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[0721 FRM Preamble EO12866_GHG+Fuel Eff Stds for Med-Heavy-Duty Engines+Vehicles 2060-

AP61.docx]

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 85, 86, 600, 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 emissions 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 heavyduty engines, pickup trucks and vans. EPA is also finalizing provisions allowing lightduty vehicle manufacturers to use CO2 credits to meet the light-duty vehicle N2O and 

CH4 standards, and a technical amendment to the criteria pollutant emissions 

requirements for certain switch locomotives.

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
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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.

The agencies estimate that the combined standards will reduce CO2 emissions by

approximately 280 million metric tons and save over 500 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.

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) 366-0949. 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

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

A. Does this Action Apply to Me

I. Overview
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A. Introduction

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 Provisions

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
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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

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
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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 from the Greenhouse Gas Emissions 

Perspective

M. Summary of Costs and Benefits from the Fuel Efficiency Perspective

N. 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
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A. EPA

B. NHTSA

List of Subjects

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

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.” 2,3 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. 

 

2

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.

3 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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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;

 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 builds on many years of heavy-duty engine and 

vehicle technology development to achieve what the agencies believe is the greatest 

degree of GHG emission and fuel consumption 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 GHG emissions and fuel consumption 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 

longer-term 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.
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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.

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.4 Heavy-duty trucks5

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 2012-2016.7 It also 

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

 

4 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.

5

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.”

7

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

Standards; Final Rule 75 FR 25323, May 7, 2010.
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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.8 

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

except the scopes differ 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.”

9

 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. NHTSA stated in the NPRM that recreational vehicles are noncommercial, 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,

10 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.

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 these greenhouse gases result in air pollution 

 

8

 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.

9

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).

11 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.
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which may reasonably be anticipated to endanger both 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.11 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 1990.12 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 2007.13 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 heavyduty vehicles in 2007, CO2 emissions represented more than 99 percent of all GHG

emissions (including HFCs).

14

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.

15

 

11 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.

12 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 

13 See Endangerment TSD, Note 11, above, at pp. 180-194.

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

See Note 12, above. 

16 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 
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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.16 

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 

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.17 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 emissions from upstream sources have been conducted. In this 

 

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.

16 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.

17 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).), as 

required by the Endangerment Finding under the CAA. See Section II.
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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. 

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. 18 time frameMandatory 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 

 

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

conformity; see Section V below. 
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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.19 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

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, and no standards that were not 

noticed at the time of this rulemaking will take effect before 2019. Those fuel 

consumption standards that become mandatory in 2017 will remain in effect through at 

least 2019. This further ensures that the 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. 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 by the work of the EPA SmartWay

 

19 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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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. 

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% less NOX and 99% 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 
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incorporates the existing engine-based approach used for criteria pollutant regulations, as 

well as new vehicle-based approaches. 

(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.21

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;22 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)23 that have long governed NHTSA’s setting of fuel 

 

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

22 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.

23 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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17 of

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

are considered under each of these provisions.

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.”

24 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 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 

 

24 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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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); 21 United 

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

technologies, and by providing technical information, financial incentives, and partner 

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.
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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

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).25 

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 complimentary 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 

 

25 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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the regulation of completed vehicles and did not give the agency 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 

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.

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 more 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 in the future. 

(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.

26

 Table I-1 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.

 

26 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-1: 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.27 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. 

 

27 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.28 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 

 

28 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 

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 veh

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

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 em

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 me

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, 

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 

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 

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

depending on GVWR (i.e

 

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

Program: A Government-Industry Research Partnership, 21CT

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

25 of

Figure I-1: Combination Tractor and Trailer Loads29

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 

vehicle 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 

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 

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 

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

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 

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 

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 

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

which is consistent with the 

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 costissions and fuel consumption while operating the 

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

world operation and performance, various characteristics of the 

asurements 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 

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 

emissions and fuel consumption. The 

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

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 

., 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 

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-2 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. 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. The agencies are also creating an allowance for certain 

tractors to be classified as vocational tractors and thus comply using vocational standards, 

while allowing other tractors that perform off-road to be exempted from the vehicle 

standards.

Table I-2: 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 
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27 of

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 model year 2016.

Separately, EPA is also finalizing engine-based N2O and CH4 standards and 

credits 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 the agencies 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 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 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-2, 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 also 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 
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28 of 

the current refrigerant used widely in all these systems has a very high global warming 

potential, EPA is concerned about leakage of refrigerant.31 

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 establishing 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 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 heavy-duty 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 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.32 

 

31 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.

32 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 
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29 of

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 

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 

 

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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30 of 

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).33

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).34 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 

provides 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 

arguing, as the agencies had, that this approach was an effective way to drive technology

development and to appropriately reflect the utility of work vehicles while setting a 

consistent metric measure of vehicle performance..

As we 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. 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 per-vehicle 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. Section II.C 

also discusses the rationale behind the separate targets for diesel and gasoline vehicle 

standards. 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, 

 

33 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).

34 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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31 of

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 curvesin 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. Under the provisions of the ABT program 

in today’s action, EPA and NHTSA have allowed manufacturers to carry forward credits 

and deficits for a set period of time. We are allowing manufacturers of vehicles or 

engines to carry forward a deficit for up to three years when there is less lead time 

available. 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 suggesting that the standards for 

heavy-duty pickups and vans should be made more stringent for gasoline vehicles and 

further 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 

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 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:
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32 of 

 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

 gasoline engine coupled cam phasing

 diesel aftertreatment optimization

 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), because, like 

other vocational vehicles, we have little information on baseline aerodynamic 

performance and opportunities for improvement. However, 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, in 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). Additional flexibilities are also being 

finalized to create further incentives for advanced technology vehicles.

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.
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33 of

(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,35 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

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 

 

35 NHTSA’s final fuel consumption standards will not apply to recreational vehicles, as discussed in 

Section I.
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34 of 

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.36 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. 

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.

 

36 See 49 U.S.C. §§ 567.5 and 568.4
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(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, as finalized for combination tractors, EPA and NHTSA are adopting separate 

standards for the manufacturers of engines used in Class 2b-8 vocational vehicles. 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.

As for the compression ignition engines used in Class 7 and 8 combination 

tractors, we are finalizing an interim alternative engine standard for model years 2014-

2016. 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. Additionally, 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 OBD requirements applicable for these same 

model years.

The agencies received a significant number of comments 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. (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 finalize 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 such as 

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 
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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. 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. As discussed below, 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. 

The agencies are setting standards beginning in the 2014 model year and 

establishing more stringent standards in the 2017 model year. Table I-3 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-3: 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 
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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.

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.37 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 excluded, 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.38 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. 

 

37 See §1036.150 and §1037.150 

38 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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The Institute for Policy Integrity (IPI) commented that the small business 

exclusion proposed in the NPRM was based on the improper framework of whether the 

exclusion 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 exclusion 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 USC 32902(k)(2) includes the authority to 

exclude certain manufacturers if their inclusion would work against these statutory

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 to develop 

the proposal, 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), all led to the determination that the inclusion 

of small businesses would not be appropriate at this time. Therefore, the final rule 

excludes small businesses as proposed. 

Volvo and EMA stated that by excluding 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 exclusion should not apply to market segments 

where a small business has a significant share of a particular HD market. Volvo argued 

that the excluded 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 exclusion. 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 spinoffs 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, and a manufacturer would 

not be considered excluded until EPA and NHTSA have made a formal determination as 

to their status in writing. As the agencies gain more experience with this exclusion, these 

clarifications may be codified in the regulatory text of a future rulemaking.

Volvo further commented that the agencies were adopting an exclusion 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 
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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 IX(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. 

(e) Light-duty Vehicle CH4 and N2O Standards Flexibility 

After finalizing 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 USC 32904) 
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40 of 

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.39 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. 

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. 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 

incentive effectively reduces 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 treating 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

 

39 E85 is a blended fuel consisting of nominally 15 percent gasoline and 85 percent ethanol.
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emissions40 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 

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,41 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 RFS.

The agencies continue to believe that alternative-fueled vehicles, including 

NGVs, provide fuel consumption benefits that should be accounted for in this program. 

However, the agencies do not agree with the commenters’ claim that the NGV incentive 

contained 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 intent for NGVs to be 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, 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). 

 

40 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).

41 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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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. 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 

determination, not on a belief that incentives present in the light-duty rule could not be 

developed for the heavy-duty program if they were not explicitly included in Section 

32902(k).

[NHTSA is drafting language to insert here on the energy security fuel 

benefits that would result from increased incentives for natural gas, but that these 

benefits are outweighed by the need for a harmonized program.]

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 

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 and benefits of the final

GHG and fuel consumption standards. Table I-4 shows estimated lifetime discounted 

program costs (including technological outlays), fuel savings, and benefits for all heavyduty vehicles projected to be sold in model years 2014-2018. 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, such as the economic damages caused by accidents, 

congestion and noise. Note that benefits depend on estimated values for the social cost of 

carbon (SCC), as described in Section VIII.G. 

The costs 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-4: Estimated Lifetime Discounted Costs, Benefits, and Net Benefits for 2014-2018 Model 

Year HD Vehicles assuming the Model Average, 3% Discount Rate SCC Valuea,b (2009 dollars)

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 benefits $2.6

Annualized costs $0.4

Net benefits $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 benefits $3.1

Annualized costs $0.6

Net benefits $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 present 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-5 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-5 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-5: 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-6 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-6 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 fuel savings, 

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.42 The lifetime 

discounted benefits are shown for one of four different SCC values considered by EPA 

and NHTSA. The values in Table I-6 do not include costs associated with new 

technology required to meet the GHG and fuel consumption standards.

Table I-6: 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, 

 

42 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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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.

c Benefits in this table include fuel savings.

Table I-7 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-7 are totals for the five model years throughout their projected lifetime 

and are not discounted. The monetized values shown in Table I-7 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-7

reflect both a 3 percent and a 7 percent discount rate as noted.

Table I-7: 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-8 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-8 are for the industry as a whole and do not account for fuel savings 

associated with the program.

Table I-8: 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-9 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-9: 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.

43

 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 to each other 

in structure and function. For combination tractor and vocational vehicle categories and 

for 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 

other similar vehicles, “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 

 

43 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. 

By restricting trading to within the same vehicle weight categories as EPA’s 

existing criteria pollutant program, we are convinced that the lifetime vehicle 

performance between different vehicles within these defined categories will be similar 

enough for us to be confident the estimated credit calculations will fairly ensure the 

expected fuel consumption and GHG reductions. 

This program 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 the existing criteria pollutant emission provisions. 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 deficit carry-forward provisions for heavy-duty

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 program, is intended to assist the broad goal of harmonizing 

the two agencies’ proposed 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. This provision will allow manufacturers the time needed to incorporate 

technology to achieve GHG reductions and improve fuel economy during the vehicle 

redesign process.
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We have received comments from (Center for Biological Diversity) against the 

need to offer the deficit carry-forward flexibility. (CBD) has stated that allowing 

manufacturers the ability 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 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, beyond ABT, the other primary flexibility provisions in this 

program involve opportunities to generate early credits, advanced technology credits 

(including 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. 

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. 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. 
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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,44

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 

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.45

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 

 

44 49 U.S.C. 32902(h).

45 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.”
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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).46 

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 

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 

 

46 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 

EPA’s Response to Comment document.
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(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 

section 213(a)(3)).47 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’”). Also see 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 

 

47

 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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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 

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) 
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of EISA, which instructs NHTSA to create a fuel efficiency improvement program for 

“commercial medium- and heavy-duty on-highway vehicles and work trucks”49 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 

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 

 

49 “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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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 

vehicles in that subsection or included the same timeline in Subsection (k).50 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.

 

50 “[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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(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.

(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).51 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

 

51 State of Ohio v. U.S. Dept. of Interior, 880 F.2d 432, 439 (D.C. Cir. 1989).
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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 commented that the 

penalties proposed by NHTSA exceeded the authority granted to the agency by Congress, 

and that the fact that Congress did not adopt an entirely new statute for the HD program 

should be interpreted to mean that provisions 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 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. 
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(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 

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,”52 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 

 

52 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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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 

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 frametime 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 frametime 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.
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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 

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 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,
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 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

 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 are delayed 

until 2016 or 2017. They will apply throughout the useful life 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 on-highway vehicle’ as an on-highway

vehicle with GVWR of 10,000 pounds or more.53 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.54 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 

 

53 Codified at 49 U.S.C. 32901(a)(7).

54 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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today cover recreational on-highway vehicles, while NHTSA limited its scope in the 

proposal to not include these vehicles. The NPRM proposed to include all segments of 

the heavy-duty category above, except that NHTSA proposed not to include recreational 

vehicles (RVs), based on an interpretation of the term “commercial medium- and heavyduty on-highway” vehicles. NHTSA stated in the NPRM that recreational vehicles were 

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 heavy-duty on-highway

vehicle” by weight only,55 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 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. 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. 

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. 

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.56

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 applicable vehicle sections. The agencies are establishing standards 

 

55 See above note.

56 Both agencies have authority to develop separate standards for vehicle and engine categories, as 

appropriate. See CAA section 202(a)(1) (authority to establish standards for “any class or classes of new 

motor vehicles or engines” and 49 U.S.C 32902(k)(2) (authority to establish standards for HD vehicles that 

are “appropriate, cost-effective, and technologically feasible” that are designed to achieve the “maximum 

feasible improvement” in fuel efficiency; authority to establish “separate standards for different classes of 

vehicles under this subsection.” NHTSA interprets 49 U.S.C. 32902(k)(2) to include a grant of authority to 

establish engines standards pursuant to the broader statement of authority to establish standards that 

achieve the maximum feasible improvement in fuel efficiency. The agencies did not receive any comments 

questioning this interpretation.
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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 

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 
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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: 

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” 
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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,

57 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. 59 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 

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. 

 

57 33 FR 19703, December 25, 1968.

59 A dromedary is a box, deck or plate mounted behind the cab to carry freight or cargo.
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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 would more appropriately be 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 

claim that a vocational tractor should be classified 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 proposed classification failed to recognize genuine 
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differences between vocational tractors, which typically operate at lower speeds in stopand-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); 

(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. 
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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 

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 
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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 vocational tractors will be regulated as a MHD vocational 

vehicle. Specifically, under the provision being finalized at 1037.630 and NHTSA’s 

regulation 523.2 of today’s rules only the following three types of vocational tractors are 

eligible for reclassification:

(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, 

manufacturers will be required to group vocational tractors into a unique family, separate 

from other combination tractors or vocational vehicles. The provision being adopted in 

40 CFR 1037.630 and 49 CFR Part 535.8 requires the manufacturers to summarize in 

their applications their basis for believing that the vehicles qualify 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. The manufacturer would then have to resubmit its application to certify

the vehicles in question to the tractor standards. 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.

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, that would 

apply in most circumstances. 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 
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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.

60

 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. 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. 

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 

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 

 

60 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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70 of 

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,61 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 

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 

 

61 See 2010 NAS Report, Note 24, Recommendation 2-1.
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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 vehicle 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 customarily tied 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.62 

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 

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 

 

62 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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-- such as sleeper cabs. To respect these differences, the agencies are finalizing separate 

standards for sleeper cabs and day cabs.63 

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 test with the fairing down. 

