 

liable for civil penalties as discussed in § 535.9.

(11) The value of credits generated in a model year is calculated as follows: 

(i) Calculate the value of credits generated in a model year for each vehicle family within 

an averaging set using the following equation: 

Vehicle Family FCC (gallons) = (Std –FEL)x(Payload)x(Volume)x(UL)x(103)

Where: 

Std = the standard for the respective vehicle family regulatory subcategory (gal/1000 tonmile). 

FEL = family emissions limit for the vehicle family (gal/1000 ton-mile). 

Payload = the prescribed payload in tons for each regulatory subcategory as shown in the 

following table:

Regulatory subcategory Payload (Tons)

LHD Vocational Vehicles 2.85

MHD Vocational Vehicles 5.60
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HHD Vocational Vehicles 7.5

Class 7 Tractor 12.50

Class 8 Tractor 19.00

Volume = the number of U.S. directed production volume of vehicles in the 

corresponding vehicle family.

UL = the useful life for the regulatory subcategory (miles) as shown in the 

following table:

Regulatory subcategory UL (miles)

LHD Vocational Vehicles 110,000

MHD Vocational Vehicles 185,000

HHD Vocational Vehicles 435,000

Class 7 Tractor 185,000

Class 8 Tractor 435,000

(ii) Calculate the value of credits generated in a model year for each vehicle family for 

advanced technology vehicles within an averaging set using the equation above, the 

guidelines provided paragraph (e)(1)(i), and the 1.5 credit multiplier.

(iii) Calculate the total credits generated in a model year for each averaging set using the 

following equation:

Total averagingset MY credits Vehiclefamily credits within each averagingset 

(12) Early credit provisions. (i) If a manufacturer chooses to generate CO2 emission 

credits under EPA provisions of 1037.150(a), it may also voluntarily generate early 

credits under the NHTSA fuel consumption program. Fuel consumption credits may be 

generated for vehicles certified in model year 2013 to the model year 2014 standards in 

§ 535.5 (b) and (c). To do so a manufacturer must certify its entire U. S. directed 

production volume of vehicles. The same production volume restrictions specified in 

§1037.150 (a)(1) relating to when test groups are certified apply to the NHTSA early 

credit provisions. Credits are calculated as specified in paragraph (c)(11) of this section 

relative to the standards that would apply for model year 2014. Surplus credits generated 

under this paragraph may be increased by a factor of 1.5 for determining total available 

credits for banking or trading. For example, if you have 10 gallons of surplus credits for 

model year 2013, you may bank 15 gallons of credits. Credit deficits for an averaging set 

prior to model year 2014 do not carry over to model year 2014. These credits may be 

used to show compliance with the standards of this part for 2014 and later model years. 

Once a manufacturer opts into the NHTSA program they must stay in the program for all 

of the optional model years and remain standardized with the same implementation 

approach being followed to meet the EPA CO2 emission program. 

(ii) A tractor manufacturer may generate fuel consumption credits for the number of 

additional SmartWay designated tractors (relative to its MY 2012 production), provided 
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that credits are not generated for those vehicles under paragraph (12)(i). Calculate credits 

for each regulatory sub-category relative to the standard that would apply in model year 

2014 using the equations in paragraph (c)(11) above. Use a production volume equal to 

the number of verified model year 2013 SmartWay tractors minus the number of verified 

model year 2012 SmartWay tractors. A manufacturer may bank credits equal to the 

surplus credits generated under this paragraph multiplied by 1.50. A manufacturer’s 

2012 and 2013 model years must be equivalent in length. Once a manufacturer opts into 

the NHTSA program they must stay in the program for all of the optional model years 

and remain standardized with the same implementation approach being followed to meet 

the EPA CO2 emission program. 

(13) Advanced technology credits. (i) If a manufacturer generates credits from vehicles 

certified for advanced technology in accordance with 535.7(e)(1) a multiplier of 1.5 can 

be used, but this multiplier cannot be used on the same credits the early credit multiplier 

is used. Advanced technology credits can be used in other averaging sets different from 

the one they are generated within with the following restrictions. 

(ii) The maximum amount of credits a manufacturer may bring into a service class group 

that contains the vocational vehicle and tractor averaging sets is 5.89 Mgallons (for 

advanced technology credits based upon compression ignition engines) or 6.76 Mgallons 

(for advanced technology credits based upon spark ignition engines) per model year as 

specified in 40 CFR part 1037.740: 

(iii) The limit specified in paragraph (c)(13)(i) of this section does not limit the amount of 

advanced technology credits that can be used across averaging sets within the same 

service class group. 

(d) ABT provisions for heavy-duty engines. (1) Heavy-duty engines consist of six 

regulatory subcategories as follows:

(i) Spark-ignition engines.

(ii) Light heavy-duty compression-ignition engines.

(iii) Medium heavy-duty vocational compression-ignition engines.

(iv) Medium heavy-duty tractor compression-ignition engines

(v) Heavy heavy-duty vocational compression-ignition engines.

(vi) Heavy heavy-duty tractor compression-ignition engines.

(2) The six regulatory subcategories consist of four averaging sets as follows:

(i) Compression-ignition light heavy-duty engines.

(ii) Compression-ignition medium heavy-duty engines.
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(iii) Compression-ignition heavy heavy-duty engines.

(iv) Spark ignition engines 

(3) Manufacturers that manufacture engines within one or more of the regulatory

subcategories, shall calculate a total credit balance within each applicable averaging set at 

the end of each model year based upon final production volumes and the sum of the 

credit balances derived for each of the engine families within each averaging set. 

(4) Each designated engine family has a “family certification level” (FCL) which is 

compared to the associated regulatory subcategory standard. A FCL that falls below the 

regulatory subcategory standard creates “positive credits,” while fuel consumption level 

of a family group above the standard creates a “credit shortfall.”

(5) Manufacturers shall sum all surplus and shortfall credits for each engine family

within the applicable averaging set to obtain the total credit balance for the model year 

before rounding. Round the sum of fuel consumptions credits to the nearest gallon. 

(6) Surplus credits, other than advanced technology credits, generated and calculated 

within this averaging set may only be used to offset a credit shortfall in this same 

averaging set. 

(7) Advanced technology credits can be used to offset a credit shortfall in this same 

averaging set or other averaging sets. However, a manufacturer must first apply

advanced technology credits to any deficits in the same averaging set before applying

them to other averaging sets.

(8) Surplus credits, other than advanced technology credits, may be traded among credit 

holders but must stay within the same averaging set. Advanced technology credits can be 

traded across averaging sets. 

(9) Surplus credits, if not used to offset a credit shortfall may be banked by the 

manufacturer for use in future model years, or traded, given the restriction that the credits 

have an expiration date of five model years after the year in which the credits are earned. 

For example, credits earned in model year 2014 may be utilized through model year 

2019. 

