*** E.O. 12866 Review – DRAFT 05-29-15 – Do Not Cite, Quote or Release During Review ***

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 85, 86, 1036, 1037, 1042, 1043, 1065, 1066, and 1068

DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration 

49 CFR Parts 523, 534, and 535

[EPA–HQ–OAR–2014–0827; NHTSA- 2014-0132; FRL-9927-21-OAR]

RIN 2060-AS16; RIN 2127-AL52

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

Engines and Vehicles - Phase 2

AGENCY: Environmental Protection Agency (EPA) and National Highway Traffic Safety

Administration (NHTSA), DOT.

ACTION: Proposed Rules.

__________________________________________________________________

SUMMARY:

EPA and NHTSA, on behalf of the Department of Transportation, are each proposing rules to 

establish a comprehensive Phase 2 Heavy-Duty (HD) National Program that will reduce 

greenhouse gas (GHG) emissions and fuel consumption for new on-road heavy-duty vehicles. 

This technology-advancing program would phase in over the long-term, beginning in the 2018 

model year and culminating in standards for model year 2027, responding to the President’s 

directive on February 18, 2014, to develop new standards that will take us well into the next 

decade. NHTSA’s proposed fuel consumption standards and EPA’s proposed carbon dioxide 

(CO2) emission standards are tailored to each of four regulatory categories of heavy-duty 

vehicles: (1) Combination Tractors; (2) Trailers used in combination with those tractors; (3) 

Heavy-duty Pickup Trucks and Vans; and (4) Vocational Vehicles. The proposal also includes 

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

Certain proposed requirements for control of GHG emissions are exclusive to EPA programs. 

These include EPA’s proposed hydrofluorocarbon standards to control leakage from air 

conditioning systems in vocational vehicles, and EPA’s proposed nitrous oxide (N2O) and 

methane (CH4) standards for heavy-duty engines. Additionally, NHTSA is addressing 

misalignment in the Phase 1 standards between EPA and NHTSA to ensure there are no 

difference in compliance standards between the agencies. In an effort to promote efficiency, the 

agencies are also proposing to amend their rules to modify reporting requirements, such as the 

method by which manufacturers submit pre-model, mid-model, and supplemental reports. 

EPA’s proposed HD Phase 2 GHG emission standards are authorized under the Clean Air Act 

and NHTSA’s proposed HD Phase 2 fuel consumption standards authorized under the Energy
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Independence and Security Act of 2007. These standards would begin with model year 2018 for 

trailers under EPA standards and 2021 for all of the other heavy-duty vehicle and engine

categories. The agencies estimate that the combined standards would reduce CO2 emissions by

approximately 1 billion metric tons and save 1.8 billion barrels of oil over the life of vehicles and 

engines sold during the Phase 2 program, providing over $200 billion in net societal benefits. As 

noted, the proposal also includes certain EPA-specific provisions relating to control of emissions 

of pollutants other than GHGs. EPA is seeking comment on non-GHG emission standards 

relating to the use of auxiliary power units installed in tractors. In addition, EPA is proposing to 

clarify the classification of natural gas engines and other gaseous-fueled heavy-duty engines, and 

is proposing closed crankcase standards for emissions of all pollutants from natural gas heavyduty engines. EPA is also proposing technical amendments to EPA rules that apply to emissions 

of non-GHG pollutants from light-duty motor vehicles, marine diesel engines, and other nonroad 

engines and equipment. Finally, EPA is proposing to require that rebuilt engines installed in new 

incomplete vehicles meet the emission standards applicable in the year of assembly, including all 

applicable standards for criteria pollutants.

DATES: EPA and NHTSA will jointly hold two public hearings on the following dates:

July 15, 2015 in Los Angeles, California and July 22, 2015 in Chicago, Illinois. 

See the SUPPLEMENTARY INFORMATION section on “Public Participation” for more 

information about the public hearings.

Comments on all aspects of this proposal must be received on or before [insert date 60 days

after publication IN THE FEDERAL REGISTER]. Under the Paperwork Reduction Act

(PRA), comments on the information collection provisions are best assured of consideration if

the Office of Management and Budget (OMB) receives a copy of your comments on or before 

[Insert date 30 days after publication IN THE FEDERAL REGISTER].

ADDRESSES:

Submit your comments, identified by Docket ID No. EPA–HQ–OAR–2014-0827 (for EPA’s 

docket) and NHTSA-2014-0132 (for NHTSA’s docket) by one of the following methods:

• Online: www.regulations.gov: Follow the on-line instructions for submitting comments.

• Email: a-and-r-docket@epa.gov.

• Mail:

EPA: Air and Radiation Docket and Information Center, Environmental Protection 

Agency, Mail code: 28221T, 1200 Pennsylvania Ave., NW., Washington, DC 20460. 

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.

• Hand Delivery: 

EPA: EPA Docket Center, EPA WJC West Building, Room 3334, 1301 Constitution Ave., 

NW., Washington, DC 20460. Such deliveries are only accepted during the Docket’s 

normal hours of operation, and special arrangements should be made for deliveries of boxed 

information. 
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NHTSA: West Building, Ground Floor, Rm. W12–140, 1200 New Jersey Avenue SE, 

Washington, DC 20590, between 9 a.m. and 4 p.m. Eastern Time, Monday through Friday, 

except Federal Holidays.

Instructions: EPA and NHTSA have established dockets for this action under Direct your 

comments to Docket ID No. EPA–HQ–OAR–2014-0827 and/or NHTSA-2014-0132, 

respectively. See the SUPPLEMENTARY INFORMATION section on “Public Participation” 

for more information about submitting written comments.

Docket: 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: Air and Radiation Docket and Information Center, EPA Docket Center, EPA/DC, 

EPA WJC 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 telephone number for the docket management facility is (202) 366-9324. 

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:

EPA: For hearing information or to register, please contact: JoNell Iffland, Office of 

Transportation and Air Quality, Assessment and Standards Division (ASD), Environmental 

Protection Agency, 2000 Traverwood Drive, Ann Arbor MI 48105; Telephone number: (734) 

214-4454; Fax number: (734) 214-4816; E-mail address: iffland.jonell@epa.gov. For all other 

information related to the rule, please contact: Tad Wysor, Office of Transportation and Air 

Quality, Assessment and Standards Division (ASD), Environmental Protection Agency, 2000 

Traverwood Drive, Ann Arbor, MI 48105; telephone number: (734) 214-4332; email address:

wysor.tad@epa.gov.

NHTSA: Ryan Hagen or Analiese Marchesseault, Office of Chief Counsel, National Highway

Traffic Safety Administration, 1200 New Jersey Avenue, SE, Washington, DC 20590. 

Telephone: (202) 366-2992; ryan.hagen@dot.gov or analiese.marchesseault@dot.gov.

SUPPLEMENTARY INFORMATION: 
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A. Does this Action Apply to Me?

This proposed action would affect companies that manufacture, sell, or import into the United 

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

tractors, all types of buses, vocational vehicles including municipal, commercial, recreational 

vehicles, and commercial trailers as well as 3⁄4-ton and 1-ton pickup trucks and vans. The heavyduty 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 standards and corporate average fuel economy standards issued 

for light-duty model year 2017-2025 vehicles. Proposed regulated categories and entities include 

the following: 

Category NAICS CodeaExamples of Potentially Affected Entities

Industry 336111 Motor Vehicle Manufacturers, Engine 

Manufacturers, Truck Manufacturers, Truck 

Trailer Manufacturers

336112

333618

336120

336212

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.

B. Public Participation

EPA and NHTSA request comment on all aspects of this joint proposed rule. This 

section describes how you can participate in this process.
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(1) How Do I Prepare and Submit Comments?

In this joint proposal, there are many issues common to both EPA’s and NHTSA’s 

proposals. For the convenience of all parties, comments submitted to the EPA docket will be 

considered comments submitted to the NHTSA docket, and vice versa. An exception is that 

comments submitted to the NHTSA docket on NHTSA’s Draft Environmental Impact Statement 

(EIS) will not be considered submitted to the EPA docket. Therefore, the public only needs to 

submit comments to either one of the two agency dockets, although they may submit comments 

to both if they so choose. Comments that are submitted for consideration by one agency should 

be identified as such, and comments that are submitted for consideration by both agencies should 

be identified as such. Absent such identification, each agency will exercise its best judgment to 

determine whether a comment is submitted on its proposal. 

Further instructions for submitting comments to either EPA or NHTSA docket are 

described below.

EPA: Direct your comments to Docket ID No EPA–HQ–OAR–2014-0827. EPA’s 

policy is that all comments received will be included in the public docket without change and 

may be made available online at www.regulations.gov, including any personal information 

provided, unless the comment includes information claimed to be Confidential Business 

Information (CBI) or other information whose disclosure is restricted by statute. Do not submit 

information that you consider to be CBI or otherwise protected through www.regulations.gov or 

e-mail. The www.regulations.gov web site is an “anonymous access” system, which means EPA 

will not know your identity or contact information unless you provide it in the body of your 

comment. If you send an e-mail comment directly to EPA without going through 

www.regulations.gov your e-mail address will be automatically captured and included as part of 

the comment that is placed in the public docket and made available on the Internet. If you 

submit an electronic comment, EPA recommends that you include your name and other contact 

information in the body of your comment and with any disk or CD–ROM you submit. If EPA 

cannot read your comment due to technical difficulties and cannot contact you for clarification, 

EPA may not be able to consider your comment. Electronic files should avoid the use of special 

characters, any form of encryption, and be free of any defects or viruses. For additional 

information about EPA’s public docket visit the EPA Docket Center homepage at http:// 

www.epa.gov/epahome/dockets.htm. 

NHTSA: Your comments must be written and in English. To ensure that your comments 

are correctly filed in the Docket, please include the Docket number NHTSA-2014-0132 in your 

comments. Your comments must not be more than 15 pages long.1 NHTSA established this 

limit to encourage you to write your primary comments in a concise fashion. However, you may

attach necessary additional documents to your comments, and there is no limit on the length of 

the attachments. If you are submitting comments electronically as a PDF (Adobe) file, we ask 

that the documents submitted be scanned using the Optical Character Recognition (OCR) 

 

1

See 49 CFR 553.21.
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process, thus allowing the agencies to search and copy certain portions of your submissions.2 

Please note that pursuant to the Data Quality Act, in order for the substantive data to be relied 

upon and used by the agency, it must meet the information quality standards set forth in the 

OMB and Department of Transportation (DOT) Data Quality Act guidelines. Accordingly, we 

encourage you to consult the guidelines in preparing your comments. OMB’s guidelines may be 

accessed at http://www.whitehouse.gov/omb/fedreg/reproducible.html. DOT’s guidelines may be 

accessed at http://www.dot.gov/dataquality.htm.

(2) Tips for Preparing Your Comments

When submitting comments, please remember to:

• Identify the rulemaking by docket number and other identifying information 

(subject heading, Federal Register date and page number).

• Explain why you agree or disagree, suggest alternatives, and substitute language 

for your requested changes.

• Describe any assumptions and provide any technical information and/or data that 

you used.

• If you estimate potential costs or burdens, explain how you arrived at your 

estimate in sufficient detail to allow for it to be reproduced.

• Provide specific examples to illustrate your concerns, and suggest alternatives

• Explain your views as clearly as possible, avoiding the use of profanity or 

personal threats.

• Make sure to submit your comments by the comment period deadline identified in 

the DATES section above.

(3) How Can I Be Sure That My Comments Were Received?

NHTSA: If you submit your comments by mail and wish Docket Management to notify

you upon its receipt of your comments, enclose a self-addressed, stamped postcard in the 

envelope containing your comments. Upon receiving your comments, Docket Management will 

return the postcard by mail.

(4) How Do I Submit Confidential Business Information?

Any confidential business information (CBI) submitted to one of the agencies will also be 

available to the other agency. However, as with all public comments, any CBI information only 

needs to be submitted to either one of the agencies’ dockets and it will be available to the other. 

Following are specific instructions for submitting CBI to either agency. If you have any 

questions about CBI or the procedures for claiming CBI, please consult the persons identified in 

the FOR FURTHER INFORMATION CONTACT section.

 

2 Optical character recognition (OCR) is the process of converting an image of text, such as a scanned paper 

document or electronic fax file, into computer-editable text.
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EPA: Do not submit CBI to EPA through www.regulations.gov or e-mail. Clearly mark 

the part or all of the information that you claim to be CBI. For CBI information in a disk or CD 

ROM that you mail to EPA, mark the outside of the disk or CD ROM as CBI and then identify

electronically within the disk or CD ROM the specific information that is claimed as CBI. 

Information not marked as CBI will be included in the public docket without prior notice. In 

addition to one complete version of the comment that includes information claimed as CBI, a 

copy of the comment that does not contain the information claimed as CBI must be submitted for 

inclusion in the public docket. Information so marked will not be disclosed except in accordance 

with procedures set forth in 40 CFR Part 2.

NHTSA: If you wish to submit any information under a claim of confidentiality, you 

should submit three copies of your complete submission, including the information you claim to 

be confidential business information, to the Chief Counsel, NHTSA, at the address given above 

under FOR FURTHER INFORMATION CONTACT. When you send a comment containing 

confidential business information, you should include a cover letter setting forth the information 

specified in our confidential business information regulation.3

In addition, you should submit a copy from which you have deleted the claimed 

confidential business information to the Docket by one of the methods set forth above.

(5) How Can I Read the Comments Submitted By Other People?

You may read the materials placed in the docket for this document (e.g., the comments 

submitted in response to this document by other interested persons) at any time by going to 

http://www.regulations.gov. Follow the online instructions for accessing the dockets. You may

also read the materials at the EPA Docket Center or NHTSA Docket Management Facility by

going to the street addresses given above under ADDRESSES. 

(6) How Do I Participate in the Public Hearings?

EPA and NHTSA will jointly host two public hearings on the dates and locations 

described in the DATES section above. The agencies will issue further information on the 

public hearings in a separate Federal Register Notice. At all hearings, both agencies will accept 

comments on the rulemaking, and NHTSA will also accept comments on the EIS.

If you would like to present testimony at the public hearings, we ask that you notify EPA 

and NHTSA contact persons listed in the FOR FURTHER INFORMATION CONTACT

section at least ten days before the hearing. Once EPA and NHTSA learn how many people have 

registered to speak at the public hearing, we will allocate an appropriate amount of time to each 

participant. For planning purposes, each speaker should anticipate speaking for approximately

ten minutes, although we may need to adjust the time for each speaker if there is a large turnout. 

 
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We suggest that you bring copies of your statement or other material for EPA and NHTSA 

panels. It would also be helpful if you send us a copy of your statement or other materials before 

the hearing. To accommodate as many speakers as possible, we prefer that speakers not use 

technological aids (e.g., audio-visuals, computer slideshows). However, if you plan to do so, 

you must notify the contact persons in the FOR FURTHER INFORMATION CONTACT

section above. You also must make arrangements to provide your presentation or any other aids 

to EPA and NHTSA in advance of the hearing in order to facilitate set-up. In addition, we will 

reserve a block of time for anyone else in the audience who wants to give testimony. The 

agencies will assume that comments made at the hearings are directed to the NPRM unless 

commenters specifically reference NHTSA’s EIS in oral or written testimony.

The hearing will be held at a site accessible to individuals with disabilities. Individuals 

who require accommodations such as sign language interpreters should contact the persons listed 

under FOR FURTHER INFORMATION CONTACT section above no later than ten days 

before the date of the hearing.

EPA and NHTSA will conduct the hearing informally, and technical rules of evidence 

will not apply. We will arrange for a written transcript of the hearing and keep the official 

record of the hearing open for 30 days to allow you to submit supplementary information. You 

may make arrangements for copies of the transcript directly with the court reporter.

C. Did EPA Conduct a Peer Review before Issuing this Notice?

This regulatory action is supported by influential scientific information. Therefore, EPA 

conducted a peer review consistent with OMB’s Final Information Quality Bulletin for Peer 

Review. As described in Section II.C.3, a peer review of updates to the vehicle simulation model 

(GEM) for the proposed Phase 2 standards has been completed. This version of GEM is based 

on the model used for the Phase 1 rule, which was peer-reviewed by a panel of four independent 

subject matter experts (from academia and a national laboratory). The peer review report and the 

agency's response to the peer review comments are available in Docket ID No. EPA–HQ–OAR–

2014-0827.

D. Executive Summary 

(1) Commitment to Greenhouse Gas Emission Reductions and Vehicle Fuel 

Efficiency

As part of the Climate Action Plan announced in June 2013,4the President directed the 

Environmental Protection Agency (EPA) and the Department of Transportation’s (DOT)

National Highway Traffic Safety Administration (NHTSA) to set the next round of standards to 

reduce greenhouse gas (GHG) emissions and improve fuel efficiency for medium- and heavyduty vehicles. More than 70 percent of the oil used in the United States and 28 percent of GHG 

 

4 The White House, The President’s Climate Action Plan (June, 2013). http://www.whitehouse.gov/share/climateaction-plan.
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emissions come from the transportation sector, and since 2009 EPA and NHTSA have worked 

with industry and states to develop ambitious, flexible standards for both the fuel economy and 

GHG emissions of light-duty vehicles and the fuel efficiency and GHG emissions of heavy-duty 

vehicles.5,6 The standards proposed here (referred to as Phase 2) would build on the light-duty 

vehicle standards spanning model years 2011 to 2025 and on the initial phase of standards 

(referred to as Phase 1) for new medium and heavy-duty vehicles (MDVs and HDVs) and 

engines in model years 2014 to 2018. Throughout every stage of development for these 

programs, EPA and NHTSA (collectively, the agencies, or “we”) have worked in close 

partnership not only with one another, but with the vehicle manufacturing industry, 

environmental community leaders, and the State of California among other entities to create a 

single, effective set of national standards. 

Through two previous rulemakings, EPA and NHTSA have worked with the auto 

industry to develop new fuel economy and GHG emission standards for light-duty vehicles. 

Taken together, the light-duty vehicle standards span model years 2011 to 2025 and are the first 

significant improvement in fuel economy in approximately two decades. Under the final 

program, average new car and light truck fuel economy is expected to double by 2025.

7

 This is 

projected to save consumers $1.7 trillion at the pump — roughly $8,200 per vehicle for a 

MY2025 vehicle — reducing oil consumption by 2.2 million barrels a day in 2025 and slashing 

GHG emissions by 6 billion metric tons over the lifetime of the vehicles sold during this period.8 

These fuel economy standards are already delivering savings for American drivers. Between 

model years 2008 and 2013, the unadjusted average test fuel economy of new passenger cars and 

light trucks sold in the United States has increased by about four miles per gallon. Altogether, 

light-duty vehicle fuel economy standards finalized after 2008 have already saved nearly one

billion gallons of fuel and avoided more than 10 million tons of carbon dioxide emissions.9

Similarly, EPA and NHTSA have previously developed joint GHG emission and fuel 

efficiency standards for MDVs and HDVs. Prior to these Phase 1 standards, heavy-duty trucks 

and buses – from delivery vans to the largest tractor-trailers – were required to meet pollution 

standards for soot and smog-causing air pollutants, but no requirements existed for the fuel 

efficiency or carbon pollution from these vehicles.10 By 2010, total fuel consumption and GHG 

emissions from MDVs and HDVs had been growing, and these vehicles accounted for 23 percent 

of total U.S. transportation-related GHG emissions.11 In August 2011, the agencies finalized the 

groundbreaking Phase 1 standards for new MDVs and HDVs in model years 2014 through 2018. 

 

5 The White House, Improving the Fuel Efficiency of American Trucks – Bolstering Energy Security, Cutting 

Carbon Pollution, Saving Money and Supporting Manufacturing Innovation (Feb. 2014), 2. 

6 U.S. Environmental Protection Agency. 2014. Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2012. 

EPA 430-R-14-003. Mobile sources emitted 28 percent of all U.S. GHG emissions in 2012. Available at

http://www.epa.gov/climatechange/Downloads/ghgemissions/US-GHG-Inventory-2014-Main-Text.pdf

7

Id. 

8

Id. 

9

Id. at 3. 

10 Id.

11 Id. 
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This program, developed with support from the trucking and engine industries, the State of 

California, Environment Canada, and leaders from the environmental community, set standards 

that are expected to save a projected 530 million barrels of oil and reduce carbon emissions by

about 270 million metric tons, representing one of the most significant programs available to 

reduce domestic emissions of GHGs.

12

 The Phase 1 program, as well as the many additional 

actions called for in the President’s 2013 Climate Action Plan13 including this Phase 2 

rulemaking, not only result in meaningful decreases in GHG emissions, but support – indeed are 

critical for – United States leadership to encourage other countries to also achieve meaningful 

GHG reductions. 

This NPRM builds on our commitment to robust collaboration with stakeholders and the 

public. It follows an expansive and thorough outreach effort in which the agencies gathered 

input, data and views from many interested stakeholders, involving over 200 meetings with 

heavy-duty vehicle and engine manufacturers, technology suppliers, trucking fleets, truck 

drivers, dealerships, environmental organizations, and state agencies. As with the previous lightduty rules and the heavy-duty Phase 1 rule, the agencies have consulted frequently with the 

California Air Resources Board staff during the development of this Phase 2 proposal, given 

California’s unique ability among the states to adopt their own GHG standards for on-highway

engines and vehicles. The agencies look forward to feedback and ongoing conversation 

following the release of this NPRM from all stakeholders – including through planned public 

hearings, written comments, and other opportunities for input.

(2) Overview of Phase 1 Medium- and Heavy-Duty Vehicle Standards

The President’s direction to EPA and NHTSA to develop GHG emission and fuel 

efficiency standards for MDVs and HDVs resulted in the agencies’ promulgation of the Phase 1 

program in 2011, which covers new trucks and heavy vehicles in model years 2014 to 2018. The 

Phase 1 program includes specific standards for combination tractors, heavy-duty pickup trucks 

and vans, and vocational vehicles, and includes separate standards for both vehicles and engines. 

The program offers extensive flexibility, allowing manufacturers to reach standards through 

average fleet calculations, a mix of technologies, and the use of various credit and banking 

programs. 

The Phase 1 program was developed through close consultation with industry and other 

stakeholders, resulting in standards tailored to the specifics of each different class of vehicles and 

engines. 

 Heavy-duty combination tractors. Combination tractors — semi trucks that typically

pull trailers — are regulated under nine subcategories based on weight class, cab type, 

 

12 Id. at 4. 

13 The President’s Climate Action Plan calls for GHG-cutting actions including, for example, reducing carbon 

emissions from power plants and curbing hydrofluorocarbon and methane emissions. 
Page 11 of 850

and roof height. These vehicles represent approximately two-thirds of all fuel 

consumption and GHG emissions from MDVs and HDVs.14

 Heavy-duty pickup trucks and vans. Heavy-duty pickup and van standards are based 

on a “work factor” attribute that combines a vehicle’s payload, towing capabilities, and 

the presence of 4-wheel drive. These vehicles represent about 15 percent of the fuel 

consumption and GHG emissions from MDVs and HDVs.15

 Vocational vehicles. Specialized vocational vehicles, which consist of a very wide 

variety of truck and bus types (e.g., delivery, refuse, utility, dump, cement, transit bus, 

shuttle bus, school bus, emergency vehicles, and recreational vehicles) are regulated in 

three subcategories based on engine classification. These vehicles represent 

approximately 20 percent of the fuel consumption and GHG emissions from MDVs and 

HDVs.16 The Phase 1 program includes EPA GHG standards for recreational vehicles, 

but not NHTSA fuel efficiency standards.17 

 Heavy-duty engines. In addition to vehicle types, the Phase 1 rule has separate 

standards for heavy-duty engines, to assure they contribute to the overall vehicle 

reductions in fuel consumption and GHG emissions. 

The Phase 1 standards are premised on utilization of immediately available technologies.

The Phase 1 program provides flexibilities that facilitate compliance. These flexibilities help 

provide sufficient lead time for manufacturers to make necessary technological improvements 

and reduce the overall cost of the program, without compromising overall environmental and 

fuel consumption objectives. The primary flexibility provisions are an engine averaging, 

banking, and trading (ABT) program and a vehicle ABT program. These ABT programs allow 

for emission and/or fuel consumption credits to be averaged, banked, or traded within each of the 

regulatory subcategories. However, credits are not allowed to be transferred across 

subcategories.

The Phase 1 program is projected to save 530 million barrels of oil and avoid 270 million 

metric tons of GHG emissions.18 At the same time, the program is projected to produce $50 

billion in fuel savings, and net societal benefits of $49 billion. Today, the Phase 1 fuel efficiency

and GHG reduction standards are already reducing GHG emissions and U.S. oil consumption, 

and producing fuel savings for America’s trucking industry. The market appears to be very

 

14 U.S. Environmental Protection Agency. 2014. Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-

2012. EPA 430-R-14-003. Mobile sources emitted 28 percent of all U.S. GHG emissions in 2012. Available at

http://www.epa.gov/climatechange/Downloads/ghgemissions/US-GHG-Inventory-2014-Main-Text.pdf. 

15.

15 Id. at 16.

16 Id. at 18.

17 The proposed Phase 2 program would also include NHTSA recreational vehicle fuel efficiency standards.

18 The White House, Improving the Fuel Efficiency of American Trucks – Bolstering Energy Security, Cutting 

Carbon Pollution, Saving Money and Supporting Manufacturing Innovation (Feb. 2014), 4. 
Page 12 of 850

accepting of the new technology, and the agencies have seen no evidence of “pre-buy” effects in 

response to the standards.

(3) Overview of Proposed Phase 2 Medium- and Heavy-Duty Vehicle Standards

The Phase 2 GHG and fuel efficiency standards for MDVs and HDVs are a critical next 

step in improving fuel efficiency and reducing GHG. The proposed Phase 2 standards carry

forward our commitment to meaningful collaboration with stakeholders and the public, as they

build on more than 200 meetings with manufacturers, suppliers, trucking fleets, dealerships, state 

air quality agencies, non-governmental organizations (NGOs), and other stakeholders to identify

and understand the opportunities and challenges involved with this next level of fuel saving 

technology. These meetings have been invaluable to the agencies, enabling the development of a 

proposal that appropriately balances all potential impacts and effectively minimizes the 

possibility of unintended consequences.

Phase 2 would include technology-advancing standards that would phase in over the 

long-term (through model year 2027) to result in an ambitious, yet achievable program that 

would allow manufacturers to meet standards through a mix of different technologies at 

reasonable cost. The Phase 2 standards would maintain the underlying regulatory structure 

developed in the Phase 1 program, such as the general categorization of MDVs and HDVs and 

the separate standards for vehicles and engines. However, the Phase 2 program would build on 

and advance Phase 1 in a number of important ways including: basing standards not only on 

currently available technologies but also on utilization of technologies now under development 

or not yet widely deployed while providing significant lead time to assure adequate time to 

develop, test, and phase in these controls; developing standards for trailers; further encouraging 

innovation and providing flexibility; including vehicles produced by small business

manufacturers; incorporating enhanced test procedures that (among other things) allow 

individual drivetrain and powertrain performance to be reflected in the vehicle certification 

process; and using an expanded and improved compliance simulation model. 

 Strengthening standards to account for ongoing technological advancements. Relative 

to the baseline as of the end of Phase 1, the proposed standards (labeled Alternative 3 or the 

“preferred alternative” throughout this proposal) would achieve vehicle fuel savings of up to

8 percent and 24 percent, depending on the vehicle category. While costs are higher than for 

Phase 1, benefits greatly exceed costs, and payback periods are short, meaning that 

consumers will see substantial net savings over the vehicle lifetime. Payback is estimated at 

about two years for tractors and trailers, about five years for vocational vehicles, and about 

three years for heavy-duty pickups and vans. The agencies are further proposing to phase in 

these MY 2027 standards with interim standards for model years 2021 and 2024 (and for 

certain types of trailers, EPA is proposing model year 2018 phase-in standards as well). 

In addition to the proposed standards, the agencies are considering another alternative

(Alternative 4), which would achieve the same performance as the proposed standards 2-3 

years earlier, leading to overall reductions in fuel use and greenhouse gas emissions. The 

agencies believe Alternative 4 has the potential to be the maximum feasible and appropriate 

alternative; however, based on the evidence currently before us, EPA and NHTSA have 

outstanding questions regarding relative risks and benefits of Alternative 4 due to the 
Page 13 of 850

timeframe envisioned by that alternative. The agencies are proposing Alternative 3 based on 

their analyses and projections, and taking into account the agencies’ respective statutory

considerations. The comments that the agencies receive on this NPRM will be instrumental 

in helping us determine standards that are appropriate (for EPA) and maximum feasible (for 

NHTSA), given the discretion that both agencies have under our respective statutes. 

Therefore, the agencies have presented different options and raised specific questions 

throughout the NPRM, focusing in particular on better understanding the perspectives on the 

feasible adoption rates of different technologies, considering associated costs and necessary

lead time. 

 Setting standards for trailers for the first time. In addition to retaining the vehicle and 

engine categories covered in the Phase 1 program, which include semi tractors, heavy-duty

pickup trucks and work vans, vocational vehicles, and separate standards for heavy-duty 

engines, the Phase 2 standards propose fuel efficiency and GHG emission standards for 

trailers used in combination with tractors. Although the agencies are not proposing standards 

for all trailer types, the majority of new trailers would be covered. 

 Encouraging technological innovation while providing flexibility and options for 

manufacturers. For each category of HDVs, the standards would set performance targets 

that allow manufacturers to achieve reductions through a mix of different technologies and 

leave manufacturers free to choose any means of compliance. For tractors and vocational 

vehicles, enhanced test procedures and an expanded and improved compliance simulation 

model enable the proposed vehicle standards to encompass more of the complete vehicle and 

to account for engine, transmission and driveline improvements than the Phase 1 program. 

With the addition of the powertrain and driveline to the compliance model, representative 

drive cycles and vehicle baseline configurations become critically important to assure the 

standards promote technologies that improve real world fuel efficiency and GHG emissions. 

This proposal updates drive cycles and vehicle configurations to better reflect real world 

operation. For tractor standards, for example, different combinations of improvements like 

advanced aerodynamics, engine improvements and waste-heat recovery, automated 

transmission, and lower rolling resistance tires and automatic tire inflation can be used to 

meet standards. Additionally, the agencies’ analyses indicate that this proposal should have 

no adverse impact on vehicle or engine safety.

 Providing flexibilities to help minimize effect on small businesses. All small businesses 

are exempt from the Phase 1 standards. The agencies are proposing to regulate small 

business entities under Phase 2 (notably certain trailer manufacturers), but have conducted 

extensive proceedings pursuant to Section 609 of the Regulatory Flexibility Act, and 

otherwise have engaged in extensive consultation with stakeholders, and developed a

proposed approach to provide targeted flexibilities geared toward helping small businesses 

comply with the Phase 2 standards. Specifically, the agencies are proposing to delay all new 

requirements by one year and simplify certification requirements for small businesses, and 

are further proposing additional specific flexibilities adapted to particular types of trailers. 
Page 14 of 850

Summary of the Proposed Phase 2 Medium- and Heavy-Duty Vehicle Rule Impacts to Fuel Consumption, 

GHG emissions, Benefits and Costs over the Lifetime of Model Years 2018 – 2029, Based on Analysis Method 

A

,a,b,c

3% 7%

Fuel Reductions (billion gallons) 73 - 77

GHG Reductions (MMT, CO2eq) 932 - 990

Pre-Tax Fuel Savings ($billion) 165 - 175 89 - 94

Discounted Technology Costs 

($billion)

25 - 25.4 16.8 -17.1

Value of reduced emissions ($billion) 70.1 – 73.7 52.9 – 55.6

Total Costs ($billion) 30.3 - 30.8 19.8 - 20.2

Total Benefits ($billion) 261 - 276 156 - 165

Net Benefits ($billion) 231 - 245 136 - 144

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the 

less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

b Range reflects two reference case assumptions, one that projects very little improvement in new 

vehicle fuel efficiency absent new standards, and the second that projects more significant 

improvements in vehicle fuel efficiency absent new standards.

c Benefits and net benefits (including those in the 7% discount rate column) use the 3 percent average 

SCC-CO2 value applied only to CO2 emissions; GHG reductions include CO2, CH4, N2O and HFC 

reductions.

Summary of the Proposed Phase 2 Medium- and Heavy-Duty Vehicle Annual Fuel and GHG Reductions, 

Program Costs, Benefits and Net Benefits in Calendar Years 2035 and 2050, Based on Analysis Method B a

2035 2050

Fuel Reductions (Billion Gallons) 9.3 13.4

GHG Reduction (MMT, CO2eq) 127.1 183.4

Vehicle Program Costs (including Maintenance; Billions of 2012$) -$6.0 -$7.1

Fuel Savings (Pre-Tax; Billions of 2012$) $37.2 $57.5

Benefits (Billions of 2012$) $20.5 $32.9

Net Benefits (Billions of 2012$) $51.7 $83.2

Notes:

a Benefits and net benefits use the 3 percent average SCC-CO2 value applied only to CO2 emissions; GHG 

reductions include CO2, CH4, N2O and HFC reductions; values reflect the preferred alternative relative to the 

less dynamic baseline (a reference case that projects very little improvement in new vehicle fuel economy 

absent new standards.
Page 15 of 850

Summary of the Proposed Phase 2 Medium- and Heavy-Duty Vehicle Program Expected Per-Vehicle Fuel 

Savings, GHG Emission Reductions, and Cost for Key Vehicle Categories, Based on Analysis Method B a

MY 2021 MY 2024 MY 2027

Maximum Vehicle Fuel Savings and Tailpipe 

GHG Reduction (%)

Tractors 13 20 24

Trailersb

4 6 8

Vocational Vehicles 7 11 16

Pickups/Vans 2.5 10 16

Per Vehicle Cost ($)c

(% Increase in Typical Vehicle Price)d

Tractors $6,710 (7%) $9,940 (10%) $11,680 (12%)

Trailers $900 (4%) $1,010 (4%) $1,170 (5%)

Vocational Vehicles $1,150 (2%) $1,770 (3%) $3,380 (5%)

Pickups/Vans $520 (1%) $950 (2%) $1,340 (3%)

Notes:

a. Note that the proposed EPA standards for some categories of box trailers begin in model year 2018; values 

reflect the preferred alternative relative to the less dynamic baseline (a reference case that projects very little 

improvement in new vehicle fuel economy absent new standards.

b All engine costs are included

c

For this table, we use a typical vehicle price today of $100,000 for tractors, $25,000 for trailers, $70,000 for 

vocational vehicles and $40,000 for HD pickups/vans

Payback Periods for MY2027 Vehicles under the Proposed Standards, Based on Analysis Method B (Payback 

Occurs in the Year Shown; using 7% Discounting)

Proposed Standards

Tractors/Trailers 2

nd

Vocational Vehicles 6

th

Pickups/Vans 3

rd

(4) Issues Addressed in this NPRM

This NPRM contains extensive discussion of the background, elements, and implications 

of the proposed Phase 2 program. Section I includes information on the MDV and HDV 

industry, related regulatory and non-regulatory programs, summaries of Phase 1 and Phase 2 

programs, costs and benefits of the proposed standards, and relevant statutory authority for EPA 

and NHTSA. Section II discusses vehicle simulation, engine standards, and test procedures. 

Sections III, IV, V, and VI detail the proposed standards for combination tractors, trailers, 

vocational vehicles, and heavy-duty pickup trucks and vans. Sections VII and VIII discuss 

aggregate GHG impacts, fuel consumption impacts, climate impacts, and impacts on non-GHG 

emissions. Section IX evaluates the economic impacts of the proposed standards. Sections X,

XI, and XII present the alternatives analyses, consideration of natural gas vehicles, and the 

agencies’ initial response to recommendations from the Academy of Sciences. Finally, Sections

XIII and XIV discuss the changes that the proposed Phase 2 NPRM would have on Phase 1 

standards and other regulatory provisions. In addition to this preamble, the agencies have also 
Page 16 of 850

prepared a joint Draft Regulatory Impact Analysis (DRIA) which is available on our respective 

websites and in the public docket for this rulemaking which provides additional data, analysis 

and discussion of the proposed standards and the alternatives analyzed by the agencies. We 

request comment on all aspects of this proposed rulemaking, including the DRIA.
Page 17 of 850

Table of Contents

A. Does this Action Apply to Me?

B. Public Participation

C. Did EPA Conduct a Peer Review before Issuing this Notice?

D. Executive Summary

I. Overview

A. Background

B. Summary of Phase 1 Program

C. Summary of the Proposed Phase 2 Standards and Requirements

D. Summary of the Costs and Benefits of the Proposed Rule

E. EPA and NHTSA Statutory Authorities

F. Other Issues

II. Vehicle Simulation, Engine Standards and Test Procedures

A. Introduction and Summary of Phase 1 and Phase 2 Regulatory Structures

B. Phase 2 Proposed Regulatory Structure

C. Proposed Vehicle Simulation Model – Phase II GEM 

D. Proposed Engine Test Procedures and Engine Standards

III. Class 7 and 8 Combination Tractors

A. Summary of the Phase 1 Tractor Program

B. Overview of the Proposed Phase 2 Tractor Program

C. Proposed Phase 2 Tractor Standards

D. Feasibility of the Proposed Tractor Standards

E. Proposed Compliance Provisions for Tractors

F. Flexibility Provisions
Page 18 of 850

IV. Trailers

A. Summary of Trailer Consideration in Phase 1

B. The Trailer Industry

C. Proposed Phase 2 Trailer Standards

D. Feasibility of the Proposed Trailer Standards

E. Alternative Standards and Feasibility Considered

F. Trailer Standards: Compliance and Flexibilities

V. Class 2b-8 Vocational Vehicles

A. Summary of Phase 1 Vocational Vehicle Standards

B. Proposed Phase 2 Standards for Vocational Vehicles

C. Feasibility of the Proposed Vocational Vehicle Standards

D. Alternative Vocational Vehicle Standards Considered

E. Compliance Provisions for Vocational Vehicles

VI. Heavy-duty Pickups and Vans

A. Introduction and Summary of Phase 1 HD Pickup and Van Standards

B. Proposed HD Pickup and Van Standards

C. Feasibility of Pickup and Van Standards

D. DOT CAFE Model Analysis of the Regulatory Alternatives for HD Pickups and 

Vans

E. Compliance and Flexibility for HD Pickup and Van Standards

VII. Aggregate GHG, Fuel Consumption, and Climate Impacts

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

Consumption Impacts?

B. Analysis of Fuel Consumption and GHG Emissions Impacts Resulting from 

Proposed Standards and Alternative 4

C. What Are the Projected Reductions in Fuel Consumption and GHG Emissions?
Page 19 of 850

D. Climate Impacts and Indicators

VIII. How Will This Proposed 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

IX. Economic and Other Impacts

A. Conceptual Framework

B. Vehicle-Related Costs Associated with the Program

C. Changes in Fuel Consumption and Expenditures

D. Maintenance Expenditures

E. Analysis of the Rebound Effect

F. Impact on Class Shifting, Fleet Turnover, and Sales

G. Monetized GHG Impacts

H. Monetized Non-GHG Health Impacts

I. Energy Security Impacts

J. Other Impacts

K. Summary of Benefits and Costs

L. Employment Impacts

M. Cost of Ownership and Payback Analysis

N. Safety Impacts

X. Analysis of the Alternatives

A. What Are the Alternatives that the Agencies Considered?

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

Emissions Reductions and in Benefits and Costs?
Page 20 of 850

XI. Natural Gas Vehicles and Engines

A. Natural Gas Engine and Vehicle Technology

B. GHG Lifecycle Analysis for Natural Gas Vehicles

C. Projected Use of LNG and CNG

D. Natural Gas Emission Control Measures

E. Dimethyl Ether

XII. Agencies’ Response to Recommendations from the National Academy of Sciences

A. Overview

B. Major Findings and Recommendations of the NAS Phase 2 First Report

XIII. Amendments to Phase 1 Standards

A. EPA Amendments

B. Other Compliance Provisions for NHTSA

XIV. Other Proposed Regulatory Provisions

A. Proposed Amendments Related to Heavy-Duty Highway Engines and Vehicles

B. Amendments Affecting Gliders and Glider Kits

C. Applying the General Compliance Provisions of 40 CFR Part 1068 to Light-Duty 

Vehicles, Light-Duty Trucks, Chassis-certified Class 2B and 3 Heavy-Duty Vehicles and 

Highway Motorcycles

D. Amendments to General Compliance Provisions in 40 CFR Part 1068

E. Amendments to Light-Duty Greenhouse Gas Program Requirements

F. Amendments to Highway and Nonroad Test Procedures and Certification 

Requirements

G. Amendments Related to Nonroad Diesel Engines in 40 CFR Part 1039

H. Amendments Related to Marine Diesel Engines in 40 CFR Parts 1042 and 1043

I. Amendments Related to Locomotives in 40 CFR Part 1033

J. Miscellaneous EPA Amendments
Page 21 of 850

K. Amending 49 CFR Parts 512 and 537 to Allow Electronic Submissions and 

Defining Data Formats for Light-Duty Vehicle Corporate Average Fuel Economy (CAFE) 

Reports

XV. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and Executive Order 

13563: Improving Regulation and Regulatory Review

B. National Environmental Policy Act

C. Paperwork Reduction Act

D. Regulatory Flexibility Act

E. Unfunded Mandates Reform Act

F. Executive Order 13132: Federalism

G. Executive Order 13175: Consultation and Coordination with Indian Tribal 

Governments

H. Executive Order 13045: Protection of Children from Environmental Health Risks 

and Safety Risks

I. Executive Order 13211: Actions Concerning Regulations That Significantly Affect 

Energy Supply, Distribution, or Use

J. National Technology Transfer and Advancement Act and 1 CFR Part 51

K. Executive Order 12898: Federal Actions to Address Environmental Justice in 

Minority Populations and Low-Income Populations

XVI. EPA and NHTSA Statutory Authorities

A. EPA

B. NHTSA

C. List of Subjects
Page 22 of 850

I. Overview

A. Background

This background and summary of the proposed Phase 2 GHG emissions and fuel 

efficiency standards includes an overview of the heavy-duty truck industry and related regulatory 

and non-regulatory programs, a summary of the Phase 1 GHG emissions and fuel efficiency

program, a summary of the proposed Phase 2 standards and requirements, a summary of the 

costs and benefits of the proposed Phase 2 standards, discussion of EPA and NHTSA statutory 

authorities, and other issues.

For purposes of this preamble, the terms “heavy-duty” or “HD” are used to apply to all 

highway vehicles and engines that are not within the range of light-duty passenger cars, lightduty trucks, and medium-duty passenger vehicles (MDPV) covered by separate GHG and 

Corporate Average Fuel Economy (CAFE) standards.19 They do not include motorcycles. Thus, 

in this rulemaking, unless specified otherwise, the heavy-duty category incorporates all vehicles 

with a gross vehicle weight rating above 8,500 pounds, and the engines that power them, except 

for MDPVs.20,21

Consistent with the President’s direction, over the past two years as we have developed 

this proposal, the agencies have met on an on-going basis with a very large number of diverse 

stakeholders. This includes meetings, and in many cases site visits, with truck, trailer, and 

engine manufacturers; technology supplier companies and their trade associations (e.g., 

transmissions, drive lines, fuel systems, turbochargers, tires, catalysts, and many others); line 

haul and vocational trucking firms and trucking associations; the trucking industries owneroperator association; truck dealerships and dealers associations; trailer manufacturers and their 

trade association; non-governmental organizations (NGOs, including environmental NGOs, 

national security NGOs, and consumer advocacy NGOs); state air quality agencies; 

manufacturing labor unions; and many other stakeholders. In particular, NHTSA and EPA have 

consulted on an on-going basis with the California Air Resources Board (CARB) over the past 

two years as we have developed the Phase 2 proposal. In addition, CARB staff and managers 

have also participated with EPA and NHTSA in meetings with many external stakeholders, in 

particular with vehicle OEMs and technology suppliers.22

 

19 2017 and Later Model Year Light-Duty Vehicle Greenhouse Gas Emissions and Corporate Average Fuel 

Economy Standards; Final Rule, 77 FR 62623, October 15, 2012.

20 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. 

21 The Energy Independence and Security Act of 2007 requires NHTSA to set standards for commercial mediumand heavy-duty on-highway vehicles, defined as on-highway vehicles with a GVWR of 10,000 pounds or more, and 

work trucks, defined as vehicles with a GVWR between 8,500 and 10,000 pounds and excluding medium duty 

passenger vehicles.

22 Vehicle chassis manufacturers are known in this industry as original equipment manufacturers or OEMs.
Page 23 of 850

NHTSA and EPA staff also participated in a large number of technical and policy

conferences over the past two years related to the technological, economic, and environmental 

aspects of the heavy-duty trucking industry. The agencies also met with regulatory counterparts 

from several other nations who either have already or are considering establishing fuel 

consumption or GHG requirements, including outreach with representatives from the 

governments of Canada, the European Commission, Japan, and China.

These comprehensive outreach actions by the agencies provided us with information to 

assist in our identification of potential technologies that can be used to reduce heavy-duty GHG 

emissions and improve fuel efficiency. The outreach has also helped the agencies to identify and 

understand the opportunities and challenges involved with the proposed standards for the heavyduty trucks, trailers, and engines detailed in this preamble, including time needed for 

implementation of various technologies and potential costs and fuel savings. The scope of this 

outreach effort to gather input for the proposal included well over 200 meetings with 

stakeholders. These meetings and conferences have been invaluable to the agencies. We believe 

they have enabled us to develop this proposal in such a way as to appropriately balance all of the 

potential impacts, to minimize the possibility of unintended consequences, and to ensure that we 

are requesting comment on a wide range of issues that can inform the final rule. 

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

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

companies involved, the range of sizes of trucks and engines they produce, the types of work for 

which the trucks are designed, 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 the largest pickup trucks and vans, as well as

vocational vehicles covering a range between these extremes. Together, the HD sector spans a 

wide range of vehicles with often specialized form and function. A primary indicator of the 

diversity among heavy-duty trucks is the range of load-carrying capability across the industry. 

The heavy-duty truck sector is often subdivided by vehicle weight classifications, as defined by 

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

(empty) weight and cargo carrying capacity of the truck.23 Table I-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.

 

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

Heavy-duty vehicles (including those designed for primary purposes other than towing) 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.
Page 24 of 850

Table I-1Vehicle 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

> 33,000

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

“Class 2b” through “Class 8” vehicles and the engines that power those vehicles.24 

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

personal travel, heavy-duty vehicles fill much more diverse operator needs. Heavy-duty pickup 

trucks and vans (Classes 2b and 3) are used chiefly as work trucks 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 vehicles 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. 

Class 7 and 8 combination tractor-trailers – some equipped with sleeper cabs and some 

not -- are primarily used for freight transportation. They are sold as tractors and operate 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. Together, Class 7 and 8 

tractors and trailers account for approximately two-thirds of the heavy-duty sector’s total CO2 

emissions and fuel consumption. Trailer designs vary significantly, reflecting the wide variety of 

cargo types. However, the most common types of trailers are box vans (dry and refrigerated), 

which are a focus of this Phase 2 rulemaking. The tractor-trailers used in combination 

applications can and frequently do travel more than 150,000 miles per year and can operate for 

20-30 years.

EPA and NHTSA have designed our respective proposed standards in careful 

consideration of the diversity and complexity of the heavy-duty truck industry, as discussed in 

Section I. B. 

 

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

by the light-duty GHG and fuel economy standards and therefore are not addressed in this rulemaking.
Page 25 of 850

(2) Related Regulatory and Non-Regulatory Programs

(a) History of EPA’s Heavy-Duty Regulatory Program and Impacts of Greenhouse Gases on 

Climate Change

This subsection provides an overview of the history of EPA’s heavy-duty regulatory

program and impacts of greenhouse gases on climate change.

(i) History of EPA’s 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 two decades 

these programs have primarily addressed emissions of particulate matter (PM) and the primary

ozone precursors, hydrocarbons (HC) and oxides of nitrogen (NOX). These programs, which 

have successfully achieved significant and cost-effective reductions in emissions and associated 

health and welfare benefits to the nation, were an important basis of the Phase 1 program. See 

e.g. 66 FR 5002, 5008, 5011-12 (January 18, 2001) (detailing substantial public health benefits 

of controls of criteria pollutants from heavy-duty diesel engines, including bringing areas into 

attainment with primary (public health) PM NAAQS, or contributing substantially to such 

attainment); National Petrochemical Refiners Association v. EPA, 287 F. 3d 1130, 1134 (D.C. 

Cir. 2002) (referring to the “dramatic reductions” in criteria pollutant emissions resulting from 

those on-highway heavy-duty engine standards, and upholding all of the standards).

As required by the Clean Air Act (CAA), the emission standards implemented by these 

programs include standards that apply at the time that the vehicle or engine is sold and continue 

to apply in actual use. 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 by regulating heavy-duty engine 

emissions. A key part of this success has been the development over many years of a wellestablished, representative, and robust set of engine test procedures that industry and EPA now 

use routinely 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.

(ii) Impacts of Greenhouse Gases on Climate Change

In 2009, the EPA Administrator issued the document known as the Endangerment 

Finding under CAA Section 202(a)(1).25 In the Endangerment Finding, which focused on public 

health and public welfare impacts within the United States, the Administrator found that elevated 

concentrations of GHG emissions in the atmosphere may reasonably be anticipated to endanger 

 

25 “Endangerment and Cause or Contribute Findings for Greenhouse Gases Under Section 202(a) of the Clean Air 

Act,” 74 FR 66496 (December 15, 2009) (“Endangerment Finding”).
Page 26 of 850

public health and welfare of current and future generations. See also Coalition for Responsible 

Regulation v. EPA, 684 F. 3d 102, 117-123 (D.C. Cir. 2012) (upholding the endangerment 

finding in all respects). The following sections summarize the key information included in the 

Endangerment Finding.

Climate change caused by human emissions of GHGs threatens public health in multiple 

ways. By raising average temperatures, climate change increases the likelihood of heat waves, 

which are associated with increased deaths and illnesses. While climate change also increases 

the likelihood of reductions in cold-related mortality, evidence indicates that the increases in heat 

mortality will be larger than the decreases in cold mortality in the United States. Compared to a 

future without climate change, climate change is expected to increase ozone pollution over broad 

areas of the U.S., including in the largest metropolitan areas with the worst ozone problems, and 

thereby increase the risk of morbidity and mortality. Other public health threats also stem from 

projected increases in intensity or frequency of extreme weather associated with climate change, 

such as increased hurricane intensity, increased frequency of intense storms and heavy 

precipitation. Increased coastal storms and storm surges due to rising sea levels are expected to 

cause increased drownings and other adverse health impacts. Children, the elderly, and the poor 

are among the most vulnerable to these climate-related health effects. See also 79 FR 75242 

(Dec. 17, 2014) (climate change, and temperature increases in particular, likely to increase O3 

(Ozone) pollution “over broad areas of the U.S., including the largest metropolitan areas with the 

worst O3 problems, increas[ing] the risk of morbidity and mortality”).

Climate change caused by human emissions of GHGs also threatens public welfare in 

multiple ways. Climate changes are expected to place large areas of the country at serious risk of 

reduced water supplies, increased water pollution, and increased occurrence of extreme events 

such as floods and droughts. Coastal areas are expected to face increased risks from storm and 

flooding damage to property, as well as adverse impacts from rising sea level, such as land loss 

due to inundation, erosion, wetland submergence and habitat loss. Climate change is expected to 

result in an increase in peak electricity demand, and extreme weather from climate change 

threatens energy, transportation, and water resource infrastructure. Climate change may

exacerbate ongoing environmental pressures in certain settlements, particularly in Alaskan 

indigenous communities. Climate change also is very likely to fundamentally rearrange U.S. 

ecosystems over the 21st century. Though some benefits may balance adverse effects on 

agriculture and forestry in the next few decades, the body of evidence points towards increasing 

risks of net adverse impacts on U.S. food production, agriculture and forest productivity as 

temperature continues to rise. These impacts are global and may exacerbate problems outside 

the U.S. that raise humanitarian, trade, and national security issues for the U.S. See also 79 FR 

75382 (Dec. 17, 2014) (welfare effects of O3 increases due to climate change, with emphasis on 

increased wildfires).

As outlined in Section VIII.A. of the 2009 Endangerment Finding, EPA's approach to 

providing the technical and scientific information to inform the Administrator's judgment 

regarding the question of whether GHGs endanger public health and welfare was to rely 

primarily upon the recent, major assessments by the U.S. Global Change Research Program 

(USGCRP), the Intergovernmental Panel on Climate Change (IPCC), and the National Research 

Council (NRC) of the National Academies. These assessments addressed the scientific issues 

that EPA was required to examine, were comprehensive in their coverage of the GHG and 
Page 27 of 850

climate change issues, and underwent rigorous and exacting peer review by the expert 

community, as well as rigorous levels of U.S. government review. Since the administrative 

record concerning the Endangerment Finding closed following EPA's 2010 Reconsideration 

Denial, a number of such assessments have been released. These assessments include the IPCC's 

2012 “Special Report on Managing the Risks of Extreme Events and Disasters to Advance 

Climate Change Adaptation” (SREX) and the 2013-2014 Fifth Assessment Report (AR5), the 

USGCRP's 2014 “Climate Change Impacts in the United States” (Climate Change Impacts), and 

the NRC's 2010 “Ocean Acidification: A National Strategy to Meet the Challenges of a 

Changing Ocean” (Ocean Acidification), 2011 “Report on Climate Stabilization Targets: 

Emissions, Concentrations, and Impacts over Decades to Millennia” (Climate Stabilization 

Targets), 2011 “National Security Implications for U.S. Naval Forces” (National Security

Implications), 2011 “Understanding Earth's Deep Past: Lessons for Our Climate Future” 

(Understanding Earth's Deep Past), 2012 “Sea Level Rise for the Coasts of California, Oregon, 

and Washington: Past, Present, and Future”, 2012 “Climate and Social Stress: Implications for 

Security Analysis” (Climate and Social Stress), and 2013 “Abrupt Impacts of Climate Change” 

(Abrupt Impacts) assessments.

EPA has reviewed these new assessments and finds that the improved understanding of 

the climate system they present strengthens the case that GHG emissions endanger public health 

and welfare.

In addition, these assessments highlight the urgency of the situation as the concentration 

of CO2 in the atmosphere continues to rise. Absent a reduction in emissions, a recent National 

Research Council of the National Academies assessment projected that concentrations by the end 

of the century would increase to levels that the Earth has not experienced for millions of years.26 

In fact, that assessment stated that “the magnitude and rate of the present greenhouse gas 

increase place the climate system in what could be one of the most severe increases in radiative 

forcing of the global climate system in Earth history.”27 What this means, as stated in another 

NRC assessment, is that:

Emissions of carbon dioxide from the burning of fossil fuels have ushered in a new epoch 

where human activities will largely determine the evolution of Earth's climate. Because 

carbon dioxide in the atmosphere is long lived, it can effectively lock Earth and future 

generations into a range of impacts, some of which could become very severe. Therefore, 

emission reductions choices made today matter in determining impacts experienced not 

just over the next few decades, but in the coming centuries and millennia.28

Moreover, due to the time-lags inherent in the Earth's climate, the Climate Stabilization 

Targets assessment notes that the full warming from any given concentration of CO2 reached will 

not be realized for several centuries.

 

26 National Research Council, Understanding Earth's Deep Past, p. 1

27 Id., p.138.

28 National Research Council, Climate Stabilization Targets, p. 3.
Page 28 of 850

The recently released USGCRP “National Climate Assessment”29 emphasizes that 

climate change is already happening now and it is happening in the United States. The 

assessment documents the increases in some extreme weather and climate events in recent 

decades, the damage and disruption to infrastructure and agriculture, and projects continued 

increases in impacts across a wide range of peoples, sectors, and ecosystems.

These assessments underscore the urgency of reducing emissions now: Today's emissions 

will otherwise lead to raised atmospheric concentrations for thousands of years, and raised Earth 

system temperatures for even longer. Emission reductions today will benefit the public health 

and public welfare of current and future generations.

Finally, it should be noted that the concentration of carbon dioxide in the atmosphere 

continues to rise dramatically. In 2009, the year of the Endangerment Finding, the average 

concentration of carbon dioxide as measured on top of Mauna Loa was 387 parts per million.30 

The average concentration in 2013 was 396 parts per million. And the monthly concentration in 

April of 2014 was 401 parts per million, the first time a monthly average has exceeded 400 parts 

per million since record keeping began at Mauna Loa in 1958, and for at least the past 800,000 

years according to ice core records.31

(b) 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 lightduty cars and trucks, which set GHG emissions and fuel economy standards for model years 

2012-2016 (see 75 FR 25324). More recently, the agencies adopted even stricter standards for 

model years 2017 and later (77 FR 62624, October 15, 2012). The agencies have used the lightduty National Program as a model for the HD National Program in several respects. This is most 

apparent in the case of heavy-duty pickups and vans, which are 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, and 

several light-duty manufacturers also manufacture HD pickups and vans).

32

 For HD pickups and 

vans, there are close parallels to the light-duty program in how the agencies have developed our 

respective heavy-duty standards and compliance structures. However, HD pickups and vans are 

true work vehicles that are designed for much higher towing and payload capabilities than are 

light-duty pickups and vans. The technologies applied to light-duty trucks are not all applicable 

to heavy-duty pickups and vans at the same adoption rates, and the technologies often produce a 

lower percent reduction in CO2 emissions and fuel consumption when used in heavy-duty 

vehicles. Another difference between the light-duty and the heavy-duty standards is that each 

 

29 U.S. Global Change Research Program, Climate Change Impacts in the United States: The Third National Climate 

Assessment, May 2014 Available at http://nca2014.globalchange.gov/.

30 ftp://aftp.cmdl.noaa.gov/products/trends/co2/co2_annmean_mlo.txt.

31 http://www.esrl.noaa.gov/gmd/ccgg/trends/.

32 This is more broadly true for heavy-duty pickup trucks than vans because every manufacturer of heavy-duty 

pickup trucks also makes light-duty pickup trucks, while only some heavy-duty van manufacturers also make lightduty vans. 
Page 29 of 850

agency adopts heavy-duty 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

throughout the Phase 1 rulemaking and the continued efforts for Phase 2. Most notably, as with 

the light-duty program, manufacturers would continue to be able to design and build vehicles to 

meet a closely coordinated, harmonized national program, and to avoid unnecessarily duplicative 

testing and compliance burdens. In addition, the averaging, banking, and trading provisions in 

the HD program, although structurally different from those of the light-duty program, serve the 

same purpose, which is to allow manufacturers to achieve large reductions in fuel consumption 

and emissions while providing a broad mix of products to their customers. The agencies have 

also worked closely with CARB to provide harmonized national standards.

(c) NHTSA and FMCSA’s Notice of Proposed Rulemaking for Heavy Vehicle Speed Limiters

NHTSA and FMCSA plan to issue a NPRM that would respond to petitions from the 

American Trucking Associations (ATA) and Roadsafe America to require the installation of 

speed limiting devices on heavy trucks. In response to the petitions, NHTSA requested public 

comment on the subject and received thousands of comments supporting the petitioner ́s request. 

We believe this rule would have minimal cost, as all heavy trucks already have these devices 

installed, although some vehicles do not have the limit set. This rule would decrease the 

estimated 1,115 fatal crashes annually involving vehicles with a GVWR of over 11,793.4 kg 

(26,000 lbs) on roads with posted speed limits of 55 mph or above.

NHTSA and EPA will continue to monitor the evolution of this rulemaking as it may

impact the effectiveness of vehicle speed limiters, one of the technologies available to reduce 

fuel consumption and CO2 emissions from heavy-duty vehicles. The HD Phase 1 and proposed 

Phase 2 programs apply fuel consumption and CO2 emissions savings for speed limiters set at 

less than 65 mph. If the mandatory speed limiters are required to be set below 65 mph, then EPA 

and NHTSA would need to consider the potential impact on the HD Phase 2 technology

effectiveness.

(d) EPA’s SmartWay Program

EPA’s voluntary SmartWay Transport Partnership program encourages businesses to take 

actions that reduce fuel consumption and CO2 emissions while cutting costs by working with the 

shipping, logistics, and carrier communities to identify low carbon strategies and technologies 

across their transportation supply chains. SmartWay provides technical information, 

benchmarking and tracking tools, market incentives, and partner recognition to facilitate and 

accelerate the adoption of these strategies. Through the SmartWay program and its related 

technology assessment center, EPA has worked closely with truck and trailer manufacturers and 

truck fleets over the last ten years 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. SmartWay partners have 

demonstrated these new and emerging technologies in their business operations, adding to the 
Page 30 of 850

body of technical data and information that EPA can disseminate to industry, researchers and 

other stakeholders. Over the last several years, EPA has developed hands-on experience testing 

the largest heavy-duty trucks and trailers and evaluating improvements in tire and vehicle 

aerodynamic performance. In developing the Phase 1 program, the agencies drew from this 

testing and from the SmartWay experience. In the same way, the agencies benefitted from 

SmartWay in developing the proposed Phase 2 trailer program.

(e) The State of California

California has established ambitious goals for reducing GHG emissions from heavy-duty 

vehicles and engines as part of an overall plan to reduce GHG emissions from the transportation 

sector in California.

33 Heavy-duty vehicles are responsible for one-fifth of the total GHG 

emissions from transportation sources in California. In the past several years the California Air 

Resources Board (CARB) has taken a number of actions to reduce GHG emissions from heavyduty vehicles and engines. For example, in 2008, the CARB adopted regulations to reduce GHG

emissions from heavy-duty tractors that pull box-type trailers through improvements in tractor 

and trailer aerodynamics and the use of low rolling resistance tires.

34 The tractors and trailers 

subject to the CARB regulation are required to use SmartWay certified tractors and trailers, or 

retrofit their existing fleet with SmartWay verified technologies, consistent with California’s

state authority to regulate both new and in-use vehicles. Recently, in December 2013, CARB

adopted regulations that establish its own parallel Phase 1 program with standards consistent 

with EPA Phase 1 standards. On December 5, 2014, California’s Office of Administrative Law 

approved CARB’s adoption of the Phase 1 standards, with an effective date of December 5, 

2014.35 Complementary to its regulatory efforts, CARB and other California agencies are 

investing significant public capital through various incentive programs to accelerate fleet 

turnover and stimulate technology innovation within the heavy-duty vehicle market (e.g., Air 

Quality Improvement, Carl Moyer, Loan Incentives, Lower-Emission School Bus and Goods 

Movement Emission Reduction Programs).36 And, recently, California Governor Jerry Brown 

established a target of up to 50 percent petroleum reduction by 2030. 

In addition to California’s efforts to reduce GHG emissions that contribute to climate 

change, California also faces unique air quality challenges as compared to many other regions of 

the United States. Many areas of the state are classified as non-attainment for both the ozone and 

particulate matter National Ambient Air Quality Standards (NAAQS) with California having the 

 

33 See http://www.arb.ca.gov/cc/cc.htm for details on the California Air Resources Board climate change actions, 

including a discussion of Assembly Bill 32, and the Climate Change Scoping Plan developed by CARB, which 

includes details regarding CARB’s future goals for reducing GHG emissions from heavy-duty vehicles.

34 See http://www.arb.ca.gov/msprog/truckstop/trailers/trailers.htm for a summary of CARB’s “Tractor-Trailer 

Greenhouse Gas Regulation”.

35 See http://www.arb.ca.gov/regact/2013/hdghg2013/hdghg2013.htm for details regarding CARB’s adoption of the 

Phase 1 standards.

36 See http://www.arb.ca.gov/ba/fininfo.htm for detailed descriptions of CARB’s mobile source incentive programs. 

Note that EPA works to support CARB’s heavy-duty incentive programs through the West Coast Collaborative 

(http://westcoastcollaborative.org/) and the Clean Air Technology Initiative 

(http://www.epa.gov/region09/cleantech/).
Page 31 of 850

nation’s only two “Extreme” ozone non-attainment airsheds (the San Joaquin Valley and South 

Coast Air Basins).37 By 2016, California must submit to EPA its Clean Air Act State 

Implementation Plans (SIPs) that demonstrate how the 2008 ozone and 2006 PM2.5NAAQS will 

be met by Clean Air Act deadlines. Extreme ozone areas must attain the 2008 ozone NAAQS by

no later than 2032 and PM2.5 moderate areas must attain the 2006 PM2.5 standard by 2021 or, if 

reclassified to serious, by 2025. 

Heavy-duty vehicles are responsible today for one-third of the state’s oxides of nitrogen 

(NOX) emissions. California has estimated that the state’s South Coast Air Basin will need 

nearly a 90 percent reduction in heavy-duty vehicle NOX emissions by 2032 from 2010 levels to 

attain the 2008 NAAQS for ozone. Additionally, on November 25, 2014, EPA issued a proposal 

to strengthen the ozone NAAQS. If a change to the ozone NAAQS is finalized, California and 

other areas of the country will need to identify and implement measures to reduce NOX as 

needed to complement Federal emission reduction measures. While this section is focused on 

California’s regulatory programs and air quality needs, EPA recognizes that other states and 

local areas are concerned about the challenges of reducing NOX and attaining, as well as 

maintaining, the ozone NAAQS (further discussed in Section VIII.D.1 below).

In order to encourage the use of lower NOX emitting new heavy-duty vehicles in 

California, in 2013 CARB adopted a voluntary low NOX emission standard for heavy-duty 

engines.38 In addition, in 2013 CARB awarded a major new research contract to Southwest 

Research Institute to investigate advanced technologies that could reduce heavy-duty vehicle 

NOX emissions well below the current EPA and CARB standards.

California has long had the unique ability among states to adopt its own separate new 

motor vehicle standards per Section 209 of the Clean Air Act (CAA). Although section 209(a) 

of the CAA expressly preempts states from adopting and enforcing standards relating to the 

control of emissions from new motor vehicles or new motor vehicle engines (such as state 

controls for new heavy-duty engines and vehicles) CAA section 209(b) directs EPA to waive this 

preemption under certain conditions. Under the waiver process set out in CAA Section 209(b), 

EPA has granted CARB a waiver for its initial heavy-duty vehicle GHG regulation.39 Even with 

California’s ability under the CAA to establish its own emission standards, EPA and CARB have 

worked closely together over the past several decades to largely harmonize new vehicle criteria 

pollutant standard programs for heavy-duty engines and heavy-duty vehicles. In the past several 

years EPA and NHTSA also consulted with CARB in the development of the Federal light-duty 

vehicle GHG and CAFE rulemakings for the 2012-2016 and 2017-2025 model years. 

 

37 See http://www.epa.gov/airquality/greenbk/index.html for more information on EPA’s nonattainment 

designations.

38 See http://www.arb.ca.gov/regact/2013/hdghg2013/hdghg2013.htm for a description of the CARB optional 

reduced NOX emission standards for on-road heavy-duty engines.

39 See EPA’s waiver of CARB’s heavy-duty tractor-trailer greenhouse gas regulation applicable to new 2011 

through 2013 model year Class 8 tractors equipped with integrated sleeper berths (sleeper-cab tractors) and 2011 

and subsequent model year dry-can and refrigerated-van trailers that are pulled by such tractors on California 

highways at 79 FR 46256 (August 7, 2014).
Page 32 of 850

As discussed above, California operates under state authority to establish its own new 

heavy-duty vehicle and engine emission standards, including standards for CO2, methane, N2O, 

and hydrofluorocarbons. EPA recognizes this independent authority, and we also recognize the 

potential benefits for the regulated industry if the Federal Phase 2 standards could result in a 

single, National Program that would meet the NHTSA and EPA’s statutory requirements to set 

appropriate and maximum feasible standards, and also be equivalent to potential future new 

heavy-duty vehicle and engine GHG standards established by CARB (addressing the same model 

years as addressed by the final Federal Phase 2 program and requiring the same technologies). 

Similarly, CARB has expressed support in the past for a Federal heavy-duty Phase 2 

program that would produce significant GHG reductions both at the Federal level and in 

California that could enable CARB to adopt the same standards at the state level. This is similar 

to CARB’s approach for the Federal heavy-duty Phase 1 program, and with past EPA criteria 

pollutant standards for heavy-duty vehicles and engines. In order to further the opportunity for 

maintaining coordinated Federal and California standards in the Phase 2 timeframe (as well as to 

benefit from different technical expertise and perspective), NHTSA and EPA have consulted on 

an on-going basis with CARB over the past two years as we have developed the Phase 2 

proposal. The agencies’ technical staff have shared information on technology cost, technology

effectiveness, and feasibility with the CARB staff. We have also received information from 

CARB on these same topics. EPA and NHTSA have also shared preliminary results from 

several of our modeling exercises with CARB as we examined different potential levels of 

stringency for the Phase 2 program. In addition, CARB staff and managers have also 

participated with EPA and NHTSA in meetings with many external stakeholders, in particular 

with vehicle OEMs and technology suppliers. 

In addition to information on GHG emissions, CARB has also kept EPA and NHTSA 

informed of the state’s need to consider opportunities for additional NOX emission reductions 

from heavy-duty vehicles. CARB has asked the agencies to consider opportunities in the HeavyDuty Phase 2 rulemaking to encourage or incentivize further NOX emission reductions, in 

addition to the petroleum and GHG reductions which would come from the Phase 2 standards. 

When combined with the Phase 1 standards, the technologies the agencies are projecting to be 

used to meet the proposed GHG emission and fuel efficiency standards would be expected to 

reduce NOX emissions by over 450,000 tons in 2050 (see Section VIII).

EPA and NHTSA believe that through this information sharing and dialog we will 

enhance the potential for the Phase 2 program to result in a National Program that can be adopted 

not only by the Federal agencies, but also by the State of California, given the strong interest 

from the regulated industry for a harmonized State and Federal program.

The agencies will continue to seek input from CARB, and from all stakeholders, 

throughout this rulemaking.

(f) Environment Canada

On March 13, 2013, Environment Canada (EPA’s Canadian counterpart) published its 

own regulations to control GHG emissions from heavy-duty vehicles and engines, beginning 

with MY 2014. These regulations are closely aligned with EPA’s Phase 1 program to achieve a 
Page 33 of 850

common set of North American standards. Environment Canada has expressed its intention to 

amend these regulations to further limit emissions of greenhouse gases from new on-road heavyduty vehicles and their engines for post-2018 MYs. As with the development of the current 

regulations, Environment Canada is committed to continuing to work closely with EPA to 

maintain a common Canada–United States approach to regulating GHG emissions for post-2018 

MY vehicles and engines. This approach will build on the long history of regulatory alignment 

between the two countries on vehicle emissions pursuant to the Canada–United States Air 

Quality Agreement.41 Environment Canada has also been of great assistance during the 

development of this Phase 2 proposal. In particular, Environment Canada supported 

aerodynamic testing, and conducted chassis dynamometer emissions testing.

(g) Recommendations of the National Academy of Sciences

In April 2010 as mandated by Congress in the Energy Independence and Security Act of 

2007 (EISA), the National Research Council (NRC) under the National Academy of Sciences 

(NAS) issued a report to NHTSA and to Congress evaluating medium- and heavy-duty truck fuel 

efficiency improvement opportunities, titled “Technologies and Approaches to Reducing the 

Fuel Consumption of Medium- and Heavy-duty Vehicles.” That NAS report was far reaching in 

its review of the technologies that were available and that might 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 included technologies that may not be available until 2020 or 

even further into the future. The report provided not only a valuable list of off the shelf 

technologies from which the agencies drew in developing the Phase 1 program, but also provided 

useful information the agencies have considered when developing this second phase of 

regulations. 

In April 2014, the NAS issued another report: “Reducing the Fuel Consumption and 

Greenhouse Gas Emissions of Medium and Heavy-Duty Vehicles, Phase Two, First Report.” 

This study outlines a number of recommendations to the U.S. Department of Transportation and 

NHTSA on technical and policy matters to consider when addressing the fuel efficiency of our 

nation’s medium- and heavy-duty vehicles. In particular, this report provided recommendations 

with respect to:

 The Greenhouse Gas Emission Model (GEM) simulation tool used by the 

agencies to assess compliance with vehicle standards

 Regulation of trailers

 Natural gas-fueled engines and vehicles

 Data collection on in-use operation

As described in Sections II, IV, and XII, the agencies are proposing to incorporate many 

of these recommendations into this proposed Phase 2 program, especially those 

recommendations relating to the GEM simulation tool and to trailers. 

 

41 http://www.ijc.org/en_/Air_Quality__Agreement
Page 34 of 850

B. Summary of Phase 1 Program

(1) EPA Phase 1 GHG Emission Standards and NHTSA Phase 1 Fuel Consumption 

Standards

The EPA Phase 1 GHG mandatory standards commenced in MY 2014 and include 

increased stringency for standards applicable to MY 2017 and later MY vehicles and engines. 

NHTSA’s fuel consumption standards are voluntary for MYs 2014 and 2015, due to lead time 

requirements in EISA, and apply on a mandatory basis thereafter. They also increase in 

stringency for MY 2017. Both agencies have allowed voluntary early compliance starting in MY 

2013 and encouraged manufacturers’ participation through credit incentives.

Given the complexity of the heavy-duty industry, the agencies divided the industry into 

three discrete categories for purposes of setting our respective Phase 1 standards – combination 

tractors, heavy-duty pickups and vans, and vocational vehicles -- based on the relative degree of 

homogeneity among trucks within each category. The Phase 1 rule also include separate 

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

regulatory category, the agencies adopted related but distinct program approaches reflecting the 

specific challenges in these segments. In the following paragraphs, we summarize briefly EPA’s 

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

regulatory categories of heavy-duty vehicles and for the engines powering vocational vehicles 

and tractors. See Sections III, V, and VI for additional details on the Phase 1 standards. To 

respect differences in design and typical uses that drive different technology solutions, the 

agencies segmented each regulatory class into subcategories. The category-specific structure 

enabled the agencies to set standards that appropriately reflect the technology available for each 

regulatory subcategory of vehicles and the engines for use in each type of vehicle. The Phase 1 

program also provided several flexibilities, as summarized in Section I.B(3).

The agencies are proposing to base the Phase 2 standards on test procedures that differ 

from those used for Phase 1, including the revised GEM simulation tool. Significant revisions to 

GEM are discussed in Section II and the draft RIA Chapter 4, and other test procedures are 

discussed further in the draft RIA Chapter 3. It is important to note that due to these test 

procedure changes, the Phase 1 standards and the proposed Phase 2 standards are not directly

comparable in an absolute sense. In particular, the proposed revisions to the 55 mph and 65 mph 

highway cruise cycles for tractors and vocational vehicles have the effect of making the cycles 

more challenging (albeit more representative of actual driving conditions). We are not proposing 

to apply these revisions to the Phase 1 program because doing so would significantly change the 

stringency of the Phase 1 standards, for which manufacturers have already developed 

engineering plans and are now producing products to meet. Moreover, the agencies intend such 

changes to address a broader range of technologies not part of the projected compliance path for 

use in Phase 1.

(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 two-thirds, 

due to their large payloads, their high annual miles traveled, and their major role in national 
Page 35 of 850

freight transport. These vehicles consist of a cab and engine (tractor or combination tractor) and 

a detachable trailer. The primary manufacturers of combination tractors in the United States are 

Daimler Trucks North America, Navistar, Volvo/Mack, and PACCAR. Each of the tractor 

manufacturers and Cummins (an independent engine manufacturer) also produce heavy-duty 

engines used in tractors. The Phase 1 standards require manufacturers to reduce GHG emissions 

and fuel consumption for these vehicles and engines, which we expect them to do through 

improvements in aerodynamics and tires, reductions in tractor weight, reduction in idle 

operation, as well as engine-based efficiency improvements.42 

The Phase 1 tractor standards differ depending on gross vehicle weight rating (GVWR) 

(i.e., whether the truck is Class 7 or Class 8), the height of the roof of the cab, and whether it is a 

“day cab” or a “sleeper cab.” The agencies created nine subcategories within the Class 7 and 8 

combination tractor category reflecting combinations of these attributes. The agencies set Phase 

1 standards for each of these subcategories beginning in MY 2014, with more stringent standards 

following in MY 2017. 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 MY 2010 tractor and engine.

For Phase 1, manufacturers demonstrate compliance with the tractor CO2 and fuel 

consumption standards using a vehicle simulation tool described in Section II. The tractor inputs 

to the simulation tool in Phase 1 are the aerodynamic performance, tire rolling resistance, vehicle 

speed limiter, automatic engine shutdown, and weight reduction. The agencies have verified, 

through our own confirmatory testing, that the values inputs into the model by manufacturers are 

generally correct. Prior to and after adopting the Phase 1 standards, the agencies worked with 

manufacturers to minimize impacts of this process on their normal business practices. 

In addition to the final Phase 1 tractor-based standards for CO2, EPA adopted a separate 

standard to reduce leakage of hydrofluorocarbon (HFC) refrigerant from cabin air conditioning 

(A/C) systems from combination tractors, to apply to the tractor manufacturer. This HFC 

leakage standard is independent of the CO2 tractor standard. Manufacturers can choose 

technologies from a menu of leak-reducing technologies sufficient to comply with the standard, 

as opposed to using a test to measure performance. Given that HFC leakage does not relate to 

fuel efficiency, NHTSA did not adopt corresponding HFC standards.

(b) Heavy-Duty Pickup Trucks and Vans (Class 2b and 3)

Heavy-duty vehicles with a GVWR between 8,501 and 10,000 lb are classified as Class 

2b motor vehicles. Heavy-duty vehicles with a 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 

 

42 We note although the standards’ stringency is predicated on use of certain technologies, and the agencies’ 

assessed the cost of the rule based on the cost of use of those technologies, the standards can be met by any means. 

Put another way, the rules create a performance standard, and do not mandate any particular means of achieving that 

level of performance.
Page 36 of 850

these rules as “HD pickups and vans”) together emit about 15 percent of today’s GHG emissions 

from the heavy-duty vehicle sector.43 

The majority of HD pickups and vans are 3⁄4-ton and 1-ton pickup trucks, 12- and 15-

passenger vans,

44 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 vehicles can also be sold as cab-complete vehicles (i.e., incomplete vehicles that 

include complete or nearly complete cabs that are sold to secondary manufacturers). The 

majority of heavy-duty pickups and vans are produced by companies with major light-duty 

markets in the United States. Furthermore, the technologies available to reduce fuel 

consumption and GHG emissions from this segment are similar to the technologies used on lightduty pickup trucks, including both engine efficiency improvements (for gasoline and diesel 

engines) and vehicle efficiency improvements. For these reasons, EPA and NHTSA concluded 

that it was appropriate to adopt GHG standards, expressed as grams per mile, and fuel 

consumption standards, expressed as gallons per 100 miles, for HD pickups and vans based on 

the whole vehicle (including the engine), consistent with the way these vehicles have been 

regulated by EPA for criteria pollutants and also consistent with the way their light-duty 

counterpart vehicles are regulated by NHTSA and EPA. This complete vehicle approach 

adopted by both agencies for HD pickups and vans was consistent with the recommendations of 

the NAS Committee in its 2010 Report.

For the light-duty GHG and fuel economy standards, the agencies based the emissions 

and fuel economy targets on vehicle footprint (the wheelbase times the average track width). 

For those standards, passenger cars and light trucks with larger footprints are assigned higher 

GHG and lower fuel economy target levels reflecting 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 have found that a work-based metric 

would be a more appropriate attribute than the footprint attribute utilized in the light-duty vehicle 

rulemaking, given that work-based measures such as towing and payload capacities are critical 

elements of these vehicles’ functionality. EPA and NHTSA therefore adopted 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.

Each manufacturer’s fleet average Phase 1 standard is based on production volumeweighting of target standards for all vehicles, which in turn are based on each vehicle’s work 

factor. These target standards are taken from a set of curves (mathematical functions), specified 

in 40 CFR 1037.104 with separate curves for gasoline and diesel.45 However, both gasoline and 

diesel vehicles in this category are included in a single averaging set. EPA phased in the CO2

standards gradually starting in the 2014 MY, at 15-20-40-60-100 percent of the MY 2018 

 

43 EPA MOVES Model, http://www.epa.gov/otaq/models/moves/index.htm

44 Note that 12-passenger vans are subject to the light-duty standards as medium-duty passenger vehicles (MDPVs) 

and are not subject to this proposal.

45 As explained in Section XII, EPA is proposing to recodify the Phase 1 requirements for pickups and vans from 40 

CFR 1037.104 into 40 CFR part 86, which is also the regulatory part that applies for light-duty vehicles. 
Page 37 of 850

standards stringency level in MYs 2014-2015-2016-2017-2018, respectively. The phase-in takes 

the form of a set of target curves, with increasing stringency in each MY.

NHTSA allowed manufacturers to select one of two fuel consumption standard 

alternatives for MYs 2016 and later. The first alternative defined individual gasoline vehicle and 

diesel vehicle fuel consumption target curves that will not change for MYs 2016-2018, and are 

equivalent to EPA’s 67-67-67-100 percent target curves in MYs 2016-2017-2018-2019, 

respectively. The second alternative defined target curves that are equivalent to EPA’s 40-60-

100 percent target curves in MYs 2016-2017-2018, respectively. NHTSA allowed 

manufacturers to opt voluntarily into the NHTSA HD pickup and van program in MYs 2014 or 

2015 at target curves equivalent to EPA’s target curves. If a manufacturer chose to opt in for one 

category, they would be required to opt in for all categories. In other words a manufacturer 

would be unable to opt in for Class 2b vehicles, but opt out for Class 3 vehicles.

EPA also adopted an alternative phase-in schedule for manufacturers wanting to have 

stable standards for model years 2016-2018. The standards for heavy-duty pickups and vans, 

like those for light-duty vehicles, are expressed as set of target standard curves, with increasing 

stringency in each model year. The final EPA standards for 2018 (including a separate standard 

to control air conditioning system leakage) represent an average per-vehicle reduction in GHG

emissions of 17 percent for diesel vehicles and 12 percent for gasoline vehicles (relative to precontrol baseline vehicles). The NHTSA standard will require these vehicles to achieve up to 

about 15 percent reduction in fuel consumption and greenhouse gas emissions by MY 2018

(relative to pre-control baseline vehicles). Manufacturers demonstrate compliance based on 

entire vehicle chassis certification using the same duty cycles used to demonstrate compliance 

with criteria pollutant standards. 

(c) Class 2b-8 Vocational Vehicles

Class 2b-8 vocational vehicles include a wide variety of vehicle types, and serve a vast 

range of functions. Some examples include service for urban delivery, refuse hauling, utility

service, dump, concrete mixing, transit service, shuttle service, school bus, emergency, motor 

homes, and tow trucks. In Phase 1, we defined Class 2b-8 vocational vehicles as all heavy-duty 

vehicles that are not included in either the heavy-duty pickup and van category or the Class 7 and 

8 tractor category. EPA’s and NHTSA’s Phase 1 standards for this vocational vehicle category

generally apply at the chassis manufacturer level. Class 2b-8 vocational vehicles and their 

engines emit approximately 20 percent of the GHG emissions and burn approximately 21 percent 

of the fuel consumed by today’s heavy-duty truck sector.

46

The Phase 1 program for vocational vehicles has vehicle standards and separate engine

standards, both of which differ based on the weight class of the vehicle into which the engine 

will be installed. The vehicle weight class groups mirror those used for the engine standards --

Classes 2b-5 (light heavy-duty or LHD in EPA regulations), Classes 6&7 (medium heavy-duty 

 

46 EPA MOVES model, http://www.epa.gov/otaq/models/moves/index.htm
Page 38 of 850

or MHD in EPA regulations) and Class 8 (heavy heavy-duty or HHD in EPA regulations). 

Manufacturers demonstrate compliance with the Phase 1 vocational vehicle CO2 and fuel 

consumption standards using a vehicle simulation tool described in Section II. The Phase 1 

program for vocational vehicles limited the simulation tool inputs to tire rolling resistance. The 

model assumes the use of a typical representative, compliant engine in the simulation, resulting 

in one overall value for CO2 emissions and one for fuel consumption. 

Engines used in vocational vehicles are subject to separate Phase 1 engine-based 

standards. Optional certification paths, for EPA and NHTSA, are also provided to enhance the 

flexibilities for vocational vehicles. Manufacturers producing spark-ignition (or gasoline) cabcomplete or incomplete vehicles weighing over 14,000 pounds GVWR and below 26,001 pounds 

GVWR have the option to certify to the complete vehicle standards for heavy-duty pickup trucks 

and vans rather than using the separate engine and chassis standards for vocational vehicles.

(d) Engine Standards

The agencies established separate Phase 1 performance standards for the engines 

manufactured for use in vocational vehicles and Class 7 and 8 tractors.47 These engine standards 

vary depending on engine size linked to intended vehicle service class. EPA’s engine-based CO2

standards and NHTSA’s engine-based fuel consumption standards are being implemented using 

EPA’s existing test procedures and regulatory structure for criteria pollutant emissions from 

heavy-duty engines.

The agencies also finalized a regulatory alternative whereby a manufacturer, for an 

interim period of the 2014-2016 MYs, would have the option to comply with a unique standard 

based on a three percent reduction from an individual engine model’s own 2011 MY baseline 

level.48 

(e) Manufacturers Excluded from the Phase 1 Standards

Phase 1 temporarily deferred 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. In order to utilize this exemption, qualifying small businesses 

must submit a declaration to the agencies. See Section I. F. (1) (b) for a summary of how Phase 

2 would apply for small businesses.

 

47 See 76 FR 57114/2 explaining why NHTSA’s authority under the Energy Independence and Safety Act includes 

authority to establish separate engine standards.

48 See 76 FR 57144.
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The agencies stated that they would 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. 

(2) Costs and Benefits of the Phase 1 Program

Overall, EPA and NHTSA estimated that the Phase 1 HD National Program will cost the 

affected industry about $8 billion, while saving vehicle owners fuel costs of nearly $50 billion 

over the lifetimes of MY 2014-2018 vehicles. The agencies also estimated that the combined 

standards will reduce CO2 emissions by about 270 million metric tons and save about 530 

million barrels of oil over the life of MY 2014 to 2018 vehicles. The agencies estimated 

additional monetized benefits from CO2 reductions, improved energy security, reduced time 

spent refueling, as well as possible disbenefits from increased driving accidents, traffic 

congestion, and noise. When considering all these factors, we estimated that Phase 1 of the HD 

National Program will yield $49 billion in net benefits to society over the lifetimes of MY 2014-

2018 vehicles. 

EPA estimated the benefits of reduced ambient concentrations of particulate matter and 

ozone resulting from the Phase 1 program to range from $1.3 to $4.2 billion in 2030.49 

In total, we estimated the combined Phase 1 standards will reduce GHG emissions from 

the U.S. heavy-duty fleet by approximately 76 million metric tons of CO2-equivalent annually by 

2030. In its Environmental Impact Statement for the Phase 1 rule, NHTSA also quantified 

and/or discussed other potential impacts of the program, such as the health and environmental 

impacts associated with changes in ambient exposures to toxic air pollutants and the benefits 

associated with avoided non-CO2 GHGs (methane, nitrous oxide, and HFCs).

(3) Phase 1 Program Flexibilities

As noted above, the agencies adopted numerous provisions designed to give 

manufacturers a degree of flexibility in complying with the Phase 1 standards. These provisions, 

which are essentially identical in structure and function in NHTSA’s and EPA’s regulations, 

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.50

Phase 1 included four primary types of flexibility: averaging, banking, and trading (ABT) 

provisions; early credits; advanced technology credits (including hybrid powertrains); and 

 

49 Note: These calendar year benefits do not represent the same time frame as the model year lifetime benefits 

described above, so they are not additive.

50 NHTSA explained 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).
Page 40 of 850

innovative technology credit provisions. The ABT provisions were patterned on existing EPA 

and NHTSA ABT programs (including the light-duty GHG and fuel economy standards) and 

will allow a vehicle manufacturer to reduce CO2 emission and fuel consumption levels further 

than the level of the standard for one or more vehicles to generate ABT credits. The 

manufacturer can use those credits to offset higher emission or fuel consumption levels in the 

same averaging set, “bank” the credits for later use, or “trade” the credits to another 

manufacturer. As also noted above, for HD pickups and vans, we adopted a fleet averaging 

system very similar to the light-duty GHG and CAFE fleet averaging system. In both programs, 

manufacturers are allowed to carry-forward deficits for up to three years without penalty. 

The agencies provided in the ABT programs flexibility for situations in which a 

manufacturer is unable to avoid a negative credit balance at the end of the year. In such cases, 

manufacturers are not considered to be out of compliance unless they are unable to make up the 

difference in credits by the end of the third subsequent model year. 

In total, the Phase 1 program divides the heavy-duty sector into 19 subcategories of 

vehicles. These subcategories are grouped into 9 averaging sets to provide greater opportunities 

in leveraging compliance. For tractors and vocational vehicles, the fleet averaging sets are 

Classes 2b through 5, Classes 6 and 7, and Class 8 weight classes. For engines, the fleet 

averaging sets are gasoline engines, light heavy-duty diesel engines, medium heavy-duty diesel 

engines, and heavy heavy-duty diesel engines. Complete HD pickups and vans (both sparkignition and compression-ignition) are the final fleet averaging set.

As noted above, the agencies included a 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. However, we did not allow trading between engines and chassis. We 

similarly allowed for trading among engine categories only within an averaging set, of which 

there are four: spark-ignition engines, compression-ignition light heavy-duty engines, 

compression-ignition medium heavy-duty engines, and compression-ignition heavy heavy-duty 

engines. 

In addition to ABT, the other primary flexibility provisions in the Phase 1 program 

involve opportunities to generate early credits, advanced technology credits (including for use of 

hybrid powertrains), and innovative technology credits.51 For the early credits and advanced 

technology credits, the agencies adopted a 1.5x multiplier, meaning that manufacturers would get 

1.5 credits for each early credit and each advanced technology credit. In addition, advanced 

technology credits for Phase 1 can be used anywhere within the heavy-duty sector (including 

 

51 Early credits are for engines and vehicles certified before EPA standards became mandatory, advanced technology 

credits are for hybrids and/or Rankine cycle engines, and innovative technology credits are for other technologies 

not in the 2010 fleet whose benefits are not reflected using the Phase 1 test procedures.
Page 41 of 850

both vehicles and engines). Put another way, as a means of promoting this promising 

technology, the Phase 1 rule does not restrict averaging or trading by averaging set in this 

instance.

For other vehicle or engine technologies that can reduce CO2 and fuel consumption, but 

for which there do not yet exist established methods for quantifying reductions, the agencies 

wanted to encourage the development of such innovative technologies, and therefore adopted 

special “innovative technology” credits. These innovative technology credits apply to 

technologies that are shown to produce emission and fuel consumption reductions that are not 

adequately recognized on the Phase 1 test procedures and that were not yet in widespread use in 

the heavy-duty sector before MY 2010. Manufacturers 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 is allowed only among vehicles and engines of the same defined averaging set generating 

the credit, as described above. The credit multiplier likewise does not apply for innovative 

technology credits.

(4) Implementation of Phase 1

Manufacturers have already begun complying with the Phase 1 standards. In some cases 

manufacturers voluntarily chose to comply early, before compliance was mandatory. The Phase 

1 rule allows manufacturers to generate credits for such early compliance. The market appears to 

be very accepting of the new technology, and the agencies have seen no evidence of “pre-buy” 

effects in response to the standards. In fact sales have been higher in recent years than they were 

before Phase 1 began. Moreover, manufacturers’ compliance plans are taking advantage of the 

Phase 1 flexibilities, and we have yet to see significant non-compliance with the standards. 

(5) Litigation on Phase 1 Rule

The D.C. Circuit recently rejected all challenges to the agencies’ Phase 1 regulations. 

The court did not reach the merits of the challenges, holding that none of the petitioners had 

standing to bring their actions, and that a challenge to NHTSA’s denial of a rulemaking petition 

could only be brought in District Court. See Delta Construction Co. v. EPA, 2015 U.S. App. 

LEXIS 6780, F.3d (D.C. Cir. April 24, 2015). 

C. Summary of the Proposed Phase 2 Standards and Requirements

The agencies are proposing new standards that build on and enhance existing Phase 1 

standards, as well as proposing the first ever standards for certain trailers used in combination 

with heavy-duty tractors. Taken together, the proposed Phase 2 program would comprise a set of 

largely technology-advancing standards that would achieve greater GHG and fuel consumption 

savings than the Phase 1 program. As described in more detail in the following sections, the 

agencies are proposing these standards because, based on the information available at this time, 

we believe they would best match our respective statutory authorities when considered in the 

context of available technology, feasible reductions of emissions and fuel consumption, costs, 

lead time, safety, and other relevant factors. The agencies request comment on all aspects of our 
Page 42 of 850

feasibility analysis including projections of feasible market adoption rates and technological 

effectiveness for each technology.

The proposed Phase 2 standards would represent a more technology-forcing52 approach 

than the Phase 1 approach, predicated on use of both off-the-shelf technologies and emerging 

technologies that are not yet in widespread use. The agencies are proposing standards for MY 

2027 that would likely require manufacturers to make extensive use of these technologies. For 

existing technologies and technologies in the final stages of development, we project that 

manufacturers would likely apply them to nearly all vehicles, excluding those specific vehicles 

with applications or uses that would prevent the technology from functioning properly. We also 

project as one possible compliance pathway that manufacturers could apply other more advanced 

technologies such as hybrids and waste engine heat recovery systems, although at lower 

application rates.

Under Alternative 3, the preferred alternative, the agencies propose to provide ten years 

of lead time for manufacturers to meet these 2027 standards, which the agencies believe is 

adequate to implement the technologies industry could use to meet the proposed standards. For 

some of the more advanced technologies production prototype parts are not yet available, though 

they are in the research stage with some demonstrations in actual vehicles.53 Additionally, even 

for the more developed technologies, phasing in more stringent standards over a longer 

timeframe may help manufacturers to ensure better reliability of the technology and to develop 

packages to work in a wide range of applications. Moving more quickly, however, as in 

Alternative 4, would lead to earlier and greater cumulative fuel savings and greenhouse gas 

reductions. 

As discussed later, the agencies are also proposing new standards in MYs 2018 (trailers 

only), 2021, and 2024 to ensure manufacturers make steady progress toward the 2027 standards, 

thereby achieving steady and feasible reductions in GHG emissions and fuel consumption in the 

years leading up to the MY 2027 standards. Moving more quickly, however, as in Alternative 4, 

would lead to earlier and greater cumulative fuel and greenhouse gas savings.

Providing additional lead time can often enable manufacturers to resolve technological 

challenges or to find lower cost means of meeting new regulatory standards, effectively making 

them more feasible in either case. See generally NRDC v. EPA, 655 F. 2d 318, 329 (D.C. Cir. 

1981). On the other hand, manufacturers and/or operators may incur additional costs if 

regulations require them to make changes to their products with less lead time than 

 

52 In this context, the term “technology-forcing” is used to distinguish standards that will effectively require 

manufacturers to develop new technologies (or to significantly improve technologies) from standards that can be 

met using off-the-shelf technology alone. Technology-forcing standards do not require manufacturers to use any 

specific technologies.

53 “Prototype” as it is used here refers to technologies that have a potentially production-feasible design that is 

expected to meet all performance, functional, reliability, safety, manufacturing, cost and other requirements and 

objectives that is being tested in laboratories and on highways under a full range of operating conditions, but is not 

yet available in production vehicles already for sale in the market.
Page 43 of 850

manufacturers would normally have when bringing a new technology to the market or expanding 

the application of existing technologies. After developing a new technology, manufacturers 

typically conduct extensive field tests to ensure its durability and reliability in actual use. 

Standards that accelerate technology deployment can lead to manufacturers incurring additional 

costs to accelerate this development work, or can lead to manufacturers beginning production 

before such testing can be completed. Some industry stakeholders have informed EPA that when

manufacturers introduced new emission control technologies (primarily diesel particulate filters) 

in response to the 2007 heavy-duty engine standards they did not perform sufficient product 

development validation, which led to additional costs for operators when the technologies 

required repairs or other resulted in other operational issues in use. Thus, the issues of costs, 

lead time, and reliability are intertwined for the agencies’ determination of whether standards are 

reasonable. 

Another important consideration is the possibility of disrupting the market, such as might 

happen if we were to adopt standards that manufacturers respond to by applying a new 

technology too suddenly. Several of the heavy-duty vehicle manufacturers, fleets, and 

commercial truck dealerships informed EPA that for fleet purchases that are planned more than a 

year in advance, expectations of reduced reliability, increased operating costs, reduced residual 

value, or of large increases in purchase prices can lead the fleets to pull-ahead by several months 

planned future vehicle purchases by pre-buying vehicles without the newer technology. In the 

context of the Class 8 tractor market, where a relatively small number of large fleets typically

purchase very large volumes of tractors, such actions by a small number of firms can result in 

large swings in sales volumes. Such market impacts would be followed by some period of 

reduced purchases that can lead to temporary layoffs at the factories producing the engines and 

vehicles, as well as at supplier factories, and disruptions at dealerships. Such market impacts

also can reduce the overall environmental and fuel consumption benefits of the standards by

delaying the rate at which the fleet turns over. See International Harvester v. EPA, 478 F. 2d 

615, 634 (D.C. Cir. 1973). A number of industry stakeholders have informed EPA that the 2007 

EPA heavy-duty engine criteria pollutant standard resulted in this pull-ahead phenomenon for the 

Class 8 tractor market. The agencies understand the potential impact that a pull-ahead can have 

on American manufacturing and labor, dealerships, truck purchasers, and on the program’s

environmental and fuel savings goals, and have taken steps in the design of the proposed 

program to avoid such disruption. These steps include the following:

 Providing considerable lead time

 The standards will result in significantly lower operating costs for vehicle owners 

(unlike the 2007 standard, which increased operating costs)

 Phasing in the standards

 Structuring the program so the industry will have a significant range of 

technology choices to be considered for compliance, rather than the one or two 

new technologies the OEMs pursued in 2007

 Allowing manufacturers to use emissions averaging, banking and trading to phase 

in the technology even further

We request comment on the sufficiency of the proposed Phase 2 structure, lead time, and 

stringency to avoid market disruptions. We note an important difference, however, between
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standards for criteria pollutants, with generally no attendant fuel savings, and the fuel 

consumption/GHG emission standards proposed today, which provide immediate and direct 

financial benefits to vehicle purchasers, who will begin saving money on fuel costs as soon as 

they begin operating the vehicles. It would seem logical, therefore, that vehicle purchasers (and 

manufacturers) would weigh those significant fuel savings against the potential for increased 

costs that could result from applying fuel-saving technologies sooner than they might otherwise 

choose in the absence of the standards. Given that fuel savings increase (and payback periods 

generally decrease) as the standards increase in stringency, it would also seem more likely that 

the expected higher fuel savings would outweight the higher costs in manufacturers’ and 

purchasers’ calculations.

As discussed in the Phase 1 final rule, NHTSA has certain statutory considerations to 

take into account when determining feasibility of the preferred alternative.54 The Energy

Independence and Security Act (EISA) states that NHTSA (in consultation with EPA and the 

Secretary of Energy) shall develop a commercial medium- and heavy-duty fuel efficiency

program designed “to achieve the maximum feasible improvement.”55 Although there is no 

definition of maximum feasible standards in EISA, NHTSA is directed to consider three factors 

when determining what the maximum feasible standards are. Those factors are the extent to 

which the standards are “appropriate, cost-effectiveness, and technological feasible,”56 which 

modify “feasible” beyond its plain meaning of “capable of being done.” 

NHTSA has the broad discretion to weigh and balance the aforementioned factors in 

order to accomplish EISA’s mandate of determining maximum feasible standards. The fact that 

the factors may often be at odds gives NHTSA significant discretion to decide what weight to 

give each of the competing factors, policies and concerns and then determine how to balance 

them—as long as NHTSA’s balancing does not undermine the fundamental purpose of the EISA:

energy conservation, and as long as that balancing reasonably accommodates “conflicting 

policies that were committed to the agency’s care by the statute.”57 

EPA also has significant discretion in assessing, weighing, and balancing the relevant 

statutory criteria. Section 202(a)(2) of the Clean Air Act requires that the standards “take effect 

after 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.” This language affords EPA considerable discretion in how to weight the critical 

statutory factors of emission reductions, cost, and lead time. 76 FR 57129-130. Section 202 (a) 

also allows (although it does not compel) EPA to adopt technology-forcing standards. Id. at 

57130. 

Giving due consideration to the agencies’ respective statutory criteria discussed above, 

the agencies are proposing these technology-forcing standards for MY 2027. The agencies 

 

54 75 FR 57198. 

55 49 U.S.C 32902(k). 

56 Id.

57 Center for Biological Diversity v. National Highway Traffic Safety Admin., 538 F.3d 1172, 1195 (9th Cir. 2008).
Page 45 of 850

nevertheless recognize that there is some uncertainty in projecting costs and effectiveness, 

especially for those technologies not yet widely available, but believe that the thresholds 

proposed for consideration account for realistic projections of technological development

discussed throughout this notice and in the draft RIA. The agencies are requesting comment on 

the alternatives described in Section X below. These alternatives range from Alternative 1 

(which is a no-action alternative that serves as the baseline for our cost and benefit analyses) to 

Alternative 5 (which includes the most stringent of the alternative standards analyzed by the 

agencies). The assessment of these different alternatives considers the importance of allowing 

manufacturers sufficient flexibility and discretion while achieving meaningful fuel consumption 

and GHG emissions reductions across vehicle types. The agencies look forward to receiving 

comments on questions of feasibility and long-term projections of costs and effectiveness.

As discussed throughout this document, the agencies believe Alternative 4 has potential 

to be the maximum feasible alternative, however, based on the evidence currently before us, the 

agencies have outstanding questions regarding relative risks and benefits of that option in the 

timeframe envisioned. Alternative 3 is generally designed to achieve the vehicle levels of fuel 

consumption and GHG reduction that Alternative 4 would achieve, but with two to three years of 

additional lead-time – i.e., the Alternative 3 standards would end up in the same place as the 

Alternative 4 standards, but two to three years later, meaning that manufacturers could, in theory, 

apply new technology at a more gradual pace and with greater flexibility as discussed above. 

However, Alternative 4 would lead to earlier and greater cumulative fuel savings and greenhouse 

gas reductions.

In the sections that follow, the agencies have closely examined the potential feasibility of 

Alternative 4 for each subcategory. The agencies may consider establishing final fuel efficiency

and GHG standards in whole or in part in the Alternative 4 timeframe if we deem them to be 

maximum feasible and reasonable for NHTSA and EPA, respectively. The agencies seek 

comment on the feasibility of Alternative 4, whether for some or for all segments, including 

empirical data on its appropriateness, cost-effectiveness, and technological feasibility. The 

agencies also note the possibility of adoption in MY 2024 of a standard reflecting deployment of 

some, rather than all, of the technologies on which Alternative 4 is predicated. It is also possible 

that the agencies could adopt some or all of the proposal (Alternative 3) earlier than MY 2027, 

but later than MY 2024, based especially on lead time considerations. Any such choices would 

involve a considered weighing of the issues of feasibility of projected technology penetration 

rates, associated costs, and necessary lead time, and would consider the information on available 

technologies, their level of performance and costs set out in the administrative record to this 

proposal.

Sections II through VI of this notice explain the consideration that the agencies took into 

account in considering options and proposing a preferred alternative based on balancing of the 

statutory factors under CAA Section 202 (a)(1) and (2), and under 49 U.S.C. Section 32902 (k) 

of EISA. 

(1) Carryover from Phase 1 Program and Proposed Compliance Changes

Phase 2 will carry over many of the compliance approaches developed for Phase 1, with 

certain changes as described below. Readers are referred to the proposed regulatory text for 
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much more detail. Note that some of these provisions are being carried over with revisions or 

additions (such as those needed to address trailers). 

(a) Certification

NHTSA and EPA are proposing to apply the same general certification procedures for 

Phase 2 as are currently being used for certifying to the Phase 1 standards. The agencies, 

however, are proposing changes to the simulation tool used for the vocational vehicle, tractor and 

trailer standards that would allow the simulation tool to more specifically reflect improvements 

to transmissions and drivetrains. 58 Rather than the model using default values for transmissions 

and drivetrains, manufacturers would enter measured or tested values as inputs reflecting 

performance of their actual transmission and drivetrain technologies. 

The agencies apply essentially the same process for certifying tractors and vocational 

vehicles, and propose largely to apply it to trailers as well. The Phase 1 certification process for 

engines used in tractors and vocational vehicles was based on EPA’s process for showing 

compliance with the heavy-duty engine criteria pollutant standards, and the agencies propose to 

continue it for Phase 2. Finally, we also propose to continue certifying HD pickups and vans 

using the Phase 1 vehicle certification process, which is very similar to the light-duty vehicle 

certification process.

EPA is also proposing to clarify provisions related to confirming a manufacturer’s test 

data during certification (i.e., confirmatory testing) and verifying a manufacturer’s vehicles are 

being produced to perform as described in the application for certification (i.e., selective 

enforcement audits or SEAs). The confirmatory testing provisions for engines and vehicles are 

in 40 CFR 1036.235 and 1037.235. The SEA provisions are in 40 CFR 1036.301 and 1037.301. 

Note that these clarifications would also apply for Phase 1 engines and vehicles. EPA welcomes 

suggestions for alternative approaches that would offer the same degree of compliance assurance 

for GHGs as these programs offer with respect to criteria pollutants.

(b) Averaging, Banking and Trading (ABT)

The Phase 1 ABT provisions were patterned on established EPA ABT programs that have 

proven to work well. In Phase 1, the agencies determined this flexibility would 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. We propose to generally continue this Phase 1 approach with few revisions for 

vehicles regulated in Phase 1. As described in Section IV, we are proposing a more limited 

averaging program for trailers. The agencies see the ABT program as playing an important role 

in making the proposed technology-advancing standards feasible, by helping to address many

issues of technological challenges in the context of lead time and costs. It provides

 

58 As described in Section IV, although the proposed trailer standards were developed using the simulation tool, the 

agencies are proposing a compliance structure that does not require trailer manufacturers to actually use the 

compliance tool. 
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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 generally, an integral part of the standard setting itself. A 

well-designed ABT program can also provide important environmental and energy security 

benefits by increasing the speed at which new technologies can be implemented (which means 

that more benefits accrue over time than with later-commencing standards) and at the same time 

increase flexibility for, and reduce costs to, the regulated industry and ultimately consumers. 

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 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 and 

more cost-effective pace.

59

(i) Carryover of Phase 1 Credits and Credit Life

The agencies propose to continue the five-year credit life provisions from Phase 1, and 

are not proposing any additional restriction on the use of banked Phase 1 credits in Phase 2. In 

other words, Phase 1 credits in MY2019 could be used in Phase 1 or in Phase 2 in MYs 2021-

2024. Although, as we have already noted, the numerical values of proposed Phase 2 standards 

are not directly comparable in an absolute sense to the existing Phase 1 standards (in other 

words, a given vehicle would have a different g/ton-mile emission rate when evaluated using 

Phase 1 GEM than it would when evaluated using Phase 2 GEM), we believe that the Phase 1 

and Phase 2 credits are largely equivalent. Because the standards and emission levels are 

included in a relative sense (as a difference), it is not necessary for the Phase 1 and Phase 2 

standards to be directly equivalent in an absolute sense in order for the credits to be equivalent.

This is best understood by examining the way in which credits are calculated. For 

example, the credit equations in 40 CFR 1037.705 and 49 CFR 535.7 calculate credits as the 

product of the difference between the standard and the vehicle’s emission level (g/ton-mile or 

gallon/1,000 ton-mile), the regulatory payload (tons), production volume, and regulatory useful 

life (miles). Phase 2 would not change payloads, production volumes, or useful lives for tractors, 

medium and heavy heavy-duty engines, or medium and heavy heavy-duty vocational vehicles. 

However, EPA is proposing to change the regulatory useful lives of HD pickups and vans, light 

heavy-duty vocational vehicles, spark-ignited engines, and light heavy-duty compressionignition engines. Because useful life is a factor in determining the value of a credit, the agencies 

are proposing interim adjustment factors to ensure banked credits maintain their value in the 

transition from Phase 1 to Phase 2.

 

59 See NRDC v. Thomas, 805 F. 2d 410, 425 (D.C. Cir. 1986) (upholding averaging as a reasonable and permissible 

means of implementing a statutory provision requiring technology-forcing standards).
Page 48 of 850

For Phase 1, EPA aligned the useful life for GHG emissions with the useful life already 

in place for criteria pollutants. After the Phase 1 rules were finalized, EPA updated the useful 

life for criteria pollutants as part of the Tier 3 rulemaking.60 The new useful life implemented for 

Tier 3 is 150,000 miles or 15 years, whichever occurs first. This is the same useful life proposed 

in Phase 2 for HD pickups and vans, light heavy-duty vocational vehicles, spark-ignited engines, 

and light heavy-duty compression-ignition engines. The numerical value of the adjustment 

factor for each of these regulatory categories depends on the Phase 1 useful life. These are 

described in detail below in this preamble in Sections II, V, and VI. Without these adjustment 

factors the proposed changes in useful life would effectively result in a discount of banked 

credits that are carried forward from Phase 1 to Phase 2, which is not the intent of the changes in 

the useful life. With the relatively flat deterioration generally associated with CO2, EPA does 

not believe the proposed changes in useful life would significantly affect the feasibility of the 

proposed Phase 2 standards. EPA requests comments on the proposed changes to useful life. We 

note that the primary purpose of allowing manufacturers to bank credits is to provide flexibility

in managing transitions to new standards. The five-year credit life is substantial, and would 

allow credits generated in either Phase 1 or early in Phase 2 to be used for the intended purpose. 

The agencies believe longer credit life is not necessary to accomplish this transition. 

Restrictions on credit life serve to reduce the likelihood that any manufacturer would be able to 

use banked credits to disrupt the heavy-duty vehicle market in any given year by effectively 

limiting the amount of credits that can be held. Without this limit, one manufacturer that saved 

enough credits over many years could achieve a significant cost advantage by using all the 

credits in a single year. The agencies believe, subject to consideration of public comment, that 

allowing a five year credit life for all credits, and as a consequence allowing use of Phase 1 

credits in Phase 2, creates appropriate flexibility and appropriately facilitates a smooth transition 

to each new level of standards.

Although we are not proposing any additional restrictions on the use of Phase 1 credits, 

we are requesting comment on this issue. Early indications suggest that positive market 

reception to the Phase 1 technologies could lead to manufacturers accumulating credit surpluses 

that could be quite large at the beginning of the proposed Phase 2 program. This appears 

especially likely for tractors. The agencies are specifically requesting comment on the likelihood 

of this happening, and whether any regulatory changes would be appropriate in response. For 

example, should the agencies limit the amount of credits that could be carried over from Phase1 

or limit them to the first year or two of the Phase 2 program? Also, if we determine that large 

surpluses are likely, how should that factor into our decision on the feasibility of more stringent 

standards in MY 2021?

(ii) Averaging Sets

EPA has historically restricted averaging to some extent for its HD emission standards to 

avoid creating unfair competitive advantages or environmental risks due to credits being 

inconsistent. Under Phase 1, averaging, banking and trading can only occur within and between 

 

60 79 FR 23492, April 28, 2014 and 40 CFR 86.1805-17.
Page 49 of 850

specified “averaging sets” (with the exception of credits generated through use of specified 

advanced technologies). We propose to continue this regime in Phase 2, to retain the existing 

vehicle and engine averaging sets, and create new trailer averaging sets. We also propose to 

continue the averaging set restrictions from Phase 1 in Phase 2. These averaging sets for 

vehicles are:

 Complete pickups and vans

 Other light heavy-duty vehicles (Classes 2b-5)

 Medium heavy-duty vehicles (Class 6-7)

 Heavy heavy-duty vehicles (Class 8)

 Long dry van trailers

 Short dry van trailers

 Long refrigerated trailers

 Short refrigerated trailers

We also propose not to allow trading between engines and chassis, even within the same vehicle 

class. Such trading would essentially result in double counting of emission credits, because the 

same engine technology would likely generate credits relative to both standards. We similarly

would limit trading among engine categories to trades within the designated averaging sets: 

 Spark-ignition engines

 Compression-ignition light heavy-duty engines

 Compression-ignition medium heavy-duty engines

 Compression-ignition heavy heavy-duty engines

The agencies continue to believe that restricting trading to within the same eight classes

would provide adequate opportunities for manufacturers to make necessary technological 

improvements and to reduce the overall cost of the program without compromising overall 

environmental and fuel efficiency objectives, and is therefore appropriate and reasonable under 

EPA’s authority and maximum feasible under NHTSA’s authority, respectively. We do not 

expect emissions from engines and vehicles – when restricted by weight class – to be dissimilar. 

We therefore expect that the lifetime vehicle performance and emissions levels will be very

similar across these defined categories, and the estimated credit calculations will fairly ensure the 

expected fuel consumption and GHG emission reductions. 

We continue to believe, subject to consideration of public comment, that the Phase 1 

averaging sets create the most flexibility that is appropriate without creating an unfair advantage 

for manufacturers with erratically integrated portfolios, including engines and vehicles. See 76 

FR 57240. The agencies committed in Phase 1 to seek public comment after credit trading 

begins with manufacturers certifying in 2014 on whether broader credit trading is more 

appropriate in developing the next phase of HD regulations (76 FR 57128, September 15, 2011). 

The 2014 model year end of year reports will become available to the agencies in mid-2015. 

Therefore, the agencies will provide information at that point. We welcome comment on 

averaging set restrictions. The agencies propose to continue this carry forward provision for 

phase 2 for the same reasons.
Page 50 of 850

(iii) Credit Deficits

The Phase 1 regulations allow manufacturers to carry-forward deficits for up to three 

years without penalty. This is an important flexibility because the program is designed to 

address the diversity of the heavy-duty industry by allowing manufacturers to sell a mix of 

engines or vehicles that have very different emission levels and fuel efficiencies. Under this 

construct, manufacturers can offset sales of engines or vehicles not meeting the standards by

selling others (within the same averaging set) that are much better than required. However, in 

any given year it is possible that the actual sales mix will not balance out and the manufacturer 

may be short of credits for that model year. The three year provision allows for this possibility

and creates additional compliance flexibility to accommodate it.

(iv) Advanced Technology Credits

At this time, the agencies believe it is no longer appropriate to provide extra credit for the 

technologies identified as advanced technologies for Phase 1, although we are requesting 

comment on this issue. The Phase 1 advanced technology credits were adopted to promote the 

implementation of advanced technologies, such as hybrid powertrains, Rankine cycle engines, 

all-electric vehicles, and fuel cell vehicles (see 40 CFR 1037.150(i)). As the agencies stated in 

the Phase 1 final rule, the Phase 1 standards were not premised on the use of advanced 

technologies but we expected these advanced technologies to be an important part of the Phase 2 

rulemaking (76 FR 57133, September 15, 2011). The proposed Phase 2 heavy-duty engine and 

vehicles standards are premised on the use of some advanced technologies, making them 

equivalent to other fuel-saving technologies in this context. We believe the Phase 2 standards 

themselves would provide sufficient incentive to develop them.

We request comment on this issue, especially with respect to electric vehicle, plug-in 

hybrid, and fuel cell technologies. Although the proposed standards are premised on some use of 

Rankine cycle engines and hybrid powertrains, none of the proposed standards are based on 

projected utilization of the use of the other advanced technologies. (Note that the most stringent 

alternative is based on some use of these technologies). Commenters are encouraged to consider 

the recently adopted light-duty program, which includes temporary incentives for these 

technologies. 

(c) Innovative Technology and Off-Cycle Credits

The agencies propose to largely continue the Phase 1 innovative technology program but 

to redesignate it as an off-cycle program for Phase 2. In other words, beginning in MY 2021 

technologies that are not fully accounted for in the GEM simulation tool, or by compliance 

dynamometer testing would be considered “off-cycle”, including those technologies that may no 

longer be considered innovative technologies. However, we are not proposing to apply this 

flexibility to trailers (which were not part of Phase 1) in order to simplify the program for trailer 

manufacturers.

The agencies propose to maintain that, in order for a manufacturer to receive credits for 

Phase 2, the off-cycle technology would still need to meet the requirement that it was not in 

common use prior to MY 2010. Although, we have not identified specific off-cycle technologies 
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at this time that should be excluded, we believe it may be prudent to continue this requirement to 

avoid the potential for manufacturers to receive windfall credits for technologies that they were 

already using before MY 2010. Nevertheless, the agencies seek comment on whether off-cycle 

technologies in the Phase 2 program should be limited in this way. In particular, the agencies are 

concerned that because the proposed Phase 2 program would be implemented MY 2021 and may

extend beyond 2027, the agencies and manufacturers may have difficulty in the future 

determining whether an off-cycle technology was in common use prior to MY 2010. Moreover, 

because we have not identified a single off-cycle technology that should be excluded by this 

provision at this time, we are concerned that this approach may create an unnecessary hindrance 

to the off-cycle program.

Manufacturers would be able to carry over an innovative technology credits from Phase 1

into Phase 2, subject to the same restrictions as other credits. Manufacturers would also be able 

to carry over the improvement factor (not the credit value) of a technology, if certain criteria 

were met. The agencies would require documentation for all off-cycle requests similar to those 

required by EPA for its light-duty GHG program.

Additionally, NHTSA would not grant any off-cycle credits for crash avoidance 

technologies. NHTSA would also require manufacturers to consider the safety of off-cycle 

technologies and would request a safety assessment from the manufacturer for all off-cycle 

technologies. 

The agencies seek comment on these proposed changes, as well as the possibility of 

adopting aspects of the light-duty off-cycle program.

(d) Alternative Fuels

The agencies are proposing to largely continue the Phase 1 approach for engines and 

vehicles fueled by fuels other than gasoline and diesel.61 Phase 1 engine emission standards 

applied uniquely for gasoline-fueled and diesel-fueled engines. The regulations in 40 CFR part 

86 implement these distinctions for alternative fuels by dividing engines into Otto-cycle and 

Diesel-cycle technologies based on the combustion cycle of the engine. The agencies are, 

however, proposing a small change that is described in Section II. Under the proposed change, 

we would require manufacturers to divide their natural gas engines into primary intended service 

classes, like the current requirement for compression-ignition engines. Any alternative fuelengine qualifying as a medium heavy-duty engine or a heavy heavy-duty engine would be 

subject to all the emission standards and other requirements that apply to compression-ignition 

engines. Note that this small change in approach would also apply with respect to EPA’s criteria 

pollutant program.

We are also proposing that the Phase 2 standards apply exclusively at the vehicle tailpipe. 

That is, compliance is based on vehicle fuel consumption and GHG emission reductions, and 

 

61 See Section I. F. (1) (a) for a summary of certain specific changes we are proposing or considering for natural gasfueled engines and vehicles. 
Page 52 of 850

does not reflect any so-called lifecycle emission properties. The agencies have explained why it 

is reasonable that the heavy duty standards be fuel neutral in this manner. See 76 FR 57123; see 

also 77 FR at 51705 (Aug. 24. 2012) and 77 FR at 51500 (Aug. 27, 2012). In particular, EPA 

notes that there is a separate, statutorily-mandated program under the Clean Air Act which 

encourages use of renewable fuels in transportation fuels, including renewable fuel used in 

heavy-duty diesel engines. This program considers lifecycle greenhouse gas emissions 

compared to petroleum fuel. NHTSA notes that the fuel efficiency standards are necessarily

tailpipe-based, and that a lifecycle approach would likely render it impossible to harmonize the 

fuel efficiency and GHG emission standards, to the great detriment of our goal of achieving a 

coordinated program. 77 FR 51500-501; see also 77 FR 51705 (similar finding by EPA); see 

also section I.F. (1) (a) below. 

One consequence of the tailpipe-based approach is that the agencies are proposing to treat 

vehicles powered by electricity the same as in Phase 1. In Phase 1, EPA treated all electric 

vehicles as having zero emissions of CO2, CH4, and N2O (see 40 CFR 1037.150(f)). Similarly, 

NHTSA adopted regulations in Phase 1 that set the fuel consumption standards based on the fuel 

consumed by the vehicle. The agencies also did not require emission testing for electric vehicles 

in Phase 1. The agencies considered the potential unintended consequence of not accounting for 

upstream emissions from the charging of heavy-duty electric vehicles. In our reassessment for 

Phase 2, we have not found any all-electric heavy-duty vehicles that have certified by 2014. As 

we look to the future, we project very limited adoption of all-electric vehicles into the market. 

Therefore, we believe that this provision is still appropriate. Unlike the 2017-2025 light-duty 

rule, which included a cap whereby upstream emissions would be counted after a certain volume 

of sales (see 77 FR 62816-62822), we believe there is no need to propose a cap for heavy-duty 

vehicles because of the small likelihood of significant production of EV technologies in the 

Phase 2 timeframe. We welcome comments on this approach. 62 Note that we also request 

comment on upstream emissions for natural gas in Section XI. 

(e) Phase 1 Interim Provisions

EPA adopted several flexibilities for the Phase 1 program (40 CFR 1036.150 and 

1037.150) as interim provisions. Because the existing regulations do not have an end date for 

Phase 1, most of these provisions did not have an explicit end date. NHTSA adopted similar 

provisions. With few exceptions, the agencies are proposing not to apply these provisions to 

Phase 2. These will generally remain in effect for the Phase 1 program. In particular, the 

agencies note that we do not propose to continue the blanket exemption for small manufacturers. 

Instead, the agencies propose to adopt narrower and more targeted relief.

(2) Proposed Phase 2 Standards

This section briefly summarizes the proposed Phase 2 standards for each category and 

identifies the technologies that the agencies project would be needed to meet the standards. 

 

62 See also Section I. C. (1) (b)(iv) above (soliciting comment on need for advanced technology incentive credits for 

heavy duty EVs).
Page 53 of 850

Given the large number of different regulatory categories and model years for which separate 

standards are being proposed, the actual numerical standards are not listed. Readers are referred 

to Sections II through IV for the tables of proposed standards.

(a) Summary of the Proposed Engine Standards

The agencies are proposing to continue the basic Phase 1 structure for the Phase 2 engine 

standards. There would be separate standards and test cycles for tractor engines, vocational 

diesel engines, and vocational gasoline engines. However, as described in Section II, we are 

proposing a revised test cycle for tractor engines to better reflect actual in-use operation.

For diesel engines, the agencies are proposing standards for MY 2027 requiring reduction 

in CO2 emissions and fuel consumption of 4.2 percent better than the 2017 baseline. 63 We are 

also proposing standards for MY 2021 and MY 2024, requiring reductions in CO2 emissions and 

fuel consumption of 1.5 to 3.7 percent better than the 2017 baseline. The agencies project that 

these reductions would be feasible based on technological changes that would improve 

combustion and reduce energy losses. For most of these improvements, the agencies project 

manufacturers will begin applying them to about 50 percent of their heavy-duty engines by 2021, 

and ultimately apply them to about 90 percent of their heavy-duty engines by 2024. However, 

for some of these improvements we project more limited application rates. In particular, we 

project a more limited use of waste exhaust heat recovery systems in 2027, projecting that about 

10 percent of tractor engines will have turbo-compounding systems, and an additional 15 percent 

of tractor engines would employ Rankine-cycle waste heat recovery. We do not project that 

turbo-compounding or Rankine-cycle waste heat recovery technology will be utilized in 

vocational engines. Although we see great potential for waste heat recovery systems to achieve 

significant fuel savings and CO2 emission reductions, we are not projecting that the technology

could be available for more wide-spread use in this time frame. 

For gasoline vocational engines, we are not proposing new more stringent engine

standards. Gasoline engines used in vocational vehicles are generally the same engines as are 

used in the complete HD pickups and vans in the Class 2b and 3 weight categories. Given the 

relatively small sales volumes for gasoline-fueled vocational vehicles, manufacturers typically 

cannot afford to invest significantly in developing separate technology for these vocational 

vehicle engines. Thus, we project that vocational gasoline engines would include the same 

technology as would be used to meet the pickup and van chassis standards, and this would result 

in some real world reductions in CO2 emissions and fuel consumption. Although it is difficult at

this time to project how much improvement would be observed during certification testing, it 

seems likely that these improvements would reduce measured CO2 emissions and fuel 

consumption by about one percent. Therefore, we are requesting comment on finalizing a Phase 

2 standard of 621 g/hp-hr for gasoline engines (i.e., one percent more stringent than the 2016 

Phase 1 standard of 627 g/hp-hr) in MY 2027. We note that the proposed MY 2027 vehicle 

standards for gasoline-fueled vocational vehicles are predicated in part on the use of advanced 

 

63 Phase 1 standards for diesel engines will be fully phased-in by MY 2017. 
Page 54 of 850

friction reduction technology with effectiveness over the GEM cycles of about one percent. We 

also request comment on whether not proposing more stringent standards for gasoline engines 

would create an incentive for purchasers who would have otherwise chosen a diesel vehicle to 

instead choose a gasoline vehicle.
Page 55 of 850

Table I-2 Summary of Phase 1 and Proposed Phase 2 Requirements for Engines in Combination Tractors and 

Vocational Vehicles

Phase 1 Program Alternative 3 - 2027 

(proposed standard)

Alternative 4 – 2024 (also 

under consideration)

Covered in this 

category 

Engines installed in tractors and vocational chassis.

Share of HDV fuel 

consumption and GHG 

emissions

Combination tractors and vocational vehicles account for approximately 85 percent of fuel use 

and GHG emissions in the medium and heavy duty truck sector.

Per vehicle fuel 

consumption and CO2

improvement 

5%-9% improvement over MY

2010 baseline, depending 

vehicle application. 

Improvements are in addition to 

improvements from tractor and 

vocational vehicle standards.

4% improvement over MY 2017 for diesel engines. Note that 

improvements are captured in complete vehicle tractor and

vocational vehicle standards, so that engine improvements 

and the vehicle improvement shown below are not additive.

Form of the standard EPA: CO2 grams/horsepower-hour and NHTSA: gallons of fuel/horsepower-hour

Example technology 

options available to 

help manufacturers 

meet standards 

Combustion, air handling, 

friction and emissions aftertreatment technology 

improvements

Further technology improvements and increased use of all 

Phase 1 technologies, plus waste heat recovery systems for 

tractor engines (e.g., turbo-compound and Rankine-cycle)

Flexibilities ABT program which allows 

emissions and fuel consumption 

credits to be averaged, banked, 

or traded (five year credit 

life). Manufacturers allowed to 

carry-forward credit deficits for 

up to three model years. Interim 

incentives for advanced 

technologies, recognition of 

innovative (off-cycle) 

technologies not accounted for 

by the HD Phase 1 test 

procedures, and credits for 

certifying early.

Same as Phase 1, except no advanced technology incentives. 

Adjustment factor of 1.36 proposed for credits carried 

forward from Phase 1 to Phase 2 for SI and LHD CI engines 

due to proposed change in useful life.

(b) Summary of the Proposed Tractor Standards 

As explained in Section III, the agencies are proposing to largely continue the Phase 1

tractor program but to propose new standards. The tractor standards proposed for MY 2027 

would achieve up to 24 percent lower CO2 emissions and fuel consumption than a 2017 model 

year Phase 1 tractor. The agencies project that the proposed 2027 tractor standards could be met 

through improvements in the:
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 Engine64 (including some use of waste heat recovery systems)

 Transmission

 Driveline

 Aerodynamic design

 Tire rolling resistance

 Idle performance

 Other accessories of the tractor. 

The agencies’ evaluation shows that some of these technologies are available today, but 

have very low adoption rates on current vehicles, while others will require some lead time for 

development. The agencies are proposing to enhance the GEM vehicle simulation tool to 

recognize these technologies, as described in Section II.C.

We have also determined that there is sufficient lead time to introduce many of these 

tractor and engine technologies into the fleet at a reasonable cost starting in the 2021 model year. 

The proposed 2021 model year standards for combination tractors and engines would achieve up 

to 13 percent lower CO2 emissions and fuel consumption than a 2017 model year Phase 1 tractor, 

and the 2024 model year standards would achieve up to 20 percent lower CO2 emissions and fuel 

consumption.

 

64 Although the agencies are proposing separate engine standards and separate engine certification, engine 

improvements would also be reflected in the vehicle certification process. Thus, it is appropriate to also consider 

engine improvements in the context of the vehicle standards.
Page 57 of 850

Table I-3 Summary of Phase 1 and Proposed Phase 2 Requirements for Class 7 and Class 8 Combination 

Tractors

Phase 1 Program Alternative 3 - 2027 

(proposed standard)

Alternative 4 – 2024 (also 

under consideration)

Covered in this 

category 

Tractors that are designed to pull trailers and move freight.

Share of HDV fuel 

consumption and GHG 

emissions

Combination tractors and their engines account for approximately two thirds of fuel use and GHG 

emissions in the medium and heavy duty truck sector.

Per vehicle fuel 

consumption and CO2

improvement 

10%-23% improvement over MY 

2010 baseline, depending on 

tractor category. Improvements 

are in addition to improvements 

from engine standards.

18%-24% improvement over MY 2017 standards

Form of the standard EPA: CO2 grams/ton payload mile and NHTSA: gallons of fuel/1,000 ton payload mile

Example technology 

options available to 

help manufacturers 

meet standards 

Aerodynamic drag 

improvements; low rolling 

resistance tires; high strength 

steel and aluminum weight 

reduction; extended idle 

reduction; and speed limiters

Further technology improvements and increased use of all 

Phase 1 technologies, plus engine improvements, improved 

and automated transmissions and axles, powertrain 

optimization, tire inflation systems, and predictive cruise 

control (depending on tractor type)

Flexibilities ABT program which allows 

emissions and fuel consumption 

credits to be averaged, banked, or 

traded (five year credit 

life). Manufacturers allowed to 

carry-forward credit deficits for 

up to three model years. Interim 

incentives for advanced 

technologies, recognition of 

innovative (off-cycle) 

technologies not accounted for by 

the HD Phase 1 test procedures, 

and credits for certifying early.

Same as Phase 1, except no extra credits for advanced 

technologies or early certification.

(c) Summary of the Proposed Trailer Standards 

This NPRM proposes a set of GHG emission and fuel consumption standards for 

manufacturers of new trailers that are used in combination with tractors that would significantly 

reduce CO2 and fuel consumption from combination tractor-trailers nationwide over a period of 

several years. As described in Section IV, there are numerous aerodynamic and tire technologies 

available to manufacturers to accomplish these proposed standards. For the most part, these 

technologies have already been introduced into the market to some extent through EPA’s 

voluntary SmartWay program. However, adoption is still somewhat limited. 

The agencies are proposing incremental levels of Phase 2 standards that would apply

beginning in MY 2018 and be fully phased-in by 2027. These standards are predicated on use of 
Page 58 of 850

aerodynamic and tire improvements, with trailer OEMs making incrementally greater 

improvements in MYs 2021 and 2024 as standard stringency increases in each of those model 

years. EPA’s GHG emission standards would be mandatory beginning in MY 2018, while 

NHTSA’s fuel consumption standards would be voluntary beginning in MY 2018, and be 

mandatory beginning in MY 2021. 

As described in Section XV.D and Chapter 12 of the draft RIA, the agencies are 

proposing special provisions to minimize the impacts on small trailer manufacturers. These 

provisions have been informed by and are largely consistent with recommendations coming from 

the SBAR Panel that EPA conducted pursuant to Section 609(b) of the Regulatory Flexibility

Act (RFA). Broadly, these provisions provide additional lead time for small manufacturers, as 

well as simplified testing and compliance requirements. The agencies are also requesting 

comment on whether there is a need for additional provisions to address small business issues.
Page 59 of 850

Table I-4 Summary of Proposed Phase 2 Requirements for Trailers

Phase 1 Program Alternative 3 - 2027 

(proposed standard)

Alternative 4 – 2024 (also under 

consideration)

Covered in this category Trailers hauled by low, mid, and high roof day and sleeper cab tractors, except those qualified as 

logging, mining, stationary or heavy-haul.

Share of HDV fuel 

consumption and GHG 

emissions

Trailers are modeled together with combination tractors and their engines. Together, they 

account for approximately two thirds of fuel use and GHG emissions in the medium and heavy 

duty truck sector.

Per vehicle fuel 

consumption and CO2

improvement 

N/A Between 3% and 8% improvement over MY 2017 baseline, 

depending on the trailer type.

Form of the standard N/A EPA: CO2 grams/ton payload mile and NHTSA: gallons /1,000 ton 

payload mile

Example technology 

options available to help 

manufacturers meet 

standards 

N/A Low rolling resistance tires, automatic tire inflation systems, 

weight reduction for most trailers, aerodynamic improvements such 

as side and rear fairings, gap closing devices, and undercarriage 

treatment for box-type trailers (e.g., dry and refrigerated vans) 

Flexibilities N/A One year delay in implementation for small businesses, trailer 

manufacturers may use pre-approved devices to avoid testing, 

averaging program for manufacturers of dry and refrigerated box 

trailers

(d) Summary of the Proposed Vocational Vehicle Standards 

As explained in Section V, the agencies are proposing to revise the Phase 1 vocational 

vehicle program and to propose new standards. These proposed standards also reflect further 

sub-categorization from Phase 1, with separate proposed standards based on mode of operation: 

urban, regional, and multi-purpose. The agencies are also proposing alternative standards for 

emergency vehicles. 

The agencies project that the proposed vocational vehicle standards could be met through 

improvements in the engine, transmission, driveline, lower rolling resistance tires, workday idle 

reduction technologies, and weight reduction, plus some application of hybrid technology. 

These are described in Section V of this preamble and in Chapter 2.9 of the draft RIA. These

MY 2027 standards would achieve up to 16 percent lower CO2 emissions and fuel consumption 

than MY 2017 Phase 1 standards. The agencies are also proposing revisions to the compliance 

regime for vocational vehicles. These include: the addition of an idle cycle that would be 

weighted along with the other drive cycles; and revisions to the vehicle simulation tool to reflect 

specific improvements to the engine, transmission, and driveline. 

Similar to the tractor program, we have determined that there is sufficient lead time to 

introduce many of these new technologies into the fleet starting in MY 2021. Therefore, we are 

proposing new standards for MY 2021 and 2024. Based on our analysis, the MY 2021 standards 

for vocational vehicles would achieve up to 7 percent lower CO2 emissions and fuel consumption 

than a MY 2017 Phase 1 vehicle, on average, and the MY 2024 standards would achieve up to 11 

percent lower CO2 emissions and fuel consumption.

In Phase 1, EPA adopted air conditioning (A/C) refrigerant leakage standards for tractors, 

as well as for heavy-duty pickups and vans, but not for vocational vehicles. For Phase 2, EPA 
Page 60 of 850

believes that it would be feasible to apply similar A/C refrigerant leakage standards for

vocational vehicles, beginning with the 2021 model year. The process for certifying that low 

leakage components are used would follow the system currently in place for comparable systems 

in tractors.
Page 61 of 850

Table I-5 Summary of Phase 1 and Proposed Phase 2 Requirements for Vocational Vehicle Chassis

Phase 1 Program Alternative 3 - 2027 

(proposed standard)

Alternative 4 – 2024 (also 

under consideration)

Covered in this 

category 

Class 2b – 8 chassis that are intended for vocational services such as delivery vehicles, emergency 

vehicles, dump truck, tow trucks, cement mixer, refuse trucks, etc., except those qualified as offhighway vehicles.

Because of sector diversity, vocational vehicle chassis are segmented into Light, Medium and 

Heavy Duty vehicle categories and for Phase 2 each of these segments are further subdivided 

using three duty cycles: Regional, Multi-purpose, and Urban.

Share of HDV fuel 

consumption and GHG 

emissions

Vocational vehicles account for approximately 20 percent of fuel use and GHG emissions in the 

medium and heavy duty truck sector categories 

Per vehicle fuel 

consumption and CO2

improvement

2% improvement over MY 

2010 baseline.

Improvements are in addition 

to improvements from engine

standards.

Up to 16% improvement over MY 2017 standards

Form of the standard EPA: CO2 grams/ton payload mile and NHTSA: gallons of fuel/1,000 ton payload mile 

Example technology 

options available to 

help manufacturers 

meet standards 

Low rolling resistance tires Further technology improvements and increased use of Phase 1 

technologies, plus improved engines, transmissions and axles, 

powertrain optimization, weight reduction, hybrids, and 

workday idle reduction systems.

Flexibilities ABT program which allows 

emissions and fuel 

consumption credits to be 

averaged, banked, or traded

(five year credit 

life). Manufacturers allowed to 

carry-forward credit deficits for 

up to three model 

years. Interim incentives for 

advanced technologies, 

recognition of innovative (offcycle) technologies not 

accounted for by the HD Phase 

1 test procedures, and credits 

for certifying early.

Same as Phase 1, except no advanced technology incentives. 

Chassis intended for emergency vehicles have proposed Phase 

2 standards based only on Phase 1 technologies, and may 

continue to certify using a simplified Phase 1-style GEM tool.

Adjustment factor of 1.36 proposed for credits carried forward 

from Phase 1 to Phase 2 due to proposed change in useful life.

(e) Summary of the Proposed Heavy-Duty Pickup and Van Standards 

The agencies are proposing to adopt new Phase 2 GHG emission and fuel consumption 

standards for heavy-duty pickups and vans that would be applied in largely the same manner as 

the Phase 1 standards. These standards are based on the extensive use of most known and 

proven technologies, and could result in some use of strong hybrid powertrain technology. 

These proposed standards would commence in MY 2021. Overall, the proposed standards are 16

percent more stringent by 2027.
Page 62 of 850

Table I-6 Summary of Phase 1 and Proposed Phase 2 Requirements for HD Pickups and Vans

Phase 1 Program Alternative 3 - 2027 

(proposed standard)

Alternative 4 – 2025 (also under 

consideration)

Covered in this 

category 

Class 2b and 3 complete pickup trucks and vans, including all work vans and 15-passenger vans 

but excluding 12-passenger vans which are subject to light-duty standards.

Share of HDV fuel 

consumption and GHG 

emissions

HD pickups and vans account for approximately 15% of fuel use and GHG emissions in the 

medium and heavy duty truck sector.

Per vehicle fuel 

consumption and CO2

improvement 

15% improvement over MY 2010 

baseline for diesel vehicles, and 10% 

improvement for gasoline vehicles

16% improvement over MY 2018-2020 standards

Form of the standard Phase 1 standards are based upon a “work factor” attribute that combines truck payload and towing 

capabilities, with an added adjustment for 4-wheel drive vehicles. There are separate target curves 

for diesel-powered and gasoline-powered vehicles. As proposed, the Phase 2 standards would be 

based on the same approach.

Example technology 

options available to 

help manufacturers 

meet standards 

Engine improvements, transmission 

improvements, aerodynamic drag 

improvements, low rolling resistance 

tires, weight reduction, and improved 

accessories.

Further technology improvements and increased use of all 

Phase 1 technologies, plus engine stop-start, and 

powertrain hybridization (mild and strong).

Flexibilities Two optional phase-in schedules; 

ABT program which allows 

emissions and fuel consumption 

credits to be averaged, banked, or 

traded (five year credit 

life). Manufacturers allowed to 

carry-forward credit deficits for up to 

three model years. Interim 

incentives for advanced technologies, 

recognition of innovative (off-cycle) 

technologies not accounted for by the 

HD Phase 1 test procedures, and 

credits for certifying early.

Proposed to be same as Phase 1, with phase-in schedule 

based on year-over-year increase in stringency. 

Adjustment factor of 1.25 proposed for credits carried 

forward from Phase 1 to Phase 2 due to proposed change 

in useful life. Proposed cessation of advanced technology 

incentives in 2021 and continuation of off-cycle credits.

(f) Summary of the Proposed Final Numeric Standards by Regulatory Subcategory

Table I-7 lists the proposed final (i.e., MY 2027) numeric standards by regulatory

subcategory for tractors, trailers, vocational vehicles and engines. Note that these are the same 

final numeric standards for Alternative 4, but for Alternative 4 these would be implemented in 

MY 2024 instead of MY 2027.

Table I-7 Proposed Final (MY 2027) Numeric Standards by Regulatory Subcategory
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Regulatory Subcategory CO2 Grams per TonMile (for engines 

CO2 Grams per Brake 

Horsepower-Hour)

Fuel Consumption 

gallon per 1,000 tonmile (for engines 

gallons per 100 Brake 

Horsepower-Hour

Tractors

Class 7 Low Roof Day 

Cab 87 8.5462

Class 7 Mid Roof Day 

Cab 96 9.4303

Class 7 High Roof Day 

Cab 96 9.4303

Class 8 Low Roof Day 

Cab 70 6.8762

Class 8 Mid Roof Day 

Cab 76 7.4656

Class 8 High Roof Day 

Cab 76 7.4656

Class 8 Low Roof 

Sleeper Cab 62 6.0904

Class 8 Mid Roof 

Sleeper Cab 69 6.7780

Class 8 High Roof 

Sleeper Cab 67 6.5815

Trailers

Long Dry Box Trailer 77 7.5639

Short Dry Box Trailer 140 13.7525

Long Refrigerated Box 

Trailer 80 7.8585

Short Refrigerated Box 

Trailer 144 14.1454

Vocational Diesel

LHD Urban 272 26.7191

LHD Multi-Purpose 280 27.5049

LHD Regional 292 28.6837

MHD Urban 172 16.8959

MHD Multi-Purpose 174 17.0923

MHD Regional 170 16.6994

HHD Urban 182 17.8782

HHD Multi-Purpose 183 17.9764

HHD Regional 174 17.0923

Vocational Gasoline

LHD Urban 299 33.6446

LHD Multi-Purpose 308 34.6574

LHD Regional 321 36.1202

MHD Urban 189 21.2670
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MHD Multi-Purpose 191 21.4921

MHD Regional 187 21.0420

HHD Urban 196 22.0547

HHD Multi-Purpose 198 22.2797

HHD Regional 188 21.1545

Diesel Engines

LHD Vocational 553 5.4322

MHD Vocational 553 5.4322

HHD Vocational 533 5.2358

MHD Tractor 466 4.5776

HHD Tractor 441 4.3320

Similar to Phase 1 the agencies are proposing for Phase 2 a set of continuous equationbased standards for HD pickups and vans. Please refer to Section 6, subsection B.1, for a 

description of these standards, including associated tables and figures.

D. Summary of the Costs and Benefits of the Proposed Rule

This section summarizes the projected costs and benefits of the proposed NHTSA fuel 

consumption and EPA GHG emission standards, along with those of Alternative 4. These 

projections helped to inform the agencies’ choices among the alternatives considered, along with 

other relevant factors, and NHTSA’s Draft Environmental Impact Statement (DEIS). See 

Sections VII through IX and the Draft RIA for additional details about these projections.

For this rule, the agencies conducted coordinated and complementary analyses using two 

analytical methods for the heavy-duty pickup and van segment by employing both DOT’s CAFE 

model and EPA’s MOVES model. The agencies used EPA’s MOVES model to estimate fuel 

consumption and emissions impacts for tractor-trailers (including the engine that powers the 

tractor), and vocational vehicles (including the engine that powers the vehicle). Additional 

calculations were performed to determine corresponding monetized program costs and benefits. 

For heavy-duty pickups and vans, the agencies performed complementary analyses, which we 

refer to as “Method A” and “Method B.” In Method A, the CAFE model was used to project a 

pathway the industry could use to comply with each regulatory alternative and the estimated 

effects on fuel consumption, emissions, benefits and costs. In Method B, the CAFE model was 

used to project a pathway the industry could use to comply with each regulatory alternative, 

along with resultant impacts on per vehicle costs, and the MOVES model was used to calculate 

corresponding changes in total fuel consumption and annual emissions. Additional calculations 

were performed to determine corresponding monetized program costs and benefits. NHTSA 

considered Method A as its central analysis and Method B as a supplemental analysis. EPA 

considered the results of both methods. The agencies concluded that both methods led the 

agencies to the same conclusions and the same selection of the proposed standards. See Section 

VII for additional discussion of these two methods. 
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(1) Reference Case against Which Costs and Benefits are Calculated

The No Action Alternative for today’s analysis, alternatively referred to as the “baseline” 

or “reference case,” assumes that the agencies would not issue new rules regarding MD/HD fuel 

efficiency and GHG emissions. This is the baseline against which costs and benefits for the 

proposed standards are calculated. The reference case assumes that model year 2018 standards 

would be extended indefinitely and without change.

The agencies recognize that if the proposed rule is not adopted, manufacturers will 

continue to introduce new heavy-duty vehicles in a competitive market that responds to a range 

of factors. Thus manufacturers might have continued to improve technologies to reduce heavyduty vehicle fuel consumption. Thus, as described in Section VII, both agencies fully analyzed 

the proposed standards and the regulatory alternatives against two reference cases. The first case 

uses a baseline that projects very little improvement in new vehicles in the absence of new Phase 

2 standards, and the second uses a more dynamic baseline that projects more significant 

improvements in vehicle fuel efficiency. NHTSA considered its primary analysis to be based on 

the more dynamic baseline, where certain cost-effective technologies are assumed to be applied 

by manufacturers to improve fuel efficiency beyond the Phase 1 requirements in the absence of 

new Phase 2 standards. EPA considered both reference cases. The results for all of the 

regulatory alternatives relative to both reference cases, derived via the same methodologies 

discussed in this section, are presented in Section X of the preamble.

The agencies chose to analyze these two different baselines because the agencies

recognize that there are a number of factors that create uncertainty in projecting a baseline 

against which to compare the future effects of the proposed action and the remaining 

alternatives. The composition of the future fleet—such as the relative position of individual 

manufacturers and the mix of products they each offer—cannot be predicted with certainty at this 

time. Additionally, the heavy-duty vehicle market is diverse, as is the range of vehicle 

purchasers. Heavy-duty vehicle manufacturers have reported that their customers’ purchasing 

decisions are influenced by their customers’ own determinations of minimum total cost of 

ownership, which can be unique to a particular customer’s circumstances. For example, some 

customers (e.g., less-than-truckload or package delivery operators) operate their vehicles within a 

limited geographic region and typically own their own vehicle maintenance and repair centers 

within that region. These operators tend to own their vehicles for long time periods, and 

sometimes for the entire service life of the vehicle. Their total cost of ownership is influenced by 

their ability to better control their own maintenance costs, and thus they can afford to consider

fuel efficiency technologies that have longer payback periods, outside of the vehicle 

manufacturer’s warranty period. Other customers (e.g. truckload or long-haul operators) tend to 

operate cross-country, and thus must depend upon truck dealer service centers for repair and 

maintenance. Some of these customers tend to own their vehicles for about four to seven years, 

so that they typically do not have to pay for repair and maintenance costs outside of either the 

manufacturer’s warranty period or some other extended warranty period. Many of these 

customers tend to require seeing evidence of fuel efficiency technology payback periods on the 

order of 18 to 24 months before seriously considering evaluating a new technology for potential 

adoption within their fleet (NAS 2010, Roeth et al. 2013, Klemick et al. 2014). Purchasers of 

HD pickups and vans wanting better fuel efficiency tend to demand that fuel consumption 

improvements pay back within approximately one to three years, but some HD pickup and van 
Page 66 of 850

owners accrue relatively few vehicle miles traveled per year, such that they may be less likely to 

adopt new fuel efficiency technologies, while other owners who use their vehicle(s) with greater 

intensity may be even more willing to pay for fuel efficiency improvements. Regardless of the 

type of customer, their determination of minimum total cost of ownership involves the customer 

balancing their own unique circumstances with a heavy-duty vehicle’s initial purchase price, 

availability of credit and lease options, expectations of vehicle reliability, resale value and fuel 

efficiency technology payback periods. The degree of the incentive to adopt additional fuel 

efficiency technologies also depends on customer expectations of future fuel prices, which 

directly impacts customer payback periods. Purchasing decisions are not based exclusively on 

payback period, but also include the considerations discussed above and in Section X.A.1. For 

the baseline analysis, the agencies use payback period as a proxy for all of these considerations, 

and therefore the payback period for the baseline analysis is shorter than the payback period 

industry uses as a threshold for the further consideration of a technology. The agencies request 

comment on the appropriateness of these reference cases. See Section X.A.1of this Preamble and 

Chapter 11 of the draft RIA for a more detailed discussion of baselines.

As part of a sensitivity analysis, additional baseline scenarios were also evaluated for HD 

pickups and vans. See Section VI of this Preamble and Chapter 10 of the draft RIA for a detailed 

discussion of these additional scenarios. 

(2) Costs and Benefits Projected for the Standards Being Proposed and Alternative 4

The tables below summarize the benefits and costs for the program in two ways: first, 

from the perspective of a program designed to improve the Nation’s energy security and to 

conserve energy by improving fuel efficiency and then from the perspective of a program 

designed to reduce GHG emissions. The individual categories of benefits and costs presented in 

the tables below are defined more fully and presented in more detail in Chapter 8 of the draft 

RIA. 

Table I-8 shows benefits and costs for the proposed standards and Alternative 4 from the 

perspective of a program designed to improve the Nation’s energy security and conserve energy

by improving fuel efficiency. From this viewpoint, technology costs occur when the vehicle is 

purchased. Fuel savings are counted as benefits that occur over the lifetimes of the vehicles 

produced during the model years subject to the Phase 2 standards as they consume less fuel.
Page 67 of 850

Table I-8 Lifetime Fuel Savings, GHG Reductions, Benefits, Costs and Net Benefits for Model Years 2018 -

2029 Vehicles Using Analysis Method A (Billions of 2012$) a, b

Category Alternative

3 

Preferred

4

3% 

Discount 

Rate

7% 

Discount 

Rate

3% 

Discount 

Rate

7% 

Discount 

Rate

Fuel Reductions (Billion Gallons) 72.2 –76.7 81.9 – 86.7

GHG reductions (MMT CO2 eq) 990 – 1,050 1,110 – 1,180

Vehicle Program: Technology and 

Indirect Costs, Normal Profit on 

Additional Investments

25.0 ‒ 

25.4

16.8 ‒ 

17.1

32.9 ‒ 

34.3

22.5 ‒ 

23.5

Additional Routine Maintenance 1.0 ‒ 1.1 0.6 ‒ 0.6 1.0 ‒ 1.1 0.6 ‒ 0.7

Congestion, Accidents, and Noise from 

Increased Vehicle Use

4.5 ‒ 4.7 2.6 ‒ 2.8 4.7 ‒ 4.9 2.7 ‒ 2.8

 Total Costs 30.5 ‒ 

31.1

20.0 ‒ 

20.5

38.7 ‒ 

40.8

25.8 ‒ 

27.0

Fuel Savings (valued at pre-tax prices) 165.1 ‒ 

175.1

89.2 ‒ 

94.2

187.4 ‒ 

198.3

102.0 ‒ 

107.5

Savings from Less Frequent Refueling 2.9 ‒ 3.1 1.5 ‒ 1.6 3.4 ‒ 3.6 1.8 ‒ 2.0

Economic Benefits from Additional 

Vehicle Use

14.7 ‒ 

15.1

8.2 ‒ 8.4 15.0 ‒ 

15.4

8.4 ‒ 8.6

Reduced Climate Damages from GHG 

Emissions c

32.9 ‒ 

34.9

32.9 ‒ 

34.9

37.3 ‒ 

39.4

37.3 ‒ 

39.4

Reduced Health Damages from NonGHG Emissions37.2 ‒ 

38.8

20 ‒ 20.7 40.9 ‒ 

42.5

22.1 ‒ 

22.8

Increased U.S. Energy Security 8.1 ‒ 8.9 4.3 ‒ 4.7 9.3 ‒ 10.2 5.0 ‒ 5.5

 Total Benefits 261 ‒ 276 156 ‒ 165 293 ‒ 309 177 ‒ 186

 Net Benefits 231 ‒ 245 136 ‒ 144 255 ‒ 269 151 ‒ 159

Notes:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

b Range reflects two reference case assumptions 1a and 1b. 

c Benefits and net benefits use the 3 percent global average SCC value applied only to CO2 emissions; GHG 

reductions include CO2, CH4, N2O and HFC reductions, and include benefits to other nations as well as the U.S. See 

Draft RIA Chapter 8.5 and Preamble Section IX.G for further discussion.

Table I-9 shows benefits and cost from the perspective of reducing GHG. 

Table I-9 Lifetime Fuel Savings, GHG Reductions, Benefits, Costs and Net Benefits for Model Years 

2018 - 2029 Vehicles Using Analysis Method B (Billions of 2012$) a, b
Page 68 of 850

Category Alternative

3 

Preferred

4

3% 

Discount 

Rate

7% 

Discount 

Rate

3% 

Discount 

Rate

7% 

Discount 

Rate

Fuel Reductions (Billion Gallons) 70.2 to 75.8 79.7 to 85.4

GHG reductions (MMT CO2eq) 960 to 1,040 1090 to 1,160

Vehicle Program (e.g., technology and 

indirect costs, normal profit on 

additional investments)

-$24.6 to -

$25.1

-$16.3 to -

$16.6

-$33.1 to -

$33.5

-$22.2 to -

$22.5

Additional Routine Maintenance -$1.1 to -

$1.1

-$0.6 to -

$0.6

-$1.1 to -

$1.1

-$0.6 to -

$0.6

Fuel Savings (valued at pre-tax prices) $159 to 

$171

$84.2 to 

$90.1

$181 to 

$193

$96.5 to 

$103

Energy Security $8.5 to $9.3 $4.4 to $4.8 $9.8 to 

$10.6

$5.2 to $5.6

Congestion, Accidents, and Noise from 

Increased Vehicle Use

-$4.2 to -

$4.3

-$2.4 to -

$2.4

-$4.2 to -

$4.3

-$2.4 to -

$2.4

Savings from Less Frequent Refueling $2.8 to $3.1 $1.4 to $1.6 $3.3 to $3.6 $1.7 to $1.9

Economic Benefits from Additional 

Vehicle Use

$14.8 to 

$14.9

$8.2 to $8.2 $14.7 to 

$14.8

$8.1 to $8.1

Benefits from Reduced Non-GHG 

Emissions c

$37.4 to 

$39.7

$17.7 to 

$18.8

$41.2 to 

$43.5

$19.7 to 

$20.7

Reduced Climate Damages from GHG 

Emissions d

$31.6 to $34.0 $35.9 to $38.3

 Net Benefits $224 to 

$242

$128 to 

$138

$248 to 

$265

$142 to 

$152

Notes:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

b Range reflects two baseline assumptions 1a and 1b. 

c Range reflects both the two baseline assumptions 1a and 1b using the mid-point of the low and high $/ton

estimates for calculating benefits.

cd Benefits and net benefits use the 3 percent average SCCO2 value applied only to CO2 emissions; GHG reductions 

include CO2, CH4 and N2O reductions. 

Table I-10 breaks down by vehicle category the benefits and costs for the proposed 

standards and Alternative 4 using the Method A analytical approach. For additional detail on pervehicle break-downs of costs and benefits, please see Chapter 10.

Table I-10 Per Vehicle Category Lifetime Fuel Savings, GHG Reductions, Benefits, Costs and Net Benefits for 

Model Years 2018 - 2029 Vehicles Using Analysis Method A (Billions of 2012$), Relative to Baseline 1b a
Page 69 of 850

Key Costs and Benefits

by Vehicle Category

Alternative

3 

Preferred

4

3% 

Discount 

Rate

7% 

Discount 

Rate

3% 

Discount 

Rate

7% 

Discount 

Rate

Tractors, Including Engines, and Trailers

Fuel Reductions (Billion Gallons) 56.1 61.6

GHG Reductions (MMT CO2 eq) 731.1 803.1

Total Costs 15.2 10.0 17.7 11.9

Total Benefits 177.8 105.4 194.2 115.7

Net Benefits 162.6 95.4 176.5 103.9

Vocational Vehicles, Including Engines

Fuel Reductions (Billion Gallons) 8.3 10.9

GHG Reductions (MMT CO2 eq) 107.0 139.8

Total Costs 9.5 6.1 12.8 8.4

Total Benefits 27.7 16.0 35.0 20.6

Net Benefits 18.1 9.9 22.1 12.1

HD Pickups and Vans

Fuel Reductions (Billion Gallons) 7.8 9.3

GHG Reductions (MMT CO2 eq) 94.1 112.8

Total Costs 5.5 3.7 7.8 5.3

Total Benefits 23.5 14.1 28.3 17.1

Net Benefits 18.0 10.5 20.4 11.9

Notes:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table I-11 Per Vehicle Costs Relative to Baseline 1a

3

Proposed Standards

4

MY 

2021

MY 2024 MY 2027 MY 2021 MY 2024

Per Vehicle Cost ($)a

 Tractors $6,710 $9,940 $11,700 $10,200 $12,400

 Trailers $900 $1,010 $1,170 $1,080 $1,230

 Vocational Vehicles $1,150 $1,770 $3,380 $1,990 $3,590

 Pickups/Vans $520 $950 $1,340 $1,050 $1,730

Note:
Page 70 of 850

a Per vehicle costs include new engine and vehicle technology only; costs associated with increased insurance, taxes 

and maintenance are included in the payback period values.

An important metric to vehicle purchasers is the payback period that can be expected on 

any new purchase. In other words, there is greater willingness to pay for new technology if that 

new technology “pays back” within an acceptable period of time. The agencies make no effort 

to define the acceptable period of time, but seek to estimate the payback period for others to 

make the decision themselves. The payback period is the point at which reduced fuel 

expenditures outpace increased vehicle costs, including increased maintenance, insurance 

premiums and taxes. The payback periods for vehicles meeting the standards considered for the 

final year of implementation (MY2024 for alternative 4 and MY2027 for the proposed standards) 

are shown in Table I-12, and are similar for both Method A and Method B.

Table I-12 Payback Periods for MY2027 Vehicles under the Proposed Standards and for MY2024 Vehicles 

Under Alternative 4 Relative to Baseline 1a (Payback Occurs in the Year Shown; using 7% Discounting)

Proposed Standards Alternative 4

Tractors/Trailers 2

nd 2nd

Vocational Vehicles 6

th 6th

Pickups/Vans 3

rd 4th

(3) Cost Effectiveness

These proposed regulations implement Section 32902 (k) of EISA and Section 202 (a) (1) 

and (2) of the Clean Air Act. Through the 2007 EISA, Congress directed NHTSA to create a 

medium- and heavy-duty vehicle fuel efficiency program designed to achieve the maximum 

feasible improvement by considering appropriateness, cost-effectiveness, and technological 

feasibility to determine maximum feasible standards.65 The Clean Air Act requires that any air 

pollutant emission standards for heavy-duty vehicles and engines take into account the costs of 

any requisite technology and the lead time necessary to implement such technology. Both 

agencies considered overall costs, overall benefits and cost effectiveness in developing the Phase 

1 standards. Although there are different ways to evaluate cost effectiveness, the essence is to 

consider some measure of costs relative to some measure of impacts.

Considering that Congress enacted EPCA and EISA to, among other things, address the 

need to conserve energy, the agencies have evaluated the proposed standards in terms of costs 

per gallon of fuel conserved. As described in the draft RIA, the agencies also evaluated the 

 

65 This EISA requirement applies to regulation of medium- and heavy-duty vehicles. For many years, and as 

reaffirmed by Congress in 2007, “economic practicability” has been among the factors EPCA requires NHTSA to 

consider when setting light-duty fuel economy standards at the (required) maximum feasible levels. NHTSA 

interprets “economic practicability” as a factor involving considerations broader than those likely to be involved in 

“cost effectiveness”.
Page 71 of 850

proposed standards using the same approaches employed in HD Phase 1. Together, the agencies 

have considered the following three ratios of cost effectiveness:

1. Total costs per gallon of fuel conserved.

2. Technology costs per ton of GHG emissions reduced.

3. Technology costs minus fuel savings per ton of GHG emissions reduced.

By all three of these measures, the proposed standards would be highly cost effective.

As discussed below, the agencies estimate that over the lifetime of heavy-duty vehicles 

produced for sale in the U.S. during model years 2018-2029, the proposed standards would cost 

about $30 billion and conserve about 75 billion gallons of fuel, such that the first measure of cost 

effectiveness would be about 40 cents per gallon. Relative to fuel prices underlying the 

agencies’ analysis, the agencies have concluded that today’s proposed standards would be cost 

effective.

With respect to the second measure, which is useful for comparisons to other GHG rules, 

the proposed standards would have overall $/ton costs similar to the HD Phase 1 rule. As 

Chapter 7 of the draft RIA shows, technology costs by themselves would amount to less than $50 

per metric ton of GHG (CO2 eq) for the entire HD Phase 2 program. This compares well to both 

the HD Phase 1 rule, which was estimated to cost about $30 per metric ton of GHG (without fuel 

savings), and to the agencies’ estimates of the social cost of carbon. Thus, even without 

accounting for fuel savings, the proposed standards would be cost-effective.

The third measure deducts fuel savings from technology costs, which also is useful for 

comparisons to other GHG rules. On this basis, net costs per ton of GHG emissions reduced 

would be negative under the proposed standards. This means that the value of the fuel savings 

would be greater than the technology costs, and there would be a net cost saving for vehicle 

owners. In other words, the technologies would pay for themselves (indeed, more than pay for 

themselves) in fuel savings. 

In addition, while the net economic benefits (i.e., total benefits minus total costs) of the 

proposed standards is not a traditional measure of their cost-effectiveness, the agencies have 

concluded that the total costs of the proposed standards are justified in part by their significant 

economic benefits. As discussed in the previous subsection and in Section IX, this rule would 

provide benefits beyond the fuel conserved and GHG emissions avoided. The rule’s net benefits 

is a measure that quantifies each of its various benefits in economic terms, including the 

economic value of the fuel it saves and the climate-related damages it avoids, and compares their 

sum to the rule’s estimated costs. The agencies estimate that the proposed standards would result 

in net economic benefits exceeding $100 billion, making this a highly beneficial rule.

Our current analysis of Alternative 4 also shows that, if technologically feasible, it would 

have similar cost-effectiveness but with greater net benefits (see Chapter 11 of the draft RIA). 

For example, the agencies estimate costs under Alternative 4 could be about $40 billion and 

about 85 billion gallons of fuel could be conserved, such that the first measure of cost 

effectiveness would be about 47 cents per gallon. However, the agencies considered all of the 

relevant factors, not just relative cost-effectiveness, when selecting the proposed standards from 
Page 72 of 850

among the alternatives considered. Relative cost-effectiveness was not a limiting factor for the 

agencies in selecting the proposed standards. It is also worth noting that the proposed standards 

and the Alternative 4 standards appear very cost effective, regardless of which reference case is 

used for the baseline, such that all of the analyses reinforced the agencies’ findings.

E. EPA and NHTSA Statutory Authorities

This section briefly summarizes the respective statutory authority for EPA and NHTSA 

to promulgate the Phase 1 and proposed Phase 2 programs. For additional details of the 

agencies’ authority, see Section XV of this notice as well as the Phase 1 rule.66

(1) EPA Authority

Statutory authority for the vehicle controls in this proposal is found in CAA Section 

202(a)(1) and (2) (which requires EPA to establish standards for emissions of pollutants from 

new motor vehicles and engines which emissions cause or contribute to air pollution which may

reasonably be anticipated to endanger public health or welfare), Sections 202(d), 203-209, 216, 

and 301 of the CAA, 42 U.S.C. 7521 (a), 7521 (d), 7522, 7523, 7524, 7525, 7541, 7542, 7543, 

7550, and 7601.

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-GHG emissions; the 

impacts of standards on oil conservation and energy security; the impacts of standards on fuel 

savings by customers; the impacts of standards on the truck industry; other energy impacts; as 

well as other relevant factors such as impacts on safety.

This proposed action implements a specific provision from Title II, Section 202(a). 

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. See Coalition for 

Responsible Regulation v. EPA, 684 F. 3d at 116-125, 126-27 (upholding EPA’s endangerment 

and cause and contribute findings, and further affirming EPA’s conclusion that it is legally 

compelled to issue standards under Section 202 (a) to address emission of the pollutant which 

 

66 76 FR 57106 at 57129, September 15, 2011.
Page 73 of 850

endangers after making the endangerment and cause of contribute findings); see also id. at 127-

29 (upholding EPA’s light-duty GHG emission standards for MYs 2012-2016 in their entirety).

Other aspects of EPA’s legal authority, including it authority under Section 202 (a), its 

testing authority under Section 203 of the Act, and its enforcement authorities under Section 207 

of the Act are discussed fully in the Phase 1 rule, and need not be repeated here. See 76 FR 

57129-130.

The proposed rule includes GHG emission and fuel efficiency standards applicable to 

trailers – an essential part of the tractor-trailer motor vehicle. Class 7/8 heavy-duty vehicles are 

composed of three major components: – the engine, the cab-chassis (i.e. the tractor), and the 

trailer. The fact that the vehicle consists of two detachable parts does not mean that either of the 

parts is not a motor vehicle. The trailer’s sole purpose is to serve as the cargo-hauling part of the 

vehicle. Without the tractor, the trailer cannot transport property. The tractor is likewise 

incomplete without the trailer. The motor vehicle needs both parts, plus the engine, to 

accomplish its intended use. Connected together, a tractor and trailer constitute ‘‘a selfpropelled vehicle designed for transporting . . . property on a street or highway,’’ and thus meet 

the definition of ‘‘motor vehicle’’ under Section 216(2) of the CAA. Thus, as EPA has 

previously explained, we interpret our authority to regulate motor vehicles to include authority to 

regulate such trailers. See 79 FR 46259 (August 7, 2014). 67 

This analysis is consistent with definitions in the Federal regulations issued under the 

CAA at 40 CFR 86.1803.01, where a heavy-duty vehicle ‘‘that has the primary load carrying 

device or container attached’’ is referred to as a ‘‘[c]omplete heavy-duty vehicle,’’ while a 

heavy-duty vehicle or truck ‘‘which does not have the primary load carrying device or container 

attached’’ is referred to as an ‘‘[i]ncomplete heavy- duty vehicle’’ or ‘‘[i]ncomplete truck.’’ The 

trailers that would be covered by this proposal are properly considered ‘‘the primary load 

carrying device or container’’ for the heavy-duty vehicles to which they become attached for use. 

Therefore, under these definitions, such trailers are implicitly part of a ‘‘complete heavy-duty 

vehicle,’’ and thus part of a ‘‘motor vehicle.’’68,69,70

The argument that trailers do not themselves emit pollutants and so are not subject to 

emission standards is also unfounded. First, the argument lacks a factual predicate. Trailers 

 

67 Indeed, an argument that a trailer is not a motor vehicle because, considered (artificially) as a separate piece of 

equipment it is not self-propelled, applies equally to the cab-chassis – the tractor. No entity has suggested that 

tractors are not motor vehicles; nor is such an argument plausible.

68 We note further, however, that certain hauled items, for example a boat, would not be considered to be a trailer 

under the proposal. See proposed section 1037.801, proposing to define “trailer’ as being “designed for cargo and 

for being drawn by a tractor.”

69 This concept is likewise reflected in the definition of “tractor” in the parallel Department of Transportation 

regulations: “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.” See 49 CFR part 571.3.

70 EPA’s proposed definition of “vehicle” in 40 CFR 1037.801 makes clear that an incomplete trailer becomes a 

vehicle (and thus subject to the prohibition against introduction into commerce with a certificate) when it has a 

frame with axles attached. Complete trailers are also vehicles.
Page 74 of 850

indisputably contribute to the motor vehicle’s CO2 emissions by increasing engine load, and 

these emissions can be reduced through various means such as trailer aerodynamic and tire 

rolling resistance improvements. See Section IV below. The argument also lacks a legal 

predicate. Section 202 (a) (1) authorizes standards applicable to emissions of air pollutants 

“from” either the motor vehicle or the engine. There is no requirement that pollutants be emitted 

from a specified part of the motor vehicle or engine. And indeed, the argument proves too much, 

since tractors and vocational vehicle chassis likewise contribute to emissions (including 

contributing by the same mechanisms that trailers do) but do not themselves directly emit 

pollutants. The fact that Section 202 (a)(1) applies explicitly to both motor vehicles and engines 

likewise indicates that EPA has unquestionable authority to interpret pollutant emission caused 

by the vehicle component to be “from” the motor vehicle and so within its regulatory authority 

under Section 202 (a)(1).71

(2) NHTSA Authority

The Energy Policy and Conservation Act (EPCA) of 1975 mandates 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 Security Act (EISA), amending 

EPCA to require, among other things, the creation of a medium- and heavy-duty fuel efficiency

program for the first time. 

Statutory authority for the fuel consumption standards in this proposed rule is found in 

EISA Section 103, 49 U.S.C. 32902(k). This section 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. 

NHTSA has 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 proposed rule would continue to fulfill the requirements of Section 103 of EISA, 

which instructs NHTSA to create a fuel efficiency improvement program for “commercial 

medium- and heavy-duty on-highway vehicles and work trucks” 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 

 

71 This argument applies equally to emissions of criteria pollutants, whose rate of emission is likewise affected by 

vehicle characteristics. It is for this reason that EPA’s implementing rules for criteria pollutants from heavy duty 

vehicles and engines specify a test weight for certification testing, since that weight influences the amount of

pollution emission.
Page 75 of 850

efficiency. NHTSA has broad discretion to balance the statutory factors in Section 103 in 

developing fuel consumption standards to achieve the maximum feasible improvement.

As discussed in the Phase 1 final rule notice, NHTSA has determined that the five year 

statutory limit on average fuel economy standards that applies to passengers and light trucks is 

not applicable to the HD vehicle and engine standards. As a result, the Phase 1 HD engine and 

vehicle standards remain in effect indefinitely at their 2018 or 2019 MY levels until amended by

a future rulemaking action. As was contemplated in that notice, NHTSA is currently engaging in 

this Phase 2 rulemaking action. Therefore, the Phase 1 standards would not remain in effect at 

their 2018 or 2019 MY levels indefinitely; they would remain in effect until the MY Phase 2

standards apply. In accordance with Section 103 of EISA, NHTSA will ensure that not less than 

four full MYs of regulatory lead-time and three full MYs of regulatory stability are provided for 

in the Phase 2 standards.

(a) Authority to Regulate Trailers

As contemplated in the Phase 1 NPRM and FR, the agencies are proposing standards for 

trailers in this rulemaking. Because Phase 1 did not include standards for trailers, NHTSA did 

not discuss its authority for regulating them in the NPRM or FR; that authority is described here

EISA 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....” EISA 

defines a commercial medium- and heavy-duty on-highway vehicle to mean “an on-highway

vehicle with a GVWR of 10,000 pounds or more.” A “work truck” is defined as a vehicle 

between 8,500 and 10,000 pounds GVWR that is not an MDPV. These definitions do not 

explicitly exclude trailers, in contrast to MDPVs. Because Congress did not act to exclude 

trailers when defining GVWRs, despite demonstrating the ability to exclude MDPVs, it is 

reasonable to interpret the provision to include them. 

Both commercial medium- and heavy-duty on-highway vehicles and work trucks, though,

must be vehicles in order to be regulated under this program. Although EISA does not define the 

term “vehicle,” NHTSA’s authority to regulate motor vehicles under its organic statute, the 

Motor Vehicle Safety Act (“Safety Act”), does. The Safety Act defines a motor vehicle as “a 

vehicle driven or drawn by mechanical power and manufactured primarily for use on public 

streets, roads, and highways....” NHTSA clearly has authority to regulate trailers under this Act 

as vehicles that are drawn and has exercised that authority numerous times. Given the absence 

of any apparent contrary intent on the part of Congress in EISA, NHTSA believes it is 

reasonable to interpret the term “vehicle” as used in the EISA definitions to have a similar 

meaning that includes trailers. 

Furthermore, the general definition of a vehicle is something used to transport goods or 

persons from one location to another. A tractor-trailer is designed for the purpose of transporting 

goods. Therefore it is reasonable to consider all of its parts – the engine, the cab-chassis, and the 

trailer – as parts of a whole. As such they are all parts of a vehicle, and are captured within the 

definition of vehicle. As EPA describes above, the tractor and trailer are both incomplete 

without the other. Neither can fulfill the function of the vehicle without the other. For this 
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reason, and the other reasons stated above, NHTSA interprets its authority to regulate 

commercial medium- and heavy-duty on-highway vehicles, including tractor-trailers, as 

encompassing both tractors and trailers.

(b) Authority to Regulate Recreational Vehicles

NHTSA did not regulate recreational vehicles as part of the Phase 1 medium- and heavyduty fuel consumption standards, although EPA did regulate them as vocational vehicles for 

GHG emissions.72 In the Phase 1 NPRM, NHTSA interpreted “commercial medium- and heavy 

duty” to mean that recreational vehicles, such as motor homes, were not to be included within the 

program because recreational vehicles are not commercial. Oshkosh Corporation submitted a 

comment on the agency’s interpretation stating that it did not match the statutory definition of 

“commercial medium- and heavy-duty on-highway vehicle,” which defines the phrase by

GVWR and on-highway use. In the Phase 1 final rule NHTSA agreed with Oshkosh Corporation 

that the agency had effectively read words into the statutory definition. However, because 

recreational vehicles were not proposed in the Phase 1 NPRM, they were not within the scope of 

the rulemaking and were excluded from NHTSA’s standards.73 NHTSA expressed that it would 

address recreational vehicles in its next rulemaking. 

NHTSA is proposing that recreational vehicles be included in the Phase 2 fuel 

consumption standards. As discussed above, EISA prescribes that NHTSA shall set average fuel 

economy standards for work trucks and commercial medium-duty or heavy-duty on-highway

vehicles. “Work truck” means a vehicle that is rated between 8,500 and 10,000 pounds GVWR 

and is not an MDPV. “Commercial medium- and heavy-duty on-road highway vehicle” means 

an on-highway vehicle with a gross vehicle weight rating of 10,000 pounds or more.74 Based on 

the definitions in EISA, recreational vehicles would be regulated as class 2b-8 vocational 

vehicles. Excluding recreational vehicles from the NHTSA standards in Phase 2 could create 

illogical results, including treating similar vehicles differently. Moreover, including recreational 

vehicles under NHTSA regulations furthers the agencies’ goal of one national program, as EPA 

regulations already cover recreational vehicles. 

NHTSA is proposing that recreational vehicles be included in the Phase 2 fuel 

consumption standards and that early compliance be allowed for manufacturers who want to 

certify during the Phase 1 period.75 

 

72 EPA did not give special consideration to recreational vehicles because the CAA applies to heavy-duty motor 

vehicle generally.

73 Motor homes are still subject to EPA’s Phase 1 CO2 standards for vocational vehicles. 

74 49 U.S.C. 32901(a)(7). 

75 NHTSA did not allow early compliance for one RV manufacturer in MY 2014 that is currently complying EPA’s 

GHG standards.
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F. Other Issues

In addition to the standards being proposed, this notice discusses several other issues 

related to those standards. It also proposes some regulatory provisions related to the Phase 1

program, as well as amendments related to other EPA and NHTSA regulations. These other 

issues are summarized briefly here and discussed in greater detail in later sections.

(1) Issues Related to Phase 2

(a) Natural Gas Engines and Vehicles

This combined rulemaking by EPA and NHTSA is designed to regulate two separate 

characteristics of heavy duty vehicles: GHGs and fuel consumption. In the case of diesel or 

gasoline powered vehicles, there is a one-to-one relationship between these two characteristics. 

For alternatively fueled vehicles, which use no petroleum, the situation is different. For 

example, a natural gas vehicle that achieves approximately the same fuel efficiency as a diesel 

powered vehicle would emit 20 percent less CO2; and a natural gas vehicle with the same fuel 

efficiency as a gasoline vehicle would emit 30 percent less CO2. Yet natural gas vehicles 

consume no petroleum. In Phase 1, the agencies balanced these facts by applying the gasoline 

and diesel CO2 standards to natural gas engines based on the engine type of the natural gas 

engine. Fuel consumption for these vehicles is then calculated according to their tailpipe CO2

emissions. In essence, this applies a one-to-one relationship between fuel efficiency and tailpipe 

CO2 emissions for all vehicles, including natural gas vehicles. The agencies determined that this 

approach would likely create a small balanced incentive for natural gas use. In other words, it 

created a small incentive for the use of natural gas engines that appropriately balanced concerns 

about the climate impact methane emissions against other factors such as the energy security 

benefits of using domestic natural gas. See 76 FR 57123. We propose to maintain this approach 

for Phase 2. Note that EPA is also considering natural gas in a broader context of life cycle 

emissions, as described in Section XI. 

(b) Alternative Refrigerants

In addition to use of leak-tight components in air conditioning system design, 

manufacturers could also decrease the global warming impact of refrigerant leakage emissions 

by adopting systems that use alternative, lower global warming potential (GWP) refrigerants, to 

replace the refrigerant most commonly used today, HFC-134a (R-134a). HFC-134a is a potent 

greenhouse gas with a GWP 1,430 times greater than that of CO2. 

Under EPA’s Significant New Alternatives Policy (SNAP) Program,76 EPA has found 

acceptable, subject to use conditions, three alternative refrigerants that have significantly lower 

 

76 Section 612(c) of the Clean Air Act requires EPA to review substitutes for class I and class II ozone-depleting 

substances and to determine whether such substitutes pose lower risk than other available alternatives. EPA is also 

required to publish lists of substitutes that it determines are acceptable and those it determines are unacceptable. 

See http://www.epa.gov/ozone/snap/refrigerants/lists/index.html, last accessed on March 5, 2015.
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GWPs than HFC-134a for use in A/C systems in newly manufactured light-duty vehicles: HFC152a, CO2 (R-744), and HFO-1234yf.77 HFC-152a has a GWP of 124, HFO-1234yf has a GWP 

of 4, and CO2 (by definition) has a GWP of 1, as compared to HFC-134a which has a GWP of 

1,430.78 CO2 is nonflammable, while HFO-1234yf and HFC-152a are flammable. All three are 

subject to use conditions requiring labeling and the use of unique fittings, and where appropriate, 

mitigating flammability and toxicity. Currently, the SNAP listing for HFO-1234yf is limited to 

newly manufactured A/C systems in LD vehicles, whereas HFC-152a and CO2 have been found 

acceptable for all motor vehicle air conditioning applications, including heavy-duty vehicles. 

None of these alternative refrigerants can simply be “dropped” into existing HFC-134a 

air conditioning systems. In order to account for the unique properties of each refrigerant and 

address use conditions required under SNAP, changes to the systems will be necessary.

Typically these changes will need to occur during a vehicle redesign cycle but could also occur 

during a refresh. For example, because CO2, when used as a refrigerant, is physically and

thermodynamically very different from HFC-134a and operates at much higher pressures, a 

transition to this refrigerant would require significant hardware changes. A transition to A/C 

systems designed for HFO-1234yf, which is more thermodynamically similar to HFC-134a than 

is CO2, requires less significant hardware changes that typically include installation of a thermal 

expansion valve and could potentially require resized condensers and evaporators, as well as 

changes in other components. In addition, vehicle assembly plants require re-tooling in order to 

handle new refrigerants safely. Thus a change in A/C refrigerants requires significant 

engineering, planning, and manufacturing investments.

EPA is not aware of any significant development of A/C systems designed to use 

alternative refrigerants in heavy-duty vehicles;

79 however, all three lower GWP alternatives are 

in use or under various stages of development for use in LD vehicles. Of these three refrigerants, 

most manufacturers of LD vehicles have identified HFO-1234yf as the most likely refrigerant to 

be used in that application. For that reason, EPA would anticipate that HFO-1234yf could be a 

primary candidate for refrigerant substitution in the HD market in the future if it is listed as an 

acceptable substitute under SNAP for HD A/C applications. EPA has begun, but has not yet 

completed, our evaluation of the use of HFO-1234yf in HD vehicles. After EPA has conducted a 

full evaluation based on the SNAP program’s comparative risk framework, EPA will list this

alternative as either a) acceptable subject to use conditions or b) unacceptable if the risk of use in 

HD A/C systems is determined to be greater than that of the other currently or potentially

available alternatives. EPA is also considering and evaluating additional refrigerant substitutes 

for use in motor vehicle A/C systems under the SNAP program. EPA welcomes comments 

related to industry development of HD A/C systems using lower-GWP refrigerants.

 

77 Listed at 40 CFR part 82, subpart G. 

78 GWP values cited in this proposal are from the IPCC Fourth Assessment Report (AR4) unless stated otherwise. 

Where no GWP is listed in AR4, GWP values shall be determined consistent with the calculations and analysis 

presented in AR4 and referenced materials.

79 To the extent that some manufacturers produce HD pickups and vans on the same production lines or in the same 

facilities as LD vehicles, some A/C system technology commonality between the two vehicle classes may be 

developing. 
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LD vehicle manufacturers are currently making investments in systems designed for 

lower-GWP refrigerants, both domestically and on a global basis. In support of the LD GHG 

rule, EPA projected a full transition of LD vehicles to lower-GWP alternatives in the United 

States by MY 2021. We expect the investment required to transition to ease over time as 

alternative refrigerants are adopted across all LD vehicles and trucks. This may occur in part due 

to increased availability of components and the continuing increases in refrigerant production 

capacity, as well as knowledge gained through experience. As lower-GWP alternatives become 

widely used in LD vehicles, some manufacturers may wish to also transition their HD vehicles. 

Transitioning could be advantageous for a variety of reasons including platform standardization 

and company environmental stewardship policies. 

Although manufacturers of HD vehicles may begin to transition to alternative refrigerants 

in the future, there is great uncertainty about when significant adoption of alternative refrigerants 

for HD vehicles might begin, on what timeline adoption might become widespread, and which 

refrigerants might be involved. Another factor is that the most likely candidate, HFO-1234yf, 

remains under evaluation and has not yet been listed under SNAP. For these reasons, EPA has 

not attempted to project any specific hypothetical scenarios of transition for analytical purposes

in this proposed rule. 

Because future introduction of and transition to lower-GWP alternative refrigerants for 

HD vehicles may occur, EPA is proposing regulatory provisions that would be in place if and 

when such alternatives become available and manufacturers of HD vehicles choose to use them. 