(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 

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 

 

63 The agencies note, as discussed in the previous section, that some day cabs and sleeper cabs will qualify 

as vocational tractors and will not be subject to the combination tractor standards.
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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.64 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 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 uneconomical. 

 

64 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-Mile65

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 GEM v2.0 which fully reflect the engine improvements due 

to the 2017 MY standards.66 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. 

 

65 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. 

66 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, as detailed in Section III.A.2.

(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 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 used, 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.67 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 

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 for use 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 engnes 

because they are not used in combination tractors.

 

67 See 40 CFR 86.90-2.
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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 II2.69

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.70 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 framein 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 

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 

 

69 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.

70 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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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.

71

 

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, 

because the agencies had said that they were based on the use of existing 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 framesuch as improved 

aftertreatment systems, friction reduction, improved auxiliaries, turbochargers, pistons, 

and other components. These standards will require diesel engine manufacturers to 

 

71 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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78 of 

achieve on average a three percent reduction in fuel consumption and CO2 emissions over 

the baseline 2010 model year levels.

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 frametime frame. 

The NAS study concluded that tractor engine fuel consumption can be reduced by

approximately 15 percent in the 2015 to 2020 time frametime frame and vocational 

engine fuel consumption can be reduced by approximately 10 to 17 percent in the same 

time frametime frame.

73

 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 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 1 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 thus cannot assume that all manufacturers will 

be able to use all technologies. 

 

73 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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79 of

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. 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. 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 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 the analysis 

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.

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. 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 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. We note that we are finalizing these 

standards as proposed based on the assessment that most manufacturers will need to 
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80 of 

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 inTable 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). 

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 the NHTSA’s 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 and noting their intent to comply with standards, with 

noting that once a manufacturer opts into the NHTSA program it must stay in the 

program for all the subsequent optional model years. 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 frametime 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 
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81 of

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 

redesigns.74 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 

frametime 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 will not, however, require 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 re-design.75 

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 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)76 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 

 

74 See 75 FR at 25467-68 for further discussion of the negative cost implications of establishing 

requirements outside of the redesign cycle. 

75 See RIA Chapter 2.4.2.7.

76 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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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 

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, 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 less 

reductions for the engines built in the 2014 and 2015 model years. 
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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 Phasein 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/bhphr)

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 

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.

77

 Manufacturers may opt into the optional OBD phasein through the voluntary NHTSA program, but must opt 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.

 

77 See §1036.150(e).
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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 frametime 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 engines that are up to approximately 25 percent worse than the average baseline 

for other engines. For this group of MHD and HHD diesel engines used 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 used in tractors with 

atypically high baseline CO2 and fuel consumption levels may also, in some instances, 

have a limited line of engines across which to average performance to meet the generallyapplicable 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.78 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. 

 

78 See 75 FR at 74178-74179.
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In comments to the NPRM, Navistar supported the alternative engine standard, 

but asked 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 of these 

MHD and HDD diesel engines were far enough away from the baseline that they could 

not meet the generally-applicable standards with any application of technology that 

would be reasonably cost- effective. The agencies continue to believe that an interim 

alternative standard is needed for these products, and reflects a legitimate differentiation 

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.79 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 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 because not all manufacturers are using the technologies that may be required 

to meet the standards, 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 everyone 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 

 

79See 75 FR at 74178. 
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what we have estimated for the primary program.80 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 frametime 

frame due to higher initial baseline conditions, and which therefore needed alternate 

standards in those model years.81 

The agencies stress that this option is a temporary and limited option being 

implemented to address diverse manufacturer needs associated with complying with this 

first phase of the regulations. As will be codified in 40 CFR 1036.620 and 49 CFR Part 

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 within 

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. 

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 

 

80 The CBI submitted by Navistar demonstrates that in order to meet the 2 percent reduction from the 

individual manufacturer 2011 baselines, technologies such as improved aftertreatment efficiency will be 

required in the 2014 time frame and turbocompounding in the 2016 time frame on tractor engines in order 

to meet the standards. These same technologies will be used by other manufacturers to meet the standards.

81 See 75 FR 25414-25419
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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. 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 be 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. 
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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. 

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.
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89 of

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.82 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, 

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 

economy 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 

 

82 See 2010 NAS Report. Note 24 Recommendation 8-4. Page 190.
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90 of 

agencies received comments from stakeholders and made changes to 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 produced 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

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.
*** E.O. 12866 Review – Revised Version 

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 alternati

for aerodynamic assessment referenced back to a coastdown test procedure, a single 

procedure for determination of 

prescribed method to determine tractor weight reduction. The agencies 

defined model inputs for determining vehicle speed limiter and extended idle reduction 

technology benefits. The other aspects of vehicle performanc

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 wh

(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 in 

emissions and fuel consumption during real world operati

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 represente

move one ton of freight 1,000 miles, or gal/1,000 ton

standards would be represented as grams of CO

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

91 of

Figure II-1: GEM Input Screen

For the aerodynamic assessment, tire rolling resistance, and tractor weight 

eduction, 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 alternati

for aerodynamic assessment referenced back to a coastdown test procedure, a single 

determination of the coefficient of rolling resistance (RRC)

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.

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 

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 CO

standards would be represented as grams of CO2 per ton-mile. The model converts CO

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

For the aerodynamic assessment, tire rolling resistance, and tractor weight 

eduction, 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 

) for tires , and a 

have finalized

defined model inputs for determining vehicle speed limiter and extended idle reduction 

e 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 

at 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 

on. 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 

d as gallons of fuel used to 

mile. EPA's final CO2 vehicle 

mile. The model converts CO2
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92 of 

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 

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.
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(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 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. 

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 
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trucks than of light-duty vehicles. As noted in the NAS report,83 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.

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 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, was 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 

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 

 

83 See 2010 NAS Report, Note 24, Finding 2-4 on page 39.
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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 the comments provided by stakeholders and 

are 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.84

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 

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 of 6.0, then the 

 

84 As explained in Section IV, there are no ABT implications to this change from proposal, since all 

combination tractors are considered to be a single averaging set for ABT purposes.
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manufacturer would assign this tractor to the Class 8 Sleeper Cab High Roof Bin III. The 

manufacturer would then use the Cd value 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 28580:2009.85 The agencies believe the ISO test procedure is 

appropriate to propose for this program because the procedure is the same one used by

NHTSA in its fuel efficiency tire labeling program86 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 vehicle. The results would be expressed as a rolling 

resistance coefficient (RRC) 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.87 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.88 

EPA and NHTSA conducted additional evaluation testing on HD trucks tires used 

for tractors and vocational vehicles. The agencies also received several commenters on 

 

85 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

86 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).

87 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). 

88 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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98 of 

the suitability of low rolling resistance tires for various HD vehicle applications. The 

summary of the agencies finding and a response to issues raised by commenters is 

presented in Section II.D(1)(a). 

(e) Weight Reduction Assessment

In the NPRM, 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 
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6 X 4 axle tractor. In this case, they assert there would be a 1,000 pound weight savings 

from removing an axle. 

As proposed, many of the material substitutions could have been considered as 

innovative technologies 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. 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.89 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.90 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:91 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.92 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.93 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 

 

89 TIAX, LLC. “Assessment of Fuel Economy Technologies for Medium- and Heavy-Duty Vehicles,” 

November 19, 2009. Pages 4-62 through 4-64. 

90 Alcoa. “Improving Sustainability of Transport: Aluminum is Part of the Solution.” 2009

91 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” 

92 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.”

93 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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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 

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, as listed in Table II-9. 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. Aluminum, but 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.

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.94 

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 pursue 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 

 

94 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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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 

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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Weight Reduction Technology Weight Reduction

(lb per tire/wheel)

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 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. 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 GEM. The specified payload in 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 GEM.

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 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 
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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 and 

medium-duty vehicles, and even larger difference between light-duty vehicles and heavyduty 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.95 

(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.96 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.97 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. 

 

95 For more information on the estimated safety effects of this rule, see Chapter 9 of the RIA.

96 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/

97 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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104 of 

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 

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.98 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.

100

 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 

 

98 See Gaines, L., A. Vyas, J.Andreson. “Estimation of Fuel Used by Idling Commercial Trucks,” Page 9 

(2006)

100 See 2010 NAS Report, Note 24, 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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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 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.101 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 

issues102 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 

 

101 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.

102 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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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 

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.103 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). 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/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 limit 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 

requiring that manufacturers providing a soft top feature must design the system so it 

 

103 See 75 FR at page 74223
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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.

104

 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 

the VSL must also be verifiable through on-board diagnostic scanning tools, and must 

 

104 See §1037.640
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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. 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 

vehicle would behave on the road when it follows a driving cycle (vehicle speed versus 
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time). As noted by the 2010 NAS Report,105 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.106 

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

107, 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.

108

 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 

trucks travel at higher speeds. The agencies analyzed the urban and rural interstate truck 

 

105 See 2010 NAS Report, Note 24, Chapters 4 and 8.

106

 This situation does not typically occur for heavy-duty emission control technology designed to control 

criteria pollutants such as PM and NOX.

107 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

108 EPA’s MOVES (Motor Vehicle Emission Simulator). See

http://www.epa.gov/otaq/models/moves/index.htm for additional information.
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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.109 

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.110 Similarly, the agencies are 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 

will be regulated as such in the HD program. Thus, these day cabs will have a drive 

cycle weighting representative of vocational vehicles with more weighting on the 

transient operation and less on the highway speed operation.

 

109 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

110 See Section IV.B.3.b
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111 of

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.111 A detailed discussion of drive 

cycles is included in RIA Chapter 3.112 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

(iii) 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. 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. 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 

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 

 

111 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

112 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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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).113 

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.

114

 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.115 

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 

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 the changes suggested by the commenters will 

 

113 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.

114 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

115 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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113 of

not change the impact on GHG emissions or fuel consumption of the technologies 

included in this phase of the HD program. NHTSA and EPA will evaluate 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, 

drive cycle, and payload; therefore, it makes sense to also specify the drivetrain that 

matches. 
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(v) Engine Input to GEM for Tractors

As proposed, the agencies are defining 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 

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 GEM. The first fuel consumption map would be used in 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 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 for the full 

rulemaking period.118 These inputs are appropriate given the separate regulatory

requirement that Class 7 and 8 combination tractor manufacturers use only certified 

engines. No commenter disagreed with this approach.

(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.119 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 

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 

 

118 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.

119 See NAS Report, Note 24, at page 39.
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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. 

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. 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 

over the defined test procedures. Cummins and Daimler supported this approach and 

stated there already exists sufficient incentives 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
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For 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 

frametime 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.120 

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 

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 

 

120 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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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 used 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 

121.201.121 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.122 The agencies estimate that these small entities comprise less than 0.5 percent 

of the total heavy-duty combination tractors in the United States based on Polk 

Registration Data from 2003 through 2007,123 and therefore that the exemption will have 

a negligible impact on the GHG emissions and fuel consumption improvements from the 

final standards. 

 

121 See §1036.150 and §1037.150 

122 The agencies have identified Ottawa Truck, Inc. and Kalmar Industries USA as two potential small 

tractor manufacturers.

123 M.J. Bradley. Heavy-duty Vehicle Market Analysis. May 2009.
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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). Sections 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 

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 
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119 of

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) Weight-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. Weight-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 weight-based differences in design and in-use operation are the 

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 
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120 of 

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. 125 

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 weight-based attributes avoids the above-mentioned disincentive for the use of 

lightweighting technology by taking vehicle curb weight out of the standards 

determination. 

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 

 

125 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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121 of

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 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.126 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. 

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.

 

126 Memorandum from Anthony Neam and Jeff Cherry, U.S.EPA, to docket EPA-HQ-OAR-2010-0162, 

October 18, 2010.
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122 of 

(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 statutory obligations. Also, for reasons discussed below, separate targets 

were proposed and are being established 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 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 Vans127

 

127 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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124 of 

Figure II-3: EPA CO2 Target Standards and NHTSA Fuel Consumption Target Standards for 

Gasoline HD Pickups and Vans128

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.

 

128 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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125 of

Table II-12: Coefficients for HD Pickup and Van Target Standards 129

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 

 

129 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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126 of 

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) vehicles. An additional two 

percent reduction in GHGs will be achieved by the EPA program from a direct air 

conditioning leakage standard. 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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127 of

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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128 of 

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. 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 

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.
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129 of

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 

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 
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130 of 

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 

manufacturer, after application of the appropriate deterioration factor to each result to 

obtain a full useful life value. See generally 75 FR 25470-25472.
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131 of

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 

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. 
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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 

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,131 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 that make such regulation 

inappropriate at this time. Furthermore, we think it likely that some of the efficiency

improving measures taken by manufacturers in response to the new standards for Class 3 

pickup trucks, such as aerodynamic and accessory improvements, will find their way into 

complete Class 4 vehicle designs as well. 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 

 

131 See above for discussion of applicability of NHTSA’s standards to non-commercial vehicles.
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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. 

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 fuel consumption and GHG 

emissions, the agencies proposed to set standards for the chassis manufacturers of 

vocational vehicles (instead of the body builders) and the engine manufacturers. Chassis 

manufacturers represent a limited number of companies as compared to body

manufacturers, 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 potentially wider array of compliance options 

without needing to make demonstrations through the off-cycle credit provisions – such as 

electrified accessories and weight reduction -- the agencies are finalizing separate 

standards for vocational vehicles that apply to chassis manufacturers and engine 

standards 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. 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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135 of

(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 as a 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.132 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.133 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 trucks134 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.135 

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 

 

132 See 75 FR at 74241

133 A recovery vehicle removes or recovers vehicles that are disabled (broken down).

134 See 2010 NAS Report, Note 24, page 133.

135 See 2010 NAS Report, Note 24, 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 

incorporating the technologies into the final rules. 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.

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. 

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 
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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. 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 will be broadly available by the 2014 model year.136 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 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 

 

136 Bachman, Joseph. Memorandum to the Docket. Heavy-Duty Tire Evaluation. . See Docket #EPA-HQOAR-2010-0162.
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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 

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.

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 
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vocational vehicles, after engines.137 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 heavily 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.138

(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 

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. 

 

137 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.

138 See 75 FR at 74241.
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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. 

(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,139 assessment of the comments received, additional review 

of tire products available, and a more thorough review of tire use in the field.140 In

addition, EPA has conducted tire rolling resistance testing to help inform the final 

rulemaking.141

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 

applications.142 Other suppliers stated that they have made conscious efforts to reduce 

 

139 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.

140 See Docket EPA-HQ-OAR-2010-0162

141 See Docket EPA-HQ-OAR-2010-0162

142 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 
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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 in some cases, 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 RRC 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 tires were included in this testing, 

which was comprised of 88 tires covering various commercial vocational vehicle 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 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 interlaboratory variability. 

 

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.
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142 of 

The test results for 88 commercial vocational vehicle tires (19.5” and 22.5” sizes) 

showed a test average RRC of 7.4 kg/metric ton, with results ranging from 5.4 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 RRC value of 8.1 kg/metric ton.