(10) Credit shortfalls must be offset by available surplus credits within three model years 

after shortfall was incurred. If the shortfall cannot be offset, the manufacturer is liable 

for civil penalties as discussed in § 535.9. 

(11) The value of credits generated in a model year is calculated as follows: 

 (i) The value of credits generated in a model year for each engine family within a 

regulatory subcategory equals 

Engine Family FCC (gallons) = (Std – FCL)x(CF)x(Volume)x(UL)x(102)
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Where: 

Std = the standard for the respective engine regulatory subcategory (gal/100 bhp-hr). 

FCL = family certification level for the engine family (gal/100 bhp-hr).

CF= a transient cycle conversion factor in bhp-hr/mile which is the integrated total cycle 

brake horsepower-hour divided by the equivalent mileage of the applicable test cycle. 

For spark-ignition heavy-duty engines, the equivalent mileage is 6.3 miles. For 

compression-ignition heavy-duty engines, the equivalent mileage is 6.5 miles.

Volume = the number of engines in the corresponding engine family.

UL = the useful life of the given engine family (miles) as shown in the following table:

Regulatory Subcategory UL (miles)

Class 2b-5 Vocational Vehicles, Spark 

Ignited (SI), and Light Heavy-Duty Diesel 

Engines

110,000

Class 6-7 Vocational Vehicles and Medium 

Heavy-Duty Diesel Engines

185,000

Class 8 Vocational Vehicles and Heavy 

Heavy-Duty Diesel Engines

435,000

Regulatory Subcategory UL (miles)

Class 7 Tractors and Medium Heavy-Duty 

Diesel Engines 

185,000

Class 8 Tractors and Heavy Heavy-Duty 

Diesel Engines 

435,000

(ii) Calculate the total credits generated in a model year for each averaging set using the 

following equation:

Total averagingset MY credits  Engine family credits within each averagingset 

(12) Alternate standard provisions for compression ignition engines. (i) The provisions 

of this section apply to manufacturers utilizing the voluntary alternate standard provisions 

specified in § 535.5(d)(4). 

(ii) Manufacturers may not certify engines to the alternate standards if they are part of an 

averaging set in which they carry a balance of banked credits. For purposes of this 

section, manufacturers are deemed to carry credits in an averaging set if they carry credits 

from advance technology that are allowed to be used in that averaging set.

(iii) Manufacturers may not bank fuel consumption credits for any engine family in the 

same averaging set and model year in which it certifies engines to the alternate standards. 

This means a manufacturer may not bank advanced technology credits in a model year it 

certifies any engines to the alternate standards. 

(iv) Note that the provisions of §535.7(d)(10) apply with respect to credit deficits 

generated while utilizing alternate standards.
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(13) Alternative phase-in standard provisions for compression ignition engines. Where a 

manufacturer has chosen to comply with the EPA alternative phase-in standard 

provisions in 1036.150(e), and has optionally decided to follow the same path under the 

NHTSA fuel consumption program, it must certify all of its model year 2013 

compression-ignition engines within a given averaging set to the applicable alternative 

standards in 535.5(d)(5). Engines certified to these standards are not eligible for early 

credits under paragraph (14) of this section. Credits are calculated using the same 

equation provided in paragraph (11) of this section.

(14) Early credit provisions. If a manufacturer chooses to generate CO2 emission credits 

under EPA provisions of 1036.150, it may also voluntarily generate early credits under 

the NHTSA fuel consumption program. Fuel consumption credits may be generated for 

engines certified in model year 2013 (2015 for spark-ignition engines) to the standards in 

§ 535.5 (d). To do so a manufacturer must certify its entire U. S. directed production 

volume of engines except as specified in 40 CFR part 1036.150(a)(2). Credits are 

calculated as specified in paragraph (d)(11) of this section relative to the standards that 

would apply for model year 2014 (2016 for spark-ignition engines). Surplus credits 

generated under this paragraph may be increased by a factor of 1.5 for determining total

available credits for banking or trading. For example, if you have 10 gallons of surplus 

credits for model year 2013, you may bank 15 gallons of credits. Credit deficits for an 

averaging set prior to model year 2014 (2016 for spark-ignition engines) do not carry

over to model year 2014 (2016 for spark-ignition engines). These credits may be used to 

show compliance with the standards of this part for 2014 and later model years. Once a 

manufacturer opts into the NHTSA program they must stay in the program for all of the 

optional model years and remain standardized with the same implementation approach 

being followed to meet the EPA CO2 emission program.

(15) Advanced technology credits. (i) If a manufacturer generates credits from engines 

certified for advanced technology in accordance with 535.7(e)(1) a multiplier of 1.5 can 

be used, but this multiplier cannot be used on the same credits the early credit multiplier 

is used. Advanced technology credits can be used in other averaging sets different from 

the one they are generated within with the following restrictions. 

(ii) The maximum amount of credits a manufacturer may bring into a service class group 

that contains the heavy-duty engine averaging sets is 5.89 Mgallons (for advanced 

technology credits based upon compression ignition engines) or 6.76 Mgallons (for 

advanced technology credits based upon spark ignition engines) per model year as 

specified in 40 CFR part 1036.740: 

(iii) The limit specified in paragraph (d)(15)(ii) of this section does not limit the amount 

of advanced technology credits that can be used across averaging sets within the same 

service class group. 

(e) Additional credit provisions. (1) Advanced technology credits. Manufacturers of 

heavy-duty pickup trucks and vans, vocational vehicles, tractors and associated engines 

showing improvements in CO2 emissions and fuel consumption using hybrid vehicles 

with regenerative braking, vehicles equipped with Rankine-cycle engines, electric 

vehicles and fuel cell vehicles are eligible for advanced technology credits. Advanced 
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technology credits may be increased by a 1.5 multiplier and applied to any heavy-duty 

vehicle or engine subcategory consistent with sound engineering judgment.

(i) Heavy-duty vehicles. (A) For advanced technology system (hybrid vehicles with 

regenerative braking, vehicles equipped with Rankine-cycle engines and fuel cell 

vehicles), calculate the advanced technology credits as follows:

(1) Measure the effectiveness of the advanced system by chassis testing a vehicle 

equipped with the advanced system and an equivalent conventional system in accordance 

with 40 CFR part 1037.615. 

(2) For purposes of this paragraph a conventional vehicle is considered to be equivalent if 

it has the same footprint, intended vehicle service class, aerodynamic drag, and other 

relevant factors not directly related to the advanced system powertrain. If there is no 

equivalent vehicle, the manufacturer may create and test a prototype equivalent vehicle. 

The conventional vehicle is considered Vehicle A, and the advanced technology vehicle 

is considered Vehicle B. 