These proposed provisions would also have the effect of easing the burden associated with 

complying with the lower-leakage requirements when a lower-GWP refrigerant is used instead of 

HFC-134a. These provisions would recognize that leakage of refrigerants would be relatively

less damaging from a climate perspective if one of the lower-GWP alternatives is used. 

Specifically, EPA is proposing to allow a manufacturer to be “deemed to comply” with the 

leakage standard by using a lower-GWP alternative refrigerant. In order to be “deemed to 

comply” the vehicle manufacturer would need to use a refrigerant other than HFC-134a that is 

listed as an acceptable substitute refrigerant for heavy-duty A/C systems under SNAP, and 

defined under the LD GHG regulations at 40 CFR 86.1867-12(e). The refrigerants currently

defined at 40 CFR 86.1867-12(e), besides HFC-134a, are HFC-152a, HFO-1234yf, and CO2. If 

a manufacturer chooses to use a lower-GWP refrigerant that is listed in the future as acceptable 

in 40 CFR part 82, subpart G, but that is not identified in 40 CFR 86.1867-12(e), then the 

manufacturer could contact EPA about how to appropriately determine compliance with the 

leakage standard.

EPA encourages comment on all aspects of our proposed approach to HD vehicle 

refrigerant leakage and the potential future use of alternative refrigerants for HD applications. 

We specifically request comment on whether there should be additional provisions that could 

prevent or discourage manufacturers that transition to an alternative refrigerant from 

discontinuing existing, low-leak A/C system components and instead reverting to higher-leakage 

components. 
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Recently, EPA proposed to change the SNAP listing for the refrigerant HFC-134a from 

acceptable (subject to use conditions) to unacceptable for use in A/C systems in new LD 

vehicles.80 EPA expects to take final action on this proposed change in listing status for HFC134a for use in new, light-duty vehicles in 2015. If the final action changes the status of HFC134a to unacceptable, it would establish a future compliance date by which HFC-134a could no 

longer be used in A/C systems in newly manufactured LD vehicles; instead, all A/C systems in 

new LD vehicles would be required to use HFC-152a, HFO-1234yf, CO2, or any other 

alternative listed as acceptable for this use in the future. The current proposed rule does not 

address the use of HFC-134a in heavy-duty vehicles; however, EPA could consider a change of 

listing status for HFC-134a use in HD vehicles in the future if EPA determines that other 

alternatives are currently or potentially available that pose lower overall risk to human health and 

the environment.

(c) Small Business Issues

The Regulatory Flexibility Act (RFA) 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. See generally 5 USC Sections 601-612. The RFA analysis is discussed in Section 

XIV.

Pursuant to Section 609(b) of the RFA, as amended by the Small Business Regulatory

Enforcement Fairness Act (SBREFA), EPA also conducted outreach to small entities and 

convened a Small Business Advocacy Review Panel to obtain advice and recommendations of 

representatives of the small entities that potentially would be subject to the rule’s requirements.

Consistent with the RFA/SBREFA requirements, the Panel evaluated the assembled materials 

and small-entity comments on issues related to elements of the IRFA. A copy of the Panel 

Report is included in the docket for this proposed rule.

The agencies determined that the proposed Phase 2 regulations could have a significant 

economic impact on small entities. Specifically, the agencies identified four categories of 

directly regulated small businesses that could be impacted:

 Trailer Manufacturers

 Alternative Fuel Converters

 Vocational Chassis Manufacturers

 Glider Vehicle81 Assemblers

To minimize these impacts the agencies are proposing certain regulatory flexibilities – both 

general and category-specific. In general, we are proposing to delay new requirements for EPA 

 

80 See 79 FR 46126, August 6, 2014.

81 Vehicles produced by installing a used engine into a new chassis are commonly referred to as “gliders,” “glider 

kits,” or “glider vehicles,”
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GHG emission standards by one year and simplify certification requirements for small 

businesses. For some of the proposed standards, small businesses would be required to comply 

with EPA’s standards before NHTSA’s fuel efficiency standards would begin. NHTSA does not 

believe that providing small businesses with an additional year of delay to comply with those 

fuel efficiency standards would provide beneficial flexibility. For other standards, NHTSA is 

proposing to require compliance with its fuel efficiency standards for small businesses in the 

same timeframe that compliance is required for the EPA standards. This would maintain 

alignment between EPA’s and NHTSA’s programs for those years in which compliance with 

both programs is required. The agencies request comment on this decision. We are also 

proposing the following specific relief:

 Trailers: Proposing simpler requirements for non-box trailers, which are more 

likely to be manufactured by small businesses; and making third-party testing 

easier for certification.

 Alternative Fuel Converters: Omitting recertification of a converted vehicle when 

the engine is converted and certified; reduced N2O testing; and simplified onboard 

diagnostics.

 Vocational Chassis: Less stringent standards for certain vehicle categories.

 Glider Vehicle Assemblers: 82 Exempt existing small businesses, but limit the 

small business exemption to a capped level of annual production (production in 

excess of the capped amount would be allowed, but subject to all otherwise 

applicable requirements including the Phase 2 standards).

These flexibilities are described in more detail in Section XIV and in the Panel Report. The 

agencies look forward to comments and to feedback from the small business community before 

finalizing the rule and associated flexibilities to protect small businesses.

(d) Confidentiality of Test Results and GEM Inputs

In accordance with Federal statutes, EPA does not release information from certification 

applications (or other compliance reports) that we determine to be confidential business 

information (CBI) under 40 CFR part 2. Consistent with the CAA, EPA does not consider 

emission test results to be CBI after introduction into commerce of the certified engine or 

vehicle. (However, we have generally treated test results as protected before the introduction 

into commerce date). For Phase 2, we expect to continue this policy and thus would not treat any

test results or other GEM inputs as CBI after the introduction into commerce date as identified 

by the manufacturer. We request comment on this approach.

We consider this issue to be especially relevant for tire rolling resistance measurements. 

Our understanding is that tire manufacturers typically consider such results as proprietary. 

 

82 EPA is proposing to amend its rules applicable to engines installed in glider kits, a proposal which would affect 

emission standards not only for GHGs but for criteria pollutants as well. EPA is also proposing to clarify its 

requirements for certification and revise its definitions for glider manufacturers. NHTSA is also considering 

including gliders under its Phase 2 standards. 
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However, under EPA’s policy, tire rolling resistance measurements are not considered to be CBI 

and can be released to the public after the introduction into commerce date identified by the 

manufacturer. We request comment on whether EPA should release such data on a regular basis 

to make it easier for operators to find proper replacement tires for their vehicles.

With regard to NHTSA’s treatment of confidential business information, manufacturers 

must submit a request for confidentiality with each electronic submission specifying any part of 

the information or data in a report that it believes should be withheld from public disclosure as 

trade secret or other confidential business information. A form will be available through the 

NHTSA website to request confidentiality. NHTSA does not consider manufacturers to continue 

to have a business case for protecting pre-model report data after the vehicles contained within 

that report have been introduced into commerce.

(e) Delegated Assembly

In EPA’s existing regulations (40 CFR 1068.261), we allow engine manufacturers to sell 

or ship engines that are missing certain emission-related components if those components will be 

installed by the vehicle manufacturer. EPA has found this provision to work well for engine 

manufacturers and is proposing a new provision in 40 CFR 1037.621 that would provide a 

similar allowance for vehicle manufacturers to sell or ship vehicles that are missing certain 

emission-related components if those components will be installed by a secondary vehicle 

manufacturer. As conditions of this allowance manufacturers would be required to:

 Have a contractual obligation with the secondary manufacturer to complete the 

assembly properly and provide instructions about how to do so.

 Keep records to demonstrate compliance.

 Apply a temporary label to the incomplete vehicles

 Take other reasonable steps to ensure the assembly is completed properly.

 Describe in its application for certification how it will use this allowance. 

We request comment on this allowance.

(2) Proposed Amendments to Phase 1 Program

The agencies are proposing revisions to test procedures and compliance provisions used 

for Phase 1. These changes are described in Section XII. As a drafting matter, EPA notes that 

we are proposing to mijgrate the GHG standards for Class 2b and 3 pickups and vans from 40 

CFR 1037.104 to 40 CFR 86.1819. NHTSA is also proposing to amend 49 CFR Part 535 to 

make technical corrections to its Phase 1 program to better align with EPA’s compliance 

approach, standards and CO2 performance results. In general, these changes are intended to 

improve the regulatory experience for regulated parties and also reduce agency administrative 

burden.

NHTSA is proposing to amend 49 CFR Part 535 to make technical corrections to its 

Phase 1 program to better align with EPA’s compliance approach, standards and CO2

performance results. More specifically, NHTSA proposes to change the rounding of its 

standards and performance values to have more significant digits. Increasing the number of 
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significant digits for values used for compliance with NHTSA standards reduces differences in

credits generated and overall credit balances for the NHTSA and EPA programs. NHTSA is also 

proposing to remove the petitioning process for off-road vehicles, clarify requirements for the 

documentation needed for submitting innovative technology requests in accordance with 40 CFR 

1037.610 and 49 CFR Part 535.7, and add further detail to requirements for submitting credit 

allocation plans as specified in 49 CFR Part 535.9. Finally, NHTSA is adding the same record 

requirements that EPA currently requires to facilitate in-use compliance inspections. These 

changes are intended to improve the regulatory experience for regulated parties and also reduce 

agency administrative burden.

(3) Other Proposed Amendments to EPA Regulations

EPA is proposing several amendments to regulations not directly related to the HD Phase 

1 or Phase 2 programs, as detailed in Section XIII. For these amendments, there would not be 

corresponding changes in NHTSA regulations (since there are no such regulations relevant to 

those programs). Some of these relate directly to heavy-duty highway engines, but not to the 

GHG programs. Others relate to nonroad engines. This latter category reflects the regulatory

structure EPA uses for its mobile source regulations, in which regulatory provisions applying 

broadly to different types of mobile sources are codified in common regulatory parts such as 40 

CFR part 1068. This approach creates a broad regulatory structure that regulates highway and 

nonroad engines, vehicles, and equipment collectively in a common program. Thus, it is 

appropriate to include some proposed amendments to nonroad regulations in addition to the 

changes proposed only for highway engines and vehicles.

(a) Standards for Engines Used In Glider Kits

EPA regulations currently allow used pre-2013 engines to be installed into new glider 

kits without meeting currently applicable standards. As described in Section XIV, EPA is 

proposing to amend our regulations to allow only engines that have been certified to meet current 

standards to be installed in new glider kits, with two exceptions. First, engines certified to earlier 

MY standards that were identical to the current model year standards may be used. Second, the 

small manufacturer allowance described in Section I. F. (1) (c) for glider vehicles would also 

apply for the engines used in the exempted glider kits.

(b) Re-proposal of Nonconformance Penalty Process Changes

Nonconformance penalties (NCPs) are monetary penalties established by regulation that 

allow a vehicle or engine manufacturer to sell engines that do not meet the emission standards. 

Manufacturers unable to comply with the applicable standard pay penalties, which are assessed 

on a per-engine basis. 

On September 5, 2012, EPA adopted final NCPs for heavy heavy-duty diesel engines that 

could be used by manufacturers of heavy-duty diesel engines unable to meet the current oxides 

of nitrogen (NOX) emission standard. On December 11, 2013 the U.S. Court of Appeals for the 

District of Columbia Circuit issued an opinion vacating that Final Rule. It issued its mandate for 

this decision on April 16, 2014, ending the availability of the NCPs for the current NOX

standard, as well as vacating certain amendments to the NCP regulations due to concerns about 
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inadequate notice. In particular, the amendments revise the text explaining how EPA determines 

when NCP should be made available. In this action, EPA is re-proposing most of these 

amendments to provide fuller notice and additional opportunity for public comment. They are 

discussed in Section XIV.

(c) Updates to Heavy-Duty Engine Manufacturer In-use Testing Requirements 

EPA and manufacturers have gained substantial experience with in-use testing over the 

last four or five years. This has led to important insights in ways that the test protocol can be 

adjusted to be more effective. We are accordingly proposing to make changes to the regulations 

in 40 CFR part 86, subparts N and T.

(d) Extension of Certain 40 CFR part 1068 Provisions to Highway Vehicles and Engines

As part of the Phase 1 GHG standards, we applied the exemption and importation 

provisions from 40 CFR part 1068, subparts C and D, to heavy-duty highway engines and 

vehicles. We also specified that the defect reporting provisions of 40 CFR 1068.501 were 

optional. In an earlier rulemaking, we applied the selective enforcement auditing under 40 CFR 

part 1068, subpart E (75 FR 22896, April 30, 2010). We are proposing in this rule to adopt the 

rest of 40 CFR part 1068 for heavy-duty highway engines and vehicles, with certain exceptions 

and special provisions. 

As described above, we are proposing to apply all the general compliance provisions of 

40 CFR part 1068 to heavy-duty engines and vehicles. We propose to also apply the recall 

provisions and the hearing procedures from 40 CFR part 1068 for highway motorcycles and for 

all vehicles subject to standards under 40 CFR part 86, subpart S. We also request comment on 

applying the rest of the provisions from 40 CFR part 1068 to highway motorcycles and to all 

vehicles subject to standards under 40 CFR part 86, subpart S.

EPA is proposing to update and consolidate the regulations related to formal and informal 

hearings in 40 CFR part 1068, subpart G. This would allow us to rely on a single set of 

regulations for all the different categories of vehicles, engines, and equipment that are subject to 

emission standards. We also made an effort to write these regulations for improved readability. 

We are also proposing to make a number of changes to part 1068 to correct errors, to add 

clarification, and to make adjustments based on lessons learned from implementing these 

regulatory provisions. 

(e) Amendments to Engine and Vehicle Test Procedures in 40 CFR parts 1065 and 1066 

EPA is proposing several changes to our engine testing procedures specified in 40 CFR 

part 1065. None of these changes would significantly impact the stringency of any standards.

(f) Amendments Related to Marine Diesel Engines in 40 CFR part 1042

EPA’s emission standards and certification requirements for marine diesel engines under 

the Clean Air Act are identified in 40 CFR part 1042. EPA is proposing to amend these 
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regulations with respect to continuous NOX monitoring and auxiliary engines, as well as making 

several other minor revisions.

(g) Amendments Related to Locomotives in 40 CFR part 1033

EPA’s emission standards and certification requirements for locomotives under the Clean 

Air Act are identified in 40 CFR part 1033. EPA is proposing to make several minor revisions to 

these regulations.

(4) Other Proposed Amendments to NHTSA Regulations

NHTSA is proposing to amend Parts 537 and 512 of title 49 of the CFR in order to allow 

manufacturers to submit required compliance data for the Corporate Average Fuel Economy

program electronically, rather than submitting some reports to NHTSA via paper and CDs and 

some reports to EPA through its VERIFY database system. The agencies are coordinating on an 

information technology project which will allow manufacturers to submit pre-model, mid-model 

and final model year reports through a single electronic entry point. The agencies anticipate that 

this would reduce the reporting burden on manufacturers by up to fifty percent. The 

amendments to Part 537 would allow reporting to an electronic database (i.e. EPA’s VERIFY 

system), and the amendments to Part 512 would ensure that manufacturer’s confidential business 

information would be protected through that process. This proposal is discussed further in 

Section XIII.
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II. Vehicle Simulation, Engine Standards and Test Procedures

A. Introduction and Summary of Phase 1 and Phase 2 Regulatory Structures

This Section II. A. gives an overview of our vehicle simulation approach in Phase 1 and 

our proposed approach for Phase 2; our separate engine standards for tractor and vocational 

chassis in Phase 1 and our proposed separate engine standards in Phase 2; and it describes our 

engine and vehicle test procedures that are common among the tractor and vocational chassis 

standards. Section II. B. discusses in more detail how the Phase 2 proposed regulatory structure 

would approach vehicle simulation, separate engine standards, and test procedures. Section II. 

C. discusses the proposed vehicle simulation computer program, GEM, in further detail and 

Section II. D. discusses the proposed separate engine standards and engine test procedure. See 

Sections III through VI for discussions of the proposed test procedures that are unique for 

tractors, trailers, vocational chassis, and HD pickup trucks and vans.

In Phase 1 the agencies adopted a regulatory structure that included a vehicle simulation 

procedure for certifying tractors and the chassis of vocational vehicles. In contrast, the agencies 

adopted a full vehicle chassis dynamometer test procedure for certifying complete heavy-duty 

pickups and vans. The Phase 1 vehicle simulation procedure for tractors and vocational chassis 

requires regulated entities to use GEM to simulate and certify tractors and vocational vehicle 

chassis. This program is provided free of charge for unlimited use and may be downloaded by 

anyone from EPA’s Website: http://www.epa.gov/otaq/climate/gem.htm. This computer 

program mathematically combines vehicle component test results with other pre-determined 

vehicle attributes to determine a vehicle’s levels of fuel consumption and CO2 emissions for 

certification purposes. For Phase 1, the required inputs to this computer program include, for 

tractors, vehicle aerodynamics information, tire rolling resistance, and whether or not a vehicle is 

equipped with certain lightweight high-strength steel or aluminum components, a tamper-proof 

speed limiter, or tamper-proof idle reduction technologies. The sole input for vocational 

vehicles, was tire rolling resistance. For Phase 1 the computer program’s inputs did not include 

engine test results or attributes related to a vehicle’s powertrain, namely, its transmission, drive 

axle(s), or tire revolutions per mile. Instead, for Phase 1 the agencies specified a generic engine 

and powertrain within the computer program, and for Phase 1 these cannot be changed by a 

program user.83 

The full vehicle chassis dynamometer test procedure for heavy-duty pickups and vans 

substantially mirrors EPA’s existing light-duty vehicle test procedure. EPA also set separate 

engine so-called cap standards for methane (CH4) and nitrous oxide (N2O) (essentially capping 

current emission levels). Compliance with the CH4 and N2O standards is measured by an engine 

dynamometer test procedure, which EPA based on our existing heavy-duty engine emissions test 

procedure with small adaptations. EPA also set hydro-fluorocarbon refrigerant leakage design 

standards for cabin air conditioning systems in tractors, pickups, and vans, which are evaluated 

by design rather than a test procedure. 

 

83 These attributes are recognized in Phase 1 innovative technology provisions at 40 CFR 1037.610.
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In this action the agencies are proposing a similar regulatory structure for Phase 2, along 

with a number of revisions that are intended to more accurately evaluate vehicle and engine 

technologies’ impact on real-world fuel efficiency and GHG emissions. Thus, we are proposing 

to continue the same certification test regime for heavy duty pickups and vans, and for the CH4

and N2O) standards, as well as tractor and pickup and van air conditioning leakage standards. 

EPA is also proposing to control vocational vehicle air conditioning leakage and to use that same 

certification procedure.

We are proposing to continue the vehicle simulation procedure for certifying tractors and 

vocational chassis, and we are proposing a new regulatory program to regulate some of the 

trailers hauled by tractors. The agencies are proposing the use of an equation based on the 

vehicle simulation procedure for trailer certification. In addition, we are proposing a simplified 

option for trailer certification that would not require testing to be undertaken by manufacturers to 

generate inputs for the equation. We are also proposing to continue separate fuel consumption 

and CO2 standards for the engines installed in tractors and vocational chassis, and we are 

proposing to continue to require a full vehicle chassis dynamometer test procedure for certifying 

complete heavy-duty pickups and vans. As described in Section II.B.(2)(b), the agencies see 

important advantages to maintaining separate engines standards, such as improved compliance 

assurance and better control during transient engine operation.

The vehicle simulation procedure necessitates some testing of engines and vehicle 

components to generate the inputs for the simulation tool; that is, to generate the inputs to the 

model which is used to certify tractors and vocational chassis. For trailers, some testing may be 

performed in order to generate values that are input into the simulation-based compliance 

equations. In addition to the testing needed for this purpose for the inputs used in the Phase 1 

standards, the agencies are proposing in Phase 2 that manufacturers conduct additional required 

and optional engine and vehicle component tests, and proposing the additional procedures for 

conducting these input tests. These include a new required engine test procedure that provides 

steady-state engine fuel consumption and CO2 inputs to represent the actual engine in a vehicle. 

In addition, we are seeking comment on a newly developed engine test procedure that captures 

transient engine performance for use in the vehicle simulation computer program. As described 

in detail in the draft RIA Chapter 4, we are proposing to require entering attributes that describe 

the vehicle’s transmission type, and its number of gears and gear ratios. We are proposing an 

optional powertrain test procedure that would provide inputs to override the agencies’ simulated 

engine and transmission in the vehicle simulation computer program. We are proposing to 

require entering attributes that describe the vehicle’s drive axle(s) type and axle ratio. We are 

also seeking comment on an optional axle efficiency test procedure that would override the 

agencies’ simulated axle in the vehicle simulation computer program. To improve the 

measurement of aerodynamic components performance, we are proposing a number of 

improvements to the aerodynamic coast-down test procedure and data analysis, and we are 

seeking comment on a newly developed constant speed aerodynamic test procedure. We are 

proposing that the aerodynamic test procedures for tractors be applicable to trailers when a 

regulated entity opts to use the GEM-based compliance equation. Additional details about all 

these test procedures are found in the draft RIA Chapter 3.

We are further proposing to significantly expand the number of technologies that are 

recognized in the vehicle simulation computer program. These include recognizing lightweight 
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thermoplastic materials, automatic tire inflation systems, advanced cruise control systems, 

workday idle reduction systems, and axle configurations that decrease the number of drive axles. 

We are seeking comment on recognizing additional technologies such as high efficiency glass 

and low global warming potential air conditioning refrigerants as post-process adjustments to the 

simulation results. 

To better reflect real-world operation, we are also proposing to revise the vehicle 

simulation computer program’s urban (55 mph) and rural (65 mph) highway duty cycles to 

include changes in road grade. We are seeking comment on whether or not these duty cycles 

should also simulate driver behavior in response to varying traffic patterns. We are proposing a 

new duty cycle to capture the performance of technologies that reduce the amount of time a 

vehicle’s engine is at idle during a workday when the vehicle is not moving. And to better 

recognize that vocational vehicle powertrains are configured for particular applications, we are 

proposing to further subdivide the vocational chassis category into three different vehicle speed 

categories. This is in addition to the Phase 1 subdivision by three weight categories. The result 

is nine proposed vocational vehicle subcategories for Phase 2. The agencies are also proposing 

to subdivide the highest weight class of tractors into two separate categories to recognize the 

unique configurations and technology applicability to “heavy-haul” tractors.

Even though we are proposing to include engine test results as inputs into the vehicle 

simulation computer model, we are also proposing to continue the Phase 1 separate engine 

standard regulatory structure by proposing separate engine fuel consumption and CO2 standards 

for engines installed in tractors and vocational chassis. For these separate engine standards, we 

are proposing to continue to use the Phase 1 engine dynamometer test procedure, which was

adapted substantially from EPA’s existing heavy-duty engine emissions test procedure. 

However, we are proposing to modify the weighting factors of the tractor engine’s 13-point 

steady-state duty cycle to better reflect real-world engine operation and to reflect the trend 

toward operating engines at lower engine speeds during tractor cruise speed operation. Further 

details on the proposed Phase 2 separate engine standards are provided below in Section II. D. 

In today’s action EPA is proposing to continue the separate engine cap standards for methane 

(CH4) and nitrous oxide (N2O) emissions. 

(1) Phase 1 Vehicle Simulation Computer Program (GEM)

For Phase 1 EPA developed a vehicle simulation computer program called, “Greenhouse 

gas Emissions Model” or “GEM.” GEM was created for Phase 1 for the exclusive purpose of

certifying tractors and vocational vehicle chassis. GEM is similar in concept to a number of 

other commercially available vehicle simulation computer programs. See 76 FR 57116, 57146, 

57156-157. However, GEM is also unique in a number of ways.

Similar to other vehicle simulation computer programs, GEM combines various vehicle

inputs with known physical laws and justified assumptions to predict vehicle performance for a 

given period of vehicle operation. For Phase 1 GEM’s vehicle inputs include vehicle 

aerodynamics information (for tractors), tire rolling resistance, and whether or not a vehicle is 

equipped with lightweight materials, a tamper-proof speed limiter, or tamper-proof idle reduction 

technologies. Other vehicle and engine characteristics were fixed as defaults that cannot be 

altered by the user. These defaults included tabulated data of engine fuel rate as a function of 
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engine speed and torque (i.e. “engine fuel maps”), transmissions, axle ratios, and vehicle 

payloads. For tractors, Phase 1 GEM models the vehicle pulling a standard trailer. For 

vocational vehicles, Phase 1 GEM includes a fixed aerodynamic drag coefficient and vehicle 

frontal area. 

GEM uses the same physical principles as many other existing vehicle simulation models 

to derive governing equations which describe driveline components, engine, and vehicle. These 

equations are then integrated in time to calculate transient speed and torque. Some of the 

justified assumptions in GEM include average energy losses due to friction between moving 

parts of a vehicle’s powertrain; the logical behavior of an average driver shifting from one 

transmission gear to the next; ad speed limit assumptions such as 55 miles per hour for urban 

highway driving and 65 miles per hour for rural interstate highway driving. The sequence of the 

GEM vehicle simulation can be visualized by imagining a human driver initially sitting in a 

parked running tractor or vocational vehicle. The driver then proceeds to drive the vehicle over a 

prescribed route that includes three distinct patterns of driving: stop-and-go city driving, urban 

highway driving, and rural interstate highway driving. The driver then exits the highway and 

brings the vehicle to a stop. This concludes the vehicle simulation. 

Over each of the three driving patterns or “duty cycles,” GEM simulates the driver’s 

behavior of pressing the accelerator, coasting, or applying the brakes. GEM also simulates how 

the engine operates as the gears in the vehicle’s transmission are shifted and how the vehicle’s 

weight, aerodynamics, and tires resist the forward motion of the vehicle. GEM combines the 

driver behavior over the duty cycles with the various vehicle inputs and other assumptions to 

determine how much fuel must be consumed to move the vehicle forward at each point during 

the simulation. For each of the three duty cycles, GEM totals the amount of fuel consumed and 

then divides that amount by the product of the miles travelled and tons of payload carried. The 

tons of payload carried are specified by the agencies for each vehicle type and weight class. For 

each regulatory subcategory of tractor and vocational vehicle (e.g., sleeper cab tractor, day cab 

tractor, small vocational vehicle, large vocational vehicle, etc.), GEM applies prescribed 

weighting factors to each of the three duty cycles to represent the fraction of city, urban highway, 

and rural highway driving that would be typical of each subcategory. After completing all the 

cycles, GEM outputs a single composite result for the vehicle, expressed as both fuel consumed 

in gallon per 1000 ton-miles (for NHTSA standards) and an equivalent amount of CO2 emitted 

in grams per ton-mile (for EPA standards). These are the vehicle’s GEM results that are used 

along with other information to demonstrate the vehicle complies with the applicable standards. 

This other information includes the annual sales volume of the vehicle (family) simulated in 

GEM, plus information on emissions credits that may be generated or used as part of that vehicle 

family’s certification.

While GEM is similar to other vehicle simulation computer programs, GEM is also 

unique in a number of ways. First, GEM was designed exclusively for regulated entities to 

certify tractor and vocational vehicle chassis to the agencies’ respective fuel consumption and 

CO2 emissions standards. For GEM to be effective for this purpose, the inputs to GEM include 

only information related to vehicle components and attributes that significantly impact vehicle 

fuel efficiency and CO2 emissions. For example, these include vehicle aerodynamics, tire rolling 

resistance, and whether or not a vehicle is equipped with lightweight materials, a tamper-proof 

speed limiter, or tamper-proof idle reduction technologies. On the other hand, other attributes 
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such as those related to a vehicle’s suspension, frame strength, or interior features are not 

included, where these might be included in other commercially available vehicle simulation 

programs for other purposes. Furthermore, the simulated driver behavior and the duty cycles 

cannot be changed in the GEM executable program. This helps to ensure that all vehicles are 

simulated and certified in the same way, but this does preclude GEM from being of much use as 

a research tool for exploring the effects of driver behavior and of different duty cycles. 

To allow for public comment, GEM is available free of charge for unlimited use, and the 

GEM source code is open source. That is, the programming source code of GEM is freely 

available upon request for anyone to examine, manipulate, and generally use without restriction. 

In contrast commercially available vehicle simulation programs are generally not free and open 

source. Additional details of GEM are included in Chapter 4 of the RIA.

As part of Phase 1, the agencies conducted a peer review of GEM version 1.0, which was 

the version released for the Phase 1 proposal.

84,85

 In response to this peer review and comments

from stakeholders, EPA has made changes to GEM. The current version of GEM is v2.0.1, 

which is the version applicable for the Phase 1 standards.86

(2) Phase 1 Engine Standards and Engine Test Procedure

For Phase 1 the agencies set separate engine fuel consumption and CO2 standards for 

engines installed in tractors and vocational vehicle chassis. EPA also set separate engine cap 

standards for methane (CH4) and nitrous oxide (N2O) emissions. These Phase 1 engine standards 

are specified in terms of brake-specific (g/hp-hr) fuel, CO2, CH4 and N2O emissions limits. For 

these separate engine standards, the agencies adopted an engine dynamometer test procedure, 

which was built substantially from EPA’s existing heavy-duty engine emissions test procedure. 

Since the test procedure already specified how to measure fuel consumption, CO2 and CH4, few 

changes were needed to employ the test procedure for purposes of the Phase 1 standards. For 

Phase 1 the test procedure was modified to specify how to measure N2O.

The duty cycles from EPA’s existing heavy-duty emissions test procedure were used in a 

somewhat unique way for Phase 1. In EPA’s non-GHG engine emissions standards, heavy-duty 

engines must meet brake-specific standards for emissions of total oxides of nitrogen (NOX), 

particulate mass (PM), non-methane hydrocarbon (NMHC), and carbon monoxide (CO). These 

standards must be met by all engines both over a 13-mode steady-state duty cycle called the 

“Supplemental Emissions Test” (SET) and over a composite of a cold-start and a hot-start 

transient duty cycle called the “Federal Test Procedure” (FTP). In contrast, for Phase 1 the 

agencies require that engines specifically installed in tractors meet fuel efficiency and CO2

 

84 See 76 FR 57146-47.

85 U.S. Environmental Protection Agency. “Peer Review of the Greenhouse Gas Emissions Model (GEM) and 

EPA’s Response to Comments.” EPA-420-R-11-007. Last access on November 24, 2014 at 

http://www.epa.gov/otaq/climate/documents/420r11007.pdf.

86 See EPA’s web site at http://www.epa.gov/otaq/climate/gem.htm for the Phase 1 GEM revision dated May 2013, 

made to accommodate a revision to 49 CFR 535.6(b)(3).
Page 91 of 850

standards over only the SET but not the FTP. This requirement was intended to reflect that 

tractor engines typically operate near steady-state conditions versus transient conditions. See 76 

FR 57159/2-3. The agencies adopted the converse for engines installed in vocational vehicles. 

That is, these engines must meet fuel efficiency and CO2 standards over only the hot-start FTP 

but not the SET. This requirement was intended to reflect that vocational vehicle engines 

typically operate under transient conditions versus steady-state conditions (76 FR 57178). For 

both tractor and vocational vehicle engines in Phase 1, EPA set CH4 and N2O emissions cap 

standards over the cold-start and hot-start FTP only and not over the SET duty cycle. See 

Section II. D. for details on how we propose to modify the engine test procedure for Phase 2.

B. Phase 2 Proposed Regulatory Structure

For Phase 2, the agencies are proposing to modify the regulatory structure used for Phase 

1. Note that we are not proposing to apply the new Phase 2 regulatory structure for compliance 

with the Phase 1 standards. The structure used to demonstrate compliance with the Phase 1 

standards will remain as finalized in the Phase 1 regulation. The modifications we are proposing 

are consistent with the agencies’ Phase 1 commitments to consider a range of regulatory

approaches during the development of future regulatory efforts (76 FR at 57133), especially for 

vehicles not already subject to full vehicle chassis dynamometer testing. For example, we 

committed to consider a more sophisticated approach to vehicle testing to more completely 

capture the complex interactions within the total vehicle, including the engine and powertrain 

performance. We also intended to consider the potential for full vehicle certification of complete 

tractors and vocational chassis using a chassis dynamometer test procedure. We also considered 

chassis dynamometer testing of complete tractors and vocational chassis as a complementary

approach for validating a more complex vehicle simulation approach. We also committed to 

consider the potential for a regulatory program for some of the trailers hauled by tractors. After 

considering these various approaches, the agencies are proposing a structure in which regulated 

tractor and vocational chassis manufacturers would additionally enter engine and powertrainrelated inputs into GEM, which was not allowed in Phase 1. 

For trailer manufacturers, which would be subject to first-time standards under the 

proposal, we are also proposing GEM-based certification. However, we are proposing a 

simplified structure that would allow certification without the manufacturers actually running

GEM. More specifically, the agencies have developed a simple equation that uses the same 

trailer inputs as GEM to represent the emission impacts of aerodynamic improvements, tire 

improvements, and weight reduction. As described in Chapter 2.10.6 of the draft RIA, these 

equations have nearly perfect correlation with GEM so that they can be used instead of GEM 

without impacting stringency.

We are proposing both required and optional test procedures to provide these additional 

GEM inputs. We are also proposing to significantly expand the number of technologies 

recognized in GEM. Further, we are proposing to modify the GEM duty cycles and to further 

subdivide the vocational vehicle subcategory to better represent real-world vehicle operation. In 

contrast to these changes, we are proposing to maintain essentially the same chassis 

dynamometer test procedure for certifying complete heavy-duty pickups and vans.
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(1) Other Structures Considered

To follow-up on the commitment to consider other approaches, the agencies spent 

significant time and resources in evaluating six different options for demonstrating compliance 

with the proposed Phase 2 standards. These six options include full vehicle chassis 

dynamometer testing, full vehicle simulation, and vehicle simulation in combination with 

powertrain testing, engine testing, engine electronic controller and/or transmission electronic 

controller testing. The agencies evaluated these options in terms of the capital investment 

required of regulated manufacturers to conduct the testing and/or simulation, the cost per test, the 

accuracy of the simulation, and the challenges of validating the results. Other considerations 

included the representativeness to the real world behavior, maintaining existing Phase 1 

certification approaches that are known to work well, enhancing the Phase 1 approaches that 

could use improvements, the alignment of test procedures for determining GHG and non-GHG 

emissions compliance, and the potential to circumvent the intent of the test procedures.

Chassis dynamometer testing is used extensively in the development and certification of 

light-duty vehicles. It also is used in Phase 1 for complete Class 2b/3 pickups and vans, as well 

as for certain incomplete vehicles (at the manufacturer’s option). The agencies considered 

chassis dynamometer testing more broadly as a heavy-duty fuel efficiency and GHG certification 

option because chassis dynamometer testing has the ability to evaluate a vehicle’s performance 

in a manner that most closely resembles the vehicle’s in-use performance. Nearly all of the fuel 

efficiency technologies can be evaluated on a chassis dynamometer, including the vehicle 

systems’ interactions that depend on the behavior of the engine, transmission, and other vehicle 

electronic controllers. One challenge associated with application of wide-spread heavy-duty 

chassis testing is the small number of heavy-duty chassis test sites that are available in North 

America. As discussed in draft RIA Chapter 3, the agencies were only able to locate 11 heavyduty chassis test sites. However, we have seen an increased interest in building new sites since 

issuing the Phase 1 Final Rule. For example, EPA is currently building a heavy-duty chassis 

dynamometer with the ability to test up to 80,000 pound vehicles at the National Vehicle and 

Fuel Emissions Laboratory in Ann Arbor, Michigan.

Nevertheless, the agencies continue to be concerned about proposing a chassis test 

procedure for certifying tractors or vocational chassis due to the initial cost of a new test facility

and the large number of heavy duty tractor and vocational chassis variants that could require 

testing. We have also concluded that for heavy-duty tractors and vocational chassis, there can be 

increased test-to-test variability under chassis dynamometer test conditions. First, the agencies 

recognize that such testing requires expensive, specialized equipment that is not widely

available. The agencies estimate that it would vary from about $1.3 to $4.0 million per new test 

site depending on existing facilities.87 In addition, the large number of heavy-duty vehicle 

configurations would require significant amounts of testing to cover the sector. For example, for 

Phase 1 tractor manufacturers typically certified several thousand variants of one single tractor 

model. Finally, EPA’s evaluation of heavy-duty chassis dynamometer testing has shown that the 

 

87

 03-19034 TASK 2 Report-Paper 03-Class8_hil_DRAFT, September 30, 2013.
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variation of chassis test results is greater than light-duty testing, up to 3 percent worse, based on 

our sponsored testing at Southwest Research Institute.88 Although the agencies are not proposing 

chassis dynamometer certification of tractors and vocational chassis, we believe such an 

approach could be appropriate in the future for some heavy duty vehicles if more test facilities 

become available and if the agencies are able to address the large number of vehicle variants that 

might require testing. We request comment on whether or not a chassis dynamometer test 

procedure should be required in lieu of the vehicle simulation approach we are proposing. Note, 

as discussed in Section II. C. (4) (b)that we are also proposing a modest complete tractor heavyduty chassis dynamometer test program only for monitoring complete tractor fuel efficiency

trends over the implementation timeframe of the Phase 1 and proposed Phase 2 standards.

Another option considered for certification involves testing a vehicle’s powertrain in a 

modified engine dynamometer test facility. In this case the engine and transmission are installed 

in a laboratory test facility and a dynamometer is connected to the output shaft of the 

transmission. GEM or an equivalent vehicle simulation computer program is then used to 

control the dynamometer to simulate vehicle speeds and loads. The step-by-step test procedure 

considered for this option was initially developed as an option for hybrid powertrain testing for 

Phase 1. A key advantage of the powertrain test approach is that it directly measures the 

effectiveness of the engine, the transmission, and the integration of the two. Engines and 

transmissions are particularly challenging to simulate within a computer program like GEM 

because engines and transmissions installed in vehicles today are actively and interactively 

controlled by their own sophisticated electronic controls. These controls already contain 

essentially their own vehicle simulation programs that GEM would then have to otherwise 

simulate.

We believe that the capital investment impact for powertrain testing on manufacturers 

could be manageable for those that already have heavy-duty engine dynamometer test cells. We 

have found that in general medium-duty powertrains can be tested in heavy-duty engine test 

cells. EPA has successfully completed such a test facility conversion at the National Vehicle and 

Fuel Emissions Laboratory in Ann Arbor, Michigan. Southwest Research Institute (SwRI) in San 

Antonio, Texas has completed a similar test cell conversion. Oak Ridge National Laboratory in 

Oak Ridge, Tennessee recently completed construction of a new and specialized heavy heavyduty powertrain dynamometer facility. EPA also contracted SwRI to evaluate North America’s 

current capabilities for powertrain testing in the heavy-duty sector and the cost of installing a 

new powertrain cell that would meet agency requirements.89 Results indicated that one supplier 

currently has this capability. We estimate that the upgrade costs to an existing engine test 

facility are on the order of $1.2 million, and a new test facility in an existing building are on the 

order of $1.9 million. We also estimate that current powertrain test cells that could be upgraded 

to measure CO2 emissions would cost approximately $600,000. For manufacturers or suppliers 

wishing to contract out such testing, SwRI estimated that a cost of $150,000 would provide about 

one month of powertrain testing services. Once a powertrain test cell is fully operational, we 

 

88 GEM Validation, Technical Research Workshop, San Antonio, December 10-11, 2014 

89 03-19034 TASK 2 Report-Paper 03-Class8_hil_DRAFT, September 30, 2013 
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estimate that for a nominal powertrain family (i.e. one engine family tested with one 

transmission family), the cost for powertrain installation, testing, and data analysis would be 

$68,972.

Since the Phase 1 Final Rule, the agencies and other stakeholders have completed 

significant new work toward refining the powertrain test procedure itself. The proposed 

regulations provide details of the refined powertrain test procedure. See 40 CFR 1037.550.

Furthermore, the agencies have worked with key transmission suppliers to develop an 

approach to define transmission families. Coupled with the agencies existing definitions of 

engine families (40 CFR 1036.230), we are proposing an approach to define a powertrain family

in 40 CFR 1037.231. We request comment on what key attributes should be considered when 

defining a transmission family.

We believe that a combination of a robust powertrain family definition, a refined 

powertrain test procedure and a refined GEM could become an optimal certification path that 

leverages the accuracy of powertrain testing along with the versatility of GEM, which alleviates 

the need to test a large number of vehicle or powertrain variants. To balance the potential 

advantages of this approach with the fact that it has never been used for vehicle certification in 

the past, we are proposing to allow this approach as an optional certification path, as described in 

Section II.B.(2)(b). To be clear, we are not proposing to require powertrain testing at this time, 

but because this testing would recognize additional technologies that are not recognized directly 

in GEM (even as proposed to be amended), we are factoring its use into our stringency

considerations for vocational chassis. We request comment on whether the agencies should 

consider requiring powertrain testing more broadly.

Another regulatory structure option considered was engine-only testing over the GEM 

duty cycles over a range of simulated vehicle configurations. This approach would use GEM to 

generate engine duty cycles by simulating a range of transmissions and other vehicle variations. 

These engine duty cycles then would be programmed into a separate controller of a 

dynamometer connected to an engine’s output shaft. Unlike the chassis dynamometer or 

powertrain dynamometer approaches, which could have significant test facility construction or 

modification costs, this approach has little capital investment impact on manufacturers because 

the majority already have engine test facilities to both develop engines and to certify engines to 

meet both the non-GHG standards and the Phase 1 fuel efficiency and GHG standards. The 

agencies also have been investigating this approach as an alternative way to generate data that 

could be used to represent an engine in GEM. Because this approach captures engine 

performance under transient conditions, this approach could be an improvement over our 

proposed Phase 2 approach of representing an engine in GEM with only steady-state operating 

data. Details of this alternative are described in draft RIA. Because this approach is new and has 

never been used for vehicle development or certification, we are not proposing requiring its use 

as part of the Phase 2 certification process. However, we encourage others to investigate this 

new approach in detail, and we request comment on whether or not the agencies should replace 

our proposed steady-state operation representation of the engine in GEM with this alternative 

approach.
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Additional certification options considered included simulating the engine, transmission, 

and vehicle using a computer program while having the actual transmission electronic controller 

connected to the computer running the vehicle simulation program. The output of the simulation 

would be an engine cycle that would be used to test the engine in an engine test facility. Just as 

in the engine-only test procedure, this procedure would not require significant capital investment 

in new test facilities. An additional benefit of this approach would be that the actual 

transmission controller would be determining the transmission gear shift points during the test, 

without a transmission manufacturer having to reveal their proprietary transmission control logic. 

This approach comes with some technical challenges, however. The model would have to 

become more complex and tailored to each transmission and controller to make sure that the 

controller would operate properly when it is connected to a computer instead of a transmission. 

Some examples of the transmission specific requirements would be simulating all the Controller 

Area Network (CAN) communication to and from the transmission controller and the specific 

sensor responses both through simulation and hardware. The vehicle manufacturer would have 

to be responsible for connecting the transmission controller to the computer, which would 

require a detailed verification process to ensure it is operating properly. Determining full 

compliance with this test procedure would be a significant challenge for the regulatory agencies 

because the agencies would have to be able to replicate each of the manufacturer’s unique 

interfaces between the transmission controller and computer running GEM. 

Finally, the agencies considered full vehicle simulation plus separate engine standards, 

which is the proposed approach for Phase 2. These are discussed in more detail in the following 

sections. 

(2) Proposed Regulatory Structure

Under the proposed structure, tractor and vocational chassis manufacturers would be 

required to provide engine, transmission, drive axle(s) and tire radius inputs into GEM. For 

Phase 1, GEM used default values for all of these, which limited the types of technologies that 

could be recognized by GEM to show compliance with the standards. We are proposing to 

significantly expand GEM to account for a wider range of technological improvements that 

would otherwise need to be recognized through some off-cycle crediting approach. These 

include improvements to the driver controller (i.e., the simulation of the driver), engines, 

transmissions, and axles. Additional technologies that would now be recognized in GEM also 

include lightweight thermoplastic materials, automatic tire inflation systems, advanced cruise 

control systems, engine stop-start idle reduction systems, and axle configurations that decrease 

the number of drive axles. The agencies are also proposing to maintain separate engine 

standards. As described below, we see advantages to having both engine-based and vehiclebased standards. Moreover, the advantages described here for full vehicle simulation do not 

necessarily correspond to disadvantages for engine testing or vice versa. 

(a) Advantages of Full Vehicle Simulation

The agencies’ primary purpose in developing fuel efficiency and GHG emissions 

standards is to increase the use of vehicle technologies that improve fuel efficiency and decrease 

GHG emissions. Under the Phase 1 tractor and vocational chassis standards, there is no

regulatory incentive for manufacturers to adopt new engine, transmission or axle technologies 
Page 96 of 850

because GEM was not configured to recognize these technologies uniquely. By recognizing 

such technologies in GEM under Phase 2, the agencies would be creating a regulatory incentive 

to improve engine, transmission, and axle technologies to improve fuel efficiency and decrease 

GHG emissions. In its 2014 report, NAS also recognized the benefits of full vehicle simulation 

and recommended that Phase 2 incorporate such an approach. 

We anticipate that the proposed Phase 2 approach would create three new specific 

regulatory incentives. First, vehicle manufacturers would have an incentive to use the most 

efficient engines. Since GEM would no longer use the agency default engine in simulation 

manufacturers would have their own more efficient engines recognized in GEM. Under Phase 1, 

engine manufacturers have a regulatory incentive to design efficient engines, but vehicle 

manufacturers do not have a similar regulatory incentive to use efficient engines in their 

vehicles. Second, the proposed approach would create incentives for both engine and vehicle 

manufacturers to design engines and vehicles to work together to ensure that engines actually

operate as much as possible near their most efficient points. This is because Phase 2 GEM 

would allow the vehicle manufactures to use specific transmission, axle, and tire characteristics 

as inputs, thus having the ability to directly recognize many powertrain integration benefits, such 

as downspeeding, and different transmission architectures and technologies, such as automated 

manual transmissions, automatic transmissions,, and different numbers of transmission gears, 

transmission gear ratios, axle ratios and tire revolutions per mile. No matter how well designed, 

all engines have speed and load operation points with differing fuel efficiency and GHG 

emissions. The speed and load point with the best fuel efficiency (i.e., peak thermal efficiency) 

is commonly known as the engine’s “sweet spot”. The more frequently an engine operates near 

its sweet spot, the better the vehicle’s fuel efficiency will be. In Phase 1, a vehicle manufacturer 

receives no regulatory credit for designing its vehicle to operate closer to the sweet spot because 

Phase 1 GEM does not model the actual engine, transmission, axle, or tire revolutions per mile. 

Third, the proposed approach would recognize improvements to the overall efficiency of the 

drivetrain including the axle. The proposed version of GEM would recognize the benefits of 

different axle technologies including axle lubricants, and reducing axle losses such as by 

enabling three-axle vehicles to deliver power to only one rear axle through the proposed postsimulation adjustment approach (see Chapter 4.5 of the Draft RIA). 

In addition to providing regulatory incentives to use more fuel efficient technologies, 

expanding GEM to recognize engine and other powertrain component improvements would also 

provide important flexibility to vehicle manufacturers. The flexibility to effectively trade engine 

and other component improvements against other vehicle improvements would allow vehicle 

manufacturers to better optimize their vehicles to achieve the lowest cost for specific customers. 

Vehicle manufacturers could use this flexibility to reduce overall compliance costs and/or 

address special applications where certain vehicle technologies are not practical. The agencies 

considered in Phase 1 allowing the exchange of emission certification credits generated relative 

to the separate brake-specific (g/hp-hr) engine standards and credits generated relative to the 

vehicle standards (g/ton-mile). However, we did not allow this in Phase 1 due in part to 

concerns about the equivalency of credits generated relative to different standards, with different 

units of measure and different test procedures. The proposed approach for Phase 2 would 

eliminate these concerns because engine and other vehicle component improvements would be 

evaluated relative to the same vehicle standard in GEM. This also means that under the 
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proposed Phase 2 approach there is no need to consider allowing emissions credit trading 

between engine-generated and vehicle-generated credits because vehicle manufacturers are 

directly credited by the combination of engine and vehicle technologies they choose to install in 

each vehicle. Therefore, this approach eliminates one of the concerns about continuing separate 

engine standards, which was that a separate engine standard and a full vehicle standard were 

somehow mutually exclusive. That is not the case. In fact, in the next section we describe how 

we propose to continue the separate engine standard along with recognizing engine performance 

at the vehicle level. The agencies acknowledge that maintaining a separate engine standard 

would limit flexibility in cases where a vehicle manufacturer wanted to use less efficient engines 

and make up for them using more efficient vehicle technologies. However, as described below, 

we see important advantages to maintaining a separate engine standard, and we believe they

more than justify the reduced flexibility.

There could be disadvantages to the proposed approach, however. As is discussed in 

Section II.B.(2)(b), some of the disadvantages can be addressed by maintaining separate engine 

standards, which we are proposing to do. We request comment on other disadvantages such as 

those discussed below. 

One disadvantage of the proposed approach is that it would increase complexity for the 

vehicle standards. For example, vehicle manufacturers would be required to conduct additional 

engine tests and track additional GEM inputs for compliance purposes. However, we believe 

that most of the burden associated with this increased complexity would be an infrequent burden 

of engine testing and updating information systems to track these inputs.

Because GEM measures performance over specific duty cycles intended to represent 

average operation of vehicles in-use, the proposed approach might also create an incentive to 

optimize powertrains and drivetrains for the best GEM performance rather than the best in-use 

performance for a particular application. This is always a concern when selecting duty cycles for 

certification. There will always be instances, however infrequent, where specific vehicle 

applications will operate differently than the duty cycles used for certification. The question is 

would these differences force manufacturers to optimize vehicles to the certification duty cycles 

in a way that decreases fuel efficiency and increases GHG emissions in-use? We believe that the 

certification duty cycles would not prevent manufacturers from properly optimizing vehicles for 

customer fuel efficiency. First, the impact of the certification duty cycles would be relatively 

small because they affect only a small fraction of all vehicle technologies. Second, the emission 

averaging and fleet average provisions mean that the proposed regulations would not require all 

vehicles to meet the standards. Vehicles exceeding a standard over the duty cycles because they

are optimized for different in-use operation can be offset by other vehicles that perform better 

over the certification duty cycles. Third, vehicle manufacturers would also have the ability to 

lower such a vehicle’s measured GHG emissions by adding technology that would improve fuel 

efficiency both over the certification duty cycles and in-use. The proposed standards are not 

intended to be at a stringency where manufacturers would be expected to apply all technologies 

to all vehicles. Thus, there should be technologies available to add to vehicle configurations that 

initially fail to meet the Phase 2 proposed standards. Fourth, we are proposing further subcategorization of the vocational vehicle segment, tripling the number of subcategories within this 

segment from 3 to 9. These 9 subcategories would divide each of the 3 Phase 1 weight 

categories into 3 additional vehicle speed categories. Each of the 3 speed categories would have 
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unique duty cycle weighting factors to recognize that different vocational chassis are configured 

for different vehicle speed applications. Furthermore, we are proposing 9 unique standards for 

each of the subcategories. This further subdivision better recognizes technologies’ performance 

under the conditions for which the vocational chassis was configured to operate. This further 

decreases the potential of the certification duty cycles to encourage manufacturers to configure 

vocational chassis differently than the optimum configuration for specific customers’ 

applications. Finally, as required by Section 202 (a) (1) and 202 (d) of the CAA, EPA is 

proposing specific GHG standards which would have to be met in-use.

One disadvantage of our proposed full vehicle simulation approach is the potential 

requirement for engine manufacturers to disclose otherwise proprietary information to vehicle 

manufacturers who install their engines. Under the proposed approach, vehicle manufacturers 

would need to know details about engine performance long before production, both for 

compliance planning purposes, as well as for the actual submission of applications for 

certification. Moreover, vehicle manufacturers would need to know details about the engine’s 

performance that are generally not publicly available – specifically the detailed fuel consumption 

of an engine over many steady-state operating points. We request comment on whether or not 

such information could be used to “reverse engineer” intellectual property related to the 

proprietary design of engines, and what steps the agencies could take to address this.

The agencies also generally request comment on the advantages and disadvantages of the 

proposed structure that would require vehicle manufacturers to provide additional inputs into 

GEM to represent the engine, transmission, drive axle(s), and loaded tire radius.

(b) Advantages of Separate Engine Standards

For engines installed in tractors and vocational vehicle chassis, we are proposing to 

maintain separate engine standards for fuel consumption and GHG emissions in Phase 2 for both 

SI and CI engines. Moreover, we are proposing new more stringent engine standards for CI 

engines. While the vehicle standards alone are intended to provide sufficient incentive for 

improvements in engine efficiency, we continue to see important advantages to maintaining 

separate engine standards for both SI and CI engines. The agencies believe the advantages 

described below are critical to fully achieve the goals of the NHTSA and EPA standards. 

First, EPA has a robust compliance program based on engine testing. For the Phase 1 

standards, we applied the existing criteria pollutant compliance program to ensure that engine 

efficiency in actual use reflected the improvements manufacturers claimed during certification. 

With engine-based standards, it is straightforward to hold engine manufacturers accountable by 

testing in-use engines. If the engines exceed the standards, they can be required to correct the 

problem or perform other remedial actions. Without separate engine standards in Phase 2, 

addressing in-use compliance becomes more subjective. Having clearly defined compliance 

responsibilities is important to both the agencies and to the market.

Second, engine standards for CO2 and fuel efficiency force engine manufacturers to 

optimize engines for both fuel efficiency and control of non-CO2 emissions at the same engine 

operating points. This is of special concern for NOX emissions, given the strong counterdependency between engine-out NOX emissions and fuel consumption. By requiring engine 
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manufacturers to comply with both NOX and CO2 standards using the same test procedures, the 

agencies ensure that manufacturers include technologies that can be optimized for both rather 

than alternate calibrations that would trade NOX emissions against fuel consumption depending 

how the engine or vehicle is tested. In the past, when there was no CO2 engine standard and no 

steady-state NOX standard, some manufacturers chose this dual calibration approach instead of 

investing in technology that would allow them to simultaneously reduce both CO2 and NOX. 

Third, engine fuel consumption can vary significantly between transient operation and 

steady-state operation, and we are proposing only steady-state engine operating data as the 

required engine input into GEM for both tractor and vocational chassis certification. Because 

vocational vehicles can spend significant operation under transient engine operation, the separate 

engine standard for engines installed in vocational vehicles is a transient test. Therefore, the 

separate engine standard for vocational engines provides the only measure of engine fuel 

consumption and CO2 emissions under transient conditions. Without a transient engine test we 

would not be able to ensure control of fuel consumption and CO2 emissions under transient 

engine conditions.

It is worth noting that these first three advantages are also beneficial for the marketplace. 

In these respects, the separate engine standards allow each manufacturer to be confident that its 

competitors are playing by the same rules. The agencies believe that the absence of a separate 

engine standard would leave open the possibility that a manufacturer might choose to cut corners 

with respect to in-use compliance margins, the NOX -CO2 tradeoff, or transient controls. 

Concerns that competitors might take advantage of this can put a manufacturer in a difficult 

situation. On the other hand knowing that the agencies are ensuring all manufacturers are 

complying fully can eliminate these concerns.

Finally, the existence of meaningful separate engine standards allows the agencies to 

exempt certain vehicles from some or all of the vehicle standards and requirements without 

forgoing the engine improvements. A good example of this is the off-road vehicle exemption in 

40 CFR 1037.631 and 49 CFR 535.3(g), which exempts vehicles “intended to be used 

extensively in off-road environments” from the vehicle requirements. The engines used in such 

vehicles must still meet the engine standards of 40 CFR part 1036 and 49 CFR 535.5(d). The 

agencies see no reason why efficient engines cannot be used in such vehicles. However, without 

separate engine standards, there would be no way to require them to be efficient.

In the past there has been some confusion about the Phase 1 separate engine standards 

somehow preventing the recognition of engine-vehicle optimization that vehicle manufacturers 

perform to minimize a vehicle’s overall fuel consumption. It was not the existence of separate 

engine standards that prevented recognition of this optimization. Rather it was that the agencies 

did not allow manufacturers to enter inputs into GEM that characterized unique engine 

performance. For Phase 2 we are proposing to require that manufacturers input such data 

because we intend for GEM to recognize this engine-vehicle optimization. The continuation of 

separate engine standards in Phase 2 does not undermine in any way the recognition of this 

optimization in GEM.

The agencies request comment on the advantages and disadvantages of the proposal to 

maintain separate engine standards and to increase the stringency of the CI engine standards. We 
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would also welcome suggested alternative approaches that would achieve the same goals. It is 

important to emphasize that the agencies see the advantages of separate engine standards as 

fundamental to the success of the program and do not expect to adopt alternative approaches that 

fall short of these goals. 

Note that commenters opposing separate engine standards should also be careful 

distinguish between concerns related to the stringency of the proposed engine standards, from 

concerns inherent to any separate engine standards whatsoever. When meeting with 

manufacturers prior to this proposal, the agencies heard many concerns about the potential 

problems with separate engines standards that were actually concerns about separate engine 

standards that are too stringent. However, we see these as two different issues. The agencies do 

recognize that setting engine standards at a high stringency could increase the cost to comply

with the vehicle standard, if lower-cost vehicle technologies are available. Additionally, the 

agencies recognize that setting engine standards at a high stringency may promote the use of 

large-displacement engines, which have inherent heat transfer and efficiency advantages over 

smaller displacement engines over the engine test cycles, though a smaller engine may be more 

efficient for a given vehicle application. Thus we encourage commenters supporting the separate 

engine standards to address the possibility of unintended consequences such as these.

C. Proposed Vehicle Simulation Model – Phase 2 GEM 90

For tractors and vocational vehicle chassis, the agencies propose that manufacturers 

would be required to meet vehicle-based standards, and certification to these standards would be 

facilitated by the required use of the vehicle simulation computer program called, “Greenhouse 

gas Emissions Model” or “GEM.” GEM was created for Phase 1 for the exclusive purpose of

certifying tractors and vocational chassis. The agencies are proposing to modify GEM and to

require vehicle manufacturers to provide additional inputs into GEM to represent the engine, 

transmission, drive axle(s), and loaded tire radius. For Phase 1, GEM used agency default values 

for all of these parameters. Under the proposed approach for Phase 2, vehicle manufacturers 

would be able to use these technologies, plus additional technologies to demonstrate compliance 

with the applicable standards. The additional technologies include lightweight thermoplastic 

materials, automatic tire inflation systems, advanced cruise control systems, engine stop-start 

idle reduction systems, and axle configurations that decrease the number of drive axles to 

comply with the standards.

(1) Description of the Proposed Modifications to GEM

As explained above, GEM is a computer program that was originally developed by EPA 

specifically for manufacturers to use to certify to the Phase 1 tractor and vocational chassis 

standards. GEM mathematically combines the results of vehicle component test procedures with 

other vehicle attributes to determine a vehicle’s certified levels of fuel consumption and CO2

 

90 The specific version of GEM used to develop the proposed standards, and which we propose to use for 

compliance purposes is also known as GEM 3.0.
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emissions. For Phase 1 the required inputs to GEM include vehicle aerodynamics information, 

tire rolling resistance, and whether or not a vehicle is equipped with certain lightweight highstrength steel or aluminum components, a tamper-proof speed limiter, or tamper-proof idle 

reduction technologies for tractors. The vocational vehicle inputs to GEM for Phase 1 only 

included tire rolling resistance. For Phase 1 the GEM’s inputs did not include engine test results 

or attributes related to a vehicle’s powertrain; namely, its transmission, drive axle(s), or loaded 

tire radius. Instead, for Phase 1 the agencies specified a generic engine and powertrain within 

GEM, and for Phase 1 these cannot be changed in GEM.

For this proposal GEM has been modified and validated against a set of experimental 

data that represents over 130 unique vehicle variants. EPA believes this new version of GEM is 

an accurate and cost-effective alternative to measuring fuel consumption and CO2 over a chassis 

dynamometer test procedure. Some of the key proposed modifications would necessitate 

required and optional vehicle component test procedures to generate additional GEM inputs. 

The results of which would provide additional inputs into GEM. These include a new required 

engine test procedure to provide steady-state engine fuel consumption and CO2 inputs into GEM. 

We are also seeking comment on a newly developed engine test procedure that also captures 

transient engine performance for use in GEM. We are proposing to require inputs that describe 

the vehicle’s transmission type, and its number of gears and gear ratios. We are proposing an 

optional powertrain test procedure that would provide inputs to override the agencies’ simulated 

engine and transmission in GEM. We are proposing to require inputs that describe the vehicle’s 

drive axle(s) type (e.g., 6x4 or 6x2) and axle ratio. We are also seeking comment on an optional 

axle efficiency test procedure to override the agencies’ simulated axle in GEM. We are 

proposing to significantly expand the number of technologies that are recognized in GEM. 

These include recognizing lightweight thermoplastic materials, automatic tire inflation systems, 

advanced cruise control systems, engine stop-start idle reduction systems, and axle 

configurations that decrease the number of drive axles. We are seeking comment on recognizing 

(outside of the GEM simulation) additional technologies such as high efficiency glass and low 

global warming potential air conditioning refrigerants. To better reflect real-world operation, we 

are also proposing to revise the vehicle simulation computer program’s urban and rural highway 

duty cycles to include changes in road grade. We are seeking comment on whether or not these 

duty cycles should also simulate driver behavior in response to varying traffic patterns. We are 

proposing a new duty cycle to capture the performance of technologies that reduce the amount of 

time a vehicle’s engine is at idle during a workday when the vehicle is not moving. And to better 

recognize that vocational vehicle powertrains are configured for particular applications, we are 

proposing to further subdivide the vocational chassis category into three different vehicle speed 

categories, where GEM weights the individual duty cycles’ results of each of the speed 

categories differently Section 4.2 of the RIA details all these modifications. This section briefly 

describes some of the key proposed modifications to GEM.

(a) Simulating Engines for Vehicle Certification

Before describing the proposed approach for Phase 2, this section first reviews how 

engines are simulated for vehicle certification in Phase 1. GEM for Phase 1 simulates the same 

generic engine for any vehicle in a given regulatory subcategory with a data table of steady-state 

engine fuel consumption mass rates (g/s) versus a series of steady-state engine output shaft 

speeds (revolutions per minute, rpm) and loads (torque, N-m). This data table is also sometimes 
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called a “fuel map” or an “engine map”, although the term “engine map” can mean other kinds of 

data in different contexts. The engine speeds in this map range from idle to maximum governed 

speed and the loads range from engine motoring (negative load) to the maximum load of an 

engine. When GEM runs over a vehicle duty cycle, this data table is linearly interpolated to find 

a corresponding fuel consumption mass rate at each engine speed and load that is demanded by

the simulated vehicle operating over the duty cycle. The fuel consumption mass rate of the 

engine is then integrated over each duty cycle in GEM to arrive at the total mass of fuel 

consumed for the specific vehicle and duty cycle. Under Phase 1, manufacturers were not 

allowed to input their own engine fuel maps to represent their specific engines in the vehicle 

being simulated in GEM. Because GEM was programmed with fixed engine fuel maps for Phase 

1 that all manufacturers had to use, interpolation of the tables themselves over each of the three 

different GEM duty cycles did not have to closely represent how an actual engine might operate 

over these three different duty cycles.

In contrast, for Phase 2 we are proposing a new and required steady-state engine 

dynamometer test procedure for manufacturers to use to generate their own engine fuel maps to 

represent each of their engine families in GEM. The proposed Phase 2 approach is consistent 

with the 2014 NAS Phase 2 First Report recommendation.91 To validate this approach we 

compared the results from 28 individual engine dynamometer tests. Three different engines were 

used to generate this data, and these engines were produced by two different engine 

manufacturers. One engine was tested at three different power ratings (13 liters at 410, 450 & 

475 hp) and one engine was tested at two ratings (6.7 liters at 240 and 300 hp), and other engine 

with one rating (15 liters 455 hp) service classes. For each engine and rating our proposed 

steady-state engine dynamometer test procedure was conducted to generate an engine fuel map 

to represent that particular engine in GEM. Next, with GEM we simulated various vehicles in 

which the engine could be installed. For each of the GEM duty cycles we are proposing, namely

the urban local (ARB Transient), urban highway with road grade (55 mph), and rural highway

with road grade (65 mph) duty cycles, we determined the GEM result for each vehicle 

configuration, and we saved the engine output shaft speed and torque information that GEM 

created to interpolate the steady-state engine map for each vehicle configuration We then had 

this same engine output shaft speed and torque information programmed into an engine 

dynamometer controller, and we had each engine perform the same duty cycles that GEM 

demanded of the simulated version of the engine. We then compared the GEM results based on 

GEM’s linear interpolation of the engine maps to the measured engine dynamometer results. We 

concluded that for the 55 mph and 65 mph duty cycles, GEM’s interpolation of the steady-state 

data tables was sufficiently accurate versus the measured results. This is an outcome one would 

reasonably expect because even with changes in road grade, the 55 mph and 65 mph duty cycles 

do not demand rapid changes in engine speed or load. The 55 mph and 65 mph duty cycles are 

nearly steady-state, as far as engine operation is concerned, just like the engine maps themselves. 

However, for the ARB Transient cycle, we observed a consistent bias, where GEM consistently 

under-predicted fuel consumption and CO2 emissions. This low bias over the 28 engine tests 

 

91 National Academy of Science. “Reducing the Fuel Consumption and GHG Emissions of Medium- and HeavyDuty Vehicles, Phase Two, First Report.” 2014. Recommendation 3.8.
Page 103 of 850

ranged from 4.2 percent low to 7.8 percent low. The mean was 5.9 percent low and the 90th

percentile value was 7.1 percent low. These observations are consistent with the fact that 

engines generally operate less efficiently under transient conditions than under steady-state 

conditions. 

A number of reasons explain this consistent trend. For example, under rapidly changing 

engine conditions, it is generally more challenging to program an engine electronic controller to 

respond with optimum fuel injection rate and timing, exhaust gas recirculation valve position, 

variable nozzle turbo-charger vane position and other set points than it is to do so under steadystate conditions. Transient heat and mass transfer within the intake, exhaust, and combustion 

chambers also tend to increase turbulence and enhance energy loss to engine coolant during 

transient operation. Furthermore, because exhaust emissions control is more challenging under 

transient engine operation, engineering tradeoffs sometimes need to be made between fuel 

efficiency and transient emissions control. Special calibrations are typically also required to 

control smoke and manage exhaust temperatures during transient operation for a transient cycle. 

We are confident that this low bias in GEM would continue to exist well into the future if we 

were to test additional engines. However, with the range of the results that we have generated so 

far we are somewhat less confident in proposing a single numerical value to correct for this 

effect over the ARB Transient duty cycle. Based on the data we have collected so far, we are 

conservatively proposing to apply a 5.0 percent correction factor to GEM’s ARB Transient 

results. Note that adjustment would be applied internal to GEM, and no manufacturer input or 

action would be needed. This means that for GEM fuel consumption and CO2 emissions results 

that were generated using the steady-state engine map representation of an engine in GEM, a 

1.05 multiplier would be applied to only the ARB Transient result. If a manufacturer chooses to 

perform the optional powertrain test procedure we are proposing, then this 1.05 multiplier to the 

ARB Transient would not apply (since we know of no bias in that optional powertrain test). For 

the same reason, if we were to replace the proposed steady-state engine map in GEM with the 

alternative approach detailed in draft RIA, then this 1.05 multiplier would not apply. We request 

comment on whether or not this single value multiplier is an appropriate way to correct between 

steady-state and transient engine fuel consumption and CO2 emissions, specifically over the 

ARB Transient duty cycle. We also request comment on the magnitude of the multiplier itself. 

For example, for the proposal we have chosen a 1.05 multiplier correction value because it is 

conservative but still near the mean bias we observed. However, for the tests we have conducted 

on current technology engines, a 1.05 multiplier would mean that about one half of these engines 

would be penalized by powertrain testing (or if we utilized the alternative engine approach) 

because the actual measured transient impact would be slightly higher than 5 percent. While 

these tests were performed on current technology powertrains rather than the kind of optimized 

powertrains we project for Phase 2, these results raise still some concerns for us. Because we 

intend to incentivize powertrain testing and not penalize it, and because we also encourage 

constructive comments on the alternative approach, we also request comment on increasing the 

magnitude of this ARB Transient multiplier toward the higher end of the biases we observed. 

For example, we request comment on increasing the proposed multiplier from 1.05 to 1.07, 

which is close to the 90th percentile of the results we have collected so far. Using this higher 

multiplier would imply that only about 10 percent of engines powertrain tested or tested under 

the alternative approach would show worse fuel consumption over the ARB Transient than its 

respective representation in a steady-state data table in GEM. This would mean that the 
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remaining 90 percent of engines powertrain tested would receive additional credit in GEM. 

Using 1.07 would essentially guarantee that any powertrain that was significantly more efficient 

than current powertrains would receive meaningful credit for the improvement. However, this 

value would also provide credits for many current powertrain designs.

We also request comment as to whether or not there might be certain vehicle subcategories or certain small volume vocational chassis, where using the Phase 1 approach of using 

a generic engine table might be more appropriate. We also request comment as to whether or not 

the agencies should provide default generic engine maps in GEM for Phase 2 and allow 

manufacturers to optionally override these generic maps with their own maps, which would be 

generated according to our proposed engine dynamometer steady-state test procedure. 

(b) Simulating Human Driver Behavior and Transmissions for Vehicle Certification

GEM for Phase 1 simulates the same generic human driver behavior and manual 

transmission for all vehicles. The simulated driver responds to changes in the target vehicle 

speed of the duty cycles by changing the simulated positions of the vehicle’s accelerator pedal, 

brake pedal, clutch pedal, and gear shift lever. For simplicity in Phase 1 the GEM driver shifted 

at ideal points for maximum fuel efficiency and the manual transmission was simulated as an 

ideal transmission that did not have any delay time (i.e., torque interruption) between gear shifts 

and did not have any energy losses associated with clutch slip during gear shifts.

In GEM for Phase 2 we are proposing to allow manufacturers to select one of three types 

of transmissions to represent the transmission in the vehicle they are certifying: manual 

transmission, automated manual transmission, and automatic transmission. We are currently in 

the process of developing a dual-clutch transmission type in GEM, but we are not proposing to 

allow its use in Phase 2 at this time. Because production of heavy-duty dual clutch transmissions 

has only begun in the past few months, we do not yet have any experimental data to validate our 

GEM simulation of this transmission type. Therefore, we are requesting comment on whether or 

not there is additional data available for such validation. Should such data be provided in 

comments, we may finalize GEM for Phase 2 with a fourth transmission types for dual clutch 

transmissions. We are also considering an option to address dual clutch transmissions through a 

post-simulation adjustment as discussed in Chapter 4 of the draft RIA.

In the proposed modifications to GEM, the driver behavior and the three different 

transmission types are simulated in the same basic manner as in Phase 1, but each transmission 

type features a unique combination of driver behavior and transmission responses that match

both the driver behavior and the transmission responses we measured during vehicle testing of 

these three transmission types. In general the transmission gear shifting strategy for all of the 

transmissions is designed to shift the transmission so that it is always in the most efficient gear 

for the current vehicle demand, while staying within certain limits to prevent unrealistically high 

frequency shifting. Some examples of these limits are torque reserve limits (which vary as 

function of engine speed), minimum time-in-gear and minimum fuel efficiency benefit to shift to 

the next gear. Some of the differences between the three transmission types include a driver 

“double-clutching” during gear shifts of the manual transmission only, and “power shifts” and 

torque converter torque multiplication, slip, and lock-up in automatic transmissions only. Refer 
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to Chapter 4 of the draft RIA for a more detailed description of these different simulated driver 

behaviors and transmission types.

We considered an alternative approach where transmission manufacturers would provide 

vehicle manufacturers with detailed information about their automated transmissions’ proprietary

shift strategies for representation in GEM. NAS also recommended this approach.

92

 The 

advantages of this approach include a more realistic representation of a transmission in GEM and 

potentially the recognition of additional fuel efficiency improving strategies to achieve additional 

fuel consumption and CO2 emissions reductions. However, there are a number of technical and 

policy disadvantages of this approach. One disadvantage is that it would require the disclosure 

of proprietary information between competing companies because some vehicle manufacturers 

produce their own transmissions and also use other suppliers’ transmissions. There are technical 

challenges too. For example, some transmission manufacturers have upwards of 40 different 

shift strategies programmed into their transmission controllers. Depending on in-use driving 

conditions, some of which are not simulated in GEM (e.g., changing payloads, changing tire 

traction) a transmission controller can change its shift strategy. Representing dynamic switching 

between multiple proprietary shift strategies would be extremely complex to simulate in GEM. 

Furthermore, if the agencies were to propose requiring transmission manufacturers to provide 

shift strategy inputs for use in GEM, then the agencies would have to devise a compliance 

strategy to monitor in-use shift strategies, including a driver behavior model that could be 

implemented as part of an in-use shift strategy test. This too would be very complex. If 

manufacturers were subject to in-use compliance requirements of their transmission shift 

strategies, this could lead to restricting the use of certain shift strategies in the heavy-duty sector, 

which would in turn potentially lead to sub-optimal vehicle configurations that do not improve 

fuel efficiency or adequately serve the wide range of customer needs; especially in the vocational 

vehicle segment. For example, if the agencies were to restrict the use of more aggressive and 

less fuel efficient in-use shift strategies that are used only under heavy loads and steep grades, 

then certain vehicle applications would need to compensate for this loss of capability through the 

installation of over-sized and over-powered engines that are subsequently poorly matched and 

less efficient under lighter load conditions. Therefore, as a policy consideration to preserve 

vehicle configuration choice and to preserve the full capability of heavy-duty vehicles today, the 

agencies are intentionally not requiring transmission manufacturers to submit detailed 

proprietary shift strategy information to vehicle manufacturers to input into GEM. This is not 

unlike Phase 1, where unique transmission and axle attributes were not recognized at all in GEM. 

Instead, the agencies are proposing that vehicle manufacturers choose from among the three 

transmission types that the agencies have already developed, validated, and programmed into 

GEM. The vehicle manufacturers would then enter into GEM their particular transmission’s 

number of gears and gear ratios. The agencies recognize that designing GEM like this would 

 

92 Transportation Research Board 2014. “Reducing the Fuel Consumption and Greenhouse Gas Emissions of 

Medium- and Heavy-Duty Vehicles, Phase Two.” (“Phase 2 First Report”) Washington, D.C., The National 

Academies Press. Cooperative Agreement DTNH22-12-00389. Available electronically from the National 

Academy Press Website at http://www.nap.edu/catalog.php?record_id=12845 (last accessed December 2, 2014). 

Recommendation 3.7.
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exclude a potentially significant reduction from the GEM simulation. However, if a 

manufacturer chooses to use the optional powertrain test procedure, then the agencies’ 

transmission types in GEM would be overridden by the actual data collected during the 

powertrain test, which would recognize the actual benefit of the transmission. Note that the 

optional powertrain test procedure is only advantageous to a vehicle manufacturer if an actual 

transmission is more efficient and has a superior shift strategy compared to its respective 

transmission type simulated in GEM.

(c) Simulating Axles for Vehicle Certification

In GEM for Phase 1 the axle ratio of the primary drive axle and the energy losses 

assumed in the simulated axle itself were the same for all vehicles. For Phase 2 we are 

proposing that the vehicle manufacturer input into GEM the axle ratio of the primary drive axle. 

This input would recognize the intent to operate the engine at a particular engine speed when the 

transmission is operating in its highest transmission gear; especially for the 55 mph and 65 mph 

duty cycles in GEM. This input facilitates GEM’s recognition of vehicle designs that take 

advantage of operating the engine at the lowest possible engine speeds. This is commonly

known as “engine down-speeding”, and the general rule-of-thumb for heavy-duty engines is that 

for every 100 rpm decrease in engine speed, there can be about a 1 percent decrease in fuel 

consumption and CO2 emissions. Therefore, it is important that GEM allow this value to be 

input by the vehicle manufacturer. Axle ratio is also straightforward to verify during any in-use 

compliance audit.

We are proposing a fixed axle ratio energy efficiency of 95.5 percent at all speeds and 

loads, but are requesting comment on whether this pre-specified efficiency is reasonable. 

However, we know that this efficiency actually varies as a function of axle speed and axle input 

torque. Therefore, as an exploratory test we have created a modified version of GEM that has as 

an input a data table of axle efficiency as a function of axle speed and axle torque. The modified 

version of GEM subsequently interpolates this table over each of the duty cycles to represent a 

more realistic axle efficiency at each point of each duty cycle. We have also created a draft axle 

ratio efficiency test procedure that requires the use of a dynamometer test facility. This 

procedure includes the use of a baseline fuel-efficient synthetic gear lubricant manufactured by

BASF.93 This baseline will be used to gauge improvements in axle design and lubricants. The 

draft test procedure includes initial feedback that we have received from axle manufacturers and 

our own engineering judgment. Refer to 40 CFR 1037.515 of the Phase 2 proposed regulations, 

which contain this draft test procedure. This test procedure could be used to generate the results 

needed to create the axle efficiency data table for input into GEM. However, the agencies have 

not yet conducted experimental tests of axles using this draft test procedure so we are reluctant to 

propose this test procedure as either mandatory or even optional at this time. Rather we request 

comment as to whether or not we should finalize this test procedure and either require its use or 

allow its use optionally to determine an axle efficiency data table as an input to GEM, which 

would override the fixed axle efficiency we are proposing at this time. We also request comment 

 

93 BASF TI/EVO 0137 e, Emgard® FE 75W-90 Fuel Efficient Synthetic Gear Lubricant.
Page 107 of 850

on improving or otherwise refining the test procedure itself. Note that the agencies believe that 

allowing the GEM default axle efficiency to be replaced by manufacturer inputs only makes 

sense if the manufacturer inputs is are the results of a specified test procedure that we could 

verify by our own independent testing of the axle.

In addition to proposing to require the primary drive axle ratio input into GEM (and 

potentially an option to input an actual axle efficiency data table), we are also proposing that the 

vehicle manufacturer input into GEM whether or not one or two drive axles are driven by the 

engine. When a heavy-duty vehicle is equipped with two rear axles where both are driven by the 

engine, this is called a “6x4” configuration. “6” refers to the total number of wheel hubs on the 

vehicle. In the 6x4 configuration there are two front wheel hubs for the two steer wheels and 

tires plus four rear wheel hubs for the four rear wheels and tires (or more commonly four sets of 

rear dual wheels and tires). “4” refers to the number of wheel hubs driven by the engine. These 

are the two rear axles that have two wheel hubs each. Compared to a 6x4 configuration a 6x2 

configuration decreases axle energy loss due to friction and oil pumping in two driven axles, by

driving only one axle. The decrease in fuel consumption and CO2 emissions associated with a 

6x2 versus 6x4 axle configuration is estimated to be 2.5 percent. 94 Therefore, in the proposed 

Phase 2 version of GEM, if a manufacturer simulates a 6x2 axle configuration, GEM decreases 

the overall GEM result by 2.5 percent. Note that GEM will similarly decrease the overall GEM 

result by 2.5 percent for a 4x2 tractor or Class 8 vocational chassis configuration if it has only

two wheel hubs driven. Note that we are not proposing that GEM have an option to increase the 

overall GEM result by some percentage by selecting, say, a 6x6 or 8x8 option if the front axle(s) 

are driven. Because these configurations are only manufactured for specialized vehicles that 

require extra traction for off-road applications, they are very low volume sales and their 

increased fuel consumption and CO2 emissions are not significant in comparison to the overall 

reductions of the proposed Phase 2 program. Note that 40 CFR 1037.631 (for off-road 

vocational vehicles), which is being continued from the Phase 1 program, would likely exempt 

many of these vehicles from the vehicle standards. 

Instead of directly modeling 6x4 or 6x2 axle configuration, we are proposing use of a 

post-simulation adjustment approach discussed in Chapter 4 of the drat RIA to model benefits of 

different axle configuration. 

(d) Simulating Accessories for Vehicle Certification

Phase 1 GEM uses a fixed power consumption value to simulate the fuel consumed for 

powering accessories such as power steering pumps and alternators. While the agencies are not 

proposing any changes to this approach for Phase 2, we are requesting comment on whether or 

not we should allow some manufacturer input to reflect the installation of accessory components 

that result in lower accessory loads. For example, we could consider an accessory load reduction 

GEM input based on installing a number of qualifying advanced accessory components that 

 

94 NACFE. Executive Report – 6x2 (Dead Axle) Tractors. November 2010. See Docket EPA-HQ-OAR-2014-

0827.
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could be in production during Phase 2. We request comment on identifying such advanced 

accessory components, and we request comment on defining these components in such a way

that they can be unambiguously distinguished from other similar components that do not 

decrease accessory loads. We also request comment on how much of a decrease in accessory

load should be programmed into GEM if qualifying advanced accessory components are 

installed.

(e) Aerodynamics for Tractor, Vocational Vehicle, and Trailer Certification

For GEM in Phase 2 the agencies propose to simulate aerodynamic drag in largely the 

same manner as in Phase 1. For vocational chassis we propose to continue to use the same 

prescribed products of drag coefficient times vehicle frontal area (Cd*A) that were predefined 

for each of the vocational subcategories in Phase 1. For tractors we propose to continue to use 

an aerodynamic bin approach similar to the one that exists in Phase 1 today. This approach 

requires tractor manufacturers to conduct a certain amount of coast-down vehicle testing, 

although manufacturers have the option to conduct scaled wind tunnel testing and/or 

computational fluid dynamics modeling. The results of these tests determine into which bin a 

vehicle is assigned. Then in GEM the aerodynamic drag coefficient for each vehicle in the same 

bin is the same. This approach helps to account for limits in the repeatability of aerodynamic 

testing and it creates a compliance margin since any test result which keeps the vehicle in the 

same aerodynamic bin is considered compliant. However, for Phase 2 we are proposing new 

boundary values for the bins themselves and we are adding two additional bins in order to 

recognize further advances in aerodynamic drag reduction beyond what was recognized in Phase 

1. Furthermore, while Phase 1 GEM used predefined frontal areas for tractors while the 

manufacturers input a Cd value, the agencies propose that manufacturers would use a measured 

drag area (CdA) value for each tractor configuration for Phase 2. See 40 CFR 1037.525. 

In addition to these proposed changes we are proposing a number of aerodynamic drag 

test procedure improvements. One proposed improvement is to update the so-called standard 

trailer that is prescribed for use during aerodynamic drag testing of a tractor – that is, the 

hypothetical trailer modeled in GEM to represent a trailer paired with the tractor in actual use. In 

Phase 1 a non-aerodynamic 53-foot long box-shaped dry van trailer was specified as the standard 

trailer for tractor aerodynamic testing (see 40 CFR 1037.501(g)). For Phase 2 we are proposing 

to modify this standard trailer for tractor testing to make it more similar to the trailers we would 

require to be produced during the Phase 2 timeframe. More specifically, we would prescribe the 

installation of aerodynamic trailer skirts (and low rolling resistance tires as applied in Phase 1) 

on the reference trailer, as discussed in further in Section III.E.2. As explained more fully in 

Sections III and IV below, the agencies believe that tractor-trailer pairings will be optimized 

aerodynamically to a significant extent in-use (such as using high-roof cabs when pulling box 

trailers), and that this real-world optimization should be reflected in the certification testing. We 

also request comment on whether or not the Phase 2 standard trailer should include the 

installation of other aerodynamic devices such as a nose fairing, an under tray, or a boat tail or 

trailer tail. Would a standard trailer including these additional components make the tractor 

program better?

Another proposed aerodynamic test procedure improvement is intended to better account 

for average wind yaw angle to better reflect the true impact of aerodynamic features on the in-
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use fuel consumption and CO2 emissions of tractors. Refer to the proposed test procedures in 40 

CFR 1037.525 for further details of these aerodynamic test procedures.

For trailer certification, the agencies are proposing to use GEM in a different way than

GEM is used for tractor certification in Phase 1 and Phase 2. As described in Section IV, the 

proposed trailer standards are based on GEM simulation, but trailer manufacturers would not run 

GEM for certification. Instead, manufacturers would use a simple equation to replicate GEM 

performance from the inputs. As with GEM, the only technologies recognized by this GEMbased equation for trailer certification are aerodynamic technologies, tire technologies (including 

tire rolling resistance and automatic tire inflation systems), and some weight reduction 

technologies. Note that since the purpose of this equation is to measure GEM performance, it 

can be considered as simply another form of the model using a different input interface. Thus, 

for simplicity, the remainder of this Section II. C. sometimes discusses GEM as being used for 

trailers, without regard to how manufacturers will actually input GEM variables.

Similar to tractor certification, we propose that trailer manufacturers may at their option 

conduct some amount of aerodynamic testing (e.g., coast-down testing, scale wind tunnel testing, 

computational fluid dynamics modeling, or possibly aerodynamic component testing) and use 

this information with the equation.

95

 In this case the agencies propose the configuration of a 

reference tractor for conducting trailer testing. Refer to Section IV of this preamble and to 40 

CFR 1037.501 of the proposed regulations for details on the proposed reference tractor 

configuration for trailer test procedures. 

(f) Tires and Tire Inflation Systems for Truck and Trailer Certification

For GEM in Phase 1 vehicle manufacturers input the tire rolling resistance of steer and 

drive tires directly into GEM. The agencies prescribed an internationally recognized tire rolling 

resistance test procedure, ISO 28580, for determining the tire rolling resistance value that is input 

into GEM, as described in 40 CFR 1037.520(c). For Phase 2 we are proposing to continue this 

same approach and the use of ISO 28580, and we propose to expand these requirements to trailer 

tires as well. We request comment on whether specific modifications to this test procedure 

would improve its accuracy, repeatability or its test lab to test lab variability.

In addition to tire rolling resistance, we are proposing that for Phase 2 vehicle 

manufacturers enter into GEM the tire manufacturer’s specified tire loaded radius for the 

vehicle’s drive tires. This value is commonly reported by tire manufacturers already so that 

vehicle speedometers can be adjusted appropriately. This input value is needed so that GEM can 

accurately convert simulated vehicle speed into axle speed, transmission speed, and ultimately 

engine speed. We request comment on whether the proposed test procedure should be modified 

to measure the tire’s revolutions per distance directly, as opposed to using the loaded radius to 

calculate the drive axle rotational speed from vehicle speed.

 

95 The agencies project that more than enough aerodynamic component vendors would take advantage of proposed 

optional pre-approval process to make trailer manufacturer testing optional.
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For tractors and trailers, we propose to allow manufacturers to specify whether or not an 

automatic tire inflation system is installed. If one is installed, GEM, or in the case of trailers, the 

equations based on GEM, would assign a 1 percent decrease in the overall fuel consumption and 

CO2 emissions simulation results for tractors, and a 1.5 percent decrease for trailers. This would 

be done through post-simulation adjustments discussed in Chapter 4 of the draft RIA. In 

contrast, we are not proposing to assign any decrease in fuel consumption and CO2 emissions for 

tire pressure monitoring systems. We do recognize that some drivers would respond to a 

warning indication from a tire pressure monitoring system, but we are unsure how to assign a 

fixed decrease in fuel consumption and CO2 emissions for tire pressure monitoring systems. We 

would estimate that the value would be less than any value we would assign for an automatic tire 

inflation system. We request comment on whether or not we should assign a fixed decrease in 

fuel consumption and CO2 emissions for tire pressure monitoring systems, and if so, we request 

comment on what would be an appropriate assigned fixed value.

(g) Weight Reduction for Tractor, Vocational Chassis and Trailer Certification

We propose for Phase 2 that GEM continues the weight reduction recognition approach 

in Phase 1, where the agencies prescribe fixed weight reductions, or “deltas”, for using certain 

lightweight materials for certain vehicle components. In Phase 1 the agencies published a list of 

weight reductions for using high-strength steel and aluminum materials on a part by part basis. 

For Phase 2 we propose to use these same values for high-strength steel and aluminum parts for 

tractors and for trailers and we have scaled these values for use in certifying the different weight 

classes of vocational chassis. In addition we are proposing a similar part by part weight 

reduction list for tractor parts made from thermoplastic material. We are also proposing to 

assign a fixed weight increase to natural gas fueled vehicles to reflect the weight increase of 

natural gas fuel tanks versus gasoline or diesel tanks. This increase would be allocated partly to 

the chassis and from the payload using the same allocation as weight reductions for the given 

vehicle type. For tractors we are proposing to continue the same mathematical approach in GEM 

to assign 1/3 of a total weight decrease to a payload increase and 2/3 of the total weight decrease 

to a vehicle mass decrease. For Phase 1 these ratios were based on the average frequency that a 

tractor operates at its gross combined weight rating. Therefore, we propose to use these ratios 

for trailers in Phase 2. However, as with the other fuel consumption and GHG reducing 

technologies manufacturers use for compliance, reductions associated with weight reduction 

would be calculated using the trailer compliance equation rather than GEM. For vocational 

chassis, for which Phase 1 did not address weight reduction, we propose a 50/50 ratio. In other 

words, for vocational chassis in GEM we propose to assign 1/2 of a total weight decrease to a 

payload increase and 1/2 of the total weight decrease to a vehicle mass decrease. We request 

comment on all aspects of applying weight reductions in GEM, including proposed weight 

increases for alternate fuel vehicles and whether a 50/50 ratio is appropriate for vocational 

chassis.

(h) GEM Duty Cycles for Tractor, Vocational Chassis and Trailer Certification

In Phase 1, there are three GEM vehicle duty cycles that represented stop-and-go city

driving (ARB Transient), urban highway driving (55 mph), and rural interstate highway driving 

(65 mph). In Phase 1 these cycles were time-based. That is, they were specified as a function of 

simulated time and the duty cycles ended once the specified time elapsed in simulation. The 
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agencies propose to use these three drive cycles in Phase 2, but with some revisions. First the 

agencies propose that GEM would simulate these cycles on a distance-based specification, rather 

than on a time-based specification. A distance-based specification ensures that even if a vehicle 

in simulation does not always achieve the target vehicle speed, the vehicle will have to continue 

in simulation for a longer period of time to complete the duty cycle. This ensures that vehicles 

are evaluated over the complete distance of the duty cycle and not just the portion of the duty

cycle that a vehicle completes in a given time period. A distance-based duty cycle specification 

also facilitates a straightforward specification of road grade as a function of distance along the 

duty cycle. For Phase 2 the agencies are proposing to enhance the 55 mph and 65 mph duty

cycles by adding representative road grade to exercise the simulated vehicle’s engine, 

transmission, axle, and tires in a more realistic way. A flat road grade profile over a constant 

speed test does not present many opportunities for a transmission to shift gears, and may have 

the unintended consequence of enabling underpowered vehicles or excessively downsped 

drivetrains to generate credits. The road grade profile proposed is the same for both the 55 mph 

and 65 mph duty cycles, and the profile was based on real over-the-road testing the agencies 

directed under an agency-funded contract with Southwest Research Institute.96 See Section III.E 

for more details on development of the proposed road grade profile. The agencies are continuing 

to evaluate alternate road grade profiles including actual sections of restricted access highway

with road grades that are statistically similar to the national road grade profile as well as purely

synthetic road grade profiles.97 We request comments on the proposed road grade profile, and 

would welcome additional statistical evaluations of this road grade profile and other road grade 

profiles for comparison. We believe that the enhancement of the 55 mph and 65 mph duty cycles 

with road grade is consistent with the NAS recommendation regarding road grade.98

We recognize that even with the proposed road grade profile, GEM may continue to 

under predict the number of transmission shifts of vehicles on restricted access highways if the 

model simulates constant speeds. We request comment on other ways in which the proposed 55 

mph and 65 mph duty cycles could be enhanced. For example, we request comment on whether 

a more aggressive road grade profile would induce a more realistic and representative number of 

transmission gear shifts. We also request comment on whether we should consider varying the 

vehicle target speed over the 55 mph and/or 65 mph duty cycles to simulate human driver 

 

96 SwRI road grade testing and GEM validation report, 2014.

97 See National Renewable Energy Laboratory report “EPA GHG Certification of Medium- and Heavy-Duty 

Vehicles: Development of Road Grade Profiles Representative of US Controlled Access Highways” dated May 

2015 and EPA memorandum “Development of an Alternative, Nationally Representative, Activity Weighted Road 

Grade Profile for Use in EPA GHG Certification of Medium- and Heavy-Duty Vehicles” dated May 13, 2015, both 

available in Docket EPA-HQ-OAR-2014-0827. This docket also includes file 

NREL_SyntheticAndLocalGradeProfiles.xlsx which contains numerical representations of all road grade profiles 

described in the NREL report.

98 NAS 2010 Report. Page 189. “A fundamental concern raised by the committee and those who testified during our 

public sessions was the tension between the need to set a uniform test cycle for regulatory purposes, and existing 

industry practices of seeking to minimize the fuel consumption of medium and heavy-duty vehicles designed for 

specific routes that may include grades, loads, work tasks or speeds inconsistent with the regulatory test cycle. This 

highlights the critical importance of achieving fidelity between certification values and real-world results to avoid 

decisions that hurt rather than help real-world fuel consumption.”
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behavior reacting to traffic congestion. This would increase the number of shifts during the 55 

mph and 65 mph duty cycles, though it may be possible for an equivalent effect to be achieved 

by assigning a greater weighting to the transient cycle in the GEM composite test score. 

(i) Workday Idle Operation for Vocational Vehicle Certification

In the Phase 1 program, reduction in idle emissions was recognized only for sleeper cab 

tractors, and only with respect to hotelling idle, where a driver needs power to operate heating, 

ventilation, air conditioning and other electrical equipment in order to use the sleeper cab to eat, 

rest, or conduct other business. As described in Section V, the agencies are now proposing to 

recognize in GEM technologies that reduce workday idle emissions, such as automatic stop-start 

systems and automatic transmissions that shift to neutral at idle. Many vocational vehicle 

applications operate on patterns implicating workday idle cycles, and the agencies are proposing 

test procedures in GEM to account specifically for these cycles and potential controls. GEM 

would recognize these idle controls in two ways. For technologies like neutral-idle that address

idle that occurs during the transient cycle (representing the type of operation that would occur 

when the vehicle is stopped at a stop light), GEM would interpolate lower fuel rates from the 

engine map. For technologies like start-stop and auto-shutdown that eliminate some of the idle 

that occurs when a vehicle is stopped or parked, GEM would assign a value of zero fuel rate for 

what we are proposing as an “idle cycle”. This idle cycle would be weighted along with the 65 

mph, 55 mph, and ARB Transient duty cycles according to the vocational chassis duty cycle 

weighting factors that we are proposing for Phase 2. These weighting factors are different for 

each of the three vocational chassis speed categories that we are proposing for Phase 2. While 

we are not proposing to apply this idle cycle for tractors, we do request comment on whether or 

not we should consider a applying this idle cycle to certain tractor types, like day cabs that could 

experience more significant amounts of time stopped or parked as part of an urban delivery

route. We also request comment on whether or not start-stop or auto-shutdown technologies are 

being developed for tractors; especially for Class 7 and 8 day cabs that could experience more 

frequent stops and more time parked for deliveries.

(2) Validation of the Proposed GEM 

After making the proposed changes to GEM, the agencies validated the model in 

comparison to over 130 vehicle variants, consistent with the recommendation made by the NAS 

in their Phase 2-First Report.99 As is described in Chapter 4 of the Draft RIA, good agreement

was observed between GEM simulations and test data over a wide range of vehicles. In general, 

the model simulations agreed with the test results within ±5 percent on an absolute basis. As 

pointed out in Chapter 4.3.2 of the RIA, relative accuracy is more relevant to this rulemaking. 

This is because all of the numeric standards proposed for tractors, trailers and vocational chassis 

are derived from running GEM first with Phase 1 “baseline” technology packages and then with 

various candidate Phase 2 technology packages. The differences between these GEM results are 

 

99 National Academy of Science. “Reducing the Fuel Consumption and GHG Emissions of Medium- and HeavyDuty Vehicles, Phase Two, First Report.” 2014. Recommendation1.2.
Page 113 of 850

examined to select stringencies. In other words, the agencies used the same version of GEM to 

establish the standards as was used to evaluate baseline performance for this rulemaking. 

Therefore, it is most important that GEM accurately reflects relative changes in emissions for 

each added technology. For vehicle certification purposes it is less important that GEM’s 

absolute value of the fuel consumption or CO2 emissions are accurate compared to laboratory

testing of the same vehicle. The ultimate purpose of this new version of GEM will be to evaluate 

changes or additions in technology, and compliance is demonstrated on a relative basis to the 

numerically standards that were also derived from GEM. Nevertheless, the agencies concluded 

that the absolute accuracy of GEM is generally within ±5 percent, as shown in Figure II-1. 

Chapter 4.3.2 of the draft RIA shows that relative accuracy is even better, ±2-3 percent. 
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Figure II-1 GEM Validation Data

2

4

6

8

10

12

14

16

2 4 6 8 10 12 14 16

G

E

M (M

P

G)

Experimental Tests (MPG)

Perfect Correlation ±5%
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In addition to this successful validation against experimental results, the agencies have 

also initiated a peer review of the proposed GEM source code. This peer review has been 

submitted to Docket # EPA-HQ-OAR-2014-0827. 

(3) Supplements to GEM Simulation

As in Phase 1, for most tractors and vocational vehicles, compliance with the Phase 2 

g/ton-mile vehicle standards could be evaluated by directly comparing the GEM result to the 

standard. However, in Phase 1, manufacturers incorporating innovative or advanced 

technologies could apply improvement factors to lower the GEM result slightly before 

comparing to the standard.100 For example, a manufacturer incorporating a launch-assist mild 

hybrid that was approved for a 5 percent benefit would apply a 0.95 improvement factor to its 

GEM results for such vehicles. In this example, a GEM result of 300 g/ton-mile would be 

reduced to 285 g/ton- mile.

For Phase 2, the agencies are proposing to largely continue the existing Phase 1 

innovative technology approach. We are also proposing to create a parallel option specifically

related to innovative powertrain designs. These proposals are discussed below.

(a) Innovative/Off-Cycle Technology Procedures

In Phase 1 the agencies adopted an emissions credit generating opportunity that applied 

to new and innovative technologies that reduce fuel consumption and CO2 emissions, that were 

not in common use with heavy-duty vehicles before model year 2010 and are not reflected over 

the test procedures or GEM (i.e., the benefits are “off-cycle”). See 76 FR at 57253. As was the 

case in the development of Phase 1, the agencies are proposing to continue this approach for 

technologies and concepts with CO2 emissions and fuel consumption reduction potential that 

might not be adequately captured over the proposed Phase 2 duty cycles or are not proposed 

inputs to GEM. Note, however, that the agencies are proposing to refer to these technologies as 

off-cycle rather than innovative. See Section I for more discussion of innovative and off-cycle 

technologies. 

We recognize that the Phase 1 testing burden associated with the innovative technology

credit provisions discouraged some manufacturers from applying. To streamline recognition of 

many technologies, default values have been integrated directly into GEM. For example, 

automatic tire inflation systems and 6x2 axles both have fixed default values, recognized through 

a post-simulation adjustment approach discussed in Chapter 4 of the draft RIA. This is similar to 

the technology “pick list” from our light-duty programs. See 77 FR at 62833-35 (Oct. 15, 2012). 

If manufacturers wish to receive additional credit beyond these fixed values, then the 

innovative/off-cycle technology credit provisions would provide the regulatory path toward that 

additional recognition. 

 

100 40 CFR 1036.610, 1036.615, 1037.610, and 1037.615 
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Beyond the additional technologies that the agencies have added to GEM, the agencies 

also believe there are several emerging technologies that are being developed today, but would 

not be accounted for in GEM as we are proposing it because we do not have enough information 

about these technologies to assign fixed values to them in GEM. Any credits for these 

technologies would need to be based on the off-cycle technology credit generation provisions. 

These require the assessment of real-world fuel consumption and GHG reductions that can be 

measured with verifiable test methods using representative operating conditions typical of the 

engine or vehicle application.

As in Phase 1, the agencies are proposing to continue to provide two paths for approval 

of the test procedure to measure the CO2 emissions and fuel consumption reductions of an offcycle technology used in the HD tractor. See 40 CFR 1037.610 and 49 CFR 535.7. The first 

path would not require a public approval process of the test method. A manufacturer can use 

“pre-approved” test methods for HD vehicles including the A-to-B chassis testing, powerpack 

testing or on-road testing. A manufacturer may also use any developed test procedure which has 

known quantifiable benefits. A test plan detailing the testing methodology is required to be 

approved prior to collecting any test data. The agencies are also proposing to continue the 

second path which includes a public approval process of any testing method which could have 

questionable benefits (i.e., an unknown usage rate for a technology). Furthermore, the agencies 

are proposing to modify its provisions to better clarify the documentation required to be 

submitted for approval aligning them with provisions in 40 CFR 86-1869-12 and NHTSA is 

separately proposing to prohibit credits from technologies addressed by any of its crash 

avoidance safety rulemakings (i.e., congestion management systems). We welcome 

recommendations on how to improve or streamline the off-cycle technology approval process.

Sections III and V describe tractor and vocational vehicle technologies, respectively, that 

the agencies anticipate may qualify for these off-cycle credit provisions. 

(b) Powertrain Testing

The agencies are proposing a powertrain test option to allow for a robust way to quantify

the benefits of CO2 reducing technologies that are a part of the powertrain (conventional or 

hybrid) that are not captured in the GEM simulation. Powertrain testing and certification was 

included as one of the NAS recommendations in the Phase 2 –First Report.101 Some of these 

improvements are transient fuel control, engine and transmission control integration and hybrid 

systems. To limit the amount of testing, the powertrain would be divided into families and 

powertrains would be tested in a limited number of simulated vehicles that cover the range of 

vehicles in which the powertrain would be installed. The powertrain test results would then be 

used to override the engine and transmission simulation portion of GEM.

 

101 National Academy of Science. “Reducing the Fuel Consumption and GHG Emissions of Medium- and HeavyDuty Vehicles, Phase Two, First Report.” 2014. Recommendation 1.6. However, the agencies are not proposing to 

allow for the use of manufacturer derived and verified models of the powertrain within GEM.
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The largest proposed change from the Phase 1 powertrain procedure is that only the 

advanced powertrain would need to be tested (as opposed to the Phase 1 requirement where both 

the advanced powertrain and the conventional powertrain had to be tested). This change is 

possible because the proposed GEM simulation uses the engine fuel map and torque curve from 

the actual engine in the vehicle to be certified. For the powertrain results to be used broadly 

across all the vehicles that the powertrain would go into, a matrix of 8 to 9 tests would be needed 

per vehicle cycle. These tests would cover the range of coefficient of drag, coefficient of rolling 

resistance, vehicle mass and axle ratio of the vehicles that the powertrain will be installed in. 

The main output of this matrix of tests would be fuel mass as a function of positive work and 

average transmission output speed over average vehicle speed. This matrix of test results would 

then be used to calculate the vehicle’s CO2 emissions by taking the work per ton-mile from the 

GEM simulation and multiplying it by the interpolated work specific fuel mass from the 

powertrain test and mass of CO2 to mass of fuel ratio. 

Along with proposing changes to how the powertrain results are used, the agencies are 

also proposing changes to the procedures that describe how to carry out a powertrain test. The 

changes are to give additional guidance on controlling the temperature of the powertrains intakeair, oil, coolant, block, head, transmission, battery, and power electronics so that they are within 

their expected ranges for normal operation. The equations that describe the vehicle model are 

proposed to be changed to allow for input of the axle’s efficiency, driveline rotational inertia, as 

well as the mechanical and electrical accessory loads. 

The determine the positive work and average transmission output speed over average 

vehicle speed in GEM for the vehicle that will be certified, the agencies have defined a generic 

powertrain for each vehicle category. The agencies are requesting comment on if the generic 

powertrains should be modified according to specific aspects of the actual powertrain. For 

example using the engine’s rated power to scale the generic engine’s torque curve. Similarly, the 

transmission gear ratios could be scaled by the axle ratio of the drive axle, to make sure the 

generic engine is operated in GEM at the correct engine speed.

(4) Production Vehicle Testing for Comparison to GEM

The agencies are is proposing to require tractor and vocational vehicle manufacturers to 

annually chassis test 5 production vehicles over the GEM cycles to verify that relative reductions 

simulated in GEM are being achieved in actual production. See 40 CFR 1037.665. We would 

not expect absolute correlation between GEM results and chassis testing. GEM makes many 

simplifying assumptions that do not compromise its usefulness for certification, but do cause it to 

produce emission rates different from what would be measured during a chassis dynamometer 

test. Given the limits of correlation possible between GEM and chassis testing, we would not 

expect such testing to accurately reflect whether a vehicle was compliant with the GEM 

standards. Therefore, we are proposing to not apply compliance liability to such testing. Rather, 

this testing would be for informational purposes only. However, we do expect there to be 

correlation in a relative sense. Vehicle to vehicle differences showing a 10 percent improvement 

in GEM should show a similar percent improvement with chassis dynamometer testing. 

Nevertheless, manufacturers would not be subject to recall or other compliance actions if chassis 

testing did not agree with the GEM results on a relative basis. Rather, the agencies would 

continue evaluate in-use compliance by verifying GEM inputs and testing in-use engines.
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EPA believes this chassis test program is necessary because of our experience 

implementing regulations for heavy-duty engines. In the past, manufacturers have designed 

engines that have much lower emissions on the duty cycles than occur during actual use. By

proposing this simple test program, we hope to be able to identify such issues earlier and to 

dissuade any attempts to design solely to the certification test. We also expect the results of this 

testing to help inform the need for any further changes to GEM.

As already noted in Section II. B. (1) , it can be expensive to build chassis test cells for 

certification. However, EPA is proposing to structure this pilot-scale program to minimize the 

costs. First, we are proposing that this chassis testing would not need to comply with the same 

requirements as would apply for official certification testing. This would allow testing to be 

performed in developmental test cells with simple portable analyzers. Second, since the 

proposed program would require only 5 tests per year, manufacturers without their own chassis 

testing facility would be able to contract with a third party to perform the testing. Finally, EPA 

proposes to apply this testing to only those manufacturers with annual production in excess of 

20,000 vehicles.

We request comment on this proposed testing requirement. Commenters are encouraged 

to suggest alternate approaches that could achieve the assurance that the projected emissions 

reductions would occur in actual use.

(5) Use of GEM in Establishing Proposed Numerical Standards

Just like in Phase 1, the agencies are proposing specific numerical standards against 

which tractors and vocational vehicles would be evaluated using GEM (We propose that trailers 

use a simplified equation-based approach that was derived from GEM). Although the proposed 

standards are performance-based standards, which do not specifically require the use of any 

particular technologies, the agencies established the proposed standards by evaluating specific 

vehicle technology packages using a prepublication version of the Phase 2 GEM. This 

prepublication version was an intermediate version of the GEM source code, rather than the 

executable file version of GEM, which is being docketed for this proposal and is available on 

EPA’s GEM Webpage. Both the GEM source code and the GEM executable file are generally 

functionally equivalent.

The agencies determined the proposed numerical standards essentially by evaluating 

certain specific technology packages representing the packages we are projecting to be feasible 

in the Phase 2 time frame. For each technology package, GEM was used determine a cycleweighted g/ton-mile emission rate and a gal/1000 ton-mile fuel consumption rate. These GEM 

results were then essentially averaged together, weighted by the adoption rates the agencies are 

projecting for each technology package and for each model year of standards. Consider as an 

oversimplified example of two technology packages for Class 8 low-roof sleepers cabs: one 

package that resulted in 60 g/ton-mile and a second that resulted in 80 g/ton-mile. If we project 

that the first package could be applied to 50 percent of the Class 8 low-roof sleeper cab fleet in 

MY 2027, and that the rest of the fleet could do no better than the second technology package, 

then we would set the fleet average standard at 70 g/ton-mile (0.5 • 60 + 0.5 • 80 = 70). 
Page 119 of 850

Formal external peer review and expert external user review was then conducted on the 

version of the GEM source code that was used to calculate the numerical values of the proposed 

standards. It was discovered via these external review processes that the GEM source code 

contained some minor software “bugs”. These bugs were then corrected by EPA and the Phase 

2 proposed GEM executable file was derived from this corrected version of the GEM source 

code. Moreover, we expect to also receive technical comments during the comment period that 

could potentially identify additional GEM software bugs, which would lead EPA to make 

additional changes to GEM before the Final Rule.

Thus, even without the agencies making any changes in our projections of technology 

effectiveness or market adoption rates, it is likely that further revisions to GEM could result in us 

finalizing different numerical values for the standards. It is important to note that the agencies 

would not necessarily consider such GEM-based numerical changes by themselves to be changes 

in the stringency of the standards. Rather, we believe that stringency is more appropriately 

evaluated in technological terms; namely, by evaluating technology effectiveness and the market 

adoption rates of technologies.

D. Proposed Engine Test Procedures and Engine Standards

For the most part, the proposed Phase 2 engine standards are a continuation of the Phase 

1 program, but with more stringent standards for compression-ignition engines. Nevertheless, 

the agencies are proposing important changes related to the test procedures and compliance 

provisions. These changes are described below.

As already discussed in Section II. B. the agencies are proposing a regulatory structure in 

which engine technologies are evaluated using engine-specific test procedures as well using 

GEM, which is vehicle-based. We are proposing separate standards for each procedure. The 

proposed engine standards described in Section II. D. (2) and the proposed vehicle standards 

described in Sections III and V are based on the same engine technology, which is described in 

Section II. D. (2) . We request comment on whether the engine and vehicle standards should be 

based on the same projected technology. As described below, while the agencies projected the 

same engine technology for engine standards and for vehicle standards, we separately projected 

the technology that would be appropriate for:

 Gasoline vocational engines and vehicles

 Diesel vocational engines and vehicles

 Tractor engines and vehicles 

Before addressing the engine standards and engine technology in Section II. D. (2) , the 

agencies describe the test procedures that would be used to evaluate these technologies in 

Section II. D. (1) below. We believe that without first understanding the test procedures, the 

numerical engine standards would not have the proper context. 

(1) Engine Test Procedures

The Phase 1 engine standards relied on the engine test procedures specified in 40 CFR 

part 1065. These procedures were previously used by EPA to regulate criteria pollutants such as 
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NOX and PM, and few changes were needed to employ them for purposes of the Phase 1 

standards. The agencies are proposing significant changes to two areas for Phase 2: (1) cycle 

weighting; and (2) GEM inputs. (Note that EPA is also proposing some minor changes to the 

basic part 1065 test procedures, as described in Section XIII).

The diesel (i.e., compression-ignition) engine test procedure relies on two separate engine 

test cycles. The first is the Heavy-duty Federal Test Procedure (Heavy-duty FTP) that includes 

transient operation typified by frequent accelerations and decelerations, similar to urban or 

suburban driving. The second is the Supplemental Engine Test (SET) which includes 13 steadystate test points. The SET was adopted by EPA to address highway cruise operation and other 

nominally steady-state operation. However, it is important to note that it was intended as a 

supplemental test cycle and not necessarily to replicate precisely any specific in-use operation. 

The gasoline (i.e., spark-ignition) engine test procedure relies on a single engine test 

cycle: a gasoline version of Heavy-duty FTP. The agencies are not proposing changes to the 

gasoline engine test procedures.

It is worth noting that EPA sees great value in using the same test procedures for 

measuring GHG emissions as is used for measuring criteria pollutants. From the manufacturers’ 

perspective, using the same procedures minimizes their test burden. However, EPA sees 

additional benefits. First, as already noted in Section(b) , requiring engine manufacturers to 

comply with both NOX and CO2 standards using the same test procedures discourages alternate 

calibrations that would trade NOX emissions against fuel consumption depending how the engine 

or vehicle is tested. Second, this approach leverages the work that went into developing the 

criteria pollutant cycles. Taken together, these factors support our decision to continue to rely on 

the Part 1065 test procedures with only minor adjustments, such as those described in Section II. 

D. (1) (a). Nevertheless, EPA would consider more substantial changes if they were necessary to 

incentivize meaningful technology changes, similar to the changes being made to GEM for Phase 

2 to address additional technologies. 

(a) SET Cycle Weighting 

The SET cycle was adopted by EPA in 2000 and modified in 2005 from a discrete-mode 

test to a ramped-modal cycle to broadly cover the most significant part of the speed and torque 

map for heavy-duty engines, defined by three non-idle speeds and three relative torques. The 

low speed is often called the “A speed”, the intermediate speed is often called the “B speed”, and 

the high speed is often called the “C speed.” As is shown in Table II-1, the SET weights these 

three speeds at 23 percent, 39 percent, and 23 percent.
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Table II-1 SET Modes Weighting Factor in Phase 1

Speed, % Load Weighting factor in Phase 1 (%)

Idle 15

A, 100 8

B, 50 10

B, 75 10

A, 50 5

A, 75 5

A, 25 5

B, 100 9

B, 25 10

C, 100 8

C, 25 5

C, 75 5

C, 50 5

Total 100

Total A Speed 23

Total B Speed 39

Total C Speed 23

The C speed is typically in the range of 1800 rpm for current HHD engine designs. 

However, it is becoming less common for engines to operate often in such a high speed in real 

world driving condition, and especially not during cruise vehicle speed between 55 and 65 mph. 

The agencies receive confidential business information from a few vehicle manufacturers that 

support this observation. Thus, although the current SET represents highway operation better 

than the FTP cycle, it is not an ideal cycle to represent future highway operation. Furthermore, 

given the recent trend configure drivetrains to operate engines at speeds down to a range of 

1150-1200 rpm at vehicle speed of 65mph. This trend would make the typical highway engine 

speeds even further away from C speed.

To address this issue, the agencies are proposing new weighting factors for the Phase 2 

GHG and fuel consumption standards. The proposed new SET mode weightings move most of 

C weighting to “A” speed, as shown in Table II-2. It would also slightly reduce the weighting 

factor on the idle speed. 

The agencies request comment on the proposed reweighting.
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Table II-2 Proposed SET Modes Weighting Factor in Phase 2

Speed/% Load Proposed Weighting factor in 

Phase 2 (%)

Idle 12

A, 100 9

B, 50 10

B, 75 10

A, 50 12

A, 75 12

A, 25 12

B, 100 9

B, 25 9

C, 100 2

C, 25 1

C, 75 1

C, 50 1

Total 100

Total A Speed 45

Total B Speed 38

Total C Speed 5

(b) Measuring GEM Engine Inputs

Although GEM does not apply directly to engine certification, implementing the Phase 2 

GEM would impact engine manufacturers. To recognize the contribution of the engine in GEM 

the engine fuel map, full load torque curve and motoring torque curve have to be input into 

GEM. To insure the robustness of each of those inputs, a standard procedure has to be followed. 

Both the full load and motoring torque curve procedures are already defined in 40CFR part 1065 

for engine testing. However, the fuel mapping procedure being proposed would be new. The 

agencies have compared the proposed procedure against other accepted engine mapping 

procedures with a number of engines at various labs including EPA’s NVFEL, Southwest 

Research Institute sponsored by the agencies, and Environment Canada’s laboratory.

102

 The 

proposed procedure was selected because it proved to be accurate and repeatable, while limiting 

the test burden to create the fuel map. This proposed provision is consistent with NAS’s 

recommendation (3.8).

One important consideration is the need to correct measured fuel consumption rates for 

the carbon and energy content of the test fuel. For engine tests, we propose to continue the Phase 

 

102 U.S. Environmental Protection Agency. Memo to Docket EPA-HQ-OAR-2014-0827.
Page 123 of 850

1 approach, which is specified in 40 CFR 1036.530. We propose a similar approach to GEM 

fuel maps in Phase 2.

The agencies are proposing that engine manufacturers must certify fuel maps as part of 

their certification to the engine standards, and that they be required to provide those maps to 

vehicle manufacturers beginning with MY 2020.103 The one exception to this requirement would 

be for cases in which the engine manufacturer certifies based on powertrain testing, as described 

in Section (c). In such cases, engine manufacturers would not be required to also certify the 

otherwise applicable fuel maps. We are not proposing that vehicle manufacturers be allowed to 

develop their own fuel maps for engines they do not manufacture. 

The current engine test procedures also require the development of regeneration emission 

rate and frequency factors to account for the emission changes for criteria pollutants during a 

regeneration event. In Phase 1, the agencies adopted provisions to exclude CO2 emissions and 

fuel consumption due to regeneration. However, for Phase 2, we propose to include CO2

emissions and fuel consumption due to regeneration over the FTP and RMC cycles as 

determined using the infrequently regenerating aftertreatment devices (IRAF) provisions in 40 

CFR 1065.680. We do not believe this would significantly impact the stringency of the proposed 

standards because manufacturers have already made great progress in reducing the impact of 

regeneration emissions since 2007. Nevertheless, we believe it would be prudent to begin 

accounting for regeneration emissions to discourage manufacturers from adopting compliance 

strategies that would reverse this trend. We request comment on this requirement.

We are not proposing, however, to include fuel consumption due to regeneration in the 

creation of the fuel map used in GEM for vehicle compliance. We believe that the proposed 

requirements for the duty-cycle standards, along with market forces that already exist, would 

create sufficient incentives to reduce fuel consumption during regeneration over the entire fuel 

map.

(c) Engine Test Procedures for Replicating Powertrain Tests 

As described in Section II.B.(2)(b), the agencies are proposing a powertrain test option to 

quantify the benefits of CO2 reducing powertrain technologies. These powertrain test results 

would then be used to override the engine and transmission simulation portion of GEM. The 

agencies are proposing to require that any manufacturer choosing to use this option also measure 

engine speed and engine torque during the powertrain test so that the engine’s performance 

during the powertrain test could be replicated in a non-powertrain engine test cell. Subsequent 

engine testing would be conducted using the normal part 1065 engine test procedures, and g/hphr CO2 results would be compared to the levels the manufacturer reported during certification. 

Such testing would apply for both confirmatory and selective enforcement audit testing. 

 

103 Current normal vehicle manufacturing processes generally result in many vehicles being produced with prior 

model year engines. For example, we expect that some MY 2021 vehicles will be produced with MY 2020 engines. 

Thus, we are proposing to require engine manufacturers to begin providing fuel maps in 2020 so that vehicle 

manufacturers could run GEM to certify MY 2021 vehicles with MY 2020 engines.
Page 124 of 850

Under the proposed regulations, engine manufacturers certifying powertrain performance 

(instead of or in addition to the multi-point fuel maps) would be held responsible for powertrain 

test results. On the other hand, where the engine manufacturer does not certify powertrain 

performance and instead certifies only the multi-point fuel maps, it would held responsible for 

fuel map performance rather than the powertrain test results. Engine manufacturers certifying 

both would be responsible for both.

(d) CO2 from Urea SCR Systems 

For diesel engines utilizing urea SCR emission control systems for NOX reduction, the 

agencies are proposing to allow correction of the final engine fuel map and powertrain duty cycle 

CO2 emission results to account for the contribution of CO2 from the urea injected into the 

exhaust. This urea could contribute up to 1 percent of the total CO2 emissions from the engine. 

Since current urea production methods use gaseous CO2 captured from the atmosphere (along 

with NH3), CO2 from urea consumption does not represent a net carbon emission. This 

adjustment is necessary so that fuel maps developed from CO2 measurements would be 

consistent with fuel maps from direct measurements of fuel flow rates. Thus, we are only 

proposing to allow this correction for emission tests where CO2 emissions are determined from 

direct measurement of CO2 and not from fuel flow measurement, which would not be impacted 

by CO2 from urea.

We note that this correction would be voluntary for manufacturers, and expect that some 

manufacturers may determine that the correction is too small to be of concern. The agencies will 

use this correction with any engines for which the engine manufacturer applied the correction for 

its fuel maps during certification. 

We are not proposing this correction for engine test results with respect to the engine CO2

standards. Both the Phase 1 standards and the proposed standards for CO2 from diesel engines 

are based on test results that included CO2 from urea. In other words, these standards are 

consistent with using a test procedure that does not correct for CO2 from urea. We request 

comment on whether it would be appropriate to allow this correction for the Phase 2 engine CO2

standards, but also adjust the standards to reflect the correction. At this time, we believe that 

reducing the numerical value of the CO2 standards by 1 g/hp-hr would make the standards 

consistent with measurement that are corrected for CO2 from urea. However, we also request 

comment on the appropriateness of applying a 2 g/hp-hr adjustment should we determine it 

would better reflect the urea contribution for current engines.

(e) Potential Alternative Certification Approach

In Section II.B.(2)(b), we explained that although GEM does not apply directly to engine 

certification, implementing the Phase 2 GEM would impact engine manufacturers by requiring 

that they measure engine fuel maps. In Section I. A. (1) , the agencies noted that some 

stakeholders may have concerns about the proposed regulatory structure that would require 

engine manufacturers to provide detailed fuel consumption maps for GEM. Given such 

concerns, the agencies are requesting comment on an approach that could mitigate the concerns 
Page 125 of 850

by allowing both vehicle and engine to use the same driving cycles for certification. The 

detailed description of this alternative certification approach can be seen in the draft RIA. We 

are requesting comment on allowing this approach as an option, or as a replacement to the 

proposed approach. Commenters supporting this approach should address possible impacts on 

the stringency of the proposed standards.

This approach utilizes GEM with a default engine fuel map pre-defined by the agency to 

run a number of pre-defined vehicle configurations over three certification cycles. Engine torque 

and speed profile would be obtained from the simulations, and would be used to specify engine 

dynamometer commands for engine testing. The results of this testing would be a CO2 map as 

function of the integrated work and the ratio of averaged engine speed (N) to averaged vehicle 

speed (V) defined as (N/V) over each certification cycle. In vehicle certification, vehicle 

manufacturers would run GEM with the to-be-certified vehicle configuration and the agency

default engine fuel map separately for each GEM cycle. Applying the total work and N/V 

resulted from the GEM simulations to the CO2 map obtained from engine tests would determine 

CO2 consumption for vehicle certification. For engine certification, we are considering allowing 

the engine to be certified based on one of the points conducted during engine alternative CO2

map tests mentioned above rather than based on the FTP and SET cycle testing. 

(2) Proposed Engine Standards for CO2 and Fuel Consumption 

We are proposing to maintain the existing Phase 1 regulatory structure for engine 

standards, which had separate standards for spark-ignition engines (such as gasoline engines) and 

compression-ignition engines (such as diesel engines), but we are proposing changes to how 

these standards would apply to natural gas fueled engines. As discussed in Section II.B.(2)(b), 

the agencies see important advantages to maintaining separate engines standards, such as 

improved compliance assurance and better control during transient engine operation.

Phase 1 also applied different test cycles depending on whether the engine is used for 

tractors, vocational vehicles, or both, and we propose to continue this as well.104 We assume 

that CO2 at the end of Phase 1 is the baseline of Phase 2. Table II-3 shows the Phase 1 CO2

standards for diesel engines, which serve as the baseline for our analysis of the proposed Phase 2 

standards. 

Table II-3 Phase 2 Baseline CO2 Performance (g/bhp-hr)

 

104 Engine classification is set forth in 40 CFR 1036.801. Spark-ignition means relating to a gasoline-fueled engine 

or any other type of engine with a spark plug (or other sparking device) and with operating characteristics similar to 

the Otto combustion cycle. However, engines that meet the definition of spark-ignition per 1036.801, but are 

regulated as diesel engines under 40 CFR part 86 (for criteria pollutants) are treated as compression-ignition engines 

for GHG standards. Compression-ignition means relating to a type of reciprocating, internal-combustion engine that 

is not a spark-ignition engine, however, engines that meet the definition of compression-ignition per 1036.801, but 

are regulated as Otto-cycle engines under 40 CFR part 86 are treated as spark-ignition engines for GHG standards.
Page 126 of 850

LHDD - FTP MHDD - FTP HHDD - FTP MHDD-SET HHDD - SET

576 576 555 487 460

The gasoline engine baseline CO2 is 627 (g/bhp-hr). The agencies used the baseline 

engine to assess the potential of the technologies described in the following sections. As 

described below, the agencies are proposing new compression-ignition engine standards for 

Phase 2 that would require additional reductions in CO2 emissions and fuel consumption beyond 

the baseline. However, as also described below in Section II.B.(2)(b), we are not proposing 

more stringent CO2 or fuel consumption standards for new heavy-duty gasoline engines. Note, 

however, that we are projecting some small improvement in gasoline engine performance that 

would be recognized over the vehicle cycles.

For heavy-heavy-duty diesel engines to be installed in Class 7 and 8 combination tractors, 

the agencies are proposing the standards shown in Table II-4.

105

 The proposed MY 2027 

standards for engines installed in tractors would require engine manufacturers to achieve, on 

average, a 4.2 percent reduction in fuel consumption and CO2 emissions beyond the Phase 1 

standard. We propose to adopt interim engine standards in MY 2021 and MY 2024 that would 

require diesel engine manufacturers to achieve, on average, 1.5 percent and 3.7 percent 

reductions in fuel consumption and CO2 emissions, respectively. 

Table II-4 Proposed Phase 2 Heavy-duty Tractor Engine Standards for Engines106 over the SET Cycle

Model Year Standard Medium HeavyDuty DieselHeavy HeavyDuty Diesel

2021-2023 CO2 (g/bhp-hr) 479 453

Fuel Consumption 

(gallon/100 bhp-hr)

4.7053 4.4499

2024 -2026 CO2 (g/bhp-hr) 469 443

Fuel Consumption 

(gallon/100 bhp-hr)

4.6071 4.3517

2027 and 

Later

CO2 (g/bhp-hr) 466 441

Fuel Consumption 

(gallon/100 bhp-hr)

4.5776 4.3320

For compression-ignition engines fitted into vocational vehicles, the agencies are 

proposing MY 2027 standards that would require engine manufacturers to achieve, on average, a 

4.0 percent reduction in fuel consumption and CO2 emissions beyond the Phase 1 standard. We 

 

105 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.

106 Tractor engine standards apply to all engines, without regard to the engine-cycle classification.
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propose to adopt interim engine standards in MY 2021 and MY 2024 that would require diesel 

engine manufacturers to achieve, on average, 2.0 percent and 3.5 percent reductions in fuel 

consumption and CO2 emissions, respectively. 

Table II-5presents the CO2 and fuel consumption standards the agencies propose for 

compression-ignition engines to be installed in vocational vehicles. The first set of standards 

would take effect with MY 2021, and the second set would take effect with MY 2024.

Table II-5 Proposed Vocational Diesel Engine Standards over the Heavy-Duty FTP Cycle

Model 

Year

Standard Light 

HeavyDuty

Diesel

Medium 

HeavyDuty

Diesel

Heavy 

HeavyDuty Diesel

2021-2023 CO2 Standard (g/bhp-hr) 565 565 544

Fuel Consumption Standard 

(gallon/100 bhp-hr)

5.5501 5.5501 5.3438

2024 -

2026

CO2 Standard (g/bhp-hr) 556 556 536

Fuel Consumption (gallon/100 

bhp-hr)

5.4617 5.4617 5.2652

2027 and 

Later

CO2 Standard (g/bhp-hr) 553 553 533

Fuel Consumption (gallon/100 

bhp-hr)

5.4322 5.4322 5.2358

Although both EPA and NHTSA are proposing to begin the Phase 2 engine standards, 

EPA considered proposing Phase 2 standards that would begin before MY 2021 – that is with 

less lead time. NHTSA is required by statute to provide four models years of lead time, while 

EPA is required only to provide lead time “necessary to permit the development and application 

of the requisite technology” (CAA Section 202 (a)(2)). However, as noted in Section I, lead time 

cannot be separated for other relevant factors such as costs, reliability, and stringency. 

Proposing these standards before 2021 could increase the risk of reliability issues in the early 

years. Given the limited number of engine models that each manufacturer produces, managing 

that many new standards would be problematic (i.e., new Phase 1 standards in 2017, new Phase 2 

EPA standards in 2018, 2019, or 2020, new standards in 2021, 2024, and again in 2027). 

Considering these challenges, EPA determined that earlier model year standards would not be 

appropriate, especially given the value of harmonizing the NHTSA and EPA standards.

(a) Feasibility of the Diesel (Compression-Ignition) Engine Standards

In this section, the agencies discuss our assessment of the feasibility of the proposed 

engine standards and the extent to which they would conform to our respective statutory

authority and responsibilities. More details on the technologies discussed here can be found in 

the Draft RIA Chapter 2.3. The feasibility of these technologies is further discussed in draft RIA 

Chapter 2.7 for tractor and vocational vehicle engines. Note also, that the agencies are 

considering adopting engine standards with less lead time, and may do so in the Final Rules. 

These standards are discussed in Section (e).
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Based on the technology analysis described below, the agencies can project a technology

path exists to allow manufacturers to meet the proposed final Phase 2 standards by 2027, as well 

as meeting the intermediate 2021 and 2024 standards. The agencies also project that 

manufacturers would be able to meet these standards at a reasonable cost and without adverse 

impacts on in-use reliability. Note that the agencies are still evaluating whether these same 

standards could be met sooner, as was analyzed in Alternative 4.

In general, engine performance for CO2 emissions and fuel consumption can be improved 

by improving combustion and reducing energy losses. More specifically, the agencies have 

identified the following key areas where fuel efficiency can be improved:

 Combustion optimization

 Turbocharging system

 Engine friction and other parasitic losses

 Exhaust aftertreatment

 Engine breathing system

 Engine downsizing

 Waste heat recovery

 Transient control for vocational engines only

The agencies are proposing to phase-in the standards from 2021 through 2027 so that 

manufacturers could gradually introduce these technologies. For most of these improvements, 

the agencies project manufacturers could begin applying them to about 45-50 percent of their 

heavy-duty engines by 2021, 90-95 percent by 2024, and ultimately apply them to 100 percent of 

their heavy-duty engines by 2027. However, for some of these improvements (such as waste 

heat recovery and engine downsizing) we project lower application rates in the Phase 2 time 

frame. This phase-in structure is consistent with the normal manner in which manufacturers 

introduce new technology to manage limited R&D budgets and well as to allow them to work 

with fleets to fully evaluate in-use reliability before a technology is applied fleet-wide. The 

agencies believe the proposed phase-in schedule would allow manufacturers to complete these 

normal processes. As described in Section (e), the agencies are also requesting comment on 

whether manufacturers could complete these development steps more quickly so that they could 

meet these standards sooner.

Based on our technology assessment described below, the proposed engine standards 

appear to be consistent with the agencies’ respective statutory authorities. All of the 

technologies with high penetration rates above 50 percent have already been demonstrated to 

some extent in the field or in research laboratories, although some development work remains to 

be completed. We note that our feasibility analysis for these engine standards is not based on 

projecting 100 percent application for any technology until 2027. We believe that projecting less 

than 100 percent application is appropriate and gives us additional confidence that the interim 

standards would be feasible. 

Because this analysis considers reductions from engines meeting the Phase 1 standards, it 

assumes manufacturers would continue to include the same compliance margins as Phase 1. In 

other words, a manufacturer currently declaring FCLs 10 g/hp-hr above its measured emission 
Page 129 of 850

rates (in order to account for production and test-to-test variability) would continue to do the 

same in Phase 2. We request comment on this assumption.

The agencies have carefully considered the costs of applying these technologies, which 

are summarized in Section II.D.(2) (d). These costs appear to be reasonable on both a per engine 

basis, and when considering payback periods107. The engine technologies are discussed in more 

detail below. Readers are encouraged to see the draft RIA Chapter 2 for additional details (and 

underlying references) about our feasibility analysis. 

(i) Combustion Optimization

Although manufacturers are making significant improvements in combustion to meet the 

Phase 1 engine standards, the agencies project that even more improvement would be possible 

after 2018. For example, improvements to fuel injection systems would allow more flexible fuel 

injection capability with higher injection pressure, which can provide more opportunities to 

improve engine fuel efficiency. Further optimization of piston bowls and injector tips would 

also improve engine performance and fuel efficiency. We project that a reduction of up to 1.0 

percent is feasible in the 2024 model year through the use of these technologies, although it 

would likely apply to only 95 percent of engines until 2027.

Another important area of potential improvement is advanced engine control 

incorporating model based calibration to reduce losses of control during transient operation. 

Improvements in computing power and speed would make it possible to use much more 

sophisticated algorithms that are more predictive than today’s controls. Because such controls 

are only beneficial during transient operation, they would reduce emission over the FTP cycle, 

and during in-use operation, they would not reduce emissions over the SET cycle. Thus the 

agencies are projecting model based control reductions only for vocational engines. Although 

this control concept is not currently available, we project model based controls achieving a 2 

percent improvement in transient emissions could be in production for some engine models by 

2021. By 2027, we project over one-third of all vocational diesel engines would incorporate 

model-based controls.

(ii) Turbocharging System

Many advanced turbocharger technologies can be potentially added into production in the 

time frame between 2021 and 2027, and some of them are already in production, such as 

mechanical or electric turbo-compound, more efficient variable geometry turbine, and Detroit 

Diesel’s patented asymmetric turbocharger. A turbo compound system extracts energy from the 

exhaust to provide additional power. Mechanical turbo-compounding includes a power turbine 

located downstream of the turbine which in turn is connected to the crankshaft to supply

additional power. On-highway demonstrations of this technology began in the early 1980s. It 

was used first in heavy duty production by Detroit Diesel for their DD15 and DD16 engines and 

reportedly provided a 3 to 5 percent fuel consumption reduction. Results are duty cycle 

 

107 See Section IX.M for additional information about payback periods.
Page 130 of 850

dependent, and require significant time at high load to see a fuel efficiency improvement. Light 

load factor vehicles can expect little or no benefit. Volvo reports two to four percent fuel 

consumption improvement in line haul applications, which could be in production even by 2020

(iii) Engine Friction and Parasitic Losses

The friction associated with each moving part in an engine results in a small loss of 

engine power. For example, frictional losses occur at bearings, in the valvetrain, and at the 

piston-cylinder interface. Taken together such losses represent a large fraction of all energy lost 

in an engine. For Phase 1, the agencies projected a 1-2 percent reduction in fuel consumption 

due to friction reduction. However, new information leads us to project that an additional 1.4 

percent reduction would be possible for some engines by 2021 and all engines by 2027. These 

reductions would be possible due to improvements in bearing materials, lubricants, and new 

accessory designs such as variable-speed pumps.

(iv) Aftertreatment Optimization

All diesel engines manufacturers are already using diesel particulate filter (DPF) to 

reduce particulate matter (PM) and selective catalytic reduction (SCR) to reduce NOX emissions. 

The agencies see two areas in which improved aftertreatment systems can also result in lower 

fuel consumption. First, increased SCR efficiency could allow re-optimization of combustion for 

better fuel consumption because the SCR would be capable of reducing higher engine-out NOX

emissions. Second, improved designs could reduce backpressure on the engine to lower 

pumping losses. The agencies project the combined impact of such improvements could be 0.6 

percent or more. 

(v) Engine Breathing System

Various high efficiency air handling (for both intake air and exhaust) processes could be 

produced in the 2020 and 2024 time frame. 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 would likely include higher efficiency EGR systems and 

intercoolers that reduce frictional pressure loss while maximizing the ability to thermally control 

induction air and EGR. EGR systems that often rely upon an adverse pressure gradient (exhaust 

manifold pressures greater than intake manifold pressures) must be reconsidered and their 

adverse pressure gradients minimized. Other components that offer opportunities for improved 

flow efficiency include cylinder heads, ports and exhaust manifolds to further reduce pumping 

losses by about 1 percent. 

(vi) Engine Downsizing

Proper sizing of an engine is an important component of optimizing a vehicle for best 

fuel consumption. This Phase 2 rule would improve overall vehicle efficiency, which would 

result in a drop in the vehicle power demand for most operation. This drop moves the vehicle 

operating points down to a lower load zone, which can move the engine away from the sweet 

spot. Engine downsizing combined with engine downspeeding can allow the engine to move 
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back to higher loads and lower speed zone, thus achieving slightly better fuel economy in the 

real world. However, because of the way engines are tested, little of the benefit of engine 

downsizing would be detected during engine testing (if power density remains the same) because 

the engine test cycles are normalized based on the full torque curve. Thus the current engine test 

is not the best way to measure the true effectiveness of engine downsizing. Nevertheless, we 

project that some small benefit would be measured over the engine test cycles – perhaps up to a 

one-quarter percent improvement in fuel consumption. Note that a bigger benefit would be 

observed during GEM simulation, better reflecting real world improvements. This is factored 

into the vehicle standards. Thus, the agencies see no reason to fundamentally revise the engine 

test procedure at this time.

(vii) Waste Heat Recovery

More than 40 percent of all energy loss in an engine is lost as heat to the exhaust and 

engine coolant. For many years, manufacturers have been using turbochargers to convert some 

of the waste heat in the exhaust into usable mechanical power than is used to compress the intake 

air. Manufacturers have also been working to use a Rankine cycle-based system to extract 

additional heat energy from the engine. Such systems are often called waste heat recovery

(WHR) systems. The possible sources of energy include the exhaust, recirculated exhaust gases, 

compressed charge air, and engine coolant. The basic approach with WHR is to use waste heat 

from one or more of these sources to evaporate a working fluid, which is passed through a 

turbine or equivalent expander to create mechanical or electrical power, then re-condensed.

Prior to the Phase 1 Final Rule, the NAS estimated the potential for WHR to reduce fuel 

consumption by up to 10 percent.

108

 However, the agencies do not believe such levels would be 

achievable within the Phase 2 time frame. There currently are no commercially available WHR 

systems for diesel engines, although research prototype systems are being tested by some 

manufacturers. The agencies believe it is likely a commercially-viable WHR capable of 

reducing fuel consumption by over three percent would be available in the 2021 to 2024 time 

frame. Cost and complexity may remain high enough to limit the use of such systems in this 

time frame. Moreover, packaging constraints and transient response challenges would limit the 

application of WHR systems to line-haul tractors. Refer to RIA Chapter 2 for a detailed 

description of these systems and their applicability. The agencies project that WHR recovery

could be used on 1 percent of all tractor engines by 2021, on 5 percent by 2024, and 15 percent 

by 2027. 

The net cost and effectiveness of future WHR systems would depend on the sources of 

waste heat. Systems that extract heat from EGR gases may provide the side benefit of reducing 

the size of EGR coolers or eliminating them altogether. To the extent that WHR systems use 

exhaust heat, they would increase the overall cooling system heat rejection requirement and 

likely require larger radiators. This could have negative impacts on cooling fan power needs and 

vehicle aerodynamics. Limited engine compartment space under hood could leave insufficient 

 

108 See 2010 NAS Report, page 57.
Page 132 of 850

room for additional radiator size increasing. On the other hand, WHR systems that extract heat 

from the engine coolant, could actually improve overall cooling.

(viii) Technology Packages for Diesel Engines Installed in Tractors

Typical technology packaged for diesel engines installed in tractors basically includes 

most technologies mentioned above, which includes combustion optimization, turbocharging 

system, engine friction and other parasitic losses, exhaust aftertreatment, engine breathing 

system, and engine downsizing. Depending on the technology maturity of WHR and market 

demands, a small number of tractors could install waste heat recovery device with Rankine cycle 

technology. During the stringency development, the agencies received strong support from 

various stakeholders, where they graciously provided many confidential business information 

(CBI) including both technology reduction potentials and estimated market penetrations. 

Combining those CBI data with the agencies’ engineering judgment, Table II-4 lists those 

potential technologies together with the agencies’ estimated market penetration for tractor 

engine. Those reduction values shown as ”SET reduction” are relative to Phase 1 engine, which 

is shown in Table II-6. It should be pointed out that the stringency in Table II-6 are developed 

based on the proposed SET reweighting factors l shown in Table II-2. The agencies welcome 

comment on the market penetration rates listed below.

Table II-6 Projected Tractor Engine Technologies and Reduction

SET Mode SET 

weighted 

reduction (%) 

2020-2027

Market 

penetration 

(2021)

Market 

penetration 

(2024)

Market 

penetration 

(2027)

Turbo compound with 

clutch

1.8% 5% 10% 10%

WHR (Rankine cycle) 3.6% 1% 5% 15%

Parasitic/Friction (Cyl

Kits, pumps, FIE), 

lubrication

1.4% 45% 95% 100%

Aftertreatment (lower 

dP)

0.6% 45% 95% 100%

EGR/Intake & exhaust 

manifolds/Turbo 

/VVT/Ports

1.1% 45% 95% 100%

Combustion/FI/Control 1.1% 45% 95% 100%

Downsizing 0.3% 10% 20% 30%

Weighted reduction (%) 1.5% 3.7% 4.2%

(ix) Technology Packages for Diesel Engines Installed in Vocational Vehicles

For compression-ignition engines fitted into vocational vehicles, the agencies are 

proposing MY 2021 standards that would require engine manufacturers to achieve, on average, a 

2.0 percent reduction in fuel consumption and CO2 emissions beyond the baseline that is the 

Phase 1 standard. Beginning in MY 2024, the agencies are proposing engine standards that 
Page 133 of 850

would require diesel engine manufacturers to achieve, on average, a 3.5 percent reduction in fuel 

consumption and CO2 emissions beyond the Phase 1 baseline standards for all diesel engines

including LHD, MHD, and HHD. The agencies are proposing these standards based on the 

performance of reduced parasitics and friction, improved aftertreatment, combustion 

optimization, superchargers with VGT and bypass, model-based controls, improved EGR 

cooling/transport, and variable valve timing (only in LHD and MHD engines). The percent 

reduction for the MY2021, MY2024, and MY2027 standards is based on the combination of 

technology effectiveness and market adoption rate projected.

Most of the potential engine related technologies discussed previously can be applied 

here. However, neither the waste heat technologies with the Rankine cycle concept nor turbocompound would be applied into vocational sector due to the inefficient use of waste heat energy

with duty cycles and applications with more transient operation than highway operation. Given 

the projected cost and complexity of such systems, we believe that for the Phase 2 time frame 

manufacturers will focus their development work on tractor applications (which would have 

better payback for operators) rather than vocational applications. In addition, the benefits due to 

engine downsizing, which can be seen in tractor engines, may not be clearly seen in vocational 

sector, again because this control technology produces few benefits in transient operation. 

One of the most effective technologies for vocational engines is the optimization of 

transient control. It would be expected that more advanced transient control including different 

levels of model based control and neural network control package could provide substantial 

benefits in vocational engines due to the extensive transient operation of these vehicles. For this 

technology, the use of the FTP cycle would drive engine manufacturers to invest more in 

transient control to improve engine efficiency. Other effective technologies would be 

parasitic/friction reduction, as well as improvements to combustion, air handling systems, 

turbochargers, and aftertreatment systems. Table II-7 below lists those potential technologies 

together with the agencies’ projected market penetration for vocational engines. Again, similar 

to tractor engine, the technology reduction and market penetration are estimated by combining 

the CBI data together with the agencies’ engineering judgment. Those reduction values shown 

as “FTP reduction” are relative to a Phase 2 baseline engine, which is shown in Table II-3. The 

weighted reductions combine the emission reduction values weighted by the market penetration 

of each technology). 
Page 134 of 850

Table II-7 Projected Vocational Engine Technologies and Reduction

Technology GHG 

Emissions 

Reduction 

2020-2027

Market 

Penetration 

2021

Market 

Penetration 

2024

Market 

Penetration 

2027

Model based control 2.0% 25% 30% 40%

Parasitic /Friction 1.5% 60% 90% 100%

EGR/Air/VVT /Turbo 1.0% 50% 90% 100%

Improved AT 0.5% 50% 90% 100%

Combustion 

Optimization

1.0% 50% 90% 100%

Weighted reduction 

(%)-L/M/HHD

2.0% 3.5% 4.0%

(x) Summary of the Agencies’ Analysis of the Feasibility of the Proposed Diesel Engine 

Standards

The proposed HD Phase 2 standards are based on adoption rates for technologies that the 

agencies regard, subject to consideration of public comment, as the maximum feasible for 

purposes of EISA Section 32902 (k) and appropriate under CAA Section 202 (a) for the reasons 

given above. The agencies believe these technologies can be adopted at the estimated rates for 

these standards within the lead time provided, as discussed in draft RIA Chapter 2. The 2021 

and 2024 MY standards are phase-in standards on the path to the 2027 MY standards and were 

developed using less aggressive application rates and therefore have lower technology package 

costs than the 2027 MY standards. 

As described in Section II.D.(2) (d) below, the cost of the proposed standards is estimated 

to range from $270 to $1,698 per engine. This is slightly higher than the costs for Phase 1, 

which were estimated to be $234 to $1,091 per engine. Although the agencies did not separately

determine fuel savings or emission reductions due to the engine standards apart from the vehicle 

program, it is expected that the fuel savings would be significantly larger than these costs, and 

the emission reductions would be roughly proportional to the technology costs when compared 

to the corresponding vehicle program reductions and costs. Thus, we regard these standards as 

cost-effective. This is true even without considering payback period. The proposed phase-in 

2021 and 2024 MY standards are less stringent and less costly than the proposed 2027 MY 

standards. Given that the agencies believe the proposed standards are technologically feasible, 

are highly cost effective, and highly cost effective when 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 proposed standards appear to 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). 

(b) Basis for Continuing the Phase 1 Spark-Ignited Engine Standard

Today most SI-powered vocational vehicles are sold as incomplete vehicles by a 

vertically integrated chassis manufacturer, where the incomplete chassis shares most of the same 
Page 135 of 850

technology as equivalent complete pickups or vans, including the powertrain. The number of 

such incomplete SI-powered vehicles is small compared to the number of completes. Another, 

even less common way that SI-powered vocational vehicles are built is by a non-integrated 

chassis manufacturer purchasing an engine from a company that also produces complete and/or 

incomplete HD pickup trucks and vans. The resulting market structure leads manufacturers of 

heavy-duty SI engines to have little market incentive to develop separate technology for 

vocational engines that are engine-certified. Moreover, the agencies have not identified a single 

SI engine technology that we believe belongs on engine-certified vocational engines that we do 

not also project to be used on complete heavy-duty pickups and vans.

In light of this market structure, when the agencies considered the feasibility of more 

stringent Phase 2 standards for SI vocational engines, we identified the following key questions:

1. Will there be technologies available that could reduce in-use emissions from 

vocational SI engines?

2. Would these technologies be applied to complete vehicles and carried-over to 

engine certified engines without a new standard?

3. Would these technologies be applied to meet the vehicle-based standards 

described in Section V?

4. What are the drawbacks associated with setting a technology-forcing Phase 2 

standard for SI engines?

With respect to the first and second questions, as noted in Chapter 2.6 of the draft RIA, 

the agencies have identified improved lubricants, friction reduction, and cylinder deactivation as 

technologies that could potentially reduce in-use emissions from vocational engines; and the 

agencies have further determined that to the extent these technologies would be viable for 

complete vehicles, they would also be applied to engine-certified engines. Nevertheless, 

significant uncertainty remains about how much benefit would be provided by these 

technologies. It is possible that the combined impact of these technologies would be one percent 

or less. With respect to the third question, we believe that to the extent these technologies are 

viable and effective, they would be applied to meet the vehicle-based standards for vocational 

vehicles.

At this time, it appears the fourth question regarding drawbacks is the most important. 

The agencies could propose a technology forcing standard for vocational SI engines based on a 

projection of each of these technologies being effective for these engines. However, as already 

noted in Section I, the agencies see value in setting the standards at levels that would not require 

every projected technology to work as projected. Effectively requiring technologies to match our 

current projections would create the risk that the standards would not be feasible if even a single 

one of technologies failed to match our projections. This risk is amplified for SI engines because 

of the very limited product offerings, which provide far fewer opportunities for averaging than 

exist for CI engines. Given the relatively small improvement projected, and the likelihood that 

most or all of this improvement would result anyway from the complete pickup and van 

standards and the vocational vehicle-based standards, we do not believe such risk is justified or 

needed. The approach the agencies are proposing accomplishes the same objective without the 

attendant potential risk. With this approach, the Phase 1 SI engine standard for these engines 

would remain in place, and engine improvements would be reflected in the stringency of the 
Page 136 of 850

vehicle standard for the vehicle in which the engine would be installed. Nevertheless, we request 

comment on the merits of adopting a more stringent SI engine standard in the 2024 to 2027 time 

frame, including comment on technologies, adoption rates, and effectiveness over the engine 

cycle that could support adoption of a more stringent standard. Please see Section V.C of this 

preamble for a description of the SI engine technologies that have been considered in developing 

the proposed vocational vehicle standards. Please see Section VI.C of this preamble for a 

description of the SI engine technologies that have been considered in developing the proposed 

HD pickup truck and van standards.

(c) Engine Improvements Projected for Vehicles over the GEM Duty Cycles

Because we are proposing that tractor and vocational vehicle manufacturers represent 

their vehicles’ actual engines in GEM for vehicle certification, the agencies aligned our engine

technology effectiveness assessments for both the separate engine standards and the tractor and 

vocational vehicle standards for each of the regulatory alternatives considered. This was an 

important step because we are proposing to recognize the same engine technologies in both the 

separate engine standards and the vehicle standards, which each have different test procedures 

for demonstrating compliance. As explained earlier in Section II. D. (1) , compliance with the 

tractor separate engine standards is determined from a composite of the Supplemental Engine 

Test (SET) procedure’s 13 steady-state operating points. Compliance with the vocational vehicle 

separate engine standards is determined over the Federal Test Procedure’s (FTP) transient engine 

duty cycle. In contrast, compliance with the vehicle standards is determined using GEM, which 

calculates composite results over a combination of 55 mph and 65 mph steady-state vehicle 

cycles and the ARB Transient vehicle cycle. Note that we are also proposing a new workday

idle cycle for vocational vehicles. Each of these duty cycles emphasizes different engine 

operating points; therefore, they can each recognize certain technologies differently.

Our first step in aligning our engine technology assessment at both the engine and vehicle 

levels was to start with an analysis of how we project each technology to impact performance at 

each of the 13 individual test points of the SET steady-state engine duty cycle. For example, 

engine friction reduction technology would be expected to have the greatest impact at the highest 

engine speeds, where frictional energy losses are the greatest. As another example, turbocharger 

technology is generally optimized for best efficiency at steady-state cruise vehicle speed. For an 

engine this is near its lower peak-torque speed and at a moderately high load that still offers 

sufficient torque reserve to climb modest road grades without frequent transmission gear 

shifting. The agencies also considered the combination of certain technologies causing synergies 

and dis-synergies with respect to engine efficiency at each of these test points. See RIA Chapter 

2 for further details.

Next we estimated unique brake-specific fuel consumption values for each of the 13 SET 

test points for two hypothetical MY2018 tractor engines that would be compliant with the Phase 

1 standards. These were a 15 liter displacement 455 horsepower engine and an 11 liter 350 

horsepower engine. We then added technologies to these engines that we determined were 

feasible for MY2021, MY2024, and MY 2027, and we determined unique improvements at each 

of the 13 SET points. We then calculated composite SET values for these hypothetical engines 

and determined the SET improvements that we could use to propose more stringent separate 

tractor engine standards for MY2021, MY2024, and MY 2027.
Page 137 of 850

To align our engine technology analysis for vehicles to the SET engine analysis described 

above, we then fit a surface equation through each engine’s SET points versus engine speed and 

load to approximate their analogous fuel maps that would represent these same engines in GEM. 

Because the 13 SET test points do not fully cover an engine’s wide range of possible operation, 

we also determined improvements for an additional 6 points of engine operation to improve the 

creation of GEM fuel maps for these engines. Then for each of these 8 tractor engines (two each 

for MY2018, MY2021, MY2024, and MY2027) we ran GEM simulations to represent low-, 

mid-, and high-roof sleeper cabs and low-, mid-, and high-roof day cabs. Class 8 tractors were 

assumed for the 455 horsepower engine and Class 7 tractors (day cabs only) were assumed for 

the 350 horsepower engine. Each GEM simulation calculated results for the 55 mph, 65 mph, 

and ARB Transient cycles, as well as the composite GEM value associated with each of the 

tractor types. After factoring in our Alternative 3 projected market penetrations of the engine 

technologies, we then compared the percent improvements that the same sets of engine 

technology caused over the separate engines’ SET composites and the various vehicles’ GEM 

composites. Compared to their respective MY2018 baseline engines, the two engines of 

different horsepower showed the same percent improvements. All of the tractor cab types 

showed nearly the same relative improvements too. For example, for the MY2021 Alternative 3 

engine technology package in a high roof sleeper tractor, the SET engine composites showed a 

1.5 percent improvement and the GEM composites a 1.6 percent improvement. For the MY2024 

Alternative 3 engine technology packages, the SET engine composites showed a 3.7 percent 

improvement and the GEM composites a 3.7 percent improvement. For MY2027 Alternative 3 

engine technology packages, the SET engine composites showed a 4.2 percent improvement and 

the GEM composites a 4.2 percent improvement. We therefore concluded that tractor engine 

technologies will improve engines and tractors proportionally, even though the separate engine 

and vehicle certification test procedures have different duty cycles.

We then repeated this same process for the FTP engine transient cycle and the GEM 

vocational vehicle types. For the vocational engine analysis we investigated four engines: 15 

liter displacement engine at 455 horsepower rating, 11 liter displacement engine at 345 

horsepower rating, a 7 liter displacement engine at a 200 horsepower rating and a 270 

horsepower rating. These engines were then used in GEM over the light-heavy, medium-heavy, 

and heavy-heavy vocational vehicle configurations. Because the technologies were assumed to 

impact each point of the FTP in the same way, the results for all engines and vehicles were 2.0 

percent improvement in MY2021, 3.5 percent improvement in MY2024, and 4.0 percent 

improvement in MY2027. Therefore, we arrived at the same conclusion that vocational vehicle 

engine technologies are recognized at the same percent improvement over the FTP as the GEM 

cycles. We request comment on our approach to arrive at this conclusion.

(d) Engine Technology Package Costs for Tractor and Vocational Engines (and Vehicles)

As described in Chapters 2 and 7 of the draft RIA, the agencies estimated costs for each 

of the engines technologies discussed here. All costs are presented relative to engines projected 

to comply with the model year 2017 standards – i.e., relative to our baseline engines. Note that 

we are not presenting any costs for gasoline engines (SI engines) because we are not proposing 

to change the standards.
Page 138 of 850

Our engine cost estimates include a separate analysis of the incremental part costs, 

research and development activities, and additional equipment. Our general approach used 

elsewhere in this action (for HD pickup trucks, gasoline engines, Class 7 and 8 tractors, and 

Class 2b-8 vocational vehicles) estimates a direct manufacturing cost for a part and marks it up 

based on a factor to account for indirect costs. See also 75 FR 25376. We believe that approach 

is appropriate when compliance with proposed 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 that OEMs will incur costs not associated with 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 have directly estimated additional indirect costs to account for these development 

costs. The agencies used the same approach in the Phase 1 HD rule. 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 would 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 draft RIA Chapter 2. To reiterate, we 

have used this different approach because the MHD and HHD diesel engines are expected to 

comply in part via technology changes that are not reflected in new hardware but rather reflect 

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. Note that these engines are also expected to incur new hardware costs 

as shown in Table II-8 through Table II-11. EPA also developed the incremental piece cost for 

the components to meet each of the 2021 and 2024 standards. The costs shown in Table II-12

include a low complexity ICM of 1.15 and assume the flat-portion of the learning curve is 

applicable to each technology.
Page 139 of 850

(i) Tractor Engine Package Costs

Table II-8 Proposed MY2021 Tractor Diesel Engine Component Costs Inclusive of Indirect Cost Markups 

and Adoption Rates (2012$)

Medium HD Heavy HD

Aftertreatment system (improved 

effectiveness SCR, dosing, DPF)

$7 $7

Valve Actuation $82 $82

Cylinder Head (flow optimized, 

increased firing pressure, improved 

thermal management)

$3 $3

Turbocharger (improved efficiency) $9 $9

Turbo Compounding $50 $50

EGR Cooler (improved efficiency) $2 $2

Water Pump (optimized, variable 

vane, variable speed)

$43 $43

Oil Pump (optimized) $2 $2

Fuel Pump (higher working pressure, 

increased efficiency, improved 

pressure regulation)

$2 $2

Fuel Rail (higher working pressure) $5 $5

Fuel Injector (optimized, improved 

multiple event control, higher working 

pressure)

$5 $5

Piston (reduced friction skirt, ring and 

pin)

$1 $1

Valvetrain (reduced friction, roller 

tappet)

$39 $39

Waste Heat Recovery $105 $105

“Right sized” engine -$40 -$40

Total $314 $314

Note: “Right sized” diesel engine is a smaller, less costly engine than the engine it replaces.
Page 140 of 850

Table II-9 Proposed MY2024 Tractor Diesel Engine Component Costs Inclusive of Indirect Cost Markups 

and Adoption Rates (2012$)

Medium HD Heavy HD

Aftertreatment system (improved 

effectiveness SCR, dosing, DPF)

$14 $14

Valve Actuation $166 $166

Cylinder Head (flow optimized, 

increased firing pressure, improved 

thermal management)

$6 $6

Turbocharger (improved efficiency) $17 $17

Turbo Compounding $92 $92

EGR Cooler (improved efficiency) $3 $3

Water Pump (optimized, variable 

vane, variable speed)

$84 $84

Oil Pump (optimized) $4 $4

Fuel Pump (higher working pressure, 

increased efficiency, improved 

pressure regulation)

$4 $4

Fuel Rail (higher working pressure) $9 $9

Fuel Injector (optimized, improved 

multiple event control, higher working 

pressure)

$10 $10

Piston (reduced friction skirt, ring and 

pin)

$3 $3

Valvetrain (reduced friction, roller 

tappet)

$75 $75

Waste Heat Recovery $502 $502

“Right sized” engine -$85 -$85

Total $904 $904

Note: “Right sized” diesel engine is a smaller, less costly engine than the engine it replaces.
Page 141 of 850

Table II-10 Proposed MY2027 Tractor Diesel Engine Component Costs Inclusive of Indirect Cost Markups 

and Adoption Rates (2012$)

Medium HD Heavy HD

Aftertreatment system (improved 

effectiveness SCR, dosing, DPF)

$14 $14

Valve Actuation $169 $169

Cylinder Head (flow optimized, 

increased firing pressure, improved 

thermal management)

$6 $6

Turbocharger (improved efficiency) $17 $17

Turbo Compounding $87 $87

EGR Cooler (improved efficiency) $3 $3

Water Pump (optimized, variable 

vane, variable speed)

$84 $84

Oil Pump (optimized) $4 $4

Fuel Pump (higher working pressure, 

increased efficiency, improved 

pressure regulation)

$4 $4

Fuel Rail (higher working pressure) $9 $9

Fuel Injector (optimized, improved 

multiple event control, higher working 

pressure)

$10 $10

Piston (reduced friction skirt, ring and 

pin)

$3 $3

Valvetrain (reduced friction, roller 

tappet)

$75 $75

Waste Heat Recovery $1,340 $1,340

“Right sized” engine -$127 -$127

Total $1,698 $1,698

Note: “Right sized” diesel engine is a smaller, less costly engine than the engine it replaces.
Page 142 of 850

(ii) Vocational Diesel Engine Package Costs

Table II-11 Proposed MY2021 Vocational Diesel Engine Component Costs Inclusive of Indirect Cost 

Markups and Adoption Rates (2012$)

Light HD Medium HD Heavy HD

Aftertreatment system (improved 

effectiveness SCR, dosing, DPF)

$8 $8 $8

Valve Actuation $91 $91 $91

Cylinder Head (flow optimized, 

increased firing pressure, improved 

thermal management)

$6 $3 $3

Turbocharger (improved efficiency) $10 $10 $10

EGR Cooler (improved efficiency) $2 $2 $2

Water Pump (optimized, variable 

vane, variable speed)

$57 $57 $57

Oil Pump (optimized) $3 $3 $3

Fuel Pump (higher working pressure, 

increased efficiency, improved 

pressure regulation)

$3 $3 $3

Fuel Rail (higher working pressure) $7 $6 $6

Fuel Injector (optimized, improved 

multiple event control, higher working 

pressure)

$8 $6 $6

Piston (reduced friction skirt, ring and 

pin)

$1 $1 $1

Valvetrain (reduced friction, roller 

tappet)

$69 $52 $52

Model Based Controls $28 $28 $28

Total $293 $270 $270
Page 143 of 850

Table II-12 Proposed MY2024 Vocational Diesel Engine Component Costs Inclusive of Indirect Cost 

Markups and Adoption Rates (2012$)

Light HD Medium HD Heavy HD

Aftertreatment system (improved 

effectiveness SCR, dosing, DPF)

$13 $13 $13

Valve Actuation $157 $157 $157

Cylinder Head (flow optimized, 

increased firing pressure, improved 

thermal management)

$10 $6 $6

Turbocharger (improved efficiency) $16 $16 $16

EGR Cooler (improved efficiency) $3 $3 $3

Water Pump (optimized, variable 

vane, variable speed)

$79 $79 $79

Oil Pump (optimized) $4 $4 $4

Fuel Pump (higher working pressure, 

increased efficiency, improved 

pressure regulation)

$4 $4 $4

Fuel Rail (higher working pressure) $10 $9 $9

Fuel Injector (optimized, improved 

multiple event control, higher working 

pressure)

$13 $10 $10

Piston (reduced friction skirt, ring and 

pin)

$2 $2 $2

Valvetrain (reduced friction, roller 

tappet)

$95 $71 $71

Model Based Controls $31 $31 $31

Total $437 $405 $405
Page 144 of 850

Table II-13 Proposed MY2027 Vocational Diesel Engine Component Costs Inclusive of Indirect Cost 

Markups and Adoption Rates (2012$)

Light HD Medium HD Heavy HD

Aftertreatment system (improved 

effectiveness SCR, dosing, DPF)

$14 $14 $14

Valve Actuation $169 $169 $169

Cylinder Head (flow optimized, 

increased firing pressure, improved 

thermal management)

$10 $6 $6

Turbocharger (improved efficiency) $17 $17 $17

EGR Cooler (improved efficiency) $3 $3 $3

Water Pump (optimized, variable 

vane, variable speed)

$84 $84 $84

Oil Pump (optimized) $4 $4 $4

Fuel Pump (higher working pressure, 

increased efficiency, improved 

pressure regulation)

$4 $4 $4

Fuel Rail (higher working pressure) $11 $9 $9

Fuel Injector (optimized, improved 

multiple event control, higher working 

pressure)

$13 $10 $10

Piston (reduced friction skirt, ring and 

pin)

$3 $3 $3

Valvetrain (reduced friction, roller 

tappet)

$100 $75 $75

Model Based Controls $39 $39 $39

Total $471 $437 $437

(e) Feasibility of Phasing In the CO2 and Fuel Consumption Standards Sooner

The agencies are requesting comment on accelerated standards for diesel engines that 

would achieve the same reductions as the proposed standards, but with less lead time. Table 

II-14 and Table II-15 below show a technology path that the agencies project could be used to 

achieve the reductions that would be required within the lead time allowed by the alternative 

standards. As discussed in Sections I and X, the agencies are proposing to fully phase in these 

standards through 2027. The agencies believe that standards that fully phase in through 2024 

have the potential to be the maximum feasible and appropriate option. However, based on the 

evidence currently before the agencies, we have outstanding questions (for which we are seeking 

comment) regarding relative risks and benefits of that option in the timeframe envisioned. 
Page 145 of 850

Commenters are encouraged to address how technologies could develop if a shorter lead time is 

selected. In particular, we request comment on the likelihood that WHR systems would be 

available for tractor engines in this time frame, and that WHR systems would achieve the 

projected level of reduction and the necessary reliability. We also request comment on whether 

it would be possible to apply the model based controls described in Section II.D.(2) (a)(i) to this 

many vocational engines in this time frame.

Table II-14 Projected Tractor Engine Technologies and Reduction for Alternative 4 Standards

%-Improvements 

beyond Phase 1, 2018 

engine as baseline

SET reduction 

(%)

Market 

penetration 

MY 2021

Market 

penetration 

MY 2024

Turbo compound 1.82% 5% 10%

WHR (Rankine cycle) 3.58% 4% 15%

Parasitics/Friction (Cyl

Kits, pumps, FIE), 

lubrication

1.41% 60% 100%

Aftertreatment 0.61% 60% 100%

Exh Manifold

Turbo Efficiency

EGR Cooler

VVT

1.14% 60% 100%

Combustion/FI/Control 1.11% 60% 100%

Downsizing 0.29% 20% 30%

Market Penetration Weighted Package 2.1% 4.2%
Page 146 of 850

Table II-15 Projected Vocational Engine Technologies and Reduction for More Stringent Alternative 

Standards

%-Improvements beyond 

Phase 1, 2018 engine as 

baseline

FTP 

reduction

Market 

Penetration 

MY 2021

Market 

Penetration 

MY 2024

Model based control 2% 30% 40%

Parasitics /Friction 1.5% 70% 100%

EGR/Air/VVT /Turbo 1% 70% 100%

Improved AT 0.5% 70% 100%

Combustion Optimization 1% 70% 100%

Weighted reduction (%)-

L/MHD/HHD

2.5% 4.0%

The projected HDD engine package costs for both tractors and vocational engines in 

MYs 2021 and 2024 under Alternative 4 are shown in Table II-16. Note that, while the 

technology application rates in MY2024 under Alternative 4 are essentially identical to those for 

MY2027 under the proposal, the costs are about 5 to 11 percent higher under Alternative 4 due to 

learning effects and markup changes that are estimated to have occurred by MY2027 under 

Alternative 3. Note also that the agencies did not include any additional costs for accelerating 

technology development or to address potential in-use durability issues. We request comment on 

whether such costs would occur if we finalized this alternative. We also request comment on 

what steps could be taken to mitigate such costs. 

Table II-16 Expected Package Costs for HD Diesel Engines under Alternative 4 (2012$)

a

Model 

Year

MHDD 

Tractor

HHDD 

Tractor

LHDD 

Vocational

MHDD 

Vocational

HHDD 

Vocational

2021 $656 $656 $372 $345 $345

2024 $1,885 $1,885 $493 $457 $457

Note:

a

Costs presented here include application rates.

The agencies’ analysis shows that, in the absence of additional costs for accelerating 

technology development or to address potential in-use durability issues, the costs associated with 

Alternative 4 would be very similar to those we project for the proposed standards. Alternative 4 

would also have similar payback times and cost-effectiveness. In other words, Alternative 4 

would achieve some additional reductions for model years 2021 through 2026, with roughly 

proportional additional costs unless there were additional costs for accelerating development or 

for in-use durability issues. (Note that reductions and costs for MY 2027 and later would be 

equivalent for the Alternative 4 and the proposed standards). We request comment on the 

following issues: whether manufacturers could meet these standards with three years less 

lead time, what additional expenses would be incurred to meet these standards with less lead 
Page 147 of 850

time, and how reliable would the engines be if the manufacturers had to bring them to market 

three years earlier. 

(3) Proposed EPA Engine Standards for N2O

EPA is proposing to adopt the MY 2021 N2O engine standards that were originally 

proposed for Phase 1. The proposed level for Phase 2 would be 0.05 g/hp-hr with a default 

deterioration factor of 0.01 g/hp-hr, which we believe is technologically feasible because a 

number of engines meet this level today. This level of stringency is consistent with the agency’s 

Phase 1 approach to set “cap” standards for N2O. EPA finalized Phase 1 standards for N2O as 

engine-based standards at 0.10 g/hp-hr and a 0.02 g/hp-hr default deterioration factor because the 

agency believes that emissions of this GHG are technologically related solely to the engine, fuel, 

and emissions aftertreatment systems, and the agency is not aware of any influence of vehiclebased technologies on these emissions. We continue to believe this approach is appropriate, but 

we believe that more stringent standards are appropriate to ensure that N2O emissions do not 

increase in the future. Note that NHTSA did not adopt standards for N2O because these 

emissions do not impact fuel consumption in a significant way, and is not proposing such 

standards for Phase 2 for the same reason. 

We are proposing this change at no additional cost and no additional benefit because 

manufacturers are generally meeting the proposed standard today. The purpose of this standard

is to prevent increases in N2O emissions absent this proposed increase in stringency. We request 

comment on whether or not we should be considering additional costs for compliance. Similarly, 

we request comment on whether or not we should assume N2O increases in our “No Action” 

regulatory Alternatives 1a and 1b described in Section X.

Although N2O is emitted in very small amounts, it can have a very significant impact on 

the climate. The global warming potential (GWP) of one molecule of N2O is 298 times that of 

one molecule CO2. Because N2O and CO2 coincidentally have the same molar mass, this means 

that one gram of N2O would have the same impact on the climate as 298 grams of CO2. To 

further put this into perspective, the difference between the proposed N2O standard (and 

deterioration factor) and the current Phase 1 standard is 0.40 g/hp-hr of N2O emissions. This is 

equivalent to 11.92 g/hp-hr CO2. Over the same certification test cycle (i.e. EPA’s HD FTP) the

Phase 1 engine CO2 emissions standard ranges from 460 to 576 g/hp-hr, depending on the 

service class of the engine. Therefore, absent today’s proposed action, engine N2O increases 

equivalent to 2.1 to 2.6 percent of the Phase 1 CO2 standard could occur. 

We are proposing this lower cap because we have determined that manufacturers 

generally are meeting this level today but in the future could increase N2O emissions up to the 

current Phase 1 cap standard. Because we do not believe any manufacturer would need to do 

anything more than recalibrate their SCR systems to comply, the lead time being provided would 

be sufficient. This section later describes why manufacturers may increase N2O emissions from 

SCR-equipped compression-ignition engines in the absence of a lower N2O cap standard. We 

request comment on this. We also note that, as described in Section XI, EPA does not believe 

there is a similar opportunity to lower the pickup and van N2O standard because it was set at a 

more stringent level in Phase 1. 
Page 148 of 850

(a) N2O Formation

N2O formation in modern diesel engines is a by-product of the SCR process. It is 

dependent on the SCR catalyst type, the NO2 to NOX ratio, the level of NOX reduction required, 

and the concentration of the reactants in the system (NH3 to NOX ratio).

Two current engine/aftertreatment designs are driving N2O emission higher. The first is 

an increase in engine out NOX, which puts a higher NOX reduction burden on the SCR NOX

emission control system. The second is an increase in NO2 formation from the diesel oxidation 

catalyst (DOC) located upstream of the passive catalyzed diesel particulate filter (CDPF). This 

increase in NO2 serves two functions: improving passive CDPF regeneration and optimization of 

faster SCR reaction. 109

There are multiple mechanisms through which N2O can form in an SCR system:

1. Low temperature formation of N2O over the DOC prior to the SCR catalyst.

2. Low temperature formation of NH4NO3 with subsequent decomposition as exhaust 

temperatures increase, leading to conversion to N2O over the SCR catalyst.

3. Formation of N2O from NO2 over the SCR catalyst at NO2 to NO ratios greater than 1:1.

N2O formation increases significantly at 300 to 350 °C.

4. Formation of N2O from NH3 via partial oxidation over the ammonia slip catalyst.

5. High-temperature N2O formation over the SCR catalyst due to NH3 oxidation facilitated 

by high SCR catalyst surface coverage of NH3.

Thus, as discussed below, control of N2O formation requires precise optimization of SCR 

controls including thermal management and dosing rates, as well as catalyst composition.

(b) N2O Emission Reduction

Through on-engine and reactor bench experiments, this same work showed that the key to 

reducing N2O emissions lies in intelligent emission control system design and operation, namely:

1. Selecting the appropriate DOC and/or CDPF catalyst loadings to maintain NO2 to NO 

ratios at or below 1:1.

2. Avoiding high catalyst surface coverage of NH3 though urea dosing management when 

the system is in the ideal N2O formation window.

3. Utilizing thermal management to push the SCR inlet temperature outside of the N2O lowtemperature formation window.

EPA believes that reducing the standard from 0.1 g/hp-hr to 0.05 g/hp-hr is feasible 

because most engines have emission rates that would meet this standard today and the others

could meet it with minor calibration changes at no additional cost. Numerous studies have 

 

109 Hallstrom, K., Voss, K., and Shah, S., "The Formation of N2O on the SCR Catalyst in a Heavy Duty US 2010 

Emission Control System", SAE Technical Paper 2013-01-2463.
Page 149 of 850

shown that diesel engine technologies can be fine-tuned to meet the current NOX and proposed 

N2O standards while still providing passive CDPF regeneration even with earlier generations of 

SCR systems. Currently model year 2014 systems have already moved on to newer generation 

systems in which the combined CDPF and SCR functions have been further optimized. The 

result of this is 18 of 24 engines in the EPA 2014 certification database emitting N2O at less than 

half of the 2014 standard, and thus below the proposed standard.110 Given the discussions in the 

literature, there are still additional calibration steps that can be taken to further reduce N2O 

emissions for the higher emitters to afford an adequate compliance margin and room to account 

for deterioration, without having an adverse effect on criteria pollutant emissions.

 

110 http://www.epa.gov/otaq/crttst.htm
Page 150 of 850

Figure II-2 EPA 2014 Certification Database N2O Emission Results for 24 Engines.
Page 151 of 850

It is important to note, however, that there is a trade off when trying to optimize SCR 

systems to achieve peak NOX reduction efficiencies. When transitioning from a <93 percent 

efficient MY 2011 system to a 98 percent efficient system of the future, lowering the N2O cap to 

0.05 g/hp-hr would put constraints on the techniques that can be applied to improve efficiency. 

If system designers push the NH3 to NOX ratio higher to try and achieve the maximum possible 

NOX reduction, it could increase N2O emissions. If EPA were to adopt a very low NOX standard 

(e.g., 0.02 g/hp-hr) over existing test cycles, some reductions would be needed throughout the 

hot portion of the cycle (although most of the reductions would have to come from the cold start 

portion of the test cycle). Thermal management would need to play a key role, and reducing 

catalyst light-off time would move the SCR catalyst through the ammonium nitrate formation 

and decomposition thermal range quicker, thus lowering N2O emissions. An increase in the NH3

to NOX ratio could also further reduce NOX emissions; however this would also adversely affect 

NH3 slip and N2O formation. The inability of NH3 slip catalysts to handle the increased NH3

load and the EPA NH3 slip limit of 10 ppm would guard against this NH3 to NOX ratio increase, 

and thus subsequent N2O increase.

In summary, EPA believes that engine manufacturers would be able to respond with 

highly efficient NOX reducing systems that can meet the proposed lower N2O cap of 0.05 g/hp-hr 

with no additional cost or lead time. When optimizing SCR systems for better NOX reduction 

efficiency, that optimization includes lowering the emissions of undesirable side reactions, 

including those that form N2O.

(4) EPA Engine Standards for Methane

EPA is proposing to apply the Phase 1 methane engine standards to the Phase 2 program. 

EPA adopted the cap standards for CH4 (along with N2O standards) as engine-based standards 

because the agency believes that emissions of this GHG 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. Note that NHTSA did not adopt standards for 

CH4 (or N2O) because these emissions do not impact fuel consumption in a significant way, and 

is not proposing CH4 standards for Phase 2 either. 

EPA continues to believe that manufacturers of most engine technologies will be able to 

comply with the Phase 1 CH4 standard with no technological improvements. We note that we 

are not aware of any new technologies that would allow us to adopt more stringent standards at 

this time. We request comment on this.

(5) Compliance Provisions and Flexibilities for Engine Standards

The agencies are proposing to continue most of the Phase 1 compliance provisions and 

flexibilities for the Phase 2 engine standards. 

(a) Averaging, Banking, and Trading

The agencies’ general approach to averaging is discussed in Section I. We are not 

proposing to offer any special credits to engine manufacturers. Except for early credits and 
Page 152 of 850

advanced technology credits, the agencies propose to retain all Phase 1 credit flexibilities and 

limitations to continue for use in the Phase 2 program.

As discussed below, EPA is proposing to change the useful life for LHD engines for 

GHG emissions from the current 10 years/110,000 miles to 15 years/150,000 miles to be 

consistent with the useful life of criteria pollutants recently updated in EPA’s Tier 3 rule. In 

order to ensure that banked credits would maintain their value in the transition from Phase 1 to 

Phase 2, NHTSA and EPA propose an adjustment factor of 1.36 (i.e., 150,000 mile ÷ 110,000 

miles) for credits that are carried forward from Phase 1 to the MY 2021 and later Phase 2 

standards. Without this adjustment factor the proposed change in useful life would effectively 

result in a discount of banked credits that are carried forward from Phase 1 to Phase 2, which is 

not the intent of the change in the useful life. See Sections V and VI for additional discussion of 

similar adjustments of vehicle-based credits. 

(b) Request for Comment on Changing Global Warming Potential Values in the Credit Program 

for CH4 and N2O

The Phase 1 rule included a compliance alternative allowing heavy-duty manufacturers 

and conversion companies to comply with the respective methane or nitrous oxide standards by

means of over-complying with CO2 standards (40 CFR 1036.705(d)). The heavy-duty rules 

allow averaging only between vehicles or engines of the same designated type (referred to as an 

“averaging set” in the rules). Specifically, the phase 1 heavy-duty rulemaking added a CO2

credits program which allowed heavy-duty manufacturers to average and bank pollutant 

emissions to comply with the methane and nitrous oxide requirements after adjusting the CO2

emission credits based on the relative GHG equivalents. To establish the GHG equivalents used 

by the CO2 credits program, the Phase 1 rule incorporated the IPCC Fourth Assessment Report 

global warming potential (GWP) values of 25 for CH4 and 298 for N2O, which are assessed over 

a 100 year lifetime.

Since the Phase 1 rule was finalized, a new IPCC report has been released (the Fifth 

Assessment Report), with new GWP estimates. This is prompting us to look again at the relative 

CO2 equivalency of methane and nitrous oxide and to seek comment on whether the methane and 

nitrous oxide GWPs used to establish the GHG equivalency value for the CO2 Credit program 

should be updated to those established by IPCC in its Fifth Assessment Report. The Fifth 

Assessment Report provides four 100 year GWPs for methane ranging from 28 to 36 and two 

100 year GWPs for nitrous oxide, either 265 or 298. Therefore, we not only request comment on 

whether to update the GWP for methane and nitrous oxide to that of the Fifth Assessment 

Report, but also on which value to use from this report. 

(c) In-Use Compliance and Useful Life

Consistent with Section 202(a)(1) and 202 (d) of the CAA, for Phase 1, EPA established 

in-use standards for heavy-duty engines. Based on our assessment of testing variability and 

other relevant factors, we established in-use standards by adding a 3 percent adjustment factor to 

the full useful life emissions and fuel consumption results measured in the EPA certification 

process to address measurement variability inherent in comparing results among different 
Page 153 of 850

laboratories and different engines. See 40 CFR part 1036. The agencies are not proposing to 

change this for Phase 2, but request comment on whether this allowance is still necessary.

We note that in Phase 1, we applied these standards to only certain engine configurations 

in each engine family (often called the parent rating). We welcome comment on whether the 

agencies should set Phase 2 CO2 and fuel consumption standards for the other ratings (often 

called the child ratings) within an engine family. We are not proposing specific engine standards 

for child ratings in Phase 2 because we are proposing to include the actual engine’s fuel map in 

the vehicle certification. We believe this approach appropriately addresses our concern that 

manufacturers control CO2 emissions and fuel consumption from all in-use engine configurations

within an engine family.

In Phase 1, EPA set the useful life for engines and vehicles with respect to GHG 

emissions equal to the respective useful life periods for criteria pollutants. In April 2014, as part 

of the Tier 3 light-duty vehicle final rule, EPA extended the regulatory useful life period for 

criteria pollutants to 150,000 miles or 15 years, whichever comes first, for Class 2b and 3 pickup 

trucks and vans and some light-duty trucks (79 FR 23414, April 28, 2014). As described in 

Section V, EPA is proposing that the Phase 2 GHG standards for vocational vehicles at or below 

19,500 pounds GVWR apply over the same useful life of 150,000 miles or 15 years. To be 

consistent with that proposed change, we are also proposing that the Phase 2 GHG standards for 

engines used in vocational vehicles at or below 19,500 pounds GVWR apply over the same 

useful life of 150,000 miles or 15 years.

We are proposing to continue regulatory allowance in 40 CFR 1036.150(g) that allows 

engine manufacturers to use assigned deterioration factors (DFs) for most engines without 

performing their own durability emission tests or engineering analysis. However, the engines 

would still be required to meet the standards in actual use without regard to whether the 

manufacturer used the assigned DFs. This allowance is being continued as an interim provision 

and may be discontinued for later phases of standards as more information becomes known. 

Manufacturers are 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 off-cycle technologies). 

Upon request, we could allow the assigned DF for CO2 emissions from engines including 

advance or off-cycle 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.

We are also requesting comment on how to apply DFs to low level measurements where 

test-to-test variability may be larger than the actual deterioration rates being measured, such as 

might occur with N2O. Should we allow statistical analysis to be used to identifying trends 

rather than basing the DF on the highest measured value? How would we allow this where 

emission deterioration is not linear, such as saw-tooth deterioration related to maintenance or 

other offsetting emission effects causing emissions to peak before the end of the useful life? 

Finally, EPA requests comment on whether a similar allowance would be appropriate for criteria 

pollutants as well.
Page 154 of 850

(d) Alternate CO2 Standards

In the Phase 1 rulemaking, the agencies proposed provisions to allow certification to 

alternate CO2 engine standards in model years 2014 through 2016. This flexibility was intended 

to address the special case of needed lead time to implement new standards for a previously

unregulated pollutant. Since that special case does not apply for Phase 2, we are not proposing a 

similar flexibility in this rulemaking. We also request comment on whether this allowance 

should be eliminated for Phase 1 engines.

(e) Proposed Approach to Standards and Compliance Provisions for Natural Gas Engines

EPA is also proposing certain clarifying changes to its rules regarding classification of 

natural gas engines. This proposal relates to standards for all emissions, both greenhouse gases 

and criteria pollutants. These clarifying changes are intended to reflect the status quo, and 

therefore should not have any associated costs.