143

 

The measured average RRC of 7.4 kg/metric ton is thus better than the average value that 

would be needed to meet vocational vehicle standards. Of those eighty-eight tires tested, 

twenty tires had RRC values worse than 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 RRC 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.

144 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 RRC values for tires fitted to 

these Class 4 vehicles typically have a higher RRC values than tires found on commercial 

vocational vehicles because of the smaller diameter wheel size and the ISO testing 

protocol.145 The test data showed the average RRC 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 11.0146 and the range for the LT245/75R16 tires 

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 RRC is 7.7 kg/metric ton and 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 are worse than 8.1 kg/metric ton. 

 

143 See 75 FR at 74244.

144 The RRC values for these applications ranged from 5.4 to 9.2 kg/metric ton.

145 See comments to docket EPA-HQ-OAR-2010-0162-1761; Ford Motor Company

146 The agency notes the highest RRC 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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143 of

The agencies also reviewed the RRC 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 RRC and a value corrected RRC 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 RRC 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 RRC 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 difference between rolling resistance and snow traction.147

(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 

this issue and do not believe that LRR tires as specified in the rules present safety issues. 

As described above, 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 

 

147 Memo to Docket. Winter Tire Traction Evaluation. Docket EPA-HQ-OAR-2010-0162.
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144 of 

are a significant number of tires available that meet or exceed the rolling resistance 

targets for vocational vehicles; both light-truck (with an adjustment factor) 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 agencies 

provided 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 which 

would fitted to a vehicle to meet extreme demands, including those 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 RRC values are obtained, a manufacturer will input the RRC

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 RRC values for vocational vehicles for 2014 and 2017 model years that are 

used to determine the vehicle standards.

Table II-14: Vocational Vehicle – Target RRC 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 

vocational applications had RRC 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 an RRC 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 
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145 of

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 RRC test results for LT tires. The agencies developed an adjustment 

factor dividing the overall vocational test average RRC 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 RRC 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 compliance model that has a pre-defined (or 

fixed) value that is established by the agencies, and that input will change in 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 

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. 
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146 of 

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 

Year148

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).

149

 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 

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 

 

148 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.

149 See 75 FR at 74199.
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reason for excluding them from the vocational vehicle standards. Vocational vehicles, 

such as those used on oil fields and construction sites150, 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. 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 offroad 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 excluding 

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/offroad 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 

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, 

 

150

 Vehicles such as concrete mixers, off-road dump trucks, backhoes and wheel loaders.
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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 for exempting vocational vehicles and 

vocational tractors that primarily travel off-road than proposed. 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.151 As such, any vocational vehicle including vocational tractors 

primarily used off-road or at low speeds must meet the following criteria to be exempted 

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

 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 requirements to exempt any

vocational vehicle that can operate in both on and off-road environments and having 

speed restricted tires rated at 55 mph or below.152 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. Also, as identified by

FMVSS No. 119, speed restricted tires at a rating of 55 mph or less are incapable of 

 

151 XXX Cite needed from NHTSA

152 See 1037.631
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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 Standards 1037.630 and 535.8. For each request, the 

manufacturer will be required to describe why it believes an exemption is warranted and 

address 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?

(b) Heavy-duty Engine Standards for Engines Installed in Vocational Vehicles

EPA is finalizing GHG standards153 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 

 

153 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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150 of 

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 Part 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

(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 

HeavyDuty

Diesel

Medium 

HeavyDuty

Diesel

Heavy 

HeavyDuty

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 
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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.154 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.

155

 

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 

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).

157

 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 

 

154 See generally 75 FR at 74200-201.

155 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.

157 Calculated using the conversion 10,180 g CO2/gallon for diesel fuel. 
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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 standards proposed in the NPRM, 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 

technology, and waiting until 2017 to increase stringency to levels reflecting application 

of this technology. 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.158

 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 

 

158 Calculated using the conversion 10,180 g CO2/gallon for diesel fuel. 
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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.159 

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 

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’ product plan cycles. 

 

159 See generally 75 FR at 74201.
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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.160 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 

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. 

 

160 See 75 FR at 25467-68.
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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.

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 
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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. 

The discussion above 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.

161

 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 2014.162 Unlike 

the majority of engine products in this segment, engine manufacturers have devoted few 

resources to developing technologies for these legacy products reasoning the investment 

would have little value if the engines are to be substantially redesigned or replaced in the 

next five years. Hence while the technologies we have identified to achieve the proposed 

five percent reduction would theoretically work for these legacy products, there is 

inadequate leadtime for manufacturers to complete the pre application development 

needed to add the technology to these engines by 2014. 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.

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 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. 

 

161 See 75 FR at 74202.

162 To be codified at 40 CFR 1036.620,
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157 of

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, 

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 aweighted 

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 

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.163 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 2014-18 model years under consideration 

within the proposal. The agencies therefore proposed fuel consumption and CO2

 

163 EPA’s heavy-duty engine certification database at http://www.epa.gov/otaq/certdata.htm#largeng.
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158 of 

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. 

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 
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159 of

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. 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 be 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. 
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160 of 

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).

(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 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 
*** E.O. 12866 Review – Revised Version 

this rulemaking to evaluate 

number of vehicle simulation tools developed by commercial and government entities. 

The model developed by 

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

address concerns of the peer reviewers and comment

RIA. An example of the GEM input screen is shown in Figure II

EPA and NHTSA have validated 

against a commonly used simulation tool used in industry, GT

vehicle subcategory. Prior to using GT

benchmarked a GT-Drive simulation of the co

Research against the experimental test results from the chassis dynamometer in the same 

manner as done for GEM. Then the 

(LHD, MHD, and HHD) and simulated them us

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 

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

161 of

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 

rpose 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 

d 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.

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 

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

performance. The GEM is similar in concept to a 

number of vehicle simulation tools developed by commercial and government entities. 

and finalized here was designed for the express 

rpose 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 

, including changes made to the model to 

are included in Chapter 4 of the 

GEM simulation of vocational vehicles 

Drive, for each vocational 

Drive as a comparison tool, the agencies first 

mbination tractor tested at Southwest 

Research against the experimental test results from the chassis dynamometer in the same 

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 
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

162 of 

cycles – the California ARB Transient cycle, 55 mph cruise, and 65 mph cruise cycle.164 

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 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 

vehicles is predicated. An example of the GEM input screen is included in Error! 

Reference source not found.Error! Reference source not found.. 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 model inputs will be fixed values predefined 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.

165

 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,166 by European regulations,167 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.

168

 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 (RRC) 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.169

The agencies received many comments on the subject of tire rolling resistance, 

including suggestions for alternative test procedures and compliance issues. Regarding 

 

164 See RIA Chapter 4, Table 4-8.

165

 See http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=44770.

166 75 FR 15893, March 30,2010

167 http://www.energy.ca.gov/2009publications/CEC-600-2009-010/CEC-600-2009-010-SD-REV.PDF

(last accessed May 9, 2011)

168 75 FR 15893, March 30, 2010

169 See generally 75 FR at 74204.
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163 of

whether the agencies should base tire RRC 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 RRC baseline values. RMA also argued that the SAE J1269 multipoint test can be used to accurately predict truck/bus tire RRC 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 

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 RRC 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 RRC 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 
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164 of 

variation.170 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 

661/2009171 and the California Air Resources Board (CARB) through a staff 

recommendation for a California regulation172, 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 

practical to attempt to include the use of the SAE J1269 procedure as an optional way of 

determining RRC values for 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 note the lab-to-lab comparison conducted in the most recent 

EPA tire test program mentioned previously. The agencies reviewed the RRC data from 

the tires that were tested at both the STL and Smithers laboratories to assess interlaboratory and test 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-to-lab variation for the STL and Smithers laboratories would have very

small effect on measured RRC values. Based on the test data, the agencies judge that it is 

 

170 75 FR 15893, March 30, 2010

171 http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2009:200:0001:0024:EN:PDF (last 

accessed May 8, 2011).

172 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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reasonable to implement the HD program with current levels of variability, and allow the 

use of either Smithers or STL laboratories for determining the RRc 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.173 A mean and a standard deviation were calculated for each set of three 

replicate measurements performed on each tire of the 3-tire sample. The coefficient of 

variability (COV) of the RRC 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.174 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).175

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 

 

173 EPA Tire Testing Memo to Docket. Docket EPA-HQ-OAR-2010-0162. July 2011.

174 EPA Tire Testing Memo to Docket. Docket EPA-HQ-OAR-2010-0162. July 2011.

175

 49 CFR 571.109.
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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 RRC for this program.

As discussed above, the agencies are taking the approach of using RRC 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 661/2009 and the California Air Resources Board (CARB) through a 

staff recommendation for a California regulation.

178

 In the NPRM, the agencies proposed 

to use RRC, but for purposes of developing these final rules, the agencies also evaluated

whether to use RRC 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. RRC values generally follow an opposite trend, where tires that are larger 

and/or carry higher loads will generally have numerically lower RRC 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 RRC 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 RRC 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 RRC 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 RRC (as opposed to the RRF) for refuse trucks were found to be 

among the best tested. This finding can be explained by considering that RRC is 

 
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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) RRC value than 

many other types of tires. The amount of load tire can carry (test load) contributes to a 

very low reported RRC, thus confirming low rolling resistance tires meeting the 

standards, as measured by RRC, are available to the industry regardless of segment or 

application.

Based on these considerations, the agencies have decided to use the RRC metric 

for the HD fuel efficiency and GHG emissions program.

(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 include the drive cycle, aerodynamics, vehicle curb 

weight, payload, engine characteristics, and drivetrain for each vehicle type, among 

others.

(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 
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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 

data to distribute vehicle miles traveled by road type.179 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. 

 

179The 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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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. 

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 GEM, coupled with too much steady state operation with very

little variation, is not representative of vocational vehicle operation. In addition, Allison 

said that 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 and require the same technologies be applied to meet the standard. 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 
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type.180 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 

agencies developed the proposed vehicle curb weight inputs based on industry

information developed by ICF.181 The proposed curb weights were 10,300 pounds for the 

LH trucks, 13,950 pounds for the MH trucks, and 29,000 pounds for the HH 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.

182

 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 weight of heavy heavyduty vocational vehicle. 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 

 

180The 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

181 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.

182 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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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. 

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.183 An analogous metric for 

 

183 See NAS Report, Note 24, at page 39.
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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 

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 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 there already exists sufficient incentives 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 
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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. 

(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 vehicle category 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.
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(4) Deferral of Standards for Small Chassis Manufacturing and Small 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 

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.184 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 2007,185 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.186 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 prescribed in Section V below. 

E. Other Standards Provisions

In addition to finalizing CO2 emission standards for heavy-duty vehicles and 

engines, EPA is also finalizing separate standards for N2O and CH4 emissions.187 

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 

 

184 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.

185 M.J. Bradley. Heavy-duty Vehicle Market Analysis. May 2009.

186 The agencies have identified Baytech Corporation, Clean Fuels USA, and BAF Technologies, Inc. as 

three potential small businesses.

187 NHTSA's statutory responsibilities relating to reducing fuel consumption are directly related to reducing 

CO2 emissions, but not to the control of other GHGs.
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GHGs that contribute to global warming, more so than CO2 for the same amount of 

emissions due to their high Global Warming Potential (GWP).188 EPA is finalizing N2O 

and CH4 standards which apply to HD pickup trucks and vans as well as to all heavy-duty 

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 in Section II.E.4 below 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 nonmethane 

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.

 

188 The global warming potentials (GWP) used in this rule are consistent with Intergovernmental Panel on 

Climate Change (IPCC) Fourth Assessment Report (AR4). At this time, the IPCC Second Assessment 

Report (SAR) GWP values are used in the official U.S. greenhouse gas inventory submission to the United 

Nations climate change framework, per that convention's requirements. N2O has a GWP of 298 and CH4

has a GWP of 25 according to the IPCC Fourth Assessment Report.
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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 

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.189 

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

 

189 Value adapted from “Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2007. April 2009.
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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 

standards that would not compromise N2O emissions in future systems as observed in 

current production engine and vehicle testing190 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 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 lean-burn 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 leanburn gasoline vehicles with advanced NOX controls would appropriately control their 

emissions of N2O. 

 

190Memorandum “N2O Data from EPA Heavy-Duty Testing” 
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(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. 

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.191 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. 

 

191 Memorandum “N2O Data from EPA Heavy-Duty Testing”.
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(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 

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.192

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 for exists 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.

 

192 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)
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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.193 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. 

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 

 

193 Engine Manufacturers Association. See Docket EPA-HQ-OAR-2010-0162.
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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 

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.194

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 

 

194 Value adapted from “Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2007. April 2009.
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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.195 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.

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 gasoline or diesel equivalent vehicles, natural gas-fueled vehicles have 

historically produced 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 would 

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% city weighting and 45% highway weighting. 

The level of the standard is approximately two times the average heavy-duty

gasoline and diesel truck and van levels.196 As with N2O, this standard level recognizes 

that manufacturers typically set emissions design targets with a compliance margin of 

approximately 50% 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, 

 

195 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)).

196 Memorandum “CH4 Data from 2010 and 2011 Heavy-Duty Vehicle Certification Tests”.
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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 

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.

197

 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 

 

197 Coordinating Research Council Report: ACES Phase 1 of the Advanced Collaborative Emissions Study, 

2009.
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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.198 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 

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.

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 

 

198 N2O has a GWP of 298 and CH4 has a GWP of 25 according to the IPCC Fourth Assessment Report.
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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 

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.199 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 

 

199 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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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 

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.200

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 

 

200 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 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 

technologies, or curtailing the use of certain technologies.201 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.202 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.203 The most 

commonly used refrigerant in automotive applications – R134a, has a high GWP of 1430.

204

 Due to the high GWP of R134a, a small leakage of the refrigerant has a much greater 

 

201 “Discussions with Vehicle Manufacturers Regarding the Light-duty Vehicle CH4 and N2O Standards,” 

Memorandum from Christopher Lieske to Docket EPA-HQ-OAR-2010-0162, 

202 The United States has submitted a proposal to the Montreal Protocol which, if adopted, would 

phasedown production and consumption of HFCs.

203 The U.S. EPA has reclamation requirements for refrigerants in place under Title VI of the Clean Air 

Act.

204 The global warming potentials used in the NPRM analysis are consistent with Intergovernmental Panel 

on Climate Change (IPCC) Fourth Assessment Report. At this time, the global warming potential values 

from the IPCC Second Assessment Report have been agreed upon as the official U.S. framework for 
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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.205 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 

 

addressing climate change. The global warming potential values from the IPCC Second Assessment 

Report are used in the official U.S. greenhouse gas inventory submission to the climate change framework. 

When inventories are recalculated for the final rule, changes in global warming potential may lead to 

adjustments. 

205 The Minnesota refrigerant leakage data can be found at 

http://www.pca.state.mn.us/climatechange/mobileair.html#leakdata.
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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 

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 demonstated that this level of yearly leakage is feasibile. 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 
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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 

components, fittings, seals, and hoses of the A/C system.207 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 procces 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 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 

heavy-duty 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 leakage-reduction 

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 

 

207 Team 1-Refrigerant Leakage Reduction: Final Report to Sponsors, SAE, 2007.
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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 

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% 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 
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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 

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.