(3) The benefit associated with the advanced system for fuel consumption is determined 

from the weighted fuel consumption results from the chassis tests of each vehicle using 

the following equation:

Benefit (gallon/1000 ton mile) = Improvement Factor x GEM Fuel Consumption 

Result_B

Where:

Improvement Factor = (Fuel Consumption_A – Fuel Consumption_B)/(Fuel 

Consumption_A) 

Fuel Consumption Rates A and B are the gallons per 1000 ton-mile of the 

conventional and advanced vehicles, respectively as measured under the test 

procedures specified by EPA.

GEM Fuel Consumption Result B is the estimated gallons per 1000 ton-mile rate 

resulting from emission modeling of the advanced vehicle as specified in 40 CFR 

1037.520 and § 535.6(b).

(4) Calculate the benefit in credits using the equation in paragraph 535.7(c)(11) of this 

section and replacing the term (Std-FEL) with the benefit. 

(B) For electric vehicles calculate the fuel consumption credits using an FEL of 0 

g/1000ton-mile. 

(ii) Heavy-duty engines. (A) This section specifies how to generate advanced 

technology-specific fuel consumption credits for hybrid powertrains that include energy

storage systems and regenerative braking (including regenerative engine braking) and for 
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engines that include Rankine-cycle (or other bottoming cycle) exhaust energy recovery

systems. 

(1) Pre-transmission hybrid powertrains are those engine systems that include features 

that recover and store energy during engine motoring operation but not from the vehicle 

wheels. These powertrains are tested using the hybrid engine test procedures of 40 CFR 

part 1065 or using the post-transmission test procedures.

(2) Post-transmission hybrid powertrains are those powertrains that include features that 

recover and store energy from braking at the vehicle wheels. These powertrains are 

tested by simulating the chassis test procedure applicable for hybrid vehicles under 40 

CFR 1037.550. 

(3) Test engines that include Rankine-cycle exhaust energy recovery systems according 

to the test procedures specified in 40 CFR part 1036 subpart F of this part unless EPA 

approves the manufacturer’s alternate procedures.

 (B) Calculate credits as specified in § 535.7(c) of this part. Credits generated from 

engines and powertrains certified under this section may be used in other averaging sets 

as described in 40 CFR part 1036.740(d). 

(2) Innovative technology credits. This provision allows engine and vehicle 

manufacturers to generate CO2 emission credits consistent with the provisions of 40 CFR 

part 1036.610 (for engines), 40 CFR part 1037.104(d)(13) (for heavy-duty pickup trucks 

and vans) and 40 CFR part 1037.610 (for vocational vehicles and tractors) for introducing 

innovative technology in heavy-duty engines and vehicles for reducing greenhouse gas 

emissions and fuel consumption. Upon identification and approval from EPA of a 

manufacturer seeking to obtain innovative technology credits in a given model year, 

NHTSA may adopt an equivalent amount of fuel consumption credits into its program. 

Such credits must remain within the same regulatory subcategory in which the credits 

were generated. NHTSA will adopt these fuel consumption credits depending upon 

whether:

(i) The technology has a direct impact upon reducing fuel consumption performance; 

(ii) The manufacturer has provided sufficient information to make sound engineering 

judgments on the impact of the technology in reducing fuel consumption performance; 

and 

(iii) Credits will be accepted on a one-for-one basis expressed in terms of gallons.

§ 535.8 Reporting requirements.

(a) General Requirements. Manufacturers producing heavy-duty vehicles and engines 

applicable to fuel consumption standards in § 535.5, for each given model year, must 

submit the required information as specified in paragraphs (b) through (h) of this section. 
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(1) The information required by this part must be submitted by the deadlines specified in 

this section and must be based upon all the information and data available to the 

manufacturer 30 days before submitting information. 

(2) Manufacturers must submit information electronically through the EPA database 

system as the single point of entry for all information required for this national program 

and both agencies will have access to the information. The format for the required 

information is specified by EPA. 

(3) If by model year 2012, the agencies are not prepared to receive information through 

the EPA database system, manufacturers are required to submit information to EPA using 

an approved information format. A manufacturer can use a different format, if it sends 

EPA a written request with justification for a waiver.

(b) Pre-model year reports. Manufacturers producing heavy-duty pickup trucks and 

vans must submit reports in advance of the model year providing early estimates 

demonstrating how their fleet(s) would comply with GHG emissions and fuel 

consumption standards. Note, the agencies understand that early model year reports 

contain estimates that may change over the course of a model year and that compliance 

information manufactures submit prior to the beginning of a new model year may not 

represent the final compliance outcome. The agencies view the necessity for requiring 

early model reports as a manufacturer’s good faith projection for demonstrating 

compliance with emission and fuel consumption standards. 

(1) Report Deadlines. For model years 2013 and later, manufacturer of heavy-duty 

pickup trucks and vans complying with voluntary and mandatory standards must submit a 

pre-model year report for the given model year as early as the date of the manufacturer’s 

annual certification preview meeting with EPA and NHTSA, or prior to submitting its 

first application for a certificate of conformity to EPA in accordance with 40 CFR part 

1037.104(d). For example, a manufacturer choosing to comply in model year 2014 could 

submit its pre-model year report during its precertification meeting which could occur 

before January 2, 2013, or could provide its pre-model year report any time prior to 

submitting its first application for certification for the given model year. 

(2) Contents. Each pre-model year report must be submitted including the following 

information for each model year. 

(i) A list of each unique subconfiguration in the manufacturer’s fleet describing the make 

and model designations, attribute based-values (i.e., GVWR, GCWR, Curb Weight and 

drive configurations) and standards;

(ii) The emission and fuel consumption fleet average standard derived from the unique 

vehicle configurations;

(iii) The estimated vehicle configuration, test group and fleet production volumes;

(iv) The expected emissions and fuel consumption test group results and fleet average 

performance; 
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(v) If complying with MY 2013 fuel consumption standards, a statement must be 

provided declaring that the manufacturer is voluntarily choosing to comply early with the 

EPA and NHTSA programs. The manufacturers must also acknowledge that once 

selected, the decision cannot be reversed and the manufacturer will continue to comply

with the fuel consumption standards for subsequent model years for all the vehicles it 

manufacturers in each regulatory category for a given model year;

(vi) If complying with MYs 2014, 2015 or 2016 fuel consumption standards, a statement 

must be provided declaring whether the manufacturer will use fixed or increasing 

standards in accordance with Part 535.5(a). The manufacturer must also acknowledge 

that once selected, the decision cannot be reversed and the manufacturer must continue to 

comply with the same alternative for subsequent model years for all the vehicles it 

manufacturers in each regulatory category for a given model year;

(vii) If complying with MYs 2014 or 2015 fuel consumption standards, a statement must 

be provided declaring that the manufacturer is voluntarily choosing to comply with 

NHTSA’s voluntary fuel consumption standards in accordance with Part 535.5(a)(4). 