EPA emission standards have always applied differently for gasoline-fueled and dieselfueled engines. The regulations in 40 CFR part 86 implement these distinctions by dividing 

engines into Otto-cycle and Diesel-cycle technologies. This approach led EPA to categorize 

natural gas engines according to their design history. A diesel engine converted to run on natural 

gas was classified as a diesel-cycle engine; a gasoline engine converted to run on natural gas was 

classified as an Otto-cycle engine. 

The Phase 1 rule described our plan to transition to a different approach, consistent with 

our nonroad programs, in which we divide engines into compression-ignition and spark-ignition 

technologies based only on the operating characteristics of the engines.111 However, the Phase 1 

rule included a provision allowing us to continue with the historic approach on an interim basis. 

Under the existing EPA regulatory definitions of “compression-ignition” and “sparkignition”, a natural gas engine would generally be considered compression-ignition if it operates 

with lean air-fuel mixtures and uses a pilot injection of diesel fuel to initiate combustion, and 

would generally be considered spark-ignition if it operates with stoichiometric air-fuel mixtures 

and uses a spark plug to initiate combustion.

EPA’s basic premise here is that natural gas engines performing similar in-use functions 

should be subject to similar regulatory requirements. The compression-ignition emission 

standards and testing requirements reflect the operating characteristics for the full range of 

heavy-duty vehicles, including substantial operation in long-haul service characteristic of 

tractors. The spark-ignition emission standards and testing requirements do not include some of 

those provisions related to use in long-haul service or other applications where diesel engines 

predominate, such as steady-state testing, Not-to-Exceed standards, and extended useful life. We 

believe it would be inappropriate to apply the spark-ignition standards and requirements to 

natural gas engines that would be used in applications mostly served by diesel engines today. 

 

111 See 40 CFR 1036.108
Page 155 of 850

We are therefore proposing to replace the interim provision described above with a differentiated 

approach to certification of natural gas engines across all of the EPA standards – for both GHGs 

and criteria pollutants. Under the proposed clarifying amendment, we would require 

manufacturers to divide all their natural gas engines into primary intended service classes, as we 

already require for compression-ignition engines, whether or not the engine has features that 

otherwise could (in theory) result in classification as SI under the current rules. Any natural gas 

engine qualifying as a medium heavy-duty engine (19,500 to 33,000 pounds GVWR) or a heavy 

heavy-duty engine (over 33,000 pounds GVWR) would be subject to all the emission standards 

and other requirements that apply to compression-ignition engines. 

Table II-17 describes the provisions that would apply differently for compression-ignition 

and spark-ignition engines:

Table II-17 Regulatory Provisions that are Different for Compression-Ignition and Spark-Ignition Engines

Provision Compression-Ignition Spark-Ignition

Transient duty cycle 40 CFR part 86, Appendix I, 

paragraph (f)(2) cycle; divide by

1.12 to de-normalize

40 CFR part 86, Appendix 

I, paragraph (f)(1) cycle

Ramped-modal test (SET) yes no

NTE standards yes no

Smoke standard yes no

Manufacturer-run in-use 

testing

yes no

ABT – pollutants NOX, PM NOX, NMHC

ABT— transient conversion 

factor

6.5 6.3

ABT – averaging set Separate averaging sets for light, 

medium, and heavy HDDE

One averaging set for all 

SI engines

Useful life 110,000 miles for light HDDE

185,000 miles for medium 

HDDE

435,000 miles for heavy HDDE

110,000 miles

Warranty 50,000 miles for light HDDE

100,000 miles for medium 

HDDE

100,000 miles for heavy HDDE

50,000 miles

Detailed AECD description yes no

Test engine selection highest injected fuel volume most likely to exceed 

emission standards

The onboard diagnostic requirements already differentiate requirements by fuel type, so 

there is no need for those provisions to change based on the considerations of this section.

We are not aware of any currently certified engines that would change from compressionignition to spark-ignition under the proposed clarified approach. Nonetheless, because these 
Page 156 of 850

proposed standards implicate rules for criteria pollutants (as well as GHGs), the provisions of 

CAA section 202 (a)(3) (C) apply (for the criteria pollutants), notably the requirement of four 

years lead time. We are therefore proposing to continue to apply the existing interim provision 

through model year 2020.112 Starting in model year 2021, all the provisions would apply as 

described above. Manufacturers would not be permitted to certify any engine families using 

carryover emission data if a particular engine model switched from compression-ignition to 

spark-ignition, or vice versa. However, as noted above, in practice these vehicles are already

being certified as CI engines, so we view these changes as clarifications ratifying the current 

status quo.

We are also proposing that these provisions would apply equally to engines fueled by any 

fuel other than gasoline or ethanol, should such engines be produced in the future. Given the 

current and historic market for vehicles above 19,500 pounds GVWR, EPA believes any 

alternative-fueled vehicles in this weight range would be competing primarily with diesel 

vehicles and should be subject to the same requirements as them. We request comment on all 

aspects of classifying natural-gas and other engines for purposes of applying emission standards. 

See Sections XI and XII for additional discussion of natural gas fueled engines.

(f) Crankcase Emissions from Natural Gas Engines

EPA is proposing one fuel-specific provision for natural gas engines, likewise applicable 

to all pollutant emissions, both GHGs and criteria pollutant emissions. Note that we are also 

proposing other vehicle-level emissions controls for the natural gas storage tanks and refueling 

connections. These are presented in Section XIII. 

EPA is proposing to require that all natural gas-fueled engines have closed crankcases, 

rather than continuing the provision that allows venting to the atmosphere all crankcase 

emissions from all compression-ignition engines. This has been allowed as long as these vented 

crankcase emissions are measured and accounted for as part of an engine’s tailpipe emissions. 

This allowance has historically been in place to address the technical limitations related to 

recirculating diesel-fueled engines’ crankcase emissions, which have high PM emissions, back 

into the engine’s air intake. High PM emissions vented into the intake of an engine can foul 

turbocharger compressors and aftercooler heat exchangers. In contrast, historically EPA has 

mandated closed crankcase technology on all gasoline fueled engines and all natural gas sparkignition engines.113

 The inherently low PM emissions from these engines posed no technical 

barrier to a closed crankcase mandate. Because natural gas-fueled compression ignition engines 

also have inherently low PM emissions, there is no technological limitation that would prevent 

manufacturers from closing the crankcase and recirculating all crankcase gases into a natural 

gas-fueled compression ignition engine’s air intake. We are requesting comment on the costs 

and effectiveness of technologies that we have identified to comply with these provisions. In 

 

112 Section 202 (a)(2), applicable to emissions of greenhouse gases, does not mandate a specific period of lead time, 

but EPA sees no reason for a different compliance date here for GHGs and criteria pollutants. This is also true with 

respect to the closed crankcase emission discussed in the following subsection.

113 See 40 CFR 86.008-10(c).
Page 157 of 850

addition, EPA is proposing that this revised standard not take effect until the 2021 model year, 

consistent with the requirement of section 202 (a)(3) (C) to provide four years lead time.
Page 158 of 850

III. Class 7 and 8 Combination Tractors

Class 7 and 8 combination tractors-trailers contribute the largest portion of the total GHG 

emissions and fuel consumption of the heavy-duty sector, approximately two-thirds, due to their 

large payloads, their high annual miles traveled, and their major role in national freight 

transport.114 These vehicles consist of a cab and engine (tractor or combination tractor) and a 

trailer.115 In general, reducing GHG emissions and fuel consumption for these vehicles would 

involve improvements to all aspects of the vehicle. 

As we found during the development in Phase 1 and as continues to be true in the 

industry today, the heavy-duty combination tractor-trailer industry consists of separate tractor 

manufacturers and trailer manufacturers. 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. 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. Thus, 

although tractor-trailers operate essentially as a unit from both a commercial standpoint and for 

purposes of fuel efficiency and CO2 emissions, the agencies have developed separate proposed 

standards for each.

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

appropriate regulatory approach for combination tractors and trailers is to establish standards for 

tractors separately from trailers. As discussed below in Section IV, the agencies are also 

proposing standards for certain types of trailers. 

A. Summary of the Phase 1 Tractor Program

The design of each tractor’s cab and drivetrain determines the amount of power that the 

engine must produce in moving the truck and its payload down the road. As illustrated in Figure 

III-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 for the variety of demands placed on the 

vehicle, regardless of the characteristics of the cab in which it is installed. 

 

114 The on-highway Class 7 and 8 combination tractor-trailers constitute the vast majority of this regulatory 

category. A small fraction of combination tractors are used in off-road applications and are regulated differently, as 

described in Section III.C. 

115

 “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.”
Page 159 of 850

Figure III-1 Combination Tractor and Trailer Loads116

 

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

Program: A Government-Industry Research Partnership, 21CT-001, December 2000.
Page 160 of 850

Accordingly, for Class 7 and 8 combination tractors, the agencies adopted two sets of 

Phase 1 tractor standards for fuel consumption and CO2 emissions. The CO2 emission and fuel 

consumption reductions related to engine technologies are recognized in the engine standards. 

For vehicle-related emissions and fuel consumption, tractor manufacturers are required to meet 

vehicle-based standards. Compliance with the vehicle standard must be determined using the 

GEM vehicle simulation tool. 

The Phase 1 tractor standards were based on several key attributes related to GHG 

emissions and fuel consumption that reasonably represent the many differences in utility and 

performance among these vehicles. 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 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 the customer’s demand. The Phase 1 tractor standards differ depending on GVWR (i.e., 

whether the truck is Class 7 or Class 8), the height of the roof 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. Based on these attributes, the agencies created nine subcategories 

within the Class 7 and 8 combination tractor category. The Phase 1 rules set standards for each 

of them. Phase 1 standards began with the 2014 model year and were followed with more 

stringent standards following in model year 2017.117 The standards represent an overall fuel 

consumption and CO2 emissions reduction up to 23 percent from the tractors and the engines 

installed in them when compared to a baseline 2010 model year tractor and engine without idle 

shutdown technology. Although the EPA and NHTSA standards are expressed differently

(grams of CO2 per ton-mile and gallons per 1,000 ton-mile respectively), the standards are 

equivalent.

In Phase 1, the agencies allowed manufacturers to certify certain types of combination 

tractors as vocational vehicles. These are tractors that do not typically operate at highway

speeds, or would otherwise not benefit from efficiency improvements designed for line-haul

tractors (although standards would still apply to the engines installed in these vehicles). The 

agencies created a subcategory of “vocational tractors,” or referred to as “special purpose 

tractors” in 40 CFR part 1037, because real world operation of these tractors is better represented 

by our Phase 1 vocational vehicle duty cycle than the tractor duty cycles. Vocational tractors are 

subject to the standards for vocational vehicles rather than the combination tractor standards. In 

addition, specific vocational tractors and heavy-duty vocational vehicles primarily designed to

 

117 Manufacturers may voluntarily opt-in to the NHTSA fuel consumption standards in model years 2014 or 2015. 

Once a manufacturer opts into the NHTSA program it must stay in the program for all optional MYs.
Page 161 of 850

perform work off-road or having tires installed with a maximum speed rating at or below 55 mph 

are exempted from the Phase 1 standards.

In Phase 1, the agencies also established separate performance standards for the engines 

manufactured for use in these tractors. EPA’s engine-based CO2 standards and NHTSA’s 

engine-based fuel consumption standards are being implemented using EPA’s existing test 

procedures and regulatory structure for criteria pollutant emissions from medium- and heavyduty engines. These engine standards vary depending on engine size linked to intended vehicle 

service class (which are the same service classes used for many years for EPA’s criteria pollutant 

standards). 

Manufacturers demonstrate compliance with the Phase 1 tractor standards using the GEM 

simulation tool. As explained in Section II above, GEM is a customized vehicle simulation 

model which is the preferred approach to demonstrating compliance testing for combination 

tractors rather than chassis dynamometer testing used in light-duty vehicle compliance. As 

discussed in the development of HD Phase 1 and recommended by the NAS 2010 study, a 

simulation tool is the preferred approach for HD tractor compliance because of the extremely 

large number of vehicle configurations.118 The GEM compliance tool was developed by EPA 

and is an accurate and cost-effective alternative to measuring emissions and fuel consumption 

while operating the vehicle on a chassis dynamometer. Instead of using a chassis dynamometer 

as an indirect way to evaluate real world operation and performance, various characteristics of 

the vehicle are measured and these measurements are used as inputs to the model. For HD Phase 

1, these characteristics relate to key technologies appropriate for this category of truck including 

aerodynamic features, weight reductions, tire rolling resistance, the presence of idle-reducing 

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

typical engine in compliance with the separate, applicable Phase 1 engine standard. Using these 

inputs, the model is used to quantify the overall performance of the vehicle in terms of CO2

emissions and fuel consumption. CO2 emission reduction and fuel consumption technologies not 

measured by the model must be evaluated separately, and the HD Phase 1 rules establish 

mechanisms allowing credit for such “off-cycle” technologies. 

In addition to the final Phase 1 tractor-based standards for CO2, EPA adopted 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 HFC leakage standard is 

independent of the CO2 tractor standard. Manufacturers can choose technologies from a menu of 

leak-reducing technologies sufficient to comply with the standard, as opposed to using a test to 

measure performance. 

The Phase 1 program also provided several flexibilities to advance the goals of the 

overall program while providing alternative pathways to achieve compliance. The primary

 

118 National Academy of Science. “Technologies and Approaches to Reducing the Fuel Consumption of Mediumand Heavy-Duty Vehicles.” 2010. Recommendation 8-4 stated “Simulation modeling should be used with 

component test data and additional tested inputs from powertrain tests, which could lower the cost and 

administrative burden yet achieve the needed accuracy of results.”
Page 162 of 850

flexibility is the averaging, banking, and trading program which allows emissions and fuel 

consumption credits to be averaged within an averaging set, banked for up to five years, or 

traded among manufacturers. Manufacturers with credit deficits were allowed to carry-forward 

credit deficits for up to three model years, similar to the LD GHG and CAFE carry-back credits. 

Phase 1 also included several interim provisions, such as incentives for advanced technologies 

and provisions to obtain credits for innovative technologies (called off-cycle in the Phase 2 

program) not accounted for by the HD Phase 1 version of GEM or for certifying early.

B. Overview of the Proposed Phase 2 Tractor Program

The proposed HD Phase 2 program is similar in many respects to the Phase 1 approach. 

The agencies are proposing to maintain the Phase 1 attribute-based regulatory structure in terms 

of dividing the tractor category into the same nine subcategories based on the tractor’s GVWR, 

cab configuration, and roof height. This structure is working well in the implementation of 

Phase 1. The one area where the agencies are proposing to change the regulatory structure is 

related to heavy-haul tractors. As noted above, the Phase 1 regulations include a set of 

provisions that allow vocational tractors to be treated as vocational vehicles. However, because 

the agencies propose to include the powertrain as part of the technology basis for the tractor and 

vocational vehicle standards in Phase 2, we are proposing to classify a certain set of these 

vocational tractors as heavy-haul tractors and subject them to a separate tractor standard that 

reflects their unique powertrain requirements and limitations in application of technologies to 

reduce fuel consumption and CO2 emissions.119

The agencies propose to also retain much of the certification and compliance structure 

developed in Phase 1 but to simplify end of the year reporting. The agencies propose that the 

Phase 2 tractor CO2 emissions and fuel consumption standards, as in Phase 1, be aligned.120 The 

agencies also propose to continue to have separate engine and vehicle standards to drive 

technology improvements in both areas. The reasoning behind the proposal to maintain separate 

standards is discussed above in Section II.B.2. As in Phase 1, the agencies propose to certify

tractors using the GEM simulation tool and to require manufacturers to evaluate the performance 

of subsystems through testing (the results of this testing to be used as inputs to the GEM 

simulation tool). Other aspects of the proposed HD Phase 2 certification and compliance 

program also mirror the Phase 1 program, such as maintaining a single reporting structure to 

satisfy both agencies, requiring limited data at the beginning of the model year for certification, 

and determining compliance based on end of year reports. In the Phase 1 program, 

manufacturers participating in the ABT program provided 90 day and 270 day reports after the 

end of the model year. The agencies required two reports for the initial program to help 

manufacturers become familiar with the reporting process. For the Phase 2 program, the 

 

119 See 76 FR 57138 for Phase 1 discussion. See 40 CFR 1037.801 for proposed Phase 2 heavy-haul tractor 

regulatory definition.

120 Fuel consumption is calculated from CO2 using the conversion factor of 10,180 grams of CO2 per gallon for 

diesel fuel.
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agencies propose that manufacturers would only be required to submit one end of the year report, 

which would simplify reporting. 

Even though many aspects of the proposed HD Phase 2 program are similar to Phase 1, 

there are some key differences. While Phase 1 focused on reducing CO2 emissions and fuel 

consumption in tractors through the application of existing (“off-the-shelf”) technologies, the 

proposed HD Phase 2 standards seek additional reductions through increased use of existing 

technologies and the development and deployment of more advanced technologies. To evaluate 

the effectiveness of a more comprehensive set of technologies, the agencies propose several 

additional inputs to GEM. The proposed set of inputs includes the Phase 1 inputs plus 

parameters to assess the performance of the engine, transmission, and driveline. Specific inputs 

for, among others, predictive cruise control, automatic tire inflation systems, and 6x2 axles 

would now be required. Manufacturers would conduct component testing to obtain the values 

for these technologies (should they choose to use them), which testing values would then be 

input into the GEM simulation tool. See Section III.D.2 below. To effectively assess 

performance of the technologies, the agencies also propose to change some aspects of the drive 

cycle used in certification through the addition of road grade. To reflect the existing trailer 

market, the agencies are proposing to refine the aerodynamic test procedure for high roof cabs by

adding some aerodynamic improving devices to the reference trailer (used for determining the 

relative aerodynamic performance of the tractor). The agencies also propose to change the 

aerodynamic certification test procedure to capture aerodynamic improvement of trailers and the 

impact of wind on tractor aerodynamic performance. The agencies are also proposing to change 

some of the interim provisions developed in Phase 1 to reflect the maturity of the program and 

reduced need and justification for some of the Phase 1 flexibilities. Further discussions on all of 

these matters are covered in the following sections.

C. Proposed Phase 2 Tractor Standards

EPA is proposing CO2 standards and NHTSA is proposing fuel consumption standards 

for new Class 7 and 8 combination tractors. In addition, EPA is proposing to maintain the HFC 

standards for the air conditioning systems that were adopted in Phase 1. EPA is also seeking 

comment on new standards to further control emissions of particulate matter (PM) from auxiliary

power units (APU) installed in tractors that would prevent an unintended consequence of 

increasing PM emissions from tractors during long duration idling. 

This section describes in detail the proposed standards. In addition to describing the 

proposed alternative (“Alternative 3”), in Section III.D.2.f we also detail another alternative 

(“Alternative 4”). Alternative 4 provides less lead time than the proposed set of standards but 

may provide more net benefits in the form of greater emission and fuel consumption reductions 

(with somewhat higher costs) in the early years of the program. The agencies believe Alternative 

4 has the potential to be maximum feasible and appropriate as discussed later in this section. 

The agencies welcome comment on all aspects of the proposed standards and the 

alternative standards described in Section III.D.2.f. Commenters are encouraged to address all 

aspects of feasibility analysis, including costs, the likelihood of developing the technology to 

achieve sufficient relaibility within the proposed and alternative lead-times, and the extent to 
Page 164 of 850

which the market could utilize the technology. It would be helpful if comments addressed these 

issues separately for each type of technology. 

(1) Proposed Fuel Consumption and CO2 Standards

The proposed fuel consumption and CO2 standards for the tractor cab are shown below in 

Table III-1. These proposed standards would achieve reductions of up to 24 percent compared to 

the 2017 model year baseline level when fully phased in beginning in the 2027 MY.121 The 

proposed standards for Class 7 are described as “Day Cabs” because we are not aware of any

Class 7 sleeper cabs in the market today; however, the agencies propose to require any Class 7 

tractor, regardless of cab configuration, meet the standards described as “Class 7 Day Cab.” We 

welcome comment on this proposed approach.

The agencies' analyses, as discussed briefly below and in more detail later in this 

preamble and in the draft RIA Chapter 2, indicate that these proposed standards, if finalized,

would be maximum feasible (within the meaning of 49 USC Section 32902 (k)) and would be

appropriate under each agency’s respective statutory authorities. The agencies solicit comment 

on all aspects of these analyses.

 

121 Since the HD Phase 1 tractor standards fully phase-in by the MY 2017, this is the logical baseline year. 
Page 165 of 850

Table III-1 Proposed Phase 2 Heavy-Duty Combination Tractor EPA Emissions Standards (g CO2/ton-mile) 

and NHTSA Fuel Consumption Standards (gal/1,000 ton-mile)

2021 Model Year CO2 Grams per Ton-Mile

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 97 78 70

Mid Roof 107 84 78

High Roof 109 86 77

2021 Model Year Gallons of Fuel per 1,000 Ton-Mile

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 9.5285 7.5639 6.8762

Mid Roof 10.5108 8.2515 7.6621

High Roof 10.7073 8.4479 7.5639

2024 Model Year CO2 Grams per Ton-Mile

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 90 72 64

Mid Roof 100 78 71

High Roof 101 79 70

2024 Model Year and Later Gallons of Fuel per 1,000 Ton-Mile

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 8.8409 7.0727 6.2868

Mid Roof 9.8232 7.5639 6.9745

High Roof 9.9214 7.7603 6.8762

2027 Model Year CO2 Grams per Ton-Mile

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 87 70 62

Mid Roof 96 76 69

High Roof 96 76 67

2027 Model Year and Later Gallons of Fuel per 1,000 Ton-Mile

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 8.5462 6.8762 6.0904

Mid Roof 9.4303 7.4656 6.7780

High Roof 9.4303 7.4656 6.5815

It should be noted that the proposed HD Phase 2 CO2 and fuel consumptions standards 

are not directly comparable to the Phase 1 standards. This is because the agencies are proposing 

several test procedure changes to more accurately reflect real world operation of tractors. These 

changes will result in the following differences. First, the same vehicle evaluated using the
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proposed HD Phase 2 version of GEM will obtain higher (i.e. less favorable) CO2 and fuel 

consumption values because the Phase 2 drive cycles include road grade. Road grade, which (of 

course) exists in the real-world, requires the engine to operate at higher horsepower levels to 

maintain speed while climbing a hill. Even though the engine saves fuel on a downhill section, 

the overall impact increases CO2 emissions and fuel consumption. The second of the key

differences between the CO2 and fuel consumption values in Phase 1 and Phase 2 is due to 

proposed changes in the evaluation of aerodynamics. In the real world, vehicles are exposed to 

wind which increases the drag of the vehicle and in turn increases the power required to move 

the vehicle down the road. To more appropriately reflect the in-use aerodynamic performance of 

tractor-trailers, the agencies are proposing to input into Phase 2 GEM the wind averaged 

coefficient of drag instead of the no-wind (zero yaw) value used in Phase 1. The final key

difference between Phase 1 and the proposed Phase 2 program includes a more realistic and 

improved simulation of the transmission in GEM, which could increase CO2 and fuel 

consumption relative to Phase 1.

The agencies are proposing Phase 2 CO2 emissions and fuel consumption standards for 

the combination tractors that reflect reductions that can be achieved through improvements in the 

tractor’s powertrain, aerodynamics, tires, and other vehicle systems. The agencies have analyzed 

the feasibility of achieving the proposed CO2 and fuel consumption standards, and have 

identified means of achieving the proposed 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 proposed standards in Section III.D.2. In developing the proposed

standards for Class 7 and 8 tractors, the agencies have evaluated the following: 

 the current levels of emissions and fuel consumption

 the kinds of technologies that could be utilized by tractor 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

 the magnitude of the CO2 and fuel savings that may be achieved

The technologies on whose performance the proposed tractor standards are predicated 

include: improvements in the engine, transmission, driveline, aerodynamic design, tire rolling 

resistance, other accessories of the tractor, and extended idle reduction technologies. These 

technologies, and other accessories of the tractor, are described in draft RIA Chapter 2.4. The 

agencies’ evaluation shows that some of these technologies are available today, but have very

low adoption rates on current vehicles, while others will require some lead time for development. 

EPA and NHTSA also present the estimated costs and benefits of the proposed Class 7 and 8 

combination tractor standards in draft RIA Chapter 2.8 and 2.12, explaining as well the basis for 

the agencies’ proposed stringency level.

As explained below in Section III.D, EPA and NHTSA have determined that there would 

be sufficient lead time to introduce various tractor and engine technologies into the fleet starting 
Page 167 of 850

in the 2021 model year and fully phasing in by the 2027 model year. This is consistent with 

NHTSA’s statutory requirement to provide four full model years of regulatory lead time for 

standards. As was adopted in Phase 1, the agencies are proposing for Phase 2 that manufacturers 

may generate and use credits from Class 7 and 8 combination tractors to show compliance with 

the standards. This is discussed further in Section III.F.

Based on our analysis, the 2027 model year standards for combination tractors and 

engines represent up to a 24 percent reduction in CO2 emissions and fuel consumption over a 

2017 model year baseline tractor, as detailed in Section III.D.2. In considering the feasibility of 

vehicles to comply with the proposed standards over their useful lives, EPA also considered the 

potential for CO2 emissions to increase during the regulatory useful life of the product. As we 

discuss in Phase 1 and separately in the context of deterioration factor (DF) testing, we have 

concluded that CO2 emissions are likely to stay the same or actually decrease in-use compared to 

new certified configurations. In general, engine and vehicle friction decreases as products wear,

leading to reduced parasitic losses and consequent lower CO2 emissions. Similarly, tire rolling 

resistance falls as tires wear due to the reduction in tread height. In the case of aerodynamic 

components, we project no change in performance through the regulatory life of the vehicle since 

there is essentially no change in their physical form as vehicles age. Similarly, weight reduction 

elements such as aluminum wheels are (evidently) not projected to increase in mass through 

time, and hence, we can conclude will not deteriorate with regard to CO2 performance in-use. 

Given all of these considerations, the agencies are confident in projecting that the tractor 

standards being proposed today would be technically feasible throughout the regulatory useful 

life of the program.

(2) Proposed Non-CO2 GHG Standards for Tractors 

EPA is also proposing standards to control non-CO2 GHG emissions from Class 7 and 8 

combination tractors.

(a) N2O and CH4 Emissions

The proposed heavy-duty engine standards for both N2O and CH4 as well as details of the 

proposed standards are included in the discussion in Section II.D.3 and II.D.4. No additional 

controls for N2O or CH4 emissions beyond those in the proposed HD Phase 2 engine standards 

are being considered for the tractor category.

(b) HFC Emissions

Manufacturers can reduce hydrofluorocarbon (HFC) emissions from air conditioning 

(A/C) leakage emissions in two ways. First, they can utilize leak-tight A/C system 

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, to replace the commonly used R-134a refrigerant. EPA proposes to address 

HFC emissions by maintaining the A/C leakage standards adopted in HD Phase 1 (see 40 CFR 

1037.115(c)). EPA believes the Phase 1 use of leak-tight components is at an appropriate level 

of stringency while maintaining the flexibility to produce the wide variety of A/C system 

configurations required in the tractor category. In addition, there currently are not any low GWP 

refrigerants approved for the heavy-duty vehicle sector. Without an alternative refrigerant 
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approved for this sector, it is challenging to demonstrate feasibility to reduce the amount of 

leakage allowed under the HFC leakage standard. Please see Section I.F(1)(b) for a discussion 

related to alternative refrigerants.

(3) PM Emissions from APUs

Auxiliary power units (APUs) can be used in lieu of operating the main engine during 

extended idle operations to provide climate control and power to the driver. APUs can reduce 

fuel consumption, NOX, HC, CH4, and CO2 emissions when compared to main engine idling.122 

However, a potential unintended consequence of reducing CO2 emissions from combination 

tractors through the use of APUs during extended idle operation is an increase in PM emissions. 

Therefore, EPA is seeking comment on the need and appropriateness to further reduce PM 

emissions from APUs. 

EPA conducted an analysis evaluating the potential impact on PM emissions due to an 

increase in APU adoption rates using MOVES. In this analysis, EPA assumed that these APUs 

emit criteria pollutants at the level of the EPA standard for this type of non-road diesel engines. 

Under this assumption, an APU would emit 1.8 grams PM per hour, assuming an extended idle 

load demand of 4.5 kW (6 hp).123 However, a 2010 model year or newer tractor that uses its 

main engine to idle emits approximately 0.35 grams PM per hour.124 The results from these 

MOVES runs are shown below in Table III-2. These results show that an increase in use of 

APUs could lead to an overall increase in PM emissions if left uncontrolled. Column three 

labeled “Proposed Program PM2.5 Emission Impact without Further PM Control (tons)” shows 

the incremental increase in PM2.5 without further regulation of APU PM2.5 emissions.

Table III-2 Projected Impact of Increased Adoption of APUs in Phase 2

CY Baseline HD 

Vehicle PM2.5 

Emissions (tons)

Proposed Program PM2.5 

a

Emission Impact without 

Further PM Control (tons)

2035 21,452 1,631

2050 24,675 2,257

Note:

a

Positive numbers mean emissions would increase from baseline to control 

case. PM2.5 from tire wear and brake wear are included. 

 

122 U.S. EPA. Development of Emission Rates for Heavy-Duty Vehicles in the Motor Vehicle Emissions Simulator 

MOVES 2010. EPA-420-B-12-049. August 2012. 

123 Tier 4, less-than-8 kW nonroad compression-ignition engine exhaust emissions standards assumed for APUs: 

http://www.epa.gov/otaq/standards/nonroad/nonroadci.htm

124 U.S. EPA. MOVES2014 Reports. Last accessed on May 1, 2015 at 

http://www.epa.gov/otaq/models/moves/moves-reports.htm.
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Since January 1, 2008, California ARB has prohibited the idling of sleeper cab tractors 

during periods of sleep and rest.125 The regulations apply additional requirements to dieselfueled APUs on tractors equipped with 2007 model year or newer engines. Truck owners in 

California must either: 1) fit the APU with an ARB verified Level 3 particulate control device 

that achieves 85 percent reduction in particulate matter; or 2) have the APU exhaust plumbed 

into the vehicle’s exhaust system upstream of the particulate matter aftertreatment device.126 

Currently ARB includes four control devices that have been verified to meet the Level 3 PM 

requirements. These devices include HUSS Umwelttechnik GmbH’s FS-MK Series Diesel 

Particulate filters, Impco Ecotrans Technologies’ ClearSky Diesel Particulate Filter, Thermo 

King’s Electric Regenerative Diesel Particulate Filter, and Proventia’s Electronically Heated 

Diesel Particulate Filter. In addition, ARB has approved a Cummins integrated diesel-fueled 

APU and several fuel-fired heaters produced by Espar and Webasto.

EPA conducted an evaluation of the impact of potentially requiring further PM control 

from APUs nationwide. As shown in Table III-2, EPA projects that the HD Phase 2 program as 

proposed (without additional PM controls) would increase PM2.5 emissions by 1,631 tons in 2035 

and 2,257 tons in 2050. The annual impact of a program to further control PM could lead to a 

reduction of PM2.5 emissions nationwide by 3,084 tons in 2035 and by 4,344 tons in 2050, as 

shown in Table III-3 the column labeled “Net Impact on National PM2.5 Emission with Further 

PM Control of APUs (tons).” 

Table III-3 Projected Impact of Further Control on PM2.5 Emissions a

CY Baseline 

National HeavyDuty Vehicle 

PM2.5 

Emissions (tons)

Proposed HD Phase 

2 Program National 

PM2.5 Emissions 

without Further PM 

Control (tons)

Proposed HD Phase 

2 Program National 

PM2.5 Emissions with

Further PM Control

(tons)

Net Impact on 

National PM2.5 

Emission with 

Further PM Control

of APUs (tons)

2035 21,452 23,083 19,999 -3,084

2050 24,675 26,932 22,588 -4,344

Note:

a

PM2.5 from tire wear and brake wear are included. 

EPA developed long-term cost projections for catalyzed diesel particulate filters (DPF) as 

part of the Nonroad Diesel Tier 4 rulemaking. In that rulemaking, EPA estimated the DPF costs 

would add $580 to the cost of 150 horsepower engines (69 FR 39126, June 29, 2004). On the 

other hand, ARB estimated the cost of retrofitting a diesel powered APU with a PM trap to be 

 

125 California Air Resources Board. Idle Reduction Technologies for Sleeper Berth Trucks. Last viewed on 

September 19, 2014 at http://www.arb.ca.gov/msprog/cabcomfort/cabcomfort.htm

126 California Air Resources Board. §2485(c)(3)(A)(1)
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$2,000 in 2005.127 The costs of a DPF for an APU that provides less than 25 horsepower would 

be less than the projected cost of a 150 HP engine because the filter volume is in general 

proportional to the engine-out emissions and exhaust flow rate. Proventia is charging customers 

$2,240 for electronically heated DPF.128 EPA welcomes comments on cost estimates associated 

with DPF systems for APUs.

EPA requests comments on the technical feasibility of diesel particulate filters ability to 

reduce PM emissions by 85 percent from non-road engines used to power APUs. EPA also 

requests comments on whether the technology costs outlined above are accurate, and if so, if 

projected reductions are appropriate taking into account cost, noise, safety, and energy factors. 

See CAA section 213(a)(4).

(4) Proposed Exclusions from the Phase 2 Tractor Standards

As noted above, in Phase 1, the agencies adopted provisions to allow tractor 

manufacturers to reclassify certain tractors as vocational vehicles.129 The agencies propose in 

Phase 2 to continue to allow manufacturers to exclude certain vocational-types of tractors from 

the combination tractor standards and instead be subject to the vocational vehicle standards. 

However, the agencies propose to set unique standards for tractors used in heavy haul 

applications in Phase 2. Details regarding the proposed heavy-haul standards are included below 

in Section II.D.3.

During the development of Phase 1, the agencies received multiple comments from 

several stakeholders supporting an approach for an alternative treatment of a subset of tractors 

because they were designed to operate at lower speeds, in stop and go traffic, and sometimes 

operate at higher weights than the typical line-haul tractor. These types of applications have 

limited potential for improvements in aerodynamic performance to reduce CO2 emissions and 

fuel consumption. Consistent with the agencies’ approach in Phase 1, the agencies agree that 

these vocational tractors are operated differently than line-haul tractors and therefore fit more 

appropriately into the vocational vehicle category. However, we need to continue to ensure that 

only tractors that are truly vocational tractors are classified as such.130 A vehicle determined by 

the manufacturer to be a HHD vocational tractor would fall into one of the HHD vocational 

vehicle subcategories and be regulated as a vocational vehicle. Similarly, MHD tractors which 

the manufacturer chooses to reclassify as vocational tractors would be regulated as a MHD 

vocational vehicle. Specifically, the agencies are proposing to change the provisions in EPA’s 

 

127 California Air Resources Board. Staff Report: Initial Statement of Reasons; Notice of Public Hearing to 

Consider Requirements to Reduce Idling Emissions From New and In-Use Trucks, Beginning in 2008. September 

1, 2005. Page 38. Last viewed on October 20, 2014 at http://www.arb.ca.gov/regact/hdvidle/isor.pdf.

128 Proventia. Tripac Filter Kits. Last accessed on October 21, 2014 at 

http://www.proventiafilters.com/purchase.html

129 See 40 CFR 1037.630.

130 As a part of the end of the year compliance process, EPA and NHTSA verify manufacturer’s production reports 

to avoid any abuse of the vocational tractor allowance. 
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40 CFR 1037.630 and NHTSA’s regulation at 49 CFR 523.2 and only allow the following two

types of vocational tractors to be eligible for reclassification by the manufacturer:

(1) Low-roof tractors intended for intra-city pickup and delivery, such as those that 

deliver bottled beverages to retail stores.

(2) Tractors intended for off-road operation (including mixed service operation), such as

those with reinforced frames and increased ground clearance.131

Because the difference between some vocational tractors and line-haul tractors is 

potentially somewhat subjective, we are also proposing to continue to limit the use of this 

provision to a rolling three year sales limit of 21,000 vocational tractors per manufacturer 

consistent with past production volumes of such vehicles. We propose to carry-over the existing 

three year sales limit with the recognition that heavy-haul tractors would no longer be permitted 

to be treated as vocational vehicles (suggesting a lower volumetric cap could be appropriate) but 

that the heavy-duty market has improved since the development of the HD Phase 1 rule 

(suggesting the need for a higher sales cap). The agencies welcome comment on whether the 

proposed sales volume limit is set at an appropriate level looking into the future.

Also in Phase 1, EPA determined that manufacturers that met the small business criteria 

specified in 13 CFR 121.201 for “Heavy Duty Truck Manufacturing” were not subject to the 

greenhouse gas emissions standards of 40 CFR 1037.106.132 The regulations required that 

qualifying manufacturers must notify the Designated Compliance Officer each model year before 

introducing the vehicles into commerce. The manufacturers are also required to label the 

vehicles to identify them as excluded vehicles. EPA and NHTSA are seeking comments on 

eliminating this provision for tractor manufacturers in the Phase 2 program. The agencies are 

aware of two second stage manufacturers building custom sleeper cab tractors. We could treat 

these vehicles in one of two ways. First, the vehicles may be considered as dromedary vehicles 

and therefore treated as vocational vehicles.133 Or the agencies could provide provisions that 

stated if a manufacturer changed the cab, but not the frontal area of the vehicle, then it could 

retain the aerodynamic bin of the original tractor. We welcome comments on these 

considerations. 

EPA is proposing to not exempt glider kits from the Phase 2 GHG emission standards.134 

Gliders and glider kits are exempt from NHTSA’s Phase 1 fuel consumption standards. For EPA 

purposes, the CO2 provisions of Phase 1 exempted gliders and glider kits produced by small 

 

131 See existing 40 CFR 1037.630 (a)(1)(i)-(iii).

132 See 40 CFR 1037.150(c).

133 A dromedary is a box, deck, or plate mounted behind the tractor cab and forward of the fifth wheel on the frame 

of the power unit of a tractor-trailer combination to carry freight.

134 Glider vehicles are new vehicles produced to accept rebuilt engines (or other used engines) along with used axles 

and/or transmissions. The common commercial term “glider kit” is used here primarily to refer to an assemblage of 

parts into which the used/rebuilt engine is installed. 
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businesses but did not include such a blanket exemption for other glider kits.135 Thus, some 

gliders and glider kits are already subject to the requirement to obtain a vehicle certificate prior 

to introduction into commerce as a new vehicle. However, the agencies believe glider 

manufacturers may not understand how these regulations apply to them, resulting in a number of 

uncertified vehicles. 

EPA is concerned about adverse economic impacts on small businesses that assemble 

glider kits and glider vehicles. Therefore, EPA is proposing an option that would grandfather 

existing small businesses, but cap annual production based on their recent sales. EPA requests 

comment on whether any special provisions would be needed to accommodate glider kits. See 

Section XIV for additional discussion of the proposed requirements for glider vehicles.

Similarly, NHTSA is considering including glider vehicles under its Phase 2 program. 

The agencies request comment on their respective considerations. 

We believe that the agencies potentially having different policies for glider kits and glider 

vehicles under the Phase 2 program would not result in problematic disharmony between the 

NHTSA and EPA programs, because of the small number of vehicles that would be 

involved. EPA believes that its proposed changes would result in the glider market returning to 

the pre-2007 levels, in which fewer than 1,000 glider vehicles would be produced in most 

years. Given that a large fraction of these vehicles would be exempted from EPA regulations 

because they would be produced by qualifying small businesses, they would thus, in practice, be 

treated the same under EPA and NHTSA regulations. Only non-exempt glider vehicles would 

be subject to different requirements under the NHTSA and EPA regulations. However, we 

believe that this is unlikely to exceed a few hundred vehicles in any year, which would be few 

enough not to result in any meaningful disharmony between the two agencies.

With regard to NHTSA’s safety authority over gliders, the agency notes that it has 

become increasingly aware of potential noncompliance with its regulations applicable to 

gliders. NHTSA has learned of manufacturers who are creating glider vehicles that are new 

vehicles under 49 CFR 571.7(e); however, the manufacturers are not certifying them and 

obtaining a new VIN as required. NHTSA plans to pursue enforcement actions as applicable 

against noncompliant manufacturers. In addition to enforcement actions, NHTSA may consider 

amending 49 CFR 571.7(e) and related regulations as necessary. NHTSA believes 

manufacturers may not be using this regulation as originally intended.

(5) In-use Standards

Section 202(a)(1) of the CAA specifies that EPA is to propose emissions standards that 

are applicable for the useful life of the vehicle. The in-use Phase 2 standards that EPA is 

proposing would apply to individual vehicles and engines, just as EPA adopted for Phase 1. 

 

135 Rebuilt engines used in glider vehicles are subject to EPA criteria pollutant emission standards applicable for the 

model year of the engine. See 40 CFR 86.004-40 for requirements that apply for engine rebuilding. Under existing 

regulations, engines that remain in their certified configuration after rebuilding may continue to be used.
Page 173 of 850

NHTSA is also proposing the same approach used in Phase 1 which does not include in-use 

standards. 

EPA is also not proposing any changes to provisions requiring that the useful life for 

tractors with respect to CO2 emissions be equal to the respective useful life periods for criteria 

pollutants, as shown below in Table III-4. (See 40 CFR 1037.106(e)). EPA does not expect 

degradation of the technologies evaluated for Phase 2 in terms of CO2 emissions, therefore we 

propose no changes to the regulations describing compliance with GHG pollutants with regards 

to deterioration. (See 40 CFR 1037.241). We welcome comments that highlight a need to 

change this approach.

Table III-4 Tractor Useful Life Periods

Years Miles

Class 7 Tractors 10 185,000

Class 8 Tractors 10 435,000

D. Feasibility of the Proposed Tractor Standards

This section describes the agencies’ technical feasibility and cost analysis in greater 

detail. Further detail on all of these technologies can be found in the draft RIA Chapter 2.

Class 7 and 8 tractors are used in combination with trailers to transport freight. The 

variation in the design of these tractors and their typical uses drive different technology solutions 

for each regulatory subcategory. As noted above, the agencies are proposing to continue the 

Phase 1 provisions that treat vocational tractors as vocational vehicles instead of as combination 

tractors, as noted in Section III.C. The focus of this section is on the feasibility of the proposed 

standards for combination tractors including the heavy-haul tractors, but 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 Southwest Research Institute evaluation of heavy-duty vehicle 

fuel efficiency and costs for NHTSA,136 the Department of Energy’s SuperTruck Program,137

2010 National Academy of Sciences report of Technologies and Approaches to Reducing the 

Fuel Consumption of Medium- and Heavy-Duty Vehicles,138 TIAX’s assessment of 

 

136 Reinhart, T. (2015). Commercial Medium- and Heavy-Duty (MD/HD) Truck Fuel Efficiency Technology Study –

Report #1. Washington, DC: National Highway Traffic Safety Administration.

.

137 U.S. Department of Energy. SuperTruck Initiative. Information available at 

http://energy.gov/eere/vehicles/vehicle-technologies-office

138 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 
Page 174 of 850

technologies to support the NAS panel report,

139 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),140 and the technology cost analysis conducted by ICF for 

EPA.141 

(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 many technologies, including engine, drivetrain, aerodynamic, tire, extended idle, 

and weight reduction technologies. The agencies’ determination of the feasibility of the 

proposed HD Phase 2 standards is based on our projection of the use of these technologies and 

an assessment of their effectiveness. We will also discuss other technologies that could 

potentially be used, such as vehicle speed limiters, although we are not basing the proposed

standards on their use for the model years covered by this proposal, for various reasons discussed 

below. 

In this section we discuss generally the tractor and engine technologies that the agencies 

considered to improve performance of heavy-duty tractors, while Section III.D.2 discusses the 

baseline tractor definition and technology packages the agencies used to determine the proposed 

standard levels. 

Engine technologies: As discussed in Section II.D above, there are several engine 

technologies that can reduce fuel consumption of heavy-duty tractors. These technologies 

include friction reduction, combustion system optimization, and Rankine cycle. These engine 

technologies would impact the Phase 2 vehicle results because the agencies propose that the 

manufacturers enter a fuel map into GEM. 

Aerodynamic technologies: There are opportunities to reduce aerodynamic drag from the 

tractor, but it is sometimes 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 

 

of Medium- and Heavy-Duty Vehicles. (“The 2010 NAS Report”) Washington, D.C., The National Academies 

Press. 

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

to National Academy of Sciences, November 19, 2009.

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

Truck Fuel Consumption and CO2 Emissions. October 2009.

141 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. 
Page 175 of 850

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. DOE has partnered 

with the heavy-duty industry to demonstrate vehicles that achieve a 50 percent improvement in 

freight efficiency. This SuperTruck program has led to significant advancements in the 

aerodynamics of combination tractor-trailers. The manufacturers’ SuperTruck demonstration 

vehicles are achieving approximately 7 percent freight efficiency improvements over a 2010 MY 

baseline vehicle due to improvements in tractor aerodynamics.142 The 2010 NAS Report on 

heavy-duty trucks found 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.143 

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. Since 2007, SmartWay designated tractors have had 

steer tires with rolling resistance coefficients of less than 6.6 kg/metric ton for the steer tire and 

less than 7.0 kg/metric ton for the drive tire.144 Low rolling resistance (LRR) drive tires are 

currently offered in both dual assembly and wide-based single configurations. Wide based single 

tires can offer rolling resistance reduction along with improved aerodynamics and weight 

reduction. The lowest rolling resistance value submitted for 2014MY GHG and fuel efficiency

certification was 4.3 and 5.0 kg/metric ton for the steer and drive tires respectively.

145

 

Weight Reduction: Reductions in vehicle mass lower fuel consumption and GHG 

emissions by decreasing the overall vehicle mass that is moved down the road. Weight 

reductions also increase vehicle payload capability which can allow additional tons to be carried 

by fewer trucks consuming less fuel and producing lower emissions on a ton-mile basis. We 

treated such weight reduction in two ways in Phase 1 to account for the fact that combination 

tractor-trailers weigh-out approximately one-third of the time and cube-out approximately twothirds of the time. Therefore in Phase 1 and also as proposed for Phase 2, one-third of the weight 

reduction would be added payload in the denominator while two-thirds of the weight reduction is 

subtracted from the overall weight of the vehicle in GEM. See 76 FR 57153.

In Phase 1, we reflected mass reductions for specific technology substitutions (e.g., 

installing aluminum wheels instead of steel wheels). These substitutions were included where we 

could with confidence verify the mass reduction information provided by the manufacturer. The 

agencies propose to expand the list of weight reduction components which can be input into 

GEM in order to provide the manufacturers with additional means to comply via GEM with the 

combination tractor standards and to further encourage reductions in vehicle weight. As in Phase 

1, we recognize that there may be additional potential for weight reduction in new high strength 

 

142 Daimler Truck North America. SuperTruck Program Vehicle Project Review. June 19, 2014. 

143 See TIAX, Note 139, Page 4-40.

144 Ibid.

145 Memo to Docket. Coefficient of Rolling Resistance Certification Data. See Docket EPA-HQ-OAR-2014-0827
Page 176 of 850

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.146 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. Additional weight reduction 

would be evaluated as a potential off-cycle credit.

Extended Idle Reduction: Auxiliary power units (APU), 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 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.147 EPA and NHTSA agree with the TIAX assessment that a 5

percent reduction in overall fuel consumption reduction is achievable.

148

 

Idle Reduction: Day cab tractors often idle while cargo is loaded or unloaded, as well as 

during the frequent stops that are inherent with driving in urban traffic conditions near cargo 

destinations. To recognize idle reduction technologies that reduce workday idling, the agencies 

have developed a new idle-only duty cycle that is proposed to be used in GEM. As discussed 

above in Section II.D, this new proposed certification test cycle would measure the amount of 

fuel saved and CO2 emissions reduced by two primary types of technologies: neutral idle and 

stop-start. The proposed rules apply this test cycle only to vocational vehicles because these 

types of vehicles spend more time at idle than tractors. However, the agencies request comment 

on whether we should extend this vocational vehicle idle reduction approach to day cab tractors. 

Neutral idle would only be available for tractors using torque-converter automatic transmissions, 

and stop-start would be available for any tractor. Unlike the fixed numerical value in GEM for 

automatic engine shutdown systems to reduce overnight idling of combination tractors, this new 

idle reduction approach would result in different numerical values depending on user inputs. 

The required inputs and other details about this cycle, as it would apply to vocational vehicles, 

are described in the draft RIA Chapter 3. If we extended this approach to day cab tractors, we 

could set a fixed GEM composite cycle weighting factor at a value representative of the time 

spent at idle for a typical day cab tractor, possibly five percent. Under this approach, tractor 

manufacturers would be able to select GEM inputs that identify the presence of workday idle 

reduction technologies, and GEM would calculate the associated benefit due to these 

technologies, using this new idle-only cycle as described in the draft RIA Chapter 3.

The agencies have also received a letter from the California Air Resources Board 

requesting consideration of credits for reducing solar loads. Solar reflective paints and solar 

 

146 American Iron and Steel Institute. “A Cost Benefit Analysis Report to the North American Steel Industry on 

Improved Material and Powertrain Architectures for 21st Century Trucks. “

147 See the draft RIA Chapter 2.4.8 for details.

148 See the 2010 NAS Report, Note 138, above, at 128.
Page 177 of 850

control glazing technologies are briefly discussed in draft RIA Chapter 2.4.9.3. The agencies 

request comment on the Air Resources Board’s letter and recommendations.149

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 another technology option for compliance that is already utilized today by

some fleets (though the typical maximum speed setting is often higher than 65 mph). 

Downsized Engines and Downspeeding: As tractor manufacturers continue to reduce the 

losses due to vehicle loads, such as aerodynamic drag and rolling resistance, the amount of 

power required to move the vehicle decreases. In addition, engine manufacturers continue to 

improve the power density of heavy-duty engines through means such as reducing the engine 

friction due to smaller surface area. These two changes lead to the ability for truck purchasers to 

select lower displacement engines while maintaining the previous level of performance. Engine 

downsizing could be more effective if it is combined with the downspeeding assuming increased 

BMEP does not affect durability. The increased efficiency of the vehicle moves the operating 

points down to a lower load zone on a fuel map, which often moves the engine away from its 

sweet spot to a less efficient zone. In order to compensate for this loss, downspeeding allows the 

engine to run at a lower engine speed and move back to higher load zones, thus can slightly 

improve fuel efficiency. Reducing the engine size allows the vehicle operating points to move 

back to the sweet spot, thus further improving fuel efficiency. Engine downsizing can be 

accounted for as a vehicle technology through the use of the engine’s fuel map in GEM.

Transmission: As discussed in the 2010 NAS report, automatic (AT) and automated 

manual transmissions (AMT) may offer the ability to improve vehicle fuel consumption by

optimizing gear selection compared to an average driver.150 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.151 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 neither an automatic nor 

automated manual transmission can anticipate. However, poorly-trained 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. As transmissions continue to evolve, we are 

now seeing in the European heavy-duty vehicle market the addition of dual clutch transmissions 

 

149 California Air Resources Board. Letter from Michael Carter to Matthew Spears dated December 3, 2014. Solar 

Control: Heavy-Duty Vehicles White Paper. Docket EPA-HA-OAR-2014-0827.

150 Manual transmissions require the driver to shift the gears and manually engage and disengage the clutch. 

Automatic transmissions shift gears through computer controls and typically include a torque converter. An AMT 

operates similar to a manual transmission, except that an automated clutch actuator disengages and engages the 

drivetrain instead of a human driver. An AMT does not include a clutch pedal controllable by the driver or a torque 

converter. 

151 See TIAX, Note 139, above at 4-70.
Page 178 of 850

(DCT). DCTs operate similar to AMTs, but with two clutches so that the transmission can 

maintain engine speed during a shift which improves fuel efficiency. We believe there may be 

real benefits in reduced fuel consumption and GHG emissions through the adoption of dual 

clutch, automatic or automated manual transmission technology. 

Low Friction Transmission, Axle, and Wheel Bearing Lubricants: The 2010 NAS report 

assessed low friction lubricants for the drivetrain as providing a 1 percent improvement in fuel 

consumption based on fleet testing.152 A field trial of European medium-duty trucks found an 

average fuel consumption improvement of 1.8 percent using SAE 5W-30 engine oil, SAE 

75W90 axle oil and SAE 75W80 transmission oil when compared to SAE 15W40 engine oil and 

SAE 90W axle oil, and SAE 80W transmission oil.153 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. 

Drivetrain: Most tractors today have three axles – a steer axle and two rear drive axles, 

and are commonly referred to as 6x4 tractors. Manufacturers offer 6x2 tractors that include one 

rear drive axle and one rear non-driving axle. The 6x2 tractors offer three distinct benefits. 

First, the non-driving rear axle does not have internal friction and therefore reduces the overall 

parasitic losses in the drivetrain. In addition, the 6x2 configuration typically weighs 

approximately 300 to 400 pounds less than a 6x4 configuration.154 Finally, the 6x2 typically

costs less or is cost neutral when compared to a 6x4 tractor. Sources cite the effectiveness of 6x2 

axles at between 1 and 3 percent.155 Similarly, with the increased use of double and triple 

trailers, which reduce the weight on the tractor axles when compared to a single trailer, 

manufacturers offer 4x2 axle configurations. The 4x2 axle configuration would have as good as 

or better fuel efficiency performance than a 6x2.

Accessory Improvements: Parasitic losses from the engine come from many systems, 

including the water pump, oil pump, and power steering pump. Reductions in parasitic losses are 

one of the areas being developed under the DOE SuperTruck program. As presented in the DOE 

Merit reviews, Navistar stated that they demonstrated a 0.45 percent reduction in fuel 

consumption through water pump improvements and 0.3 percent through oil pump 

improvements compared to a current engine. In addition, Navistar showed a 0.9 percent benefit 

for a variable speed water pump and variable displacement oil pump. Detroit Diesel reports a 0.5 

percent coming from improved water pump efficiency.

156

 It should be noted that water pump 

improvements include both pump efficiency improvement and variable speed or on/off controls. 

 

152 See the 2010 NAS Report, Note 138, page 67.

153 Green, D.A., et. al. “The Effect of Engine, Axle, and Transmission Lubricant, and Operating Conditions on 

Heavy Duty Diesel Fuel Economy. Part 1: Measurements.” SAE 2011-01-2129. SAE International Journal of Fuels 

and Lubricants. January 2012.

154 North American Council for Freight Efficiency. ”Confidence Findings on the Potential of 6x2 Axles.” 2014. 

Page 16.

155 Reinhart, T. (2015). Commercial Medium- and Heavy-Duty (MD/HD) Truck Fuel Efficiency Technology Study –

Report #1. Washington, DC: National Highway Traffic Safety Administration.

156 See the draft RIA Chapter 2.4 for details.
Page 179 of 850

Lube pump improvements are primarily achieved using variable displacement pumps and may

also include efficiency improvement. All of these results shown in this paragraph are

demonstrated through the DOE SuperTruck program at single operating point on the engine map, 

and therefore the overall expected reduction of these technologies is less than the single point 

result.

Intelligent Controls: Skilled drivers know how to control a vehicle to obtain maximum 

fuel efficiency by, among other things, considering road terrain. For example, the driver may

allow the vehicle to slow down below the target speed on an uphill and allow it to go over the 

target speed when going downhill, to essentially smooth out the engine demand. Electronic 

controls can be developed to essentially mimic this activity. The agencies propose to provide a 2 

percent reduction in fuel consumption and CO2 emissions for vehicles configured with intelligent 

controls, such as predictive cruise control.

Automatic Tire Inflation Systems: Proper tire inflation is critical to maintaining proper 

stress distribution in the tire, which reduces heat loss and rolling resistance. Tires with reduced 

inflation pressure exhibit a larger footprint on the road, more sidewall flexing and tread shearing, 

and therefore, have greater rolling resistance than a tire operating at its optimal inflation 

pressure. Bridgestone tested the effect of inflation pressure and found a 2 percent variation in 

fuel consumption over a 40 psi range.157 Generally, a 10 psi reduction in overall tire inflation 

results in about a 1 percent reduction in fuel economy.

158

 To achieve the intended fuel efficiency

benefits of low rolling resistance tires, it is critical that tires are maintained at the proper inflation 

pressure. 

Proper tire inflation pressure can be maintained with a rigorous tire inspection and 

maintenance program or with the use of tire pressure and inflation systems. According to a study 

conducted by FMCSA in 2003, about 1 in 5 tractors/trucks is operating with 1 or more tires 

underinflated by at least 20 psi.159 A 2011 FMCSA study estimated underinflation accounts for 

one service call per year and increases tire procurement costs 10 to 13 percent. The study found 

that total operating costs can increase by $600 to $800 per year due to underinflation. 160 A 

recent study by The North American Council on Freight Efficiency, found that adoption of tire 

pressure monitoring systems is increasing. It also found that reliability and durability of 

commercially available tire pressure systems are good and early issues with the systems have 

 

157 Bridgestone Tires. Real Questions, Real Answers. 

http://www.bridgestonetrucktires.com/us_eng/real/magazines/ra_special-edit_4/ra_special4_fuel-tires.asp

158 “Factors Affecting Truck Fuel Economy,” Goodyear, Radial Truck and Retread Service Manual. Accessed 

February 16, 2010 at http://www.goodyear.com/truck/pdf/radialretserv/Retread_S9_V.pdf. 

159 American Trucking Association. Tire Pressure Monitoring and Inflation Maintenance. June 2010. Page 3. Last 

accessed on December 15, 2014 at 

http://www.trucking.org/ATA%20Docs/About/Organization/TMC/Documents/Position%20Papers/Study%20Group

%20Information%20Reports/Tire%20Pressure%20Monitoring%20and%20Inflation%20Maintenance%E2%80%94

TMC%20I.R.%202010-2.pdf 

160 TMC Future Truck Committee Presentation “FMCSA Tire Pressure Monitoring Field Operational Test Results,” 

February 8, 2011
Page 180 of 850

been addressed. 161 These automatic tire inflation systems monitor tire pressure and also 

automatically keep tires inflated to a specific level. The agencies propose to provide a 1 percent 

CO2 and fuel consumption reduction value for tractors with automatic tire inflation systems 

installed. 

Tire pressure monitoring systems notify the operator of tire pressure, but require the 

operator to manually inflate the tires to the optimum pressure. Because of the dependence on the 

operator’s action, the agencies are not proposing to provide a reduction value for tire pressure 

monitoring systems. We request comment on this approach and seek data from those that 

support a reduction value be assigned to tire pressure monitoring systems.

Hybrid: Hybrid powertrain development in Class 7 and 8 tractors has been limited to a 

few manufacturer demonstration vehicles to date. One of the key benefit opportunities for fuel 

consumption reduction with hybrids is less fuel consumption when a vehicle is idling, but the 

standard is already premised on use of extended idle reduction so use of hybrid technology 

would duplicate many of the same emission reductions attributable to extended idle reduction. 

NAS estimated that hybrid systems would cost approximately $25,000 per tractor in the 2015 

through the 2020 time frame and provide a potential fuel consumption reduction of 10 percent, of 

which 6 percent is idle reduction which can be achieved (less expensively) through the use of 

other idle reduction technologies.162 The limited reduction potential outside of idle reduction for 

Class 8 sleeper cab tractors is due to the mostly highway operation and limited start-stop 

operation. Due to the high cost and limited benefit during the model years at issue in this action 

(as well as issues regarding sufficiency of lead time (see Section III.D.2 below), the agencies are 

not including hybrids in assessing standard stringency (or as an input to GEM). 

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 draft 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. 

(2) Projected Technology Effectiveness and Cost

EPA and NHTSA project that CO2 emissions and fuel consumption reductions can be 

feasibly and cost-effectively met through technological improvements in several areas. The 

agencies evaluated each technology and estimated the most appropriate adoption rate of 

technology into each tractor subcategory. The next sections describe the baseline vehicle 

configuration, the effectiveness of the individual technologies, the costs of the technologies, the 

projected adoption rates of the technologies into the regulatory subcategories, and finally the 

derivation of the proposed standards.

 

161 North American Council for Freight Efficiency, “Tire Pressure Systems,” 2013.

162 See the 2010 NAS Report, Note 138, page 128.
Page 181 of 850

The agencies propose Phase 2 standards that project by 2027, all high-roof tractors would 

have aerodynamic performance equal to or better today’s SmartWay performance – which 

represents the best of today’s technology. This would equate to having 40 percent of new high 

roof sleeper cabs in 2027 complying with the current best practices and 60 percent of the new 

high-roof sleeper cab tractors sold in 2027 having better aerodynamic performance than the best 

tractors available today. For tire rolling resistance, we premised the proposed standards on the 

assumption that nearly all tires in 2027 would have rolling resistance equal to or superior to tires 

meeting today’s SmartWay designation. As discussed in Section II.D, the agencies assume the 

proposed 2027 MY engines would achieve an additional 4 percent improvement over Phase 1 

engines and we project would include 15 percent of waste heat recovery (WHR) and many other 

advanced engine technologies. In addition, we are proposing standards that project 

improvements to nearly all of today’s transmissions, incorporation of extended idle reduction 

technologies on 90 percent of sleeper cabs, and significant adoption of other types of 

technologies such as predictive cruise control and automatic tire inflation systems. 

In addition to the high cost and limited utility of hybrids for many tractor drive cycles 

noted above, the agencies believe that hybrid powertrains systems for tractors may not be 

sufficiently developed and the necessary manufacturing capacity put in place to base a standard 

on any significant volume of hybrid tractors. Unlike hybrids for vocational vehicles and lightduty vehicles, the agencies are not aware of any full hybrid systems currently developed for long 

haul tractor applications. To date, hybrid systems for tractors have been primarily focused on 

idle shutdown technologies and not on the broader energy storage and recovery systems 

necessary to achieve reductions over typical vehicle drive cycles. The proposed standards reflect 

the potential for idle shutdown technologies through GEM. Further as highlighted by the 2010 

NAS report, the agencies do believe that full hybrid powertrains may have the potential in the 

longer term to provide significant improvements in tractor fuel efficiency and to greenhouse gas 

emission reductions. However, due to the high cost, limited benefit during highway driving, and

lacking any existing systems or manufacturing base, we cannot conclude with certainty, absent 

additional information, that such technology would be available for tractors in the 2021-2027

timeframe. However the agencies welcome comment from industry and others on their projected 

timeline for deployment of hybrid powertrains for tractor applications. 

(a) Tractor Baselines for Costs and Effectiveness

The fuel efficiency and CO2 emissions of combination tractors vary depending on the 

configuration of the tractor. Many aspects of the tractor impact its performance, including the 

engine, transmission, drive axle, aerodynamics, and rolling resistance. For each subcategory, the 

agencies selected a theoretical tractor to represent the average 2017 model year tractor that meets 

the Phase 1 standards (see 76 FR 57212, September 15, 2011). These tractors are used as 

baselines from which to evaluate costs and effectiveness of additional technologies and 

standards. The specific attributes of each tractor subcategory are listed below in Table III-5. 

Using these values, the agencies assessed the CO2 emissions and fuel consumption performance 

of the proposed baseline tractors using the proposed version of Phase 2 GEM. The results of 

these simulations are shown below in Table III-6. 

As noted earlier, the Phase 1 2017 model year tractor standards and the baseline 2017 

model year tractor results are not directly comparable. The same set of aerodynamic and tire 
Page 182 of 850

rolling resistance technologies were used in both setting the Phase 1 standards and determining 

the baseline of the Phase 2 tractors. However, there are several aspects that differ. First, a new 

version of GEM was developed and validated to provide additional capabilities, including more 

refined modeling of transmissions and engines. Second, the determination of the proposed HD 

Phase 2 CdA value takes into account a revised test procedure, a new standard reference trailer, 

and wind averaged drag as discussed below in Section III.E. In addition, the proposed HD Phase 

2 version of GEM includes road grade in the 55 mph and 65 mph highway cycles, as discussed 

below in Section III.E. Finally, the agencies assessed the current level of automatic engine 

shutdown and idle reduction technologies used by the tractor manufacturers to comply with the 

2014 model year CO2 and fuel consumption standards. To date, the manufacturers are meeting 

the 2014 model year standards without the use of this technology. Therefore, in this proposal the 

agencies reverted back to the baseline APU adoption rate of 30 percent, the value used in the 

Phase 1 baseline. 

Table III-5 GEM Inputs for the Baseline Class 7 and 8 Tractor 

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

Engine

2017 MY 

11L 

Engine 

350 HP

2017 MY 

11L 

Engine 

350 HP

2017 MY 

11L 

Engine 

350 HP

2017 MY 

15L 

Engine 

455 HP

2017 MY 

15L 

Engine 

455 HP

2017 MY 

15L 

Engine 

455 HP

2017 MY 

15L 

Engine 

455 HP

2017 MY 

15L 

Engine 

455 HP

2017 MY 

15L 

Engine 

455 HP

Aerodynamics (CdA in m2)

5.00 6.40 6.42 5.00 6.40 6.42 4.95 6.35 6.22

Steer Tires (CRR in kg/metric ton)

6.99 6.99 6.87 6.99 6.99 6.87 6.87 6.87 6.54

Drive Tires (CRR in kg/metric ton)

7.38 7.38 7.26 7.38 7.38 7.26 7.26 7.26 6.92

Extended Idle Reduction Adoption Rate

N/A N/A N/A N/A N/A N/A 30% 30% 30%

Transmission = 10 Speed Manual Transmission

Gear Ratios = 12.8, 9.25, 6.76, 4.90, 3.58, 2.61, 1.89, 1.38, 1.00, 0.73

Drive Axle Ratio = 3.70
Page 183 of 850

Table III-6 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)

107 118 121 86 93 95 79 87 88

Fuel 

Consumption 

(gal/1,000 tonmile)

10.5 11.6 11.9 8.4 9.1 9.3 7.8 8.5 8.6

The fuel consumption and CO2 emissions in the baseline described above remains the 

same over time with no assumed improvements after 2017, absent a Phase 2 regulation. An 

alternative baseline was also evaluated by the agencies in which there is a continuing uptake of 

technologies in the tractor market that reduce fuel consumption and CO2 emissions absent a 

Phase 2 regulation. This alternative baseline, referred to as the more dynamic baseline, was 

developed to estimate the effect of market pressures and non-regulatory government initiatives to 

improve tractor fuel consumption. The more dynamic baseline assumes that the significant level 

of research funded and conducted by the Federal government, industry, academia and other 

organizations will, in the future, result the adoption of some technologies beyond the levels 

required to comply with Phase 1 standards. One example of such research is the Department of 

Energy Super Truck program163 which has a goal of demonstrating cost-effective measures to 

improve the efficiency of Class 8 long-haul freight trucks by 50 percent by 2015. The more

dynamic baseline also assumes that manufacturers will not cease offering fuel efficiency

improving technologies that currently have significant market penetration, such as automated 

manual transmissions. The baselines (one for each of the nine tractor types) are characterized by

fuel consumption and CO2 emissions that gradually decrease between 2019 and 2028. In 2028, 

the fuel consumption for the alternative tractor baselines is approximately 4.0 percent lower than 

those shown in Table III-6. This results from the assumed introduction of aerodynamic 

technologies such as down exhaust, underbody airflow treatment in addition to tires with lower 

rolling resistance. The assumed introduction of these technologies reduces the CdA of the 

baseline tractors and CRR of the tractor tires. To take one example, the CdA for baseline high 

roof sleeper cabs in Table III-5 is 6.22 (m2) in 2018. In 2028, the CdA of a high roof sleeper cab 

would be assumed to still be 6.22 m2in the baseline case outlined above. Alternatively, in the 

dynamic baseline, the CdA for high roof sleeper cabs is 5.61 (m2) in 2028 due to assumed market 

penetration of technologies absent the Phase 2 regulation. The dynamic baseline analysis is 

discussed in more detail in draft RIA Chapter 11.

 

163 U.S. Department of Energy. “SuperTruck Making Leaps in Fuel Efficiency.” 2014. Last accessed on May 

10,2015 at http://energy.gov/eere/articles/supertruck-making-leaps-fuel-efficiency
Page 184 of 850

(b) Tractor Technology Packages

The agencies’ assessment of the proposed technology effectiveness was developed 

through the use of the GEM in coordination with modeling conducted by Southwest Research 

Institute. The agencies developed the proposed standards through a three-step process, similar to 

the approach used in Phase 1. First, the agencies developed technology performance 

characteristics for each technology, as described below. Each technology is associated with an 

input parameter which in turn would be used as an input to the Phase 2 GEM simulation tool and 

its effectiveness thereby modeled. The performance levels for the range of Class 7 and 8 tractor 

aerodynamic packages and vehicle technologies are described below in Table III-7. Second, the 

agencies combined the technology performance levels with a projected technology adoption rate 

to determine the GEM inputs used to set the stringency of the proposed standards. Third, the 

agencies input these parameters into Phase 2 GEM and used the output to determine the 

proposed CO2 emissions and fuel consumption levels. All percentage improvements noted 

below are over the 2017 baseline tractor.

(i) Engine Improvements

There are several technologies that could be used to improve the efficiency of diesel 

engines used in tractors. Details of the engine technologies, adoption rates, and overall fuel 

consumption and CO2 emission reductions are included in Section II.D. The proposed heavyduty tractor engine standards would lead to a 1.5 percent reduction in 2021MY, a 3.5 percent 

reduction in 2024MY, and a 4 percent reduction in 2027MY. These reductions would show up 

in the fuel map used in GEM.

(ii) Aerodynamics

The aerodynamic packages are categorized as Bin I, Bin II, Bin III, Bin IV, Bin V, Bin 

VI, or Bin VII based on the wind averaged drag aerodynamic performance determined through 

testing conducted by the manufacturer. A more complete description of these aerodynamic 

packages is included in Chapter 2 of the draft RIA. In general, the proposed CdA values for each 

package and tractor subcategory were developed through EPA’s coastdown testing of tractortrailer combinations, the 2010 NAS report, and SAE papers. 

(iii) Tire Rolling Resistance

The proposed rolling resistance coefficient target for Phase 2 was developed from 

SmartWay’s tire testing to develop the SmartWay certification, testing a selection of tractor tires 

as part of the Phase 1 and Phase 2 programs, and from 2014 MY certification data. Even though 

the coefficient of tire rolling resistance comes in a range of values, to analyze this range, the tire 

performance was evaluated at four levels for both steer and drive tires, as determined by the 

agencies. The four levels are the baseline (average) from 2010, Level I and Level 2 from Phase 

1, and Level 3 that achieves an additional 25 percent improvement over Level 2. The Level 1 

rolling resistance performance represents the threshold used to develop SmartWay designated

tires for long haul tractors. The Level 2 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. The Level 3 values represent the long-term rolling resistance value that the 
Page 185 of 850

agencies predicts could be achieved in the 2025 timeframe. Given the multiple year phase-in of 

the standards, the agencies expect that tire manufacturers will continue to respond to demand for 

more efficient tires and will offer increasing numbers of tire models with rolling resistance 

values significantly better than today’s typical low rolling resistance tires. The tire rolling 

resistance level assumed to meet the 2017 MY Phase 1 standard high roof sleeper cab is 

considered to be a weighted average of 10 percent baseline rolling resistance, 70 percent Level 1, 

and 20 percent Level 2. The tire rolling resistance to meet the 2017MY Phase 1 standards for the 

high roof day cab, low roof sleeper cab, and mid roof sleeper cab includes 30 percent baseline, 

60 percent Level 1 and 10 percent Level 2. Finally, the low roof day cab 2017MY standard can 

be met with a weighted average rolling resistance consisting of 40 percent baseline, 50 percent 

Level 1, and 10 percent Level 2.

(iv) Idle Reduction

The benefits for the extended idle reductions were developed from literature, SmartWay

work, and the 2010 NAS report. Additional details regarding the comments and calculations are 

included in draft RIA Section 2.4.

(v) Transmission

The benefits for automated manual, automatic, and dual clutch transmissions were 

developed from literature and from simulation modeling conducted by Southwest Research 

Institute. The benefit of these transmissions is proposed to be set to a two percent improvement 

over a manual transmission due to the automation of the gear shifting.

(vi) Drivetrain

The reduction in friction due to low viscosity axle lubricants is set to 0.5 percent. 6x4 

and 4x2 axle configurations lead to a 2.5 percent improvement in vehicle efficiency. 

Downspeeding would be as demonstrated through the Phase 2 GEM inputs of transmission gear 

ratio, drive axle ratio, and tire diameter. Downspeeding is projected to improve the fuel 

consumption by 1.8 percent.

(vii) Accessories and Other Technologies

Compared to 2017MY air conditioners, air conditioners with improved efficiency

compressors will reduce CO2 emissions by 0.5 percent. Improvements in accessories, such as 

power steering, can lead to an efficiency improvement of 1 percent over the 2017MY baseline. 

Based on literature information, intelligent controls such as predictive cruise control will reduce 

CO2 emissions by 2 percent while automatic tire inflation systems improve fuel consumption by

1 percent by keeping tire rolling resistance to its optimum based on inflation pressure.

(viii) Weight Reduction

The weight reductions were developed from tire manufacturer information, the 

Aluminum Association, the Department of Energy, SABIC and TIAX, as discussed above in 

Section II.B.3.e. 
Page 186 of 850

(ix) Vehicle Speed Limiter

The agencies did not consider the availability of vehicle speed limiter technology in 

setting the Phase 1 stringency levels, and again did not consider the availability of the technology

in developing regulatory alternatives for Phase 2. However, as described in more detail above, 

speed limiters could be an effective means for achieving compliance, if employed on a voluntary

basis. 

(x) Summary of Technology Performance

Table III-7 describes the performance levels for the range of Class 7 and 8 tractor vehicle 

technologies. 
Page 187 of 850

Table III-7 Proposed Phase 2 Technology Inputs

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

Engine

2021MY 

11L 

Engine 

350 HP

2021MY 

11L 

Engine 

350 HP

2021MY 

11L 

Engine 

350 HP

2021MY 

15L 

Engine 

455 HP

2021MY 

15L 

Engine 

455 HP

2021MY 

15L 

Engine 

455 HP

2021MY 

15L 

Engine 

455 HP

2021MY 

15L 

Engine 

455 HP

2021MY 

15L 

Engine 

455 HP

Aerodynamics (CdA in m2)

Bin I 5.3 6.7 7.6 5.3 6.7 7.6 5.3 6.7 7.4

Bin II 4.8 6.2 7.1 4.8 6.2 7.1 4.8 6.2 6.9

Bin III 4.3 5.7 6.5 4.3 5.7 6.5 4.3 5.7 6.3

Bin IV 4.0 5.4 5.8 4.0 5.4 5.8 4.0 5.4 5.6

Bin V N/A N/A 5.3 N/A N/A 5.3 N/A N/A 5.1

Bin VI N/A N/A 4.9 N/A N/A 4.9 N/A N/A 4.7

Bin VII N/A N/A 4.5 N/A N/A 4.5 N/A N/A 4.3

Steer Tires (CRR in kg/metric ton)

Base 7.8 7.8 7.8 7.8 7.8 7.8 7.8 7.8 7.8

Level 1 6.6 6.6 6.6 6.6 6.6 6.6 6.6 6.6 6.6

Level 2 5.7 5.7 5.7 5.7 5.7 5.7 5.7 5.7 5.7

Level 3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3

Drive Tires (CRR in kg/metric ton)

Base 8.2 8.2 8.2 8.2 8.2 8.2 8.2 8.2 8.2

Level 1 7.0 7.0 7.0 7.0 7.0 7.0 7.0 7.0 7.0

Level 2 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0

Level 3 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5

Idle Reduction (% reduction)

APU N/A N/A N/A N/A N/A N/A 5% 5% 5%

Other N/A N/A N/A N/A N/A N/A 7% 7% 7%

Transmission Type (% reduction)

Manual 0% 0% 0% 0% 0% 0% 0% 0% 0%

AMT 2% 2% 2% 2% 2% 2% 2% 2% 2%

Auto 2% 2% 2% 2% 2% 2% 2% 2% 2%

Dual Clutch 2% 2% 2% 2% 2% 2% 2% 2% 2%

Driveline (% reduction)

Axle 

Lubricant

0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5%

6x2 or 4x2 

Axle

2.5% 2.5% 2.5% 2.5% 2.5% 2.5% 2.5% 2.5% 2.5%

Downspeed 1.8% 1.8% 1.8% 1.8% 1.8% 1.8% 1.8% 1.8% 1.8%

Accessory Improvements (% reduction)

A/C 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% 0.5%

Electric 

Access.

1% 1% 1% 1% 1% 1% 1% 1% 1%

Other Technologies (% reduction)
Page 188 of 850

Predictive 

Cruise 

Control

2% 2% 2% 2% 2% 2% 2% 2% 2%

Automated 

Tire 

Inflation 

System

1% 1% 1% 1% 1% 1% 1% 1% 1%

(c) Tractor Technology Adoption Rates

As explained above, tractor 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 adoption used to develop the proposed HD Phase 

2 standards, NHTSA and EPA established technology adoption constraints. The first type of 

constraint was established based on the application of fuel consumption and CO2 emission 

reduction technologies into the different types of tractors. For example, extended idle reduction 

technologies are limited to Class 8 sleeper cabs using the reasonable assumption that day cabs 

are not used for overnight hoteling. A second type of constraint was applied to most other 

technologies and limited their adoption 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, powertrain, and vehicle speed limiter technologies.

Table III-8 and Table III-10, specify the adoption rates that EPA and NHTSA used to 

develop the proposed standards. The agencies welcome comments on these adoption rates.

NHTSA and EPA believe 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. For example, the agencies are not predicating the proposed standards on 

the use of full aerodynamic vehicle treatments on 100 percent of tractors because we know that 

in many applications (for example gravel truck engaged in local aggregate delivery) the added 

weight of the aerodynamic technologies will increase fuel consumption and hence CO2 emissions 

to a greater degree than the reduction that would be accomplished from the more aerodynamic 

nature of the tractor. 

(i) Aerodynamics Adoption Rate

The impact of aerodynamics on a tractor-trailer’s efficiency increases with vehicle speed. 

Therefore, the usage pattern of the vehicle 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 
Page 189 of 850

aerodynamic technology development, including SmartWay tractors, on these types of trucks. 

Therefore the agencies are proposing the most aggressive aerodynamic technology application to 

this regulatory subcategory. All of the major manufacturers today offer at least one SmartWay

sleeper cab tractor model, which is represented as Bin III aerodynamic performance. The 

proposed aerodynamic adoption rate for Class 8 high roof sleeper cabs in 2027 (i.e., the degree 

of technology adoption on which the stringency of the proposed standard is premised) consists of 

20 percent of Bin IV, 35 percent Bin V, 20 percent Bin VI, and 5 percent Bin VII reflecting our 

assessment of the fraction of tractors in this segment that could successfully apply these 

aerodynamic packages with this amount of lead time. We believe that there is sufficient lead 

time to develop aerodynamic tractors that can move the entire high roof sleeper cab aerodynamic 

performance to be as good as or better than today’s SmartWay designated tractors. The changes 

required for Bin IV and better performance reflect the kinds of improvements projected in the 

Department of Energy’s SuperTruck program. That program assumes that such systems can be 

demonstrated on vehicles by 2017. In this case, the agencies are projecting that truck 

manufacturers would be able to begin implementing these aerodynamic technologies as early as 

2021 MY on a limited scale. Importantly, our averaging, banking and trading provisions provide 

manufacturers with the flexibility (and incentive) to implement these technologies over time 

even though the standard changes in a single step. 

The aerodynamic adoption rates used to develop the proposed standards for the other 

tractor regulatory categories are less aggressive than for the Class 8 sleeper cab high roof. 

Aerodynamic improvements through new tractor designs and the development of new 

aerodynamic components is an inherently slow and iterative process. The agencies recognize 

that there are tractor 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.165 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 adoption of 

more advanced aerodynamic technologies for all of the tractor regulatory subcategories.

As discussed in Section III.C.2, the agencies propose to increase the number of 

aerodynamic bins for low and mid roof tractors from the two levels adopted in Phase 1 to four 

levels in Phase 2. The agencies propose to increase 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. 

 

165 U.S. Department of Energy. Transportation Energy Data Book, Edition 28-2009. Table 5.7.
Page 190 of 850

(ii) Low Rolling Resistance Tire Adoption Rate

For the tire manufacturers to further reduce tire rolling resistance, the manufacturers must 

consider several performance criteria that affect tire selection. The characteristics of a tire also 

influence durability, traction control, vehicle handling, comfort, and retreadability. A single 

performance parameter can easily be enhanced, but an optimal balance of all the criteria will 

require improvements in materials and tread design at a higher cost, as estimated by the agencies. 

Tire design requires balancing performance, since changes in design may change different 

performance characteristics in opposing directions. Similar to the discussion regarding lesser 

aerodynamic technology application in tractor segments other than sleeper cab high roof, the 

agencies believe that the proposed standards should not be premised on 100 percent application 

of Level 3 tires in all tractor segments given the potential interference with vehicle utility that 

could result. 

(iii) Weight Reduction Technology Adoption Rate

Unlike in HD Phase 1, the agencies propose setting the 2021 through 2027 model year 

tractor standards without using weight reduction as a technology to demonstrate the feasibility. 

However, as described in Section III.C.2 below, the agencies are proposing an expanded list of 

weight reduction options which could be input into the GEM by the manufacturers to reduce 

their certified CO2 emission and fuel consumption levels. The agencies view weight reduction as 

a technology with a high cost that offers a small benefit in the tractor sector. For example, our 

estimate of a 400 pound weight reduction would cost $2,050 (2012$) in 2021MY, but offers a 

0.3 percent reduction in fuel consumption and CO2 emissions. 

(iv) Idle Reduction Technology Adoption Rate

Idle reduction technologies provide significant reductions in fuel consumption and CO2

emissions for Class 8 sleeper cabs and are available on the market today. 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 adopted in Phase 1, we are allowing only idle emission reduction technologies 

which include an automatic engine shutoff (AES) with some override provisions.166 However, 

we welcome comment on other approaches that would appropriately quantify the reductions that 

would be experienced in the real world. 

We propose an overall 90 percent adoption rate for this technology for Class 8 sleeper 

cabs. The agencies are unaware of reasons why AES with extended idle reduction technologies 

 

166 The agencies are proposing to continue the HD Phase 1 AES override provisions included in 40 CFR 

1037.660(b) for driver safety.
Page 191 of 850

could not be applied to this high fraction of tractors with a sleeper cab, except those deemed a 

vocational tractor, in the available lead time. 

The agencies are interested in extending the idle reduction benefits beyond Class 8 

sleepers, to day cabs. 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.167 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 day cabs and identify the percent of this idling which could be reduced through the use 

of AES. We welcome comment and data on quantifying the effectiveness of AES on day cabs. 

(v) Vehicle Speed Limiter Adoption Rate

As adopted in Phase 1, we propose to continue the approach where vehicle speed limiters 

may be used as a technology to meet the proposed standard. In setting the proposed standard, 

however, we assumed a zero percent adoption 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 tractors 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 or owners. 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 at 55 mph for this vehicle at the request of the customer. The 

resulting tractor would be optimized for its intended application and would be fully compliant 

with our program all at a lower cost to the ultimate tractor purchaser.168 

As in Phase 1, we have chosen not to base the proposed standards on performance of 

VSLs because of concerns about how to set a realistic adoption rate that avoids unintended 

adverse impacts. Although we expect there would 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. To date, the compliance data provided by manufacturers 

 

167Gaines, L., A. Vyas, J. Anderson. Estimation of Fuel Use by Idling Commercial Trucks. January 2006.

168 Ibid.

168 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 proposed standard is not based 

on performance of VSLs (i.e. VSL is an on-cycle technology).
Page 192 of 850

indicate that none of the tractor configurations include a tamper-proof VSL setting less than 65 

mph. 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 or how many

customers would be willing to accept a tamper-proof VSL setting. As discussed in Section 

III.E.2.f below, we welcome comment on suggestions to modify the tamper-proof requirement 

while maintaining assurance that the speed limiter is used in-use throughout the life of the 

vehicle. We are not able at this time to quantify the potential loss in utility due to the use of 

VSLs, but we welcome comment on whether the use of a VSL would require a fleet to deploy

additional tractors. Absent this information, we cannot make a determination regarding the 

reasonableness of setting a standard based on a particular VSL level. Therefore, the agencies are 

not premising the proposed standards on use of VSL, and instead would continue to 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 proposed program’s costs and 

benefits, therefore it remains a significant flexibility for manufacturers to choose. 

(vi) Summary of the Adoption Rates used to Determine the Proposed Standards

Table III-8 through Table III-10 provide the adoption rates of each technology broken down by

weight class, cab configuration, and roof height.
Page 193 of 850

Table III-8 Technology Adoption Rates for Class 7 and 8 Tractors for Determining the Proposed 2021 MY 

Standards

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

2021MY Engine Technology Package

100% 100% 100% 100% 100% 100% 100% 100% 100%

Aerodynamics 

Bin I 0% 0% 0% 0% 0% 0% 0% 0% 0%

Bin II 75% 75% 0% 75% 75% 0% 75% 75% 0%

Bin III 25% 25% 40% 25% 25% 40% 25% 25% 40%

Bin IV 0% 0% 35% 0% 0% 35% 0% 0% 35%

Bin V N/A N/A 20% N/A N/A 20% N/A N/A 20%

Bin VI N/A N/A 5% N/A N/A 5% N/A N/A 5%

Bin VII N/A N/A 0% N/A N/A 0% N/A N/A 0%

Steer Tires 

Base 5% 5% 5% 5% 5% 5% 5% 5% 5%

Level 1 60% 60% 60% 60% 60% 60% 60% 60% 60%

Level 2 25% 25% 25% 25% 25% 25% 25% 25% 25%

Level 3 10% 10% 10% 10% 10% 10% 10% 10% 10%

Drive Tires 

Base 5% 5% 5% 5% 5% 5% 5% 5% 5%

Level 1 60% 60% 60% 60% 60% 60% 60% 60% 60%

Level 2 25% 25% 25% 25% 25% 25% 25% 25% 25%

Level 3 10% 10% 10% 10% 10% 10% 10% 10% 10%

Extended Idle Reduction 

APU N/A N/A N/A N/A N/A N/A 80% 80% 80%

Transmission Type 

Manual 45% 45% 45% 45% 45% 45% 45% 45% 45%

AMT 40% 40% 40% 40% 40% 40% 40% 40% 40%

Auto 10% 10% 10% 10% 10% 10% 10% 10% 10%

Dual Clutch 5% 5% 5% 5% 5% 5% 5% 5% 5%

Driveline

Axle 

Lubricant

20% 20% 20% 20% 20% 20% 20% 20% 20%

6x2 or 4x2 

Axle

10% 10% 20% 10% 10% 20%

Downspeed 20% 20% 20% 20% 20% 20% 20% 20% 20%

Accessory Improvements 

A/C 10% 10% 10% 10% 10% 10% 10% 10% 10%

Electric 

Access.

10% 10% 10% 10% 10% 10% 10% 10% 10%

Other Technologies 

Predictive 

Cruise 

Control

20% 20% 20% 20% 20% 20% 20% 20% 20%
Page 194 of 850

Automated 

Tire 

Inflation 

System

20% 20% 20% 20% 20% 20% 20% 20% 20%

Table III-9 Technology Adoption Rates for Class 7 and 8 Tractors for Determining the Proposed 2024 MY 

Standards

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

2024 MY Engine Technology Package

100% 100% 100% 100% 100% 100% 100% 100% 100%

Aerodynamics 

Bin I 0% 0% 0% 0% 0% 0% 0% 0% 0%

Bin II 60% 60% 0% 60% 60% 0% 60% 60% 0%

Bin III 38% 38% 30% 38% 38% 30% 38% 38% 30%

Bin IV 2% 2% 30% 2% 2% 30% 2% 2% 30%

Bin V N/A N/A 25% N/A N/A 25% N/A N/A 25%

Bin VI N/A N/A 13% N/A N/A 13% N/A N/A 13%

Bin VII N/A N/A 2% N/A N/A 2% N/A N/A 2%

Steer Tires 

Base 5% 5% 5% 5% 5% 5% 5% 5% 5%

Level 1 50% 50% 50% 50% 50% 50% 50% 50% 50%

Level 2 30% 30% 30% 30% 30% 30% 30% 30% 30%

Level 3 15% 15% 15% 15% 15% 15% 15% 15% 15%

Drive Tires 

Base 5% 5% 5% 5% 5% 5% 5% 5% 5%

Level 1 50% 50% 50% 50% 50% 50% 50% 50% 50%

Level 2 30% 30% 30% 30% 30% 30% 30% 30% 30%

Level 3 15% 15% 15% 15% 15% 15% 15% 15% 15%

Extended Idle Reduction 

APU N/A N/A N/A N/A N/A N/A 90% 90% 90%

Transmission Type 

Manual 20% 20% 20% 20% 20% 20% 20% 20% 20%

AMT 50% 50% 50% 50% 50% 50% 50% 50% 50%

Auto 20% 20% 20% 20% 20% 20% 20% 20% 20%

Dual Clutch 10% 10% 10% 10% 10% 10% 10% 10% 10%

Driveline

Axle 

Lubricant

40% 40% 40% 40% 40% 40% 40% 40% 40%

6x2 or 4x2 

Axle

20% 20% 60% 20% 20% 60%

Downspeed 40% 40% 40% 40% 40% 40% 40% 40% 40%

Direct Drive 50% 50% 50% 50% 50% 50% 50% 50% 50%

Accessory Improvements 

A/C 20% 20% 20% 20% 20% 20% 20% 20% 20%
Page 195 of 850

Electric 

Access.

20% 20% 20% 20% 20% 20% 20% 20% 20%

Other Technologies 

Predictive 

Cruise 

Control

40% 40% 40% 40% 40% 40% 40% 40% 40%

Automated 

Tire 

Inflation 

System

40% 40% 40% 40% 40% 40% 40% 40% 40%
Page 196 of 850

Table III-10 Technology Adoption Rates for Class 7 and 8 Tractors for Determining the Proposed 2027 MY 

Standards

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

2027 MY Engine Technology Package

100% 100% 100% 100% 100% 100% 100% 100% 100%

Aerodynamics 

Bin I 0% 0% 0% 0% 0% 0% 0% 0% 0%

Bin II 50% 50% 0% 50% 50% 0% 50% 50% 0%

Bin III 40% 40% 20% 40% 40% 20% 40% 40% 20%

Bin IV 10% 10% 20% 10% 10% 20% 10% 10% 20%

Bin V N/A N/A 35% N/A N/A 35% N/A N/A 35%

Bin VI N/A N/A 20% N/A N/A 20% N/A N/A 20%

Bin VII N/A N/A 5% N/A N/A 5% N/A N/A 5%

Steer Tires 

Base 5% 5% 5% 5% 5% 5% 5% 5% 5%

Level 1 20% 20% 20% 20% 20% 20% 20% 20% 20%

Level 2 50% 50% 50% 50% 50% 50% 50% 50% 50%

Level 3 25% 25% 25% 25% 25% 25% 25% 25% 25%

Drive Tires 

Base 5% 5% 5% 5% 5% 5% 5% 5% 5%

Level 1 20% 20% 20% 20% 20% 20% 20% 20% 20%

Level 2 50% 50% 50% 50% 50% 50% 50% 50% 50%

Level 3 25% 25% 25% 25% 25% 25% 25% 25% 25%

Extended Idle Reduction 

APU N/A N/A N/A N/A N/A N/A 90% 90% 90%

Transmission Type 

Manual 10% 10% 10% 10% 10% 10% 10% 10% 10%

AMT 50% 50% 50% 50% 50% 50% 50% 50% 50%

Auto 30% 30% 30% 30% 30% 30% 30% 30% 30%

Dual Clutch 10% 10% 10% 10% 10% 10% 10% 10% 10%

Driveline

Axle 

Lubricant

40% 40% 40% 40% 40% 40% 40% 40% 40%

6x2 Axle 20% 20% 60% 20% 20% 60%

Downspeed 60% 60% 60% 60% 60% 60% 60% 60% 60%

Direct Drive 50% 50% 50% 50% 50% 50% 50% 50% 50%

Accessory Improvements 

A/C 30% 30% 30% 30% 30% 30% 30% 30% 30%

Electric 

Access.

30% 30% 30% 30% 30% 30% 30% 30% 30%

Other Technologies 

Predictive 

Cruise 

Control

40% 40% 40% 40% 40% 40% 40% 40% 40%
Page 197 of 850

Automated 

Tire 

Inflation 

System

40% 40% 40% 40% 40% 40% 40% 40% 40%

(d) Derivation of the Proposed Tractor Standards

The agencies used the technology effectiveness inputs and technology adoption rates to 

develop GEM inputs to derive the proposed HD Phase 2 fuel consumption and CO2 emissions 

standards for each subcategory of Class 7 and 8 combination tractors. Note that we have 

analyzed one technology pathway for each proposed level of stringency, but manufacturers

would be free to use any combination of technology to meet the standards, and with the 

flexibility of averaging, banking and trading, to meet the standard on average. The agencies 

derived a scenario tractor for each subcategory by weighting the individual GEM input 

parameters included in Table III-7 with the adoption rates in Table III-8 through Table III-10.

For example, the proposed CdA value for a 2021MY Class 8 Sleeper Cab High Roof scenario 

case was derived as 40 percent times 6.3 plus 35 percent times 5.6 plus 20 percent times 5.1 plus 

5 percent times 4.7, which is equal to a CdA of 5.74 m

2

. Similar calculations were made for tire 

rolling resistance, transmission types, idle reduction, and other technologies. To account for the 

proposed engine standards and engine technologies, the agencies assumed a compliant engine 

fuel map in GEM.169 The agencies then ran GEM with a single set of vehicle inputs, as shown in 

Table III-11, to derive the proposed standards for each subcategory. Additional detail is 

provided in the draft RIA Chapter 2. 

 

169 See Section II.D above explaining the derivation of the proposed engine standards.
Page 198 of 850

Table III-11 GEM Inputs for the Proposed 2021MY 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

Engine

2021MY 

11L 

Engine 

350 HP

2021MY 

11L 

Engine 

350 HP

2021MY 

11L 

Engine 

350 HP

2021MY 

15L 

Engine 

455 HP

2021MY 

15L 

Engine 

455 HP

2021MY 

15L 

Engine 

455 HP

2021MY 

15L 

Engine 

455 HP

2021MY 

15L 

Engine 

455 HP

2021MY 

15L 

Engine 

455 HP

Aerodynamics (CdA in m2)

4.68 6.08 5.94 4.68 6.08 5.94 4.68 6.08 5.74

Steer Tires (CRR in kg/metric ton)

6.2 6.2 6.2 6.2 6.2 6.2 6.2 6.2 6.2

Drive Tires (CRR in kg/metric ton)

6.6 6.6 6.6 6.6 6.6 6.6 6.6 6.6 6.6

Extended Idle Reduction Weighted Effectiveness

N/A N/A N/A N/A N/A N/A 2.5% 2.5% 2.5%

Transmission = 10 speed Automated Manual Transmission

Gear Ratios = 12.8, 9.25, 6.76, 4.90, 3.58, 2.61, 1.89, 1.38, 1.00, 0.73

Drive axle Ratio = 3.55

6x2 Axle Weighted Effectiveness

N/A N/A N/A 0.3% 0.3% 0.5% 0.3% 0.3% 0.5%

Low Friction Axle Lubrication = 0.1%

Transmission benefit = 1.1%

Predictive Cruise Control =0.4%

Accessory Improvements = 0.1%

Air Conditioner Efficiency Improvements = 0.1%

Automatic Tire Inflation Systems = 0.2%

Weight Reduction = 0 pounds
Page 199 of 850

Table III-12 GEM Inputs for the Proposed 2024MY 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

Engine

2024MY 

11L 

Engine 

350 HP

2024MY 

11L 

Engine 

350 HP

2024MY 

11L 

Engine 

350 HP

2024MY 

15L 

Engine 

455 HP

2024MY 

15L 

Engine 

455 HP

2024MY 

15L 

Engine 

455 HP

2024MY 

15L 

Engine 

455 HP

2024MY 

15L 

Engine 

455 HP

2024MY 

15L 

Engine 

455 HP

Aerodynamics (CdA in m2)

4.59 5.99 5.74 4.59 5.99 5.74 4.59 5.99 5.54

Steer Tires (CRR in kg/metric ton)

5.9 5.9 5.9 5.9 5.9 5.9 5.9 5.9 5.9

Drive Tires (CRR in kg/metric ton)

6.2 6.2 6.2 6.2 6.2 6.2 6.2 6.2 6.2

Extended Idle Reduction Weighted Effectiveness

N/A N/A N/A N/A N/A N/A 3% 3% 3%

Transmission = 10 speed Automated Manual Transmission

Gear Ratios = 12.8, 9.25, 6.76, 4.90, 3.58, 2.61, 1.89, 1.38, 1.00, 0.73

Drive axle Ratio = 3.36

6x2 Axle Weighted Effectiveness

N/A N/A N/A 0.5% 0.5% 1.5% 0.5% 0.5% 1.5%

Low Friction Axle Lubrication = 0.2%

Transmission benefit = 1.6%

Predictive Cruise Control =0.8%

Accessory Improvements = 0.2%

Air Conditioner Efficiency Improvements = 0.1%

Automatic Tire Inflation Systems = 0.4%

Weight Reduction = 0 pounds

Direct Drive Weighted Efficiency = 1% for sleeper cabs; 0.8% for day cabs
Page 200 of 850

Table III-13 GEM Inputs for the Proposed 2027MY 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

Engine

2027MY 

11L 

Engine 

350 HP

2027MY 

11L 

Engine 

350 HP

2027MY 

11L 

Engine 

350 HP

2027MY 

15L 

Engine 

455 HP

2027MY 

15L 

Engine 

455 HP

2027MY 

15L 

Engine 

455 HP

2027MY 

15L 

Engine 

455 HP

2027MY 

15L 

Engine 

455 HP

2027MY 

15L 

Engine 

455 HP

Aerodynamics (CdA in m2)

4.52 5.92 5.52 4.52 5.92 5.52 4.52 5.92 5.32

Steer Tires (CRR in kg/metric ton)

5.6 5.6 5.6 5.6 5.6 5.6 5.6 5.6 5.6

Drive Tires (CRR in kg/metric ton)

5.9 5.9 5.9 5.9 5.9 5.9 5.9 5.9 5.9

Extended Idle Reduction Weighted Effectiveness

N/A N/A N/A N/A N/A N/A 3% 3% 3%

Transmission = 10 speed Automated Manual Transmission

Gear Ratios = 12.8, 9.25, 6.76, 4.90, 3.58, 2.61, 1.89, 1.38, 1.00, 0.73

Drive axle Ratio = 3.2

6x2 Axle Weighted Effectiveness

N/A N/A N/A 0.5% 0.5% 1.5% 0.5% 0.5% 1.5%

Low Friction Axle Lubrication = 0.2%

Transmission benefit = 1.8%

Predictive Cruise Control =0.8%

Accessory Improvements = 0.3%

Air Conditioner Efficiency Improvements = 0.2%

Automatic Tire Inflation Systems = 0.4%

Weight Reduction = 0 pounds

Direct Drive Weighted Efficiency = 1% for sleeper cabs; 0.8% for day cabs

The proposed level of the 2027 model year standards, in addition to the phase-in 

standards in model years 2021 and 2024 for each subcategory is included in Table III-14. 
Page 201 of 850

Table III-14 Proposed 2021, 2024, and 2027 Model Year Tractor Standards

2021 Model Year CO2 Grams per Ton-Mile

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 97 78 70

Mid Roof 107 84 78

High Roof 109 86 77

2021 Model Year Gallons of Fuel per 1,000 Ton-Mile

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 9.5285 7.6621 6.8762

Mid Roof 10.5108 8.2515 7.6621

High Roof 10.7073 8.4479 7.5639

2024 Model Year CO2 Grams per Ton-Mile

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 90 72 64

Mid Roof 100 78 71

High Roof 101 79 70

2024 Model Year and Later Gallons of Fuel per 1,000 Ton-Mile

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 8.8409 7.0727 6.2868

Mid Roof 9.8232 7.6621 6.9745

High Roof 9.9214 7.7603 6.8762

2027 Model Year CO2 Grams per Ton-Mile

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 87 70 62

Mid Roof 96 76 69

High Roof 96 76 67

2027 Model Year and Later Gallons of Fuel per 1,000 Ton-Mile

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 8.5462 6.8762 6.0904

Mid Roof 9.4303 7.4656 6.7780

High Roof 9.4303 7.4656 6.5815

A summary of the draft technology package costs is included in Table III-15 through 

Table III-17 for MYs 2021, 2024, and 2027, respectively, with additional details available in the 

draft RIA Chapter 2.12. We welcome comments on the technology costs.
Page 202 of 850

Table III-15 Class 7 and 8 Tractor Technology Incremental Costs in the 2021 Model Yeara,b

Preferred Alternative vs. the Less Dynamic Baseline (2012$ per vehicle)

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

Enginec $314 $314 $314 $314 $314 $314 $314

Aerodynamics $687 $511 $687 $511 $656 $656 $535

Tires $49 $9 $81 $15 $59 $59 $15

Tire inflation 

system

$180 $180 $180 $180 $180 $180 $180

Transmission $3,969 $3,969 $3,969 $3,969 $3,969 $3,969 $3,969

Axle & axle 

lubes

$50 $50 $70 $90 $70 $70 $90

Idle reduction 

with APU

$0 $0 $0 $0 $2,449 $2,449 $2,449

Air 

conditioning

$45 $45 $45 $45 $45 $45 $45

Other vehicle 

technologies

$174 $174 $174 $174 $174 $174 $174

Total $5,468 $5,252 $5,520 $5,298 $7,916 $7,916 $7,771

Notes:

a Costs shown are for the 2021 model year and are incremental to the costs of a tractor meeting the Phase 1 

standards. These costs include indirect costs via markups along with learning impacts. For a description of the 

markups and learning impacts considered in this analysis and how it impacts technology costs for other years, refer 

to Chapter 2 of the draft RIA (see draft RIA 2.12).

b Note that values in this table include adoption rates. Therefore, the technology costs shown reflect the average cost 

expected for each of the indicated tractor classes. To see the actual estimated technology costs exclusive of adoption

rates, refer to Chapter 2 of the draft RIA (see draft RIA 2.12 in particular).

c Engine costs are for a heavy HD diesel engine meant for a combination tractor. The engine costs in this table are 

equal to the engine costs associated with the separate engine standard because both include the same set of engine 

technologies (see Section II.D.2.d.i).
Page 203 of 850

Table III-16 Class 7 and 8 Tractor Technology Incremental Costs in the 2024 Model Yeara,b

Preferred Alternative vs. the Less Dynamic Baseline (2012$ per vehicle)

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

Enginec $904 $904 $904 $904 $904 $904 $904

Aerodynamics $744 $684 $744 $684 $712 $712 $723

Tires $47 $11 $78 $18 $58 $58 $18

Tire inflation 

system

$330 $330 $330 $330 $330 $330 $330

Transmission $5,883 $5,883 $5,883 $5,883 $5,883 $5,883 $5,883

Axle & axle 

lubes

$92 $92 $128 $200 $128 $128 $200

Idle reduction 

with APU

$0 $0 $0 $0 $2,687 $2,687 $2,687

Air 

conditioning

$82 $82 $82 $82 $82 $82 $82

Other vehicle 

technologies

$318 $318 $318 $318 $318 $318 $318

Total $8,400 $8,304 $8,467 $8,419 $11,102 $11,102 $11,145

Notes:

a Costs shown are for the 2024 model year and are incremental to the costs of a tractor meeting the Phase 1 

standards. These costs include indirect costs via markups along with learning impacts. For a description of the 

markups and learning impacts considered in this analysis and how it impacts technology costs for other years, refer 

to Chapter 2 of the draft RIA (see draft RIA 2.12).

b Note that values in this table include adoption rates. Therefore, the technology costs shown reflect the average cost 

expected for each of the indicated tractor classes. To see the actual estimated technology costs exclusive of adoption

rates, refer to Chapter 2 of the draft RIA (see draft RIA 2.12).

c Engine costs are for a heavy HD diesel engine meant for a combination tractor. The engine costs in this table are 

equal to the engine costs associated with the separate engine standard because both include the same set of engine 

technologies (see Section II.D.2.d.i).
Page 204 of 850

Table III-17 Class 7 and 8 Tractor Technology Incremental Costs in the 2027 Model Yeara,b

Preferred Alternative vs. the Less Dynamic Baseline (2012$ per vehicle)

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

Enginec $1,698 $1,698 $1,698 $1,698 $1,698 $1,698 $1,698

Aerodynamics $771 $765 $771 $765 $733 $733 $802

Tires $45 $10 $75 $17 $56 $56 $17

Tire inflation 

system

$314 $314 $314 $314 $314 $314 $314

Transmission $6,797 $6,797 $6,797 $6,797 $6,797 $6,797 $6,797

Axle & axle 

lubes

$97 $97 $131 $200 $131 $131 $200

Idle reduction 

with APU

$0 $0 $0 $0 $2,596 $2,596 $2,596

Air 

conditioning

$117 $117 $117 $117 $117 $117 $117

Other vehicle 

technologies

$302 $302 $302 $302 $302 $302 $302

Total $10,140 $10,099 $10,204 $10,209 $12,744 $12,744 $12,842

Notes:

a Costs shown are for the 2027 model year and are incremental to the costs of a tractor meeting the Phase 1 

standards. These costs include indirect costs via markups along with learning impacts. For a description of the 

markups and learning impacts considered in this analysis and how it impacts technology costs for other years, refer 

to Chapter 2 of the draft RIA (see draft RIA 2.12).

b Note that values in this table include adoption rates. Therefore, the technology costs shown reflect the average cost 

expected for each of the indicated tractor classes. To see the actual estimated technology costs exclusive of adoption

rates, refer to Chapter 2 of the draft RIA (see draft RIA 2.12 in particular).

c Engine costs are for a heavy HD diesel engine meant for a combination tractor. The engine costs in this table are 

equal to the engine costs associated with the separate engine standard because both include the same set of engine 

technologies (see Section II.D.2.d.i).

(i) Proposed Heavy-Haul Tractor Standards

For Phase 2, the agencies propose to add a tenth subcategory to the tractor category for 

heavy-haul tractors. The agencies recognize the need for manufacturers to build these types of 

vehicles for specific applications and believe the appropriate way to prevent penalizing these 

vehicles is to set separate standards recognizing a heavy-haul vehicle’s unique needs, such as 

requiring a higher horsepower engine or different transmissions. The agencies are proposing this 

change in Phase 2 because unlike in Phase 1 the engine, transmission, and drivetrain 

technologies are included in the technology packages used to determine the stringency of the 

proposed tractor standards and are included as manufacturer inputs in GEM. This means that the 

agencies can adopt a standard reflecting individualized performance of these technologies in 

particular applications, in this case, heavy-haul tractors, and further, have a means of reliably 

assessing individualized performance of these technology at certification. 
Page 205 of 850

The typical tractor is designed with a Gross Combined Weight Rating (GCWR) of 

approximately 80,000 pounds due to the effective weight limit on the federal highway system, 

except in states with preexisting higher weight limits. The agencies propose to consider tractors 

with a GCWR over 120,000 pounds as heavy-haul tractors. Based on comments received during 

the development of HD Phase 1 (76 FR 57136-8) and because we are not proposing a sales limit 

for heavy-haul like we have for the vocational tractors, the agencies also believe it would be 

appropriate to further define the heavy-haul vehicle characteristics to differentiate these vehicles 

from the vehicles in the other nine tractor subcategories. The two additional requirements would 

include a total gear reduction greater than or equal to 57:1 and a frame Resisting Bending 

Moment (RBM) greater than or equal to 2,000,000 in-lbs per rail or rail and liner combination. 

Heavy-haul tractors typically require the large gear reduction to provide the torque necessary to 

start the vehicle moving. These vehicles also typically require frame rails with extra strength to 

ensure the ability to haul heavy loads. We welcome comment on the proposed heavy-haul 

tractor specifications, including whether Gross Vehicle Weight Rating (GVWR) or Gross Axle 

Weight Rating (GAWR) would be a more appropriate metric to differentiate between a heavyhaul tractor and a typical tractor.

The agencies propose that heavy-haul tractors demonstrate compliance with the proposed 

standards using the day cab drive cycle weightings of 19 percent transient cycle, 17 percent 55 

mph cycle, and 64 percent 65 mph cycle. We also propose that GEM simulates the heavy-haul 

tractors with a payload of 43 tons and a total tractor, trailer, and payload weight of 118,500 

pounds. In addition, we propose that the engines installed in heavy-haul tractors meet the 

proposed tractor engine standards included in 40 CFR 1036.108. We welcome comments on 

these proposed specifications.

The agencies recognize that certain technologies used to determine the stringency of the 

proposed Phase 2 tractor standards are less applicable to heavy-haul tractors. Heavy-haul 

tractors are not typically used in the same manner as long-haul tractors with extended highway

driving, and therefore would experience less benefit from aerodynamics. Aerodynamic 

technologies are very effective at reducing the fuel consumption and GHG emissions of tractors, 

but only when traveling at highway speeds. At lower speeds, the aerodynamic technologies may

have a detrimental impact due to the potential of added weight. The agencies therefore are not 

considering the use of aerodynamic technologies in the development of the proposed Phase 2 

heavy-haul tractor standards. Moreover, because aerodynamics would not play a role in the 

heavy-haul standards, the agencies propose to combine all of the heavy-haul tractor cab 

configurations (day and sleeper) and roof heights (low, mid, and high) into a single heavy-haul 

tractor subcategory.

170

 We welcome comment on this approach.

Certain powertrain and drivetrain components are also impacted during the design of a 

heavy-haul tractor, including the transmission, axles, and the engine. Heavy-haul tractors 

typically require transmissions with 13 or 18 speeds to provide the ratio spread to ensure that the 

 

170 Since aerodynamic improvements are not part of the technology package, the agencies likewise are not proposing 

any bin structure for the heavy-haul tractor subcategory.
Page 206 of 850

tractor is able to start pulling the load from a stop. Downsped powertrains are typically not an 

option for heavy-haul operations because these vehicles require more torque to move the vehicle 

because of the heavier load. Finally, due to the loading requirements of the vehicle, it is not 

likely that a 6x2 axle configuration can be used in heavy-haul applications.

The agencies used the following heavy-haul tractor inputs for developing the proposed 

2021, 2024, and 2027 MY standards, as shown in Table III-18 and Table III-19. 

Table III-18 Application Rates for Proposed Heavy-Haul Tractor Standards

Heavy-Haul Tractor Application Rates

2021MY 2024MY 2027MY

Engine 2021 MY 15L Engine 

with 600 HP

2024 MY 15L Engine 

with 600 HP

2027 MY 15L Engine 

with 600 HP

Aerodynamics – 0%

Steer Tires

Phase 1 Baseline 5% 5% 5%

Level I 60% 50% 20%

Level 2 25% 30% 50%

Level 3 10% 15% 25%

Drive Tires

Phase 1 Baseline 5% 5% 5%

Level I 60% 50% 20%

Level 2 25% 30% 50%

Level 3 10% 15% 25%

Transmission

AMT 40% 50% 50%

Automatic 10% 20% 30%

DCT 5% 10% 10%

Other Technologies

6x2 Axle 0% 0% 0%

Low Friction Axle 

Lubrication

20% 40% 40%

Predictive Cruise 

Control

20% 40% 40%

Accessory 

Improvements

10% 20% 30%

Air Conditioner 

Efficiency 

Improvements

10% 20% 30%

Automatic Tire 

Inflation Systems

20% 40% 40%

Weight Reduction 0% 0% 0%
Page 207 of 850

Table III-19 GEM Inputs for Proposed 2021, 2024 and 2027 MY Heavy-Haul Tractor Standards

Heavy-Haul Tractor

Baseline 2021MY 2024MY 2027MY

Engine = 2017 MY 15L 

Engine with 600 HP

Engine = 2021 MY 15L 

Engine with 600 HP

Engine = 2024 MY 15L 

Engine with 600 HP

Engine = 2027 MY 15L 

Engine with 600 HP

Aerodynamics (CdA in m2) = 5.00

Steer Tires (CRR in 

kg/metric ton) = 7.0

Steer Tires (CRR in 

kg/metric ton) = 6.2

Steer Tires (CRR in 

kg/metric ton) = 6.0

Steer Tires (CRR in 

kg/metric ton) = 5.8

Drive Tires (CRR in 

kg/metric ton) = 7.4

Drive Tires (CRR in 

kg/metric ton) = 6.6

Drive Tires (CRR in 

kg/metric ton) = 6.4

Drive Tires (CRR in 

kg/metric ton) = 6.2

Transmission = 13

speed Manual 

Transmission

Gear Ratios = 12.29, 

8.51, 6.05, 4.38, 3.20, 

2.29, 1.95, 1.62, 1.38,

1.17, 1.00, 0.86, 0.73

Transmission = 13 speed 

Automated Manual 

Transmission

Gear Ratios = 12.29, 8.51, 

6.05, 4.38, 3.20, 2.29, 1.95, 

1.62, 1.38, 1.17, 1.00, 0.86, 

0.73

Transmission = 13 speed 

Automated Manual 

Transmission

Gear Ratios = 12.29, 8.51, 

6.05, 4.38, 3.20, 2.29, 1.95,

1.62, 1.38, 1.17, 1.00, 0.86,

0.73

Transmission = 13 speed 

Automated Manual 

Transmission

Gear Ratios = 12.29, 8.51, 

6.05, 4.38, 3.20, 2.29, 1.95, 

1.62, 1.38, 1.17, 1.00, 0.86, 

0.73

Drive axle Ratio = 3.55 Drive axle Ratio = 3.55 Drive axle Ratio = 3.55 Drive axle Ratio = 3.55

N/A 6x2 Axle Weighted 

Effectiveness = 0%

6x2 Axle Weighted 

Effectiveness = 0%

6x2 Axle Weighted 

Effectiveness = 0%

N/A Low Friction Axle 

Lubrication = 0.1%

Low Friction Axle 

Lubrication = 0.2%

Low Friction Axle 

Lubrication = 0.2%

N/A AMT benefit = 1.1% AMT benefit = 1.8% AMT benefit = 1.8%

N/A Predictive Cruise Control 

=0.4%

Predictive Cruise Control 

=0.8%

Predictive Cruise Control 

=0.8%

N/A Accessory Improvements = 

0.1%

Accessory Improvements 

= 0.2%

Accessory Improvements = 

0.3%

N/A Air Conditioner Efficiency 

Improvements = 0.1%

Air Conditioner Efficiency 

Improvements = 0.1%

Air Conditioner Efficiency 

Improvements = 0.2%

N/A Automatic Tire Inflation 

Systems = 0.2%

Automatic Tire Inflation 

Systems = 0.4%

Automatic Tire Inflation 

Systems = 0.4%

N/A Weight Reduction = 0 

pounds

Weight Reduction = 0 

pounds

Weight Reduction = 0 

pounds

The baseline 2017 MY heavy-haul tractor would emit 57 grams of CO2 per ton-mile and 

consume 5.6 gallons of fuel per 1,000 ton-mile. The agencies propose the heavy-haul standards 

shown in Table III-20. We welcome comment on the heavy-haul tractor technology path and 

standards proposed by the agencies.
Page 208 of 850

Table III-20 Proposed Heavy-Haul Tractor Standards

Heavy-Haul Tractor

2021 MY 2024 MY 2027 MY

Grams of CO2 per 

Ton-Mile Standard

54 52 51

Gallons of Fuel per 

1,000 Ton-Mile

5.3045 5.1081 5.010

The technology costs associated with the proposed heavy-haul tractor standards are 

shown below in Table III-21. We welcome comment on the technology costs.

Table III-21 Heavy-Haul Tractor Technology Incremental Costs in the 2021, 2024, and 2027 Model Yeara,b

Preferred Alternative vs. the Less Dynamic Baseline (2012$ per vehicle)

2021 MY 2024 MY 2027 MY

Enginec $314 $904 $1,698

Tires $81 $78 $75

Tire inflation system $180 $330 $314

Transmission $3,969 $5,883 $6,797

Axle & axle lubes $70 $128 $200

Air conditioning $45 $82 $117

Other vehicle technologies $174 $318 $302

Total $4,833 $7,723 $9,503

Notes:

a Costs shown are for the specified model year and are incremental to the costs of a tractor meeting the phase 1 

standards. These costs include indirect costs via markups along with learning impacts. For a description of the 

markups and learning impacts considered in this analysis and how it impacts technology costs for other years, refer 

to Chapter 2 of the draft RIA (see draft RIA 2.12).

b Note that values in this table include adoption rates. Therefore, the technology costs shown reflect the average cost 

expected for each of the indicated tractor classes. To see the actual estimated technology costs exclusive of adoption

rates, refer to Chapter 2 of the draft RIA (see draft RIA 2.12 in particular).

c Engine costs are for a heavy HD diesel engine meant for a combination tractor.

(e) Consistency of the Proposed Tractor Standards with the Agencies’ Legal Authority 

The proposed HD Phase 2 standards are based on adoption rates for technologies that the 

agencies regard, subject to consideration of public comment, 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.D.2(b) through (d) above; see also draft RIA Chapter 2.4. The agencies 

believe these technologies can be adopted at the estimated rates for these standards within the 

lead time provided, as discussed in draft RIA Chapter 2. The 2021 and 2024 MY standards are 

phase-in standards on the path to the 2027 MY standards and were developed using less 

aggressive application rates and therefore have lower technology package costs than the 2027 

MY standards. Moreover, we project the cost of these technologies would be rapidly recovered 

by operators due to the associated fuel savings, as shown in the payback analysis included in 

Section IX below. The cost per tractor to meet the proposed 2027 MY standards is projected to 
Page 209 of 850

range between $10,000 and $13,000 (much or all of this would be mitigated by the fuel savings 

during the first two years of ownership). The agencies note that while the projected costs are 

significantly greater than the costs projected for Phase 1, we still consider that cost to be 

reasonable, especially given the relatively short payback period. In this regard the agencies note 

that the estimated payback period for tractors of less than two years171 is itself shorter than the 

estimated payback period for light duty trucks in the 2017-2025 light duty greenhouse gas 

standards. That period was slightly over three years, see 77 FR 62926-27, which EPA found to 

be a highly reasonable given the usual period of ownership of light trucks is typically five 

years.172 The same is true here. Ownership of new tractors is customarily four to six years, 

meaning that the greenhouse gas and fuel consumption technologies pay for themselves early on 

and the purchaser sees overall savings in succeeding years – while still owning the vehicle.173 

The agencies note further that the costs for each subcategory are relatively proportionate; that is, 

costs of any single tractor subcategory are not disproportionately higher (or lower) than any 

other. Although the proposal is technology-forcing (especially with respect to aerodynamic and 

tire rolling resistance improvements), the agencies believe that manufacturers retain leeway to 

develop alternative compliance paths, increasing the likelihood of the standards’ successful 

implementation. The agencies also regard these reductions as cost-effective, even without 

considering payback period. The agencies estimate the cost per metric ton of CO2eq reduction 

without considering fuel savings to be $20 in 2030, which compares favorably with the cost per 

ton of $142 per ton (in 2030) the agencies found to be reasonable for light duty trucks.174 See 77 

FR 62922. The proposed phase-in 2021 and 2024 MY standards are less stringent and less costly

than the proposed 2027 MY standards. For these reasons, and because the agencies have 

carefully considered lead time, EPA believes they are also reasonable under Section 202(a) of 

the CAA. Given that the agencies believe the proposed standards are technically feasible, are 

highly cost effective, and highly cost effective when 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 proposed standards appear to 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). 

Based on the information before the agencies, we currently believe that Alternative 3 

would be maximum feasible and reasonable for the tractor segment for the model years in 

question. The agencies believe Alternative 4 has potential to be the maximum feasible and 

reasonable alternative; however, based on the evidence currently before us, EPA and NHTSA

have outstanding questions regarding relative risks and benefits of Alternative 4 due to the 

timeframe envisioned by the alternative. Alternative 3 is generally designed to achieve the levels 

of fuel consumption and GHG reduction that Alternative 4 would achieve, but with several years 

 

171 See Draft RIA Chapter 7.1.3.

172 Auto Remarketing. Length of Ownership Returning to More Normal Levels; New Registrations Continue Slow 

Climb. April 1, 2013. Last accessed on February 26, 2015 at http://www.autoremarketing.com/trends/lengthownership-returning-more-normal-levels-new-registrations-continue-slow-climb

173 North American Council for Freight Efficiency. Barriers to Increased Adoption of Fuel Efficiency Technologies 

in Freight Trucking. July 2013. Page 24.

174 See Draft RIA Chapter 7.1.4.
Page 210 of 850

of additional lead-time – i.e., the Alternative 3 standards would end up in the same place as the 

Alternative 4 standards, but several years later, meaning that manufacturers could, in theory, 

apply new technology at a more gradual pace and with greater flexibility. However, Alternative 

4 would provide earlier GHG benefits compared to Alternative 3.

(f) Alternative Tractor Standards Considered

The agencies developed and considered other alternative levels of stringency for the 

Phase 2 program. The results of the analysis of these alternatives are discussed below in Section 

X of the preamble. For tractors, the agencies developed the following alternatives as shown in 

Table III-22.

Table III-22 Summary of Alternatives Considered for the Proposed Rulemaking

Alternative 1 No action alternative

Alternative 2 Less Stringent than the Proposed Alternative applying off-the-shelf technologies

Alternative 3 

(Proposed Alternative)

Proposed Alternative fully phased-in by 2027 MY

Alternative 4 Alternative that pulls ahead the proposed 2027 MY standards to 2024 MY

Alternative 5 Alternative based on very high market adoption of advanced technologies

When evaluating the alternatives, it is necessary to evaluate the impact of a proposed 

regulation in terms of CO2 emission reductions, fuel consumption reductions, and technology

costs. However, it is also necessary to consider other aspects, such as manufacturers’ research 

and development resources, the impact on purchase price, and the impact on purchasers. 

Manufacturers are limited in their ability to develop and implement new technologies due to their 

human resources and budget constraints. This has a direct impact on the amount of lead time 

that is required to meet any new standards. From the owner/operator perspective, heavy-duty 

vehicles are a capital investment for firms and individuals so large increases in the upfront cost 

could impact buying patterns. Though the dollar value of the lifetime fuel savings will far 

exceed the upfront technology costs, purchasers often discount future fuel savings for a number 

of reasons. The purchaser often has uncertainty in the amount of fuel savings that can be 

expected for their specific operation due to the diversity of the heavy-duty tractor market. 

Although a nationwide perspective that averages out this uncertainty is appropriate for 

rulemaking analysis, individual operators must consider their potentially narrow operation. In 

addition, purchasers often put a premium on reliability (because downtime is costly in terms of 

towing, repair, late deliveries, and lost revenue) and may perceive any new technology as a 

potential risk with respect to reliability. Another factor that purchasers consider is the impact of 

a new technology on the resale market, which can also be impacted by uncertainty. 

The agencies selected the proposed standards over the more stringent alternatives based 

on considering the relevant statutory factors. In 2027, the proposed standards achieve up to a 24 

percent reduction in CO2 emissions and fuel consumption compared to a Phase 1 tractor at a per 

vehicle cost of approximately $13,000. Alternative 4 achieves the same percent reduction in 
Page 211 of 850

CO2 emissions and fuel consumption compared to a Phase 1 tractor, but three years earlier, at a 

per vehicle cost of approximately $14,000. The alternative standards are projected to result in 

more emission and fuel consumption reductions from the heavy-duty tractors built in model 

years 2021 through 2026.175 We project the proposed standards to be achievable within known 

design cycles, and we believe these standards would allow different paths to compliance in 

addition to the one we outline and cost here. 

The agencies solicit comment on all of these issues and again note the possibility of 

adopting, in a final action, standards that are more accelerated than those proposed in Alternative 

3. The agencies are also assuming that both the proposed standards and Alternative 4 could be 

accomplished with all changes being made during manufacturers’ normal product design cycles. 

However, we note that doing so would be more challenging for Alternative 4 and may require 

accelerated research and development outside of design cycles with attendant increased costs. 

The agencies are especially interested in seeking detailed comments on Alternative 4. Therefore, 

we are including the details of the Alternative 4 analysis below. The adoption rates considered 

for the 2021 and 2024 MY standards developed for Alternative 4 are shown below in Table 

III-23 and Table III-24. The inputs to GEM used to develop the Alternative 4 CO2 and fuel 

consumption standards are shown below in Table III-25 and Table III-26. The standards 

associated with Alternative 4 are shown below in Table III-27. Commenters are encouraged to 

address all aspects of feasibility analysis, including costs, the likelihood of developing the 

technology to achieve sufficient relaibility within the proposed lead time, and the extent to which 

the market could utilize the technology. 

(g) Derivation of Alternative 4 Tractor Standards

The adoption rates considered for the 2021 and 2024 MY standards developed for 

Alternative 4 are shown below in Table III-23 and Table III-24. The inputs to GEM used to 

develop the Alternative 4 CO2 and fuel consumption standards are shown below in Table III-25

and Table III-26. The standards associated with Alternative 4 are shown below in Table III-27. 

Commenters are encouraged to address all aspects of feasibility analysis, including costs, the 

likelihood of developing the technology to achieve sufficient relaibility within the lead time. 

 

175 See Tables III-14 and III-27.
Page 212 of 850

Table III-23 Alternative 4 Adoption Rates for 2021 MY

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

Alternative 4 2021MY Engine Technology Package

100% 100% 100% 100% 100% 100% 100% 100% 100%

Aerodynamics 

Bin I 0% 0% 0% 0% 0% 0% 0% 0% 0%

Bin II 65% 65% 0% 65% 65% 0% 65% 65% 0%

Bin III 30% 30% 35% 30% 30% 35% 30% 30% 35%

Bin IV 5% 5% 30% 5% 5% 30% 5% 5% 30%

Bin V N/A N/A 25% N/A N/A 25% N/A N/A 25%

Bin VI N/A N/A 10% N/A N/A 10% N/A N/A 10%

Bin VII N/A N/A 0% N/A N/A 0% N/A N/A 0%

Steer Tires 

Base 5% 5% 5% 5% 5% 5% 5% 5% 5%

Level 1 35% 35% 35% 35% 35% 35% 35% 35% 35%

Level 2 45% 45% 45% 45% 45% 45% 45% 45% 45%

Level 3 15% 15% 15% 15% 15% 15% 15% 15% 15%

Drive Tires 

Base 5% 5% 5% 5% 5% 5% 5% 5% 5%

Level 1 35% 35% 35% 35% 35% 35% 35% 35% 35%

Level 2 45% 45% 45% 45% 45% 45% 45% 45% 45%

Level 3 15% 15% 15% 15% 15% 15% 15% 15% 15%

Extended Idle Reduction 

APU N/A N/A N/A N/A N/A N/A 80% 80% 80%

Transmission Type 

Manual 25% 25% 25% 25% 25% 25% 25% 25% 25%

AMT 40% 40% 40% 40% 40% 40% 40% 40% 40%

Auto 30% 30% 30% 30% 30% 30% 30% 30% 30%

Dual Clutch 5% 5% 5% 5% 5% 5% 5% 5% 5%

Driveline 

Axle 

Lubricant

20% 20% 20% 20% 20% 20% 20% 20% 20%

6x2 Axle 10% 10% 20% 10% 10% 30%

Downspeed 30% 30% 30% 30% 30% 30% 30% 30% 30%

Direct Drive 50% 50% 50% 50% 50% 50% 50% 50% 50%

Accessory Improvements 

A/C 20% 20% 20% 20% 20% 20% 20% 20% 20%

Electric 

Access.

20% 20% 20% 20% 20% 20% 20% 20% 20%

Other Technologies 

Predictive 

Cruise 

Control

30% 30% 30% 30% 30% 30% 30% 30% 30%
Page 213 of 850

Automated 

Tire 

Inflation 

System

30% 30% 30% 30% 30% 30% 30% 30% 30%
Page 214 of 850

Table III-24 Alternative 4 Adoption Rates for 2024 MY

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

Alternative 4 2024MY Engine Technology Package

100% 100% 100% 100% 100% 100% 100% 100% 100%

Aerodynamics 

Bin I 0% 0% 0% 0% 0% 0% 0% 0% 0%

Bin II 50% 50% 0% 50% 50% 0% 50% 50% 0%

Bin III 40% 40% 20% 40% 40% 20% 40% 40% 20%

Bin IV 10% 10% 20% 10% 10% 20% 10% 10% 20%

Bin V N/A N/A 35% N/A N/A 35% N/A N/A 35%

Bin VI N/A N/A 20% N/A N/A 20% N/A N/A 20%

Bin VII N/A N/A 5% N/A N/A 5% N/A N/A 5%

Steer Tires 

Base 5% 5% 5% 5% 5% 5% 5% 5% 5%

Level 1 20% 20% 20% 20% 20% 20% 20% 20% 20%

Level 2 50% 50% 50% 50% 50% 50% 50% 50% 50%

Level 3 25% 25% 25% 25% 25% 25% 25% 25% 25%

Drive Tires 

Base 5% 5% 5% 5% 5% 5% 5% 5% 5%

Level 1 20% 20% 20% 20% 20% 20% 20% 20% 20%

Level 2 50% 50% 50% 50% 50% 50% 50% 50% 50%

Level 3 25% 25% 25% 25% 25% 25% 25% 25% 25%

Extended Idle Reduction 

APU N/A N/A N/A N/A N/A N/A 90% 90% 90%

Transmission Type 

Manual 10% 10% 10% 10% 10% 10% 10% 10% 10%

AMT 50% 50% 50% 50% 50% 50% 50% 50% 50%

Auto 30% 30% 30% 30% 30% 30% 30% 30% 30%

Dual Clutch 10% 10% 10% 10% 10% 10% 10% 10% 10%

Driveline

Axle 

Lubricant

40% 40% 40% 40% 40% 40% 40% 40% 40%

6x2 Axle 20% 20% 60% 20% 20% 60%

Downspeed 60% 60% 60% 60% 60% 60% 60% 60% 60%

Direct Drive 50% 50% 50% 50% 50% 50% 50% 50% 50%

Accessory Improvements 

A/C 30% 30% 30% 30% 30% 30% 30% 30% 30%

Electric 

Access.

30% 30% 30% 30% 30% 30% 30% 30% 30%

Other Technologies 

Predictive 

Cruise 

Control

40% 40% 40% 40% 40% 40% 40% 40% 40%
Page 215 of 850

Automated 

Tire 

Inflation 

System

40% 40% 40% 40% 40% 40% 40% 40% 40%

Table III-25 Alternative 4 GEM Inputs for 2021MY

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

Engine

2021MY 

11L 

Engine 

350 HP –

2% 

reduction

2021MY 

11L 

Engine 

350 HP –

2% 

reduction

2021MY 

11L 

Engine 

350 HP –

2% 

reduction

2021MY 

15L 

Engine 

455 HP –

2% 

reduction

2021MY 

15L 

Engine 

455 HP –

2% 

reduction

2021MY 

15L 

Engine 

455 HP –

2% 

reduction

2021MY 

15L 

Engine 

455 HP –

2% 

reduction

2021MY 

15L 

Engine 

455 HP –

2% 

reduction

2021MY 

15L 

Engine 

455 HP –

2% 

reduction

Aerodynamics (CdA in m2)

4.61 6.01 5.83 4.61 6.01 5.83 4.61 6.01 5.63

Steer Tires (CRR in kg/metric ton)

5.9 5.9 5.9 5.9 5.9 5.9 5.9 5.9 5.9

Drive Tires (CRR in kg/metric ton)

6.2 6.2 6.2 6.2 6.2 6.2 6.2 6.2 6.2

Extended Idle Reduction Weighted Effectiveness

N/A N/A N/A N/A N/A N/A 2.5% 2.5% 2.5%

Transmission = 10 speed Automated Manual Transmission

Gear Ratios = 12.8, 9.25, 6.76, 4.90, 3.58, 2.61, 1.89, 1.38, 1.00, 0.73

Drive axle Ratio = 3.45

6x2 Axle Weighted Effectiveness

N/A N/A N/A 0.3% 0.3% 0.8% 0.3% 0.3% 0.8%

Low Friction Axle Lubrication = 0.1%

Transmission benefit = 1.5%

Predictive Cruise Control =0.6%

Accessory Improvements = 0.2%

Air Conditioner Efficiency Improvements = 0.1%

Automatic Tire Inflation Systems = 0.3%

Weight Reduction = 0 pounds

Direct Drive Weighted Efficiency = 1% for sleeper cabs; 0.8% for day cabs
Page 216 of 850

Table III-26 Alternative 4 GEM Inputs for 2024MY

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

Engine

2021MY 

11L 

Engine 

350 HP –

4% 

reduction

2021MY 

11L 

Engine 

350 HP –

4% 

reduction

2021MY 

11L 

Engine 

350 HP –

4% 

reduction

2021MY 

15L 

Engine 

455 HP –

4% 

reduction

2021MY 

15L 

Engine 

455 HP –

4% 

reduction

2021MY 

15L 

Engine 

455 HP –

4% 

reduction

2021MY 

15L 

Engine 

455 HP –

4% 

reduction

2021MY 

15L 

Engine 

455 HP –

4% 

reduction

2021MY 

15L 

Engine 

455 HP –

4% 

reduction

Aerodynamics (CdA in m2)

4.52 5.92 5.52 4.52 5.92 5.52 4.52 5.92 5.32

Steer Tires (CRR in kg/metric ton)

5.6 5.6 5.6 5.6 5.6 5.6 5.6 5.6 5.6

Drive Tires (CRR in kg/metric ton)

5.9 5.9 5.9 5.9 5.9 5.9 5.9 5.9 5.9

Extended Idle Reduction Weighted Effectiveness

N/A N/A N/A N/A N/A N/A 3% 3% 3%

Transmission = 10 speed Automated Manual Transmission

Gear Ratios = 12.8, 9.25, 6.76, 4.90, 3.58, 2.61, 1.89, 1.38, 1.00, 0.73

Drive axle Ratio = 3.2

6x2 Axle Weighted Effectiveness

N/A N/A N/A 0.5% 0.5% 1.5% 0.5% 0.5% 1.5%

Low Friction Axle Lubrication = 0.2%

Transmission benefit = 1.8%

Predictive Cruise Control =0.8%

Accessory Improvements = 0.3%

Air Conditioner Efficiency Improvements = 0.2%

Automatic Tire Inflation Systems = 0.4%

Weight Reduction = 0 pounds

Direct Drive Weighted Efficiency = 1% for sleeper cabs; 0.8% for day cabs
Page 217 of 850

Table III-27 Tractor Standards Associated with Alternative 4

2021 Model Year CO2 Grams per Ton-Mile

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 92 74 66

Mid Roof 102 81 74

High Roof 104 82 73

2021 Model Year Gallons of Fuel per 1,000 Ton-Mile

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 9.0373 7.2692 6.4833

Mid Roof 10.0196 7.9568 7.2692

High Roof 10.2161 8.0550 7.1709

2024 Model Year CO2 Grams per Ton-Mile

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 87 70 62

Mid Roof 96 76 69

High Roof 96 76 67

2024 Model Year and Later Gallons of Fuel per 1,000 Ton-Mile

Day Cab Sleeper Cab

Class 7 Class 8 Class 8

Low Roof 8.5462 6.8762 6.0904

Mid Roof 9.4303 7.4656 6.7780

High Roof 9.4303 7.4656 6.5815

The technology costs of achieving the reductions projected in Alternative 4 are included 

below in Table III-28 and Table III-29.
Page 218 of 850

Table III-28 Class 7 and 8 Tractor Technology Incremental Costs in the 2021 Model Year 

Alternative 4 vs. the Less Dynamic Baseline a,b

(2012$ per vehicle)

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

Enginec $656 $656 $656 $656 $656 $656 $656

Aerodynamics $769 $632 $769 $632 $740 $740 $665

Tires $50 $11 $83 $18 $61 $61 $18

Tire inflation 

system

$271 $271 $271 $271 $271 $271 $271

Transmission $6,794 $6,794 $6,794 $6,794 $6,794 $6,794 $6,794

Axle & axle 

lubes

$56 $56 $75 $95 $75 $75 $115

Idle reduction 

with APU

$0 $0 $0 $0 $2,449 $2,449 $2,449

Air 

conditioning

$90 $90 $90 $90 $90 $90 $90

Other vehicle 

technologies

$261 $261 $261 $261 $261 $261 $261

Total $8,946 $8,769 $8,999 $8,816 $11,397 $11,397 $11,318

Notes:

a Costs shown are for the 2021 model year and are incremental to the costs of a tractor meeting the Phase 1 

standards. These costs include indirect costs via markups along with learning impacts. For a description of the 

markups and learning impacts considered in this analysis and how it impacts technology costs for other years, refer 

to Chapter 2 of the draft RIA (see draft RIA 2.12).

b Note that values in this table include adoption rates. Therefore, the technology costs shown reflect the average cost 

expected for each of the indicated tractor classes. To see the actual estimated technology costs exclusive of adoption

rates, refer to Chapter 2 of the draft RIA (see draft RIA 2.12 in particular).

c Engine costs are for a heavy HD diesel engine meant for a combination tractor. The engine costs in this table are 

equal to the engine costs associated with the separate engine standard because both include the same set of engine 

technologies (see Section II.D.2.e).
Page 219 of 850

Table III-29 Class 7 and 8 Tractor Technology Incremental Costs in the 2024 Model Year 

Alternative 4 vs. the Less Dynamic Baseline a,b

(2012$ per vehicle)

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

Enginec $1,885 $1,885 $1,885 $1,885 $1,885 $1,885 $1,885

Aerodynamics $805 $935 $805 $935 $773 $773 $997

Tires $50 $14 $83 $23 $63 $63 $23

Tire inflation 

system

$330 $330 $330 $330 $330 $330 $330

Transmission $7,143 $7,143 $7,143 $7,143 $7,143 $7,143 $7,143

Axle & axle 

lubes

$102 $102 $138 $210 $138 $138 $210

Idle reduction 

with APU

$0 $0 $0 $0 $2,687 $2,687 $2,687

Air 

conditioning

$123 $123 $123 $123 $123 $123 $123

Other vehicle 

technologies

$318 $318 $318 $318 $318 $318 $318

Total $10,757 $10,851 $10,826 $10,968 $13,461 $13,461 $13,717

Notes:

a Costs shown are for the 2024 model year and are incremental to the costs of a tractor meeting the Phase 1 

standards. These costs include indirect costs via markups along with learning impacts. For a description of the 

markups and learning impacts considered in this analysis and how it impacts technology costs for other years, refer 

to Chapter 2 of the draft RIA (see draft RIA 2.12).

b Note that values in this table include adoption rates. Therefore, the technology costs shown reflect the average cost 

expected for each of the indicated tractor classes. To see the actual estimated technology costs exclusive of adoption

rates, refer to Chapter 2 of the draft RIA (see draft RIA 2.12 in particular).

c Engine costs are for a heavy HD diesel engine meant for a combination tractor. The engine costs in this table are 

equal to the engine costs associated with the separate engine standard because both include the same set of engine 

technologies (see Section II.D.2.e).

E. Proposed Compliance Provisions for Tractors

In HD Phase 1, the agencies developed an entirely new program to assess the CO2

emissions and fuel consumption of tractors. The agencies propose to carry over many aspects of 

the Phase 1 compliance approach, but are proposing to enhance several aspects of the 

compliance program. The sections below highlight the key areas that are the same and those that 

are different.
Page 220 of 850

(1) HD Phase 2 Compliance Provisions That Remain the Same

The regulatory structure considerations for Phase 2 are discussed in more detail above in 

Section II. We welcome comment on all aspects of the compliance program including where we 

are not proposing any changes.

(a) Application and Certification Process

For the Phase 2 NPRM, the agencies are proposing to keep many aspects of the HD 

Phase 1 tractor compliance program. For example, the agencies propose to continue to use GEM 

(as revised for Phase 2), in coordination with additional component testing by manufacturers to 

determine the inputs, to determine compliance with the proposed fuel efficiency and CO2

standards. Another aspect that we propose to carry over is the overall compliance approach.

In Phase 1 and as proposed in Phase 2, the general compliance process in terms of the 

pre-model year, during the model year, and post model year activities remain unchanged. The 

manufacturers would continue to be required to apply for certification through a single source, 

EPA, with limited sets of data and GEM results (see 40 CFR 1037.205). EPA would issue 

certificates upon approval based on information submitted through the VERIFY database (see 40 

CFR 1037.255). In Phase 1, EPA and NHTSA jointly review and approve innovative technology

requests, i.e. performance of any technology whose performance is not measured by the GEM 

simulation tool and is not in widespread use in the 2010 MY. For Phase 2, the agencies are 

proposing a similar process for allowing credits for off-cycle technologies that are not measured 

by the GEM simulation tool (see Section I.B.v. for a more detailed discussion of off-cycle 

requests). During the model year, the manufacturers would continue to generate certification 

data and conduct GEM runs on each of the vehicle configurations it builds. After the model year 

ends, the manufacturers would submit end of year reports to EPA that include the GEM results 

for all of the configurations it builds, along with credit/deficit balances if applicable (see 40 CFR 

1037.250 and 1037.730). EPA and NHTSA would jointly coordinate on any enforcement action 

required. 

(b) Compliance Requirements

The agencies are also proposing not to change the following provisions:

 Useful life of tractors (40 CFR 1037.105(e) and 1037.106(e))

 Emission-related warranty requirements (40 CFR 1037.120)

 Maintenance Instructions, allowable maintenance, and amending maintenance 

instructions (40 CFR 1037.125 and 137.220)

 Deterioration factors (40 CFR 1037.205(l) and 1037.241(c))

 Vehicle family, subfamily, and configurations (40 CFR 1037.230)

(c) Drive Cycles and Weightings

In Phase 1, the agencies adopted three drive cycles used in GEM to evaluate the fuel 

consumption and CO2 emissions from various vehicle configurations. One of the cycles is the 

Transient mode of the California ARB Heavy Heavy-Duty Truck 5 Mode cycle. It is intended to 
Page 221 of 850

broadly cover urban driving. The other two cycles represent highway driving at 55 mph and 65 

mph.

The agencies propose to maintain the existing drive cycles and weighting. For sleeper 

cabs, the weightings would remain 5 percent of the Transient cycle, 9 percent of the 55 mph 

cycle, and 86 percent of the 65 mph cycle. The day cab results would be weighted based on 19 

percent of the transient cycle, 17 percent of the 55 mph cycle, and 64 percent of the 65 mph 

cycle (see 40 CFR 1037.510(c)). One key difference in the proposed drive cycles is the addition 

of grade, discussed below in Section III.E.2.

The 55 mph and 65 mph drive cycles used in GEM assume constant speed operation at 

nominal vehicle speeds with downshifting occurring if road incline causes a predetermined drop 

in vehicle speed. In real-world vehicle operation, traffic conditions and other factors may cause 

periodic operation at lower (e.g. creep) or variable vehicle speeds. The agencies therefore 

request comment on the need to include segments of lower or variable speed operation in the 

nominally 55 mph and 65 mph drive cycles used in GEM and how this may or may not impact 

the strategies manufacturers would develop. We also request data from fleet operators or others 

that may track vehicle speed operation of heavy-duty tractors.

(d) 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 Phase 2, we are proposing to carry over the total weight of the tractortrailer combination used in GEM for Phase 1. The agencies developed the proposed tractor curb 

weight inputs for Phase 2 from actual tractor weights measured in two of EPA’s Phase 1 test 

programs. The proposed trailer curb weight inputs were derived from actual trailer weight 

measurements conducted by EPA and from weight data provided to ICF International by the 

trailer manufacturers.176 

There is a further issue of what payload weight to assign during compliance testing. 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, this may not always be practicable. Delivery logistics may dictate partial loading. 

Some payloads, such as potato chips, may fill the trailer before it reaches the vehicle’s maximum

weight limit. Or full loads simply may not be available commercially. 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 

 

176 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.
Page 222 of 850

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).177 

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 Phase 1, 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 payloads. FHWA’s results indicated 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.

178

 The same study shows that Class 7 vehicles carried between 

18,674 and 34,210 pounds of payload also depending on average distance travelled per day. 

Based on these data, the agencies are proposing to continue to prescribe a fixed payload of 

25,000 pounds for Class 7 tractors and 38,000 pounds for Class 8 tractors for certification 

testing. The agencies propose to continue to use a common payload for Class 8 day cabs and 

sleeper cabs as a predefined GEM input because the data available do not distinguish among 

Class 8 tractor types. These proposed 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.” 

Details of the proposed individual weight inputs by regulatory category, as shown in 

Table III-30, are included in draft RIA Chapter 3. We welcome comment or new data to support 

changes to the tractor weights, or refinements to the heavy-haul tractor, trailer, and payload 

weights.

 

177 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.

178 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.
Page 223 of 850

Table III-30 Proposed Combination Tractor Weight Inputs

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

Class 8 Heavy-Haul 19,000 13,500 86,000 118,500

(e) Tire Testing

In Phase 1, the manufacturers are required to input their tire rolling resistance coefficient 

into GEM. Also in Phase 1, the agencies adopted the provisions in ISO 28580 to determine the 

rolling resistance of tires. As described in 40 CFR 1037.520(c), the agencies require that at least 

three tires for each tire design are to be tested at least one time. Our assessment of the Phase 1 

program to date indicates that these requirements reasonably balance the need for precision, 

repeatability, and testing burden. Therefore we propose to carry over the Phase 1 testing 

provisions for tire rolling resistance into Phase 2. We welcome comments regarding the 

proposed tire testing provisions.

In Phase 1, the agencies received comments from stakeholders highlighting a need to 

develop a reference lab and alignment tires for the HD sector. The agencies discussed the lab-tolab comparison conducted in the Phase 1 EPA tire test program (76 FR 57184). The agencies 

reviewed the rolling resistance 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 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 rolling resistance values. Based on the test data, the agencies 

judge for the HD Phase 2 program to continue to use the current levels of variability, and the 

agencies therefore propose to allow the use of either Smithers or STL laboratories for 

determining the tire rolling resistance value. However, we welcome comment on the need to 
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establish a reference machine for the HD sector and whether tire testing facilities are interested 

in and willing to commit to developing a reference machine.

(2) Key Differences in HD Phase 2 Compliance Provisions

We welcome comment on all aspects of the compliance program for which we are 

proposing changes.

(a) Aerodynamic Assessment

In Phase 1, the manufacturers conduct aerodynamic testing to establish the appropriate 

bin and GEM input for determining compliance with the CO2 and fuel consumption standards. 

The agencies propose to continue this general approach in HD Phase 2, but make several 

enhancements to the aerodynamic assessment of tractors. As discussed below in this section, we 

propose some modifications to the aerodynamic test procedures—the addition of wind averaged 

yaw in the aerodynamic assessment, the addition of trailer skirts to the standard trailer used to 

determine aerodynamic performance of tractors and revisions to the aerodynamic bins.

(i) Aerodynamic Test Procedures

The aerodynamic drag of a vehicle is determined by the vehicle’s coefficient of drag 

(Cd), frontal area, air density and speed. Quantifying tractor aerodynamics as an input to the 

GEM presents technical challenges because of the proliferation of tractor configurations, and 

subtle variations in measured aerodynamic values among various test procedures. In Phase 1, 

Class 7 and 8 tractor aerodynamic results are developed by manufacturers using a range of 

techniques, including wind tunnel testing, computational fluid dynamics, and constant speed 

tests. 

We continue to believe a broad approach allowing manufacturers to use these multiple 

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. However, we also 

recognize the need for consistency and a level playing field in evaluating aerodynamic 

performance. To address the consistency and level playing field concerns, NHTSA and EPA 

adopted in Phase 1, while working with industry, an approach that identified a reference 

aerodynamic test method and a procedure to align results from other aerodynamic test 

procedures with the reference method.

The agencies adopted in Phase 1 an enhanced coastdown procedure as the reference 

method (see 40 CFR 1066.310) and defined a process for manufacturers to align drag results 

from each of their own test methods to the reference method results using Falt-aero (see 40 CFR 

1037.525). Manufacturers are 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 agencies propose to continue to use this alignment method approach to maintain the testing 

flexibility that manufacturers have today. However, the agencies propose to increase the rigor in 

determining the Falt-aero for Phase 2. Beginning in 2021 MY, we propose that the 

manufacturers would be required to determine a new Falt-aero for each of their tractor models 

for each aerodynamic test method. In Phase 1, manufacturers are required to determine their 

Falt-aero using only a high roof sleeper cab with a full aerodynamics package (see 40 CFR 
Page 225 of 850

1037.525(a)(2)). In Phase 2, we propose that manufacturers would be required to determine a 

unique Falt-aero value for each major model of their high roof day cabs and high roof sleeper 

cabs. In Phase 2, we propose that manufacturers may carry over the Falt-aero value until a 

model changeover or based on the agencies’ discretion to require up to six new Falt-aero 

determinations each year. We welcome comment on the burden associated with this proposed 

change to conduct up to six coastdown tests per year per manufacturer.

Based on feedback received during the development of Phase 1, we understand that there 

is interest from some manufacturers to change the reference method in Phase 2 from coastdown 

to constant speed testing. EPA has conducted an aerodynamic test program at Southwest 

Research Institute to evaluate both methods in terms of cost of testing, testing time, testing 

facility requirements, and repeatability of results. Details of the analysis and results are included 

in draft RIA Chapter 3.2. The results showed that the enhanced coastdown test procedures and 

analysis produced results with acceptable repeatability and at a lower cost than the constant 

speed testing. Based on the results of this testing, the agencies propose to continue to use the 

enhanced coastdown procedure for the reference method in Phase 2.179 However, we welcome 

comment on the need to change the reference method for the Phase 2 final rule to constant speed 

testing, including comparisons of aerodynamic test results using both the coastdown and constant 

speed test procedures. In addition, we welcome comments on and suggested revisions to the 

constant speed test procedure specifications set forth in Chapter 3.2.2.2 of the draft RIA and 40 

CFR 1037.533. If we determine that it is appropriate to make the change, then the aerodynamic 

bins in the final rule would be adjusted to take into account the difference in absolute CdA 

values due to the change in method.

The agencies are also considering refinements to the computational fluid dynamics 

modeling method to determine the aerodynamic performance of tractors. Specifically, we are 

considering whether the conditions for performing the analysis require greater specificity (e.g., 

wind speed and direction inclusion, turbulence intensity criteria value) or if turbulence model 

and mesh deformation should be required, rather than “if applicable,” for all CFD analysis.181 

The agencies welcome comment on the proposed revisions.

In Phase 1, we adopted interim provisions in 40 CFR 1037.150(k) that accounted for 

coastdown measurement variability by allowing a compliance demonstration based on in-use test 

results if the drag area was at or below the maximum drag area allowed for the bin above the bin 

to which the vehicle was certified. Since adoption of Phase 1, EPA has conducted in-use 

aerodynamic testing and found that uncertainty associated with coastdown testing is less than 

anticipated.182 In addition, we are proposing additional enhancements in the Phase 2 coastdown 

procedures to continue to reduce the variability of coastdown results, including the impact of 

environmental conditions. Therefore, we are proposing to sunset the provision in 40 CFR 

1037.150(k) at the end of the Phase 1 program (after the 2020 model year). We request 

 

179 Southwest Research Institute. “Heavy Duty Class 8 Truck Coastdown and Constant Speed Testing.” April 

2015.

181 40 CFR 1037.531 “Computational fluid dynamics (CFD)”.

182 Southwest Research Institute. “Heavy Duty Class 8 Truck Coastdown and Constant Speed Testing.” April 2015.
Page 226 of 850

comment on whether or not we should factor in a test variability compliance margin into the 

aerodynamic test procedure, and therefore request data on aerodynamic test variability.

(ii) Wind Averaged Drag

In Phase 1, EPA and NHTSA recognized that wind conditions, most notably wind 

direction, have a greater impact on real world CO2 emissions and fuel consumption of heavyduty trucks than of light-duty vehicles.183

 As noted in the NAS report, the wind average drag 

coefficient is about 15 percent higher than the zero degree coefficient of drag. 184 In addition, the 

agencies received comments in Phase 1 that supported the use of wind averaged drag results for 

the aerodynamic determination. The agencies considered adopting the use of a wind averaged 

drag coefficient in the Phase 1 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 took this approach recognizing that the reference method is coastdown 

testing and it is not capable of determining wind averaged yaw.

185

 Wind tunnels and CFD are 

currently the only tools to accurately assess the influence of wind speed and direction on a 

truck’s aerodynamic performance. The agencies recognized, 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. 

As the tractor manufacturers continue to refine the aerodynamics of tractors, we believe 

that continuing the zero yaw approach into Phase 2 could potentially impact the overall 

technology effectiveness or change the kinds of technology decisions made by the tractor 

manufacturers in developing equipment to meet our proposed HD Phase 2 standards. Therefore, 

we are proposing aerodynamic test procedures that take into account the wind averaged drag 

performance of tractors. The agencies propose to account for this change in aerodynamic test 

procedure by appropriately adjusting the aerodynamic bins to reflect a wind averaged drag result 

instead of a zero yaw result. 

The agencies propose that beginning in 2021 MY, the manufacturers would be required 

to adjust their CdA values to represent a zero yaw value from coastdown and add the CdA 

impact of the wind averaged drag. The impact of wind averaged drag relative to a zero yaw 

condition can only be measured in a wind tunnel or with CFD. We welcome data evaluating the 

consistency of wind averaged drag measurements between wind tunnel, CFD, and other potential 

methods such as constant speed or coastdown. The agencies propose that manufacturers would 

use the following equation to make the necessary adjustments to a coastdown result to obtain the 

CdAwad value:

CdAwad = CdAzero,coastdown + (CdAwad,wind tunnel – CdAzero,wind tunnel) * Falt-aero

 

183 See 2010 NAS Report, page 95

184 See 2010 NAS Report, Finding 2-4 on page 39. Also see 2014 NAS Report, Recommendation 3.5.

185 See 2010 NAS Report. Page 95.
Page 227 of 850

If the manufacturer has a wind averaged CdA value from either a wind tunnel or CFD, 

then we propose they would use the following equation to obtain the CdAwad value:

CdAwad = CdAwad,wind tunnel or CFD * Falt-aero

We welcome comment on whether the wind averaged drag should be determined using a 

full yaw sweep as specified in Appendix A of the Society of Automotive Engineers (SAE) 

recommended practice number J1252 “SAE Wind Tunnel Test Procedure for Trucks and Buses” 

(e.g., zero degree yaw and a six other yaw angles at increments of 3 degrees or greater) or a 

subset of specific angles as currently allowed in the Phase 1 regulations.186

To reduce the testing burden the agencies propose that manufacturers have the option of 

determining the offset between zero yaw and wind averaged yaw either through testing or by 

using the EPA-defined default offset. Details regarding the determination of the offset are 

included in the draft RIA Chapter 3.2. We propose the manufacturers would use the following 

equation if they had a zero yaw coastdown value and choose not to conduct wind averaged 

measurements.

CdAwad = CdAzero,coastdown + 0.80

In addition, we propose the manufacturers would use the following equation if they had a 

zero yaw wind tunnel or CFD value and choose not to conduct wind averaged measurements.

CdAwad = (CdAzero,wind tunnel or CFD * Falt-aero)+0.80

We welcome comments on all aspects of the proposed wind averaged drag provisions.

(iii) Standard Trailer Definition

Similar to the approach the agencies adopted in Phase 1, NHTSA and EPA are proposing 

provisions such that the tractor performance in GEM is judged assuming the tractor is pulling a 

standardized trailer.187 The agencies believe that an assessment of the tractor fuel consumption 

and CO2 emissions should be conducted using a tractor-trailer combination, as tractors are 

invariably used in combination with trailers and this is their essential commercial purpose. 

Trailers, of course, also influence the extent of carbon emissions from the tractor (and viceversa). We believe that using a standardized trailer best reflects the impact of the overall weight 

of the tractor-trailer and the aerodynamic technologies in actual use, and consequent real-world 

performance, where tractors are designed and used with a trailer. EPA research confirms what 

one would intuit: tractor-trailer pairings are almost always optimized. EPA conducted an 

evaluation of over 4,000 tractor-trailer combinations using live traffic cameras in 2010. 188 The 

results showed that approximately 95 percent of the tractors were matched with the standard 

 

186 Proposed 40 CFR 1037.525(d)(2); “Yaw Sweep Corrections”.

187 See 40 CFR 1037.501(g).

188 See Memo to Docket, Amy Kopin. “Truck and Trailer Roof Match Analysis.” August 2010.
Page 228 of 850

trailer specified (high roof tractor with box trailer, mid roof tractor with tanker trailer, and low

roof with flatbed trailer). Therefore, the agencies propose that Phase 2 GEM continue to use a 

predefined typical trailer defined in Phase 1 in assessing overall performance for test purposes. 

As such, the high roof tractors would be paired with a standard box trailer; the mid roof tractors 

would be paired with a tanker trailer; and the low roof tractors would be paired with a flatbed 

trailer. 

However, the agencies are proposing to change the definition of the standard box trailer 

used by tractor manufacturers to determine the aerodynamic performance of high roof tractors in 

Phase 2. We believe this is necessary to reflect the aerodynamic improvements experienced by 

the trailer fleet over the last several years due to influences from the California Air Resources 

Board mandate189 and EPA’s SmartWay Transport Partnership. The standard box trailer used in 

Phase 1 to assess the aerodynamic performance of high roof tractors is a 53 foot box trailer 

without any aerodynamic devices. In the development of Phase 2, the agencies evaluated the 

increase in adoption rates of trailer side skirts and boat tails in the market over the last several 

years and have seen a marked increase. We estimate that approximately 50 percent of the new 

trailers sold in 2018 will have trailer side skirts.190,191 As the agencies look towards the proposed 

standards in the 2021 and beyond timeframe, we believe that it is appropriate to update the 

standard box trailer definition. In 2021-2027, we believe the trailer fleet will be a mix of trailers 

with no aerodynamics, trailers with skirts, and trailers with advanced aero; with the advanced 

aero being a very limited subset of the new trailers sold each year. Consequently, overall, we 

believe a trailer with a skirt will be the most representative of the trailer fleet for the duration of 

the regulation timeframe, and plausibly beyond. Therefore, we are proposing that the standard 

box trailer in Phase 2 - the trailer assumed during the certification process to be paired with a 

high roof tractor - be updated to include a trailer skirt starting in 2021 model year. Even though 

the agencies are proposing new box trailer standards beginning in 2018 MY, we are not 

proposing to update the standard trailer in the tractor certification process until 2021 MY, to 

align with the new tractor standards. If we were to revise the standardized trailer definition for 

Phase 1, then we would need to revise the Phase 1 tractor standards. The details of the trailer 

skirt definition are included in 40 CFR 1037.501(g)(1). 

EPA has conducted extensive aerodynamic testing to quantify the impact on the 

coefficient of drag of a high roof tractor due to the addition of a trailer skirt. Details of the test 

program and the results can be found in the draft RIA Chapter 3.2. The results of the test 

program indicate that on average, the impact of a trailer skirt matching the definition of the skirt 

specified in 40 CFR 1037.501(g)(1) is approximately 8 percent improvement in coefficient of 

drag area. This off-set was used during the development of the Phase 2 aerodynamic bins.

 

189 California Air Resources Board. Tractor-Trailer Greenhouse Gas regulation. Last viewed on September 4, 2014 

at http://www.arb.ca.gov/msprog/truckstop/trailers/trailers.htm.

190 Ben Sharpe (ICCT) and Mike Roeth (North American Council for Freight Efficiency), “Costs and Adoption 

Rates of Fuel-Saving Technologies for Trailer in the North American On-Road Freight Sector”, Feb 2014

191 Frost & Sullivan, “Strategic Analysis of North American Semi-trailer Advanced Technology Market”, Feb 2013
Page 229 of 850

We seek comment on our proposed HD Phase 2 standard trailer configuration. We also 

welcome comments on suggestions on alternative ways to define the standard trailer, such as 

developing a certified computer aided drawing (CAD) model.

(iv) Aerodynamic Bins

The agencies are proposing to continue the approach where the manufacturer would 

determine a tractor’s aerodynamic drag force through testing, determine the appropriate 

predefined aerodynamic bin, and then input the predefined CdA value for that bin into the GEM. 

The agencies proposed Phase 2 aerodynamic bins reflect three changes to the Phase 1 bins – the 

incorporation of wind averaged drag, the addition of trailer skirts to the standard box trailer used 

to determine the aerodynamic performance of high roof tractors, and the addition of bins to 

reflect the continued improvement of tractor aerodynamics in the future. Because of each of 

these changes, the aerodynamic bins proposed for Phase 2 are not directly comparable to the 

Phase 1 bins.

HD Phase 1 included five aerodynamic bins to cover the spectrum of aerodynamic 

performance of high roof tractors. Since the development of the Phase 1 rules, the manufacturers 

have continued to invest in aerodynamic improvements for tractors. This continued evolution of 

aerodynamic performance, both in production and in the research stage as part of the SuperTruck 

program, has consequently led the agencies to propose two additional aerodynamic technology

bins (Bins VI and VII) for high roof tractors. These two new bins would further segment the 

Phase 1 aerodynamic Bin V to recognize the difference in advanced aerodynamic technologies 

and designs. 

In both HD Phase 1 and as proposed by the agencies in Phase 2, aerodynamic Bin I 

through Bin V represent tractors sharing similar levels of technology. The first high roof 

aerodynamic category, Bin I, is designed to represent tractor bodies which prioritize appearance 

or special duty capabilities over aerodynamics. These Bin I tractors incorporate few, if any, 

aerodynamic features and may have several features that 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 in 2010. The agencies developed this bin to incorporate conventional 

tractors which capitalize on a generally aerodynamic shape and avoid classic features which 

increase drag. High roof tractors within Bin III build on the basic aerodynamics of Bin II 

tractors with added components to reduce drag in the most significant areas on the tractor, such 

as integral roof fairings, side extending gap reducers, fuel tank fairings, and streamlined 

grill/hood/mirrors/bumpers, similar to 2013 model year SmartWay tractors. 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. HD Phase 1 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. 

For HD Phase 2, the agencies propose to segment the aerodynamic performance of these 

advanced technologies into Bins V through VII.
Page 230 of 850

In Phase 1, the agencies adopted only two aerodynamic bins for low and mid roof 

tractors. The agencies limited the number of bins to reflect the actual range of aerodynamic 

technologies effective in low and mid roof tractor applications. 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 through VII 

include features such as gap reducers and integral roof fairings which would not be appropriate 

on low and mid roof tractors. 

As Phase 2 looks to further improve the aerodynamics for high roof sleeper cabs, we 

believe it is also appropriate to expand the number of bins for low and mid roof tractors too. For 

Phase 2, the agencies are proposing to differentiate the aerodynamic performance for low and 

mid roof applications with four bins, instead of two, in response to feedback received from 

manufacturers of low and mid roof tractors related to the limited opportunity to incorporate 

aerodynamic technologies in their compliance plan. We propose that low and mid roof tractors 

may determine the aerodynamic bin based on the aerodynamic bin of an equivalent high roof 

tractor, as shown below in Table III-31.

Table III-31 Proposed Phase 2 Revisions to 40 CFR 1037.520(b)(3)

High Roof Bin Low and Mid Roof Bin

Bin I Bin I

Bin II Bin I

Bin III Bin II

Bin IV Bin II

Bin V Bin III

Bin VI Bin III

Bin VII Bin IV

The agencies developed new high roof tractor aerodynamic bins for Phase 2 that reflect 

the change from zero yaw to wind averaged drag, the more aerodynamic reference trailer, and 

the addition of two bins. Details regarding the derivation of the proposed high roof bins are 

included in Draft RIA Chapter 3.2.8. The proposed high roof tractor bins are defined in Table 

III-32. The proposed revisions to the low and mid roof tractor bins reflect the addition of two 

new aerodynamic bins and are listed in Table III-33.
Page 231 of 850

Table III-32 Proposed Phase 2 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 (CdAwad in m2)

Bin I ≥ 7.5 ≥ 7.5 ≥7.3

Bin II 6.8-7.4 6.8-7.4 6.6-7.2

Bin III 6.2-6.7 6.2-6.7 6.0-6.5

Bin IV 5.6-6.1 5.6-6.1 5.4-5.9

Bin V 5.1-5.5 5.1-5.5 4.9-5.3

Bin VI 4.7-5.0 4.7-5.0 4.5-4.8

Bin VII ≤ 4.6 ≤ 4.6 ≤ 4.4

Aerodynamic Input to GEM (CdAwad in m2)

Bin I 7.6 7.6 7.4

Bin II 7.1 7.1 6.9

Bin III 6.5 6.5 6.3

Bin IV 5.8 5.8 5.6

Bin V 5.3 5.3 5.1

Bin VI 4.9 4.9 4.7

Bin VII 4.5 4.5 4.3

Table III-33 Proposed Phase 2 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 ≥ 6.5 ≥ 5.1 ≥ 6.5 ≥ 5.1 ≥ 6.5

Bin II 4.6-5.0 6.0-6.4 4.6-5.0 6.0-6.4 4.6-5.0 6.0-6.4

Bin III 4.2-4.5 5.6-5.9 4.2-4.5 5.6-5.9 4.2-4.5 5.6-5.9

Bin IV ≤ 4.1 ≤ 5.5 ≤ 4.1 ≤ 5.5 ≤ 4.1 ≤ 5.5

Aerodynamic Input to GEM (CdA in m2)

Bin I 5.3 6.7 5.3 6.7 5.3 6.7

Bin II 4.8 6.2 4.8 6.2 4.8 6.2

Bin III 4.3 5.7 4.3 5.7 4.3 5.7

Bin IV 4.0 5.4 4.0 5.4 4.0 5.4

(b) Road Grade in the Drive Cycles

Road grade can have a significant impact on the overall fuel economy of a heavy-duty 

vehicle. Table III-34 shows the results from a real world evaluation of heavy-duty tractor-
Page 232 of 850

trailers conducted by Oak Ridge National Lab.

192

 The study found that the impact of a mild 

upslope of one to four percent led to a decrease in average fuel economy from 7.33 mpg to 4.35 

mpg. These results are as expected because vehicles consume more fuel while driving on an 

upslope than driving on a flat road because the vehicle needs to exert additional power to 

overcome the grade resistance force.193 The amount of extra fuel increases with increases in road 

gradient. On downgrades, vehicles consume less fuel than on a flat road. However, as shown in 

the fuel consumption results in Table III-34, the amount of increase in fuel consumption on an 

upslope is greater than the amount of decrease in fuel consumption on a downslope which leads 

to a net increase in fuel consumption. As an example, the data shows that a vehicle would use 

0.3 gallons per mile more fuel in a severe upslope than on flat terrain, but only save 0.1 gallons 

of fuel per mile on a severe downslope. In another study, Southwest Research Institute modeling 

found that the addition of road grade to a drive cycle has an 8 to 10 percent negative impact on

fuel economy.

194

 

Table III-34 Fuel Consumption Relative to Road Grade

Type of Terrain Average Fuel Economy

(miles per gallon)

Average Fuel Consumption 

(gallons per mile)

Severe upslope (>4%) 2.90 0.34

Mild upslope (1% to 4%) 4.35 0.23

Flat terrain (1% to 1%) 7.33 0.14

Mild downslope (-4% to -1%) 15.11 0.07

Severe downslope (<-4%) 23.50 0.04

In Phase 1, the agencies did not include road grade. However, we believe it is important 

to propose including road grade in Phase 2 to properly assess the value of technologies, such as 

downspeeding and the integration of the engine and transmission, which were not technologies 

included in the technology basis for Phase 1 and are not directly assessed by GEM in its Phase 1 

iteration. The addition of road grade to the drive cycles would be consistent with the NAS 

recommendation in the 2014 Phase 2 First Report.195

The U.S. Department of Energy and EPA have partnered to support a project aimed at 

evaluating, refining and/or developing the appropriate road grade profiles for the 55 mph and 65 

mph highway cruise duty cycles that would be used in the certification of heavy-duty vehicles to 

the Phase 2 GHG emission and fuel efficiency standards. The National Renewable Energy

Laboratory (NREL) was contracted to do this work and has since developed two pairs of

candidate, activity-weighted road grade profiles representative of U.S. limited-access highways.

To this end, NREL used high-accuracy road grade data and county-specific vehicle miles 

 

192 Oakridge National Laboratory. Transportation Energy Book, Edition 33. Table 5.10 Effect of Terrain on Class 8 

Truck Fuel Economy. 2014. Last accessed on September 19, 2014 at http://cta.ornl.gov/data/Chapter5.shtml.

193 Ibid. 

194 Reinhart, T. (2015). Commercial Medium- and Heavy-Duty (MD/HD) Truck Fuel Efficiency Technology Study –

Report #2. Washington, DC: National Highway Traffic Safety Administration.

195 National Academy of Science. “Reducing the Fuel Consumption and GHG Emissions of Medium- and HeavyDuty Vehicles, Phase Two, First Report.” 2014. Recommendation S.3 (3.6).
Page 233 of 850

traveled data. One pair of the profiles is representative of the nation’s limited-access highways 

with 55 and 60 mph speed limits, and another is representative of such highways with speed 

limits of 65 to 75 mph. The profiles are distance-based and cover a maximum distance of 12 and

15 miles, respectively. A report documenting this NREL work is in the public docket for these

proposed rules, and comments are requested on the recommendations therein.196 In addition to 

NREL work, the agencies have independently developed yet another candidate road grade profile 

for use in the 55 mph and 65 mph highway cruise duty cycles. While based on the same road 

grade database generated by NREL for U.S. restricted-access highways, its design is predicated 

on a different approach. The development of this profile is documented in the memorandum to 

the docket.197 The agencies have evaluated all of the candidate road grade profiles and have 

prepared possible alternative tractor standards based on these profiles. The agencies request 

comment on this analysis, which is available in a memorandum to the docket.198

For the proposal, the agencies developed an interim road grade profile for development of 

the proposed standards. The agencies are proposing the inclusion of an interim road grade 

profile, as shown below in Figure III-2, in both the 55 mph and 65 mph cycles. The grade profile 

was developed by Southwest Research Institute on a 12.5 mile stretch of restricted-access 

highway during on-road tests conducted for EPA’s validation of the Phase 2 version of GEM.199 

The minimum grade in the interim cycle is -2.1 percent and the maximum grade is 2.4 percent. 

The cycle spends 30 percent of the distance in grades of +/- 0.5 percent. Overall, the cycle 

spends approximately 50 percent of the time in relatively flat terrain with road gradients of less 

than 1 percent.

The agencies believe the interim cycle has sufficient representativeness based on a 

comparison to data from the Department of Transportation used in the development of the lightduty Federal Test Procedure cycle (FTP), which found approximately 55 percent of the vehicle 

miles traveled were on road gradients of less than 1 percent.200 Consequently, we expect that 

road grade profiles developed by NREL and by the agencies will not differ significantly from the 

interim profile proposed here. The agencies request data from fleet operators or others that have 

real world grade profile data.

 

196 See NREL Report “EPA Road Grade profiles” for DOE-EPA Interagency Agreement to Refine Drive Cycles for 

GHG Certification of Medium- and Heavy-Duty Vehicles, IA Number DW-89-92402501 

197 Memorandum dated April 2015 on Possible Tractor, Trailer, and Vocational Vehicle Standards Derived from 

Alternative Road Grade Profiles

198 Ibid. 

199 Southwest Research Institute. “GEM Validation”, Technical Research Workshop supporting EPA and NHTSA 

Phase 2 Standards for MD/HD Greenhouse Gas and Fuel Efficiency — December 10 and 11, 2014. Can be 

accessed at http://www.epa.gov/otaq/climate/regs-heavy-duty.htm

200 U.S. EPA. FTP Preliminary Report. May 14, 1993. Table 5-1, page 76. EPA-420-R-93-007.
Page 234 of 850

Figure III-2 Proposed Road Grade Profile for 55 mph and 65 mph Drive Cycles

-4

-2

0

2

4

0 2 4 6 8 10 12 14

Grade (%)

Distance (mi)

Road Grade on the 55 mph and 65 mph Cycles
Page 235 of 850

(c) Weight Reduction

In Phase 1, the agencies adopted regulations that provided manufacturers with the ability

to use GEM to measure emission reduction and reductions in fuel consumption resulting from 

use of high strength steel and aluminum components for weight reduction, , and to do so without 

the burden of entering the curb weight of every tractor produced. We treated such weight 

reduction in two ways in Phase 1 to account for the fact that combination tractor-trailers weighout approximately one-third of the time and cube-out approximately two-thirds of the time. 

Therefore, one-third of the weight reduction is added payload in the denominator while twothirds of the weight reduction is subtracted from the overall weight of the vehicle in GEM. See 

76 FR 57153. The agencies also allowed manufacturers to petition for off-cycle credits for 

components not measured in GEM.

NHTSA and EPA propose carrying the Phase 1 treatment of weight reduction into Phase 

2. That is, these types of weight reduction, although not part of the agencies’ technology

packages for the proposed (or alternative) standards, can still be recognized in GEM up to a 

point. In addition, the agencies propose to add additional thermoplastic components to the 

weight reduction table, as shown below in Table III-35. The thermoplastic component weight 

reduction values were developed in coordination with SABIC, a thermoplastic component 

supplier. Also, in Phase 2, we are proposing to recognize the potential weight reduction 

opportunities in the powertrain and drivetrain systems as part of the vehicle inputs into GEM. 

Therefore, we believe it is appropriate to also recognize the weight reduction associated with 

both smaller engines and 6x2 axles.201 We propose including the values listed in Table III-36

and make them available upon promulgation of the final Phase 2 rule (i.e., available even under 

Phase 1). We welcome comments on all aspects of weight reduction.

 

201 North American Council for Freight Efficiency. ”Confidence Findings on the Potential of 6x2 Axles.” 2014. 

Page 16.
Page 236 of 850

Table III-35 Proposed Phase 2 Weight Reduction Technologies for Tractors

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.)

Thermoplastic 

Weight 

Reduction (lb.)

Door (per door) 20 6

Roof (per vehicle) 60 18

Cab rear wall (per vehicle) 49 16

Cab floor (per vehicle) 56 18

Hood (per vehicle) 55 17

Hood Support Structure (per vehicle) 15 3

Hood and Front Fender (per vehicle) 65

Day Cab Roof Fairing (per vehicle) 18

Sleeper Cab Roof Fairing (per vehicle) 75 20 40

Aerodynamic Side Extender (per vehicle) 10

Fairing Support Structure (per vehicle) 35 6

Instrument Panel Support Structure (per vehicle) 5 1

Brake Drums – Drive (per 4) 140 11

Brake Drums – Non Drive (per 2) 60 8

Frame Rails (per vehicle) 440 87

Crossmember – Cab (per vehicle) 15 5

Crossmember – Suspension (per vehicle) 25 6

Crossmember – Non Suspension ( per 3) 15 5

Fifth Wheel (per vehicle) 100 25

Radiator Support (per vehicle) 20 6

Fuel Tank Support Structure (per vehicle) 40 12

Steps (per vehicle) 35 6

Bumper (per vehicle) 33 10

Shackles (per vehicle) 10 3

Front Axle (per vehicle) 60 15

Suspension Brackets, Hangers (per vehicle) 100 30

Transmission Case (per vehicle) 50 12

Clutch Housing (per vehicle) 40 10

Drive Axle Hubs (per 4) 80 20

Non Drive Front Hubs (per 2) 40 5

Driveshaft (per vehicle) 20 5

Transmission/Clutch Shift Levers (per vehicle) 20 4
Page 237 of 850

Table III-36 Proposed Phase 2 Weight Reduction Values for Other Components

Weight Reduction Technology Weight Reduction

(lb)

6x2 axle configuration in tractors 300

4x2 axle configuration in Class 8 

tractors

300

Tractor engine with displacement less 

than 14.0L

300202

CI Liquified Natural Gas tractor -600203,204

SI Compressed Natural Gas tractor -525

CI Compressed Natural Gas tractor -900

(d) GEM Inputs 

The agencies propose to continue to require the Phase 1 GEM inputs for tractors in Phase 

2. These inputs include the following:

 Steer tire rolling resistance,

 Drive tire rolling resistance,

 Coefficient of Drag Area,

 Idle Reduction, and 

 Vehicle Speed Limiter.

As discussed above in Section II.C and III.D, there are several additional inputs that are 

proposed for Phase 2. The new GEM inputs proposed for Phase 2 include the following:

 Engine information including manufacturer, model, combustion type, fuel type, 

family name, and calibration identification

 Engine fuel map,

 Engine full-load torque curve,

 Engine motoring curve,

 Transmission information including manufacturer and model

 Transmission type,

 Transmission gear ratios,

 

202 Kenworth. “Kenworth T680 with PACCAR MX-13 Engine Lowers Costs for Oregon Open-Deck Carrier.” 

Last viewed on December 16, 2014 at http://www.kenworth.com/news/news-releases/2013/december/t680-cotc.aspx

203 National Energy Policy Institute. “What Set of Conditions Would Make the Business Case to Convert Heavy 

Trucks to Natural Gas? – A Case Study.” May 1, 2012. Last accessed on December 15, 2014 at 

http://www.tagnaturalgasinfo.com/uploads/1/2/2/3/12232668/natural_gas_for_heavy_trucks.pdf

204 Westport presentation (2013). Last accessed on December 15, 2014 at 

http://www.westport.com/file_library/files/webinar/2013-06-19_CNGandLNG.pdf
Page 238 of 850

 Drive axle ratio,

 Loaded tire radius for drive tires, and 

 Other technology inputs.

The agencies welcome comments on the inclusion of these proposed technologies into 

GEM in Phase 2.

(e) Vehicle Speed Limiters and Extended Idle Provisions 

The agencies received comments during the development of Phase 1 that the Clean Air 

Act provisions to prevent tampering (Section 203 (a)(3) (A) of the Act; 42 U.S.C. 7522(a)(3)(A)) 

of vehicle speed limiters and extended idle reduction technologies would prohibit their use for 

demonstrating compliance with the Phase 1 standards. In Phase 1, the agencies adopted 

provisions to allow for discounted credits for idle reduction technologies that allowed for 

override conditions and expiring engine shutdown systems (see 40 CFR 1037.660). Similarly, 

the agencies adopted provisions to allow for “soft top” speeds and expiring vehicle speed 

limiters, and we are not proposing to change those provisions (see 40 CFR 1037.640). However, 

as we develop Phase 2, we understand that the concerns still exist that the ability for a tractor 

manufacturer to reflect the use of a VSL in its compliance determination may be constrained by

the demand for flexibility in the use of VSLs by the customers. . The agencies welcome 

suggestions on how to close the gap between the provisions that would be acceptable to the 

industry while maintaining our need to ensure that modifications do not violate 42 U.S.C. 

7522(a)(3)(A). We request comment on potential approaches which would enable feedback 

mechanism between the vehicle owner/fleet that would provide the agencies the assurance that 

the benefits of the VSLs will be seen in use but which also provides the vehicle owner/fleet the 

flexibility they many need during in-use operation. More generally in our discussions with 

several trucking fleets and with the American Trucking Associations an interest was expressed 

by the fleets if there was a means by which they could participate in the emissions credit 

transactions which is currently limited to the directly regulated truck manufacturers. VSLs and 

extended idle systems were two example technologies which fleets and individual owners can 

order for a new build truck, and that from the fleet’s perspective the truck manufacturers receive 

emission credits for. The agencies do not have a specific proposal or a position on the request 

from the American Trucking Association and its members, but we request comment on whether 

or not it is appropriate to allow owners to participate in the overall compliance process for the 

directly regulated parties, if such a thing is allowed under the two agencies’ respective statutes, 

and what regulatory provisions would be needed to incorporate such an approach.

(f) Emission Control Labels

The agencies consider it crucial that authorized compliance inspectors are able to identify

whether a vehicle is certified, and if so whether it is in its certified condition. To facilitate this 

identification in Phase 1, EPA adopted labeling provisions for tractors that included several 

items. The Phase 1 tractor label must include the manufacturer, vehicle identifier such as the 

Vehicle Identification Number (VIN), vehicle family, regulatory subcategory, date of 

manufacture, compliance statements, and emission control system identifiers (see 40 CFR 

1037.135). In Phase 1, the emission control system identifiers are limited to vehicle speed 
Page 239 of 850

limiters, idle reduction technology, tire rolling resistance, some aerodynamic components, and 

other innovative and advanced technologies.

The number of proposed emission control systems for greenhouse gas emissions in Phase 

2 has increased significantly. For example, the engine, transmission, drive axle ratio, 

accessories, tire radius, wind averaged drag, predictive cruise control, and automatic tire inflation 

system are controls which can be evaluated on-cycle in Phase 2 (i.e. these technologies’ 

performance can now be input to GEM), but could not be in Phase 1. Due to the complexity in 

determining greenhouse gas emissions as proposed in Phase 2, the agencies do not believe that 

we can unambiguously determine whether or not a vehicle is in a certified condition through 

simply comparing information that could be made available on an emission control label with the 

components installed on a vehicle. Therefore, EPA proposes to remove the requirement to 

include the emission control system identifiers required in 40 CFR 1037.135(b)(6) and in 

Appendix III to 40 CFR part 1037 from the emission control labels for vehicles certified to the 

Phase 2 standards. However, the agencies may finalize requirements to maintain some label 

content to facilitate a limited visual inspection of key vehicle parameters that can be readily 

observed. Such requirements may be very similar to the labeling requirements from the Phase 1 

rulemaking, though we would want to more carefully consider the list of technologies that would 

allow for the most effective inspection. We request comment on an appropriate list of candidate 

technologies that would properly balance the need to limit label content with the interest in 

providing the most useful information for inspectors to confirm that vehicles have been properly 

built. We are not proposing to modify the existing emission control labels for tractors certified 

to the Phase 1 CO2 standards.