(8) 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. 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 
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to power switch locomotives provided, among other things, that “the engines were 

certified to standards that are numerically lower than the applicable locomotive standards 

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.208 

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.

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. The 

decision on what standard to set is guided by each agency’s statutory requirements, and is 

 

208 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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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 

technology-forcing. See e.g. CAA sections 202 (a)(3)(1)209; 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 

 

209 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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(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 USC 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 

CAFE standards. Instead, NHTSA is directed to consider and meet three factors when 

determining what the maximum feasible standards are – “appropriateness, costeffectiveness, and technological feasibility.” 32902(k)(2). These factors modify

“feasible” in the context of the MD/HD rules beyond a plain meaning of “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.
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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 

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.210 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). 

 

210 See 40 CFR 1036.620
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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 incorporated in this final program 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 

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 
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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.

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 
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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 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 

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 fundamental 

changes in the engine or truck’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 
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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 

heavy-duty engine and truck manufacturers.211 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. 

 

211 RTI International. Heavy-duty Truck Retail Price Equivalent and Indirect Cost Multipliers. July 2010.
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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.212

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 

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,213 TIAX’s assessment of technologies to support the NAS panel 

report,214 EPA’s Heavy-duty Lumped Parameter Model215, 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),216 and the 

technology cost analysis conducted by ICF for EPA.217 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, 

 

212 “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.”

213 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.

214 TIAX, LLC. “Assessment of Fuel Economy Technologies for Medium- and Heavy-Duty Vehicles,” 

November 19, 2009.

215 U.S. EPA. Heavy-duty Lumped Parameter Model.

216 NESCCAF, ICCT, Southwest Research Institute, and TIAX. Reducing Heavy-Duty Long Haul 

Combination Truck Fuel Consumption and CO2 Emissions. October 2009.

217 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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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. 

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,

218 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,219 dual tires with steel wheels on the drive axles, and no 

 

218 MJ Bradley. Heavy-duty Market Analysis. May 2009. Page 10.

219 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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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 

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 0.80.220 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.221 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 

 

220 See TIAX, Note 184 , Page 4-50.

221 See SmartWay, Note 219, above. 
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for the drive tire.222 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 (and also for vocational vehicles).

223

 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 and for vocational trucks 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.

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, which 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

 

222 Ibid.

223 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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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.

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 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 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.

On average, these mass reduction technologies together can reduce weight by

over 400 pounds. A weight reduction of this magnitude 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 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.224 EPA and NHTSA agree with the TIAX assessment of a 6 percent reduction in 

overall fuel consumption reduction.225 

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 

 

224 See the RIARIA Chapter 2 for details.

225 See the 2010 NAS Report, Note 213, above, at 128.
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206 of 

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.226

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.227 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. 

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.228 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 truck 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 other idle reduction technologies.229 

 

226 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. 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.

227 See TIAX, Note 214, above at 4-70.

228 See the 2010 NAS Report, Note 213, page 67.

229 See the 2010 NAS Report, Note 213, page 128.
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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, 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 

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. EPA disagrees with the statement that SCR 

is infeasible and that therefore the engine used as the baseline engine in the agencies’ 

analysis does indeed exist. In fact, several engine families have been certified by EPA 
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208 of 

using SCR technology over the past two years, all of which have met the 0.20 g/bhp-hr 

NOx standard.230 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 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:

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.231

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.

232

 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 

 

230 See 2010 Model Year Engine Certification Data and 2011 Model Year Engine Certification Data files 

located in the Docket EPA-HQ-OAR-2010-0162.

231 TIAX. Assessment of Fuel Economy Technologies for Medium- and Heavy-Duty Vehicles. November 

2009. Page 4-13.

232 TIAX Assessment of Fuel Economy Technologies for Medium and Heavy-duty Vehicles, Report to 

National Academy of Sciences, Nov 19, 2009, Page 4-2.
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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.233 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.234

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.235 Bendix, in their comments to the agencies, 

confirmed that there are engine accessories available that can improve an engine’s fuel 

efficiency. 

 

233 TIAX Assessment of Fuel Economy Technologies for Medium and Heavy-duty Vehicles, Report to 

National Academy of Sciences, Nov 19, 2009, Page 4-13.

234 TIAX, Assessment of Fuel Economy Technologies for Medium- and Heavy-duty Vehicles, Final 

Report, Nov. 19, 2009, pg 4-15

235 TIAX. November 2009. Page 3-5.
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210 of 

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.236 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.237 

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.238 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. The agencies did 

not receive any comments regarding the efficacy of mechanical turbocompound systems. 

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.239 The agencies did not receive any 

comments regarding the efficacy of electric turbocompound systems

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.240 

 

236 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.

237 TIAX Assessment of Fuel Economy Technologies for Medium and Heavy-duty Vehicles, Report to 

National Academy of Sciences, Nov 19, 2009, pg. 4-9

238 NESCCAF/ICCT study (p. 54) and TIAX (2009, pp. 3-5)

239 K. G. Duleep of Energy and Environmental Analysis, R. Kruiswyk, 2008, pp. 212-214, 

NESCCAF/ICCT, 2009, p. 54

240 See 2010 NAS Report, Note 213, page 57.
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However, none of the bottoming cycle or Rankine systems has been demonstrated 

commercially and are currently in only the research stage. 

(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. As highlighted by the 2010 NAS report, the 

agencies do believe that hybrid powertrains have the potential in the longer term to 

provide significant improvements in fuel efficiency and to reduce greenhouse gas 

emissions. . The agencies also are not including drivetrain technologies in the standard 

setting process, as discussed in Section II. 

The agencies evaluated each technology and estimated the most appropriate 

application rate of technology into each tractor subcategory. The next sections describe 

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 exhaust stacks at the B-pillar, which increase 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.241 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.

 

241 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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212 of 

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 (RRC kg/metric ton)

Baseline 7.8 7.8 7.8 7.8 7.8 7.8 7.8 7.8 7.8

Drive Tires (RRC 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

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 tonmile)

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. 
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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 small 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

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. 
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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. 1,258,788 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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215 of

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 (RRC 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 (RRC 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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216 of 

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 truck. 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 EPCA.

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.242 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. 

 

242 TIAX. Assessment of Fuel Economy Technologies for Medium- and Heavy-Duty Vehicles. November 

2009. Page 4-40.
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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 

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. 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.243 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, 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 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.

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 Bin I and Bin II tire packages so the 

2014 MY should afford manufacturers sufficient lead time to install these packages. 

However, tire rolling resistance is only one of 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 

 

243 U.S. Department of Energy. Transportation Energy Data Book, Edition 28-2009. Table 5.7.
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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 LRR 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.

EPA and NHTSA conducted additional evaluation testing on HD trucks tires used 

for tractors and vocational vehicles. The agencies also received several commenters on 

the suitability of low rolling resistance tires for various HD truck applications. The 

summary of the agencies finding and a response to issues raised by commenters is 

presented in Section II.D(1)(a).

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. 

The agencies, upon further analysis, continue to believe that a 400 pound weight 

reduction package is appropriate for tractors in the time frame. 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 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. 

Idle Reduction Technology Application Rate
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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 law, 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 

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.

244

 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

 

244Gaines, L., A. Vyas, J. Anderson. Estimation of Fuel Use by Idling Commercial Trucks. January 2006
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220 of 

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.245 

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 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. 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.

 

245 Gaines, L., A. Vyas, J. Anderson. Estimation of Fuel Use by Idling Commercial Trucks. January 2006

245 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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Table III-4 provides the final application rates of each technology broken down 

by weight class, cab configuration, and roof height.

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 (RRC 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 (RRC 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 truck 

for each subcategory by weighting the individual GEM input parameters included in

Table III-3 by 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.246 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 

 

246 See Section III.A.2.b below explaining the derivation of the engine standards
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tractor standard.247 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. 

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 (RRC kg/metric ton)

6.99 6.99 6.87 6.99 6.99 6.87 6.87 6.87 6.54

Drive Tires (RRC 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.

 

247 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-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-Mile248

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.

 

248 Manufacturers may voluntarily opt-in to the NHTSA fuel consumption program in 2014 or 2015. If a 

manufacturer opts-in, the program becomes mandatory. See Section [add cross reference] below for more 

information about NHTSA’s voluntary opt-in program for MYs 2014 and 2015.
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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

Auxiliary

Power Unit

-- -- -- -- $3,819 $3,819 $3,819

Air 

Conditioning

$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).

(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.249 

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.250 Moreover, the cost of controls is 

rapidly recovered due to the associated fuel savings, as shown in the payback analysis 

included in Table VIII-8 located in Section VIII below. Thus, overall cost per ton of the 

program, considering fuel savings, is negative – fuel savings associated with the rules

 

249 See Section VIII.D below.

250 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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more than offset projected costs by a wide margin. See Table VIII-5 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, 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 

$25,000.251

(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. 

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 

 

251 2010 NAS Report.Page 146. 
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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 turbocompounding, 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 across the industry by model year 2014. 

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 while reflecting the typical heavy-duty 
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engine manufacturer product plan redesign and refresh cycles. Thus, the agencies are 

finalizing to set 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.

252

 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 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 this 

rule 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 

 

252 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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percent improvement in fuel consumption. Conversely, low temperature EGR was found 

to provide only a 1 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 thus 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. 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. 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 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 the analysis 

that we believed best suited tractors engines. 

The agencies selected engine technologies and the estimated fuel reduction 

percentages for setting the standards. For the reasons stated above, the agency believes 

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 
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year included in their report are highly uncertain, though they include Rankine cycle type 

waste heat recovery as applicable sometime between 2016 and 2020.253 The Department 

of Energy, along with industry are both working to develop waste heat recovery systems 

for heavy-duty 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.

254

 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.255 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).256 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 

finalizing provisions 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.

 

253 TIAX Report (2009). Page 4-29.

254 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

255 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

256 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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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. 

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 
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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 value 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 N20 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 value 

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 include a low complexity ICM of 

1.15 and flat-portion of the curve learning is considered applicable to each technology.

Table III-10: Heavy-duty Diesel Engine Component Costs for Combination Tractors (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:
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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 a 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,257 and the associated reductions are highly cost effective, an estimated $20 per 

ton of CO2eq per vehicle.258 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.259 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).

(vi) Temporary Alternative Standard for Certain Engine Families 

As discussed above in Section II.B (1)(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 engines 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

 

257 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.

258 See Tractor CO2 savings and technology costs in Table 7-5 in RIA Chapter 7..

259 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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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. (1) (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 are not finalizing that the option to select an alternative standard 

continues past the 2016 MY. By this time, the engines should have gone through a 

redesign cycle which 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 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 
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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 data260 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 

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.261

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 

 

260 http://www.epa.gov/otaq/certdata.htm

261 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.
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(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.262

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 

control on gasoline engines likewise mostly in place,263 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 

 

262 Memorandum from Anthony Neam and Jeff Cherry, U.S.EPA, to docket EPA-HQ-OAR-2010-0162, 

October 18, 2010.

263 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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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 that it was necessary for feasibility to apply

varying technology penetration levels to different vehicles, 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 standards could miss the opportunity to achieve meaningful and cost-effective early 

reductions not requiring a major product redesign when the largest changes and 

reductions are expected to occur.

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. 264 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: the gradual application of technologies across the fleet (averaging a fifth of 

 

264 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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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 over 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 

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 Section III. B. (1) (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
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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 where turbo-charging and downsizing of gasoline vehicles and hydraulic 

hybrid systems. While turbo-charging and downsizing of gasoline vehicles was a 

principal technology 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 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 
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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. 

 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:
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 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. 

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 
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components for the purposes of improving tailpipe CO2 emissions as a result of 

A/C use.265

(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.266 

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.

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,267 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 

 

265 See RIA Chapter 2.3 for more detailed technology descriptions.

266 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.

267 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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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. 

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 
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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.268,269

(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.270 

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.

 

268 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 

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)

269

 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. 

270 “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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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 

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.
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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 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 

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. 
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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.273 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.

(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 

 

273 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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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.

(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 
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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.274 

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 trucks 

and vans.

 

274 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 

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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(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.

(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 
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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.275

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 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 

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.”276 This means for each one pound reduction in a primary component, up to 

 

275 In the CAFE model, improved accessories refers solely to improved engine cooling. However, EPA has 

included a high efficiency alternator in this category, as well as improvements to the cooling system.

276 “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. 
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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.277 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 

every kilogram of weight saved on a light-duty vehicle when all subsystems are 

redesigned to take into account the initial primary weight savings.278,279 

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. 

 

Accessed on the Internet on May 30, 2009 at: http://www.asp.org/database/custom/Mass%20Compounding%20-%20Final%20Report.pdf

277

 “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

278 “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.

279 “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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 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.

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 2015.280 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 2020.281 Mazda 

plans to reduce vehicle weight by 220 pounds per vehicle or more as models are 

redesigned.282,283 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.280 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 

 

280 “Lighten Up!,” Brooke, L., Evans, H. Automotive Engineering International, Vol. 117, No. 3, March 

2009.

281 “2008/9 Blueprint for Sustainability,” Ford Motor Company. Available at: http:// 

www.ford.com/go/sustainability (last accessed February 8, 2010).

282 “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).

283 “Mazda: Don’t believe hot air being emitted by hybrid hype,” Greimel, H. Automotive News, March 30, 

2009.
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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.284 The resulting analysis showed costs for 5% mass 

reduction on light-duty vehicles to be near zero or cost parity. 

At proposal for heavy-duty vehicles, 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, 2b diesel $95, 3 gasoline $90, 3 diesel 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

 

284 “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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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).286 

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.

(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.

 

286 “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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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 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 

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.
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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 $1,2009 $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.287 The 

reductions are cost effective, estimated at $90 per ton of CO2eq removed in 2030.288 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 in 2030. The cost 

of controls is fully recovered due to the associated fuel 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 

 

287 See Table VI-4.

288 See Table VIII-3.
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authority under 49 U.S.C. 32902(k)(2). Based on the discussion above, NHTSA believes 

these standards are the maximum feasible under EISA.

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 parties 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 

vehicles’ utility. The agencies are adopting a vehicle standard for vocational vehicles for 

the first phase of the program that relies on less extensive addition of technology than for 

the other regulatory categories as well as focusing on the chassis manufacturer as 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 used 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.

(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 
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transmission losses, and the remaining four percent of losses to axles and accessories for 

a medium-duty truck traveling at 30 mph.289 

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.

290

 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 have 

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 truck. 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. 

Weight Reduction: NHTSA and EPA are also not basing any of the final 

standards on use of vehicle weight reduction. Thus, vehicle mass reductions would not 

be input into GEM. The vocational vehicle models are not designed to be applicationspecific. Therefore weight reductions are difficult to quantify. 

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.291 Initially, the agencies considered reflecting transmission choices and 

technology in our standard setting process for both tractors and vocational vehicles (see 

 

289 Argonne National Lab. Evaluation of Fuel Consumption Potential of Medium and Heavy-duty Vehicles 

through Modeling and Simulation. October 2009. Page 89.