The manufacturers must also acknowledge that once selected, the decision cannot be 

reversed and the manufacturer will continue to comply with the fuel consumption 

standards for subsequent model years for all the vehicles it manufacturers in each 

regulatory category for a given model year;

(viii) The list of Class 2b-3 incomplete (cab-complete or chassis complete vehicles) and 

the method used to certify these vehicles as complete pickups and vans identifying the 

most similar complete sister- or other complete vehicles used to derive the target 

standards and performance test results;

(ix) The list of Class 4 and 5 incomplete and complete vehicles and the method use to 

certify these vehicles as complete pickups and vans identifying the most similar complete 

or sister vehicles used to derive the target standards and performance test results;

(x) List of loose engines included in the heavy-duty pickup and van category and the list 

of vehicles used to derive target standards and performance test results; 

(xi) Copy of any notices a vehicle manufacturer sends to the engine manufacturer to 

notify the engine manufacturers that their engines are subject to emissions and fuel 

consumption standards and that it intends to use their engines in excluded vehicles; 

(xii) A credit plan identifying the manufacturers estimated credit balances, planned 

credit flexibilities (i.e., credit balances, planned credit trading, innovative, advanced and 

early credits and etc.) and if needed a credit deficit plan demonstrating how it plans to 

resolve any credit deficits that might occur for a model year within a period of up to three 

model years after that deficit has occurred; and

(xiii) The supplemental information specified in paragraph (h) of this part. Note, 

NHTSA may also ask a manufacturer to provide additional information if necessary to 

verify compliance with the fuel consumption requirements of this regulation. 
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(c) Applications for certificate of conformity. Manufacturers producing vocational 

vehicles, tractors and heavy-duty engines are required to submit applications for 

certificates of conformity to EPA in accordance with 40 CFR part 1036.205 and 40 CFR 

part 1037.205 in advance of introducing vehicles for commercial sale. Applications 

contain early model year information demonstrating how manufacturers plan to comply

with GHG emissions. For model years 2013 and later, manufacturers of vocational 

vehicles, tractors and engine complying with NHTSA’s voluntary and mandatory

standards must submit applications for certificates of conformity in accordance through 

the EPA database including both GHG emissions and fuel consumption information for 

each given model year. 

(1) Submission Deadlines. Applications are primarily submitted in advance of the given 

model year to EPA but cannot be submitted any later than December 31st of the given 

model year. 

(2) Contents. Each application for certificates of conformity submitted to EPA must 

include the following equivalent fuel consumption.

(i) Equivalent fuel consumption values for emissions CO2 FCLs values used to certify

each engine family in accordance with 1036.205(e). This provision applies only to 

manufacturers producing heavy-duty engines. 

(ii) Equivalent fuel consumption values for emission CO2 data engines used to comply 

with emission standards in § 1036.108. This provision applies only to manufacturers 

producing heavy-duty engines. 

(iii) Equivalent fuel consumption values for emissions CO2 FELs values used to certify 

each vehicle families or subfamilies in accordance with 1037.205(k). This provision 

applies only to manufacturers producing vocational vehicles and tractors. 

(iv) Report modeling results for ten configurations in terms of CO2 emissions and 

equivalent fuel consumption results in accordance with 1037.205(o). Include modeling 

inputs and detailed descriptions of how they were derived. This provision applies only to 

manufacturers producing vocational vehicles and tractors. 

(3) Additional supplemental information. Manufacturers are required to submit 

additional information as specified in paragraph (h) of this part for the NHTSA program 

before or at the same time it submits its first application for a certificate of conformity to 

EPA. Under limited conditions, NHTSA may also ask a manufacturer to provide 

additional information directly to the Administrator if necessary to verify the fuel 

consumption requirements of this regulation.

(d) End-of-the-Year-Report. Both manufacturers participating and not participating in the 

ABT program are required to submit year end reports; end-of-the-year (EOY) reports in 

accordance with 40 CFR part 1036.730 and 40 CFR part 1037.730. The EOY reports are 

used to review a manufacturer’s preliminary final estimates and to identify manufacturers 

that might have a credit deficit for the given model year. For model years 2013 and later, 

heavy-duty vehicle and engine manufacturers complying with NHTSA’s voluntary and 
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mandatory standards must submit EOY reports through the EPA database including both 

GHG emissions and fuel consumption information for each given model year. 

(1) Report Deadlines. For model year 2013 and later, heavy-duty vehicle and engine 

manufacturers complying with NHTSA voluntary and mandatory standards must submit 

EOY reports through the EPA database including both GHG emissions and fuel 

consumption information within 90 days after the end of the given model year and no 

later than April 1 of the next calendar year. For example, the EOY report for model year 

2014 must be submitted no later than April 1, 2015.

(i) If a manufacturer expects differences in the information reported between the EOY 

and the final year report specified in 40 CFR part 1036.730 and 40 CFR part 1037.730, it 

must provide the most up-to-date fuel consumption projections in its EOY report and 

indentify the information as preliminary. 

(ii) If the manufacturer cannot provide any of the required fuel consumption information, 

it must state the specific reason for the insufficiency and identify the additional testing 

needed or explain what analytical methods are believed by the manufacturer will be 

necessary to eliminate the insufficiency and certify that the results will be available for 

the final report. 

(2) Contents. Each EOY report must be submitted including the following fuel 

consumption information for each model year. 

(i) Engine and vehicle family designations and averaging sets.

(ii) Engine and vehicle regulatory subcategory and fuel consumption standards including 

any alternative standards used.

(iii) Engine and vehicle family FCLs and FELs in terms of fuel consumption.

(iv) Production volumes for engines and vehicles.

(v) A credit plan (for manufacturers participating in the ABT program) identifying the 

manufacturers actual fuel consumption credit balances, credit flexibilities, credit trades 

and a credit deficit plan if needed demonstrating how it plans to resolve any credit 

deficits that might occur for a model year within a period of up to three model years after 

that deficit has occurred 

(vi) A plan describing the vocational vehicles and vocational tractors that were exempted 

as heavy-duty off-road vehicles.

(vii) A final plan describing any advanced technology engines or vehicles including 

alternative fueled vehicles that were produced for the model year identifying the 

approaches used to determinate compliance and the production volumes.

(viii) A final list of each unique subconfiguration included in a manufacturers fleet of 

heavy-duty pickup trucks and vans describing the designations, attribute based-values 
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(GVWR, GCWR, Curb Weight and drive configurations) and standards. This provision 

applies only to manufacturers producing heavy-duty pickup trucks and vans.

(ix) The final fuel consumption fleet average standard derived from the unique vehicle 

configurations. This provision applies only to manufacturers producing heavy-duty

pickup trucks and vans. 

(x) The preliminary final subconfiguration and test group production volumes. This 

provision applies only to manufacturers producing heavy-duty pickup trucks and vans. 