Under the agencies’ existing authorities, manufacturers must provide detailed build 

information for a specific vehicle upon our request. Our expectation is that this information 

should be available to us via e-mail or other similar electronic communication on a same-day

basis, or within 24 hours of a request at most. We request comment on any practical limitations 

in promptly providing this information. We also request comment on approaches that would 

minimize burden for manufacturers to respond to requests for vehicle build information and 

would expedite an authorized compliance inspector’s visual inspection. For example, the 

agencies have started to explore ideas that would provide inspectors with an electronic method to 

identify vehicles and access on-line databases that would list all of the engine-specific and 

vehicle-specific emissions control system information. We believe that electronic and Internet 

technology exists today for using scan tools to read a bar code or radio frequency identification 

tag affixed to a vehicle that would then lead to secure on-line access to a database of 

manufacturers’ detailed vehicle and engine build information. Our exploratory work on these 

ideas has raised questions about the level of effort that would be required to develop, implement 

and maintain an information technology system to provide inspectors real-time access to this 

information. We have also considered questions about privacy and data security. We request 

comment on the concept of electronic labels and database access, including any available 

information on similar systems that exist today and on burden estimates and approaches that 

could address concerns about privacy and data security. Based on new information that we 

receive, we may consider initiating a separate rulemaking effort to propose and request comment 

on implementing such an approach. 
Page 240 of 850

(g) End of Year Reports

In the Phase 1 program, manufacturers participating in the ABT program provided 90 day

and 270 day reports to EPA and NHTSA after the end of the model year. The agencies adopted 

two reports for the initial program to help manufacturers become familiar with the reporting 

process. For the HD Phase 2 program, the agencies propose to simplify reporting such that 

manufacturers would only be required to submit the final report 90 days after the end of the 

model year with the potential to obtain approval for a delay up to 30 days. We are accordingly 

proposing to eliminate the end of year report, which represents a preliminary set of ABT figures 

for the preceding year. We welcome comment on this proposed revision. 

(h) Special Compliance Provisions

In Phase 2, the agencies propose to consider the performance of the engine, transmission, 

and drivetrain in determining compliance with the Phase 2 tractor standards. With the inclusion 

of the engine’s performance in the vehicle compliance, EPA proposes to modify the prohibition 

to introducing into U.S. commerce a tractor containing an engine not certified for use in tractor 

(see 40 CFR 1037.601(d)). In Phase 2, we no longer see the need to prohibit the use of 

vocational engines in tractors because the performance of the engine would be appropriately 

reflected in GEM. We welcome comment on removing this prohibition.

The agencies also propose to change the compliance process for manufacturers seeking to 

use the off-road exclusion. During the Phase 1 program, manufacturers realized that contacting 

the agencies in advance of the model year was necessary to determine whether vehicles would 

qualify for exemption and need approved certificates of conformity. The agencies found that the 

petition process allowed at the end of the model year was not necessary and that an informal 

approval during the precertification period was more effective. Therefore, NHTSA is proposing 

to remove its off-road petitioning process in 49 CFR 535.8(h) and EPA is proposing to add 

requirements for informal approvals in 40 CFR 1037.610.

(i) Chassis Dynamometer Testing Requirement

The agencies foresee the need to continue to track the progress of the Phase 2 program 

throughout its implementation. As discussed in Section II, the agencies expect to evaluate the 

overall performance of tractors with the GEM results provided by manufacturers through the end 

of year reports. However, we also need to continue to have confidence in our simulation tool, 

GEM, as the vehicle technologies continue to evolve. Therefore, EPA proposes that the 

manufacturers conduct annual chassis dynamometer testing of three sleeper cabs tractor and two

day cab tractor and provide the data and the GEM result from each of these two tractor 

configurations to EPA (see 40 CFR 1037.665). We request comment on the costs and efficacy of 

this data submission requirement. We emphasize that this program would not be used for 

compliance or enforcement purposes.
Page 241 of 850

F. Flexibility Provisions

EPA and NHTSA are proposing two flexibility provisions specifically for heavy-duty 

tractor manufacturers in Phase 2. These are an averaging, banking and trading program for CO2

emissions and fuel consumption credits, as well as provisions for credits for off-cycle 

technologies which are not included as inputs to the GEM. Credits generated under these 

provisions can only be used within the same averaging set which generated the credit. 

The agencies are also proposing to remove or modify several Phase 1 interim provisions, 

as described below.

(1) Averaging, Banking, and Trading (ABT) Program

Averaging, banking, and trading of emission credits have been an important part of many

EPA mobile source programs under CAA Title II, and the NHTSA light-duty CAFE program. 

The agencies also included this flexibility in the HD Phase 1 program. ABT provisions are 

useful because they can help to address many potential issues of technological feasibility and 

lead-time, as well as considerations of cost. They provide manufacturers flexibilities that assist 

in the efficient development and implementation of new technologies and therefore enable new 

technologies to be implemented at a more aggressive pace than without ABT. A well-designed 

ABT program can also provide important environmental and energy security benefits by

increasing the speed at which new technologies can be implemented. Between MYs 2013 and

2014 all four tractor manufacturers are taking advantage of the ABT provisions in the Phase 1 

program. NHTSA and EPA propose to carry-over the Phase 1 ABT provisions for tractors into 

Phase 2.

The agencies propose to continue the five year credit life and three year deficit carry-over 

provisions from Phase 1 (40 CFR 1037.740(c) and 1037.745). Please see additional discussion 

in Section I.C.1.b. Although we are not proposing any additional restrictions on the use of Phase 

1 credits, we are requesting comment on this issue. Early indications suggest that positive 

market reception to the Phase 1 technologies could lead to manufacturers accumulating credits 

surpluses that could be quite large at the beginning of the proposed Phase 2 program. This 

appears especially likely for tractors. The agencies are specifically requesting comment on the 

likelihood of this happening, and whether any regulatory changes would be appropriate. For 

example, should the agencies limit the amount of credits than could be carried over from Phase 1 

or limit them to the first year or two of the Phase 2 program? Also, if we determine that large 

surpluses are likely, how should that factor into our decision on the feasibility of more stringent 

standards in MY 2021? .

We welcome comments on these proposed flexibilities and are interested in information 

that may indicate doing as proposed could distort the heavy-duty vehicle market.

(2) Off-Cycle Technology Credits

In Phase 1, the agencies adopted an emissions and fuel consumption credit generating 

opportunity that applied to innovative technologies that reduce fuel consumption and CO2

emissions. These technologies were required to not be in common use with heavy-duty vehicles 

before the 2010MY and not reflected in the GEM simulation tool (i.e., the benefits are “off-
Page 242 of 850

cycle”). See 76 FR at 57253. The agencies propose to largely continue, but redesignate the 

Phase 1 innovative technology program as part of the off-cycle program for Phase 2. In other 

words, beginning in 2021 MY all technologies that are not fully accounted for in the GEM 

simulation tool, or by compliance dynamometer testing could be considered off-cycle, including 

those technologies that may have been considered innovative technologies in Phase 1 of the 

program. The agencies propose to maintain the requirement that, in order for a manufacturer to 

receive credits for Phase 2, the off-cycle technology would still need to meet the requirement that 

it was not in common use prior to MY 2010. For additional information on the treatment of offcycle technologies see Section I.C.1.c.

The agencies are proposing a split process for handling off-cycle technologies in Phase 2. 

First, there is a set of predefined off-cycle technologies that are entering the market today, but 

could be fully-recognized in our proposed HD Phase 2 certification procedures. Examples of 

such technologies include predictive cruise control, 6x2 axles, axle lubricants, automated tire 

inflation systems, and air conditioning efficiency improvements. For these technologies, the 

agencies propose to define the effectiveness value of these technologies similar to the approach 

taken in the MY2017-2025 light-duty rule (see 77 FR at 62832-840 (October 15, 2012)). These 

default effectiveness values could be used as valid inputs to Phase 2 GEM. The proposed 

effectiveness value of each technology is discussed above in Section III.D.2.

The agencies also recognize that there are emerging technologies today that are being 

developed, but would not be accounted for in the GEM inputs, therefore would be considered 

off-cycle. These technologies could include systems such as efficient steering systems, cooling 

fan optimization, and further tractor-trailer integration. These off-cycle technologies could 

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.

The agencies propose that the approval for Phase 1 innovative technology credits 

(approved prior to 2021 MY) would be carried into the Phase 2 program on a limited basis for 

those technologies where the benefit is not accounted for in the Phase 2 test procedure. 

Therefore, the manufacturers would not be required to request new approval for any innovative 

credits carried into the off-cycle program, but would have to demonstrate the new cycle does not 

account for these improvements beginning in the 2021 MY. The agencies believe this is 

appropriate because technologies, such as those related to the transmission or driveline, may no 

longer be “off-cycle” because of the addition of these technologies into the Phase 2 version of 

GEM. The agencies also seek comments on whether off-cycle technologies in the Phase 2 

program should be limited by infrequent common use and by what model years, if any. We also 

seek comments on an appropriate penetration rate for a technology not to be considered in 

common use.

As in Phase 1, the agencies are proposing to continue to provide two paths for approval 

of the test procedure to measure the CO2 emissions and fuel consumption reductions of an offcycle technology used in the HD tractor. See proposed 40 CFR 1037.610 and 49 CFR 535.7. 

The first path would not require a public approval process of the test method. A manufacturer 

could use “pre-approved” test methods for HD vehicles including the A-to-B chassis testing, 
Page 243 of 850

powerpack testing or on-road testing. A manufacturer may also use any developed test 

procedure that has known quantifiable benefits. A test plan detailing the testing methodology

would be required to be approved prior to collecting any test data. The agencies are also 

proposing to continue the second path, which includes a public approval process of any testing 

method that could have questionable benefits (i.e., an unknown usage rate for a 

technology). Furthermore, the agencies are proposing to modify their provisions to clarify what

documentation must be submitted for approval, which would align them with provisions in 40 

CFR 86.1869-12. NHTSA and EPA are also proposing to prohibit credits from technologies 

addressed by any of NHTSA’s crash avoidance safety rulemakings (i.e., congestion management 

systems). See 77 FR 62733/2-3 (discussing similar issues in the context of the light-duty fuel 

economy and greenhouse gas reduction standards). We welcome recommendations on how to 

improve or streamline the off-cycle technology approval process. 

(3) Post Useful Life Modifications

Under 40 CFR part 1037, it is generally prohibited for any person to remove or render 

inoperative any emission control device installed to comply with the requirements of part 1037. 

However, in 40 CFR 1037.655 EPA clarifies that certain vehicle modifications are allowed after 

a vehicle reaches the end of its regulatory useful life. This section applies for all vehicles subject 

to 40 CFR part 1037 and would thus apply for trailers regulated in Phase 2. EPA is proposing to 

continue this provision and requests comment on it. 

This section states (as examples) that it is generally allowable to remove tractor roof 

fairings after the end of the vehicle’s useful life if the vehicle will no longer be used primarily to 

pull box trailers, or to remove other fairings if the vehicle will no longer be used significantly on 

highways with vehicle speed of 55 miles per hour or higher. More generally, this section 

clarifies that owners may modify a vehicle for the purpose of reducing emissions, provided they

have a reasonable technical basis for knowing that such modification will not increase emissions 

of any other pollutant. This essentially requires the owner to have information that would lead 

an engineer or other person familiar with engine and vehicle design and function to reasonably 

believe that the modifications will not increase emissions of any regulated pollutant. Thus, this 

provision does not provide a blanket allowance for modifications after the useful life.

This section also makes clear that no person may ever disable a vehicle speed limiter 

prior to its expiration point, or remove aerodynamic fairings from tractors that are used primarily 

to pull box trailers on highways. It is also clear that this allowance does not apply with respect to 

engine modifications or recalibrations. 

This section does not apply with respect to modifications that occur within the useful life 

period, other than to note that many such modifications to the vehicle during the useful life and 

to the engine at any time are presumed to violate 42 U.S.C 7522(a)(3)(A). EPA notes, however, 

that this is merely a presumption, and would not prohibit modifications during the useful life 

where the owner clearly has a reasonable technical basis for knowing that the modifications 

would not cause the vehicle to exceed any applicable standard.
Page 244 of 850

(4) Other Interim Provisions

In HD Phase 1, EPA adopted provisions to delay the onboard diagnostics (OBD) 

requirements for heavy-duty hybrid powertrains (see 40 CFR 86.010-18(q)). This provision 

delayed full OBD requirements for hybrids until 2016 and 2017 model years. In discussion with 

manufacturers during the development of Phase 2, the agencies have learned that meeting the onboard diagnostic requirements for criteria pollutant engine certification continues to be a 

potential impediment to adoption of hybrid systems. See Section XIV.A.1 for a discussion of 

regulatory changes proposed to reduce the non-GHG certification burden for engines paired with 

hybrid powertrain systems. 

(5) Phase 1 Flexibilities Not Proposed for Phase 2

The Phase 1 advanced technology credits were adopted to promote the implementation of 

advanced technologies, such as hybrid powertrains, Rankine cycle engines, all-electric vehicles, 

and fuel cell vehicles (see 40 CFR 1037.150(i)). As the agencies stated in the Phase 1 final rule, 

the Phase 1 standards were not premised on the use of advanced technologies but we expected 

these advanced technologies to be an important part of the Phase 2 rulemaking (76 FR 57133, 

September 15, 2011). The proposed HD Phase 2 heavy-duty engine and tractor standards are 

premised on the use of Rankine-cycle engines, therefore the agencies believe it is no longer 

appropriate to provide extra credit for this technology. While the agencies have not premised the 

proposed HD Phase 2 tractor standards on hybrid powertrains, fuel cells, or electric vehicles, we 

also foresee some limited use of these technologies in 2021 and beyond. Therefore, we propose 

to not provide advanced technology credits in Phase 2 for any technology, but we welcome 

comments on the need for such incentive.

Also in Phase 1, the agencies adopted early credits to create incentives for manufacturers 

to introduce more efficient engines and vehicles earlier than they otherwise would have planned 

to do (see 40 CFR 1037.150(a)). The agencies are not proposing to extend this flexibility to 

Phase 2 because the ABT program from Phase 1 will be available to manufacturers in 2020 

model year and this would displace the need for early credits. 
Page 245 of 850

IV. Trailers

As mentioned in Section III, trailers pulled by Class 7 and 8 tractors (together considered 

“tractor-trailers”) account for approximately two-thirds of the heavy-duty sector’s total CO2

emissions and fuel consumption. Because neither trailers nor the tractors that pull them are 

useful by themselves, it is the combination of the tractor and the trailer that forms the useful 

vehicle. Although trailers do not directly generate exhaust emissions or consume fuels (except 

for the refrigeration units on refrigerated trailers), their designs and operation nevertheless 

contribute substantially to the CO2 emissions and diesel fuel consumption of the tractors pulling 

them. See also Section I.E (1) and (2) above. 

The agencies are proposing standards for trailers specifically designed to be drawn by

Class 7 and 8 tractors when coupled to the tractor’s fifth wheel. The agencies are not proposing 

standards for trailers designed to be drawn by vehicles other than tractors, and those that are 

coupled to vehicles with pintle hooks or hitches instead of a fifth wheel. These proposed 

standards are expressed as CO2 and fuel consumption standards, and would apply to each trailer 

with respect to the emissions and fuel consumption that would be expected for a specific 

standard type of tractor pulling such a trailer. Note that this approach is discussed in more detail 

later. Nevertheless, EPA and NHTSA believe it is appropriate to establish standards for trailers 

separately from tractors because they are separately manufactured by distinct companies; the 

agencies are not aware of any manufacturers that currently assemble both the finished tractor and 

the trailer. 

A. Summary of Trailer Consideration in Phase 1

In the Phase 1 program, the agencies did not regulate trailers, but discussed how we 

might do so in the future (see 76 FR 57362). We chose not to regulate trailers at that time, 

primarily because of the lack of a proposed test procedure, as well as the technical and policy

issues at that time. The agencies also noted the large number of small businesses in this industry, 

the possibility that regulations would substantially impact these small businesses, and the 

agencies’ consequent obligations under the Small Business Regulatory Enforcement Fairness 

Act.205 However, the agencies did indicate the potential CO2 and fuel consumption benefits of 

including trailers in the program and we committed to consider establishing standards for trailers 

in future rulemakings. 

In the Phase 1 proposal, the agencies solicited general comments on controlling CO2

emissions and fuel consumption through future trailer regulations (see 75 FR at 74345-51). 

 

205The Regulatory Flexibility Act (RFA), as amended by the Small Business Regulatory Enforcement Fairness Act 

(SBREFA), requires agencies to account for economic impacts of all rules that may have a significant impact on a 

substantial number of small businesses and in addition contains provisions specially applicable to EPA requiring a 

multi-agency pre-proposal process involving outreach and consultation with representatives of potentially affected 

small businesses. See http://www.epa.gov/rfa/ for more information. Note that for this Phase 2 proposal, EPA has 

completed a Small Business Advocacy Review panel process that included small trailer manufacturers, as discussed 

in XIV.C below.
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Although we neither proposed nor finalized trailer regulations at that time, the agencies have 

considered those comments in developing this proposal. This notice proposes the first EPA 

regulations covering trailer manufacturers for CO2 emissions (or any other emissions), and the 

first fuel consumption regulations by NHTSA for these manufacturers. The agencies intend for 

this program to be a unified national program so that when a trailer model complies with EPA’s 

standards it will also comply with NHTSA’s standards. 

B. The Trailer Industry

(1) Industry Characterization

The trailer industry encompasses a wide variety of trailer applications and designs. 

Among these are box trailers (dry vans and refrigerated vans of all sizes) and “non-box” trailers, 

including platform (sometimes called “flatbed”), tanker, container chassis, bulk, dump, grain, 

and many specialized types of trailers, such as car carriers, pole trailers, and logging trailers. 

Most trailers are designed for predominant use on paved streets, roads, and highways (called 

“highway trailers” for purposes of this proposed rule). A relatively small number of trailers are 

designed for dedicated use in logging and mining operations or for use in applications that we 

expect would involve little or no time on paved roadways. A more detailed description of the 

characteristics that distinguish these trailers is included in Section IV.C.(5).

The trailer manufacturing industry is very competitive, and manufacturers are highly 

responsive to their customers’ diverse demands. The wide range of trailer designs and features 

reflects the broad variety of customer needs, chief among them typically being the ability to 

maximize the amount of freight the trailer can transport. Other design goals reflect the 

numerous, more specialized customer needs. 

Box trailers are the most common type of trailer and are made in many different lengths, 

generally ranging from 28 feet to 53 feet. While all have a rectangular shape, they can vary

widely in basic construction design (internal volume and weight), materials (steel, fiberglass 

composites, aluminum, and wood) and the number and configuration of axles (usually two axles 

closely spaced, but number and spacing of axles can be greater). Box trailer designs may also 

include additional features, such as one or more side doors, out-swinging or roll-up rear doors, 

side or rear lift gates, and numerous types of undercarriage accessories. 

Non-box trailers are uniquely designed to transport a specific type of freight. Platform 

trailers carry cargo that may not be easily contained within or loaded and unloaded into a box 

trailer, such as large, nonuniform equipment or machine components. Tank trailers are often 

pressure-tight enclosures designed to carry liquids, gases or bulk, dry solids and semi-solids. 

There are also a number of other specialized trailers such as grain, dump, automobile hauler, 

livestock trailers, construction and heavy-hauling trailers.

Chapter 1 of the Draft RIA includes a more thorough characterization of the trailer 

industry. The agencies have considered the variety of trailer designs and applications in 

developing the proposed CO2 emissions and fuel consumption standards for trailers. 
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(2) Historical Context for Proposed Trailer Provisions

(a) SmartWay Program 

EPA’s voluntary SmartWay Transport Partnership program encourages businesses to take 

actions that reduce fuel consumption and CO2 emissions while cutting costs. (See Section I.A.2.f 

above). SmartWay staff work with the shipping, logistics, and carrier communities to identify

low carbon strategies and technologies across their transportation supply chains. It is a 

voluntary, fleet-targeted program that provides an objective ranking of a fleet’s freight efficiency

relative to its competitors. SmartWay Partners commit to adopting fuel-saving practices and 

technologies relative to a baseline year as well as tracking their progress. 

EPA’s SmartWay program has accelerated the availability and market penetration of 

advanced, fuel efficient technologies and operational practices. In conjunction with the 

SmartWay Partners Program, EPA established a testing, verification, and designation program, 

the SmartWay Technology Program, to help freight companies identify the equipment, 

technologies, and strategies that save fuel and lower emissions. SmartWay verifies the 

performance of aerodynamic equipment and low rolling resistance tires and maintains a list of 

verified technologies on its website. The trailer aerodynamic technologies verified are grouped 

in bins that represent one percent, four percent, or five percent fuel savings relative to a typical 

long-haul tractor-trailer at 65-mph cruise conditions. Historically, use of verified aerodynamic 

devices totaling at least five percent fuel savings, along with verified tires, qualifies a 53-foot dry

van trailer for the “SmartWay Trailer” designation. In 2014, EPA expanded the program to 

qualify trailers as “SmartWay Elite” if they use verified tires and aerodynamic equipment 

providing nine percent or greater fuel savings. The 2014 updates also expanded the SmartWaydesignated trailer eligibility to include 53-foot refrigerated van trailers in addition to 53-foot dry

van trailers. 

The SmartWay Technology Program continues to improve the technical quality of data 

that EPA and stakeholders need for verification. EPA bases its SmartWay verifications on 

common industry test methods using SmartWay-specified testing protocols. Historically, 

SmartWay’s aerodynamic equipment verification was performed using the SAE J1321 test 

procedure, which measures fuel consumption as the test vehicle drives laps around a test track. 

Under SmartWay’s 2014 updates, EPA expanded its trailer designation and equipment 

verification programs to allow additional testing options. The updates included a new, more 

stringent 2014 track test protocol based on SAE’s 2012 update to its SAE J1321 test method,206

as well as protocols for wind tunnel, coastdown, and possibly computational fluid dynamics 

(CFD) approaches. These new protocols are based on stakeholder input, the latest industry 

standards (i.e., 2012 versions of the SAE fuel consumption and wind tunnel test207 methods), 

EPA’s own testing and research, and lessons learned from years of implementing technology

 

206 SAE International, Fuel Consumption Test Procedure - Type II. SAE Standard J1321. Revised 2012-02-06. 

Available at: http://standards.sae.org/j1321_201202/

207 SAE International. Wind Tunnel Test Procedure for Trucks and Buses. SAE Standard J1252. Revised 2012-07-

16. Available at: http://standards.sae.org/j1252_201207/
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verification programs. Wind tunnel, coastdown, and CFD testing produce values for 

aerodynamic drag improvements in terms of coefficient of drag (CD), which is then related to 

projected fuel savings using a mathematical curve.208

SmartWay verifies tires based on test data submitted by tire manufacturers demonstrating 

the coefficient of rolling resistance (CRR) of their tires using either the SAE J1269 or ISO 28580 

test methods. These verified tires have rolling resistance targets for each axle position on the 

tractor-trailer. SmartWay-verified trailer tires achieve a CRR of 5.1 kg/metric ton or less on the 

ISO28580 test method. An operator who replaces the trailer tires with SmartWay-verified tires 

can expect fuel consumption savings of one percent or more at a 65-mph cruise. Operators who 

apply SmartWay-verified tires on both the trailer and tractor can achieve three percent fuel 

consumption savings at 65-mph. 

Over the last decade, SmartWay partners have demonstrated measureable fuel 

consumption benefits by adding aerodynamic features and low rolling resistance tires to their 53-

foot dry van trailers. To date, SmartWay has verified over 70 technologies, including nine 

packages from five manufacturers that have received the Elite designation. The SmartWay

Transport program has worked with over 3,000 partners, the majority of which are trucking 

fleets, and broadly throughout the supply-chain industry, since 2004. These relationships, 

combined with the Technology Program’s extensive involvement in the HD vehicle technology

industry, have provided EPA with significant experience in freight fuel efficiency. Furthermore, 

the more than 10-year duration of the voluntary SmartWay Transport Partnership has resulted in 

significant fleet and manufacturer experience with innovating and deploying technologies that 

reduce CO2 emissions and fuel consumption. 

(b) California Tractor-Trailer Greenhouse Gas Regulation 

The state of California passed the Global Warming Solutions Act of 2006 (Assembly Bill 

32, or AB32), enacting the state’s 2020 greenhouse gas emissions reduction goal into law. 

Pursuant to this Act, the California Air Resource Board (CARB) was required to begin 

developing early actions to reduce GHG emissions. As a part of a larger effort to comply with 

AB32, the California Air Resource Board issued a regulation entitled “Heavy-Duty Greenhouse 

Gas Emission Reduction Regulation” in December 2008. 

This regulation reduces GHG emissions by requiring improvement in the efficiency of 

heavy-duty tractors and 53 foot or longer dry and refrigerated box trailers that operate in 

California.209 The program is being phased in between 2010 and 2020. Small fleets have been 

allowed special compliance opportunities to phase in the retrofits of their existing trailer fleets 

through 2017. The regulation requires affected trailer fleet owners to either use SmartWay-

 

208 McCallen, R., et al. Progress in Reducing Aerodynamic Drag for Higher Efficiency of Heavy Duty Trucks 

(Class 7-8). SAE Technical Paper. 1999-01-2238. 

209 Recently, in December 2013, ARB adopted regulations that establish its own parallel Phase 1 program with 

standards consistent with the EPA Phase 1 tractor standards. On December 5, 2014 California’s Office of 

Administrative Law approved ARB’s adoption of the Phase 1 standards, with an effective date of December 5, 2014
Page 249 of 850

verified trailers or to retrofit trailers with SmartWay-verified technologies. The efficiency

improvements are achieved through the use of aerodynamic equipment and low rolling resistance 

tires on both the tractor and trailer. EPA has granted a waiver for this California program.210

(c) NHTSA Safety-Related Regulations for Trailers and Tires

NHTSA regulates new trailer safety through regulations. Table IV-1 lists the current 

regulations in place related to trailers. Trailer manufacturers will continue to be required to meet 

current safety regulations for the trailers they produce. We welcome any comments on 

additional regulations that are not included and particularly those that may be incompatible with 

the regulations outlined in this proposal.

FMVSS Nos. 223 and 224211 require installation of rear guard protection on trailers. The 

definition of rear extremity of the trailer in 223 limits installation of rear fairings to a specified 

zone behind the trailer. The agencies request comment on any issues associated with installing 

potential boat tails or other rear aerodynamic fairings that would be more effective than current 

designs, given the current definition of trailer rear extremity in FMVSS 223.

Table IV-1 Current NHTSA Statutes and Regulations Related To Trailers

Reference Title

49 CFR 565 Vehicle Identification Number (VIN) Requirements 

49 CFR 566 Manufacturer Identification 

49 CFR 567 Certification 

49 CFR 568 Vehicles Manufactured in Two or More Stages

49 CFR 569 Regrooved Tires 

49 CFR 571 Federal Motor Vehicle Safety Standards 

49 CFR 573 Defect and Noncompliance Responsibility and Reports 

49 CFR 574 Tire Identification and Recordkeeping 

49 CFR 575 Consumer Information 

49 CFR 576 Record Retention 

(d) Additional DOT Regulations Related to Trailers 

In addition to NHTSA’s regulations, DOT’s Federal Highway Administration (FHWA) 

regulates the weight and dimensions of motor vehicles on the National Network.212 FHWA’s 

regulations limit states from setting truck size and weight limits beyond certain ranges for 

vehicles used on the National Network. Specifically, vehicle weight and truck tractor-semitrailer 

 

210 See EPA’s waiver of CARB’s heavy-duty tractor-trailer greenhouse gas regulation applicable to new 2011 

through 2013 model year Class 8 tractors equipped with integrated sleeper berths (sleeper-cab tractors) and 2011 

and subsequent model year dry-can and refrigerated-van trailers that are pulled by such tractors on California 

highways at 79 FR 46256 (August 7, 2014),

211 49 CFR 571.223, 224. 

212 23 CFR 658.9. 
Page 250 of 850

length and width are limited by FHWA.213 EPA and NHTSA do not anticipate any conflicts 

between FHWA’s regulations and those proposed in this rulemaking.

(3) Agencies’ Outreach in Developing This Proposal

In developing this proposed rule, EPA and NHTSA staff met and consulted with a wide 

range of organizations that have an interest in trailer regulations. Staff from both agencies met 

representatives of the Truck Trailer Manufacturers Association, the National Trailer Dealers 

Association, and the American Trucking Association, including their Fuel Efficiency Advisory

Committee and their Technology and Maintenance Council. We also met with and visited the 

facilities of several individual trailer manufacturers, trailer aerodynamic device manufacturing 

companies, and trailer tire manufacturers, as well as visited an aerodynamic wind tunnel test 

facility and two independent tire testing facilities. The agencies consulted with representatives 

from California Air Resources Board, the International Council on Clean Transportation, the 

North American Council for Freight Efficiency, and several environmental NGOs. 

In addition to these informal meetings, and as noted above, EPA also conducted several 

outreach meetings with representatives from small business trailer manufacturers as required 

under section 609(b) of the Regulatory Flexibility Act (RFA) and amended by the Small 

Business Regulatory Enforcement Fairness Act of 1996 (SBREFA). EPA convened a Small 

Business Advocacy Review (SBAR) Panel, and additional information regarding the findings 

and recommendations of the Panel are available in Section XIV below and in the Panel’s final 

report.214 EPA worked with NHTSA to propose flexibilities in response to EPA’s SBAR Panel 

(as outlined in Section IV. F (6) (f) with more detail provided in Chapter 12 of the draft RIA). 

We welcome comments from all entities and the public to all aspects of this proposal. 

C. Proposed Phase 2 Trailer Standards

This NPRM proposes, for the first time, a set of CO2 emission and fuel consumption 

standards for manufacturers of new trailers that would phase in over a period of nine years and 

continue to reduce CO2 emissions and fuel consumption in the years to follow. The proposed 

standards are expressed as overall CO2 emissions and fuel consumption performance standards 

considering the trailer as an integral part of the tractor-trailer vehicle. 

The agencies are proposing trailer standards that we believe well implement our 

respective statutory obligations. The agencies believe that a proposed set of standards with 

similar stringencies, but less lead-time (referred to as “Alternative 4” and discussed in more 

detail later) has the potential to be the maximum feasible alternative within the meaning of 

section 32902 (k) of EISA, and appropriate under EPA’s CAA authority (sections 202 (a)(1) and 

(2)). However, based on the evidence currently before us, EPA and NHTSA have outstanding 

 

213 23 CFR 658. 

214 Final Report of the Small Business Advocacy Review Panel on EPA’s Planned Proposed Rule: Greenhouse Gas 

Emissions and Fuel Efficiency Standards for Medium- and Heavy-Duty Engines and Vehicles: Phase 2, January 15, 

2015
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questions regarding relative risks and benefits of Alternative 4 due to the timeframe envisioned 

by that alternative. The proposed alternative (referred to as “Alternative 3” and discussed in 

more detail later) is generally designed to achieve the levels of fuel consumption and GHG 

reduction that Alternative 4 would achieve, but with several years of additional lead-time. Put 

another way, the Alternative 3 standards would result in the same stringency as the Alternative 4 

standards, but several years later, meaning that manufacturers could, in theory apply new 

technology at a more gradual pace and with greater flexibility. Additional lead-time will also 

provide for a more gradual implementation of full compliance program, which could be 

especially helpful for this newly-regulated trailer industry. It is possible that the agencies could 

adopt, in full or in part, stringencies from Alternative 4 in the final rule. The agencies seek 

comment on the lead-time and market penetration in these alternatives. 

The agencies are not proposing standards for CO2 emissions and fuel consumption from 

the transport refrigeration units (TRUs) used on refrigerated box trailers. Additionally, EPA is 

not proposing standards for hydrofluorocarbon (HFC) emissions from TRUs. See Section IV. C. 

(4) 

It is worth noting that the proposed standards for box trailers are based in part on the 

expectation that the proposed program would allow emissions averaging. However, as discussed 

in Section I. A. below, given the specific structure and competitive nature of the trailer industry, 

we request comment on the advantages and disadvantages of implementing the proposed 

standards without an averaging program. Commenters addressing the stringency of the proposed 

standards are encouraged to address stringency in the context of compliance programs with and 

without averaging.

(1) Trailer Designs Covered By This Proposed Rule

As described previously, the trailer industry produces many different trailer designs for 

many different applications. The agencies are proposing standards for a majority of these 

trailers. Note that these proposed regulations apply to trailers designed for being drawn by a 

tractor when coupled to the tractor’s fifth wheel. As described in detail in Section IV.C below, 

the agencies are proposing standards that would phase in between MY 2018 and 2027; the 

NHTSA standards would be voluntary until MY 2021. The proposed standards would apply to 

most types of trailers. For most box trailers, these standards would be based on the use of 

various technologies to improve aerodynamic performance, and on improved tire efficiency 

through low rolling resistance tires and use of automatic tire inflation (ATI) systems. As 

discussed below, the agencies have identified some trailers with characteristics that limit the 

aerodynamics that can be applied, and are proposing reduced the stringencies for those trailer 

types. As described in Sections IV.D. (1)(d) and (2)(d) below, although manufacturers can 

reduce trailer weight to reduce fuel costs by reducing trailer weight, these standards are not 

predicated on weight reduction for the industry.

The most comprehensive set of proposed requirements would apply to long box trailers, 

which include refrigerated and non-refrigerated (dry) vans. Long box trailers are the largest 

trailer category and are typically paired with high roof cab tractors that have high annual vehicle 

miles traveled (VMT) and high average speeds, and therefore offer the greatest potential for CO2

and fuel consumption reductions. Many of the aerodynamic and tire technologies considered for 
Page 252 of 850

long box trailers in this proposal are similar to those used in EPA’s SmartWay program and 

required by California’s Heavy-Duty Greenhouse Gas Emission Reduction Regulation. Many

manufacturers and operators of box trailers have experience with these CO2- and fuel 

consumption-reducing technologies. In addition to SmartWay partners and those fleets affected 

by the California regulation, many operators also seek such technologies in response to high fuel 

prices and the prospect of improved fuel efficiency. As a result, more data about the 

performance of these technologies exist for long box trailers than for other trailer types. Short 

box vans do not have the benefit of programs such as SmartWay to provide an incentive for 

development of and a reliable evaluation and promotion of CO2- and fuel consumption-reducing 

technologies for their trailers. In addition, short box trailers are more frequently used in shorthaul and urban operations, which may limit the potential effectiveness of these technologies. As 

such, EPA is proposing less stringent requirements for manufacturers of short box trailers. 

Some trailer designs include features that can affect the practicality or the effectiveness 

of devices that manufacturers may consider to lower their CO2 emissions and fuel consumption. 

We are proposing to recognize box trailers that are restricted from using aerodynamic devices in 

one location on the trailer as “partial-aero” box trailers.215 The proposed standards for these 

trailers are based on the proposed standards for full-aero box-trailers, but would be less stringent 

than when the program is fully phased in. 

We propose that box trailers that have work-performing devices in two locations such 

that they inhibit the use of all practical aerodynamic devices be considered “non-aero” box 

trailers in this proposal. The proposed standards for non-aero box trailers are predicated on the 

use of tire technologies -- lower rolling resistance tires and ATI. We are proposing similar 

standards for non-box trailers (including applications such as dump trailers and agricultural 

trailers that are designed to be used both on and off the highway). 

We are proposing to completely exclude several types of trailers from this trailer 

program. These excluded trailers would include those designed for dedicated in-field operations 

related to logging and mining. In addition, we are proposing to exclude heavy-haul trailers and 

trailers the primary function of which is performed while they are stationary. For all of these 

excluded trailers, manufacturers would not have any regulatory requirements under this program, 

and would not be subject to the proposed trailer compliance requirements. We seek comment on 

the appropriateness of excluding these types of trailers from the proposed trailer program and 

whether other trailer designs should be excluded. Section IV. C. (5) discusses these trailer types 

we propose to exclude and the physical characteristics that would define these trailers. 

In summary, the agencies are proposing separate standards for ten trailer subcategories:

 

215 Examples of types of work-performing components, equipment, or designs that the agencies might consider as 

warranting recognition as partial-aero or non-aero trailers include side or end lift gates, belly boxes, pull-out 

platforms or steps for side door access, and drop-deck designs. See 40 CFR 1037.107 and 49 CFR 535.5(e).
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– Long box (longer than 50 feet216) dry vans

– Long box (longer than 50 feet) refrigerated vans

– Short box (50 feet and shorter) dry vans

– Short box (50 feet and shorter) refrigerated vans

– Partial-aero long box dry vans

– Partial-aero long box refrigerated vans

– Partial-aero short box dry vans

– Partial-aero short box refrigerated vans

– Non-aero box vans (all lengths of dry and refrigerated vans)

– Non-box trailers (tanker, platform, container chassis, and all other types of highway

trailers that are not box trailers)

As discussed in the next section, partial-aero box trailers would have the same standards 

as their corresponding full-aero trailers in the early phase-in years, and would have separate, less 

stringent standards as the program is fully implemented. Section IV. C. (5) introduces these 

proposed partial-aero trailer standards and Section IV. D. describes the technologies that could 

be applied to meet these proposed standards. 

(2) Proposed Fuel Consumption and CO2 Standards

As described in previously, it is the combination of the tractor and the trailer that form 

the useful vehicle, and trailer designs substantially affect the CO2 emissions and diesel fuel 

consumption of the tractors pulling them. Note that although the agencies are proposing new 

CO2 and fuel consumption standards for trailers separately from tractors, we set the numerical 

level of the trailer standards (see Section IV.D below) in relation to “standard” reference tractors 

in recognition of their interrelatedness. In other words, the regulatory standards refer to the 

simulated emissions and fuel consumption of a standard tractor pulling the trailer being certified.

The agencies project that these proposed standards, when fully implemented in MY 

(model year) 2027, would achieve fuel consumption and CO2 emissions reductions of three to 

eight percent, depending on trailer subcategory. These projected reductions assume a degree of 

technology adoption into the future absent the proposed program and are evaluated on a 

weighted drive cycle (see Section IV. D. (3) . We expect that the MY 2027 standards would be 

met with high-performing aerodynamic and tire technologies largely available in the marketplace 

today. With a lead-time of more than 10 years, the agencies believe that both trailer construction 

and bolt-on CO2- and fuel consumption-reducing technologies will advance well beyond the 

performance of their current counterparts that exist today. A description of technologies that the 

agencies considered for this proposal is provided in Section IV. D. 

The agencies designed this proposed trailer program to ensure a gradual progression of 

both stringency and compliance requirements in order to limit the impact on this newly-regulated 

 

216 Most long trailers are 53 feet in length; we are proposing a cut-point of 50 feet to avoid an unintended incentive 

for an OEM to slightly shorten a trailer design in order to avoid the new regulatory requirements. 
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industry. The agencies are proposing progressively more stringent standards in three-year stages 

leading up to the MY 2027.217 The agencies are proposing several options to reduce compliance 

burden (see Section I. A. ) in the early years as the industry gains experience with the program. 

EPA is proposing to initiate its program in 2018 with modest standards for long box dry and 

refrigerated vans that can be met with common SmartWay-verified aerodynamic and tire 

technologies. In this early stage, we expect that manufacturers of the other trailer subcategories 

would meet those standards by using tire technologies only. Standards that we propose for the 

next stages, which we propose to begin in MY 2021, MY 2024, and MY 2027, would gradually 

increase in stringency for each subcategory, including the introduction of standards for shorter 

box vans that we expect would be met by applying both aerodynamic and tire technologies. 

NHTSA’s regulations would be voluntary until MY 2021 as described in Section IV. C. (3) .

Table IV-2 below presents the CO2 and fuel consumption phase-in standards, beginning 

in MY 2018 that the agencies are proposing for trailers. The standards are expressed in grams of 

CO2 per ton-mile and gallons of fuel per 1000 ton-miles to reflect the load-carrying capacity of 

the trailers. Partial-aero trailers would be subject to the same standards as their corresponding 

“full aero” trailers for MY 2018 through MY 2026. In MY 2027 and the years to follow, partialaero trailers would continue to meet the standards for MY 2024. 

The agencies are not proposing CO2 or fuel consumption standards predicated on 

aerodynamic improvements for non-box trailers or non-aero box vans at any stage of this 

proposed program. Instead, we are proposing design standards that would require manufacturers 

of these trailers to adopt specific tire technologies and thus to comply without aerodynamic 

devices. We believe that this approach would significantly limit the compliance burden for these 

manufacturers and request comment on this provision.

218

 

Table IV-2 Proposed Trailer CO2 and Fuel Consumption Standards for Box Trailers

 

217 These stages are consistent with NHTSA’s stability requirements under EISA.

218 The agencies are not proposing provisions to allow averaging for non-box trailers, non-aero box trailers, or 

partial-aero box trailers, and this reduced flexibility would likely have the effect of requiring compliant tire 

technologies to be used.
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MODEL YEAR SUBCATEGORY DRY VAN REFRIGERATED VAN

LENGTH LONG SHORT LONG SHORT

2018 - 2020 EPA Standard 83 144 84 147

(CO2 Grams per Ton-Mile)

Voluntary NHTSA Standard 8.1532 14.1454 8.2515 14.4401

(Gallons per 1,000 Ton-Mile)

2021 - 2023 EPA Standard 81 142 82 146

(CO2 Grams per Ton-Mile)

NHTSA Standard 7.9568 13.9489 8.0550 14.3418

(Gallons per 1,000 Ton-Mile)

2024 - 2026 EPA Standard 79 141 81 144

(CO2 Grams per Ton-Mile)

NHTSA Standard 7.7603 13.8507 7.9568 14.1454

(Gallons per 1,000 Ton-Mile)

2027 + EPA Standard 77 140 80 144

(CO2 Grams per Ton-Mile)

NHTSA Standard 7.5639 13.7525 7.8585 14.1454

(Gallons per 1,000 Ton-Mile)

Differences in the numerical values of these standards among trailer subcategories are 

due to differences in the tractor-trailer characteristics, as well as differences in the default 

payloads, in the vehicle simulation model we used to develop the proposed standards (as 

described in Section IV. D. (3) (a) below). Lower numerical values in Table IV-2 do not 

necessarily indicate more stringent standards. For instance, the proposed standards for dry and 

refrigerated vans of the same length have the same stringency through MY 2026, but the 

standards recognize differences in trailer weight and aerodynamic performance due to the TRU 

on refrigerated vans. Trailers of the same type but different length differ in weight as well as in 

the number of axles (and tires), tractor type, payload and aerodynamic performance. Section IV. 

D. and Chapter 2.10 of the draft RIA provide more details on the characteristics of the tractortrailer vehicles, with various technologies, that are the basis for these standards. 

In developing the proposed standards for trailers, the agencies evaluated the current level 

of CO2 emissions and fuel consumption, the types and availability of technologies that could be 

applied to reduce CO2 and fuel consumption, and the current adoption rates of these 

technologies. Additionally, we considered the necessary lead-time and associated costs to the 

industry to meet these standards, as well as the fuel savings to the consumer and magnitude of 

CO2 and fuel savings that we project would be achieved as a result of these proposed standards. 

As discussed in more detail later in this preamble and in Chapter 2.10 of the draft RIA, the 

analyses of trailer aerodynamic and tire technologies that the agencies have conducted appear to 

show that these proposed standards would be the maximum feasible and appropriate in the leadtime provided under each agency’s respective statutory authorities. We ask that any comments 

related to stringency include data whenever possible indicating the potential effectiveness and 

cost of adding such devices to these vehicles.
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The agencies request comment on all aspects of these proposed standards, including 

trailers to be covered and the proposed 50-foot demarcation between “long” and “short” box 

vans, the proposed phase-in schedule, and the stringency of the standards in relation to their cost, 

CO2 and fuel consumption reductions, and on the proposed compliance provisions, as discussed 

in Section I. A. 

In addition to these proposed trailer standards, the agencies considered standards both 

less stringent and more stringent than the proposed standards. We specifically request comment 

on a set of accelerated standards that we considered, as presented in Section IV. E. This set of 

standards is predicated on performance and penetration rates of the same technologies as the 

proposed standards, but would reach full implementation three years sooner. 

(3) Lead-time Considerations

As mentioned earlier, although the agencies did not include standards for trailers in Phase 

1, box trailer manufacturers have been gaining experience with CO2- and fuel consumptionreducing technologies over the past several years, and the agencies expect that trend to continue, 

due in part to EPA’s SmartWay program and California’s Tractor-Trailer Greenhouse Gas 

Regulation. Most manufacturers of long box trailers have some experience installing these 

aerodynamic and tire technologies for customers. This experience impacts how much lead-time 

is necessary from a technological perspective. EPA is proposing CO2 emission standards for 

long box trailers for MY 2018 that represent stringency levels similar to those used for 

SmartWay verification and required for the California regulation, and thus could be met by

adopting off-the-shelf aerodynamic and tire technologies available today. The NHTSA program 

from 2018 through 2020 would be voluntary. 

Manufacturers of trailers other than 53-foot box vans do not have the benefit of programs 

such as SmartWay to provide a reliable evaluation and promotion of these technologies for their 

trailers and therefore have less experience with these technologies. As such, EPA is proposing 

less stringent requirements for manufacturers of other highway trailer subcategories beginning in 

MY 2018. We expect these manufacturers of short box trailers would adopt some aerodynamic 

and tire technologies, and manufacturers of other trailers would adopt tire technologies only, as a 

means of achieving the proposed standards. Some manufacturers of trailers other than long 

boxes may not yet have direct experience with these technologies, but the technologies they

would need are fairly simple and can be incorporated into trailer production lines without 

significant process changes. Also, the NHTSA program for these trailers would be voluntary

until MY 2021. 

The agencies believe that the burdens of installing and marketing these technologies 

would not be limiting factors in determining necessary lead-time for manufacturers of these 

trailers. Instead, we expect that the proposed first-time compliance and, in some cases, 

performance testing requirements, would be the more challenging obstacles for this newly 

regulated industry. For these reasons, we are proposing that these standards phase in over a 

period of nine years, with flexibilities that would minimize the compliance and testing burdens in 

the early years of the proposed program (see Section I. A. ). 
Page 257 of 850

As mentioned previously, EPA is proposing modest standards and several compliance 

options that would allow it to begin its program for MY 2018. However, EISA requires four 

model years of lead-time for fuel consumption standards, regardless of the stringency level or 

availability of flexibilities. Therefore, NHTSA’s proposed fuel consumption requirements would 

not become mandatory until MY 2021. Prior to MY 2021, trailer manufacturers could 

voluntarily participate in NHTSA’s program, noting that once they made such a choice, they

would need to stay in the program for all succeeding model years.219 

The agencies believe that the expected period of seven years or more between the issuing 

of the final rules and full implementation of the program would provide sufficient lead-time for 

all affected trailer manufacturers to adopt CO2- and fuel consumption-reducing technologies or 

design trailers to meet the proposed standards. 

(4) Non-CO2 GHG Emissions from Trailers

In addition to the impact of trailer design on the CO2 emissions of tractor-trailer vehicles, 

the agencies recognize that refrigerated trailers can also be a source of emissions of HFCs. 

Specifically, HFC refrigerants that are used in transport refrigeration units (TRUs) have the 

potential to leak into the atmosphere. We do not currently believe that HFC leakage is likely to 

become a major problem in the near future, and we are not proposing provisions addressing 

refrigerant leakage of trailer-related HFCs in this proposed rulemaking. TRUs differ from the 

other source categories where EPA has adopted (or proposed) to apply HFC leakage 

requirements (i.e., air conditioning). We believe trailer owners have a strong incentive to limit 

refrigerant leakage in order to maintain the operability of the trailer’s refrigeration unit and avoid 

financial liability for damage to perishable freight due to a failure to maintain the agreed-upon 

temperature and humidity conditions. In addition, refrigerated van units represent a relatively 

small fraction of new trailers. Nevertheless, we request comment on this issue, including any 

data on typical TRU charge capacity, the frequency of HFC refrigerant leakage from these units 

across the fleet, the magnitude of unaddressed leakage from individual units, and how potential 

EPA regulations might address this leakage issue. 

(5) Exclusions and Less-Stringent Standards

All trailers built before January 1, 2018 are excluded from the Phase 2 trailer program, 

and from 40 CFR Part 1037 and 49 CFR Part 535 in general (see 1037.5(g) and 535.3(d)). 

Furthermore, the proposed regulations do not apply to trailers designed to be drawn by vehicles 

other than tractors, and those that are coupled to vehicles with pintle hooks or hitches instead of a 

fifth wheel. As stated previously, we are proposing that non-box trailers that are designed for 

dedicated use with in-field operations related to logging and mining be completely excluded 

from this Phase 2 trailer program. The agencies believe that the operational capabilities of 

trailers designed for these purposes could be compromised by the use of aerodynamic devices or 

 

219 NHTSA adopted a similar voluntary approach in the first years of Phase 1 (see 76 FR at 57106).
Page 258 of 850

tires with lower rolling resistance. Additionally, the agencies are proposing to exclude trailers 

designed for heavy-haul applications and those that are not intended for highway use, as follows:

– Trailers shorter than 35 feet in length with three axles, and all trailers with four or 

more axles (including any lift axles)

– Trailers designed to operate at low speeds such that they are unsuitable for normal 

highway operation

– Trailers designed to perform their primary function while stationary

– Trailers intended for temporary or permanent residence, office space, or other 

work space, such as campers, mobile homes, and carnival trailers

– Trailers designed to transport livestock

– Incomplete trailers that are sold to a secondary manufacturer for modification to 

serve a purpose other than transporting freight, such as for offices or storage220 

Where the criteria for exclusion identified above may be unclear for specific trailer 

models, manufacturers would be encouraged to ask the agencies to make a determination before 

production begins. The agencies seek comments on these and any other trailer characteristics 

that might make the trailers incompatible with highway use or would restrict their typical 

operating speeds. 

Because the agencies are proposing that these trailers be excluded from the program, we 

are not proposing to require manufacturers to report to the agencies about these excluded trailers.

We seek comments on whether, in lieu of the exclusion of trailers from the program, the agencies 

should instead exempt these trailers from the standards, but still require reporting to the agencies 

in order to verify that a manufacturer qualifies for an exemption. In that case, exempt trailers 

would have some regulatory requirements (e.g., reporting); again, excluded trailers would have 

no regulatory requirements under this proposal. All other trailers would remain covered by the 

proposed standards. 

As described earlier, the proposed program is based on the expectation that 

manufacturers would be able to apply aerodynamic devices and tire technologies to the vast 

majority of box trailers, and these standards would be relatively stringent. We propose to 

categorize trailers with functional components or work-performing equipment, and trailers with 

certain design elements, that could partially interfere with the installation or the effectiveness of 

some aerodynamic technologies, as “partial-aero” box trailers. For example, some trailer 

equipment by their placement or their need for operator access might not be compatible with 

current designs of trailer skirts, but a boat tail could be effective on that trailer in the early years 

of the program. Similarly, a rear lift gate or roll-up rear door might not be compatible with a 

current boat tail design, but skirts could be effective. The proposed requirements for these 

trailers would the same as their full-aero counterparts until MY 2027, at which time they would 

continue to be subject to the MY 2024 standards. See 40 CFR 1037.107. 

 

220 Secondary manufacturers who purchase incomplete trailers and complete their construction to serve as trailers are 

subject to the requirements of 40 CFR 1037.620. 
Page 259 of 850

For trailers for which no aerodynamic devices are practical, the agencies are proposing 

design standards requiring LRR tires and ATI systems. Trailers for which neither skirt/underbody devices nor rear-end devices would be likely to be feasible fall into two categories: nonbox trailers and non-aero box trailers. We believe that there is limited availability of 

aerodynamic technologies for non-box trailers (for example, platform (flatbed) trailers, tank 

trailers, and container chassis trailers). Also, for container chassis trailers, operational 

considerations, such as stacking of the chassis trailers, impede introduction of aerodynamic 

technologies. In addition, manufacturers of these trailer types have little or no experience with 

aerodynamic technologies designed for their products. Non-aero box trailers, defined as those 

with equipment or design features that would preclude both skirt/under-body and rear-end 

aerodynamic technologies (e.g., a trailer with both a pull-out platform for side access and a rear 

lift gate), would be subject to the same tire-only design standards as would non-box trailers, 

based exclusively on the performance of tire and ATI technologies.221 

We recognize that the shortest short box vans (i.e., less than 35 feet) are often pulled in 

tandem. Since these trailers make up the majority of trailers in the short box van subcategories, 

we are not proposing standards for short box dry and refrigerated vans based on the use of rear 

devices. Thus, work-performing features on the rear of the trailer (e.g., lift gates) would not 

impact a trailer’s ability to meet the full-aero short-box trailer standards. As a result, we are 

proposing that all short box vans only be categorized as partial-aero vans if they have workperforming side features (e.g., belly boxes). We expect that partial-aero short dry van trailers 

would be able to adopt front-side devices that would achieve the reduced standards. 

Furthermore, some short box trailers that are not operated in tandem, such as 40- or 48-foot 

trailers, could also be able to adopt rear-side devices and achieve even greater reductions. 

Refrigerated short box vans are a special case in that they have TRUs that limit the ability

to apply aerodynamic technologies to the front side of the trailers. Because of this, we are 

proposing to classify the shortest refrigerated box vans (shorter than 35 feet) as non-aero trailers 

if they are designed with work-performing side features. Since these trailers may be pulled in 

tandem and since they cannot adopt front-side aerodynamic devices, we propose that they meet 

standards predicated on tire technologies only. Short box refrigerated trailers 35 feet and longer 

would only qualify for non-aero standards if they have work-performing devices on both the side 

and rear of the trailer. See 40 CFR 1037.107.

We request comment on these proposed provisions for excluding some trailers from the 

program, including speed restrictions and physical characteristics that would generally make 

them incompatible for highway use. We also request comment on the proposed approach of 

applying less-stringent standards to non-box, non-aero box, and partial-aero box trailers. 

 

221 The agencies are not aware of work-performing equipment that would prevent the use of gap-reducing trailer 

devices on dry vans of any length; thus dry vans with side and rear equipment could qualify as “non-aero” trailers, 

even if the manufacturer could install a gap-reducing device. 
Page 260 of 850

(6) In-Use Standards

Consistent with Section 202(a)(1) of the CAA, EPA is proposing that the emissions

standards apply for the useful life of the trailers.222 Aerodynamic devices available today, 

including trailer skirts, rear fairings, under-body devices, and gap-reducing fairings, are designed 

to maintain their physical integrity for the life of the trailer. In the absence of failures like 

detachment, breakage, or misalignment, we expect that the aerodynamic performance of the 

devices will not degrade appreciably over time and that the projected CO2 and fuel consumption 

reductions will continue for the life of the vehicle with no special maintenance requirements. 

Because of this, EPA does not see a benefit to establishing separate standards that would apply

in-use for trailers. EPA is proposing a regulatory useful life value for trailers of 10 years, and 

thus the certification standards would apply in-use for that period of time.223 See Section IV. F. 

(5) (a) for a discussion of other factors related to trailer useful life.

D. Feasibility of the Proposed Trailer Standards

As discussed below, the agencies’ initial determination, subject to consideration of public 

comment, is that the standards presented in the Section IV.C.2, are the maximum feasible and 

appropriate under the agencies’ respective authorities, considering lead time, cost, and other 

factors. We summarize our analyses in this section, and describe them in more detail in the Draft 

RIA (Chapter 2.10). 

Our analysis of the feasibility of the proposed CO2 and fuel consumption standards is 

based on technology cost and effectiveness values collected from several sources. Our 

assessment of the proposed trailer program is based on information from:

– Southwest Research Institute evaluation of heavy-duty vehicle fuel efficiency and 

costs for NHTSA,224

– 2010 National Academy of Sciences report of Technologies and Approaches to 

Reducing the Fuel Consumption of Medium- and Heavy-Duty Vehicles,225

– TIAX’s assessment of technologies to support the NAS panel report,226

– The analysis conducted by the Northeast States Center for a Clean Air Future, 

International Council on Clean Transportation, Southwest Research Institute and 

 

222 NHTSA does not have in-use standards

223 EPA may perform in-use testing of any vehicle subject to the standards of this part, including trailers. For 

example, we may test trailers to verify drag areas or other GEM inputs.

224 Reinhart, T. (2015). Commercial Medium- and Heavy-Duty (MD/HD) Truck Fuel Efficiency Technology Study 

– Report #1. Washington, DC: National Highway Traffic Safety Administration. 

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

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

of Medium- and Heavy-Duty Vehicles. (“The NAS Report”) Washington, D.C., The National Academies Press. 

Available electronically from the National Academy Press Website at 

http://www.nap.edu/catalog.php?record_id=12845.

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

to National Academy of Sciences, November 19, 2009.
Page 261 of 850

TIAX for reducing fuel consumption of heavy-duty long haul combination tractors 

(the NESCCAF/ICCT study),227

– The technology cost analysis conducted by ICF for EPA,228 and 

– Testing conducted by EPA. 

As an initial step in our analysis, we identified the extent to which fuel consumption- and 

CO2-reducing technologies are in use today. 

The technologies include those that reduce aerodynamic drag at the front, back, and 

underside of trailers, tires with lower rolling resistance, tire inflation technologies, and weight 

reduction through component substitution. It should be noted that the agencies need not and did 

not attempt to predict the exact future pathway of the industry’s response to the new standards, 

but rather demonstrated one example of how compliance could reasonably occur, taking into 

account cost of the standards (including costs of compliance testing and certification), and 

needed lead time. We are proposing that full-aero box trailer manufacturers have additional 

flexibility in meeting the standards through averaging. The less complex standards proposed for 

partial- and non-aero box and non-box trailers would still provide a degree of technology choices 

that would meet their standards.

For our feasibility analysis, we identified a set of technologies to represent the range of 

those likely to be used in the time frame of the rule. We then combined these technologies into 

packages of increasing effectiveness in reducing CO2 and fuel consumption and projected 

reasonable rates at which the evaluated technologies and packages could be adopted across the 

trailer industry. More details regarding our analysis can be found in Chapter 2.10.4.1 of the draft 

RIA.

The agencies developed the proposed CO2 and fuel consumption standards for each stage 

of the program by combining the projected effectiveness of trailer technologies and the projected 

adoption rates for each trailer type. We evaluated these standards with respect to the cost of 

these technologies, the emission reductions and fuel consumption improvements achieved, and 

the lead-time needed to deploy the technology at a given adoption rate.

Unlike the other sectors covered by this Phase 2 rulemaking, trailer manufacturers do not 

have experience certifying under the Phase 1 program. Moreover, a large fraction of the trailer 

industry is composed of small businesses and very few of the largest trailer manufacturers have 

the same resources available as manufacturers in the other heavy-duty sectors. The standards 

have been developed with this in mind, and we are confident the proposed standards can be 

achieved by manufacturers who lack prior experience implementing such standards. 

 

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

Truck Fuel Consumption and CO2 Emissions. October 2009.

228 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. 
Page 262 of 850

(1) Available Technologies

Trailer manufacturers can design a trailer to reduce fuel consumption and CO2 emissions 

by addressing the trailer’s aerodynamic drag, tire rolling resistance and weight. In this section 

we outline the general trailer technologies that the agencies considered in evaluating the 

feasibility of the proposed standards. 

(a) Aerodynamic Drag Reduction

Historically, the primary goal when designing the shape of box trailers has been to 

maximize usable internal cargo volume, while complying with regulatory size limits and 

minimizing construction costs. This led to standard box trailers being rectangular. This basic 

shape creates significant aerodynamic drag and makes box trailers strong candidates for 

aerodynamic improvements. Current bolt-on aerodynamic technologies for box trailers are 

designed to create a smooth transition of airflow from the tractor, around the trailer, and beyond 

the trailer. 

Table IV-3 lists general aerodynamic technologies that the EPA SmartWay program has 

evaluated for use on box trailers and a description of their intended impact. Several versions of 

each of these technologies are commercially available and have seen increased adoption over the 

past decade. Performance of these devices varies based on their design, their location and 

orientation on the trailer, and the vehicle speed. More information regarding the agencies’ initial 

assessment of these devices, including incremental costs is discussed in Chapter 2.10 of the draft 

RIA.

Table IV-3 Aerodynamic Technologies for Box Trailers

Location on Trailer Example Technologies Intended Impact on Aerodynamics

Front Front fairings and gap-reducing 

fairings

Reduce cross-flow through gap and smoothly 

transition airflow from tractor to the trailer

Rear Rear fairings, boat tails and flow

diffusers

Reduce pressure drag induced by the trailer wake

Underside Side fairings and skirts, and 

underbody devices, 

Manage flow of air under the trailer to reduce 

turbulence, eddies and wake

As mentioned previously, SmartWay-verified technologies are evaluated on 53-foot dry

vans. However, the CO2- and fuel consumption-reducing potential of some aerodynamic 

technologies demonstrated on 53-foot dry vans can be translated to refrigerated vans and box 

trailers in lengths different than 53 feet and some fleets have opted to add trailer skirts to their 

refrigerated vans and 28-foot trailers (often called “pups”). In addition, some side skirts have 

been adapted for non-box trailers (e.g., tankers, platforms, and container chassis), and have 

shown potential for large reductions in drag. At this time, however, non-box trailer aerodynamic 

devices are not widely available, with many still at the prototype stage. The agencies encourage 

commenters to provide more information and data related to the effectiveness of technologies 

applied to trailers other than 53-foot dry and refrigerated vans. 

“Boat tail” devices, applied to the rear of a trailer, are typically designed to collapse flat 

as the trailer rear doors are opened. If the tail structure can remain in the collapsed configuration 
Page 263 of 850

when the doors are closed, the benefit of the device is lost. The agencies request comment on 

whether we should require that trailer manufacturers using such devices for compliance with the 

proposed standards only use designs that automatically deploy when the vehicle is in motion.

The agencies are aware that physical characteristics of some box trailers influence the 

technologies that can be applied. For instance, the TRUs on refrigerated vans are located at the 

front of the trailer, which prohibits the use of current gap-reducers. Similarly, drop deck dry

vans have lowered floors between the landing gear and the trailer axles that limit the ability to 

use side skirts. The agencies considered the availability and limitations of aerodynamic 

technologies for each trailer type evaluated in our feasibility analysis of the proposed and 

alternative standards. 

(b) Tire Rolling Resistance

On a typical Class 8 long-haul tractor-trailer, over 40 percent of the total energy loss from 

tires is attributed to rolling resistance from the trailer tires.229 Trailer tire rolling resistance 

values collected by the agencies for Phase 1 indicate that the average coefficient of rolling 

resistance (CRR) for new trailer tires was 6.0 kg/ton. This value was applied for the standard 

trailer used for tractor compliance in the Phase 1 tractor program. For Phase 2, the agencies 

consider all trailer tires with CRR values below 6.0 kg/ton to be “lower rolling resistance” (LRR) 

tires. For reference, a trailer tire that qualifies as a SmartWay-verified tire must meet a CRR

value of 5.1 kg/ton, a 15 percent CRR reduction from the trailer tire identified in Phase 1. Our 

research of rolling resistance indicates an additional CRR reduction of 15 percent or more from 

the SmartWay verification threshold is possible with tires that are available in the commercial 

market today.

For this proposal, the agencies are proposing to use the same rolling resistance baseline 

value of 6.0 kg/ton for all trailer subcategories. We request comment on the appropriateness of 

6.0 kg/ton as the proposed CRR threshold for all regulated trailers. Specifically, the agencies 

would like more information on current adoption rates of and CRR values for models of LRR tires 

currently in use on short box trailers and the various non-box trailers.

Similar to the case of tractor tires, LRR tires are available as either dual or as single widebased tires for trailers. Single wide-based tires achieve CRR values that are similar to their dual 

counterparts, but have an added benefit of weight reduction, which can be an attractive option for 

trailers that frequently maximize cargo weight. (See Section IV.D.1.d below).

(c) Tire Pressure Systems

The inflation pressure of tires also impacts the rolling resistance. Tractor-trailers 

operating with all tires under-inflated by 10 psi have been shown to increase fuel consumed by 

 

229 “Tires & Truck Fuel Economy: A New Perspective”, The Tire Topic Magazine, Special Edition Four, 2008, 

Bridgestone Firestone, North American Tire, LLC. Available online: 

http://www.trucktires.com/bridgestone/us_eng/brochures/pdf/08-Tires_and_Truck_Fuel_Economy.pdf
Page 264 of 850

up to 1 percent.230 Tires can gradually lose pressure from small punctures, leaky valves or 

simply diffusion through the tire casing. Changes in ambient temperature can also have an effect 

on tire pressure. Trailers that remain unused for long periods of time between hauls may

experience any of these conditions. A 2003 FMCSA report found that nearly 1 in 5 trailers had 

at least 1 tire under-inflated by 20 psi or more. If drivers or fleets are not diligent about checking 

and attending to under-inflated tires, the trailer may have much higher rolling resistance and 

much higher CO2 emissions and fuel consumption.

Tire pressure monitoring (TPM) and automatic tire inflation (ATI) systems are designed 

to address under-inflated tires. Both systems alert drivers if a tire’s pressure drops below its set 

point. TPM systems are simpler and merely monitor tire pressure. Thus, they require userinteraction to re inflate to the appropriate pressure. Today’s ATI systems, on the other hand, 

typically take advantage of trailers’ air brake systems to supply air back into the tires 

(continuously or on demand) until a selected pressure is achieved. In the event of a slow leak, 

ATI systems have the added benefit of maintaining enough pressure to allow the driver to get to 

a safe stopping area. The agencies believe TPM systems cannot sufficiently guarantee the proper 

inflation of tires due to the inherent user-interaction required. Therefore, ATI systems are the 

only pressure systems the agencies are proposing to recognize in Phase 2. 

Benefits of ATI systems in individual trailers vary depending on the base level of 

maintenance already performed by the driver or fleet, as well as the number of miles the trailer 

travels. Trailers that are well maintained or that travel fewer miles will experience less benefits 

from ATI systems compared to trailers that often drive with poorly inflated tires or log many

miles. The agencies believe ATI systems can provide a CO2 and fuel consumption benefit to 

most trailers. With ATI use, trailers that have lower annual vehicle miles traveled (VMT) due to 

long periods between uses would be less susceptible to low tire pressures when they resume 

activity. Trailers with high annual VMT would experience the fuel savings associated with 

consistent tire pressures. Automatic tire inflation systems could provide a CO2 and fuel 

consumption savings of 0.5-2.0 percent, depending on the degree of under-inflation in the trailer 

system. See Section IV.D.3.d below for discussion of our estimates of these factors, as well as 

estimates of the degree of adoption of ATI systems prior to and at various points in the phase-in 

of the proposed program.

The use of ATI systems can result in cost savings beyond reducing fuel costs. For 

example, drivers and fleets that diligently maintain their tires would spend less time and money

to inspect each tire. A 2011 FMCSA estimated under-inflation accounts for one service call per 

year and increases tire procurement costs 10 to 13 percent. The study found that total operating 

costs can increase by $600 to $800 per year due to under-inflation. 231 

 

230 “Tire Pressure Systems - Confidence Report”. North American Council for Freight Efficiency. 2013. Available 

online: http://nacfe.org/wp-content/uploads/2014/01/TPS-Detailed-Confidence-Report1.pdf

231 TMC Future Truck Committee Presentation “FMCSA Tire Pressure Monitoring Field Operational Test Results,” 

February 8, 2011
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(d) Weight Reduction

Reduction in trailer tare (i.e., empty) weight can lead to fuel efficiency reductions in two 

ways. For applications where payload is not limited by weight restrictions, the overall weight of 

the tractor and trailer would be reduced and would lead to improved fuel efficiency. For 

applications where payload is limited by weight restrictions, the lower trailer weight would allow 

additional payload to be transported during the truck’s trip, so emissions and fuel consumption 

on a ton-mile basis would decrease. There are weight reduction opportunities for trailers in both 

the structural components and in the wheels/tires. Material substitution (e.g., replacing steel with 

aluminum or lighter-weight composites) is feasible for components such as roof bows, side and 

corner posts, cross members, floor joists, floors, and van sidewalls. Similar material substitution 

is feasible for wheels (e.g., substituting aluminum for steel). Weight can also be reduced through 

the use of single wide-based tires replacing two dual tires.

Lower weight is a desired trailer attribute for many customers, and most trailer 

manufacturers offer options that reduce weight to some degree. Some of these manufacturers, 

especially box van makers, market trailers with lower-weight major components, such as lightweight composite van sidewalls or aluminum floors, especially to customers that expect to 

frequently reach regulatory weight limits (i.e., “weigh out”) and are willing to pay a premium for 

the ability to increase cargo weight without exceeding overall vehicle weight. Alternatively, 

manufacturers that primarily design trailers for customers that do not have weight limit concerns 

(i.e., their payloads frequently fill the available trailer cargo space before the weight limit is 

reached, or “cube out”), or for customers that have smaller budgets, may continue to design 

trailers based on traditional, heavier materials, such as wood and steel. 

There is no clear “baseline” for current trailer weight against which lower-weight designs 

could be compared for regulatory purposes. For this reason, the agencies do not believe it would 

be appropriate or fair across the industry to apply overall weight reductions toward compliance. 

However, the agencies do believe it would be appropriate to allow a manufacturer to account for 

weight reductions that involve substituting very specific, traditionally heavier components with 

lower-weight options that are not currently widely adopted in the industry. We discuss how we 

apply weight reduction in developing the standards in Section IV. D. (2) (d) below. 

(2) Technological Basis of the Standards

The analysis below presents one possible set of technology designs by which trailer 

manufacturers could reasonably achieve the goals of the program on average. However, in 

practice, trailer manufacturers could choose different technologies, versions of technologies, and 

combinations of technologies that meet the business needs of their customers while complying 

with this proposed program. 

Much of our analysis is performed for box trailers, which have the most stringent 

proposed standards. As mentioned previously, we have separate standards for short and long box 

vans, and a trailer length of 50 feet is proposed as the cut-point to distinguish the two length 

categories. For the purpose of this analysis, long trailers are represented by 53-foot vans and 

short trailers are represented by single, 28-foot (“pup”) vans. These trailer lengths make up the 

largest fraction of the vans in the two categories. The agencies recognize that many 28-foot 
Page 266 of 850

short vans are operated in tandem. However, these trailers are sold individually, and require a 

“dolly”, often sold by a separate manufacturer, to connect the trailers for tandem operation. 

In addition, the other trailer types considered short vans in this proposal (e.g., 40-foot and 

48-foot) typically operate as single trailers. To minimize complexity, we are proposing that 28-

foot trailers represent all short refrigerated and dry vans for both compliance and for this 

feasibility analysis. This means that manufacturers would not need to perform tests (or report 

device manufacturers’ test data) of the performance of devices for each trailer length in the short 

van category. Although this approach would provide a conservative estimate of actual CO2

emissions and fuel consumption reductions for the short van category, the agencies believe that 

the need to avoid an overly complex compliance program justifies this approach. We request 

comment on this approach to evaluating short box trailers.

(a) Aerodynamic Packages

In order to evaluate performance and cost of the aerodynamic technologies discussed in 

the previous section, the agencies identified “packages” of individual or combined technologies 

that are being sold today on box trailers. The agencies also identified distinct performance levels 

(i.e., bins) for these technologies based on EPA’s aerodynamic testing. The agencies recognize 

that there are other technology options that have similar performance. We chose the 

technologies presented here based on their current adoption rates and effectiveness in reducing 

CO2 and fuel consumption. 

Bin I represents a base trailer with no aerodynamic technologies added. There is no cost 

associated with this bin. Bin II achieves small reductions in CO2 and fuel consumption. This bin 

includes a gap reducing fairing added to a long dry van or a skirt added to a solo short dry van.232 

Bin III includes devices that would achieve SmartWay’s verification threshold of four percent at 

cruise speeds. Some basic skirts and boat tails would achieve these levels of reductions for long 

box trailers. A gap reducer and a basic skirt on a short dry van would meet this level of 

performance. Bin IV technologies are more effective, single aerodynamic devices for long box 

trailers, including advanced skirts or boat tails, that achieve larger reductions in drag than the 

technologies in Bin III. The combination of an advanced skirt and gap reducer on a short dry

van are also expected to achieve this bin. 

Bin V levels of performance were not observed in EPA’s aerodynamic testing for short 

box trailers. It is possible that a gap reducer, skirt, and boat tail could achieve this performance, 

but boat tails are not feasible for 28-foot trailers operated in tandem unless the trailer is located 

in the rear position. For this analysis, the agencies only evaluated solo pup trailers and, 

therefore, did not evaluate any technologies for short box trailers beyond Bin IV. For this 

proposed rulemaking, we believe a Bin V level of performance can be achieved for long box 

trailers by either highly effective single devices or by applying a combination of basic boat tails 

 

232 The agencies recognize that many 28-foot pup trailers are often operated in tandem. However, we are regulating 

and evaluating short dry vans as solo trailers since they are sold individually and the short box regulatory 

subcategories also include trailer sizes not often operated in tandem (e.g., 40-foot and 48-foot trailers).
Page 267 of 850

and skirts. We do not currently have data for a single aerodynamic device that fits this bin and 

we evaluated it as a combination of a basic tail and skirt. Bin VI combines advanced skirts and 

boat tail technologies on long box trailers. This bin is expected to include many technologies 

that qualify for SmartWay’s “Elite” designation. 

Bin VII represents an optimized system of technologies that work together to 

synergistically address each of the main areas of drag and achieves aerodynamic improvements 

greater than SmartWay’s “Elite” designation. We are representing Bin VII with a gap reducer, 

and advanced tail and skirt. Bin VIII is designed to represent aerodynamic technologies that may

become available in the future, including aerodynamic devices yet to be designed or approaches 

that would incorporate changes to the construction of trailer bodies. We have not analyzed this 

final bin in terms of effectiveness or cost, but are including it to account for future advancements 

in trailer aerodynamics. 

For this proposal, aerodynamic performance is evaluated using a vehicle’s aerodynamic 

drag area, CDA. EPA collected aerodynamic test data for several tractor-trailer configurations, 

including 53-foot dry vans and 28-foot dry van trailers with many of these technology packages. 

The agencies developed bins, somewhat similar to the aerodynamic bins in the Phase 1 and 

proposed Phase 2 tractor programs, based on results from our test program. However, unlike the 

tractor program, we grouped the technologies by changes in CDA (or “delta CDA”) rather than by 

absolute values. In other words, each bin would comprise aerodynamic technologies that 

provide similar improvements in drag. This delta CDA classification methodology, which 

measures improvement in performance relative to a baseline, is similar to the SmartWay

technology verification program with which most trailer manufacturers are familiar. 

Table IV-4 illustrates the bin structure that the agencies are proposing as the basis for 

compliance. The table shows example technology packages that might be included in each bin 

based on EPA’s testing of 53-foot dry vans and solo 28-foot dry vans. The agencies believe 

these bins apply to other box trailers (refrigerated vans and lengths other than 28 and 53 feet), 

which will be described in more detail in Section IV.D.3.b. These bins cover a wide enough 

range of delta CDAs to account for the uncertainty seen in EPA’s aerodynamic testing program 

due to procedure variability, the use of different test methods, or different models of tractors, 

trailers and devices. A more detailed description of the development of these bins can be found 

in the draft RIA, Chapter 2.10. We welcome comments and additional data that may support or 

suggest changes to these bins.
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Table IV-4 Technology Bins used to Evaluate Trailer Benefits and Costs

Bin Delta CdA AVERAGE 

DELTA CDA

Example Technologies

53-FOOT DRY VAN 28-FOOT DRY VAN

Bin I < 0.09 0.0 No Aero Devices No Aero Devices

Bin II 0.10 - 0.19 0.1 Gap Reducer Skirt

Bin III 0.20 - 0.39 0.3 Basic Skirt or Basic Tail Skirt + Gap Reducer 

Bin IV 0.40 - 0.59 0.5 Advanced Skirt or Tail Adv. Skirt + Gap Reducer

Bin V 0.60 - 0.79 0.7 Basic Combinations

Bin VI 0.80 - 1.19 1.0 Advanced Combinations 

(including SmartWay Elite)

Bin VII 1.20 - 1.59 1.4 Optimized Combinations

Bin VIII > 1.6 1.8 Changes to Trailer Construction

Note: A blank cell indicates a zero or NA value in this table.

The agencies used EPA’s Greenhouse gas Emissions Model (GEM) vehicle simulation 

tool to conduct this analysis. (See Section F.1 below for more about GEM) Within GEM, the 

aerodynamic performance of each trailer subcategory is evaluated by subtracting the delta CDA 

shown in Table IV-4 from the CDA value representing a specific standard tractor pulling a zerotechnology trailer. The agencies chose to model the zero-technology long box dry van using a 

CDA value of 6.2 m2(the average CDA from EPA’s coastdown testing). For long box 

refrigerated vans, a two percent reduction in CDA was assumed to account for the aerodynamic 

benefit of the TRU at the front of the trailer. Short box dry vans also received a two percent 

lower CDA value compared to its 53-foot counterpart, consistent with the reduction observed in 

EPA’s wind tunnel testing. The CDA value assigned to the refrigerated short box vans was an 

additional two percent lower than the short box dry van. Non-aero box trailers are modeled as 

short box dry vans. The trailer subcategories that have design standards (i.e., non-box and nonaero box trailers) do not have numerical standards to meet, but they were evaluated in this 

feasibility analysis in order to quantify the benefits of including them in the program. Non-aero 

box trailers are modeled as short dry vans. Non-box trailers, which are modeled as flatbed 

trailers, were assigned a drag area of 4.9 m2, as was done in the Phase 1 tractor program for low 

roof day cabs. Table IV-5 illustrates the Bin I drag areas (CDA) associated with each trailer 

subcategory.

Table IV-5 Baseline CDA Values Associated with Aerodynamic Bin I (Zero Trailer Technologies)

TRAILER 

SUBCATEGORY

DRY VAN

Long Dry Van 6.2

Short Dry Van 6.1

Long Ref. Van 6.1

Short Ref. Van 6.0

Non-Aero Box 6.1

Non-Box 4.9

(b) Tire Rolling Resistance

Similar to the proposed Phase 2 tractor and vocational vehicle programs, the agencies are 

proposing a tire program based on adoption of lower rolling resistance tires. Feedback from 

several box trailer manufacturers indicates that the standard tires offered on their new trailers are 
Page 269 of 850

SmartWay-verified tires (i.e., CRR of 5.1 kg/ton or better). An informal survey of members from 

the Truck Trailer Manufacturers Association (TTMA) indicates about 35 percent of box trailers 

sold today have SmartWay tires.233 While some trailers continue to be sold with tires of higher 

rolling resistances, the agencies believe most box trailer tires currently achieve the Phase 1 trailer 

tire CRR of 6.0 kg/ton or better.

The agencies evaluated two levels of tire performance for this proposal beyond the

baseline trailer tire rolling resistance level (TRRL) of 6.0 kg/ton. The first performance level 

was set at the criteria for SmartWay-verification for trailer tires, 5.1 kg/ton, which is a 15 percent 

reduction in CRR from the baseline. As mentioned previously, several tire models available today

achieve rolling resistance values well below the present SmartWay threshold. Given the multiple 

year phase-in of the standards, the agencies expect that tire manufacturers will continue to 

respond to demand for more efficient tires and will offer increasing numbers of tire models with 

rolling resistance values significantly better than today’s typical LRR tires. In this context, we 

believe it is reasonable to expect a large fraction of the trailer industry could adopt tires with 

rolling resistances at a second performance level that would achieve an additional eight percent 

reduction in rolling resistance (a 22 percent reduction from the baseline tire), especially in the 

later stages of the program. The agencies project the CRR for this second level of performance to 

be a value of 4.7 kg/ton. 

The agencies evaluated these three tire rolling resistance levels, summarized in Table 

IV-6, in the feasibility analysis of the following sections. GEM simulations that apply Level 1

and 2 tires result in CO2 and fuel consumption reductions of two and three percent from the 

baseline tire, respectively. It should be noted that these levels are for the feasibility analysis 

only. For compliance, manufacturers would have the option to use tires with any rolling 

resistance and would not be limited to these TRRLs. 

Table IV-6 Summary of Trailer Tire Rolling Resistance Levels Evaluated

Tire Rolling 

Resistance Level

CRR (kg/ton)

Baseline 6.0 

Level 1 5.1 

Level 2 4.7 

(c) Automatic Tire Inflation Systems

NHTSA and EPA recognize the role of proper tire inflation in maintaining optimum tire 

rolling resistance during normal trailer operation. For this proposal, rather than require 

performance testing of ATI systems, the agencies are proposing to recognize the benefits of ATI 

systems with a single default reduction for manufacturers that incorporate ATI systems into their 

trailer designs. Based on information available today, we believe that there is a narrow range of 

 

233 Truck Trailer Manufacturers Association letter to EPA. Received on October 16, 2014. Docket EPA-HQ-OAR2014-0827
Page 270 of 850

performance among technologies available and among systems in typical use. We propose to 

assign a 1.5 percent reduction in CO2 and fuel consumption for all trailers that implement ATI 

systems, based on information available today.

234

 We believe the use of these systems can 

consistently ensure that tire pressure and tire rolling resistance are maintained. We selected the 

levels of the proposed trailer standards with the expectation that a high rate of adoption of ATI 

systems would occur across all on-highway trailers and during all years of the phase-in of the 

program. See Section IV.D.3.d below for discussion of our estimates of these factors, as well as 

estimates of the degree of adoption of ATI systems prior to and at various points in the phase-in 

of the proposed program. The informal survey of members from the Truck Trailer 

Manufacturers Association (TTMA) indicates about 40 percent of box trailers sold today have 

ATI systems.235

(d) Weight Reduction

The agencies are proposing compliance provisions that would limit the weight-reduction 

options to the substitution of specified components that can be clearly isolated from the trailer as 

a whole. For this proposal, the agencies have identified several conventional components with 

available lighter-weight substitutes (e.g., substituting conventional dual tires mounted on steel 

wheels with wide-based single tires mounted on aluminum wheels). We are proposing values for 

the associated weight-related savings that would be applied with these substitutions for 

compliance. The proposed component substitutions and their associated weight savings are 

presented in the draft RIA, Chapter 2.10.2.4 and in proposed 40 CFR 1037.520. We believe that 

the initial cost of these component substitutions is currently substantial enough that only a 

relatively small segment of the industry has adopted these technologies today. 

The agencies recognize that when weight reduction is applied to a trailer, some operators 

will replace that saved weight with additional payload. To account for this in EPA’s GEM 

vehicle simulation tool, it is assumed that one-third of the weight reduction will be applied to the 

payload. For tractor-trailers simulated in GEM, it takes a weight reduction of nearly 1,000 

pounds before a one percent fuel savings is achieved. The component substitutions identified by

the agencies result in weight reductions of less than 500 pounds, yet can cost over $1,000. The 

agencies believe that few trailer manufacturers would apply weight reduction solely as a means 

of achieving reduced fuel consumption and CO2 emissions. Therefore, we are proposing 

standards that could be met without reducing weight – that is, the compliance path set out by the 

agencies for the proposed standards does not include weight reduction. However, we are 

proposing to offer weight reduction as an option for box trailer manufacturers who wish to apply

it to some of their trailers as part of their compliance strategy. 

 

234 See the Chapter 2.10.2.3 of the draft RIA.

235 Truck Trailer Manufacturers Association letter to EPA. Received on October 16, 2014. Docket EPA-HQ-OAR2014-0827
Page 271 of 850

The agencies have identified 11 common trailer components that have lighter weight 

options available (see 40 CFR 1037.520)

236,237,238,239

 Manufacturers that adopt these 

technologies would sum the associated weight reductions and apply those values in GEM. As 

mentioned previously, we are restricting the weight reduction options to those listed in 40 CFR 

1037.520. We are requesting comment on the appropriateness of the specified weight reductions 

from component substitution. In addition, we seek weight and cost data regarding additional 

components that could be offered as specific weight reduction options. The agencies request that 

any such components be applicable to most box trailers, and that the reduced weight option not 

currently be in common use. 

(3) Effectiveness, Adoption Rates, and Costs of Technologies for the Proposed 

Standards

The agencies evaluated the technologies above as they apply to each of the trailer 

subcategories. The next sections describe the effectiveness, adoption rates and costs associated 

with these technologies. The effectiveness and adoption rates are then used to derive the 

proposed standards. 

(a) Zero-Technology Baseline Tractor-Trailer Vehicles

The regulatory purpose of EPA’s heavy-duty vehicle compliance tool, GEM, is to 

combine the effects of trailer technologies through simulation so that they can be expressed as 

g/ton-mile and gal/100 ton-mile and thus avoid the need for direct testing of each trailer model 

being certified. The proposed trailer program has separate standards for each trailer subcategory, 

and a unique tractor-trailer vehicle was chosen to represent each subcategory for compliance. In 

the Phase 2 update to GEM, each trailer subcategory is modeled as a particular trailer being 

pulled by a standard tractor depending on the physical characteristics and use pattern of the 

trailer. Table IV-7 highlights the relevant vehicle characteristics for the zero-technology

baseline of each subcategory. Baseline trailer tires are used, and the drag area, which is a 

function of the aerodynamic characteristics of both the tractor and trailer, is set to the Bin I 

values shown previously in Table IV-5. Weight reduction and ATI systems are not applied in 

these baselines. Chapter 2.10 of the draft RIA provides a detailed description of the 

development of these baseline tractor-trailers. 

The agencies chose to consistently model a Class 8 tractor across all trailer subcategories. 

We recognize that Class 7 tractors are sometimes used in certain applications. However, we 

believe Class 8 tractors are more widely available, which will make it easier for trailer 

 

236 Scarcelli, Jamie. "Fuel Efficiency for Trailers" Presented at ACEEE/ICCT Workshop: Emerging Technologies 

for Heavy-Duty Vehicle Fuel Efficiency, Wabash National Corporation. July 22, 2014

237 "Weight Reduction: A Glance at Clean Freight Strategies", EPA SmartWay. EPA420F09-043. Available at: 

http://permanent.access.gpo.gov/gpo38937/EPA420F09-043.pdf

238 CBI obtained during SBREFA Panel.

239 Randall Scheps, Aluminum Association, “The Aluminum Advantage: Exploring Commercial Vehicles 

Applications,” presented in Ann Arbor, Michigan, June 18, 2009
Page 272 of 850

manufacturers to obtain a qualified tractor if they choose to perform trailer testing. We request 

comment on the use of Class 8 tractors as part of the tractor-trailer vehicles used in the 

compliance simulation as well as performance testing. We ask that commenters include data, 

where available, related to the current use and availability of Class 7 and 8 tractors with respect 

to the trailer types in each trailer subcategory.

Table IV-7 Characteristics of the Zero-Technology Baseline Tractor-Trailer Vehicles

DRY VAN REFRIGERATED VAN NONAERO 

BOX

NON-BOX

Trailer Length Long Short Long Short All 

Lengths

All Lengths

Tractor Class Class 8 Class 8 Class 8 Class 8 Class 8 Class 8

Tractor Cab Type Sleeper Day Sleeper Day Day Day

Tractor Roof Height High High High High High Low

Engine 2018 MY 

15L, 

455 HP

2018 MY 

15L, 

455 HP

2018 MY 

15L, 

455 HP

2018 MY 

15L, 

455 HP

2018 MY 

15L, 

455 HP

2018 MY 

15L, 

455 HP

Frontal Area (m2) 10.4 10.4 10.4 10.4 10.4 6.9

Drag Area, CDA (m2) 6.2 6.1 6.1 6.0 6.1 4.9

Steer Tire RR (kg/ton) 6.54 6.54 6.54 6.54 6.54 6.54

Drive Tire RR (kg/ton) 6.92 6.92 6.92 6.92 6.92 6.92

Trailer Tire RR (kg/ton) 6.00 6.00 6.00 6.00 6.00 6.00

Total Weight (kg) 31978 21028 33778 22828 21028 29710

Payload (tons) 19 10 19 10 10 19

ATI System Use 0 0 0 0 0 0

Weight Reduction (lb) 0 0 0 0 0 0

Drive Cycle Weightings

65-MPH Cruise 86% 64% 86% 64% 64% 64%

55-MPH Cruise 9% 17% 9% 17% 17% 17%

Transient Driving 5% 19% 5% 19% 19% 19%

(b) Effectiveness of Technologies

The agencies are proposing to recognize trailer improvements via four performance 

parameters: aerodynamic drag reduction, tire rolling resistance reduction, the adoption of ATI 

systems, and by substituting specific weight-reducing components. Table IV-8 summarizes the 

performance levels for each of these parameters based on the technology characteristics outlined 

in Section IV. D. (2) . 
Page 273 of 850

Table IV-8 Performance Parameters for the Proposed Trailer Program

Aerodynamics (Delta CDA, m2)

Bin I 0.0

Bin II 0.1

Bin III 0.3

Bin IV 0.5

Bin V 0.7

Bin VI 1.0

Bin VII 1.4

Bin VIII 1.8

Tire Rolling Resistance (CRR, kg/ton)

Tire Baseline 6.0

Tire Level 1 5.1

Tire Level 2 4.7

Tire Inflation System (% reduction)

ATI System 1.5

Weight Reduction (pounds)

Weight 1/3 added to payload, remaining

reduces overall vehicle weight

These performance parameters have different effects on each trailer subcategory due to 

differences in the simulated trailer characteristics. Table IV-9 shows the agencies’ estimates of 

the effectiveness of each parameter for the four box trailer subcategories. Each technology was 

evaluated using the baseline parameter values for the other technology categories. For example, 

each aerodynamic bin was evaluated using the baseline tire (6.0 kg/ton) and the baseline weight 

reduction option (zero pounds). The table shows that aerodynamic improvements offer the 

largest potential for CO2 emissions and fuel consumption reductions, making them relatively 

effective technologies. 
Page 274 of 850

Table IV-9 Effectiveness (Percent CO2 and Fuel Savings from Baseline) of Technologies for the Proposed 

Trailer Program

Aerodynamics Delta CDA (m2) Dry Van Refrigerated Van

Long Short Long Short

Bin I 0.0 0% 0% 0% 0%

Bin II 0.1 -1% -1% -1% -1%

Bin III 0.3 -2% -2% -2% -2%

Bin IV 0.5 -3% -4% -3% -3%

Bin V 0.7 -5% -5% -5% -5%

Bin VI 1.0 -7% -7% -7% -7%

Bin VII 1.4 -10% -10% -9% -10%

Bin VIII 1.8 -13% -13% -12% -12%

Tire Rolling Resistance CRR (kg/ton) Dry Van Refrigerated Van

Long Short Long Short

Baseline 6.0 0% 0% 0% 0%

Level 1 5.1 -2% -1% -2% -1%

Level 2 4.7 -3% -2% -3% -2%

Weight Reduction Weight (lb) Dry Van Refrigerated Van

Long Short Long Short

Baseline 0.0 0.0% 0.0% 0.0% 0.0%

Al. Dual Wheels 168 -0.2% -0.3% -0.2% -0.3%

Upper Coupler 280 -0.3% -1% -0.3% -1%

Suspension 430 -0.5% -1% -0.5% -1%

Al. Single Wide 556 -1% -1% -1% -1%

(c) Reference Tractor-Trailer to Evaluate Benefits and Costs

In order to evaluate the benefits and costs of the proposed standards, it is necessary to 

establish a reference point for comparison. As mentioned previously, the technologies described 

in Section IV. D. (2) exist in the market today, and their adoption is driven by available fuel 

savings as well as by the voluntary SmartWay Partnership and California’s tractor-trailer 

requirements. For this proposal, the agencies identified reference case tractor-trailers for each 

trailer subcategory based on the technology adoption rates we project would exist if this 

proposed trailer program was not implemented. 

We project that by 2018, absent further California regulation, EPA’s SmartWay program 

and these research programs will result in about 20 percent of 53-foot dry and refrigerated vans 

adopting basic SmartWay-level aerodynamic technologies (meeting SmartWay’s four percent 

verification level and Bin III from Table IV-5), 30 percent adopting more advanced aerodynamic 

technologies at the five percent SmartWay-verification level (Bin IV from Table IV-5) and five 

percent adding combinations of technologies (Bin V).240,241,242 In addition, we project half of

 

240 Truck Trailer Manufacturers Association letter to EPA. Received on October 16, 2014. Docket EPA-HQ-OAR2014-0827
Page 275 of 850

these 53’ box trailers will be equipped with SmartWay-verified tires (i.e., 5.1 kg/ton or better) 

and ATI systems as well. The agencies project that market forces will drive an additional one 

percent increase in adoption of the advanced SmartWay and tire technologies each year through 

2027. For analytical purposes, the agencies assumed manufacturers of the shorter box trailers 

and other trailer subcategories would not adopt these technologies in the timeframe considered 

and a zero-technology baseline is assumed. We are not assuming weight reduction for any of the 

trailer subcategories in the reference cases. Table IV-10 summarizes the reference case trailers 

for each trailer subcategory. 

Table IV-10 Projected Adoption Rates and Average Performance Parameters for the Less Dynamic 

Reference Case Trailers

TECHNOLOGY LONG BOX

DRY & REFRIGERATED 

VANS

SHORT BOX, 

NON-AERO BOX, 

& NON-BOX TRAILERS

Model Year 2018 2021 2024 2027 2018 - 2027

Aerodynamics

Bin I 45% 41% 38% 35% 100%

Bin II

Bin III 20% 20% 20% 20%

Bin IV 30% 34% 37% 40%

Bin V 5% 5% 5% 5%

Bin VI

Bin VII

Bin VIII

Average Delta CDA (m2) a0.2 0.3 0.3 0.3 0.0

Tire Rolling Resistance

Baseline tires 50% 47% 43% 40% 100%

Level 1 tires 50% 53% 57% 60%

Level 2 tires

Average CRR (kg/ton) a5.55 5.52 5.49 5.46 6.0

Tire Inflation

ATI 50% 53% 57% 60% 0%

Average % Reduction a0.8% 0.8% 0.9% 0.9% 0.0%

Weight Reduction (pounds)

Weight b

Notes: 

A blank cell indicates a zero value

a

: Combines adoption rates with performance levels shown in Table IV-8

b

: Weight reduction was not projected for the reference case trailers

Also shown in Table IV-10 are average aerodynamic performance (delta CDA), average 

tire rolling resistance (CRR), and average reductions due to use of ATI and weight reduction for 

each stage of the proposed program. These values indicate the performance of theoretical 

 

241 Ben Sharpe (ICCT) and Mike Roeth (North American Council for Freight Efficiency), “Costs and Adoption 

Rates of Fuel-Saving Technologies for Trailer in the North American On-Road Freight Sector”, Feb 2014

242 Frost & Sullivan, “Strategic Analysis of North American Semi-trailer Advanced Technology Market”, Feb 2013
Page 276 of 850

average tractor-trailers that the agencies project will be in use if no federal regulations were in 

place for trailer CO2 and fuel consumption. The average tractor-trailer vehicles serve as 

reference cases for each trailer subcategory. The agencies provide a detailed description of the 

development of these reference case vehicles in Chapter 2.10 in the draft RIA.

Because the agencies cannot be certain about future trends, we also considered a second 

reference case. This more dynamic reference case reflects the possibility that absent a Phase 2 

regulation, there will be continuing adoption of technologies in the trailer market after 2027 that 

reduce fuel consumption and CO2 emissions. This case assumes the research funded and 

conducted by the federal government, industry, academia and other organizations will, after 

2027, result the adoption of some technologies beyond the levels required to comply with 

existing regulatory and voluntary programs. One example of such research is the Department of 

Energy Super Truck program which has a goal of demonstrating cost-effective measures to 

improve the efficiency of Class 8 long-haul freight trucks by 50 percent by 2015.243 This 

reference case assumes that by 2040, 75 percent of new trailers will be equipped with 

SmartWay-verified aerodynamic devices, low rolling resistance tires, and ATI systems. Table 

IV-11 shows the agencies’ projected adoption rates of technologies in the more dynamic 

reference case.

 

243 Daimler Truck North America. SuperTruck Program Vehicle Project Review. June 19, 2014. Docket EPA-HQOAR-2014-0827
Page 277 of 850

Table IV-11 Projected Adoption Rates and Average Performance Parameters for the More Dynamic 

Reference Case 

TECHNOLOGY LONG BOX

DRY & REFRIGERATED VANS

SHORT BOX, 

NON-AERO BOX, 

& NON-BOX TRAILERS

Model Year 2018 2021 2024 2027 2040 2018 - 2027

Aerodynamics

Bin I 45% 41% 38% 35% 20% 100%

Bin II

Bin III 20% 20% 20% 20% 20%

Bin IV 30% 34% 37% 40% 55%

Bin V 5% 5% 5% 5% 5%

Bin VI

Bin VII

Bin VIII

Average Delta CDA (m2) a0.2 0.3 0.3 0.3 0.4 0.0

Tire Rolling Resistance

Baseline tires 50% 47% 43% 40% 25% 100%

Level 1 tires 50% 53% 57% 60% 75%

Level 2 tires

Average CRR (kg/ton) a5.6 5.5 5.5 5.5 5.3 6.0

Tire Inflation

ATI 50% 53% 57% 60% 75% 0%

Average % Reduction a0.8% 0.8% 0.9% 0.9% 1.1% 0.0%

Weight Reduction (pounds)

Weight b

Notes: 

A blank cell indicates a zero value

a

: Combines adoption rates with performance levels shown in Table IV-8

b

: Weight reduction was not projected for the reference case trailers

The agencies applied the vehicle attributes from Table IV-7 and the average performance 

values from Table IV-10 in the proposed Phase 2 GEM vehicle simulation to calculate the CO2 

emissions and fuel consumption performance of the reference tractor-trailers. The results of 

these simulations are shown in Table IV-12. We used these CO2 and fuel consumption values to 

calculate the relative benefits of the proposed standards. Note that the large difference between 

the per ton-mile values for long and short trailers is due primarily to the large difference in 

assumed payload (19 tons compared to 10 tons) as seen in Table IV-7 and discussed further in 

the Chapter 2.10.3. The alternative reference case shown in Table IV-11 impacts the long-term 

projections of benefits beyond 2027, which are analyzed in Chapters 5-7 of the draft RIA. 
Page 278 of 850

Table IV-12 CO2 Emissions and Fuel Consumption Results for the Reference Tractor-Trailers

Dry Van Refrigerated Van

Length Long Short Long Short

CO2 Emissions 

(g/ton-mile)

85 147 87 151

Fuel Consumption 

(gal/100 ton-miles)

8.3497 14.4401 8.5462 14.8330

(d) Projected Technology Adoption Rates for the Proposed Standards

As described in Section IV. E. , the agencies evaluated several alternatives for the 

proposed trailer program. Based on our analysis, and current information, the agencies are 

proposing the alternative we believe reflects the agencies’ respective statutory authorities. The 

agencies are also considering an accelerated alternative with less lead time, requiring the same 

incremental stringencies for the proposed program, but becoming effective three years earlier. 

The agencies believe this alternative has the potential to be the maximum feasible alternative. 

However, based on the evidence currently before us, EPA and NHTSA have outstanding 

questions regarding relative risks and benefits of Alternative 4 due to the timeframe envisioned 

by that alternative. EPA and NHTSA are seriously considering this accelerated alternative in 

whole or in part for the trailer segment. In other words, the agencies could determine that less 

lead-time is maximum feasible in the final rule. We request comment on these two alternatives, 

including the proposed lead-times. 

Table IV-13 and Table IV-14 present a set of assumed adoption rates for aerodynamic, 

tire, and ATI technologies that a manufacturer could apply to meet the proposed standards. 

These adoption rates begin with 60 percent of long box trailers achieving current SmartWay

level aerodynamics (Bin IV) and progress to 90 percent achieving SmartWay Elite (Bin VI) or 

better over the following nine years. The adoption rates for short box trailers assume adoption of 

single aero devices in MY 2021 and combinations of devices by MY 2027. Although the shorter 

lengths of these trailers can restrict the design of aerodynamic technologies that fully match the 

SmartWay-like performance levels of long boxes, we nevertheless expect that trailer and device 

manufacturers would continue to innovate skirt, under-body, rear, and gap-reducing devices and 

combinations to achieve improved aerodynamic performance on these shorter trailers. The 

assumed adoption rates for aerodynamic technologies for both long and short refrigerated vans 

are slightly less than for dry vans, reflecting the more limited number of aerodynamic options 

due to the presence of their TRUs. 

The gradual increase in assumed adoption of aerodynamic technologies throughout the 

phase-in to the MY 2027 standards recognizes that even though many of the technologies are 

available today and technologically feasible throughout the phase-period, their adoption on the 

scale of the proposed program would likely take time. The adoption rates we are assuming in the 

interim years – and the standards that we developed from these rates -- represent steady and yet 

reasonable improvement in average aerodynamic performance. 
Page 279 of 850

The agencies project that nearly all box trailers will adopt tire technologies to comply 

with the standards and the agencies projected consistent adoption rates across all lengths of dry

and refrigerated vans, with more advanced (Level 2) low-rolling resistance tires assumed to 

replace Level 1 tire models in the 2024 time frame, as Level 2-type tires become more available 

and fleet experience with these tires develops. As mentioned previously, the agencies did not 

include weight reduction in their technology adoption projections, but certain types of weight 

reduction could be used as a compliance pathway, as discussed in Section IV.D.1.d above. 

The adoption rates shown in these tables are one set of many possible combinations that 

box trailer manufacturers could apply to achieve the same average stringency. If a manufacturer 

chose these adoption rates, a variety of technology options exist within the aerodynamic bins, 

and several models of LRR tires exist for the levels shown. Alternatively, technologies from 

other aero bins and tire levels could be used to comply. It should be noted that manufacturers are 

not limited to aerodynamic and tire technologies, since these are performance-based standards, 

and manufacturers would not be constrained to adopt any particular way to demonstrate 

compliance. Certain types of weight reduction, for example, may be used as a compliance 

pathway, as discussed in Section IV.D.1.d above. 

Similar to our analyses of the reference cases, the agencies derived a single set of 

performance parameters for each subcategory by weighting the performance levels included in 

Table IV-8 by the corresponding adoption rates. These performance parameters represent an 

average compliant vehicle for each trailer subcategory and we present these values in the tables. 

The 2024 MY adoption rates would continue to apply for the partial-aero box trailers in 2027 and 

later model years. 
Page 280 of 850

Table IV-13 Projected Adoption Rates and Average Performance Parameters for Long Box Trailers

TECHNOLOGY LONG BOX

DRY VANS

LONG BOX

REFRIGERATED VANS

Model Year 2018 2021 2024 2027 2018 2021 2024 2027

Aerodynamic Technologies

Bin I 5% 5%

Bin II

Bin III 30% 5% 30% 5%

Bin IV 60% 55% 25% 60% 55% 25%

Bin V 5% 10% 10% 10% 5% 10% 10% 20%

Bin VI 30% 65% 50% 30% 65% 60%

Bin VII 40% 20%

Bin VIII

Average Delta CDA (m2) a0.4 0.7 0.8 1.1 0.4 0.7 0.8 1.0

Trailer Tire Rolling Resistance

Baseline tires 15% 5% 5% 5% 15% 5% 5% 5%

Level 1 tires 85% 95% - - 85% 95%

Level 2 tires 95% 95% 95% 95%

Average CRR (kg/ton) a5.2 5.1 4.8 4.8 5.2 5.1 4.8 4.8

Tire Inflation System

ATI 85% 95% 95% 95% 85% 95% 95% 95%

Average ATI Reduction (%) a1.3% 1.4% 1.4% 1.4% 1.3% 1.4% 1.4% 1.4%

Weight Reduction (pounds)

Weight b

Notes: 

A blank cell indicates a zero value

a

: Combines projected adoption rates with performance levels shown in Table IV-8

b

: This set of proposed adoption rates did not apply any assumed weight reduction to meet the proposed standards for these 

trailers
Page 281 of 850

Table IV-14 Projected Adoption Rates and Average Performance Parameters for Short Box Trailers

TECHNOLOGY SHORT BOX

DRY VANS

SHORT BOX

REFRIGERATED VANS

Model Year 2018 2021 2024 2027 2018 2021 2024 2027

Aerodynamic Technologies a

Bin I 100% 5% 100% 5%

Bin II 95% 70% 30% 95% 70% 55%

Bin III 30% 60% 30% 40%

Bin IV 10% 5%

Bin V

Bin VI

Bin VII

Bin VIII

Average Delta CDA (m2) b0.4 0.7 0.8 1.1 0.4 0.7 0.8 1.0

Trailer Tire Rolling Resistance

Baseline tires 15% 5% 5% 5% 15% 5% 5% 5%

Level 1 tires 85% 95% 85% 95%

Level 2 tires 95% 95% 95% 95%

Average CRR (kg/ton) b5.2 5.1 4.8 4.8 5.2 5.1 4.8 4.8

Tire Inflation System

ATI 85% 95% 95% 95% 85% 95% 95% 95%

Average ATI Reduction (%) c1.3% 1.4% 1.4% 1.4% 1.3% 1.4% 1.4% 1.4%

Weight Reduction (pounds)

Weight b

Notes: 

A blank cell indicates a zero value

a

: The majority of short box trailers are 28 feet in length. We recognize that they are often operated in tandem, which limits the 

technologies that can be applied (for example, boat tails). 

b

: Combines projected adoption rates with performance levels shown in Table IV-8

c

: This set of proposed adoption rates did not apply any assumed weight reduction to meet the proposed standards for these 

trailers

Non-aero box trailers, with two or more work-related special components, and non-box 

trailers are not shown in the tables above. We are proposing that manufacturers of these trailers 

meet design-based (i.e., technology-based) standards, instead of performance-based standards 

that would apply to other trailers. That is, manufacturers of these trailers would not need to use 

aerodynamic technologies, but they would need to use appropriate lower rolling resistance tires 

and ATI systems, based on our assessments of the typical CO2 and fuel consumption

performance of this equipment (See Section IV.2.c). Thus, we are projecting 100 percent 

adoption rates of these technologies at each stage of the program. Compared to manufacturers 

that needed aerodynamic technologies to comply, the approach for non-aero box trailers and nonbox trailers would result in a significantly lower compliance burden for manufacturers by

reducing the amount of tracking and eliminating the need to calculate a compliance value (see 

Section I. A. ) The agencies are proposing these design standards in two stages. In 2018, the 

proposed standards would require manufacturers to use tires meeting a rolling resistance of Level 

1 or better and to install ATI systems on all non-box and non-aero box trailers. In 2024, the 

proposed standards would require manufacturers to use LRR tires at a Level 2 or better, and to 

still install ATI systems. We seek comment on all aspects of this design-based standards 

concept. We also seek comment on providing manufacturers with the option of adopting Level 2
Page 282 of 850

tires in the early years of the program (MY 2018-2023) and avoiding the use of ATI systems if 

they chose. 

Table IV-15 Projected Adoption Rates and Average Performance Parameters for Non-Aero Box and NonBox Trailers

TECHNOLOGY NON-AERO BOX

& NON-BOX TRAILERS

Model Year 2018 2021 2024 2027

Aerodynamic Technologies

Bin I 100% 100% 100% 100%

Bin II

Bin III

Bin IV

Bin V

Bin VI

Bin VII

Bin VIII

Average Delta CDA (m2) a0.0 0.0 0.0 0.0

Trailer Tire Rolling Resistance

Baseline tires

Level 1 tires 100% 100%

Level 2 tires 100% 100%

Average CRR (kg/ton) a5.1 5.1 4.7 4.7

Tire Inflation System

ATI 100% 100% 100% 100%

Average ATI Reduction (%) a1.5% 1.5% 1.5% 1.5%

Weight Reduction (pounds)

Weight b

Notes: 

A blank cell indicates a zero value

a

: Combines projected adoption rates with performance levels shown in Table IV-8

b

: This set of adoption rates did not apply weight reduction to meet the proposed standards 

for these trailers

We request comment and any data related to our projections of technology adoption rates. 

The following section (d) explains how the agencies combined these adoption rates with the 

performance values shown previously to calculate the proposed standards. 

(e) Derivation of the Proposed Standards

The average performance parameters from Table IV-14, and Table IV-15 were applied as 

input values to the GEM vehicle simulation to derive the proposed HD Phase 2 fuel consumption 

and CO2 emissions standards for each subcategory of trailers. The proposed standards are shown 

in Table IV-16. The proposed standards for partial-aero trailers, which are not explicitly shown 

in Table IV-16, would be the same as their full-aero counterparts through MY 2026. In MY 

2027 and later, partial aero trailers would continue to meet the MY 2024 standards.

Over the four stages of the proposed rule, box trailers longer than 50 feet would, on 

average, reduce their CO2 emissions and fuel consumption by two percent, four percent, seven 

percent and eight percent compared to their reference cases. Box trailers 50-feet and shorter 
Page 283 of 850

would achieve reductions of two percent, three percent and four percent compared to their 

reference cases. The tire technologies used on non-box and non-aero box trailers would provide 

reductions of two percent in the first two stages and achieve three percent by 2027.

Table IV-16 Proposed Standards for Box Trailers

MODEL 

YEAR

SUBCATEGORY DRY VAN REFRIGERATED VAN

LENGTH LONG SHORT LONG SHORT

2018 - 2020 EPA Standard 

(CO2 Grams per Ton-Mile)

83 144 84 147

Voluntary NHTSA Standard

(Gallons per 1,000 Ton-Mile)

8.1532 14.1454 8.2515 14.4401

2021 - 2023 EPA Standard

(CO2 Grams per Ton-Mile)

81 142 82 146

NHTSA Standard

(Gallons per 1,000 Ton-Mile)

7.9568 13.9489 8.0550 14.3418

2024 - 2026 EPA Standard 

(CO2 Grams per Ton-Mile)

79 141 81 144

NHTSA Standard

(Gallons per 1,000 Ton-Mile)

7.7603 13.8507 7.9568 14.1454

2027 + EPA Standard 

(CO2 Grams per Ton-Mile)

77 140 80 144

NHTSA Standard

(Gallons per 1,000 Ton-Mile)

7.5639 13.7525 7.8585 14.1454

It should be noted that the proposed standards are based on highway cruise cycles that 

include road grade to better reflect real world driving and to help recognize engine and driveline 

technologies. See Section III.E. The agencies have evaluated some alternate road grade profiles 

recommended by the National Renewable Energy Laboratory (NREL) and have prepared 

possible alternative trailer vehicle standards based on these profiles. The agencies request 

comment on this analysis, which is available in a memorandum to the docket.244

(f) Technology Costs for the Proposed Standards

The agencies evaluated the technology costs for 53-foot dry and refrigerated vans and 28-

foot dry vans, which we believe are representative of the majority of trailers in the 50-foot and 

longer and shorter than 50-foot categories, respectively. We identified costs for each technology

package evaluated and projected the costs for each year of the program. A summary of the 

technology costs is included in Table IV-17 through Table IV-20 for MYs 2018 through 2027, 

with additional details available in the draft RIA Chapter 2.12. Costs shown in the following 

tables are for the specific model year indicated and are incremental to the average reference case 

costs, which includes some level of adoption of these technologies as shown in Table IV-13. 

Therefore, the technology costs in the following tables reflect the average cost expected for each 

 

244 Memorandum dated March 2015 on Analysis of Possible Tractor, Trailer, and Vocational Vehicle Standards 

Based on Alternative Road Grade Profiles. Docket EPA-HQ-OAR-2014-0827
Page 284 of 850

of the indicated trailer classes. Note that these costs do not represent actual costs for the 

individual components because some fraction of the component costs has been subtracted to 

reflect some use of these components in the reference case. For more on the estimated 

technology costs exclusive of adoption rates, refer to Chapter 2.12 of the draft RIA. These costs 

include indirect costs via markups and reflect lower costs over time due to learning impacts. For 

a description of the markups and learning impacts considered in this analysis and how 

technology costs for other years are thereby affected, refer to Chapter 7 of the draft RIA. We 

welcome comment on the technology costs, markups, and learning impacts.

Table IV-17 Trailer Technology Incremental Costs in the 2018 Model Year (2012$) 

53-foot

Dry Van

53-foot

Refrigerated Van

28-foot

Dry Van

Non-Aero 

& Non-Box 

Aerodynamics $285 $285 $0 $0

Tires $65 $65 $78 $185

Tire inflation system $239 $239 $435 $683

Total $588 $588 $514 $868

Table IV-18 Trailer Technology Incremental Costs in the 2021 Model Year (2012$)

53-foot

Dry Van

53-foot

Refrigerated Van

28-foot

Dry Van

Non-Aero 

& Non-Box 

Aerodynamics $602 $602 $468 $0

Tires $65 $65 $79 $175

Tire inflation system $234 $234 $426 $632

Total $901 $901 $974 $807

Table IV-19 Trailer Technology Incremental Costs in the 2024 Model Year (2012$)

53-foot

Dry Van

53-foot

Refrigerated Van

28-foot

Dry Van

Non-Aero 

& Non-Box 

Aerodynamics $836 $836 $608 $0

Tires $61 $61 $76 $160

Tire inflation system $220 $220 $412 $578

Total $1,116 $1,116 $1,097 $739

Table IV-20 Trailer Technology Incremental Costs in the 2027 Model Year (2012$)

53-foot

Dry Van

53-foot

Refrigerated Van

28-foot

Dry Van

Non-Aero 

& Non-Box 

Aerodynamics $1,163 $1,034 $788 $0

Tires $54 $54 $74 $155

Tire inflation system $192 $192 $391 $549

Total $1,409 $1,280 $1,253 $704
Page 285 of 850

(4) Consistency of the Proposed Trailer Standards with the Agencies’ Legal 

Authority

The agencies’ initial determination, subject to consideration of public comment, is that 

the standards presented in the Section IV.C.2, are the maximum feasible and appropriate under 

the agencies’ respective authorities, considering lead time, cost, and other factors. The 

agencies’ proposed decisions on the stringency and timing of the proposed standards focused on 

available technology and the consequent emission reductions and fuel efficiency improvements 

associated with use of the technology, while taking into account the circumstances of the trailer 

manufacturing sector. Trailer manufacturers would be subject to first-time emission control and 

fuel consumption regulation under the proposed standards. These manufacturers are in many 

cases small businesses, with limited resources to master the mechanics of regulatory compliance. 

Thus, the agencies’ proposal seeks to provide a reasonable time for trailer manufacturers to 

become familiar with the requirements and the proposed new compliance regime, given the 

unique circumstances of the industry and the compliance flexibilities and optional compliance 

mechanisms specially adapted for this industry segment that we are proposing.

The stringency of the standard is predicated on more widespread deployment of 

aerodynamic and tire technologies that are already in commercial use. The availability, 

feasibility, and level of effectiveness of these technologies are well-documented. Thus the 

agencies do not believe that there is any issue of technological feasibility of the proposed 

standards. Among the issues reflected in the agencies’ proposal are considerations of cost and 

sufficiency of lead-time – including lead-time not only to deploy technological improvements, 

but also this industry sector to assimilate for the first time the compliance mechanisms of the 

proposed rule. 

The highest cost shown in Table IV-20 is associated with the long dry vans. We project 

that the average cost per trailer to meet the proposed MY 2027 standards for these trailers would 

be about $1,400, which is less than 10 percent of the cost of a new dry van trailer (estimated to 

be about $20,000). Other trailer types have lower projected technology costs, and many have 

higher purchase prices. As a result, we project that the per-trailer costs for all trailers covered in 

this regulation will be less than 10 percent of the cost of a new trailer. This trend is consistent 

with the expected average control costs for Phase 2 tractors, which are also less than 10 percent 

of typical tractor costs (see Section III). 

The agencies believe these technologies can be adopted at the rates the standards are 

predicated on within the proposed lead-time, as discussed above in Section IV.C.(3). Moreover, 

we project that most owners would rapidly recover the initial cost of these technologies due to 

the associated fuel savings, usually in less than two years, as shown in the payback analysis in 
Page 286 of 850

Section IX. This payback period is generally considered reasonable in the trailer industry for 

investments that reduce fuel consumption.245

Overall, as discussed above in IV.D.3.c in the context of our assumed technology

adoption rates, the gradual increase in stringency of the proposed trailer program over the phasein period recognizes two important factors that the agencies carefully considered in developing 

this proposed rule. One factor is that assumed adoption of technologies many of the 

aerodynamic technologies that box trailer manufacturers would likely choose are available today

and clearly technologically feasible throughout the phase-period. At the same time, we 

recognize that the adoption of these technologies across the industry scale envisioned by the 

proposed program would likely take time. The standards we are proposing in the interim years 

represent steady improvement in average aerodynamic performance toward the final MY 2027 

standards. 

E. Alternative Standards and Feasibility Considered 

As discussed in Section X, the agencies evaluated several different regulatory alternatives 

representing different levels of stringency for the Phase 2 program. The results of the analysis of 

these proposed alternatives are discussed below in Section X of the preamble. The agencies 

believe each alternative is feasible from a technical standpoint. However, each successive 

alternative increases costs and complexity of compliance for the manufacturers, which can be a 

prohibitive burden on the large number of small businesses in the industry. Table IV-21

provides a summary of the alternatives considered in this proposal.

Table IV-21 Summary of Alternatives Considered for the Proposed Rulemaking

Alternative 1 No action alternative

Alternative 2 Expand the use of aerodynamic and tire technologies at SmartWay levels to all 53-foot 

box trailers

Alternative 3 

(Proposed Alternative)

Adoption of advanced aerodynamic and tire technologies on all box trailers

Adoption of tire technologies on non-box trailers

Alternative 4 Same technology and application assumptions as Alternative 3 with an accelerated 

introduction schedule

Alternative 5 Aggressive adoption of advance aerodynamic and tire technologies for all box trailers 

Adoption of aerodynamic and tire technologies for some tank, flatbed, and container 

chassis trailers

Adoption of tire technologies for the remaining non-box trailers

While we welcome comment on any of these alternatives, we are specifically requesting 

comment on Alternative 4 for the trailer program identified as Alternative 4 above and in Section 

X. The same general technology effectiveness values were considered and much of the 

feasibility analysis was the same in this alternative and in the proposed alternative, but 

 

245 Roeth, Mike, et al. “Barriers to Increased Adoption of Fuel Efficiency Technologies in Freight Trucking”. July 

2013. International Council for Clean Transportation. Available here: 

http://www.theicct.org/sites/default/files/publications/ICCT-NACFE-CSS_Barriers_Report_Final_20130722.pdf
Page 287 of 850

Alternative 4 applies the adoption rates of higher-performing aerodynamic technologies from 

Alternative 3 at earlier stages for box trailers. This accelerated alternative achieves the same 

final fuel consumption and CO2 reductions as our proposed alternative three years in advance. 

The following sections detail the adoption rates, reductions and costs projected for this 

alternative.

(1) Effectiveness, Adoption Rates, and Technology Costs for Alternative 4

Alternative 4 includes the same trailer subcategories and same trailer technologies as the 

proposed alternative. Therefore, the zero-technology baseline trailers (Table IV-7), reference 

case trailers (Table IV-10) and performance levels (Table IV-8) described in Section IV. D. 

apply for this analysis as well. The following sections describe the adoption rates of this 

accelerated alternative and the associated benefits and costs. 

(a) Projected Technology Adoption Rates for Alternative 4

The adoption rates and average performance parameters projected by the agencies for 

Alternative 4 are shown in Table IV-22 and Table IV-23. Adoption rates for non-aero box and 

non-box trailers remain unchanged from the proposed standards and they are not repeated in this 

section. From the tables, it can be seen that the 2018 MY aerodynamic technology adoption 

rates and the tire technology adoption rates for all model years are identical to those presented 

previously for the proposed standards. The aerodynamic projections for MY 2021 and MY 2024 

in this accelerated alternative are the same as those projected for MY 2024 and MY 2027 of the 

proposed standards, but are applied three years earlier. In this alternative, the 2021 MY adoption 

rates would continue to apply for the partial-aero box trailers in 2024 and later model years. 
Page 288 of 850

Table IV-22 Adoption Rates and Average Performance Parameters for the Long Box Trailers in

Alternative 4

TECHNOLOGY LONG BOX

DRY VANS

LONG BOX

REFRIGERATED VANS

Model Year 2018 2021 2024 2018 2021 2024

Aerodynamic Technologies a

Bin I 5% 5%

Bin II

Bin III 30% 30%

Bin IV 60% 25% 60% 25%

Bin V 5% 10% 10% 5% 10% 20%

Bin VI 65% 50% 65% 60%

Bin VII 40% 20%

Bin VIII

Average Delta CDA (m2) a0.4 0.8 1.1 0.4 0.8 1.0

Trailer Tire Rolling Resistance

Baseline tires 15% 5% 5% 15% 5% 5%

Level 1 tires 85% 95% 85% 95%

Level 2 tires 95% 95%

Average CRR (kg/ton) a5.2 5.1 4.8 5.2 5.1 4.8

Tire Inflation System

ATI 85% 95% 95% 85% 95% 95%

Average ATI Reduction (%) a1.3% 1.4% 1.4% 1.3% 1.4% 1.4%

Weight Reduction (pounds)

Weight b

Notes: 

A blank cell indicates a zero value

a

: Combines adoption rates with performance levels shown in Table IV-8

b

: This set of adoption rates did not apply weight reduction to meet the proposed standards for these trailers
Page 289 of 850

Table IV-23 Adoption Rates and Average Performance Parameters for the Short Box Trailers in

Alternative 4

TECHNOLOGY SHORT BOX

DRY VANS

SHORT BOX

REFRIGERATED VANS

Model Year 2018 2021 2024 2018 2021 2024

Aerodynamic Technologies a

Bin I 100% 100%

Bin II 70% 30% 70% 55%

Bin III 30% 60% 30% 40%

Bin IV 10% 5%

Bin V

Bin VI

Bin VII

Bin VIII

Average Delta CDA (m2) b0.4 0.8 1.1 0.4 0.8 1.0

Trailer Tire Rolling Resistance

Baseline tires 15% 5% 5% 15% 5% 5%

Level 1 tires 85% 95% 85% 95%

Level 2 tires 95% 95%

Average CRR (kg/ton) b5.2 5.1 4.8 5.2 5.1 4.8

Tire Inflation System

ATI 85% 95% 95% 85% 95% 95%

Average ATI Reduction (%) b1.3% 1.4% 1.4% 1.3% 1.4% 1.4%

Weight Reduction (pounds)

Weight c

Notes: 

A blank cell indicates a zero value

a

: The majority of short box trailers are 28 feet in length. We recognize that they are often operated in tandem, which 

limits the technologies that can be applied (for example, boat tails).

b

: Combines adoption rates with performance levels shown in Table IV-8

c

: This set of adoption rates did not apply weight reduction to meet the proposed standards for these trailers

(b) Derivation of the Standards for Alternative 4

Similar to the proposed standards of Section IV. D. (3) (d), the agencies applied the 

technology performance values from Table IV-22 and Table IV-23 as GEM inputs to derive the 

proposed standards for each subcategory. 

Table IV-24 shows the resulting standards for Alternative 4. Over the three phases of the 

alternative, box trailers longer than 50 feet would, on average, reduce their CO2 emissions and 

fuel consumption by two percent, six percent and eight percent. Box trailers 50-foot and shorter 

would achieve reductions of two percent, three percent, and four percent compared to the 

reference case. Partial-aero box trailers would continue to be subject to the 2021 MY standards 

for MY 2024 and later. The non-aero box and non-box trailers would meet the same standards as 

shown in the proposed Alternative 3 and achieve the same two and three percent benefits as 

shown in the proposed alternative. 
Page 290 of 850

Table IV-24 Trailer CO2 and Fuel Consumption Standards for Box Trailers in Alternative 4

MODEL

YEAR

SUBCATEGORY DRY VAN REFRIGERATED VAN

LENGTH LONG SHORT LONG SHORT

2018 - 2020 EPA Standard 83 144 84 147

(CO2 Grams per Ton-Mile)

Voluntary NHTSA Standard 8.1532 14.1454 8.2515 14.4401

(Gallons per 1,000 Ton-Mile)

2021 - 2023 EPA Standard 80 142 81 145

(CO2 Grams per Ton-Mile)

NHTSA Standard 7.8585 13.9489 7.9568 14.2436

(Gallons per 1,000 Ton-Mile)

2024+ EPA Standard 77 140 80 144

(CO2 Grams per Ton-Mile)

NHTSA Standard 7.5639 13.7525 7.8585 14.1454

(Gallons per 1,000 Ton-Mile)

(c) Costs Associated with Alternative 4

A summary of the technology costs is included in Table IV-25 to Table IV-27for MYs 

2018, 2021 and 2024, with additional details available in the draft RIA Chapter 2.12. Costs 

shown in the following tables are for the specific model year indicated and are incremental to the 

average reference case costs, which includes some level of adoption of these technologies as 

shown in Table IV-10. Therefore, the technology costs in the following tables reflect the 

average cost expected for each of the indicated trailer classes. Note that these costs do not 

represent actual costs for the individual components because some fraction of the component 

costs has been subtracted to reflect some use of these components in the reference case. For 

more on the estimated technology costs exclusive of adoption rates, refer to Chapter 2.12 of the 

draft RIA. These costs include indirect costs via markups and reflect lower costs over time due 

to learning impacts. For a description of the markups and learning impacts considered in this 

analysis and how it impacts technology costs for other years, refer to the draft RIA.
Page 291 of 850

Table IV-25 Trailer Technology Incremental Costs in the 2018 Model Year for Alternative 4 (2012$) 

53-foot

Dry Van

53-foot

Refrigerated Van

28-foot

Dry Van

Non-Aero 

& Non-Box 

Aerodynamics $285 $285 $0 $0

Tires $65 $65 $78 $185

Tire inflation system $239 $239 $435 $683

Total $588 $588 $514 $868

Table IV-26 Trailer Technology Incremental Costs in the 2021 Model Year for Alternative 4 (2012$)

53-foot

Dry Van

53-foot

Refrigerated Van

28-foot

Dry Van

Non-Aero 

& Non-Box 

Aerodynamics $908 $908 $641 $0

Tires $65 $65 $79 $175

Tire inflation system $234 $234 $426 $632

Total $1,207 $1,207 $1,146 $807

Table IV-27 Trailer Technology Incremental Costs in the 2024 Model Year for Alternative 4 (2012$)

53-foot

Dry Van

53-foot

Refrigerated Van

28-foot

Dry Van

Non-Aero 

& Non-Box 

Aerodynamics $1,223 $1,090 $816 $0

Tires $61 $61 $76 $160

Tire inflation system $220 $220 $412 $578

Total $1,504 $1,371 $1,304 $739

The agencies believe Alternative 4 has the potential to be the maximum feasible and 

appropriate alternative. However, based on the evidence currently before us, EPA and NHTSA 

have outstanding questions regarding relative risks and benefits of Alternative 4 due to the 

timeframe envisioned by that alternative. As discussed earlier, the ability for manufacturers in 

this industry to broadly take the necessary technical steps while becoming familiar with firsttime regulatory responsibilities may be significantly limited with three fewer years of lead-time. 

As reinforced in the SBAR Panel Report, this challenge would not be equal across the industry, 

often falling more heavily on smaller trailer manufacturers. 

The agencies request comment on the feasibility and costs for trailer manufacturers to 

achieve the Alternative 4 standards by applying advanced aerodynamic technologies with three 

years less lead-time than Alternative 3 would provide. The agencies also request comment on 

particular burdens that these aggressive adoption rates could have on small business trailer 

manufacturers. 

F. Trailer Standards: Compliance and Flexibilities 

Under the proposed structure, trailer manufacturers would be required to obtain a 

certificate of conformity from EPA before introducing into commerce new trailers subject to the 

proposed new trailer CO2 and fuel consumption standards. See CAA section 206(a). The 
Page 292 of 850

certification process the agencies are proposing for trailer manufacturers is very similar in its 

basic structure to the process for the tractor program. This structure involves pre-certification 

activities, the certification application and its approval, and end-of-year reporting.

In this section, the agencies first describe how we developed compliance equations based 

on the GEM vehicle simulation tool and the general certification process, followed by a 

discussion of the proposed test procedures for measuring the performance of tires and 

aerodynamic technologies and how manufacturers would apply test results toward compliance 

and certification. The section closes with discussions of several other proposed certification and 

compliance provisions as well as proposed provisions to provide manufacturers with compliance 

flexibility. 

(1) Trailer Compliance using a GEM-Based Equation

The agencies are committed to introducing a compliance program for trailer 

manufacturers that is straightforward, technically robust, transparent, and that minimizes new 

administrative burdens on the industry. As described earlier in this section and in Chapter 4 of 

the draft RIA, GEM is a customized vehicle simulation model that EPA developed for the Phase 

1 program to relate measured aerodynamic and tire performance values, as well as other 

parameters, to CO2 and fuel consumption without performing full-vehicle testing. As with the 

Phase 1 and proposed Phase 2 tractor and vocational vehicle programs, the proposed trailer 

program uses GEM in evaluating emissions and fuel consumption in developing the proposed 

standards. However, unlike the tractor and vocational vehicle programs, we are not proposing to 

use GEM directly to demonstrate compliance with the trailer standards. Instead, we have 

developed an equation based on GEM that calculates CO2 and fuel consumption from 

performance inputs, but without running the model. 

For the proposed trailer program, the trailer characteristics that a manufacturer would 

supply to the equation are aerodynamic improvements (i.e., a change in the aerodynamic drag 

area, delta CDA), tire rolling resistance (i.e., coefficient of rolling resistance, CRR), the presence 

of an automatic tire inflation (ATI) system, and the use of light-weight components from a predetermined list. The use of the equation would quantify the overall performance of the trailer in 

terms of CO2 emissions and fuel consumption on a per ton-mile basis. 

Chapter 2.10.6 of the draft RIA provides a full a description of the development and 

evaluation of the equation proposed for trailer compliance. Equation IV-1 is a single linear 

regression curve that can be used for all box trailers in this proposal. Unique constant values, C1

through C4, are applied for each of the trailer subcategories as shown in Table IV-28. Constant 

C5 is equal to 0.985 for any trailer that installs an ATI system (accounting for the 1.5% reduction 

given for use of ATI) or 1.0 for trailers without ATI systems. This equation was found to 

accurately reproduce the results of GEM for each of the four box van subcategories and the 

agencies are proposing that trailer manufacturers use Equation IV-1 when calculating CO2 for 

compliance. Manufacturers would use a conversion of 10,180 grams of CO2 per gallon of diesel 

to calculate the corresponding fuel consumption values for compliance with NHTSA’s 

regulations. See 40 CFR 1037.515 and 49 CFR 535.6.
Page 293 of 850

 = [ +  ∙ () +  ∙ (∆) +  ∙ ()] ∙ 

(IV-1)

Table IV-28 Constants for GEM-Based Trailer Compliance Equation

TRAILER SUBCATEGORY C1 C2 C3 C4

Long Dry Van 77.4 1.7 -6.1 -0.001

Long Refrigerated Van 78.3 1.8 -6.0 -0.001

Short Dry Van 134.0 2.2 -10.5 -0.003

Short Refrigerated Van 136.3 2.4 -10.3 -0.003

The constants for long vans apply for all dry or refrigerated vans longer than 50-feet and 

the constants for short vans apply for all dry or refrigerated vans 50-feet and shorter. These long 

and short van constants are based on GEM-simulated tractors pulling 53-foot and solo 28-foot 

trailers, respectively. As a result, we are proposing that aerodynamic testing to obtain a trailer’s 

performance parameters for Equation IV-1 be performed using consistent trailer sizes (i.e., all 

lengths of short vans be tested as a solo 28-foot van, and all lengths of long vans be tested as a 

53-foot van). More information about aerodynamic testing is provided in Section IV. F. (3) 

(2) General Certification Process

Under the proposed process for certification, trailer manufacturers would be required to 

apply to EPA for certification and would provide performance test data (see 40 CFR 1037.205) 

in their applications.246 A staff member from EPA’s Compliance Division (in the Office of 

Transportation and Air Quality) would be assigned to each trailer manufacturer to help them 

through the compliance process. Although not required, we recommend that manufacturers 

arrange to meet with the agencies to discuss compliance plans and obtain any preliminary

approvals (e.g., appropriate test methods) before applying for certification. 

Trailer manufacturers would submit their applications through the EPA VERIFY 

electronic database, and EPA would issue certificates based on the information provided. At the 

end of the model year, trailer manufacturers would submit an end-of-year report to the agencies 

to complete their annual obligations.

The proposed EPA certification provisions also contain provisions for applying to the 

NHTSA program. EPA and NHTSA would coordinate on any enforcement action required. 

 

246 As with the tractor program, manufacturers would submit their applications to EPA, which would then share 

them with NHTSA. Obtaining an approved certificate of conformity from EPA is the first step in complying with 

the NHTSA program.
Page 294 of 850

(a) Preliminary Considerations for Compliance

Prior to submitting an application for a certificate, a manufacturer would choose the 

technologies they plan to offer their customers, obtain performance information for these 

technologies, and identify any trailers in their production line that qualify for exclusion from the 

program.247 Manufacturers that choose to perform aerodynamic or tire testing would obtain 

approval of test methods and perform preliminary testing as needed. During this time, the 

manufacturer would also decide the strategy they intend to use for compliance by identifying 

“families” for the trailers they produce. A family is a grouping of similar products that would all 

be subject to the same standard and covered by a single certificate. 

At its simplest, the program would allow all products in each of the trailer subcategories 

to be certified as separate families. That is, long box dry vans, short box dry vans, long 

refrigerated vans, short refrigerated vans, non-box trailers, partial-aero trailers (long and short 

box, dry and refrigerated vans), and non-aero trailers, could each be certified as separate trailer 

families. If a manufacturer chooses this approach, all products within a family would need to 

meet or do better than the standards for that trailer subcategory. This is not to say that, for 

example, every long box dry van model would need to have identical technologies like skirts, 

tires, and tire inflation systems, but that every model in that family would need to have a 

combination of technologies that had performance representative of testing demonstrated for that 

family. (Because the manufacturer would not be using averaging provisions, a trailer that “overcomplied” could not offset a trailer that did not meet that family’s emission limit). 

If a trailer manufacturer wishes to take advantage of the proposed averaging provisions, it 

could divide the trailer models in each of the standard box trailer categories (i.e., not including 

the non-box trailer or non-aero box trailer categories248) into subfamilies. Each subfamily could 

be a grouping of trailers that have with similar performance levels, even if they use different 

technologies. We call the performance levels for each subfamily as “Family Emission Limits” 

(FELs). A long box dry van manufacturer could choose, for example, to create two or more 

subfamilies in its long box dry van family. Trailers in one or more of these subfamilies could be 

allowed to under-comply with the standard (e.g., if the manufacturer chose not to apply ATI or 

chose tires with higher rolling resistance levels) as long as the performance of the other 

subfamilies over-comply with the standard (e.g., if the manufacturer applied higher-performing 

skirts) such that the average of all of the subfamilies’ FELs met or did better than the stringency

for that family on a production-weighted basis. Section IV.F.6.a below further discusses how the 

proposed averaging program would function for any such trailer subfamilies. 

 

247 Trailers that meet the qualifications for exclusion do not require a certificate of conformity and manufacturers do 

not have to submit an application to EPA for these trailers.

248 The agencies are proposing that manufacturers implement 100 percent of their non-box and special purpose box 

trailers with automatic tire inflation systems and tires meeting the specified rolling resistance levels. As a result, 

averaging provisions do not apply to these trailer subcategories.
Page 295 of 850

(b) Submitting a Certification Application and Request for a Certificate to EPA

Once the preliminary steps are completed, the manufacturer can prepare and submit 

applications to EPA for certificate of conformity for each of its trailer families. The contents of 

the application are specified in 40 CFR 1037.205, though not all items listed in the regulation are 

applicable to each trailer manufacturer. 

For the early years of the program (i.e., 2018 through 2020), the application must specify

whether the trailer manufacturer is opting into the NHTSA voluntary program to ensure the 

information is transferred between the agencies. It must also include a description of the 

emission controls that a manufacturer intends to offer. These emission controls could include 

aerodynamic features, tire models, tire inflation systems or components that qualify for weight 

reduction. Basic information about labeling, warranty, and recommended maintenance should 

also be included the application (see Section IV.F.5 for more information).

The manufacturer would also provide a summary of the plans to comply with the 

standard. This information would include a description of the trailer family and subfamilies (if 

applicable) covered by the certificate and projected sales of its products. Manufacturers that do 

not participate in averaging would include information on the lowest level of CO2 and fuel 

consumption performance offered in the trailer family. Manufacturers that choose to average 

within their families would include performance information for the projected highest production 

trailer configuration, as well as the lowest and the highest performing configurations within that 

trailer family.

(c) End-of-Year Obligations

After the end of each year, all manufacturers would need to submit a report to the 

agencies presenting production-related data for that year (see 40 CFR 1037.250 and 49 CFR 

535.8). In addition, manufacturers participating in the averaging program would submit an endof-year report containing both emissions and fuel consumption information for both agencies. 

This report would include the year’s final compliance data (as calculated using the compliance 

equation) and actual sales in order to demonstrate that the trailers either met the standards for 

that year or that the manufacturer generated a deficit to be reconciled within the next three years 

under the averaging provisions (see 40 CFR 1037.730 and 1037.745 and 49 CFR 535.7). All 

certifying manufacturers would need to maintain records of all the data and information required 

to be supplied to EPA and NHTSA for eight years. 

(3) Trailer Certification Test Protocols

The Clean Air Act specifies that compliance with emission standards for motor vehicles 

be demonstrated using emission test data (see CAA section 206(a) and (b)). The Act does not 

require the use of specific technologies or designs. The agencies are proposing that the 

compliance equation shown in Section IV. F. (1) function as the official “test procedure” for 

quantifying CO2 and fuel consumption performance for trailer compliance and certification (as 

opposed to GEM, which serves this function in the tractor and vocational vehicle programs). 

Manufacturers would insert performance information from the trailer technologies applied into 

the equation in order to calculate their impact on overall trailer performance. The agencies are 
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proposing to assign performance levels to ATI systems and specific weight reduction values to 

pre-determined component substitutions. Aerodynamic and tire rolling resistance performance 

would be obtained by the trailer manufacturers. The following sections describe the approved 

performance tests for tire rolling resistance and aerodynamic drag. Non-box and non-aero box 

trailers have tire requirements only. Manufacturers of these trailers will only need to obtain 

results from the tire performance tests. Long and short box trailers are expected to use 

aerodynamic and tire technologies to meet the proposed standards and will need to obtain test 

results from both procedures. See generally proposed 40 CFR part 1037, subpart F for full 

description of the proposed performance tests, and see in particular proposed section 1037.515. 

(a) Trailer Tire Performance Testing

Under Phase 1, tractor and vocational chassis manufacturers are required to input the tire 

rolling resistance coefficient into GEM and the agencies adopted the provisions in ISO 

28580:2009(E)249 to determine the rolling resistance of tires. As described in 40 CFR 

1037.520(c), this measured value, expressed as CRR, is required to be the result of at least three 

repeat measurements of three different tires of a given design, giving a total of at least nine data 

points. Manufacturers specify a CRR value for GEM that may not be lower than the average of 

these nine results. Tire rolling resistance may be determined by either the vehicle or tire 

manufacturer. In the latter case, the tire manufacturer would provide a signed statement 

confirming that it conducted testing in accordance with this part.

Similar to the tractor program, we propose to extend the Phase 1 testing provisions for 

tire rolling resistance to apply to the Phase 2 box trailer program, only without requiring the use 

of GEM. The average rolling resistance value obtained from this test would be used to specify

the tire rolling resistance level (TRRL) for the trailer tires in the compliance equation. Based on 

the current practice for tractors, we expect the trailer manufacturers to obtain these data from tire 

manufacturers. We welcome comments regarding the proposed tire testing provisions as they

relate to the proposed trailer program.

For non-box trailers, the agencies are proposing to use the same test methods to evaluate 

tires, but are proposing to apply a single threshold standard instead of inputting the rolling 

resistance value into the GEM equation. Manufacturers of non-box trailers would comply with 

the rolling resistance standard by using tires with rolling resistance below the threshold. From 

the perspective of the trailer manufacturer, this would be equivalent to a design standard for the 

trailers, even though the standard would be expressed as a performance standard for the tires.

The agencies are considering adopting a program for tire manufacturers similar to the 

provision described in Section IV. F. (3) (b)(iv) for aerodynamic device manufacturers. For 

aerodynamic devices, the agencies are proposing to allow device manufacturers to seek 

preliminary approval of the performance of their devices. Device manufacturers would perform 

the required testing of their device and submit the performance results directly to EPA. We are 

 

249 See http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=44770
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requesting comment on a similar provision for tires. Tire manufacturers could submit their test 

data directly to EPA to show they meet the rolling resistance requirements, and trailer 

manufacturers that choose to use approved tires would merely indicate that in their the 

certification applications.

EPA is also considering adopting regulatory text addressing obligations for tire 

manufacturers. We note that CAA §207(c)(1) requires “the manufacturer” to remedy certain inuse problems and does not limit this responsibility to certificate holders. The remedy process is 

generally called recall, and the regulations for this process are in 40 CFR part 1068, subpart F. 

In the case of in-use problems with trailer tires, EPA is requesting comment on adding regulatory

text that would explicitly apply these provisions to tire manufacturers. In other words, if EPA 

determines that tires on certified trailers do not conform to the regulations in actual use, should 

EPA require the tire manufacturer to recall and replace the nonconforming tires?250

(b) Trailer Aerodynamic Performance Testing

Our proposed trailer aerodynamic test procedures are based on the current and proposed 

tractor procedures for testing aerodynamic control devices, including coastdown, constant speed, 

wind tunnel, and computational fluid dynamics (CFD) modeling. The purpose of the tests is to 

establish an estimate of the aerodynamic drag experienced by a tractor-trailer vehicle in realworld operation. In the tractor program, the resulting CdA value represents the aerodynamic drag 

of a tested tractor assumed to be pulling a specified standard trailer. In the proposed trailer 

program, the CDA value used in the compliance equation would represent the tested trailer pulled 

by a standard tractor. 

To minimize the number of tests required, the agencies are proposing that devices for 

long trailers be evaluated based on 53-foot trailers, and that devices for short trailers be evaluated 

based on 28-foot trailers. Details of the test procedures can be found in 40 CFR 1037.525 and a 

discussion of EPA’s aerodynamic testing program as it relates to the proposed trailer program are 

provided in the draft RIA Chapter 3.2. The following sections outline the testing requirements 

proposed for the long term trailer program, as well as simpler testing provisions that would apply

in the nearer term. 

(i) A to B Testing for Trailer Aerodynamic Performance 

A key difference between the proposed tractor and trailer programs is that while the 

tractor procedures provide a direct measurement of an absolute CDA value for each tractor 

model, the agencies expect a majority of the aerodynamic improvements for trailers will be 

accomplished by adding bolt-on technologies. As a result, we are proposing to evaluate the 

aerodynamic improvements for trailers by measuring a change in CDA (delta CDA) relative to a 

 

250 The agencies are considering such a requirement for trailer tire manufacturers, but not at this time for 

manufacturers of other heavy-duty vehicle components. This is because, for the trailer sector, we believe that the 

small business trailer manufacturers that make up a large fraction of companies in this industry could be uniquely 

challenged if they needed to recall trailers to replace tires. 
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baseline. Specifically, we propose that the trailer tests be performed as “A to B” tests, 

comparing the aerodynamic performance of a tractor-trailer without a trailer aerodynamic device 

to one with the device installed. See Draft RIA Chapter 2.10 for more information on this 

approach. 

As mentioned in Section IV. F. (1) that is consistent with the compliance equations. See 

40 CFR 1037.525 and 49 CFR 535.6. We believe that most trailers longer than 50 feet with 

comparable technologies would perform similarly in aerodynamic testing. We also recognize 

that devices used on some lengths of trailers in the short-van category may perform differently

than those devices perform when used on a representative 28-foot test trailer. 

The agencies are proposing that manufacturers have some flexibility in the devices (or 

packages of devices) that they use with box vans that have lengths different than those of the 

trailers on which the devices/packages were tested (i.e., trailers not 53 or 28 feet long). In such 

situations, a manufacturer could use devices that they believe would be more appropriate for the 

length of the trailer they are producing, consistent with good engineering judgement. For 

example, they could use longer or shorter side skirts than those tested on 53- or 28-foot trailers. 

No additional testing would be required in order to validate the appropriateness of using the 

alternate devices on these trailers.

On average, we believe that testing of a device on a 28-foot test trailer would provide a 

conservative evaluation of the performance of that device on other lengths of short box trailers. 

We believe that the proposed compliance approach would effectively represent the performance 

of such devices on the majority of short van trailers, yet would limit the number of trailers a 

manufacturer would need to track and evaluate. We request comment, including data where 

possible, on additional approaches that could be used to address this issue of varying 

performance for devices across the range of short van lengths. Commenters supporting an 

allowance or requirement to test devices on short van trailers of other lengths than 28 feet are 

encouraged to also address how the agencies should consider such a provision in setting the 

levels of the standards, as well as how any additional compliance complexity would be justified.

The agencies note that it was relatively straightforward in Phase 1 to establish a standard 

trailer with enough specificity to ensure consistent testing of tractors, since there are relatively 

small differences in aerodynamic performance of base-model dry van trailers. However, as 

discussed in Chapter 2.10 of the draft RIA, small differences in tractor design can have a 

significant impact on overall tractor-trailer aerodynamic performance. An advantage of an A to 

B test approach for trailers is that many of the differences in tractor design are canceled-out, 

which allows a variety of standard tractors to be used in testing without compromising the 

evaluation of the trailer aerodynamic technology. Thus, the relative approach does not require 

the agencies to precisely specify a standard tractor, nor does it require trailer manufacturers to 

purchase, modify or retain a specific tractor model in order to evaluate their trailers. 

In essence, an A to B test is a set of tests: one test of a baseline tractor-trailer with zero 

trailer aerodynamic technologies (A), and one test that includes the aerodynamic devices to be 

tested (B). However, because an A test would relate to a B test only with respect to the test 

method and the test trailer length, one A test could be used for many different B tests. This type 

of testing would result in a delta CDA value instead of an absolute CDA value. For the trailer 
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program, the vehicle configuration in the A test would include a standard tractor that meets 

specified characteristics,251 and a manufacturer’s baseline trailer with no aerodynamic 

improvements. The entity conducting the testing (e.g., the trailer manufacturer or the trailer 

aerodynamic device manufacturer, as discussed below) would perform the test for this 

configuration according to the procedures in 40 CFR 1037.525 and repeat the test for the B 

configuration, which includes the trailer aerodynamic package/device(s) being tested. The delta 

CDA value for that trailer with that device would be the difference between the CDA values 

obtained in the A and B tests. 

In the event that a trailer manufacturer makes major changes to the aerodynamic design 

of its trailer in lieu of installing add-on devices, trailer manufacturers would use the same 

baseline trailer for the A configuration as would be used for bolt-on features. In both cases, the 

baseline trailer would be a manufacturer’s standard box trailer. Thus, the manufacturer of a 

redesigned trailer would get full credit for any aerodynamic improvements it made. We request 

comment on this issue. In addition, we request comment on how the program could handle a 

situation where a manufacturer made aerodynamic design changes to a trailer between 28 and 50 

feet, which as proposed could only be compared to a 28-foot standard trailer. 

The agencies are proposing to determine the delta CDA for trailer aerodynamics using the 

zero-yaw (or head-on wind) values. The agencies are not proposing a reference method (i.e., the 

coastdown procedure in the tractor program). Instead, we are proposing to allow manufacturers 

to perform any of the proposed test procedures to establish a delta CDA. Since the proposed 

coastdown and constant speed procedures include wind restrictions, we are proposing to only 

accept the zero-yaw values from aerodynamic evaluation techniques that are capable of 

measuring drag at multiple yaw angles (e.g., wind tunnels and CFD) to allow cross-method 

comparison and certification. The agencies welcome comment on the pros and cons of exclusive 

use of zero-yaw data from trailer aerodynamic compliance testing. We recognize that the

benefits of aerodynamic devices can be higher when measured considering wind from other yaw 

angles. We request comment on the possibility of allowing manufacturers to use wind-averaged 

results for compliance if they choose to test using procedures that provide wind-averaged values. 

Chapter 2.10 of the draft RIA compares zero-yaw and wind-averaged results from EPA’s wind 

tunnel testing. We request that commenters provide test data to support any preference for 

compliance test results. We also request comments on strategies that could be used to maintain 

consistency with other methods that cannot provide wind-averaged results. 

(ii) Standard Tractor for Aerodynamic Testing in the Proposed Trailer Program 

We propose that the proposed compliance equation, based on GEM, be used to determine 

compliance with the trailer standards. Our discussion of the feasibility of our proposed standards 

(Section IV. D. (3) (a)) includes a description of the tractor-trailer vehicle used in GEM. We 

recognize the impact of the tractor and want to maintain consistency with GEM, but for the 

 

251 As explained in Section IV. F. (3) (b)(ii), the standard tractor in GEM consists of a high roof sleeper cab for box 

trailers longer than 50 feet and a high roof day cab for box trailers 50 feet and shorter.
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trailer program it is not necessary to address all aspects (e.g., the engine) of the tractor, because, 

as explained above, the impact of many of its features will be canceled-out with the use of an A 

to B test strategy. However, some aerodynamic design features of the tractor can influence the 

performance of trailer aerodynamic technologies and we want to ensure a level of consistency

between tests of different trailer manufacturers. 

The agencies believe the A to B test strategy would reduce the degree of precision with 

which the standard tractor needs to be specified. Instead of identifying a specific make and 

model of a tractor to be used over the entire duration of the program, the agencies would instead 

identify key characteristics of a standard tractor. EPA’s trailer testing program investigated the 

impact of tractor aerodynamics on the performance of trailer aerodynamic technologies, as 

mentioned in Chapter 2.10 of the draft RIA. In order to maintain a minimal level of 

performance, we are proposing that tractors used in trailer aerodynamic tests meet Phase 2 Bin 

III or better tractor requirements (See Section III.D.). We believe the majority of tractors in the 

U.S. trucking fleet will be Bin III or better in the timeframe of this rulemaking, and trailer 

manufacturers have the option to choose higher-performing tractors in later years as tractor 

technology improves. The standard tractor for long-box trailers is a Class 8 high-roof sleeper 

cab. The standard tractor for short box trailers is a Class 8 high roof day cab. Trailer 

manufacturers are free to choose any standard tractor that meets these criteria in their 

aerodynamic performance testing. See 40 CFR 1037.501.

(iii) Bins for Aerodynamic Performance

As mentioned in Section IV. D. (1) (a), the agencies are proposing aerodynamic bins to 

account for testing variability and to provide consistency in the performance values used for 

compliance. These bins were developed in terms of delta CDA ranges, and designed to be broad 

enough to cover the range of uncertainty seen in our aerodynamic testing program in terms of 

test-to-test variability as well as variability due to differences in test method, tractor models, 

trailer models and device models. 

As discussed in Chapter 2.10 of the draft RIA, measured drag coefficients and drag areas 

vary depending on the test method used. In general, values measured using wind tunnels and 

CFD tend to be lower than values measured using the coastdown method. The Phase 1 and 

proposed Phase 2 tractor program use coastdown testing as the reference test method, and the 

agencies require tractor manufacturers to perform at least one test using that method to establish 

a correction factor (called “Falt,aero”) to apply to any of the alternative test methods. For 

simplicity, the agencies are not proposing a similar approach for trailers. We believe that the 

size of the bins and the use of change in CDA (as opposed to absolute values) would minimize 

the significance of this variability. However, we recognize that this could be a problem in 

instances where a manufacturer using a method other than coastdown produces a trailer with 

performance near the upper end of a bin. In such cases, it is possible that adjusting for 

methodological differences using an Falt,aero would allow the manufacturer to achieve a more 

stringent bin. 

We request comment on the proposed approach for evaluating performance of trailers and 

establishing bins for trailer compliance. We specifically request that commenters address the 

need for an aerodynamic reference test for trailer performance or additional strategies for 
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normalizing test methods. For example, would it be appropriate to allow all manufacturers using 

wind tunnel or CFD methods to apply an assigned Falt,aero of 1.10, or another value, to their 

results?

Table IV-29 Aerodynamic Bins Used to Determine Inputs for Trailer Certification

DELTA CDA 

MEASURED IN 

TESTING

BIN AVERAGE 

DELTA CDA 

INPUT FOR GEM

0.09 Bin I 0.0

0.10 - 0.19 Bin II 0.1

0.20 - 0.39 Bin III 0.3

0.40 - 0.59 Bin IV 0.5

0.60 - 0.79 Bin V 0.7

0.80 - 1.19 Bin VI 1.0

1.20 - 1.59 Bin VII 1.4

> 1.6 Bin VIII 1.8

A manufacturer that wished to perform testing would first identify a standard tractor 

(according to 40 CFR 1037.525) and a representative baseline trailer with no aerodynamic 

features, then perform the A to B tests with and without aerodynamic devices and obtain a delta 

CDA value. The manufacturer would use Table IV-29 to determine the appropriate bin based on 

their delta CDA. Each bin has a corresponding average delta CDA value which is the value 

manufacturers insert into the compliance equation.

(iv) Aerodynamic Device Testing Alternative

The agencies recognize that much of the trailer manufacturing industry may have little 

experience with aerodynamic performance testing. As such, we are proposing an alternative 

compliance option that we believe will minimize the testing burden for trailer manufacturers, 

meet the requirements of the Clean Air Act and of EISA, and provide reasonable assurance that 

the anticipated CO2 and fuel consumption benefits of the program will be realized in real-world 

operation. 

The agencies are proposing to allow trailer aerodynamic device manufacturers to seek 

preliminary approval of the performance of their devices (or combinations of devices) based on 

the same performance tests described previously in Section IV. F. (3) (b)(i). Device 

manufacturers would perform the required A to B testing of their device(s) on a trailer that meets 

the requirements specified in 40 CFR 1037.211 and 1037.525 and submit the performance 

results, in terms of delta CDA, directly to EPA.252 Trailer manufacturers could then choose to use 

these devices and apply their performance levels in the certification application for their trailer 

families. This approach would provide an opportunity for trailer manufacturers to choose 

 

252 Note that in the event a device manufacturer chooses to submit such data to EPA, it could incur liability for 

causing a regulated entity to commit a prohibited act. See 40 CFR section 1068.1(c). This same potential liability 

exists with respect to information provided by a device manufacturer directly to a trailer manufacturer. 
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technologies with pre-approved test data for installation on their new trailers without performing 

their own aerodynamic testing. We note that this proposed testing alternative is consistent with 

recommendations of the SBAR Panel. The Panel Report is summarized below in Section XV.D. 

If trailer manufacturers wish to use multiple devices with pre-approved test data, the 

proposed program provides a process for combining the effects of multiple devices to determine 

an appropriate delta CDA value for compliance. More specifically, such manufacturers would 

fully count the technology with largest delta CDA value, discount the second by 10 percent, and 

discount each of the remaining additional technologies by 20 percent.

253

 This discounting would 

acknowledge the complex interactions among individual aerodynamic devices and would 

provide a conservative value for the impact of the combined devices. For example, a 

manufacturer applying three separately tested devices with delta CDA values of 0.40, 0.30, and 

0.10 would calculate the combined delta CDA as: 

Delta CDA = 0.40 + 0.90*0.30 + 0.80*0.10 = 0.75 m2

In addition, the agencies believe that discounting the delta CDA values of individuallytested devices used as a combination would provide a modest incentive for trailer or device 

manufacturers to test and get EPA pre-approval of the combination as an aerodynamic system for 

compliance. We propose that device manufacturers be allowed to test and receive EPA preapproval for combinations of devices, and that trailer manufacturers that wish to use those 

specific combinations be allowed to use the results from the tests of the combined devices.

The agencies propose that this alternative testing approach – whereby device 

manufacturers rather than trailer manufacturers do aerodynamic testing – be an interim measure, 

although we are not proposing an end date at this time. Rather we would monitor use of this 

option and make changes in the future as necessary. The agencies note that many of the largest 

box trailer manufacturers are already performing aerodynamic test procedures to some extent, 

and the agencies expect other box trailer manufacturers will increasingly be capable of 

performing these tests as the program progresses. 

The proposed alternative testing approach is intended to allow trailer manufacturers to 

focus on and become familiar with the certification process in the early years of the program and, 

if they wish, begin to perform testing in the later years, when it may be more appropriate for their 

individual companies. This approach would not preclude trailer manufacturers from performing 

their own testing at any time, even if the technologies they wish to install are already preapproved. For example, a manufacturer that believed a specific trailer actually performed in a 

more synergistic manner with a given device than the device’s pre-approved delta CDA value 

suggested could perform its own testing and submit the results to EPA for certification. The 

process to obtain approval is outlined in the proposed 40 CFR 1037.150(n) and 1037.211.

 

253 A trailer manufacturer would need to use good engineering judgement in combining devices for compliance in 

order to avoid combinations that are not intended to work together (e.g., both a side skirt and an under-body device).
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(4) Use of the Compliance Equation for Trailer Compliance

The agencies are proposing standards for non-box and non-aero box trailers requiring the 

use of tires with rolling resistance levels at or below a threshold, and on ATI systems. As part of 

their certification application, manufacturers of these trailers would submit their tire rolling 

resistance levels and a description of their ATI system(s) to EPA. As long as the trailer 

manufacturer certifies that they will install the appropriate tires and ATI systems on all of their 

trailers, the agencies do not believe it is necessary to require these trailer manufacturers to use 

the equation and report the results of the model to the agencies to demonstrate compliance. 

Box trailer manufacturers who apply more than tire technologies to meet the standards 

would use the compliance equation to combine the effects of these technologies and quantify the 

overall performance of the vehicle to demonstrate compliance. Trailer manufacturers would 

obtain delta CDA and tire rolling resistance values from testing (either from their own testing or 

testing performed by another entity as described previously) and note if they installed a 

qualifying automatic tire inflation system or made a component substitution that qualifies for 

weight reduction. Manufacturers would directly apply the delta CDA and TRRL values into the 

equation, which would also recognize the use of an ATI system, applying a 1.5 percent reduction 

in CO2 and fuel consumption. Qualifying components for weight reduction can be found in 40 

CFR 1037.515(d). Manufacturers that substitute one or more of these components on their box 

trailers would sum the weight reductions assigned to each component and enter that total into the

equation. The equation would also account for the use of weight-reducing components, 

assigning one-third of that reduced weight to increase the payload and the remaining weight 

reduction to reduce the overall weight of the assumed vehicle. 

For this proposal, we are requiring that the equation be used if the manufacturer is to take 

advantage of the agencies’ proposed averaging provisions. Prior to submitting a certificate 

application, manufacturers would decide which technologies to make available for their 

customers and use the equation to determine the range performance of the packages they will 

offer. Manufacturers would supply these results from the equation in their certificate application 

and those manufacturers that wish to perform averaging would continue to calculate emissions 

(and fuel consumption) with the equation throughout the model year and keep records of the 

results for each trailer package sold. As described in Section IV.F.2.c above, at the end of the 

year, manufacturers would submit two reports. One report would include their production 

volumes for each configuration. The second report, required for manufacturers using averaging, 

would summarize the families and subfamilies, and CO2 emissions and fuel consumption results 

from the equation for all of the trailer configurations they build.254

Box trailer manufacturers that do not participate in averaging would also use the 

compliance equation to ensure that all of the trailer configurations they offer would meet the 

 

254 We are not proposing to allow manufacturers to “bank” credits to the following year if a manufacturer overcomplies on average for a given model year. We are proposing to allow manufacturers to generate temporary 

deficits if they under-comply on average. These deficits would need to be resolved within three model years. See 

Section IV.F.7.a below and 40 CFR 1037.250, 40 CFR 1037.730, and 49 CFR 535.7
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standard for the given model year. These calculations using the equation could be performed by

the manufacturer prior to submitting a certificate application, but it is not necessary for the 

manufacturer to continue to calculate emissions and fuel consumption throughout the model year 

unless a new technology package is offered. These manufacturers would submit a single end-ofyear report that would include their production volumes and confirmation that all of their trailers 

applied the technology packages outlined in their application. 

(5) Additional Certification and Compliance Provisions

(a) Trailer Useful Life 

Section 202(a)(1) of the CAA specifies that EPA is to propose emission standards that are 

applicable for the “useful life” of the vehicle. Based on our own research and discussions with 

trailer manufacturers, EPA and NHTSA are proposing a regulatory useful life value for trailers 

of 10 years. This useful life represents the average duration of the initial use of trailers, before 

they are moved into less rigorous (e.g., limited use or storage) duty. We note that the useful life 

value is 10 years for other heavy-duty vehicles. However, unlike the other vehicles, we are not 

proposing to set a mile value for trailers because we do not require odometers for trailers.

Thus, we propose that trailer manufacturers be responsible for meeting the CO2 emissions 

and fuel consumption standards for 10 years after the trailer is produced. We believe that 

manufacturers would be able to demonstrate at certification that their trailers will comply for the 

useful life of the trailers without durability testing. The aerodynamic technologies that we 

expect manufacturers to use to comply with the proposed standards, including side skirts and 

boat tails, are designed to continue to provide their full potential benefit indefinitely as long as 

no serious damage occurs. (See also Section IV.C.6 above describing why we are not proposing 

separate in-use standards).

Regarding trailer tires, we recognize that the original lower rolling resistance tires will 

wear over time and will be replaced several times during the useful life of a trailer, either with 

new or retreaded tires. As with the Phase 1 tractor program, to help ensure that trailer owners 

have sufficient knowledge of which replacement tires to purchase in order to retain the ascertified emission and fuel consumption performance of their trailer for its useful life, we are 

proposing to require that trailer manufacturers supply adequate information in the owner’s 

manual to allow the trailer owner to purchase replacement tires meeting or exceeding the rolling 

resistance performance of the original equipment tires. We believe that the favorable fuel 

consumption benefit of continued use of LRR tires would generally result in proper replacements 

throughout the 10-year useful life. Finally, we are requiring that ATI systems remain effective 

for at least the 10 year useful life, although some servicing may be necessary. (See the 

maintenance discussion in Section IV.D.4.e). 

(b) Emission Control Labels

Historically, EPA-certified vehicles are required to have a permanent emission control 

label affixed to the vehicle. The label facilitates the identification of the vehicle as a certified 

vehicle. For the trailer program, EPA proposes that the labels include the same basic 
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information as we are proposing to require for tractor labels. For trailers, this information would 

include the manufacturer, a trailer identifier such as the Vehicle Identification Number, the 

trailer family and regulatory subcategory, the date of manufacture, and compliance statements. 

Although the proposed Phase 2 label for tractors would not include emission control system 

identifiers (as previously required for tractors in the Phase 1 program in 40 CFR 1037.135(b) 

(6)), we are proposing that these identifiers be included in the trailer labels. As for tractors, we 

would require manufacturers to maintain records that would allow us to verify that an individual 

trailer was in its certified configuration.

(c) 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 the 

proposed trailer program, EPA would require trailer manufacturers to warrant all components 

that form the basis of the certification to the CO2 emission standards. The emission-related 

warranty would cover all aerodynamic devices, lower rolling resistance tires, automatic tire 

inflation systems, and other components that may be included in the certification application. 

The trailer manufacturer would need to warrant that these components and systems are 

designed to remain functional for the warranty period. Based on the historical practice of 

requiring emissions warranties to apply for half of the useful life, we propose that the warranty 

period for trailers be 5 years for everything except tires. For trailer tires, we propose to apply a 

warranty period of 1 year. Manufacturers could offer a more generous warranty if they chose; 

however the emissions related warranty may not be shorter than any other warranty offered 

without charge for the vehicle. If aftermarket components were installed (unrelated to emissions 

performance) that offer a longer warranty, this would not impact emission related warranty 

obligations of the vehicle manufacturer. NHTSA is not proposing any warranty requirements 

relating to its trailer fuel consumption program. 

At the time of certification, manufacturers would need to supply a copy of the warranty 

statement that they would supply to the end customer. This document would outline what is 

covered under the GHG emissions related warranty as well as the duration of coverage. 

Customers would also have clear access to the terms of the warranty, the repair network, and the 

process for obtaining warranty service.

(d) Maintenance

In general, EPA requires that vehicle manufacturers specify maintenance schedules to 

keep their product in compliance with emission standards throughout the useful life of the 

vehicle (CAA section 207). For trailers, such maintenance could include fairing adjustments or 

service to ATI systems. However, EPA believes that any such maintenance is likely to be 

performed by operators to maintain the fuel savings of the components, and we are not proposing 

that trailer manufacturers be required submit a maintenance schedule for these components as 

part of its application for certification. 

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 
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important to clarify how tires would fit into the emission-related maintenance requirements. 

Although the agencies encourage the exclusive use of LRR tires throughout the life of trailers 

vehicles, we do not propose to hold trailer manufacturers responsible for the actions of operators. 

We do not see this as problematic because we believe that trailer operators have a genuine 

financial motivation for ensuring their vehicles are as fuel efficient as possible, which includes 

purchasing LRR replacement tires. Therefore, as mentioned in Section IV.F.5.a above, to help 

ensure that trailer owners have sufficient knowledge of which replacement tires to purchase in 

order to retain the as-certified emission and fuel consumption performance of their trailer, we are 

proposing to require that trailer manufacturers supply adequate information in the owner’s 

manual to allow the trailer owner to purchase tires meeting or exceeding the rolling resistance 

performance of the original equipment tires. We would require that these instructions be 

submitted to EPA as part of the application for certification.

(e) Post-Useful Life Modifications

Under 40 CFR part 1037, it is generally prohibited for any person to remove or render 

inoperative any emission control device installed to comply with the requirements of part 1037. 

However, in 40 CFR 1037.655 EPA clarifies that certain vehicle modifications are allowed after 

a vehicle reaches the end of its regulatory useful life. EPA is proposing for this section to apply

trailers, since it applies to all vehicles subject to part 1037, and requests comment on it. 

Generally, this section clarifies that owners may modify a vehicle for the purpose of 

reducing emissions, provided they have a reasonable technical basis for knowing that such 

modification will not increase emissions of any other pollutant. In the case of trailers, this 

essentially requires a trailer owner to have information that would lead an engineer or other 

person familiar with trailer design and function to reasonably believe that the modifications will 

not increase emissions of any regulated pollutant. Thus, this provision does not provide a 

blanket allowance for modifications after the useful life.

This section does not apply with respect to modifications that occur within the useful life 

period, other than to note that many such modifications to the vehicle during the useful life are 

presumed to violate 42 U.S.C 7522(a)(3)(A). EPA notes, however, that this is merely a 

presumption, and would not prohibit modifications during the useful life where the owner clearly 

has a reasonable technical basis for knowing the modifications would not cause the vehicle to 

exceed any applicable standard.

(6) Flexibilities

The trailer program that the agencies are proposing incorporates a number of provisions 

that would have the effect of providing flexibility and easing the compliance burden on trailer 

manufacturers while maintaining the expected CO2 and fuel consumption benefits of the 

program. Among these is the basic approach we used in setting the proposed standards, 

including the staged phase-in of the standards, which would gradually increase the CO2 and fuel 

consumption reductions that manufacturers would need to achieve over time as they also 

increase their experience with the program. As described in the general certification discussion 

above (Section IV.F.2), another proposed provision would allow trailer manufacturers to 

designate broad trailer families that would aggregate several models with similar technologies or 
Page 307 of 850

performance, thus potentially limiting the number of families and the associated family-level 

compliance requirements. 

In addition to these provisions inherent to the proposed trailer program, the agencies are 

proposing additional options for certification that we believe would be very valuable to many

trailer manufacturers. One of these is the proposed process for component manufacturers to 

submit test data directly to EPA for review by the agencies in advance of formal certification, 

allowing a trailer manufacturer to reduce the amount of testing needed to demonstrate 

compliance or avoid it altogether. (See Section IV.F.4 above).

(a) Proposed Averaging Provisions

The agencies are also proposing a limited averaging program as a part of the trailer 

compliance process for box trailers. This program would be similar to the Phase 1 averaging 

program for other sectors, but would be narrower in scope to reflect the unique competitive 

aspects of the trailer market. The trailer manufacturing industry is very competitive, and 

manufacturers must be highly responsive to their customers’ diverse demands. Compared to 

other industry sectors, this reality can limit the value of the flexibility that averaging could 

provide to trailer manufacturers, since they can have little control over what kinds of trailer 

models their customers demand and thus limited ability to manage the mix and volume of 

different products. In addition, the majority of trailer manufacturers have very few basic trailer 

models to offer, potentially putting them at a competitive disadvantage to the small number of 

larger companies that would be in a position to meet market demands that the smaller companies 

could not. For example, one of the larger, more diverse manufacturers could potentially supply a 

customer with trailers that had few if any aerodynamic features, while offsetting this part of their 

business with over-complying trailers that they were able to sell to another customer; many

smaller companies with limited product offerings might not be able to compete for those 

customers. 

Although we recognize that there might be potential negative impacts on at least some 

trailer manufacturers of an averaging program, we believe that there may be overall value to such 

a program. We propose that full-aero box trailer manufacturers may optionally comply with 

their standards on average for a trailer family in any given model year. We are not proposing to 

allow partial-aero box trailers to average. Instead, all trailers in partial-aero families would need 

to meet the standard for that subcategory. We are proposing to allow a trailer manufacturer to

combine partial-aero box trailers with the corresponding full-aero trailer family and reduce the 

number of certification applications required. We expect this to be particularly beneficial to 

manufacturers in the early years of the program, when these two trailer categories have identical 

standards. Although this option should reduce the compliance paperwork, the partial-aero 

trailers would not be able to adopt enough technologies to meet the full-aero standards in the 

later years, and manufacturers would have the option of creating a separate family for these 

trailers. Additionally, we are proposing to allow refrigerated trailers to combine with the dry

vans of the same length and meet the dry van standards and to allow short box vans to combine 

with their long box counterparts to meet the long box standards. 

Unlike averaging programs in other sectors, including those in this Phase 2 program, we 

propose that averaging be limited to a single model year, and manufacturer not be allowed to 
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“bank” credits generated from over-compliance in one year for use in a future year. In other 

words, a manufacturer that produces some trailers in a family that perform better than required 

by the applicable standard would be allowed to produce a number of trailers that do not meet the 

standards, provided the average of the trailers it produces in any given model year is at or below 

the standards. A trailer family performing better than the standard would not be allowed to bank 

credits for a future model year.255 However, as a temporary recourse for unexpected challenges 

in a given model year, we propose that manufacturers be allowed to generate a deficit that would 

be resolved within the next three model years, and to allow the manufacturer to use credits they

generate from over-compliance in subsequent years to address deficits from prior model years. 

As discussed below, we are not proposing this allowance for non-box trailers or non-aero trailers.

We recognize that at each stage of the program, there may be a small fraction of trailer 

applications for which the trailer manufacturers cannot easily apply all of the aerodynamic and 

tire technologies. Thus the proposed dry and refrigerated van standards are designed in the form 

of family average performance, meaning that each trailer manufacturer would comply on average 

across the trailer families it produces within each subcategory category (or family). The 

proposed program would allow a manufacturer, for example, to comply without full adoption of 

aerodynamic devices across 100 percent of its box trailer production in a trailer family, as long 

as it also produced a sufficient number of trailers within that family that performed better than 

the standard, such that the overall production-weighted CO2 and fuel consumption results of the 

trailer models in that family complied with the appropriate standard. 

In addition to the flexibility created by averaging, the proposed box trailer standards 

themselves are not predicated on a set adoption rate of any one technology. Manufacturers 

would be free under the proposed averaging program to choose to apply the appropriate number 

and type of technologies that met their customers’ needs and the level of performance required 

within a particular trailer family. The proposed rules in general do not mandate inclusion of any 

particular technology or other means of emission control. The agencies believe that, ordinarily, 

averaging would create an incentive for manufacturers to promote high-performing technologies 

for some customers, beyond the requirements for that given year, in order to provide other 

customers with trailers with fewer aerodynamic technologies.

The agencies also recognize, however, that an averaging program would inherently 

require a higher degree of data management, record keeping, and reporting than one without 

averaging. Recognizing that this could impose burdens, especially on small business 

manufacturers, the agencies are proposing that the averaging provisions be optional; a box trailer 

manufacturer could choose whether to use averaging for any or all of its standard box trailer 

subcategories (families), or to forego averaging and simply meet the standards with 100 percent 

of the production within each family. Also, unlike some other regulated motor vehicle sectors, 

we are not proposing that credits from over-compliance be able to be “banked” for use in a later 

 

255 Section IV.F.2 describes the process of identifying trailer families and sub-families based on basic trailer 

characteristics. Section 1037.710 of the proposed regulations describes the provisions for establishing subfamilies 

within a trailer family and the Family Emission Limits that would be averaged among the subfamilies. 
Page 309 of 850

model year, or to be “traded” among trailer manufacturers, since they would exacerbate the 

competitive issues, especially for small manufacturers, as discussed immediately below. 

However, we are proposing to apply to trailers the provisions of Phase 1 for tractors that allow 

for the generation of a compliance deficit that could be resolved over several years. Thus, a 

manufacturer that chose to use averaging, but by the end of the production year found that a 

trailer family’s CO2 and fuel consumption values did not reach that year’s standards, could carry

a “deficit” that would need to be resolved by the third year following. 

The availability of averaging options also has the potential to be a disadvantage to some 

companies in a competitive market that is highly customer-driven. During the SBREFA process, 

several manufacturers expressed concern about their ability to manage their credit balances in a 

highly competitive market. Many believe that they would have little ability to essentially force 

their customers to purchase the technology, especially if other manufacturers that had credits 

were able to sell trailers without the technology. We see this as especially problematic for nonbox trailers, which are much more likely to be produced by small businesses, and for which 

customers may have less interest in fuel savings technologies since they are less often used longhaul applications than are box trailers. For these reasons, we are proposing averaging only for 

dry and refrigerated vans. 

The agencies understand that averaging is unfamiliar to many trailer manufacturers and 

other stakeholders. We have drafted a supplementary document that includes example scenarios 

to illustrate the concept of averaging for a hypothetical box trailer manufacturer.256 Example 

adoption rates are provided for a standard compliance strategy (no averaging) and a strategy

using the proposed averaging provisions. 

One value of averaging that the agencies have historically cited in several other motor 

vehicle regulatory programs is that the availability of averaging provisions made it possible for 

the agencies to propose and enact more stringent standards than would otherwise have been 

appropriate, recognizing that the expected flexibility of averaging provisions would ease the path 

to compliance by the more challenged members of the industry. In the case of trailer 

manufacturers, however, our decisions on the proposed stringency of the standards is essentially

independent of the presence or absence of averaging, since, as discussed above, averaging 

provisions may have relatively less value to manufacturers in this customer-driven industry and 

we did not speculate about much or how little it might be used.

We also request comment on whether the burden of managing an averaging program 

could be more trouble than the flexibility is worth. In the event that averaging were not allowed, 

the agencies would need to require that all trailers meeting specified characteristics meet a 

minimum stringency level without averaging. If we were to finalize such non-averaging 

standards, manufacturers would still be allowed to select the appropriate technology package that 

best achieved their emission performance level, but they would not have the ability to 

 

256 Memorandum dated March 2015 on Example Compliance Scenarios for the Proposed GHG Phase 2 Trailer 

Program. Docket EPA-HQ-OAR-2014-0827
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accommodate customers that may request trailers that perform less well on an individual trailer 

basis.

It is also worth noting that the agencies are not proposing to allow any generation of early 

credits before MY 2018. It is clear to us that small businesses would be less prepared to begin 

complying early than larger businesses, and that allowing large manufacturers to generate early 

credits that could be used later could put small businesses at a competitive disadvantage. It does 

not appear to us that there would be a sufficient broader programmatic benefit from early credits 

to justify such an adverse impact on small businesses.

We request comment on this proposed averaging option, including whether the program 

should allow credit and deficit banking and credit trading, as well as on any other potential 

provisions that could provide compliance flexibility for trailer manufacturers while achieving the 

goals of the overall program. Comments supporting averaging, banking, or trading should 

explain how these provisions would be valuable for trailer manufactures across the industry, 

including how the provisions would maintain a “level playing field.” 

(b) Proposed SmartWay-Based Certification

Since many manufacturers have some experience with the SmartWay program, the 

agencies are proposing a gradual transition to the proposed approach that recognizes the parallel 

SmartWay Technology Program. The agencies expect aerodynamic device manufacturers to 

continue to submit test data to SmartWay for verification. Device manufacturers that also wish 

to have their technology available for trailer manufacturers to use in the Phase 2 program could, 

in parallel, submit their test data to EPA for pre-approval for Phase 2 (see Section IV.F.4). The 

information obtained by EPA from the device manufacturers would include the technology

name, a description of its proper installation procedure, and its corresponding delta CDA derived 

from the approved test procedures. Any manufacturers that attained SmartWay verification prior 

to January 1, 2018 would be eligible to submit their previous data to EPA’s Compliance Division 

for pre-approval, provided their test results come from SmartWay’s 2014 test protocols that 

measure a delta CDA. The protocols for coastdown, wind tunnel, and computational fluid 

dynamics analyses result in a CDA value. Note that SmartWay’s 2014 protocols allow SAE 

J1321 Type 2 track testing, which generates fuel consumption results, not CDA values. The 

agencies request comment on whether we should pre-approve devices tested using SAE J1321 

and also seek comment on an appropriate means of converting from the fuel consumption results 

of that test to the delta CDA values required for trailer compliance. 

Beginning on January 1, 2018, EPA would require that device manufacturers that wish to 

seek approval of new technologies for trailer certification use one of the approved test methods 

for Phase 2 (i.e., coastdown, constant speed, wind tunnel or CFD) and the test procedures found 

in 40 CFR 1037.525. Technologies that were pre-approved using SmartWay’s 2014 Protocols 

would maintain their approved status until CY 2021. After January 1, 2021, we are proposing 

that all pre-approved aerodynamic trailer technologies be tested using the Phase 2 test 

procedures. 
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(c) Off-Cycle Technologies

The Phase 1 and proposed Phase 2 programs for tractors include provisions for 

manufacturers to request the use of off cycle technologies that are not recognized in GEM or 

were not in common use before MY 2010. In the case of trailers, the agencies are not aware of

any technologies that could improve CO2 and fuel consumption performance that would not be 

captured in the test protocols as proposed. We are therefore not proposing a process to evaluate 

off-cycle trailer technologies. 

(d) Small Business Regulatory Flexibility Provisions

As a part of our small business obligations under the Regulatory Flexibility Act, EPA and 

NHTSA have considered additional flexibility provisions aimed at this segment of the trailer 

manufacturing industry. EPA convened a Small Business Advocacy Review (SBAR) Panel as 

required by the Small Business Regulatory Enforcement Fairness Act (SBREFA), and much of 

the information gained and recommendations provided by this process form the basis of the 

flexibilities proposed.257 As in previous rulemakings, our justification for including provisions 

specific to small businesses is that these entities generally have a greater degree of difficulty in 

complying with the standards compared to other entities. Thus, as discussed below, we are 

proposing several regulatory flexibility provisions for small trailer manufacturers that we believe 

would reduce the burden on them while achieving the goals of the program.

We believe that the small business regulatory flexibilities discussed below and in Section 

XV.C could provide these entities with reduced compliance requirements and/or additional time 

to accumulate capital internally or to secure capital financing from lenders, and to acquire 

additional engineering and testing resources. 

The agencies designed many of the proposed program elements and flexibility provisions 

available to all trailer manufacturers with the large fraction of small business trailer 

manufacturers in mind. We believe the option to choose pre-approved aerodynamic devices 

would significantly reduce the compliance burden and eliminate the requirement for all 

manufacturers to perform testing. 

As noted above, the small trailer manufacturers raised concerns that their businesses 

could be harmed by provisions allowing averaging, banking, and trading of emissions and fuel 

consumption performance, since they would not be able to generate the same volume of credits 

as large manufacturers. The agencies are proposing not to include banking and trading 

provisions in any part of the program, and are limiting the option to average to manufacturers of 

dry and refrigerated box trailers. Since a majority of non-box trailer manufacturers are small 

businesses, we believe a requirement of specific tire technologies for all non-box trailers would 

 

257 Additional information regarding the findings and recommendations of the Panel are available in Section XIV, 

Chapter 11 of the draft RIA, and in the Panel’s final report titled “Final Report of the Small Business Advocacy 

Review Panel on EPA’s Planned Proposed Rule Greenhouse Gas Emissions and Fuel Efficiency Standards for 

Medium- and Heavy-Duty Engines and Vehicles: Phase 2” (See Docket EPA-HQ-OAR-2014-0827). 
Page 312 of 850

create the most uniformity in requirements among manufacturers and would reduce the 

compliance burden by eliminating the use of the compliance equation. 

In addition to the provisions offered to trailer manufacturers of all sizes, the agencies are 

proposing or requesting comment on several additional provisions designed specifically to ease 

compliance burdens on small trailer manufacturers. For all small business trailer manufacturers, 

the agencies propose a one-year delay in the beginning of implementation of the program, until 

MY 2019. We believe (subject to consideration of public comment) that this would allow small 

businesses additional needed lead-time to make the proper staffing adjustments and process 

changes, and possibly add new infrastructure to meet the requirements. We also request 

comment about where there may be circumstances in later stages of the program, when the 

stringency of the standards increase in MY 2021 and 2024, when a similar 1-year delay in 

implementation could be warranted for small trailer manufacturers.

As mentioned previously, we are proposing to offer averaging provisions for 

manufacturers of dry and refrigerated box trailers only. We recognize that the small box trailer 

manufacturers may not be able to fully take advantage of averaging and may be at a competitive 

disadvantage with larger manufacturers with larger sales volumes and more diverse product 

lines. We request comment on additional provisions that could ease the potential harm to and/or 

incentivize small business participation in an averaging program. 

For small business manufacturers of box trailers, the agencies propose that if the 

proposed provisions allowing EPA pre-approval of aerodynamic devices (which is proposed as 

an interim program) were to end, small business trailer manufacturers could continue to use preapproved devices and avoid independent testing. Furthermore, we are proposing to end the 

interim design-based certification option after MY 2023. We request comment on whether this 

option should be extended beyond MY 2023 for small manufacturers. 