290 See 2010 NAS Report, Note 213, page 146.

291 See 2010 NAS Report, Note 213, pp 134 and 137.
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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 

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. 

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.292 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. The use of 

hybrid powertrains to reduce idling is discussed below.

 

292 Gaines, Linda, A. Vyas, J. Anderson (Argonne National Laboratory). Estimation of Fuel Use by Idling 

Commercial Trucks. January 2006.
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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. However, 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, 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 engine 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 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 

EPA believe that employing average values for technology effectiveness estimates is an 
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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. 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 did not receive any significant 

comments suggesting the consideration of other technologies to reduce the fuel 

consumption and CO2 emissions from heavy-duty gasoline engines. 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, NESCCAF293 and EEA294 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 

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 

 

293 Northeast States Center for a Clean Air Future. “Reducing Greenhouse Gas Emissions from Light-Duty 

Motor Vehicles.” September 2004.

294 Energy and Environmental Analysis, Inc. “Technology to Improve the Fuel Economy of Light Duty 

Trucks to 2015.” May 2006.
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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 2010 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 

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. 
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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 6.2.295 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 

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 turbocompound 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

 

295 U.S. EPA. Greenhouse Gas Emissions Standards and Fuel Efficiency Standards for Mediumand Heavy-Duty Engines and Vehicles - EPA Response to Comments Document for Joint 

Rulemaking . EPA-420-R-11-004. Docket EPA-HQ-OAR-2010-0162.
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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.296

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.297 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.298 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.299

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.300

 

296 TIAX, Assessment of Fuel Economy Technologies for Medium- and Heavy-duty Vehicles, Final 

Report, Nov. 19, 2009, pg 4-15

297 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.

298 TIAX Assessment of Fuel Economy Technologies for Medium and Heavy-duty Vehicles, Report to 

National Academy of Sciences, Nov 19, 2009, pg. 4-9

299 See 2010 NAS Report, Note 213, page 56. 

300 TIAX. 2009. Pages 3-5.
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(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.301 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. The agencies are assuming for the final 

rulemaking that the baseline tire rolling resistance is 8.1 kg/metric ton which reflect an 

aggregate improvement of 5 percent in rolling resistance.

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’ 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. 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, 

 

301 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. 

Additional details are available in the RIA Chapter 2. 
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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.

Table III-14: Final Vocational Vehicle Standards and Percent Reductions

Vocational Vehicle

Light 

Heavy-Duty

Medium 

Heavy-Duty

Heavy 

Heavy-Duty

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%
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(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 2030.302 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.303 

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 

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. For 

 

302 See Section VIII.D.

303 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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these reasons, the agencies are not adopting more stringent standards for vocational 

vehicles.

(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 of 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,304 and the associated reductions are highly cost 

effective, an estimated $20 per ton of CO2eq per vehicle.305 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.306 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 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 would not be 

available for production by the 2017 model year. 

 

304 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.

305 See Vocational Vehicle CO2 savings and technology costs in Table 7-4 in RIA Chapter 7.

306 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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(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.

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 heavy-
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duty engine manufacturer product plans have fallen into three year cycles to reflect this 

environment. EPA is finalizing set CO2 emission standards recognizing the opportunity

for technology improvements over this time frame while reflecting the typical heavy-duty 

engine manufacturer product plan cycles. Thus, the agencies are finalizing to establish 

initial standards for the 2014 model year and a more stringent standard for heavy-duty 

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 

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.307 

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. EPA and 

NHTSA are therefore both finalizing provisions described in Section IV to create 

incentives for manufacturers to continue to invest to develop this technology.

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 

 

307 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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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 

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 N20 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 
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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.

Table III-18: Heavy-duty Diesel Engine Component Costs inclusive of Indirect Cost Markups 

(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,308 and the 

associated reductions are highly cost effective, an estimated $20 per ton of CO2eq per 

vehicle.309 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.310 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 considered finalizing diesel engine standards which are more 

stringent reflecting the inclusion of other advanced technologies. 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. 

 

308 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.

309 See RIA Chapter 7, Table 7-4.

310 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 achieve 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 13563.311 The 

primary flexibility provisions for combination tractors and vocational vehicles and the 

engines manufactured for use in these vehicles are incorporated in a program of 

averaging, banking, and trading of credits that EPA and NHTSA developed in association 

with each agency’s respective CO2 and fuel consumption standards (see Section II

above). For HD pickups and vans, the primary flexibility provision is 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 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. 

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 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 

 

311 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 together 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 312 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 

 

312 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, Autocar, and Eaton, 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. 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 larger 

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 

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. In essence, the 

HD pickup truck and van category is one large averaging set that will remain as 

proposed. 
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However, the agencies are maintaining the restrictions against averaging vehicle 

credits with engine credits or between vehicle weight classes or engine subcategories. 

EPA and NHTSA believe that the use of credits beyond these designated averaging sets 

could create an advantage that currently does not exist in the market for large integrated 

manufacturers. For example, a manufacturer that produces both engines and heavy-duty 

highway vehicles could mix credits across engine and vehicle categories to gain an 

advantage over competitors that are not integrated. Limiting credit ABT to within each 

engine averaging set and not allowing it between engines and vehicles will help prevent a 

competitive advantage due solely to the regulatory structure.314 Similarly, large volume 

manufacturers of engines could shift credits between heavy heavy-duty diesel engines 

and light heavy-duty diesel engines to gain an advantage in one subcategory over other 

manufacturers that may not have multiple engine offerings over several regulatory engine 

subcategories. Finally, relating 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 part of the planned follow-up 

rulemaking, 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.

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 the investments and technological 

innovation. The agencies respectfully disagree with CBD and believe this provision has 

 

314 These concerns were not present in the 2012-2016 MY light-duty vehicle rule, where most 

manufacturers offer diverse product lines because there are no separate vehicle and engine standards (with 

differing manufacturers of each) and there is not as much disparity among vehicle useful lives. That rule 

consequently does not restrict CO2 credit trading opportunities between light-duty vehicle sectors.
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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 

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. We do not see how extending the life of credits can assist manufacturers 

in dealing with lead time issues

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. Consistent with past EPA practice, the agencies will address credit life in any 

follow-on rulemaking.315 

 

315 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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281 of

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 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 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 finalizing an approach which aggregates the six proposed engine 

averaging sets into four averaging sets. The four engine averaging sets are light heavyduty (LHD) diesel, medium heavy-duty (MHD) diesel, heavy heavy-duty (HHD) diesel, 

and gasoline or spark ignited engines. 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. The agencies intend to monitor this 

program and may consider revisiting the ABT averaging sets if appropriate in a potential 

future rulemaking (should there be some persuasive reason that there is a difference in 

averaging sets for GHGs and criteria pollutants).

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\\J2756DAAEC001.AA.AD.EPA.GOV\Share\Project\GHG Heavy Duty Truck Rule 

2009\1NPRM\Preamble\Primary Working Documents\P02 Proposed Standards.doc. 

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 
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282 of 

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

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
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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 

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. 316 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 or N2O caps.

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 

 

316 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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284 of 

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. 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 

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 combustion 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 are 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 
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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 

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. 

 Additional flexibilities for engines are discussed later in Section IV(B) which 

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 NPRM 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 
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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. This structure also allows for a straightforward compliance program for 

each sector, with aspects that are independently quantifiable and verifiable. 

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
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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

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 are discussed later 

in Section IV.B which 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 
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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 

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 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 
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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 

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 early 

credit provision as proposed in the NPRM 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 
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manufacturer to obtain early credits for products if they certify their entire subcategory at 

GHG emissions and fuel consumption levels below the standards. 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 compared to their 2012 

model year sales, of SmartWay designated combination tractors 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 model 

year 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.
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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 

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 2013.317 

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.

 

317 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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(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, 

unlike the ABT and early credits discussed above. The eligible technologies were: 

 Hybrid powertrain designs that include energy storage systems

 Rankine cycle engines318

 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. 

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 technolgies 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 

 

318 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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293 of

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 

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 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. Weight saving approaches will not be credited for 

vocational vehicles given the very small percentage improvement that weight reduction 

provides for vocational vehicles. 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 
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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. 

(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. 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 earlycomplying 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 NPRM 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 handling 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 powerplants 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 unusual 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 so infrequent 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 
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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.

(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. 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_A= ___ (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)
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4. Improvement Factor x GEM Fuel Consumption Result_A = ___ 

(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. 

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.
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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 

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 
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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

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 substantial 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 be not 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 
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existing precedence 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 from 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 agencies have revised the duty cycles for complete vehicle and posttransmission 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 flexibility so the options 

available to those manufacturers who choose to certify hybrid engines or vehicles, are not 

contrained 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 used 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 
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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. 

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 is used 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
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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 

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. 

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 to seek under 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
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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 

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, 
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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 

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 
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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. Examples of such 

technologies mentioned in the NPRM include predictive cruise control, gear-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 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.

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.
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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, 

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 

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.

In response to the NPRM, 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 have requested further 

clarification, so the agencies are adopting the full provision as proposed and providing 

further discussion that addresses and clarifies the provision in response to the comments 

solicited and the comments received. 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 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 
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not already been considered, 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. 

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 
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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 

opportunity for comment.319 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 consumption320

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 §1037.611 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 

 

319 See 75 FR 25440. 

320

 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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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 

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.321 

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.322 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 

 

321 See 75 FR 25440. 

322 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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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 

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 fubgibility of innovative technology

credits across service classes and categories. 

The agencies proposed that this optional 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 engines manufacturers to gain credit for redesigning 

aftertreatment systems to reduce N2O emissions. It can be argued that such credits would 

be necessary where the N2O reductions are achieved at the expense of slightly higher CO2
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emissions, since both are greenhouse gas emissions. EPA agrees that it is appropriate to 

consider all greenhouse gas emissions together for such situations where trade-offs 

among the emissions exist due to technology selections. Thus, EPA is adopting a

provision which allows engine manufacturers to generate CO2 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/hphr 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 agency 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.

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. 

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 
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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 

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 
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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, 

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 
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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 

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. 
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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.323 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 

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 

 

323 Memorandum from Don Kopinski, U.S. EPA to docket EPA-HQ-OAR-2010-0162, July 7, 2011.
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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. 

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
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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)324. 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 

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.

 

324 Diesel engines are engine-certified with the option to chassis certification Federally and for California
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(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.326

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.327

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.

An integrated approach with NHTSA has been undertaken to allow manufacturers 

a single point of entry to address certification and compliance. Vehicle manufacturers 

 

326 CAA Section 206(a)(1).

327 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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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.328

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.329 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. 

 

328 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).

329 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. 

(c) Pre-Model Year (or Compliance Plan) Reporting

EPA and NHTSA are requiring that manufacturers submit a compliance plan for 

their entire fleet prior to the certification of any test group in a given model year. 
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Preferably, this compliance plan would be submitted at the manufacturer’s annual 

certification preview meeting. This preview meeting is typically held before the earliest 

date that the model year can begin. The earliest a model year can begin is January 2nd of 

the calendar year prior to the model year. This plan should include the manufacturer’s 

estimate of its attribute-based standard, along with a demonstration of compliance with 

the standard based on projected model-level CO2 emissions and fuel consumption, and 

production estimates. This information will be similar to the information submitted to 

NHTSA and EPA in the pre-model year report required for CAFE compliance for lightduty vehicles. Included in the compliance plan, manufacturers seeking to take advantage 

of credit flexibilities will include these in their compliance demonstration. Similarly, the 

compliance demonstration will need to include a credible plan for addressing deficits 

accrued in prior model years. EPA and NHTSA will review the compliance plan for 

technical viability and conduct a certification preview discussion with the manufacturer. 

The agencies will view the compliance plan as part of the manufacturer’s good faith 

demonstration, but understands that initial projections can vary considerably from the 

reality of final production and emission results. In addition, the compliance plan must be 

approved by the EPA Administrator prior to any certificate of compliance being issued. 

(d) 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, 
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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 

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. 
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(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.

(e) 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 

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 
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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 relevant 

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 mockedup vehicle made from its incomplete vehicle and an added open or 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 

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 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 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.

Finally, we are adopting a related special provision involving chassis-certification 

aimed at simplifying compliance for manufacturers of complete HD pickups and vans 

who sell a relatively small number of engines that are designed for these vehicle 
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products, but that are sold separately to other manufacturers as “loose” engines. 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 to focus their energy on 

improving the GHG and fuel consumption performance of their complete vehicle 

products (including, most likely, significant engine improvements), rather than on 

concurrently calibrating for both vehicle and engine test compliance.

These engines would not be certified to engine-based GHG and fuel consumption 

standards, but instead 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 average 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 for 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 that use the engine. 

Because it is our intent that this loose engine provision be for the purpose of 

simplifying compliance for HD pickup/van manufacturers who sell a relatively small 

number of engines for other applications, we are limiting its use to 10% of the total 

engines 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 allowing complete HD vehicles to use certified 

diesel engines but not certified gasoline engines.

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.
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Together these provisions provide a robust approach to regulating vehicles and 

engines that, though not as straightforward as the complete Class 2b/3 pickups and vans, 

share some characteristics with them that argue for accomplishing more improvement in 

GHG and fuel consumption performance than simply applying the vocational vehicle 

standards, but does not, on the other hand, create a complex and burdensome program 

would force manufacturer to track and design for a plethora of specialized vehicle 

configurations.

 

(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.

(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 
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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 

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 
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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 

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; 
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 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 

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.
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(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.330 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 

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;

 

330 Corresponding to the compliance model year
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 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;

 The final list of vehicles a manufacturer is designating to include in the 

low volume exclusion; 

 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;

 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 (low-
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hour) 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 

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. 

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 
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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) 

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) 
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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 lightheavy-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 is not convinced that engine/aftertreatment wear will not have a 

negative impact on GHG emissions. To address useful life compliance for MHD and 

HHD diesel engines certified to GHG standards, we believe the criteria pollutant 

approach for developing DFs is appropriate. Using CO2 as an example, many of the 

engine deterioration concerns previously identified 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. 
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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 are detailed in their maintenance instructions. Lean-NOX

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, the 

agencies are 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 
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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 data has indicated that it 

may be more appropriate to use a three percent margin to also account for production 

variability between engines. Under this final action, the FEL will always be threepercent 

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 
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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 

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 
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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 

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. Therefore, we 

believe it is appropriate to still require the submission of modal data, however 

manufacturers may submit development data from production-level engine calibrations to 

satisfy this modal data requirement. 

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. 
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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

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. 
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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 

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 
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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. 

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 
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catalyst over another will effectively determine compliance with N2O standards over the 

useful life of the engine. 

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 

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 
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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

 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 are 

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.
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(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.

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 
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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.

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. 
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(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.