(xi) The preliminary final fuel consumption test group results and fleet average 

performance. This provision applies only to manufacturers producing heavy-duty pickup 

trucks and vans. 

(xii) Under limited conditions, NHTSA may also ask a manufacturer to provide 

additional information directly to the Administrator if necessary to verify the fuel 

consumption requirements of this regulation.

(e) Final Reports. Both manufacturers participating and not participating in the ABT 

program are required to submit year end final reports in accordance with 40 CFR part 

1036.730 and 40 CFR part 1037.730. The final reports are used to review a 

manufacturer’s final data and to identify manufacturers that might have a credit deficit 

for the given model year. For model years 2013 and later, heavy-duty vehicle and engine 

manufacturers complying with NHTSA’s voluntary and mandatory standards must 

submit final reports through the EPA database including both GHG emissions and fuel 

consumption information for each given model year. 

(1) Report Deadlines. For model year 2013 and later, heavy-duty vehicle and engine 

manufacturers complying with NHTSA voluntary and mandatory standards must submit 

final reports through the EPA database including both GHG emissions and fuel 

consumption information within 270 days after the end of the given model year and no 

later than October 1 of the next calendar year. For example, the final reports for model 

year 2014 must be submitted no later than October 1, 2015. 

(2) Contents. Each final report must be submitted including the following fuel 

consumption information for each model year. 

(i) Final engine and vehicle family designations and averaging sets.

(ii) Final engine and vehicle fuel consumption standards including any alternative 

standards used.

(iii) Final engine and vehicle family FCLs and FELs in terms of fuel consumption.

(iv) Final production volumes for engines and vehicles.

(v) A final credit plan identifying the manufacturers actual fuel consumption credit 

balances, credit flexibilities, credit trades and a credit deficit plan if needed 
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demonstrating how it plans to resolve any credit deficits that might occur for a model 

year within a period of up to three model years after that deficit has occurred 

(vi) A final plan describing the vocational vehicles and vocational tractors that were 

exempted as heavy-duty off-road vehicles.

(vii) A final plan describing any advanced technology engines or vehicles including 

alternative fueled vehicles that were produced for the model year identifying the 

approaches used to determinate compliance and the production volumes.

(viii) A final list of each unique subconfiguration included in a manufacturers fleet of 

heavy-duty pickup trucks and vans describing the designations, attribute based-values 

(GVWR, GCWR, Curb Weight and drive configurations) and standards. This provision 

applies only to manufacturers producing heavy-duty pickup trucks and vans.

(ix) The final fuel consumption fleet average standard derived from the unique vehicle 

configurations. This provision applies only to manufacturers producing heavy-duty

pickup trucks and vans. 

(x) The final subconfiguration and test group production volumes. This provision 

applies only to manufacturers producing heavy-duty pickup trucks and vans.

(xi) The final fuel consumption test group results and fleet average performance. This 

provision applies only to manufacturers producing heavy-duty pickup trucks and vans. 

(xii) Under limited conditions, NHTSA may also ask a manufacturer to provide 

additional information directly to the Administrator if necessary to verify the fuel 

consumption requirements of this regulation.

(f) Amendments to applications for certification. At any time, a manufacturer modifies 

an application for certification in accordance with § 1036.225 and § 1037.225, it must 

submit GHG emissions changes with equivalent fuel consumption values for the 

information required in paragraphs (b) through (e) and (h) of this part. 

(g) Confidential Information. Manufacturers must submit a request for confidentiality

with each electronic specifying any part of the for information or data in a report that it 

believes should be withheld from public disclosure as trade secret or other confidential 

business information. Information submitted to EPA should follow EPA guidelines for 

treatment of confidentiality. Confidential information submitted to NHTSA shall be 

treated according to paragraph (g)(1) of this section.

(1) For any information or data requested by the manufacturer to be withheld under 5 

U.S.C. 552(b)(4) and 15 U.S.C. 2005(d)(1), the manufacturer shall provide evidence in 

its request for confidentiality to justify that:

(i) The item is within the scope of 5 U.S.C. 552(b)(4) and 15 U.S.C. 2005(d)(1);

(ii) The disclosure of such as item would result in significant competitive damage;
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(iii) The period during which the item must be withheld to avoid that damage; and

(iv) How earlier disclosure would result in that damage.

(h) Additional Required Information. The following additional information is required to 

be submitted through the EPA database. NHTSA reserves the right to ask a manufacturer 

to provide additional information if necessary to verify the fuel consumption 

requirements of this regulation. 

(1) Small business exemptions. Vehicles and engines produced by small business 

manufacturers meeting the criteria in 13 CFR part 121.201 are exempted from the 

requirements of this regulation. Qualifying small business manufacturers must notify the 

EPA and NHTSA Administrators before importing or introducing into U.S. commerce 

exempted vehicles or engines. This notification must include a description of the 

manufacturer’s qualification as a small business under 13 CFR 121.201 and must be 

submitted to EPA. The agencies may review a manufacturer’s qualification as a small 

business manufacturer under 13 CFR 121.201.

(2) Early Introduction. The provision applies to manufacturers seeking to comply early 

with the NHTSA’s fuel consumption program prior to model year 2014. The 

manufacturer must send the request to EPA before submitting its first application for a 

certificate of conformity. 

(3) NHTSA Voluntary Compliance Model Years. Manufacturers must submit a statement 

declaring whether the manufacturer chooses to comply voluntarily with NHTSA’s fuel 

consumption standards for model years 2014 through 2015. The manufacturers must 

acknowledge that once selected, the decision cannot be reversed and the manufacturer 

will continue to comply with the fuel consumption standards for subsequent model years. 

The manufacturer must send the statement to EPA before submitting its first application 

for a certificate of conformity. 

(4) Alternative engine standards. Manufacturers choosing to comply with the alternative 

engine standards must notify EPA and NHTSA of their choice and include in that 

notification a demonstration that it has exhausted all available credits and credit 

opportunities. The manufacturer must send the statement to EPA before submitting its 

EOY report. 

(5) Alternate phase-in. Manufacturers choosing to comply with the alternative engine 

phase-in must notify EPA and NHTSA of their choice. The manufacturer must send the 

statement to EPA before submitting its first application for a certificate of conformity. 

(6) Off-road exclusion (tractors and vocational vehicles only). (i) Vehicles intended to 

be used extensively in off-road environments such as forests, oil fields, and construction 

sites may be exempted without request from the requirements of this regulation as 

specified in 49 CFR 523.2 and § 535.5(b). Within 90 days after the end of each model 

year, manufacturers must send EPA and NHTSA through the EPA database a report with 

the following information:
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(A) A description of each excluded vehicle configuration, including an explanation of 

why it qualifies for this exclusion.

(B) The number of vehicles excluded for each vehicle configuration. 