The agencies also request comment on provisions for small manufacturers that might face 

a situation where the technologies needed for compliance are unavailable. This could be a 

particular concern for small business non-box and non-aero box trailers that require the use of 

LRR tires and ATI systems. We request that trailer manufacturers as well as tire and 

aerodynamic technology manufacturers provide information regarding the current projected 

availability of the technologies that trailer manufacturers can use to meet our proposed standards.
Page 313 of 850

V. Class 2b-8 Vocational Vehicles

A. Summary of Phase 1 Vocational Vehicle Standards

Class 2b-8 vocational vehicles include a wide variety of vehicle types, and serve a wide

range of functions. Some examples include service for urban delivery, refuse hauling, utility

service, dump, concrete mixing, transit service, shuttle service, school bus, emergency, motor 

homes, and tow trucks. In the HD Phase 1 Program, the agencies defined Class 2b-8 vocational 

vehicles as all heavy-duty vehicles that are not included in the Heavy-duty Pickup Truck and 

Van or the Class 7 and 8 Tractor categories. In effect, the rules classify heavy-duty vehicles that 

are not a combination tractor or a pickup truck or van as vocational vehicles. Class 2b-8 

vocational vehicles and their engines emit approximately 20 percent of the GHG emissions and 

burn approximately 21 percent of the fuel consumed by today’s heavy-duty truck sector.258

Most vocational vehicles are produced in a two-stage build process, though some are 

built from the “ground up” by a single entity. In the two-stage process, the first stage sometimes 

is completed by a chassis manufacturer that also builds its own proprietary components such as 

engines or transmissions. This is known as a vertically integrated manufacturer. The first stage 

can also be completed by a chassis manufacturer who procures all components, including the 

engine and transmission, from separate suppliers. The product completed at the first stage is

generally either a stripped chassis, a cowled chassis, or a cab chassis. A stripped chassis may

include a steering column, a cowled chassis may include a hood and dashboard, and a cab chassis 

may include an enclosed driver compartment. Many of the same companies that build Class 7 

and 8 tractors also sell vocational chassis in the medium heavy- and heavy heavy-duty weight 

classes. Similarly, some of the companies that build Class 2b and 3 pickups and vans also sell 

vocational chassis in the light heavy-duty weight classes. 

The second stage is typically completed by a final stage manufacturer or body builder, 

which installs the primary load carrying device or other work-related equipment, such as a dump 

bed, delivery box, or utility boom. There are over 200 final stage manufacturers in the U.S., 

most of which are small businesses. Even the large final stage manufacturers are specialized, 

producing a narrow range of vehicle body types. These businesses also tend to be small volume 

producers. In 2011, the top four producers of truck bodies sold a total of 64,000 units, which is 

about 31 percent of sales in that year.259 In that same year, 74 percent of final stage 

manufacturers produced less than 500 units.

The businesses that act both as the chassis manufacturer and the final stage manufacturer 

are those that build the vehicles from the “ground up.” These entities generally produce custom 

products that are sold in lower volumes than those produced in large commercial processes. 

 

258 See Memorandum to the Docket “Runspecs and Model Inputs for MOVES for HD GHG Phase 2 Emissions 

Modeling” Docket Number EPA-HQ-OAR-2014-0827. See also EPA’s MOVES webpage at 

http://www.epa.gov/otaq/models/moves/index.htm. 

259 Specialty Transportation.net, 2012. Truck Body Manufacturing in North America
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Examples of vehicles produced with this build process would include fire apparatus and transit 

buses. 

The diversity in the vocational vehicle segment can be primarily attributed to the variety 

of customer needs for specialized vehicle bodies and added equipment, 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 would lead to different in-use fuel consumption and GHG emissions. However, the 

baseline fuel consumption and emissions due to the components included in the common chassis 

(such as the engine, drivetrain, frame, and tires) would be the same between these two types of 

vehicles. 

Owners of vocational vehicles that are upfitted with high-priced bodies that are purposebuilt for particular applications tend to keep them longer, on average, than owners of vehicles 

such as pickups, vans, and tractors, which are traded in broad markets that include many 

potential secondary markets. The fact that vocational vehicles also generally accumulate far 

fewer annual miles than tractors further contributes to lengthy trade cycles among owners of 

these vehicles. To the extent vocational vehicle owners may be similar to owners of tractors in 

terms of business profiles, they would be more likely to resemble private fleets or owneroperators than for-hire fleets. A 2013 survey conducted by NACFE found that the trade cycle of 

private tractor fleets ranged from seven to 12 years.260 

The Phase 1 standards for this vocational vehicle category generally apply at the chassis 

manufacturer level. For the same reasons given in Phase 1, the agencies propose to apply the 

Phase 2 vocational vehicle standards at the chassis manufacturer level.261

The Phase 1 regulations prohibit the introduction into commerce of any heavy-duty

vehicle without a valid certificate or exemption. Title 40 CFR §1037.620 allows for a temporary

exemption for the chassis manufacturer if it produces the chassis for a secondary manufacturer 

that holds a certificate. Further discussion of temporary exemptions and possible obligations of 

secondary manufacturers can be found in Section V. E. 

In Phase 1, the agencies adopted two equivalent sets of standards for Class 2b-8 

vocational vehicles. For vehicle-level (chassis) emissions, EPA adopted CO2 standards 

expressed in grams per ton-mile. For fuel efficiency, NHTSA adopted fuel consumption 

standards expressed in gallons per 1,000 ton-miles. The Phase 1 engine-based standards vary

based on the expected weight class and usage of the vehicle into which the engine will be 

installed. We adopted Phase 1 vehicle-based standards that vary according to one key attribute, 

GVWR, based on the same groupings of vehicle weight classes used for the engine standards --

light heavy-duty (LHD, Class 2b-5), medium heavy-duty (MHD, Class 6-7), and heavy heavyduty (HHD, Class 8). 

 

260 See 2013 ICCT Barriers Report at Note 242, above.

261 See 76 FR 57120.
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In Phase 1, the agencies defined a special regulatory category called vocational tractor, 

which generally operate more like vocational vehicles than line haul tractors.262 As described 

above in Section III.C.4, under the Phase 1 rules, a vocational tractor is certified under standards 

for vocational vehicles, not those for tractors. In Phase 2, the agencies propose to retain the 

vocational tractor definition, and to allow vocational tractors to certify over any of the proposed 

vocational vehicle duty cycles, following the same decision-tree as other vocational chassis. 

Vocational tractors would continue to satisfy the proposed engine standard and vocational 

vehicle GEM-based standard, rather than the proposed tractor standard.

Manufacturers are required to use GEM to determine compliance with the Phase 1 

vocational vehicle standards, where the primary vocational vehicle manufacturer-generated input 

is the measure of tire rolling resistance. The GEM assumes the use of a typical representative, 

compliant engine in the simulation, resulting in one overall value for CO2 emissions and one for 

fuel consumption. The manufacturers of engines intended for use in vocational vehicles are 

subject to separate Phase 1 engine-based standards. Manufacturers also may demonstrate 

compliance with the CO2 standards in whole or in part using credits reflecting CO2 reductions 

resulting from technologies not reflected in the GEM testing regime. See 40 CFR Section

1037.610.

In Phase 1, EPA and NHTSA also adopted provisions designed to give manufacturers a 

degree of flexibility in complying with the standards. Most significantly, we adopted an ABT 

program to allow manufacturers within the same averaging set to comply on average. See 40 

CFR Section 1037 subpart H. These provisions enabled the agencies to adopt overall standards 

that are more stringent than we could have considered with a less flexible program.263 

B. Proposed Phase 2 Standards for Vocational Vehicles

The agencies have held dozens of meetings with manufacturers, suppliers, nongovernmental organizations (NGOs), and other stakeholders to identify and understand the 

opportunities and challenges involved with regulating vocational vehicles. These meetings have 

helped us to better understand the performance demands of the customers, the fuel-saving and 

GHG reducing technologies that are being investigated, as well as some challenges that are being 

encountered. In addition, we updated our industry characterization to better understand the 

vocational vehicle manufacturing process, including the component suppliers and body

builders.264 We believe these information exchanges have enabled us to develop this proposal 

with an appropriate balance of reasonably achievable goals and a reasonably small risk of 

unintended consequences.

 

262 See EPA’s regulation at 40 CFR 1037.630 and NHTSA’s regulation at 49 CFR 523.2 a.

263 As noted earlier, 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 lightduty CAFE program. Cf. 49 U.S.C. 32902(h), which applies to light-duty CAFE but not to heavy-duty fuel 

efficiency under 49 U.S.C. 32902(k).

264 September 2013, Heavy Duty Vocational Vehicle Industry Characterization, EPA Contract No. EP-C-12-011. 
Page 316 of 850

(1) Proposed Subcategories and Test Cycles

The proposed Phase 2 vocational vehicle standards are based on the performance of a 

wider array of control technologies than the Phase 1 rules. In particular, the agencies are 

proposing to recognize detailed characteristics of powertrains and drivelines in the proposed 

Phase 2 vocational vehicle standards. As described below, driveline improvements present a 

significant opportunity for reducing fuel consumption and CO2 emissions from vocational 

vehicles. However, there is no single package of driveline technologies that would be equally 

suitable for the majority of vocational vehicles, because there is an extremely broad range of 

driveline configurations available in the market. This is due in part to the variety of build 

processes, ranging from a purpose built custom chassis to a commercial chassis that may be 

intended as a multi-purpose stock vehicle. Further, the wide range of applications and driving 

patterns of these vehicles leads manufacturers to offer a variety of drivelines, as each performs 

differently in use. For example, depending on whether the transmission has an overdrive gear, 

drive axle ratios for Class 7 and 8 tractors can be found in the range of 2.5:1 to 4.1:1. By

contrast, across all types of vocational vehicles, drive axle ratios can be as low as 3.1:1 (delivery

vehicle) and as high as 9.8:1 (transit bus).265 Other components of the driveline also have a 

broader range of product in vocational vehicles than in tractors, including transmission gears, tire 

sizes, and engine speeds. Each of these design features affects the GHG emission rate and fuel 

consumption of the vehicle. It therefore is reasonable to define more than one baseline 

configuration of vocational vehicle, to encompass a range of drivelines and recognize that the 

agencies cannot use a one-size-fits-all approach. A detailed list of the technologies the agencies 

project could be adopted to meet the proposed vocational vehicle standards is described in 

Section V.C, and in the draft RIA Chapter 2. The agencies have determined that these 

technologies perform differently depending on the drivelines and driving patterns, further 

supporting the need to subcategorize this segment.

For these reasons, the agencies are proposing to create additional subcategories of 

vocational vehicles in Phase 2. By creating additional subcategories we would essentially be 

setting separate baselines and separate numerical performance standards for different groups of 

vocational vehicle chassis over different test cycles. This would enable the technologies that 

perform best at highway speeds and those that perform best in urban driving to each to be fully 

recognized over appropriate test cycles, while avoiding the unintended consequence of forcing 

vocational vehicles that are designed to serve in a wide variety of applications to be measured 

against a single baseline. The attributes we believe could define these chassis groups are 

described below.

 

265 See Dana Spicer Drive Axle Application Guidelines, available at 

http://www.dana.com/wps/wcm/connect/133007004bd8422b9ea8be14e7b6dae0/DEXTdaag2012_0712_DriveAxlesAppGuide_LR.pdf?MOD=AJPERES&CONVERT_TO=url&CACHEID=133007004bd

8422b9ea8be14e7b6dae0. See also ZF Driveline and Chassis Technology brochure, available at 

http://www.zf.com/media/media/en/document/corporate_2/downloads_1/flyer_and_brochures/bus_driveline_techno

logy_flyer/Busbroschuere_12_DE_final.pdf
Page 317 of 850

The agencies are proposing to split groups of chassis into subcategories based generally

on vehicle use patterns in which the CO2 emissions and fuel consumption standards vary as a 

consequence. Compliance with these standards would be demonstrated through test cycles 

reflecting these use patterns, to best assure that actual in-use benefits occur. An ideal test cycle 

is one in which the performance improvements achieved by the adopted technologies are 

recognized over the cycle. As described in Section V.C and in the draft RIA Chapter 2.9, the 

agencies have found that most of the technologies considered do perform differently under 

different driving conditions. For example, the effectiveness of lower tire rolling resistance is 

different depending on the degree of highway or transient driving, but the differences are very

small compared to the difference in effectiveness for a hybrid drivetrain under different driving 

conditions. The agencies have found that the measurable changes in performance of a majority 

of the technologies are significant enough to merit creation of different subcategories with 

different test cycles. 

Idle reduction technology is one type of technology that is particularly duty-cycle 

dependent. The composite test cycle for vocational vehicles in Phase 1 includes a 42 percent 

weighting on the ARB Transient test cycle, which comprises nearly 17 percent of idle time. 

However, no single idle event in this test cycle is longer than 36 seconds, which may not be 

enough time to adequately recognize the benefits of some idle reduction technologies.266 For 

Phase 2, the agencies propose to recognize this important fuel saving technology by evaluating 

workday idle reduction technologies through a new idle-only cycle as described in the draft RIA 

Chapter 3. 

The agencies are proposing three different composite test cycles for vocational vehicles 

in Phase 2: Regional, Multi-Purpose, and Urban. The agencies believe these three cycles balance 

the competing pressures to recognize the varying performance of technologies, serve the varying 

needs of customers, and maintain reasonable regulatory simplicity. Table V-1 below presents 

the nine proposed subcategories of vocational vehicles: three weight class groupings, each with 

three composite duty cycles. Each of these proposed composite duty cycles has a different 

weighting of the new idle cycle, the highway cruise cycles, and the ARB Transient cycle, as 

shown in Table V-2. The CALSTART HD Truck Fuel Economy Task Group met in June 2013 

to discuss vocational vehicle segmentation, and suggested an approach very similar to this. The 

task group generally supported a limited number of duty cycles that would be sufficient to cover 

the basic applications while allowing new technology to demonstrate its worth. They recognized 

that a few meaningful duty cycles could “bound” how vocational vehicles are generally used, 

while recognizing that this approach would not perfectly match how every vocational vehicle is 

actually used. Their recommendations included three vocational vehicle duty-cycle-based 

subcategories: Urban, Regional, and Work Site. A detailed discussion of the CALSTART 

recommendations, as well as reasoning why the agencies selected the proposed composite cycle 

weightings can be found in the draft RIA Chapter 2. Continuing the averaging scheme from 

Phase 1, each manufacturer would be able to average within each vehicle weight class. 

 

266 However, as noted above, emission improvements due to workday idle technology can be recognized under 

Phase 1 as an innovative credit under 40 CFR 1037.610 and 49 CFR Part 535.7.
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Table V-1 Proposed Regulatory Subcategories for Vocational Vehicles

Weight Class Light Heavy-Duty 

Class 2b-5

Medium Heavy-Duty 

Class 6-7

Heavy Heavy-Duty

Class 8

Duty Cycle Regional Regional Regional

Multi-Purpose Multi-Purpose Multi-Purpose

Urban Urban Urban

Table V-2 Proposed Composite Test Cycle Weightings (in Percent) for Vocational Vehicles

ARB Transient 55 mph Cruise

with Road Gradea

65 mph Cruise

with Road Gradea

Idle

Regional 50 28 22 10

Multi-Purpose 82 15 3 15

Urban 94 6 0 20

Note:

a As described in Section III.E.2.b, the agencies are proposing to add road grade to the highway cruise test cycles.

The agencies are proposing criteria for determining the applicability of these 

subcategories. This is not as straightforward an exercise as with tractors, where attributes such 

as cab type are obvious physical properties that indicate reasonably well how a vehicle is 

intended to be used. The agencies have identified the final drive ratio of a vocational vehicle as 

a possible attribute that may indicate how the vehicle is intended to be used. As described in 

Section V. E. (1) (d), we expect that most vocational chassis could be assigned to a duty cycle by 

estimating the percent of maximum engine test speed that is achieved over highway cruise 

cycles, by use of an equation that relates engine speed to vehicle speed. To simplify this 

assignment process, the agencies propose that a vocational chassis would be presumed to certify

using the Multi-Purpose duty cycle unless some criteria were met that indicated either the 

Regional or Urban cycle would be more appropriate. Those criteria could include the objective 

calculation described in Section V.E., or a mix of physical attributes and knowledge of intended 

use. The agencies are also proposing that chassis manufacturers would be able to request a 

different duty cycle. 

We understand that even within certain vocational vehicle types, vehicle use varies 

significantly. By employing the agencies’ recommended assignment process, it is our 

expectation that a delivery truck and a dump truck could both be certified over the same duty 

cycle while still yielding accurate technology effectiveness, if they had similar chassis and 

driveline characteristics. Further, while intended service class may help a manufacturer decide 

how to classify some vehicles, we do not believe that intended service class would be a sufficient 

indicator by itself. An example of this is the refuse service class. A neighborhood collection 

refuse truck would not need to be assigned to the same subcategory as a roll-off refuse 

straight/dump truck that makes daily highway trips to a landfill.

The agencies request comment on the method for assigning vocational chassis to 

regulatory subcategories. We believe the proposed approach is aligned with the objective to 
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allow manufacturers to certify their chassis over appropriate duty cycles, while maintaining the 

ability of the market to offer a variety of products to meet customer demand. 

(2) Alternative Approach to Subcategorization

The U.S. Department of Energy and EPA are partnering to support a project aimed at 

evaluating, refining and/or developing duty cycles for tractors and vocational vehicles to be used 

in the certification of heavy-duty vehicles to GHG emission standards. This project is underway 

at the National Renewable Energy Laboratory (NREL) and includes a task to develop alternative

subcategorization options for vocational vehicles, along with new drive cycles and/or cycle 

composite weightings. NREL is continuing to collate available vehicle activity data and vehicle 

characteristics, and the public is invited to submit information to the docket in support of this 

work to identify possible alternative GEM test cycles and segmentation options for vocational 

vehicles. Preliminary work under this project indicates that two or three test cycles may

adequately represent most vocational vehicles. Depending on how many distinct vehicle driving 

patterns can be identified with correlation to vehicle attributes, the agencies may finalize a 

vocational subcategorization approach that includes as few as two or as many as five composite 

GEM duty cycles. It is also possible that some test cycles may not apply to all subcategories. It

is further possible that the approach to assignment of vocational chassis to subcategories in the 

final rules may be based on different attributes than those proposed, including different engine 

and driveline characteristics and different indicators of vehicle purpose. Preliminary work from 

NREL indicates that in-use drive cycles may include more idle operation for all types of 

vocational vehicles than is represented by the currently proposed GEM test cycles. Depending 

on comments and additional information received during the comment period, it may be within 

the agencies’ discretion to adopt one or more alternative vocational vehicle test cycles, or reweight the current test cycles, to better represent real world driving and better reflect 

performance of the technology packages. 

(3) Proposed GHG and Fuel Consumption Standards for Vocational Vehicles

EPA is proposing CO2 standards and NHTSA is proposing fuel consumption standards 

for manufacturers of chassis for new vocational vehicles. As described in Sections II.C.1 and 

II.D.1 above, the agencies are proposing test procedures so that engine performance would be 

evaluated within the GEM simulation tool. These test procedures include corrections for the test 

fuel, enabling vocational vehicles to be certified with many different types of CI and SI engines.

In addition, EPA is proposing to establish HFC leakage standards for air conditioning systems in 

vocational vehicles, as described below and in the draft RIA Chapters 2 and 5.

This section describes the standards and implementation dates that the agencies are 

proposing for the nine subcategories of vocational vehicles. The agencies have performed a 

technology analysis to determine the level of standards that we believe would be available at 

reasonable cost, and would be cost-effective, technologically feasible, and appropriate in the lead 

time provided. More details of this analysis are described in the draft RIA Chapter 2. This 

analysis considered the following for each of the proposed regulatory subcategories:

the level of technology that is incorporated in current new vehicles, 

forecasts of manufacturers’ product redesign schedules,
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the available data on 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 2027 model year, 

the effectiveness and cost of these technologies, 

a projection of the technologically feasible application rates of these technologies, in this 

time frame, and

projections of future U.S. sales for different types of vehicles and engines. 

The proposal described here and throughout the rulemaking documents is the preferred 

alternative, referred to as Alternative 3 in Section X and the draft RIA Chapter 11. However, the 

agencies are seriously considering another alternative for all segments, including vocational 

vehicles, referred to as Alternative 4. The agencies believe that Alternative 4 has the potential to 

be the maximum feasible and reasonable alternative. However, based on the evidence currently 

before the agencies, EPA and NHTSA have outstanding questions regarding relative risks and 

benefits of Alternative 4 due to the time frame envisioned by that alternative. Alternative 4 is 

predicated on the same general market adoption rates of the same technologies as the proposal, 

but would provide three years less lead time than the proposal. Details of Alternative 4 are 

presented in Section V.D, Section X, and in the draft RIA Chapter 11. 

The agencies seek comment on the feasibility of Alternative 4 for vocational vehicles,

including empirical data on its appropriateness, cost-effectiveness, and technological feasibility. 

It would be helpful if comments addressed these issues separately for each type of technology. 

Additional information and feedback could further inform our assumptions and, by 

extension, our analysis of feasibility. The agencies believe it is possible that it could be within 

the agencies’ discretion to determine in the final rules that Alternative 4 could be maximum 

feasible and appropriate under CAA section 202 (a)(1) and (2). If the agencies receive relevant 

information supporting the feasibility of Alternative 4, or regarding technology pathways 

different than those in Alternatives 3 and 4, the agencies may consider establishing final fuel 

consumption and GHG emission standards at levels that provide more overall reductions than 

what we are proposing if we deem them to be maximum feasible and reasonable for NHTSA and 

EPA, respectively.

(a) Proposed Fuel Consumption and CO2 Standards

The agencies are proposing standards that would phase in over a period of seven years, 

beginning in the 2021 model year, consistent with the requirement in EISA that NHTSA’s 

standards provide four full model years of regulatory lead time and three full model years of 

regulatory stability, and provide sufficient time “to permit the development and application of 

the requisite technology” for purposes of CAA section 202 (a)(2). The proposed Phase 2 

program would progress in three-year stages with an intermediate set of standards in MY 2024 

and would continue to reduce fuel consumption and CO2 emissions well beyond the full 

implementation year of MY 2027. The agencies have identified a technology path for each of 

these levels of improvement, as described below.
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Combining engine and vehicle technologies, vocational vehicles powered by CI engines 

would be projected to achieve improvements of 16 percent in MY 2027 over the MY 2017 

baseline, as described below and in the draft RIA Chapter 2. The agencies project up to 13 

percent improvement in fuel consumption and CO2 emissions in MY 2027 from SI-powered 

vocational vehicles, as shown in Table V-3. The incremental Phase 2 vocational vehicle 

standards would ensure steady progress toward the MY2027 standards, with improvements in 

MY 2021 of up to seven percent and improvements in MY 2024 of up to 11 percent over the MY 

2017 baseline vehicles, as shown in Table V-3. 

The agencies’ analyses, as discussed in this preamble and in the draft RIA Chapter 2, 

show that the proposed standards would be appropriate under each agency’s respective statutory

authority. 

Table V-3 Projected Vocational Vehicle CO2 and Fuel Use Reductions (in Percent) from 2017 Baseline

Model Year Engine Type Heavy HeavyDuty Class 8Medium HeavyDuty Class 6-7Light Heavy-Duty 

Class 2b-5

2021 CI Engine 7 7 6

SI Engine 5 5 4

2024 CI Engine 11 11 10

SI Engine 7 7 7

2027 CI Engine 16 16 16

SI Engine 12 13 12

Based on our analysis and research, the agencies believe that the improvements in 

vocational vehicle fuel consumption and CO2 emissions can be achieved through deployment 

and utilization of a greater set of technologies than formed the technology basis for the Phase 1 

standards. In developing the proposed standards, the agencies have evaluated the current levels 

of fuel consumption and emissions, the kinds of technologies that could be utilized by

manufacturers to reduce fuel consumption and emissions, the associated lead time, the associated 

costs for the industry, fuel savings for the owner/operator, and the magnitude of the CO2

reductions and fuel savings that may be achieved. After examining the possibilities of vehicle 

improvements, the agencies are basing the proposed standards on the performance of workday

idle reduction technologies, improved transmissions including hybrid powertrains, axle 

technologies, weight reduction, and further tire rolling resistance improvements. The EPA-only

air conditioning standard is based on leakage improvements.

The agencies’ evaluation indicates that some of the above vehicle technologies are 

commercially available today, though often in limited volumes. Other technologies would need 

additional time for development. Those that we believe are available today and may be adopted 

to a limited extent in some vehicles include improved tire rolling resistance, weight reduction, 

some types of conventional transmission improvements, neutral idle, and air conditioning 
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leakage improvements. However, EPA is not proposing standards predicated on performance of 

these technologies until MY 2021.267 The agencies consider any potential benefits that could be 

achieved by implementing rules requiring some technologies on vocational vehicles earlier than 

MY 2021 to be outweighed by several disadvantages. For one, manufacturers would need lead 

time to develop compliance tracking tools. Also, if the Phase 2 vocational vehicle standards 

began in a different year than the tractor standards, this could create unnecessary added 

complexity, and could strongly detract from the fuel savings and GHG emission reductions that 

could otherwise be achieved. Therefore we anticipate that the Phase 1 standards will continue to 

apply in model years 2018 to 2020.

Vehicle technologies that we believe will become available in the near term include 

improved axle lubrication and 6x2 axles. Vehicle technologies that we understand would benefit 

from even more development time include stop-start idle reduction and hybrid powertrains. The 

agencies have analyzed the technological feasibility of achieving the fuel consumption and CO2

standards, based on projections of what actions manufacturers would be expected to take to 

reduce fuel consumption and emissions to achieve the standards, and believe that the standards 

would be technologically feasible throughout the regulatory useful life of the program. EPA and 

NHTSA estimated vehicle package costs are found in Section V. C. (2) .

Table V-4 and Table V-5 present EPA’s proposed CO2 standards and NHTSA’s proposed 

fuel consumption standards, respectively, for chassis manufacturers of Class 2b through Class 8 

vocational vehicles for the beginning model year of the program, MY 2021. As in Phase 1, the 

standards would be in the form of the mass of emissions, or gallons of fuel, associated with

carrying a ton of cargo over a fixed distance. The EPA standards would be measured in units of 

grams CO2 per ton-mile and the NHTSA standards would be in gallons of fuel per 1,000 tonmiles. With the mass of freight in the denominator of this term, the program is designed to 

measure improved efficiency in terms of freight efficiency. As in Phase 1, the Phase 2 program 

would assign a fixed default payload in GEM for each vehicle weight class group (heavy heavyduty, medium heavy-duty, and light heavy-duty). Even though this simplification does not allow 

individual vehicle freight efficiencies to be recognized, the general capacity for larger vehicles to 

carry more payload is represented in the numerical values of the proposed standards for each 

weight class group.

EPA’s proposed vocational vehicle CO2 standards and NHTSA’s proposed fuel 

consumption standards for the MY 2024 stage of the program are presented in Table V-6 and 

Table V-7, respectively. These reflect broader adoption rates of vehicle technologies already

considered in the technology basis for the MY 2021 standards. The standards for vehicles 

powered by CI engines also reflect that in MY 2024, the separate engine standard would be more 

stringent, so the vehicle standard keeps pace with the engine standard. 

 

267 NHTSA is unable to adopt mandatory amended standards in those model years since there would be less than the 

statutorily-prescribed amount of lead time available. 49 USC section 32902 (k)(3)(A).
Page 323 of 850

EPA’s proposed vocational vehicle CO2 standards and NHTSA’s proposed fuel 

consumption standards for the full implementation year of MY 2027 are presented in Table V-8

and Table V-9, respectively. These reflect even greater adoption rates of the same vehicle 

technologies considered in the basis for the previous stages of the Phase 2 standards. The 

proposed MY 2027 standards for vocational vehicles powered by CI engines reflect additional 

engine technologies consistent with those on which the separate proposed MY 2027 CI engine 

standard is based. The proposed MY 2027 standards for vocational vehicles powered by SI

engines reflect improvements due to additional engine friction reduction technology, which is 

not among the technologies on which the separate SI engine standard is based.

The proposed standards are based on highway cruise cycles that include road grade, to 

better reflect real world driving and to help recognize engine and driveline technologies. See 

Section III.E. The agencies have evaluated some alternate road grade profiles, including several

recommended by NREL and two developed independently by the agencies, and have prepared 

possible alternative vocational vehicle standards based on these profiles. The agencies request 

comment on this analysis, which is available in a memorandum to the docket.268

As described in Section I, the agencies are proposing to continue the Phase 1 approach to

averaging, banking and trading (ABT), allowing ABT within vehicle weight classes. For Phase 

2, continuing this approach means allowing averaging between CI-powered vehicles and SIpowered vehicles that belong to the same weight class group and have the same regulatory useful 

life.

Table V-4 Proposed EPA CO2 Standards for MY2021 Class 2b-8 Vocational Vehicles 

EPA Standard for Vehicle with CI Engine Effective MY2021 (gram CO2/ton-mile)

Duty Cycle Light Heavy-Duty 

Class 2b-5

Medium Heavy-Duty 

Class 6-7

Heavy Heavy-Duty

Class 8

Urban 296 188 198

Multi-Purpose 305 190 200

Regional 318 186 189

EPA Standard for Vehicle with SI Engine Effective MY2021 (gram CO2/ton-mile)

Duty Cycle Light Heavy-Duty 

Class 2b-5

Medium Heavy-Duty 

Class 6-7

Heavy Heavy-Duty

Class 8

Urban 320 203 214

Multi-Purpose 329 205 216

Regional 343 201 204

 

268 See Memorandum dated May 2015 on Possible Tractor, Trailer, and Vocational Vehicle Standards Derived from 

Alternative Road Grade Profiles
Page 324 of 850

Table V-5 Proposed NHTSA Fuel Consumption Standards for MY2021 Class 2b-8 Vocational Vehicles 

NHTSA Standard for Vehicle with CI Engine Effective MY 2021 (Fuel Consumption 

gallon per 1,000 ton-mile)

Duty Cycle Light Heavy-Duty 

Class 2b-5

Medium Heavy-Duty 

Class 6-7

Heavy Heavy-Duty

Class 8

Urban 29.0766 18.4676 19.4499

Multi-Purpose 29.9607 18.6640 19.6464

Regional 31.2377 18.2711 18.5658

NHTSA Standard for Vehicle with SI Engine Effective MY 2021 (Fuel Consumption 

gallon per 1,000 ton-mile) 

Duty Cycle Light Heavy-Duty 

Class 2b-5

Medium Heavy-Duty 

Class 6-7

Heavy Heavy-Duty

Class 8

Urban 36.0077 22.8424 24.0801

Multi-Purpose 37.0204 23.0674 24.3052

Regional 38.5957 22.6173 22.9549

Table V-6 Proposed EPA CO2 Standards for MY2024 Class 2b-8 Vocational Vehicles

EPA Standard for Vehicle with CI Engine Effective MY2024 (gram CO2/ton-mile)

Duty Cycle Light Heavy-Duty 

Class 2b-5

Medium Heavy-Duty 

Class 6-7

Heavy Heavy-Duty

Class 8

Urban 284 179 190

Multi-Purpose 292 181 192

Regional 304 178 182

EPA Standard for Vehicle with SI Engine Effective MY2024 (gram CO2/ton-mile)

Duty Cycle Light Heavy-Duty 

Class 2b-5

Medium Heavy-Duty 

Class 6-7

Heavy Heavy-Duty

Class 8

Urban 312 197 208

Multi-Purpose 321 199 210

Regional 334 196 199
Page 325 of 850

Table V-7 Proposed NHTSA Fuel Consumption Standards for MY2024 Class 2b-8 Vocational Vehicles

NHTSA Standard for Vehicle with CI Engine Effective MY 2024 (Fuel Consumption 

gallon per 1,000 ton-mile)

Duty Cycle Light Heavy-Duty 

Class 2b-5

Medium Heavy-Duty 

Class 6-7

Heavy Heavy-Duty

Class 8

Urban 27.8978 17.5835 18.6640

Multi-Purpose 28.6837 17.7800 18.8605

Regional 29.8625 17.4853 17.8782

NHTSA Standard for Vehicle with SI Engine Effective MY 2024 (Fuel Consumption 

gallon per 1,000 ton-mile)

Duty Cycle Light Heavy-Duty 

Class 2b-5

Medium Heavy-Duty 

Class 6-7

Heavy Heavy-Duty

Class 8

Urban 35.1075 22.1672 23.4050

Multi-Purpose 36.1202 22.3923 23.6300

Regional 37.5830 22.0547 22.3923

Table V-8 Proposed EPA CO2 Standards for MY2027 Class 2b-8 Vocational Vehicles

EPA Standard for Vehicle with CI Engine Effective MY2027 (gram CO2/ton-mile)

Duty Cycle Light Heavy-Duty 

Class 2b-5

Medium Heavy-Duty 

Class 6-7

Heavy Heavy-Duty

Class 8

Urban 272 172 182

Multi-Purpose 280 174 183

Regional 292 170 174

EPA Standard for Vehicle with SI Engine Effective MY2027 (gram CO2/ton-mile)

Duty Cycle Light Heavy-Duty 

Class 2b-5

Medium Heavy-Duty 

Class 6-7

Heavy Heavy-Duty

Class 8

Urban 299 189 196

Multi-Purpose 308 191 198

Regional 321 187 188
Page 326 of 850

Table V-9 Proposed NHTSA Fuel Consumption Standards for MY2027 Class 2b-8 Vocational Vehicles

NHTSA Standard for Vehicle with CI Engine Effective MY 2027 (Fuel Consumption 

gallon per 1,000 ton-mile)

Duty Cycle Light Heavy-Duty 

Class 2b-5

Medium Heavy-Duty 

Class 6-7

Heavy Heavy-Duty

Class 8

Urban 26.7191 16.8959 17.8782

Multi-Purpose 27.5049 17.0923 17.9764

Regional 28.6837 16.6994 17.0923

NHTSA Standard for Vehicle with SI Engine Effective MY 2027 (Fuel Consumption 

gallon per 1,000 ton-mile)

Duty Cycle Light Heavy-Duty 

Class 2b-5

Medium Heavy-Duty 

Class 6-7

Heavy Heavy-Duty

Class 8

Urban 33.6446 21.2670 22.0547

Multi-Purpose 34.6574 21.4921 22.2797

Regional 36.1202 21.0420 21.1545

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

proposing standards that apply to Class 2b-8 vocational vehicles at the time of production, and 

EPA is proposing standards for a specified period of time in use (e.g., throughout the regulatory

useful life of the vehicle). The derivation of the standards for these vehicles, as well as details 

about the proposed provisions for certification and implementation of these standards, are 

discussed in more detail later in this notice and in the draft RIA.

(b) Proposed HFC Leakage Standards

The Phase 1 GHG standards do not include standards to control direct HFC emissions 

from air conditioning systems on vocational vehicles. EPA deferred such standards 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”. 76 FR 

57194/3. During our stakeholder outreach conducted for Phase 2, we learned that the majority of 

vocational vehicles are sold as cab-completes with the dashboard-mounted air conditioning 

systems installed by the chassis manufacturer. For those vehicles that have A/C systems 

installed by a second stage manufacturer, EPA is proposing revisions to our regulations that 

would resolve the issues identified in Phase 1, in what we believe is a practical and feasible 

manner, as described below in Section V.E. 

For the above reasons, in Phase 2, EPA now believes that it is reasonable to propose A/C 

refrigerant leakage standards for Class 2b-8 vocational vehicles, beginning with the 2021 model 

year. Chassis sold as cab-completes typically have air conditioning systems installed by the 

chassis manufacturer. For these configurations, the process for certifying that low leakage 

components are used would follow the system in place currently for comparable systems in 

tractors. In the case where a chassis manufacturer would rely on a second stage manufacturer to 

install a compliant air conditioning system, the chassis manufacturer must follow the proposed 

delegated assembly provisions described below in Section V.E.
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(4) Proposed Exemptions and Exclusions

(a) Proposed Standards for Emergency Vehicles 

Emergency vehicles are covered by the Phase 1 program at the same level of stringency

as any other vocational vehicle. In discussions with representatives of the Fire Apparatus 

Manufacturers Association, the agencies have learned that chassis manufacturers of fire 

apparatus are currently able to obtain compliant engines and tires with the coefficient of rolling 

resistance allowing compliance with the Phase 1 standards. The agencies are proposing in Phase 

2 to allow emergency vehicles to meet less stringent standards than other vocational vehicles. 

There are two reasons for doing so. First, as the level of complexity of Phase 2 would increase 

with the need for additional technologies aimed to improve driveline efficiency, the compliance 

burden would be disproportionately high for a company that manufactures small volumes of 

specialized chassis. The ability of such a company to benefit from averaging would be limited, 

as would be the ability to spread compliance costs across many vehicles. The second and more 

important reason is that emergency vehicles, which are necessarily built for high levels of 

performance and reliability, would likely sacrifice some levels of function to attain the proposed 

Phase 2 standards. For example, vehicles with large engines, high-torque powertrains, and tires 

designed with deep tread would likely be deficit-producing vehicles if manufacturers needed to 

certify an emergency vehicle family to the primary proposed standards.

In the MY 2017-2025 light-duty rule, the agencies adopted an exclusion for emergency

and police vehicles from GHG and fuel economy standards.269 As described in that rule, the 

unique features of purpose-built emergency vehicles, such as high rolling resistance tires, 

reinforced suspensions, and special calibrations of engines and transmissions, have the effect of 

raising their GHG emissions. The agencies determined in that rule that an exemption was 

appropriate because the technological feasibility issues for emergency vehicles went beyond 

those of other high-performance vehicles, and vehicles with these performance characteristics 

must continue to be made available in the market. The agencies do not believe that nonemergency vocational vehicles are designed for the severe duty cycles that are experienced by

emergency vehicles, and therefore do not face the same potential constraints in terms of vehicle 

design and the application of technology.

In conducting an independent technological feasibility assessment for heavy-duty 

emergency vehicles, the agencies believe that some GHG and fuel saving technologies could 

reasonably be applied without compromising vehicle utility. However, these vehicles are 

designed, built, and operated so differently than other vocational vehicles that we believe 

keeping them in the same averaging sets as other vocational vehicles in Phase 2 would not be 

appropriate and thus a separate standard (evaluated from a baseline specific to these vehicles) is 

warranted. 

 

269 See 77 FR 62653, October 12, 2012.
Page 328 of 850

Our feasibility analysis and the available tire data indicate that emergency vehicle 

manufacturers can reasonably continue to apply tires with the Phase 1 level tire CRR 

performance, in the Phase 2 program. We have also learned that a variety of vehicle-level 

technologies are being developed specifically for emergency vehicles, to maintain on-board 

electronics without excessive idling. Modern fire apparatus and ambulances typically have 

multiple computers and other electronic devices on-board, each of which requires power and 

continues to draw electricity when the vehicle is parked and the crew is responding to an 

emergency, which could take several hours. Most on-board batteries and alternators are not 

capable of sustaining these power demands for any length of time, so emergency vehicles must 

either operate in a high-idle mode or adopt one of several possible technologies that can assist 

with electrical load management. Some of these technologies can enable an emergency vehicle 

to shut down the main engine and drastically reduce idle emissions.270 NHTSA and EPA have 

not based the proposed emergency vehicle standards on use of idle reduction technologies 

because we do not believe the regular neutral idle and stop-start technologies we project for other 

vocational vehicles could apply equally to emergency vehicles, and we do not have enough 

information about this subset of idle reduction technologies that is designed for extended 

electrical load management to either estimate an effectiveness value or determine an appropriate 

market adoption rate. The agencies request comment on whether we should include any market 

adoption rate of idle reduction technologies for emergency vehicles, as part of the basis for the 

Phase 2 emergency vocational vehicle standard.

To address both the technical feasibility and the compliance burden, the agencies are 

proposing less stringent standards that also have a simplified compliance method. Because the 

potential trade-offs between performance and fuel efficiency apply equally to any emergency

vehicle manufacturer, the agencies propose that these less stringent standards would apply for 

commercial chassis manufacturers of emergency vehicles, as well as for custom chassis 

manufacturers. The standard for vehicles identified at the time of certification as being intended 

for emergency service would be predicated solely on the continued use of lower rolling 

resistance tires, at the Phase 2 baseline level (i.e. compliant with Phase 1).271 

With respect to standards for engines used in these emergency vehicles, based on what 

we have learned from discussions with engine manufacturers, we understand that engines 

designed for heavy-duty emergency vehicles are generally higher-emitting than other engines. 

However, if we maintain a separate engine standard and regulatory flexibility such as ABT, fire 

apparatus manufacturers would be able to obtain engines that, on average, meet the proposed 

Phase 2 engine standards. The agencies further recognize that the proposed engine map inputs to 

GEM in the primary program would pose a difficulty for emergency vehicle manufacturers. If 

we required engine-specific inputs then these manufacturers would have to apply extra vehicle 

technologies to compensate for the necessary but higher-emitting engine. The agencies are 

 

270 See “How to solar power a fire truck or ambulance,” available at http://www.firerescue1.com/fireproducts/apparatus-accessories/articles/1934440-How-to-solar-power-a-fire-truck-or-ambulance/, accessed 

November 2014

271 See 40 CFR 86.1803-01 for the applicable definition of emergency vehicle.
Page 329 of 850

therefore not proposing to recognize engine performance as part of the vehicle standard for 

emergency vehicles. Manufacturers of these vehicles would be expected to install an engine that 

is certified to the applicable separate Phase 2 engine standard. However, under the simplified 

compliance method we are proposing, emergency vehicle manufacturers would not follow the 

otherwise applicable Phase 2 proposed approach of entering an engine map in GEM. Instead a 

Phase 1 style GEM interface would be made available, where an EPA default engine specified by

rule would be simulated in GEM. The agencies request comments on the merits of using an 

equation-based compliance approach for emergency vehicle manufacturers, similar to the 

approach proposed for trailer manufacturers and described in Section IV.F. 

This approach is consistent with the approach recommended by the Small Business 

Advocacy Review Panel, which believed it would be feasible for small emergency vehicle 

manufacturers to install a Phase 2-compliant engine, but recommended a simplified certification 

approach to reduce the number of required GEM inputs. Consistent with the recommendations 

of this panel, the agencies are asking for comments on whether there would be enough fuel 

consumption and CO2 emissions benefits achieved by use of LRR tires in emergency vehicles to 

justify requiring small business emergency chassis manufacturers to adopt them. 

We expect some commercial chassis manufacturers that serve the emergency vehicle 

market may have the ability to meet the proposed Phase 2 standards of our primary program 

when including emergency vehicles in their averaging sets. Even so, we are proposing that they

have the option to comply with the less stringent standards, because there are fewer opportunities 

to improve fuel efficiency on emergency vehicles, which (as noted) are designed for high levels 

of performance and severe duty. The agencies expect that this compliance path would be most 

needed by custom chassis manufacturers who serve the emergency vehicle market. Custom 

chassis manufacturers typically offer a narrow range of products with low sales volumes. 

Therefore, fleet averaging would provide a lower level of compliance flexibility, and there would 

be less opportunity to spread the costs of developing advanced technologies across a large 

number of vehicles. Further, many custom chassis manufacturers do not qualify as small entities 

under the SBA regulations. Thus, the agencies believe that existence of program-wide ABT does 

not vitiate the need to propose alternative, less stringent standards for emergency vehicles. 

Table V-10 below presents the proposed numerical standards to which an emergency

vehicle chassis would be certified under this provision. Emergency vehicles certified to these 

proposed emergency vehicle standards would be ineligible to generate credits. The proposed 

standards shown below were derived by building a model of three baseline vehicles (LHD, 

MHD, HHD) using attributes similar to those developed for the primary program as assigned to 

the Urban drive cycle subcategories. By modeling a 2021-compliant engine and tires with CRR 

of 7.7, the MY 2021 standards were derived using GEM. Details of these configurations are 

provided in the draft RIA Chapter 2.
Page 330 of 850

Table V-10 Proposed Standards for Class 2b-8 Emergency Vehicles for MY 2021 and Later 

Proposed EPA Emergency Vehicle Standard (gram CO2/ton-mile)

Implementation 

Year

Light Heavy-Duty 

Class 2b-5

Medium Heavy-Duty 

Class 6-7

Heavy Heavy-Duty

Class 8

MY2021 312 195 215

Proposed NHTSA Emergency Vehicle Standard (Fuel Consumption gallon per 1,000 tonmile)

Implementation 

Year

Light Heavy-Duty 

Class 2b-5

Medium Heavy-Duty 

Class 6-7

Heavy Heavy-Duty

Class 8

MY2021 30.6483 19.1552 21.1198

The agencies have estimated the costs of vocational vehicle technology packages, as 

presented below in Table V-20 to Table V-22. The technologies on which the proposed 

emergency vehicle standards are based include engines, LRR tires, and leak-tight air 

conditioning systems. Using the estimated costs of those technologies as presented, the agencies 

estimate that the average cost for a heavy heavy-duty or medium-heavy-duty emergency vehicle 

to meet the proposed emergency vehicle standards would be approximately $463 in MY 2027, 

and the average cost for a light heavy-duty emergency vehicle would be approximately $497 in 

MY 2027. To derive these estimates, the agencies have combined the $7 cost of LRR tires that is 

presented in Table V-20 with the engine and air conditioning costs presented in Table V-22. The 

agencies are not aware of any emergency vehicle manufacturer that produces engines, thus most 

of these costs would be borne by engine manufacturers. While some of the added engine costs 

may be passed on to emergency vehicle manufacturers and vehicle owners/operators, the overall 

costs of these technologies are on the order of the Phase 1 vocational vehicle program costs, 

which are highly cost-effective.

To ensure that only emergency vehicle chassis would be able to certify to these less 

stringent standards, the agencies propose that manufacturers identify vehicles using the definition 

at 40 CFR 86.1803-01, which for Phase 2 purposes would be an ambulance or a fire truck. 

Manufacturers have informed us that it is feasible to identify such vehicles using sales codes or 

the presence of specialty attributes. The agencies request comment on the merits and drawbacks 

of aligning the definition of emergency vehicle for purposes of the Phase 2 program with the 

definition of emergency vehicle for purposes of the light-duty GHG provisions under 40 CFR 

86.1818, which includes additional vehicles such as those used by law enforcement.

According to the International Council on Clean Transportation (ICCT), less than one 

percent of all new heavy-duty truck registrations from 2003 to 2007 were emergency vehicles.272

On average, the ICCT’s data suggest that approximately 5,700 new emergency vehicles are sold 

in the U.S. each year; about 0.8 percent of the 3.4 million new heavy-duty trucks registered 

between 2003 and 2007. According to the Fire Apparatus Manufacturers Association, the annual 

 

272 ICCT, May 2009, “Heavy-Duty Vehicle Market Analysis: Vehicle Characteristics & Fuel Use, Manufacturer 

Market Shares”
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VMT of the newest emergency vehicles ranges from approximately 2,000 to 8,000 miles, as 

documented in their 2004 Fire Apparatus Duty Cycle White Paper.273 Because there are 

relatively few of these vehicles and they travel a relatively small number of miles, the agencies 

believe that setting less stringent GHG and fuel consumptions standards for these vehicles would 

not detract from the greater benefits of this rulemaking, and such separate standards are 

warranted in any case.

(b) Possible Standards for Other Custom Chassis Manufacturers

The agencies request comment on extending the above simplified compliance procedure 

and less stringent Phase 2 standards to other custom chassis manufacturers – those who offer 

such a narrow range of products that averaging is not of practical value as a compliance 

flexibility, and for whom there are not large sales volumes over which to distribute technology

development costs. Custom chassis manufacturers that are not small businesses must comply

with the Phase 1 standards and are generally doing so, by installing tires with the required 

coefficient of rolling resistance. We are aware of a handful of U.S. chassis manufacturers 

serving the recreational vehicle and bus markets who we believe would have a disproportionate 

compliance burden, should we require compliance with the primary proposed Phase 2 standards. 

According to the MOVES model forecast, there will be approximately 1,000 commercial 

intercity coach buses, 5,000 transit buses, 40,000 school buses, and 90,000 recreational vehicles 

manufactured new for MY 2018.274 In each of these markets, specialty chassis manufacturers 

compete with large vertically integrated manufacturers. We request comment on the merits of 

offering less stringent standards to small volume chassis manufacturers, and seek comment as 

well as to other factors the agencies should consider to ensure this approach would not have 

unintended consequences for businesses competing in the vocational vehicle market.

If the agencies were to adopt less stringent standards for custom non-emergency chassis 

manufacturers, we would expect to limit this by setting a maximum number of eligible 

vocational chassis annually for each such manufacturer. The agencies request comment on an 

appropriate sales volume to qualify for these possible standards, and also request comment as to 

whether the sales volume thresholds should be different for different markets. We further 

request comment on whether it would adversely affect business competitiveness if custom 

chassis manufacturers were held to a different standard than commercial chassis manufacturers, 

and whether the agencies should consider allowing commercial chassis manufacturers competing 

in these markets to sell a limited number of chassis certified to a less stringent standard. 

As an alternative approach, the agencies request comment on providing custom chassis 

manufacturers with additional lead time to comply. For example, we could allow such 

 

273 Fire Apparatus Manufacturer’s Association, Fire Apparatus Duty Cycle White Paper, August 2004, available at 

http://www.deepriverct.us/firehousestudy/reports/Apparatus-Duty-Cycle.pdf

274 Vehicle populations are estimated using MOVES2014. More information on projecting populations in MOVES is 

available in the following report: USEPA (2015). Population and Activity of On-road Vehicles in MOVES2014. 

EPA-420-D-15-001, available at http://www.epa.gov/otaq/models/moves/moves-reports.htm
Page 332 of 850

manufacturers an additional one or two years to meet each level of the primary proposed 

vocational vehicle standards. 

If the agencies pursued the approach of less stringent standards, we would likely adopt a 

simplified compliance procedure similar to the one proposed for emergency vehicles. Custom 

chassis manufacturers would not follow the otherwise applicable Phase 2 proposed approach of 

entering an engine map in GEM. Instead, a Phase 1 style GEM interface would be made 

available, where an EPA default engine specified by rule would be simulated in GEM. The 

vehicle-level standard would be predicated on a simpler set of technologies than the primary

proposed Phase 2 standard, most likely lower rolling resistance tires and idle reduction. Because 

these would not be emergency vehicles, we believe the performance of these vehicles would not 

be compromised by requiring improvement in tire CRR beyond that of the Phase 1 level. The 

agencies request comment on whether we should develop separate standards for different vehicle 

types such as recreational vehicles and buses. 

The Small Business Advocacy Review Panel recommended that EPA seek comment on 

how to design a small business vocational vehicle exemption by means of a custom chassis 

volume exemption and what sales volume would be an appropriate threshold. The agencies seek 

comments on all aspects of an approach for custom vocational vehicle chassis manufacturers that 

would enable us to adopt a final Phase 2 program that would be consistent with the 

recommendations of the panel.

(c) Off-Road and Low-Speed Vocational Vehicle Exemptions

The agencies are proposing to continue the exemptions in Phase 1 for off-road and lowspeed vocational vehicles, with revision. See generally 76 FR 57175. These provisions currently 

apply for vehicles that are defined as “motor vehicles” per 40 CFR 85.1703, but may conduct 

most of their operations off-road, such as drill rigs, mobile cranes and yard hostlers. Vehicles 

qualifying under these provisions must be built with engines certified to meet the applicable 

engine standard, but need not comply with a vehicle-level GHG or fuel consumption standard.

In Phase 1, this typically means not needing to install tires with a lower coefficient of rolling 

resistance. Because manufacturers choosing to exempt vehicles (but not engines) based on the 

criteria for heavy-duty off road vehicles at 40 CFR §1037.631 and 49 CFR §523.2 will for the 

first time provide a description to the agencies of how they meet the qualifications for this 

exemption in their end-of-the year reports in the spring of 2015, we do not have information 

beyond what we knew at the time of the Phase 1 rules regarding how broadly this provision is 

being used. Nonetheless, we are proposing to discontinue the criterion for exemption based 

solely on use of tires with maximum speed rating at or below 55 mph. The agencies are 

concerned that tires are so easily replaced that this would be an unreliable way to identify

vehicles that truly need special consideration. We are proposing to retain the qualifying criteria 

related to design and use of the vehicle. We invite comments on the proposed revisions to the 

qualifying criteria in the regulations, including whether the rated speed of the tires should be 

retained, and whether vehicles intended to be covered by this provision have characteristics that 

are captured by the proposed criteria.
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C. Feasibility of the Proposed Vocational Vehicle Standards

This section describes the agencies’ technological feasibility and cost analysis in greater 

detail. Further detail on all of these technologies can be found in the draft RIA Chapter 2.4 and 

Chapter 2.9. The variation in the design and use of vocational vehicles has led the agencies to 

project different technology solutions for each regulatory subcategory. Manufacturers may also 

find additional means to reduce emissions and lower fuel consumption than the technologies 

identified by the agencies, and of course may adopt any compliance path they deem most 

advantageous. The focus of this section is on the feasibility of the proposed standards for nonemergency vocational vehicles. Further, the agencies project that these technology packages 

would also be feasible for vocational tractors. With typical driving patterns having limited 

operation at highway speeds, vocational tractors would appropriately be classified as vocational 

vehicles, with proposed standards that would not be predicated on the performance of 

aerodynamic devices. The agencies propose to allow vocational tractors to follow the same 

subcategory assignment process as other vocational vehicles. For example, a beverage tractor 

intended for local delivery routes may have a driving pattern that is reasonably represented by

the proposed Urban test cycle. The agencies request comment on whether vocational tractors 

would be deficit-generating vehicles if certified as vocational vehicles, where performance 

would be measured against the proposed vocational vehicle baseline configurations. For 

example, if a tractor were designed with a higher power engine to carry a heavier payload than 

presumed in the GEM baseline for that subcategory, would GEM return a value that poorly 

represents the real world performance of that vehicle, and if so, would that merit a different 

certification approach for vocational tractors?

NHTSA and EPA 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 Southwest Research Institute evaluation of heavy-duty vehicle 

fuel efficiency and costs for NHTSA,275 the 2010 National Academy of Sciences report of 

Technologies and Approaches to Reducing the Fuel Consumption of Medium- and Heavy-Duty 

Vehicles,276 TIAX’s assessment of technologies to support the NAS panel report,277 the 

technology cost analysis conducted by ICF for EPA,

278 and the 2009 report from Argonne 

National Laboratory on Evaluation of Fuel Consumption Potential of Medium and Heavy Duty 

Vehicles through Modeling and Simulation.279 

 

275 Reinhart, T, 2015. Commercial Medium- and Heavy-Duty (MD/HD) Truck Fuel Efficiency Technology Study –

Reports #1 and #2. Washington, DC: National Highway Traffic Safety Administration; and Schubert, R., Chan, M., 

Law, K. 2015, Commercial Medium- and Heavy-Duty (MD/HD) Truck Fuel Efficiency Cost Study. Washington, 

DC: National Highway Traffic Safety Administration.

276 See NAS Report, Note 136, above.

277 See TIAX 2009, Note 137, above.

278 See ICF 2010, Note 139, above. 

279 Argonne National Laboratory, “Evaluation of Fuel Consumption Potential of Medium and Heavy Duty Vehicles 

through Modeling and Simulation.” October 2009
Page 334 of 850

(1) What Technologies Are the Agencies Considering to Reduce the CO2 Emissions 

and Fuel Consumption of vocational vehicles?

In assessing the feasibility of the proposed Phase 2 vocational vehicle standards, the 

agencies evaluated a suite of technologies, including workday idle reduction, improved tire 

rolling resistance, improved transmissions, improved axles, and weight reduction, as well as their 

impact on reducing fuel consumption and GHG emissions. The agencies also evaluated 

aerodynamic technologies and full electric vehicles. 

As discussed above, vocational vehicles may be powered by either SI or CI engines. The 

technologies and feasibility of the proposed engine standards are discussed in Section II. At the 

vehicle level, the agencies have considered the same suite of technologies and have applied the 

same reasoning for including or rejecting these vehicle-level technologies as part of the basis for 

the proposed standards, regardless of whether the vehicle is powered by a CI or SI engine. With 

the exception of the MY 2027 proposed standards, the analysis below does not distinguish 

between vehicles with different types of engines. The resulting proposed vehicle standards do 

reflect the differences arising from the performance of different types of engines over the GEM 

cycles.

(a) Vehicle Technologies Considered in Standard-Setting

The agencies note that the effectiveness values estimated for the technologies may

represent average values, and do not reflect the potentially-limitless combination 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 axle lubricants, each 

vehicle could have a unique effectiveness estimate depending on the baseline axle’s oil viscosity

rating. For purposes of this proposed rulemaking, 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 given technology. There may be real world effectiveness that 

exceeds or falls short of the average, but on-balance the agencies believe this is the most 

practicable approach for determining the wide ranging effectiveness of technologies in the 

diverse vocational vehicle arena. 

(i) Transmissions

Transmission improvements present a significant opportunity for reducing fuel 

consumption and CO2 emissions from vocational vehicles. Transmission efficiency is important 

for many vocational vehicles as their duty cycles involve high percentages of driving under 

transient operation. The three categories of transmission improvements the agencies considered 

for Phase 2 are driveline optimization, architectural improvements, and hybrid powertrain 

systems.

The agencies believe an effective way to derive efficiency improvements from a 

transmission is by optimizing it with the engine and other driveline components to balance both 

performance needs and fuel savings. However, many vocational vehicles today are not operating 

with such optimized systems. Because customers are able to specify their preferred components 

in a highly customized build process, many vocational vehicles are assembled with components 
Page 335 of 850

that were designed more for compatibility than for optimization. To some extent, vertically

integrated manufacturers are able to optimize their drivelines. However, this is not widespread 

in the vocational vehicle sector, resulting primarily, from the multi-stage manufacture process. 

The agencies project transmission and driveline optimization will yield a substantial proportion 

of vocational vehicle fuel efficiency and GHG emissions reduction improvements for Phase 2. 

On average, we anticipate that efficiency improvements of about five percent can be achieved 

from optimization, or deep integration of drivelines. However, we are not assigning a fixed level 

of improvement; rather we have developed a test procedure, the powertrain test, for 

manufacturers to use to obtain improvement factors representative of their systems. See Section 

V.E and the draft RIA Chapter 3 for a discussion of this proposed test procedure. Depending on 

the test cycle and level of integration, the agencies believe improvement factors greater than ten 

percent above the baseline vehicle performance could be achieved. To obtain such benefits 

across more of the vocational vehicle fleet, the agencies believe there is opportunity for 

manufacturers to form strategic partnerships and to explore commercial pathways to deeper 

driveline integration. For example, one partnership of an engine manufacturer and a 

transmission manufacturer has led to development of driveline components that deliver improved 

fuel efficiency based on optimization that could not be realized without sharing of critical 

data.280

The agencies project other related transmission technologies would be recognized over 

the powertrain test along with driveline optimization. These include improved mechanical gear 

efficiency, more sophisticated shift strategies, more aggressive torque converter lockups, 

transmission friction reduction, and reduced parasitic losses, as described in the 2009 TIAX 

report at 4.5.2. Each of these attributes would be simulated in GEM using default values, unless 

the powertrain test were utilized by the certifying manufacturer. The draft RIA Chapter 4 

explains each parameter that would be set as a fixed value in GEM. The expected benefits of 

improved gear efficiency, shift logic, and torque converter lockup are included in the total 

projected effectiveness of optimized conventional transmissions using the powertrain test.

Transmission efficiency could also be improved in the time frame of the proposed rules 

by changes in the architecture of conventional transmissions. Most vocational vehicles currently 

use torque converter automatic transmissions (AT), especially in Classes 2b-6. According to the 

2009 TIAX report, approximately 70 percent of Class 3-6 box and bucket trucks use AT, and all 

refuse trucks, urban buses, and motor coaches use AT.281 Automatic transmissions offer 

acceleration benefits over drive cycles with frequent stops, which can enhance productivity. 

However, with the diversity of vocational vehicles and drive cycles, other kinds of transmission 

architectures can meet customer needs, including automated manual transmissions (AMT) and 

even some manual transmissions (MT).282 

 

280 See Cummins-Eaton partnership at http://smartadvantagepowertrain.com/

281 See TIAX 2009, Note 137, above.

282 See http://www.truckinginfo.com/channel/equipment/article/story/2014/10/2015-medium-duty-trucks-thevehicles-and-trends-to-look-for/page/3.aspx (downloaded November 2014)
Page 336 of 850

One type of architectural improvement the agencies project will be developed by

manufacturers of all transmission architectures is increased number of gears. The benefit of 

adding more gears varies depending on whether the gears are added in the range where most 

operation occurs. The TIAX 2009 report projected that 8-speed transmissions could 

incrementally reduce fuel consumption by 2 to 3 percent over a 6-speed automatic transmission, 

for Class 3-6 box and bucket trucks, refuse haulers, and transit buses.283 Although the agencies 

estimate the improvement could on average be about two percent for the adding of two gears in 

the range where significant vehicle operation occurs, we are not assigning a fixed improvement 

based solely on number of transmission gears. Manufacturers would enter the number of gears 

and gear ratios into GEM and the model would simulate the efficiency benefit over the 

applicable test cycle. Because a public version of proposed GEM is being released with these 

proposed rules, stakeholders are free to use this tool to explore the effectiveness of different 

numbers of gears and gear ratios over the proposed test cycles. The agencies request comment 

on all aspects of the GEM tool, including how it models transmissions and shifting strategies. 

More details on GEM are available in the draft RIA Chapter 4.

Other architectural changes that the agencies project will offer efficiency improvements 

include improved automated manual transmissions (AMT) and introduction of dual clutch 

transmissions (DCT). Newer versions of AMT are showing significant improvements in 

reliability, such that the current generation of transmissions with this architecture is more likely 

to retain resale value and win customer acceptance than early models.

284

 The agencies believe 

AMT generally compare favorably to manual transmissions in fuel efficiency, and while the 

degree of improvement is highly driver-dependent, it can be two percent or greater, depending on 

the drive cycle. See Section III for additional discussion of AMT. The agencies are not assigning 

fixed average performance levels to compare an AMT with a traditional automatic transmission. 

Although the lack of a torque converter offers AMT an efficiency advantage in one respect, the 

lag in power during shifts is a disadvantage. For Phase 2, the agencies have developed validated 

models of both AMT and AT, as described in the draft RIA Chapter 4. Manufacturers installing 

AMT or AT would enter the relevant inputs to GEM and the simulation would calculate the 

performance. Dual clutch transmissions (DCT) designed for medium heavy-duty vocational 

vehicles are already in production, and could reasonably be expected to be adapted for other 

weight classes of vocational vehicles during the time frame of Phase 2.285 Based on supplier 

conversations, manufacturers intend to match varying DCT designs with the diverse needs of the 

heavy-duty market. The agencies do not yet have a validated DCT model in GEM, and we are 

not assigning a fixed performance level for DCT, though we expect the per-vehicle fuel 

efficiency improvement due to switching from automatic to DCT to be in the range of three 

 

283 See TIAX 2009, Note 137, Table 4-48.

284 See NACFE Confidence Report: Electronically Controlled Transmissions, at 

http://www.truckingefficiency.org/powertrain/automated-manual-transmissions (January 2015). See also 

http://www.overdriveonline.com/auto-vs-manual-transmission-autos-finding-solid-ground-by-sharing-data-withengines/ (accessed November 2014)

285 See Eaton Announcement September 2014, available at 

http://www.ttnews.com/articles/lmtbase.aspx?storyid=2969&t=Eaton-Unveils-Medium-Duty-ProcisionTransmission.
Page 337 of 850

percent over the GEM vocational vehicle test cycles. Selection of transmission architecture type 

(Manual, AMT, AT, DCT) would be made by manufacturers at the time of certification, and 

GEM would either use this input information to simulate that transmission using algorithms as 

described in the draft RIA Chapter 4, or fixed improvements may be assigned. The agencies are 

assigning fixed levels of improvement that vary by test cycle in GEM for AMT when replacing a 

manual, which for vocational vehicles would be in the HHD Regional subcategory. If a 

manufacturer elected not to conduct powertrain testing to obtain specific improvements for use 

of a DCT, GEM would simulate a DCT as if it were an AMT, with no fixed assigned benefit. 

The draft RIA at Chapter 2.9 describes the projected effectiveness of each type of transmission 

improvement for each vocational vehicle test cycle. 

Hybrid powertrain systems are included under transmission technologies because, 

depending on the design and degree of hybridization, they may either replace a conventional 

transmission or be deeply integrated with a conventional transmission. Further, these systems

are often manufactured by companies that also manufacture conventional transmissions.

The agencies are including hybrid powertrains as a technology on which some of the 

proposed vocational vehicle standards are predicated. We project a variety of mild and strong 

hybrid systems, with a wide range of effectiveness. Mild hybrid systems that offer an engine 

stop-start feature are discussed below under workday idle reduction. For hybrid powertrains, we 

are estimating a 22 to 25 percent fuel efficiency improvement over the powertrain test, 

depending on the duty cycle in GEM for the applicable subcategory. The agencies obtained 

these estimates by projecting a 27 percent effectiveness over the ARB Transient cycle, and zero 

percent over the constant-speed highway cruise cycles. With the proposed cycle weightings, this 

calculates to a 25 percent improvement over the Urban cycle, and 22 percent over the MultiPurpose cycle. According to the NREL Final Evaluation of UPS Diesel Hybrid-Electric 

Delivery Vans, the improvement of a hybrid over a conventional diesel in gallons per ton-mile 

on a chassis dynamometer over the NYC Composite test cycle was 28 percent.286 NREL 

characterizes the NYC Composite cycle as more aggressive than most of the observed field data 

points from the study, and may represent an ideal hybrid cycle in terms of low average speed, high 

stops per mile, and high kinetic intensity. NREL noted that most of the observed field data points 

were reasonably represented by the HTUF4 cycle, over which the chassis dynamometer results 

showed a 31 percent improvement in gallons per ton-mile. In units of grams CO2 per mile, 

NREL reported these test results as 22 percent improvement over the NYC Composite cycle and 

26 percent improvement over the HTUF4 cycle. Based on these results, and the fact that any 

improvement from strong hybrids in Phase 2 would not be simulated in GEM, but rather would 

be evaluated using the powertrain test, the agencies deemed it reasonable to estimate a 

conservative 27 percent effectiveness over the ARB Transient in setting the stringency of the 

proposed standards.

 

286 Lammert, M., Walkowivz, K., NREL, Eighteen-Month Final Evaluation of UPS Second Generation Diesel 

Hybrid-Electric Delivery Vans, September 2012, NREL/TP-5400-55658
Page 338 of 850

The Phase 1 standards were not predicated on any adoption of hybrid powertrains in the 

vocational vehicle sector. Because the first implementation year of Phase 1 came just three years 

after promulgation, there was insufficient lead time for development and deployment of the 

technology.

287

 In addition, our proposed Phase 2 vocational vehicle GEM test cycles are 

expected to better recognize hybrid technology effectiveness than the Phase 1 hybrid test cycle, 

especially in the Urban subcategory. Further, our Phase 2 cost analysis shows that hybrid 

systems designed for LHD and MHD vocational vehicles would cost less than the costs we were 

projecting in Phase 1. The agencies believe the Phase 2 rulemaking timeframes would offer 

sufficient lead time to develop, demonstrate, and conduct reliability testing for technologies that 

are still maturing, including these hybrid technologies.

Several types of vocational vehicles are well suited for hybrid powertrains, and are 

among the early adopters of this technology. 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.

There are a few hybrid systems in the market today and several more under development. In 

addition, energy storage systems are improving.288 Heavy-duty customers are getting used to 

these systems with the number of demonstration products on the road. Even so, some 

manufacturers may be uncertain how much investment to make in this technology without clear 

signals about future market demand. A list of hybrid manufacturers and their products intended 

for the vocational market is provided in the draft RIA Chapter 2.9. 

Some low cost products on the simple end of the hybrid spectrum are available that 

minimize battery demand through the use of ultracapacitors or only provide power assist at low 

speeds. Our regulations define a hybrid system as one that has the capacity for energy storage.289 

In the light-duty GHG program a mild hybrid is defined as including an integrated starter 

generator, a high-voltage battery (above 12v), and a capacity to recover at least 15 percent of the 

braking energy. In such systems some accessories are usually electrified. Strong hybrids are 

typically referred to as those that have larger energy recovery and storage capacity, defined at 65 

percent braking energy recovery in the light-duty GHG program. Although integration of a 

strong hybrid system may enable installation of a downsized engine in some cases, the agencies 

have not projected any vocational engine downsizing for any hybrid systems as part of our Phase 

 

287 In addition to concerns over adequacy of lead time, the agencies described concerns over “modest” emission 

reductions. See 76 FR 57234. Even so, in Phase 1 the agencies adopted provisions for hybrids to generate advanced 

technology credits.

288 Green Fleet Magazine, The Latest Developments in EV Battery Technology, November 2013, available at 

http://www.greenfleetmagazine.com/article/story/2013/12/the-latest-developments-in-ev-battery-technologygrn/page/1.aspx

289 NHTSA’s and EPA’s regulations define a hybrid vehicle as one that “includes energy storage features ... in 

addition to an internal combustion engine or other engine using consumable chemical fuel....” 49 CFR 535.4 and 40 

CFR 1037.801.
Page 339 of 850

2 technology assessment. This is in part to be conservative in our cost estimates, and in part 

because in some applications a smaller engine may not be acceptable if it would risk that 

performance could be sacrificed during some portion of a work day. Depending on the drive 

cycle and units of measurement, strong hybrids developed to date have seen fuel consumption 

and CO2 emissions reductions between 20 and 50 percent in the field.290

The agencies are working to reduce barriers related to hybrid vehicle certification. In 

Phase 1, there is a significant test burden associated with demonstrating the GHG and fuel 

efficiency performance of vehicles with hybrid powertrain systems. Manufacturers must obtain 

a conventional vehicle that is identical to the hybrid vehicle in every way except the 

transmission, test both, and compare the results.291 In Phase 2, the agencies are proposing that 

manufacturers would conduct powertrain testing on the hybrid system, and the results of that 

testing would become inputs to GEM for simulation of the non-powertrain features of the hybrid

vehicle, removing a significant test burden. 

In discussions with manufacturers during the development of Phase 2, the agencies have 

learned that meeting the on-board diagnostic requirements for criteria pollutant engine 

certification continues to be a potential impediment to adoption of hybrid systems. See Section 

XIV.A.1 for a discussion of regulatory changes proposed to reduce the non-GHG certification 

burden for engines paired with hybrid powertrain systems. The agencies have also received a 

letter from the California Air Resources Board requesting consideration of supplemental NOX

testing of hybrids. The agencies request comment on the Air Resources Board’s letter and 

recommendations.292

(ii) Axles

The agencies are considering two axle technologies for the vocational vehicle sector. The 

first is advanced low friction axle lubricants. SwRI tested improved driveline lubrication and 

found measurable improvements by switching from current mainstream products to newer

formulations focusing on modified viscometric effects.293 Synthetic lubricant formulations can 

offer superior thermal and oxidative stability compared to petroleum or mineral based lubricants. 

The agencies believe that a 0.5 percent improvement in vocational vehicle efficiency (as for 

tractors) is achievable through the application of low friction axle lubricants, and have included 

that value as a fixed value in GEM. Beyond the use of different lubricant formulations, some 

axle manufacturers are offering products that achieve efficiency improvements by varying the 

 

290 Van Amburg, Bill, CALSTART, Status Report: Alternative Fuels and High-Efficiency Vehicles, Presentation to 

National Association of Fleet Administrators (NAFA) 2014 Institute and Expo, April 8, 2014

291 See test procedures at 40 CFR 1037.555

292 California Air Resources Board. Letter from Michael Carter to Matthew Spears dated December 29, 

2014. CARB Request for Supplemental NOX Emission Check for Hybrid Vehicles. Docket EPA-HA-OAR-2014-

0827.

293 Reinhart, T. (2015). Commercial Medium- and Heavy-Duty (MD/HD) Truck Fuel Efficiency Technology Study –

Report #1. Washington, DC: National Highway Traffic Safety Administration. See T-270 Delivery Truck Vehicle 

Technology Results
Page 340 of 850

lubrication levels with vehicle speed, reducing churning losses. The agencies request comment 

on whether we could accept these systems as qualifying for a fixed GEM improvement value. If 

a manufacturer wishes to demonstrate the benefit of a specific axle technology, an off-cycle

technology credit would be necessary. To support such an application, manufacturers could 

conduct a rear axle efficiency test, as described in the draft RIA Chapter 3.8. Proposed 

regulations for this test procedure can be found at 40 CFR 1037.515. Our estimated axle 

lubricating costs do not include operational costs such as refreshing lubricants on a periodic 

basis. Based on supplier information, it is likely that some advanced lubricants may have a 

longer drain interval than traditional lubricants. We are estimating the axle lubricating costs for 

HHD to be the same as for tractors since those vehicles likewise typically have three axles. 

However, for LHD and MHD vocational vehicles, we scaled down the cost of this technology to 

reflect the presence of a single rear axle.

The second axle technology the agencies are considering is a design that enables one of 

the rear axles to disconnect or otherwise behave as if it’s a non-driven axle, on vehicles with two 

rear (drive) axles, commonly referred to as a 6x2 configuration. The agencies have considered 

two types of 6x2 configurations for vocational vehicles: those that are engaged full time on a 

vehicle, and those that may be engaged only during some types of vehicle operation, such as only 

when operating at highway cruise speeds. Some early versions of 6x2 technology offered by

manufacturers were not accepted by vehicle owners. When the second drive axle is no longer 

powered, traction may be sacrificed in some cases. Vehicles with earlier versions of this 

technology have seen reduced residual values in the secondary market. Over the model years 

covered by the Phase 2 rules, the agencies expect the market to offer significantly improved 

versions of this technology, with traction control maintained at lower speeds and efficiency gains 

at highway cruise speeds.294 Further information about this technology is provided in the 

feasibility of the tractor standards, Section III, as well as in draft RIA Chapter 2.4. 

The efficiency benefit of a 6x2 axle configuration can be duty-cycle dependent. In many

instances, vocational vehicles need to operate off-highway, such as at a construction site 

delivering materials or dumping at a refuse collection facility. In these cases, vehicles with two 

drive axles may need the full tractive benefit of both drive axles. The part-time 6x2 axle 

technology is not expected to measurably improve a vehicle’s efficiency for vehicles whose 

normal duty cycle involves performing significant off-highway work, but the agencies do expect 

this technology to be recognized over a highway cruise cycle.

Some vocational vehicles in the HHD Regional subcategory may see a 6x2 axle 

configuration as a reasonable option for improving fuel efficiency. As in Phase 1, our vehicle 

simulation model assumes that only HHD vehicles have two rear axles, so only these could be 

recognized for adopting this technology. Further, the agencies don’t believe the Multipurpose 

and Urban subcategories include a significant enough highway cycle weighting in the composite 

 

294 NACFE, Confidence Findings on the Potential of 6x2 Axles, available at http://nacfe.org/wpcontent/uploads/2014/01/Trucking-Efficiency-6x2-Confidence-Report-FINAL-011314.pdf, January 2014 

(downloaded November 2014).
Page 341 of 850

cycle for vehicles that operate in this manner to experience a benefit from adopting this 

technology. The agencies project this can achieve 2 percent benefit at highway cruise;

295 thus,

we propose to assign a fixed value in GEM for part-time 6x2 technology of 2.5 percent over the 

highway cruise cycles, where the specific improvement would be calculated according to the 

composite weighting of the applicable vocational vehicle test cycle. We request comment on the 

best way to recognize this technology in Phase 2, either through a GEM calculation or a fixed 

assigned value, for vocational vehicles.

(iii) Lower 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.296 There is a wide range of rolling 

resistance of tires used on vocational vehicles today. 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 vocational vehicle buyers to value tire traction and durability more heavily than rolling 

resistance. 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, based on input from tire suppliers, the agencies expect that the LRR 

tires that will be available in the Phase 2 timeframe will not compromise performance parameters 

such as traction, handling, wear, retreadability, or structural durability. 

After the Phase 1 rules were promulgated, NHTSA and EPA conducted supplemental tire 

testing. Other data that have become available to the agencies since Phase 1 include precertification data provided to manufacturers by tire suppliers in preparation for MY 2014 vehicle 

certification. 297 The agencies categorized the data by tire position and vehicle application, so 

that we have a representation of the variety of LRR vocational vehicle tires that are available in 

the market for the drive position, steer and all-position tires, as well as wide base singles in all 

positions. Based on our data set that includes results from multiple laboratories, drive tires that 

are intended for vocational vehicles have an average CRR of 7.8, and steer and all-position tires 

that are intended for vocational vehicles have an average CRR of 6.7. The results also indicate 

that there are a variety of wide based single tires that are intended for vocational vehicles, with 

an average CRR of 6.6. Each of these data sets shows several models of commercial tires are 

available at levels of CRR ranging generally from 20 percent worse than average to 20 percent 

better than average. Further details are presented in the draft RIA Chapter 2.

According to the 2014 SwRI report, vocational vehicles are likely to see the most benefits 

from reduced tire rolling resistance when they are driving at 55 mph.298 This report also found 

an influence of vehicle weight on the benefits of LRR tires. The study found that both vocational 

vehicles tested had greater benefits of LRR tires at 100 percent payload than when empty. Also, 

 

295 See NHTSA Technology Report #1, Note 293 , T-700 Class 8 Tractor-Trailer Vehicle Technology Results.

296 See Argonne National Laboratory 2009 report, Note 279, page 91.

297 See memorandum dated May 2015 on Vocational Vehicle Tire Rolling Resistance Test Data Evaluation.

298 See NHTSA Technology Report #1, Note 293, T-270 Delivery Truck Vehicle Technology Results
Page 342 of 850

the T270 delivery box truck that was 4,000 pounds heavier when fully loaded saw slightly 

greater efficiency gains from LRR tires than the F650 flatbed tow truck over the same cycles. At 

higher speeds, aerodynamic drag grows, which reduces the rolling resistance share of total 

vehicle power demand. In highly transient cycles, the power required to accelerate the vehicle 

inertia overshadows the rolling resistance power demand. In simulation, GEM represents 

vocational vehicles with fixed vehicle weights, payloads and aerodynamic coefficients. Thus, 

the benefit of LRR tires will be reflected in GEM differently for vehicles of different weight 

classes. There will also be further differences arising from the different test cycles. Based on 

preliminary simulations, it appears the vehicles in GEM most likely to see the greatest fuel 

efficiency gains from use of LRR tires are those in the MHD weight classes tested over the 

Regional or Multipurpose duty cycles, where one percent efficiency improvement could be 

achieved by reducing CRR by four to five percent. Those seeing the least benefit from LRR tires 

would likely be Class 8 vehicles tested over the Urban or Multipurpose cycles, where one 

percent efficiency improvement could be achieved by reducing CRR by seven to eight percent.

The agencies propose to continue the light truck (LT) tire CRR adjustment factor that was 

adopted in Phase 1. See generally 76 FR 57172-74. In Phase 1, the agencies developed this 

adjustment factor by dividing the overall vocational test average CRR of 7.7 by the LT 

vocational average CRR of 8.9. This yielded an adjustment factor of 0.87. After promulgation 

of the Phase 1 rules, the agencies conducted additional tire CRR testing on a variety of LT tires, 

most of which were designated as all-position tires. In addition, manufacturers have submitted to 

the agencies pre-certification data that include CRR values provided by tire suppliers. For the 

small subset of newer test tires that were designated as steer tires, the average CRR was 7.8 

kg/ton. For the subset of newer test tires that were designated as drive tires, the average CRR 

was 8.6 kg/ton. However all-position tires had an average CRR of 8.9 kg/ton.299 Therefore, for 

LT vocational vehicle tires, we propose to continue allowing the measured CRR values to be 

multiplied by a 0.87 adjustment factor before entering the values in the GEM for compliance, 

because this additional testing has not revealed compelling information that a change is needed. 

We request comment on whether the adjustment factor should be retained, as well as data on 

which to base a possible update of its numerical value. 

As described above in V. B. (4) (c), the agencies are proposing to continue the Phase 1 

off-road and low speed exemptions in Phase 2, with the proposed revision of discontinuing the 

option to qualify for this exemption solely if the vehicle is fitted with tires that have a maximum 

speed rating at or below 55 mph. The agencies welcome comments on this revision.

(iv) Workday Idle Reduction

The Phase 2 idle reduction technologies considered for vocational vehicles are those that 

reduce workday idling, unlike the overnight idling of combination tractors. There are many

potential technologies. The agencies in particular evaluated neutral idle and stop-start 

technologies, and the proposed standards are predicated on projected amounts of penetrations of 

these technologies, described in Section V. C. (2) . While neutral idle is necessarily a 

 

299 See tire memorandum, Note 297
Page 343 of 850

transmission technology, stop-start could range from an engine technology to one that would be 

installed by a secondary manufacturer under a delegated assembly agreement. 

The agencies are aware that for a vocational vehicle’s engine to turn off during workday 

driving conditions, there must be a reserve source of energy to maintain functions such as power 

steering, cabin heat, and transmission pressure, among others. Stop-start systems can be viewed 

as having a place on the low-cost end of the hybridization continuum. As described in Section

V. C. (2) and in the draft RIA Chapter 2.9, the agencies are including the cost of energy storage 

sufficient to maintain critical onboard systems and restart the engine as part of the cost of 

vocational vehicle stop-start packages. The technologies to capture this energy could include a 

system of photovoltaic cells on the roof of a box truck, or regenerative braking. The 

technologies to store the captured energy could include a battery or a hydraulic pressure bladder. 

More discussion of stop-start technologies is found in the draft RIA Chapter 2.4.

The agencies intend for the technologies that would qualify to be recognized in GEM as 

stop-start to be broadly defined, including those that may be installed at different stages in the 

manufacturing process. The agencies request comment on an appropriate definition of stop-start 

technologies for vocational vehicles. 

The agencies are also proposing a certification test cycle that measures the amount of fuel 

saved and CO2 reduced by these two primary types of idle reduction technologies: neutral idle

and stop-start. Vocational vehicles frequently also idle while cargo is loaded or unloaded, and 

while operating a PTO such as compacting garbage or operating a bucket. In these rules, the 

agencies are proposing that the Regional duty cycle have ten percent idle, the Multi-purpose 

cycle have 15 percent idle, and the Urban cycle have 20 percent idle. These estimates are based 

on publically available data published by NREL.300 To bolster this information, EPA entered 

into an interagency agreement with NREL to characterize workday idle among vocational 

vehicles. One task of this agreement is to estimate the nationally representative fraction of idle 

operation for vocational vehicles for each proposed regulatory subcategory including a 

distinction between idling while driving or stopping in gear, and idling while parked. The 

preliminary range of total daily idle operation per vehicle indicated by this work is about 18

percent to 33 percent when combining the data from all available vehicles. The agencies request 

comment regarding the nature of vocational workday idle operation, including how much of it is 

in traffic and how much is while the vehicle is parked. Depending on comments and additional 

information received during the comment period, it may be within the agencies’ discretion to 

adopt different final test cycles, or re-weight the current test cycles, to better represent real world 

driving and better reflect performance of the technology packages. An analysis of possible 

vocational vehicle standards derived from alternate characterizations of idle operation has been 

prepared by the agencies, and is available for review in the public docket for this rulemaking.301

 

300 See NREL data at http://www.nrel.gov/vehiclesandfuels/fleettest/research_fleet_dna.html

301 See memorandum dated May 2015 on Analysis of Possible Vocational Vehicle Standards Based on Alternative 

Idle Cycle Weightings
Page 344 of 850

Based on GEM simulations using the currently proposed vocational vehicle test cycles, 

the agencies estimate neutral idle for automatic transmissions to provide fuel efficiency

improvements ranging from one percent to nearly four percent, depending on the regulatory

subcategory. The agencies estimate stop-start to provide fuel efficiency improvements ranging 

from 0.5 percent to nearly seven percent, depending on the regulatory subcategory. Because of 

the higher idle weighting factor in the Urban test cycle, vehicles certified in these subcategories 

would derive the greatest benefit from applying idle reduction technologies.

Although the primary program would not simulate vocational vehicles over a test cycle 

that includes PTO operation, the agencies are proposing to continue, with revisions, the hybridPTO test option that was in Phase 1. See 40 CFR 1037.525 and 76 FR 57247. Recall that we are 

proposing to regulate vocational vehicles at the incomplete stage when a chassis manufacturer 

may not know at the time of certification whether a PTO will be installed or how the vehicle will 

be used. Based on stakeholder input, chassis manufacturers are expected to know whether a 

vehicle’s transmission is PTO-enabled. However, that is very different from knowing whether a 

PTO will actually be installed and how it will be used. Chassis manufacturers may rarely know 

whether the PTO-enabled vehicle will use this capability to maneuver a lift gate on a delivery

vehicle, to operate a utility boom, or merely to keep it as a reserve item to add value in the 

secondary market. In cases where a manufacturer can certify that a PTO with an idle-reduction 

technology will be installed either by the chassis manufacturer or by a second stage 

manufacturer, the hybrid-PTO test cycle may be utilized by the certifying manufacturer to 

measure an improvement factor over the GEM duty cycle that would otherwise apply to that 

vehicle. In addition, the delegated assembly provisions would apply. See Section V.E for a 

description of the delegated assembly provisions. See draft RIA Chapter 3 for a discussion of 

the proposed revisions to the PTO test cycle. 

The agencies have reason to believe there may be a NOX co-benefit to stop-start idle 

reduction technologies, e-PTO, and possibly also to neutral idle. For this to be true, the benefits 

of reduced fuel consumption and retained aftertreatment temperature would have to outweigh 

any extra emissions due to re-starts. In the draft RIA Chapter 2.9, there is a more detailed 

discussion of the relationship between idle reduction and NOX co-benefits. The agencies request 

comments and relevant test data that can help inform this issue.

(v) Weight Reduction

The agencies believe there is opportunity for weight reduction in some vocational 

vehicles. According to the 2009 TIAX report, there are freight-efficiency benefits to reducing 

weight on vocational vehicles that carry heavy cargo, and tax savings potentially available to 

vocational vehicles that remain below excise tax weight thresholds. This report also estimates 

that the cost effectiveness of weight reduction over urban drive cycles is potentially greater than 

the cost effectiveness of weight reduction for long haul tractors and trailers. On a city duty 

cycle, 89 percent of the vehicle’s road load is weight dependent, compared to 38 percent on a 
Page 345 of 850

steady-state 55 mph duty cycle.302 The 2014 SwRI report found that weight reduction provides a 

greater fuel efficiency benefit for vehicles driving under transient conditions than for those 

operating under constant speeds. In simulation, the study found that the two Class 6 trucks 

improved fuel efficiency by over two percent on the ARB transient cycle by removing 1,100 lbs. 

Further, SwRI observed that the improvements due to weight reduction behaved linearly.

303

 The 

proposed menu of components available for a vocational vehicle weight credit in GEM is 

presented in Section V.E and in the draft RIA Chapter 2.9. It includes fewer options than for 

tractors, but the agencies believe there are a number of feasible material substitution choices at 

the chassis level, which could add up to weight savings on the order of a few hundred pounds. 

The agencies project that refuse trucks, construction vehicles, and weight-limited regional 

delivery vehicles could reasonably apply material substitution for weight reduction. We do not 

expect this to be broadly applicable across many types of vocational vehicles. Based on the 

assumed payload in GEM, and depending on the vocational vehicle subcategory, the agencies 

believe a reduction of 200 pounds may offer a fuel efficiency improvement of approximately 1 to 

2 percent.

Without more specific data on which to base our assumptions, the agencies are proposing 

to allocate 50 percent of any mass reduction to increased payload, and 50 percent to reduce the 

chassis weight. We considered the data on which the tractor weight allocation (1/3:2/3) is based, 

but determined this would not be valid for vocational vehicles, as the underlying data pertained 

only to long haul tractor-trailers. The agencies propose that 50 percent of weight removed from 

vocational vehicle chassis would be added back as additional payload in GEM. This suggests an 

equal likelihood that a vehicle would be reducing weight for benefits of being lighter, or 

reducing weight to carry more payload. The agencies welcome data that could better inform the 

fraction of weight reduced for vocational vehicles that is added back as payload.

The agencies request comment on whether the HD Phase 2 program should recognize 

that weight reduction of rotating components provides an enhanced fuel efficiency benefit over 

weight reduction on static components. In theory, as components such as brake rotors, brake 

drums, wheels, tires, crankshafts, camshafts, and piston assemblies become lighter, the power 

consumption to rotate the masses would be directly proportional to the mass decrease. Using 

physical properties of a rotating component such as a wheel, it is relatively straightforward to 

calculate an equivalent mass. However, we do not have enough information to derive industry

average values for equivalent mass, nor have we evaluated the best way for GEM to account for 

this.

(vi) HFC Refrigerant from Cabin Air Conditioning (A/C) Systems

Manufacturers can reduce direct A/C leakage emissions by utilizing leak-tight 

components. EPA’s proposed HFC direct emission leakage standard would be independent of 

 

302 Helms 2003 as referenced in TIAX 2009.

303 See NHTSA Technology Report #1, Note 293, T-270 Delivery Truck Vehicle Technology Results and Vehicle 

Performance in the F-650 Truck
Page 346 of 850

the CO2 vehicle standard. Manufacturers could choose components from a menu of leakreducing technologies sufficient to comply with the standard, as opposed to using a test to 

measure performance. See 76 FR 57194/3.

In Phase 1, EPA adopted a HFC leakage standard to assure that high-quality, low-leakage 

components are used in each air conditioning system installed in HD pickup trucks, vans, and 

combination tractors (see 40 CFR 1037.115(c)). We did not adopt a HFC leakage standard in 

Phase 1 for systems installed in vocational vehicles. EPA is proposing in Phase 2 to extend the 

HFC leakage standard that exists due to Phase 1 requirements to all vocational 

vehicles. Beginning in the 2021 model year, EPA proposes that vocational vehicle air 

conditioning systems with a refrigerant capacity of greater than 733 grams meet a leakage rate of 

1.50 percent leakage per year and systems with a refrigerant capacity of 733 grams or lower meet 

a leakage standard of 11.0 grams per year. EPA believes this proposed approach of having a 

leak rate standard for lower capacity systems and a percent leakage per year standard for higher 

capacity systems would 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.

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 began in the 2012 model year and the 

HD Phase 1 rule that began in the 2014 model year. 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.304 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 2021. However, 

EPA has recognized some manufacturers utilize an improved manufacturing process for air 

conditioning systems, where a helium leak test is performed on 100 percent of all o-ring fittings 

and connections after final assembly. By leak testing each fitting, the manufacturer or supplier is 

verifying the o-ring is not damaged during assembly (which is the primary source of leakage 

from o-ring fittings), and when calculating the yearly leak rate for a system, EPA will allow a 

relative emission value equivalent to a ‘seal washer’ can be used in place of the value normally

used for an o-ring fitting, when 100 percent helium leak testing is performed on those 

fittings. The agencies request comment on other possible improvements in the design of air 

conditioning systems that EPA could recognize for the purposes of compliance with this 

proposed standard. For example, should the agency recognize electrified compressors as having 

a zero leak rate, and should we allow vehicles fitted with electrified compressors to use a 

simplified version of the compliance reporting form? Please see Section I.F.1 (b) of this 

preamble for a description of proposed program-wide revisions to EPA’s HFC leakage standards 

that would address air conditioning systems designed for alternative refrigerants.

 

304 Team 1-Refrigerant Leakage Reduction: Final Report to Sponsors, SAE, 2007.
Page 347 of 850

The HFC control costs presented in the draft RIA Chapter 2.9 and 2.12 are applied to all 

heavy-duty vocational vehicles. 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 proposed rules.

(b) Engine Technologies Considered in Vehicle Standard-Setting

Section II explains the technical basis for the agencies’ proposed separate engine 

standards. The agencies are not proposing to predicate the vocational vehicle standards on 

different diesel engine technology packages than those presumed for compliance with the 

separate diesel engine standards. However, for the proposed MY 2027 vocational vehicle 

standards, the agencies are predicating the SI-powered vocational vehicle standards on a gasoline

engine technology package that includes additional friction reduction beyond that presumed for 

compliance with the MY 2016 gasoline engine standard. Chapter 2 of the draft RIA provides 

more details on each of the technologies that can be applied to both gasoline and diesel engines.

The vehicle-level standards would vary depending on whether the engines powering 

those vehicles are compression-ignition or spark-ignition.305 In Phase 1, this was not the case 

because GEM used a default engine that was the same for every vehicle configuration, regardless 

of the actual engine being installed. As described above in Section II, the Phase 2 vehicle 

certification tool, GEM, would require manufacturers to enter specific engine performance data, 

where emissions and fuel consumption profiles would differ significantly depending on the 

engine’s architecture.306

As explained in Section II.A.2, engines would continue to be certified over the FTP test 

cycle. The FTP test cycle that is applicable for bare vocational engines is very different than the 

proposed test cycles for vocational vehicles in GEM. The FTP is a very demanding transient 

cycle that exercises the engine over its full range of capabilities. In contrast, the cycles evaluated 

by GEM measure emissions over more frequently used engine operating ranges. The ARB 

Transient vehicle cycle represents city driving, and the highway cruise cycles measure engine 

operation that is closer to steady state. Each of these cycles is described in the draft RIA Chapter

3. A consequence of recognizing engine performance at the vehicle level would be that further 

engine improvements (i.e. improvements measureable by duty cycles that more precisely 

represent driving patterns for specific subcategories of vocational vehicles) could be evaluated as 

possible components of a technical basis for a vocational vehicle standard.307 For this reason, the 

agencies considered whether any different engine technologies should be included in the 

feasibility analysis for the vehicle standards (and potentially, in the proposed standard 

stringency). 

 

305 Specifically, EPA is proposing CO2, N2O, and CH4 emission standards for new heavy-duty engines over an EPA 

specified useful life period (See Section II).

306 See Section II.D.5 for an explanation of which engine architecture would need to meet which standard.

307 As noted in II.B.2 above, manufacturers also have greater flexibility to meet a vehicle standard if engine 

improvements can be evaluated as part of compliance testing. 
Page 348 of 850

One CI engine technology that might be recognized over a vehicle highway cruise cycle 

would be waste heat recovery (WHR). However, the agencies do not consider this to be a 

feasible technology for vocational engines. As described in Section II of this preamble and 

Chapter 2.3 of the draft RIA, there currently are no commercially available WHR systems for 

diesel engines, although most engine manufacturers are exploring this technology. While it 

would be possible to capture excess heat from a vocational engine operating at highway speeds,

many vocational vehicles spend insufficient time at highway speeds to generate enough excess 

heat to make this technology worthwhile. As explained in Section II.D, the agencies are 

projecting a very small adoption rate of WHR even in the tractor engine market. Because the 

research is currently being conducted to apply this technology for tractors, it is logical that future 

research may reveal ways to adapt this technology for those vocational engines that are intended 

for on-highway applications. The agencies do not believe this technology will be developed to 

the point of commercial readiness for vocational vehicles in the time frame of these proposed 

rules.

The agencies assessed three SI engine technologies for possible inclusion in the 

vocational vehicle technology packages: cylinder deactivation, variable valve timing, and 

advanced friction reduction. These might be recognized over the proposed vocational vehicle 

test cycles in GEM through use of the proposed engine mapping procedures. To the extent either 

cylinder deactivation or variable valve timing would be adopted for complete heavy-duty

pickups and vans, they would be recognized over the complete chassis test specified for that 

segment and possibly over the GEM highway cruise cycles, however the aggressive bare engine 

FTP test is unlikely to put the engine into operating modes that activate either of those 

technologies. Based on stakeholder input, the agencies project that the SI engines certified over 

the FTP and fitted into vocational vehicles would most likely be designed as overhead valve 

engines, for which the only kind of VVT available is dual cam phasing.308 Dual cam phasing is 

already included at 100 percent adoption rate in the feasibility and stringency of the MY 2016 

bare engine standard. If manufacturers choose to fit vocational vehicles with coaxial camshaft SI

engines, additional VVT options would be feasible and could be recognized over the vocational 

vehicle test cycles. Based on stakeholder input, the agencies project that some SI engines 

certified over the FTP and fitted into vocational vehicles may be designed with cylinder 

deactivation by MY 2021. However, the agencies do not have enough information at this time to 

quantify the potential fuel efficiency improvements over the vocational vehicle test cycles for 

engines with cylinder deactivation or various designs implementing VVT. Therefore we are not 

proposing to predicate the SI-powered vocational vehicle standards on use of these technologies. 

In Section II.D, the agencies explain why we are not proposing a more stringent separate 

SI vocational engine standard in Phase 2 based on additional engine technologies beyond those 

assumed for the Phase 1 MY 2016 standard. The agencies are instead proposing to include 

adoption and performance of advanced engine friction reduction technology as a basis for the 

proposed SI-powered vocational vehicle standards. Based on Volpe model results presented in 

preamble Section VI, the agencies project that manufacturers of some SI engines for complete 

 

308 See preamble Section VI.C.5.(a) under Coupled Cam Phasing
Page 349 of 850

HD pickups would apply advanced friction reduction. Level 2 engine friction reduction is listed 

in Table VI-3, and costs are presented in the draft RIA Chapter 2.12. We expect some engines 

with this technology would be engine-certified and sold for use in vocational vehicles. We are 

projecting an overall effectiveness of 0.6 percent improvement over the GEM cycles for this 

technology, calculated using a per-vehicle effectiveness of 1.1 percent and a vocational vehicle 

adoption rate of 56 percent. We request comment on the merits of setting a SI-based vocational 

vehicle standard predicated on adoption of SI engine technologies.

(c) Technologies the Agencies Assessed but did not Use In Standard-Setting

(i) Aerodynamics 

The Argonne National lab work shows that aerodynamics has less of an impact on 

vocational vehicle energy losses than do engines or tires.309 Further, when a vehicle spends 

significant time at slower speeds, the disbenefit of the added weight of the aero devices 

diminishes the benefit obtained when driving at high speeds. In addition, the aerodynamic 

performance of a complete vehicle is significantly influenced by the body of the vehicle. As 

noted above, the agencies are not proposing to regulate body builders for the reasons discussed in 

Phase 1.

The NAS 2010 report estimated a one percent fuel efficiency improvement could be 

achieved from a full aerodynamic package on a box truck with an average speed of 30 mph.310 

Both from the NAS 2010 report and from experiences of EPA’s SmartWay team, the agencies 

expect the potential benefits of aerodynamics at an average speed of 60 mph would be 

diminished by 50 percent or more when average speeds are closer to 40 mph. The proposed 

Regional composite duty cycle in GEM for vocational vehicles (the test cycle with the most 

highway weighting) has a weighted average speed of 39 mph.

The 2014 SwRI technology assessment simulated a Class 6 box truck with a coefficient 

of aerodynamic drag that had been improved by 15 percent. Over transient test cycles, this 

produced a one percent fuel efficiency benefit, though this produced results of approximately

seven percent improvement over the 55 mph and eight percent over the 65 mph cycle. SwRI 

conducted coastdown testing to determine the baseline CdA of the truck, of 5.0.

311

 However, it 

is unknown what aerodynamic technologies could be applied to yield a 15 percent improvement 

in CdA. Using these simulation results and the proposed Regional cycle weightings of 22 

percent at 65 mph and 28 percent at 55 mph, the agencies estimate the fuel efficiency benefit of 

improving the CdA of a Class 6 box truck by 15 percent could be approximately four percent. 

This assumes no penalty for carrying the weight of the aerodynamic devices while operating 

under transient driving conditions.

 

309 See Argonne National Laboratory 2009 report, Note 279, above.

310 See Table 5-10 of the NAS 2010 report, Note 136.

311See NHTSA Technology Report #1, Note 293 , Appendix C. 
Page 350 of 850

Because we do not have information on specific technologies that could be applied to 

vocational vehicles to yield a 15 percent improvement in CdA, or their costs, we are not basing 

any of the proposed standards for vocational vehicles on aerodynamic improvements. 

Nonetheless, we are working with CARB to incorporate into GEM some data from testing that is 

being conducted by CARB through NREL. A test plan is underway to assess the fuel efficiency

benefit of three different devices to improve the aerodynamic performance of a Class 6 box truck

and one device on a Class 4 box truck. The agencies request comment on allowing a 

manufacturer to obtain an improved GEM result by certifying that a final vehicle configuration 

will closely match one of the configurations on which this testing was conducted, where the 

improvement would be based on installation of specific aerodynamic devices for which we have 

pre-defined effectiveness through this testing program. The amount of improvement would be 

set by EPA and NHTSA based on NREL’s test results. This credit provision would apply only to 

vocational vehicles certified over the Regional duty cycle. Manufacturers wishing to receive 

credit for other aerodynamic technologies or on other vehicle configurations would be able to 

seek credit for it as an off-cycle technology. See Section V.E, for a description of regulatory

flexibilities such as off-cycle technology credits.

A description of vehicles and aerodynamic technologies that could be eligible for this 

option, as well as a description of the testing conducted to obtain the assigned GEM 

improvements due to these technologies, can be found in a memorandum to the docket.

313

 The 

agencies seek comment on this potential approach to providing credits for aerodynamic aids to 

vocational box trucks.

(ii) Full Electric Trucks

Some heavy-duty vehicles can be powered exclusively by electric motors. Electric 

motors are efficient and able to produce high torque, giving e-trucks strong driving 

characteristics, particularly in stop-and-go or urban driving situations, and are well-suited for 

moving heavy loads. Electric motors also offer the ability to operate with very low noise, an 

advantage in certain applications. Currently, e-trucks have some disadvantages over 

conventional vehicles, primarily in cost, weight and range. Components are relatively expensive, 

and storing electricity using currently available technology is expensive, bulky, and heavy.

The West Coast Collaborative, a public-private partnership, has estimated the incremental 

costs for electric Class 3-6 trucks in the Los Angeles, CA, area.314 Compared to a conventional 

diesel, the WCC estimates a BEV system would cost between $70,000 and $90,000 more than a 

conventional diesel system. The CalHEAT Technology Roadmap includes an estimate that the 

incremental cost for a fully-electric medium- or heavy- duty vehicle would be between $50,000 

and $100,000. This roadmap report also presents several actions that must be taken by

 

313 See May 2015 memorandum to the docket titled Vocational Vehicle Aerodynamic Testing Program.

314 See http://westcoastcollaborative.org/files/sector-fleets/WCC-LA-BEVBusinessCase2011-08-15.pdf
Page 351 of 850

manufacturers and others, before heavy-duty e-trucks can reach what they call Stage 3 

Deployment.315 

Early adopters of electric drivetrain technology are medium-heavy-duty vocational 

vehicles that are not weight-limited and have drive cycles where they don’t need to go far from a 

central garage. Examples include Frito-Lay. CalHEAT has published results of a comprehensive 

performance evaluation of three battery electric truck models using information and data from 

in-use data collection, on road testing and chassis dynamometer testing.316 

Given the high costs and the developing nature of this technology, the agencies do not 

project fully electric vocational vehicles to be widely commercially available in the time frame 

of the proposed rules. For this reason, the agencies have not based the proposed Phase 2 

standards on adoption of full-electric vocational vehicles. To the extent this technology is able to 

be brought to market in the time frame of the Phase 2 program, there is currently a certification 

path for these chassis from Phase 1, as described in Section V.E and in EPA’s regulations at 40 

CFR 1037.150 and NHTSA’s regulations at 49 CFR 535.8.

(iii) Electrified Accessories

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. Electrification of accessories can individually

improve fuel consumption, regardless of whether the drivetrain is a strong hybrid. 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.317

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 

 

315 Silver, Fred, and Brotherton, Tom. (CalHEAT) Research and Market Transformation Roadmap to 2020 for 

Medium- and Heavy-Duty Trucks. California Energy Commission, June 2013.

316 Gallo, Jean-Baptiste, and Jasna Tomic (CalHEAT). 2013. Battery Electric Parcel Delivery Truck Testing and 

Demonstration. California Energy Commission.

317 TIAX 2009, Note 137, pp. 3-5
Page 352 of 850

turned. EPS is an enabler for all vehicle hybridization technologies since it provides power 

steering when the engine is off. EPS is feasible for most vehicles with a standard 12V system. 

Some heavier vehicles may require a higher voltage system which may add cost and complexity.

The agencies are projecting that some electrified accessories will be necessary as part of 

the development of stop-start idle reduction systems for vocational vehicles. However, the 

agencies have not developed a pre-defined credit-generating option for manufacturers to directly 

receive credit in GEM for electrified accessories on vocational vehicles. Manufacturers wishing 

to conduct independent testing may apply for off-cycle credits derived from electrified 

accessories. 

(iv) E-PTO

There are products available today that can provide auxiliary power, usually electric, to a 

vehicle that needs to work in PTO mode for an extended time, to avoid idling the main engine. 

There are different designs of electrified PTO systems on the market today. Some designs have 

auxiliary power sources, typically batteries, with sufficient energy storage to power an onboard 

tool or device for a short period of time, and are intended to be recharged during the workday by

operating the main engine, either while driving between work sites, or by idling the engine until 

a sufficient state of charge is reached that the engine may shut off. Other designs have sufficient 

energy storage to power an onboard tool or device for many hours, and are intended to be 

recharged as a plug-in hybrid at a home garage. The agencies are proposing to continue the 

hybrid-PTO test option that was available in Phase 1, with a few revisions. See the proposed 

regulations at 40 CFR 1037.540. The current test procedure is a charge-sustaining procedure, 

meaning the test is not complete until the energy storage system is depleted and brought back to 

its original state of charge. The agencies request comment and data relating to the population 

and energy storage capacity of plug-in e-PTO systems, for which a charge-depleting test cycle 

may be more appropriate. For the reasons described above in Section V.C.1.a.iv, the agencies 

are not basing the proposed vocational vehicle standards on use of electrified PTO or hybrid 

PTO technology. Manufacturers wishing to conduct testing as specified may apply for off-cycle 

credits derived from e-PTO or hybrid PTO technologies.

(2) Projected Vehicle Technology Package Effectiveness and Cost

(a) Baseline Vocational Engine and Vehicle Performance

The proposed baseline vocational vehicle configurations for each of the nine proposed 

regulatory subcategories are described in draft RIA Chapter 2.9 and Chapter 4.4. The agencies 

propose to set the baseline rolling resistance coefficient for the 2017 vocational vehicle fleet at 

7.7 kg/metric ton, which assumes 100 percent of tires meet the Phase 1 standard. 

In the agencies’ proposed baseline configurations, we include torque converter 

automatics with five forward gears in eight of the nine subcategories. In the Regional HHD 

subcategory, the baseline includes a manual transmission with ten forward gears. No additional 

vehicle-level efficiency-improving technology is included in the baseline vehicles, nor in the 

agencies’ analyses for the no-action reference case. Specifically, we have assumed zero 

adoption rates for other types of transmissions, increased numbers of gears, idle reduction, and 
Page 353 of 850

technologies other than Phase 1 compliant LRR tires in both the nominally flat baseline and the 

dynamic baseline reference cases. Technology adoption rates for Alternative 1a (nominally flat 

baseline) can be found in the draft RIA Chapter 2.12. Chapter 2.12.8 presents the adoption rates 

for tires on vocational vehicles with different levels of rolling resistance, including the 100 

percent adoption rate of tires with Level 1 CRR in the reference case and in model years 

preceding Phase 2. In this manner, we have defined a reference vocational vehicle fleet that 

meets the Phase 1 standards and includes reasonable representations of vocational vehicle 

technology and configurations. Details of the vehicle configurations, including reasons why they 

are reasonably included as baseline technologies, are discussed in the draft RIA Chapter 2.9.

The agencies note that the baseline performance derived for the proposed rules varies 

between regulatory subcategories – as noted above, this is the reason the agencies are proposing 

the further subcategories. The range of performance at baseline is due to the range of attributes 

and modeling parameters, such as transmission characteristics, final drive ratio, and vehicle 

weight, which were selected to represent a range of performance across this diverse segment. 

The agencies request comment on whether the proposed configurations adequately represent a 

reasonable range of vocational chassis configurations likely to be manufactured in the 

implementation years of the Phase 2 program. We especially are interested in comments 

regarding the following driveline parameters: transmission gear ratios, axle ratios, and tire radii. 

The baseline engine fuel consumption represents improvements beyond currently

available engines to achieve the efficiency of what the agencies believe would be a 2017 model 

year diesel engine, as described in the draft RIA Chapter 2. Using the values for compressionignition engines, the baseline performance of vocational vehicles is shown in Table V-11. 

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. Because of these differences, the GEM simulation of baseline vocational CI engines 

includes four engines - one for LHD, one for MHD, and two for HHD. Detailed descriptions can 

be seen in Chapter 4 of the draft RIA. These four engine models have been employed in setting 

the vocational vehicle baselines, as described in the draft RIA Chapter 2.9. 
Page 354 of 850

Table V-11 Baseline Vocational Vehicle Performance with CI Engines

Baseline Emissions Performance in CO2 gram/ton-mile

Duty Cycle Light Heavy-Duty 

Class 2b-5

Medium Heavy-Duty 

Class 6-7

Heavy Heavy-Duty

Class 8

Urban 316 201 212

Multi-Purpose 325 203 214

Regional 339 199 203

Baseline Fuel Efficiency Performance in gallon per 1,000 ton-mile

Duty Cycle Light Heavy-Duty 

Class 2b-5

Medium Heavy-Duty 

Class 6-7

Heavy Heavy-Duty

Class 8

Urban 31.0413 19.7446 20.8251

Multi-Purpose 31.9253 19.9411 21.0216

Regional 33.3006 19.5481 19.9411

The agencies intend to develop a model in GEM of a MY 2016-compliant gasoline 

engine, but we have been unable to obtain sufficient information to complete this process. The 

agencies request comments on the process for mapping gasoline engines for simulation purposes, 

as well as information about the power rating and displacement that should be considered as a 

baseline SI engine for vocational vehicle standard-setting purposes. In lieu of a SI engine map, 

the agencies have applied a correction factor to the GEM CI vocational simulation results, to 

approximate the baseline performance of a SI-powered vocational vehicle. The SI-powered

vocational vehicle baseline performance shown in Table V-12 was calculated from applying an 

adjustment factor to the respective CI-powered vocational vehicle baseline values. This CI to SI 

baseline adjustment factor is derived from the Phase 1 HD pickup and van stringency curves, as 

described in the draft RIA Chapter 2.9.1. The correction factor approach is not the agencies’ 

preferred approach, as it has many drawbacks. One key drawback with this approach is that it 

does not account for the fact that SI engines operate very differently than CI engines at idle. Our 

current model includes information on CI engine idle performance, and assumes transmissions 

and torque converters appropriate for CI engines. We expect these driveline parameters would 

be very different for SI powered vehicles, which would affect performance over all the GEM 

duty cycles.

The baseline performance levels for HHD vocational vehicles powered by SI engines 

were derived using the same procedures described above for the MHD and LHD vehicles, 

adjusting the performance of the HHD CI powered vocational vehicles by the same degree as for 

the other vehicles. However, we expect that any gasoline Class 8 vocational vehicle would be 

powered by a MHD SI engine, as there are no HHD gasoline engines on the market. Further, we 

expect that if we were to develop an engine map for use in simulating heavier SI vocational 

vehicles in GEM, we could establish a more representative baseline performance level by

calculating the work done by the MHD engine to move the heavier vehicle over the test cycles. 

The agencies request comments on the merits of developing separate baseline levels and 

numerical standards for HHD vocational vehicles powered by SI engines, including any benefits 

that could be obtained by addressing this unlikely occurrence and other ways in which the 

agencies could avoid the instance of an orphaned SI vocational vehicle. Commenters who favor 

separate numerical standards are encouraged to submit information related to appropriate default 
Page 355 of 850

vehicle characteristics such as weight and payload. Depending on comments, the agencies could 

choose to require all Class 8 vocational vehicles to certify to the standards for CI powered HHD 

vocational vehicles, or we could require SI powered Class 8 vocational vehicles to certify to the 

MHD standards for SI vocational vehicles. 

Table V-12 Baseline Vocational Vehicle Performance with SI Engines

Baseline Emissions Performance in CO2 gram/ton-mile

Duty Cycle Light Heavy-Duty 

Class 2b-5

Medium Heavy-Duty 

Class 6-7

Heavy Heavy-Duty

Class 8

Urban 334 213 224

Multi-Purpose 344 215 226

Regional 358 211 214

Baseline Fuel Efficiency Performance in gallon per 1,000 ton-mile

Duty Cycle Light Heavy-Duty 

Class 2b-5

Medium Heavy-Duty 

Class 6-7

Heavy Heavy-Duty

Class 8

Urban 37.5830 23.9676 25.2054

Multi-Purpose 38.7082 24.1926 25.4304

Regional 40.2836 23.7425 24.0801

(b) Technology Packages for Derivation of Proposed Standards

Prior to developing the numerical values for the proposed standards, the agencies 

projected the mix of new technologies and technology improvements that would be feasible 

within the proposed lead time. We note that for some technologies, the adoption rates and 

effectiveness may be very similar across subcategories. However, for other technologies, either 

the adoption rate, effectiveness, or both differ across subcategories. The standards being 

proposed reflect the technology projected for each service class. Where a technology performs 

differently over different test cycles, these differences are reflected to some extent in the 

derivation of the stringency of the proposed standard. However, the proposed standard 

stringency does reflect, to some extent, the ability of manufacturers to utilize credits. For 

example, we project that hybrid vehicles would generally be certified in the Urban subcategory 

and would generate emission credits that would most likely be used in the other subcategories 

within the weight class group.

318

 

As part of the derivation of the numerical standards, we performed a benchmarking 

analysis to inform our development of standards that would have roughly equivalent stringency 

among the duty-cycle-based subcategories within each weight class group. To do this, the 

agencies assessed the performance of broadly applicable technologies, such as low rolling 

resistance tires, on each of the selected baseline vehicles over each of the duty cycles. We then 

 

318 See averaging sets at 40 CFR 1037.740.
Page 356 of 850

evaluated how much improvement could be achieved over the various duty cycles for a vehicle 

that incorporated all the broadly applicable technologies, but which did not include a hybrid 

powertrain. We simulated neutral idle for benchmarked vehicles for MY 2021 and MY 2024, and 

simulated stop-start idle reduction on the benchmarked MY 2027 vehicles. From this, we 

learned that a vehicle with neutral idle and a deeply integrated conventional powertrain, with 

moderately low rolling resistance tires and some weight reduction could easily meet the 

proposed standards in the early implementation years of the program, in any weight class or duty 

cycle. We also learned how the effectiveness of tire rolling resistance and weight reduction vary

in GEM (i.e. and therefore likely in actual operation) across the different subcategories. We also 

found that a vehicle with a deeply integrated conventional powertrain, tires with even lower 

CRR, some weight reduction, and stop-start idle reduction could achieve the MY 2027 proposed 

standards. However, our technology feasibility does not presume that 100 percent of vocational 

vehicles can reasonably apply deep powertrain integration, nor do we project 100 percent 

adoption of LRR tires or weight reduction.

The technologies assumed for the benchmarked vehicles are summarized in Table V-13, 

Table V-14, and Table V-15. Note that the agencies are not projecting that these are the vehicles 

that would actually be produced. Rather, these theoretical vehicles are being evaluated to 

compare the relative stringency of the standards for each subcategory.

Table V-13 GEM Inputs for Benchmarked MY 2021 Vocational Vehicles

Class 2b-5 Class 6-7 Class 8

Urban MultiPurposeRegional Urban MultiPurposeRegional Urban MultiPurposeRegional

Transmission

100% Deep Transmission Integration for 7% Urban, 6% Multipurpose, 5% Regional

5s AT 5s AT 5s AT 5s AT 5s AT 5s AT 5s AT 5s AT 10s AMT

CI Enginea

2021 MY 7L, 200 hp Engine 2021 MY 7L, 270 hp Engine 2021 MY 11L, 345 

hp Engine

2021 MY 

15L 455hp 

Engine

100% Idle Reduction = Neutral Idle

100% improved axle lubrication: 0.5% 

100% Steer Tires with CRR 6.9 kg/metric ton

100% Drive Tires with CRR 7.3 kg/metric ton

Weight Reduction 200 lb

Note:

a

SI engines were not simulated in GEM
Page 357 of 850

Table V-14 GEM Inputs for Benchmarked MY 2024 Vocational Vehicles

Class 2b-5 Class 6-7 Class 8

Urban MultiPurposeRegional Urban MultiPurposeRegional Urban MultiPurposeRegional

Transmission

100% Deep Transmission Integration for 7% Urban, 6% Multipurpose, 5% Regional

5s AT 5s AT 5s AT 5s AT 5s AT 5s AT 5s AT 5s AT 10s AMT

CI Enginea

2024 MY 7L, 200 hp Engine 2024 MY 7L, 270 hp Engine 2024 MY 11L, 345 

hp Engine

2024 MY 

15L 455hp 

Engine

100% Idle Reduction = Neutral Idle

100% improved axle lubrication: 0.5% 

100% Steer Tires with CRR 6.7 kg/metric ton

100% Drive Tires with CRR 7.1 kg/metric ton

Weight Reduction 200 lb

Note:

a

SI engines were not simulated in GEM

Table V-15 GEM Inputs for Benchmarked MY 2027 Vocational Vehicles

Class 2b-5 Class 6-7 Class 8

Urban MultiPurposeRegional Urban MultiPurposeRegional Urban MultiPurposeRegional

Transmission

100% Deep Transmission Integration for 7% Urban, 6% Multipurpose, 5% Regional

5s AT 5s AT 5s AT 5s AT 5s AT 5s AT 5s AT 5s AT 10s AMT

CI Enginea

2027 MY 7L, 200 hp Engine 2027 MY 7L, 270 hp Engine 2027 MY 11L, 345 

hp Engine

2027 MY 

15L 455hp 

Engine

100% Idle Reduction = Stop-Start

100% Steer Tires with CRR 6.4 kg/metric ton

100% Drive Tires with CRR 7.0 kg/metric ton

Weight Reduction 200 lb

Note:

a

SI engines were not simulated in GEM

Next we identified the best performing baseline vehicle in each weight class group (one 

for HHD, one for MHD and one for LHD) and normalized the baseline GEM results to the 

performance of that vehicle. A complete description of this normalization process is found in the 

draft RIA Chapter 2. We then applied our actual projected technology adoption rates, including 

hybrid powertrains and stop-start idle reduction, to normalized-benchmarked vehicles in each of 

the nine subcategories. The proposed standards then were calculated by multiplying the 

normalized baseline vehicle GEM result by an average percent improvement for each weight 

class group. For example, the GEM results from applying the projected technology mix for MY 

2021 MHD CI vocational vehicles were a 5 percent improvement in the Regional MHD 

subcategory, 7 percent improvement in the MHD Multipurpose subcategory, and 8 percent 

improvement in the MHD Urban subcategory. To achieve standards with equivalent stringency, 
Page 358 of 850

we multiplied each normalized baseline vehicle’s GEM performance by the numerical average of 

those simulated improvements, 6.6 percent. Without comparable stringency across the 

subcategories, manufacturers could have an incentive to select a subcategory strategically to 

have a less stringent standard, rather than to certify vehicles in the subcategory that best matches 

the vehicles’ expected use patterns. By setting the standards at the same percent reduction from 

each weight class group of normalized-benchmarked vehicles, we would expect to minimize any

incentive for a manufacturer to certify a vocational vehicle in an inappropriate subcategory. 

We request comment on using this approach to normalize the standards. Commenters are 

encouraged to address both the approach in general and the specific technology assumed for the 

benchmark vehicles.

We are aware that in this approach, some of the projected technology packages would not 

provide a direct path to compliance for manufacturers, such as in the example above of the MHD 

Regional vehicle. Using the technologies adopted at projected rates, it would fall short of the 

standard by 1.5 percent. The agencies believe that the Phase 2 program has enough regulatory

flexibility (averaging, banking, and trading provisions in particular) to enable such a vehicle to 

be certified. 

In the package descriptions that follow, individual technology costs are not presented, 

rather these can be found in the draft RIA Chapter 2.9 and 2.12. Section V. C. (2) (d) includes 

the costs estimated for packages of technologies the agencies project would enable vocational 

vehicles to meet the proposed Phase 2 standards.

(i) Transmission Packages

The agencies project that 30 percent of vocational vehicles would have one or more of 

the transmission technologies identified above in this section applied by MY 2021, increasing to 

nearly 60 percent by MY 2024 and over 80 percent by MY 2027. Most of this increase is due to 

a projected increase in adoption of technologies that represent deep driveline integration. The 

agencies project an adoption rate of 15 percent in MY 2021 and 30 percent in MY 2024 for 

manufacturers using the powertrain test to be recognized for non-hardware upgrades such as gear 

efficiencies, shift strategies, and torque converter lockups, as well as other technologies that 

enable driveline optimization. Due to the relatively high efficiency gains available from 

driveline optimization for relatively low costs, the agencies are projecting a 70 percent

application rate of driveline optimization by MY 2027 across all subcategories. We do not have 

information about the extent to which integration may be deterred by barriers to informationsharing between component suppliers. Therefore we are projecting that major manufacturers 

would work to overcome these barriers, integrate and optimize their drivelines, and use the 

powertrain test on all eligible configurations, while smaller manufacturers may not adopt these

technologies at all, or not to a degree that they would find value in this optional test procedure.

For the technology of adding two gears, we are predicating the proposed MY 2021 

standard on a five percent adoption rate, except zero in the HHD Regional subcategory, which is 

modeled with a 10-speed transmission. This adoption rate is projected to essentially remain at 

this level throughout the program, with an increase to ten percent only for two subcategories 

(Regional LHD and MHD) in MY 2027. This is because the manufacturers most likely to 
Page 359 of 850

develop 8-speed transmissions are those that are also developing transmissions for HD pickups 

and vans, and the GEM-certified vocational market share among those manufacturers is 

relatively small. 

The HHD Regional subcategory is the only one where we assume a manual transmission

in the baseline configuration. For these vehicles, the agencies project upgrades to electronic 

transmissions such as either AMT, DCT, or automatic, at collective adoption rates of 51 percent

in MY 2021, 68 percent in MY 2024, and five percent in MY 2027. The decrease in MY 2027 

reflects a projection that a greater number of deeply integrated HHD powertrains would be used 

by MY 2027 (one consequence being that fewer HHD powertrains would be directly simulated 

in GEM in that year). The larger numbers in the phase-in years reflect powertrains that have 

been automated or electrified but not deeply integrated. The agencies have been careful to 

account for the cost of both electrifying and deeply integrating the MY 2027 powertrains. In 

draft RIA Chapter 11, the technology adoption rates for the HHD Regional subcategory

presented in Table 11-42, Table 11-45, and Table 11-48 account for the assumption that a 

manual transmission cannot be deeply integrated, so there must also be an automation upgrade. 

These tables are inputs to the agencies’ cost analysis, thus the costs of both upgrading and 

integrating HHD powertrains are included. The adoption rates of the upgraded but not integrated 

transmission architectures represent a projection of three percent of all vocational vehicles in 

MY 2021 and four percent in MY 2024. This is based on an estimate that seven percent of the 

vocational vehicles would be in the HHD Regional subcategory. For more information about the 

assumptions that were made about the populations of vehicles in different subcategories, see the 

agencies’ inventory estimates in draft RIA Chapter 5. 

In the eight subcategories in which automatic transmissions are the base technology, the 

agencies project that five percent would upgrade to a dual clutch transmission in MY 2021. This 

projection increases to 15 percent in MY 2024 and decreases in MY 2027 to ten percent for two 

subcategories (Regional LHD and MHD) and five percent for the remaining 6 subcategories. 

The low projected adoption rates of DCT reflect the fact that this is a relatively new technology

for the heavy-duty sector, and it is likely that broader market acceptance would be achieved once 

fleets have gained experience with the technology. Similar to the pattern described for the HHD 

Regional subcategory, the decrease in MY 2027 reflects a projection of greater use of deeply 

integrated powertrains.

In setting the proposed standard stringency, we have projected that hybrids on vehicles 

certified in the Multipurpose subcategories would achieve on average 22 percent improvement, 

and those in the Urban subcategories would see a 25 percent improvement. We have also 

projected zero hybrid adoption rate by vehicles in the Regional subcategories, expecting that the 

benefit of hybrids for those vehicles would be too low to merit use of that type of technology. 

However, there is no fixed hybrid value assigned in GEM and the actual improvement over the 

applicable test cycle would be determined by powertrain testing. By the full implementation 

year of MY 2027, the agencies are projecting an overall vocational vehicle adoption rate of ten 

percent hybrids, which we estimate would be 18 percent of vehicles certified in the MultiPurpose and Urban subcategories. We are projecting a low adoption rate in the early years of the 

Phase 2 program, just four percent in these subcategories in MY 2021, and seven percent in MY 

2024 for vehicles certified in the Multi-Purpose and Urban subcategories. Based on our 
Page 360 of 850

assumptions about the populations of vehicles in different subcategories, these hybrid adoption 

rates are about two percent overall in MY 2021 and four percent overall in MY 2024.

Considering the combination of the above technologies and adoption rates, we project the 

CO2 and fuel efficiency improvements for all transmission upgrades to be approximately seven

percent on a fleet basis by MY 2027. One subcategory in which we are projecting a very large 

advanced transmission adoption rate is the HHD Regional subcategory, in which we are 

projecting 75 percent of the transmissions would be either automated or automatic (upgraded 

from a manual) with 70 percent of those also being deeply integrated by MY 2027. By

comparison, the agencies are projecting that HHD day cab tractors would have 90 percent 

adoption of automated or automatic transmissions by MY 2027. Although we are not prepared 

to predict what fraction of these would be upgraded in the absence of Phase 2, the draft RIA 

Chapter 2.9 explains why the agencies are confident that durable transmissions will be widely

available in the Phase 2 time frame to support manufacture of HHD vocational vehicles.

If the above technologies do not reach the expected level of market adoption, the 

vocational vehicle Phase 2 program has several other technology options that manufacturers 

could choose to meet the proposed standards.

(ii) Axle Packages

The agencies project that 75 percent of vocational vehicles in all subcategories would 

adopt advanced axle lubricant formulations in all implementation years of the Phase 2 program.

Fuel efficient lubricant formulations are widespread across the heavy-duty market, though 

advanced synthetic formulations are currently less popular.319 Axle lubricants with improved 

viscosity and efficiency-enhancing performance are projected to be widely adopted by 

manufacturers in the time frame of Phase 2. Such formulations are commercially available and 

the agencies see no reason why they could not be feasible for most vehicles. Nonetheless, we 

have refrained from projecting full adoption of this technology. The agencies do not have 

specific information regarding reasons why axle manufacturers may specify a specific type of 

lubricant over another, and whether advanced lubricant formulations may not be recommended 

in all cases. The agencies request comment on information regarding any vocational vehicle 

applications for which use of advanced lubricants would not be feasible.

The agencies estimate that 45 percent of HHD Regional vocational vehicles would adopt 

either full time or part time 6x2 axle technology in MY 2021. This technology is most likely to 

be applied to Class 8 vocational vehicles (with 2 rear axles) that are designed for frequent 

highway trips. The agencies project a slightly higher adoption rate of 60 percent combined for 

both full and part time 6x2 axle technologies in MY 2024 and MY 2027. Based on our estimates 

of vehicle populations, this is about four percent of all vocational vehicles.

 

319

 Based on conversations with axle suppliers.
Page 361 of 850

(iii) Tire Packages

The agencies estimate that the per-vehicle average level of rolling resistance from 

vocational vehicle tires could be reduced by 11 percent by full implementation of the Phase 2 

program in MY 2027, based on the tire development achievements expected over the next 

decade. This is estimated by weighting the projected improvements of steer tires and drive tires 

using an assumed axle load distribution of 30 percent on the steer tires and 70 percent on the 

drive tires, as explained in the draft RIA Chapter 2.9. The projected adoption rates and expected 

improvements in CRR are presented in Table V-16. By applying the assumed axle load 

distribution, the average vehicle CRR improvements projected for the proposed MY 2021 

standards would be four percent, which we project would achieve up to one percent reduction in 

fuel use and CO2 emissions, depending on the vehicle subcategory. Using that same method, the 

agencies estimate the average vehicle CRR in MY 2024 would be seven percent, yielding 

reductions in fuel use and CO2 emissions of between one and two percent, depending on the 

vehicle subcategory. 

The agencies understand that the vocational vehicle segment has access to a large variety 

of tires, including some that are designed for tractors, some that are designed for HD pickups and 

vans, and some with multiple use designations. In spite of the likely availability of LRR tires 

during the Phase 2 program, the projected adoption rates are intended to be conservative. The 

agencies believe that these tire packages recognize the variety of tire purposes and performance 

levels in the vocational vehicle market, and maintain choices for manufacturers to use the most 

efficient tires (i.e. those with least rolling resistance) only where it makes sense given these 

vehicles’ differing purposes and applications. 
Page 362 of 850

Table V-16 Projected LRR Tire Adoption Rates

Tire 

Position

Level of Rolling 

Resistance

MY 2021 Adoption 

Rate

MY 2024 

Adoption Rate

MY 2027 

Adoption Rate

Drive Baseline CRR (7.7) 50 20 10

Steer Baseline CRR (7.7) 20 10 0

Drive 5% Lower CRR 

(7.3)

50 50 25

Steer 10% Lower CRR 

(6.9)

80 30 20

Drive 10% Lower CRR 

(6.9)

0 30 50

Steer 15% Lower CRR 

(6.5)

0 60 30

Drive 15% Lower CRR 

(6.5)

0 0 15

Steer 20% Lower CRR 

(6.2)

0 0 50

Drive Average 

Improvement in 

CRR

3% 6% 9%

Steer Average 

Improvement in 

CRR

8% 12% 17%

For comparison purposes, the reader may note that these levels of tire CRR generally 

correspond with levels of tire CRR projected for tractors built for the Phase 1 standards. For 

example, the baseline level CRR for vocational tires is very similar to the baseline tractor steer 

tire CRR. Vocational vehicle tires with 10 percent better CRR have a similar CRR level as 

tractor tires of Drive Level 1. Vocational vehicle tires with 15 percent better CRR have a similar 

CRR level as tractor tires of Steer Level 1. Vocational vehicle tires with 20 percent better CRR 

have a similar CRR level as tractor tires of Drive Level 2, as described in Section III.D.2.

(iv) Idle Reduction Packages

In this proposal, we are projecting a progression of idle reduction technology

development that begins with 70 percent adoption rate of neutral idle for the MY 2021 standards, 

which by MY 2027 is replaced by a 70 percent adoption rate of stop-start idle reduction 

technology. Although it is possible that a vehicle could have both neutral idle and stop-start, we 

are only considering emissions reductions for vehicles with one or the other of these 

technologies. Also, as the program phases in, we do not see a reduction in the projected adoption 

rate of neutral idle to be a concern in terms of stranded investment, because it is a very low cost 

technology that could be an enabler for stop-start systems in some cases. 

We are not projecting any adoption of neutral idle for the HHD Regional subcategory,

because any vehicle with a manual transmission must shift to neutral when stopped to avoid 

stalling the engine, so that vehicles in the HHD Regional subcategory would already essentially
Page 363 of 850

be idling in neutral and no additional technology would be needed to achieve this. A similar case 

can be made for any vocational vehicle with an automated manual transmission, since these 

share inherently similar architectures with manuals. The agencies are not projecting an adoption 

rate of 85 percent neutral idle until MY 2024, because it may take some additional development 

time to apply this technology to high-torque automatic transmissions designed for the largest 

vocational vehicles. Based on stakeholder input, the designs needed to avoid an uncomfortable 

re-engagement bump when returning to drive from neutral may require some engineering 

development time as well as some work to enable two-way communication between engines and 

transmissions.

We are projecting a five percent adoption rate of stop-start in the six MHD and LHD 

subcategories for MY 2021 and zero for the HHD vehicles, because this technology is still 

developing for vocational vehicles and is most likely to be feasible in the early years of Phase 2 

for vehicles with lower power demands and lower engine inertia. Stopping a heavy-duty engine 

is not challenging. The real challenge is designing a robust system that can deliver multiple 

smooth restarts daily without loss of function while the engine is off. Many current light-duty 

products offer this feature, and some heavy-duty manufacturers are exploring this.320 The 

agencies are projecting an adoption rate of 15 percent stop-start across all subcategories in the 

intermediate year of MY 2024. The agencies are projecting this technology to have a relatively 

high adoption rate (70 percent as stated above) by MY 2027 because we see it being technically

feasible on the majority of vocational vehicles, and especially effective on those with the most 

time at idle in their workday operation. Although we are not prepared to predict what fraction of 

vehicles would adopt stop-start in the absence of Phase 2, the draft RIA Chapter 2.9 explains 

why the agencies are confident that this technology, which is on the entry-level side of the hybrid 

and electrification spectrum, will be widely available in the Phase 2 time frame. 

Based on these projected adoption rates and the effectiveness values described above in 

this section, we expect overall GHG and fuel consumption reductions from workday idle on 

vocational vehicles to be approximately three percent in MY 2027.

(v) Weight Reduction Packages

As described in the draft RIA Chapter 2.12, weight reduction is a relatively costly

technology, at approximately $3 to $4 per pound for a 200-lb package. Even so, for vehicles in 

service classes where dense, heavy loads are frequently carried, weight reduction can translate 

directly to additional payload. The agencies project weight reduction would most likely be used 

for vocational vehicles in the refuse and construction service classes, as well as some regional 

delivery vehicles. The agencies are predicating the proposed standards on an adoption rate of 

 

320 See Ford announcement December 2013, 

https://media.ford.com/content/fordmedia/fna/us/en/news/2013/12/12/70-percent-of-ford-lineup-to-have-auto-startstop-by-2017--fuel-.html. See also Allison-Cummins announcement July 2014, 

http://www.oemoffhighway.com/press_release/12000208/allison-stopstart?utm_source=OOH+Industry+News+eNL&utm_medium=email&utm_campaign=RCL140723006
Page 364 of 850

five to eight percent, depending on the subcategory, in MY 2027, with slightly lower adoption 

rates in MY 2021 and MY 2024.

For this technology package, NHTSA and EPA project manufacturers would use material 

substitution in the amount of 200 pounds. An example of how this weight could be reduced 

would be a complete set of aluminum wheels for a Class 8 vocational vehicle, or an aluminum 

transmission case plus high strength steel wheels, frame rails, and suspension brackets on a 

MHD or LHD vocational vehicle. The agencies have limited information about how popular the 

use of aluminum components is in the vocational vehicle sector. We request comments with 

information on whether any lightweight vocational vehicle components are in such widespread 

use that we should exclude them from the list of components for which a GEM improvement 

value would be available. 

(c) GEM Inputs for Derivation of Proposed Vocational Vehicle Standards

To derive the stringency of the proposed vocational vehicle standards, the agencies

developed a suite of fuel consumption maps for use with the GEM: one set of maps that 

represent engines meeting the proposed MY 2021 vocational diesel engine standards, a second 

set of maps representing engines meeting the proposed MY 2024 vocational diesel engine

standards, and a third set of maps representing engines meeting the proposed MY 2027 

vocational diesel engine standards.

321

 By incorporating the engine technology packages 

projected to be adopted to meet the proposed Phase 2 vocational CI engine standards, the 

agencies employed GEM engine models in deriving the stringency of the proposed Phase 2 CIpowered vocational vehicle standards. As noted above, because the agencies did not have 

enough information to develop a robust GEM-based gasoline engine fuel map, the stringency of 

the proposed SI-powered vocational vehicle standards is derived as an adjustment from the CIpowered vocational vehicle standards. See the draft RIA Chapter 2.9 for more details about this 

adjustment process.

Depending on the particular technology, either the effectiveness was assigned by the 

agencies using an accepted average value, or the GEM tool was used to assess the proposed 

technology effectiveness, as discussed above. The agencies derived a scenario vehicle for each 

subcategory using the adoption rate and assigned or modeled improvement values of 

transmission, axle, and idle reduction technologies. For example, the MY 2021 CRR values for 

each subcategory scenario case were derived as follows: for steer tires - 20 percent times 7.7 plus 

80 percent times 6.9 yields an average CRR of 7.1 kg/metric ton; and for drive tires - 50 percent 

times 7.7 plus 50 percent times 7.3 yields an average CRR of 7.5 kg/metric ton. Similar 

calculations were done for weight reduction, transmission improvements, and axle 

improvements. The set of tire CRR, idle reduction, weight reduction, engine and transmission 

input parameters that was modeled in GEM in support of the proposed MY 2021 vocational 

vehicle standards is shown in Table V-17. The agencies derived the level of the proposed MY 

2024 standards by using the tire, weight reduction, engine and transmission GEM inputs shown 

 

321 See Section II.D.2 of this preamble for the derivation of the engine standards.
Page 365 of 850

in Table V-18, below. The agencies derived the level of the proposed MY 2027 standards by 

using the tire, weight reduction, engine and transmission GEM inputs shown in Table V-19, 

below. As post-processing, the respective adoption rates and assigned improvement values of 

transmission, axle, and idle reduction technologies were calculated for each subcategory.

The agencies have not directly transferred the GEM results from these inputs as the 

proposed standards. Rather, the proposed standards are the result of the normalizing and 

benchmarking analysis described above. The proposed standards are presented in Table V-4

through Table V-9. Additional detail is provided in the RIA Chapter 2.9.

Table V-17 GEM Inputs Used to Derive Proposed MY 2021 Vocational Vehicle Standards

Class 2b-5 Class 6-7 Class 8

Urban MultiPurposeRegional Urban MultiPurposeRegional Urban MultiPurposeRegional

CI Enginea

2021 MY 7L, 200 hp Engine 2021 MY 7L, 270 hp Engine 2021 MY 11L, 345 

hp Engine

2021 MY 

15L 455hp 

Engine

Transmission (improvement factor)

0.023 0.021 0.008 0.023 0.021 0.009 0.023 0.022 0.022

Axle (improvement factor)

0.004 0.004 0.004 0.004 0.004 0.004 0.004 0.004 0.012

Stop-Start (adoption rate)

5% 5% 5% 5% 5% 5% 0% 0% 0%

Neutral Idle (adoption rate)

70% 70% 70% 70% 70% 70% 70% 70% 0%

Steer Tires (CRR kg/metric ton)

7.1 7.1 7.1 7.1 7.1 7.1 7.1 7.1 7.1

Drive Tires (CRR kg/metric ton)

7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5

Weight Reduction (lb)

8 8 14 8 8 12 8 8 10

Note:

a

SI engines were not simulated in GEM, rather a gas/diesel adjustment factor was applied to the results
Page 366 of 850

Table V-18 GEM Inputs Used to Derive Proposed MY 2024 Vocational Vehicle Standards

Class 2b-5 Class 6-7 Class 8

Urban MultiPurposeRegional Urban MultiPurposeRegional Urban MultiPurposeRegional

CI Enginea

2024 MY 7L, 200 hp Engine 2024 MY 7L, 270 hp Engine 2024 MY 11L, 345 

hp Engine

2024 MY 

15L 455hp 

Engine

Transmission (improvement factor)

0.045 0.04 0.017 0.045 0.041 0.018 0.045 0.042 0.035

Axle (improvement factor)

0.004 0.004 0.004 0.004 0.004 0.004 0.004 0.004 0.014

Stop-Start (adoption rate)

15% 15% 15% 15% 15% 15% 15% 15% 15%

Neutral Idle (adoption rate)

85% 85% 85% 85% 85% 85% 85% 85% 0%

Steer Tires (CRR kg/metric ton)

6.8 6.8 6.8 6.8 6.8 6.8 6.8 6.8 6.8

Drive Tires (CRR kg/metric ton)

7.3 7.3 7.3 7.3 7.3 7.3 7.3 7.3 7.3

Weight Reduction (lb)

8 8 14 8 8 12 8 8 10

Note:

a

SI engines were not simulated in GEM, rather a gas/diesel adjustment factor was applied to the results
Page 367 of 850

Table V-19 GEM Inputs Used to Derive Proposed MY 2027 Vocational Vehicle Standards

Class 2b-5 Class 6-7 Class 8

Urban MultiPurposeRegional Urban MultiPurposeRegional Urban MultiPurposeRegional

CI Enginea

2027 MY 7L, 200 hp Engine 2027 MY 7L, 270 hp Engine 2027 MY 11L, 345 

hp Engine

2027 MY 

15L 455hp 

Engine

Transmission (improvement factor)

0.096 0.085 0.034 0.096 0.088 0.037 0.097 0.089 0.036

Axle (improvement factor)

0.004 0.004 0.004 0.004 0.004 0.004 0.004 0.004 0.014

Stop-Start (adoption rate)

75% 70% 70% 75% 70% 70% 70% 70% 70%

Neutral Idle (adoption rate)

25% 30% 30% 25% 30% 30% 30% 30% 0%

Steer Tires (CRR kg/metric ton)

6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4 6.4

Drive Tires (CRR kg/metric ton)

7.0 7.0 7.0 7.0 7.0 7.0 7.0 7.0 7.0

Weight Reduction (lb)

10 10 16 10 10 14 10 10 12

Note:

a

SI engines were not simulated in GEM, rather a gas/diesel adjustment factor was applied to the results

(d) Technology Package Costs

The agencies have estimated the costs of the technologies that could be used to comply

with the proposed standards. The estimated costs are shown in Table V-20 for MY2021, in 

Table V-21 for MY2024, and Table V-22 for MY 2027. Fleet average costs are shown for light, 

medium and heavy HD vocational vehicles in each duty-cycle-based subcategory – Urban, 

Multi-Purpose, and Regional. As shown in Table V-20, in MY 2021 these range from 

approximately $600 for MHD and LHD Regional vehicles, up to $3,400 for HHD Regional 

vehicles. Those two lower-cost packages reflect zero hybrids, and the higher-cost package 

reflects significant adoption of automated transmissions. In the draft RIA Chapter 2.13.2, the 

agencies present vocational vehicle technology package costs differentiated by MOVES vehicle 

type. For example, intercity buses are estimated to have an average package cost of $2,900 and 

gasoline motor homes are estimated to have an average package cost of $450 in MY 2021. 

These costs do not indicate the per-vehicle cost that may be incurred for any individual 

technology. For more specific information about the agencies’ estimates of per-vehicle costs, 

please see the draft RIA Chapter 2.12. For example, Chapter 2.12.7 describes why a complex 

technology such as hybridization is estimated to range between $15,000 and $40,000 per vehicle 

for vocational vehicles in MY 2021. The engine costs listed represent the cost of an average 

package of diesel engine technologies as set out in Section II. Individual technology adoption 

rates for engine packages are described in Section II.D. The details behind all these costs are 

presented in draft RIA Chapter 2.12, including the markups and learning effects applied and how 
Page 368 of 850

the costs shown here are weighted to generate an overall cost for the vocational segment. We 

welcome comments on our technology cost assessments. 

Table V-20 Vocational Vehicle Technology Incremental Costs for the Proposal in the 2021 Model Yeara,b

(2012$)

Light HD Medium HD Heavy HD

Urban MultipurposeRegiona

l

Urba

n

MultipurposeRegiona

l

Urba

n

MultipurposeRegional

Enginec$293 $293 $293 $270 $270 $270 $270 $270 $270

Tires $7 $7 $7 $7 $7 $7 $7 $7 $7

Transmission $81 $81 $81 $81 $81 $81 $81 $81 $2,852

Axle related $99 $99 $99 $99 $99 $99 $148 $148 $219

Weight 

Reduction

$27 $27 $48 $27 $27 $41 $27 $27 $34

Idle reduction $49 $49 $49 $51 $51 $51 $6 $6 $0

Electrification 

& 

hybridization

$547 $547 $0 $861 $861 $0 $1,43

7

$1,437 $0

Air 

Conditioningd

$22 $22 $22 $22 $22 $22 $22 $22 $22

Total $1,125 $1,125 $598 $1,41

8

$1,418 $571 $1,99

8

$1,998 $3,404

Notes:

a Costs shown are for the 2021 model year and are incremental to the costs of a vehicle meeting the Phase 1 

standards. These costs include indirect costs via markups along with learning impacts. For a description of the 

markups and learning impacts considered in this analysis and how it impacts technology costs for other years, refer 

to Chapter 2 of the draft RIA (see draft RIA 2.12).

b Note that values in this table include adoption rates. Therefore, the technology costs shown reflect the average cost 

expected for each of the indicated vehicle classes. To see the actual estimated technology costs exclusive of 

adoption rates, refer to Chapter 2 of the draft RIA (see RIA 2.9 in particular).

c Engine costs are for a light HD, medium HD or heavy HD diesel engine. We are projecting no additional costs 

beyond Phase 1 for gasoline vocational engines.

d EPA’s air conditioning standards are presented in Section V.C above.

The estimated fleet average vocational vehicle package costs are shown in Table V-21 for 

MY2024. As shown, these range from approximately $800 for MHD and LHD Regional 

vehicles, up to $4,800 for HHD Regional vehicles. The increased costs above the MY 2021 

values reflect increased adoption rates of individual technologies, while the individual 

technology costs are generally expected to remain the same or decrease, as explained in the draft 

RIA Chapter 2.12. For example, Chapter 2.12.7 presents MY 2024 hybridization costs that 

range from $13,000 to $33,000 per vehicle for vocational vehicles. The engine costs listed 

represent the average costs associated with the proposed MY 2024 vocational diesel engine 

standard described in Section II.D. 
Page 369 of 850

Table V-21 Vocational Vehicle Technology Incremental Costs for the Proposal in the 2024 Model Yeara,b

(2012$)

Light HD Medium HD Heavy HD

Urban MultipurposeRegiona

l

Urba

n

MultipurposeRegiona

l

Urban MultipurposeRegional

Enginec$437 $437 $437 $405 $405 $405 $405 $405 $405

Tires $17 $17 $17 $17 $17 $17 $23 $23 $23

Transmission $123 $123 $123 $123 $123 $123 $123 $123 $3,915

Axle related $90 $90 $90 $90 $90 $90 $136 $136 $224

Weight 

Reduction

$24 $24 $43 $24 $24 $37 $24 $24 $30

Idle reduction $119 $119 $119 $125 $125 $125 $224 $224 $217

Electrification 

& 

hybridization

$906 $906 $0 $1,42

3

$1,423 $0 $2,377 $2,377 $0

Air 

Conditioningd

$20 $20 $20 $20 $20 $20 $20 $20 $20

Total $1,737 $1,737 $849 $2,22

8

$2,228 $817 $3,332 $3,332 $4,834

Notes:

a Costs shown are for the 2024 model year and are incremental to the costs of a vehicle meeting the Phase 1 

standards. These costs include indirect costs via markups along with learning impacts. For a description of the 

markups and learning impacts considered in this analysis and how it impacts technology costs for other years, refer 

to Chapter 2 of the draft RIA (see draft RIA 2.12).

b Note that values in this table include adoption rates. Therefore, the technology costs shown reflect the average cost 

expected for each of the indicated vehicle classes. To see the actual estimated technology costs exclusive of 

adoption rates, refer to Chapter 2 of the draft RIA (see RIA 2.9 in particular).

c Engine costs are for a light HD, medium HD or heavy HD diesel engine. We are projecting no additional costs 

beyond Phase 1 for gasoline vocational engines.

d EPA’s air conditioning standards are presented in Section V.C above.

The estimated fleet average vocational vehicle package costs are shown in Table V-22 for 

MY2027. As shown, these range from approximately $1,400 for MHD and LHD Regional 

vehicles, up to $7,400 for HHD Urban and Multipurpose vehicles. These two subcategories are 

projected to have the higher-cost packages in MY 2027 due to an estimated 18 percent adoption 

of HHD hybrids, which are estimated to cost $31,000 per vehicle in MY 2027, as shown in 

Chapter 2.12.7 of the draft RIA. These per-vehicle technology package costs were averaged 

using our projections of vehicle populations in the nine regulatory subcategories and do not 

correspond to the MOVES vehicle types. The engine costs shown represent the average costs 

associated with the proposed MY 2027 vocational diesel engine standard described in Section 

II.D. For gasoline vocational vehicles, the agencies are projecting adoption of Level 2 engine 

friction reduction with an estimated $68 added to the average SI vocational vehicle package cost 

in MY 2027, which represents about 56 percent of those vehicles upgrading beyond Level 1 

engine friction reduction. Further details on how these SI vocational vehicle costs were 

estimated are provided in the draft RIA Chapter 2.9. 

Purchase prices of vocational vehicles can range from $60,000 for a stake-bed landscape 

truck to over $400,000 for some transit buses. The costs of the vocational vehicle standards can 
Page 370 of 850

be put into perspective by considering package costs estimated using MOVES vehicle types 

along with typical prices for those vehicles. For example, a package cost of $4,000 on a $60,000 

short haul straight truck would represent an incremental increase of about six percent of the 

vehicle purchase price. Similarly, a package cost of $7,000 on a $200,000 refuse truck would 

represent an incremental increase of less than four percent of the vehicle purchase price. The 

vocational vehicle industry characterization report in the docket includes additional examples of 

vehicle prices for a variety of vocational applications.322

Table V-22 Vocational Vehicle Technology Incremental Costs for the Proposal in the 2027 Model Yeara,b

(2012$)

Light HD Medium HD Heavy HD

Urba

n

MultipurposeRegion

al

Urban MultipurposeRegiona

l

Urban MultipurposeRegional

Enginec$471 $471 $471 $437 $437 $437 $437 $437 $437

Tires $20 $20 $20 $20 $20 $20 $29 $29 $29

Transmission $244 $244 $267 $244 $244 $267 $244 $244 $2,986

Axle related $86 $86 $86 $86 $86 $86 $129 $129 $215

Weight 

Reduction

$29 $29 $46 $29 $29 $40 $29 $29 $35

Idle reduction $498 $499 $499 $526 $526 $526 $964 $964 $962

Electrification 

& 

hybridization

$2,12

2

$2,122 $0 $3,336 $3,336 $0 $5,571 $5,571 $0

Air 

Conditioningd

$19 $19 $19 $19 $19 $19 $19 $19 $19

Total $3,48

9

$3,490 $1,407 $4,696 $4,696 $1,395 $7,422 $7,422 $4,682

Notes:

a Costs shown are for the 2027 model year and are incremental to the costs of a vehicle meeting the Phase 1 

standards. These costs include indirect costs via markups along with learning impacts. For a description of the 

markups and learning impacts considered in this analysis and how it impacts technology costs for other years, refer 

to Chapter 2 of the draft RIA (see draft RIA 2.12).

b Note that values in this table include adoption rates. Therefore, the technology costs shown reflect the average cost 

expected for each of the indicated vehicle classes. To see the actual estimated technology costs exclusive of 

adoption rates, refer to Chapter 2 of the draft RIA (see RIA 2.9 in particular).

c Engine costs are shown for a light HD, medium HD or heavy HD diesel engine. For gasoline-powered vocational 

vehicles we are projecting $68 of additional engine-based costs beyond Phase 1.

d EPA’s air conditioning standards are presented in Section V.C above.

(3) Consistency of the Proposed Vocational Vehicle Standards with the Agencies’ 

Legal Authority

NHTSA and EPA project the proposed standards to be achievable within known design 

cycles, and we believe these standards, although technology-forcing, would allow many different 

paths to compliance in addition to the example outlined in this section. The proposed standards 

 

322 See industry characterization, Note 264, above.
Page 371 of 850

are predicated on manufacturers implementing technologies that we expect will be available in 

the time frame of these proposed rules, although in some instances these technologies are still 

under development or not widely deployed in the current vocational vehicle fleet. Under the 

proposal, manufacturers would need to apply a range of technologies to their vocational chassis, 

which the agencies believe would be consistent with the agencies’ respective statutory

authorities. We are projecting that most vehicles could adopt certain of the technologies. For 

example, we project a 70 to 75 percent application rate for stop-start idle reduction and advanced 

axle lubrication. However, for other technologies, such as strong hybrids and weight reduction, 

we are projecting adoption rates of ten percent or less overall, with individual subcategories 

having adoption rates greater or less than this. The proposed standards offer manufacturers the 

flexibility to apply the technologies that make sense for their business and customer needs. 

As discussed above, average per-vehicle costs associated with the proposed 2027 MY 

standards are projected to be generally less than six percent of the overall price of a new vehicle. 

The cost-effectiveness of these proposed vocational vehicle standards in dollars per ton is similar 

to the cost effectiveness estimated for light-duty trucks in the 2017-2025 light duty greenhouse 

gas standards, which the agencies have found to be highly cost effective.

323

 In addition, the 

vocational vehicle standards are clearly effective from a net benefits perspective (see draft RIA 

Chapter 11.2). Therefore, the agencies regard the cost of the proposed standards as reasonable.

The agencies note that while the projected costs are significantly greater than the costs 

projected for Phase 1, we still consider these costs to be reasonable, especially given that the first 

vehicle owner may see the technologies pay for themselves in many cases. As discussed above, 

the usual period of ownership for a vocational vehicle reflects a lengthy trade cycle that may

often exceed seven years. For most vehicle types evaluated, the cost of these technologies, if 

passed on fully to customers, would be recovered within five years or less due to the associated 

fuel savings, as shown in the payback analysis included in Section IX and in the draft RIA 

Chapter 7.1. Specifically, in Table 7-30 of the draft RIA Chapter 7.1.3, a summary is presented 

with estimated payback periods for each of the MOVES vocational vehicle types, using the 

annual vehicle miles traveled from the MOVES model for each vehicle type. As shown, the 

vocational vehicle type with the shortest payback would be intercity buses (less than one year), 

while most other vehicles (with the exception of school buses and motor homes) are projected to 

see paybacks in the fifth year or sooner.

The agencies note further that although the proposal is technology-forcing (especially 

with respect to driveline improvements) and the estimated costs for each subcategory vary

considerably (by a factor of five in some cases), these costs represent only one of many possible 

pathways to compliance for manufacturers. Manufacturers retain leeway to develop alternative 

compliance paths, increasing the likelihood of the standards’ successful implementation. Based 

on available information, the agencies believe the proposed standards are technically feasible 

within the lead time provided, are cost effective while accounting for the fuel savings (see draft 

 

323 See Chapter 5.3 of the final RIA for the MY 2017-2025 Light-Duty GHG Rule, available at 

http://www.epa.gov/otaq/climate/documents/420r12016.pdf.
Page 372 of 850

RIA Chapter 7.1.4), and have no apparent adverse collateral potential impacts (e.g., there are no 

projected negative impacts on safety or vehicle utility).

The proposed standards thus appear to 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). The agencies believe that the proposed standards are consistent with their 

respective authorities. Based on the information currently before the agencies, we believe that 

the preferred alternative would be maximum feasible and reasonable for the vocational segment 

with a progression of standards reaching full implementation in MY 2027.

Nevertheless, as discussed in Section 0and in Section X (Alternatives), the agencies seek 

comment on the feasibility of Alternative 4 , which the agencies may determine is maximum 

feasible and reasonable depending on comments and information received during the comment 

period. This alternative is discussed in detail below because it may be possible for 

manufacturers to accelerate product development cycles enough to reach the required levels by

the 2024 model year. Thus, the agencies may conclude in the final rules that Alternative 4, or 

some elements of this alternative, would be maximum feasible and appropriate under CAA 

section 202 (a)(1) and (2), depending on information and comments received. The agencies 

seek comments to assist us in making that determination. 

D. Alternative Vocational Vehicle Standards Considered

The agencies have analyzed vocational vehicle standards other than the proposed 

standards. These alternatives, listed in Table III-22, are described in detail in Section X of this 

preamble and the draft RIA Chapter 11. 

Table V-23 Summary of Alternatives Considered for the Proposed Rulemaking

Alternative 1 No action alternative

Alternative 2 Less stringent than the proposed alternative, applying off-the-shelf technologies

Alternative 3 

(Proposed Alternative)

Proposed alternative fully phased-in by MY 2027

Alternative 4 Same stringency as proposed alternative, except phasing in faster, by MY 2024

Alternative 5 More stringent alternative, based on higher adoption rates of advanced technologies

NHTSA and EPA are considering an Alternative 4 that achieves the same level of 

stringency as the preferred alternative, except it would provide less lead time, reaching its most 

stringent level three years earlier than the preferred alternative, that is in MY 2024. The agencies 

project that the same selection of technology options would be available to manufacturers 

regardless of what alternative is chosen. The preferred alternative would allow greater lead time 

to manufacturers to select and develop technologies for their vehicles. 

The agencies have outstanding questions regarding relative risks and benefits of 

Alternative 4 due to the time frame envisioned by that alternative. If the agencies receive 

relevant information supporting the feasibility of Alternative 4, the agencies may consider 

establishing vocational vehicle standards that provide more overall reductions than what we are

proposing if we deem them to be maximum feasible and reasonable for NHTSA and EPA, 

respectively. See the draft RIA Chapter 11.2.2 for a summary of costs and benefits that 
Page 373 of 850

compares the proposed Phase 2 vocational vehicle program with the costs and benefits of other 

vocational vehicle alternatives considered. 

In the paragraphs that follow, the agencies present the derivation of the Alternative 4 

vocational vehicle standards. For currently developing technologies where we project an 

adoption rate that could present potential risks or challenges, we seek comment on the cost and 

effectiveness of such technology. Further, the agencies seek comment on the potential for 

adoption of developing technologies into the vocational vehicle fleet, as well as the extent to 

which the more accelerated alternative vocational vehicle standards may depend on such 

technology.

(1) Adoption Rates for Derivation of Alternative 4 Vocational Vehicle Standards

In developing the Alternative 4 standards, the agencies are projecting a set of technology

packages in MY 2024 that is identical to those projected for the final phase-in year of the 

preferred alternative. Because these are the same for each subcategory, the GEM inputs modeled 

to derive the level of the MY 2024 Alternative 4 standards can be found in Table V-19, which 

presents the GEM inputs used to derive the level of the MY 2027 proposed standards. In the 

package descriptions below, the agencies outline technology-specific adoption rates in MY 2021 

for Alternative 4 and offer insights on what market conditions could enable reaching adoption 

rates that would achieve the full implementation levels of stringency with less lead time. 

For transmissions including hybrids, the agencies project for Alternative 4 that 50 percent 

of vocational vehicles would have one or more of the transmission technologies identified above 

in this section applied by MY 2021. This includes 25 percent deeply integrated conventional 

transmissions that would be recognized over the powertrain test, 10 percent DCT, 11 percent 

adding two gears (except zero for HHD Regional), and nine percent hybrids for vehicles certified 

in the Multi-Purpose and Urban subcategories, which we estimate would be five percent overall. 

In this alternative, the agencies project 21 percent of the vocational vehicles with manual 

transmissions in the HHD Regional subcategory would upgrade to either an AMT, DCT, or 

automatic transmission. The increased projection of driveline integration would mean that more 

manufacturers would need to overcome data-sharing barriers. In this alternative, we project that 

manufacturers would need to conduct additional research and development to achieve overall 

application of five percent hybrids. In the draft RIA Chapter 7.1, the agencies have estimated 

costs for this additional accelerated research. Comments are requested on the expected costs to 

accelerate hybrid development to meet the projected adoption rates of this alternative.

For advanced axle lubricants, the agencies are projecting the same 75 percent adoption 

rate in MY 2021 as in the proposed program. For part time or full time 6x2 axles, the agencies 

project the HHD Regional vocational vehicles could apply this at the 60 percent adoption rate in 

MY 2021, where this level wouldn’t be reached until MY 2024 in the proposed program. One 

action that could enable this to be achieved is if information on the reliability of these systems 

were to be disseminated to more fleet owners by trustworthy sources.

For lower rolling resistance tires in this alternative, the agencies project the same 

adoption rates of LRR tires as in the proposed program for MY 2021, because we don’t expect 

tire suppliers would be able to make greater improvements for the models that are fitted on 
Page 374 of 850

vocational vehicles in that time frame. The tire research that is being conducted currently is 

focused on models for tractors and trailers, and we project further improved LRR tires would not 

be commercially available for vocational vehicles in the early implementation years of Phase 2.

For the adoption rate of LRR tires in MY 2024 to reach the level projected for MY 2027 

in the proposed program, tire suppliers could promote their most efficient products to vocational 

vehicle manufacturers to achieve equivalent improvements with less lead time. Depending on 

how tire manufacturers focus their research and product development, it is possible that more of 

the LRR tire advancements being applied for tractors and trailers could be applied to vocational 

vehicles. To see the specific projected adoption rates of different levels of LRR tires for 

Alternative 4, see columns three and five of Table V-16 above.

For workday idle technologies, the agencies project an adoption rate of 12 percent stopstart in the six MHD and LHD subcategories for MY 2021 and zero for the HHD vehicles, on the 

expectation that manufacturers would have fewer challenges in the short term in bringing this 

technology to market for vehicles with lower power demands and lower engine inertia. In this 

alternative, the agencies project the overall workday idle adoption rate would approach 100 

percent, such that any vehicle without stop-start (except HHD Regional) would apply neutral idle 

in MY 2021. These adoption raters consider a more aggressive investment by manufacturers in 

developing these technologies. Estimates of research and development costs for this alternative 

are presented in the draft RIA Chapter 7.1.

For weight reduction, in this alternative, the agencies project the same adoption rates of a 

200-lb lightweighting package as in the proposal for each subcategory in MY 2021, which is four 

to seven percent. Table V-24 shows the GEM inputs used to derive the level of the Alternative 4 

MY 2021 standards. 
Page 375 of 850

Table V-24 GEM Inputs Used to Derive Alternative 4 MY 2021 Vocational Vehicle Standards

Class 2b-5 Class 6-7 Class 8

Urban MultiPurposeRegional Urban MultiPurposeRegional Urban MultiPurposeRegional

Alternative 4 CI Enginea

2021 MY 7L, 200 hp Engine 2021 MY 7L, 270 hp Engine 2021 MY 11L, 345 

hp Engine

2021 MY 

15L 455hp 

Engine

Transmission (improvement factor)

0.045 0.04 0.014 0.045 0.041 0.015 0.045 0.041 0.018

Axle (improvement factor)

0.004 0.004 0.004 0.004 0.004 0.004 0.004 0.004 0.015

Stop-Start (adoption rate)

12% 12% 12% 12% 12% 12% 0% 0% 0%

Neutral Idle (adoption rate)

88% 88% 88% 88% 88% 88% 90% 90% 0%

Steer Tires (CRR kg/metric ton)

7.1 7.1 7.1 7.1 7.1 7.1 7.1 7.1 7.1

Drive Tires (CRR kg/metric ton)

7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5

Weight Reduction (lb)

8 8 14 8 8 12 8 8 10

Note:

a

SI engines were not simulated in GEM, rather a gas/diesel adjustment factor was applied to the results.

(2) Possible Alternative 4 Standards

Because the MY 2024 Alternative 4 standards are the same as the proposed standards for 

MY 2027 for each subcategory, these numerical standards can be found in Table V-8 and Table 

V-9, which present EPA’s and NHTSA’s proposed MY 2027 standards, respectively. Table 

V-25 and Table V-26 present the Alternative 4 vocational vehicle standards for the initial year of 

MY 2021. These represent incremental improvements over the MY 2017 baseline of six to 

seven percent for SI-powered vocational vehicles and nine percent for CI-powered vocational 

vehicles.
Page 376 of 850

Table V-25 Alternative 4 EPA CO2 Standards for MY2021 Class 2b-8 Vocational Vehicles 

Alternative EPA Standard for Vehicle with CI Engine Effective MY2021 (gram CO2/tonmile)

Duty Cycle Light Heavy-Duty 

Class 2b-5

Medium Heavy-Duty 

Class 6-7

Heavy Heavy-Duty

Class 8

Urban 288 183 193

Multi-Purpose 297 185 196

Regional 309 181 185

Alternative EPA Standard for Vehicle with SI Engine Effective MY2021 (gram CO2/tonmile)

Duty Cycle Light Heavy-Duty 

Class 2b-5

Medium Heavy-Duty 

Class 6-7

Heavy Heavy-Duty

Class 8

Urban 313 199 210

Multi-Purpose 323 201 212

Regional 336 197 201

Table V-26 Alternative 4 NHTSA Fuel Consumption Standards for MY2021 Class 2b-8 Vocational Vehicles 

Alternative NHTSA Standard for Vehicle with CI Engine Effective MY 2021 (Fuel 

Consumption gallon per 1,000 ton-mile)

Duty Cycle Light Heavy-Duty 

Class 2b-5

Medium Heavy-Duty 

Class 6-7

Heavy Heavy-Duty

Class 8

Urban 28.2908 17.9764 18.9587

Multi-Purpose 29.1749 18.1729 19.2534

Regional 30.3536 17.7800 18.1729

Alternative NHTSA Standard for Vehicle with SI Engine Effective MY 2021 (Fuel 

Consumption gallon per 1,000 ton-mile) 

Duty Cycle Light Heavy-Duty 

Class 2b-5

Medium Heavy-Duty 

Class 6-7

Heavy Heavy-Duty

Class 8

Urban 35.2200 22.3923 23.6300

Multi-Purpose 36.3452 22.6173 23.8551

Regional 37.8080 22.1672 22.6173

(3) Costs Associated with Alternative 4 Standards

The agencies have estimated the costs of the technologies expected to be used to comply

with the Alternative 4 standards, as shown in Table V-27 for MY2021. Fleet average costs are 

shown for light, medium and heavy HD vocational vehicles in each duty-cycle-based 

subcategory – Urban, Multi-Purpose, and Regional. As shown in Table V-27, in MY 2021 these 

range from approximately $800 for MHD and LHD Regional vehicles, to $4,300 for HHD Urban 

and Multipurpose vehicles. Those two subcategories are projected to have the higher-cost 

packages in MY 2021 due to an estimated 9 percent adoption of HHD hybrids, which are 

estimated to cost $40,000 per vehicle in MY 2021, as shown in Chapter 2.12.7 of the draft RIA. 
Page 377 of 850

For more specific information about the agencies’ estimates of per-vehicle costs, please see the 

draft RIA Chapter 2.12. The engine costs listed represent the cost of an average package of 

diesel engine technologies with Alternative 4 adoption rates described in Section II.D.2(e). The 

details behind all these costs are presented in draft RIA Chapter 2.12, including the markups and 

learning effects applied and how the costs shown here are weighted to generate an overall cost 

for the vocational segment.

Table V-27 Vocational Vehicle Technology Incremental Costs for Alternative 4 Standards in the 2021 Model 

Yeara,b (2012$)

Light HD Medium HD Heavy HD

Urban MultipurposeRegional Urban MultipurposeRegional Urban MultipurposeRegional

Enginec$372 $372 $372 $345 $345 $345 $345 $345 $345

Tires $7 $7 $7 $7 $7 $7 $7 $7 $7

Transmission $148 $148 $148 $148 $148 $148 $148 $148 $2,042

Axle related $99 $99 $99 $99 $99 $99 $148 $148 $243

Weight Reduction $27 $27 $48 $27 $27 $41 $27 $27 $34

Idle reduction $110 $110 $110 $116 $116 $116 $8 $8 $0

Electrification & 

hybridization

$1,384 $1,384 $0 $2,175 $2,175 $0 $3,633 $3,633 $0

Air Conditioningd$22 $22 $22 $22 $22 $22 $22 $22 $22

Total $2,169 $2,169 $805 $2,938 $2,938 $777 $4,337 $4,337 $2,693

Notes:

a Costs shown are for the 2021 model year and are incremental to the costs of a vehicle meeting the Phase 1 

standards. These costs include indirect costs via markups along with learning impacts. For a description of the 

markups and learning impacts considered in this analysis and how it impacts technology costs for other years, refer 

to Chapter 2 of the draft RIA (see draft RIA 2.12).

b Note that values in this table include adoption rates. Therefore, the technology costs shown reflect the average cost 

expected for each of the indicated vehicle classes. To see the actual estimated technology costs exclusive of 

adoption rates, refer to Chapter 2 of the draft RIA (see RIA 2.9 in particular).

c Engine costs are for a light HD, medium HD or heavy HD diesel engine. We are projecting no additional costs 

beyond Phase 1 for gasoline vocational engines.

d EPA’s air conditioning standards are presented in Section V.C above.

The estimated costs of the technologies expected to be used to comply with the 

Alternative 4 standards for MY2024 are shown in Table V-28. As shown, these range from 

approximately $1,500 for MHD and LHD Regional vehicles to $7,900 for HHD Urban and 

Multipurpose vehicles. These two subcategories are projected to have the higher-cost packages 

in MY 2024 due to an estimated 18 percent adoption of HHD hybrids, which are estimated to 

cost $33,000 per vehicle in MY 2024, as shown in Chapter 2.12.7 of the draft RIA. The engine 

costs listed represent the cost of an average package of diesel engine technologies with 

Alternative 4 adoption rates described in Section II.D.2(e). For gasoline vocational vehicles, the 

agencies are projecting adoption of Level 2 engine friction reduction with an estimated $74

added to the average SI vocational vehicle package cost in MY 2024, which represents about 56 

percent of those vehicles upgrading beyond Level 1 engine friction reduction. Further details on 

how these SI vocational vehicle costs were estimated are provided in the draft RIA Chapter 2.9.
Page 378 of 850

Table V-28 Vocational Vehicle Technology Incremental Costs for Alternative 4 Standards in the 2024 Model 

Yeara(2012$)

Light HD Medium HD Heavy HD

Urban MultipurposeRegional Urban MultipurposeRegional Urban MultipurposeRegional

Enginec$493 $493 $493 $457 $457 $457 $457 $457 $457

Tires $26 $26 $26 $26 $26 $26 $40 $40 $40

Transmission $256 $256 $280 $256 $256 $280 $256 $256 $3,123

Axle related $90 $90 $90 $90 $90 $90 $136 $136 $224

Weight Reduction $30 $30 $49 $30 $30 $43 $30 $30 $37

Idle reduction $561 $524 $524 $592 $553 $553 $1,014 $1,014 $1,011

Electrification & 

hybridization

$2,264 $2,264 $0 $3,559 $3,559 $0 $5,943 $5,943 $0

Air Conditioningd$20 $20 $20 $20 $20 $20 $20 $20 $20

Total $3,741 $3,704 $1,482 $5,030 $4,992 $1,469 $7,895 $7,895 $4,912

Notes:

a Costs shown are for the 2024 model year and are incremental to the costs of a vehicle meeting the Phase 1 

standards. These costs include indirect costs via markups along with learning impacts. For a description of the 

markups and learning impacts considered in this analysis and how it impacts technology costs for other years, refer 

to Chapter 2 of the draft RIA (see draft RIA 2.12).

b Note that values in this table include adoption rates. Therefore, the technology costs shown reflect the average cost 

expected for each of the indicated vehicle classes. To see the actual estimated technology costs exclusive of 

adoption rates, refer to Chapter 2 of the draft RIA (see RIA 2.9 in particular).

c Engine costs shown are for a light HD, medium HD or heavy HD diesel engine. For gasoline-powered vocational 

vehicles we are projecting $74 of additional engine-based costs beyond Phase 1.

d EPA’s air conditioning standards are presented in Section V.C above.

E. Compliance Provisions for Vocational Vehicles

We welcome comment on all aspects of the compliance program, including those where 

we would adopt a provision without change in Phase 2.

(1) Application and Certification Process

The agencies propose to continue to use GEM to determine compliance with the 

proposed vehicle fuel efficiency and CO2 standards. Because the agencies are proposing to 

modify GEM to recognize inputs in addition to those recognized under Phase 1, there is a 

consequent proposed requirement that manufacturers or component suppliers conduct component 

testing to generate those input values. See Section II for details of engine testing and GEM 

inputs for engines. 

As described above in Section I, the agencies propose to continue the Phase 1 compliance 

process in terms of the manufacturer requirements prior to the effective model year, during the 

model year, and after the model year. The information that would be required to be submitted by

manufacturers is set forth in 40 CFR 1037.205 and 49 CFR 537.6-537.7. EPA would continue to 

issue certificates upon approval based on information submitted through the VERIFY database 

(see 40 CFR 1037.255). End of year reports would continue to include the GEM results for all of 

the configurations built, along with credit/deficit balances, if applicable (see 40 CFR 1037.250 

and 1037.730).
Page 379 of 850

(a) GEM Inputs

In Phase 1, there were two inputs to GEM for vocational vehicles:

 Steer tire coefficient of rolling resistance, and

 Drive tire coefficient of rolling resistance

As discussed above in Section II and III.D, there are several additional inputs that are 

proposed for Phase 2. In addition to the steer and drive tire CRR, the proposed inputs include the 

following:

 Engine fuel map,

 Engine full-load torque curve,

 Engine motoring curve,

 Transmission type,

 Transmission gear ratios,

 Drive axle ratio,

 Loaded tire radius for drive and steer tires,

 Idle Reduction,

 Weight Reduction, and

 Other pre-defined off-cycle technologies.

(i) Driveline Inputs

As with tractors, for each engine family, an engine fuel map, full load torque curve, and 

motoring curve would be generated by engine manufacturers as inputs to GEM. The test 

procedures for the torque and motoring curves are found in proposed 40 CFR part 1065. Section 

II.D.1.b describes these proposed procedures as well as the proposed new procedure for 

generating the engine fuel map. Also similar to tractors, transmission specifications would be 

input to GEM. Any number of gears could be entered with a numerical ratio for each, and 

transmission type would be selectable as either a Manual, Automated Manual, Automatic, or 

Dual Clutch transmission. 

As part of the driveline information needed to run GEM, drive axle ratio would be a user 

input. If a configuration has a two-speed axle, the agencies propose that a manufacturer may

enter the ratio that is expected to be engaged most often. We request comment on whether the 

agencies should allow this choice. Two-speed axles are typically specified for heavy-haul 

vocational vehicles, where the higher numerical ratio axle would be engaged during transient 

driving conditions and to deliver performance needed on work sites, while the lower numerical 

ratio axle would be engaged during highway driving. The agencies request comment on whether 

we should require GEM to be run twice, once with each axle ratio, where the output over the 

highway cycles would be used from the run with the lower axle ratio, and the output over the 

transient cycle would be used from the run with the higher axle ratio. 

Tire size would be a new input to GEM that is necessary for the model to simulate the 

performance of the vehicle. The draft RIA Chapter 3 includes a description of how to measure 
Page 380 of 850

tire size. For each model and nominal size of a tire, there are numerous possible sizes that could 

be measured, depending on whether the tire is new or “grown,” meaning whether it has been 

broken in for at least 200 miles. Size could also vary based on load and inflation levels, air 

temperature, and tread depth. The agencies request comment on aspects of measuring and 

reporting tire size that could be specified by rule, to avoid any unnecessary compliance burden of 

the Phase 2 program. 

(ii) Idle Reduction Inputs 

Based on user inputs derived from engine testing described in Section II and draft RIA 

Chapter 3, GEM would calculate CO2 emissions and fuel consumption at both zero torque 

(neutral idle) and with torque set to Curb-Idle Transmission Torque for automatic transmissions 

in “drive” (as defined in 40 CFR 1065.510(f)(4) for variable speed engines) for use in the CO2

emission calculation in 40 CFR 1037.510(b). The proposed regulations at 40 CFR part 1065 

specify that that there must be two consecutive reference zero load idle points to establish 

periods of zero load idle for purposes of calculating total work over an engine test cycle. These 

two idle points from the engine test would be used in GEM for purposes of calculating emissions 

during vehicle idling over the vocational vehicle test cycles.

The agencies welcome comments on the inclusion of these technologies into GEM in 

Phase 2.

(iii) Weight Reduction Inputs

In Phase 1, the agencies adopted tractor regulations that provided manufacturers with the 

ability to utilize high strength steel and aluminum components for weight reduction without the 

burden of entering the curb weight of every tractor produced. In Phase 2, the agencies propose 

to apply relevant weights from the tractor lookup table to vocational vehicles. As noted above, 

the agencies are proposing to recognize weight reduction by allocating one half of the weight 

reduction to payload in the denominator, while one half of the weight reduction would be 

subtracted from the overall weight of the vehicle in GEM. 

To adapt the tractor table for vocational vehicles, the agencies propose to add lookup 

values for vehicles in lower weight classes. We believe it is appropriate to also recognize the 

weight reduction associated with 6x2 axles.324 Components available for vocational vehicle 

manufacturers to select for weight reduction are shown below in Table V-29, below. We are also 

proposing to assign a fixed weight increase to natural gas fueled vehicles to reflect the weight 

increase of natural gas fuel tanks versus gasoline or diesel tanks. These are shown as negative 

values in Table V-29 to indicate that GEM would internally compute these values in an inverse 

manner as would be computed for a weight reduction, for which the GEM input is a positive 

numerical value. We welcome comments on all aspects of weight reduction approaches and 

potential weight increases as a byproduct of technology application. 

 

324 See NACFE Confidence Findings on the Potential of 6x2 Axles, Note 152 above.
Page 381 of 850

Table V-29 Proposed Phase 2 Weight Reduction Technologies for Vocational Vehicles 

COMPONENT MATERIAL VOCATIONAL VEHICLE CLASS

Class 2b-5 Class 6-7 Class 8

Axle Hubs - Non-Drive Aluminum 40 40

Axle Hubs - Non-Drive High Strength Steel 5 5

Axle - Non-Drive Aluminum 60 60

Axle - Non-Drive High Strength Steel 15 15

Brake Drums - Non-Drive Aluminum 60 60

Brake Drums - Non-Drive High Strength Steel 8 8

Axle Hubs - Drive Aluminum 40 80

Axle Hubs - Drive High Strength Steel 10 20

Brake Drums - Drive Aluminum 70 140

Brake Drums - Drive High Strength Steel 5.5 11

Clutch Housing Aluminum 34 40

Clutch Housing High Strength Steel 9 10

Suspension Brackets, 

Hangers

Aluminum 67 100

Suspension Brackets, 

Hangers

High Strength Steel 20 30

Transmission Case Aluminum 45 50

Transmission Case High Strength Steel 11 12

Crossmember – Cab Aluminum 10 14 15

Crossmember – Cab High Strength Steel 2 4 5

Crossmember - NonSuspensionAluminum 15 18 21

Crossmember - NonSuspensionHigh Strength Steel 5 6 7

Crossmember -Suspension Aluminum 15 20 25

Crossmember -Suspension High Strength Steel 4 5 6

Driveshaft Aluminum 12 40 50

Driveshaft High Strength Steel 5 10 12

Frame Rails Aluminum 120 300 440

Frame Rails High Strength Steel 24 40 87

Wheels - Dual Aluminum 126 126 210

Wheels - Dual High Strength Steel 48 48 80

Wheels - Dual Lightweight 

Aluminum

180 180 300

Wheels - Wide Base 

Single

Aluminum 278 278 556

Wheels - Wide Base 

Single

High Strength Steel 168 168 336
Page 382 of 850

Wheels - Wide Base 

Single

Lightweight 

Aluminum

294 294 588

Permanent 6x2 Axle 

Configuration

Multi N/A N/A 300

CI Liquified Natural Gas 

Vocational Vehicle

Multi -600325,326

SI Compressed Natural 

Gas Vocational Vehicle

Multi -525

CI Compressed Natural 

Gas Vocational Vehicle

Multi -900

(b) Test Procedures

Powertrain families are defined in Section II.C.3.b, and powertrain test procedures are

discussed in the draft RIA Chapter 3. The agencies propose that the results from testing a 

powertrain configuration using the matrix of tests described in draft RIA Chapter 3.6 could be 

applied broadly across all vocational vehicles in which that powertrain would be installed. 

As in Phase 1, the rolling resistance of each tire would be measured using the ISO 28850 

test method for drive tires and steer tires planned for fitment to the vehicle being certified. Once 

the test CRR values are obtained, a manufacturer would input the CRR values for the drive and 

steer tires separately into the GEM. For vocational vehicles in Phase 2, the agencies propose that 

the vehicle load would be distributed with 30 percent of the load over the steer tires and 70

percent of the load over the drive tires. With these data entered, the amount of GHG reduction 

attributed to tire rolling resistance would be incorporated into the overall vehicle compliance 

value.

(c) Useful Life and In-Use Standards

Section 202(a)(1) of the CAA specifies that emission standards are to be applicable for 

the useful life of the vehicle. The standards that EPA is proposing would apply to individual 

vehicles and engines at production and in use. NHTSA is not proposing in-use standards for 

vehicles and engines. 

Manufacturers may be required to submit, as part of the application for certification, an 

engineering analysis showing that emission control performance will not deteriorate during the 

useful life, with proper maintenance. If maintenance will be required to prevent or minimize 

deterioration, a demonstration may be required that this maintenance will be performed in use. 

(See 40 CFR 1037.241).

 

325 See National Energy Policy Institute (2012), Note 199 above. 

326 See Westport presentation (2013), Note 200, above. 
Page 383 of 850

EPA is proposing to continue the Phase 1 approach to adjustment factors and 

deterioration factors. The technologies on which the Phase 1 vocational vehicle standards were 

predicated were not expected to have any deterioration of GHG effectiveness in use. However, 

the regulations provided a process for manufacturers to develop deterioration factors (DF) if they

needed. We anticipate that some hybrid powertrain systems may experience some deterioration 

of effectiveness with age of the energy storage device. We believe the regulations in place

currently provide adequate instructions to manufacturers for developing DF where needed. We 

request comment on whether any changes to the DF process are needed. 

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.

For vocational vehicles, attributes generally refers to components that are installed by the 

manufacturer to meet the standard, whose reduction properties are assessed at the time of 

certification, and which are expected to last the full life of the vehicle with effectiveness 

maintained as new for the life of the vehicle with no special maintenance requirements. To 

assess useful life compliance, we are proposing to follow a design-based approach that would 

ensure that the manufacturer has robustly designed these features so they can reasonably be 

expected to last the useful life of the vehicle.

For vocational vehicles, maintenance items generally 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, but may also include hybrid system batteries. 