(c) 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 2009.331 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 vehicle rule, we 

believe that monitoring of these components and systems for criteria pollutant emissions 

will have an equally beneficial effect on CO2 emissions.332 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 

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 heavyduty 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 them 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 

 

331 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

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

Standards; Final Rule 75 FR 25323,(May 7, 2010.
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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 implementing full OBD with hybrid 

systems. Hybrid manufacturers have indicated that the interaction between hybrid 

systems and OBD compliant engines are not well understood at this time, for example if 

the system shuts down the vehicle at idle (as is common), the 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, engine manufacturers are concerned 

that this would result in high costs due to frequent design changes that could result 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 including criteria for the messages, and 

determining a single set of fault codes that can work for all manufacturers can take a 

substantial amount of time. OBD cannot exist without fault codes to report. Hybrid 

manufacturers have stated that until such time as ‘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 needs to take place. The type of messages needed must first be 

identified once 2013 HDOBD 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 that will likely take at least 2 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 heavy-duty 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 
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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. Existing transmission systems and 

other powertrain components do not exercise the level of control the hybrid will need to 

exercise to effectively reduce GHG emissions and improve fuel consumption 

performance for internal combustion engines.

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 to 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 have to have 

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 to validate. Hardware may also need to be changed to 

accommodate OBD on hybrid systems, in particular, affecting 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 in the millions of dollars) cannot 

support 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. 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. In addition, 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 the 

OBD compliant engines to then be able to immediately implement additional 

requirements may be impractical or infeasible in many instances. Given the phase-in HD 

OBD 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 provides adequate time for development of components and 

protocols necessary for successful integration of complete OBD systems for engines 

equipped with hybrid systems. 
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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 

more fully developed OBD systems will need to be applied to certified engine system 

configurations. The phase in period takes into account that current production systems 

are likely to be smaller in terms of sales volume 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 proprietary system diagnostic 

capability that does not meet OBD requirements, and 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. 

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.333 

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, in lieu of meeting full OBD, meeting EMD 

would result in a cost savings because of the flexibility in scan-tool reporting and 

diagnostic content. Specific EMD requirements will be considered met if they are 

redundant due to the installed engine's fully functioning OBD content.

If a manufacturer certifies an engine hybrid package with CARB OBD, and it's 

diagnostics meet or exceed the requirements for full 2013 OBD, the manufacturer must 

either use their CARB certified package for Federal release or phase in the package and 

certify it with full EPA OBD by MY 2016. In addition, when submitting EMD 

certification to the EPA each year during the interim part of the phase-in, manufacturers 

must also submit a compliance plan for 2016 which describes their progress towards full 

compliance with HD OBD requirements. This plan must include information on:

protocol, software, hardware, and other component development status. If these 

compliance plans are not submitted each year prior to full OBD phase in by a 

manufacturer and full OBD compliance is not demonstrated when required (i.e. 2016 or 

2017 depending on the system) these systems will not be certified. Finally, these systems 

must maintain existing OBD capability for certified engines used in hybrid applications 

with the exception of having liability for failure to meet detection thresholds and in-use 

performance frequency requirements. Hybrid systems must also continue to maintain 

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. 

 

333 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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(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.

(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.
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(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 establishe 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 

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.336 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 

 

336 Corresponding to the compliance model year
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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 

(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 
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mechanical attributes, control algorithms, and driver inputs. The majority of these inputs 

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 
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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.

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 
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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 

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 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 
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manufacturer has robustly designed these features so they can reasonably be expected to 

last the useful life of the vehicle.

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 
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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 

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 which 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 
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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. 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 
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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 

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 
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-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

-LRRD – Low rolling resistance tires – Drive (RRC of 8.2 kg/metric ton or less)

-LRRS – Low rolling resistance tires – Steer (RRC 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.
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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 

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 
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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 

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 
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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 

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.
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The annual submission may be based on coastdown testing conducted consistent 

with the modified protocol detailed in this rulemaking or with an approved alternative 

method. The coastdown testing must be conducted using the Modified Protocol which 

uses SAE J1263 as a basis with some elements of SAEJ2263 (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. Double wide. 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 per 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 Test Track Condition Specifications

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)

Wheel fairings:

Wheels: 24.5 inches. Double wide. 

Tanker Operation Empty

Coastdown Track 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 <.02% or account for the impact of gravity as 

described in SAE J2263 Equation 6.
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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. 
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Figure V-1: Standard Flatbed Trailer Diagram for Special Testing

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.
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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;

 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 106; 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 
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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., 

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;
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 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 

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, NavierStokes 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 
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smaller geometry features, with cell sizes in other areas of the mesh grid starting at 

tweleve millimeters and increasing in size from this value as the distance from the 

tractor-trailer 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 

ration 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 

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 judgement,

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. 
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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 

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 
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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.

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 
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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:

 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)
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 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, highroof day cab and Class 8 high-roof day or sleeper cab tractors and a manufacturer

seeking yaw sweep adjustment must use an approved, alternative aerodyanmic 

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 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 
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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 pick up 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. 

(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.337 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 

 

337 Corresponding to the compliance model year
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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 

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 vocation and 

tractor categories. This approach should reduce the number of vehicle families to an 

amount that is be 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 will retain the NPRM proposal for EOY and final 

reports. 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 establishe 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 
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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

(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 should the technology not be an 

input into GEM, alternative procedures would be needed to determine the value of the 

credit as described in Preamble Section 4.

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 maintenance schedules 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 disposiiton 

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.
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(3) Test Procedures for Measuring Emissions from Heavy-Duty Vehicles

We are finalizing a new part 1066 that would contain a general chassis-based test 

procedures in for measuring emissions from a variety of vehicles, including vehicles over 

14,000 pounds GVWR. However, we are not finalizing application of these procedures 

broadly at this time. The test procedures in 40 CFR part 86 would continue to apply for 

vehicles under 14,000 pounds GVWR. Rather, the final part 1066 procedures would 

apply 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 
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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 

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

Same as Tractors early model year data in Section V.D(4)(a).

(b) Final Reports

Same as Tractors final reports in Section V.D(4)(b).
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(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. 

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. 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.338 

 

338 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 have compliance review and enforcement responsibilities. The same body 

of evidence may establish a violation of EISA and a violation of the CAA. A 

manufacturer that violates both EISA and the CAA will be considered to have committed 

two distinct violations, and may not claim immunity from one simply because it has been 

subject to an enforcement action under another. The agencies will address the concern 

about multiple enforcement actions both when considering initiating an action and when 

stating its penalty demand. 

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 

 

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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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 

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 
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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 

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 rules.

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 byEPA 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. 
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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. 

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)339, 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.

 

339 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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The agencies also used MOVES to estimate emissions and fuel consumption 

impacts for the other alternatives considered and described in Section IX.

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.
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Table VI-1: Estimated Reductions in Engine CO2 Emission Rates340

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%

Table VI-2: Estimated Reductions in Rolling Resistance Coefficient, Aerodynamic Drag Coefficient, 

and Gross Combined Weight

TRUCK TYPE REDUCTION IN 

TIRE ROLLING 

RESISTANCE 

COEFFICIENT 

FROM BASELINE

REDUCTION IN 

AERODYNAMIC 

DRAG COEFFICIENT 

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

10.0% 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.

 

340 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-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 

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. 
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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)

341 and 138,451 kJ/gallon for diesel.342

 

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.

Table VI-4 Model Year 2014 through 2018 Lifetime GHG Reductions and Fuel Savings by Heavyduty 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 

 

341 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.

342 MOVES2004 Energy and Emission Inputs. EPA420-P-05-003, March 2005. 

http://www.epa.gov/otaq/models/ngm/420p05003.pdf
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403 of

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

(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 millenia, 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 
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404 of 

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.

343

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)344 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 

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.345

In May 2010, the NRC published its comprehensive assessment, “Advancing the 

Science of Climate Change.”346 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 

 

343 U.S. EPA (2010) Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990–2007. EPA-430-R-10-

006, Washington, DC.

344 See Endangerment TSD, Note 11 above.

345 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. 

346 National Research Council (NRC) (2010). Advancing the Science of Climate Change. National 

Academy Press. Washington, DC.
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emissions were 7,150 teragrams347 of CO2 equivalent348 (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)349 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 

sources under section 202(a) made up 4.3% of total global GHG emissions in 2005,350

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.

 

347 One teragram (Tg) = 1 million metric tons. 1 metric ton = 1,000 kilograms = 1.102 short tons = 2,205 

pounds.

348 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 using the 100-year time frame values for GWPs established in the IPCC Second Assessment 

Report.

349 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.

350 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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(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.

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 IPCC351 and 

the CCSP reports attributed recent North American warming to elevated GHG 

concentrations. In the CCSP (2008) report,352 the authors find that for North America, 

 

351 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.

352 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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407 of

“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.

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 
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408 of 

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,

353 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 

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 IPCC354 to rise 

between 7.1 and 23 inches (18 and 59 centimeter [cm]), relative to around 1990, in the 

 

353 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.

354 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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409 of

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. 

The CCSP355 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 IPCC356 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, 

 

355 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.

356 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.
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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 CCSP357 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 

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.

 

357 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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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 

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.
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(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,358 Southeast,359 Southwest,360 and Midwest.361 Projected 

climate change would continue to cause loss of sea ice, glacier retreat, permafrost 

thawing, and coastal erosion in Alaska.

Reduced snowpack, earlier spring snowmelt, and increased likelihood of seasonal 

summer droughts are projected in the Northeast, Northwest,362 and Alaska. More severe, 

sustained droughts and water scarcity are projected in the Southeast, Great Plains,363 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.

 

358 Northeast includes West Virginia, Maryland, Delaware, Pennsylvania, New Jersey, New York, 

Connecticut, Rhode Island, Massachusetts, Vermont, New Hampshire, and Maine.

359 Southeast includes Kentucky, Virginia, Arkansas, Tennessee, North Carolina, South Carolina, southeast 

Texas, Louisiana, Mississippi, Alabama, Georgia, and Florida.

360 Southwest includes California, Nevada, Utah, western Colorado, Arizona, New Mexico (except the 

extreme eastern section), and southwest Texas.

361 The Midwest includes Minnesota, Wisconsin, Michigan, Iowa, Illinois, Indiana, Ohio, and Missouri.

362 The Northwest includes Washington, Idaho, western Montana, and Oregon.

363 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
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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 

IPCC364 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.

E. Changes in Atmospheric CO2 Concentrations, Global Mean 

Temperature, Sea Level Rise, and Ocean pH Associated with the 

Program’s GHG Emissions Reductions

EPA examined365 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.

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 

 

364 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.

365 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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414 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),

integrated assessment model366 coupled with the Model for the Assessment of 

Greenhouse Gas Induced Climate Change (MAGICC, version 5.3v2).367 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. 

 

366 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.

367 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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415 of

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, 

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 chapter. 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.

368

 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.369 Details about this modeling 

analysis can be found in the RIA Chapter 8.4.

 

368 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/

369 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 
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416 of 

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 

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.370 Further discussion of EPA’s modeling analysis is found in the RIA, 

Chapter 8.

EPA used the Program CO2SYS,371 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. 

 

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.

370 National Research Council, 2011. Climate Stabilization Targets: Emissions, Concentrations, and 

Impacts over Decades to Millenia. Washington, DC: National Academies Press.

371 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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417 of

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. 

(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.372 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. 

 

372 See NRC 2011, Note 370.373 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-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

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 
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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 PM2.5 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. 

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 on-road 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 2050.373 

 

373 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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420 of 

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 -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

3

56 .1

2050

-

340,656 23.7

-

41,506 18.3

-

9,857 -11.0

-

76,834 2.2

4

43 .1

Table VII-6: Overall Estimated Total Impacts (Upstream Plus Downstream) Impacts on Air Toxics

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, 
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421 of

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 

Assessment for Particulate Matter (ISA).

374

 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.

375

 

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.376 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.

377

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.

378

For ultrafine particles, the ISA concludes that there is suggestive evidence of a 

causal relationship between short-term exposures and cardiovascular effects, such as 

 

374 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.

375 See U.S. EPA, 2009 Final PM ISA, Note 374, at Section 2.3.1.1.

376 See U.S. EPA 2009 Final PM ISA, Note 374, at page 2-12, Sections 7.3.1.1 and 7.3.2.1.

377 See U.S. EPA 2009 Final PM ISA, Note 374, at Section 2.3.2.

378 See U.S. EPA 2009 Final PM ISA, Note 374, at Section 2.3.4, Table 2-6.
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422 of 

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.379

(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.380,381 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 

 

379 See U.S. EPA 2009 Final PM ISA, Note 374, at Section 2.3.5, Table 2-6.

380 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.

381 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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423 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 

benefits of reducing ozone exposure.382 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.383 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

 

382 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

383 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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424 of 

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 

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.384 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.

385

 The ISA concludes that ambient 

concentrations of CO are associated with a number of adverse health effects.386 This 

 

384 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.

385 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

386 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. 
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425 of

section provides a summary of the health effects associated with exposure to ambient 

concentrations of CO.

387

 

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. 

 

387 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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426 of 

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 

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.”388 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.389 

(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. 

 

388 U. S. EPA. 2002 National-Scale Air Toxics Assessment. 

http://www.epa.gov/ttn/atw/nata12002/risksum.html Docket EPA-HQ-OAR-2010-0162

389 U.S. EPA 2009. National-Scale Air Toxics Assessment for 2002. http://www.epa.gov/ttn/atw/nata2002/ 

Docket EPA-HQ-OAR-2010-0162
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427 of

The lifetime for some of the compounds present in diesel exhaust ranges from hours to 

days.390

(i) Diesel Exhaust: Potential Cancer Effects

In EPA’s 2002 Diesel Health Assessment Document (Diesel HAD),391 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.392,393

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 

 

390 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

391 See U.S. EPA (2002) Diesel HAD, Note 390, at pp. 1-1, 1-2.

392 Bhatia, R., Lopipero, P., Smith, A. (1998). Diesel exposure and lung cancer. Epidemiology, 9(1), 84-91. 

Docket EPA-HQ-OAR-2010-0162

393 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
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

428 of 

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.

(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.394,395,396,397 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.”398

(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 

 

394 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

395 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

396 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

397 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

398 See U.S. EPA (2002), Diesel HAD at Note 390, at p. 9-9.
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429 of

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.

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 have 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.399,400,401 

High ambient particle concentrations have also been reported near trucking terminals, 

truck stops, and bus garages.402,403,404 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 

 

399 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

400 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

401 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

402 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

403 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

404 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
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430 of 

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.

405,406,407 EPA states in its IRIS database that data indicate a causal relationship 

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.408,409

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.410,411 The most sensitive noncancer effect observed in humans, based on current 

data, is the depression of the absolute lymphocyte count in blood.412, 413 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.414,415,416,417 EPA’s IRIS program has not yet evaluated these new 

data.

 

405 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.

406 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

407 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.

408 See IARC, Note 406, above.

409 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

410 Aksoy, M. (1989). Hematotoxicity and carcinogenicity of benzene. Environ. Health Perspect. 82: 193-

197. Docket EPA-HQ-OAR-2010-0162.

411 Goldstein, B.D. (1988). Benzene toxicity. Occupational medicine. State of the Art Reviews. 3: 541-554. 

Docket EPA-HQ-OAR-2010-0162.

412 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.

413 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.

414 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. 

415 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.

416 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.
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431 of

(c) 1,3-Butadiene

EPA has characterized 1,3-butadiene as carcinogenic to humans by

inhalation.

418,419

 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.420,421 

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.422

(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.423 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.424, 425 In an analysis of the lymphohematopoietic cancer mortality from 

 

417 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.