(ii) A manufacturer having an off-road vehicle failing to meet the criteria under the 

agencies’ off-road exclusions will be allowed to submit a petition describing how and 

why their vehicles should qualify for exclusion. The process of petitioning for an 

exclusion is explained below. For each request, the manufacturer will be required to 

describe why it believes an exclusion is warranted and address following factors which 

the agencies will consider in granting its petition: 

(A) The agencies will provide an exclusion based on off road capability of the vehicle or 

if the vehicle is fitted with speed restricted tires. A manufacturer should explain which 

exclusion does its vehicle qualify under; and

(B) A manufactures should verify if there any comparable tires that exist in the market to 

carry out the desired application both on and off road for the subject vehicle(s) of the 

petition which have LLR values that would enable compliance with the standard.

(7) Vocational Tractor. Tractors intended to be used as vocational tractors may comply

with vocational vehicle standards in Part 535.5(b) of this regulation. Manufacturers 

classifying tractor as vocational tractors must provide a description of how they meet the 

qualifications in their applications for certificates of conformity as specified in 40 CFR 

part 1037.205. 

(8) Approval of alternate methods to determine drag coefficients (tractors only). 

Manufacturers seeking to use alternative methods to determine aerodynamic drag 

coefficients must provide a request and gain approval by EPA. The manufacturer must 

send the request to EPA before submitting its first application for a certificate of 

conformity. 

(9) Innovative Technology Credits. Manufacturers pursuing innovative technology

credits must submit information to the agencies and may be subject to a public evaluation 

process in which the public would have opportunity for comment if not using a test 

procedure in accordance with 40 CFR part 1037.610(c). Whether the approach involves 

on-road testing, modeling, or some other analytical approach, the manufacturer would be 

required to present a final methodology to EPA and NHTSA. EPA and NHTSA would 

approve the methodology and credits only if certain criteria were met. Baseline 

emissions and fuel consumption and control emissions and fuel consumption would need 

to be clearly demonstrated over a wide range of real world driving conditions and over a 

sufficient number of vehicles to address issues of uncertainty with the data. Data would 

need to be on a vehicle model-specific basis unless a manufacturer demonstrated modelspecific data was not necessary. The agencies may publish a notice of availability in the 

Federal Register notifying the public of a manufacturer’s proposed alternative off-cycle 

credit calculation methodology and provide opportunity for comment. Any notice will 
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include details regarding the methodology, but not include any Confidential Business 

Information.

(10) If a manufacturer trades fuel consumption credits, it must send EPA a report within 

90 days after the transaction, as follows:

(i) As the seller, the manufacturer must include the following information in its report:

(A) The corporate names of the buyer and any brokers.

(B) A copy of any contracts related to the trade.

(C) The fleet, vehicle or engine families that generated fuel consumption credits for the 

trade, including the number of fuel consumption credits from each family.

(ii) As the buyer, the manufacturer or entity must include the following information in its 

report:

(A) The corporate names of the seller and any brokers.

(B) A copy of any contracts related to the trade.

(C) How the manufacturer or entity intends to use the fuel consumption credits, including 

the number of fuel consumption credits it intends to apply to each vehicle family (if 

known).

(i) Public Information. Based upon information submitted by manufacturers and EPA, 

NHTSA will publish fuel consumption standards and performance results. 

(j) Information received from EPA. NHTSA will receive information from EPA as 

specified in 40 CFR part1036.755 and 40 CFR part 1037.755. 

§535.9 Enforcement Approach.

(a) Compliance. (1) NHTSA will assess compliance with fuel consumption standards 

each year, based upon EPA final verified data submitted to NHTSA for its heavy-duty 

vehicle fuel efficiency program established pursuant to 49 U.S.C. 32902(k). NHTSA 

may conduct verification testing throughout a given model year in order to validate data 

received from manufacturers and will discuss any potential issues with EPA and the 

manufacturer. 

(2) Credit values in gallons are calculated based on the final CO2 emissions and fuel 

consumption data submitted by manufacturers and verified/validated by EPA. 

(3) NHTSA will verify a manufacturer’s credit balance in each averaging set for each 

given model year. The average set balance is based upon the engines or vehicles 

performance above or below the applicable regulatory subcategory standards in each 
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respective averaging set and any credits that are traded into or out of an averaging set 

during the model year. 

(i) If the balance is positive, the manufacturer is designated as having a credit surplus.

(ii) If the balance is negative, the manufacturer is designated as having a credit deficit. 

(4) NHTSA will provide written notification to the manufacturer that has a negative 

balance for any averaging set for each model year. The manufacturer will be required to 

confirm the negative balance and submit a plan indicating how it will allocate existing 

credits or earn, and/or acquire by trade credits, or else be liable for a civil penalty as 

determined in paragraph (b) of this section. The manufacturer must submit a plan within 

60 days of receiving agency notification.

(5) Credit shortfall within an averaging set may be carried forward only three years, and 

if not offset by earned or traded credits, the manufacturer may be liable for a civil penalty

as described in paragraph (b) of this section. 

(6) Credit allocation plans received from a manufacturer will be reviewed and approved 

by NHTSA. NHTSA will approve a credit allocation plan unless it determines that the 

proposed credits are unavailable or that it is unlikely that the plan will result in the 

manufacturer earning sufficient credits to offset the subject credit shortfall. If a plan is 

approved, NHTSA will revise the respective manufacturer's credit account accordingly 

by identifying which existing or traded credits are being used to address the credit 

shortfall, or by identifying the manufacturer’s plan to earn future credits for addressing 

the respective credit shortfall. If a plan is rejected, NHTSA will notify the respective 

manufacturer and request a revised plan. The manufacturer must submit a revised plan 

within 14 days of receiving agency notification. The agency will provide a manufacturer 

one opportunity to submit a revised credit allocation plan before it initiates civil penalty

proceedings. 

(7) For purposes of this regulation, NHTSA will treat the use of future credits for 

compliance, as through a credit allocation plan, as a deferral of civil penalties for noncompliance with an applicable fuel consumption standard.

(8) If NHTSA receives and approves a manufacturer's credit allocation plan to earn 

future credits within the following three model years in order to comply with regulatory

obligations, NHTSA will defer levying civil penalties for non-compliance until the 

date(s) when the manufacturer's approved plan indicates that credits will be earned or 

acquired to achieve compliance, and upon receiving confirmed CO2 emissions and fuel 

consumption data from EPA. If the manufacturer fails to acquire or earn sufficient 

credits by the plan dates, NHTSA will initiate civil penalty proceedings.

(9) In the event that NHTSA fails to receive or is unable to approve a plan for a noncompliant manufacturer due to insufficiency or untimeliness, NHTSA may initiate civil

penalty proceedings.
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(10) In the event that a manufacturer fails to report accurate fuel consumption data for 

vehicles or engines covered under this rule, noncompliance will be assumed until 

corrected by submission of the required data, and NHTSA may initiate civil penalty

proceedings.