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. In this proposal, the only maintenance costs we have quantified are those for tire 

replacement, as described in Section IX.C.3 and the draft RIA Chapter 7.1. The agencies invite 

comments with information related to maintenance costs that the agencies should quantify for the 

final rules.

For current non-hybrid technologies, 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. As in Phase 1, the agencies propose allowing the use of an 

assigned deterioration factor of zero where appropriate in Phase 2; however this does not negate 

the responsibility of the manufacturer to ensure compliance with the emission standards 

throughout the useful life. 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 would show that components are 
Page 384 of 850

constructed of sufficiently robust materials and design practices so as not to become 

dysfunctional under normal operating conditions.

In Phase 1, EPA set the useful life for engines and vehicles with respect to GHG 

emissions equal to the respective useful life periods for criteria pollutants. In April 2014, as part 

of the Tier 3 light-duty vehicle final rule, EPA extended the regulatory useful life period for 

criteria pollutants to 150,000 miles or 15 years, whichever comes first, for Class 2b and 3 pickup 

trucks and vans and some light-duty trucks (79 FR 23414, April 28, 2014). Class 2 through 

Class 5 heavy-duty vehicles subject to the GHG standards described in this section for vocational 

applications generally use the same kinds of engines, transmissions, and emission controls as the 

Class 2b and 3 vehicles that are chassis-certified to the criteria standards under 40 CFR part 86, 

subpart S. EPA is therefore proposing that the Phase 2 GHG standards for vocational vehicles at 

or below 19,500 pounds GVWR apply over the same useful life of 150,000 miles or 15 years. In 

many cases, this will result in aligned useful-life values for criteria and GHG standards. Where 

this longer useful life is not aligned with the useful life that applies for criteria standards 

(generally in the case of engine-based certification under 40 CFR part 86, subpart A), EPA may

revisit the useful-life values for both criteria and GHG standards in a future rulemaking. For 

medium heavy-duty vehicles (19,500 to 33,000 pounds GVWR) and heavy heavy-duty vehicles 

(above 33,000 pounds GVWR) EPA is proposing to keep the useful-life values from Phase 1, 

which are 185,000 miles (or 10 years) and 435,000 miles (or 10 years), respectively. EPA 

requests comment on this approach, including the proposed values and the overall process 

envisioned for achieving the long-term goal of adopting harmonized useful-life specifications for 

criteria and GHG standards that properly represent the manufacturers’ obligation to meet 

emission standards over the expected service life of the vehicles. EPA may also revisit the 

useful-life values that apply for medium heavy-duty vehicles and heavy heavy-duty vehicles.

One technology option for vocational vehicle manufacturers to reduce GHG emissions is 

to use a smaller engine, perhaps in conjunction with a hybrid powertrain. This could lead to a 

situation where the engine and the vehicle are subject to emission standards over different usefullife periods. For example, an urban bus (heavy heavy-duty vehicle), might be able to use a 

medium heavy-duty engine, or even a light heavy-duty engine. While such a mismatch in useful 

life values could be confusing, we don’t believe it poses any particular policy problem that we 

need to address. EPA requests comment on the possibility of mismatched engine and vehicle 

useful-life values and on any possible implications this may have for manufacturers’ ability to 

design, certify, produce, and sell their engines and vehicles.

While NHTSA would use useful life considerations as described above 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 would be notable deterioration of fuel 

consumption over the engines’ useful life. 

(d) Assigning Vehicles to Test Cycles 

The agencies propose the following logic for deciding which chassis configurations 

would be assigned to each of the three proposed vocational duty cycles and thus regulatory

subcategories:
Page 385 of 850

 A vehicle would be certified over the Multipurpose Duty Cycle, unless one of the 

following conditions warrants certifying over either the Regional or Urban cycle. 

 If the vehicle is powered by a CI engine, use the Regional Duty Cycle if the 

resulting value from the calculation described in Equation V-1 is less than 75 

percent.

 If the vehicle is powered by a SI engine, use the Regional Duty Cycle if the 

resulting value from the calculation described in Equation V-1 is less than 45 

percent.

Equation V-1 Proposed Regional Duty Cycle Cutpoint

  = 

65 h        

 ∗   100

Where

CutpointRegional is the percent of maximum engine test speed that is achieved at a vehicle 

speed of 65 mph,

SLR is the static loaded tire radius entered into GEM as specified in the regulations,

Axle ratio is the drive axle ratio that entered into GEM as specified in the regulations,

Trans ratio is the ratio of the top transmission gear that is not permanently locked out,

fntest is the maximum engine test speed as defined at 40 CFR 1065.610, and

C is a constant equal to

5280 

  12 

  .0254 



60 

h

 2

 If a vehicle is powered by a CI engine, use the Urban Duty Cycle if the resulting 

value from the calculation described in Equation V-2 is greater than 90 percent.

 If a vehicle is powered by a SI engine, use the Urban Duty Cycle if the resulting 

value from the calculation described in Equation V-2 is greater than 50 percent.

Equation V-2 Proposed Urban Duty Cycle Cutpoint

  = 

55 h        

 ∗   100

Where

CutpointUrban is the percent of maximum engine test speed that is achieved at a vehicle 

speed of 55 mph,
Page 386 of 850

SLR is the static loaded tire radius entered into GEM as specified in the regulations,

Axle ratio is the drive axle ratio that is entered into GEM as specified in the regulations,

Trans ratio is the ratio of the top transmission gear that is not permanently locked out,

fntest is the maximum engine test speed as defined at 40 CFR 1065.610, and

C is a constant equal to

5280 

  12 

  .0254 



60 

h

 2

The agencies ran GEM with many vocational vehicle configurations to develop a data set 

with which we could assess appropriate cutpoints for the above equations. The configurations 

varied primarily by the engine model, fuel type, and axle ratio. See the draft RIA Chapter 2.9.2 

for further details on the assessment process for these proposed cutpoints.

The agencies realize that there are vocational vehicles for which the above logic may not 

result in an appropriate assignment of test cycle. Therefore we are proposing an exception that 

would enable any vehicle with a hybrid drivetrain to certify over the Urban test cycle. Further, 

we are proposing that the following vehicles must be certified using the Regional cycle: intercity 

coach buses, recreational vehicles, and vehicles whose engine is exclusively certified over the 

SET. We are also proposing to allow manufacturers to request a different duty cycle. We 

request comment on this approach, and whether we should allow manufacturers to have complete 

freedom to select a test cycle without any need for EPA or NHTSA approval. 

(2) Other Compliance Provisions

(a) Emission Control Labels

The agencies consider it crucial that authorized compliance inspectors are able to identify

whether a vehicle is certified, and if so whether it is in its certified condition. To facilitate this 

identification in Phase 1, EPA adopted labeling provisions for vocational vehicles that included 

several items. The Phase 1 vocational vehicle label must include the manufacturer, vehicle 

identifier such as the Vehicle Identification Number, vehicle family, regulatory subcategory, date 

of manufacture, compliance statements, and emission control system identifiers (see 40 CFR 

1037.135). In Phase 1, the vocational vehicle emission control system identifier is tire rolling 

resistance, plus any innovative and advanced technologies.

The number of proposed emission control systems for greenhouse gas emissions in Phase 

2 has increased significantly. For example, the engine, transmission, axle configuration, tire 

radius, and idle reduction system are control systems that can be evaluated on-cycle in Phase 2 

(i.e. these technologies’ performance can now be input to GEM), but could not be evaluated in 

Phase 1. Due to the complexity in determining greenhouse gas emissions as proposed in Phase 

2, the agencies do not believe that we can unambiguously determine whether or not a vehicle is 

in a certified condition through simply comparing information that could be made available on 
Page 387 of 850

an emission control label with the components installed on a vehicle. Therefore, EPA proposes 

to remove the requirement to include the emission control system identifiers required in 40 CFR 

1037.135(b)(6) and in Appendix III to 40 CFR part 1037 from the emission control labels for 

vocational vehicles certified to the primary Phase 2 standards. However, the agencies may

finalize requirements to maintain some label content to facilitate a limited visual inspection of

key vehicle parameters that can be readily observed. Such requirements may be very similar to 

the labeling requirements from the Phase 1 rulemaking, though we would want to more carefully 

consider the list of technologies that would allow for the most effective inspection. We request 

comment on an appropriate list of candidate technologies that would properly balance the need to 

limit label content with the interest in providing the most useful information for inspectors to 

confirm that vehicles have been properly built. EPA is not proposing to modify the existing 

emission control labels for vocational vehicles certified to the Phase 1 CO2 standards.

Under the agencies’ existing authorities, manufacturers must provide detailed build 

information for a specific vehicle upon our request. Our expectation is that this information 

should be available to us via e-mail or other similar electronic communication on a same-day

basis, or within 24 hours of a request at most. We request comment on any practical limitations 

in promptly providing this information. We also request comment on approaches that would 

minimize burden for manufacturers to respond to requests for vehicle build information and 

would expedite an authorized compliance inspector’s visual inspection. For example, the 

agencies have started to explore ideas that would provide inspectors with an electronic method to 

identify vehicles and access on-line databases that would list all of the engine-specific and 

vehicle-specific emissions control system information. We believe that electronic and Internet 

technology exists today for using scan tools to read a bar code or radio frequency identification 

tag affixed to a vehicle that would then lead to secure on-line access to a database of 

manufacturers’ detailed vehicle and engine build information. Our exploratory work on these 

ideas has raised questions about the level of effort that would be required to develop, implement 

and maintain an information technology system to provide inspectors real-time access to this 

information. We have also considered questions about privacy and data security. We request 

comment on the concept of electronic labels and database access, including any available 

information on similar systems that exist today and on burden estimates and approaches that 

could address concerns about privacy and data security. Based on new information that we 

receive, we may consider initiating a separate rulemaking effort to propose and request comment 

on implementing such an approach.

(b) End of Year Reports

In the Phase 1 program, manufacturers participating in the ABT program provided 90 day

and 270 day reports to EPA and NHTSA after the end of the model year. The agencies adopted 

two reports for the initial program to help manufacturers become familiar with the reporting 

process. For the HD Phase 2 program, the agencies propose to simplify reporting such that 

manufacturers would only be required to submit one end of the year report 120 days after the end 

of the model year with the potential to obtain approval for a delay up to 30 days. We welcome 

comment on this proposed revision. 
Page 388 of 850

(c) Delegated Assembly

The proposed standards for vocational vehicles are based on the application of a wide 

range of technologies. Certifying vehicle manufacturers manage their compliance demonstration 

to reflect this range of technologies by describing their certified configurations in the application 

for certification. In many cases, these technologies are designed and assembled (or installed) 

directly by the certifying vehicle manufacturer, which is typically the chassis manufacturer. In 

these cases, it is straightforward to assign the responsibility to the certifying vehicle 

manufacturer for ensuring that vehicles are in their proper certified configuration when sold to 

the ultimate user. In Phase 1, the only vehicle technology available for certified vocational 

vehicles was LRR tires. Because these are generally installed by the chassis manufacturer, there 

would have been no need to rely on a second stage manufacturer for purposes of certification. 

In Phase 2, the agencies are considering certain technologies where the certifying vehicle 

manufacturer may want or need to rely on a downstream manufacturing company (a secondary

vehicle manufacturer) to take steps to assemble or install certain components or technologies to 

bring the vehicle into a certified configuration. A similar relationship between manufacturers 

applies with aftertreatment devices for certified engines. EPA has adopted “delegated assembly” 

provisions for engines at 40 CFR 1068.261 to describe how manufacturers can share compliance 

responsibilities through these cooperative assembly procedures. 

We are proposing to take a similar approach for vehicle-based GHG standards in 40 CFR 

part 1037. The delegated assembly provisions as proposed for GHG standards are focused on 

add-on features to reduce aerodynamic drag, and on air conditioning systems. This may occur, 

for example, if the certifying manufacturer sells a cab-complete chassis to a secondary vehicle 

manufacturer, which in turn installs a box with the appropriate aerodynamic accessories to 

reduce drag losses. To the extent certifying manufacturers rely on secondary vehicle 

manufacturers to bring the vehicle into a certified configuration, the following provisions would

apply:

 The certifying manufacturer would describe their approach to delegated assembly

in the application for certification.

 The certifying manufacturer would create installation instructions to describe how 

the secondary vehicle manufacturer would bring the vehicle into a certified 

configuration.

 The certifying manufacturer would have a contractual agreement with each 

affected secondary vehicle manufacturer obligating the secondary vehicle 

manufacturer to build each vehicle into a certified configuration and to provide 

affidavits confirming proper assembly procedures, and to provide information 

regarding deployment of each type of technology (if there are technology options 

that relate to different GEM input values).

The delegated assembly provisions are most relevant to vocational vehicles, but we are 

not proposing to limit these provisions to vocational vehicles. Similarly, we expect that 

aerodynamic devices and air conditioning systems are the most likely technologies for which 

delegated assembly is appropriate, but we are not proposing to limit the use of delegated 

assembly to these technologies.
Page 389 of 850

Secondary manufacturers (such as body builders) that build complete vehicles from 

certified chassis are obligated to comply with the emission-related installation instructions 

provided by the certifying manufacturer. Secondary manufacturers that build complete vehicles 

from exempted chassis are obligated to comply with all of the regulations.

The draft regulations at §1037.621 describe further detailed provisions related to 

delegated assembly. We request comment on all aspects of these provisions. In particular, we 

request comment on how the procedures should be applied more broadly or more narrowly for 

specific technologies. We also request comment on any further modifications that should be 

made to the delegated assembly provisions to reflect the nature of manufacturing relationships or 

technologies that are specific to greenhouse gas standards for heavy-duty highway vehicles.

(d) Demonstrating Compliance with Proposed HFC Leakage Standards

EPA is proposing requirements for vocational chassis manufacturers to demonstrate 

reductions in direct emissions of HFC in their A/C systems and components through a designbased method. The method for calculating A/C leakage is the same as was adopted in Phase 1 

for tractors and HD pickups and vans. It 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. 

As is done currently for other HD vehicles, vocational chassis manufacturers would choose from 

a menu of A/C equipment and components used in their vehicles in order to establish leakage 

scores, to characterize their A/C system leakage performance. The percent leakage per year 

would then be calculated as this score divided by the system refrigerant capacity.

Consistent with the light-duty rule and the Phase 1 program for other HD vehicles, EPA 

is proposing a requirement that vocational chassis manufacturers compare the components of a 

vehicle’s A/C system with a set of leakage-reduction technologies and actions that is based 

closely on that developed through the Improved Mobile Air Conditioning program and SAE 

International (as SAE Surface Vehicle Standard J2727, “HFC-134a, Mobile Air Conditioning 

System Refrigerant Emission Chart,” August 2008 version). See generally 75 FR 25426. The 

SAE J2727 approach was developed from laboratory testing of a variety of A/C related 

components, and EPA believes that the J2727 leakage scoring system generally represents a 

reasonable correlation with average real-world leakage in new vehicles. This approach 

associates each component with a specific leakage rate in grams per year that is identical to the 

values in J2727 and then sums together the component leakage values to develop the total A/C 

system leakage. Unlike the light-duty program, in the heavy-duty vehicle program, the total A/C 

leakage score is divided by the value of the total refrigerant system capacity to develop a percent 

leakage per year. EPA believes that the design-based approach results in estimates of likely

leakage emissions reductions that are comparable to those that would result from performancebased testing.

Consistent with HD GHG Phase 1, EPA is not proposing 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 HD Phase 1 program and the 

light-duty rule, where we propose to require that manufacturers attest to the durability of 

components and systems used to meet the CO2 standards (see 75 FR 25689), we propose to 
Page 390 of 850

require that manufacturers of heavy-duty vocational vehicles attest to the durability of these 

systems, and provide an engineering analysis that demonstrates component and system 

durability.

(e) Glider Vehicles

EPA is proposing to not exempt glider vehicles from the Phase 2 GHG emission and fuel 

consumption standards. 327 Gliders and glider kits are exempt from NHTSA’s Phase 1 fuel 

consumption standards. EPA’s interim provisions of Phase 1 exempted glider vehicles produced 

by small businesses from the Phase 1 CO2 emission standards but did not include such a blanket 

exemption for other glider vehicles.328 Thus, some glider vehicles are already subject to the 

requirement to obtain a vehicle certificate prior to introduction into commerce as a new vehicle. 

However, the agencies believe glider manufacturers may not understand how these regulations 

apply to them, resulting in a number of uncertified vehicles.

EPA is concerned about adverse economic impacts on small businesses that assemble 

glider kits and glider vehicles. Therefore, EPA is proposing a new provision that would 

grandfather existing small businesses, but cap annual production based on recent sales. This 

approach is consistent with the approach recommended by the Small Business Advocacy Review 

Panel, which believed there should be an allowance to produce some glider vehicles for 

legitimate purposes. EPA requests comment on whether any special provisions would be needed 

to accommodate glider vehicles. See Section XIV.B for additional discussion of the proposed 

requirements for glider vehicles.

Similarly, NHTSA is considering including gliders under its Phase 2 program. The 

agencies request comment on their respective considerations. We believe that the agencies 

potentially having different policies for glider kits and glider vehicles under the Phase 2 program 

would not result in problematic disharmony between the NHTSA and EPA programs, because of 

the small number of vehicles that would be involved. EPA believes that its proposed changes 

would result in the glider market returning to the pre-2007 levels, in which fewer than 1,000 

glider vehicles would be produced in most years. Given that a large fraction of these vehicles 

would be exempted from EPA regulations because they would be produced by qualifying small 

businesses, they would thus, in practice, be treated the same under EPA and NHTSA 

regulations. Only non-exempt glider vehicles would be subject to different requirements under 

the NHTSA and EPA regulations. However, we believe that this is unlikely to exceed a few 

hundred vehicles in any year, which would be few enough not to result in any meaningful 

disharmony between the two agencies.

 

327 Glider vehicles are new vehicles produced to accept rebuilt engines (or other used engines) along with used axles 

and/or transmissions. The common term “glider kit” is used here primarily to refer to an assemblage of parts into 

which the used/rebuilt engine is installed.

328 Rebuilt engines used in glider vehicles are subject to EPA criteria pollutant emission standards applicable for the 

model year of the engine. See 40 CFR 86.004-40 for requirements that apply for engine rebuilding. Under existing 

regulations, engines that remain in their certified configuration after rebuilding may continue to be used.
Page 391 of 850

With regard to NHTSA’s safety authority over gliders, the agency notes that it has 

become increasingly aware of potential noncompliance with its regulations applicable to 

gliders. NHTSA has learned of manufacturers who are creating glider vehicles that are new 

vehicles under 49 CFR 571.7(e); however, the manufacturers are not certifying them and 

obtaining a new VIN as required. NHTSA plans to pursue enforcement actions as applicable 

against noncompliant manufacturers. In addition to enforcement actions, NHTSA may consider 

amending 49 CFR 571.7(e) and related regulations as necessary in the future. NHTSA believes 

manufacturers may not be using this regulation as originally intended.

(3) Proposed Compliance Flexibility Provisions

EPA and NHTSA are proposing three flexibility provisions specifically for vocational 

vehicle manufacturers in Phase 2. These are an averaging, banking and trading program for CO2

emissions and fuel consumption credits, provisions for off-cycle credits for technologies that are 

not included as inputs to the GEM, and optional chassis certification. The agencies are also 

proposing to remove or modify several Phase 1 interim provisions, as described below. 

Program-wide compliance flexibilities are discussed in Section I.B.3 to I.C.1.

(a) Averaging, Banking, and Trading (ABT) Program

Averaging, banking, and trading of emission credits have been an important part of many

EPA mobile source programs under CAA Title II. ABT provisions provide manufacturers 

flexibilities that assist in the efficient development and implementation of new technologies and 

therefore enable new technologies to be implemented at a more aggressive pace than without 

ABT. NHTSA and EPA propose to carry-over the Phase 1 ABT provisions for vocational 

vehicles into Phase 2, as it is an important way to achieve each agency’s programmatic goals. 

ABT is also discussed in Section I and Section III.F.1.

Consistent with the Phase 1 averaging sets, the agencies propose that chassis 

manufacturers may average SI-powered vocational vehicle chassis with CI-powered vocational 

vehicle chassis, within the same vehicle weight class group. In Phase 1, all vocational and 

tractor chassis within a vehicle weight class group were able to average with each other, 

regardless of whether they were powered by a CI or SI engine. The proposed Phase 2 approach 

would continue this. The only difference is that in Phase 2, there would be different numerical 

standards set for the SI-powered and CI-powered vehicles, but that would not need to alter the 

basis for averaging. This is consistent with the Phase 1 approach where, for example, Class 8 

day cab tractors, Class 8 sleeper cab tractors and Class 8 vocational vehicles each have different

numerical standards, while they all belong to the same averaging set. 

As discussed in V. E. (1) (c), EPA is proposing to change the useful life for LHD 

vocational vehicles for GHG emissions from the current 10 years/110,000 miles to 15 

years/150,000 miles to be consistent with the useful life of criteria pollutants recently updated in 

EPA’s Tier 3 rule. For the same reasons, EPA is also proposing a useful life adjustment for HD 

pickups and vans, as described in Section VI.E.(1). According to the credits calculation formula

at 40 CFR 1037.705 and 49 CFR 535.7, useful life in miles is a multiplicative factor included in 

the calculation of CO2 and fuel consumption credits. In order to ensure that banked credits 

would maintain their value in the transition from Phase 1 to Phase 2, NHTSA and EPA propose 
Page 392 of 850

an interim vocational vehicle adjustment factor of 1.36 for credits that are carried forward from 

Phase 1 to the MY 2021 and later Phase 2 standards. 329 Without this adjustment factor the 

proposed change in useful life would effectively result in a discount of banked credits that are 

carried forward from Phase 1 to Phase 2, which is not the intent of the change in the useful life.

The agencies do not believe that this proposed adjustment would result in a loss of program 

benefits because there is little or no deterioration anticipated for CO2 emissions and fuel 

consumption over the life of the vehicles. Also, the carry-forward of credits is an integral part of 

the program, helping to smoothing the transition to the new Phase 2 standards. The agencies 

believe that effectively discounting carry-forward credits from Phase 1 to Phase 2 would be 

unnecessary and could negatively impact the feasibility of the proposed Phase 2 standards. EPA 

and NHTSA request comment on all aspects of the averaging, banking, and trading program.

(b) Innovative and Off-Cycle Technology Credits

In Phase 1, the agencies adopted an emissions and fuel consumption credit generating 

opportunity that applied to innovative technologies that reduce fuel consumption and CO2

emissions. These technologies were required to not be in common use with heavy-duty vehicles 

before the 2010MY and not reflected in the GEM simulation tool (i.e., the benefits are “offcycle”). See 76 FR at 57253. The agencies propose to largely continue the Phase 1 innovative 

technology program but to redesignate it as an off-cycle program for Phase 2. The agencies 

propose to maintain that, in order for a manufacturer to receive credits for Phase 2, the off-cycle 

technology would still need to meet the requirement that it was not in common use prior to MY 

2010.

The agencies recognize that there are emerging technologies today that are being 

developed, but would not be accounted for in the GEM tool, and therefore would be considered 

off-cycle. These technologies could include systems such as electrified accessories, air 

conditioning system efficiency, and aerodynamics for vocational vehicles beyond those tested 

and pre-approved in the HD Phase 2 program. Such off-cycle technologies could 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. More information

about off-cycle technology credits can be found at Section I.C.1.c.

As in Phase 1, the agencies are proposing to continue to provide two paths for approval 

of the test procedure to measure the CO2 emissions and fuel consumption reductions of an offcycle technology used in vocational vehicles. See 40 CFR 1037.610 and 49 CFR 535.7. The 

first path would not require a public approval process of the test method. A manufacturer could

use “pre-approved” test methods for HD vehicles including the A-to-B chassis testing, 

powerpack testing or on-road testing. A manufacturer may also use any developed test 

procedure that has known quantifiable benefits. A test plan detailing the testing methodology

 

329 See 40 CFR 1037.150(s) and 49 CFR 535.7
Page 393 of 850

would be required to be approved prior to collecting any test data. The agencies are also 

proposing to continue the second path, which includes a public approval process of any testing 

method that could have questionable benefits (i.e., an unknown usage rate for a 

technology). Furthermore, the agencies are proposing to modify their provisions to clarify what

documentation must be submitted for approval, which would align them with provisions in 40 

CFR 86.1869-12. NHTSA is separately proposing to prohibit credits from technologies 

addressed by any of its crash avoidance safety rulemakings (i.e., congestion management 

systems). See also 77 FR at 62733 (discussion of similar issue in the light duty greenhouse 

gas/fuel economy regulations). We welcome recommendations on how to improve or streamline 

the off-cycle technology approval process.

There are some technologies that are entering the market today, and although our model 

does not have the capability to simulate the effectiveness over the test cycles, there are reliable 

estimates of effectiveness available to the agencies. These are proposed to be recognized in our 

HD Phase 2 certification procedures as pre-defined technologies, and would not be considered 

off-cycle. Examples of such technologies for vocational vehicles include 6x2 axles and axle 

lubricants. These default effectiveness values would be used as valid inputs to GEM. The 

projected effectiveness of each vocational vehicle technology is discussed in the draft RIA 

Chapter 2.9.

The agencies propose that the approval for Phase 1 innovative technology credits 

(approved prior to 2021 MY) would be carried into the Phase 2 program on a limited basis for 

those technologies where the benefit is not accounted for in the Phase 2 test procedure. 

Therefore, the manufacturers would not be required to request new approval for any innovative 

credits carried into the off-cycle program, but would have to demonstrate the new cycle does not 

account for these improvements beginning in the 2021 MY. The agencies believe this is 

appropriate because technologies, such as those related to the transmission or driveline, may no 

longer be “off-cycle” because of the addition of these technologies into the Phase 2 version of 

GEM. The agencies also seek comments on whether off-cycle technologies in the Phase 2 

program should be limited by infrequent common use and by what model years, if any. We also 

seek comments on an appropriate penetration rate for a technology not to be considered in 

common use.

(c) Optional Chassis Certification

In Phase 2, the agencies are proposing to continue the Phase 1 provisions allowing the 

optional chassis certification of vehicles over 14,000 pounds GVWR. In Phase 1 the agencies 

allowed manufacturers the option to choose to comply with heavy-duty pickup or van standards, 

for incomplete vehicles that were identical to those on complete pickup truck or van 

counterparts, with respect to most components that affect GHG emissions and fuel consumption, 

such as engines, cabs, frames, transmissions, axles, and wheels. The incomplete vehicles would 

typically be produced as cab-complete vehicles. For example, a manufacturer could certify

under this allowance an incomplete pickup truck that includes the cab, but not the bed. The 
Page 394 of 850

Phase 1 program also includes provisions that allow manufacturers to include some Class 4 and 

Class 5 vehicles in averaging sets subject to the chassis-based HD pickup and van standards, 

rather than the vocational vehicle program.330

This optional chassis certification of vehicles over 14,000 pounds applies for greenhouse 

gas emission standards in Phase 1, but not for criteria pollutant emission standards. We revisited 

this issue in the recent Tier 3 final rule, where we revised the regulation to allow this same 

flexibility relative to exhaust emission standards for criteria pollutants. However, EPA is now 

seeking comment on the proper approach for certifying vehicles above 14,000 lbs GVWR, 

because there are lingering questions about how best to align the certification processes for GHG 

emissions and for criteria pollutants. The agencies are requesting comment on several issues on 

this topic, including whether there should be an upper weight limit to this allowance. See 

Section XIV.A.2 for the issues on which the agencies seek comment with respect to chassis and 

engine certification for GHG and criteria pollutants for vehicles opting into the HD pickup and 

van program.

(d) Phase 1 Flexibilities Not Proposed for Phase 2

As described above in Section I, the agencies are not proposing to provide advanced 

technology credits in Phase 2. These technologies had been defined in Phase 1 as hybrid 

powertrains, Rankine cycle engines, all-electric vehicles, and fuel cell vehicles (see 40 CFR 

1037.150(i)), at a 1.5 credit value with the purpose to promote the early implementation of 

advanced technologies that were not expected to be widely adopted in the market in the 2014 to 

2018 time frame. Our feasibility assessment for the proposed Phase 2 vocational vehicle 

standards includes a projection of the use of hybrid powertrains as described earlier in this 

section; therefore the agencies believe it would no longer be appropriate to provide extra credit 

for this technology. As noted above, waste heat recovery is not projected to be utilized for 

vocational vehicles within the time frame of Phase 2. While the agencies are not proposing to 

premise the Phase 2 vocational vehicle standards on fuel cells or electric vehicles, we expect that 

any vehicle certified with this technology would provide such a large credit to a manufacturer 

that an additional incentive credit would not be necessary. We welcome comments on the need 

for such incentives, including information on why an incentive for specific technologies in this 

time frame may be warranted, recognizing that the incentive would result in reduced benefits in 

terms of CO2 emissions and fuel use due to the Phase 2 program.

The agencies are not proposing to extend early credits to manufacturers who comply

early with Phase 2 standards, because the ABT program from Phase 1 will be available to 

manufacturers and this displaces the need for early credits (see 40 CFR 1037.150(a)). Please see 

the more complete discussion of this above in Section I.

Another Phase 1 interim flexibility that the agencies are not proposing to continue in 

Phase 2 is the flexibility known as the “loose engine” provision, whereby SI engines sold to 

 

330 See 76 FR 57259-57260, September 15, 2011 and 78 FR 36374, June 17, 2013
Page 395 of 850

chassis manufacturers and intended for use in vocational vehicles need not meet the separate SI 

engine standard (see preamble Section II and draft RIA Chapter 2.6), and instead may be 

averaged with the manufacturer’s HD pickup and van fleet. We believe the benefits this 

particular flexibility offers for manufacturers in the interim between Phase 1 and Phase 2 would 

diminish considerably in Phase 2. The agencies are proposing a Phase 2 SI engine standard that 

is no more stringent than the MY 2016 SI engine standard adopted in Phase 1, while the 

proposed Phase 2 standards for the HD pickup and van fleet would be progressively more 

stringent through MY 2027. The primary certification path designed in the Phase 1 program for 

both CI and SI engines sold separately and intended for use in vocational vehicles was that they

be engine certified while the vehicle would be GEM certified under the GHG rules. In Phase 2 

the agencies propose to continue this as the certification path for such engines intended for 

vocational vehicles. See the draft RIA Chapter 2.6 for further discussion of the separate engine 

standard for SI engines intended for vocational vehicles. 

(e) Other Phase 1 Interim Provisions

In HD Phase 1, EPA adopted provisions to delay the onboard diagnostics (OBD) 

requirements for heavy-duty hybrid powertrains (see 40 CFR 86.010-18(q)). This provision 

delayed full OBD requirements for hybrids until MY 2016 and MY 2017. In discussion with 

manufacturers during the development of Phase 2, the agencies have learned that meeting the onboard diagnostic requirements for criteria pollutant engine certification continues to be a 

potential impediment to adoption of hybrid systems. See Section XIII.A.1 for a discussion of 

regulatory changes proposed to reduce the non-GHG certification burden for engines paired with 

hybrid powertrain systems. 

Also in Phase 1, EPA adopted provisions that reinforced the fact that we were setting 

GHG emissions from the tailpipe of heavy-duty vehicles. Therefore, we treated all electric 

vehicles as having zero emissions of CO2, CH4, and N2O (see 40 CFR 1037.150(f)). Similarly, 

NHTSA adopted regulations in Phase 1 that set the fuel consumption standards based on the fuel 

consumed by the vehicle. The agencies also did not require emission testing for electric vehicles 

in Phase 1. The agencies considered the potential unintended consequence of ignoring upstream 

emissions from the charging of heavy-duty battery-electric vehicles. In our assessment, we have 

observed that the few all-electric heavy-duty vocational vehicles that have been certified are 

being produced in very small volumes in MY2014. As we look to the future, we project very

limited adoption of electric vocational vehicles into the market; therefore, we believe that this 

provision is still appropriate. Unlike the MY2012-2016 light-duty rule, which adopted a cap 

whereby upstream emissions would be counted after a certain volume of sales (see 75 FR 25434-

25436), we believe there is no need to propose a cap for vocational vehicles because of the 

infrequent projected use of EV technologies in the Phase 2 timeframe. In Phase 2, we propose to 

continue to deem electric vehicles as having zero CO2, CH4, and N2O emissions as well as zero 

fuel consumption. We welcome comments on this approach.
Page 396 of 850

VI. Heavy-duty Pickups and Vans

A. Introduction and Summary of Phase 1 HD Pickup and Van Standards

In the Phase 1 rule, EPA and NHTSA established GHG and fuel consumption standards 

and a program structure for complete Class 2b and 3 heavy-duty vehicles (referred to in these 

rules as “HD pickups and vans”), as described below. The Phase 1 standards began to be 

phased-in in MY 2014 and the agencies believe the program is working well. The agencies are 

proposing to retain most elements from the structure of the program established in the Phase 1 

rule for the Phase 2 program while proposing more stringent Phase 2 standards for MY 2027, 

phased in over MYs 2021-2027, that would require additional GHG reductions and fuel 

consumption improvements. The MY 2027 standards would remain in place unless and until 

amended by the agencies.

Heavy-duty vehicles with GVWR between 8,501 and 10,000 lb are classified in the 

industry as Class 2b motor vehicles. Class 2b includes vehicles classified as medium-duty

passenger vehicles (MDPVs) such as very large SUVs. Because MDPVs are frequently used 

like light-duty passenger vehicles, they are regulated by the agencies under the light-duty vehicle 

rules. Thus the agencies did not adopt additional requirements for MDPVs in the Phase 1 rule 

and are not proposing 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 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. 

Most of these vehicles are produced by companies with major light-duty markets in the United 

States, primarily Ford, General Motors, and Chrysler. Often, the technologies available to 

reduce fuel consumption and GHG emissions from this segment are similar to the technologies 

used for the same purpose on light-duty pickup trucks and vans, including both engine efficiency 

improvements (for gasoline and diesel engines) and vehicle efficiency improvements. 

In the Phase 1 rule EPA adopted GHG standards for HD pickups and vans based on the 

whole vehicle (including the engine), expressed as grams of CO2 per mile, consistent with the 

way these vehicles are regulated by EPA today for criteria pollutants. NHTSA adopted 

corresponding gallons per 100 mile fuel consumption standards that are likewise based on the 

whole vehicle. This complete vehicle approach adopted by both agencies for HD pickups and 

vans was consistent with the recommendations of the NAS Committee in its 2010 Report. EPA 

and NHTSA adopted a structure for the Phase 1 HD pickup and van standards that in many

respects paralleled long-standing NHTSA CAFE standards and more recent coordinated EPA 

GHG standards for manufacturers’ fleets of new light-duty vehicles. These commonalities 

include a new vehicle fleet average standard for each manufacturer in each model year and the 

determination of these fleet average standards based on production volume-weighted targets for 

each model, with the targets varying based on a defined vehicle attribute. Vehicle testing for 

both the HD and light-duty vehicle programs is conducted on chassis dynamometers using the 
Page 397 of 850

drive cycles from the EPA Federal Test Procedure (Light-duty FTP or “city” test) and Highway

Fuel Economy Test (HFET or “highway” test).331

For the light-duty GHG and fuel economy

332 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).333 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. EISA requires that 

NHTSA study “the appropriate metric for measuring and expressing commercial medium- and 

heavy-duty vehicle and work truck fuel efficiency performance, taking into consideration, among 

other things, the work performed by such on-highway vehicles and work trucks...” 49 U.S.C. 

32902 (k) (1)(B).334 For HD pickups and vans, the agencies also set standards based on vehicle 

attributes, but used a work-based metric as the attribute rather 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 HD pickup or van. EPA and NHTSA therefore 

finalized Phase 1 standards for HD pickups and vans based on a “work factor” attribute that 

combines the vehicle’s payload and towing capabilities, with an added adjustment for 4-wheel 

drive vehicles. See generally 76 FR 57161-62.

For Phase 1, the agencies adopted provisions such that each manufacturer’s fleet average 

standard is 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). The Phase 1 curves are shown in the figures below for reference and 

are described in detail in the Phase 1 final rule.335 The agencies established separate curves for 

diesel and gasoline HD pickups and vans. The agencies are proposing to continue to use the 

work-based attribute and gradually declining standards approach for the Phase 2 standards, as 

discussed in Section VI.B. below. Note that this approach does not create an incentive to reduce 

the capabilities of these vehicles because less capable vehicles are required to have 

proportionally lower emissions and fuel consumption targets.

 

331 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).

332 Light duty fuel economy standards are expressed as miles per gallon (mpg), which is inverse to the HD fuel 

consumption standards which are expressed as gallons per 100 miles.

333 EISA requires CAFE standards for passenger cars and light trucks to be attribute-based; See 49 U.S.C. 

32902(b)(3)(A).

334 The NAS 2010 report likewise recommended standards recognizing the work function of HD vehicles. See 76 

FR 57161/2.

335 The Phase 1 Final Rule provides a full discussion of the standard curves including the equations and coefficients. 

See 76 FR 57162-57165, September 15 2011. The standards are also provided in the regulations at 40 CFR 

1037.104.
Page 398 of 850

Figure VI-1 EPA Phase 1 CO2 Target Standards and NHTSA Fuel Consumption Target Standards for Diesel 

HD Pickups and Vans336

 

336 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 the Phase 1 preamble Section II.C (d)(ii).

300

350

400

450

500

550

600

650

700

750

800

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

Work Factor (pounds)

CO2 (grams per mile)

2.95

3.95

4.95

5.95

6.95

Fuel Consumption (gallons per 100 miles)

Diesel Vehicles

2018

2017

2015

2014

2016

300

350

400

450

500

550

600

650

700

750

800

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

Work Factor (pounds)

CO2 (grams per mile)

2.95

3.95

4.95

5.95

6.95

Fuel Consumption (gallons per 100 miles)

Diesel Vehicles

2018

2017

2015

2014

2016
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Figure VI-2 EPA Phase 1 CO2 Target Standards and NHTSA Fuel Consumption Target Standards for 

Gasoline HD Pickups and Vans

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
Page 400 of 850

EPA phased in its 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 the set of target standard curves 

shown above, with increasing stringency in each model year. The final EPA Phase 1 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 MY 2010 baseline. EPA also finalized a compliance 

alternative whereby manufacturers can phase in different percentages: 15-20-67-67-67-100 

percent of the model year 2019 standards stringency level in model years 2014-2015-2016-2017-

2018-2019, respectively. This compliance alternative parallels and is equivalent to NHTSA’s 

first alternative described below.

NHTSA’s Phase 1 program allows 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. This option is consistent with EISA requirements that 

NHTSA provide 4 years lead-time and 3 years of stability for standards. 49 U.S.C. Section 

32902 (k)(3). The second alternative uses target curves that are equivalent to EPA’s 40-60-100 

percent target curves in model years 2016-2017-2018, respectively. Stringency for the 

alternatives in Phase 1 was selected by the agencies to allow a manufacturer, through the use of 

the credit carry-forward and carry-back provisions that the agencies also finalized, to meet both 

NHTSA fuel efficiency and EPA GHG emission standards using a single compliance strategy. If 

a manufacturer cannot meet an applicable standard in a given model year, it may make up its 

shortfall by over-complying in a subsequent year. NHTSA also allows 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 Phase 1 phase-in options are summarized in Table VI-1.

Table VI-1 Phase 1 Standards Phase-in Options

2014 2015 2016 2017 2018 2019

EPA Primary Phase-in 15% 20% 40% 60% 100% 100%

EPA Compliance Option 15% 20% 67% 67% 67% 100%

NHTSA First Option 0% 0% 67% 67% 67% 100%

NHTSA Second Option 0% 0% 40% 60% 100% 100%

The form and stringency of the Phase 1 standards curves are based on the performance of 

a set of vehicle, engine, and transmission technologies expected (although not required) to be 

used to meet the GHG emissions and fuel economy standards for model year 2012-2016 lightduty vehicles, with full consideration of how these technologies are likely to perform in heavyduty vehicle testing and use. All of these technologies are already in use or have been 

announced for upcoming model years in some light-duty vehicle models, and some are in use in 

a portion of HD pickups and vans as well. The technologies include:

advanced 8-speed automatic transmissions

aerodynamic improvements
Page 401 of 850

electro-hydraulic power steering

engine friction reductions

improved accessories

low friction lubricants in powertrain components

lower rolling resistance tires

lightweighting

gasoline direct injection

diesel aftertreatment optimization

air conditioning system leakage reduction (for EPA program only)

B. Proposed HD Pickup and Van Standards

As described in this section, NHTSA and EPA are proposing more stringent MY 2027 

and later Phase 2 standards that would be phased in over model years 2021-2027. The agencies 

are proposing standards based on a year-over-year increase in stringency of 2.5 percent over

MYs 2021-2027 for a total increase in stringency for the Phase 2 program of about 16 percent

compared to the MY 2018 Phase 1 standard. Note that an individual manufacturer’s fleet-wide 

target may differ from this stringency increase due to changes in vehicle sales mix and changes 

in work factor. The agencies have analyzed several alternatives which are discussed in this 

section below and in Section X. In particular, we are requesting comment not only on the 

proposed standards but also particularly on the Alternative 4 standard which would result in 

approximately the same Phase 2 program stringency increase of about 16 percent compared to 

Phase 1 but would do so two years earlier, in MY 2025 rather than in MY 2027. The Alternative 

4 phase in from 2021-2025 would be based on a year-over-year increase in stringency of 3.5

percent, as discussed below. While we believe the proposed preferred alternative is feasible in 

the time frame of this rule, and that Alternative 4 could potentially be feasible, the two phase-in 

schedules differ in the required adoption rate of advanced technologies for certain high volume 

vehicle segments. The agencies’ analysis essentially shows that the additional lead-time 

provided by the preferred alternative would allow manufacturers to more fully utilize lower cost 

technologies thereby reducing the adoption rate of more advanced higher cost technologies such 

as strong hybrids. As discussed in more detail in C.8 below, both of the considered phase-ins 

require comparable penetration rates of several non-hybrid technologies with some approaching 

100 percent penetration. However, as discussed below, the additional lead-time provided by

Alternative 3 would allow manufacturers more flexibility to fully utilize these non-hybrid 

technologies to reduce the number of hybrids needed compared to Alternative 4. Alternative 4 

would additionally require significant penetration of strong hybridization. We request 

comments, additional information, data, and feedback to determine the extent to which such

adoption would be realistic within the MY 2025 timeframe.

When considering potential Phase 2 standards, the agencies anticipate that the 

technologies listed above that were considered in Phase 1 will continue to be available in the 

future if not already applied under Phase 1 standards and that additional technologies will also be 

available:
Page 402 of 850

 advanced engine improvements for friction reduction and low friction lubricants

 improved engine parasitics, including fuel pumps, oil pumps, and coolant pumps

 valvetrain variable lift and timing

 cylinder deactivation

 direct gasoline injection

 cooled exhaust gas recirculation

 turbo downsizing of gasoline engines

 Diesel engine efficiency improvements

 downsizing of diesel engines

 8-speed automatic transmissions

 electric power steering

 high efficiency transmission gear boxes and driveline

 further improvements in accessory loads

 additional improvements in aerodynamics and tire rolling resistance

 low drag brakes

 mass reduction

 mild hybridization

 strong hybridization

Sections VI.C. and D below and Section 2 of the Draft RIA provide a detailed analysis of 

these and other potential technologies for Phase 2, including their feasibility, costs, and 

effectiveness and projected application rates for reducing fuel consumption and CO2 emissions 

when utilized in HD pickups and vans. Sections VI.C and D and Section X also discuss the 

selection of the proposed standards and the alternatives considered.

In addition to EPA’s CO2 emission standards and NHTSA’s fuel consumption standards 

for HD pickups and vans, EPA in Phase 1 also finalized standards for two additional GHGs —

N2O and CH4, as well as standards for air conditioning-related HFC emissions in the Phase 1 

rule. EPA is proposing to continue these standards in Phase 2. Also, consistent with CAA 

Section 202(a)(1), EPA finalized Phase 1 standards that apply to HD pickups and vans in use and 

EPA is proposing in-use standards for these vehicles in Phase 2. All of the proposed standards 

for these HD pickups and vans are discussed in more detail below. Program flexibilities and 

compliance provisions related to the standards for HD pickups and vans are discussed in Section 

VI.E.

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. A sizeable 

subset of these incomplete vehicles, often called cab-chassis vehicles, are sold by the vehicle 

manufacturers in configurations with complete cabs and 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. The Phase 1 

program includes provisions that allow manufacturers to include these incomplete vehicles as 
Page 403 of 850

well as some Class 4 through 6 vehicles to be regulated under the chassis-based HD pickup and 

van program (i.e. subject to the standards for HD pickups and vans), rather than the vocational 

vehicle program.337 The agencies are proposing to continue allowing such incomplete vehicles 

the option of certifying under either the heavy duty pickup and van standards or the standards for 

vocational vehicles. 

Phase 1 also includes optional compliance paths for spark-ignition engines identical to 

engines used in heavy-duty pickups and vans to comply with 2b/3 standards. See 40 CFR 

1037.150(m) and 49 CFR 535.5(a)(7). Manufacturers sell such engines as “loose engines” or 

install these engines in incomplete vehicles that are not cab-complete vehicles. The agencies are 

not proposing to retain the loose engine provisions for Phase 2. These program elements are 

discussed above in Section V.E. on vocational vehicles and XIV.A.2 on engines.

NHTSA and EPA request comment on all aspects of the proposed HD pickup and van 

standards and program elements described below and the alternatives discussed in Section X.

(1) Vehicle-Based Standards

For Phase 1, EPA and NHTSA chose to set vehicle-based standards whereby the entire 

vehicle is chassis-tested. The agencies propose to retain this approach for Phase 2. 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 (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 engines covered by CAA engine emission standards for criteria pollutants, 

expressed in grams per brake horsepower-hour. As a result, Class 2b and 3 complete vehicles 

share both substantive elements and a regulatory structure much more in common with light-duty

trucks than with the other heavy-duty vehicles.

Three of these features in common 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 

criteria pollutant and GHG 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 a single manufacturer is 

generally responsible for both engine and vehicle design. All of these factors together suggest 

that it is still appropriate and reasonable to base standards on performance of the vehicle as a 

whole, rather than to establish separate engine and vehicle GHG and fuel consumption standards, 

 

337 See 76 FR 57259-57260, September 15, 2011 and 78 FR 36374, June 17, 2013.
Page 404 of 850

as is being done for the other heavy-duty categories. The chassis-based standards approach for 

complete vehicles was also consistent with NAS recommendations and there was consensus in 

the public comments on the Phase 1 proposal supporting this approach. For all of these reasons, 

the agencies continue to believe that establishing chassis-based standards for Class 2b and 3 

complete vehicles is appropriate for Phase 2. 

(a) Work-Based Attributes

In developing the Phase 1 HD 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. Work-based measures such as payload 

and towing capability are key among the things that characterize differences in the design of 

vehicles, as well as differences in how the vehicles will be used. Vehicles in the 2b and 3 

categories have a wide range of payload and towing capacities. These work-based differences in 

design and in-use operation are 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 and the Phase 1 standards is conducted with the 

vehicle loaded to half of its payload capacity (rather than to a flat 300 lb as in the light-duty

program), and the correlation between test weight and fuel use is strong. 

Towing, on the other hand, does not directly factor into test weight as nothing is towed 

during the test. Hence, setting aside any interdependence between towing capacity and payload, 

only the higher curb weight caused by any 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 vehicle 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 heavyduty vehicle to buy. For passenger vans, seating capacity is of course a major consideration, but 

this correlates closely with payload weight.

For these reasons, EPA and NHTSA set Phase 1 standards for HD pickups and vans 

based on a “work factor” attribute that combines vehicle payload capacity and vehicle towing 

capacity, in lbs, with an additional fixed adjustment for four-wheel drive (4wd) vehicles. This 

adjustment accounts for the fact that 4wd, critical to enabling many off-road heavy-duty work 

applications, adds roughly 500 lb to the vehicle weight. The work factor is calculated as follows: 

75 percent maximum payload + 25 percent of maximum towing + 375 lbs if 4wd. Under this 

approach, target GHG and fuel consumption standards are determined for each vehicle with a 

unique work factor (analogous to a target for each discrete vehicle footprint in the light-duty

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. There was 

widespread support (and no opposition) for the work factor-based approach to standards and fleet 

average approach to compliance expressed in the comments we received on the Phase 1 rule. 

The agencies are proposing to continue using the work factor attribute for the Phase 2 standards 

and request comments on continuing this approach.
Page 405 of 850

Recognizing that towing is not reflected in the certification test for these vehicles, 

however, the agencies are requesting comment with respect to the treatment of towing in the 

work factor, especially for diesel vehicles. More specifically, does using the existing work factor 

equation create an inappropriate incentive for manufacturers to provide more towing capability 

than needed for some operators, or a disincentive for manufacturers to develop vehicles with 

intermediate capability. In other words, does it encourage “surplus” towing capability that has 

no value to vehicle owners and operators? We recognize that some owners and operators do 

actually use their vehicles to tow very heavy loads, and that some owners and operators who 

rarely use their vehicles to tow heavy loads nonetheless prefer to own vehicles capable of doing 

so. However, others may never tow such heavy loads and purchase their vehicles for other 

reasons, such as cargo capacity or off-road capability. Some of these less demanding (in terms 

of towing) users may choose to purchase gasoline-powered vehicles that are typically less 

expensive and have lower GCWR values, an indicator of towing capability. However, others 

could prefer a diesel engine more powerful than today’s gasoline engines but less powerful than 

the typical diesel engines found in 2b and 3 pickups today. In this context, the agencies are 

considering (but have not yet evaluated) four possible changes to the work factor and how it is 

applied. First, the agencies are considering revising the work factor to weight payload by 80 

percent and towing by 20 percent. Second, we are considering capping the amount of towing 

that could be credited in the work factor. For example, the work factors for all vehicles with 

towing ratings above 15,000 lbs could be calculated based on a towing rating of 15,000 lbs. It is 

important to be clear that such a provision would not limit the towing capability manufacturers 

could provide, but would only impact the extent to which the work factor would “reward” towing 

capability. Third, the agencies are considering changing the shape of the standard curve for 

diesel vehicles to become more flat at very high work factors. A flatter curve would mean that 

vehicles with very high work factors would be more similar to vehicles with lower work factors 

than is the case for the proposed curve. Thus, conceptually, flattening the curves at the high end 

might be appropriate if we were to determine that these high work factor vehicles actually 

operate in a manner more like the vehicles with lower work factors. For example, when not 

towing and when not hauling a full payload, heavy-duty pickup trucks with very different work 

factors may actually be performing the same amount of work. Finally, we are considering 

having different work factor formulas for pickups and vans, and are also further considering 

whether any of other changes should be applied differently to pickups than to vans. We 

welcome comments on both the extent to which surplus towing may be an issue and whether any

of the potential changes discussed above would be appropriate. Commenters supporting such 

changes are encouraged to also address any potential accompanying changes. For example, if we 

reweight the work factor, would other changes to the coefficients defining the target curves be 

important to ensure that standards remain at the maximum feasible levels. (Commenters should, 

however, recognize that average requirements will, in any event, depend on fleet mix, and the 

agencies expect to update estimates of future fleet mix before issuing a final rule).

As noted in the Phase 1 rule, the attribute-based CO2 and fuel consumption standards are 

meant to be as consistent as practicable 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 
Page 406 of 850

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.

(b) Standards 

The agencies are proposing Phase 2 standards based on analysis performed to determine 

the appropriate HD pickup and van Phase 2 standards and the most appropriate phase in of those 

standards. This analysis, described below and in the Draft RIA, considered:

projections of future U.S. sales for HD pickup and vans

the estimates of corresponding CO2 emissions and fuel consumption for these vehicles

forecasts of manufacturers’ product redesign schedules

the technology available in new MY 2014 HD pickups and vans to specify preexisting 

technology content to be included in the analysis fleet (the fleet of vehicles used as a 

starting point for analysis) extending through MY 2030

the estimated effectiveness, cost, applicability, and availability of technologies for HD 

pickup and vans

manufacturers’ ability to use credit carry-forward

the levels of technology that are projected to be added to the analysis fleet through MY 

2030 considering improvements needed in order to achieve compliance with the 

Phase 1 standards (thus defining the reference fleet–i.e., under the No-Action 

Alternative—relative to which to measure incremental impacts of Phase 2 standards), 

and

the levels of technology that are projected to be added to the analysis fleet through 

MY2030 considering further improvements needed in order to achieve compliance 

with standards defining each regulatory (action) alternative for Phase 2.

Based on this analysis, EPA is proposing CO2 attribute-based target standards shown in

Figure VI-3 and Figure VI-4, and NHTSA is proposing the equivalent attribute-based fuel 

consumption target standards, also shown in Figure VI-3 and Figure VI-4, applicable in model 

year 2021-2027. As shown in these tables, these standards would be phased in year-by-year 

commencing in MY 2021. The agencies are not proposing to change the standards for 2018-

2020 and therefore the standards would remain stable at the MY 2018 Phase 1 levels for MYs 

2019 and 2020. EISA requires four years of lead-time and three years stability for NHTSA 

standards and this period of lead-time and stability for 2018-2020 is consistent with the EISA 

requirements. For MYs 2021-2027, the agencies are proposing annual reductions in the 

standards as the primary phase-in of the Phase 2 standards. The proposed standards become 16 

percent more stringent overall between MY 2020 and MY 2027. This approach to the Phase 2 

standards as a whole can be considered a phase-in or implementation schedule of the proposed 

MY 2027 standards (which, as noted, would apply thereafter unless and until amended).

For EPA, Section 202(a) provides the Administrator with the authority to establish 

standards, and to revise those standards “from time to time,” thus providing the Administrator 

with considerable discretion in deciding when to revise the Phase 1 MY 2018 standards. EISA 

requires that NHTSA provide four full model years of regulatory lead time and three full model 
Page 407 of 850

years of regulatory stability for its fuel economy standards. 49 U.S.C. 32902(k)(3). Consistent 

with these authorities, the agencies are proposing more stringent standards beginning with MY 

2021 that consider the level of technology we predict can be applied to new vehicles in the 2021 

MY. EPA believes the proposed Phase 2 standards are consistent with CAA requirements 

regarding lead-time, reasonable cost, and feasibility, and safety. NHTSA believes the proposed 

Phase 2 standards are the maximum feasible under EISA. Manufacturers in the HD pickup and 

van market segment have relatively few vehicle lines and redesign cycles are typically longer 

compared to light-duty vehicles. Also, the timing of vehicle redesigns differs among 

manufacturers. To provide lead time needed to accommodate these longer redesign cycles, the 

proposed Phase 2 GHG standards would not reach their highest stringency until 2027. Although 

the proposed standards would become more stringent over time between MYs 2021 and 2027, 

the agencies expect manufacturers will likely strive to make improvements as part of planned 

redesigns, such that some model years will likely involve significant advances, while other 

model years will likely involve little change. The agencies also expect manufacturers to use 

program flexibilities (e.g., credit carry-forward provisions and averaging, banking, and trading 

provisions) to help balance compliance costs over time (including by allowing needed changes to 

align with redesign schedules). The agencies are proposing to provide stable standards in MYs 

2019-2020 in order to provide necessary lead time for Phase 2. However, for some 

manufacturers, the transition to the Phase 2 standards may begin earlier (e.g., as soon as MY 

2017) depending on their vehicle redesign cycles. Although standards are not proposed to 

change in MYs 2019-2020, manufacturers may introduce additional technologies in order to 

carry forward corresponding improvements and perhaps generate credits under the 5 year credit 

carry-forward provisions established in Phase 1 and proposed to continue for Phase 2. Sections

VI.C. and D below provides additional discussion of vehicle redesign cycles and the feasibility

of the proposed standards.

While it is unlikely that there is a phase-in approach that would equally fit with all 

manufacturers’ unique product redesign schedules, the agencies recognize that there are other 

ways the Phase 2 standards could be phased in and request comments on other possible 

approaches. One alternative approach would be to phase in the standards in a few step changes, 

for example in MYs 2021, 2024 and 2027. Under this example, if the step changes on the order 

of 5 percent, 10 percent, and 16 percent improvements from the MY 2020 baseline in MYs 2021, 

2024 and 2027 respectively, the program would provide CO2 reductions and fuel improvements 

roughly equivalent to the proposed approach. Among the factors the agencies would consider in 

assessing a different phase-in than that proposed would be impacts on lead time, feasibility, cost, 

CO2 reductions and fuel consumption improvements. The agencies request that commenters 

consider all of these factors in their recommendations on phase-in. 

As in Phase 1, the proposed Phase 2 standards would be met on a production-weighted 

fleet average basis. No individual vehicle would have to meet a particular fleet average standard. 

Nor would all manufacturers have to meet numerically identical fleet average requirement. 

Rather, each manufacturer would have its own unique fleet average requirement based on the 

production- weighted average of the heavy duty pickups and vans it chooses to produce. 

Moreover, averaging, banking, and trading provisions, just alluded to and discussed further

below, would provide significant additional compliance flexibility in implementing the 

standards. It is important to note, however, that while the standards would differ numerically 
Page 408 of 850

from manufacturer to manufacturer, effective stringency should be essentially the same for each 

manufacturer. 

Also, as with the Phase 1 standards, the agencies are proposing separate Phase 2 targets 

for gasoline-fueled (and any other Otto-cycle) vehicles and diesel-fueled (and any other dieselcycle) vehicles. The targets would be used to determine the production-weighted fleet average 

standards that apply to the combined diesel and gasoline fleet of HD pickups and vans produced 

by a manufacturer in each model year. The above-proposed stringency increase for Phase 2 

applies equally to the separate gasoline and diesel targets. The agencies considered different 

rates of increase for the gasoline and diesel targets in order to more equally balance compliance

burdens across manufacturers with varying gasoline/diesel fleet mixes. However, at least among 

major HD pickup and van manufacturers, our analysis suggests limited potential for such 

optimization, especially considering uncertainties involved with manufacturers’ future fleet mix. 

The agencies have thus maintained the equivalent rates of stringency increase. The agencies 

invite comment on this element.
Page 409 of 850

Figure VI-3 EPA Proposed CO2 Target Standards and NHTSA Proposed Fuel Consumption Target 

Standards for Diesel HD Pickups and Vans

3.44

3.94

4.44

4.94

5.44

5.94

6.44

6.94

350

400

450

500

550

600

650

700

750

3000 3500 4000 4500 5000 5500 6000 6500 7000

Work Factor

Diesel Standards

CO2(grams permile)
Page 410 of 850

Figure VI-4 EPA Proposed CO2 Target Standards and NHTSA Proposed Fuel Consumption Target 

Standards for Gasoline HD Pickups and Vans

3.94

4.44

4.94

5.44

5.94

6.44

6.94

7.44

7.94

8.44

350

400

450

500

550

600

650

700

750

3000 3500 4000 4500 5000 5500 6000 6500 7000

Work Factor

Gasoline Standards

FuelConsumption (gallonsper100 miles)

CO2(grams permile)
Page 411 of 850

Described mathematically, EPA’s and NHTSA’s proposed target standards are defined 

by the following formulas:

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 VI-2. 

Table VI-2 Proposed Phase 2 Coefficients for HD Pickup and Van Target Standards

Diesel Vehicles

Model Year a b c d

2018-2020 a0.0416 320 0.0004086 3.143

2021 0.0406 312 0.0003988 3.065

2022 0.0395 304 0.0003880 2.986

2023 0.0386 297 0.0003792 2.917

2024 0.0376 289 0.0003694 2.839

2025 0.0367 282 0.0003605 2.770

2026 0.0357 275 0.0003507 2.701

2027 and later 0.0348 268 0.0003418 2.633

Gasoline Vehicles

Model Year a b c d

2018-2020 a0.044 339 0.0004951 3.815

2021 0.0429 331 0.0004827 3.725

2022 0.0418 322 0.0004703 3.623

2023 0.0408 314 0.0004591 3.533

2024 0.0398 306 0.0004478 3.443

2025 0.0388 299 0.0004366 3.364

2026 0.0378 291 0.0004253 3.274

2027 and later 0.0369 284 0.0004152 3.196

Note:

a

Phase 1 primary phase-in coefficients. Alternative phase-in coefficients are different in MY2018 only.
Page 412 of 850

As noted above, the standards are not proposed to change from the final Phase 1 

standards for MYs 2018-2020. The MY 2018-2020 standards are shown in the Figures and 

tables above for reference. 

NHTSA and EPA have also analyzed regulatory alternatives to the proposed standards, as 

discussed in Sections VI.C and D and Section X. below. The agencies request comments on all 

of the alternatives analyzed for the proposal, but request comments on Alternative 4 in particular. 

The agencies believe Alternative 4 has the potential to be the maximum feasible alternative; 

however, based on the evidence currently before us, EPA and NHTSA have outstanding 

questions regarding relative risks and benefits of Alternative 4 due to the timeframe envisioned 

by that alternative. Alternative 4 would provide less lead time for the complete phase-in of the 

proposed Phase 2 standards based on an annual improvement of 3.5 percent per year in MYs 

2021-2025 compared to the proposed Alternative 3 per year improvement of 2.5 percent in MYs 

2021-2027. The CO2 and fuel consumption attribute-based target standards for the Alternative 4 

phase-in are shown in Figure VI-5 and Figure VI-6 below. As the target curves for Alternative 4 

show in comparison to the target curves shown above for the proposed Alternative 3, the final 

Phase 2 standards would result in essentially the same level of stringency under either 

alternative. However, the Phase 2 standards would be fully implemented two years earlier, in 

MY 2025, under Alternative 4. The agencies are seriously considering whether this Alternative 

4 (i.e., the proposed standards but with two years less lead-time) would be realistic and feasible, 

as described in Sections VI.C and D, Section X, and in the Draft RIA Chapter 11. Alternative 4

is predicated on shortened lead time that would result in accelerated and in some cases higher 

adoption rates of the same technologies on which the proposed Alternative 3 is predicated. The 

agencies request comments, data, and information that would help inform determination of the 

maximum feasible (for NHTSA) and appropriate (for EPA) stringency for HD pickups and vans

and are particularly interested in information and data related to the expected adoption rates of 

different emerging technologies, such as mild and strong hybridization.
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Figure VI-5 Alternative 4 EPA CO2 Target Standards and NHTSA Fuel Consumption Target Standards for 

Diesel HD Pickups and Vans

3.44

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Figure VI-6 Alternative 4 EPA CO2 Target Standards and NHTSA Fuel Consumption Target Standards for 

Gasoline HD Pickups and Vans

3.94

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Gasoline Standards
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As with Phase 1 standards, to calculate a manufacturer’s HD pickup and van fleet 

average standard, the agencies are proposing that separate target curves be used for gasoline and 

diesel vehicles. The agencies’ proposed standards result in approximately 16 percent reductions 

in CO2 and fuel consumption for both diesel and gasoline vehicles relative to the MY 2018 Phase 

1 standards for HD pickup trucks and vans. These target reductions are based on the agencies’ 

assessment of the feasibility of incorporating technologies (which differ for gasoline and diesel 

powertrains) in the 2021-2027 model years, and on the differences in relative efficiency in the 

current gasoline and diesel vehicles. 

The agencies generally prefer to set standards that do not distinguish between fuel types 

where technological or market-based reasons do not strongly argue otherwise. However, as with 

Phase 1, we continue to believe that fundamental differences between spark ignition and 

compression ignition engines warrant unique fuel standards, which is also important in ensuring 

that our program maintains product choices available to vehicle buyers. In fact, gasoline and 

diesel fuel behave so differently in the internal combustion engine that they have historically

required unique test procedures, emission control technologies and emission standards. These 

technological differences between gasoline and diesel engines for GHGs and fuel consumption 

exist presently and will continue to exist after Phase 1 and through Phase 2 until advanced 

research evolves the gasoline fueled engine to diesel-like efficiencies. This will require 

significant technological breakthroughs currently in early stages of research such as 

homogeneous charge compression ignition (HCCI) or similar concepts. Because these 

technologies are still in the early research stages, we believe the proposed separate fuel type 

standards are appropriate in the timeframe of this rule to protect for the availability of both 

gasoline and diesel engines and will result in roughly equivalent redesign burdens for engines of 

both fuel types as evidenced by feasibility and cost analysis in RIA Chapter 10. The agencies 

request comment on the level of stringency of the proposed standards, the continued separate 

targets for gasoline and diesel HD pickups and vans, and the continued use of the work-based 

attribute approach described above.

The proposed NHTSA fuel consumption target curves and 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, Phase 1 established a provision that EPA is not proposing to 

change for Phase 2 that allows manufacturers, if they choose, to use CO2 credits to help 

demonstrate compliance with N2O and CH4 emissions standards, by expressing any N2O and 

CH4 under compliance in terms of their CO2-equivalent and applying CO2 credits as needed. 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 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. 
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(2) What Are the HD Pickup and Van Test Cycles and Procedures

The Phase 1 program established testing procedures for HD pickups and vans and 

NHTSA and EPA are not proposing to change these testing protocols. The vehicles would 

continue to be tested 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). These test procedures are used by manufacturers for 

certification and emissions compliance demonstrations and by the agencies for compliance 

verification and enforcement. 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. Please see Section II.C (2) of the Phase 1 preamble (76 FR 

57166) for a discussion of how HD pickups and vans would be tested. 

One item that the agencies are considering to change is how vehicles are categorized into 

test weight bins. Under the current test procedures, vehicles are tested at 500 lb increments of 

inertial weight classes when testing at or above 5500 lbs test weight. For example, all vehicles 

having a calculated test weight basis of 11,251 to 11,750 pounds would be tested 11,500 pounds 

(i.e., the midpoint of the range). However, for some vehicles, the existence of these bins and the 

large intervals between bins may reduce or eliminate the incentive for mass reduction for some 

vehicles, as a vehicle may require significant mass reduction before it could switch from one test 

weight bin to the next lower bin. For other vehicles, these bins may unduly reward relatively 

small reductions of vehicle mass, as a vehicle’s mass may be only slightly greater than that 

needed to be assigned a 500-pound lighter inertia weight class. For example, for a vehicle with a 

calculated test weight basis of 11,700 pounds, a manufacturer would receive no regulatory

benefit for reducing the vehicle weight by 400 pounds, because the vehicle would stay within the 

same weight bracket. The agencies do recognize that the test weight bins allow for some 

reduction in testing burden as many vehicles can be grouped together under a single test. For 

Phase 2, the agencies seek comment on whether the test weight bins should be changed in order 

to allow for more realistic testing of HD pickups and vans and better capture of the 

improvements due to mass reduction. Some example changes could include reducing the five 

hundred pound interval between bins to smaller intervals similar to those allowed for vehicles

tested below 5,500 lbs. test weight, or allowing any test weight value that is not fixed to a 

particular test weight bin. The latter scenario would still allow some grouping of vehicles to 

reduce test burden, and the agencies also seek comment on how vehicles would be grouped and 

how the test weight of this group of vehicles should be selected. 

We further seek comment as to whether there may be a more appropriate method such as 

allowing analytical adjustment of the CO2 levels and fuel consumption within a vehicle weight 

class to more precisely account for the individual vehicle models performance. For example, 

could an equation like the one specified in 40 CFR 1037.104(g) for analytically adjusting CO2

emissions be used. The agencies are specifically considering an approach in which vehicles are 

tested in the same way with the same test weights, but manufacturers have the option to either 

accept the emission results as provided under the current regulations, or choose to adjust the 

emissions based on the actual test weight basis (actual curb plus half payload) instead of the 

equivalent test weight for the 500 test weight interval. Should the agencies finalize this as an 
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option, manufacturers choosing to adjust their emissions would be required to do so for all of 

their vehicles, and not just for those with test weights below the midpoint of the range. 

(3) Fleet Average Standards

NHTSA and EPA are proposing to retain the fleet average standards approach finalized 

in the Phase 1 rule and structurally similar to light-duty Corporate Average Fuel Economy 

(CAFE) and GHG standards. The fleet average standard for a manufacturer is a productionweighted average of the work factor-based targets assigned to unique vehicle configurations 

within each model type produced by the manufacturer in a model year. Each manufacturer 

would continue to have an average GHG requirement and an average fuel consumption 

requirement unique to its new HD pickup and van fleet in each model year, depending on the 

characteristics (payload, towing, and drive type) 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 and/or four-wheel drive have 

individual targets at numerically higher CO2 and fuel consumption levels than less capable 

vehicles, as discussed in Section VI.B(1). 

The fleet average standard with which the manufacturer must comply would continue to 

be based on its final production figures for the model year, and thus a final assessment of 

compliance would occur after production for the model year ends. The assessment of 

compliance also must consider the manufacturer’s use of carry-forward and carry-back credit 

provisions included in the averaging, banking, and trading program. 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 (initial) EPA 

certificate of conformity for a test group. Instead, at certification the manufacturer would 

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 parallel program for light-duty vehicles, 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. Please see Section II.C (3)(a) 

of the Phase 1 preamble (76 FR 57167) for further discussion of the fleet average approach for 

HD pickups and vans.

(4) 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. EPA is proposing to continue the in-use standards 

approach for individual vehicles that EPA finalized for the Phase 1 program. NHTSA did not 

adopt Phase 1 in-use standards and is not proposing in-use standards for Phase 2. For the EPA 
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program, compliance with the in-use standard for individual vehicles and vehicle models does 

not impact compliance with the fleet average standard, which will be based on the productionweighted average of the new vehicles. Vehicles that fail to meet their in-use emission standards 

would be subject to recall to correct the noncompliance.

As with Phase 1, EPA proposes that the in-use Phase 2 standards for HD pickups and 

vans be established by adding an adjustment factor to the full useful life emissions used to 

calculate the GHG fleet average. EPA proposes that each model’s in-use CO2 standard be the 

model-specific level used in calculating the fleet average, plus 10 percent. No adverse comments 

were received on this provision during the Phase 1 rulemaking. Please see Section II.C (3)(b) of 

the Phase 1 preamble (76 FR 57167) for further discussion of in-use standards for HD pickups 

and vans. 

For Phase 1, EPA aligned the useful life for GHG emissions with the useful life that was 

in place for criteria pollutants: 11 years or 120,000 miles, whichever occurs first (40 CFR 

86.1805-04(a)). Since the Phase 1 rule was finalized, EPA updated the useful life for criteria 

pollutants as part of the Tier 3 rulemaking.338 The new useful life implemented for Tier 3 is 

150,000 miles or 15 years, whichever occurs first. EPA proposes that the useful life for GHG 

emissions also be updated to 150,000 miles/15 years starting in MY 2021 when the Phase 2 

standards begin so that the useful life remains aligned for GHG and criteria pollutant standards 

long term. With the relatively flat deterioration generally associated with CO2 and the proposed 

in-use standard adjustment factor discussed above, EPA does not believe the proposed change in 

useful life would significantly affect the feasibility of the proposed Phase 2 standards.

339

 EPA 

requests comments on the proposed change to useful life.

(5) Other GHG Standards for HD Pickups and Vans

This section addresses greenhouse gases other than CO2. Note that since these are 

greenhouse gases not directly related to fuel consumption, NHTSA does not have equivalent 

standards.

(a) Nitrous Oxide (N2O) and Methane (CH4)

In the Phase 1 rule, EPA established emissions standards for HD pickups and vans for 

both nitrous oxide (N2O) and methane (CH4). Similar to the CO2 standard approach, the N2O 

and CH4 emission levels of a vehicle are based on a composite of the light-duty FTP and HFET 

cycles with the same 55 percent city weighting and 45 percent highway weighting. The N2O and 

CH4 standards were both set by EPA at 0.05 g/mile. Unlike the CO2 standards, averaging 

between vehicles is not allowed. The standards are designed to prevent increases in N2O and 

 

338 79 FR 23492, April 28, 2014 and 40 CFR 86.1805-17.

339 As discussed below in Section VI.D.1., EPA and NHTSA are proposing an adjustment factor of 1.25 for banked 

credits that are carried over from Phase 1 to Phase 2. The useful life is factored into the credits calculation and 

without the adjustment factor the change in useful life would effectively result in a discount of those carry-over 

credits.
Page 419 of 850

CH4 emissions from current levels, i.e., a no-backsliding standard. EPA is not proposing to 

change the N2O or CH4 standards or related provisions established in the Phase 1 rule. Please see 

Phase 1 preamble Section II.E. (76 FR 57188-57193) for additional discussion of N2O and CH4 

emissions and standards.

Across both current gasoline- and diesel-fueled heavy-duty vehicle designs, emissions of 

CH4 and N2O are relatively low and the intent of the cap standards is to ensure that future vehicle 

technologies or fuels do not result in an increase in these emissions. Given the global warning 

potential (GWP) of CH4, the 0.05 g/mile cap standard is equivalent to about 1.25 g/mile CO2, 

which is much less than 1 percent of the overall GHG emissions of most HD pickups and 

vans.340 The effectiveness of oxidation of CH4 using a three-way or diesel oxidation catalyst is 

limited by the activation energy, which tends to be higher where the number of carbon atoms in 

the hydrocarbon molecule is low and thus CH4 is very stable. At this time we are not aware of 

any technologies beyond the already present catalyst systems which are highly effective at 

oxidizing most hydrocarbon species for gasoline and diesel fueled engines that would further 

lower the activation energy across the catalyst or increase the energy content of the exhaust 

(without further increasing fuel consumption and CO2 emissions) to further reduce CH4

emissions at the tailpipe. We note that we are not aware of any new technologies that would 

allow us to adopt more stringent CH4 and N2O standards at this time. The CH4 standard remains 

an important backstop to prevent future increases in CH4 emissions. 

N2O is emitted from gasoline and diesel vehicles mainly during specific catalyst 

temperature conditions conducive to N2O formation. The 0.05 g/mile standard, which translates 

to a CO2-equivalent value of 14.9 g/mile, ensures that systems are not designed in a way that 

emphasizes efficient NOX control while allowing the formation of significant quantities of N2O. 

The Phase 1 N2O standard of 0.05 g/mile for pickups and vans was finalized knowing that it is 

more stringent than the Phase 1 N2O engine standard of 0.10 g/hp-hr, currently being revaluated 

as discussed in Section II.D.3. EPA continues to believe that the 0.05 g/mile standard provides 

the necessary assurance that N2O will not significantly increase, given the mix of gasoline and 

diesel fueled engines in this market and the upcoming implementation of the light-duty and 

heavy-duty (up to 14,000 lbs. GVWR) Tier 3 NOX standards. EPA knows of no technologies 

that would lower N2O emissions beyond the control provided by the precise emissions control 

systems already being implemented to meet EPA’s criteria pollutant standards. Therefore, EPA 

continues to believe the 0.05 g/mile N2O standard remains appropriate. 

If a manufacturer is unable to meet the N2O or CH4 cap standards, the EPA program 

allows the manufacturer to comply using CO2 credits. In other words, a manufacturer may offset 

any N2O or CH4 emissions above the standard by taking steps to further reduce CO2. A 

manufacturer choosing this option would use GWPs to convert its measured N2O and CH4 test 

results that are in excess of the applicable standards into CO2eq to determine the amount of CO2

credits required. For example, a manufacturer would use 25 Mg of positive CO2 credits to offset 

1 Mg of negative CH4 credits or use 298 Mg of positive CO2 credits to offset 1 Mg of negative 

 

340 N2O has a GWP of 298 and CH4 has a GWP of 25 according to the IPCC AR4.
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N2O credits.341 By using the GWP of N2O and CH4, the approach recognizes the intercorrelation 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 included in the Phase 1 rule a compliance option for fuel conversion manufacturers to 

comply with the N2O and CH4 standards that is similar to the credit program described above. 

See 76 FR 57192/3. The compliance option will allow conversion manufacturers, on an 

individual engine family basis, to convert CO2 over compliance into CO2 equivalents (CO2 eq) of 

N2O and/or CH4 that can be subtracted from the CH4 and N2O measured values to demonstrate 

compliance with CH4 and/or N2O standards. EPA did not include similar provisions allowing 

over compliance with the N2O or CH4 standards to serve as a means to generate CO2 credits 

because the CH4 and N2O standards are cap standards representing levels that all but the worst 

vehicles should already be well below. Allowing credit generation against such cap standard 

would provide a windfall credit without any true GHG reduction. EPA proposes to maintain 

these provisions for Phase 2 as they provide important flexibility without reducing the overall 

GHG benefits of the program.

EPA is requesting comment on updating GWPs used in the calculation of credits 

discussed above. Please see the full discussion of this issue and request for comments provided 

in Sections II.D and XI.D. 

(b) Air Conditioning Related Emissions

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. This includes the direct leakage of refrigerant as 

well as the subsequent leakage associated with maintenance and servicing, and with disposal at 

the end of the vehicle’s life.342 Currently, the most commonly used refrigerant in automotive 

applications – R134a, has a high GWP. Due to the high GWP of R134a, a small leakage of the 

refrigerant has a much greater global warming impact than a similar amount of emissions of CO2

or other mobile source GHGs. 

In Phase 1, EPA finalized low leakage requirement for all air conditioning systems 

installed in 2014 model year and later HDVs, with the exception of Class 2b-8 vocational 

vehicles. As discussed in Section V.B.3, EPA is proposing to extend leakage standards to 

vocational vehicles for Phase 2. For air conditioning systems with a refrigerant capacity greater 

than 733 grams, EPA finalized 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. EPA finalized a standard of 1.50 percent leakage per year for heavy-duty pickup 

 

341 N2O has a GWP of 298 and CH4 has a GWP of 25 according to the IPCC AR4.

342 The U.S. EPA has reclamation requirements for refrigerants in place under Title VI of the Clean Air Act.
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trucks and vans and Class 7 and 8 tractors. See Section II.E.5. of Phase 1 preamble (76 FR 

57194-57195) for further discussion of the A/C leakage standard.

In addition to use of leak-tight components in air conditioning system design, 

manufacturers could also decrease the global warming impact of leakage emissions by adopting 

systems that use alternative, lower global warming potential (GWP) refrigerants, to replace the 

refrigerant most commonly used today, HFC-134a (R-134a). The potential use of alternative 

refrigerants in HD vehicles and EPA’s proposed revisions to 40 CFR 1037.115 so that use of 

certain lower GWP refrigerants would cause an air conditioning system in a HD vehicle to be 

deemed to comply with the low leakage standard is discussed in Section I.F. above.

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 (as just noted) air conditioners create load on the engine. See 74 FR 49529. In 

Phase 1, the agencies did not set 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 were estimated to be minimal compared to 

their overall emissions of CO2. This continues to be the case. For this reason, EPA is not 

proposing to establish standards for A/C efficiency for Phase 2.

NHTSA and EPA request comments on all aspects of the proposed HD pickup and van 

standards and program elements described in this section.

C. Feasibility of Pickup and Van Standards

EPCA and EISA require NHTSA 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 to establish corresponding fuel consumption standards 

“that are appropriate, cost-effective, and technologically feasible.”343 Section 202 (a) (1) and (2) 

of the Clean Air Act require EPA to establish standards for emissions of pollutants from new 

motor vehicles and engines which emissions cause or contribute to air pollution which may

reasonably be anticipated to endanger public health or welfare, which include GHGs. See 

section I.E. above. Under section 202 (a) (1) and (2), 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-GHG emissions; the impacts of standards on oil conservation and energy security; the 

 

343 49 USC 32902(k)(2).
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impacts of standards on fuel savings by customers; the impacts of standards on the truck 

industry; other energy impacts; as well as other relevant factors such as impacts on safety. 

As part of the feasibility analysis of potential standards for HD pickups and vans, the 

agencies have applied DOT’s CAFE Compliance and Effects Modeling System (sometimes 

referred to as “the CAFE model” or “the Volpe model”), which DOT’s Volpe National 

Transportation Systems Center (Volpe Center) developed, maintains, and applies to support 

NHTSA CAFE analyses and rulemakings.344 The agencies used this model to determine the 

range of stringencies that might be achievable through the use of technology that is projected to 

be available in the Phase 2 time frame. From these runs, the agencies identified the stringency

level that would be technology-forcing (i.e. reflect levels of stringency based on performance of 

merging as well as currently available control technologies), but leave manufacturers the 

flexibility to adopt varying technology paths for compliance and allow adequate lead time to 

develop, test, and deploy the range of technologies. 

As noted in Section I and discussed further below, the analysis considers two reference 

cases for HD pickups and vans, a flat baseline (designated Alternative 1a) where no 

improvements are modeled beyond those needed to meet Phase 1 standards and a dynamic 

baseline (designated Alternative 1b) where certain cost-effective technologies (i.e., those that 

payback within a 6 month period) are assumed to be applied by manufacturers to improve fuel 

efficiency beyond the Phase 1 requirements in the absence of new Phase 2 standards. NHTSA 

considered its primary analysis to be based on the more dynamic baseline whereas EPA 

considered both reference cases. As shown below and in Sections VII through X, using the two 

different reference cases has little impact on the results of the analysis and would not lead to a 

different conclusion regarding the appropriateness of the proposed standards. As such, the use of 

different reference cases corroborates the results of the overall analysis.

The proposed phase-in schedule of reduction of 2.5 percent per year in fuel consumption 

and CO2 levels relative to the 2018 MY Phase 1 standard level, starting in MY 2021 and 

extending through MY 2027, was chosen to strike a balance between meaningful reductions in 

the early years and providing manufacturers with needed lead time via a gradually accelerating 

ramp-up of technology penetration. By expressing the phase-in in terms of increasing year to 

year stringency for each manufacturer, while also providing for credit generation and use 

(including averaging, carry-forward, and carry-back), we believe our proposed program would 

afford manufacturers substantial flexibility to satisfy the proposed phase-in through a variety of 

pathways: the gradual application of technologies across the fleet, greater application levels on 

only a portion of the fleet, and a sufficiently broad set of available technologies to account for 

 

344 The CAFE model has been under ongoing development, application, review, and refinement since 2002. In five 

rulemakings subject to public review and comment, DOT has used the model to estimate the potential impacts of 

new CAFE standards. The model has also been subject to formal review outside the rulemaking process, and DOT 

anticipates comments on the model in mid-2015 as part of a broader report under development by the National 

Academy of Sciences (NAS). The model, underlying source code, inputs, and outputs are available at NHTSA’s 

web site, and some outside organizations are making use of the model. The agency anticipates that stakeholders will 

have comments on recent model changes made to accommodate standards for HD pickups and vans.
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the variety of current technology deployment among manufacturers and the lowest-cost 

compliance paths available to each.

We decided to propose a phased implementation schedule that would be appropriate to 

accommodate manufacturers’ redesign workload and product schedules, especially in light of 

this sector’s limited product offerings345 and long product cycles. We did not estimate the cost 

of implementing the proposed standards immediately in 2021 without a phase-in, but we 

qualitatively assessed it to be somewhat higher than the cost of the phase-in we are proposing, 

due to the workload and product cycle disruptions it could 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 75 FR 25451/3 (May 7, 2010) 

(documenting types of drastic cost increases associated with trying to accelerate redesign 

schedules and concluding that “[w]e believe that it would be an inefficient use of societal 

resources to incur such costs when they can be obtained much more cost effectively just one year 

later”). On the other hand, waiting until 2027 before applying any new standards could miss the 

opportunity to achieve meaningful and cost-effective early reductions not requiring a major 

product redesign.

The agencies believe that Alternative 4 has the potential to be the maximum feasible 

alternative, however, the agencies are uncertain that the potential technologies and market 

penetration rates included in Alternative 4 are currently technologically feasible. Alternative 4 

would ultimately reach the same levels of stringency as Alternative 3, but would do so with less 

lead time. This could require the application of a somewhat different (and possibly broader)

application of the projected technologies depending on product redesign cycles. We expect, in 

fact, that some of these technologies may well prove feasible and cost-effective in this 

timeframe, and may even become technologies of choice for individual manufacturers. 

Additionally, Alternative 3 provides two more years of phase-in than Alternative 4, 

which eases compliance burden by having more vehicle redesigns and lower stringency during 

the phase-in period. Historically, the vehicles in this segment are typically only redesigned every

6-10 years, so many of the vehicles may not even be redesigned during the timeframe of the 

stringency increase. In this case, a manufacturer must either make up for any vehicle that falls 

short of its target through some combination of early compliance, overcompliance, credit carryforward and carry-back, and redesigning vehicles more frequently. Each of these will increase 

technology costs to the manufacturers and vehicle purchasers, and early redesigns will 

significantly increases capital costs and product development costs. Also, the longer phase-in 

time for Alternative 3 means that any manufacturer will have a slightly lower target to meet from 

2021-2026 than for the shorter phase-in of Alternative 4, though by 2027 the manufacturers will 

have the same target in either alternative.

Alternative 4 is projected to be met using a significantly higher degree of hybridization 

including the use of more strong hybrids, compared to the proposed preferred Alternative 3. In 

 

345 Manufacturers generally have only one pickup platform and one van platform in this segment.
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order to comply with a 3.5 percent per year increase in stringency over MYs 2021-2025, 

manufacturers would need to adopt more technology compared to the 2.5 percent per year 

increase in stringency over MYs 2021-2027. The two years of additional lead time provided by

Alternative 3 to achieve the proposed final standards reduces the potential number of strong 

hybrids projected to be used by allowing for other more cost effective technologies to be more 

fully utilized across the fleet. Alternative 4 is also projected to result in higher costs and risks 

than the proposed Alternative 3 due to the projected higher technology adoption rates with the 

additional emission reductions and fuel savings predominately occurring only during the 

program phase-in period. The agencies’ analysis is discussed in detail below. 

In some cases, the model selects strong hybrids as a more cost effective technology over 

certain other technologies including stop-start and mild hybrid. In other words, strong hybrids 

are not a technology of last resort in the analysis. The agencies believe it is technologically 

feasible to apply hybridization to HD pickups and vans in the lead time provided. However, 

strong hybrids present challenges in this market segment compared to light-duty where there are 

several strong hybrids already available. The agencies do not believe that at this stage there is 

enough information about the viability of strong hybrid technology in this vehicle segment to 

assume that they can be a part of large-volume deployment strategies for regulated 

manufacturers. For example, we believe that hybrid electric technology could provide 

significant GHG and fuel consumption benefits, but we recognize that there is uncertainty at this 

time over the real world effectiveness of these systems in HD pickups and vans, and over 

customer acceptance of the technology for vehicles with high GCWR towing large loads. 

Further, the development, design, and tooling effort needed to apply this technology to a vehicle 

model is quite large, and might not be cost-effective due to the small sales volumes relative to 

the light-duty sector. Additionally, the analysis does not project that engines would be downsized in conjunction with hybridization for HD pickups and vans due to the importance pickup 

trucks buyers place on engine horsepower and torque necessary to meet towing objectives. 

Therefore, with no change projected for engine size, the strong hybrid costs do not include costs 

for engine changes. In light-duty, the use of smaller engines facilitates much of a hybrid’s 

benefit.

Due to these considerations, the agencies have conducted a sensitivity analysis that is 

based on the use of no strong hybrids. The results of the analysis are also discussed below. The 

analysis indicates that there would be a technology pathway that would allow manufacturers to 

meet both the proposed preferred Alternatives 3 and Alternative 4 without the use of strong 

hybrids. However, the analysis indicates that costs would be higher and the cost effectiveness 

would be lower under the no strong hybrid approach, especially for Alternative 4, which 

provides less lead time to manufacturers. 

We also considered proposing less stringent standards under which manufacturers could 

comply by deploying a more limited set of technologies. However, our assessment concluded 

with a high degree of confidence that the technologies on which the proposed standards are 

premised would be available at reasonable cost in the 2021-2027 timeframe, and that the phasein and other flexibility provisions allow for their application in a very cost-effective manner, as 

discussed in this section below.
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More difficult to characterize is the degree to which more or less stringent standards 

might be appropriate because of under- or over-estimating the costs or effectiveness of the 

technologies whose performance is the basis of the proposed standards. For the most part, these 

technologies have not yet been applied to HD pickups and vans, even on a limited basis. We are

therefore 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 a NHTSA contracted study at SwRI346 and our recent rulemaking on light-duty vehicle 

GHGs and fuel economy, and have generated a robust set of effectiveness values. Chapter 10 of 

the draft RIA provides a detailed description of the CAFE Model and the analysis performed for 

the proposal.

(1) Regulatory Alternatives Considered by the Agencies

As discussed above, the agencies are proposing standards defined by fuel consumption 

and GHG targets that continue through model year 2020 unchanged from model year 2018, and 

then increase in stringency at an annual rate of 2.5 percent through model year 2027. In addition 

to this regulatory alternative, the agencies also considered a no-action alternative under which 

standards remain unchanged after model year 2018, as well as three other alternatives, defined by 

annual stringency increases of 2.0 percent, 3.5 percent, and 4.0 percent during 2021-2025. For 

each of the “action alternatives” (i.e., those involving stringency increases beyond the no-action 

alternative), the annual stringency increases are applied as follows: An annual stringency

increase of r is applied by multiplying the model year 2020 target functions (identical to those 

applicable to model year 2018) by 1 – r to define the model year 2021 target functions, 

multiplying the model year 2021 target functions by 1 – r to define the model year 2022 target 

functions, continuing through 2025 for all alternatives except for the preferred Alternative 3 

which extends through 2027. In summary, the agencies have considered the following five 

regulatory alternatives in Table VI-3.

Table VI-3 Regulatory Alternatives

Regulatory

Alternative

Annual Stringency Increase

2019-2020 2021-2025 2026-2027

1: No Action None None None

2: 2.0%/y None 2.0% None

3: 2.5%/y None 2.5% 2.5%

4: 3.5%/y None 3.5% None

5: 4.0%/y None 4.0% None

 

346 Reinhart, T. (2015). Commercial Medium- and Heavy-Duty (MD/HD) Truck Fuel Efficiency Technology Study –

Report #1. Washington, DC: National Highway Traffic Safety Administration.
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(2) DOT CAFE Model

DOT developed the CAFE model in 2002 to support the 2003 issuance of CAFE 

standards for MYs 2005-2007 light trucks. DOT has since significantly expanded and refined 

the model, and has applied the model to support every ensuing CAFE rulemaking for both lightduty and heavy-duty. For this analysis, the model was reconfigured to use the work based 

attribute metric of “work factor” established in the Phase 1 rule instead of the light duty 

“footprint” attribute metric. 

Although the CAFE model can also be used for more aggregated analysis (e.g., involving 

“representative vehicles”, single-year snapshots, etc.), NHTSA designed the model with a view 

toward (a) detailed simulation of manufacturers’ potential actions given a defined set of 

standards, followed by (b) calculation of resultant impacts and economic costs and benefits. The 

model is intended to describe actions manufacturers could take in light of defined standards and 

other input assumptions and estimates, not to predict actions manufacturers will take in light of 

competing product and market interests (e.g. engine power, customer features, technology

acceptance, etc.).

For these rules, the agencies conducted coordinated and complementary analyses using 

two analytical methods for the heavy-duty pickup and van segment by employing both DOT’s 

CAFE model and EPA’s MOVES model. The agencies used EPA’s MOVES model to estimate 

fuel consumption and emissions impacts for tractor-trailers (including the engine that powers the 

tractor), and vocational vehicles (including the engine that powers the vehicle). Additional 

calculations were performed to determine corresponding monetized program costs and benefits. 

For heavy-duty pickups and vans, the agencies performed complementary analyses, which we 

refer to as “Method A” and “Method B”. In Method A, the CAFE model was used to project a 

pathway the industry could use to comply with each regulatory alternative and the estimated 

effects on fuel consumption, emissions, benefits and costs. In Method B, the CAFE model was 

used to project a pathway the industry could use to comply with each regulatory alternative, 

along with resultant impacts on per vehicle costs, and the MOVES model was used to calculate 

corresponding changes in total fuel consumption and annual emissions. Additional calculations 

were performed to determine corresponding monetized program costs and benefits. NHTSA 

considered Method A as its central analysis and Method B as a supplemental analysis. EPA 

considered the results of both methods. The agencies concluded that both methods led the 

agencies to the same conclusions and the same selection of the proposed standards. See Section 

VII for additional discussion of these two methods.

As a starting point, the model makes use of an input file defining the analysis fleet—that 

is, a set of specific vehicle models (e.g., Ford F250) and model configurations (e.g., Ford F250 

with 6.2-liter V8 engine, 4WD, and 6-speed manual transmission) estimated or assumed to be 

produced by each manufacturer in each model year to be included in the analysis. The analysis 

fleet includes key engineering attributes (e.g., curb weight, payload and towing capacities, 

dimensions, presence of various fuel-saving technologies) of each vehicle model, engine, and 

transmissions, along with estimates or assumptions of future production volumes. It also 

specifies the extent to which specific vehicle models share engines, transmissions, and vehicle 

platforms, and describes each manufacturer’s estimated or assumed product cadence (i.e., timing 

for freshening and redesigning different vehicles and platforms). This input file also specifies a 
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payback period used to estimate the potential that each manufacturer might apply technology to 

improve fuel economy beyond levels required by standards. The file used for this analysis was 

created from 2014 manufacturer compliance reports for the base sales and technology

information, and a future fleet projection created from a combination of data from a sales 

forecast that the agencies purchased from IHS Automotive and total volumes class 2b and 3 fleet 

volumes from 2014 AEO Reference Case. A complete description of the future fleet is available 

in Draft RIA Chapter 10.

A second input file to the model contains a variety of contextual estimates and 

assumptions. Some of these inputs, such as future fuel prices and vehicle survival and mileage 

accumulation (versus vehicle age), are relevant to estimating manufacturers’ potential 

application of fuel-saving technologies. Some others, such as fuel density and carbon content, 

vehicular and upstream emission factors, the social cost of carbon dioxide emissions, and the 

discount rate, are relevant to calculating physical and economic impacts of manufacturers’ 

application of fuel-saving technologies.

A third input file contains estimates and assumptions regarding the future applicability, 

availability, efficacy, and cost of various fuel-saving technologies. Efficacy is expressed in 

terms of the percentage reduction in fuel consumption, cost is expressed in dollars, and both 

efficacy and cost are expressed on an incremental basis (i.e., estimates for more advanced 

technologies are specified as increments beyond less advanced technologies). The input file also 

includes “synergy factors” used to make adjustments accounting for the potential that some 

combinations of technologies may result fuel savings or costs different from those indicated by 

incremental values.

Finally, a fourth model input file specifies standards to be evaluated. Standards are 

defined on a year-by-year basis separately for each regulatory class (passenger cars, light trucks, 

and heavy-duty pickups and vans). Regulatory alternatives are specified as discrete scenarios, 

with one scenario defining the no-action alternative or “baseline”, all other scenarios defining 

regulatory alternatives to be evaluated relative to that no-action alternative.

Given these inputs, the model estimates each manufacturer’s potential year-by-year 

application of fuel-saving technologies to each engine, transmission, and vehicle. Subject to a 

range of engineering and planning-related constraints (e.g., secondary axle disconnect can’t be 

applied to 2-wheel drive vehicles, many major technologies can only be applied practicably as 

part of a vehicle redesign, and applied technologies carry forward between model years), the 

model attempts to apply technology to each manufacturer’s fleet in a manner that minimizes 

“effective costs” (accounting, in particular, for technology costs and avoided fuel outlays), 

continuing to add improvements as long as doing so would help toward compliance with 

specified standards or would produce fuel savings that “pay back” at least as quickly as specified 

in the input file mentioned above.

After estimating the extent to which each manufacturer might add fuel-saving 

technologies under each specified regulatory alternative, the model calculates a range of physical 

impacts, such as changes in highway travel (i.e., VMT), changes in fleetwide fuel consumption, 

changes in highway fatalities, and changes in vehicular and upstream greenhouse gas and criteria 

pollutant emissions. The model also applies a variety of input estimates and assumptions to 
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calculate economic costs and benefits to vehicle owners and society, based on these physical 

impacts.

Since the manufacturers of HD pickups and vans generally only have one basic pickup

truck and van with different versions ((i.e., different wheelbases, cab sizes, two-wheel drive, 

four-wheel drive, etc.) there exists less flexibility than in the light-duty fleet to coordinate model 

improvements over several years. As such, the CAFE model allows changes to the HD pickups 

and vans to meet new standards according to predefined redesign cycles included as a model 

input. As noted above, 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 eight or more years for this analysis. However, opportunities for gradual 

improvements not necessarily linked to large scale changes can occur between the redesign 

cycles (i.e., model refresh). Examples of such improvements are upgrades to an existing vehicle 

model’s engine, transmission and aftertreatment systems. Given the long redesign cycle used in 

this analysis and the understanding with respect to where the different manufacturers are in that 

cycle, the agencies have initially determined that the full implementation of the proposed 

standards would be feasible and appropriate by the 2027 model year.

This analysis reflects several changes made to the model since 2012, when NHTSA used 

the model to estimate the effects, costs, and benefits of final CAFE standards for light-duty 

vehicles produced during MYs 2017-2021, and augural standards for MYs 2022-2025. Some of 

these changes specifically enable analysis of potential fuel consumption standards (and, hence, 

CO2 emissions standards harmonized with fuel consumption standards) for heavy-duty pickups 

and vans; other changes implement more general improvements to the model. Key changes 

include the following:

 Changes to accommodate standards for heavy-duty pickups and vans, including attributebased standards involving targets that vary with “work factor”.

 Explicit calculation of test weight, taking into account test weight “bins” and differences 

in the definition of test weight for light-duty vehicles (curb weight plus 300 pound) and 

heavy-duty pickups and vans (average of GVWR and curb weight).

 Procedures to estimate increases in payload when curb weight is reduced, increases in 

towing capacity if GVWR is reduced, and calculation procedures to correspondingly 

update calculated work factors.

 Inclusion of technologies not included in prior analyses.

 Changes to enable more explicit accounting for shared vehicle platforms and adoption 

and “inheritance” of major engine changes.

 Expansion of the Monte Carlo simulation procedures used to perform probabilistic 

uncertainty analysis.

In addition to the inputs summarized above, the agencies’ analysis of potential standards 

for HD pickups and vans makes use of a range of other estimates and assumptions specified as 

inputs to the CAFE modeling system. Some significant inputs (e.g., estimates of future fuel 

prices) also applicable to other HD segments are discussed below in Section IX. Others more 
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specific to the analysis of HD pickups and vans are listed as follows, with additional details in 

section D:

 Vehicle survival and mileage accumulation

 VMT rebound

 On-road “gap” in fuel consumption

 Fleet population profile

 Past fuel consumption levels

 Long-term fuel consumption levels

 Payback period

 Coefficients for fatality calculations

 Compliance credits carried-forward

 Emission factors for non-CO2 emissions

 Refueling time benefits

 External Costs of travel

 Ownership and operating costs

The CAFE model and its modifications for this rulemaking are described in more detail 

in Section I. below as well as the Draft RIA Chapter 10.

(3) How Did the Agencies Develop the Analysis Fleet

In order to more accurately estimate the impacts of potential standards, the agencies are 

estimating the composition of the future vehicle fleet. Projections of the future vehicle fleet are 

also done for both vocational vehicles and tractors. The procedure for pickups and vans is more 

detailed, though, in order to show the differences for each manufacturer in the segment. Doing 

so enables estimation of the extent to which each manufacturer may need to add technology in 

response to a given series of attribute-based standards, accounting for the mix and fuel 

consumption of vehicles in each manufacturer’s regulated fleet. The agencies create an analysis 

fleet in order to track the volumes and types of fuel economy-improving and CO2 -reducing 

technologies that are already present in the existing fleet of Class 2b and 3 vehicles. This aspect 

of the analysis fleet helps to keep the CAFE model from adding technologies to vehicles that 

already have these technologies, which would result in “double counting” of technologies’ costs 

and benefits. An additional step involved projecting the fleet sales into MYs 2019-2030. This 

represents the fleet volumes that the agencies believe would exist in MYs 2019-2030. The CAFE 

model considers the actual redesign years of each vehicle platform for each manufacturer. Due 

to credit banking, some manufacturers may not need to add technology to comply with the 

standards until later model years, which may be after the rulemaking period. Therefore, it is 

necessary to run the model until all of the vehicle technology changes have stabilized.

Most of the information about the vehicles that make up the 2014 analysis fleet was 

gathered from the 2014 Pre-Model Year Reports submitted to EPA by the manufacturers under 

Phase 1 of Fuel Efficiency and GHG Emission Program for Medium- and Heavy-Duty Trucks, 

MYs 2014-2018. The major manufacturers of class 2b and class 3 trucks (Chrysler, Ford and 

GM) were asked to voluntarily submit updates to their Pre-Model Year Reports. Updated data 
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were provided by Chrysler and GM. The agencies used these updated data in constructing the 

analysis fleet for these manufacturers. The agencies agreed to treat this information as 

Confidential Business Information (CBI) until the publication of the NPRM. This information 

can be made public at this time because by now all MY2014 vehicle models have been produced, 

which makes data about them essentially public information.

In addition to information about each vehicle, the agencies need additional information 

about the fuel economy-improving/CO2-reducing technologies already on those vehicles in order 

to assess how much and which technologies to apply to determine a path toward future 

compliance. To correctly account for the cost and effectiveness of adding technologies, it is 

necessary to know the technology penetration in the existing vehicle fleet. Otherwise, “doublecounting” of technology could occur. Thus, the agencies augmented this information with 

publicly-available data that include more complete technology descriptions, e.g. for specific 

engines and transmissions.

The analysis fleet also requires projections of sales volumes for the years of the 

rulemaking analysis. The agencies relied on the MY 2014 pre-model-year compliance 

submissions from manufacturers to provide sales volumes at the model level based on the level 

of disaggregation in which the models appear in the compliance data. However, the agencies 

only use these reported volumes without adjustment for MY 2014. For all future model years, 

we combine the manufacturer submissions with sales projections from the 2014 Annual Energy

Outlook Reference Case and IHS Automotive to determine model variant level sales volumes in 

future years.

For more detail on how the analysis fleet and sales volume projections were developed, 

please see Section D below as well as the draft RIA Chapter 10.

(4) 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 2021-

2027. The majority of the technologies described in this section are readily available, well 

known and proven in other vehicle sectors, and could be incorporated into vehicles once 

production decisions are made. 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 that 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 proposed action. However, we are considering and seek comment on 

advanced technology credits to encourage the development of such technologies, as discussed 

below in Section VI.E. 

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.
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In this class of trucks and vans, diesel engines are installed in about half of all vehicles. 

The buyer’s decision to purchase a diesel versus gasoline engine depends on several factors 

including initial purchase price, fuel operating costs, durability, towing capability and payload 

capacity amongst other reasons. As discussed in IV.B. above, the agencies generally prefer to 

set standards that do not distinguish between fuel types where technological or market-based 

reasons do not strongly argue otherwise. However, as with Phase 1, we continue to believe that 

fundamental differences between spark ignition and compression ignition engines warrant unique 

fuel standards, which is also important in ensuring that our program maintains product choices 

available to vehicle buyers. Therefore, we are proposing separate standards for gasoline and 

diesel vehicles and in the context of our technology discussion for heavy-duty pickups and vans, 

we are treating gasoline and diesel engines separately so each has a set of baseline technologies. 

We discuss performance improvements in terms of changes to those baseline engines. Our cost 

and inventory estimates contained elsewhere reflect the current fleet baseline with an appropriate 

mix of gasoline and diesel engines. Note that we are not basing the proposed standards on a 

targeted switch in the mix of diesel and gasoline vehicles. We believe our proposed standards 

require similar levels of technology development and cost for both diesel and gasoline vehicles. 

Hence the proposed program is not intended to force, nor discourage, changes in a 

manufacturer’s fleet mix between gasoline and diesel vehicles. Types of engine technologies 

that improve fuel efficiency and reduce CO2 emissions include the following:

 Low-friction lubricants – low viscosity and advanced low friction lubricant 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 low-friction 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. 

 Reduction of engine parasitic demand – mechanical engine load reduction can be 

achieved by variable-displacement oil pumps, higher-efficiency direct injection fuel 

pumps, and variable speed/displacement coolant pumps.

 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.

 Variable valve lift – alters the intake valve lift in order to reduce pumping losses and 

more efficiently ingest air.

 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 
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cylinder, which allows for higher compression ratios and increased thermodynamic 

efficiency.

 Cooled exhaust gas recirculation – technology that conceptually involves utilizing EGR 

as a charge diluent for controlling combustion temperatures and cooling the EGR prior to 

its introduction to the combustion system.

• Turbocharging and downsizing – technology approach that conceptually involves 

decreasing the displacement and cylinder count to improve efficiency when not 

demanding regular high loads and adding a turbocharger to recover any loss to the 

original larger engine peak operating power. This technology was limited in this analysis 

to vehicles that are not expected to operate at high trailer towing levels and instead are 

more akin to duty cycles of light duty (i.e. V6 vans).

• Lean-burn combustion – concept that gasoline engines that are normally stoichiometric 

mainly for emission reasons can run lean over a range of operating conditions and utilize 

diesel like aftertreatment systems to control NOX. For this analysis, we determined that 

the modal operation nature of this technology to currently only be beneficial at light loads 

would not be appropriate for a heavy duty application purchased specifically for its high 

work and load capability.

 Diesel engine improvements and diesel aftertreatment improvements – improved 

turbocharger, 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:

 Eight-speed automatic transmissions – the gear span, gear ratios, and control system are 

optimized for a broader range of efficient engine operating conditions.

 High efficiency transmission – significant reduction of internal parasitic losses such as 

pumps gear bands, etc.

 Driveline friction reduction – reduction in the driveline friction from improvements to 

bearings, seals and other machining tolerances in the axles and transfer cases.

 Secondary axle disconnect – disconnecting of some rotating components in the front axle 

on 4wd vehicles when the secondary axle is not needed for traction.

Types of vehicle technologies considered include:
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 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 – are electrically-assisted 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.

 Mild hybrid – a small, engine-driven (through a belt or other mechanism) electric 

motor/generator/battery combination to enable features such as start-stop, energy

recovery, and launch assist.

 Strong hybrid – a powerful electric motor/generator/battery system coupled to the 

powertrain to enable features such as start-stop, and significant levels of launch assist, 

electric operation, and brake energy recovery. For HD pickups and vans, the engine 

coupled with the strong hybrid system would remain unchanged in power and torque to 

ensure vehicle performance at all times, even if the hybrid battery is depleted.

 Air Conditioner Systems – These technologies include improved hoses, connectors and 

seals for leakage control. They also include improved compressors, expansion valves, 

heat exchangers and the control of these components for the purposes of improving 

tailpipe CO2 emissions as a result of A/C use.347

 

347 See Draft RIA Chapter 2.3 for more detailed technology descriptions.
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(5) How Did the Agencies Determine the Costs and Effectiveness of Each of These 

Technologies

Building on the technical analysis underlying the 2017-2025 MY light-duty vehicle rule, 

the 2014-2018 MY heavy-duty vehicle rule, and the 2014 SwRI report, the agencies took a fresh 

look at technology cost and effectiveness values for purposes of this proposal. 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 the agencies in the light-duty rule as well as referencing costs 

from the 2014-2018 MY heavy-duty vehicle rule and a new cost survey performed by Tetra Tech 

in 2014.

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.348 

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 

2012 dollars (see Section IX.B.1.e of this preamble), and indirect costs were accounted for using 

a methodology consistent with the new ICM approach developed by EPA and used in the Phase 

1 rule, and the 2012-2016 and 2017-2025 light-duty rules. 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. We present the individual 

technology costs used in this analysis in Chapter 2.12 of the Draft RIA.

Regarding estimates for technology effectiveness, the agencies used the estimates from 

the 2014 Southwest Research Institute study as a baseline, which was designed specifically to 

inform this rulemaking. In addition, the agencies used 2017-2025 light-duty rule as a reference, 

and adjusted these estimates 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 

 

348 U.S. Environmental Protection Agency, “Draft Report – Light-Duty Technology Cost Analysis Pilot Study,” 

Contract No. EP-C-07-069, Work Assignment 1-3, September 3, 2009.
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the specific impact of the added load on each technology when compared to the use of the 

technology on a light-duty vehicle. The agencies also considered other sources such as the 2010 

NAS Report, recent CAFE compliance data, and confidential manufacturer estimates of 

technology effectiveness. The agencies 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, the agencies 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 contains a description of technologies the agencies considered in the 

analysis for this proposal. 

(a) Engine Technologies

The agencies reviewed the engine technology estimates used in the 2017-2025 light-duty

rule, the 2014-2018 heavy-duty rule, and the 2014 SwRI report. In doing so the agencies 

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 multi-viscosity engine 

oils are available today with improved performance in a wider temperature band and with better 

lubricating properties. This can be accomplished by changes to the oil base stock (e.g., 

switching engine lubricants from a Group I base oils to lower-friction, lower viscosity Group III 

synthetic) and through changes to lubricant additive packages (e.g., friction modifiers and 

viscosity improvers). The use of 5W-30 motor oil is now widespread and auto manufacturers are 

introducing the use of even lower viscosity oils, such as 5W-20 and 0W-20, to improve cold-
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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.

(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.349 Examples include 

improvements in low-tension piston rings, piston skirt design, roller cam followers, improved 

crankshaft design and bearings, material coatings, material substitution, more optimal thermal 

management, and piston and cylinder surface treatments. Additionally, as computer-aided 

modeling software continues to improve, more opportunities for evolutionary friction reductions

may become available. All reciprocating and rotating components in the engine are potential 

candidates for friction reduction, and minute improvements in several components can add up to 

a measurable fuel efficiency improvement. 

(iii) Engine Parasitic Demand Reduction

In addition to physical engine friction reduction, manufacturers can reduce the 

mechanical load on the engine from parasitics, such as oil, fuel, and coolant pumps. The highpressure fuel pumps of direct-injection gasoline and diesel engines have particularly high 

demand. Example improvements include variable speed or variable displacement water pumps, 

variable displacement oil pumps, more efficient high pressure fuel pumps, valvetrain upgrades 

and shutting off piston cooling when not needed.

(iv) 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.350 For overhead valve engines, which have only one camshaft to actuate both inlet 

 

349 “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).

350 Although couple cam phasing appears only in the single overhead cam and overhead valve branches of the 

decision tree, it is noted that a single phaser with a secondary chain drive would allow couple cam phasing to be 

applied to direct overhead cam engines. Since this would potentially be adopted on a limited number of direct 

overhead cam engines NHTSA did not include it in that branch of the decision tree.
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and exhaust valves, couple cam phasing is the only variable valve timing implementation option 

available and requires only one cam phaser.351

(v) Cylinder Deactivation

In conventional spark-ignited engines throttling the airflow controls engine torque output. 

At partial loads, efficiency can be improved by using cylinder deactivation instead of throttling. 

Cylinder deactivation can improve engine efficiency by disabling or deactivating (usually) half 

of the cylinders when the load is less than half of the engine’s total torque capability – the valves 

are kept closed, and no fuel is injected – as a result, the trapped air within the deactivated 

cylinders is simply compressed and expanded as an air spring, with reduced friction and heat 

losses. The active cylinders combust at almost double the load required if all of the cylinders 

were operating. Pumping losses are significantly reduced as long as the engine is operated in 

this “part-cylinder” mode.

Cylinder deactivation control strategy relies on setting maximum manifold absolute 

pressures or predicted torque within a range in which it can deactivate the cylinders. Noise and 

vibration issues reduce the operating range to which cylinder deactivation is allowed, although 

manufacturers are exploring vehicle changes that enable increasing the amount of time that 

cylinder deactivation might be suitable. Some manufacturers may choose to adopt active engine 

mounts and/or active noise cancellations systems to address Noise Vibration and Harshness 

(NVH) concerns and to allow a greater operating range of activation. 

Cylinder deactivation 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 V8-powered lineups.

(vi) 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.

 

351 It is also noted that coaxial camshaft developments would allow other variable valve timing options to be applied 

to overhead valve engines. However, since they would potentially be adopted on a limited number of overhead valve 

engines, NHTSA did not include them in the decision tree.
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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.

(vii) Turbocharging and Downsizing

The specific power of a naturally aspirated engine is primarily limited by the rate at 

which the engine is able to draw air into the combustion chambers. Turbocharging and 

supercharging (grouped together here as boosting) are two methods to increase the intake 

manifold pressure and cylinder charge-air mass above naturally aspirated levels. Boosting 

increases the airflow into the engine, thus increasing the specific power level, and with it the 

ability to reduce engine displacement while maintaining performance. This effectively reduces 

the pumping losses at lighter loads in comparison to a larger, naturally aspirated engine.

Almost every major manufacturer currently markets a vehicle with some form of 

boosting. While boosting has been a common practice for increasing performance for several 

decades, turbocharging has considerable potential to improve fuel economy and reduce CO2

emissions when the engine displacement is also reduced. Specific power levels for a boosted 

engine often exceed 100 hp/L, compared to average naturally aspirated engine power densities of 

roughly 70 hp/L. As a result, engines can be downsized roughly 30 percent or higher while 

maintaining similar peak output levels. In the last decade, improvements to turbocharger turbine 

and compressor design have improved their reliability and performance across the entire engine 

operating range. New variable geometry turbines and ball-bearing center cartridges allow faster

turbocharger spool-up (virtually eliminating the once-common “turbo lag”) while maintaining 

high flow rates for increased boost at high engine speeds. Low speed torque output has been 

dramatically improved for modern turbocharged engines. However, even with turbocharger 

improvements, maximum engine torque at very low engine speed conditions, for example launch 

from standstill, is increased less than at mid and high engine speed conditions. The potential to 

downsize engines may be less on vehicles with low displacement to vehicle mass ratios for 

example a very small displacement engine in a vehicle with significant curb weight, in order to 

provide adequate acceleration from standstill, particularly up grades or at high altitudes. 

The use of GDI in combination with turbocharging and charge air cooling reduces the 

fuel octane requirements for knock limited combustion enabling the use of higher compression 

ratios and boosting pressures. Recently published data with advanced spray-guided injection 

systems and more aggressive engine downsizing targeted towards reduced fuel consumption and 

CO2 emissions reductions indicate that the potential for reducing CO2 emissions for 

turbocharged, downsized GDI engines may be as much as 15 to 30 percent relative to port-fuelinjected engines.14,15,16,17,18

 Confidential manufacturer data suggests an incremental range of fuel 

consumption and CO2 emission reduction of 4.8 to 7.5 percent for turbocharging and 

downsizing. Other publicly-available sources suggest a fuel consumption and CO2 emission 

reduction of 8 to 13 percent compared to current-production naturally-aspirated engines without 

friction reduction or other fuel economy technologies: a joint technical paper by Bosch and 

Ricardo suggesting fuel economy gain of 8 to 10 percent for downsizing from a 5.7 liter port 

injection V8 to a 3.6 liter V6 with direct injection using a wall-guided direct injection system; a 

Renault report suggesting a 11.9 percent NEDC fuel consumption gain for downsizing from a 1.4 

liter port injection in-line 4-cylinder engine to a 1.0 liter in-line 4-cylinder engine, also with 
Page 439 of 850

wall-guided direct injection; and a Robert Bosch paper suggesting a 13 percent NEDC gain for 

downsizing to a turbocharged DI engine, again with wall-guided injection. These reported fuel 

economy benefits show a wide range depending on the SGDI technology employed.

Note that for this analysis we determined that this technology path is only applicable to 

heavy duty applications that have operating conditions more closely associated with light duty

vehicles. This includes vans designed mainly for cargo volume or modest payloads having 

similar GCWR to light duty applications. These vans cannot tow trailers heavier than similar 

light duty vehicles and are largely already sharing engines of significantly smaller displacement 

and cylinder count compared to heavy duty vehicles designed mainly for trailer towing.

(viii) Cooled Exhaust-Gas Recirculation

Cooled exhaust gas recirculation or Boosted EGR is a combustion concept that involves

utilizing EGR as a charge diluent for controlling combustion temperatures and cooling the EGR 

prior to its introduction to the combustion system. Higher exhaust gas residual levels at part load 

conditions reduce pumping losses for increased fuel economy. The additional charge dilution 

enabled by cooled EGR reduces the incidence of knocking combustion and obviates the need for 

fuel enrichment at high engine power. This allows for higher boost pressure and/or compression 

ratio and further reduction in engine displacement and both pumping and friction losses while 

maintaining performance. Engines of this type use GDI and both dual cam phasing and discrete 

variable valve lift. The EGR systems considered in this proposed rule, consistent with the 

proposal, would use a dual-loop system with both high and low pressure EGR loops and dual 

EGR coolers. The engines would also use single-stage, variable geometry turbocharging with 

higher intake boost pressure available across a broader range of engine operation than 

conventional turbocharged SI engines. Such a system is estimated to be capable of an additional 

3 to 5 percent effectiveness relative to a turbocharged, downsized GDI engine without cooledEGR. The agencies have also considered a more advanced version of such a cooled EGR system 

that employs very high combustion pressures by using dual stage turbocharging.

(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 light-duty 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.352 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.

 

352 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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Based on confidential business information and the 2010 NAS Report, two major areas of 

diesel engine design could be improved during the timeframe of this proposed rule. 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 may result 

in a reduction in the amount of fuel used in the process. However, due to uncertainties with 

these improvements regarding the extent of current optimization and future criteria emissions 

obligations, the agencies are not considering aftertreatment improvements as a fuel-saving 

technology in the rulemaking analysis.

(ii) Engine Improvements

Diesel engines in the HD pickup and van segment are expected to have several 

improvements in their base design in the 2021-2027 timeframe. These improvements include 

items such as improved combustion management, optimal turbocharger design, and improved 

thermal management.

(c) Transmission Technologies 

The agencies have also reviewed the transmission technology estimates used in the 2017-

2015 light-duty and 2014-2018 heavy-duty final rules. In doing so, NHTSA and EPA considered 

or reconsidered all available sources including the 2014 SwRI report and updated the estimates 

as appropriate. The section below describes each of the transmission technologies considered for 

the proposal.

(i) Automatic 8-Speed Transmissions

Manufacturers can also choose to replace 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 gear sets are added, additional weight and friction are introduced 

requiring additional countermeasures to offset these losses. Some manufacturers are replacing 6-

speed automatics already, and 7- and 8-speed automatics have entered production. 

(ii) High Efficiency Transmission

For this proposal, a high efficiency transmission refers to some or all of a suite of 

incremental transmission improvement technologies that should be available within the 2019 to 

2027 timeframe. The majority of these improvements address mechanical friction within the 

transmission. These improvements include but are not limited to: shifting clutch technology

improvements, improved kinematic design, dry sump lubrication systems, more efficient seals, 

bearings and clutches (reducing drag), component superfinishing and improved transmission 

lubricants.
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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.

(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 them electrically, and only when needed (“on-demand”). 

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 warmup time, reduce warm-up fuel enrichment, and reduce parasitic losses.

Indirect benefit may be obtained by reducing the flow from the water pump electrically

during the engine warm-up period, allowing the engine to heat more rapidly and thereby 

reducing the fuel enrichment needed during cold operation and warm-up of the engine. Faster oil 

warm-up may also result from better management of the coolant warm-up period. Further benefit 

may be obtained when electrification is combined with an improved, higher efficiency engine 

alternator used to supply power to the electrified accessories. 

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.353 However, towing vehicles tend to have large cooling system 

capacity and flow scaled to required heat rejection levels when under full load situations such as 

towing at GCWR in extreme ambient conditions. During almost all other situations, this design 

characteristic may result in unnecessary energy usage for coolant pumping and heat rejection to 

the radiator. 

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, 

 

353 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.
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electric oil pump technology has insignificant effect on efficiency. Therefore, the agencies 

decided to not include electric oil pump technology.

(iii) Mild Hybrid

Mild hybrid systems offer idle-stop functionality and a limited level of regenerative 

braking and power assist. These systems replace the conventional alternator with a belt or crank 

driven starter/alternator and may add high voltage electrical accessories (which may include 

electric power steering and an auxiliary automatic transmission pump). The limited electrical 

requirements of these systems allow the use of lead-acid batteries or supercapacitors for energy

storage, or the use of a small lithium-ion battery pack.

(iv) Strong Hybrid

A hybrid vehicle is a vehicle that combines two significant sources of propulsion energy, 

where one uses a consumable fuel (like gasoline), and one is rechargeable (during operation, or 

by another energy source). Hybrid technology is well established in the U.S. light-duty market 

and more manufacturers are adding hybrid models to their lineups. Hybrids reduce fuel 

consumption through three major mechanisms:

 The internal combustion engine can be optimized (through downsizing, modifying the 

operating cycle, or other control techniques) to operate at or near its most efficient 

point more of the time. Power loss from engine downsizing can be mitigated by

employing power assist from the secondary power source.

 A significant amount of the energy normally lost as heat while braking can be 

captured and stored in the energy storage system for later use.

 The engine is turned off when it is not needed, such as when the vehicle is coasting or 

when stopped.

Hybrid vehicles utilize some combination of the three above mechanisms to reduce fuel 

consumption and CO2 emissions. The effectiveness of fuel consumption and CO2 reduction 

depends on the utilization of the above mechanisms and how aggressively they are pursued. One 

area where this variation is particularly prevalent is in the choice of engine size and its effect on 

balancing fuel economy and performance. Some manufacturers choose not to downsize the 

engine when applying hybrid technologies. In these cases, overall performance (acceleration) is 

typically improved beyond the conventional engine. However, fuel efficiency improves less than 

if the engine was downsized to maintain the same performance as the conventional version. The 

non-downsizing approach is used for vehicles like trucks where towing and/or hauling are an 

integral part of their performance requirements. In these cases, if the engine is downsized, the 

battery can be quickly drained during a long hill climb with a heavy load, leaving only a

downsized engine to carry the entire load. Because towing capability is currently a heavilymarketed truck attribute, manufacturers are hesitant to offer a truck with downsized engine 

which can lead to a significantly diminished towing performance when the battery state of charge 

level is low, and therefore engines are traditionally not downsized for these vehicles.
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Strong Hybrid technology utilizes an axial electric motor connected to the transmission 

input shaft and connected to the engine crankshaft through a clutch. The axial motor is a 

motor/generator that can provide sufficient torque for launch assist, all electric operation, and the 

ability to recover significant levels of braking energy.

(e) Vehicle Technologies

(i) Mass Reduction

Mass reduction is a technology that can be used in a manufacturer’s strategy to meet the 

Heavy Duty Greenhouse Gas Phase 2 standards. Vehicle mass reduction (also referred to as 

“down-weighting” or ‘light-weighting”), decreases fuel consumption and GHG emissions by

reducing the energy demand needed to overcome inertia forces, and rolling 

resistance. Automotive companies have worked with mass reduction technologies for many

years and a lot of these technologies have been used in production vehicles. The weight savings 

achieved by adopting mass reduction technologies offset weight gains due to increased vehicle 

size, larger powertrains, and increased feature content (sound insulation, entertainment systems, 

improved climate control, panoramic roof, etc.). Sometimes mass reduction has been used to 

increase vehicle towing and payload capabilities.

Manufacturers employ a systematic approach to mass reduction, where the net mass 

reduction is the addition of a direct component or system mass reduction, also referred to as 

primary mass reduction, plus the additional mass reduction taken from indirect ancillary systems 

and components, also referred to as secondary mass reduction or mass compounding. There are 

more secondary mass reductions achievable for light-duty vehicles compared to heavy-duty 

vehicles, which are limited due to the higher towing and payload requirements for these vehicles.

Mass reduction can be achieved through a number of approaches, even while maintaining 

other vehicle functionalities. As summarized by NAS in its 2011 light duty vehicle report,354

there are two key strategies for primary mass reduction: 1) changing the design to use less 

material; 2) substituting lighter materials for heavier materials. 

The first key strategy of using less material compared to the baseline component can be 

achieved by optimizing the design and structure of vehicle components, systems and vehicle 

structure. Vehicle manufacturers have long used these continually-improving CAE tools to 

optimize vehicle designs. For example, the Future Steel Vehicle (FSV) project355 sponsored by

WorldAutoSteel used three levels of optimization: topology optimization, low fidelity 3G 

(Geometry Grade and Gauge) optimization, and subsystem optimization, to achieve 30 percent 

mass reduction in the body structure of a vehicle with a mild steel unibody structure. Using less 

 

354 Committee on the Assessment of Technologies for Improving Light-Duty Vehicle Fuel Economy; National 

Research Council, “Assessment of Fuel Economy Technologies for Light-Duty Vehicles”, 2011. Available at 

http://www.nap.edu/catalog.php?record_id=12924 (last accessed Jun 27, 2012).

355 SAE World Congress, “Focus B-pillar ‘tailor rolled’ to 8 different thicknesses,” Feb. 24, 2010. Available at 

http://www.sae.org/mags/AEI/7695 (last accessed Jun. 10, 2012).
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material can also be achieved through improving the manufacturing process, such as by using 

improved joining technologies and parts consolidation. This method is often used in 

combination with applying new materials.

The second key strategy to reduce mass of an assembly or component involves the 

substitution of lower density and/or higher strength materials. Material substitution includes 

replacing materials, such as mild steel, with higher-strength and advanced steels, aluminum, 

magnesium, and composite materials. In practice, material substitution tends to be quite specific 

to the manufacturer and situation. Some materials work better than others for particular vehicle 

components, and a manufacturer may invest more heavily in adjusting to a particular type of 

advanced material, thus complicating its ability to consider others. The agencies recognize that 

like any type of mass reduction, material substitution has to be conducted not only with 

consideration to maintaining equivalent component strength, but also to maintaining all the other 

attributes of that component, system or vehicle, such as crashworthiness, durability, and noise, 

vibration and harshness (NVH).

If vehicle mass is reduced sufficiently through application of the two primary strategies 

of using less material and material substitution described above, secondary mass reduction 

options may become available. Secondary mass reduction is enabled when the load requirements 

of a component are reduced as a result of primary mass reduction. If the primary mass reduction 

reaches a sufficient level, a manufacturer may use a smaller, lighter, and potentially more 

efficient powertrain while maintaining vehicle acceleration performance. If a powertrain is 

downsized, a portion of the mass reduction may be attributed to the reduced torque requirement 

which results from the lower vehicle mass. The lower torque requirement enables a reduction in 

engine displacement, changes to transmission torque converter and gear ratios, and changes to 

final drive gear ratio. The reduced powertrain torque enables the downsizing and/or mass 

reduction of powertrain components and accompanying reduced rotating mass (e.g., for 

transmission, driveshafts/halfshafts, wheels, and tires) without sacrificing powertrain durability. 

Likewise, the combined mass reductions of the engine, drivetrain, and body in turn reduce 

stresses on the suspension components, steering components, wheels, tires, and brakes, which 

can allow further reductions in the mass of these subsystems. Reducing the unsprung masses 

such as the brakes, control arms, wheels, and tires further reduce stresses in the suspension 

mounting points, which will allow for further optimization and potential mass reduction.

However, pickup trucks have towing and hauling requirements which must be taken into account 

when determining the amount of secondary mass reduction that is possible and so it is less than 

that of passenger cars.

Ford’s MY 2015 F-150 is one example of a light duty manufacturer who has begun 

producing high volume vehicles with a significant amount of mass reduction identified, 

specifically 250 to 750 lb per vehicle356. The vehicle is an aluminum intensive design and 

includes an aluminum cab structure, body panels, and suspension components, as well as a high 

 

356 “2008/9 Blueprint for Sustainability,” Ford Motor Company. Available at: http:// 

www.ford.com/go/sustainability (last accessed February 8, 2010).
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strength steel frame and a smaller, lighter and more efficient engine. The Executive Summary

to Ducker Worldwide’s 2014 report357 states that state that the MY 2015 F-150 contains 1080 

pounds of aluminum with at least half of this being aluminum sheet and extrusions for body and 

closures. Ford engine range for its light duty truck fleet includes a 2.7L EcoBoost V-6. It is 

possible that the strategy of aluminum body panels will be applied to the heavy duty F-250 and 

F-350 versions when they are redesigned.358 

EPA recently completed a multi-year study with FEV North America, Inc. on the 

lightweighting of a light-duty pickup truck, a 2011 GMC Silverado, titled “Mass Reduction and 

Cost Analysis –Light-Duty Pickup Trucks Model Years 2020-2025”359. Results contain a cost 

curve for various mass reduction percentages with the main solution being evaluated for a 21.4 

percent (511 kg/1124 lb) mass reduction resulting in an increased direct incremental 

manufacturing cost of $2228. In addition, the report outlines the compounding effect that occurs 

in a vehicle with performance requirements including hauling and towing. Secondary mass 

evaluation was performed on a component level based on an overall 20 percent vehicle mass 

reduction. Results revealed 84 kg of the 511 kg, or 20 percent, were from secondary mass 

reduction. Information on this study is summarized in SAE paper 2015-01-0559. DOT has also 

sponsored an on-going pickup truck lightweighting project. This project uses a more recent 

baseline vehicle, a MY 2014 GMC Silverado, and the project will be finished by early 2016. 

Both projects will be utilized for the light-duty GHG and CAFE Midterm Evaluation mass 

reduction baseline characterization and may be used to update assumptions of mass reduction for 

HD pickups and vans for the final Phase 2 rulemaking.

In order to determine if technologies identified on light duty trucks are applicable to 

heavy-duty pickups, EPA also contracted with FEV North America, Inc. to perform a scaling 

study in order to evaluate the technologies identified for the light-duty truck would be applicable 

for a heavy-duty pickup truck, in this study a Silverado 2500, a Mercedes Sprinter and a Renault 

Master. This report is currently being drafted and will be peer reviewed and finalized between 

the NPRM and FRM. The specific results will be presented in the final rulemaking and may be 

used to update assumptions of mass reduction for the FRM. 

The RIA for this rulemaking shows that mass reduction is assumed to be part of the 

strategy for compliance for HD pickups and vans. The assumptions of mass reduction for HD 

pickups and vans as used in this analysis were taken from the recent light-duty fuel 

economy/GHG rulemaking for light-duty pickup trucks, though they may be updated for the 

FRM based upon the on-going EPA and NHTSA lightweighting studies as well as other 

 

357 “2015 North American Light Vehicle Aluminum Content Study – Executive Summary”, June 2014, 

http://www.drivealuminum.org/research-resources/PDF/Research/2014/2014-ducker-report (last accessed February 

26, 2015)

358 http://www.foxnews.com/leisure/2014/09/30/ford-confirms-increased-aluminum-use-on-next-gen-super-dutypickups/

359 “Mass Reduction and Cost Analysis – Light-Duty Pickup Trucks Model Years 2020-2025”, FEV, North 

America, Inc., April 2015, Document no. EPA-420-R-15-006.
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information received in the interim. The cost and effectiveness assumptions for mass reduction 

technology are described in the RIA. 

(ii) Low Rolling Resistance Tires

Tire rolling resistance is the frictional loss associated mainly with the energy dissipated 

in the deformation of the tires under load and thus influences fuel efficiency and CO2

emissions. Other tire design characteristics (e.g., materials, construction, and tread design) 

influence durability, traction (both wet and dry grip), vehicle handling, and ride comfort in 

addition to rolling resistance. A typical LRR tire’s attributes would include: increased tire 

inflation pressure, material changes, and tire construction with less hysteresis, geometry changes 

(e.g., reduced aspect ratios), and reduction in sidewall and tread deflection. These changes 

would generally be accompanied with additional changes to suspension tuning and/or suspension 

design.

(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.

(6) What Are the Projected Technology Effectiveness Values and Costs

The assessment of the technology effectiveness and costs was determined from a 

combination of sources. First an assessment was performed by SwRI under contract with the 

agencies to determine the effectiveness and costs on several technologies that were generally not 

considered in the Phase 1 GHG rule time frame. Some of the technologies were common with 

the light-duty assessment but the effectiveness and costs of individual technologies were 

appropriately adjusted to match the expected effectiveness and costs when implemented in a 

heavy-duty application. Finally, the agencies performed extensive outreach to suppliers of 

engine, transmission and vehicle technologies applicable to heavy-duty applications to get 

industry input on cost and effectiveness of potential GHG and fuel consumption reducing 

technologies.

To achieve the levels of the proposed standards for gasoline and diesel powered heavyduty vehicles, a combination of the technologies previously discussed would be required 

respective to unique gasoline and diesel technologies and their challenges. Although some of the 

technologies may already be implemented in a portion of heavy-duty vehicles, none of the 

technologies discussed are considered ubiquitous in the heavy-duty fleet. Also, as would be 
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expected, the available test data show that some vehicle models would not need the full 

complement of available technologies to achieve the proposed 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 pickups and vans are shown in Table VI-4. These costs reflect 

direct and indirect costs to the vehicle manufacturer for the 2021 model year. See Chapter 2 of 

the Draft RIA for a more complete description of the basis of these costs.

Table VI-4 Technology Costs for HD Pickups & Vans Inclusive of Indirect Cost Markups for MY2021 

(2012$)

Technology Gasoline Diesel

Engine changes to accommodate low friction lubes $6 $6

Engine friction reduction – level 1 $116 $116

Engine friction reduction – level 2 $254 $254

Dual cam phasing $183 $183

Cylinder deactivation $196 N/A

Stoichiometric gasoline direct injection $451 N/A

Turbo improvements N/A $16

Cooled EGR $373 $373

Turbocharging & downsizinga$671 N/A

“Right-sized” diesel from larger diesel N/A $0

8s automatic transmission (increment to 6s automatic transmission) $457 $457

Improved accessories – level 1 $82 $82

Improved accessories – level 2 $132 $132

Low rolling resistance tires – level 1 $10 $10

Passive aerodynamic improvements (aero 1) $51 $51

Passive plus Active aerodynamic improvements (aero2) $230 $230

Electric (or electro/hydraulic) power steering $151 $151

Mass reduction (10% on a 6500 lb vehicle) $318 $318

Driveline friction reduction $139 $139

Stop-start (no regenerative braking) $539 $539

Mild HEV $2730 $2730

Strong HEV without inclusion of any engine changes $6779 $6779

Note:

a Cost to downsize from a V8 OHC to a V6 OHC engine with twin turbos.

As noted above, the CAFE model works by adding technologies in an incremental 

fashion to each particular vehicle in a manufacturer’s fleet until that fleet complies with the 

imposed standards. It does this by following a predefined set of decision trees whereby the 

particular vehicle is placed on the appropriate decision tree and it follows the predefined 

progression of technology available on that tree. At each step along the tree, a decision is made 

regarding the cost of a given technology relative to what already exists on the vehicle along with 
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the fuel consumption improvement it provides relative to the fuel consumption at the current 

location on the tree, prior to deciding whether to take that next step on the tree or remain in the 

current location. Because the model works in this way, the input files must be structured to 

provide costs and effectiveness values for each technology relative to whatever technologies 

have been added in earlier steps along the tree. Table VI-5 presents the cost and effectiveness 

values used in the CAFE model input files.
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Table VI-5 CAFE Model Input Values for Cost & Effectiveness for Given Technologiesa

Technology FC Savings Incremental Cost (2012$)a,b

2021 2025 2027

Improved Lubricants and Engine 

Friction Reduction

1.60% 24 24 23

Coupled Cam Phasing (SOHC) 3.82% 48 43 39

Dual Variable Valve Lift (SOHC) 2.47% 42 37 34

Cylinder Deactivation (SOHC) 3.70% 34 30 27

Intake Cam Phasing (DOHC) 0.00% 48 43 39

Dual Cam Phasing (DOHC) 3.82% 46 40 37

Dual Variable Valve Lift (DOHC) 2.47% 42 37 34

Cylinder Deactivation (DOHC) 3.70% 34 30 27

Stoichiometric Gasoline Direct 

Injection (OHC)

0.50% 71 61 56

Cylinder Deactivation (OHV) 3.90% 216 188 172

Variable Valve Actuation (OHV) 6.10% 54 47 43

Stoichiometric Gasoline Direct 

Injection (OHV)

0.50% 71 61 56

Engine Turbocharging and 

Downsizing

 Small Gasoline Engines 8.00% 518 441 407

 Medium Gasoline Engines 8.00% -12 -62 -44

 Large Gasoline Engines 8.00% 623 522 456

Cooled Exhaust Gas Recirculation 3.04% 382 332 303

Cylinder Deactivation on 

Turbo/downsized Eng.

1.70% 33 29 26

Lean-Burn Gasoline Direct Injection 4.30% 1,758 1,485 1,282

Improved Diesel Engine 

Turbocharging

2.51% 22 19 18

Engine Friction & Parasitic 

Reduction

 Small Diesel Engines 3.50% 269 253 213

 Medium Diesel Engines 3.50% 345 325 273

 Large Diesel Engines 3.50% 421 397 334

Downsizing of Diesel Engines (V6 

to I-4)

11.10% 0 0 0

8-Speed Automatic Transmissionc5.00% 482 419 382
Page 450 of 850

Electric Power Steering 1.00% 160 144 130

Improved Accessories (Level 1) 0.93% 93 83 75

Improved Accessories (Level 2) 0.93% 57 54 46

Stop-Start System 1.10% 612 517 446

Integrated Starter-Generator 3.20% 1,040 969 760

Strong Hybrid Electric Vehicle 17.20% 3,038 2,393 2,133

Mass Reduction (5%) 1.50% 0.28 0.24 0.21

Mass Reduction (additional 5%) 1.50% 0.87 0.75 0.66

Reduced Rolling Resistance Tires 1.10% 10 9 9

Low-Drag Brakes 0.40% 106 102 102

Driveline Friction Reduction 0.50% 153 137 124

Aerodynamic Improvements (10%) 0.70% 58 52 47

Aerodynamic Improvements (add’l 

10%)

0.70% 193 182 153

Notes:

a Values for other model years available in CAFE model input files available at NHTSA web site.

b For mass reduction, cost reported on mass basis (per pound of curb weight reduction).

c

8 speed automatic transmission costs include costs for high efficiency gearbox and aggressive shift logic whereas 

those costs were kept separate in prior analyses.

(7) Summary of Alternatives Analysis

The major outputs of the CAFE model analysis are summarized in Table VI-6 and Table 

VI-7 below for the flat and dynamic baselines, respectively. For a more detailed analysis of the 

alternatives, please refer to Section D below as well as the draft RIA.
Page 451 of 850

Table VI-6 Summary of HD Pickup and Van Alternatives’ Analysis – Method A using the Flat Baseline a

Alternative 2 3 4 5

Annual Standard 

Increase

2.0%/y 2.5%/y 3.5%/y 4.0%/y

Stringency

Increase through 

MY

2025 2027 2025 2025

Total Stringency

Increase

9.6% 16.2% 16.3% 18.5%

Average Fuel Economy (miles per gallon)

Required 19.05 20.58 20.58 21.14

Achieved 19.12 20.58 20.83 21.32

Average Fuel Consumption (gallons /100 mi.)

Required 5.25 4.86 4.86 4.73

Achieved 5.23 4.86 4.80 4.69

Average Greenhouse Gas Emissions (g/mi)

Required 495 458 458 446

Achieved 493 458 453 442

Incremental Technology Cost (vs. No-Action)

Average 

($/vehicle)

b

700 1,324 1,804 2,135

Payback period 

(m) b

24 26 34 36

Total ($m) 529 1,001 1,363 1,614

Benefit-Cost Summary, MYs 2021 - 2030 ($billion) c

Fuel Savings (bil. 

gall.)

6.1 10.1 11.9 13.3

CO2 Reduction 

(mmt)

73 118 139 155

Total Social Cost 3.3 5.6 8.7 10.2

Total Social 

Benefit

18.4 29.0 34.4 37.9

Net Social Benefit 15.1 23.4 25.7 27.7

Notes:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of 

the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

b Values also used in Method B

c

at a 3% discount rate.
Page 452 of 850

Table VI-7 Summary of HD Pickup and Van Alternatives’ Analysis - Method A using the Dynamic Baseline a

Alternative 2 3 4 5

Annual 

Standard 

Increase

2.0%/y 2.5%/y 3.5%/y 4.0%/y

Stringency

Increase 

through MY

2025 2027 2025 2025

Total 

Stringency

Increase

9.6% 16.2% 16.3% 18.5%

Average Fuel Economy (miles per gallon)

Required 19.04 20.57 20.57 21.14

Achieved 19.14 20.61 20.83 21.27

Average Fuel Consumption (gallons /100 mi.)

Required 5.25 4.86 4.86 4.73

Achieved 5.22 4.85 4.80 4.70

Average Greenhouse Gas Emissions (g/mi)

Required 495 458 458 446

Achieved 491 458 453 444

Incremental Technology Cost (vs. No-Action)

Average 

($/vehicle)

b

578 1,348 1,655 2,080

Payback period 

(m) b

25 31 34 38

Total ($m) 437 1,019 1,251 1,572

Benefit-Cost Summary, MYs 2021 - 2030 ($billion) c

Fuel Savings 

(bil. gall.)

5.0 8.9 10.5 11.9

CO2 Reduction 

(mmt)

59 104 122 139

Total Social 

Cost

3.3 6.8 9.5 13.0

Total Social 

Benefit

14.3 23.6 28.2 32.8

Net Social 

Benefit

11.0 16.8 18.7 19.8

Notes:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of 

the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

b Values also used in Method B

c

at a 3% discount rate.
Page 453 of 850

In general, the proposed standards are projected to cause manufacturers to produce HD 

pickups and vans that are lighter, more aerodynamic, and more technologically complex across 

all the alternatives, while social benefits continue to increase across all alternatives. As shown, 

there is a major difference between the relatively small improvements in required fuel 

consumption and average incremental technology cost between the alternatives, suggesting that 

the challenge of improving fuel consumption and CO2 emissions accelerates as stringency

increases (i.e., that there may be a “knee” in the dependence of the challenge and on the 

stringency). Despite the fact that the required average fuel consumption level only changes by 3 

percent between Alternative 4 and Alternative 5, average technology cost increases by more than 

25 percent.

Note further that the difference in estimated costs, effectiveness, degree of technology

penetration required, and overall benefits do not vary significantly under either the flat or 

dynamic baseline assumptions. The agencies view these results as corroborative of the basic 

reasonableness of the approach proposed.

(8) Consistency of the Proposed Standards with the Agencies’ Respective Legal 

Authorities

Based on the information currently before the agencies, we believe that Alternative 3 

would be maximum feasible and appropriate for this segment for the model years in question.

EPA believes this reflects a reasonable consideration of the statutory factors of technology

effectiveness, feasibility, cost, lead time, and safety for purposes of CAA sections 202 (a)(1) and 

(2). NHTSA believes this proposal is maximum feasible under EISA. The agencies have 

projected a compliance path for the proposed standards showing aggressive implementation of

technologies that the agencies consider to be available in the time frame of these rules. Under 

this approach, manufacturers are expected to implement these technologies at aggressive 

adoption rates on essentially all vehicles across this sector by 2027 model year. In the case of 

several of these technologies, adoption rates are projected to approach 100 percent. This 

includes a combination of engine, transmission and vehicle technologies as described in this 

section across every vehicle. The proposal also is premised on less aggressive penetration of 

particular advanced technologies, including strong hybrid electric vehicles.

We project the proposed standards to be achievable within known design cycles, and we 

believe these standards would allow different paths to compliance in addition to the one we 

outline and cost here. As discussed below and throughout this analysis, our proposal places a 

higher value on maintaining functionality and capability of vehicles designed for work (versus 

light-duty), and on the assurance of in use reliability and market acceptance of new technology, 

particularly in initial model years of the program. Nevertheless, it may be possible to have 

additional adoption rates of the technologies than we project so that further reductions could be 

available at reasonable cost and cost-effectiveness.

Alternative 4 is also discussed in detail below because the agencies believe it has the 

potential to be the maximum feasible alternative, and otherwise appropriate. The agencies could 

decide to adopt Alternative 4, in whole or in part, in the final rule. In particular, the agencies 

believe Alternative 4, which would achieve the same stringency as the proposed standards with 

two years less lead time, merits serious consideration. However, the agencies are uncertain 
Page 454 of 850

whether the projected technologies and market penetration rates that could be necessary to meet 

the stringencies would be practicable within the lead time provided in Alternative 4. The 

proposed standards are generally designed to achieve the levels of fuel consumption and GHG 

stringency that Alternative 4 would achieve, but with several years of additional lead time, 

meaning that manufacturers could, in theory, apply new technology at a more gradual pace and 

with greater flexibility. The agencies seek comment on these alternatives, including their 

corresponding lead times. 

Alternative 4 is based on a year-over-year increase in stringency of 3.5 percent in MYs 

2021-2025 whereas the proposed preferred Alternative 3 is based on a 2.5 percent year-over-year 

increase in stringency in MY 2021-2027. The agencies project that the higher rate of increase in 

stringency associated with Alternative 4 and the shorter lead time would necessitate the use of a 

different technology mix under Alternative 4 compared to Alternative 3. Alternative 3 would 

achieve the same final stringency increase as Alternative 4 at about 80 percent of the average 

per-vehicle cost increase, and without the expected deployment of more advanced technology at 

high penetration levels. In particular, under the agencies’ primary analysis that includes the use 

of strong hybrids manufacturers are estimated to deploy strong hybrids in approximately 8

percent of new vehicles (in MY2027) under Alternative 3, compared to 12 percent under 

Alternative 4 (in MY 2025). Less aggressive electrification technologies also appear on 33 

percent of new vehicles simulated to be produced in MY2027 under Alternative 4, but are not 

necessary under Alternative 3. Additionally, it is important to note that due to the shorter lead 

time of Alternative 4, there are fewer vehicle refreshes and redesigns during the phase-in period 

of MY 2021-2025. While the CAFE model’s algorithm accounts for manufacturers’ 

consideration of upcoming stringency changes and credit carry-forward, the steeper ramp-up of 

the standard in Alternative 4, coupled with the five-year credit life, results in a prediction that 

manufacturers would take less cost-effective means to comply with the standards compared with 

the proposed alternative 3 phase-in period of MY 2021-2027. For example, the model predicts 

that some manufacturers would not implement any amount of strong hybrids on their vans 

during the 2021-2025 timeframe and instead would implement less effective technologies such 

as mild hybrids at higher rates than what would otherwise have been required if they had 

implemented a small percentage of strong hybrids. Whereas for Alternative 3, the longer, 

shallower phase-in of the standards allows for more compliance flexibility and closer matching 

with the vehicle redesign cycles, which (as noted above) can be up to ten years for HD vans.

There is also a high degree of sensitivity to the estimated effectiveness levels of 

individual technologies. At high penetration rates of all technologies on a vehicle, the result of a 

reduced effectiveness of even a single technology could be non-compliance with the standards. 

If the standards do not account for this uncertainty, there would be a real possibility that a 

manufacturer who followed the exact technology path we project would not meet their target

because a technology performed slightly differently in their application. NHTSA has explored 

this uncertainty, among others, in the uncertainty analysis described in Section D below.

As discussed above, the proposed Alternative 3 standards and the Alternative 4 standards 

are based on the application of the technologies described in this section. These technologies are 

projected to be available within the lead time provided under Alternative 3 – i.e., by MY 2027, 

as discussed in Draft RIA Chapter 2.6. The proposed standards and Alternative 4 would require 

a relatively aggressive implementation schedule of most of these technologies during the 
Page 455 of 850

program phase-in. Heavy-duty pickups and vans would need to have a combination of many

individual technologies to achieve the proposed standards. The proposed standards are projected 

to yield significant emission and fuel consumption reductions without requiring a large segment 

transition to strong hybrids, a technology that while successful in light-duty passenger cars, 

cross-over vehicles and SUVs, may impact vehicle work capabilities360 and have questionable 

customer acceptance in a large portion of this segment dedicated to towing361.

Table VI-8 below shows that the agencies’ analysis estimates that the most cost-effective 

way to meet the requirements of Alternative 3 would be to use strong hybrids in up to 9.9 percent 

of pickups and 5.5 percent of vans on an industry-wide basis whereas Alternative 4 shows strong 

hybrids on up to 19 percent of pickups. The analysis shows that the two years of additional lead 

time provided by the proposed Alternative 3 would provide manufacturers with a better 

opportunity to maximize the use of more cost effective technologies over time thereby reducing 

the need for strong hybrids which may be particularly challenging for this market segment. The 

agencies seek comment on the potential use of technologies in response to Alternatives 3 and 4, 

as well as the corresponding lead times proposed in each alternative. 

 

360 Hybrid batteries, motors and electronics generally add weight to a vehicle and require more space which can 

result in conflicts with payload weight and volume objectives. 

361 Hybrid electric systems are not sized for situations when vehicles are required to do trailer towing where the 

combined weight of vehicle and trailer is 2 to 4 times that of the vehicle alone. During these conditions, the hybrid 

system will have reduced effectiveness. Sizing the system for trailer towing is prohibitive with respect to hybrid 

component required sizes and the availability of locations to place larger components like batteries. 
Page 456 of 850

Table VI-8 CAFE Model Technology Adoption Rates for Proposal and Alternative 4 Summary – Flat 

Baseline

Proposal (2.5% per year)

2021 to 2027

Alternative 4 (3.5% per year)

2021 to 2025

Technology Pickup Trucks Vans Pickup 

Trucks

Vans

Low friction lubricants 100% 100% 100% 100%

Engine friction reduction 100% 100% 100% 100%

Cylinder deactivation 22% 19% 22% 19%

Variable valve timing 22% 82% 22% 82%

Gasoline direct injection 0% 63% 0% 80%

Diesel engine 

improvements

60% 3.6% 60% 3.6%

Turbo downsized engine 0% 63% 0% 63%

8 speed transmission 98% 92% 98% 92%

Low rolling resistance 

tires

100% 92% 100% 59%

Aerodynamic drag 

reduction

100% 100% 100% 100%

Mass reduction and 

materials

100% 100% 100% 100%

Electric power steering 100% 49% 100% 46%

Improved accessories 100% 87% 100% 36%

Low drag brakes 100% 45% 100% 45%

Stop/start engine systems 0% 0% 15% 1.5%

Mild hybrid 0% 0% 29% 15%

Strong hybrid 9.9% 5.5% 19% 0%

As discussed earlier, the agencies also conducted a sensitivity analysis to determine a 

compliance pathway where no strong hybrids would be selected. Although the agencies project 

that strong hybrids may be the most cost effective approach, manufacturers may select another 

compliance path. This no strong hybrid analysis included the use of downsized turbocharged 

engine in vans currently equipped with large V-8 engines. Turbo-downsized engines were not 

allowed on 6+ liter gasoline vans in the primary analysis because the agencies sought to preserve 

consumer choice with respect to vans that have large V-8s for towing. However, given the 

recent introduction of vans with considerable towing capacity and turbo-downsized engines, the 

agencies believe it would be feasible for vans in the time-frame of these proposed rules. Table 

VI-9 below reflects the difference in penetration rates of technologies for the proposal and 

Alternative 4 if strong hybridization is not chosen as a technology pathway. For simplicity, 

pickup trucks and vans are combined into a single industry wide penetration rate. While strong 

hybridization may provide the most cost effective path for a manufacturer to comply with the 

Proposal or Alternative 4, there are other means to comply with the requirements, mainly a 20 

percent penetration rate of mild hybrids for the Proposal or a 66 percent penetration of mild 

hybrids for Alternative 4. The modeling of both alternatives predicts a 1 to 4 percent penetration 

of stop/start engine systems. 
Page 457 of 850

The table also shows that when strong hybrids are used as a pathway to compliance, 

penetration rates of all hybrid technologies increase substantially between the proposal and 

Alternative 4. The analysis predicts an increase in strong hybrid penetration from 8 percent to 12 

percent, a 23 percent penetration of mild hybrids and a 10 percent penetration stop/start engine 

systems for Alternative 4 compared with the proposal. Also, by having the final standards apply 

in MY2027 instead of MY2025, the proposal is not premised on use of any mild hybrids or 

stop/start engine systems to achieve the same level of stringency as Alternative 4. 

Table VI-9 CAFE Model Technology Adoption Rates for Proposal and Alternative 4 Combined Fleet and 

Fuels Summary– Flat Baseline

Proposal (2.5% per year)

2021 to 2027

Alternative 4 (3.5% per year)

2021 to 2025

Technology With strong 

hybrids

Without 

strong 

hybrids

With strong 

hybrids

Without strong 

hybrids

Low friction lubricants 100% 100% 100% 100%

Engine friction reduction 100% 100% 100% 100%

Cylinder deactivation 21% 22% 21% 14%

Variable valve timing 46% 46% 46% 46%

Gasoline direct injection 25% 45% 31% 45%

Diesel engine improvements 38% 38% 38% 38 %

Turbo downsized engine a25% 31% 25% 31%

8 speed transmission 96% 96% 96% 96%

Low rolling resistance tires 97% 97% 84% 84%

Aerodynamic drag reduction 100% 100% 100% 100%

Mass reduction and materials 100% 100% 100% 100%

Electric power steering 80% 92% 79% 79%

Improved accessories 67% 77% 75% 75%

Low drag brakes 78% 93% 78% 78%

Stop/start engine systems 0% 1 % 10% 4%

Mild hybrid 0% 20% 23% 66%

Strong hybrid 8% 0% 12% 0%

Note:

a

The 6+ liter V8 vans were allowed to convert to turbocharged and downsized engines in the “without strong 

hybrid” analysis for both the Proposal and the Alternative 4 to provide a compliance path.

Table VI-10 and Table VI-11 below provide a further breakdown of projected technology

adoption rates specifically for gasoline-fueled pickups and vans which shows potential adoption 

rates of strong hybrids for each vehicle type. Strong hybrids are not projected to be used in 

diesel applications. The Alternative 4 analysis shows the use of strong hybrids in up to 48

percent of gasoline pickups, depending on the mix of strong and mild hybrids, and stop/start 

engine systems in 20 percent of gasoline pickups (the largest gasoline HD segment). It is 

important to note that this analysis only shows one pathway to compliance, and the 

manufacturers may make other decisions, e.g., changing the mix of strong vs. mild hybrids, or 

applying electrification technologies to HD vans instead. The technology adoption rates 
Page 458 of 850

projected for gasoline pickups and gasoline vans due to the proposed Alternative 3 and 

Alternative 4 are shown in Table VI-10 and Table VI-11, respectively. 

Table VI-10 CAFE Model Technology Adoption Rates for Proposal and Alternative 4 on Gasoline Pickup 

Trucks – Flat Baseline

Proposal (2.5% per year)

2021 to 2027

Alternative 4 (3.5% per year)

2021 to 2025

Technology With strong 

hybrids

Without strong 

hybrids

With strong 

hybrids

Without strong 

hybrids

Low friction 

lubricants

100% 100% 100% 100%

Engine friction 

reduction

100% 100% 100% 100%

Cylinder deactivation 56% 56% 56% 56%

Variable valve timing 56% 56% 56% 56%

Gasoline direct 

injection

0% 56% 0% 56%

8 speed transmission 100% 100% 100% 100%

Low rolling resistance 

tires

100% 100% 100% 100%

Aerodynamic drag 

reduction

100% 100% 100% 100%

Mass reduction and 

materials

100% 100% 100% 100%

Electric power 

steering

100% 100% 100% 100%

Improved accessories 100% 100% 100% 100%

Low drag brakes 100% 100% 100% 100%

Driveline friction 

reduction

44% 68% 68% 68%

Stop/start engine 

systems

0% 0% 20% 0%

Mild hybrid Up to 42% a0% 18 - 86%

a

86%

Strong hybrid Up to 25% - Up to 48% -

Note:

a Depending on extent of strong hybrid adoption as hybrid technologies can replace each other, however 

they will have different effectiveness and costs.
Page 459 of 850

Table VI-11 CAFE Model Technology Adoption Rates for Proposal and Alternative 4 on Gasoline Vans –

Flat Baseline

Proposal (2.5% per year)

2021 to 2027

Alternative 4 (3.5% per year)

2021 to 2025

Technology With strong 

hybrids

Without strong 

hybrids

With strong 

hybrids

Without strong 

hybrids

Low friction 

lubricants

100% 100% 100% 100%

Engine friction 

reduction

100% 100% 100% 100%

Cylinder deactivation 23% 3% 23% 3%

Variable valve timing 100% 100% 100% 100%

Gasoline direct 

injection

57% 97% 97% 97%

Turbo downsized 

engine a

77% 97% 77% 97%

8 speed transmission 97% 97% 97% 97%

Low rolling resistance 

tires

100% 100% 60% 60%

Aerodynamic drag 

reduction

100% 100% 100% 100%

Mass reduction and 

materials

100% 100% 100% 100%

Electric power 

steering

55% 85% 53% 53%

Improved accessories 23% 38% 43% 43%

Low drag brakes 53% 89% 53% 100%

Stop/start engine 

systems

0% 0% 2% 0%

Mild hybrid Up to 13%b13% 18% 40%

Strong hybrid Up to 7% - 0% -

Notes:

a

The 6+ liter V8 vans were allowed to convert to turbocharged and downsized engines in the “without strong 

hybrid” analysis for both the Proposal and the Alternative 4 to provide a compliance path.

b Depending on extent of strong hybrid adoption as hybrid technologies can replace each other, however they will 

have different effectiveness and costs.

The tables above show that many technologies would be at or potentially approach 100 

percent adoption rates according to the analysis. If certain technologies turn out to be not well 

suited for certain vehicle models or less effective that projected, other technology pathways 

would be needed. The additional lead time provided by the proposed Alternative 3 reduces these 

concerns because manufacturers would have more flexibility to implement their compliance 

strategy and are more likely to contain a product redesign cycle necessary for many new 

technologies to be implemented. 
Page 460 of 850

GM may have a particular challenge meeting new standards compared to other 

manufacturers because their production consists of a larger portion of gasoline-powered vehicles 

and because they continue to offer a traditional style HD van equipped only with a V-8 engine. 

Under the strong hybrid analysis for Alternative 3, GM is projected to apply strong hybrids to 46 

percent of their HD gasoline pickups and 17 percent their HD gasoline vans. Under Alternative 

4, GM is projected to apply a combination of 53 percent strong and 43 percent mild hybrids to 

their HD gasoline pickups and 44 percent mild hybrids to their HD vans. The no strong hybrid 

analysis shows that GM could comply without strong hybrids based on the use of turbo 

downsizing on all of their HD gasoline vans to fully comply with either Alternative 3 or 

Alternative 4. As modeled, Alternative 4 would also require GM to additionally utilize several 

other technologies such as higher penetration of mild hybridization. If GM were to choose to 

maintain a V-8 version of their current HD van and not fully utilize turbo downsizing, another 

compliance path such as some use of strong hybrids would be needed. This would also be the 

case if GM chose not to fully utilize some other technologies under Alterative 4 as well.

In addition to the possibility of an increased level of hybridization, the agencies are also 

requesting comment on other possible outcomes associated especially with Alternative 4; in 

particular, the possibility of traditional van designs or other products being discontinued. 

Several manufacturers now offer or are moving to European style HD vans. Ford, for example, 

has discontinued its E-series body on frame HD van and has replaced it with the unibody Transit 

van for MY 2015. While other manufacturers have replaced their traditional style vans with new 

European style van designs, GM continues to offer the traditional full frame style van with eight 

cylinder gasoline engines for higher towing capability (up to 16,000 lb GCWR). Typically, the 

European style vans are equipped with smaller engines offering better fuel consumption and 

lower CO2 emissions but with reduced towing capability, similar to light-duty trucks (though 

Ford offers a Transit van with a GCWR of 15,000 lb). 

The agencies request comment on the potential for Alternative 4 in particular to 

incentivize GM to discontinue its current traditional style van and replace it with an as yet to be 

designed European style van similar to its competitor’s products. See Bluewater Network v. 

EPA, 370 F. 3d 1, 22 (D.C. Cir. 2004) (standard implementing technology-forcing provision of 

CAA remanded to EPA for an explanation of why the standard was not based on discontinuation 

of a particular model); International Harvester v. Ruckelshaus, 478 F. 2d 615, 640-41 (D.C. Cir. 

1973) (“We are inclined to agree with the Administrator that as long as feasible technology

permits the demand for new passenger automobiles to be generally met, the basic requirements 

of the Act would be satisfied, even though this might occasion fewer models and a more limited 

choice of engine types”). Such an outcome could limit consumer choice both on the style of van 

available in the marketplace and on the range of capabilities of the vehicles available. The 

agencies have not attempted to cost out this possible compliance path. The agencies request 

comments on the likelihood of this type of redesign as a possible outcome of Alternative 3 and 

Alternative 4, and whether it would be appropriate. We are especially interested in comments on 

the potential impact on consumer choice and the costs associated with this type of wholesale 

vehicle model replacement.

In addition, another potential outcome of Alternative 4 would be that manufacturers 

could change the product utility. For example, although GM’s traditional van discussed above 

currently offers similar towing capacity as gasoline pickups, GM could choose to replace engines 
Page 461 of 850

designed for those towing capacities with small gas or diesel engines. The agencies request 

comment on the potential for Alternative 4 to lead to this type of compliance approach.

The agencies also request comment on the possibility that Alternative 4 could lead to 

increased dieselization of the HD pickup and van fleet. Dieselization is not a technology path 

the agencies included in the analysis for the Phase 1 rule or the Phase 2 proposal but it is 

something the agencies could consider as a technology path under Alternative 4. As discussed 

earlier, diesel engines are fundamentally more efficient than gasoline engines providing the same 

power (even gasoline engines with the technologies discussed above). Alternative 4 could result 

in manufacturers switching from gasoline engines to diesel engines in certain challenging 

segments. However, while technologically feasible, this pathway could cause a distortion in 

consumer choices and significantly increase the cost of those vehicles, particularly considering 

Alternative 4 is projected to require penetration of some form of hybridization. Also, if 

dieselization occurs by manufacturers equipping vehicles with larger diesel engines rather than 

“right-sized” engines, the towing capability of the vehicles could increase resulting in higher 

work factors for the vehicles, higher targets, and reduced program benefits. The issue of surplus 

towing capability is also discussed above in VI.B. (1). 

The technologies associated with meeting the proposed standards are estimated to add 

costs to heavy-duty pickups and vans as shown in Table VI-12 and Table VI-13 for the flat 

baseline and dynamic baseline, respectively. These costs are the average fleet-wide incremental 

vehicle costs relative to a vehicle meeting the MY2018 standard in each of the model years 

shown. Reductions associated with these costs and technologies are considerable, estimated at a 

13.6 percent reduction of fuel consumption and CO2eq emissions from the MY 2018 baseline for 

gasoline and diesel engine equipped vehicles.362 A detailed cost and cost effectiveness analysis 

for both the proposed preferred Alternative 3 are provided in Section IX and Chapter 7.1 of the 

draft RIA. As shown by the analysis, the long-term cost effectiveness of the proposal is similar 

to that of the Phase 1 HD pickup and van standards and also falls within the range of the cost 

effectiveness for Phase 2 standards proposed for the other HD sectors. 363 The cost of controls 

would be fully recovered by the operator due to the associated fuel savings, with a payback 

period somewhere in the third year of ownership, as shown in Section IX.L of this preamble. 

Consistent with the agencies’ respective statutory authorities under CAA Section 202 (a) and 49 

U.S.C. 32902(k)(2)., and based on the agencies’ analysis, EPA and NHTSA are proposing 

Alternative 3. The agencies seek comment on Alternative 4, as we may seek to adopt it in whole 

or in part in the final rule. 

We also show the costs for the potential Alternative 4 standards in Table VI-14 and Table 

VI-15. As shown, the costs under Alternative 4 would be significantly higher compared to 

Alternative 3. 

 

362 See Table VI-5.

363 Analysis using the MOVES model indicates that the cost effectiveness of these standards is $95 per ton CO2 eq

removed in MY 2030 (Draft RIA Table 7-31), almost identical to the $90 per ton CO2 eq removed (MY 2030) which 

the agencies found to be highly cost effective for these same vehicles in Phase 1. See 76 FR 57228. 
Page 462 of 850

Table VI-12 HD Pickups and Vans Incremental Technology Costs per Vehicle

Preferred Alternative vs. Flat Baseline (2012$)

2021 2022 2023 2024 2025 2026 2027

HD Pickups & Vans $516 $508 $791 $948 $1,161 $1,224 $1,342

Table VI-13 HD Pickups and Vans Incremental Technology Costs per Vehicle

Preferred Alternative vs Dynamic Baseline (2012$)

2021 2022 2023 2024 2025 2026 2027

HD Pickups & Vans $493 $485 $766 $896 $1,149 $1,248 $1,366

Table VI-14 HD Pickups and Vans Incremental Technology Costs per Vehicle

Alternative 4 vs. Flat Baseline (2012$)

2021 2022 2023 2024 2025 2026 2027

HD Pickups & Vans $1,050 $1,033 $1,621 $1,734 $1,825 $1,808 $1,841

Table VI-15 HD Pickups and Vans Incremental Technology Costs per Vehicle

Alternative 4 vs. Dynamic Baseline (2012$)

2021 2022 2023 2024 2025 2026 2027

HD Pickups & Vans $909 $894 $1,415 $1,532 $1,627 $1,649 $1,684

D. DOT CAFE Model Analysis of the Regulatory Alternatives for HD 

Pickups and Vans

Considering the establishment of potential HD pickup and van fuel consumption and 

GHG standards to follow those already in place through model year 2018, the agencies evaluated 

a range of potential regulatory alternatives. The agencies estimated the extent to which 

manufacturers might add fuel-saving and CO2-avoiding technologies under each regulatory

alternative, including the no-action alternative described in Section X. of this proposal. For HD 

pickups and vans both agencies analyzed two no-action alternatives, where one no-action 

alternative could be described as a “flat baseline” and the other as a “dynamic baseline”. Please 

refer to Section X. of this proposal for a complete discussion of the assumptions that underlie 

these baselines. The agencies then estimated the extent to which additional technology that 

would be implemented to meet each regulatory alternative would incrementally (compared to the 

no-action alternative) impact costs to manufacturers and vehicle buyers, physical outcomes such 

as highway travel, fuel consumption, and greenhouse gas emissions, and economic benefits and 

costs to vehicle owners and society. The remainder of this section and portions of Sections VII 

through X present the regulatory alternatives the agencies have considered, summarize the 

agencies’ analyses, and explain the agencies’ selection of the HD pickup and van preferred 

alternative defined by today’s proposed standards.
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The agencies conducted coordinated and complementary analyses by employing both 

DOT’s CAFE model and EPA’s MOVES model and other analytical tools to project fuel 

consumption and GHG emissions impacts resulting from the proposed standards for HD pickups 

and vans, against both the flat and dynamic baselines. In addition to running the DOT CAFE

model to provide per vehicle cost and technology values, NHTSA also used the model to 

estimate the full range of impacts for pickups and vans, including fuel consumption and GHG 

emissions, including downstream vehicular emissions as well as emissions from upstream 

processes related to fuel production, distribution, and delivery. The CAFE model applies fuel 

properties (density and carbon content) to estimated fuel consumption in order to calculate 

vehicular CO2 emissions, applies per-mile emission factors (in this analysis, from MOVES) to 

estimated VMT in order to calculate vehicular CH4 and N2O emissions (as well, as discussed 

below, of non-GHG pollutants), and applies per-gallon upstream emission factors (in this 

analysis, from GREET) in order to calculate upstream GHG (and non-GHG) emissions. EPA 

also ran its MOVES model for all HD categories, namely tractors and trailers, vocational 

vehicles and HD pickups and vans, to develop a consistent set of fuel consumption and CO2

reductions for all HD categories. The MOVES runs followed largely the procedures described 

above, with some differences. MOVES used the same technology application rates and costs 

that are part of the inputs, and used cost per vehicle outputs of the CAFE model to evaluate the 

proposed standards for HD pickup trucks and vans. The agencies note that these two 

independent analyses of aggregate costs and benefits both support the proposed standards.

While both agencies fully analyzed the regulatory alternatives against both baselines, 

NHTSA considered its primary analysis to be based on the dynamic baseline, where certain costeffective technologies are assumed to be applied by manufacturers to improve fuel efficiency

beyond the Phase 1 requirements in the absence of new Phase 2 standards. On the other hand, 

EPA considered both baselines and EPA’s less dynamic or flat baseline analysis is presented in 

Sections VII through X of this proposal as well as the draft Regulatory Impact Analysis 

accompanying this proposal. In Section X both the flat and dynamic baseline analyses are 

presented for all of the regulatory alternatives. 

This section provides a discussion of the CAFE model, followed by the comprehensive 

results of the CAFE model against the dynamic baseline to show costs, benefits, and 

environmental impacts of the regulatory alternatives for HD pickups and vans. This presentation 

of regulatory analysis is consistent with NHTSA’s presentation of similar analyses conducted in 

support of the agencies joint light-duty vehicle fuel economy and GHG regulations. The CAFE 

analysis against the flat baseline as well as EPA’s complementary analysis of GHG impacts, 

non-GHG impacts, and economic and other impacts using MOVES is presented in Sections VII 

through IX of this proposal, as well as in the draft Regulatory Impact Analysis accompanying 

this proposal. These are presented side-by-side with the agencies’ joint analyses of the other 

heavy-duty sectors (i.e., tractors, trailers, vocational vehicles). The presentation of the EPA 

analyses of HD pickups and vans in these sections is consistent with the agencies’ presentation 

of similar analyses conducted as part of the agencies’ joint HD Phase 1 regulations and with 

EPA’s presentation of similar analyses conducted in support of the agencies’ joint light-duty

vehicle fuel economy and GHG regulations. The agencies’ intention for presenting both of 

these complementary and coordinated analyses is to offer interested readers the opportunity to 
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compare the regulatory alternatives considered for Phase 2 in both the context of our Phase 1 

analytical approaches and our light-duty vehicle analytical approaches.

(1) Evaluation of Regulatory Alternatives

As discussed in Section C above, the agencies used DOT’s CAFE model to conduct an 

analysis of potential standards for HD pickups and vans. The basic operation of the CAFE 

model was described in section VI.C.2, so will not be repeated here. However, this section 

provides additional detail on the model operation, inputs, assumptions, and outputs.

DOT developed the CAFE model in 2002 to support the 2003 issuance of CAFE 

standards for MYs 2005-2007 light trucks. DOT has since significantly expanded and refined 

the model, and has applied the model to support every ensuing CAFE rulemaking;

 2006: MYs 2008-2011 light trucks

 2008: MYs 2011-2015 passenger cars and light trucks (final rule prepared but 

withheld)

 2009: MY 2011 passenger cars and light trucks

 2010: MYs 2012-2016 passenger cars and light trucks (joint rulemaking with EPA)

 2012: MYs 2017-2021 passenger cars and light trucks (joint rulemaking with EPA)

Past analyses conducted using the CAFE model have been subjected to extensive and 

detailed review and comment, much of which has informed the model’s expansion and 

refinement. NHTSA’s use of the model was considered and supported in Center for Biological 

Diversity v. National Highway Traffic Safety Admin., 538 F.3d 1172, 1194 (9th Cir. 2008). For 

further discussion see 76 FR 57198, and the model has been subjected to formal peer review and 

review by the General Accounting Office (GAO) and National Research Council (NRC). 

NHTSA makes public the model, source code, and—except insofar as doing so would 

compromise confidential business information (CBI) manufacturers have provided to NHTSA—

all model inputs and outputs underlying published rulemaking analyses. 

This analysis reflects several changes made to the model since 2012, when NHTSA used 

the model to estimate the effects, costs, and benefits of final CAFE standards for light-duty 

vehicles produced during MYs 2017-2021, and augural standards for MYs 2022-2025. Some of 

these changes specifically enable analysis of potential fuel consumption standards (and, hence, 

related CO2 emissions standards harmonized with fuel consumption standards) for heavy-duty 

pickups and vans; other changes implement more general improvements to the model. Key

changes include the following:

 Expansion and restructuring of model inputs, compliance calculations, and reporting to 

accommodate standards for heavy-duty pickups and vans, including attribute-based 

standards involving targets that vary with “work factor”.
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 Explicit calculation of test weight, taking into account test weight “bins” and differences 

in the definition of test weight for light-duty vehicles (curb weight plus 300 pound) and 

heavy-duty pickups and vans (average of GVWR and curb weight).

 Procedures to estimate increases in payload when curb weight is reduced, increases in 

towing capacity if GVWR is reduced, and calculation procedures to correspondingly 

update calculated work factors.

 Expansion of model inputs, procedures, and outputs to accommodate technologies not 

included in prior analyses.

 Changes to the algorithm used to apply technologies, enabling more explicit accounting 

for shared vehicle platforms and adoption and “inheritance” of major engine changes.

 Expansion of the Monte Carlo simulation procedures used to perform probabilistic 

uncertainty analysis.

These changes are reflected in updated model documentation available at NHTSA’s web 

site, the documentation also providing more information about the model’s purpose, scope, 

structure, design, inputs, operation, and outputs. DOT invites comment on the updated model, 

and in particular, on the updated handling of shared vehicle platforms, engines, and 

transmissions, and on the new procedures to estimate changes to test weight, GVWR, and 

GCWR as vehicle curb weight is reduced.

(a) Product Cadence

Past comments on the CAFE model have stressed the importance of product cadence—

i.e., the development and periodic redesign and freshening of vehicles—in terms of involving 

technical, financial, and other practical constraints on applying new technologies, and DOT has 

steadily made changes to the model with a view toward accounting for these considerations. For 

example, early versions of the model added explicit “carrying forward” of applied technologies 

between model years, subsequent versions applied assumptions that most technologies would be 

applied when vehicles are freshened or redesigned, and more recent versions applied 

assumptions that manufacturers would sometimes apply technology earlier than “necessary” in 

order to facilitate compliance with standards in ensuing model years. Thus, for example, if a 

manufacturer is expected to redesign many of its products in model years 2018 and 2023, and the 

standard’s stringency increases significantly in model year 2021, the CAFE model will estimate 

the potential that the manufacturer will add more technology than necessary for compliance in 

MY 2018, in order to carry those product changes forward through the next redesign and 

contribute to compliance with the MY 2021 standard. 

The model also accommodates estimates of overall limits (expressed as “phase-in caps” 

in model inputs) on the rates at which manufacturers’ may practicably add technology to their 

respective fleets. So, for example, even if a manufacturer is expected to redesign half of its 

production in MY 2016, if the manufacturer is not already producing any strong hybrid electric 

vehicles (SHEVs), a phase-in cap can be specified in order to assume that manufacturer will stop 
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applying SHEVs in MY 2016 once it has done so to at least 3 percent of its production in that 

model year.

After the light-duty rulemaking analysis accompanying the 2012 final rule regarding 

post-2016 CAFE standards and related GHG emissions standards, DOT staff began work on 

CAFE model changes expected to better reflect additional considerations involved with product 

planning and cadence. These changes, summarized below, interact with preexisting model 

characteristics discussed above.

(b) Platforms and Technology

The term “platform” is used loosely in industry, but generally refers to a common 

structure shared by a group of vehicle variants. The degree of commonality varies, with some 

platform variants exhibiting traditional “badge engineering” where two products are 

differentiated by little more than insignias, while other platforms be used to produce a broad 

suite of vehicles that bear little outer resemblance to one another.

Given the degree of commonality between variants of a single platform, manufacturers 

do not have complete freedom to apply technology to a vehicle: while some technologies (e.g. 

low rolling resistance tires) are very nearly “bolt-on” technologies, others involve substantial 

changes to the structure and design of the vehicle, and therefore necessarily are constant between 

vehicles that share a common platform. DOT staff has, therefore, modified the CAFE model 

such that all mass reduction and aero technologies are forced to be constant between variants of a 

platform. The agencies request comment on the suitability of this viewpoint, and which 

technologies can deviate from one platform variant to another.

Within the analysis fleet, each vehicle is associated with a specific platform. As the 

CAFE model applies technology, it first defines a platform “leader” as the vehicle variant of a 

platform with the highest technology utilization vehicle of mass reduction and aerodynamic 

technologies. As the vehicle applies technologies, it effectively harmonizes to the highest 

common denominator of the platform. If there is a tie, the CAFE model begins applying 

aerodynamic and mass reduction technology to the vehicle with the lowest average sales across 

all available model years. If there remains a tie, the model begins by choosing the vehicle with 

the highest average MSRP across all available model years. The model follows this formulation 

due to previous market trends suggesting that many technologies begin deployment at the highend, low-volume end of the market as manufacturers build their confidence and capability in a 

technology, and later expand the technology across more mainstream product lines.

In the HD pickup and van market, there is a relatively small amount of diversity in 

platforms produced by manufacturers: typically 1-2 truck platforms and 1-2 van platforms. 

However, accounting for platforms will take on greater significance in future analyses involving 

the light-duty fleet, and the agency requests comments on the general use of platforms within 

CAFE rulemaking.
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(c) Engine and Transmission Inheritance

In practice, manufacturers are limited in the number of engines and transmissions that 

they produce. Typically a manufacturer produces a number of engines—perhaps six or eight 

engines for a large manufacturer—and tunes them for slight variants in output for a variety of car 

and truck applications. Manufacturers limit complexity in their engine portfolio for much the 

same reason as they limit complexity in vehicle variants: they face engineering manpower 

limitations, and supplier, production and service costs that scale with the number of parts 

produced.

In previous usage of the CAFE model, engines and transmissions in individual models 

were allowed relative freedom in technology application, potentially leading to solutions that 

would, if followed, involve unaccounted-for costs associated with increased complexity in the 

product portfolio. The lack of a constraint in this area allowed the model to apply different 

levels of technology to the engine in each vehicle at the time of redesign or refresh, independent 

of what was done to other vehicles using a previously identical engine.

In the current version of the CAFE model, engines and transmissions that are shared 

between vehicles must apply the same levels of technology in all technologies dictated by engine 

or transmission inheritance. This forced adoption is referred to as “engine inheritance” in the 

model documentation.

As with platform-shared technologies, the model first chooses an “engine leader” among 

vehicles sharing the same engine. The leader is selected first by the vehicle with the lowest 

average sales across all available model years. If there is a tie, the vehicle with the highest 

average MSRP across model years is chosen. The model applies the same logic with respect to 

the application of transmission changes. As with platforms, this is driven by the concept that 

vehicle manufacturers typically deploy new technologies in small numbers prior to deploying 

widely across their product lines. 

(d) Interactions between Regulatory Classes

Like earlier versions, the current CAFE model provides for integrated analysis spanning 

different regulatory classes, accounting both for standards that apply separately to different 

classes and for interactions between regulatory classes. Light vehicle CAFE standards are 

specified separately for passenger cars and light trucks. However, there is considerable sharing 

between these two regulatory classes. Some specific engines and transmissions are used in both 

passenger cars and light trucks, and some vehicle platforms span these regulatory classes. For 

example, some sport-utility vehicles are offered in 2WD versions classified as passenger cars and 

4WD versions classified as light trucks. Integrated analysis of manufacturers’ passenger car and 

light truck fleets provides the ability to account for such sharing and reduce the likelihood of 

finding solutions that could involve impractical levels of complexity in manufacturers’ product 

lines. In addition, integrated analysis provides the ability to simulate the potential that 

manufactures could earn CAFE credits by over complying with one standard and use those

credits toward compliance with the other standard (i.e., to simulate credit transfers between 

regulatory classes).
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HD pickups and vans are regulated separately from light-duty vehicles. While 

manufacturers cannot transfer credits between light-duty and MDHD classes, there is some 

sharing of engineering and technology between light-duty vehicles and HD pickups and vans. 

For example, some passenger vans with GVWR over 8,500 pounds are classified as mediumduty passenger vehicles (MDPVs) and thus included in manufacturers’ light-duty truck fleets, 

while cargo vans sharing the same nameplate are classified as HD vans.

While today’s analysis examines the HD pickup and van fleet in isolation, as a basis for 

analysis supporting the planned final rule, the agencies intend to develop an overall analysis fleet 

spanning both the light-duty and HD pickup and van fleets. Doing so could show some 

technology “spilling over” to HD pickups and vans due, for example, to the application of 

technology in response to current light-duty standards. More generally, modeling the two fleets 

together should tend to more realistically limit the scope and complexity of estimated 

compliance pathways.

The agencies anticipate that the impact of modeling a combined fleet will primarily arise 

from engine-transmission inheritance. While platform sharing between the light-duty and MD 

pickup and van fleets is relatively small (MDPVs aside), there are a number of instances of 

engine and transmission sharing across the two fleets. When the fleets are modeled together, the 

agencies anticipate that engine inheritance will be implemented across the combined fleet, and 

therefore only one engine-transmission leader can be defined across the combined fleet. As with 

the fleets separately, all vehicles using a shared engine/transmission would automatically adopt 

technologies adopted by the engine-transmission leader.

The agencies request comment on plans to analyze the light-duty and MD pickup and van 

fleets jointly in support of planning for the final rule.

(e) Phase-In Caps

The CAFE model retains the ability to use phase-in caps (specified in model inputs) as 

proxies for a variety of practical restrictions on technology application. Unlike vehicle-specific 

restrictions related to redesign, refreshes or platforms/engines, phase-in caps constrain 

technology application at the vehicle manufacturer level. They are intended to reflect a 

manufacturer's overall resource capacity available for implementing new technologies (such as 

engineering and development personnel and financial resources), thereby ensuring that resource 

capacity is accounted for in the modeling process.

In previous CAFE rulemakings, redesign/refresh schedules and phase-in caps were the 

primary mechanisms to reflect an OEM's limited pool of available resources during the 

rulemaking time frame and the years leading up to the rulemaking time frame, especially in years 

where many models may be scheduled for refresh or redesign. The newly-introduced 

representation platform-, engine-, and transmission-related considerations discussed above 

augment the model’s preexisting representation of redesign cycles and accommodation of phasein caps. Considering these new constraints, inputs for today’s analysis de-emphasize reliance on 

phase-in caps.
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In this application of the CAFE model, phase-in caps are used only for the most advanced 

technologies included in the analysis, i.e., SHEVs and lean-burn GDI engines, considering that 

these technologies are most likely to involve implementation costs and risks not otherwise 

accounted for in corresponding input estimates of technology cost. For these two technologies, 

the agencies have applied caps that begin at 3 percent (i.e., 3 percent of the manufacturer’s 

production) in MY 2017, increase at 3 percent annually during the ensuing nine years (reaching 

30 percent in the MY 2026), and subsequently increasing at 5 percent annually for four years 

(reaching 50 percent in MY 2030). Note that the agencies did not feel that lean-burn engines 

were feasible in the timeframe of this rulemaking, so decided to reject any model runs where 

they were selected. Due to the cost ineffectiveness of this technology, it was never chosen. The 

agencies request comment on the appropriateness of these phase-in caps as proxies for 

constraints that, though not monetized by the agencies, nonetheless limit rates at which these two 

technologies can practicably be deployed, and on the appropriateness of setting inputs to stop 

applying phase-in caps to other technologies in this analysis. Comments on this issue should 

provide information supporting any alternative recommended inputs.