418 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.

419 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

420 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

421 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

422 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.

423 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.

424 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.
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432 of 

an extended follow-up of these workers, the National Cancer Institute confirmed an 

association between lymphohematopoietic cancer risk and peak exposures.426 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.427 

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.428 Recently, the IARC re-classified 

formaldehyde as a human carcinogen (Group 1).429 

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.430,431

(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.

432

 Acetaldehyde is reasonably anticipated to be a human 

carcinogen by the U.S. DHHS in the 11th Report on Carcinogens and is classified as 

 

425 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.

426 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.

427 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.

428 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.

429 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

430 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.

431 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.

432 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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433 of

possibly carcinogenic to humans (Group 2B) by the IARC.433,434 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.435 In short-term (4 week) rat studies, 

degeneration of olfactory epithelium was observed at various concentration levels of 

acetaldehyde exposure.

436, 437

 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.438 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.439 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.440 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.441 Lesions to the lungs and upper respiratory tract of 

rats, rabbits, and hamsters have been observed after subchronic exposure to acrolein.442 

 

433 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.

434 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

435 See Integrated Risk Information System File of Acetaldehyde, Note 432, above.

436 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

437 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.

438 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

439 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

440 See U.S. EPA 2003 Toxicological review of acrolein, Note 439, above. 

441 See U.S. EPA 2003 Toxicological review of acrolein, Note 439, at p. 11.

442 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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434 of 

Acute exposure effects in animal studies report bronchial hyper-responsiveness.443 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.444 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.

445

 The IARC determined in 1995 that acrolein 

was not classifiable as to its carcinogenicity in humans.

446

(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.

447448

 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.449 Recent studies 

have found that maternal exposures to PAHs in a population of pregnant women were 

 

443 See U.S. 2003 Toxicological review of acrolein, Note 439, at p. 15. 

444 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.

445 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.

446 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

447 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.

448 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

449 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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435 of

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).450,451 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.452 The draft reassessment completed external peer 

review.453 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.454 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.455 

Naphthalene also causes a number of chronic non-cancer effects in animals, including 

abnormal cell changes and growth in respiratory and nasal tissues.456

(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 

 

450 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.

451 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.

452 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.

453 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.

454 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.

455 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.

456 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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436 of 

ethylbenzene, propionaldehyde, toluene, and xylene. Information regarding the health 

effects of these compounds can be found in EPA’s IRIS database.457

(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.458 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.459

 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.460 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, 

 

457 U.S. EPA Integrated Risk Information System (IRIS) database is available at: www.epa.gov/iris 

458 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-HQ-OAR-2010-

0162.

459 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.

460 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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437 of

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.461

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.462

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.463

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.464 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 

 

461 Holguin, F. (2008) Traffic, outdoor air pollution, and asthma. Immunol Allergy Clinics North Am 28: 

577-588. Docket EPA-HQ-OAR-2010-0162.

462 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.

463 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

464 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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438 of 

individual urban areas report higher levels of traffic-related air pollutants in areas with 

high minority or poor populations.465,466,467

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.468 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. 469,470,471 

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.468 

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.472 Visibility impairment is caused by light scattering and absorption by suspended 

 

465 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

466 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

467 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

468 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

469 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

470 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

471 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

472 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/
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

439 of

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.473

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 and are being 

addressed in the currently ongoing PM NAAQS review. The secondary PM2.5 standards 

serve as a reasonable complement to the Regional Haze Program.

(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 

 

473 See U.S. EPA 2009 Final PM ISA, Note 374. 
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440 of 

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.474

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.475,476,477,478,479 

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

 

474 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.

475 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.

476 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.

477 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.

478 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.

479 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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441 of

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.480 In laboratory experiments, a wide range of tolerance 

to VOCs has been observed.481 Decreases in harvested seed pod weight have been 

reported for the more sensitive plants, and some studies have reported effects on seed 

 

480 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.

481 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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442 of 

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.482

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.483, 484, 485 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 

 

482 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. 

483 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.

484 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.

485 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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443 of

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

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. 
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

444 of 

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. 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 
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

445 of

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. 
*** E.O. 12866 Review – Revised Version – Do Not Cite, Quote, or Release During Review ***

446 of 

(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.486 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.487 According to the National Air Toxic 

Assessment (NATA) for 2005,

488 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.

489 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 

 

486 U.S. Environmental Protection Agency (2007). Control of Hazardous Air Pollutants from Mobile 

Sources; Final Rule. 72 FR 8434, February 26, 2007.

487 U. S. Environmental Protection Agency (2007). Control of Hazardous Air Pollutants from Mobile 

Sources; Final Rule. 72 FR 8434, February 26, 2007. 

488 U. S. EPA. (2011) 2005 National-Scale Air Toxics Assessment. http://www.epa.gov/ttn/atw/nata2005/. 

Docket EPA-HQ-OAR-2010-0162. 

489 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.490

(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 2030.491 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 

 

490 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 

491 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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448 of 

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/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,492 the price increase measures the loss to the buyer.493 

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-30. The costs of the 

program in 2030 are estimated to be approximately $2.6 billion for new engine and truck 

technology, less $20.6 billion in savings realized by trucking operations through fewer 

fuel expenditures (calculated using pre-tax fuel prices). These costs are summarized 

below in Table VIII-29. 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-30, 

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, less fuel 

savings (calculated using pre-tax fuel prices) of $375.3 billion with a 3% discount rate, 

and $166.5 billion with a 7% discount rate. Total net present benefits (in Table VIII-31) 

 

492 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. 

493 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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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.494

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 

 

494 See Memorandum to Docket, “Economy-Wide Impacts of Proposed Heavy-Duty Truck Greenhouse Gas 

Emissions and Fuel Efficiency Standards”, October 8, 2010. 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% to 420% (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.

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 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 semi-truck 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 semitrucks 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.495 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 

 

495 See NAS 2010, Note 213, 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.496

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 

 

496 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. 

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.

Anecdotal information about large truck fleets suggests that, even within a 

company, the office or department responsible for truck purchases is often different from 

that responsible for purchasing fuel. Therefore, the employees who purchase trucks may

have strong incentives to lower their initial capital cost, but not equally strong incentives 

to lower operating costs. 

In addition, the NAS report notes that split incentives can arise between tractor 

and trailer operators.497 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.

 

497 See NAS 2010, Note 213, 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.498 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.

499 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.500 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 

 

498 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.

499 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.

500 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 fuel efficiency for diesel trucks to decline in the 

past decade. Because engine manufacturers would have to invest heavily (both 

financially and with personnel) in emissions reduction technologies, they would not 

invest in fuel efficiency. The costs associated with the decline in fuel efficiency due to 

the emissions regulations were accounted for in that rulemaking. 

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 
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458 of 

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 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 heavyduty 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.

(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.
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459 of

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

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 
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460 of 

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 

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 
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461 of

indirect costs, please refer to the report that has been placed in the docket for this final 

action.501

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 

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 

 

501 RTI International. Heavy-duty Truck Retail Price Equivalent and Indirect Cost Multipliers. July 2010.
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462 of 

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, 

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.
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463 of

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 

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.502 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 

 

502 “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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464 of 

present more detail regarding the 2014-2018 model year trucks in Sections VIII.L and M, 

where we summarize all monetized costs and benefits.

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

2012 $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

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.503 

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.504 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.505 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 

 

503 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.

504 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.

505 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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466 of 

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 

RTI report506 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.507 

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 in the cost estimates, the cost per ton is generally less than $0 

 

506

 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.

507 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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467 of

since the estimated value of fuel savings outweighs the program costs. The results for 

CO2eq costs per ton 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 (2009 dollars)508

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

Table VIII-5: Annual Cost per Metric Ton of CO2eq Reduced – Combination Tractors (2009

dollars)509

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

 

508 The program costs, fuel savings, and CO2eq reductions of the engines installed in vocational vehicles are 

embedded in the vehicle standards and analysis.

509 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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468 of 

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 Sections

VIII.L and M, 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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470 of 

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.

Costs in this section, and summarized in Section VIII.L, are shown from the 

greenhouse gas perspective where fuel savings are treated as negative costs, since the 

primary motivations of this program are U.S. energy security and reductions in GHG 

emissions. From that perspective, the benefits of the program are the external effects, 

and the net effects on truck owners and operators are the costs. EPA prefers to account 

for all costs (positive and negative) directly realized by the end user to accurately present 

the total cost and to differentiate those costs and cost savings from more generally 

realized societal benefits. In Section VIII.M, the agencies also present summary tables 
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471 of

that show the cost and benefit analysis from the fuel efficiency perspective, where the 

purpose of a program to regulate fuel efficiency is primarily to save fuel. From this 

perspective, fuel savings are counted as benefits that occur over the lifetime of the 

vehicle as it consumes less fuel, rather than as negative costs that would be experienced 

either at the time of purchase or over the lifetime of the vehicle. OMB’s Circular A-4, 

which provides guidance to Federal agencies on the development of regulatory analysis, 

makes clear that either approach is acceptable.

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.
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472 of 

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.

Table VIII-11: Payback Period for a 2018 Model Year Combination Tractor (2009$)

Year of 

Ownershi

p

Reduced Fuel Use 

(gallons)b

Fuel SavingsaIncrease

d Cost

Cumulative 

Savings

Gasoline Diesel 3% 

Discoun

t 

7% 

Discoun

t

3% 

Discount 

7% 

Discoun

t

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 
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473 of

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 

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 

Report510, 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,511, distance traveled, type of truck, and commodity.512 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 

 

510 See NAS Report, Note 213

511 American Transportation Research Institute, An Analysis of the Operational Costs of Trucking, 

December 2008 (Docket ID: EPA-HQ-OAR-2010-0162-0007). 

512 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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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%, a 

rebound effect for HD pickup trucks and vans of 10%, and a rebound effect for 

combination tractors of 5%. 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 
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475 of

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.513 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 

aggregate elasticity estimates generally fall in the range of -0.5 to -1.5.514 In other words, 

given an own-price elasticity of -1.5, a 10% 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.515 

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 

 

513 Memo from Energy and Environmental Research Associates, LLC Regarding HDV Rebound Effect, 

dated June 8, 2011.

514 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). 

515 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.
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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 0.59.516 Other reports provide significantly

different cross-price elasticities, ranging from 0.1517 to 2.0.518 

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 

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 

 

516 See 2010 NAS Report, Note 213. 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). 

517 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).

518 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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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.519 

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 

GHG emissions reductions based on mode shifting, given existing limitations of 

infrastructure and other route characteristics in the United States. 520 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.521 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. 522 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 

 

519 Christidis and Leduc, “Longer and Heavier Vehicles for freight transport,” European Commission Joint 

Research Center’s Institute for Prospective Technology Studies, 2009. 

520 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-OAR2010-0162-0011)

521 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).

522 Cambridge Systematics, Inc., 2009. 
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478 of 

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 

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.523 One 

 

523 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.) 
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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.

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% 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 

 

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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480 of 

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, 

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, 
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481 of

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.524 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; 

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 

 

524 See 2010 NAS Report, Note 213, page 152.
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482 of 

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.525 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.526 A trucking fleet 

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 

 

525 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.

526 The average marginal cost difference between sleeper cabs and day cabs in the proposal is nearly 

$6,000.
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483 of

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.527

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. 

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.528 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.529 

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 

 

527 The final rule projects the difference in costs between the HHD and MHD vocational vehicle 

technologies is approximately $30.

528 See NAS Report, Note 213, pp. 150-151

529 See NAS Report, Note 213, page 151.
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484 of 

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 

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 MYvehicle rule; see that rule’s 

preamble for a discussion of application of the SCC.

530

 The SCC Technical Support 

 

530 See 2010 Light-DutyFinal Rule, Note 7, docket ID EPA-HQ-OAR-2009-0472-11424.
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485 of

Document (SCC TSD) provides a complete discussion of the methods used to develop 

these SCC estimates.531

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

emissions in 2010, in 2009 dollars.532,533 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 

 

531 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

532 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).

533 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.
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486 of 

translation of these environmental impacts into economic damages.534 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 

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%.535 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 

 

534

 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.

535 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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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.

Table VIII-15: Monetized CO2 Benefits of Vehicle Program, CO2 Emissionsa(Million 2009$)

YEAR CO2

EMISSIONS 

REDUCTION 

(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. 
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488 of 

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.

536

 

(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.537 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.538,539

 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,540

 

536 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 

“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.

537 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.

538 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

539 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

540 Final Federal Implementation Plans to Reduce Interstate Transport of Fine Particulate Matter and 

Ozone. Signed July 6, 2011. Available at http://epa.gov/airtransport/
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the light-duty 2012-2016 MY vehicle rule,541 and the final Portland Cement National 

Emissions Standards for Hazardous Air Pollutants (NESHAP) RIA.542 To model the 

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).543 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. 

 

541 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

542 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 

Internet at < http://www.epa.gov/ttn/ecas/regdata/RIAs/portlandcementfinalria.pdf >. EPA-HQ-OAR-2009-

0472-0241

543 Information on BenMAP, including downloads of the software, can be found at 

http://www.epa.gov/ttn/ecas/ benmodels.html.
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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:

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:
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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

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)
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Pollutant/Effects Effects Not Included in Analysis - Changes in:

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

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.544 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,

545 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 

 

544 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.

545 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>.
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493 of

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.”546 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.

547

 

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 inTable VIII-18 and Table VIII-19, we 

provide both the mean estimate and the 90% confidence interval. 

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)

 

546 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>.

547 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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494 of 

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)

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).548

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.

 

548 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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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 

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.
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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)

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)
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497 of

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.

(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);
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498 of 

 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 

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.549 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.

 

549 National Research Council (NRC), 2008. Estimating Mortality Risk Reduction and Economic Benefits 

from Controlling Ozone Air Pollution. The National Academies Press: Washington, D.C.
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499 of

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.550,551 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 

“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. 

 

550 National Research Council (NRC). 2002. Estimating the Public Health Benefits of Proposed Air 

Pollution Regulations. The National Academies Press: Washington, D.C.

551 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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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 9.5 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.552 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 1975.553 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 

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.554 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. 

 

552 Source: U.S. Bureau of Economic Analysis, U.S. International Transactions Accounts Data, as shown on 

June 24, 2009.

553 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.

554 This figure is calculated as 0.50 + 0.50*0.9 = 0.50 + 0.45 = 0.95.
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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.

555,556

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 

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.557 The components of the energy security premiums

and their values are discussed in detail in Chapter 9.4 of the RIA.

 

555 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)

556 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)

557 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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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 

are located in countries facing social, economic, and demographic challenges making 

them even more vulnerable to the potential local instability associated with the impacts of 

climate change. For example, in 2010 just over 40% 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% of global supply is from Persian Gulf countries alone. 