(b) Civil Penalties. (1) Generally. NHTSA may assess a civil penalty for any violation 

of this part under 49 U.S.C. 32902(k). This section states the procedures for assessing 

civil penalties for violations of 49 CFR 535. 5. The provisions of 5 U.S.C. 554, 556, and 

557 do not apply to any proceedings conducted pursuant to this section.

(2) Initial Determination of Noncompliance. An action for civil penalties is commenced 

by the execution of a Notice of Violation. A determination by NHTSA’s Office of 

Enforcement of noncompliance with applicable fuel consumption standards utilizing the 

certified and reported CO2 emissions and fuel consumption data provided by the 

Environmental Protection Agency as described in this part, and after considering all the 

flexibilities available under § 535.7, underlies a Notice of Violation. If NHTSA 

Enforcement determines that a manufacturer’s averaging set of vehicles or engines fails 

to comply with the applicable fuel consumption standard(s) by generating a credit 

shortfall, the chassis, vehicle or engine manufacturer, as relevant, shall be subject to a 

civil penalty.

(3) Numbers of Violations and Maximum Civil Penalties. Any violation shall constitute a 

separate violation with respect to each vehicle or engine within the applicable regulatory

averaging set. The maximum civil penalty is not more than $37,500.00 per vehicle or 

engine. The maximum civil penalty under this section for a related series of violations 

shall be determined by multiplying $37,500.00 times the vehicle or engine production 

volume for the model year in question within the regulatory averaging set. NHTSA may

adjust this civil penalty amount to account for inflation. 

(4) Factors for determining penalty amount. In determining the amount of any civil 

penalty proposed to be assessed or assessed under this section, NHTSA shall take into 

account the gravity of the violation, the size of the violator’s business, the violator’s 

history of compliance with applicable fuel consumption standards, the actual fuel 

consumption performance related to the applicable standards, the estimated cost to 

comply with the regulation and applicable standards, the quantity of vehicles or engines 

not complying, and the effect of the penalty on the violator’s ability to continue in 

business. The “estimated cost to comply with the regulation and applicable standards,” 

will be used to ensure that penalties for non-compliance will not be less than the cost of 

compliance.

(5) NHTSA enforcement report of determination of non-compliance. (i) If NHTSA 

Enforcement determines that a violation has occurred, NHTSA Enforcement may prepare 

a report and send the report to the NHTSA Chief Counsel.

(ii) The NHTSA Chief Counsel will review the report prepared by NHTSA Enforcement 

to determine if there is sufficient information to establish a likely violation.
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(iii) If the Chief Counsel determines that a violation has likely occurred, the Chief 

Counsel may issue a Notice of Violation to the party.

(iv) If the Chief Counsel issues a Notice of Violation, he or she will prepare a case file 

with recommended actions. A record of any prior violations by the same party shall be 

forwarded with the case file.

(6) Notice of violation. (i) The Notice of Violation will contain the following 

information:

(A) The name and address of the party;

(B) The alleged violation(s) and the applicable fuel consumption standard(s) violated;

(C) The amount of the proposed penalty and basis for that amount;

(D) The place to which, and the manner in which, payment is to be made;

(E) A statement that the party may decline the Notice of Violation and that if the Notice 

of Violation is declined within 30 days of the date shown on the Notice of Violation, the 

party has the right to a hearing, if requested within 30 days of the date shown on the 

Notice of Violation, prior to a final assessment of a penalty by a Hearing Officer; and

(F) A statement that failure to either pay the proposed penalty or to decline the Notice of 

Violation and request a hearing within 30 days of the date shown on the Notice of 

Violation will result in a finding of violation by default and that NHTSA will proceed 

with the civil penalty in the amount proposed on the Notice of Violation without 

processing the violation under the hearing procedures set forth in this subpart.

(ii) The Notice of Violation may be delivered to the party by:

(A) Mailing to the party (certified mail is not required);

(B) Use of an overnight or express courier service; or

(C) Facsimile transmission or electronic mail (with or without attachments) to the party 

or an employee of the party.

(iii) At any time after the Notice of Violation is issued, NHTSA and the party may agree 

to reach a compromise on the payment amount. 

(iv) Once a penalty amount is paid in full, a finding of “resolved with payment” will be 

entered into the case file. 

(v) If the party agrees to pay the proposed penalty, but has not made payment within 30 

days of the date shown on the Notice of Violation, NHTSA will enter a finding of 

violation by default in the matter and NHTSA will proceed with the civil penalty in the 
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amount proposed on the Notice of Violation without processing the violation under the 

hearing procedures set forth in this subpart.

(vi) If within 30 days of the date shown on the Notice of Violation a party fails to pay the 

proposed penalty on the Notice of Violation, and fails to request a hearing, then NHTSA 

will enter a finding of violation by default in the case file, and will assess the civil penalty

in the amount set forth on the Notice of Violation without processing the violation under 

the hearing procedures set forth in this subpart.

(vii) NHTSA’s order assessing the civil penalty following a party’s default is a final 

agency action.

(7) Hearing Officer. (i) If a party timely requests a hearing after receiving a Notice of 

Violation, a Hearing Officer shall hear the case.

(ii) The Hearing Officer will be appointed by the NHTSA Administrator, and is solely

responsible for the case referred to him or her. The Hearing Officer shall have no other 

responsibility, direct or supervisory, for the investigation of cases referred for the 

assessment of civil penalties. The Hearing Officer shall have no duties related to the 

light-duty fuel economy or medium- and heavy-duty fuel efficiency programs.

(iii) The Hearing Officer decides each case on the basis of the information before him or 

her.

(8) Initiation of action before the Hearing Officer. (i) After the Hearing Officer 

receives the case file from the Chief Counsel, the Hearing Officer notifies the party in 

writing of:

(A) The date, time, and location of the hearing and whether the hearing will be 

conducted telephonically or at the DOT Headquarters building in Washington, DC;

(B) The right to be represented at all stages of the proceeding by counsel as set forth in 

the paragraph (b)(9) of this section;

(C) The right to a free copy of all written evidence in the case file.

(ii) On the request of a party, or at the Hearing Officer’s direction, multiple proceedings 

may be consolidated if at any time it appears that such consolidation is necessary or 

desirable.

(9) Counsel. A party has the right to be represented at all stages of the proceeding by 

counsel. A party electing to be represented by counsel must notify the Hearing Officer of 

this election in writing, after which point the Hearing Officer will direct all further 

communications to that counsel. A party represented by counsel bears all of its own 

attorneys’ fees and costs.

(10) Hearing location and costs. (i) Unless the party requests a hearing at which the 

party appears before the Hearing Officer in Washington, DC, the hearing may be held 
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telephonically. In Washington, DC, the hearing is held at the headquarters of the U.S. 

Department of Transportation.