(f) Impact of Vehicle Technology Application Requirements

Compared to prior analyses of light-duty standards, these model changes, along with 

characteristics of the HD pickup and van fleet result in some changes in the broad characteristics 

of the model’s application of technology to manufacturers’ fleets. First, since the number of HD 

pickup and van platforms in a portfolio is typically small, compliance with standards may appear 

especially “lumpy” (compared to previous applications of the CAFE model to the more highly 

segmented light-duty fleet), with significant over compliance when widespread redesigns 

precede stringency increases, and/or significant application of carried-forward (aka “banked”) 

credits.

Second, since the use of phase-in caps has been de-emphasized and manufacturer 

technology deployment remains tied strongly to estimated product redesign and freshening 

schedules, technology penetration rates may jump more quickly as manufacturers apply 

technology to high-volume products in their portfolio.

By design, restrictions that enforce commonality of mass reduction and aerodynamic 

technologies on variants of a platform, and those that enforce engine inheritance, will result in 

fewer vehicle-technology combinations in a manufacturer’s future modeled fleet. These 

restrictions are expected to more accurately capture the true costs associated with producing and 

maintaining a product portfolio.

(g) Accounting for Test Weight, Payload, and Towing Capacity

As mentioned above, NHTSA has also revised the CAFE model to explicitly account for 

the regulatory “binning” of test weights used to certify light-duty fuel economy and HD pickup 

and van fuel consumption for purposes of evaluating fleet-level compliance with fuel economy 

and fuel consumption standards. For HD pickups and vans, test weight (TW) is based on 

adjusted loaded vehicle weight (ALVW), which is defined as the average of gross vehicle weight 

rating (GVWR) and curb weight (CW). TW values are then rounded, resulting in TW “bins”:
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ALVW ≤ 4,000 lb.: TW rounded to nearest 125 lb.

4000 lb. < ALVW ≤ 5,500 lb.: TW rounded to nearest 250 lb.

ALVW > 5,500 lb.: TW rounded to nearest 500 lb.

This “binning” of TW is relevant to calculation of fuel consumption reductions 

accompanying mass reduction. Model inputs for mass reduction (as an applied technology) are 

expressed in terms of a percentage reduction of curb weight and an accompanying estimate of 

the percentage reduction in fuel consumption, setting aside rounding of test weight. Therefore, 

to account for rounding of test weight, NHTSA has modified these calculations as follows:

∆_ = ∆ ×

∆_

∆

where:

∆CW = % change in curb weight (from model input),

∆FCunrounded_TW = % change in fuel consumption (from model input), without TW 

rounding,

∆TW = % change in test weight (calculated), and

∆FCrounded_TW = % change in fuel consumption (calculated), with TW rounding.

As a result, some applications of vehicle mass reduction will produce no compliance 

benefit at all, in cases where the changes in ALVW are too small to change test weight when 

rounding is taken into account. On the other hand, some other applications of vehicle mass

reduction will produce significantly more compliance benefit than when rounding is not taken 

into account, in cases where even small changes in ALVW are sufficient to cause vehicles’ test 

weights to increase by, e.g., 500 pounds when rounding is accounted for. Model outputs now 

include initial and final TW, GVWR, and GCWR (and, as before, CW) for each vehicle model in 

each model year, and the agencies invite comment on the extent to which these changes to 

account explicitly for changes in TW are likely to produce more realistic estimates of the 

compliance impacts of reductions in vehicle mass.

In addition, considering that the regulatory alternatives in the agencies’ analysis all 

involve attribute-based standards in which underlying fuel consumption targets vary with “work 

factor” (defined by the agencies as the sum of three quarters of payload, one quarter of towing 

capacity, and 500 lb. for vehicles with 4WD), NHTSA has modified the CAFE model to apply 

inputs defining shares of curb weight reduction to be “returned” to payload and shares of GVWR 

reduction to be returned to towing capacity. The standards’ dependence on work factor provides 

some incentive to increase payload and towing capacity, both of which are buyer-facing 

measures of vehicle utility. In the agencies’ judgment, this provides reason to assume that if 

vehicle mass is reduced, manufacturers are likely to “return” some of the change to payload 

and/or towing capacity. For this analysis, the agencies have applied the following assumptions:
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 GVWR will be reduced by half the amount by which curb weight is reduced. In other 

words, 50 percent of the curb weight reduction will be returned to payload.

 GCWR will not be reduced. In other words, 100 percent of any GVWR reduction 

will be returned to towing capacity.

 GVWR/CW and GCWR/GVWR will not increase beyond levels observed among the 

majority of similar vehicles (or, for outlier vehicles, initial values):

Table VI-16 Ratios for Modifying GVW and GCW as a Function of Mass Reduction

Maximum Ratios Assumed Enabled by 

Mass Reduction

Group GVWR/CW GCWR/GVWR

Unibody 1.75 1.50

Gasoline pickups > 13k GVWR 2.00 1.50

Other gasoline pickups 1.75 2.25

Diesel SRW pickups 1.75 2.50

All other 1.75 2.25

The first of two of these inputs are specified along with standards for each regulatory

alternative, and the GVWR/CW and GCWR/GVWR “caps” are specified separately for each 

vehicle model in the analysis fleet.

In addition, DOT has changed the model to prevent HD pickup and van GVWR from 

falling below 8,500 pounds when mass reduction is applied (because doing so would cause 

vehicles to be reclassified as light-duty vehicles), and to treat any additional mass for hybrid 

electric vehicles as reducing payload by the same amount (e.g., if adding a strong HEV package 

to a vehicle involves a 350 pound penalty, GVWR is assumed to remain unchanged, such that 

payload is also reduced by 350 pounds).

The agencies invite comment on these methods for estimating how changes in vehicle 

mass may impact fuel consumption, GVWR, and GCWR, and on corresponding inputs to today’s 

analysis.

(2) Development of the Analysis Fleet

As discussed above, both agencies used DOT’s CAFE modeling system to estimate 

technology costs and application rates under each regulatory alternative, including the no action 

alternative (which reflects continuation of previously-promulgated standards). Impacts under 

each of the “action” alternatives are calculated on an incremental basis relative to impacts under 

the no action alternative. The modeling system relies on many inputs, including an analysis 

fleet. In order to estimate the impacts of potential standards, it is necessary to estimate the 

composition of the future vehicle fleet. Doing so enables estimation of the extent to which each 

manufacturer may need to add technology in response to a given series of attribute-based 

standards, accounting for the mix and fuel consumption of vehicles in each manufacturer’s 

regulated fleet. The agencies create an analysis fleet in order to track the volumes and types of 

fuel economy-improving and CO2 -reducing technologies that are already present in the existing 

vehicle fleet. This aspect of the analysis fleet helps to keep the CAFE model from adding 
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technologies to vehicles that already have these technologies, which would result in “double 

counting” of technologies’ costs and benefits. An additional step involved projecting the fleet 

sales into MYs 2019-2030. This represents the fleet volumes that the agencies believe would 

exist in MYs 2019-2030. The following presents an overview of the information and methods 

applied to develop the analysis fleet, and some basic characteristics of that fleet. 

The resultant analysis fleet is provided in detail at NHTSA’s web site, along with all 

other inputs to and outputs from today’s analysis. The agencies invite comment on this analysis 

fleet and, in particular, on any other information that should be reflected in an analysis fleet used 

to update the agencies’ analysis for the final rule. Also, the agencies also invites comment on the 

potential expansion of this analysis fleet such that the impacts of new HD pickup and van 

standards can be estimated within the context of an integrated analysis of light-duty vehicles and 

HD pickups and vans, accounting for interactions between the fleets.

(a) Data Sources

Most of the information about the vehicles that make up the 2014 analysis fleet was 

gathered from the 2014 Pre-Model Year Reports submitted to EPA by the manufacturers under 

Phase 1 of Fuel Efficiency and GHG Emission Program for Medium- and Heavy-Duty Trucks, 

MYs 2014-2018.

The major manufacturers of class 2b and class 3 trucks (Chrysler, Ford and GM) were 

asked to voluntarily submit updates to their Pre-Model Year Reports. Updated data were 

provided by Chrysler and GM. These updated data were used in constructing the analysis fleet 

for these manufacturers.

The agencies agreed to treat this information as Confidential Business Information (CBI) 

until the publication of the NPRM. This information can be made public at this time because by 

now all MY2014 vehicle models have been produced, which makes data about them essentially

public information.

These data (by individual vehicle configuration produced in MY2014) include: Projected 

Production Volume/MY2014 Sales, Drive Type, Axle Ratio, Work Factor, Curb Weight, Test 

Weight364, GVWR, GCWR, Fuel Consumption (gal/100 mile), engine type (gasoline or diesel), 

engine displacement, transmission type and number of gears.

The column “Engine” of the Pre-Model Year report for each OEM was copied to the 

column “Engine Code” of the vehicle sheet of the CAFE model market data input file. Values of 

“Engine” were changed to Engine Codes for use in the CAFE model. The codes indicated on the 

vehicle sheet map the detailed engine data on the engine sheet to the appropriate vehicle on the 

vehicle sheet of the CAFE model input file.

 

364 Chrysler and GM did not provide test weights in their submittals. Test weights were calculated as the average of 

GVWR and curb weight rounded up to the nearest 100 lb.
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The column “Trans Class” of the Pre-Model Year report for each OEM was copied to the 

column “Transmission Code” of the vehicle sheet of the market data input file. Values of 

“Trans Class” were changed to Transmission Codes for use in the CAFE model. The codes 

indicated on the vehicle sheet map the detailed transmission data on the transmission sheet to the 

appropriate vehicle on the vehicle sheet of the CAFE model input file.

In addition to information about each vehicle, the agencies need additional information 

about the fuel economy-improving/CO2-reducing technologies already on those vehicles in order 

to assess how much and which technologies to apply to determine a path toward future 

compliance. Thus, the agencies augmented this information with publicly-available data that 

includes more complete technology descriptions. Specific engines and transmissions associated 

with each manufacturer’s trucks were identified using their respective internet sites. Detailed 

technical data on individual engines and transmissions indicated on the engine sheet and 

transmission sheet of the CAFE model input file were then obtained from manufacturer internet 

sites, spec sheets and product literature, Ward’s Automotive Group and other commercial 

internet sites such as cars.com, edmunds.com, and motortrend.com. Specific additional 

information included:

 “Fuel Economy on Secondary Fuel” was calculated as E85 = .74 gasoline fuel 

economy, or B20 = .98 diesel fuel economy. These values were duplicated in the 

columns “Fuel Economy (Ethanol-85)” and “Fuel Economy (Biodiesel-20)” of the 

CAFE market data input file. 

 Values in the columns “Fuel Share (Gasoline)”, “Fuel Share (Ethanol-85)”, “Fuel 

Share (Diesel),” and “Fuel Share (Biodiesel-20)” are Volpe assumptions.

 The CAFE model also requires that values of Origin, Regulatory Class, Technology

Class, Safety Class, and Seating (Max) be present in the file in order for the model to 

run. Placeholder values were added in these columns.

 In addition to the data taken from the OEM Pre Model Year submittals, NHTSA 

added additional data for use by the CAFE model. These included Platform, Refresh 

Years, Redesign Years, MSRP, Style, Structure and Fuel Capacity.

 MSRP was obtained from web2carz.com and the OEM web sites.

 Fuel capacity was obtained from OEM spec sheets and product literature.

 The Structure values (Ladder, Unibody) used by the CAFE model were added. These 

were determined from OEM product literature and the automotive press. It should be 

noted that the new vans such as the Transit in fact utilize a ladder/unibody structure. 

Ford product literature uses the term “Uniladder” to describe the structure. Vans 

based on this structure are noted in the Vehicle Notes column of the NHTSA input 

file.
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 Style values used by the CAFE model were also added: Chassis Cab, Cutaway, 

Pickup and Van.

(b) Vehicle Redesign Schedules and Platforms 

Product cadence in the Class 2b and 3 pickup market has historically ranged from 7-9 

years between major redesigns. However, due to increasing competitive pressures and consumer 

demands the agency anticipates that manufacturers will generally shift to shorter design cycles 

resembling those of the light duty market. Pickup truck manufacturers in the Class 2b and 3 

segments are shown to adopt redesign cycles of six years, allowing two redesigns prior to the end 

of the regulatory period in 2025. The agencies request comment on the anticipated future use of 

redesign cycles in this product segment. 

The Class 2b and 3 van market has changed markedly from five years ago. Ford, Nissan, 

Ram and Daimler have adopted vans of “Euro Van” appearance, and in many cases now use 

smaller turbocharged gasoline or diesel engines in the place of larger, naturally-aspirated V8s. 

The 2014 Model Year used in this analysis represents a period where most manufacturers, with 

the exception of General Motors, have recently introduced a completely redesigned product after 

many years. The van segment has historically been one of the slowest to be redesigned of any

product segment, with some products going two decades or more between redesigns.

Due to new entrants in the field and increased competition, the agencies anticipate that 

most manufacturers will increase the pace of product redesigns in the van segment, but that they

will continue to trail other segments. The cycle time used in this analysis is approximately ten 

years between major redesigns, allowing manufacturers only one major redesign during the 

regulatory period. The agencies request comment on this anticipated product design cycle.

Additional detail on product cadence assumptions for specific manufacturers is located in 

Chapter 10 of the draft RIA.

(c) Sales Volume Forecast

Since each manufacturer’s required average fuel consumption and GHG levels are salesweighted averages of the fuel economy/GHG targets across all model offerings, sales volumes 

play a critical role in estimating that burden. The CAFE model requires a forecast of sales 

volumes, at the vehicle model-variant level, in order to simulate the technology application 

necessary for a manufacturer to achieve compliance in each model year for which outcomes are 

simulated.

For today’s analysis, the agencies relied on the MY 2014 pre-model-year compliance 

submissions from manufacturers to provide sales volumes at the model level based on the level 

of disaggregation in which the models appear in the compliance data. However, the agencies 

only use these reported volumes without adjustment for MY 2014. For all future model years, 
Page 475 of 850

we combine the manufacturer submissions with sales projections from the 2014 Annual Energy

Outlook Reference Case and IHS Automotive to determine model variant level sales volumes in 

future years.368 The projected sales volumes by class that appear in the 2014 Annual Energy

Outlook as a result of a collection of assumptions about economic conditions, demand for 

commercial miles traveled, and technology migration from light-duty pickup trucks in response 

to the concurrent light-duty CAFE/GHG standards. These are shown in Chapter 2 of the draft 

RIA.

For this analysis, the agencies have limited this analysis fleet to class 2b and 3 HD 

pickups and vans. However, especially considering interactions between the light-duty and HD 

pickup and van fleets (e.g., MDPVs being included in the light-duty fleet), the agencies are 

evaluating the potential to analyze the fleets in an integrated fashion for the final rule, and invite 

comment on the extent to which doing so could provide more realistic estimates of the 

incremental impacts of new standards applicable HD pickups and vans.

The projection of total sales volumes for the Class 2b and 3 market segment was based on 

the total volumes in the 2014 AEO Reference Case. For the purposes of this analysis, the 

AEO2014 calendar year volumes have been used to represent the corresponding model-year 

volumes. While AEO2014 provides enough resolution in its projections to separate the volumes 

for the Class 2b and 3 segments, the agencies deferred to the vehicle manufacturers and chose to 

rely on the relative shares present in the pre-model-year compliance data.

The relative sales share by vehicle type (van or pickup truck, in this case) was derived 

from a sales forecast that the agencies purchased from IHS Automotive, and applied to the total 

volumes in the AEO2014 projection. Table VI-17 shows the implied shares of the total new 2b/3 

vehicle market broken down by manufacturer and vehicle type. 

 

368 Tables from AEO’s forecast are available at http://www.eia.gov/oiaf/aeo/tablebrowser/. The agencies also made 

use of the IHS Automotive Light Vehicle Production Forecast (August 2014).
Page 476 of 850

Table VI-17 IHS Automotive Market Share Forecast for 2b/3 vehicles

Model Year Market Share

Manufacturer Style 2015 2016 2017 2018 2019 2020 2021

Daimler Van 3% 3% 3% 3% 3% 3% 3%

Fiat Van 2% 2% 2% 2% 2% 2% 3%

Ford Van 16% 17% 17% 17% 18% 18% 18%

General Motors Van 12% 12% 11% 12% 13% 13% 13%

Nissan Van 2% 2% 2% 2% 2% 2% 2%

Daimler Pickup 0% 0% 0% 0% 0% 0% 0%

Fiat Pickup 14% 14% 14% 14% 11% 12% 12%

Ford Pickup 28% 27% 30% 30% 30% 27% 26%

General Motors Pickup 23% 23% 21% 21% 21% 22% 23%

Nissan Pickup 0% 0% 0% 0% 0% 0% 0%

Within those broadly defined market shares, volumes at the manufacturer/model-variant 

level were constructed by applying the model-variant’s share of manufacturer sales in the premodel-year compliance data for the relevant vehicle style, and multiplied by the total volume 

estimated for that manufacturer and that style.

After building out a set of initial future sales volumes based on the sources described 

above, the agencies attempted to incorporate new information about changes in sales mix that 

would not be captured by either the existing sales forecasts or the simulated technology changes 

in vehicle platforms. In particular, Ford has announced intentions to phase out their existing 

Econoline vans, gradually shifting volumes to the new Transit platform for some model variants 

(notably chassis cabs and cutaways variants) and eliminating offerings outright for complete 

Econoline vans as early as model year 2015. In the case of complete Econoline vans, the 

volumes for those vehicles were allocated to MY2015 Transit vehicles based on assumptions 

about likely production splits for the powertrains of the new Transit platform. The volumes for 

complete Econoline vans were shifted at ratios of 50 percent, 35 percent, and 15 percent for 3.7 

L, 3.5 L Eco-boost, and 3.2 L diesel, respectively. Within each powertrain, sales were allocated 

based on the percentage shares present in the pre-model-year compliance data. The chassis cab 

and cutaway variants of the Econolines were phased out linearly between MY2015 and MY2020, 

at which time the Econolines cease to exist in any form and all corresponding volume resides 

with the Transits.

(3) Additional Technology Cost and Effectiveness Inputs

In addition to the base technology cost and effectiveness inputs described in I. of this 

preamble, the CAFE model has some additional cost and effectiveness inputs, described as 

follows.

The CAFE model accommodates inputs to adjust accumulated effectiveness under 

circumstances when combining multiple technologies could result in underestimation or 
Page 477 of 850

overestimation of total incremental effectiveness relative to an “unevolved” baseline vehicle. 

These so-called synergy factors may be positive, where the combination of the technologies 

results in greater improvement than the additive improvement of each technology, or negative, 

where the combination of the technologies is lower than the additive improvement of each 

technology. The synergy factors used in this analysis are described in VI-18.

Table VI-18 Technology Pair Effectiveness Synergy Factors for HD Pickups and Vans

Technology 

Pair

Adjustment Technology Pair Adjustment

8SPD/CCPS -4.60% IATC/CCPS -1.30%

8SPD/DEACO -4.60% IATC/DEACO -1.30%

8SPD/ICP -4.60% IATC/ICP -1.30%

8SPD/TRBDS1 4.60% IATC/TRBDS1 1.30%

AERO2/SHEV1 1.40% MR1/CCPS 0.40%

CCPS/IACC1 -0.40% MR1/DCP 0.40%

CCPS/IACC2 -0.60% MR1/VVA 0.40%

DCP/IACC1 -0.40% MR2/ROLL1 -0.10%

DCP/IACC2 -0.60% MR2/SHEV1 -0.40%

DEACD/IATC -0.10% NAUTO/CCPS -1.70%

DEACO/IACC2 -0.80% NAUTO/DEACO -1.70%

DEACO/MHEV -0.70% NAUTO/ICP -1.70%

DEACS/IATC -0.10% NAUTO/SAX -0.40%

DTURB/IATC 1.00% NAUTO/TRBDS1 1.70%

DTURB/MHEV -0.60% ROLL1/AERO1 0.10%

DTURB/SHEV1 -1.00% ROLL1/SHEV1 1.10%

DVVLD/8SPD -0.60% ROLL2/AERO2 0.20%

DVVLD/IACC2 -0.80% SHFTOPT/MHEV -0.30%

DVVLD/IATC -0.60% TRBDS1/MHEV 0.80%

DVVLD/MHEV -0.70% TRBDS1/SHEV1 -3.30%

DVVLS/8SPD -0.60% TRBDS1/VVA -8.00%

DVVLS/IACC2 -0.80% TRBDS2/EPS -0.30%

DVVLS/IATC -0.50% TRBDS2/IACC2 -0.30%

DVVLS/MHEV -0.70% TRBDS2/NAUTO -0.50%

VVA/IACC1 -0.40%

VVA/IACC2 -0.60%

VVA/IATC -0.60%

The CAFE model also accommodates inputs to adjust accumulated incremental costs 

under circumstances when the application sequence could result in underestimation or 

overestimation of total incremental costs relative to an “unevolved” baseline vehicle. For 
Page 478 of 850

today’s analysis, the agencies have applied one such adjustment, increasing the cost of mediumsized gasoline engines by $513 in cases where turbocharging and engine downsizing is applied 

with variable valve actuation.

The analysis performed using Method A also applied cost inputs to address some costs 

encompassed neither by the agencies’ estimates of the direct cost to apply these technologies, nor 

by the agencies’ methods for “marking up” these costs to arrive at increases in the new vehicle 

purchase costs. To account for the additional costs that could be incurred if a technology is 

applied and then quickly replaced, the CAFE model accommodates inputs specifying a “stranded 

capital cost” specific to each technology. For this analysis, the model was run with inputs to 

apply about $78 of additional cost (per engine) if gasoline engine turbocharging and downsizing 

(separately for each “level” considered) is applied and then immediately replaced, declining 

steadily to zero by the tenth model year following initial application of the technology. The 

model also accommodates inputs specifying any additional changes owners might incur in 

maintenance and post-warranty repair costs. For this analysis, the model was run with inputs 

indicating that vehicles equipped with less rolling-resistant tires could incur additional tire 

replacement costs equivalent to $21-$23 (depending on model year) in additional costs to 

purchase the new vehicle. The agencies did not, however, include inputs specifying any 

potential changes repair costs that might accompany application of any of the above 

technologies. A sensitivity analysis using Method A, discussed below, includes a case in which

repair costs are estimated using factors consistent with those underlying the indirect cost 

multipliers used to mark up direct costs for the agencies’ central analysis.

The agencies invite comment on all efficacy and cost inputs involved in today’s analysis 

and request that commenters provide any additional data or forward-looking estimates that could 

be used to support alternative inputs, including those related to costs beyond those reflected in 

the cost to purchase new vehicles.

(4) Other Analysis Inputs

In addition to the inputs summarized above, the analysis of potential standards for HD 

pickups and vans makes use of a range of other estimates and assumptions specified as inputs to 

the CAFE modeling system. Some significant inputs (e.g., estimates of future fuel prices) also 

applicable to other MDHD segments are discussed below in Section IX. Others more specific to 

the analysis of HD pickups and vans are as follows:

(a) Vehicle Survival and Mileage Accumulation: 

Today’s analysis estimates the travel, fuel consumption, and emissions over the useful 

lives of vehicles produced during model years 2014-2030. Doing so requires initial estimates of 

these vehicles’ survival rates (i.e., shares expected to remain in service) and mileage 

accumulation rates (i.e., anticipated annual travel by vehicles remaining in service), both as a 

function of vehicle vintage (i.e., age). These estimates are based on an empirical analysis of 

changes in the fleet of registered vehicles over time, in the case of survival rates, and usage data 

collected as part of the last Vehicle In Use Survey (the 2002 VIUS), in the case of mileage 

accumulation.
Page 479 of 850

(b) Rebound Effect

Expressed as an elasticity of mileage accumulation with respect to the fuel cost per mile 

of operation, the agencies have applied a rebound effect of 10 percent for today’s analysis.

(c) On-Road "Gap"

The model was run with a 20 percent adjustment to reflect differences between on-road 

and laboratory performance.

(d) Fleet Population Profile

Though not reported here, cumulative fuel consumption and CO2 emissions are presented 

in the accompanying draft EIS, and these calculations utilize estimates of the numbers of 

vehicles produced in each model year remaining in service in calendar year 2014. The initial age 

distribution of the registered vehicle population in 2014 is based on vehicle registration data 

acquired by NHTSA from R.L. Polk Company. 

(e) Past Fuel Consumption Levels

Though not reported here, cumulative fuel consumption and CO2 emissions are presented 

in the accompanying draft EIS, and these calculations require estimates of the performance of 

vehicles produced prior to model year 2014. Consistent with AEO 2014, the model was run with 

the assumption that gasoline and diesel HD pickups and vans averaged 14.9 mpg and 18.6 mpg, 

respectively, with gasoline versions averaging about 48 percent of production.

(f) Long-Term Fuel Consumption Levels

Though not reported here, longer-term estimates of fuel consumption and emissions are 

presented in the accompanying draft EIS. These estimates include calculations involving vehicle 

produced after MY 2030 and, consistent with AEO 2014, the model was run with the assumption

that fuel consumption and CO2 emission levels will continue to decline at 0.05 percent annually 

(compounded) after MY 2030.

(g) Payback Period

To estimate in what sequence and to what degree manufacturers might add fuel-saving 

technologies to their respective fleets, the CAFE model iteratively ranks remaining opportunities 

(i.e., applications of specific technologies to specific vehicles) in terms of effective cost, primary

components of which are the technology cost and the avoided fuel outlays, attempting to 

minimize effective costs incurred.369 Depending on inputs, the model also assumes 

manufacturers may improve fuel consumption beyond requirements insofar as doing so will 

involve applications of technology at negative effective cost—i.e., technology application for 

 

369 Volpe CAFE Model, available at http://www.nhtsa.gov/fuel-economy
Page 480 of 850

which buyers’ up-front costs are quickly paid back through avoided fuel outlays. This 

calculation includes only fuel outlays occurring within a specified payback period. For this

analysis, a payback period of 6 months was applied for the dynamic baseline case, or Alternative 

1b. Thus, for example, a manufacturer already in compliance with standards is projected to 

apply a fuel consumption improvement projected to cost $250 (i.e., as a cost that could be 

charged to the buyer at normal profit to the manufacturer) and reduce fuel costs by $500 in the 

first year of vehicle operation. The agencies have conducted the same analysis applying a 

payback period of 0 months for the flat baseline case, or Alternative 1a. 

(h) Civil Penalties

EPCA and EISA require that a manufacturer pay civil penalties if it does not have enough 

credits to cover a shortfall with one or both of the light-duty CAFE standards in a model year. 

While these provisions do not apply to HD pickups and vans, at this time, the CAFE model will 

show civil penalties owed in cases where available technologies and credits are estimated to be 

insufficient for a manufacturer to achieve compliance with a standard. These model-reported 

estimates have been excluded from this analysis.

(i) Coefficients for Fatality Calculations

Today’s analysis considered the potential effects on crash safety of the technologies 

manufacturers may apply to their vehicles to meet each of the regulatory alternatives. NHTSA 

research has shown that vehicle mass reduction affects overall societal fatalities associated with 

crashes370 and, most relevant to this proposal, mass reduction in heavier light- and medium-duty 

vehicles has an overall beneficial effect on societal fatalities. Reducing the mass of a heavier 

vehicle involved in a crash with another vehicle(s) makes it less likely there will be fatalities 

among the occupants of the other vehicles. In addition to the effects of mass reduction, the 

analysis anticipates that the proposed standards, by reducing the cost of driving HD pickups and 

vans, would lead to increased travel by these vehicles and, therefore, more crashes involving 

these vehicles. The Method A analysis considers overall impacts considering both of these 

factors, using a methodology similar to NHTSA’s analyses for the MYs 2017 – 2025 CAFE and 

GHG emission standards.

The Method A analysis includes estimates of the extent to which HD pickups and vans 

produced during MYs 2014-2030 may be involved in fatal crashes, considering the mass, 

survival, and mileage accumulation of these vehicles, taking into account changes in mass and 

mileage accumulation under each regulatory alternative. These calculations make use of the 

same coefficients applied to light trucks in the MYs 2017-2025 CAFE rulemaking analysis. 

Baseline rates of involvement in fatal crashes are 13.03 and 13.24 fatalities per billion miles for 

vehicles with initial curb weights above and below 4,594 pounds, respectively. Considering that 

the data underlying the corresponding statistical analysis included observations through calendar 

 

370 U.S. DOT/NHTSA, Relationships Between Fatality Risk Mass and Footprint in MY 2000-2007 PC and LTVs, 

ID: NHTSA-2010-0131-0336, Posted August 21, 2012.
Page 481 of 850

year 2010, these rates are reduced by 9.6 percent to account for subsequent impacts of recent 

Federal Motor Vehicle Safety Standards (FMVSS) and anticipated behavioral changes (e.g., 

continued increases in seat belt use). For vehicles above 4,594 pounds—i.e., the majority of the 

HD pickup and van fleet—mass reduction is estimated to reduce the net incidence of highway

fatalities by 0.34 percent per 100 pounds of removed curb weight. For the few HD pickups and 

vans below 4,594 pounds, mass reduction is estimated to increase the net incidence of highway

fatalities by 0.52 percent per 100 pounds. Consistent with DOT guidance, the social cost of 

highway fatalities is estimated using a value of statistical life (VSL) of $9.36m in 2014, 

increasing thereafter at 1.18 percent annually.

(j) Compliance Credit Provisions

Today’s analysis accounts for the potential to over comply with standards and thereby

earn compliance credits, applying these credits to ensuring compliance requirements. In doing 

so, the agencies treat any unused carried-forward credits as expiring after five model years, 

consistent with current and proposed standards. For today’s analysis, the agencies are not 

estimating the potential to “borrow”—i.e., to carry credits back to past model years.

(k) Emission Factors

While CAFE model calculates vehicular CO2 emissions directly on a per-gallon basis 

using fuel consumption and fuel properties (density and carbon content), the model calculates 

emissions of other pollutants (methane, nitrogen oxides, ozone precursors, carbon monoxide, 

sulfur dioxide, particulate matter, and air toxics) on a per-mile basis. In doing so, the Method A 

analysis used corresponding emission factors estimated using EPA’s MOVES model.373 To 

estimate emissions (including CO2) from upstream processes involved in producing, distributing, 

and delivering fuel, NHTSA has applied emission factors—all specified on a gram per gallon 

basis—derived from Argonne National Laboratory’s GREET model.374

(l) Refueling Time Benefits

To estimate the value of time savings associated with vehicle refueling, the Method A 

analysis used estimates that an average refueling event involves refilling 60 percent of the tank’s 

capacity over the course of 3.5 minutes, at an hourly cost of $27.22.

(m) External Costs of Travel

Changes in vehicle travel will entail economic externalities. To estimate these costs, the Method 

A analysis used estimates that congestion-, accident-, and noise-related externalities will total 5.1 

¢/mi., 2.8 ¢/mi., and 0.1 ¢/mi., respectively.

 

373 EPA MOVES model available at http://www.epa.gov/otaq/models/moves/index.htm (last accessed Feb 23, 

2015).

374 GREET (Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation) Model, Argonne National 

Laboratory, https://greet.es.anl.gov/.
Page 482 of 850

(n) Ownership and Operating Costs

Method A results predict that the total cost of vehicle ownership and operation will change not 

just due to changes in vehicle price and fuel outlays, but also due to some other costs likely to 

vary with vehicle price. To estimate these costs, NHTSA has applied factors of 5.5 percent (of 

price) for taxes and fees, 15.3 percent for financing, 19.2 percent for insurance, 1.9 percent for 

relative value loss. The Method A analysis also estimates that average vehicle resale value will 

increase by 25 percent of any increase in new vehicle price.

(5) DOT CAFE Model Analysis of Impacts of Regulatory Alternatives for HD 

Pickups and Vans

(a) Industry Impacts

The agencies’ analysis fleet provides a starting point for estimating the extent to which 

manufacturers might add fuel-saving (and, therefore, CO2-avoiding) technologies under various 

regulatory alternatives, including the no-action alternative that defines a baseline against which 

to measure estimated impacts of new standards. The analysis fleet is a forward-looking 

projection of production of new HD pickups and vans, holding vehicle characteristics (e.g., 

technology content and fuel consumption levels) constant at model year 2014 levels, and 

adjusting production volumes based on recent DOE and commercially-available forecasts. This 

analysis fleet includes some significant changes relative to the market characterization that was 

used to develop the Phase 1 standards applicable starting in model year 2014; in particular, the 

analysis fleet includes some new HD vans (e.g., Ford’s Transit and Fiat/Chrysler’s Promaster) 

that are considerably more fuel-efficient than HD vans these manufacturers have previously 

produced for the U.S. market.

While the proposed standards are scheduled to begin in model year 2021, the 

requirements they define are likely to influence manufacturers’ planning decisions several years 

in advance. This is true in light-duty planning, but accentuated by the comparatively long 

redesign cycles and small number of models and platforms offered for sale in the 2b/3 market 

segment. Additionally, manufacturers will respond to the cost and efficacy of available fuel 

consumption improvements, the price of fuel, and the requirements of the Phase 1 standards that 

specify maximum allowable average fuel consumption and GHG levels for MY2014-MY2018 

HD pickups and vans (the final standard for MY2018 is held constant for model years 2019 and 

2020). The forward-looking nature of product plans that determine which vehicle models will be 

offered in the model years affected by the proposed standards lead to additional technology

application to vehicles in the analysis fleet that occurs in the years prior to the start of the 

proposed standards. From the industry perspective, this means that manufacturers will incur 

costs to comply with the proposed standards in the baseline and that the total cost of the 

proposed regulations will include some costs that occur prior to their start, and represent 

incremental changes over a world in which manufacturers will have already modified their 

vehicle offerings compared to today.
Page 483 of 850

Table VI-19 MY2021 Baseline Costs for Manufacturers in 2b/3 Market Segment in the Dynamic Baseline, or 

Alternative 1b

Manufacturer Average 

Technology Cost 

Total Cost 

Increase ($m)

Chrysler/Fiat 275 27

Daimler 18 0

Ford 258 78

General Motors 782 191

Nissan 282 3

Industry 442 300

As Table VI-19 shows, the industry as a whole is expected to add about $440 of new 

technology to each new vehicle model by 2021 under the no-action alternative defined by the 

Phase 1 standards. Reflecting differences in projected product offerings in the analysis fleet, 

some manufacturers (notably Daimler) are significantly less constrained by the Phase 1 standards 

than others and face lower cost increases as a result. General Motors (GM) shows the largest

increase in average vehicle cost, but results for GM’s closest competitors (Ford and 

Chrysler/Fiat) do not include the costs of their recent van redesigns, which are already present in 

the analysis fleet (discussed in greater detail below).

The above results reflect the assumption that manufacturers having achieved compliance 

with standards might act as if buyers are willing to pay for further fuel consumption 

improvements that “pay back” within 6 months (i.e., those improvements whose incremental 

costs are exceeded by savings on fuel within the first six months of ownership). It is also 

possible that manufacturers will choose not to migrate cost-effective technologies to the 2b/3 

market segment from similar vehicles in the light-duty market. To examine this possibility, all 

regulatory alternatives were also analyzed using the DOT CAFE model (Method A) with a 0-

month payback period in lieu of the 6-month payback period discussed above. (A sensitivity

analysis using Method A, discussed below, also explores longer payback periods, as well as the 

combined effect of payback period and fuel price on vehicle design decisions). Resultant 

technology costs in model year 2021 results for the no-action alternative, summarized in Table 

VI-20 below, are quite similar to those shown above for the 6-month payback period. Due to the 

similarity between the two baseline characterizations, results in the following discussion 

represent differences relative to only the 6-month payback baseline.
Page 484 of 850

Table VI-20 MY2021 Baseline Costs for HD Pickups and Vans in the Flat Baseline, or Alternative 1a

Manufacturer Average Technology 

Cost ($)

Total Cost Increase 

($m)

Chrysler/Fiat 268 27

Daimler 0 0

Ford 248 75

General Motors 767 188

Nissan 257 3

Industry 431 292

The results below represent the impacts of several regulatory alternatives, including those 

defined by the proposed standards, as incremental changes over the baseline, where the baseline 

is defined as the state of the world in the absence of the proposed regulatory action. Large-scale, 

macroeconomic conditions like fuel prices are constant across all alternatives, including the 

baseline, as are the fuel economy improvements under the no-action alternative defined by the 

Phase 1 MDHD rulemaking that covers model years 2014 – 2018 and is constant from model

year 2018 through 2020. In the baseline scenario, the Phase 1 standards are assumed to remain 

in place and at 2018 levels throughout the analysis (i.e. MY 2030). The only difference between 

the definitions of the alternatives is the stringency of the proposed standards starting in MY 2021 

and continuing through either MY 2025 or MY 2027, and all of the differences in outcomes 

across alternatives are attributable to differences in the standards. 

The standards vary in stringency across regulatory alternatives (1 – 5), but as discussed 

above, all of the standards are based on the curve developed in the Phase 1 standards that relate 

fuel economy and GHG emissions to a vehicle’s work factor. The alternatives considered here 

represent different rates of annual increase in the curve defined for model year 2018, growing 

from a 0 percent annual increase (Alternative 1, the baseline or “no-action” alternative) up to a 4

percent annual increase (Alternative 5). Table VI-21 shows a summary375 of outcomes by

alternative incremental to the baseline (Alternative 1b) for Model Year 2030376, with the 

exception of technology penetration rates, which are absolute. 

The technologies applied by the CAFE model have been grouped (in most cases) to give 

readers a general sense of which types of technology are applied more frequently than others, 

and are more likely to be offered in new class 2b/3 vehicles once manufacturers are fully 

compliant with the standards in the alternative. Model year 2030 was chosen to account for 

 

375 NHTSA generated hundreds of outputs related to economic and environmental impacts, each available 

technology, and the costs associated with the rule. A more comprehensive treatment of these outputs appears in 

Chapter 10 of the draft RIA.

376 The DOT CAFE model estimates that redesign schedules will “straddle” model year 2027, the latest year for 

which the agencies are proposing increases in the stringency of fuel consumption and GHG standards. Considering 

also that today’s analysis estimates some earning and application of “carried forward” compliance credits, the model 

was run extending the analysis through model year 2030. 
Page 485 of 850

technology application that occurs once the standards have stabilized, but manufacturers are still 

redesigning products to achieve compliance – generating technology costs and benefits in those 

model years. The summaries of technology penetration are also intended to reflect the 

relationship between technology application and cost increases across the alternatives. The table 

rows present the degree to which specific technologies will be present in new class 2b and class 

3 vehicles in 2030, and correspond to: Variable valve timing (VVT) and/or variable valve lift 

(VVL), cylinder deactivation, direct injection, engine turbocharging, 8-speed automatic 

transmissions, electric power-steering and accessory improvements, micro-hybridization (which 

reduces engine idle, but does not assist propulsion), full hybridization (integrated starter 

generator or strong hybrid that assists propulsion and recaptures braking energy), and 

aerodynamic improvements to the vehicle shape. In addition to the technologies in the following 

tables, there are some lower-complexity technologies that have high market penetration across 

all the alternatives and manufacturers; low rolling-resistance tires, low friction lubricants, and 

reduced engine friction, for example. 
Page 486 of 850

Table VI-21 Summary of HD Pickups and Vans Alternatives’ Impact on Industry versus the Dynamic 

Baseline, Alternative 1b

Alternative 2 3 4 5

Annual Stringency Increase 2.0%/y 2.5%/y 3.5%/y 4.0%/y

Stringency Increase Through MY 2025 2027 2025 2025

Total Stringency Increase 9.6% 16.2% 16.3% 18.5%

Average Fuel Economy (miles per gallon)

Required 19.04 20.57 20.57 21.14

Achieved 19.14 20.61 20.83 21.27

Average Fuel Consumption (gallons /100 mi.)

Required 5.25 4.86 4.86 4.73

Achieved 5.22 4.85 4.80 4.70

Average Greenhouse Gas Emissions (g/mi)

Required 495 458 458 446

Achieved 491 458 453 444

Technology Penetration (%)

VVT and/or VVL 46 46 46 46

Cylinder Deac. 29 21 21 21

Direct Injection 17 25 31 32

Turbocharging 55 63 63 63

8-Speed AT 67 96 96 97

EPS, Accessories 54 80 79 79

Stop Start 0 0 10 13

Hybridizationa0 8 35 51

Aero. Improvements 36 78 78 78

Mass Reduction (vs. No-Action)

CW (lb.) 239 243 325 313

CW (%) 3.7 3.7 5.0 4.8

Technology Cost (vs. No-Action)

Average ($) b578 1,348 1,655 2,080

Total ($m) c437 1,019 1,251 1,572

Payback period (m) c25 31 34 38

Notes:

a Includes mild hybrids (ISG) and strong HEVs.

b Values used in Methods A & B

c Values used in Method A, calculated using a 3% discount rate.

In general, the model projects that the standards would cause manufacturers to produce 

HD pickups and vans that are lighter, more aerodynamic, and more technologically complex 

across all the alternatives. As Table VI-21 shows, there is a difference between the relatively 

small increases in required fuel economy and average incremental technology cost between the 

alternatives, suggesting that the challenge of improving fuel consumption and CO2 emissions 

accelerates as stringency increases (i.e., that there may be a “knee” in the relationship between 
Page 487 of 850

technology cost and reductions in fuel consumption/GHG emissions). Despite the fact that the 

required average fuel consumption level changes by about 3 percent between Alternative 4 and 

Alternative 5, average technology cost increases by more than 25 percent. These differences 

help illustrate the clustered character of this market segment, where relatively small increases in 

fuel economy can lead to much larger cost increases if entire platforms must be changed in 

response to the standards.

The contrast between alternatives 3 and 4 is even more prominent, with an identical

required fuel economy improvement leading to price increases greater than 20 percent based on 

the more rapid rate of increase and shorter time span of Alternative 4, which achieves all of its 

increases by MY 2025 while Alternative 3 continues to increase at a slower rate until MY 2027. 

Despite these differences, the increase in average payback period when moving from Alternative 

3 to Alternative 4 to Alternative 5 is fairly constant at around an additional three months for each 

jump in stringency.

Manufacturers offer few models, typically only a pickup truck and/or a cargo van, and 

while there are a large number of variants of each model, the degree of component sharing across 

the variants can make diversified technology application either economically impractical or 

impossible. This forces manufacturers to apply some technologies more broadly in order to 

achieve compliance than they might do in other market segments (passenger cars, for example). 

This difference between broad and narrow application – where some technologies must be 

applied to entire platforms, while some can be applied to individual model variants – also 

explains why certain technology penetration rates decrease between alternatives of increasing 

stringency (cylinder deactivation or mass reductions in Table VI-21, for example). For those 

cases, narrowly applying a more advanced (and costly) technology can be a more cost effective 

path to compliance and lead to reductions in the amount of lower-complexity technology that is 

applied. 

One driver of the change in technology cost between Alternative 3 and Alternative 4 is 

the amount of hybridization projected to result from the implementation of the standards. While 

only about 5 percent full hybridization (defined as either integrated starter-generator or strong 

hybrid) is expected to be needed to comply with Alternative 3, the higher rate of increase and 

compressed schedule moving from Alternative 3 to Alternative 4 is enough to increase the 

percentage of the fleet adopting full hybridization by a factor of two. To the extent that 

manufacturers are concerned about introducing hybrid vehicles in the 2b and 3 market, it is 

worth noting that new vehicles subject to Alternative 3 achieve the same fuel economy as new 

vehicle subject to Alternative 4 by 2030, with less hybridization required to achieve the 

improvement.

The alternatives also lead to important differences in outcomes at the manufacturer level, 

both from the industry average and from each other. General Motors, Ford, and Chrysler (Fiat), 

are expected to have approximately 95 percent of the 2b/3 new vehicle market during the years 

that the proposed standards are being phased in. Due to their importance to this market and the 

similarities between their model offerings, these three manufacturers are discussed together and a 

summary of the way each is impacted by the standards appears below in Table VI-22, Table 

VI-23, and Table VI-24 for General Motors, Ford, and Chrysler/Fiat, respectively.
Page 488 of 850

Table VI-22 Summary of impacts on General Motors by 2030 in the HD Pickup and Van Market versus the 

Dynamic Baseline, Alternative 1b

Alternative 2 3 4 5

Annual 

Stringency

Increase

2.0%/y 2.5%/y 3.5%/y 4.0%/y

Stringency

Increase Through 

MY

2025 2027 2025 2025

Average Fuel Economy (miles per gallon)

Required 18.38 19.96 20 20.53

Achieved 18.43 19.95 20.24 20.51

Average Fuel Consumption (gallons /100 mi.)

Required 5.44 5.01 5 4.87

Achieved 5.42 5.01 4.94 4.87

Average Greenhouse Gas Emissions (g/mi)

Required 507 467 467 455

Achieved 505 468 461 455

Technology Penetration (%)

VVT and/or 

VVL

64 64 64 64

Cylinder Deac. 47 47 47 47

Direct Injection 18 18 36 36

Turbocharging 53 53 53 53

8-Speed AT 36 100 100 100

EPS, Accessories 100 100 100 100

Stop Start 0 0 2 0

Hybridization 0 19 79 100

Aero. 

Improvements

100 100 100 100

Mass Reduction (vs. No-Action)

CW (lb.) 325 161 158 164

CW (%) 5.3 2.6 2.6 2.7

Technology Cost (vs. No-Action)

Average ($) a785 1,706 2,244 2,736

Total ($m, 

undiscounted)

b

214 465 611 746

Notes:

a Values used in Methods A & B

b Values used in Method A, calculated at a 3% discount rate
Page 489 of 850

Table VI-23 Summary of Impacts on Ford by 2030 in the HD Pickup and Van Market versus the Dynamic 

Baseline, Alternative 1b

Alternative 2 3 4 5

Annual 

Stringency

Increase

2.0%/y 2.5%/y 3.5%/y 4.0%/y

Stringency

Increase Through 

MY

2025 2027 2025 2025

Average Fuel Economy (miles per gallon)

Required 19.42 20.96 20.92 21.51

Achieved 19.5 21.04 21.28 21.8

Average Fuel Consumption (gallons /100 mi.)

Required 5.15 4.77 4.78 4.65

Achieved 5.13 4.75 4.70 4.59

Average Greenhouse Gas Emissions (g/mi)

Required 485 449 450 438

Achieved 482 447 443 433

Technology Penetration (%)

VVT and/or 

VVL

34 34 34 34

Cylinder Deac. 18 0 0 0

Direct Injection 16 34 34 34

Turbocharging 51 69 69 69

8-Speed AT 100 100 100 100

EPS, Accessories 41 62 59 59

Stop Start 0 0 20 29

Hybridization 0 2 14 30

Aero. 

Improvements

0 59 59 59

Mass Reduction (vs. No-Action)

CW (lb.) 210 202 379 356

CW (%) 3.2 3 5.7 5.3

Technology Cost (vs. No-Action)

Average ($) a506 1,110 1,353 1,801

Total ($m, 

undiscounted)

b

170 372 454 604

Notes:
Page 490 of 850

a Values used in Methods A & B

b Values used in Method A, calculated at a 3% discount rate

Table VI-24 Summary of Impacts on Fiat/Chrysler by 2030 in the HD Pickup and Van Market versus the 

Dynamic Baseline, Alternative 1b

Alternative 2 3 4 5

Annual 

Stringency

Increase

2.0%/y 2.5%/y 3.5%/y 4.0%/y

Stringency

Increase Through 

MY

2025 2027 2025 2025

Average Fuel Economy (miles per gallon)

Required 18.73 20.08 20.12 20.70

Achieved 18.83 20.06 20.10 20.70

Average Fuel Consumption (gallons /100 mi.)

Required 5.34 4.98 4.97 4.83

Achieved 5.31 4.99 4.97 4.83

Average Greenhouse Gas Emissions (g/mi)

Required 515 480 479 466

Achieved 512 481 480 467

Technology Penetration (%)

VVT and/or 

VVL

40 40 40 40

Cylinder Deac. 23 23 23 23

Direct Injection 17 17 17 17

Turbocharging 74 74 74 74

8-Speed AT 65 88 88 88

EPS, Accessories 0 100 100 100

Stop-Start 0 0 0 0

Hybridization 0 3 3 10

Aero. 

Improvements

0 100 100 100

Mass Reduction (vs. No-Action)

CW (lb.) 196 649 648 617

CW (%) 2.8 9.1 9.1 8.7

Technology Cost (vs. No-Action)

Average ($) a434 1,469 1,486 1,700

Total ($m, 

undiscounted)

b

48 163 164 188

Notes:
Page 491 of 850

a Values used in Methods A & B

b Values used in Method A, calculated at a 3% discount rate

The fuel consumption and GHG standards require manufacturers to achieve an average 

level of compliance, represented by a sales-weighted average across the specific targets of all 

vehicles offered for sale in a given model year, such that each manufacturer will have a unique 

required consumption/emissions level determined by the composition of its fleet, as illustrated 

above. However, there are more interesting differences than the small differences in required 

fuel economy levels among manufacturers. In particular, the average incremental technology

cost increases with the stringency of the alternative for each manufacturer, but the size of the 

cost increase from one alternative to the next varies among them, with General Motors showing 

considerably larger increases in cost moving from Alternative 3 to Alternative 4, than from either 

Alternative 2 to Alternative 3 or Alternative 4 to Alternative 5. Ford is estimated to have more 

uniform cost increases from each alternative to the next, in increasing stringency, though still 

benefits from the reduced pace and longer period of increase associated with Alternative 3 

compared to Alternative 4. 

The simulation results show all three manufacturers facing cost increases when the 

stringency of the standards move from 2.5 percent annual increases over the period from MY 

2021 – 2027 to 3.5 percent annual increases from MY 2021 - 2025, but General Motors has the 

largest at 75 percent more than the industry average price increase for Alternative 4. GM also 

faces higher cost increases in Alternative 2 about 50 percent more than either Ford or 

Fiat/Chrysler. And for the most stringent alternative considered, the agencies estimate that 

General Motors would face average cost increases of more than $2,700, in addition to the more 

than $700 increase in the baseline – approaching nearly $3,500 per vehicle over today’s prices.

Technology choices also differ by manufacturer, and some of those decisions are directly

responsible for the largest cost discrepancies. For example, GM is estimated to engage in the 

least amount of mass reduction among the Big 3 after Phase 1, and much less than Chrysler/Fiat, 

but reduces average vehicle mass by over 300 pounds in the baseline – suggesting that some of 

GM’s easiest Phase 1 compliance opportunities can be found in lightweighting technologies. 

Similarly, Chrysler/Fiat is projected to apply less hybridization than the others, and much less 

than General Motors, which is simulated to have full hybrids (either integrated starter generator 

or complete hybrid system) on all of its fleet by 2030, nearly 20 percent of which will be strong 

hybrids, in Alternative 4 and the strong hybrid share decreases to about 18 percent in Alternative 

5, as some lower level technologies are applied more broadly. Because the analysis applies the 

same technology inputs and the same logic for selecting among available opportunities to apply

technology, the unique situation of each manufacturer determined which technology path is 

projected as the most cost-effective. 

In order to understand the differences in incremental technology costs and fuel economy 

achievement across manufacturers in this market segment, it is important to understand the 

differences in their starting position relative to the proposed standards. One important factor, 

made more obvious in the following figures, is the difference between the fuel economy and 

performance of the recently redesigned vans offered by Fiat/Chrysler and Ford (the Promaster 

and Transit, respectively), and the more traditionally-styled vans that continue to be offered by 

General Motors (the Express/Savannah). In MY 2014, Ford began the phase-out of the 
Page 492 of 850

Econoline van platform, moving those volumes to the Euro-style Transit vans (discussed in more 

detail in Section I. D.2). The Transit platform represents a significant improvement over the 

existing Econoline platform from the perspective of fuel economy, and for the purpose of 

complying with the standards, the relationship between the Transit’s work factor and fuel 

economy is a more favorable one than the Econoline vans it replaces. Since the redesign of van 

offerings from both Chrysler/Fiat and Ford occur in (or prior to) the 2014 model year, the costs, 

fuel consumption improvements, and reductions of vehicle mass associated with those redesigns 

are included in the analysis fleet, meaning they are not carried as part of the compliance 

modeling exercise. By contrast, General Motors is simulated to redesign their van offerings after 

2014, such that there is a greater potential for these vehicles to incur additional costs attributable 

to new standards, unlike the costs associated with the recent redesigns of their competitors. The 

inclusion of these new Ford and Chrysler/Fiat products in the analysis fleet is the primary driver 

of the cost discrepancy between GM and its competitors in both the baseline and Alternative 2, 

when Ford and Chrysler/Fiat have to apply considerably less technology to achieve compliance. 

The remaining 5 percent of the 2b/3 market is attributed to two manufacturers, Daimler 

and Nissan, which, unlike the other manufacturers in this market segment, only produce vans. 

The vans offered by both manufacturers currently utilize two engines and two transmissions, 

although both Nissan engines are gasoline engines and both Daimler engines are diesels. Despite 

the logical grouping, these two manufacturers are impacted much differently by the proposed 

standards. For the least stringent alternative considered, Daimler adds no technology and incurs 

no incremental cost in order to comply with the standards. At stringency increases greater than 

or equal to 3.5 percent per year, Daimler only really improves some of their transmissions and 

improves the electrical accessories of its Sprinter vans. By contrast, Nissan’s starting position is 

much weaker and their compliance costs closer to the industry average in Table VI-21. This 

difference could increase if the analysis fleet supporting the final rule includes forthcoming 

Nissan HD pickups.
Page 493 of 850

Table VI-25 Summary of Impacts on Daimler by 2030 in the HD Pickup and Van Market versus the 

Dynamic Baseline, Alternative 1b

Alternative 2 3 4 5

Annual 

Stringency

Increase

2.0%/y 2.5%/y 3.5%/y 4.0%/y

Stringency

Increase Through 

MY

2025 2027 2025 2025

Average Fuel Economy (miles per gallon)

Required 23.36 25.19 25.25 25.91

Achieved 25.23 25.79 25.79 26.53

Average Fuel Consumption (gallons /100 mi.)

Required 4.28 3.97 3.96 3.86

Achieved 3.96 3.88 3.88 3.77

Average Greenhouse Gas Emissions (g/mi)

Required 436 404 404 393

Achieved 404 395 395 384

Technology Penetration (%)

VVT and/or VVL 0 0 0 0

Cylinder Deac. 0 0 0 0

Direct Injection 0 0 0 0

Turbocharging 44 44 44 44

8-Speed AT 0 44 44 100

EPS, Accessories 0 0 0 0

Stop-Start 0 0 0 0

Hybridization 0 0 0 0

Aero. 

Improvements

0 0 0 0

Mass Reduction (vs. No-Action)

CW (lb.) 0 0 0 0

CW (%) 0 0 0 0

Technology Cost (vs. No-Action)

Average ($) a0 165 165 374

Total ($m, 

undiscounted)

b

0 4 4 9

Notes:

a Values used in Methods A & B

b Values used in Method A, calculated at a 3% discount rate
Page 494 of 850

Table VI-26 Summary of Impacts on Nissan by 2030 in the HD Pickup and Van Market versus the Dynamic 

Baseline, Alternative 1b

Alternative 2 3 4 5

Annual Stringency

Increase

2.0%/y 2.5%/y 3.5%/y 4.0%/y

Stringency Increase 

Through MY

2025 2027 2025 2025

Average Fuel Economy (miles per gallon)

Required 19.64 21.19 20.92 21.46

Achieved 19.84 21.17 21.19 21.51

Average Fuel Consumption (gallons /100 mi.)

Required 5.09 44.72 4.78 4.66

Achieved 5.04 4.72 4.72 4.65

Average Greenhouse Gas Emissions (g/mi)

Required 452 419 425 414

Achieved 448 419 419 413

Technology Penetration (%)

VVT and/or VVL 100 100 100 100

Cylinder Deac. 49 49 49 49

Direct Injection 51 51 51 100

Turbocharging 51 51 51 50

8-Speed AT 0 51 51 51

EPS, Accessories 0 100 100 100

Stop-Start 0 0 0 0

Hybridization 0 0 0 28

Aero. 

Improvements

0 100 100 100

Mass Reduction (vs. No-Action)

CW (lb.) 0 0 307 303

CW (%) 0 0 5 4.9

Technology Cost (vs. No-Action)

Average ($) a378 1,150 1,347 1,935

Total ($m, 

undiscounted)

b

5 15.1 17.7 25.4

Notes:

a Values used in Methods A & B

b Values used in Method A, calculated at a 3% discount rate
Page 495 of 850

As Table VI-25 and Table VI-26 show, Nissan applies more technology than Daimler in 

the less stringent alternatives and significantly more technology with increasing stringency. The 

Euro-style Sprinter vans that comprise all of Daimler’s model offerings in this segment put 

Daimler in a favorable position. However, those vans are already advanced – containing 

downsized diesel engines and advanced aerodynamic profiles. Much like the Ford Transit vans, 

the recent improvements to the Sprinter vans occurred outside the scope of the compliance 

modeling so the costs of the improvements are not captured in the analysis.

Although Daimler’s required fuel economy level is much higher than Nissan’s (in miles 

per gallon), Nissan starts from a much weaker position than Daimler and must incorporate 

additional engine, transmission, platform-level technologies (e.g. mass reduction and 

aerodynamic improvements) in order to achieve compliance. In fact, more than 25 percent of 

Nissan’s van offerings are projected to contain integrated starter generators by 2030 in 

Alternative 5. 

While the agencies do not allow sales volumes for any manufacturer (or model) to vary

across regulatory alternatives in the analysis, it is conceivable that under the most stringent 

alternatives individual manufacturers could lose market share to their competitors if the prices of 

their new vehicles rise more than the industry average without compensating fuel savings and/or 

changes to other features. 

(b) Estimated Owner/operator Impacts with Respect to HD Pickups and Vans Using 

Method A

The owner/operator impacts of the proposed rules are more straightforward. Table VI-27

shows the impact on the average owner/operator who buys a new class 2b or 3 vehicle in model 

year 2030 using the worst case assumption that manufacturers pass through the entire cost of 

technology to the purchaser. (All dollar values are discounted at a rate of 7 percent per year 

from the time of purchase, except the average price increase, which occurs at the time of 

purchase). The additional costs associated with increases in taxes, registration fees, and 

financing costs are also captured in the table.
Page 496 of 850

Table VI-27 Summary of Individual Owner/operator Impacts in MY 2030 in the HD Pickup and Van 

Market Segment using Method A and versus the Dynamic Baseline, Alternative 1b a

Alternative 2 3 4 5

Annual 

Stringency

Increase Increases

2.0%/y 2.5%/y 3.5%/y 4.0%/y

Stringency

Increase Through 

MY

2025 2027 2025 2025

Value of Lifetime Fuel Savings (discounted 2012 dollars)

Pretax 2,068 3,924 4,180 4,676

Tax 210 409 438 491

Total 2,278 4,334 4,618 5,168

Economic Benefits (discounted 2012 dollars)

Mobility Benefit 244 437 472 525

Avoided 

Refueling Time

86 164 172 193

New Vehicle Purchase (vs. No-Action Alternative)

Avg. Price 

Increase ($)

578 1,348 1,655 2,080

Avg. Payback 

(years)

2.5 3 3.4 3.9

Additional costs 

($)

120 280 344 432

Net Lifetime Owner/operator Benefits (discounted $)

Total Net Benefits 1,910 3,307 3,263 3,374

Notes:

*All dollar values are discounted at a rate of 7 percent per year from the time of purchase, 

except the average price increase, which occurs at the time of purchase).

a For an explanation of analytical Methods A and B, please see Section I.D; for an explanation 

of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

As expected, an owner/operator’s lifetime fuel savings increase monotonically across the 

alternatives. The mobility benefit in Table VI-27 refers to the value of additional miles that an 

individual owner/operator travels as a result of reduced per-mile travel costs. The additional 

miles result in additional fuel consumption and represent foregone fuel savings, but are valued 

by owner/operators at the cost of the additional fuel plus the owner/operator surplus (a measure 

of the increase in welfare that owner/operators achieve by having more mobility). The refueling 

benefit measures the value of time saved through reduced refueling events, the result of 

improved fuel economy and range in vehicles that have been modified in response to the 

standards. 
Page 497 of 850

There are some limitations to using payback period as a measure, as it accounts for fuel 

expenditures and incremental costs associated with taxes, registration fees and financing, and 

increased maintenance costs, but not the cost of potential repairs or replacements, which may or 

may not be more expensive with more advanced technology. 

Overall, the average owner/operator is likely to see discounted lifetime benefits that are 

multiples of the price increases faced when purchasing the new vehicle in MY 2030 (or the few 

model years preceding 2030). In particular, the net present value of future benefits at the time of 

purchase are estimated to be 3.5, 3.0, 2.2, and 1.8 times the price increase of the average new 

MY2030 vehicle for Alternatives 2 – 5, respectively. As Table VI-27 illustrates, the preferred 

alternative has the highest ratio of discounted future owner/operator benefits to owner/operator

costs.

(c) Estimated Social and Environmental Impacts for HD Pickups and Vans

Social benefits increase with the increasing stringency of the alternatives. As in the 

owner/operator analysis, the net benefits continue to increase with increasing stringency –

suggesting that benefits are still increasing faster than costs for even the most stringent 

alternative. 
Page 498 of 850

Table VI-28 Summary of Total Social Costs and Benefits Through MY2029 in the HD Pickup and Van 

Market Segment using Method A and versus the Dynamic Baseline, Alternative 1b a

Alternative 2 3 4 5

Annual Stringency

Increase

2.0% 2.5% 3.5% 4.0%

Stringency Increase 

Through MY

2025 2027 2025 2025

Fuel Purchases ($billion)

Pretax Savings 9.6 15.9 19.1 22.2

Fuel Externalities ($billion)

Energy Security 0.5 0.9 1.1 1.3

CO2 emissionsb1.9 3.2 3.8 4.4

VMT-Related Externalities ($billion)

Driving Surplus 1.1 1.8 2.1 2.4

Refueling Surplus 0.4 0.7 0.8 0.9

Congestion -0.2 -0.4 -0.4 -0.5

Accidents -0.1 -0.2 -0.2 -0.3

Noise 0 0 0 0

Fatalities 0.1 -0.2 -0.2 -0.5

Criteria Emissions 0.6 1.1 1.3 1.6

Technology Costs vs. No-Action ($billion)

Incremental Cost 2.5 5.0 7.2 9.7

Additional Costs 0.5 1.0 1.5 2.0

Benefit Cost Summary ($billion)

Total Social Cost 3.3 6.8 9.5 13.0

Total Social Benefit 13.9 22.7 27.4 31.7

Net Social Benefit 10.6 15.9 17.9 18.7

Notes:

*All dollar values are discounted at a rate of 3 percent per year from the time of 

purchase. 

a

For an explanation of analytical Methods A and B, please see Section I.D; for an 

explanation of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see 

Section X.A.1.

b

Using the 3% average social cost of CO2 value. There are four distinct social cost of 

CO2 values presented in the Technical Support Document: Social Cost of Carbon for 

Regulatory Impact Analysis under Executive Order 12866 (2010 and 2013). The CO2

emissions presented here would be valued lower with one of those other three values 

and higher at the other two values.

Table VI-28 provides a summary of benefits and costs, cumulative from MY2015 –

MY2029 (although the early years of the series typically have no incremental costs and benefits 

over the baseline), for each alternative. In the social perspective, fuel savings are considered net 

of fuel taxes, which are a transfer from purchasers of fuel to society at large. The energy security

component represents the risk premium associated with exposure to oil price spikes and the 
Page 499 of 850

economic consequences of adapting to them. This externality is monetized on a per-gallon basis, 

just as the social cost of carbon is used in this analysis. Just as the previous two externalities are 

caused by fuel consumption, others are caused by travel itself. The additional VMT resulting 

from the increase in travel demand that occurs when the price of driving decreases (i.e. the 

rebound effect), not only leads to increased mobility (which is a benefit to drivers), but also to 

increases in congestion, noise, accidents, and per-mile emissions of criteria pollutants like carbon 

monoxide and diesel particulates. Although increases in VMT lead to increases in tailpipe 

emissions of criteria pollutants, the proposed regulations decrease overall consumption enough 

that the emissions reductions associated with the remainder of the fuel cycle (extraction, refining, 

transportation and distribution) are large enough to create a net reduction in the emissions of 

criteria pollutants (shown below in Table VI-29 and VI-30).377 A full presentation of the costs 

and benefits, and the considerations that have gone into each cost and benefit category—such as 

how energy security premiums were developed, how the social costs of carbon and co-pollutant 

benefits were developed, etc.—is presented in Section IX of this preamble and in Chapters 7 and 

8 of the draft RIA for each regulated segment (engines, HD pickups and vans, vocational 

vehicles, tractors and trailers).

Another side effect of increased VMT is the likely increase in crashes, which is a 

function of the total vehicle travel in each year. Although additional crashes could involve 

additional fatalities, we estimate that this potential could be partially offset by the application of 

mass reduction to HD pickup trucks and vans, which could make fatalities less likely in some 

crashes involving these vehicles. As Table VI-28 illustrates, the social cost associated with 

traffic fatalities is the result of an additional -10 (Alternative 2 leads to a reduction in fatalities 

over the baseline, due to the application of mass reduction technologies), 35, 36, and 66 fatalities 

for Alternatives 2-5, respectively. The baseline contains nearly 25,000 fatalities involving 2b/3 

vehicles over the same period. The incremental fatalities associated with Alternative 2-5 are -

0.4, 0.1, 0.1, and 0.3 percent relative to the MYs 2015-2029 baseline, respectively. 

The CAFE model was used to estimate the emissions impacts of the various alternatives 

that are the result of lower fuel consumption, but increased vehicle miles traveled for vehicle 

produced in model years subject to the standards in the alternatives. Criteria pollutants are 

largely the result of vehicle use, and accrue on a per-mile-of-travel basis, but the alternatives still 

generally lead to emissions reductions. Although vehicle use increases under each of the 

alternatives, upstream emissions associated with fuel refining, transportation and distribution are 

reduced for each gallon of fuel saved and that savings is larger than the incremental increase in 

emissions associated with increased travel. The net of the two factors is a savings of criteria (and 

other) pollutant emissions.

 

377 For a more detailed discussion of the results from the CAFE Model on the proposed heavy duty pickups and vans 

regulation’s impact on emissions of CO2 and criteria pollutants, see NHTSA’s accompanying Draft Environmental 

Impact Statement.
Page 500 of 850

Table VI-29 Summary of Environmental Impacts Through MY2029 in the HD Pickup and Van Market 

Segment, using Method A and versus the Dynamic Baseline, Alternative 1b a

Alternative 2 3 4 5

Annual Stringency

Increase

2.0% 2.5% 3.5% 4.0%

Stringency Increase 

Through MY

2025 2027 2025 2025

Greenhouse Gas Emissions vs. No-Action Alternative

CO2 (MMT) 54 91 110 127

CH4 and N2O (tons) 65,600 111,400 133,700 155,300

Other Emissions vs. No-Action Alternative (tons)

CO 10,400 20,700 25,800 30,400

VOC and NOX 23,800 43,600 53,500 62,200

PM 1,470 2,550 3,090 3,590

SO2 11,400 19,900 24,100 28,000

Air Toxics 44 47 49 55

Diesel PM10 2,470 4,350 5,300 6,160

Other Emissions vs. No-Action Alternative (% reduction)

CO 0.1 0.3 0.4 0.4

VOC and NOX 1.1 2.1 2.6 3.0

PM 1.7 3.0 3.6 4.2

SO2 2.9 5.1 6.2 7.2

Air Toxics 0.1 0.1 0.1 0.2

Diesel PM10 2.7 4.8 5.9 6.8

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

In addition to comparing environmental impacts of the alternatives against a dynamic 

baseline that shows some improvement over time, compared to today’s fleet, even in the absence 

of the alternatives, the environmental impacts from the Method A analysis were compared 

against a flat baseline. This other comparison is summarized below, but both comparisons are 

discussed in greater detail in the Draft EIS.
Page 501 of 850

Table VI-30 Summary of Environmental Impacts Through MY2029 in the HD Pickup and Van Market 

Segment, using Method A and versus the Flat Baseline, Alternative 1a a

Alternative 2 3 4 5

Annual Stringency

Increase

2.0% 2.5% 3.5% 4.0%

Stringency Increase 

Through MY

2025 2027 2025 2025

Greenhouse Gas Emissions vs. No-Action Alternative

CO2 (MMT) 66 105 127 142

CH4 and N2O (tons) 79,700 127,400 154,800 172,800

Other Emissions vs. No-Action Alternative (tons)

CO 11,630 22,160 28,030 32,370

VOC and NOX 28,280 48,770 60,180 68,050

PM 1,780 2,900 3,550 3,980

SO2 13,780 22,580 27,660 31,020

Air Toxics 60 65 72 73

Diesel PM10 2,980 4,930 6,060 6,810

Other Emissions vs. No-Action Alternative (% reduction)

CO 0.2 0.3 0.4 0.4

VOC and NOX 1.4 2.3 2.9 3.3

PM 2.1 3.4 4.2 4.7

SO2 3.5 5.7 7.0 7.9

Air Toxics 0.2 0.2 0.2 0.2

Diesel PM10 3.3 5.4 6.7 7.5

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less 

dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

(6) Sensitivity Analysis Evaluating Different Inputs to the DOT CAFE Model

This section describes some of the principal sensitivity results, obtained by running the 

various scenarios describing the policy alternatives with alternative inputs. OMB Circular A-4 

indicates that “it is usually necessary to provide a sensitivity analysis to reveal whether, and to 

what extent, the results of the analysis are sensitive to plausible changes in the main assumptions 

and numeric inputs.”378 Considering this guidance, a number of sensitivity analyses were 

performed using analysis Method A to examine important assumptions and inputs, including the 

following, all of which are discussed in greater detail in the accompanying RIA:

1. Payback Period: In addition to the 0 and 6 month payback periods discussed above, also 

evaluated cases involving payback periods of 12, 18, and 24 months.

 

378 Available at http://www.whitehouse.gov/omb/circulars_a004_a-4/.
Page 502 of 850

2. Fuel Prices: Evaluated cases involving fuel prices from the AEO 2014 low and high oil 

price scenarios. (See AEO-Low and AEO-High in the tables.)

3. Fuel Prices and Payback Period: Evaluated one side case involving a 0 month payback 

period combined with fuel prices from the AEO 2014 low oil price scenario, and one side 

case with a 24 month payback period combined with fuel prices from the AEO 2014 high 

oil price scenario.

4. Benefits to Vehicle Buyers: The main Method A analysis assumes there is no loss in 

value to owner/operators resulting from vehicles that have an increase in price and higher 

fuel economy. NHTSA performed this sensitivity analysis assuming that there is a 25, or 

50 percent loss in value to owner/operators – equivalent to the assumption that 

owner/operators will only value the calculated benefits they will achieve at 75, or 50 

percent, respectively, of the main analysis estimates. (These are labeled as 

75pctOwner/operatorBenefit and 50pctOwner/operatorBenefit.)

5. Value of Avoided GHG Emissions: Evaluated side cases involving lower and higher 

valuation of avoided CO2 emissions, expressed as the social cost of carbon (SCC). 

6. Rebound Effect: Evaluated side cases involving rebound effect values of 5 percent, 15

percent, and 20 percent. (These are labeled as 05PctReboundEffect, 15PctReboundEffect 

and 20PctReboundEffect).

7. RPE-based Markup: Evaluated a side case using a retail price equivalent (RPE) markup 

factor of 1.5 for non-electrification technologies, which is consistent with the NAS 

estimation for technologies manufactured by suppliers, and a RPE markup factor of 1.33 

for electrification technologies (mild and strong HEV).

8. ICM-based Post-Warranty Repair Costs: NHTSA evaluated a side case that scaled the 

frequency of repair by vehicle survival rates, assumes that per-vehicle repair costs during 

the post-warranty period are the same as in the in-warranty period, and that repair costs 

are proportional to incremental direct costs (therefore vehicles with additional 

components will have increased repair costs).

9. Mass-Safety Effect: Evaluated side cases with the mass-safety impact coefficient at the 

values defining the 5th and 95th percent points of the confidence interval estimated in the 

underlying statistical analysis. (These are labeled MassFatalityCoeff05pct and 

MassFatalityCoeff95pct.)

10. Strong HEVs: Evaluated a side case in which strong HEVs were excluded from the set of 

technology estimated to be available for HD pickups and vans through model year 2030.

As in Section VI.Error! Reference source not found., this “no SHEV” case allowed 

turbocharging and downsizing on all GM vans to provide a lower-cost path for 

compliance.

11. Diesel Downsizing: Evaluated a side case in which downsizing of diesel engines was 

estimated to be more widely available to HD pickups and vans.

12. Technology Effectiveness: Evaluated side cases involving inputs reflecting lower and 

higher impacts of technologies on fuel consumption.

13. Technology Direct Costs: Evaluated side cases involving inputs reflecting lower and 

higher direct incremental costs for fuel-saving technologies.

14. Fleet Mix: Evaluated a side case in which the shares of individual vehicle models and 

configurations were kept constant at estimated current levels.
Page 503 of 850

Table VI-31Table VI-31 below, summarizes key metrics for each of the cases included in 

the sensitivity analysis using Method A for the proposed alternative. The table reflects the 

percent change in the metrics (columns) relative to the main analysis, due to the particular 

sensitivity case (rows) for the proposed alternative 3. For each sensitivity run, the change in the 

metric can we described as the difference between the baseline and the preferred alternative for 

the sensitivity case, minus the difference between the preferred alternative and the baseline in the 

main analysis, divided by the difference between the preferred alternative and the baseline in the 

main analysis. Or, 

  =

∆   − ∆  

∆  

∙ 100

Each metric represents the sum of the impacts of the preferred alternative over the model 

years 2018-2029, and the percent changes in the table represent percent changes to those sums. 

More detailed results for all alternatives are available in the accompanying RIA Chapter 10.
Page 504 of 850

Table VI-31 Sensitivity Analysis Results from CAFE Model in the HD Pickup and Van Market Segment 

using Method A and versus the Dynamic Baseline, Alternative 1b (2.5 % growth in stringency: Cells are 

percent change from base case) a

Sensitivity Case Fuel 

Savings

(gallons)

CO2 

savings

(MMT)

Fuel Savings

($)

Social

Costs

Social 

Benefits

Social 

Net 

Benefits

0 Month Payback 14.0% 14.5% 15.1% 5.6% 15.1% 18.2%

12 Month Payback -4.8% -4.7% -4.5% -2.5% -4.7% -5.4%

18 Month Payback -29.2% -28.1% -26.5% -14.1% -26.8% -31.1%

24 Month Payback -42.9% -42.4% -41.9% -23.2% -42.1% -48.4%

AEO-Low 3.3% 3.5% -27.9% -10.8% -22.2% -26.1%

AEO-High -7.0% -7.2% 23.3% 1.4% 19.5% 25.6%

AEO-Low, 0 Month 

Payback

18.6% 19.3% -16.5% -3.4% -10.1% -12.3%

AEO-High, 24 

Month Payback

-63.8% -64.6% -54.4% -49.9% -55.7% -57.7%

50pct 

Owner/operator

Benefit

0.0% 0.0% -50.0% 0.0% -34.6% -46.2%

75pct 

Owner/operator

Benefit

0.0% 0.0% -25.0% 0.0% -17.3% -23.1%

Low SCC 0.0% 0.0% 0.0% 0.0% -10.6% -14.1%

Low SCC, 0 Month 

Payback

14.0% 14.5% 15.1% 5.6% 2.9% 2.0%

High SCC 0.0% 0.0% 0.0% 0.0% 7.8% 10.4%

High SCC, 0 Month 

Payback

14.0% 14.5% 15.1% 5.6% 24.0% 30.1%

Very High SCC 0.0% 0.0% 0.0% 0.0% 28.7% 38.4%

Very High SCC, 0 

Month Payback

14.0% 14.5% 15.1% 5.6% 48.0% 62.2%

05 Pct Rebound 

Effect

4.6% 4.6% 4.6% -12.9% 0.4% 4.8%

15 Pct Rebound 

Effect

-4.6% -4.6% -4.6% 12.9% -0.4% -4.8%

20 Pct Rebound 

Effect

-9.1% -9.2% -9.2% 25.7% -0.8% -9.7%

RPE-Based Markup -3.2% -1.5% 0.3% 31.4% -0.1% -10.6%

Mass Fatality Coeff

05pct

0.0% 0.0% 0.0% -23.6% 0.0% 7.9%

Mass Fatality Coeff

95pct

0.0% 0.0% 0.0% 23.9% 0.0% -8.0%

NoSHEVs -6.7% -5.8% -5.0% 2.3% -5.1% -7.6%

NoSHEVs, 0 Month 

Payback

8.2% 9.8% 11.5% -1.2% 11.3% 15.4%

Lower Effectiveness -7.8% -7.8% -8.1% 39.5% -8.0% -23.9%

Higher Effectiveness -10.6% -10.3% -10.0% -23.3% -10.2% -5.8%

Lower Direct Costs 0.9% 2.7% 4.8% 18.4% 4.3% -0.4%

Higher Direct Costs -4.1% -3.8% -3.5% 75.3% -3.8% -30.3%
Page 505 of 850

Wider Diesel 

Downsizing

-1.5% -1.0% -0.6% -10.3% -0.8% 2.4%

07 Pct Discount Rate 0.0% 0.0% -100.0% -41.7% -100.0% -119.5%

07 Pct DR, 0 Month 

Payback

14.0% 14.5% -37.9% -30.7% -30.7% -30.7%

Allow Gas To Diesel 15.5% 5.3% -100.0% 16.8% -100.0% -139.1%

Allow Gas To 

Diesel, 0 Month 

Payback

32.1% 22.6% 14.5% 46.8% 17.0% 7.0%

flat mix after 2016 1.1% 0.9% 0.7% 2.6% 0.8% 0.2%

Note

a For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

For some of the cases for which results are presented above, the sensitivity of results to 

changes in inputs is simple, direct, and easily observed. For example, changes to valuation of 

avoided GHG emissions impact only this portion of the estimated economic benefits; 

manufacturers’ responses and corresponding costs are not impacted. Similarly, a higher discount 

rate does not affect physical quantities saved (gallons of fuel and metric tons of CO2 in the 

table), but reduces the value of the costs and benefits attributable to the proposed standards in an 

intuitive way. Some other cases warrant closer consideration:

First, cases involving alternatives to the reference six-month payback period involve 

different degrees of fuel consumption improvement, and these differences are greatest in the noaction alternative defining the baseline. Because all estimated impacts of the proposed standards 

are shown as incremental values relative to this baseline, longer payback periods correspond to 

smaller estimates of incremental impacts, as fuel economy increasingly improves in the absence 

of the rule and manufacturers are compelled to add less technology in order to comply with the 

standards.

Second, cases involving different fuel prices similarly involve different degrees of fuel 

economy improvement in the absence of the standard, as more, or less, improvement occurs as a 

result of more, or fewer, technologies appearing cost effective to owner/operators. Lower fuel 

prices correspond to increases in fuel savings on a volumetric basis, as the standard is 

responsible for a greater amount of the fuel economy improvement, but the value of fuel savings 

decreases because each gallon saved is worth less when fuel prices are low. Higher fuel prices 

correspond to reductions in the volumetric fuel savings attributable to the proposed standards, 

but lead to increases in the value of fuel saved because each gallon saved is worth more when 

fuel prices are high.

Third, because the payback period and fuel price inputs work in opposing directions, the 

relative magnitude of each is important to consider for the combined sensitivity cases. While the 

low price and 0-month payback case leads to significant volumetric savings compared to the 

main analysis, the low fuel price is still sufficient to produce a negative change in net benefits. 

Similarly, the high price and 24-month payback case results in large reductions to volumetric 

savings that can be attributed to the proposed standards, but the presence of high fuel prices is 

not sufficient to lead to increases in either the dollar value of fuel savings or net social benefits.
Page 506 of 850

Fourth, the cases involving different inputs defining the availability of some technologies 

do not impact equally the estimated impacts across all manufacturers. Section C.8 above 

provides a discussion of a sensitivity analysis that excludes strong hybrids and includes the use 

of downsized turbocharged engines in vans currently equipped with large V-8 engines. The 

modeling results for this analysis are provided in Section C.8 and in the table above. The no 

strong hybrid analysis shows that GM could comply with the proposed preferred Alternative 3 

without strong hybrids based on the use of turbo downsizing on all of their HD gasoline vans. 

Alternatively, when the analysis is modified to allow for wider application of diesel engines, 

strong HEV application for GM drops slightly (from 19 percent to 17 percent) in MY2030, 

average per-vehicle costs drop slightly (by about $50), but MY2030 additional penetration rates 

of diesel engines increase by about 10 percent. Manufacturer-specific model results 

accompanying today’s rules show the extent to which individual manufacturers’ potential 

responses to the standards vary with these alternative assumptions regarding the availability and 

applicability of fuel-saving technologies. However, across all of these sensitivity cases, the 

model projects that social costs increase (as a result of increases in technology costs) when 

manufacturers choose to comply with the proposed regulations without the use of strong hybrids.

Fifth, the cases that vary the effectiveness and direct cost of available technologies 

produce nuanced results in the context of even the 0-month payback case. In the case of 

effectiveness changes, both sensitivity cases result in reductions to the volumetric fuel savings 

attributable to the proposal; lower effectiveness because the technologies applied in response to 

the standards save less fuel, and higher effectiveness because more of the increase in fuel 

economy occurs in the baseline. However, for both cases, social costs (a strong proxy for 

technology costs) move in the intuitive direction. 

The cases that vary direct costs show volumetric fuel savings increasing under lower 

direct technology costs despite additional fuel economy improvements in the baseline, as more 

aggressive technology becomes cost effective. Higher direct costs lead to decreases in 

volumetric fuel savings, as more of the fuel economy improvement can be attributed to the rule. 

In both cases, social costs (as a result of technology costs) move in the intuitive direction.

If, instead of using the values in the main analysis, each sensitivity case were itself the 

main analysis, the costs and benefits attributable to the proposed rule would be as they appear in 

Table VI-32, below.

Table VI-32 Costs and Benefits of Proposed Standards for HD Pickups and Vans Under Alternative 

Assumptions
Page 507 of 850

Sensitivity Case Fuel Savings 

(billion 

gallons)

CO2 

Reduction 

(MMT)

Fuel 

Savings 

($billion)

Social 

Costs 

($billion)

Social 

Benefits 

($billion)

Net Social 

Benefits 

($billion)

6 Month Payback (main) 7.8 94.1 15.9 5.5 23.5 18

0 Month Payback 8.9 107.7 18.3 5.8 27.0 21.3

12 Month Payback 7.4 87.2 151.8 56.2 218.8 162.7

18 Month Payback 5.5 65.8 116.9 49.5 168.0 118.5

24 Month Payback 4.5 52.7 92.4 44.2 132.9 88.6

AEO-Low 8.1 94.7 114.7 51.4 178.5 127.1

AEO-High 7.3 84.9 196.0 58.4 274.3 215.9

AEO-Low, 0 Month 

Payback

9.3 109.1 132.8 55.6 206.4 150.7

AEO-High, 24 Month 

Payback

2.8 32.4 72.5 28.9 101.7 72.8

50pct Owner/operator 

Benefit

7.8 91.5 79.5 57.6 150.0 92.4

75pct Owner/operator 

Benefit

7.8 91.5 119.3 57.6 189.8 132.2

Low SCC 7.8 91.5 159.0 57.6 205.2 147.6

Low SCC, 0 Month 

Payback

8.9 104.7 183.0 60.8 236.2 175.4

High SCC 7.8 91.5 159.0 57.6 247.4 189.8

High SCC, 0 Month 

Payback

8.9 104.7 183.0 60.8 284.5 223.7

Very High SCC 7.8 91.5 159.0 57.6 295.5 237.9

Very High SCC, 0 Month 

Payback

8.9 104.7 183.0 60.8 339.6 278.8

05 Pct Rebound Effect 8.2 95.7 166.3 50.2 230.4 180.3

15 Pct Rebound Effect 7.5 87.2 151.7 65.0 228.6 163.6

20 Pct Rebound Effect 7.1 83.0 144.4 72.4 227.7 155.3

RPE-Based Markup 7.6 90.1 159.5 75.7 229.4 153.7

Mass Fatality Coeff 05pct 7.8 91.5 159.0 44.0 229.5 185.5

Mass Fatality Coeff 95pct 7.8 91.5 159.0 71.4 229.5 158.1

NoSHEVs 7.3 85.8 150.6 68.6 217.0 148.4

NoSHEVs, 0 Month 

Payback

8.4 99.8 176.0 74.3 253.5 179.2

Lower Effectiveness 7.2 84.3 146.1 80.4 211.2 130.8

Higher Effectiveness 7.0 82.0 143.1 44.2 206.2 162.0

Lower Direct Costs 7.9 94.0 166.6 68.2 239.4 171.3

Higher Direct Costs 7.5 88.0 153.4 100.9 220.8 119.9

Wider Diesel Downsizing 7.7 90.5 158.1 51.7 227.7 176.1

07 Pct Discount Rate 7.8 91.5 85.4 37.7 138.0 100.3

07 Pct DR, 0 Month 

Payback

8.9 104.7 98.7 39.9 159.1 119.2
Page 508 of 850

Allow Gas To Diesel 9.0 96.3 152.8 71.6 226.9 155.3

Allow Gas To Diesel, 0 

Month Payback

10.3 112.2 182.0 84.6 268.6 184.0

Flat mix after 2016 7.9 92.3 160.1 59.1 231.3 172.2

(7) Uncertainty Analysis

As in previous rules, NHTSA has conducted an uncertainty analysis to determine the 

extent to which uncertainty about input assumptions could impact the costs and benefits 

attributable to the proposed rule. Unlike the preceding sensitivity analysis, which is useful for 

understanding how alternative values of a single input assumption may influence the estimated 

impacts of the proposed standards, the uncertainty analysis considers multiple states of the 

world, characterized by a distribution of specific values of all relevant inputs, based on their 

relative probability of occurrence. A sensitivity analysis varies a single parameter of interest, 

holding all others constant at whatever nominal values are used to generate the single point 

estimate in the main analysis, and measures the resulting deviation. However, the uncertainty 

analysis allows all of those parameters to vary simultaneously – relaxing the assumption that “all 

else is equal”. 

Each trial, of which there are 14,000 in this analysis, represents a different state of the 

world in which the standards are implemented. To gauge the robustness of the estimates of 

impacts in the proposal, NHTSA varied technology costs and effectiveness, fuel prices, market 

demand for fuel economy improvements in the absence of the rule, the amount of additional 

driving associated with fuel economy improvements (the rebound effect), and the on-road gaps 

between realized fuel economy and laboratory test values for gasoline and diesel vehicles. The 

shapes and types of the probability distributions used in the analysis vary by uncertainty 

parameter, though the costs and effectiveness values for technologies are sampled as groups to 

minimize issues associated with interdependence. The most important input to the uncertainty 

analysis, fuel prices (which drive the majority of benefits from the proposed standards), are 

drawn from a range of fuel prices characterized by permutations of the Low, Reference, and 

High fuel price cases in the Annual Energy Outlook 2014.
Page 509 of 850

Figure VI-7 Distribution of Net Benefits from Proposed Standards for HD Pickups and Vans
Page 510 of 850

Figure VI-7 displays the distribution of net benefits estimated by the ensemble of 

simulation runs. As Figure VI-7 indicates, the analysis produces a wide distribution of possible 

outcomes that are much broader than the range of estimates characterized by only the difference 

between the more and less dynamic baselines. While the expected value, the probabilityweighted average outcome, is only about 70 percent of the net benefits estimated in the main 

analysis, almost all of the trials produce positive net benefits. In fact, the distribution suggests 

there is only a one percent chance of the proposal producing negative net benefits for HD 

pickups and vans. So while the estimated net benefits in the main analysis may be higher than 

the expected value when uncertainty is considered, net benefits at least as high as those estimated 

in the main analysis are still 20 times as likely as an outcome that results in net costs.

Figure VI-8 shows the distribution of payback periods (in years) for Model Year 2029 

trucks across 14,000 simulation runs. The “payback period” typically refers to the number of 

years of vehicle use that occur before the savings on fuel expenditures offset the additional 

technology cost associated with improved fuel economy. As Figure VI-8 illustrates, the 

expected incremental technology cost of both Phase 1 and Phase 2 is eclipsed by the value of 

fuel savings by year three of ownership in most cases
Page 511 of 850

Figure VI-8 Average Payback Period for MY 2029 HP Pickup or Van Based on Expected Phase 1 and Phase 

2 (combined) Technology Costs
Page 512 of 850

This is an important metric for owner/operator acceptability and, though Figure VI-8

illustrates the long right tail of the payback distribution (where payback periods are likely to be 

unacceptably long), fewer than ten percent of the trials result in payback periods longer than four 

years. This suggests that, even in the face of uncertainty about future fuel prices and fuel 

economy in real-world driving conditions, buyers of the vehicles that are modified to comply

with the requirements of the proposal will still see fuel savings greater than their additional 

vehicle cost in a relatively short period of time. As one would expect, the technologies used in 

Phase 1 of the MDHD program are likely to be more cost effective and serve to lower the 

expected payback period, even compared to the main analysis of Phase 2.

E. Compliance and Flexibility for HD Pickup and Van Standards

(1) Averaging, Banking, and Trading

The Phase 1 program established substantial flexibility in how manufacturers can choose 

to implement EPA and NHTSA standards while preserving the benefits for the environment and 

for energy consumption and security. Primary among these flexibilities are the gradual phase-in 

schedule, and the corporate fleet average approach which encompasses averaging, banking and 

trading described below. See Section IV.A. of the Phase 1 preamble (76 FR 57238) for 

additional discussion of the Phase 1 averaging, banking, and trading and Section IV.A (3) of the 

Phase 1 preamble (76 FR 57243) for a discussion of the credit calculation methodology.

Manufacturers in this category typically offer gasoline and diesel versions of HD pickup 

and van vehicle models. The agencies established chassis-based Phase 1 standards that are 

equivalent in terms of stringency for gasoline and diesel vehicles and are proposing the same 

approach to stringency for Phase 2. In Phase 1, the agencies established that HD pickups and 

vans are treated as one large averaging set that includes both gasoline and diesel vehicles379 and 

the agencies are proposing to maintain this averaging set approach for Phase 2.

As explained in Section II.C(3) of the Phase 1 preamble (76 FR 57167), and in Section 

VI.B (3) above, the program is structured so that final compliance is determined at the end of 

each model year, when production for the model year is complete. At that point, each 

manufacturer calculates production-weighted fleet average CO2 emission and fuel consumption 

rates along with its production-weighted fleet average standard. 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 would 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 within the HD pickup 

 

379 See 40 CFR Section 1037.104 (d). Credits may not be transferred or traded between this vehicle averaging set 

and loose engines or other heavy-duty categories, as discussed in Section I.
Page 513 of 850

and van averaging set. These types of credit provisions also exist in the light-duty 2012-2016 

and 2017-2025 MY vehicle rules, 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. 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. Averaging vehicle credits with 

engine credits or between vehicle weight classes is not allowed, as discussed in Section I. The 

agencies are not proposing changes to any of these provisions for the Phase 2 program. 

While the agencies are proposing to retain 5 year carry-forward of credits for all HD 

sectors, the agencies request comment on the merits of a temporary credit carry-forward period 

of longer than 5 years for HD pickups and vans, allowing Phase 1 credits generated in MYs 

2014-2019 to be used through MY 2027. EPA included a similar provision in the MY 2017-

2025 light-duty vehicle rule, which allows a one-time credit carry-forward of MY 2010-2015 

credits to be carried forward through MY 2021.380 Such a credit carry-forward extension for HD 

pickups and vans may provide manufacturers with additional flexibility during the transition to 

the proposed Phase 2 standards. A temporary credit carry-forward period of longer than five 

years for Phase 1 credits may help manufacturers resolve lead-time issues they might face as the 

proposed more stringent Phase 2 standards phase-in and help avoid negative impacts to their 

product redesign cycles which tend to be longer than those for light-duty vehicles.

As discussed in Section VI.B.4., EPA is proposing to change the HD pickup and van 

useful life for GHG emissions from the current 11 years/120,000 miles to 15 years/150,000 miles 

to make the useful life for GHG emissions consistent with the useful life of criteria pollutants 

recently updated in the Tier 3 rule. As shown in the Equation VI-1 credits calculation formula 

below, established by the Phase 1 rule, useful life in miles is a multiplicative factor included in 

the calculation of CO2 and fuel consumption credits. In order to ensure banked credits maintain 

their value in the transition from Phase 1 to Phase 2, NHTSA and EPA propose an adjustment 

factor of 1.25 (i.e, 150,000÷120,000) for credits that are carried forward from Phase 1 to the MY 

2021 and later Phase 2 standards. Without this adjustment factor the proposed change in useful 

life would effectively result in a discount of banked credits that are carried forward from Phase 1 

to Phase 2, which is not the intent of the change in the useful life. Consider, for example, a 

vehicle configuration with annual sales of 1,000 vehicles that was 10 g/mile below the standard. 

Under Phase 1, those vehicles would generate 1,200 Mg of credit 

(10×1,000×120,000÷1,000,000). Under Phase 2, the same vehicles would generate 1,500 Mg of 

credit (10×1,000×150,000÷1,000,000). The agencies do not believe that this proposed 

adjustment results in a loss of program benefits because there is little or no deterioration 

anticipated for CO2 emissions and fuel consumption over the life of the vehicles. Also, as 

described in the standards and feasibility sections above, the carry-forward of credits is an 

integral part of the program, helping to smoothing the transition to the new Phase 2 standards. 

The agencies believe that effectively discounting carry-forward credits from Phase 1 to Phase 2 

 

380 77 FR 62788, October 15, 2012.
Page 514 of 850

would be unnecessary and could negatively impact the feasibility of the proposed Phase 2 

standards. EPA and NHTSA request comment on all aspects of the averaging, banking, and 

trading program.

Equation VI-1 Total Model Year Credit (Debit) Calculation

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)

(2) Advanced Technology Credits

The Phase 1 program included on an interim basis advanced technology credits for MYs 

2014 and later in the form of a multiplier of 1.5 for the following technologies: 

 Hybrid powertrain designs that include energy storage systems

 Waste heat recovery

 All-electric vehicles

 Fuel cell vehicles 

The advanced technology credit program is intended to encourage early development of 

technologies that are not yet commercially available. This multiplier approach means that each 

advanced technology vehicle would count as 1.5 vehicles in a manufacturer’s compliance 

calculation. A manufacturer also has the option to subtract these vehicles out of its fleet and 

determine their performance as a separate fleet calculating 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 conventional pickup and van category credit balance. 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 and the proposed off-cycle technology credits discussed in the 

following subsection. The agencies also capped the amount of advanced credits that can be 
Page 515 of 850

transferred into any averaging set into any model year at 60,000 Mg to prevent market 

distortions.

The advanced technology multipliers were included on an interim basis in the Phase 1 

program and the agencies are proposing to end the incentive multipliers beginning in MY 2021, 

when the more stringent Phase 2 standards are proposed to begin phase-in. The agencies are 

proposing a similar approach for the other HD sectors as discussed in Section I.C. (1). The 

advanced technology incentives are intended to promote the commercialization of technologies 

that have the potential to provide substantially better GHG emissions and fuel consumption if 

they were able to overcome major near-term market barriers. However, the incentives are not 

intended to be a permanent part of the program as they result in a decrease in overall GHG 

emissions and fuel consumption benefits associated with the program when used. More 

importantly, as explained in Section I. above, the agencies are already predicating the stringency

of the proposed standards on development and deployment of two of these Phase 1 advanced 

technologies (waste heat recovery and strong hybrid technology), so that it would be 

inappropriate (and essentially a windfall) to include credits for use of these technologies in Phase 

2.381 

As discussed in Section I, the agencies request comment on the proposed approach for 

the advanced technology multipliers for HD pickups and vans as well as the other HD sectors, 

including comments on whether or not the credits should be extended to later model years for 

more advanced technologies such as EVs and fuel cell vehicles. These technologies are not 

projected to be part of the technology path used by manufacturer to meet the proposed Phase 2 

standards for HD pickups and vans. Waste heat recovery is also not projected to be used for HD 

pickups and vans in the time frame of the proposed rules. EV and fuel cell technologies would 

presumably need to overcome the highest hurdles to commercialization for HD pickups and vans

in the time frame of the proposed rules, and also have the potential to provide the highest level of 

benefit. We welcome comments on the need for such incentives, including information on why

an incentive for specific technologies in this time frame may be warranted, recognizing that the 

incentive would result in reduced benefits in terms of CO2 emissions and fuel use due to the 

Phase 2 program.

NHTSA and EPA established that for Phase 1, 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. The agencies also established 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) rather than including upstream emissions or energy consumption associated with 

electricity generation. As we look to the future, we are not projecting the adoption of electric 

 

381 EPA and NHTSA similarly included temporary advanced technology multipliers in the light-duty 2017-2025 

program, believing it was worthwhile to forego modest additional emissions reductions and fuel consumption 

improvements in the near-term in order to lay the foundation for the potential for much larger “game-changing” 

GHG and oil consumption reductions in the longer term. The incentives in the light-duty vehicle program are 

available through the 2021 model year. See 77 FR 62811, October 15, 2012.
Page 516 of 850

HD pickups and vans into the market; therefore, we believe that this provision is still 

appropriate. Unlike the MY2012-2016 light-duty rule, which adopted a cap whereby upstream 

emissions would be counted after a certain volume of sales (see 75 FR 25434-25436), we believe 

there is no need to propose a cap for HD pickups and vans because of the infrequent projected 

use of EV technologies in the Phase 2 timeframe. In Phase 2, we propose to continue to deem 

electric vehicles as having zero CO2, CH4, and N2O emissions as well as zero fuel consumption. 

We welcome comments on this approach. See also Section I for a discussion of the treatment of 

lifecycle emissions for alternative fuel vehicles and Section XI for the treatment of lifecycle 

emissions for natural gas specifically.

(3) Off-cycle Technology Credits

The Phase 1 program established an opportunity for manufacturers to generate credits by

applying innovative technologies whose CO2 and fuel consumption benefits are not captured on 

the 2-cycle test procedure (i.e., off-cycle).382 As discussed in Sections III.F. and V.E.3., the 

agencies are proposing approaches for Phase 2 off-cycle technology credits for tractors and 

vocational vehicles with proposed provisions tailored for those sectors. For HD pickups and 

vans, the approach for off-cycle technologies established in Phase 1 is similar to that established 

for light-duty vehicles due to the use of the same basic chassis test procedures. The agencies are 

proposing to retain this approach for Phase 2. To generate credits, manufacturers are required to 

submit data and a methodology for determining the level of credits for the off-cycle technology

subject to EPA and NHTSA review and approval. The application for off-cycle technology

credits is also subject to a public evaluation process and comment period. EPA and NHTSA 

would approve the methodology and credits only if certain criteria were met. Baseline emissions 

and fuel consumption383 and control emissions and fuel consumption 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 must be on a vehicle model-specific 

basis unless a manufacturer demonstrated model-specific data were not necessary. Once a 

complete application is submitted by the manufacturer, the regulations require that the agencies 

publish a notice of availability in the Federal Register notifying the public of a manufacturer’s 

proposed off-cycle credit calculation methodology and provide opportunity for comment. 

As noted above, the approach finalized for HD pickups and vans paralleled provisions for 

off-cycle credits in the MY 2012-2016 light-duty vehicle GHG program.384 In the MY 2017-

2025 light-duty vehicle program, EPA revised the off-cycle credits program for light-duty 

vehicles to streamline the credits process. In addition to the process established in the MY 2012-

2016 rule, EPA added a list or “menu” of pre-approved off-cycle technologies and associated 

credit levels.385 Manufacturers may use the pre-defined off-cycle technology menu to generate 

light-duty vehicle credits by demonstrating at time of certification that the vehicles are equipped 

 

382 See 76 FR 57251, September 15, 2011 and 40 CFR 1037.104(d)(13).

383

 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.

384 See 75 FR 25440, May 7, 2010 and 40 CFR 86.1869(d).

385 77 FR 62832-62839, October 15, 2012.
Page 517 of 850

with the technology without providing additional test data. Different levels of credits are 

provided for cars and light trucks in the light-duty program. NHTSA also included these credits 

in the CAFE program (in gallons/mile equivalent) starting with MY 2017. The list of preapproved off-cycle technologies for light-duty vehicles is shown below.

Table VI-33 Pre-Approved Off-Cycle Technologies for Light-Duty Vehicles 

Pre-approved technologies

High Efficiency Exterior Lighting (at 100W)

Waste Heat Recovery (at 100W; scalable)

Solar Roof Panels (for 75 W, battery charging 

only)

Solar Roof Panels (for 75 W, active cabin 

ventilation plus battery charging)

Active Aerodynamic Improvements 

(scalable)

Engine Idle Start-Stop w/ heater circulation 

system

Engine Idle Start-Stop without/ heater 

circulation system

Active Transmission Warm-Up

Active Engine Warm-Up

Solar/Thermal Control

The agencies initially note that where vehicles are not chassis-certified, but rather 

evaluate compliance using the GEM simulation tool, with the proposed modifications to GEM, 

many more technologies (especially those related to engine and transmission improvements) will 

now be ‘on-cycle’ – evaluated directly by the GEM compliance tool. However, with respect to 

the proposed standards which would be chassis-certified – namely, the standards for heavy duty 

pickups and vans, the effectiveness of some technologies will be only partially captured (or not 

captured at all). EPA and NHTSA are requesting comment on establishing a pre-defined 

technology menu list for HD pickups and vans. The list for HD pickups and vans could include 

some or all of the technologies listed in Table VI-33. As with the light-duty program, the predefined list may simplify the process for generating off-cycle credits and may further encourage 

the introduction of these technologies. However, the appropriate default level of credits for the 

heavier vehicles would need to be established. The agencies request comments with supporting 

HD pickup and van specific data and analysis that would provide a substantive basis for 

appropriate adjustments to the credits levels for the HD pickup and van category. The data and 

analysis would need to demonstrate that the pre-defined credit level represents real-world 

emissions reductions and fuel consumption improvements not captured by the 2-cycle test 

procedures. 
Page 518 of 850

As with the light-duty vehicle program, the agencies would also consider including a cap 

on credits generated from a pre-defined list established for HD pickups and vans. The cap for 

the light-duty vehicle program is 10 g/mile (and gallons/mi equivalent) applied on a 

manufacturer fleet-wide basis.386 The 10 g/mile cap limits the total off-cycle credits allowed 

based on the pre-defined list across the manufacturer’s light-duty vehicle fleet. The agencies 

adopted the cap on credits to address issues of uncertainty regarding the level of credits 

automatically assigned to each technology. Manufacturers able to demonstrate that a technology

provides improvements beyond the menu credit level would be able to apply for additional 

credits through the individual demonstration process noted above. Credits based on the 

individual manufacturer demonstration would not count against the credit cap. If a menu list of 

credits is developed to be included in the HD pickup and van program, a cap may also be 

appropriate depending on the technology list and credit levels. The agencies request comments 

on all aspects of the off-cycle credits program for HD trucks and vans.

(4) Demonstrating Compliance for Heavy-duty Pickup Trucks and Vans

The Phase 1 rule established a comprehensive compliance program for HD pickups and 

vans that NHTSA and EPA are generally retaining for Phase 2. The compliance provisions 

cover details regarding the implementation of the fleet average standards including vehicle 

certification, demonstrating compliance at the end of the model year, in-use standards and 

testing, carryover of certification test data, and reporting requirements. Please see Section V.B 

(1) of the Phase 1 rule preamble (76 FR 57256-57263) for a detailed discussion of these 

provisions.

The Phase 1 rule contains special provisions regarding loose engines and optional chassis 

certification of certain vocational vehicles over 14,000 lbs. GVWR. The agencies are proposing 

to extend the optional chassis certification provisions to Phase 2 and are not proposing to extend 

the loose engine provisions. See the vocational vehicle Section V.E. and XIV.A.2 for a detailed

discussion of the proposal for optional chassis certification and II.D. for the discussion of loose 

engines. 

 

386 See 40 CFR 86.1869-12(b).
Page 519 of 850

VII. Aggregate GHG, Fuel Consumption, and Climate Impacts

Given that the purpose of setting these Phase 2 standards is to reduce fuel consumption 

and greenhouse gas (GHG) emissions from heavy-duty vehicles, it is necessary for the agencies 

to analyze the extent to which the proposed standards would accomplish that purpose. This 

section describes the agencies’ methodologies for projecting the reductions in greenhouse gas 

(GHG) emissions and fuel consumption, and the methodologies the agencies used to quantify the 

impacts associated with the proposed standards, as well as the impacts of Alternative 4. In 

addition, EPA’s analyses of the projected change in atmospheric carbon dioxide (CO2) 

concentration and consequent climate change impacts are discussed. Because of NHTSA’s 

obligations under EPCA/EISA and NEPA, NHTSA further analyzes, for each regulatory

alternative, the projected environmental impacts related to fuel consumption, GHG emissions, 

and climate change. Detailed documentation of this analysis is provided in Chapters 3 and 5 of 

NHTSA’s DEIS accompanying today’s notice.

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

and Fuel Consumption Impacts?

Different tools exist for estimating potential fuel consumption and GHG emissions 

impacts associated with fuel efficiency and GHG emission standards. One such tool is EPA’s 

official mobile source emissions inventory model named Motor Vehicle Emissions Simulator

(MOVES).

387

 The agencies used the most current version of the model, MOVES2014, to 

quantify the impacts of the proposed standards for vocational vehicles and combination tractortrailers on GHG emissions and fuel consumption for each regulatory alternative. MOVES was 

run with user input databases, described in more detail below, that reflected the projected 

technological improvements resulting from the proposed rules, such as the improvements in 

engine and vehicle efficiency, aerodynamic drag, and tire rolling resistance.

Another such tool is DOT’s CAFE model, which estimates how manufacturers could 

potentially apply technology improvements in response to new standards, and then calculates, 

among other things, resultant changes in national fuel consumption and GHG emissions. For 

today’s analysis of potential new standards for HD pickups and vans, the model was 

reconfigured to use the work-based attribute metric of “work factor” established in the Phase 1 

rule for heavy-duty pickups and vans instead of the light-duty “footprint” attribute metric. The 

CAFE model takes user-specified inputs on, among other things, vehicles that will be produced 

in a given model year, technologies available to improve fuel efficiency on those vehicles, 

potential regulatory standards that would drive improvements in fuel efficiency, and economic 

assumptions. The CAFE model takes every vehicle in each manufacturer’s fleet and decides 

what technologies to add to those vehicles in order to allow each manufacturer to comply with 

the standards in the most cost-effective way. Based on the resulting improved vehicle fleet, the 

CAFE model then calculates total fuel consumption and GHG emissions impacts based on those 

 

387 MOVES homepage: http://www.epa.gov/otaq/models/moves/index.htm (last accessed Feb 23, 2015). 
Page 520 of 850

inputs, along with economic costs and benefits. The DOT’s CAFE model is further described in 

detail in Section VI.C of the preamble and Chapter 2 of the draft RIA. 

For these rules, the agencies conducted coordinated and complementary analyses by 

using two analytical methods for the heavy-duty pickup and van segment employing both DOT’s 

CAFE model and EPA’s MOVES model. The agencies used EPA’s MOVES model to estimate 

fuel consumption and emissions impacts for tractor-trailers (including the engine that powers the 

tractor), and vocational vehicles (including the engine that powers the vehicle). 

For heavy-duty pickups and vans, the agencies performed complementary analyses,

which we refer to as “Method A” and “Method B”. In Method A, the CAFE model was used to 

project a pathway the industry could use to comply with each regulatory alternative and the 

estimated effects on fuel consumption, emissions, benefits and costs. In Method B, the MOVES 

model was used to estimate fuel consumption and emissions from these vehicles. NHTSA 

considered Method A as its central analysis. EPA considered the results of both methods. The 

agencies concluded that both methods led the agencies to the same conclusions and the same 

selection of the proposed standards. See Chapter 5 of the draft RIA for additional discussions of 

these two methods.

For both methods, the agencies analyzed the impact of the proposed rules and Alternative 

4, relative to two different reference cases – less dynamic and more dynamic. The less dynamic 

baseline projects very little improvement in new vehicles in the absence of new Phase 2 

standards. In contrast, the more dynamic baseline projects more improvements in vehicle fuel 

efficiency. The agencies considered both reference cases (for additional details, see Chapter 11 

of the draft RIA). The results for all of the regulatory alternatives relative to both reference 

cases, derived via the same methodologies discussed in this section, are presented in Section X 

of the preamble. 

For brevity, a subset of these analyses are presented in this section, and the reader is 

referred to both the RIA Chapter 11 and NHTSA’s DEIS Chapters 3 and 5 for complete sets of 

these analyses. In this section, Method A is presented for both the proposed standards (i.e., 

Alternative 3—the agencies’ preferred alternative) and for the standards the agencies considered 

in Alternative 4, relative to both the more dynamic baseline (Alternative 1b) and the less 

dynamic baseline (Alternative 1a). Method B is presented also for the proposed standards and 

Alternative 4, but relative only to the less dynamic baseline. The agencies’ intention for 

presenting both of these complementary and coordinated analyses is to offer interested readers 

the opportunity to compare the regulatory alternatives considered for Phase 2 in both the context 

of our HD Phase 1 analytical approaches and our light-duty vehicle analytical approaches. The 

agencies view these analyses as corroborative and reinforcing: both support agencies’ conclusion 

that the proposed standards are appropriate and at the maximum feasible levels.

Because reducing fuel consumption also affects emissions that occur as a result of fuel 

production and distribution (including renewable fuels), the agencies also calculated those 

“upstream” changes using the “downstream” fuel consumption reductions predicted by the 

CAFE model and the MOVES model. As described in Section VI, Method A uses the CAFE 

model to estimate vehicular fuel consumption and emissions impacts for HD pickups and vans 

and to calculate upstream impacts. For vocational vehicles and combination tractor-trailers, both 
Page 521 of 850

Method A and Method B use the same upstream tools originally created for the Renewable Fuel 

Standard 2 (RFS2) rulemaking analysis,388 used in the LD GHG rulemakings,389 HD GHG Phase 

1,390 and updated for the current analysis. The estimate of emissions associated with production 

and distribution of gasoline and diesel from crude oil is based on emission factors in the 

“Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation” model (GREET) 

developed by DOE's Argonne National Lab. In some cases, the GREET values were modified or 

updated by the agencies to be consistent with the National Emission Inventory (NEI) and 

emission factors from MOVES. Method B uses the same tool described above to estimate the 

upstream impacts for HD pickups and vans. For additional details, see Chapter 5 of the draft 

RIA. The upstream tool used for the Method B can be found in the docket.391 As noted in 

Section VI above, these analyses corroborate each other’s results. 

The agencies analyzed the anticipated emissions impacts of the proposed rules and 

Alternative 4 on carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and 

hydrofluorocarbons (HFCs) for a number of calendar years (for purposes of the discussion in 

these proposed rules, only 2025, 2035 and 2050 will be shown) by comparing to both reference 

cases.392 Additional runs were performed for just the three of the greenhouse gases (CO2, CH4, 

and N2O) 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, discussed in sections below.393

B. Analysis of Fuel Consumption and GHG Emissions Impacts 

Resulting from Proposed Standards and Alternative 4

The following sections describe the model inputs and assumptions for both the less 

dynamic and more dynamic reference cases and the control case representing the agencies’ 

proposed fuel efficiency and GHG standards. The agencies request comment on the model 

inputs, projected reductions in energy rates and fuel consumption rates presented in this section, 

as well as in Chapter 5 of the draft RIA. The details of all the MOVES runs, and input data 

 

388 U.S. EPA. Draft Regulatory Impact Analysis: Changes to Renewable Fuel Standard Program. Chapters 2 and 3. 

May 26, 2009. Docket ID: EPA-HQ-OAR-2009-0472-0119

389 2017 and Later Model Year Light-Duty Vehicle Greenhouse Gas Emissions and Corporate Average Fuel 

Economy Standards (77 FR 62623, October 15, 2012)

390 Greenhouse Gas Emission Standards and Fuel Efficiency Standards for Medium- and Heavy-Duty Engines and 

Vehicles (76 FR 57106, September 15, 2011)

391 Memorandum to the Docket “Upstream Emissions Modeling Files for HDGHG Phase 2 NPRM” Docket No. 

EPA-HQ-OAR-2014-0827

392 The emissions impacts of the proposed rules on non-GHGs, including air toxics, were also estimated using 

MOVES. See Section VIII of the preamble for more information.

393 The CAFE model estimates, among other things, manufacturers’ potential multiyear planning decisions within 

the context of an estimated year-by-year product cadence (i.e., schedule for redesigning and freshening vehicles). 

The agencies included earlier model years in the analysis in order to account for the potential that manufacturers 

might take anticipatory actions in model years preceding those covered by today’s proposal.
Page 522 of 850

tables, as well as the MOVES code and database, can be found in the docket.394 See Section 

VI.C for the discussion of the model inputs and assumptions for the analysis of the HD pickups 

and vans using DOT’s CAFE Model.

(1) Model Inputs and Assumptions for the Less Dynamic Reference Case

The less dynamic reference case (identified as Alternative 1a in Section X), includes the 

impact of Phase 1, but generally assumes that fuel efficiency and GHG emission standards are 

not improved beyond the required 2018 model year levels. Alternative 1a functions as one of the 

baselines against which the impacts of the proposed standards can be evaluated. This case 

projects some improvements in the efficiency of the box trailers pulled by combination tractors 

due to increased penetration of aerodynamic technologies and low rolling resistance tires 

attributed to both EPA’s SmartWay Transport Partnership and California Air Resources Board’s 

Tractor-Trailer Greenhouse Gas regulation, as described in Section IV of the preamble. For 

other HD vehicle sectors, no market-driven improvement in fuel efficiency was assumed. For 

HD pickups and vans, the CAFE model was applied in a manner that assumes manufacturers 

would only add fuel-saving technology as needed to continue complying with Phase 1 standards. 

MOVES2014 defaults were used for all other parameters to estimate the emissions inventories 

for this case. The less dynamic reference case assumed the MOVES2014 default vehicle 

population and miles traveled estimates. The growth in vehicle populations and miles traveled in 

MOVES2014 is based on the relative annual VMT growth from AEO2014 Early Release for 

model years 2012 and later.395

(2) Model Inputs and Assumptions for the More Dynamic Reference Case

The more dynamic reference case (identified as Alternative 1b in Section X), also 

includes the impact of Phase 1 and generally assumes that fuel efficiency and GHG emission 

standards are not improved beyond the required 2018 model year levels. However, for this case, 

the agencies assume market forces would lead to additional fuel efficiency improvements for HD 

pickups and vans and tractor-trailers. These additional assumed improvements are described in 

Section X of the preamble. No additional fuel efficiency improvements due to market forces 

were assumed for vocational vehicles. For HD pickups and vans, the agencies applied the CAFE 

model using the input assumption that manufacturers having achieved compliance with Phase 1

standards would continue to apply technologies for which increased purchase costs would be 

“paid back” through corresponding fuel savings within the first six months of vehicle operation. 

The agencies conducted the MOVES analysis of this case in the same manner as for the less 

dynamic reference case.

 

394 Memorandum to the Docket “Runspecs, Model Inputs, MOVES Code and Database for HD GHG Phase 2 

NPRM Emissions Modeling” Docket No. EPA-HQ-OAR-2014-0827

395 MOVES2014 assumes the population and VMT growth based on the early release version of AEO2014 because 

it was the only version that was available at the time of MOVES2014 development. Annual Energy Outlook 2014. 

http://www.eia.gov/forecasts/aeo/er/ (last accessed Feb 23, 2015).
Page 523 of 850

(3) Model Inputs and Assumptions for “Control” Case

(a) Vocational Vehicles and Tractor-Trailers

The “control” case represents the agencies’ proposed fuel efficiency and GHG standards. 

The agencies developed additional user input data for MOVES runs to estimate the control case 

inventories. The inputs to MOVES for the control case account for improvements of engine and 

vehicle efficiency in vocational vehicles and combination tractor-trailers. The agencies used the 

percent reduction in aerodynamic drag and tire rolling resistance coefficients and absolute 

changes in average total running weight (gross combined weight) expected from the proposed 

rules to develop the road load inputs for the control case, based on the GEM analysis. The 

agencies also used the percent reduction in CO2 emissions expected from the powertrain and 

other vehicle technologies not accounted for in the aerodynamic drag and tire rolling resistance 

in the proposed rules to develop energy inputs for the control case runs. 

Table VII-1 and Table VII-2 describe the proposed improvements in engine and vehicle 

efficiency from the proposed rules for vocational vehicles and combination tractor-trailers that 

were input into MOVES for estimating the control case emissions inventories. Additional details 

regarding the MOVES inputs are included in the Chapter 5 of the draft RIA.
Page 524 of 850

Table VII-1 Estimated Reductions in Energy Rates for the Proposed Standards

VEHICLE TYPE FUEL MODEL 

YEARS

REDUCTION FROM 

REFERENCE CASE

Long-haul 

Tractor-Trailers

and HHD 

Vocational

Diesel 2018-2020 1.3%

2021-2023 5.2%

2024-2026 9.7%

2027+ 10.4%

Short-haul 

Tractor-Trailers

and HHD 

Vocational

Diesel 2018-2020 0.9%

2021-2023 5.0%

2024-2026 9.5%

2027+ 10.4%

Single-Frame 

Vocational396

Diesel and 

CNG

2021-2023 5.3%

2024-2026 8.9%

2027+ 13.3%

Gasoline 2021-2023 3.3%

2024-2026 5.4%

2027+ 10.3%

 

396 Vocational vehicles modeled in MOVES include heavy heavy-duty, medium heavy-duty, and light heavy-duty 

vehicles. However, for light heavy-duty vocational vehicles, class 2b and 3 vehicles are not included in the 

inventories for the vocational sector. Instead, all vocational vehicles with GVWR of less than 14,000 lbs were 

modeled using the energy rate reductions described below for HD pickup trucks and vans. In practice, many 

manufacturers of these vehicles choose to average the lightest vocational vehicles into chassis-certified families (i.e., 

heavy-duty pickups and vans). 
Page 525 of 850

Table VII-2 Estimated Reductions in Road Load Factors for the Proposed Standards

VEHICLE 

TYPE

MODEL 

YEARS

REDUCTION IN 

TIRE ROLLING 

RESISTANCE 

COEFFICIENT

REDUCTION IN 

AERODYNAMIC 

DRAG 

COEFFICIENT

WEIGHT 

REDUCTION 

(LB)i

Combination 

Long-haul 

TractorTrailers

2018-

2020

5.5% 5.1% -131

2021-

2023

9.8% 15.3% -199

2024-

2026

15.7% 20.5% -246

2027+ 17.9% 26.9% -304

Combination 

Short-haul 

TractorTrailers397

2018-

2020

4.0% 1.6% -41

2021-

2023

10.5% 9.3% -79

2024-

2026

13.9% 12.3% -100

2027+ 17.6% 15.9% -127

Intercity 

Buses

2021-

2023

6.5% 0% 0

2024-

2026

9.2% 0% 0

2027+ 16.5% 0% 0

Transit 

Buses

2021-

2023

0% 0% 0

2024-

2026

2.9% 0% 0

2027+ 3.0% 0% 0

School 

Buses

2021-

2023

0% 0% 0

2024-

2026

2.9% 0% 0

2027+ 4.0% 0% 0

Refuse 

Trucks

2021-

2023

0% 0% 20

2024-

2026

2.9% 0% 20

2027+ 3.0% 0% 25

Single Unit 

Short-haul 

Trucks

2021-

2023

4.8% 0% 5.8

2024-

2026

8.3% 0% 5.8

 

397 Vocational tractors are included in the short-haul tractor segment.
Page 526 of 850

2027+ 13.0% 0% 7

Single Unit

Long-haul 

Trucks

2021-

2023

6.5% 0% 20

2024-

2026

9.2% 0% 20

2027+ 16.5% 0% 25

Motor 

Homes

2021-

2023

3.0% 0% 0

2024-

2026

6.2% 0% 0

2027+ 7.4% 0% 0

Note:

i Negative weight reductions reflect an expected weight increase as a byproduct of other vehicle and engine

improvements, as described in Chapter 5 of the draft RIA.

In addition, the proposed CO2 standard for tractors reflecting the use of auxiliary power 

units (APU) during extended idling, as discussed in Section III.D of the preamble, was included 

in the modeling for the long-haul combination tractor-trailers, as shown below in Table VII-3.

Table VII-3 Assumed APU Use during Extended Idling for Combination Long-haul Tractor-Trailers

VEHICLE TYPE MODEL 

YEAR

APU PENETRATIONi

Combination LongHaul Trucks2010-2020 30%

2021-2023 80%

2024+ 90%

Note:

i The assumed APU penetration remains constant for model years 2024 and later.

To account for the potential increase in vehicle use expected to result from improvements 

in fuel efficiency for vocational vehicles and combination tractor-trailers due to the proposed 

rules (also known as the “rebound effect” and described in more detail in Chapter 5 of the draft 

RIA), the control case assumed an increase in VMT from the reference levels by 1.83 percent for 

the vocational vehicles and 0.79 percent for the combination tractor-trailers.

(b) Heavy-Duty Pickups and Vans

As explained above and as also discussed in the draft RIA, the agencies used both DOT’s 

CAFE model and EPA’s MOVES model, for Method A and B, respectively, to project fuel 

consumption and GHG emissions impacts resulting from the proposed standards for HD pickups 

and vans, including downstream vehicular emissions as well as emissions from upstream 

processes related to fuel production, distribution, and delivery. 

(i) Method A for HD Pickups and Vans

For Method A, the agencies used the CAFE model which applies fuel properties (density

and carbon content) to estimated fuel consumption in order to calculate vehicular CO2 emissions,
Page 527 of 850

applies per-mile emission factors from MOVES to estimated VMT (for each regulatory

alternative, adjusted to account for the rebound effect) in order to calculate vehicular CH4 and 

N2O emissions (as well, as discussed below, of non-GHG pollutants), and applies per-gallon 

upstream emission factors from GREET in order to calculate upstream GHG (and non-GHG) 

emissions.

As discussed above in Section VI, the proposed standards for HD pickups and vans—that 

is, the functions defining fuel consumption and GHG targets that each depend work factor—

increase in stringency by 2.5 percent annually during model years 2021-2027. The standards 

define targets specific to each vehicle model, but no vehicle is required to meet its target; instead, 

the production-weighted averages of the vehicle-specific targets define average fuel consumption 

and CO2 emission rates that a given manufacturer’s overall fleet of produced vehicles is required 

to achieve. The standards are specified separately for gasoline and diesel vehicles, and vary with 

work factor. Work factors could change, and today’s analysis assumes that some applications of 

mass reduction could enable increased work factor in cases where manufacturers could increase 

a vehicle’s rated payload and/or towing capacity. Therefore, average required levels will depend 

on the mix of vehicles and work factors of the vehicles produced for sale in the U.S., and since 

these can only be estimated at this time, average required and achieved fuel consumption and 

CO2 emission rates are subject to uncertainty. Between today’s notice and issuance of the 

ensuing final rule, the agencies intend to update the market forecast (and other inputs) used to 

analyze HD pickup and van standards, and expect that doing so will lead to different estimates of 

required and achieved fuel consumption and CO2 emission rates (as well as different estimates of 

impacts, costs, and benefits).

The following four tables present stringency increases and estimated required and 

achieved fuel consumption and CO2 emission rates for the two No Action Alternatives 

(Alternative 1a and 1b) and the proposed standards defining the Preferred Alternative. 

Stringency increases are shown relative to standards applicable in model year 2018 (and through 

model year 2020). As mathematical functions, the standards themselves are not subject to 

uncertainty. By 2027, they are 16.2 percent more stringent (i.e., lower) than those applicable 

during 2018-2020. NHTSA estimates that, by model 2027, the proposed standards could reduce 

average required fuel consumption and CO2 emission rates to about 4.86 gallons/100 miles and 

about 458 grams/mile, respectively. NHTSA further estimates that average achieved fuel 

consumption and CO2 emission rates could correspondingly be reduced to about the same levels. 

If, as represented by Alternative 1b, manufacturers would, even absent today’s proposed 

standards, voluntarily make improvements that pay back within six months, these model year 

2027 levels are about 13.5 percent lower than the agencies estimate could be achieved under the 

Phase 1 standards defining the No Action Alternative. If, as represented by Alternative 1a, 

manufacturers would, absent today’s proposed standards, only apply technology as required to 

achieve compliance, these model year 2027 levels are about 15 percent lower than the agencies 

estimate could be achieved under the Phase 1 standards. As indicated below, the agencies 

estimate that these improvements in fuel consumption and CO2 emission rates would build from 

model year to model year, beginning as soon as model year 2017 (insofar as manufacturers may

make anticipatory improvements if warranted given planned produce cadence).
Page 528 of 850

Table VII-VII-4 Stringency of HD Pickup and Van Standards, Estimated Average Required and Achieved 

Fuel Consumption Rates for Method A, Relative to Alternative 1b a

Model Year Stringency 

(vs. 2018)

Ave. Required Fuel Cons. (gal./100 mi.) Ave. Achieved Fuel Cons. (gal./100 mi.)

No Action Proposed Reduction No Action Proposed Reduction

2014 MYs 2014-

2020 

Subject to 

Phase 1

Standards

6.41 6.41 0.0% 6.21 6.21 0.0%

2015 6.41 6.41 0.0% 6.12 6.12 0.0%

2016 6.27 6.27 0.0% 6.15 6.15 0.0%

2017 6.11 6.11 0.0% 5.89 5.88 0.2%

2018 5.80 5.80 0.0% 5.75 5.70 0.8%

2019 5.78 5.78 0.0% 5.72 5.68 0.7%

2020 5.78 5.78 0.0% 5.69 5.64 0.8%

2021 2.5% 5.77 5.64 2.2% 5.63 5.42 3.8%

2022 4.9% 5.77 5.50 4.7% 5.63 5.42 3.8%

2023 7.3% 5.77 5.38 6.8% 5.63 5.28 6.3%

2024 9.6% 5.77 5.25 9.0% 5.63 5.23 7.1%

2025 11.9% 5.77 5.12 11.4% 5.63 4.99 11.5%

2026 14.1% 5.77 4.98 13.7% 5.63 4.93 12.5%

2027 16.2% 5.77 4.86 15.8% 5.62 4.86 13.7%

2028* 16.2% 5.77 4.86 15.8% 5.62 4.86 13.7%

2029* 16.2% 5.77 4.86 15.8% 5.62 4.85 13.7%

2030* 16.2% 5.77 4.86 15.8% 5.62 4.85 13.7%

Notes:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

*Absent further action, standards assumed to continue unchanged after model year 2027.
Page 529 of 850

Table VII-VII-5 Stringency of HD Pickup and Van Standards, Estimated Average Required and Achieved 

CO2 Emission Rates for Method A, Relative to Alternative 1b a

Model Year Stringency 

(vs. 2018)

Ave. Required CO2 Rate (g./mi.) Ave. Achieved CO2 Rate (g./mi.)

No Action Proposed Reduction No Action Proposed Reduction

2014 MYs 2014-

2020 

Subject to 

Phase 1

Standards

602 602 0.0% 581 581 0.0%

2015 608 608 0.0% 578 578 0.0%

2016 593 593 0.0% 580 580 0.0%

2017 578 578 0.0% 556 554 0.2%

2018 548 548 0.0% 543 538 0.8%

2019 545 545 0.0% 539 535 0.7%

2020 545 545 0.0% 536 532 0.8%

2021 2.5% 544 532 2.2% 530 510 3.8%

2022 4.9% 544 519 4.7% 530 510 3.8%

2023 7.3% 544 507 6.8% 530 496 6.4%

2024 9.6% 544 495 9.1% 530 492 7.2%

2025 11.9% 544 482 11.3% 530 470 11.3%

2026 14.1% 544 470 13.6% 530 465 12.3%

2027 16.2% 544 458 15.8% 529 458 13.4%

2028* 16.2% 544 458 15.8% 529 458 13.4%

2029* 16.2% 544 458 15.8% 529 458 13.5%

2030* 16.2% 544 458 15.8% 529 458 13.5%

Notes:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

*Absent further action, standards assumed to continue unchanged after model year 2027.
Page 530 of 850

Table VII-VII-6 Stringency of HD Pickup and Van Standards, Estimated Average Required and Achieved 

Fuel Consumption Rates for Method A, Relative to Alternative 1a a

Model Year Stringency 

(vs. 2018)

Ave. Required Fuel Cons. (gal./100 mi.) Ave. Achieved Fuel Cons. (gal./100 mi.)

No Action Proposed Reduction No Action Proposed Reduction

2014 MYs 2014-

2020 

Subject to 

Phase 1

Standards

6.41 6.41 0.0% 6.21 6.21 0.0%

2015 6.41 6.41 0.0% 6.12 6.12 0.0%

2016 6.27 6.27 0.0% 6.15 6.15 0.0%

2017 6.11 6.11 0.0% 5.89 5.87 0.3%

2018 5.80 5.80 -0.1%** 5.75 5.70 0.9%

2019 5.78 5.78 0.0% 5.73 5.68 0.8%

2020 5.78 5.78 0.0% 5.73 5.68 0.8%

2021 2.5% 5.77 5.64 2.3% 5.72 5.44 4.8%

2022 4.9% 5.77 5.50 4.7% 5.72 5.44 4.8%

2023 7.3% 5.77 5.38 6.8% 5.72 5.29 7.6%

2024 9.6% 5.77 5.25 9.1% 5.72 5.23 8.5%

2025 11.9% 5.77 5.12 11.4% 5.72 4.98 12.9%

2026 14.1% 5.77 4.98 13.7% 5.72 4.94 13.6%

2027 16.2% 5.77 4.86 15.8% 5.72 4.87 14.9%

2028* 16.2% 5.77 4.86 15.8% 5.72 4.87 14.9%

2029* 16.2% 5.77 4.86 15.8% 5.72 4.86 15.0%

2030* 16.2% 5.77 4.86 15.8% 5.72 4.86 15.0%

Notes:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.*Absent further action, standards assumed to 

continue unchanged after model year 2027.

**Increased work factor for some vehicles produces a slight increase in average required fuel consumption.
Page 531 of 850

Table VII-VII-7 Stringency of HD Pickup and Van Standards, Estimated Average Required and Achieved 

CO2 Emission Rates for Method A, Relative to Alternative 1a a

Model Year Stringency 

(vs. 2018)

Ave. Required CO2 Rate (g./mi.) Ave. Achieved CO2 Rate (g./mi.)

No Action Proposed Reduction No Action Proposed Reduction

2014 MYs 2014-

2020 

Subject to 

Phase 1

Standards

602 602 0.0% 581 581 0.0%

2015 608 608 0.0% 578 578 0.0%

2016 593 593 0.0% 580 580 0.0%

2017 578 578 0.0% 556 554 0.3%

2018 548 548 -0.1%** 543 538 0.9%

2019 545 546 -0.1%** 539 535 0.8%

2020 545 545 -0.1%** 539 535 0.8%

2021 2.5% 544 532 2.2% 538 512 4.9%

2022 4.9% 544 519 4.7% 538 512 4.9%

2023 7.3% 544 507 6.8% 538 497 7.7%

2024 9.6% 544 495 9.1% 538 492 8.6%

2025 11.9% 544 482 11.4% 538 470 12.7%

2026 14.1% 544 470 13.6% 538 466 13.4%

2027 16.2% 544 458 15.8% 538 459 14.7%

2028* 16.2% 544 458 15.8% 538 459 14.7%

2029* 16.2% 544 458 15.8% 538 459 14.8%

2030* 16.2% 544 458 15.8% 538 459 14.8%

Notes:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.*Absent further action, standards assumed to 

continue unchanged after model year 2027.

**Increased work factor for some vehicles produces a slight increase in the average required CO2 emission rate.

While the above tables show the agencies’ estimates of average fuel consumption and 

CO2 emission rates manufacturers might achieve under today’s proposed standards, total U.S. 

fuel consumption and GHG emissions from HD pickups and vans will also depend on how many 

of these vehicles are produced, and how they are operated over their useful lives. Relevant to 

estimating these outcomes, the CAFE model applies vintage-specific estimates of vehicle 

survival and mileage accumulation, and adjusts the latter to account for the rebound effect. This 

impact of the rebound effect is specific to each model year (and, underlying, to each vehicle

model in each model year), varying with changes in achieved fuel consumption rates. 

(ii) Method B for HD Pickups and Vans

For Method B, the MOVES model was used to estimate fuel consumption and GHG 

emissions for HD pickups and vans. MOVES evaluated the proposed standards for HD pickup 

trucks and vans in terms of grams of CO2 per mile or gallons of fuel per 100 miles. Since nearly 

all HD pickup trucks and vans are certified on a chassis dynamometer, the CO2 reductions for 

these vehicles were not represented as engine and road load reduction components, but rather as 

total vehicle CO2 reductions. The control case for HD pickups and vans assumed an increase in 

VMT from the reference levels by 1.18 percent for HD pickups and vans.
Page 532 of 850

Table VII-8 Estimated Total Vehicle CO2 Reductions for the Proposed Standards and In-Use Emissions for 

HD Pickup Trucks and Vans in Method B a

VEHICLE TYPE FUEL MODEL 

YEAR

CO2 REDUCTION 

FROM REFERENCE 

CASE

HD pickup trucks 

and vans

Gasoline 

and Diesel

2021 2.50%

2022 4.94%

2023 7.31%

2024 9.63%

2025 11.89%

2026 14.09%

2027+ 16.24%

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an 

explanation of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see 

Section X.A.1.

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

Emissions?

NHTSA and EPA expect significant reductions in GHG emissions and fuel consumption 

from the proposed rules – fuel consumption reductions from more efficient vehicles, emission 

reductions from both downstream (tailpipe) and upstream (fuel production and distribution) 

sources, and HFC emissions from the proposed air conditioning leakage standards. The 

following subsections summarize two slightly different analyses of the annual GHG emissions 

and fuel consumption reductions expected from these proposed rules, as well as the reductions in 

GHG emissions and fuel consumption expected over the lifetime of each heavy-duty vehicle 

categories. In addition, because the agencies are carefully considering Alternative 4 along with 

Alternative 3, the preferred alternative, the results from both are presented here for the reader’s 

reference. Section VII. C. (1) shows the impacts of the proposed rules and Alternative 4 on fuel 

consumption and GHG emissions using the MOVES model for tractor-trailers and vocational 

vehicles, and the DOT’s CAFE model for HD pickups and vans (Method A), relative to two 

different reference cases – less dynamic and more dynamic. Section VII. C. (2) shows the 

impacts of the proposed standards and Alternative 4, relative to the less dynamic reference case 

only, using the MOVES model for all heavy-duty vehicle categories. NHTSA also analyzes 

these impacts resulting from the proposed rules and reasonable alternatives in Chapters 3 and 5 

of its DEIS.
Page 533 of 850

(1) Impacts of the Proposed Rules and Alternative 4 using Analysis Method A

(a) Calendar Year Analysis

(i) Downstream (Tailpipe) Emissions Projections

As described in Section VII. A, for the analysis using Method A, the agencies used 

MOVES to estimate downstream GHG inventories from the proposed rules for vocational 

vehicles and tractor-trailers. For HD pickups and vans, DOT’s CAFE model was used. 

The following two tables summarize the agencies’ estimates of HD pickup and van fuel 

consumption and GHG emissions under the current and proposed standards defining the NoAction and Preferred alternatives, respectively, using Method A. Table VII-VII-9 shows results 

assuming manufacturers would voluntarily make improvements that pay back within six months 

(i.e., Alternative 1b). Table VII-VII-10 shows results assuming manufacturers would only make 

improvements as needed to achieve compliance with standards (i.e., Alternative 1a). While 

underlying calculations are all performed for each calendar year during each vehicle’s useful life, 

presentation of outcomes on a model year basis aligns more clearly with consideration of cost 

impacts in each model year, and with consideration of standards specified on a model year basis. 

In addition, Method A analyzes manufacturers’ potential responses to HD pickup and van 

standards on a model year basis through 2030, and any longer-term costs presented in today’s 

notice represent extrapolation of these results absent any underlying analysis of longer-term 

technology prospects and manufacturers’ longer-term product offerings.
Page 534 of 850

Table VII-VII-9 Estimated Fuel Consumption and GHG Emissions over Useful Life of HD Pickups and Vans

Produced in Each Model Year for Method A, Relative to Alternative 1b a

Model Year Fuel Consumption (b. gal.)

over Fleet’s Useful Life

GHG Emissions (MMT CO2eq)

over Fleet’s Useful Life

No Action Proposed Reduction No Action Proposed Reduction

2014 9.41 9.41 0.0% 115 115 0.0%

2015 9.53 9.53 0.0% 117 117 0.0%

2016 9.72 9.72 0.0% 119 119 0.0%

2017 9.49 9.47 0.2% 116 116 0.2%

2018 9.26 9.19 0.7% 113 113 0.7%

2019 9.20 9.14 0.7% 113 112 0.7%

2020 9.19 9.12 0.7% 112 112 0.7%

2021 9.10 8.79 3.4% 111 107 3.4%

2022 9.13 8.82 3.4% 112 108 3.4%

2023 9.11 8.59 5.7% 111 105 5.7%

2024 9.32 8.72 6.4% 114 107 6.4%

2025 9.49 8.49 10.5% 116 104 10.4%

2026 9.67 8.56 11.5% 118 105 11.3%

2027 9.78 8.55 12.6% 120 105 12.3%

2028 9.90 8.66 12.6% 121 106 12.3%

2029 10.02 8.75 12.6% 122 107 12.4%

2030 10.03 8.76 12.6% 123 107 12.4%

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.
Page 535 of 850

Table VII-VII-10 Estimated Fuel Consumption and GHG Emissions over Useful Life of HD Pickups and 

Vans Produced in Each Model Year for Method A, Relative to Alternative 1a a

Model Year Fuel Consumption (b. gal.)

over Fleet’s Useful Life

GHG Emissions (MMT CO2eq)

over Fleet’s Useful Life

No Action Proposed Reduction No Action Proposed Reduction

2014 9.41 9.41 0.0% 115 115 0.0%

2015 9.53 9.53 0.0% 117 117 0.0%

2016 9.72 9.72 0.0% 119 119 0.0%

2017 9.49 9.46 0.3% 116 116 0.3%

2018 9.27 9.19 0.8% 114 113 0.8%

2019 9.20 9.14 0.7% 113 112 0.7%

2020 9.25 9.18 0.7% 113 112 0.8%

2021 9.23 8.82 4.4% 113 108 4.4%

2022 9.26 8.85 4.4% 113 108 4.4%

2023 9.23 8.60 6.9% 113 105 6.9%

2024 9.45 8.72 7.7% 116 107 7.7%

2025 9.62 8.48 11.8% 118 104 11.7%

2026 9.81 8.58 12.5% 120 105 12.3%

2027 9.93 8.57 13.7% 121 105 13.5%

2028 10.05 8.68 13.7% 123 106 13.5%

2029 10.17 8.77 13.7% 124 108 13.5%

2030 10.18 8.78 13.7% 124 108 13.5%

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

To more clearly communicate these trends visually, the following two charts present the 

above results graphically for Method A, relative to Alternative 1b. As shown, fuel consumption 

and GHG emissions follow parallel though not precisely identical paths. Though not presented,

the charts for Alternative 1a would appear sufficiently similar that differences between 

Alternative 1a and Alternative 1b remain best communicated by comparing values in the above 

tables.
Page 536 of 850

Figure VII-9 Fuel Consumption (b. gal.) over Useful Life of HD Pickups and Vans Produced in Each Model 

Year for Method A
Page 537 of 850

Figure VII-10 GHG Emissions (MMT CO2eq) over Useful Life of HD Pickups and Vans Produced in Each 

Model Year for Method A
Page 538 of 850

Table VII-11 Annual Downstream GHG Emissions Impacts in Calendar Years 2025, 2035 and 2050 –

Preferred Alternative vs. Alt 1b using Analysis Method A a

CY CO2

(MMT)

CH4

(MMT CO2eq)

N2O 

(MMT CO2eq)9

TOTAL DOWNSTREAM 

(MMT CO2eq)

2025 -26.9 -0.4 0 -27.2

2035 -86.0 -1.0 0 -86.9

2050 -121.6 -1.4 0 -123.0

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less 

dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table VII-12 Annual Fuel Savings in Calendar Years 2025, 2035 and 2050 – Preferred Alternative vs. Alt 1b

using Analysis Method A a

CY DIESEL SAVINGS

(Billion Gallons)

GASOLINE SAVINGS

(Billion Gallons)

2025 2.5 0.2

2035 7.6 0.9

2050 10.8 1.2

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation 

of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table VII-13 Annual Downstream GHG Emissions Impacts in Calendar Years 2025, 2035 and 2050 –

Preferred Alternative vs. Alt 1a using Analysis Method A a

CY CO2

(MMT)

CH4

(MMT CO2eq)

N2O 

(MMT CO2eq)9

TOTAL DOWNSTREAM 

(MMT CO2eq)

2025 -27.7 -0.4 0 -28.1

2035 -93.6 -1.0 0 -94.6

2050 -133.5 -1.4 0 -134.9

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less 

dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table VII-14 Annual Fuel Savings in Calendar Years 2025, 2035 and 2050 – Preferred Alternative vs. Alt 1a

using Analysis Method A a

CY DIESEL SAVINGS

(Billion Gallons)

GASOLINE SAVINGS

(Billion Gallons)

2025 2.5 0.2

2035 8.3 1.0

2050 11.9 1.3

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation 

of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.
Page 539 of 850

Table VII-15 Annual Downstream GHG Emissions Impacts in Calendar Years 2025, 2035 and 2050 –

Alternative 4 vs. Alt 1b using Analysis Method A a

CY CO2

(MMT)

CH4

(MMT CO2eq)

N2O 

(MMT CO2eq)9

TOTAL DOWNSTREAM 

(MMT CO2eq)

2025 -33.2 -0.4 0 -33.5

2035 -89.9 -1.0 0 -90.9

2050 -122.6 -1.4 0 -124.0

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less 

dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table VII-16 Annual Fuel Savings in Calendar Years 2025, 2035 and 2050 – Alternative 4 vs. Alt 1b using 

Analysis Method A a

CY DIESEL SAVINGS

(Billion Gallons)

GASOLINE SAVINGS

(Billion Gallons)

2025 3.0 0.3

2035 7.9 1.0

2050 10.8 1.3

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation 

of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table VII-17 Annual Downstream GHG Emissions Impacts in Calendar Years 2025, 2035 and 2050 –

Alternative 4 vs. Alt 1a using Analysis Method A a

CY CO2

(MMT)

CH4

(MMT CO2eq)

N2O 

(MMT CO2eq)9

TOTAL DOWNSTREAM 

(MMT CO2eq)

2025 -34.3 -0.4 0 -34.6

2035 -97.7 -1.0 0 -98.7

2050 -134.6 -1.4 0 -136.0

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less 

dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table VII-18 Annual Fuel Savings in Calendar Years 2025, 2035 and 2050 – Alternative 4 vs. Alt 1a using 

Analysis Method A a

CY DIESEL SAVINGS

(Billion Gallons)

GASOLINE SAVINGS

(Billion Gallons)

2025 3.1 0.3

2035 8.6 1.1

2050 12.0 1.3

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation 

of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.
Page 540 of 850

(ii) Upstream (Fuel Production and Distribution) Emissions Projections

(iii)

Table VII-19 Annual Upstream GHG Emissions Impacts in Calendar Years 2025, 2035 and 2050 – Preferred 

Alternative vs. Alt 1b using Analysis Method A a

CY CO2

(MMT)

CH4

(MMT CO2eq)

N2O

(MMT CO2eq)

TOTAL UPSTREAM

(MMT CO2eq)

2025 -8.4 -0.9 -0.1 -9.3

2035 -26.6 -2.8 -0.2 -29.7

2050 -37.7 -4.0 -0.3 -42.0

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less 

dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table VII-20 Annual Upstream GHG Emissions Impacts in Calendar Years 2025, 2035 and 2050 – Preferred 

Alternative vs. Alt 1a using Analysis Method A a

CY CO2

(MMT)

CH4

(MMT CO2eq)

N2O

(MMT CO2eq)

TOTAL UPSTREAM

(MMT CO2eq)

2025 -8.6 -0.9 -0.1 -9.6

2035 -29.0 -3.1 -0.2 -32.3

2050 -41.4 -4.4 -0.3 -46.1

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less 

dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table VII-21 Annual Upstream GHG Emissions Impacts in Calendar Years 2025, 2035 and 2050 –

Alternative 4 vs. Alt 1b using Analysis Method A a

CY CO2

(MMT)

CH4

(MMT CO2eq)

N2O

(MMT CO2eq)

TOTAL UPSTREAM

(MMT CO2eq)

2025 -10.3 -1.1 -0.1 -11.5

2035 -27.8 -3.0 -0.2 -31.0

2050 -38.0 -4.0 -0.3 -42.3

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less 

dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table VII-22 Annual Upstream GHG Emissions Impacts in Calendar Years 2025, 2035 and 2050 –

Alternative 4 vs. Alt 1a using Analysis Method A a

CY CO2

(MMT)

CH4

(MMT CO2eq)

N2O

(MMT CO2eq)

TOTAL UPSTREAM

(MMT CO2eq)

2025 -10.6 -1.1 -0.1 -11.8

2035 -30.2 -3.2 -0.2 -33.7

2050 -41.7 -4.4 -0.3 -46.5

Note:
Page 541 of 850

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less 

dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

(iv) HFC Emissions Projections

The projected HFC emission reductions due to the proposed AC leakage standards are 

93,272 metric tons of CO2eq in 2025, 253,118 metric tons of CO2eq in 2035, and 299,590 metric 

tons CO2eq in 2050.

(v) Total (Downstream + Upstream + HFC) Emissions Projections

Table VII-23 Annual Total GHG Emissions Impacts in Calendar Years 2025, 2035 and 2050 – Preferred 

Alternative vs. Alt 1b using Analysis Method A a

CY 2025 (MMT CO2eq) 2035 (MMT CO2eq) 2050 (MMT CO2eq)

Downstream -27.2 -86.9 -123.0

Upstream -9.3 -29.7 -42.0

HFC -0.09 -0.25 -0.3

Total -36.4 -116.4 -164.7

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table VII-24 Annual Total GHG Emissions Impacts in Calendar Years 2025, 2035 and 2050 2050 –

Preferred Alternative vs. Alt 1a using Analysis Method A a

CY 2025 (MMT CO2eq) 2035 (MMT CO2eq) 2050 (MMT CO2eq)

Downstream -28.1 -94.6 -134.9

Upstream -9.6 -32.3 -46.1

HFC -0.09 -0.25 -0.3

Total -37.6 -126.4 -180.7

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table VII-25 Annual Total GHG Emissions Impacts in Calendar Years 2025, 2035 and 2050 – Alternative 4 

vs. Alt 1b using Analysis Method A a

CY 2025 (MMT CO2eq) 2035 (MMT CO2eq) 2050 (MMT CO2eq)

Downstream -33.5 -90.9 -124.0

Upstream -11.5 -31.0 -42.3

HFC -0.09 -0.25 -0.3

Total -44.9 -121.7 -166.0

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.
Page 542 of 850

Table VII-26 Annual Total GHG Emissions Impacts in Calendar Years 2025, 2035 and 2050 2050 –

Alternative 4 vs. Alt 1a using Analysis Method A a

CY 2025 (MMT CO2eq) 2035 (MMT CO2eq) 2050 (MMT CO2eq)

Downstream -34.6 -98.7 -136.0

Upstream -11.8 -33.7 -46.5

HFC -0.09 -0.25 -0.3

Total -46.3 -132.2 -182.2

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

(b) Model Year Lifetime Analysis

Table VII-27 Lifetime GHG Reductions and Fuel Savings using Analysis Method A – Summary for Model 

Years 2018-2029 a

ALTERNATIVE 3 

(PROPOSED)

ALTERNATIVE 4

NO-ACTION ALTERNATIVE 

(BASELINE)

1b (More 

Dynamic)

1a (Less 

Dynamic)

1b (More 

Dynamic)

1a (Less 

Dynamic)

Fuel Savings (Billion Gallons) 72.2 76.7 81.9 86.7

Total GHG Reductions (MMT CO2eq) 986.6 1,047.4 1,114.8 1,181.1

 Downstream (MMT CO2eq) 735.3 780.8 830.9 880.9

 Upstream (MMT CO2eq) 251.3 266.6 283.9 300.2

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

(2) Impacts of the Proposed Rules and Alternative 4 using Analysis Method B

(a) Calendar Year Analysis

(i) Downstream (Tailpipe) Emissions Projections

As described in Section VII. A., the Method B used MOVES to estimate downstream 

GHG inventories from the proposed rules and Alternative 4 relative to Alternative 1a for all 

heavy-duty vehicle categories (including the engines associated with tractor-trailer combinations 

and vocational vehicles). The agencies expect reductions in CO2 emissions from all heavy-duty 

vehicle categories due to engine and vehicle improvements. We expect N2O emissions to 

increase very slightly because of a rebound in vehicle miles traveled (VMT). However, since 

N2O is produced as a byproduct of fuel combustion, the increase in N2O emissions is expected to 
Page 543 of 850

be more than offset by the improvements in fuel efficiency from the proposed rules.398 We 

expect methane emissions to decrease primarily due to reduced refueling from improved fuel 

efficiency and the differences in hydrocarbon emission characteristics between on-road diesel 

engines and APUs. The amount of methane emitted as a fraction of total hydrocarbons is 

expected to be significantly less for APUs than for on-road diesel engines during extended 

idling. Overall, the downstream GHG emissions would be reduced significantly and are 

described in the following subsections. 

Since fuel consumption is not directly modeled in MOVES, the total energy consumption 

was run as a surrogate in MOVES. Then, the total energy consumption was converted to fuel 

consumption based on the fuel heating values assumed in the Renewable Fuels Standard 

rulemaking399 and used in the development of MOVES emission and energy rates.400 

Table VII-28 and Table VII-29 show the impacts on downstream GHG emissions and 

fuel savings in 2025, 2035 and 2050, relative to Alternative 1a, for the preferred alternative and 

Alternative 4, respectively. Note:

a For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less 

dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table VII-30 and Table VII-31 show the estimated fuel savings from the preferred 

alternative and Alternative 4 in 2025, 2035, and 2050, relative to Alternative 1a. For both GHG 

emissions and fuel savings, the annual impacts are greater for Alternative 4 than the preferred 

alternative in earlier years, but the differences become indistinguishable by 2050. The results 

from the comparable analyses relative to Alternative 1b are presented in Section VII. C. (1).

Table VII-28 Annual Downstream GHG Emissions Impacts in Calendar Years 2025, 2035 and 2050 –

Preferred Alternative vs. Alt 1a using Analysis Method B a

CY CO2

(MMT)

CH4

(MMT CO2eq)

N2O 

(MMT CO2eq)

TOTAL DOWNSTREAM 

(MMT CO2eq)

2025 -27.0 -0.4 0.002 -27.4

2035 -93.7 -1.0 0.004 -94.7

2050 -135.1 -1.4 0.005 -136.5

Note:

 

398 MOVES is not capable of modeling the changes in exhaust N2O emissions from the improvements in fuel 

efficiency. Due to this limitation, a conservative approach was taken to only model the VMT rebound in estimating 

the emissions impact on N2O from the proposed rules, resulting in a slight increase in downstream N2O inventory.

399 Renewable Fuels Standards assumptions of 115,000 BTU/gallon gasoline (E0) and 76,330 BTU/gallon ethanol 

(E100) were weighted 90% and 10%, respectively, for E10 and 85% and 15%, respectively, for E15 and converted 

to kJ at 1.055 kJ/BTU. The conversion factors are 117,245 kJ/gallon for gasoline blended with ten percent ethanol 

(E10) and 115,205 kJ/gallon for gasoline blended with fifteen percent ethanol (E15).

400 The conversion factor for diesel is 138,451 kJ/gallon. See MOVES2004 Energy and Emission Inputs. EPA420-

P-05-003, March 2005. http://www.epa.gov/otaq/models/ngm/420p05003.pdf (last accessed Feb 23, 2015).
Page 544 of 850

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table VII-29 Annual Downstream GHG Emissions Impacts in Calendar Years 2025, 2035 and 2050 –

Alternative 4 vs. Alt 1a using Analysis Method B a

CY CO2

(MMT)

CH4

(MMT CO2eq)

N2O 

(MMT CO2eq)

TOTAL DOWNSTREAM 

(MMT CO2eq)

2025 -33.3 -0.4 0.002 -33.7

2035 -97.3 -1.0 0.004 -98.3

2050 -135.5 -1.4 0.005 -136.9

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table VII-30 Annual Fuel Savings in Calendar Years 2025, 2035 and 2050 – Preferred Alternative vs. Alt 1a 

using Analysis Method B a

CY DIESEL SAVINGS

(Billion Gallons)

GASOLINE SAVINGS

(Billion Gallons)

2025 2.5 0.2

2035 8.5 0.8

2050 12.3 1.1

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation 

of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table VII-31 Annual Fuel Savings in Calendar Years 2025, 2035 and 2050 – Alternative 4 vs. Alt 1a using 

Analysis Method B a

CY DIESEL SAVINGS

(Billion Gallons)

GASOLINE SAVINGS

(Billion Gallons)

2025 3.1 0.3

2035 8.8 0.9

2050 12.3 1.1

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation 

of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

(ii) Upstream (Fuel Production and Distribution) Emissions Projections

(iii)

The upstream GHG emission reductions associated with the production and distribution 

of gasoline and diesel from crude oil were based on emission factors from DOE’s “Greenhouse 

Gases, Regulated Emissions, and Energy Use in Transportation” (GREET) model. In some 

cases, the GREET values were modified or updated by the agencies to be consistent with EPA’s 

National Emissions Inventory (NEI), and emission factors from MOVES. More information 
Page 545 of 850

regarding these modifications can be found in Chapter 5 of the draft RIA. These estimates show 

the impacts for domestic emission reductions only. Additionally, since this rulemaking is not 

expected to impact biofuel volumes mandated by the Annual Renewable Fuel Standards (RFS) 

regulations401, the impacts on upstream emissions from changes in biofuel feedstock (i.e., 

agricultural sources such as fertilizer, fugitive dust, and livestock) are not shown. GHG emission 

reductions from upstream sources can be found in Table VII-32 and Table VII-33 for preferred 

alternative and Alternative 4, respectively.

Table VII-32 Annual Upstream GHG Emissions Impacts in Calendar Years 2025, 2035 and 2050 – Preferred 

Alternative vs. Alt 1a using Analysis Method B a

CY CO2

(MMT)

CH4

(MMT CO2eq)

N2O

(MMT CO2eq)

TOTAL UPSTREAM

(MMT CO2eq)

2025 -8.4 -0.9 -0.04 -9.3

2035 -29.1 -3.0 -0.14 -32.2

2050 -41.9 -4.4 -0.20 -46.5

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table VII-33 Annual Upstream GHG Emissions Impacts in Calendar Years 2025, 2035 and 2050 –

Alternative 4 vs. Alt 1a using Analysis Method B a

CY CO2

(MMT)

CH4

(MMT CO2eq)

N2O

(MMT CO2eq)

TOTAL UPSTREAM

(MMT CO2eq)

2025 -10.4 -1.0 -0.1 -11.5

2035 -30.1 -3.2 -0.1 -33.4

2050 -42.0 -4.4 -0.2 -46.6

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

(iv) HFC Emissions Projections

Based on projected HFC emission reductions due to the proposed AC leakage standards, 

EPA estimates the HFC reductions to be 93,272 metric tons of CO2eq in 2025, 253,118 metric 

tons of CO2eq in 2035, and 299,590 metric tons CO2eq in 2050, as detailed in Chapters 5.3.4 of 

the draft RIA. EPA welcomes comments on the methodology used to quantify the HFC 

emissions benefits, as detailed in Chapter 5 of the draft RIA.

(v) Total (Downstream + Upstream + HFC) Emissions Projections

Table VII-34 combines the impacts of the preferred alternative from downstream (Table 

VII-28), upstream (Table VII-32), and HFC to summarize the total GHG reductions in calendar 

 

401 U.S. EPA. 2014 Standards for the Renewable Fuel Standard Program. 40 CFR Part 90. EPA-HQ-OAR-2013-

0479; FRL-9900-90-OAR, RIN 2060-AR76.
Page 546 of 850

years 2025, 2035 and 2050, relative to Alternative 1a. The combined impact of Alternative 4 on 

total GHG emissions are shown in Table VII-35.

Because of the differences in lead time, as expected, Alternative 4 shows greater annual 

GHG reductions in earlier years (i.e., calendar year 2025), but by 2050, the preferred alternative 

and Alternative 4 show the same magnitude of reductions in annual GHG emissions.

Table VII-34 Annual Total GHG Emissions Impacts in Calendar Years 2025, 2035 and 2050 – Preferred 

Alternative vs. Alt 1a using Analysis Method B a

CY 2025 (MMT CO2eq) 2035 (MMT CO2eq) 2050 (MMT CO2eq)

Downstream -27.4 -94.7 -136.5

Upstream -9.3 -32.2 -46.5

HFC -0.1 -0.25 -0.3

Total -36.8 -127.2 -183.3

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table VII-35 Annual Total GHG Emissions Impacts in Calendar Years 2025, 2035 and 2050 – Alternative 4 

vs. Alt 1a using Analysis Method B a

CY 2025 (MMT CO2eq) 2035 (MMT CO2eq) 2050 (MMT CO2eq)

Downstream -33.7 -98.3 -136.9

Upstream -11.5 -33.4 -46.6

HFC -0.1 -0.25 -0.3

Total -45.3 -132.0 -183.8

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

(b) Model Year Lifetime Analysis

In addition to the annual GHG emissions and fuel consumption reductions expected from 

the proposed rules and Alternative 4, the combined (downstream and upstream) GHG and fuel 

consumption impacts for the lifetime of the impacted vehicles were estimated. Table VII-36

shows the fleet-wide GHG reductions and fuel savings from the preferred alternative and 

Alternative 4, relative to Alternative 1a, through the lifetime402 of heavy-duty vehicles. 

Compared to the preferred alternative, Alternative 4 shows greater lifetime GHG reductions and 

fuels savings by 12 percent and 13 percent, respectively. For the lifetime GHG reductions and 

fuel savings by vehicle categories, see Chapter 5 of the draft RIA.

 

402 A lifetime of 30 years is assumed in MOVES.
Page 547 of 850

Table VII-36 Lifetime GHG Reductions and Fuel Savings using Analysis Method B – Summary for Model 

Years 2018-2029 a

MODEL YEARS ALTERNATIVE 3 

(PROPOSED)

ALTERNATIVE 4

NO-ACTION ALTERNATIVE 

(BASELINE)

1a (Less Dynamic) 1a (Less Dynamic)

Fuel Savings (Billion Gallons) 75.8 85.4

Total GHG Reductions (MMT CO2eq) 1,036.4 1,163.1

 Downstream (MMT CO2eq) 772.6 867.3

 Upstream (MMT CO2eq) 263.8 295.8

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

D. Climate Impacts and Indicators

(1) Climate Change Impacts from GHG Emissions 

The impact of GHG emissions on the climate has been reviewed in the 2009 

Endangerment and Cause or Contribute Findings for Greenhouse Gases under Section 202(a) of 

the Clean Air Act, the 2012-2016 light-duty vehicle rulemaking, the 2014-2018 heavy-duty 

vehicle GHG and Fuel Efficiency rulemaking, and the 2017-2025 light-duty vehicle rulemaking, 

and the proposed standards for new electricity utility generating units. See 74 FR at 66496; 75 

FR at 25491; 76 FR at 57294; 77 FR at 62894; 79 FR at 1456-59 (Jan.8, 2014). This section 

briefly discusses again some of the climate impact of EPA’s proposed actions in context of 

transportation emissions. NHTSA has analyzed the climate impacts of its specific proposed 

actions (i.e., excluding EPA’s HFC regulatory provisions) as well as reasonable alternative in its 

DEIS that accompanies this NPRM. DOT has considered the potential climate impacts 

documented in the DEIS as part of the rulemaking process.

Once emitted, GHGs that are the subject of this proposed regulation can remain in the 

atmosphere for decades to millennia, meaning that 1) their concentrations become well-mixed 

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, agricultural activities, cement 

production, and some industrial activities. Transportation activities, in aggregate, were the 

second largest contributor to total U.S. GHG emissions in 2010 (27 percent of total 

emissions).403

The EPA Administrator relied on thorough and peer-reviewed assessments of climate 

change science prepared by the Intergovernmental Panel on Climate Change (“IPCC”), the 

 

403 U.S. EPA (2012) Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990–2010. EPA 430-R-12-001. 

Available at http://epa.gov/climatechange/emissions/downloads12/US-GHG-Inventory-2012-Main-Text.pdf
Page 548 of 850

United States Global Change Research Program (“USGCRP”), and the National Research 

Council of the National Academies (“NRC”)

404 as the primary scientific and technical basis for 

the Endangerment and Cause or Contribute Findings for Greenhouse Gases Under Section 202(a) 

of the Clean Air Act (74 FR 66496, December 15, 2009). These assessments comprehensively 

address the scientific issues the EPA Administrator had to examine, providing her data and 

information on a wide range of issues pertinent to the Endangerment Finding. These 

assessments have been rigorously reviewed by the expert community, and also by United States 

government agencies and scientists, including by EPA itself.

Based on these assessments, the EPA Administrator determined that the emissions from 

new motor vehicles and engines contributes to elevated concentrations of greenhouse gases, that 

these greenhouse gases cause warming; that the recent warming has been attributed to the 

increase in greenhouse gases; and that warming of the climate endangers the public health and 

welfare of current and future generations. See Coalition for Responsible Regulation v. EPA, 684 

F. 3d 102, 121 (D.C. Cir. 2012) (upholding all of EPA’s findings and stating “EPA had before it 

substantial record evidence that anthropogenic emissions of greenhouse gases ‘very likely’ 

caused warming of the climate over the last several decades. EPA further had evidence of 

current and future effects of this warming on public health and welfare. Relying again upon 

substantial scientific evidence, EPA determined that anthropogenically induced climate change 

threatens both public health and public welfare. It found that extreme weather events, changes in 

air quality, increases in food- and water-borne pathogens, and increases in temperatures are 

likely to have adverse health effects. The record also supports EPA’s conclusion that climate 

change endangers human welfare by creating risk to food production and agriculture, forestry, 

energy, infrastructure, ecosystems, and wildlife. Substantial evidence further supported EPA’s 

conclusion that the warming resulting from the greenhouse gas emissions could be expected to 

create risks to water resources and in general to coastal areas as a result of expected increase in 

sea level.”) 

A number of major peer-reviewed scientific assessments have been released since the 

administrative record concerning the Endangerment Finding closed following EPA’s 2010 

Reconsideration Denial405. These assessments include the “Special Report on Managing the 

Risks of Extreme Events and Disasters to Advance Climate Change Adaptation”406, the 2013-14 

Fifth Assessment Report (AR5),407 the 2014 National Climate Assessment report,408 the “Ocean 

 

404 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-2010-0799)

405 “EPA’s Denial of the Petitions to Reconsider the Endangerment and Cause or Contribute Findings for 

Greenhouse Gases under Section 202(a) of the Clean Air Act”, 75 Fed. Reg. 49,556 (Aug. 13, 2010) 

(“Reconsideration Denial”).

406 Intergovernmental Panel on Climate Change (IPCC). 2012: Managing the Risks of Extreme 

Events and Disasters to Advance Climate Change Adaptation. A Special Report of Working 

Groups I and II of the Intergovernmental Panel on Climate Change. Cambridge University 

Press, Cambridge, UK, and New York, NY, USA.

407 Intergovernmental Panel on Climate Change (IPCC). 2013. Climate Change 2013: The Physical Science Basis. 

Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate 
Page 549 of 850

Acidification: A National Strategy to Meet the Challenges of a Changing Ocean,”409 “Report on 

Climate Stabilization Targets: Emissions, Concentrations, and Impacts over Decades to 

Millennia,”410 “National Security Implications for U.S. Naval Forces” (National Security

Implications),411 “Understanding Earth’s Deep Past: Lessons for Our Climate Future,”412 “Sea 

Level Rise for the Coasts of California, Oregon, and Washington: Past, Present, and Future,”413

“Climate and Social Stress: Implications for Security Analysis,”414 and “Abrupt Impacts of 

Climate Change” (Abrupt Impacts) assessments.415

EPA has reviewed these assessments and finds that in general, the improved 

understanding of the climate system they present are consistent with the assessments underlying 

the 2009 Endangerment Finding.

The most recent assessments released were the IPCC AR5 assessments between 

September 2013 and April 2014, the NRC Abrupt Impacts assessment in December of 2013, and 

the U.S. National Climate Assessment in May of 2014. The NRC Abrupt Impacts report 

examines the potential for tipping points, thresholds beyond which major and rapid changes 

occur in the Earth’s climate system or other systems impacted by the climate. The Abrupt 

Impacts report did find less cause for concern than some previous assessments regarding some 

abrupt events within the next century such as disruption of the Atlantic Meridional Overturning 

Circulation (AMOC) and sudden releases of high-latitude methane from hydrates and 

permafrost, but found that the potential for abrupt changes in ecosystems, weather and climate 

extremes, and groundwater supplies critical for agriculture now seem more likely, severe, and 

imminent. The assessment found that some abrupt changes were already underway (Arctic sea 

 

Change. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, Intergovernmental 

Panel on Climate Change (IPCC). 2014. Climate Change 2014: Impacts, Adaptation, and Vulnerability. 

Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate 

Change. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, Intergovernmental 

Panel on Climate Change (IPCC). 2014. Climate Change 2014: Mitigation of Climate Change. Contribution of 

Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge 

University Press, Cambridge, United Kingdom and New York, NY, USA.

408 Melillo, Jerry M., Terese (T.C.) Richmond, and Gary W. Yohe, Eds. 2014. Climate Change Impacts in the United

States: The Third National Climate Assessment. U.S. Global Change Research Program. Available at 

<http://nca2014.globalchange.gov>

409 National Research Council (NRC). 2010. Ocean Acidification: A National Strategy to Meet the Challenges of a 

Changing Ocean. National Academies Press. Washington, DC.

410 National Research Council (NRC). 2011. Climate Stabilization Targets: Emissions, Concentrations, and Impacts 

over Decades to Millennia. National Academies Press, Washington, DC.

411 National Research Council (NRC) 2011. National Security Implications of Climate Change for U.S. Naval 

Forces. National Academies Press. Washington, DC.

412 National Research Council (NRC). 2012. Sea-Level Rise for the Coasts of California, Oregon, and Washington: 

Past, Present, and Future. National Academies Press. Washington, DC.

413 National Research Council (NRC). 2012. Sea-Level Rise for the Coasts of California, Oregon, and Washington: 

Past, Present, and Future. National Academies Press. Washington, DC.

414 National Research Council (NRC). 2013. Climate and Social Stress: Implications for Security Analysis. National 

Academies Press. Washington, DC.

415 National Research Council (NRC). 2013. Abrupt Impacts of Climate Change: Anticipating Surprises. National 

Academies Press. Washington, DC.
Page 550 of 850

ice retreat and increases in extinction risk due to the speed of climate change), but cautioned that 

even abrupt changes such as the AMOC disruption that are not expected in this century can have 

severe impacts when they happen.

The IPCC AR5 assessments are also generally consistent with the underlying science 

supporting the 2009 Endangerment Finding. For example, confidence in attributing recent 

warming to human causes has increased: the IPCC stated that it is extremely likely (>95 percent 

confidence) that human influences have been the dominant cause of recent warming. Moreover, 

the IPCC found that the last 30 years were likely (>66 percent confidence) the warmest 30 year 

period in the Northern Hemisphere of the past 1400 years, that the rate of ice loss of worldwide 

glaciers and the Greenland and Antarctic ice sheets has likely increased, that there is medium 

confidence that the recent summer sea ice retreat in the Arctic is larger than it has been in 1450 

years, and that concentrations of carbon dioxide and several other of the major greenhouse gases 

are higher than they have been in at least 800,000 years. Climate-change induced impacts have 

been observed in changing precipitation patterns, melting snow and ice, species migration, 

negative impacts on crops, increased heat and decreased cold mortality, and altered ranges for 

water-borne illnesses and disease vectors. Additional risks from future changes include death, 

injury, and disrupted livelihoods in coastal zones and regions vulnerable to inland flooding, food 

insecurity linked to warming, drought, and flooding, especially for poor populations, reduced 

access to drinking and irrigation water for those with minimal capital in semi-arid regions, and 

decreased biodiversity in marine ecosystems, especially in the Arctic and tropics, with 

implications for coastal livelihoods. The IPCC determined that “[c]ontinued emissions of 

greenhouse gases will cause further warming and changes in all components of the climate 

system. Limiting climate change will require substantial and sustained reductions of greenhouse 

gases emissions.”

Finally, the recently released National Climate Assessment stated, “Climate change is 

already affecting the American people in far reaching ways. Certain types of extreme weather 

events with links to climate change have become more frequent and/or intense, including 

prolonged periods of heat, heavy downpours, and, in some regions, floods and droughts. In 

addition, warming is causing sea level to rise and glaciers and Arctic sea ice to melt, and oceans 

are becoming more acidic as they absorb carbon dioxide. These and other aspects of climate 

change are disrupting people’s lives and damaging some sectors of our economy.”

Assessments from these bodies represent the current state of knowledge, 

comprehensively cover and synthesize thousands of individual studies to obtain the majority

conclusions from the body of scientific literature and undergo a rigorous and exacting standard 

of review by the peer expert community and U.S. government.

Based on modeling analysis performed by the agencies, reductions in CO2 and other 

GHG emissions associated with these proposed rules will affect future climate change. Since 

GHGs are well-mixed in the atmosphere and have long atmospheric lifetimes, changes in GHG 

emissions will affect atmospheric concentrations of greenhouse gases and future climate for 

decades to millennia, depending on the gas. This section provides estimates of the projected 

change in atmospheric CO2 concentrations based on the emission reductions estimated for these

proposed rules, compared to the reference case. In addition, this section analyzes the response to 
Page 551 of 850

the changes in GHG concentrations of the following climate-related variables: global mean 

temperature, sea level rise, and ocean pH. 

(2) Projected Change in Atmospheric CO2 Concentrations, Global Mean Surface 

Temperature and Sea Level Rise

To assess the impact of the emissions reductions from the proposed rules, EPA estimated 

changes in projected atmospheric CO2 concentrations, global mean surface temperature and sealevel rise to 2100 using the GCAM (Global Change Assessment Model, formerly MiniCAM), 

integrated assessment model416 coupled with the MAGICC (Model for the Assessment of 

Greenhouse-gas Induced Climate Change) simple climate model.417 GCAM was used to create 

the globally and temporally consistent set of climate relevant emissions required for running 

MAGICC. MAGICC was then used to estimate the projected change in relevant climate 

variables over time. Given the magnitude of the estimated emissions reductions associated with 

these rules, a simple climate model such as MAGICC is appropriate for estimating the 

atmospheric and climate response.

The analysis projects that the proposed rules would reduce atmospheric concentrations of 

CO2, global climate warming, ocean acidification, 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 or when considered in isolation. 

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 rules avoids essentially permanent climate change on centennial time scales. 

EPA determines that the projected reductions in atmospheric CO2, global mean 

temperature, sea level rise, and ocean pH are meaningful in the context of this action. The 

results of the analysis, summarized in Table VII-37, demonstrate that relative to the reference 

case, by 2100 projected atmospheric CO2 concentrations are estimated to be reduced by 1.1 to 

 

416 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 greenhouse gases (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.

417 MAGICC consists of a suite of coupled gas-cycle, climate and ice-melt models integrated into a single 

framework. The framework allows the user to determine changes in greenhouse-gas concentrations, global-mean 

surface air temperature and sea-level resulting from anthropogenic emissions of carbon dioxide (CO2), methane 

(CH4), nitrous oxide (N2O), reactive gases (CO, NOx, VOCs), the halocarbons (e.g. HCFCs, HFCs, PFCs) and 

sulfur dioxide (SO2). MAGICC emulates the global-mean temperature responses of more sophisticated coupled 

Atmosphere/Ocean General Circulation Models (AOGCMs) with high accuracy.
Page 552 of 850

1.2 part per million by volume (ppmv), global mean temperature is estimated to be reduced by 

0.0026 to 0.0065 °C, and sea-level rise is projected to be reduced by approximately 0.023 to 

0.057 cm, based on a range of climate sensitivities (described below). Details about this 

modeling analysis can be found in the draft RIA Chapter 6.3.

Table VII-37 Impact of GHG Emissions Reductions on Projected Changes in Global Climate Associated with 

Proposed Phase 2 Standards for MY 2018-2024 (Based on a range of climate sensitivities from 1.5-6°C)

Variable Units Year Projected Change

Atmospheric CO2 CONCENTRATION ppmv 2100 -1.1 to -1.2

Global Mean Surface Temperature oC 2100 -0.0026 to -0.0065

Sea Level Rise cm 2100 -0.023 to -0.057

Ocean pH pH units 2100 +0.0006a

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), 

CO2 concentration (404 to 470 ppm), sea level rise (23 – 56 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. Moreover, these effects are occurring everywhere 

around the globe, so benefits that appear to be marginal for any one location, such as a reduction 

in seal level rise of half a millimeter, can be sizable when the effects are summed along 

thousands of miles of coastline. 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: estimates of 

sea level rise from the recent NRC, IPCC, and NCA assessments range from 26 cm to 2 meters 

depending on the emissions scenario, the processes included, and the likelihood range assessed; 

inclusion of these effects would lead to correspondingly larger benefits of mitigation. Further 

discussion of EPA’s modeling analysis is found in the RIA, Chapter 6.3.

Based on the projected atmospheric CO2 concentration reductions resulting from these

proposed rules, EPA calculates an increase in ocean pH of 0.0006 pH units in 2100 relative to 

the baseline case (this is a reduction in the expected acidification of the ocean of a decrease of 

0.3 pH units from 1990 to 2100 in the baseline case). Thus, this analysis indicates the projected 

decrease in atmospheric CO2 concentrations from the proposed Phase 2 standards would result in 

an increase in ocean pH (i.e., a reduction in the expected acidification of the ocean in the 

reference case). A more detailed discussion of the modeling analysis associated with ocean pH 

is provided in the draft RIA, Chapter 6.3.

The 2011 NRC assessment on "Climate Stabilization Targets: Emissions, Concentrations, 

and Impacts over Decades to Millennia" determined how a number of climate impacts - such as 

heaviest daily rainfalls, crop yields, and Arctic sea ice extent - would change with a temperature 

change of 1 degree Celsius (C) of warming. These relationships of impacts with temperature 

change could be combined with the calculated reductions in warming in Table VII-37 to estimate 

changes in these impacts associated with this proposed rulemaking.
Page 553 of 850

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 some degree of 

effectively permanent climate change. Therefore, reductions in emissions in the near-term are 

important in determining climate impacts experienced not just over the next decades but over 

thousands of years.418 Though the magnitude of the avoided climate change projected here in 

isolation 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 this proposed rule’s impact on global climate conditions is intended to 

quantify these potential reductions using the best available science. EPA’s modeling results 

show consistent reductions relative to the baseline case in changes of CO2 concentration, 

temperature, sea-level rise, and ocean pH over the next century. 

 

418 National Research Council (NRC) (2011). Climate Stabilization Targets: Emissions, Concentrations, and Impacts 

over Decades to Millennia. National Academy Press. Washington, DC. (Docket EPA-HQ-OAR-2010-0799)
Page 554 of 850

VIII. How Will This Proposed Action Impact Non-GHG Emissions 

and Their Associated Effects?

The proposed heavy-duty vehicle standards are expected to influence the emissions of 

criteria air pollutants and several air toxics. This section describes the projected impacts of the 

proposed rules and Alternative 4 on non-GHG emissions and air quality, and the health and 

environmental effects associated with these pollutants. NHTSA further analyzes these projected 

health and environmental effects resulting from its proposed rules and reasonable alternatives in 

Chapter 4 of its DEIS. 

A. Emissions Inventory Impacts

As described in Section VII, the agencies conducted coordinated and complementary

analyses for these rules by employing both DOT’s CAFE model and EPA’s MOVES model, 

relative to different reference cases (i.e., different baselines). The agencies used EPA’s MOVES 

model to estimate the non-GHG impacts for tractor-trailers (including the engine that powers the 

vehicle), and vocational vehicles (including the engine that powers the vehicle). For heavy-duty

pickups and vans, the agencies performed complementary analyses using the CAFE model 

(“Method A”) and the MOVES model (“Method B”) to estimate non-GHG emissions from these 

vehicles. For both methods, the agencies analyzed the impact of the proposed rules, relative to 

two different reference cases – less dynamic and more dynamic. The less dynamic baseline 

projects very little improvement in new vehicles in the absence of new Phase 2 standards. In 

contrast, the more dynamic baseline projects more improvements in vehicle fuel efficiency. The 

agencies considered both reference cases. The results for all of the regulatory alternatives 

relative to both reference cases, derived via the same methodologies discussed in Section VII of 

the Preamble, are presented in Section X of the Preamble. 

For brevity, a subset of these analyses are presented in this section and the reader is 

referred to both the RIA Chapter 11 and NHTSA’s DEIS Chapters 3 and 5 for complete sets of 

these analyses. In this section, Method A is presented for both the proposed standards (i.e., 

Alternative 3—the agencies’ preferred alternative) and for the standards the agencies considered 

in Alternative 4, relative to both the more dynamic baseline (Alternative 1b) and the less 

dynamic baseline (Alternative 1a). Method B is presented also for the proposed standards and 

Alternative 4, but relative only to the less dynamic baseline. The agencies’ intention for 

presenting both of these complementary and coordinated analyses is to offer interested readers 

the opportunity to compare the regulatory alternatives considered for Phase 2 in both the context 

of our HD Phase 1 analytical approaches and our light-duty vehicle analytical approaches. The 

agencies view these analyses as corroborative and reinforcing: both support agencies’ conclusion 

that the proposed standards are appropriate and at the maximum feasible levels.

The following subsections summarize two slightly different analyses of the annual nonGHG emissions reductions expected from the proposed standards and Alternative 4. Section 

VIII. A. (1) presents the impacts of the proposed rules and Alternative 4 on non-GHG emissions 

using the analytical Method A, relative to two different reference cases – less dynamic and more 

dynamic. Section VIII. A. (2) presents the impacts of the proposed standards and Alternative 4, 
Page 555 of 850

relative to the less dynamic reference case only, using the MOVES model for all heavy-duty 

vehicle categories. 

(1) Impacts of the Proposed Rules and Alternative 4 using Analysis Method A

(a) Calendar Year Analysis

(i) Upstream Impacts of the Proposed Program and Alternative 4

Increasing efficiency in heavy-duty vehicles would result in reduced fuel demand, and 

therefore, reductions in the emissions associated with all processes involved in getting petroleum 

to the pump. Both Method A and Method B project these impacts for fuel consumed by

vocational vehicles and combination tractor-trailers, using the same methods. See Section VIII. 

A. (2) (a)(i) for the description of this methodology. To project these impacts for fuel consumed 

by HD pickups and vans, Method A used similar calculations and inputs applicable to the CAFE 

model, as discussed above in Section VI. More information on the development of the emission 

factors used in this analysis can be found in Chapter 5 of the draft RIA. 

The following four tables summarize the projected upstream emission impacts of the 

preferred alternative and Alternative 4 on both criteria pollutants and air toxics from the heavyduty sector, relative to Alternative 1b (more dynamic baseline conditions under the No-Action 

Alternative) and Alternative 1a (less dynamic baseline conditions under the No-Action 

Alternative).