Measured in terms of the share of world oil resources or the share of global oil export 

supply, rather than oil production, the concentration in OPEC nations is even larger. As 

another measure of concentration, of the 137 countries/principalities that export either 

crude or product, the top 12 have recently accounted for over 55% of exports.558 Eight of 

 

558 Based on data from the CIA, combining various recent years, 

https://www.cia.gov/library/publications/the-world-factbook/rankorder/2176rank.html.
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these countries are members of OPEC, and a 9th is Russia.559 In a market where even a 

1-2% supply loss raises prices noticeably, and where a 10% supply loss could lead to an 

unprecedented price shock, this regional concentration is of concern. This year, political 

instability has been reflected in large street protests, beginning in Iran, and spreading to 

other countries in North African and the Middle East, including regime change in Egypt 

and insurrection in the oil exporting country of Libya. Historically, the countries of the 

Middle East have been the source of eight of the ten major world oil disruptions560, with 

the 9th originating in Venezuela, an OPEC country, and the 10th being Hurricanes 

Katrina and Rita.

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.” (DOD 2010) 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.”561 

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.”562 

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. This benefit is 

why President Obama has identified this program as a key component for improving 

energy efficiency and putting America on a path to reducing oil imports in the Blueprint 

for a Secure Energy Future.563

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 

 

559 The other three are Norway, Canada, and the EU, an exporter of product.

560 IEA 2011 “IEA Response System for Oil Supply Emergencies.”

561 The Department of the Navy’s Energy Goals (http://www.navy.mil/features/Navy_EnergySecurity.pdf) 

(Last accessed May 31, 2011).

562 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).

563 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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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 

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.
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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.564 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:.

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.

 

564 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-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 

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 
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estimated at the hourly rate recommended for truck operators ($22.36 in 2009 dollars) in 

DOT guidance for valuing time savings.565

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. 

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

 

565 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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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 

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 
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proposed requirements among the targeted F, G, H, J and L load range tires.566 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 

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,567 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 

 

566 “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. 

567 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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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 

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.
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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 rule568

found that reducing the weight of the heavier light trucks (LT > 3,870) had a positive 

overall effect on safety, reducing societal fatalities. 

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 

 

568 “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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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 from the Greenhouse Gas Emissions 

Perspective

As noted in Section VIII.A, the primary motivations of the HD National Program 

are improved energy security and GHG emissions reductions in the United States. From 

that perspective, the benefits of the program are the external effects, and the net effects 

on truck owners and operators are the costs. In this section, the agencies present a 

summary of costs, benefits, and net benefits of the program. Section VIII.M presents the 

benefits and costs from the perspective that the motivation of the program is to improve 

fuel efficiency.

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.569 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. 

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

Technology

Costs

$2,000 $2,200 $2,700 $3,300 $47,400 $24,700

Fuel 

Savings 

(pre-tax)

-$9,600 -$20,600 -$28,000 -$36,500 -$375,300 -$166,500

Monetized 

Annual 

Costs

-$7,600 -$18,400 -$25,300 -$33,200 -$327,900 -$141,800

Note:

a Technology costs and fuel savings for separate truck segments can be found in Section VIII.B.1.

 

569 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-30 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. 

Table VIII-30: 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, Noise

-$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
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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. 

Table VIII-31 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. 
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Table VIII-31: Monetized Net Benefits Associated with the Final Program (Millions, 2009$)

2020 2030 2040 2050 NPV, 3%a NPV, 7%a

Total Annual Costsb

Total Annual 

Costs

-$7,600 -$18,400 -$25,300 -$33,200 -$327,900 -$141,800

Total Annual Benefits at each assumed SCC value c

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 Negative costs represent savings.

c

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.

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-31, 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-32 and Table VIII-33 at 

both 3 percent and 7 percent discount rates, respectively. 
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Table VIII-32: Monetized Costs, 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 -$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

-$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.
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Table VIII-33: Monetized Costs, 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 -$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

-$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.

M. Summary of Costs and Benefits from the Fuel Efficiency 

Perspective

The purpose of a program to regulate fuel efficiency is primarily to save fuel, as 

compared to the purpose of a program to regulate GHG emissions, which is primarily to 

reduce the impact of climate change. Considering costs and benefits from a fuel 

efficiency perspective, technology costs occur when the vehicle is purchased, just as they

do from a GHG emissions perspective, but fuel savings will be counted as benefits that 

occur over the lifetime of the vehicle as it consumes less fuel, rather than as negative 

costs experienced either at the time of purchase or over the lifetime of the vehicle. Table 
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VIII-35Table VIII-34 and Table VIII-35 show similar model year estimates to those 

provided above in Table VIII-32 and Table VIII-33 above in Section VIII.L, but with the 

categories relabeled to illustrate the fuel efficiency perspective. In addition, these figures

reflect only the impacts of the mandatory portions (three model years) of the NHTSA HD 

program.

Table VIII-34: Monetized Costs, 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

Benefits

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 -$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 proposal (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.
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Table VIII-35: Monetized Costs, 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

Benefits

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 -$200 -$200 -$200 -$600

Refueling Savings $30 $50 $50 $130

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) $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 proposal (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.

N. 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, 
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520 of 

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. Therefore, 

we have provided a robust qualitative discussion of the potential employment impacts of 

the Heavy-Duty National Program. 

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.

570

 In this situation, any effects on net 

employment are likely to be transitory as workers change jobs (e.g., 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). 

On the other hand, 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. Schmalansee and Stavins571

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 

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 2011.572 

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 this RIA, this rulemaking is predicted to reduce the amount of 

fuel these vehicles use, and thus affect the petroleum refinery industry. The petroleum 

 

570 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.

571 Ibid.

572 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).
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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.573 As discussed in Chapter 5 of 

this 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.574 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.575 The study predicts an increase in 63,000 jobs in 2020 and 124,000 in 2030, 

as result of higher fuel efficiency for HD vehicles. 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.576

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 

and Shih577 identify three separate ways employment levels may change in the regulated 

industry in response to a new (or more stringent) regulation. First, 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 (“demand 

effect”). Second, costs rise because of increased use of inputs, including labor, in order 

to comply with the new regulatory requirements (“cost effect”). Third, 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”). The “demand effect” is expected to 

 

574 U.S. Census Bureau, 2009 Annual Survey of Manufactures, Published December 3, 2010.

574 U.S. Census Bureau, 2009 Annual Survey of Manufactures, Published December 3, 2010.

575 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.

576 Berck, Peter, and Sandra Hoffman. “Assessing the Employment Impacts of Environmental and Natural 

Resource Policy.” Environmental and Resource Economics 22 (2002): 133-156.

577 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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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 as 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. The related sectors which these rules are 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. 

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 sector-specific 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. 

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 

decrease. The effects of this rulemaking on HD vehicle sales depend on the perceived 
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523 of

desirability of the new vehicles. On one hand, this rulemaking will increase vehicle 

costs; by itself, this effect would reduce vehicle sales. 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 

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.”

578

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. 

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 this 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 require 

additional labor to install the technologies on trucks, thus clearly increasing labor demand 

(the “cost effect”). For “replacement” technologies, the predicted impact on labor 

demand from regulation depends on the change in the amount of labor used to install one 

 

578 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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524 of 

type of technology compared to another. In many cases, the new technologies are 

predicted to be more complex than the existing technologies and are therefore likely to 

require additional labor installation inputs. However, most of the technologies that are 

expected to be used to meet these standards are replacement technologies, therefore 

overall changes in the labor intensity are expected to be relatively small. For example, 

almost all of the engine improvements involve 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. 

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 may have a slightly positive effect on 

employment in this sector. 

(b) Motor Vehicle Parts Manufacturing Sector

Some vehicle parts are made in-house and would be included directly in the 

regulated sector; alternatively, some 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. Because demand for these parts is expected to 

increase, employment effects in this sector are expected to be positive.

(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 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. To the extent that 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.579,580

 

579 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.

580 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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(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.581 

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.582 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 and, as a 

result, could increase the profitability of trucking firms operating in the U.S. In a 

competitive market, the fuel saving 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. 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 

spent by consumers or trucking firm owners, 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

 

581 North American Industry Classification System (NAICS) Code 32411.

582 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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526 of 

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.

(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 may have a slightly positive effect on 

employment, though we cannot definitively say this is the case without quantification. 

Increased expenditures by truck and engine manufacturers are expected to require 

increased labor to build parts, though this effect also depends on any changes in the labor 

intensity of production; increased complexity of technologies may imply increased labor 

inputs. Lower prices for shipping are expected to lead to an increase in demand for truck 

shipping services and, therefore, an increase in employment, 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.

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 

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 

used 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.
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527 of

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.583 The agencies refer to this as the “No Action Alternative” 

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

 

583 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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528 of 

projections for the Light Commercial Trucks, along with the Medium- and Heavy-Duty

Freight Vehicles developed in AEO 2011.584 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 

our preferred alternative, the total AEO2011 baseline cost estimate would be 

approximately equal to the total cost of the preferred case, but 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 2-36 in RIA 

Chapter 2 for a list of all of the technologies, as well as their cost and relative 

 

584 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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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, 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. 

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 2 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, 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 
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not be expanded quickly enough to allow for significant vehicle production volume in the 

time frame of this program. 

(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 frametime 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

system would reduce CO2 emissions by 6 percent at a cost of $8,400 per truck.585 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

 

585 TIAX. 2009. Page 4-20.
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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 $1,743.586

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.587 

(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. 

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 frametime 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.588 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.589 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.590

The combination tractor technology package for Alternative 5 includes the 

preferred alternative technologies, waste heat recovery and Advanced SmartWay

 

586 See RIA Chapter 2, Table 2.35.

587 NAS Report. Page 146.

588 NAS Report. Page 146.

589 NAS Report. Page 146.

590 NAS Report. Page 146.
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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.591 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 frametime 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.592 

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. 

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.

 

591 The Cd improvement of 10 percent for trailer improvements was derived from the TIAX report, Table 4-

26 on page 4-50.

592 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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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

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 $3,287
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TECHNOLOGY COSTS (2009$ MILLIONS)

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.

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% -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 

Preferred

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 $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 $0 -$1,300 -$1,500 -$1,600 -$1,600

Refueling Savings $0 $300 $400 $500 $600
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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.

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 

Preferred

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 $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. 
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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.

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

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 
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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 diversity and 

complexity of the trailer industry, as well as a lack of critical information from the

SmartWay program, industry and other key stakeholders. 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. 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.

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 
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the Secretary of Energy.

593 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.

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.594 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. 

 

593 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). 

594 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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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 

result in slightly less fuel savings and CO2 emissions reductions than those noted in the 

EIS.595 For environmental impacts associated with the final rule, see Sections VI.C and 

VII of this Final Rule.596

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.597 Three of the action alternatives 

 

595 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.

596 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.

597 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. 
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(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.598 

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 

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).

599

 

598 For example, as noted in the FEIS, the combination tractor standard for Alternative 2 was based on the 

removal of the Advanced SmartWay aerodynamic package and weight reduction technologies assumed 

under the Preferred Alternative. The vocational vehicle standard for Alternative 2 was based on the 

removal of low rolling resistance tires and some diesel engine technologies assumed under the Preferred 

Alternative. The pickup truck and van standard for Alternative 2 standard was based on removal of the 5 

percent mass reduction technology, The combination tractor standard for Alternative 4 was based on the 

addition of Rankine waste heat recovery systems and 100 percent application of advanced aerodynamic 

technologies not assumed under the Preferred Alternative. The pickup truck and van standard for 

Alternative 4 was based on the addition of turbocharged, downsized technology to gasoline engines. The 

vocational vehicle standard for Alternative 4 was based on the addition of hybrid powertrains to 6 percent 

of the vehicles.

599 Emissions of diesel particulate matter (DPM) and fine particulate matter (PM2.5) 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 Table 3.5.2-5. This anomaly 
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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.

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 

 

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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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.

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.

NHTSA is also subject to Executive Order 13563 (76 FR 3821, January 21, 2011) 

and 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 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.
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(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.600 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.601 See 40 CFR § 1501.7. On October 29, 

2010, EPA issued its Notice of Availability of the DEIS,602 triggering a public comment 

period. See 40 CFR § 1506.10. The public was invited to submit written comments on 

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.603 

 

600 40 CFR § 1501.6.

601 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).

602 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). 

603 The agency also changed the FEIS as a result of updated information that became available after 

issuance of the DEIS. 
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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.

604

 

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 Council on Environmental Quality (CEQ) regulations implementing 

NEPA, DOT Order 5610.1C, and NHTSA regulations.605 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.

(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 the NAAQS 

every five years and to change the levels of 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 levels established by the 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 

 

604 76 FR 37111 (June 24, 2011).

605 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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permissible levels specified by the NAAQS in order to assess whether the region’s air 

quality is potentially unhealthful.

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 Federal standards 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 

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.
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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 

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 
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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. 

(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. 
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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. 

(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 
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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.

(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.
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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.

(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 35 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 
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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 25,052 hours annually (see Table XII-1:). 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-1: Burden for Reporting and Recordkeeping Requirements

Number of Affected Vehicle Manufacturers 34

Annual Labor Hours for Each Manufacturer to Prepare and Submit 

Required Information

Varies 

Total Annual Information Collection Burden 35.804 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 

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 an Initial Regulatory Flexibility Analysis for 

this action because we are certifying that these rules would not have a significant 

economic impact on a substantial number of small entities. 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 
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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 

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 
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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 $134 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. 

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 $100 or more for the private sector in any one year. 

The agencies believe that the program represents the least costly, most cost-effective 

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 XI-3 presents the rule-related benefits, 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 
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554 of 

(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. 

Table XI-3: Estimated Lifetime and Annualized Discounted Costs, Benefits, and Net Benefits for 

2014-2018 Model Year HD Vehicles assuming the $22/ton SCC Valuea,b (billions 2009 dollars)

Costs Benefits Net Benefits

Lifetime Present Valuec,d– 3% Discount Rate $8.1 $57 $49

Annualized Valuec,e– 3% Discount Rate $0.4 $2.6 $2.2

Lifetime Present Valuec,d– 7% Discount Rate $8.1 $41 $33

Annualized Valuec,e– 7% Discount Rate $0.6 $3.1 $2.5

Notes:

a Although the agencies estimated the benefits associated with four different values of a one ton CO2

reduction (SCC: $5, $22, $36, $66), for the purposes of this overview presentation of estimated 

costs and benefits we are showing the benefits associated with the marginal value deemed to be 

central by the interagency working group on this topic: $22 per ton of CO2, in 2008 dollars and 

2010 emissions and fuel consumption. As noted in Section VIII.G, SCC increases over time.

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.G for more detail.

c Discounted values presented in this table are based on an underlying series 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 this preamble.

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

over time is worth now (in year 2008 dollar terms), discounting future values to the present.

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.

(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 
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555 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.

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.

606

 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 

 

606 See Endangerment TSD, Note 10, above.
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556 of 

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 

(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.H.

(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. 
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557 of

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.

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.

607

 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.608 

In addition, the U.S. Climate Change Science Program stated as one of its conclusions: 

 

607 ICCT. ICCT Evaluation of Vehicle Simulation Tools. 2009. 

608 See Endangerment TSD, Note 10, above.
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558 of 

“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

impacted by climate change.” 609 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 authorizes standards for emissions of pollutants from new motor vehicles 

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.

 

609 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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559 of

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, 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 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, Incorporation by reference, 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.

49 CFR Parts 523, 534, and 535

Fuel Efficiency