(ii) The Hearing Officer may transfer a case to another Hearing Officer at a party’s 

request or at the Hearing Officer’s direction.

(iii) A party is responsible for all fees and costs (including attorneys’ fees and costs, and 

costs that may be associated with travel or accommodations) associated with attending a 

hearing.

(11) Hearing procedures. (i) There is no right to discovery in any proceedings 

conducted pursuant to this subpart. 

(ii) The material in the case file pertinent to the issues to be determined by the Hearing 

Officer is presented by the Chief Counsel or his or her designee.

(iii) The Chief Counsel may supplement the case file with information prior to the 

hearing. A copy of such information will be provided to the party no later than 3 

business days before the hearing.

(iv) At the close of the Chief Counsel’s presentation of evidence, the party has the right 

to examine respond to and rebut material in the case file and other information presented 

by the Chief Counsel. In the case of witness testimony, both parties have the right of 

cross-examination.

(v) In receiving evidence, the Hearing Officer is not bound by strict rules of evidence. In 

evaluating the evidence presented, the Hearing Officer must give due consideration to the 

reliability and relevance of each item of evidence.

(vi) At the close of the party’s presentation of evidence, the Hearing Officer may allow 

the introduction of rebuttal evidence that may be presented by the Chief Counsel. 

(vii) The Hearing Officer may allow the party to respond to any rebuttal evidence 

submitted. 

(viii) After the evidence in the case has been presented, the Chief Counsel and the party 

may present arguments on the issues in the case. The party may also request an 

opportunity to submit a written statement for consideration by the Hearing Officer and 

for further review. If granted, the Hearing Officer shall allow a reasonable time for 

submission of the statement and shall specify the date by which it must be received. If 

the statement is not received within the time prescribed, or within the limits of any 

extension of time granted by the Hearing Officer, it need not be considered by the 

Hearing Officer. 

(ix) A verbatim transcript of the hearing will not normally be prepared. A party may, 

solely at its own expense, cause a verbatim transcript to be made. If a verbatim transcript 

is made, the party shall submit two copies to the Hearing Officer not later than 15 days 

after the hearing. The Hearing Officer shall include such transcript in the record.
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(12) Determination of Violations and Assessment of Civil Penalties. (i) Not later than 30 

days following the close of the hearing, the Hearing Officer shall issue a written decision 

on the Notice of Violation, based on the hearing record. This may be extended by the 

Hearing officer if the submissions by the Chief Counsel or the party are voluminous. The 

decision shall address each alleged violation, and may do so collectively. For each 

alleged violation, the decision shall find a violation or no violation and provide a basis for 

the finding. The decision shall set forth the basis for the Hearing Officer’s assessment of 

a civil penalty, or decision not to assess a civil penalty. In determining the amount of the 

civil penalty, the gravity of the violation, the size of the violator’s business, the violator’s 

history of compliance with applicable fuel consumption standards, the actual fuel 

consumption performance related to the applicable standard, the estimated cost to comply

with the regulation and applicable standard, the quantity of vehicles or engines not 

complying, and the effect of the penalty on the violator’s ability to continue in business. 

The assessment of a civil penalty by the Hearing Officer shall be set forth in an 

accompanying final order. The Hearing Officer’s written final order is a final agency

action.

(ii) If the Hearing Officer assesses civil penalties in excess of $1,000,000, the Hearing 

Officer’s decision shall contain a statement advising the party of the right to an 

administrative appeal to the Administrator within a specified period of time. The party is 

advised that failure to submit an appeal within the prescribed time will bar its 

consideration and that failure to appeal on the basis of a particular issue will constitute a 

waiver of that issue in its appeal before the Administrator.

(iii) The filing of a timely and complete appeal to the Administrator of a Hearing 

Officer’s order assessing a civil penalty shall suspend the operation of the Hearing 

Officer’s penalty, which shall no longer be a final agency action. 

(iv) There shall be no administrative appeals of civil penalties assessed by a Hearing 

Officer of less than $1,000,000.

(13) Appeals of civil penalties in excess of $1,000,000. (i) A party may appeal the 

Hearing Officer’s order assessing civil penalties over $1,000,000 to the Administrator 

within 21 days of the date of the issuance of the Hearing Officer’s order.

(ii) The Administrator will review the decision of the Hearing Officer de novo, and may

affirm the decision of the hearing officer and assess a civil penalty, or

(iii) The Administrator may:

(A) Modify a civil penalty;

(B) Rescind the Notice of Violation; or

(C) Remand the case back to the Hearing Officer for new or additional proceedings.

(iv) In the absence of a remand, the decision of the Administrator in an appeal is a final 

agency action.
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(14) Collection of assessed or compromised civil penalties. (i) Payment of a civil 

penalty, whether assessed or compromised, shall be made by check, postal money order, 

or electronic transfer of funds, as provided in instructions by the agency. A payment of 

civil penalties shall not be considered a request for a hearing.

(ii) The party must remit payment of any assessed civil penalty to NHTSA within 30 

days after receipt of the Hearing Officer’s order assessing civil penalties, or, in the case 

of an appeal to the Administrator, within 30 days after receipt of the Administrator’s 

decision on the appeal.

(iii) The party must remit payment of any compromised civil penalty to NHTSA on the 

date and under such terms and conditions as agreed to by the party and NHTSA. Failure 

to pay may result in NHTSA entering a finding of violation by default and assessing a 

civil penalty in the amount proposed in the Notice of Violation without processing the 

violation under the hearing procedures set forth in this part.

(c) Changes in corporate ownership and control. Manufacturers must inform NHTSA 

of corporate relationship changes to ensure that credit accounts are identified correctly 

and credits are assigned and allocated properly.

(1) In general, if two manufacturers merge in any way, they must inform NHTSA how 

they plan to merge their credit accounts. NHTSA will subsequently assess corporate fuel 

consumption and compliance status of the merged fleet instead of the original separate 

fleets.

(2) If a manufacturer divides or divests itself of a portion of its automobile 

manufacturing business, it must inform NHTSA how it plans to divide the manufacturer's 

credit holdings into two or more accounts. NHTSA will subsequently distribute holdings 

as directed by the manufacturer, subject to provision for reasonably anticipated 

compliance obligations.

(3) If a manufacturer is a successor to another manufacturer's business, it must inform 

NHTSA how it plans to allocate credits and resolve liabilities per 49 CFR part 534.
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Greenhouse Gas Emissions Standards and Fuel Efficiency Standards for Mediumand Heavy-Duty Engines and Vehicles: Final Rules

Dated: _______________________

_____________________________________________________

Ray LaHood, Secretary, Department of Transportation
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Greenhouse Gas Emissions Standards and Fuel Efficiency Standards for Mediumand Heavy-Duty Engines and Vehicles: Final Rules

Dated: _______________________

_____________________________________________________

Lisa P. Jackson, Administrator, Environmental Protection Agency