Table VIII-1 Annual Upstream Impacts on Criteria Pollutants and Air Toxics from Heavy-Duty Sector in

Calendar Years 2025, 2035 and 2050 – Preferred Alternative vs. Alt 1b using Analysis Method A a

Pollutant CY2025 CY2035 CY2050

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

1,3-Butadiene -1 -5% -3 -14% -5 -17%

Acetaldehyde -3 -3% -10 -11% -15 -13%

Acrolein 0 -4% -1 -12% -2 -15%

Benzene -21 -4% -74 -13% -104 -15%

CO -3,798 -5% -12,087 -14% -17,120 -17%

Formaldehyde -19 -5% -59 -14% -84 -17%

NOX -9,472 -5% -30,333 -14% -42,839 -17%

PM2.5 -1,019 -5% -3,257 -14% -4,609 -17%

SOX -5,983 -5% -19,190 -14% -27,074 -17%

VOC -3,066 -4% -11,029 -13% -15,386 -15%

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.
Page 556 of 850

Table VIII-2 Annual Upstream Impacts on Criteria Pollutants and Air Toxics from Heavy-Duty Sector in

Calendar Years 2025, 2035 and 2050 – Alternative 4 vs. Alt 1b using Analysis Method A a

Pollutant CY2025 CY2035 CY2050

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

1,3-Butadiene -1 -6% -3 -15% -5 -17%

Acetaldehyde -4 -5% -11 -12% -15 -14%

Acrolein -1 -5% -1 -13% -2 -15%

Benzene -28 -5% -78 -13% -105 -16%

CO -4,679 -6% -12,640 -15% -17,263 -17%

Formaldehyde -23 -6% -62 -15% -85 -17%

NOX -11,708 -6% -31,769 -15% -43,263 -17%

PM2.5 -1,259 -6% -3,408 -15% -4,649 -17%

SOX -7,402 -6% -20,107 -15% -27,356 -17%

VOC -4,081 -5% -11,717 -13% -15,645 -15%

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table VIII-3 Annual Upstream Impacts on Criteria Pollutants and Air Toxics from Heavy-Duty Sector in

Calendar Years 2025, 2035 and 2050 – Preferred Alternative vs. Alt 1a using Analysis Method A a

Pollutant CY2025 CY2035 CY2050

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

1,3-Butadiene -1 -5% -4 -15% -5 -18%

Acetaldehyde -3 -3% -11 -12% -16 -14%

Acrolein 0 -4% -1 -13% -2 -15%

Benzene -22 -4% -80 -14% -113 -16%

CO -3,911 -5% -13,153 -15% -18,794 -18%

Formaldehyde -19 -5% -65 -15% -92 -18%

NOX -9,787 -5% -33,021 -15% -47,028 -18%

PM2.5 -1,051 -5% -3,545 -15% -5,058 -18%

SOX -6,189 -5% -20,896 -15% -29,726 -18%

VOC -3,193 -4% -11,848 -13% -16,625 -16%

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.
Page 557 of 850

Table VIII-4 Annual Upstream Impacts on Criteria Pollutants and Air Toxics from Heavy-Duty Sector in

Calendar Years 2025, 2035 and 2050 – Alternative 4 vs. Alt 1a using Analysis Method A a

Pollutant CY2025 CY2035 CY2050

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

1,3-Butadiene -1 -6% -4 -16% -5 -18%

Acetaldehyde -4 -5% -12 -12% -16 -14%

Acrolein -1 -5% -1 -13% -2 -16%

Benzene -29 -5% -84 -14% -114 -17%

CO -4,816 -6% -13,720 -16% -18,945 -18%

Formaldehyde -24 -6% -67 -16% -93 -18%

NOX -12,098 -6% -34,501 -16% -47,477 -18%

PM2.5 -1,298 -6% -3,700 -16% -5,101 -18%

SOX -7,658 -6% -21,843 -16% -30,024 -18%

VOC -4,251 -5% -12,541 -14% -16,870 -16%

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

(ii) Downstream Impacts of the Proposed Program and Alternative 4

For vocational vehicles and tractor-trailers, the agencies used the MOVES model to 

determine non-GHG emissions inventories. The improvements in engine efficiency and road 

load, the increased use of APUs, and VMT rebound were included in the MOVES analysis. For 

the analysis presented in this section, the DOT CAFE model was used for HD pickups and vans. 

Further information about DOT’s CAFE model is available in Section VI.C and Chapter 10 of 

the draft RIA. The following four tables summarize the projected downstream emission impacts 

of the preferred alternative and Alternative 4 on both criteria pollutants and air toxics from the 

heavy-duty sector, relative to Alternative 1b and Alternative 1a.

Table VIII-5 Annual Downstream Impacts on Criteria Pollutants and Air Toxics from HeavyDuty Sector in Calendar Years 2025, 2035 and 2050 – Preferred Alternative vs. Alt 1b using 

Analysis Method A
Page 558 of 850

a

Pollutant CY2025 CY2035 CY2050

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

1,3-Butadiene -8 -3% -21 -12% -30 -16%

Acetaldehyde -669 -10% -1,882 -31% -2,667 -36%

Acrolein -97 -10% -272 -31% -385 -37%

Benzene -123 -6% -347 -19% -490 -24%

CO -26,485 -3% -75,199 -8% -106,756 -9%

Formaldehyde -2,100 -12% -5,910 -32% -8,376 -37%

NOX -92,444 -7% -260,949 -28% -370,663 -34%

PM2.5

b

 643 2% 1,722 8% 2,410 10%

SOX -229 -4% -715 -13% -1,026 -15%

VOC -13,161 -6% -38,051 -21% -54,139 -26%

Notes:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

b

Positive number means emissions would increase from reference to control case. PM2.5 from tire wear and brake 

wear are included. 

Table VIII-6 Annual Downstream Impacts on Criteria Pollutants and Air Toxics from Heavy-Duty Sector in

Calendar Years 2025, 2035 and 2050 – Alternative 4 vs. Alt 1b using Analysis Method A a

Pollutant CY2025 CY2035 CY2050

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

1,3-Butadiene -8 -2% -21 -12% -30 -16%

Acetaldehyde -669 -10% -1,882 -31% -2,667 -36%

Acrolein -97 -10% -271 -31% -385 -37%

Benzene -124 -6% -347 -19% -490 -24%

CO -26,705 -3% -75,407 -8% -106,874 -9%

Formaldehyde -2,100 -12% -5,908 -32% -8,375 -37%

NOX -93,984 -8% -262,150 -28% -370,704 -34%

PM2.5

b

 619 2% 1,705 8% 2,412 10%

SOX -280 -5% -742 -13% -1,029 -15%

VOC -13,925 -7% -38,472 -22% -54,150 -26%

Notes:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

b

Positive number means emissions would increase from reference to control case. PM2.5 from tire wear and brake 

wear are included. 

Table VIII-7 Annual Downstream Impacts on Criteria Pollutants and Air Toxics from HeavyDuty Sector in Calendar Years 2025, 2035 and 2050 – Preferred Alternative vs. Alt 1a using 

Analysis Method A
Page 559 of 850

a

Pollutant CY2025 CY2035 CY2050

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

1,3-Butadiene -8 -3% -21 -12% -30 -16%

Acetaldehyde -669 -10% -1,880 -31% -2,664 -36%

Acrolein -97 -10% -271 -31% -384 -37%

Benzene -123 -6% -346 -19% -490 -24%

CO -26,576 -3% -75,571 -8% -107,287 -9%

Formaldehyde -2,100 -12% -5,904 -32% -8,369 -37%

NOX -93,197 -8% -266,890 -29% -380,303 -35%

PM2.5

b

 632 2% 1,635 8% 2,267 9%

SOX -232 -4% -776 -14% -1,125 -16%

VOC -13,210 -6% -38,964 -22% -55,628 -26%

Notes:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.bPositive number means emissions would 

increase from reference to control case. PM2.5 from tire wear and brake wear are included. 

Table VIII-8 Annual Downstream Impacts on Criteria Pollutants and Air Toxics from Heavy-Duty Sector in

Calendar Years 2025, 2035 and 2050 – Alternative 4 vs. Alt 1a using Analysis Method A a

Pollutant CY2025 CY2035 CY2050

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

1,3-Butadiene -8 -2% -21 -12% -29 -16%

Acetaldehyde -668 -10% -1,880 -31% -2,664 -36%

Acrolein -97 -10% -271 -31% -384 -37%

Benzene -124 -6% -346 -19% -489 -24%

CO -26,821 -3% -75,795 -8% -107,414 -9%

Formaldehyde -2,099 -12% -5,902 -32% -8,367 -37%

NOX -94,724 -8% -268,075 -29% -380,328 -35%

PM2.5

b

 609 2% 1,618 8% 2,269 9%

SOX -282 -5% -803 -14% -1,127 -16%

VOC -13,971 -7% -39,383 -22% -55,638 -26%

Notes:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

b

Positive number means emissions would increase from reference to control case. PM2.5 from tire wear and brake 

wear are included. 

(iii) Total Impacts of the Proposed Program and Alternative 4

The following four tables summarize the projected upstream emission impacts of the 

preferred alternative and Alternative 4 on both criteria pollutants and air toxics from the heavyduty sector, relative to Alternative 1b and Alternative 1a.
Page 560 of 850

Table VIII-9 Annual Total Impacts (Upstream and Downstream) of Criteria Pollutants and Air Toxics from 

Heavy-Duty Sector in Calendar Years 2025, 2035 and 2050 – Preferred Alternative vs. Alt 1b using Analysis 

Method A a

Pollutant CY2025 CY2035 CY2050

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

1,3-Butadiene -9 -3% -25 -13% -34 -16%

Acetaldehyde -672 -10% -1,893 -30% -2,682 -36%

Acrolein -97 -10% -273 -31% -387 -37%

Benzene -145 -5% -421 -18% -595 -22%

CO -30,282 -3% -87,286 -8% -123,876 -10%

Formaldehyde -2,119 -11% -5,969 -32% -8,460 -37%

NOX -101,916 -7% -291,282 -26% -413,501 -31%

PM2.5 -376 -1% -1,535 -3% -2,199 -4%

SOX -6,213 -5% -19,905 -14% -28,101 -17%

VOC -16,227 -6% -49,080 -18% -69,525 -22%

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table VIII-10 Annual Total Impacts (Upstream and Downstream) of Criteria Pollutants and Air Toxics 

from Heavy-Duty Sector in Calendar Years 2025, 2035 and 2050 – Alternative 4 vs. Alt 1b using Analysis 

Method A a

Pollutant CY2025 CY2035 CY2050

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

1,3-Butadiene -9 -3% -25 -13% -34 -16%

Acetaldehyde -673 -10% -1,893 -30% -2,682 -36%

Acrolein -97 -10% -273 -31% -387 -37%

Benzene -152 -6% -426 -18% -595 -22%

CO -31,383 -3% -88,047 -8% -124,137 -10%

Formaldehyde -2,123 -11% -5,970 -32% -8,460 -37%

NOX -105,693 -7% -293,918 -26% -413,967 -31%

PM2.5 -639 -1% -1,703 -4% -2,237 -4%

SOX -7,682 -6% -20,849 -15% -28,385 -17%

VOC -18,006 -6% -50,189 -19% -69,796 -22%

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.
Page 561 of 850

Table VIII-11 Annual Total Impacts (Upstream and Downstream) of Criteria Pollutants and Air Toxics 

from Heavy-Duty Sector in Calendar Years 2025, 2035 and 2050 – Preferred Alternative vs. Alt 1a using 

Analysis Method A a

Pollutant CY2025 CY2035 CY2050

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

1,3-Butadiene -9 -3% -25 -13% -35 -16%

Acetaldehyde -672 -10% -1,891 -30% -2,680 -36%

Acrolein -97 -10% -273 -31% -386 -37%

Benzene -145 -5% -425 -18% -603 -22%

CO -30,487 -3% -88,724 -8% -126,081 -10%

Formaldehyde -2,119 -11% -5,969 -32% -8,461 -37%

NOX -102,983 -7% -299,911 -26% -427,332 -32%

PM2.5 -419 -1% -1,910 -4% -2,791 -5%

SOX -6,421 -5% -21,672 -15% -30,850 -18%

VOC -16,403 -6% -50,812 -19% -72,253 -23%

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table VIII-12 Annual Total Impacts (Upstream and Downstream) of Criteria Pollutants and Air Toxics 

from Heavy-Duty Sector in Calendar Years 2025, 2035 and 2050 – Alternative 4 vs. Alt 1a using Analysis 

Method A a

Pollutant CY2025 CY2035 CY2050

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

1,3-Butadiene -9 -3% -25 -13% -35 -16%

Acetaldehyde -672 -10% -1,891 -30% -2,679 -36%

Acrolein -97 -10% -273 -31% -386 -37%

Benzene -153 -6% -430 -18% -603 -22%

CO -31,637 -3% -89,514 -8% -126,360 -10%

Formaldehyde -2,123 -11% -5,969 -32% -8,460 -37%

NOX -106,822 -7% -302,575 -26% -427,805 -32%

PM2.5 -689 -1% -2,082 -5% -2,833 -5%

SOX -7,941 -6% -22,646 -16% -31,151 -18%

VOC -18,222 -6% -51,924 -19% -72,509 -23%

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.
Page 562 of 850

(b) Model Year Lifetime Analysis

Table VIII-13 Lifetime Non-GHG Reductions using Analysis Method A – Summary for Model Years 2018-

2029 (US Short Tons) a

ALTERNATIVE 3 

(PROPOSED)

ALTERNATIVE 4

NO-ACTION ALTERNATIVE 

(BASELINE)

1b (More 

Dynamic)

1a (Less 

Dynamic)

1b (More

Dynamic)

1a (Less 

Dynamic)

NOX 2,359,548 2,409,738 2,420,931 2,472,021

 Downstream 2,103,163 2,137,232 2,130,659 2,164,458

 Upstream 256,385 272,506 290,272 307,563

PM2.5 13,496 15,706 17,524 19,839

 Downstreamb-14,051 -13,546 -13,649 -13,153

 Upstream 27,547 29,252 31,173 32,992

SOX 167,415 177,948 189,670 200,992

 Downstream 5,326 5,562 6,079 6,311

 Upstream 162,089 172,386 183,591 194,681

Notes:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

b Negative number means emissions would increase from reference to control case. PM2.5 from tire wear and brake 

wear are included. 

(2) Impacts of the Proposed Rules and Alternative 4 using Analysis Method B

(a) Calendar Year Analysis

(i) Upstream Impacts of the Proposed Program and Alternative 4

Increasing efficiency in heavy-duty vehicles would result in reduced fuel demand, and 

therefore, reductions in the emissions associated with all processes involved in getting petroleum 

to the pump. To project these impacts, Method B 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. 

Method B estimated the emissions associated with production and distribution of gasoline and 

diesel from crude oil based on emission factors in the “Greenhouse Gases, Regulated Emissions, 

and Energy used in Transportation” model (GREET) developed by DOE's Argonne National 

Laboratory. In some cases, the GREET values were modified or updated by the agencies to be 

consistent with the National Emission Inventory (NEI) and emission factors from MOVES. 

Method B estimated the projected corresponding changes in upstream emissions using the same 
Page 563 of 850

tools originally created for the Renewable Fuel Standard 2 (RFS2) rulemaking analysis,419 used 

in the LD GHG rulemakings,420 HD GHG Phase 1,421 and updated for the current analysis. More 

information on the development of the emission factors used in this analysis can be found in 

Chapter 5 of the draft RIA.

Table VIII-14 and Table VIII-15 summarizes the projected upstream emission impacts of 

the Preferred Alternative and Alternative 4 on both criteria pollutants and air toxics from the 

heavy-duty sector, relative to Alternative 1a. The comparable estimates relative to Alternative 

1b are presented in Section VIII. A. (1). 

Table VIII-14 Annual Upstream Impacts on Criteria Pollutants and Air Toxics from Heavy-Duty Sector in

Calendar Years 2025, 2035 and 2050 – Preferred Alternative vs. Alt 1a using Analysis Method B a

Pollutant CY2025 CY2035 CY2050

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

1,3-Butadiene -1 -5.0% -4 -15.3% -5 -18.4%

Acetaldehyde -4 -3.0% -18 -11.9% -26 -14.6%

Acrolein -0.5 -3.4% -2 -12.7% -3 -15.5%

Benzene -24 -3.8% -92 -13.4% -132 -16.3%

CO -3,798 -4.9% -13,001 -15.3% -18,772 -18.4%

Formaldehyde -19 -4.7% -67 -14.9% -98 -18.0%

NOX -9,282 -4.9% -31,782 -15.3% -45,888 -18.4%

PM2.5 -1,020 -4.9% -3,514 -15.2% -5,072 -18.2%

SOX -5,817 -4.9% -19,902 -15.3% -28,736 -18.4%

VOC -3,283 -3.7% -12,724 -13.2% -18,214 -16.1%

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

 

419 U.S. EPA. Draft Regulatory Impact Analysis: Changes to Renewable Fuel Standard Program. Chapters 2 and 3. 

May 26, 2009. Docket ID: EPA-HQ-OAR-2009-0472-0119

420 2017 and Later Model Year Light-Duty Vehicle Greenhouse Gas Emissions and Corporate Average Fuel 

Economy Standards (77 FR 62623, October 15, 2012)

421 Greenhouse Gas Emission Standards and Fuel Efficiency Standards for Medium- and Heavy-Duty Engines and 

Vehicles (76 FR 57106, September 15, 2011)
Page 564 of 850

Table VIII-15 Annual Upstream Impacts on Criteria Pollutants and Air Toxics from Heavy-Duty Sector in

Calendar Years 2025, 2035 and 2050 – Alternative 4 vs. Alt 1a using Analysis Method B a

Pollutant CY2025 CY2035 CY2050

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

1,3-Butadiene -1 -6.1% -4 -15.9% -5 -18.4%

Acetaldehyde -6 -4.3% -20 -12.6% -26 -14.7%

Acrolein -1 -4.7% -2 -13.3% -3 -15.5%

Benzene -32 -5.0% -97 -14.0% -133 -16.3%

CO -4,661 -6.1% -13,485 -15.9% -18,812 -18.4%

Formaldehyde -24 -5.9% -70 -15.5% -97 -18.0%

NOX -11,393 -6.1% -32,965 -15.9% -45,986 -18.4%

PM2.5 -1,256 -6.0% -3,647 -15.7% -5,083 -18.3%

SOX -7,137 -6.1% -20,641 -15.9% -28,797 -18.4%

VOC -4,342 -4.9% -13,326 -13.8% -18,273 -16.1%

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

(ii) Downstream Impacts of the Proposed Program and Alternative 4

Both the proposed program and Alternative 4 would impact the downstream emissions of 

non-GHG pollutants. These pollutants include oxides of nitrogen (NOX), oxides of sulfur (SOX),

volatile organic compounds (VOC), carbon monoxide (CO), fine particulate matter (PM2.5), and 

air toxics. The agencies are expecting reductions in downstream emissions of NOX, VOC, SOX, 

CO, and air toxics. Much of these estimated net reductions are a result of the agencies’ 

anticipation of increased use of auxiliary power units (APUs) in combination tractors during 

extended idling; APUs emit these pollutants at a lower rate than on-road engines during extended 

idle operation, with the exception of PM2.5. Additional reductions in tailpipe emissions of NOX

and CO and refueling emissions of VOC would be achieved through improvements in engine 

efficiency and reduced road load (improved aerodynamics and tire rolling resistance), which 

reduces the amount of work required to travel a given distance and increases fuel economy. For 

vehicle types not affected by road load improvements, such as HD pickups and vans422, nonGHG emissions would increase very slightly due to VMT rebound. In addition, brake wear and 

tire wear emissions of PM2.5 would also increase very slightly due to VMT rebound. The 

agencies estimate that downstream emissions of SOX would be reduced, because they are 

roughly proportional to fuel consumption. Alternative 4 would have directionally similar effects 

as the preferred alternative.

 

422 HD pickups and vans are subject to gram per mile (distance) emission standards, as opposed to larger heavy-duty

vehicles which are certified to a gram per brake horsepower (work) standard. 
Page 565 of 850

For vocational vehicles and tractor-trailers, agencies used MOVES to determine nonGHG emissions impacts of the proposed rules and Alternative 4, relative to the less dynamic 

baseline (Alternative 1a). The improvements in engine efficiency and road load, the increased 

use of APUs, and VMT rebound were included in the MOVES analysis. For this analysis, 

Method B also used the MOVES model for HD pickups and vans. (Note that for the comparable 

analysis as described in Section VIII. A. (1), Method A used DOT’s CAFE model). Further 

information about the modeling using DOT’s CAFE and MOVES model is available in Section 

VII and Chapter 5 of the draft RIA. 

The downstream criteria pollutant and air toxics impacts of the Preferred Alternative and 

Alternative 4, relative to Alternative 1a, are presented in Table VIII-16 and Table VIII-17, 

respectively.

Table VIII-16 Annual Downstream Impacts on Criteria Pollutants and Air Toxics from Heavy-Duty Sector 

in Calendar Years 2025, 2035 and 2050 – Preferred Alternative vs. Alt 1a using Analysis Method B a

Pollutant CY2025 CY2035 CY2050

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

1,3-Butadiene -8 -2.6% -22 -15.1% -31 -19.6%

Acetaldehyde -670 -10.3% -1,884 -31.0% -2,671 -36.5%

Acrolein -97 -9.9% -272 -31.6% -385 -37.3%

Benzene -125 -5.9% -353 -21.0% -501 -25.7%

CO -25,824 -1.7% -72,960 -6.0% -103,887 -7.6%

Formaldehyde -2,102 -11.5% -5,911 -32.1% -8,379 -37.5%

NOX -93,220 -7.5% -267,125 -29.1% -380,721 -35.2%

PM2.5

b

 634 1.6% 1,631 7.6% 2,257 9.1%

SOX -254 -4.8% -876 -15.0% -1,264 -18.1%

VOC -13,440 -6.4% -40,148 -21.7% -57,308 -26.1%

Notes:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.b

Positive number means emissions would increase from reference to control case. PM2.5 from tire wear and brake 

wear are included. 
Page 566 of 850

Table VIII-17 Annual Downstream Impacts on Criteria Pollutants and Air Toxics from Heavy-Duty Sector 

in Calendar Years 2025, 2035 and 2050 – Alternative 4 vs. Alt 1a using Analysis Method B a

Pollutant CY2025 CY2035 CY2050

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

1,3-Butadiene -8 -2.6% -22 -15.1% -31 -19.6%

Acetaldehyde -670 -10.3% -1,884 -31.0% -2,671 -36.5%

Acrolein -97 -9.9% -272 -31.6% -385 -37.3%

Benzene -126 -5.9% -354 -21.0% -501 -25.7%

CO -25,919 -1.7% -73,041 -6.0% -103,891 -7.6%

Formaldehyde -2,101 -11.5% -5,910 -32.1% -8,378 -37.5%

NOX -94,787 -7.6% -268,373 -29.2% -380,810 -35.2%

PM2.5

b

 610 1.5% 1,611 7.5% 2,256 9.1%

SOX -313 -5.9% -909 -15.6% -1,267 -18.1%

VOC -14,310 -6.8% -40,640 -22.0% -57,348 -26.1%

Notes:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less 

dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.b

Positive number means emissions would increase from reference to control case. PM2.5 from tire wear and brake 

wear are included. 

As shown in Table VIII-16, a net increase in downstream PM2.5 emissions is expected. 

Although the improvements in engine efficiency and road load are expected to reduce tailpipe 

emissions of PM2.5, the projected increased use423 of APUs would lead to higher PM2.5 emissions

that more than offset the reductions from the tailpipe, since engines powering APUs are currently 

required to meet less stringent PM standards than on-road engines. Therefore, EPA conducted 

an evaluation of a program that would reduce the unintended consequence of increase in PM2.5

emissions from increased APU use by fitting the APU with a diesel particulate filter or having 

the APU exhaust plumbed into the vehicle’s exhaust system upstream of the particulate matter 

aftertreatment device. Such program requiring additional PM2.5 controls on APU could 

significantly reduce PM2.5 emissions, as shown in Table VIII-18 below. For additional details, 

see Section III.C.3 of the preamble. 

 

423 The projected use of APU during extended idling is presented in Table VII-3 of the preamble.
Page 567 of 850

Table VIII-18 Projected Impact on PM2.5 Emissions of Further PM2.5 Control on APUs – Preferred 

Alternative vs. Alt 1a using Analysis Method B (US Short Tons) a

CY Proposed program 

inventory without 

further PM2.5 control 

on APUs

Proposed program 

inventory with 

further PM2.5 control 

on APUs

Net impact of further 

PM2.5 control on 

APUs

2035 23,083 19,999 -3,084

2050 26,932 22,588 -4,344

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation 

of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

It is worth noting that the emission reductions shown in Table VIII-16 are not 

incremental to the emissions reductions projected in the Phase 1 rulemaking. This is because, as 

described in Sections III.D.2.a of the preamble, the agencies have revised their assumptions 

about the adoption rate of APUs. This proposal assumes that without the proposed Phase 2 

program (i.e., in the Phase 2 reference case), the APU adoption rate will be 30 percent for model 

years 2010 and later, which is the value used in the Phase 1 reference case. EPA conducted an 

analysis to estimate the combined emissions impacts of the Phase 1 and the proposed Phase 2 

programs for NOX, VOC, SOX and PM2.5 in calendar year 2050 using MOVES2014. The results 

are shown in Table VIII-19. For additional details, see Chapter 5 of the draft RIA.

Table VIII-19 Combined Phase 1 and Phase 2 Annual Downstream Impacts on Criteria Pollutants from

Heavy-Duty Sector in Calendar Year 2050 – Preferred Alternative vs. Alt 1a using Analysis Method B (US 

Short Tons) a

CY NOX VOC SOX PM2.5 

b

2050 -403,915 -69,415 -2,111 1,890

Notes:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an 

explanation of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see 

Section X.A.1.

b

Positive number reflects an increase in emissions. 

(iii) Total Impacts of the Proposed Program and Alternative 4

As shown in Table VIII-20 and Table VIII-21, agencies estimate that both the proposed 

program and Alternative 4 would result in overall net reductions of NOX, VOC, SOX, CO, PM2.5, 

and air toxics emissions. The downstream increase in PM2.5 due to APU use is expected to be 
Page 568 of 850

more than offset by reductions in PM2.5 from upstream.424 The results are shown both in changes 

in absolute tons and in percent reductions from the less dynamic reference to the alternatives for 

the heavy-duty sector. By 2050, the total impacts of the proposed program and Alternative 4 on 

criteria pollutants and air toxics are indistinguishable. 

Table VIII-20 Annual Total Impacts (Upstream and Downstream) of Criteria Pollutants and Air Toxics 

from Heavy-Duty Sector in Calendar Years 2025, 2035 and 2050 – Preferred Alternative vs. Alt 1a using 

Analysis Method B a

Pollutant CY2025 CY2035 CY2050

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

1,3-Butadiene -9 -2.7% -25 -15.1% -36 -19.4%

Acetaldehyde -674 -10.1% -1,902 -30.5% -2,697 -36.0%

Acrolein -97 -9.8% -274 -31.3% -388 -36.9%

Benzene -149 -5.4% -445 -18.8% -633 -22.9%

CO -29,622 -1.9% -85,961 -6.6% -122,659 -8.4%

Formaldehyde -2,121 -11.4% -5,978 -31.7% -8,475 -37.0%

NOX -102,502 -7.2% -298,907 -26.6% -426,610 -32.1%

PM2.5 -386 -0.6% -1,883 -4.2% -2,815 -5.4%

SOX -6,070 -4.9% -20,777 -15.3% -30,000 -18.4%

VOC -16,724 -5.6% -52,872 -18.8% -75,521 -22.7%

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

 

424 Although net reduction in PM2.5 is expected at 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. 

For further details, see Section VIII.D of this preamble and in Chapter 8 of the draft RIA.
Page 569 of 850

Table VIII-21 Annual Total Impacts (Upstream and Downstream) of Criteria Pollutants and Air Toxics 

from Heavy-Duty Sector in Calendar Years 2025, 2035 and 2050 – Alternative 4 vs. Alt 1a using Analysis 

Method B a

Pollutant CY2025 CY2035 CY2050

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

US Short 

Tons

% 

Reduction

1,3-Butadiene -9 -2.8% -26 -15.2% -36 -19.4%

Acetaldehyde -676 -10.1% -1,903 -30.6% -2,697 -36.0%

Acrolein -97 -9.8% -274 -31.3% -388 -36.9%

Benzene -157 -5.7% -450 -18.9% -634 -22.9%

CO -30,580 -1.9% -86,526 -6.6% -122,703 -8.4%

Formaldehyde -2,125 -11.4% -5,980 -31.7% -8,476 -37.0%

NOX -106,180 -7.4% -301,339 -26.8% -426,796 -32.1%

PM2.5 -646 -1.1% -2,036 -4.6% -2,827 -5.4%

SOX -7,450 -6.1% -21,550 -15.9% -30,064 -18.4%

VOC -18,652 -6.2% -53,966 -19.2% -75,621 -22.7%

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

(b) Model Year Lifetime Analysis

In addition to the annual non-GHG emissions reductions expected from the proposed 

rules and Alternative 4, the combined (downstream and upstream) non-GHG impacts for the 

lifetime of the impacted vehicles were estimated. Table VIII-22 shows the fleet-wide reductions 

of NOX, PM2.5 and SOX from the preferred alternative and Alternative 4, relative to Alternative 

1a, through the lifetime425 of heavy-duty vehicles. For the lifetime non-GHG reductions by 

vehicle categories, see Chapter 5 of the draft RIA.

 

425 A lifetime of 30 years is assumed in MOVES.
Page 570 of 850

Table VIII-22 Lifetime Non-GHG Reductions using Analysis Method B – Summary for Model Years 2018-

2029 (US Short Tons) a

ALTERNATIVE 3 

(PROPOSED)

ALTERNATIVE 4

NO-ACTION ALTERNATIVE 

(BASELINE)

1a (Less Dynamic) 1a (Less Dynamic)

NOX 2,399,990 2,459,497

 Downstream 2,139,331 2,167,512

 Upstream 260,659 291,986

PM2.5 15,206 19,151

 Downstreamb-13,528 -13,089

 Upstream 28,733 32,240

SOX 169,436 189,904

 Downstream 6,158 7,035

 Upstream 163,278 182,869

Notes:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

b Negative number means emissions would increase from reference to control case. PM2.5 from tire wear and brake 

wear are included. 

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 proposed and alternative heavy-duty vehicle standards. 

(1) Particulate Matter

(a) Background

Particulate matter is a highly complex mixture of solid particles and liquid droplets 

distributed among numerous atmospheric gases which interact with solid and liquid phases. 

Particles range in size from those smaller than 1 nanometer (10-9 meter) to over 100 micrometer 

(μm, or 10-6 meter) in diameter (for reference, a typical strand of human hair is 70 μm in 

diameter and a grain of salt is about 100 μm). Atmospheric particles can be grouped into several 

classes according to their aerodynamic and physical sizes. Generally, the three broad classes of 

particles considered by EPA include ultrafine particles (UFP, aerodynamic diameter <0.1 μm), 

“fine” particles (PM2.5; particles with a nominal mean aerodynamic diameter less than or equal to 

2.5 μm), and “thoracic” particles (PM10; particles with a nominal mean aerodynamic diameter 

less than or equal to 10 μm).426 Particles that fall within the size range between PM2.5 and PM10, 

are referred to as “thoracic coarse particles” (PM10-2.5, particles with a nominal mean 

 

426 U.S. EPA. (2009). Integrated Science Assessment for Particulate Matter (Final Report). U.S. Environmental 

Protection Agency, Washington, DC, EPA/600/R-08/139F. Figure 3-1.
Page 571 of 850

aerodynamic diameter less than or equal to 10 μm and greater than 2.5 μm). EPA currently has 

standards that regulate PM2.5 and PM10.

427

 

Particles span many sizes and shapes and may consist of hundreds of different chemicals. 

Particles are emitted directly from sources and are also formed through atmospheric chemical 

reactions; the former are often referred to as “primary” particles, and the latter as “secondary” 

particles. Particle concentration and composition varies by time of year and location, and in 

addition to differences in source emissions, is affected by several weather-related factors, such as 

temperature, clouds, humidity, and wind. A further layer of complexity comes from particles’ 

ability to shift between solid/liquid and gaseous phases, which is influenced by concentration and 

meteorology, especially temperature. 

Fine particles are produced primarily by combustion processes and by transformations of 

gaseous emissions (e.g., sulfur oxides (SOX), oxides of nitrogen, and volatile organic compounds 

(VOC)) in the atmosphere. The chemical and physical properties of PM2.5 may vary greatly with 

time, region, meteorology, and source category. Thus, PM2.5 may include a complex mixture of 

different components 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 broad range of health effects. 

These health effects are discussed in detail in the December 2009 Integrated Science Assessment 

for Particulate Matter (PM ISA).428 The PM ISA summarizes health effects evidence associated 

with both short- and long-term exposures to PM2.5, PM10-2.5, and ultrafine particles. The PM ISA 

concludes that human exposures to ambient PM2.5 concentrations are associated with a number 

of adverse health effects and characterizes the weight of evidence for these health outcomes.429 

The discussion below highlights the PM ISA’s conclusions pertaining to health effects associated 

with both short- and long-term PM exposures. Further discussion of health effects associated 

 

427 Regulatory definitions of PM size fractions, and information on reference and equivalent methods for measuring 

PM in ambient air, are provided in 40 CFR Parts 50, 53, and 58. With regard to national ambient air quality 

standards (NAAQS) which provide protection against health and welfare effects, the 24-hour PM10 standard 

provides protection against effects associated with short-term exposure to thoracic coarse particles (i.e., PM10-2.5).

428 U.S. EPA. (2009). Integrated Science Assessment for Particulate Matter (Final Report). U.S. Environmental 

Protection Agency, Washington, DC, EPA/600/R-08/139F. 

429 The causal framework draws upon the assessment and integration of evidence from across epidemiological, 

controlled human exposure, and toxicological studies, and the related uncertainties that ultimately influence our 

understanding of the evidence. This framework employs a five-level hierarchy that classifies the overall weight of 

evidence and causality using the following categorizations: causal relationship, likely to be causal relationship, 

suggestive of a causal relationship, inadequate to infer a causal relationship, and not likely to be a causal relationship 

(U.S. EPA. (2009). Integrated Science Assessment for Particulate Matter (Final Report). U.S. Environmental 

Protection Agency, Washington, DC, EPA/600/R-08/139F, Table 1–3). 
Page 572 of 850

with PM2.5 can also be found in the rulemaking documents for the most recent review of the PM 

NAAQS completed in 2012.430,431

EPA has concluded that a causal relationship exists between both long- and short-term 

exposures to PM2.5 and premature mortality and cardiovascular effects and a likely causal 

relationship exists between long- and short-term PM2.5 exposures and respiratory effects. 

Further, there is evidence suggestive of a causal relationship between long-term PM2.5 exposures 

and other health effects, including developmental and reproductive effects (e.g., low birth 

weight, infant mortality) and carcinogenic, mutagenic, and genotoxic effects (e.g., lung cancer 

mortality).432

As summarized in the Final PM NAAQS rule, and discussed extensively in the 2009 PM 

ISA, the available scientific evidence significantly strengthens the link between long- and shortterm exposure to PM2.5 and premature mortality, while providing indications that the magnitude 

of the PM2.5- mortality association with long-term exposures may be larger than previously

estimated. 433,434 The strongest evidence comes from recent studies investigating long-term 

exposure to PM2.5 and cardiovascular-related mortality. The evidence supporting a causal 

relationship between long-term PM2.5 exposure and mortality also includes consideration of new 

studies that demonstrated an improvement in community health following reductions in ambient 

fine particles.

Several studies evaluated in the 2009 PM ISA have examined the association between 

cardiovascular effects and long-term PM2.5 exposures in multi-city epidemiological studies 

conducted in the U.S. and Europe. These studies have provided new evidence linking long-term 

exposure to PM2.5 with an array of cardiovascular effects such as heart attacks, congestive heart 

failure, stroke, and mortality. This evidence is coherent with studies of effects associated with 

short-term exposure to PM2.5 that have observed associations with a continuum of effects ranging 

from subtle changes in indicators of cardiovascular health to serious clinical events, such as 

increased hospitalizations and emergency department visits due to cardiovascular disease and 

cardiovascular mortality.

435

As detailed in the 2009 PM ISA, extended analyses of seminal epidemiological studies,

as well as more recent epidemiological studies conducted in the U.S. and abroad, provide strong 

evidence of respiratory-related morbidity effects associated with long-term PM2.5 exposure. The 

strongest evidence for respiratory-related effects is from studies that evaluated decrements in 

 

430 78 FR 3086 (January 15, 2013), pages 3103-3104.

431 77 FR 38890 (June 29, 2012), pages 38906-38911.

432 These causal inferences are based not only on the more expansive epidemiological evidence available in this 

review but also reflect consideration of important progress that has been made to advance our understanding of a 

number of potential biologic modes of action or pathways for PM-related cardiovascular and respiratory effects 

(U.S. EPA. (2009). Integrated Science Assessment for Particulate Matter (Final Report). U.S. Environmental 

Protection Agency, Washington, DC, EPA/600/R-08/139F, Chapter 5).

433 78 FR 3103-3104 (January 15, 2013). 

434 U.S. EPA. (2009). Integrated Science Assessment for Particulate Matter (Final Report). U.S. Environmental 

Protection Agency, Washington, DC, EPA/600/R-08/139F, Chapter 6 (Section 6.5) and Chapter 7 (Section 7.6).

435 U.S. EPA. (2009). Integrated Science Assessment for Particulate Matter (Final Report). U.S. Environmental 

Protection Agency, Washington, DC, EPA/600/R-08/139F, Chapter 2 (Section 2.3.1 and 2.3.2) and Chapter 6.
Page 573 of 850

lung function growth (in children), increased respiratory symptoms, and asthma development. 

The strongest evidence from short-term PM2.5 exposure studies has been observed for increased 

respiratory-related emergency department visits and hospital admissions for chronic obstructive 

pulmonary disease (COPD) and respiratory infections.436

The body of scientific evidence detailed in the 2009 PM ISA is still limited with respect 

to associations between long-term PM2.5 exposures and developmental and reproductive effects 

as well as cancer, mutagenic, and genotoxic effects. The strongest evidence for an association 

between PM2.5 and developmental and reproductive effects comes from epidemiological studies 

of low birth weight and infant mortality, especially due to respiratory causes during the postneonatal period (i.e., 1 month to 12 months of age). 437

 With regard to cancer effects, 

‘‘[m]ultiple epidemiologic studies have shown a consistent positive association between PM2.5

and lung cancer mortality, but studies have generally not reported associations between PM2.5

and lung cancer incidence.’’438

Specific groups within the general population are at increased risk for experiencing 

adverse health effects related to PM exposures.439,440,441, 442 The evidence detailed in the 2009 

PM ISA expands our understanding of previously identified at-risk populations and lifestages 

(i.e., children, older adults, and individuals with pre-existing heart and lung disease) and supports 

the identification of additional at-risk populations (e.g., persons with lower socioeconomic 

status, genetic differences). Additionally, there is emerging, though still limited, evidence for 

additional potentially at-risk populations and lifestages, such as those with diabetes, people who 

are obese, pregnant women, and the developing fetus. 443

For PM10-2.5, the 2009 PM ISA concluded that available evidence was suggestive of a 

causal relationship between short-term exposures to PM10-2.5 and cardiovascular effects (e.g., 

hospital admissions and ED visits, changes in cardiovascular function), respiratory effects (e.g., 

ED visits and hospital admissions, increase in markers of pulmonary inflammation), and 

premature mortality. Data were inadequate to draw conclusions regarding the relationships 

between long-term exposure to PM10-2.5 and various health effects. 444,445,446

 

436

 U.S. EPA. (2009). Integrated Science Assessment for Particulate Matter (Final Report). U.S. Environmental 

Protection Agency, Washington, DC, EPA/600/R-08/139F, Chapter 2 (Section 2.3.1 and 2.3.2) and Chapter 6.

437 U.S. EPA. (2009). Integrated Science Assessment for Particulate Matter (Final Report). U.S. Environmental 

Protection Agency, Washington, DC, EPA/600/R-08/139F, Chapter 2 (Section 2.3.1 and 2.3.2) and Chapter 7.

438 U.S. EPA. (2009). Integrated Science Assessment for Particulate Matter (Final Report). U.S. Environmental 

Protection Agency, Washington, DC, EPA/600/R-08/139F. pg 2-13

439 U.S. EPA. (2009). Integrated Science Assessment for Particulate Matter (Final Report). U.S. Environmental 

Protection Agency, Washington, DC, EPA/600/R-08/139F. Chapter 8 and Chapter 2.

440 77 FR 38890 (June 29, 2012).

441 78 FR 3104 (January 15, 2013).

442 U.S. EPA. (2011). Policy Assessment for the Review of the PM NAAQS. U.S. Environmental Protection 

Agency, Washington, DC, EPA/452/R-11-003. Section 2.2.1.

443 U.S. EPA. (2009). Integrated Science Assessment for Particulate Matter (Final Report). U.S. Environmental 

Protection Agency, Washington, DC, EPA/600/R-08/139F. Chapter 8 and Chapter 2 (Section 2.4.1).

444 U.S. EPA. (2009). Integrated Science Assessment for Particulate Matter (Final Report). U.S. Environmental 

Protection Agency, Washington, DC, EPA/600/R-08/139F. Section 2.3.4 and Table 2-6.

445 78 FR 3167-8 (January 15, 2013).
Page 574 of 850

For ultrafine particles, the 2009 PM ISA concluded that the evidence was suggestive of a 

causal relationship between short-term exposures and cardiovascular effects, including changes 

in heart rhythm and vasomotor function (the ability of blood vessels to expand and contract). It 

also concluded that there was evidence suggestive of a causal relationship between short-term 

exposure to ultrafine particles and respiratory effects, including lung function and pulmonary

inflammation, with limited and inconsistent evidence for increases in ED visits and hospital 

admissions. Data were inadequate to draw conclusions regarding the relationship between shortterm exposure to ultrafine particle and additional health effects including premature mortality as 

well as long-term exposure to ultrafine particles and all health outcomes evaluated.447,448

(2) Ozone 

(a) Background

Ground-level ozone pollution is typically formed through reactions involving 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 and its 

precursors 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

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

ambient concentrations of ozone.449 The information in this section is based on the information 

and conclusions in the February 2013 Integrated Science Assessment for Ozone (Ozone ISA).450 

The Ozone ISA concludes that human exposures to ambient concentrations of ozone are 

associated with a number of adverse health effects and characterizes the weight of evidence for 

 

446 77 FR 38947-51 (June 29, 2012).

447 U.S. EPA. (2009). Integrated Science Assessment for Particulate Matter (Final Report). U.S. Environmental 

Protection Agency, Washington, DC, EPA/600/R-08/139F. Section 2.3.5 and Table 2-6.

448 78 FR 3121 (January 15, 2013).

449 Human exposure to ozone varies over time due to changes in ambient ozone concentration and because people 

move between locations which have notable different ozone concentrations. Also, the amount of ozone delivered to 

the lung is not only influenced by the ambient concentrations but also by the individuals breathing route and rate.

450 U.S. EPA. Integrated Science Assessment of Ozone and Related Photochemical Oxidants (Final Report). U.S. 

Environmental Protection Agency, Washington, DC, EPA/600/R-10/076F, 2013. The ISA is available at 

http://cfpub.epa.gov/ncea/isa/recordisplay.cfm?deid=247492#Download
Page 575 of 850

these health effects. 451 The discussion below highlights the Ozone ISA’s conclusions pertaining 

to health effects associated with both short-term and long-term periods of exposure to ozone.

For short-term exposure to ozone, the Ozone ISA concludes that respiratory effects, 

including lung function decrements, pulmonary inflammation, exacerbation of asthma, 

respiratory-related hospital admissions, and mortality, are causally associated with ozone 

exposure. It also concludes that cardiovascular effects, including decreased cardiac function and 

increased vascular disease, and total mortality are likely to be causally associated with short-term 

exposure to ozone and that evidence is suggestive of a causal relationship between central 

nervous system effects and short-term exposure to ozone. 

For long-term exposure to ozone, the Ozone ISA concludes that respiratory effects, 

including new onset asthma, pulmonary inflammation and injury, are likely to be causally related 

with ozone exposure. The Ozone ISA characterizes the evidence as suggestive of a causal 

relationship for associations between long-term ozone exposure and cardiovascular effects, 

reproductive and developmental effects, central nervous system effects and total mortality. The 

evidence is inadequate to infer a causal relationship between chronic ozone exposure and 

increased risk of lung cancer.

Finally, interindividual variation in human responses to ozone exposure can result in 

some groups being at increased risk for detrimental effects in response to exposure. The Ozone 

ISA identified several groups that are at increased risk for ozone-related health effects. These 

groups are people with asthma, children and older adults, individuals with reduced intake of 

certain nutrients (i.e., Vitamins C and E), outdoor workers, and individuals having certain 

genetic variants related to oxidative metabolism or inflammation. Ozone exposure during 

childhood can have lasting effects through adulthood. Such effects include altered function of 

the respiratory and immune systems. Children absorb higher doses (normalized to lung surface 

area) of ambient ozone, compared to adults, due to their increased time spent outdoors, higher 

ventilation rates relative to body size, and a tendency to breathe a greater fraction of air through 

the mouth. Children also have a higher asthma prevalence compared to adults. Additional 

children’s vulnerability and susceptibility factors are listed in Section XIV.

(3) Nitrogen 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. NO2 and its gas phase oxidation products can dissolve in water droplets and further 

oxidize to form nitric acid which reacts with ammonia to form nitrates, which are important 

 

451 The ISA evaluates evidence and draws conclusions on the causal relationship between relevant pollutant 

exposures and 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 more information on these levels of evidence, please refer to Table II in the 

Preamble of the ISA. 
Page 576 of 850

components of ambient PM. The health effects of ambient PM are discussed in Section 

VIII.B.1.b of this preamble. NOX and VOC are the two major precursors of ozone. The health 

effects of ozone are covered in Section VIII.B.2.b.

(b) Health Effects of Nitrogen Oxides

The most recent review of the health effects of oxides of nitrogen completed by EPA can 

be found in the 2008 Integrated Science Assessment for Oxides of Nitrogen - Health Criteria 

(Oxides of Nitrogen ISA).

452 EPA concluded that the findings of epidemiological, controlled 

human exposure, and animal toxicological studies provided evidence that was sufficient to infer 

a likely causal relationship between respiratory effects and short-term NO2 exposure. The 2008 

ISA for Oxides of Nitrogen concluded that the strongest evidence for such a relationship comes 

from epidemiological studies of respiratory effects including increased respiratory symptoms, 

emergency department visits, and hospital admissions. Based on both short- and long-term 

exposure studies, the 2008 ISA for Oxides of Nitrogen concluded that individuals with 

preexisting pulmonary conditions (e.g., asthma or COPD), children, and older adults are 

potentially at greater risk of NO2-related respiratory effects. Based on findings from controlled 

human exposure studies, the 2008 ISA for Oxides of Nitrogen also drew two broad conclusions 

regarding airway responsiveness following NO2 exposure. First, the ISA concluded 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 

asthmatic adults to NO2 concentrations as low as 260 ppb.

453

 Second, exposure to NO2 was 

found to enhance the inherent responsiveness of the airway to subsequent nonspecific challenges 

in controlled human exposure studies of healthy and asthmatic adults. Statistically significant 

increases in nonspecific airway responsiveness were reported for asthmatic adults following 30-

minute exposures to 200-300 ppb NO2 and following 1-hour exposures to 100 ppb NO2.

454

 

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 epidemiological and experimental 

data sets formed 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 admissions and emergency department visits for respiratory causes, 

especially asthma.

455

 

In evaluating a broader range of health effects, the 2008 ISA for Oxides of Nitrogen

concluded evidence was “suggestive but not sufficient to infer a causal relationship” between 

 

452 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. 

453 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, Section 3.1.3.1.

454 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, Section 3.1.3.2.

455 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, Section 3.1.7.
Page 577 of 850

short-term NO2 exposure and premature mortality and between long-term NO2 exposure and 

respiratory effects. The latter was based largely on associations observed between long-term 

NO2 exposure and decreases in lung function growth in children. Furthermore, the 2008 ISA for 

Oxides of Nitrogen concluded that evidence was “inadequate to infer the presence or absence of 

a causal relationship” between short-term NO2 exposure and cardiovascular effects as well as 

between long-term NO2 exposure and cardiovascular effects, reproductive and developmental 

effects, premature mortality, and cancer.456 The conclusions for these health effect categories 

were informed by uncertainties in the evidence base such as the independent effects of NO2

exposure within the broader mixture of traffic-related pollutants, limited evidence from 

experimental studies, and/or an overall limited literature base.

(4) Sulfur Oxides

(a) Background

Sulfur dioxide (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 its gas phase oxidation products can dissolve in water 

droplets and further oxidize to form sulfuric acid which reacts with ammonia to form sulfates, 

which are important components of ambient PM. The health effects of ambient PM are 

discussed in Section VIII.B.1.b of this preamble. 

(b) Health Effects of SO2

Information on the health effects of SO2 can be found in the 2008 Integrated Science 

Assessment for Sulfur Oxides – Health Criteria (SOX ISA).

457

 Short-term peaks of SO2 have

long been known to cause adverse respiratory health effects, particularly among individuals with 

asthma. In addition to those with asthma (both children and adults), potentially sensitive groups 

include all 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, EPA 

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, EPA concluded that the overall 

evidence is suggestive of a causal relationship between short-term exposure to SO2 and 

mortality. Additional information on the health effects of SO2 is available in Chapter 6.1.1.4.2 

of the RIA.

 

456 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.

457 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.
Page 578 of 850

(5) Carbon Monoxide 

(a) Background

Carbon monoxide (CO) is a colorless, odorless gas emitted from combustion processes. 

Nationally and, particularly in urban areas, the majority of CO emissions to ambient air come 

from mobile sources.

(b) Health Effects of Carbon Monoxide

Information on the health effects of CO can be found in the January 2010 Integrated 

Science Assessment for Carbon Monoxide (CO ISA).

458

 The CO ISA concludes that ambient 

concentrations of CO are associated with a number of adverse health effects.459 This section 

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

CO.460 

Controlled human exposure 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 CO 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 central nervous system and behavioral effects following low-level 

CO exposures, although the findings have not been consistent across all studies. The CO ISA 

concludes the evidence is suggestive of a causal relationship with both short- and long-term 

exposure to CO and central nervous system effects.

 

458 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. 

459 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. 

460 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.
Page 579 of 850

A number of studies cited in the CO ISA have evaluated the role of CO exposure in birth 

outcomes such as preterm birth or cardiac birth defects. The epidemiologic studies provide 

limited evidence of a CO-induced effect on preterm births and birth defects, with weak evidence 

for a decrease in birth weight. Animal toxicological studies have found perinatal CO exposure to 

affect birth weight, as well as other developmental outcomes. The CO ISA concludes the

evidence is suggestive of a causal relationship between long-term exposures to CO and 

developmental effects and birth outcomes.

Epidemiologic studies provide evidence of associations between ambient CO 

concentrations and respiratory morbidity such as changes in pulmonary function, respiratory

symptoms, and hospital admissions. 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 CO ISA concludes that the evidence 

is suggestive of a causal relationship between short-term CO exposure and respiratory morbidity, 

and inadequate to conclude that a causal relationship exists between long-term exposure and 

respiratory morbidity. 

Finally, the CO ISA concludes that the epidemiologic evidence is suggestive of a causal 

relationship between short-term concentrations of 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 CO ISA also concludes that there is not likely to be a causal 

relationship between relevant long-term exposures to CO and mortality.

(6) Diesel Exhaust

(a) Background

Diesel exhaust consists of 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), of which

a significant fraction is 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, 
Page 580 of 850

decelerate), and fuel formulations (high/low sulfur fuel). Also, there are emissions differences 

between on-road and nonroad engines because the nonroad engines are generally of older 

technology. After being emitted in the engine exhaust, diesel exhaust undergoes dilution as well 

as chemical and physical changes in the atmosphere. The lifetime for some of the compounds 

present in diesel exhaust ranges from hours to days.

(b) Health Effects of Diesel Exhaust

In EPA’s 2002 Diesel Health Assessment Document (Diesel HAD), 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.461,462 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) had made similar hazard classifications 

prior to 2002. EPA also concluded in the 2002 Diesel HAD that it was not possible to calculate a 

cancer unit risk for diesel exhaust due to limitations in the exposure data for the occupational 

groups or the absence of a dose-response relationship. 

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 range of 

possible lung cancer risk. The outcome was that environmental risks of cancer from long-term 

diesel exhaust exposures could plausibly range from as low as 10-5to as high as 10-3. Because of 

uncertainties, the analysis acknowledged that the risks could be lower than 10-5, and a zero risk 

from diesel exhaust exposure could not be ruled out.

Non-cancer health effects of acute and chronic exposure to diesel exhaust emissions are 

also of concern to EPA. EPA derived a diesel exhaust reference concentration (RfC) from 

consideration of four well-conducted chronic rat inhalation studies showing adverse pulmonary

effects. The RfC is 5 μg/m3for diesel exhaust measured as diesel particulate matter. This RfC 

does not consider allergenic effects such as those associated with asthma or immunologic or the 

potential for cardiac effects. There was emerging evidence in 2002, discussed in the Diesel 

HAD, that exposure to diesel exhaust can exacerbate these effects, but the exposure-response 

data were lacking at that time to derive an RfC based on these then emerging considerations. 

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.” The Diesel HAD also notes “that acute exposure to [diesel exhaust] has been 

associated with irritation of the eye, nose, and throat, respiratory symptoms (cough and phlegm), 

 

461 U.S. EPA. (1999). Guidelines for Carcinogen Risk Assessment. Review Draft. NCEA-F-0644, July. Washington, 

DC: U.S. EPA. Retrieved on March 19, 2009 from http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=54932. 

462 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. pp. 1-1 1-2. 
Page 581 of 850

and neurophysiological symptoms such as headache, lightheadedness, nausea, vomiting, and 

numbness or tingling of the extremities.” The Diesel HAD noted that the cancer and noncancer 

hazard conclusions applied to the general use of diesel engines then on the market and as cleaner 

engines replace a substantial number of existing ones, the applicability of the conclusions would 

need to be reevaluated. 

It is important to note that the Diesel HAD also briefly summarizes health effects 

associated with ambient PM and discusses EPA’s then-annual PM2.5 NAAQS of 15 μg/m3. In

2012, EPA revised the annual PM2.5 NAAQS to 12 μg/m3. There is a large and 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 health effects and premature mortality

attributed to exposure to PM2.5. The contribution of diesel PM to total ambient PM varies in 

different regions of the country and also, within a region, from one area to another. The 

contribution can be high in near-roadway environments, for example, or in other locations where 

diesel engine use is concentrated. 

Since 2002, several new studies have been published which continue to report increased 

lung cancer risk with occupational exposure to diesel exhaust from older engines. Of particular 

note since 2011 are three new epidemiology studies which have examined lung cancer in 

occupational populations, for example, truck drivers, underground nonmetal miners and other 

diesel motor related occupations. These studies reported increased risk of lung cancer with 

exposure to diesel exhaust with evidence of positive exposure-response relationships to varying 

degrees.463,464,465 These newer studies (along with others that have appeared in the scientific 

literature) add to the evidence EPA evaluated in the 2002 Diesel HAD and further reinforces the

concern that diesel exhaust exposure likely poses a lung cancer hazard. The findings from these 

newer studies do not necessarily apply to newer technology diesel engines since the newer 

engines have large reductions in the emission constituents compared to older technology diesel 

engines. 

In light of the growing body of scientific literature evaluating the health effects of 

exposure to diesel exhaust, in June 2012 the World Health Organization’s International Agency

for Research on Cancer (IARC), a recognized international authority on the carcinogenic 

potential of chemicals and other agents, evaluated the full range of cancer related health effects 

data for diesel engine exhaust. IARC concluded that diesel exhaust should be regarded as 

 

463 Garshick, Eric, Francine Laden, Jaime E. Hart, Mary E. Davis, Ellen A. Eisen, and Thomas J. Smith. 2012. Lung 

cancer and elemental carbon exposure in trucking industry workers. Environmental Health Perspectives 120(9): 

1301-1306.

464 Silverman, D. T., Samanic, C. M., Lubin, J. H., Blair, A. E., Stewart, P. A., Vermeulen, R., & Attfield, M. D. 

(2012). The diesel exhaust in miners study: a nested case–control study of lung cancer and diesel exhaust. Journal of 

the National Cancer Institute.

465 Olsson, Ann C., et al. "Exposure to diesel motor exhaust and lung cancer risk in a pooled analysis from casecontrol studies in Europe and Canada." American journal of respiratory and critical care medicine 183.7 (2011): 

941-948.
Page 582 of 850

“carcinogenic to humans.”466 This designation was an update from its 1988 evaluation that 

considered the evidence to be indicative of a “probable human carcinogen.” 

(7) Air Toxics

(a) Background

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.”467 These compounds 

include, but are not limited to, benzene, 1, 3-butadiene, formaldehyde, acetaldehyde, acrolein, 

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.468

(b) Benzene

EPA’s Integrated Risk Information System (IRIS) database lists benzene as a known 

human carcinogen (causing leukemia) by all routes of exposure, and concludes that exposure is 

associated with additional health effects, including genetic changes in both humans and animals 

and increased proliferation of bone marrow cells in mice.469,470,471 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 nonlymphocytic leukemia and chronic lymphocytic leukemia. EPA’s IRIS documentation for 

benzene also lists a range of 2.2 x 10-6to 7.8 x 10-6as the unit risk estimate (URE) for 

benzene.472,473 The International Agency for Research on Carcinogens (IARC) has determined 

 

466 IARC [International Agency for Research on Cancer]. (2013). Diesel and gasoline engine exhausts and some 

nitroarenes. IARC Monographs Volume 105. [Online at 

http://monographs.iarc.fr/ENG/Monographs/vol105/index.php]

467 U.S. EPA. (2011) Summary of Results for the 2005 National-Scale Assessment. 

www.epa.gov/ttn/atw/nata2005/05pdf/sum_results.pdf. 

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

469 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. 

470 International Agency for Research on Cancer, IARC monographs on the evaluation of carcinogenic risk of 

chemicals to humans, Volume 29, some industrial chemicals and dyestuffs, International Agency for Research on 

Cancer, World Health Organization, Lyon, France 1982. 

471 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 colony-stimulating factor 

in vitro, Proc. Natl. Acad. Sci. 89:3691-3695. 

472 A unit risk estimate is defined as the increase in the lifetime risk of an individual who is exposed for a lifetime to 

1 μg/m3 benzene in air.

473 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. 
Page 583 of 850

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.474,475 

A number of adverse noncancer health effects including blood disorders, such as pre 

leukemia and aplastic anemia, have also been associated with long-term exposure to 

benzene.476,477 The most sensitive noncancer effect observed in humans, based on current data, 

is the depression of the absolute lymphocyte count in blood.478,479 EPA’s inhalation reference 

concentration (RfC) for benzene is 30 μg/m3. The RfC is based on suppressed absolute 

lymphocyte counts seen in humans under occupational exposure conditions. In addition, recent 

work, including studies sponsored by the Health Effects Institute, provides evidence that 

biochemical responses are occurring at lower levels of benzene exposure than previously 

known.480,481,482,483 EPA’s IRIS program has not yet evaluated these new data. EPA does not 

currently have an acute reference concentration for benzene. The Agency for Toxic Substances 

and Disease Registry (ATSDR) Minimal Risk Level (MRL) for acute exposure to benzene is 29 

μg/m3for 1-14 days exposure.484,485

 

474 International Agency for Research on Cancer (IARC). (1987). Monographs on the evaluation of carcinogenic 

risk of chemicals to humans, Volume 29, Supplement 7, Some industrial chemicals and dyestuffs, World Health 

Organization, Lyon, France.

475 NTP. (2014). 13th Report on Carcinogens. Research Triangle Park, NC: U.S. Department of Health and Human 

Services, Public Health Service, National Toxicology Program.

476 Aksoy, M. (1989). Hematotoxicity and carcinogenicity of benzene. Environ. Health Perspect. 82: 193-197. 

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

478 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. 

479 U.S. EPA. (2002). Toxicological Review of Benzene (Noncancer Effects). Environmental Protection Agency, 

Integrated Risk Information System (IRIS), Research and Development, National Center for Environmental 

Assessment, Washington DC. This material is available electronically at http://www.epa.gov/iris/subst/0276.htm. 

480 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.

481 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. 

482 Lan, Qing, Zhang, L., Li, G., Vermeulen, R., et al. (2004). Hematotoxically in Workers Exposed to Low Levels 

of Benzene. Science 306: 1774-1776.

483 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. 

484 U.S. Agency for Toxic Substances and Disease Registry (ATSDR). (2007). Toxicological profile for benzene. 

Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service. 

http://www.atsdr.cdc.gov/ToxProfiles/tp3.pdf.

485 A minimal risk level (MRL) is defined as an estimate of the daily human exposure to a hazardous substance that 

is likely to be without appreciable risk of adverse noncancer health effects over a specified duration of exposure.
Page 584 of 850

(c) 1,3-Butadiene

EPA has characterized 1,3-butadiene as carcinogenic to humans by inhalation.486,487 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.488,489,490 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. The URE for 1,3-butadiene is 3 × 10-5per μg/m3.

491

 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.492 Based on this critical effect and the benchmark concentration methodology, an 

RfC for chronic health effects was calculated at 0.9 ppb (approximately 2 μg/m3).

(d) Formaldehyde

In 1991, EPA concluded that formaldehyde is a carcinogen based on nasal tumors in 

animal bioassays.493 An Inhalation URE for cancer and a Reference Dose for oral noncancer 

effects were developed by the agency and posted on the IRIS database. Since that time, the 

 

486 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. 

487 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. 

488 International Agency for Research on Cancer (IARC). (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. 

489 International Agency for Research on Cancer (IARC). (2008). Monographs on the evaluation of carcinogenic risk 

of chemicals to humans, 1,3-Butadiene, Ethylene Oxide and Vinyl Halides (Vinyl Fluoride, Vinyl Chloride and 

Vinyl Bromide) Volume 97, World Health Organization, Lyon, France. 

490 NTP. (2014). 13th Report on Carcinogens. Research Triangle Park, NC: U.S. Department of Health and Human 

Services, Public Health Service, National Toxicology Program.

491 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. 

492 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.

493 EPA. Integrated Risk Information System. Formaldehyde (CASRN 50-00-0) 

http://www.epa.gov/iris/subst/0419/htm
Page 585 of 850

National Toxicology Program (NTP) and International Agency for Research on Cancer (IARC) 

have concluded that formaldehyde is a known human carcinogen.494,495

The conclusions by IARC and NTP reflect the results of epidemiologic research 

published since 1991 in combination with previous animal, human and mechanistic evidence. 

Research conducted by the National Cancer Institute reported an increased risk of 

nasopharyngeal cancer and specific lymph hematopoietic malignancies among workers exposed 

to formaldehyde.496,497,498 A National Institute of Occupational Safety and Health study of 

garment workers also reported increased risk of death due to leukemia among workers exposed 

to formaldehyde.499 Extended follow-up of a cohort of British chemical workers did not report 

evidence of an increase in nasopharyngeal or lymph hematopoietic cancers, but a continuing 

statistically significant excess in lung cancers was reported.500 Finally, a study of embalmers 

reported formaldehyde exposures to be associated with an increased risk of myeloid leukemia 

but not brain cancer.501

Health effects of formaldehyde in addition to cancer were reviewed by the Agency for 

Toxics Substances and Disease Registry in 1999502 and supplemented in 2010,503 and by the 

World Health Organization.504 These organizations reviewed the scientific literature concerning 

health effects linked to formaldehyde exposure to evaluate hazards and dose response 

relationships and defined exposure concentrations for minimal risk levels (MRLs). The health 

endpoints reviewed included sensory irritation of eyes and respiratory tract, pulmonary function, 

nasal histopathology, and immune system effects. In addition, research on reproductive and 

developmental effects and neurological effects were discussed along with several studies that 

suggest that formaldehyde may increase the risk of asthma – particularly in the young.

 

494 NTP. (2014). 13th Report on Carcinogens. Research Triangle Park, NC: U.S. Department of Health and Human 

Services, Public Health Service, National Toxicology Program.

495 IARC Monographs on the Evaluation of Carcinogenic Risks to Humans Volume 100F (2012): Formaldehyde

496 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. 

497 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. 

498 Beane Freeman, L. E.; Blair, A.; Lubin, J. H.; Stewart, P. A.; Hayes, R. B.; Hoover, R. N.; Hauptmann, M. 2009. 

Mortality from lymph hematopoietic malignancies among workers in formaldehyde industries: The National Cancer 

Institute cohort. J. National Cancer Inst. 101: 751-761. 

499 Pinkerton, L. E. 2004. Mortality among a cohort of garment workers exposed to formaldehyde: an update. 

Occup. Environ. Med. 61: 193-200.

500 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.

501 Hauptmann, M,; Stewart P. A.; Lubin J. H.; Beane Freeman, L. E.; Hornung, R. W.; Herrick, R. F.; Hoover, R. 

N.; Fraumeni, J. F.; Hayes, R. B. 2009. Mortality from lymph hematopoietic malignancies and brain cancer among 

embalmers exposed to formaldehyde. Journal of the National Cancer Institute 101:1696-1708.

502 ATSDR. 1999. Toxicological Profile for Formaldehyde, U.S. Department of Health and Human Services (HHS), 

July 1999.

503 ATSDR. 2010. Addendum to the Toxicological Profile for Formaldehyde. U.S. Department of Health and Human 

Services (HHS), October 2010.

504 IPCS. 2002. Concise International Chemical Assessment Document 40. Formaldehyde. World Health 

Organization.
Page 586 of 850

EPA released a draft Toxicological Review of Formaldehyde – Inhalation Assessment 

through the IRIS program for peer review by the National Research Council (NRC) and public 

comment in June 2010.505 The draft assessment reviewed more recent research from animal and 

human studies on cancer and other health effects. The NRC released their review report in April 

2011.506 EPA is currently developing a new draft assessment in response to this review.

(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.507 The URE in IRIS for acetaldehyde is 2.2 × 10-6per μg/m3.

508

 Acetaldehyde is 

reasonably anticipated to be a human carcinogen by the U.S. DHHS in the 13

th Report on 

Carcinogens and is classified as possibly carcinogenic to humans (Group 2B) by the IARC.509,510 

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.511 In short-term (4 week) rat studies, degeneration of 

olfactory epithelium was observed at various concentration levels of acetaldehyde 

exposure.512,513 Data from these studies were used by EPA to develop an inhalation reference 

concentration of 9 μg/m3. Some asthmatics have been shown to be a sensitive subpopulation to 

decrements in functional expiratory volume (FEV1 test) and bronchoconstriction upon 

 

505 EPA (U.S. Environmental Protection Agency). 2010. Toxicological Review of Formaldehyde (CAS No. 50-00-0) 

– Inhalation Assessment: In Support of Summary Information on the Integrated Risk Information System (IRIS). 

External Review Draft. EPA/635/R-10/002A. U.S. Environmental Protection Agency, Washington DC [online]. 

Available: http://cfpub.epa.gov/ncea/irs_drats/recordisplay.cfm?deid=223614

506 NRC (National Research Council). 2011. Review of the Environmental Protection Agency’s Draft IRIS 

Assessment of Formaldehyde. Washington DC: National Academies Press. 

http://books.nap.edu/openbook.php?record_id=13142

507 U.S. EPA (1991). Integrated Risk Information System File of Acetaldehyde. Research and Development, 

National Center for Environmental Assessment, Washington, DC. This material is available electronically at 

http://www.epa.gov/iris/subst/0290.htm.

508 U.S. EPA (1991). Integrated Risk Information System File of Acetaldehyde. This material is available 

electronically at http://www.epa.gov/iris/subst/0290.htm. 

509 NTP. (2014). 13th Report on Carcinogens. Research Triangle Park, NC: U.S. Department of Health and Human 

Services, Public Health Service, National Toxicology Program. 

510 International Agency for Research on Cancer (IARC). (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.

511 U.S. EPA (1991). Integrated Risk Information System File of Acetaldehyde. This material is available 

electronically at http://www.epa.gov/iris/subst/0290.htm. 

512 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 electronically at 

http://www.epa.gov/iris/subst/0364.htm. 

513 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. 
Page 587 of 850

acetaldehyde inhalation.514 The agency is currently conducting a reassessment of the health 

hazards from inhalation exposure to acetaldehyde.

(f) Acrolein

EPA most recently evaluated the toxicological and health effects literature related to 

acrolein in 2003 and concluded 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.

515

 The IARC determined in 1995 that acrolein was not classifiable as to its 

carcinogenicity in humans.516 

Lesions to the lungs and upper respiratory tract of rats, rabbits, and hamsters have been 

observed after subchronic exposure to acrolein.517 The agency has developed an RfC for 

acrolein of 0.02 μg/m3 and an RfD of 0.5 μg/kg-day.

518

 EPA is considering updating the acrolein 

assessment with data that have become available since the 2003 assessment was completed.

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.519 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.520 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. Acute exposures in animal studies report bronchial hyperresponsiveness. Based on animal data (more pronounced respiratory irritancy in mice with 

 

514 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): 940-943. 

515 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. 

516 International Agency for Research on Cancer (IARC). (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. 

517 U.S. EPA. (2003). 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. 

518 U.S. EPA. (2003). 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. 

519 U.S. EPA. (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. 

520 U.S. EPA. (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. 

Available online at: http://www.epa.gov/ncea/iris/toxreviews/0364tr.pdf. 
Page 588 of 850

allergic airway disease in comparison to non-diseased mice521) 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 does not currently have an acute 

reference concentration for acrolein. The available health effect reference values for acrolein 

have been summarized by EPA and include an ATSDR MRL for acute exposure to acrolein of 

7 μg/m3for 1-14 days exposure; and Reference Exposure Level (REL) values from the 

California Office of Environmental Health Hazard Assessment (OEHHA) for one-hour and 8-

hour exposures of 2.5 μg/m3and 0.7 μg/m3, respectively.522

(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.523,524 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.525 In 1997 EPA 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.526 Since that time, studies have found that maternal exposures to PAHs in a 

population of pregnant women were 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).527,528 These and similar studies are being evaluated as a part 

of the ongoing IRIS assessment of health effects associated with exposure to benzo[a]pyrene.

 

521 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. 

522 U.S. EPA. (2009). Graphical Arrays of Chemical-Specific Health Effect Reference Values for Inhalation 

Exposures (Final Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-09/061, 2009. 

http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=211003 

523 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. 

524 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. 

525 International Agency for Research on Cancer (IARC). (2012). Monographs on the Evaluation of the 

Carcinogenic Risk of Chemicals for Humans, Chemical Agents and Related Occupations. Vol. 100F. Lyon, France.

526 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. 

527 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. 
Page 589 of 850

(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. Acute (short-term) exposure of humans to naphthalene by inhalation, ingestion, or 

dermal contact is associated with hemolytic anemia and damage to the liver and the nervous 

system.529 Chronic (long term) exposure of workers and rodents to naphthalene has been 

reported to cause cataracts and retinal damage.530 EPA released an external review draft of a 

reassessment of the inhalation carcinogenicity of naphthalene based on a number of recent 

animal carcinogenicity studies.531 The draft reassessment completed external peer review.532 

Based on external peer review comments received, a revised draft assessment that considers all 

routes of exposure, as well as cancer and noncancer effects, is under development. The 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.533 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.534 

 

528 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. 

529 U. S. EPA. 1998. 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.

530 U. S. EPA. 1998. 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.

531 U. S. EPA. (1998). 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. 

532 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. 

533 NTP. (2014). 13th Report on Carcinogens. U.S. Department of Health and Human Services, Public Health 

Service, National Toxicology Program.

534 International Agency for Research on Cancer (IARC). (2002). Monographs on the Evaluation of the 

Carcinogenic Risk of Chemicals for Humans. Vol. 82. Lyon, France. 
Page 590 of 850

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

abnormal cell changes and growth in respiratory and nasal tissues.535 The current EPA IRIS 

assessment includes noncancer data on hyperplasia and metaplasia in nasal tissue that form the 

basis of the inhalation RfC of 3 μg/m3.

536

 The ATSDR MRL for acute exposure to naphthalene 

is 0.6 mg/kg/day.

(i) Other Air Toxics

In addition to the compounds described above, other compounds in gaseous hydrocarbon 

and PM emissions from motor vehicles will be affected by this action. Mobile source air toxic 

compounds that will potentially be impacted include ethylbenzene, propionaldehyde, toluene, 

and xylene. Information regarding the health effects of these compounds can be found in EPA’s 

IRIS database.537

(8) Exposure and Health Effects Associated with Traffic

Locations in close proximity to major roadways generally have elevated concentrations 

of many air pollutants emitted from motor vehicles. Hundreds of such studies have been 

published in peer-reviewed journals, concluding that concentrations of CO, NO, NO2, benzene, 

aldehydes, particulate matter, black carbon, and many other compounds are elevated in ambient 

air within approximately 300-600 meters (about 1,000-2,000 feet) of major roadways. Highest 

concentrations of most pollutants emitted directly by motor vehicles are found at locations within 

50 meters (about 165 feet) of the edge of a roadway’s traffic lanes.

A recent large-scale review of air quality measurements in vicinity of major roadways 

between 1978 and 2008 concluded that the pollutants with the steepest concentration gradients in 

vicinities of roadways were CO, ultrafine particles, metals, elemental carbon (EC), NO, NOX, 

and several VOCs.538 These pollutants showed a large reduction in concentrations within 100 

meters downwind of the roadway. Pollutants that showed more gradual reductions with distance 

from roadways included benzene, NO2, PM2.5, and PM10. In the review article, results varied 

based on the method of statistical analysis used to determine the trend.

For pollutants with relatively high background concentrations relative to near-road 

concentrations, detecting concentration gradients can be difficult. For example, many aldehydes 

have high background concentrations as a result of photochemical breakdown of precursors from 

many different organic compounds. This can make detection of gradients around roadways and 

other primary emission sources difficult. However, several studies have measured aldehydes in 

 

535 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 

536 U.S. EPA. (1998). Toxicological Review of Naphthalene. Environmental Protection Agency, Integrated Risk 

Information System (IRIS), Research and Development, National Center for Environmental Assessment, 

Washington, DC http://www.epa.gov/iris/subst/0436.htm. 

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

538 Karner, A.A.; Eisinger, D.S.; Niemeier, D.A. (2010). Near-roadway air quality: synthesizing the findings from 

real-world data. Environ Sci Technol 44: 5334-5344.
Page 591 of 850

multiple weather conditions, and found higher concentrations of many carbonyls downwind of 

roadways.539,540 These findings suggest a substantial roadway source of these carbonyls.

In the past 15 years, many studies have been published with results reporting that 

populations who live, work, or go to school near high-traffic roadways experience higher rates of 

numerous adverse health effects, compared to populations far away from major roads.541 In

addition, numerous studies have found adverse health effects associated with spending time in 

traffic, such as commuting or walking along high-traffic roadways.542,543,544,545 The health 

outcomes with the strongest evidence linking them with traffic-associated air pollutants are 

respiratory effects, particularly in asthmatic children, and cardiovascular effects.

Numerous reviews of this body of health literature have been published as well. In 2010, 

an expert panel of the Health Effects Institute (HEI) published a review of hundreds of exposure, 

epidemiology, and toxicology studies.546 The panel rated how the evidence for each type of 

health outcome supported a conclusion of a causal association with traffic-associated air 

pollution as either “sufficient,” “suggestive but not sufficient,” or “inadequate and insufficient.” 

The panel categorized evidence of a causal association for exacerbation of childhood asthma as 

“sufficient.” The panel categorized evidence of a causal association for new onset asthma as 

between “sufficient” and as “suggestive but not sufficient.” “Suggestive of a causal association” 

was how the panel categorized evidence linking traffic-associated air pollutants with 

exacerbation of adult respiratory symptoms and lung function decrement. It categorized as 

“inadequate and insufficient” evidence of a causal relationship between traffic-related air 

pollution and health care utilization for respiratory problems, new onset adult asthma, chronic 

obstructive pulmonary disease (COPD), nonasthmatic respiratory allergy, and cancer in adults 

and children. Other literature reviews have been published with conclusions generally similar to 

 

539 Liu, W.; Zhang, J.; Kwon, J.l; et l. (2006). Concentrations and source characteristics of airborne carbonyl 

compounds measured outside urban residences. J Air Waste Manage Assoc 56: 1196-1204.

540 Cahill, T.M.; Charles, M.J.; Seaman, V.Y. (2010). Development and application of a sensitive method to 

determine concentrations of acrolein and other carbonyls in ambient air. Health Effects Institute Research Report 

149.Available at http://dx.doi.org

541 In the widely-used PubMed database of health publications, between January 1, 1990 and August 18, 2011, 605 

publications contained the keywords “traffic, pollution, epidemiology,” with approximately half the studies 

published after 2007. 

542 Laden, F.; Hart, J.E.; Smith, T.J.; Davis, M.E.; Garshick, E. (2007) Cause-specific mortality in the unionized 

U.S. trucking industry. Environmental Health Perspect 115:1192-1196.

543 Peters, A.; von Klot, S.; Heier, M.; Trentinaglia, I.; Hörmann, A.; Wichmann, H.E.; Löwel, H. (2004) Exposure 

to traffic and the onset of myocardial infarction. New England J Med 351: 1721-1730.

544 Zanobetti, A.; Stone, P.H.; Spelzer, F.E.; Schwartz, J.D.; Coull, B.A.; Suh, H.H.; Nearling, B.D.; Mittleman, 

M.A.; Verrier, R.L.; Gold, D.R. (2009) T-wave alternans, air pollution and traffic in high-risk subjects. Am J 

Cardiol 104: 665-670.

545 Dubowsky Adar, S.; Adamkiewicz, G.; Gold, D.R.; Schwartz, J.; Coull, B.A.; Suh, H. (2007) Ambient and 

microenvironmental particles and exhaled nitric oxide before and after a group bus trip. Environ Health Perspect 

115: 507-512.

546 Health Effects Institute Panel on the Health Effects of Traffic-Related Air Pollution. (2010). Traffic-related air 

pollution: a critical review of the literature on emissions, exposure, and health effects. HEI Special Report 17. 

Available at http://www.healtheffects.org
Page 592 of 850

the HEI panel’s.547,548,549,550 However, researchers from the U.S. Centers for Disease Control and 

Prevention (CDC) recently published a systematic review and meta-analysis of studies 

evaluating the risk of childhood leukemia associated with traffic exposure, and reported positive 

associations between “postnatal” proximity to traffic and leukemia risks, but no such association 

for “prenatal” exposures.551 

Health outcomes with few publications suggest the possibility of other effects still 

lacking sufficient evidence to draw definitive conclusions. Among these outcomes with a small 

number of positive studies are neurological impacts (e.g., autism and reduced cognitive function) 

and reproductive outcomes (e.g., preterm birth, low birth weight).552,553,554,555

In addition to health outcomes, particularly cardiopulmonary effects, conclusions of 

numerous studies suggest mechanisms by which traffic-related air pollution affects health. 

Numerous studies indicate that near-roadway exposures may increase systemic inflammation, 

affecting organ systems, including blood vessels and lungs.556,557,558,559 Long-term exposures in 

 

547 Boothe, V.L.; Shendell, D.G. (2008). Potential health effects associated with residential proximity to freeways 

and primary roads: review of scientific literature, 1999-2006. J Environ Health 70: 33-41.

548 Salam, M.T.; Islam, T.; Gilliland, F.D. (2008). Recent evidence for adverse effects of residential proximity to 

traffic sources on asthma. Curr Opin Pulm Med 14: 3-8.

549 Sun, X.; Zhang, S.; Ma, X. (2014) No association between traffic density and risk of childhood leukemia: a 

meta-analysis. Asia Pac J Cancer Prev 15: 5229-5232

550 Raaschou-Nielsen, O.; Reynolds, P. (2006). Air pollution and childhood cancer: a review of the epidemiological 

literature. Int J Cancer 118: 2920-9.

551 Boothe, VL.; Boehmer, T.K.; Wendel, A.M.; Yip, F.Y. (2014) Residential traffic exposure and childhood 

leukemia: a systematic review and meta-analysis. Am J Prev Med 46: 413-422.

552 Volk, H.E.; Hertz-Picciotto, I.; Delwiche, L.; et al. (2011). Residential proximity to freeways and autism in the 

CHARGE study. Environ Health Perspect 119: 873-877.

553 Franco-Suglia, S.; Gryparis, A.; Wright, R.O.; et al. (2007). Association of black carbon with cognition among 

children in a prospective birth cohort study. Am J Epidemiol. doi: 10.1093/aje/kwm308. [Online at 

http://dx.doi.org]

554 Power, M.C.; Weisskopf, M.G.; Alexeef, S.E.; et al. (2011). Traffic-related air pollution and cognitive function in 

a cohort of older men. Environ Health Perspect 2011: 682-687.

555 Wu, J.; Wilhelm, M.; Chung, J.; et al. (2011). Comparing exposure assessment methods for traffic-related air 

pollution in and adverse pregnancy outcome study. Environ Res 111: 685-6692.

556 Riediker, M. (2007). Cardiovascular effects of fine particulate matter components in highway patrol officers. 

Inhal Toxicol 19: 99-105. doi: 10.1080/08958370701495238 Available at http://dx.doi.org

557 Alexeef, S.E.; Coull, B.A.; Gryparis, A.; et al. (2011). Medium-term exposure to traffic-related air pollution and 

markers of inflammation and endothelial function. Environ Health Perspect 119: 481-486. 

doi:10.1289/ehp.1002560 Available at http://dx.doi.org

558 Eckel. S.P.; Berhane, K.; Salam, M.T.; et al. (2011). Traffic-related pollution exposure and exhaled nitric oxide 

in the Children’s Health Study. Environ Health Perspect (IN PRESS). doi:10.1289/ehp.1103516. Available at 

http://dx.doi.org

559 Zhang, J.; McCreanor, J.E.; Cullinan, P.; et al. (2009). Health effects of real-world exposure diesel exhaust in 

persons with asthma. Res Rep Health Effects Inst 138. [Online at http://www.healtheffects.org]
Page 593 of 850

near-road environments have been associated with inflammation-associated conditions, such as 

atherosclerosis and asthma.560,561,562 

Several studies suggest that some factors may increase susceptibility to the effects of 

traffic-associated air pollution. Several studies have found stronger respiratory associations in 

children experiencing chronic social stress, such as in violent neighborhoods or in homes with 

high family stress.563,564,565 

The risks associated with residence, workplace, or schools near major roads are of 

potentially high public health significance due to the large population in such locations. 

According to the 2009 American Housing Survey, over 22 million homes (17.0 percent of all 

U.S. housing units) were located within 300 feet of an airport, railroad, or highway with four or 

more lanes. This corresponds to a population of more than 50 million U.S. residents in close 

proximity to high-traffic roadways or other transportation sources. Based on 2010 Census data, a 

2013 publication estimated that 19 percent of the U.S. population (over 59 million people) lived 

within 500 meters of roads with at least 25,000 annual average daily traffic (AADT), while about 

3.2 percent of the population lived within 100 meters (about 300 feet) of such roads.566 Another 

2013 study estimated that 3.7 percent of the U.S. population (about 11.3 million people) lived 

within 150 meters (about 500 feet) of interstate highways, or other freeways and expressways.567 

As discussed in Section VIII. B. (9), on average, populations near major roads have higher 

fractions of minority residents and lower socioeconomic status. Furthermore, on average, 

Americans spend more than an hour traveling each day, bringing nearly all residents into a highexposure microenvironment for part of the day.

In light of these concerns, EPA has required and is working with states to ensure that air 

quality monitors be placed near high-traffic roadways for determining NAAQS compliance for 

CO, NO2, and PM2.5 (in addition to those existing monitors located in neighborhoods and other 

locations farther away from pollution sources). Near-roadway monitors for NO2 begin operation 

between 2014 and 2017 in Core Based Statistical Areas (CBSAs) with population of at least 

 

560 Adar, S.D.; Klein, R.; Klein, E.K.; et al. (2010). Air pollution and the microvasculatory: a cross-sectional

assessment of in vivo retinal images in the population-based Multi-Ethnic Study of Atherosclerosis. PLoS Med 

7(11): E1000372. doi:10.1371/journal.pmed.1000372. Available at http://dx.doi.org

561 Kan, H.; Heiss, G.; Rose, K.M.; et al. (2008). Proxpective analysis of traffic exposure as a risk factor for incident 

coronary heart disease: the Atherosclerosis Risk in Communities (ARIC) study. Environ Health Perspect 116: 

1463-1468. doi:10.1289/ehp.11290. Available at http://dx.doi.org

562 McConnell, R.; Islam, T.; Shankardass, K.; et al. (2010). Childhood incident asthma and traffic-related air 

pollution at home and school. Environ Health Perspect 1021-1026.

563 Islam, T.; Urban, R.; Gauderman, W.J.; et al. (2011). Parental stress increases the detrimental effect of traffic 

exposure on children’s lung function. Am J Respir Crit Care Med (In press) 

564 Clougherty, J.E.; Levy, J.I.; Kubzansky, L.D.; et al. (2007). Synergistic effects of traffic-related air pollution and 

exposure to violence on urban asthma etiology. Environ Health Perspect 115: 1140-1146.

565 Chen, E.; Schrier, H.M.; Strunk, R.C.; et al. (2008). Chronic traffic-related air pollution and stress interact to 

predict biologic and clinical outcomes in asthma. Environ Health Perspect 116: 970-5.

566 Rowangould, G.M. (2013) A census of the U.S. near-roadway population: public health and environmental 

justice considerations. Transportation Research Part D 25: 59-67.

567 Boehmer, T.K.; Foster, S.L.; Henry, J.R.; Woghiren-Akinnifesi, E.L.; Yip, F.Y. (2013) Residential proximity to 

major highways – United States, 2010. Morbidity and Mortality Weekly Report 62(3); 46-50.
Page 594 of 850

500,000. Monitors for CO and PM2.5 begin operation between 2015 and 2017. These monitors 

will further our understanding of exposure in these locations.

EPA and DOT continue to research near-road air quality, including the types of pollutants 

found in high concentrations near major roads and health problems associated with the mixture 

of pollutants near roads. 

(9) Environmental Justice

Environmental justice (EJ) is a principle asserting that all people deserve fair treatment 

and meaningful involvement with respect to environmental laws, regulations, and policies. 

EPA seeks to provide the same degree of protection from environmental health hazards for all 

people. DOT shares this goal and is informed about the potential environmental impacts of its 

rulemakings through its NEPA process (see NHTSA’s DEIS). As referenced below, numerous 

studies have found that some environmental hazards are more prevalent in areas where 

racial/ethnic minorities and people with low socioeconomic status (SES), represent a higher 

fraction of the population compared with the general population.

As discussed in Section VIII. B. (8) of this document and NHTSA’s DEIS, 

concentrations of many air pollutants are elevated near high-traffic roadways. If minority

populations and low-income populations disproportionately live near such roads, then an issue 

of EJ may be present. We reviewed existing scholarly literature examining the potential for 

disproportionate exposure among minorities and people with low SES and we conducted our 

own evaluation of two national datasets: the U.S. Census Bureau’s American Housing Survey

for calendar year 2009 and the U.S. Department of Education’s database of school locations.

Publications that address EJ issues generally report that populations living near major 

roadways (and other types of transportation infrastructure) tend to be composed of larger 

fractions of nonwhite residents. People living in neighborhoods near such sources of air 

pollution also tend to be lower in income than people living elsewhere. Numerous studies 

evaluating the demographics and socioeconomic status of populations or schools near roadways 

have found that they include a greater percentage of minority residents, as well as lower SES 

(indicated by variables such as median household income). Locations in these studies include

Los Angeles, CA; Seattle, WA; Wayne County, MI; Orange County, FL; and the State of 

California 568,569,570,571,572,573 Such disparities may be due to multiple factors.574

 

568 Marshall, J.D. (2008) Environmental inequality: air pollution exposures in California’s South Coast Air Basin.

569 Su, J.G.; Larson, T.; Gould, T.; Cohen, M.; Buzzelli, M. (2010) Transboundary air pollution and environmental 

justice: Vancouver and Seattle compared. GeoJournal 57: 595-608. doi:10.1007/s10708-009-9269-6 [Online at 

http://dx.doi.org]

570 Chakraborty, J.; Zandbergen, P.A. (2007) Children at risk: measuring racial/ethnic disparities in potential 

exposure to air pollution at school and home. J Epidemiol Community Health 61: 1074-1079. doi: 

10.1136/jech.2006.054130 [Online at http://dx.doi.org]

571 Green, R.S.; Smorodinsky, S.; Kim, J.J.; McLaughlin, R.; Ostro, B. (2003) Proximity of California public schools 

to busy roads. Environ Health Perspect 112: 61-66. doi:10.1289/ehp.6566 [http://dx.doi.org]
Page 595 of 850

People with low SES often live in neighborhoods with multiple stressors and health risk 

factors, including reduced health insurance coverage rates, higher smoking and drug use rates, 

limited access to fresh food, visible neighborhood violence, and elevated rates of obesity and 

some diseases such as asthma, diabetes, and ischemic heart disease. Although questions 

remain, several studies find stronger associations between air pollution and health in locations 

with such chronic neighborhood stress, suggesting that populations in these areas may be more 

susceptible to the effects of air pollution.575,576,577,578 Household-level stressors such as parental 

smoking and relationship stress also may increase susceptibility to the adverse effects of air 

pollution.579,580

More recently, three publications report nationwide analyses that compare the 

demographic patterns of people who do or do not live near major roadways.581,582,583 All three 

of these studies found that people living near major roadways are more likely to be minorities or 

low in SES. They also found that the outcomes of their analyses varied between regions within 

the U.S. However, only one such study looked at whether such conclusions were confounded 

by living in a location with higher population density and how demographics differ between 

locations nationwide. In general, it found that higher density areas have higher proportions of 

low income and minority residents.

 

572 Wu, Y; Batterman, S.A. (2006) Proximity of schools in Detroit, Michigan to automobile and truck traffic. J 

Exposure Sci & Environ Epidemiol. doi:10.1038/sj.jes.7500484 [Online at http://dx.doi.org]

573 Su, J.G.; Jerrett, M.; de Nazelle, A.; Wolch, J. (2011) Does exposure to air pollution in urban parks have 

socioeconomic, racial, or ethnic gradients? Environ Res 111: 319-328.

574 Depro, B.; Timmins, C. (2008) Mobility and environmental equity: do housing choices determine exposure to air 

pollution? North Caroline State University Center for Environmental and Resource Economic Policy

575 Clougherty, J.E.; Kubzansky, L.D. (2009) A framework for examining social stress and susceptibility to air 

pollution in respiratory health. Environ Health Perspect 117: 1351-1358. Doi:10.1289/ehp.0900612 [Online at 

http://dx.doi.org]

576 Clougherty, J.E.; Levy, J.I.; Kubzansky, L.D.; Ryan, P.B.; Franco Suglia, S.; Jacobson Canner, M.; Wright, R.J. 

(2007) Synergistic effects of traffic-related air pollution and exposure to violence on urban asthma etiology. 

Environ Health Perspect 115: 1140-1146. doi:10.1289/ehp.9863 [Online at http://dx.doi.org]

577 Finkelstein, M.M.; Jerrett, M.; DeLuca, P.; Finkelstein, N.; Verma, D.K.; Chapman, K.; Sears, M.R. (2003) 

Relation between income, air pollution and mortality: a cohort study. Canadian Med Assn J 169: 397-402.

578 Shankardass, K.; McConnell, R.; Jerrett, M.; Milam, J.; Richardson, J.; Berhane, K. (2009) Parental stress 

increases the effect of traffic-related air pollution on childhood asthma incidence. Proc Natl Acad Sci 106: 12406-

12411. doi:10.1073/pnas.0812910106 [Online at http://dx.doi.org]

579 Lewis, A.S.; Sax, S.N.; Wason, S.C.; Campleman, S.L (2011) Non-chemical stressors and cumulative risk 

assessment: an overview of current initiatives and potential air pollutant interactions. Int J Environ Res Public 

Health 8: 2020-2073. Doi:10.3390/ijerph8062020 [Online at http://dx.doi.org]

580 Rosa, M.J.; Jung, K.H.; Perzanowski, M.S.; Kelvin, E.A.; Darling, K.W.; Camann, D.E.; Chillrud, S.N.; Whyatt, 

R.M.; Kinney, P.L.; Perera, F.P.; Miller, R.L (2010) Prenatal exposure to polycyclic aromatic hydrocarbons, 

environmental tobacco smoke and asthma. Respir Med (In press). doi:10.1016/j.rmed.2010.11.022 [Online at 

http://dx.doi.org]

581 Rowangould, G.M. (2013) A census of the U.S. near-roadway population: public health and environmental 

justice considerations. Transportation Research Part D; 59-67.

582 Tian, N.; Xue, J.; Barzyk. T.M. (2013) Evaluating socioeconomic and racial differences in traffic-related metrics 

in the United States using a GIS approach. J Exposure Sci Environ Epidemiol 23: 215-222.

583 Boehmer, T.K.; Foster, S.L.; Henry, J.R.; Woghiren-Akinnifesi, E.L.; Yip, F.Y. (2013) Residential proximity to 

major highways – United States, 2010. Morbidity and Mortality Weekly Report 62(3): 46-50. 
Page 596 of 850

We analyzed two national databases that allowed us to evaluate whether homes and 

schools were located near a major road and whether disparities in exposure may be occurring in 

these environments. The American Housing Survey (AHS) includes descriptive statistics of 

over 70,000 housing units across the nation. The study survey is conducted every two years by

the U.S. Census Bureau. The second database we analyzed was the U.S. Department of 

Education’s Common Core of Data, which includes enrollment and location information for 

schools across the U.S.

In analyzing the 2009 AHS, we focused on whether or not a housing unit was located 

within 300 feet of “4-or-more lane highway, railroad, or airport.”

584

 We analyzed whether there 

were differences between households in such locations compared with those in locations farther 

from these transportation facilities.

585

 We included other variables, such as land use category, 

region of country, and housing type. We found that homes with a nonwhite householder were 

22-34 percent more likely to be located within 300 feet of these large transportation facilities

than homes with white householders. Homes with a Hispanic householder were 17-33 percent 

more likely to be located within 300 feet of these large transportation facilities than homes with 

non-Hispanic householders. Households near large transportation facilities were, on average, 

lower in income and educational attainment, more likely to be a rental property and located in 

an urban area compared with households more distant from transportation facilities.

In examining schools near major roadways, we examined the Common Core of Data 

(CCD) from the U.S. Department of Education, which includes information on all public 

elementary and secondary schools and school districts nationwide.586 To determine school 

proximities to major roadways, we used a geographic information system (GIS) to map each 

school and roadways based on the U.S. Census’s TIGER roadway file.587 We found that 

minority students were overrepresented at schools within 200 meters of the largest roadways, 

and that schools within 200 meters of the largest roadways also had higher than expected 

numbers of students eligible for free or reduced-price lunches. For example, Black students 

represent 22 percent of students at schools located within 200 meters of a primary road, whereas 

Black students represent 17 percent of students in all U.S. schools. Hispanic students represent 

30 percent of students at schools located within 200 meters of a primary road, whereas Hispanic 

students represent 22 percent of students in all U.S. schools.

Overall, there is substantial evidence that people who live or attend school near major 

roadways are more likely to be of a minority race, Hispanic ethnicity, and/or low SES. The 

emission reductions from these proposed rules would likely result in widespread air quality

 

584 This variable primarily represents roadway proximity. According to the Central Intelligence Agency’s World 

Factbook, in 2010, the United States had 6,506,204 km or roadways, 224,792 km of railways, and 15,079 airports. 

Highways thus represent the overwhelming majority of transportation facilities described by this factor in the AHS.

585 Bailey, C. (2011) Demographic and Social Patterns in Housing Units Near Large Highways and other 

Transportation Sources. Memorandum to docket.

586 http://nces.ed.gov/ccd/

587 Pedde, M.; Bailey, C. (2011) Identification of Schools within 200 Meters of U.S. Primary and Secondary Roads. 

Memorandum to the docket.
Page 597 of 850

improvements, but the impact on pollution levels in close proximity to roadways would be most 

direct. Thus, these proposed rules would likely help in mitigating the disparity in racial, ethnic, 

and economically-based exposures. 

C. Environmental Effects of Non-GHG Pollutants

(1) Visibility

Visibility can be defined as the degree to which the atmosphere is transparent to visible 

light.588 Visibility impairment is caused by light scattering and absorption by suspended 

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.589

EPA is working to address visibility impairment. Reductions in air pollution from 

implementation of various programs associated with the Clean Air Act Amendments of 1990 

(CAAA) provisions have resulted in substantial improvements in visibility, and will continue to 

do so in the future. Because trends in haze are closely associated with trends in particulate 

sulfate and nitrate due to the simple relationship between their concentration and light extinction, 

visibility trends have improved as emissions of SO2 and NOx have decreased over time due to air 

pollution regulations such as the Acid Rain Program.590

In the Clean Air Act Amendments of 1977, Congress recognized visibility’s value to 

society by establishing a national goal to protect national parks and wilderness areas from 

visibility impairment caused by manmade pollution.591 In 1999, EPA finalized the regional haze 

program to protect the visibility in Mandatory Class I Federal areas.592 There are 156 national 

parks, forests and wilderness areas categorized as Mandatory Class I Federal areas.593 These 

areas are defined in CAA Section 162 as those national parks exceeding 6,000 acres, wilderness 

 

588 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. This book can be viewed on the National Academy Press Website at 

http://www.nap.edu/books/0309048443/html/

589 U.S. EPA. (2009). Integrated Science Assessment for Particulate Matter (Final Report). U.S. Environmental 

Protection Agency, Washington, DC, EPA/600/R-08/139F. 

590 U.S. Environmental Protection Agency (U.S. EPA). 2009. Integrated Science Assessment for Particulate Matter 

(Final Report). EPA-600-R-08-139F. National Center for Environmental Assessment—RTP Division. December. 

Available on the Internet at <http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=216546>.

591 See Section 169(a) of the Clean Air Act. 

592 64 FR 35714 (July 1, 1999). 

593 62 FR 38680-38681 (July 18, 1997).
Page 598 of 850

areas and memorial parks exceeding 5,000 acres, and all international parks which were in 

existence on August 7, 1977. 

EPA has also 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 such as dry chemical composition and relative humidity (i.e., an indicator of the water 

composition of the particles). EPA revised the PM2.5 standards in December 2012 and 

established a target level of protection that is expected to be met through attainment of the 

existing secondary standards for PM2.5. 

(2) Plant and Ecosystem Effects of Ozone

The welfare effects of ozone can be observed across a variety of scales, i.e. subcellular, 

cellular, leaf, whole plant, population and ecosystem. Ozone effects that begin at small spatial 

scales, such as the leaf of an individual plant, when they occur at sufficient magnitudes (or to a 

sufficient degree) can result in effects being propagated along a continuum to larger and larger 

spatial scales. For example, effects at the individual plant level, such as altered rates of leaf gas 

exchange, growth and reproduction can, when widespread, result in broad changes in 

ecosystems, such as productivity, carbon storage, water cycling, nutrient cycling, and community

composition.

Ozone can produce both acute and chronic injury in sensitive species depending on the 

concentration level and the duration of the exposure.594 In those sensitive species,

595 effects from 

repeated exposure to ozone throughout the growing season of the plant tend to accumulate, so 

that even low concentrations experienced for a longer duration have the potential to create 

chronic stress on vegetation.596 Ozone damage to sensitive species includes impaired 

photosynthesis and visible injury to leaves. The impairment of photosynthesis, the process by

which the plant makes carbohydrates (its source of energy and food), can lead to reduced crop 

yields, timber production, and plant productivity and growth. Impaired photosynthesis can also 

lead to a reduction in root growth and carbohydrate storage below ground, resulting in other, 

more subtle plant and ecosystems impacts.597 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 areas with sensitive species could 

potentially lead to species shifts and loss from the affected ecosystems,598 resulting in a loss or 

 

594 73 FR 16486 (March 27, 2008).

595 73 FR 16491 (March 27, 2008). Only a small percentage of all the plant species growing within the U.S. (over 

43,000 species have been catalogued in the USDA PLANTS database) have been studied with respect to ozone 

sensitivity.

596 The concentration at which ozone levels overwhelm a plant’s ability to detoxify or compensate for oxidant 

exposure varies. Thus, whether a plant is classified as sensitive or tolerant depends in part on the exposure levels 

being considered. Chapter 9, Section 9.3.4 of U.S. EPA, 2013 Integrated Science Assessment for Ozone and 

Related Photochemical Oxidants. Office of Research and Development/National Center for Environmental 

Assessment. U.S. Environmental Protection Agency. EPA 600/R-10/076F.

597 73 FR 16492 (March 27, 2008).

598 73 FR 16493/16494 (March 27, 2008), Per footnote 175 above, ozone impacts could be occurring in areas where 

plant species sensitive to ozone have not yet been studied or identified.
Page 599 of 850

reduction in associated ecosystem goods and services. Additionally, visible ozone injury to 

leaves can result in a loss of aesthetic value in areas of special scenic significance like national 

parks and wilderness areas and reduced use of sensitive ornamentals in landscaping.599 

The Integrated Science Assessment (ISA) for Ozone presents more detailed information 

on how ozone effects vegetation and ecosystems.600 The ISA concludes that ambient 

concentrations of ozone are associated with a number of adverse welfare effects and 

characterizes the weight of evidence for different effects associated with ozone.601 The ISA 

concludes that visible foliar injury effects on vegetation, reduced vegetation growth, reduced 

productivity in terrestrial ecosystems, reduced yield and quality of agricultural crops, and 

alteration of below-ground biogeochemical cycles are causally associated with exposure to 

ozone. It also concludes that reduced carbon sequestration in terrestrial ecosystems, alteration of 

terrestrial ecosystem water cycling, and alteration of terrestrial community composition are 

likely to be causally associated with exposure to ozone.

(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. 

Adverse impacts to human health and the environment can occur when particulate matter 

is deposited to soils, water, and biota.602 Deposition of heavy metals or other toxics may lead to 

the human ingestion of contaminated fish, impairment of drinking water, damage to terrestrial, 

freshwater and marine ecosystem components, and limits to recreational uses. 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.603 

 

599 73 FR 16490/ 16497 (March 27, 2008).

600 U.S. EPA. Integrated Science Assessment of Ozone and Related Photochemical Oxidants (Final Report). U.S. 

Environmental Protection Agency, Washington, DC, EPA/600/R-10/076F, 2013. The ISA is available at 

http://cfpub.epa.gov/ncea/isa/recordisplay.cfm?deid=247492#Download

601 The Ozone ISA evaluates the evidence associated with different ozone related health and welfare 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 more information on these levels of evidence, please refer to Table II of the ISA. 

602 U.S. EPA. Integrated Science Assessment for Particulate Matter (Final Report). U.S. Environmental Protection 

Agency, Washington, DC, EPA/600/R-08/139F, 2009.

603 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. 
Page 600 of 850

The ecological effects of acidifying deposition and nutrient enrichment are detailed in the 

Integrated Science Assessment for Oxides of Nitrogen and Sulfur-Ecological Criteria.604

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 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 biodiversity of fishes, zooplankton and macroinvertebrates 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 in forests include a decline in sensitive tree species, such as red 

spruce (Picea rubens) and sugar maple (Acer saccharum). 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 Chapter 8.1.2.3 of the RIA.

Building materials including metals, stones, cements, and paints undergo natural 

weathering processes from exposure to environmental elements (e.g., wind, moisture, 

temperature fluctuations, sunlight, etc.). Pollution can worsen and accelerate these effects. 

Deposition of PM is associated with both physical damage (materials damage effects) and 

impaired aesthetic qualities (soiling effects). Wet and dry deposition of PM can physically affect 

materials, adding to the effects of natural weathering processes, by potentially promoting or 

accelerating the corrosion of metals, by degrading paints and by deteriorating building materials 

such as stone, concrete and marble.605 The effects of PM are exacerbated by the presence of 

acidic gases and can be additive or synergistic due to the complex mixture of pollutants in the air 

and surface characteristics of the material. Acidic deposition has been shown to have an effect 

on materials including zinc/galvanized steel and other metal, carbonate stone (as monuments and 

building facings), and surface coatings (paints).

606 The effects on historic buildings and outdoor 

works of art are of particular concern because of the uniqueness and irreplaceability of many of 

these objects.

 

604 NOX and SOX secondary ISA604 U.S. EPA. Integrated Science Assessment (ISA) for Oxides of Nitrogen and 

Sulfur Ecological Criteria (Final Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R08/082F, 2008.

605 U.S. Environmental Protection Agency (U.S. EPA). 2009. Integrated Science Assessment for Particulate Matter 

(Final Report). EPA-600-R-08-139F. National Center for Environmental Assessment—RTP Division. December. 

Available on the Internet at <http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=216546>.

606 Irving, P.M., e.d. 1991. Acid Deposition: State of Science and Technology, Volume III, Terrestrial, Materials, 

Health, and Visibility Effects, The U.S. National Acid Precipitation Assessment Program, Chapter 24, page 24–76.
Page 601 of 850

(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.607 In laboratory experiments, a wide range of tolerance to VOCs has been observed.608 

Decreases in harvested seed pod weight have been reported for the more sensitive plants, and 

some studies have reported effects on seed 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.609

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.610,611, 612

D. Air Quality Impacts of Non-GHG Pollutants

(1) Current Concentrations of Non-GHG Pollutants

Nationally, levels of PM2.5, ozone, NOX, SOX, CO and air toxics are declining.613

However, as of July 2, 2014 approximately 147 million people lived in counties designated 

nonattainment for one or more of the NAAQS, and this figure does not include the people living 

in areas with a risk of exceeding the NAAQS in the future.614 The most recent available data 

indicate that 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.615 In addition, 

 

607 U.S. EPA. (1991). Effects of organic chemicals in the atmosphere on terrestrial plants. EPA/600/3-91/001. 

608 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. 

609 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. 

610 Viskari E-L. (2000). Epicuticular wax of Norway spruce needles as indicator of traffic pollutant deposition. 

Water, Air, and Soil Pollut. 121:327-337. 

611 Ugrekhelidze D, F Korte, G Kvesitadze. (1997). Uptake and transformation of benzene and toluene by plant 

leaves. Ecotox. Environ. Safety 37:24-29. 

612 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. 

613 U.S. EPA, 2011. Our Nation’s Air: Status and Trends through 2010. EPA-454/R-12-001. February 2012. 

Available at: http://www.epa.gov/airtrends/2011/. 

614 Data come from Summary Nonattainment Area Population Exposure Report, current as of July 2, 2014 at: 

http://www.epa.gov/oar/oaqps/greenbk/popexp.html and contained in Docket EPA-HQ-OAR-2014-0827.

615 U.S. EPA. (2011) Summary of Results for the 2005 National-Scale Assessment. 

www.epa.gov/ttn/atw/nata2005/05pdf/sum_results.pdf.
Page 602 of 850

populations who live, work, or attend school near major roads experience elevated exposure 

concentrations to a wide range of air pollutants.616

EPA recognizes that states and local areas are particularly concerned about the challenges 

of reducing NOX and attaining as well as maintaining the ozone NAAQS. States and local areas 

are required to adopt emission control measures to attain the NAAQS. States may then choose to 

seek redesignation to attainment and if they do so they must demonstrate that control measures 

are in place sufficient to maintain the NAAQS for ten years (and eight years later, a similar 

demonstration is required for another ten-year period). The most recent revision to the ozone

standards was in 2008; the previous 8-hour ozone standards were set in 1997. Attaining and 

maintaining the NAAQS has been challenging for some areas in the past, and EPA has recently

issued a proposal that would strengthen the ozone NAAQS (79 Fed. Reg 75,234, Dec. 17, 2014). 

 

(2) Impacts of Proposed Standards on Future Ambient Concentrations of Non-GHG 

Pollutants

Full-scale photochemical air quality modeling is necessary to accurately project levels of 

criteria pollutants and air toxics. For the final rulemaking, national-scale air quality modeling 

analyses will be performed to analyze the impacts of the standards on PM2.5, ozone, NO2, and 

selected air toxics (i.e., benzene, formaldehyde, acetaldehyde, naphthalene, acrolein and 1,3-

butadiene). The length of time needed to prepare the necessary emissions inventories, in 

addition to the processing time associated with the modeling itself, has precluded us from 

performing air quality modeling for this proposal.

Section VIII.A of the preamble presents projections of the changes in criteria pollutant 

and air toxics emissions due to the proposed vehicle standards; the basis for those estimates is set 

out in Chapter 5 of the draft RIA. NHTSA also provides its projections in Chapter 4 of its DEIS. 

The atmospheric chemistry related to ambient concentrations of PM2.5, ozone and air toxics is 

very complex, and making predictions based solely on emissions changes is extremely difficult. 

However, based on the magnitude of the emissions changes predicted to result from the proposed 

standards, the agencies expect that there will be improvements in ambient air quality, pending 

more comprehensive analyses for the final rulemaking. 

For the final rulemaking national-scale air quality modeling analyses will be performed to 

estimate future year ambient ozone, NO2, and PM2.5 concentrations, air toxics concentrations, 

visibility levels and nitrogen and sulfur deposition levels for 2040. The agencies intend to use a 

2011-based Community Multi-scale Air Quality (CMAQ) modeling platform as the tool for the 

air quality modeling. The CMAQ modeling system is a comprehensive three-dimensional gridbased Eulerian air quality model designed to estimate the formation and fate of oxidant 

 

616 Health Effects Institute Panel on the Health Effects of Traffic-Related Air Pollution. (2010) Traffic-related air 

pollution: a critical review of the literature on emissions, exposure, and health effects. HEI Special Report 17. 

Available at http://www.healtheffects.org] 
Page 603 of 850

precursors, primary and secondary PM concentrations and deposition, and air toxics, over 

regional and urban spatial scales (e.g., over the contiguous United States).617,618,619,620 The 

CMAQ model is a well-known and well-established tool and is commonly used by EPA for 

regulatory analyses, by States in developing attainment demonstrations for their State 

Implementation Plans, and in numerous other national and international applications.

621,622,623,624

 

The CMAQ model version 5.0 was most recently peer-reviewed in September of 2011 for the 

U.S. EPA.625 CMAQ includes numerous science modules that simulate the emission, 

production, decay, deposition and transport of organic and inorganic gas-phase and particlephase pollutants in the atmosphere. This 2011 multi-pollutant modeling platform used the most 

recent multi-pollutant CMAQ code available at the time of air quality modeling (CMAQ version 

5.0.2; multipollutant version).626 CMAQ v5.0.2 reflects updates to version 5.0 to improve the 

underlying science algorithms as well as include new diagnostic/scientific modules which are 

detailed at http://www.cmascenter.org.627,628,629 

 

617 U.S. Environmental Protection Agency, Byun, D.W., and Ching, J.K.S., Eds, 1999. Science algorithms of EPA 

Models-3 Community Multiscale Air Quality (CMAQ modeling system, EPA/600/R-99/030, Office of Research and 

Development). Docket EPA-HQ-OAR-2010-0162

618 Byun, D.W., and Schere, K.L., 2006. Review of the Governing Equations, Computational Algorithms, and Other 

Components of the Models-3 Community Multiscale Air Quality (CMAQ) Modeling System, J. Applied Mechanics 

Reviews, 59 (2), 51-77. Docket EPA-HQ-OAR-2010-0162

619 Dennis, R.L., Byun, D.W., Novak, J.H., Galluppi, K.J., Coats, C.J., and Vouk, M.A., 1996. The next generation 

of integrated air quality modeling: EPA’s Models-3, Atmospheric Environment, 30, 1925-1938. Docket EPA-HQOAR-2010-0162

620 Carlton, A., Bhave, P., Napelnok, S., Edney, E., Sarwar, G., Pinder, R., Pouliot, G., and Houyoux, M. Model 

Representation of Secondary Organic Aerosol in CMAQv4.7. Ahead of Print in Environmental Science and 

Technology. Accessed at: http://pubs.acs.org/doi/abs/10.1021/es100636q?prevSearch=CMAQ&searchHistoryKey

Docket EPA-HQ-OAR-2010-0162.

621 U.S. EPA (2007). Regulatory Impact Analysis of the Proposed Revisions to the National Ambient Air Quality 

Standards for Ground-Level Ozone. EPA document number 442/R-07-008, July 2007. Docket EPA-HQ-OAR2010-0162

622 Hogrefe, C., Biswas, J., Lynn, B., Civerolo, K., Ku, J.Y., Rosenthal, J., et al. (2004). Simulating regional-scale 

ozone climatology over the eastern United States: model evaluation results. Atmospheric Environment, 38(17),

2627-2638.

623 United States Environmental Protection Agency. (2008). Technical support document for the final 

locomotive/marine rule: Air quality modeling analyses. Research Triangle Park, N.C.: U.S. Environmental 

Protection Agency, Office of Air Quality Planning and Standards, Air Quality Assessment Division.

624 Lin, M., Oki, T., Holloway, T., Streets, D.G., Bengtsson, M., Kanae, S., (2008). Long range transport of 

acidifying substances in East Asia Part I: Model evaluation and sensitivity studies. Atmospheric Environment, 

42(24), 5939-5955.

625 Brown, N., Allen, D., Amar, P., Kallos, G., McNider, R., Russell, A., Stockwell, W. (September 2011). Final 

Report: Fourth Peer Review of the CMAQ Model, NERL/ORD/EPA. U.S. EPA, Research Triangle Park, NC. 

http://www.epa.gov/asmdnerl/Reviews/2011_CMAQ_Review_FinalReport.pdf. It is available from the Community 

Modeling and Analysis System (CMAS) as well as previous peer-review reports at: http://www.cmascenter.org.

626 CMAQ version 5.0.2 was released in April 2014. It is available from the Community Modeling and Analysis 

System (CMAS) website: http://www.cmascenter.org.

627 Community Modeling and Analysis System (CMAS) website: http://www.cmascenter.org, RELEASE_NOTES 

for CMAQv5.0 - February 2012. 

628 Community Modeling and Analysis System (CMAS) website: http://www.cmascenter.org, RELEASE_NOTES 

for CMAQv5.0.1 - July 2012.
Page 604 of 850

 

629 Community Modeling and Analysis System (CMAS) website: http://www.cmascenter.org. CMAQ version 5.0.2 

(April 2014 release) Technical Documentation. - May 2014.
Page 605 of 850

IX. Economic and Other Impacts

This section presents the costs, benefits and other economic impacts of the proposed 

Phase 2 standards. It is important to note that NHTSA’s proposed fuel consumption standards 

and EPA’s proposed GHG standards would both be in effect, and each would lead to average 

fuel efficiency increases and GHG emission reductions. 

The net benefits of the proposed Phase 2 standards consist of the effects of the program 

on: 

 the vehicle program costs (costs of complying with the vehicle CO2 and fuel 

consumption standards),

 changes in fuel expenditures associated with reduced fuel use resulting from more 

efficient vehicles and increased fuel use associated with the “rebound” effect, both of 

which result from the program,

 the economic value of reductions in GHGs, 

 the economic value of reductions in non-GHG pollutants, 

 costs associated with increases in noise, congestion, and accidents resulting from 

increased vehicle use, 

 savings in drivers’ time from less frequent refueling,

 benefits of increased vehicle use associated with the “rebound” effect,

 the economic value of improvements in U.S. energy security. 

The benefits and costs of these rules are analyzed using 3 percent and 7 percent discount 

rates, consistent with current OMB guidance.630 These rates are intended to represent 

consumers’ preference for current over future consumption (3 percent), and the real rate of return 

on private investment (7 percent) which indicates the opportunity cost of capital. However, 

neither of these rates necessarily represents the discount rate that individual decision-makers use.

The program may also have other economic effects that are not included here. The

agencies seek comment on whether any costs or benefits are omitted from this analysis, so that 

they can be explicitly recognized in the final rules. In particular, as discussed in Sections III 

through VI of this preamble and in Chapter 2 of the draft RIA, the technology cost estimates 

developed here take into account the costs to hold other vehicle attributes, such as size and 

performance, constant. With these assumptions, and because welfare losses represent monetary

estimates of how much buyers would have to be compensated to be made as well off as they

would have been in the absence of this regulation,631 price increases for new vehicles measure 

 

630 The range of Social Cost of Carbon (SC-CO2) values uses several discount rates because the literature shows that 

the SC-CO2 is quite sensitive to assumptions about the discount rate, and because no consensus exists on the 

appropriate rate to use in an intergenerational context (where costs and benefits are incurred by different 

generations). Refer to Section F.1 for more information.

631 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, 
Page 606 of 850

the welfare losses to the vehicle buyers.632 If the full technology cost gets passed along to the 

buyer as an increase in price, the technology cost thus measures the primary welfare loss of the 

standards, including impacts on buyers. Increasing fuel efficiency would have to lead to other 

changes in the vehicles that buyers find undesirable for there to be additional welfare losses that 

are not included in the technology costs. 

As the 2012-2016 and 2017-2025 light-duty GHG/CAFE rules discussed, if other vehicle 

attributes are not held constant, then the technology cost estimates do not capture the losses to 

vehicle buyers associated with these changes.633 The light-duty rules also discussed other 

potential issues that could affect the calculation of the welfare impacts of these types of changes, 

such as aspects of buyers’ behavior that might affect the demand for technology investments, 

uncertainty in buyers’ investment horizons, and the rate at which truck owner’s trade off higher 

vehicle purchase price against future fuel savings. The agencies seek comments, including 

supporting data and quantitative analyses, of any additional impacts of the proposed standards on 

vehicle attributes and performance, or other potential aspects that could positively or negatively

affect the welfare implications of this proposed rulemaking. 

Where possible, we identify the uncertain aspects of these economic impacts and attempt 

to quantify them (e.g., sensitivity ranges associated with quantified and monetized GHG impacts; 

range of dollar-per-ton values to monetize non-GHG health benefits; uncertainty with respect to 

learning and markups). For HD pickups and vans, the agencies explicitly analyzed the 

uncertainty surrounding its estimates of the economic impacts from requiring higher fuel 

efficiency in Preamble Section VI. The agencies have also examined the sensitivity of oil prices

on fuel expenditures; results of this sensitivity analysis can be found in Chapter 8 of the RIA. 

NHTSA’s draft EIS also characterizes the uncertainty in economic impacts associated with the 

HD national program. For other impacts, however, there is inadequate information to inform a 

thorough, quantitative assessment of uncertainty. EPA and NHTSA continue 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 agencies seek comments on the methods and 

 

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. 

632 Indeed, it is likely to be an overestimate of the loss to the consumer, 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 efficiency improvements that make the vehicle less 

desirable to consumers.

633 Environmental Protection Agency and Department of Transportation, “Light-Duty Vehicle Greenhouse Gas 

Emission Standards and Corporate Average Fuel Economy Standards; Final Rule,” 75 FR 25324, May 7, 2010, 

especially Sections III.H.1 (pp. 25510-25513) and IV.G.6 (pp. 25651-25657); Environmental Protection Agency and 

Department of Transportation, ”2017 and Later Model Year Light-Duty Vehicle Greenhouse Gas Emissions and 

Corporate Average Fuel Economy Standards; Final Rule,” 77 FR 62624, October 15, 2012, especially Sections 

III.H.1 (pp. 62913-62919) and IV.G.5.a (pp. 63102-63104).
Page 607 of 850

assumptions used to quantify uncertainty in this analysis, as well as comments on methods and 

data that might inform relevant uncertainty analyses not quantified in this analysis.

This and other sections of the preamble address Section 317 of the Clean Air Act on 

economic analysis. Section IX.L addresses Section 321 of the Clean Air Act on employment 

analysis. The total monetized benefits and costs of the program are summarized in Section IX.K 

for the preferred alternative and in Section X for all alternatives. 

A. Conceptual Framework 

The HD Phase 2 proposed standards would implement both the 2007 Energy

Independence and Security Act requirement that NHTSA establish fuel efficiency standards for 

medium- and heavy-duty vehicles and the Clean Air Act requirement that EPA adopt 

technology-based standards to control pollutant emissions from motor vehicles and engines 

contributing to air pollution that endangers public health and welfare. NHTSA’s statutory

mandate is intended to further the agency’s long-standing goals of reducing U.S. consumption 

and imports of petroleum energy to improve the nation’s energy security. 

From an economics perspective, government actions to improve our nation’s energy

security and to protect our nation from the potential threats of climate change address 

“externalities,” or economic consequences of decisions by individuals and businesses that extend 

beyond those who make these decisions. For example, users of transportation fuels increase the 

entire U.S. economy’s risk of having to make costly adjustments due to rapid increases in oil 

prices, but these users generally do not consider such costs when they decide to consume more

fuel. 

Similarly, consuming transportation fuel also increases emissions of greenhouse gases 

and other more localized air pollutants that occur when fuel is refined, distributed, and 

consumed. Some of these emissions increase the likelihood and severity of potential climaterelated economic damages, and others cause economic damages by adversely affecting human 

health. The need to address these external costs and other adverse effects provides a wellestablished economic rationale that supports the statutory direction given to government agencies 

to establish regulatory programs that reduce the magnitude of these adverse effects at reasonable 

costs. 

The proposed Phase 2 standards would require manufacturers of new heavy-duty

vehicles, including trailers (HDVs), to improve the fuel efficiency of the products that they

produce. As HDV users purchase and operate these new vehicles, they would consume 

significantly less fuel, in turn reducing U.S. petroleum consumption and imports as well as 

emissions of GHGs and other air pollutants. Thus, as a consequence of the agencies’ efforts to 

meet our statutory obligations to improve U.S. energy security and EPA’s obligation to issue 

standards “to regulate emissions of the deleterious pollutant... from motor vehicles” that 
Page 608 of 850

endangers public health and welfare,634 the proposed fuel efficiency and GHG emission 

standards would also reduce HDV operators’ outlays for fuel purchases. These fuel savings are 

one measure of the proposed rule’s effectiveness in promoting NHTSA’s statutory goal of 

conserving energy, as well as EPA’s obligation to assess the cost of standards under section 202 

(a) (1) and (2) of the Clean Air Act. Although these savings are not the agencies’ primary

motivation for adopting higher fuel efficiency standards, these substantial fuel savings represent 

significant additional economic benefits of this proposal.

Potential savings in fuel costs would appear to offer HDV buyers strong incentives to pay

higher prices for vehicles that feature technology or equipment that reduces fuel consumption. 

These potential savings would also appear to offer HDV manufacturers similarly strong 

incentives to produce more fuel-efficient vehicles. Economic theory suggests that interactions 

between vehicle buyers and sellers in a normally-functioning competitive market would lead 

HDV manufacturers to incorporate all technologies that contribute to lower net costs into the 

vehicles they offer, and buyers to purchase them willingly. Nevertheless, many readily available 

technologies that appear to offer cost-effective increases in HDV fuel efficiency (when evaluated 

over their expected lifetimes using conventional discount rates) have not been widely adopted, 

despite their potential to repay buyers’ initial investments rapidly. 

This economic situation is commonly known as the “energy efficiency gap” or “energy

paradox.” This situation is perhaps more challenging to understand with respect to the heavyduty sector versus the light-duty vehicle sector. Unlike light-duty vehicles – which are 

purchased and used mainly by individuals and households – the vast majority of HDVs are 

purchased and operated by profit-seeking businesses for which fuel costs represent a substantial 

operating expense. Nevertheless, on the basis of evidence reviewed below, the agencies believe 

that a significant number of fuel efficiency improving technologies would remain far less widely 

adopted in the absence of these proposed standards. 

Economic research offers several possible explanations for why the prospect of these 

apparent savings might not lead HDV manufacturers and buyers to adopt technologies that 

would be expected to reduce HDV operating costs. Some of these explanations involve failures 

of the HDV market for reasons other than the externalities caused by producing and consuming 

fuel. These include situations where information about the performance of fuel economy 

technologies is incomplete, costly to obtain, or available only to one party to a transaction (or 

“asymmetrical”), as well as behavioral rigidities in either the HDV manufacturing or HDVoperating industries, such as standardized or inflexibly administered operating procedures, or 

requirements of other regulations on HDVs. Other explanations for the limited use of apparently 

cost-effective technologies that do not involve market failures include HDV operators’ concerns 

about the performance, reliability, or maintenance requirements of new technology under the 

demands of everyday use, uncertainty about the fuel savings they will actually realize, and 

questions about possible effects on carrying capacity or other aspects of HDVs’ utility. 

 

634 State of Massachusetts v. EPA, 549 U.S. at 533.
Page 609 of 850

In the HD Phase 1 rulemaking (which, in contrast to these proposed standards, did not 

apply to trailers), the agencies raised five hypotheses that might explain this energy efficiency

gap or paradox: 

 Imperfect information in the new vehicle market: information available to prospective 

buyers about the effectiveness of some fuel-saving technologies for new vehicles may

be inadequate or unreliable. If reliable information on their effectiveness in reducing 

fuel consumption is unavailable or difficult to obtain, HDV buyers will 

understandably be reluctant to pay higher prices to purchase vehicles equipped with 

unproven technologies.

 Imperfect information in the resale market: buyers in the used vehicle market may not 

be willing to pay adequate premiums for more fuel efficient vehicles when they are 

offered for resale to ensure that buyers of new vehicles can recover the remaining 

value of their original investment in higher fuel efficiency. The prospect of an 

inadequate return on their original owners’ investments in higher fuel efficiency may

contribute to the short payback periods that buyers of new vehicles appear to 

demand.635 

 Principal-agent problems causing split incentives: an HDV buyer may not be directly 

responsible for its future fuel costs, or the individual who will be responsible for fuel 

costs may not participate in the HDV purchase decision. In these cases, the signal to 

invest in higher fuel efficiency normally provided by savings in fuel costs may not be 

transmitted effectively to HDV buyers, and the incentives of HDV buyers and fuel 

buyers will diverge, or be “split.” The trailers towed by heavy-duty tractors, which 

are typically not supplied by the tractor manufacturer or seller, present an obvious 

potential situation of split incentives that was not addressed in the HD Phase 1 

rulemaking, but it may apply in this rulemaking. If there is inadequate pass-through 

of price signals from trailer users to their buyers, then low adoption of fuel-saving 

technologies may result.

 Uncertainty about future fuel cost savings: HDV buyers may be uncertain about 

future fuel prices, or about maintenance costs and reliability of some fuel efficiency

technologies. Buyers may react to this uncertainty by implicitly discounting potential 

future savings at rates above discount rates used in this analysis. In contrast, the costs 

of fuel-saving or maintenance-reducing technologies are immediate and thus not 

subject to discounting. In this situation, potential variability about buyers’ expected 

returns on capital investments to achieve higher fuel efficiency may shorten the 

 

635 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 2010”). 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 (accessed September 10, 2010).
Page 610 of 850

payback period – the time required to repay those investments – they demand in order 

to make them.

 Adjustment and transactions costs: potential resistance to new technologies –

stemming, for example, from drivers’ reluctance or slowness to adjust to changes in 

the way vehicles operate – may slow or inhibit new technology adoption. If a 

conservative approach to new technologies leads HDV buyers to adopt them slowly, 

then successful new technologies would be adopted over time without market 

intervention, but only with potentially significant delays in achieving the fuel saving, 

environmental, and energy security benefits they offer. There also may be costs 

associated with training drivers to realize 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 these technologies. 

Some of these explanations imply failures in the private market for fuel-saving 

technology beyond the externalities caused by producing and consuming fuel, while others 

suggest that complications in valuing or adapting to technologies that reduce fuel consumption 

may partly explain buyers’ hesitance to purchase more fuel-efficient vehicles. In either case, 

adopting this proposed rule would provide regulatory certainty and generate important economic 

benefits in addition to reducing externalities. 

Since the HD Phase 1 rulemaking, new research has provided further insight into 

potential barriers to adoption of fuel-saving technologies. Several studies utilized focus groups 

and interviews involving small numbers of participants, who were people with time and 

inclination to join such studies, rather than selected at random.636 As a result, the information 

from these groups is not necessarily representative of the industry as a whole. While these 

studies cannot provide conclusive evidence about how all HDV buyers make their decisions, 

they do describe issues that arise for those that participated.

One common theme that emerges from these studies is the inability of HDV buyers to 

obtain reliable information about the fuel savings, reliability, and maintenance costs of 

technologies that improve fuel efficiency. In many product markets, such as consumer 

electronics, credible reviews and tests of product performance are readily available to potential 

buyers. In the trucking industry, however, the performance of fuel-saving technology is likely to 

depend on many firm-specific attributes, including the intensity of HDV use, the typical distance

and routing of HDV trips, driver characteristics, road conditions, regional geography and traffic 

patterns.

 

636 Klemick, Heather, Elizabeth Kopits, Keith Sargent, and Ann Wolverton (2014). “Heavy-Duty Trucking and the 

Energy Efficiency Paradox.” US EPA NCEE Working Paper Series. Working Paper 14-02; Roeth, Mike, Dave 

Kircher, Joel Smith, and Rob Swim (2013). “Barriers to the Increased Adoption of Fuel Efficiency Technologies in 

the North American On-Road Freight Sector.” NACFE report for the International Council on Clean Transportation; 

Aarnink, Sanne, Jasper Faber, and Eelco den Boer (2012). “Market Barriers to Increased Efficiency in the European 

On-road Freight Sector.” CE Delft report for the International Council on Clean Transportation. 
Page 611 of 850

As a result, businesses that operate HDVs have strong preferences for testing fuel-saving 

technologies “in-house” because they are concerned that their patterns of vehicle use may lead to 

different results from those reported in published information. Businesses with less capability to 

do in-house testing often seek information from peers, yet often remain skeptical of its 

applicability due to differences in the nature of their operations. One source of imperfect 

information is the lack of availability of certain technologies from preferred suppliers. HDV 

buyers often prefer to have technology or equipment installed by their favored original 

equipment manufacturers. However, some technologies may not be available through these 

preferred sources, or may be available only as after-market installations from third parties 

(Aarnink et al. 2012, Roeth et al. 2013).

Although these studies appear to show that information in the new HDV market is often 

limited or viewed as unreliable, the evidence for imperfect information in the market for used 

HDVs is mixed. On the one hand, some studies noted that fuel-saving technology is often not 

valued or demanded in the used vehicle market, because of imperfect information about its 

benefits, or greater mistrust of its performance among buyers in the used vehicle market than 

among buyers of new vehicles. The lack of demand might also be due to the intended use of the 

used HDV, which may not require or reward the presence of certain fuel-saving technologies. In 

other cases, however, fuel-saving technology can lead to a premium in the used market, as for 

instance to meet the more stringent requirements for HDVs operating in California.

All of the recent research identifies split incentives, or principal-agent problems, as a 

potential barrier to technology adoption. These occur when those responsible for investment 

decisions are different from the main beneficiaries of the technology. For instance, businesses 

that own and lease trailers to HDV operators may not have an incentive to invest in trailerspecific fuel-saving technology, since they do not collect the savings from the lower fuel costs 

that result. Vernon and Meier (2012) estimate that 23 percent of trailers may be exposed to this 

kind of principal-agent problem, although they do not quantify its financial significance.637

Split incentives can also exist when the HDV driver is not responsible for paying fuel 

costs. Some technologies require additional effort, training, or changes in driving behavior to 

achieve their promised fuel savings; drivers who do not pay for fuel may be reluctant to 

undertake those changes, thus reducing the fuel-saving benefits from the perspective of the 

individual or company paying for the fuel. For instance, drivers might not consistently deploy 

boat-tails equipped on trailers to improve vehicle aerodynamics.638 Vernon and Meier also 

calculate that 91 percent of HDV fuel use is subject to this form of principal-agent problem, 

although they do not estimate how much it might reduce fuel savings to those who are paying for 

the fuel.

 

637 Vernon, David and Alan Meier (2012). “Identification and quantification of principal-agent problems affecting 

energy efficiency investments and use decisions in the trucking industry.” Energy Policy, 49(C), pp. 266-273.

638 Some boat-tails are being developed with technology to open them automatically when the trailer reaches a 

suitable speed, to reduce this problem.
Page 612 of 850

The studies based on focus groups and interviews (Klemick et al. 2013, Aarnink et al. 

2012, Roeth et al. 2013) provide mixed evidence on the severity of the split-incentive problem. 

Focus groups often do identify diverging incentives between drivers and the decision-makers 

responsible for purchasing vehicles, and economics literature recognizes that this split incentive 

can be a barrier to adopting new technology. Aarnink et al. (2012) and Roeth et al. (2013) cite 

examples of split incentives involving trailers and fuel surcharges, although the latter also cites 

other examples where these same issues do not lead to split incentives. 

In an effort to minimize problems that can arise form split incentives, many businesses 

that operate HDVs also train drivers in the use of specific technologies or to modify their driving 

behavior in order to improve fuel efficiency, while some also offer financial incentives to their 

drivers to conserve fuel. All of these options can help to reduce the split incentive problem, 

although they may not be effective where it arises from different ownership of combination 

tractors and trailers. 

Uncertainty about future costs for fuel and maintenance, or about the reliability of new 

technology, also appears to be a significant obstacle that can slow the adoption of fuel-saving 

technologies. These examples illustrate the problem of uncertain or unreliable information about 

the actual performance of fuel efficiency technology discussed above. In addition, businesses 

that operate HDVs may be concerned about how reliable new technologies will prove to be on 

the road, and whether significant additional maintenance costs or equipment malfunctions that 

result in costly downtime could occur. Roeth et al. (2013) and Klemick et al. (2013) both 

document the short payback periods that HDV buyers require on their investments -- usually

about 2 years -- which may be partly attributable to these uncertainties. 

These studies also provide some support for the view that adjustment and transactions 

costs may impede HDV buyers from investing in higher fuel efficiency. As discussed above, 

several studies note that HDV buyers are less likely to select new technology when it is not 

available from their preferred manufacturers. Some technologies are only available as aftermarket additions, which can add other costs to adopting them. 

Some studies also cite driver acceptance of new equipment or technologies as a barrier to 

their adoption. HDV driver turnover is high in the U.S., and businesses that operate HDVs are 

concerned about retaining their best drivers. Therefore, they may avoid technologies that require 

significant new training or adjustments in driver behavior. For some technologies that can be 

used to meet the proposed standards, such as automatic tire inflation systems, training costs are 

likely to be minimal. Other technologies such as stop-start systems, however, may require 

drivers to adjust their expectations about vehicle operation, and it is difficult for the agencies to 

anticipate how drivers will respond to such changes.639 

 

639 The distinction between simply requiring drivers (or mechanics) to adjust their expectations and compromises in 

vehicle performance or utility is subtle. While the former may not impose significant compliance costs in the long 

run, the latter would represent additional economic costs of complying with the standard.
Page 613 of 850

In addition to these factors, the studies considered other possible explanations for HDV 

buyers’ apparent reluctance or slowness to invest in fuel-saving equipment or technology. 

Financial constraints – access to lending sources willing to finance purchases of more expensive 

vehicles – do not appear to be a problem for the medium- and large-sized businesses 

participating in Klemick et al.’s (2013) study. However, Roeth et al. (2013) noted that access to 

capital can be a significant challenge to smaller or independent businesses, and that price is 

always a concern to buyers. In general, businesses that operate HDVs face a range of competing 

uses for available capital other than investing in fuel-saving technologies, and may assign higher 

priority to these other uses, even when investing in higher fuel efficiency HDVs appears to 

promise adequate financial returns. 

Other potentially important barriers to the adoption of measures that improve fuel 

efficiency may arise from “network externalities,” where the benefits to new users of a 

technology depend on how many others have already adopted it. One example where network 

externalities seem likely to arise is the market for natural gas-fueled HDVs: the limited 

availability of refueling stations may reduce potential buyers’ willingness to purchase natural 

gas-fueled HDVs, while the small number of such HDVs in-use does not provide sufficient 

economic incentive to construct more natural gas refueling stations. 

Some businesses that operate HDVs may also be concerned about the difficulty in 

locating repair facilities or replacement parts, such as single-wide tires, wherever their vehicles 

operate. When a technology has been widely adopted, then it is likely to be serviceable even in 

remote or rural places, but until it becomes widely available, its early adopters may face 

difficulties with repairs or replacements. By accelerating the widespread adoption of these 

technologies, the proposed standards may assist in overcoming these difficulties.

As discussed previously, the lack of availability of fuel-saving technologies from 

preferred manufactures can also be a significant barrier to adoption (Roeth et al. 2013). 

Manufacturers may be hesitant to offer technologies for which there is not strong demand, 

especially if the technologies require significant research and development expenses and other 

costs of bringing the technology to a market of uncertain demand. 

Roeth et al. (2013) also noted that it can take years, and sometimes as much as a decade, 

for a specific technology to become available from all manufacturers. Many manufacturers 

prefer to observe the market and follow other manufacturers rather than be the first to market 

with a specific technology. The “first-mover disadvantage” has been recognized in other 

research where the “first-mover” pays a higher proportion of the costs of developing technology, 

but loses the long-term advantage when other businesses follow quickly.

640

 In this way, there 

 

640 Blumstein, Carl and Margaret Taylor (2013). “Rethinking the Energy-Efficiency Gap: Producers, Intermediaries, 

and Innovation,” Energy Institute at Haas Working Paper 243, University of California at Berkeley; Tirole, Jean 

(1998). The Theory of Industrial Organization. Cambridge, MA: MIT Press, pp.400, 402. This first-mover 

disadvantage must large enough to overcome the incentive normally offered by the potential to for first movers to 

earn unusually high (but temporary) profit levels. 
Page 614 of 850

may be barriers to innovation on the supply side that result in lower adoption rates of fuelefficiency technology than would be optimal. 

In summary, the agencies recognize that businesses that operate HDVs are under 

competitive pressure to reduce operating costs, which should compel HDV buyers to identify and 

rapidly adopt cost-effective fuel-saving technologies. Outlays for labor and fuel generally 

constitute the two largest shares of HDV operating costs, depending on the price of fuel, distance 

traveled, type of HDV, and commodity transported (if any), so businesses that operate HDVs 

face strong incentives to reduce these costs.641,642

However, the short payback periods that buyers of new HDVs appear to require suggest 

that some combination of uncertainty about future cost savings, transactions costs, and 

imperfectly functioning markets impedes this process. Markets for both new and used HDVs

may face these problems, although it is difficult to assess empirically the degree to which they 

actually do. Even if the benefits from widespread adoption of fuel-saving technologies exceed 

their costs, their use may remain limited or spread slowly because their early adopters bear a 

disproportionate share of those costs. In this case, the proposed standards may help to overcome 

such barriers by ensuring that these measures would be widely adopted.

Providing information about fuel-saving technologies, offering incentives for their 

adoption, and sharing HDV operators’ real-world experiences with their performance through 

voluntary programs such as EPA’s SmartWay Transport Partnership should assist in the adoption 

of new cost-saving technologies. Nevertheless, other barriers that impede the diffusion of new 

technologies are likely to remain. Buyers who are willing to experiment with new technologies 

expect to find cost savings, but those savings may be difficult to verify or replicate. As noted 

previously, because benefits from employing these technologies are likely to vary with the 

characteristics of individual routes and traffic patterns, buyers of new HDVs may find it difficult 

to identify or verify the effects of fuel-saving technologies in their operations. Risk-averse 

buyers may also avoid new technologies out of concerns over the possibility of inadequate 

returns on their investments, or with other possible adverse impacts. 

Some HDV manufacturers may delay in investing in the development and production of 

new technologies, instead waiting for other manufacturers to bear the risks of those investments 

first. Competitive pressures in the HDV freight transport industry can provide a strong incentive 

to reduce fuel consumption and improve environmental performance. However, not every HDV 

operator has the requisite ability or interest to access and utilize the technical information, or the 

resources necessary to evaluate this information within the context of his or her own operations.

As discussed previously, whether the technologies available to improve HDVs’ fuel 

efficiency would be adopted widely in the absence of the program is challenging to assess. To 

 

641 American Transportation Research Institute, An Analysis of the Operational Costs of Trucking, September 2013 

(Docket ID: EPA-HQ-OAR-2014-0827). 

642 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-2014-0827). 
Page 615 of 850

the extent that these technologies would be adopted in its absence, neither their costs nor their 

benefits would be attributed to the program. To account for this possibility, the agencies 

analyzed the proposed standards and the regulatory alternatives against two reference cases, or 

baselines, as described in Section X.

The first case uses a baseline that projects some improvement in fuel efficiency for new 

trailers, but no improvement in fuel efficiency for other vehicle segments in the absence of new 

Phase 2 standards. This first case is referred to as the less dynamic baseline, or Alternative 1a. 

The second case uses a baseline that projects some improvement in vehicle fuel efficiency for 

tractors, trailers, pickup trucks, and vans but not for vocational vehicles. This second case is 

referred to as the more dynamic baseline, or Alternative 1b.

The agencies will continue to explore reasons for the slow adoption of readily available 

and apparently cost-effective technologies for improving fuel efficiency. We also seek 

comments on our hypotheses about its causes, as well as data or other information that can 

inform our understanding of why this situation seems to persist. 

B. Vehicle-Related Costs Associated with the Program

(1) Technology Cost Methodology

(a) Direct Manufacturing Costs

The direct manufacturing costs (DMCs) used throughout this analysis are derived from 

several sources. Many of the tractor, vocational and trailer DMCs can be sourced to the Phase 1 

rule which, in turn, were sourced largely from a contracted study by ICF International for 

EPA.643 We have updated those costs by converting them to 2012 dollars, as described in Section 

IX.B.1.e below, and by continuing the learning effects described in the Phase 1 rule and in 

Section IX.B.1.c below. The new tractor, vocational and trailer costs can be sourced to a more 

recent study conducted by Southwest Research Institute (SwRI) under contract to NHTSA.644 

The cost methodology used by SwRI was to estimate retail costs and work backward from there 

to derive a DMC for each technology. The agencies did not agree with the approach used by

SwRI to move from retail cost to DMC as the approach was to simply divide retail costs by 2 and 

use the result as a DMC. Our research, discussed below, suggests that a divisor of 2 is too high. 

Therefore, where we have used a SwRI derived retail estimate, we have divided by our 

researched markups to arrive at many of the DMCs used in this analysis. In this way, the 

agencies have used an approach consistent with past GHG/CAFE/fuel consumption rules by

 

643 ICF International. Investigation of Costs for Strategies to Reduce Greenhouse Gas Emissions for Heavy-Duty 

On-Road Vehicles. July 2010.

644 Schubert, R., Chan, M., Law, K. (2015). Commercial Medium- and Heavy-Duty (MD/HD) Truck Fuel Efficiency 

Cost Study. Washington, DC: National Highway Traffic Safety Administration.
Page 616 of 850

dividing estimated retail prices by our estimated retail price equivalent (RPE) markups to derive 

an appropriate DMC for each technology. We describe our RPEs in Section IX.B.1.b, below. 

For HD pickups and vans, we have relied primarily on the Phase 1 rule and the recent 

light-duty 2017-2025 model year rule since most technologies expected on these vehicles are, in 

effect, the same as those used on light-duty pickups. Many of those technology DMCs are based 

on cost teardown studies which the agencies consider to be the most robust method of cost 

estimation. However, because most of the HD versions of those technologies are expected to be 

more costly than their light-duty counterparts, we have scaled upward most of the light-duty 

DMCs for this analysis. We have also used some costs developed under contract to NHTSA by

SwRI.

645

Importantly, in our methodology, all technologies are treated as being sourced from a 

supplier rather than being developed and produced in-house. As a result, some portion of the 

total indirect costs of making a technology or system—those costs incurred by the supplier for 

research, development, transportation, marketing etc.—are contained in the sales price to the 

engine and/or vehicle/trailer manufacturer (i.e., the original equipment manufacturer (OEM)). 

That sale price paid by the OEM to the supplier is the DMC we estimate. 

We present the details—sources, DMC values, scaling from light-duty values, markups, 

learning effects, adoption rates—behind all our costs in Chapter 2 of the draft RIA.

(b) Indirect Costs

To produce a unit of output, engine and truck manufacturers incur direct and indirect 

costs. Direct costs include cost of materials and labor costs. Indirect costs are all the costs 

associated with producing the unit of output that are not direct costs – for example, they may be 

related to production (such as research and development [R&D]), corporate operations (such as 

salaries, pensions, and health care costs for corporate staff), or selling (such as transportation, 

dealer support, and marketing). Indirect costs are generally recovered by allocating a share of 

the costs to each unit of good sold. Although it is possible to account for direct costs allocated to 

each unit of good sold, it is more challenging to account for indirect costs allocated to a unit of 

goods sold. To make a cost analysis process more feasible, markup factors, which relate total 

indirect costs to total direct costs, have been developed. These factors are often referred to as 

retail price equivalent (RPE) multipliers.

While the agencies have traditionally used RPE multipliers to estimate indirect costs, in 

recent GHG/CAFE/fuel consumption rules RPEs have been replaced in the primary analysis with 

indirect cost multipliers (ICMs). ICMs differ from RPEs in that they attempt to estimate not all 

indirect costs incurred to bring a product to point of sale, but only those indirect costs that 

change as a result of a government action or regulatory requirement. As such, some indirect 

costs, notably health and retirement benefits of retired employees, among other indirect costs, 

 

645 Schubert, R., Chan, M., Law, K. (2015). Commercial Medium- and Heavy-Duty (MD/HD) Truck Fuel Efficiency 

Cost Study. Washington, DC: National Highway Traffic Safety Administration.
Page 617 of 850

would not be expected to change due to a government action and, therefore, the portion of the 

RPE that covered those costs does not change. 

Further, the ICM is not a “one-size-fits-all” markup as is the traditional RPE. With 

ICMs, higher complexity technologies like hybridization or moving from a manual to automatic 

transmission may require higher indirect costs—more research and development, more 

integration work, etc.—suggesting a higher markup. Conversely, lower complexity technologies 

like reducing friction or adding passive aero features may require fewer indirect costs thereby 

suggesting a lower markup.

Notably, ICMs are also not a simple multiplier as are traditional RPEs. The ICM is 

broken into two parts—warranty related and non-warranty related costs. The warranty related 

portion of the ICM is relatively small while the non-warranty portion represents typically over 95 

percent of indirect costs. These two portions are applied to different DMC values to arrive at 

total costs (TC). The warranty portion of the markup is applied to a DMC that decreases yearover-year due to learning effects (described below in Section IX.B.1.c). 646

 As learning effects 

decrease the DMC with production volumes, it makes sense that warranty costs would decrease 

since those parts replaced under warranty should be less costly. In contrast, the non-warranty 

portion of the markup is applied to a static DMC year-over-year resulting in static indirect costs. 

This is logical since the production plants and transportation networks and general overhead 

required to build parts, market them, deliver them and integrate them into vehicles do not 

necessarily decrease in cost year-over-year. Because the warranty and non-warranty portions of 

the ICM are applied differently, one cannot compare the markup itself to the RPE to determine 

which markup would result in higher indirect cost estimates, at least in the time periods typically

considered in our rules (four to ten years).

The agencies are concerned that some potential costs associated with this rulemaking 

may not be adequately captured by our ICMs. ICMs are estimated based on a few specific 

technologies and these technologies may not be representative of the changes actually made to 

meet the proposed requirements. Specifically, we may not have adequately estimated the costs 

for accelerated R&D or potential reliability issues with advanced technologies required by

Alternative 4. There is a great deal of uncertainty regarding these costs, and this makes estimates 

for this alternative of particular concern. We request comment on that aspect of our estimates

and on all aspects of our indirect cost estimation approach.

We provide more details on our ICM approach and the markups used for each technology

in Chapter 2.12 of the draft RIA.

 

646 We note that the labor portion of warranty repairs does not decrease due to learning. However, we do not have 

data to separate this portion and so we apply learning to the entire warranty cost. Because warranty costs are a small 

portion of overall indirect costs, this has only a minor impact on the analysis.
Page 618 of 850

(c) Learning Effects on Direct and Indirect Costs

For some of the technologies considered in this analysis, manufacturer learning effects 

would be expected to play a role in the actual end costs. The “learning curve” or “experience 

curve” describes the reduction in unit production costs as a function of accumulated production 

volume. In theory, the cost behavior it describes applies to cumulative production volume 

measured at the level of an individual manufacturer, although it is often assumed—as both 

agencies have done in past regulatory analyses—to apply at the industry-wide level, particularly

in industries that utilize many common technologies and component supply sources. Both 

agencies believe there are indeed many factors that cause costs to decrease over time. Research 

in the costs of manufacturing has consistently shown that, as manufacturers gain experience in 

production, they are able to apply innovations to simplify machining and assembly operations, 

use lower cost materials, and reduce the number or complexity of component parts. All of these 

factors allow manufacturers to lower the per-unit cost of production (i.e., the manufacturing 

learning curve).647

In this analysis, the agencies are using the same approach to learning as done in past 

GHG/CAFE/fuel consumption rules. In short, learning effects result in rapid cost reductions in 

the early years following introduction of a new technology. The agencies have estimated those 

cost reductions as resulting in 20 percent lower costs for every doubling of production volume. 

As production volumes increase, learning rates continue at the same pace but flatten 

asymptotically due to the nature of the persistent doubling of production required to realize that 

cost reduction. As such, the cost reductions flatten out as production volumes continue to 

increase. Consistent with the Phase 1 rule, we refer to these two distinct portions of the 

“learning cost reduction curve” or “learning curve” as the steeper and flatter portions of the 

curve. On that steep portion of the curve, costs are estimated to decrease by 20 percent for each 

double of production or, by proxy, in the third and then fifth year of production following 

introduction. On the flat portion of the curve, costs are estimated to decrease by 3 percent per 

year for 5 years, then 2 percent per year for 5 years, then 1 percent per year for 5 years. Also 

consistent with the Phase 1 rule, the majority of the technologies we expect would be adopted are 

considered to be on the flat portion of the learning curve meaning that the 20 percent cost 

reductions are rarely applied. The agencies request comment on this approach to estimating 

these effects, and request that commenters provide data and forward-looking information to 

support any alternative methods or specific estimates.

We provide more details on the concept of learning-by-doing and the learning effects 

applied in this analysis in Chapter 2 of the draft RIA.

 

647 See “Learning Curves in Manufacturing”, L. Argote and D. Epple, Science, Volume 247; “Toward Cost Buy 

down Via Learning-by-Doing for Environmental Energy Technologies, R. Williams, Princeton University, 

Workshop on Learning-by-Doing in Energy Technologies, June 2003; “Industry Learning Environmental and the 

Heterogeneity of Firm Performance, N. Balasubramanian and M. Lieberman, UCLA Anderson School of 

Management, December 2006, Discussion Papers, Center for Economic Studies, Washington DC.
Page 619 of 850

(d) Technology Adoption Rates and Developing Package Costs

Determining the stringency of the proposed standards involves a balancing of relevant 

factors – chiefly technology feasibility and effectiveness, costs, and lead time. For vocational 

vehicles, tractors and trailers, the agencies have projected a technology path to achieve the 

proposed standards reflecting an application rate of those technologies the agencies consider to 

be available at reasonable cost in the lead times provided. The agencies do not expect each of 

the technologies for which costs have been developed to be employed by all trucks and trailers 

across the board. Further, many of today’s vehicles are already equipped with some of the 

technologies and/or are expected to adopt them by MY2018 to comply with the HD Phase 1 

standards. Estimated adoption rates in both the reference and control cases are necessary for each 

vehicle/trailer category. The adoption rates for most technologies are zero in the reference case; 

however, for some technologies—notably aero and tire technologies—the adoption rate is not 

zero in the reference case. These reference and control case adoption rates are then applied to 

the technology costs with the result being a package cost for each vehicle/trailer category. 

For HD pickups and vans, the CAFE model determines the technology adoption rates that 

most cost effectively meet the standards being proposed. Similar to vocational vehicles, tractors 

and trailers, package costs are rarely if ever a simple sum of all the technology costs since each 

technology would be expected to be adopted at different rates. The methods for estimating 

technology adoption rates and resultant costs (and other impacts) for HD pickups and vans are 

discussed above in Section 6.

We provide details of expected adoption rates in Chapter 2 of the draft RIA. We present 

package costs both in Sections III through VI of this preamble and in more detail in Chapter 2 of 

the draft RIA.

(e) Conversion of Technology Costs to 2012 US Dollars

As noted above in Section IX.B.1, the agencies are using technology costs from many

different sources. These sources, having been published in different years, present costs in 

different year dollars (i.e., 2009 dollars or 2010 dollars). For this analysis, the agencies sought to 

have all costs in terms of 2012 dollars to be consistent with the dollars used by AEO in its 2014 

Annual Energy Outlook.648 The agencies have used the GDP Implicit Price Deflator for Gross 

Domestic Product as the converter, with the actual factors used as shown in Table IX-1.

649

 

648 U.S. Energy Information Administration, Annual Energy Outlook 2014, Early Release; Report Number 

DOE/EIA-0383ER (2014), December 16, 2013.

649 Bureau of Economic Analysis, Table 1.1.9 Implicit Price Deflators for Gross Domestic Product; as revised on 

March 27, 2014.
Page 620 of 850

Table IX-1 Implicit Price Deflators and Conversion Factors for Conversion to 2012$

2006 2007 2008 2009 2010 2011 2012 2013

Price index for GDP 94.818 97.335 99.236 100 101.211 103.199 105.002 106.588

Factor applied for 2012$ 1.107 1.079 1.058 1.050 1.037 1.017 1.000 0.985

(2) Compliance Program Costs

The agencies have also estimated additional and/or new compliance costs associated with 

the proposed standards. Normally, compliance program costs would be considered part of the 

indirect costs and, therefore, would be accounted for via the markup applied to direct 

manufacturing costs. However, since the agencies are proposing new compliance elements that 

were not present during development of the indirect cost markups used in this analysis, 

additional compliance program costs are being accounted for via a separate “line-item.” New 

research and development costs (see below) are being handled in the same way. 

The new compliance program elements included in this proposal are new powertrain 

testing within the vocational vehicle program, and an all-new compliance program where none 

has existed to date within the trailer program. Note that for HD pickups and vans, HD engines, 

vocational vehicles and tractors, the Phase 1 rule included analogous compliance program costs 

meant to account for costs incurred in the all-new compliance program placed on the regulated 

firms by that rule. Compliance program costs cover costs associated with any necessary

compliance testing and reporting to the agencies and differ somewhat by alternative since, for 

example, more manufacturers are expected to conduct powertrain testing under alternative 4 than 

under alternative 3, etc. The details behind the estimated compliance program costs are provided 

in Chapter 7 of the draft RIA. We request comment on our estimated compliance costs.

(3) Research and Development Costs

Much like the compliance program costs described above, we have estimated additional 

HDD engine, vocational vehicle and tractor R&D associated with the proposed standards that is 

not accounted for via the indirect cost markups used for these segments. Much like the Phase 1 

rule, EPA is estimating these additional R&D costs will occur over a 4-year timeframe as the 

proposed standards come into force and industry works on means to comply. After that period, 

the additional R&D costs go to $0 as R&D expenditures return to their normal levels and R&D 

costs are accounted for via the ICMs—and the RPEs behind them—used for these segments. 

Note that, due to the accelerated implementation of some technologies, alternative 4 has higher 

R&D costs than does alternative 3. The details behind the estimated R&D costs are provided in 

Chapter 7 of the draft RIA. We request comment on our estimated R&D costs.

(4) Summary of Costs of the Proposed Vehicle Programs

The agencies have estimated the costs of the proposed vehicle standards on an annual 

basis for the years 2018 through 2050, and have also estimated costs for the full model year 

lifetimes of MY2018 through MY2029 vehicles. Table IX-2 shows the annual costs of the 

proposed standards along with net present values using both 3 percent and 7 percent discount 
Page 621 of 850

rates. Table IX-3 shows the discounted model year lifetime costs of the proposed standards at 

both 3 percent and 7 percent discount rates along with sums across applicable model years.

Table IX-2 Annual Costs of the Preferred Alternative and Net Present Values at 3% and 7% Discount Rates 

using Method B and Relative to the Less Dynamic Baseline 

($Millions of 2012$) a

Calendar

Year

New

Technology

Compliance R&D Sum

2018 $116 $0 $0 $116

2019 $113 $0 $0 $113

2020 $112 $0 $0 $112

2021 $2,173 $18 $240 $2,432

2022 $2,161 $6 $240 $2,407

2023 $2,224 $6 $240 $2,470

2024 $3,455 $6 $240 $3,701

2025 $3,647 $6 $0 $3,653

2026 $3,736 $6 $0 $3,742

2027 $5,309 $6 $0 $5,315

2028 $5,334 $6 $0 $5,340

2029 $5,376 $6 $0 $5,381

2030 $5,399 $6 $0 $5,405

2035 $5,856 $6 $0 $5,862

2040 $6,316 $6 $0 $6,322

2050 $6,987 $6 $0 $6,992

NPV, 3% $85,926 $104 $759 $86,789

NPV, 7% $40,516 $56 $561 $41,133

Note:

a For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less 

dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table IX-3 Discounted MY Lifetime Costs of the Preferred Alternative using Method B and Relative to the 

Less Dynamic Baseline ($Millions of 2012$) a

Model

Year

Discounted at 3% Discounted at 7%

New

Technology

Compliance R&D Sum New

Technology

Compliance R&D Sum

2018 $104 $0 $0 $104 $91 $0 $0 $91

2019 $99 $0 $0 $99 $84 $0 $0 $84

2020 $95 $0 $0 $95 $77 $0 $0 $77

2021 $1,794 $15 $198 $2,007 $1,401 $12 $155 $1,567

2022 $1,731 $5 $193 $1,928 $1,302 $3 $145 $1,450

2023 $1,730 $4 $187 $1,921 $1,252 $3 $135 $1,390

2024 $2,610 $4 $181 $2,795 $1,818 $3 $126 $1,947

2025 $2,674 $4 $0 $2,678 $1,793 $3 $0 $1,796

2026 $2,660 $4 $0 $2,664 $1,717 $3 $0 $1,719

2027 $3,670 $4 $0 $3,673 $2,280 $2 $0 $2,283

2028 $3,580 $4 $0 $3,583 $2,141 $2 $0 $2,143

2029 $3,502 $4 $0 $3,506 $2,017 $2 $0 $2,019

Sum $24,248 $48 $759 $25,055 $15,973 $33 $561 $16,568

Note:
Page 622 of 850

a For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less 

dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

New technology costs begin in MY2018 as trailers begin to add new technology. 

Compliance costs begin with the new standards with capital cost expenditure in that year for 

building and upgrading test facilities to conduct the proposed powertrain testing in the vocational 

program. Research and development costs begin in 2021 and last for 4 years as engine, tractor 

and vocational vehicle manufacturers conduct research and development testing to integrate new 

technologies into their engines and vehicles. We request comment on all aspects of our 

technology costs, both individual technology costs and package costs, as detailed in Chapter 2 of 

the draft RIA.

C. Changes in Fuel Consumption and Expenditures 

(1) Changes in Fuel Consumption

The new GHG and fuel consumption standards would result in significant improvements 

in the fuel efficiency of affected vehicles, and drivers of those vehicles would see corresponding 

savings associated with reduced fuel expenditures. The agencies have estimated the impacts on 

fuel consumption for the proposed standards. Details behind how these changes in fuel 

consumption were calculated are presented in Section VII of this preamble and in Chapter 5 of

the draft RIA. The total number of miles that vehicles are driven each year is different under the 

regulatory alternatives than in the reference case due to the “rebound effect” (discussed below in 

Section IX.E), so the changes in fuel consumption associated with each alternative are not 

strictly proportional to differences in the fuel economy levels they require. 

The expected annual impacts on fuel consumption are shown in Table IX-4. Table IX-5

shows the MY lifetime changes in fuel consumption. The gallons shown in these tables as 

reductions in fuel consumption reflect reductions due to the proposed standards and include any 

increased consumption resulting from the rebound effect (discussed below in Section IX.E). 
Page 623 of 850

Table IX-4 Annual Fuel Consumption Reductions due to the Preferred Alternative using Method B and 

Relative to the Less Dynamic Baseline (Millions of gallons) a

Calendar

Year

Gasoline Diesel

Reference

Case

Fuel

Consumption

Reduction

%

Reduction

Reference

Case

Fuel

Consumption

Reduction

%

Reduction

2018 6,781 0 0% 45,999 74 0%

2019 6,799 0 0% 46,362 150 0%

2020 6,832 0 0% 46,768 227 0%

2021 6,884 10 0% 47,236 523 1%

2022 6,944 29 0% 47,761 894 2%

2023 7,005 57 1% 48,309 1,276 3%

2024 7,054 99 1% 48,807 1,895 4%

2025 7,113 151 2% 49,400 2,523 5%

2026 7,169 210 3% 49,967 3,152 6%

2027 7,221 291 4% 50,420 3,890 8%

2028 7,273 369 5% 50,821 4,600 9%

2029 7,332 445 6% 51,262 5,278 10%

2030 7,396 516 7% 51,792 5,924 11%

2035 7,732 801 10% 54,602 8,517 16%

2040 8,075 968 12% 58,082 10,209 18%

2050 8,806 1,127 13% 65,937 12,310 19%

Note:

a For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of 

the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table IX-5 Model Year Lifetime Fuel Consumption Reductions due to the Preferred Alternative using 

Method B and Relative to the Less Dynamic Baseline (Millions of gallons) a

Model

Year

Gasoline Diesel

Reference Fuel

Consumption

Reduction

%

Reduction

Reference Fuel

Consumption

Reduction

%

Reduction

2018 0 0 0% 33,384 754 2%

2019 0 0 0% 33,922 745 2%

2020 0 0 0% 34,575 738 2%

2021 7,128 113 2% 47,792 4,424 9%

2022 7,118 216 3% 48,112 4,568 9%

2023 7,106 317 4% 48,366 4,703 10%

2024 7,225 493 7% 49,577 7,628 15%

2025 7,376 602 8% 51,050 7,967 16%

2026 7,535 714 9% 52,420 8,289 16%

2027 7,628 982 13% 53,532 9,984 19%

2028 7,711 992 13% 54,524 10,181 19%

2029 7,769 999 13% 55,421 10,360 19%

Sum 66,596 5,430 8% 562,673 70,342 13%

Note:

a For an explanation of analytical Methods A and B, please see Section I.D; for an explanation 

of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.
Page 624 of 850

(2) Fuel Savings

We have also estimated the changes in fuel expenditures, or the fuel savings, using fuel 

prices estimated in the Energy and Information Administration’s 2014 Annual Energy

Outlook.650 As the AEO fuel price projections go through 2040 and not beyond, fuel prices 

beyond 2040 were set equal to the 2040 values. These estimates do not account for the 

significant uncertainty in future fuel prices; the monetized fuel savings would be understated if 

actual fuel prices are higher (or overstated if fuel prices are lower) than estimated. The Annual 

Energy Outlook (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 changes fuel purchasers would see. 

The pre-tax fuel savings measure the value to society of the resources saved when less fuel is 

refined and consumed. Assuming no change in fuel tax rates, the difference between these two 

columns represents the reduction in fuel tax revenues that would be received by state and federal 

governments, or about $240 million in 2021 and $5.2 billion by 2050 as shown in Table IX-6

where annual changes in monetized fuel savings are shown along with net present values using 3 

percent and 7 percent discount rates. Table IX-7 and Note:

a For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of 

the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table IX-8 show the discounted model year lifetime fuel savings using 3 percent and 7 

percent discount rates, respectively. 

 

650 U.S. Energy Information Administration, Annual Energy Outlook 2014, Early Release; Report Number 

DOE/EIA-0383ER (2014), December 16, 2013.
Page 625 of 850

Table IX-6 Annual Fuel Savings and Net Present Values at 3% and 7% Discount Rates using Method B for 

the Preferred Alternative and Relative to the Less Dynamic Baseline ($Millions of 2012$) a

Calendar

Year

Fuel Savings - Retail Fuel Savings – Untaxed Change in

Gasoline Diesel Sum Gasoline Diesel Sum Transfer

2018 $0 $261 $261 $0 $227 $227 $34

2019 $0 $540 $540 $0 $472 $472 $68

2020 $0 $834 $834 $0 $731 $731 $103

2021 $31 $1,958 $1,989 $27 $1,723 $1,750 $239

2022 $92 $3,413 $3,505 $80 $3,015 $3,095 $410

2023 $183 $4,936 $5,119 $160 $4,372 $4,532 $587

2024 $324 $7,426 $7,750 $285 $6,594 $6,879 $871

2025 $496 $10,035 $10,531 $436 $8,937 $9,372 $1,158

2026 $695 $12,683 $13,378 $613 $11,321 $11,934 $1,445

2027 $976 $15,883 $16,859 $861 $14,215 $15,076 $1,782

2028 $1,243 $18,938 $20,181 $1,099 $16,980 $18,079 $2,102

2029 $1,511 $21,974 $23,485 $1,338 $19,745 $21,083 $2,402

2030 $1,770 $24,905 $26,675 $1,571 $22,422 $23,993 $2,682

2035 $2,921 $38,047 $40,968 $2,621 $34,621 $37,242 $3,726

2040 $3,778 $48,300 $52,078 $3,427 $44,357 $47,783 $4,295

2050 $4,397 $58,241 $62,638 $3,988 $53,486 $57,474 $5,164

NPV, 3% $37,319 $506,971 $544,290 $33,603 $461,992 $495,595 $48,695

NPR, 7% $15,211 $212,373 $227,584 $13,663 $192,984 $206,646 $20,937

Note:

a For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of 

the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table IX-7 Discounted Model Year Lifetime Fuel Savings, 3% Discount Rate using Method B for the 

Preferred Alternative and Relative to the Less Dynamic Baseline ($Millions of 2012$) a

Model

Year

Fuel Savings - Retail Fuel Savings – Untaxed Change in

Gasoline Diesel Sum Gasoline Diesel Sum Transfer

2018 $0 $2,183 $2,183 $0 $1,937 $1,937 $246

2019 $0 $2,123 $2,123 $0 $1,890 $1,890 $234

2020 $0 $2,066 $2,066 $0 $1,844 $1,844 $222

2021 $258 $12,178 $12,436 $228 $10,898 $11,126 $1,310

2022 $487 $12,369 $12,856 $431 $11,094 $11,525 $1,331

2023 $700 $12,513 $13,212 $620 $11,247 $11,867 $1,346

2024 $1,067 $19,934 $21,001 $947 $17,953 $18,901 $2,100

2025 $1,277 $20,435 $21,712 $1,136 $18,441 $19,577 $2,135

2026 $1,484 $20,858 $22,342 $1,323 $18,858 $20,180 $2,161

2027 $2,001 $24,642 $26,643 $1,787 $22,319 $24,106 $2,537

2028 $1,981 $24,610 $26,592 $1,772 $22,329 $24,101 $2,491

2029 $1,957 $24,536 $26,493 $1,754 $22,298 $24,052 $2,441

Sum $11,211 $178,448 $189,659 $9,997 $161,107 $171,105 $18,554

Note:

a For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of 

the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.
Page 626 of 850

Table IX-8 Discounted Model Year Lifetime Fuel Savings, 7% Discount Rate using Method B for the 

Preferred Alternative and Relative to the Less Dynamic Baseline ($Millions of 2012$) a

Model

Year

Fuel Savings - Retail Fuel Savings – Untaxed Change in

Gasoline Diesel Sum Gasoline Diesel Sum Transfer

2018 $0 $1,529 $1,529 $0 $1,352 $1,352 $176

2019 $0 $1,428 $1,428 $0 $1,267 $1,267 $161

2020 $0 $1,331 $1,331 $0 $1,185 $1,185 $146

2021 $163 $7,538 $7,701 $143 $6,731 $6,874 $827

2022 $295 $7,383 $7,678 $260 $6,608 $6,869 $810

2023 $408 $7,200 $7,607 $361 $6,458 $6,819 $789

2024 $599 $11,055 $11,654 $531 $9,938 $10,469 $1,186

2025 $690 $10,917 $11,607 $613 $9,834 $10,447 $1,160

2026 $772 $10,734 $11,505 $687 $9,688 $10,374 $1,131

2027 $1,003 $12,215 $13,218 $894 $11,046 $11,940 $1,278

2028 $956 $11,741 $12,697 $854 $10,636 $11,490 $1,206

2029 $909 $11,269 $12,179 $814 $10,228 $11,041 $1,137

Sum $5,794 $94,339 $100,134 $5,157 $84,971 $90,128 $10,005

Note:

a For an explanation of analytical Methods A and B, please see Section I.D; for an explanation 

of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

D. Maintenance Expenditures

The agencies expect minimal increases in maintenance costs under the proposed 

standards, having estimated increased maintenance costs associated only with installation of 

lower rolling resistance tires. We expect that, when replaced, the lower rolling resistance tires 

would be replaced by equivalent performing tires throughout the vehicle lifetime. As such, the 

incremental increases in costs for lower rolling resistance tires would be incurred throughout the 

vehicle lifetime at intervals consistent with current tire replacement intervals. Those intervals 

are difficult to quantify given the variety of vehicles and operating modes within the HD 

industry. We detail the inputs used to estimate maintenance impacts in Chapter 7.3.3 of the draft 

RIA. We request comment on all aspects of the maintenance estimates. Specifically, for 

electrified vehicles (mild/strong hybrids) which are expected in alternatives 3 and 4 and in each 

vehicle category, we have not estimated any increased maintenance costs. We have heard from 

at least one source651 that strong hybrid maintenance can be higher in some ways, including 

possible battery replacement, but may also be much lower for some vehicle systems like brakes 

and general engine wear. Given the uncertainty, we have not estimated maintenance costs 

specifically for these electrified vehicles but request comment so that we might be able to 

include potential costs in the final rule. We also request comment on any other maintenance costs 

that should be considered along with supporting data.

 

651 Allison Transmission’s Responses to EPA’s Hybrid Questions, November 6, 2014.
Page 627 of 850

Table IX-9 shows the annual increased maintenance costs of the preferred alternative 

along with net present values using both 3 percent and 7 percent discount rates. Table IX-10

shows the discounted model year lifetime increased maintenance costs of the preferred 

alternative at both 3 percent and 7 percent discount rates along with sums across applicable 

model years.

Table IX-9 Annual Maintenance Expenditure Increase due to the Proposal and Net Present Values at 3% 

and 7% Discount Rates using Method B and Relative to the Less Dynamic Baseline ($Millions of 2012$) a

Calendar

Year

Maintenance

Expenditure

Increase

2018 $6

2019 $11

2020 $16

2021 $28

2022 $39

2023 $50

2024 $64

2025 $78

2026 $90

2027 $104

2028 $116

2029 $127

2030 $127

2035 $127

2040 $127

2050 $127

NPV, 3% $1,796

NPV, 7% $860

Note:

a For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less 

dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.
Page 628 of 850

Table IX-10 Discounted MY Lifetime Maintenance Expenditure Increase due to the Proposal using Method 

B and Relative to the Less Dynamic Baseline ($Millions of 2012$) a

Model

Year

3% Discount

Rate

7% Discount

Rate

2018 $51 $36

2019 $49 $33

2020 $47 $31

2021 $90 $57

2022 $89 $54

2023 $89 $52

2024 $112 $63

2025 $113 $61

2026 $102 $53

2027 $116 $58

2028 $111 $54

2029 $101 $47

Sum $1,071 $600

Note:

a For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less 

dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

E. Analysis of the Rebound Effect

The “rebound effect” has been defined a number of ways in the literature, and one 

common definition states that the rebound effect is the increase in demand for an energy service 

when the cost of the energy service is reduced due to efficiency improvements.

652,653,654 In the 

context of heavy-duty vehicles (HDVs), this can be interpreted as an increase in HDV fuel 

consumption resulting from more intensive vehicle use in response to increased vehicle fuel 

efficiency.

655 Although much of this vehicle use increase is likely to take the form of increases 

in the number of miles vehicles are driven, it can also take the form of increases in the loaded 

weight at which vehicles operate or changes in traffic and road conditions vehicles encounter as 

operators alter their routes and schedules in response to improved fuel efficiency. Because this 

more intensive use consumes fuel and generates emissions, it reduces the fuel savings and 

 

652 Winebrake, J.J., Green, E.H., Comer, B., Corbett, J.J., Froman, S., 2012. Estimating the direct rebound effect for 

on-road freight transportation. Energy Policy 48, 252-259.

653 Greene, D.L., Kahn, J.R., Gibson, R.C., 1999, “Fuel economy rebound effect for U.S. household vehicles”, The 

Energy Journal, 20.

654 For a discussion of the wide range of definitions found in the literature, see Appendix D: Discrepancy in 

Rebound Effect Definitions, in EERA (2014), “Research to Inform Analysis of the Heavy-Duty vehicle Rebound 

Effect”, Excerpts of Draft Final Report of Phase 1 under EPA contract EP-C-13-025. (Docket ID: EPA-HQ-OAR2014-0827). See also Greening, L.A., Greene, D.L., Difiglio, C., 2000, “Energy efficiency and consumption — the 

rebound effect — a survey”, Energy Policy, 28, 389-401.

655 We discuss other potential rebound effects in section IX.D.3, such as the indirect and economy-wide rebound 

effects. Note also that there is more than one way to measure HDV energy services and vehicle use. The agencies’ 

analyses use VMT as a measure (as discussed below); other potential measures include ton-miles, cube-miles, and 

fuel consumption.
Page 629 of 850

avoided emissions that would otherwise be expected to result from the increases in fuel 

efficiency this rulemaking proposes. 

Unlike the light-duty vehicle (LDV) rebound effect, the HDV rebound effect has not been 

extensively studied. According to a 2010 HDV report published by the National Research 

Council of the National Academies (NRC)656, it is “not possible to provide a confident measure 

of the rebound effect,” yet NRC concluded that a HDV rebound effect probably exists and that,

“estimates of fuel savings from regulatory standards will be somewhat misestimated if the 

rebound effect is not considered.” Although we believe the HDV rebound effect needs to be 

studied in more detail, we have nevertheless attempted to capture its potential effect in our 

analysis of these proposed rules, rather than to await further study. We have elected to do so 

because the magnitude of the rebound effect is an important determinant of the actual fuel 

savings and emission reductions that are likely to result from adopting stricter fuel efficiency and 

GHG emission standards. 

In our analysis and discussion below, we focus on one widely-used metric to estimate the 

rebound effect associated with all types of more intensive vehicle use, the increase in vehicle 

miles traveled (VMT) that results from improved fuel efficiency. VMT can often provide a 

reasonable approximation for all types of more intensive vehicle use. For simplicity, we refer to 

this as “the VMT rebound effect” or “VMT rebound” throughout this section, although we 

acknowledge that it is an approximation to the rebound effect associated with all types of more 

intensive vehicle use. The agencies use our VMT rebound estimates to generate VMT inputs 

that are then entered into the EPA MOVES national emissions inventory model and the Volpe 

Center’s HD CAFE model. Both of these models use these inputs along with many others to 

generate projected emissions and fuel consumption changes resulting from each of the regulatory 

alternatives analyzed.

Using VMT rebound to approximate the fuel consumption impact from all types of more 

intensive vehicle use may not be completely accurate. Many factors other than distance traveled 

– for example, a vehicle’s loaded weight – play a role in determining its fuel consumption, so it 

is also important to consider how changes in these factors are correlated with variation in vehicle 

miles traveled. Empirical estimates of the effect of weight on HDV fuel consumption vary, but 

universally show that loaded weight has some effect on fuel consumption that is independent of 

distance traveled. Therefore, the product of vehicle payload and miles traveled, which typically 

is expressed in units of “ton-miles” or “ton-kilometers”, has also been considered as a metric to 

approximate the rebound effect. Because this metric’s value depends on both payload and 

distance, it is important to note that changes in these two variables can have different impacts on

HDV fuel consumption. This is because the fuel consumed by HDV freight transport is 

determined by several vehicle attributes including engine and accessory efficiencies, 

 

656 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,” 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).
Page 630 of 850

aerodynamic characteristics, tire rolling resistance and total vehicle mass—including payload

carried, if any.

Other factors such as vehicle route and traffic patterns can also affect how each of these

vehicle attributes contributes to the overall fuel consumption of a vehicle. While it seems 

intuitive that if all of these other conditions remain constant, a vehicle driving the same route and 

distance twice will consume twice as much fuel as driving that same route once. However,

because of the other vehicle attributes, it is less intuitive how a change in vehicle payload would 

affect vehicle fuel consumption. We request comment on how the agencies should consider the 

relationship between changes in vehicle miles traveled, changes in vehicle ton-miles achieved, 

and overall fuel consumption when considering how best to measure the rebound effect.

Because the factors influencing HDV VMT rebound are generally different from those 

affecting LDV VMT rebound, much of the research on the LDV sector is likely to not apply to 

the HDV sector. For example, the owners and operators of LDVs would likely view the costs 

and benefits associated with changes in their personal vehicle’s fuel efficiency very differently

than a HDV fleet owner or operator would view the costs and benefits (e.g., profits, offering 

more competitive prices for services) associated with changes in their HDVs’ fuel efficiency. 

The potential exception is HD pickups and vans, which share some similarities with LDVs. As 

discussed in the 2010 NRC HD report, one difference from the LDV case is that when 

calculating the change in HDV costs that causes the rebound effect, it is more important to 

consider all components of HDV operating costs. The costs of labor and fuel generally

constitute the two largest shares of HDV operating costs, depending on the price of petroleum, 

distance traveled, type of vehicle, and commodity transported (if any).657,658 Equipment 

depreciation costs associated with the purchase or lease of an HDV are another significant 

component of total operating costs. Even when HDV purchases involve upfront, one-time 

payments, HDV operators must recover the depreciation in the value of their vehicles resulting 

from their use, so this is likely to be considered as an operating cost they will attempt to pass on 

to final consumers of HDV operator services. 

Estimates of the impact of fuel efficiency standards on HDV VMT, and hence fuel 

consumption, should account for changes in all of these components of HDV operating costs. 

The higher the net savings in total operating costs is, the higher the expected rebound effect 

would be. Conversely, if higher HDV purchase costs outweigh future cost savings and total 

operating costs increase, HDV costs could rise, which would likely result in a decrease in HDV

VMT. In theory, other cost changes resulting from any requirement to achieve higher fuel 

efficiency, such as changes in maintenance costs or insurance rates, should also be taken into 

account, although information on these elements of HDV operating costs is extremely limited. 

In this analysis, the agencies adapt estimates of the VMT rebound effect to project the response 

of HDV use to the estimated changes in total operating costs that result from the proposed Phase 

 

657 American Transportation Research Institute, An Analysis of the Operational Costs of Trucking, September 2013. 

658 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. 
Page 631 of 850

2 standards. We seek comment and data on how our proposed standards could impact these and 

other types of HDV operating costs, as well as on our procedure for adapting the VMT rebound 

effect to estimate the response of HDV use to changes in total operating costs. 

Since businesses are profit-driven, one would expect their decisions to be based on the 

costs and benefits of different operating decisions, both in the near-term and long-term. 

Specifically, one would expect commercial HDV operators to take into account changes in 

overall operating costs per mile when making decisions about HDV use and setting rates they

charge for their services. If demand for those services is sensitive to the rates HDV operators

charge, HDV VMT could change in response to the effect of higher fuel efficiency on the rates 

HDV operators charge. If demand for HDV services is insensitive to price (e.g., due to lack of 

good substitutes), however, or if changes in HDV operating costs due to the proposed standards 

are not passed on to final consumers of HDV operator services, the proposed standards may have 

a limited impact on HDV VMT.

The following sections describe the factors affecting the magnitude of HDV VMT 

rebound; review the econometric and other evidence related to HDV VMT rebound; and 

summarize how we estimated the HDV rebound effect for this proposal. 

(1) Factors Affecting the Magnitude of HDV VMT Rebound 

The magnitude and timing of HDV VMT rebound result from the interaction of many 

different factors.659 Fuel savings resulting from fuel efficiency standards may cause HDV

operators and their customers to change their patterns of HDV use and fuel consumption in a 

variety of ways. For example, HDV operators may pass on the fuel cost savings to their 

customers by decreasing prices for shipping products or providing services, which in turn could 

stimulate more demand for those products and services (e.g., increases in freight output), and 

result in higher VMT. Alternatively, HDV operators could simply use fuel savings to spend 

more on other costs such as driver labor or vehicle capital (e.g., holding freight output constant), 

which may not result in higher VMT. As discussed later in this section, HDV VMT rebound 

estimates determined via other proxy elasticities vary widely, but in no case has there been an 

estimate that fully offsets the fuel saved due to efficiency improvements (i.e., no rebound effect 

greater than or equal to 100 percent). 

If fuel cost savings are passed on to the HDV operators’ customers (e.g., logistics 

businesses, manufacturers, retailers, municipalities, utilities consumers), those customers might

reorganize their logistics and distribution networks over time to take advantage of lower 

operating costs. For example, customers might demand more frequent shipments, ship products 

or materials over longer distances, or shift traffic to HDVs from other shipping modes such as 

rail, barge or air. In addition, customers might choose to reduce their number of warehouses, 

 

659 These factors are discussed more fully in a report to EPA from EERA, which illustrates in a series of diagrams 

the complex system of decisions and decision-makers that could influence the magnitude and timing of the rebound 

effect. See Sections 2.2.2, 2.2.3, 2.2.4, and 2.3 in EERA (2014), “Research to Inform Analysis of the Heavy-Duty 

Vehicle Rebound Effect”, Excerpts of Draft Final Report of Phase 1 under EPA contract EP-C-13-025. 
Page 632 of 850

reduce shipment rates or make smaller but more frequent shipments, all of which could lead to 

an increase in HDV VMT. Ultimately, fuel cost savings could ripple through the entire 

economy, thus increasing demand for goods and services shipped by trucks, and therefore 

increase HDV VMT due to increased gross domestic product (GDP).

Conversely, if fuel efficiency standards lead to net increases in the total costs of HDV 

operation because fuel cost savings do not fully offset the increase in HDV purchase prices and 

associated depreciation costs, then the price of HDV services could rise. This is likely to spur a 

decrease in HDV VMT, and perhaps a shift to alternative shipping modes. These effects could 

also ripple through the economy and affect GDP. 

It is also important to note that any increase in HDV VMT resulting from our proposed 

standards may be offset, to some extent, by a decrease in VMT by older HDVs. This may occur 

if lower fuel costs resulting from our standards cause multi-vehicle fleet operators to shift VMT 

to newer, more efficient HDVs in their fleet or cause operators with newer, more efficient HDVs 

to be more successful at winning contracts than operators with older HDVs.

Also, as discussed in Chapter 8.3.3 of the Draft RIA, the magnitude of the rebound effect 

is likely to be influenced by the extent of any market failures that affect the demand for more 

fuel efficient HDVs, as well as by HDV operators’ responses to their perception of the tradeoff 

between higher upfront HDV purchase costs versus lower but uncertain future expenditures on 

fuel. 

(2) Econometric and Other Evidence Related to HDV VMT Rebound

As discussed above, HDV VMT rebound is defined as the change in HDV VMT that 

occurs in response to an increase in HDV fuel efficiency. We are not aware of any studies that 

directly estimate this elasticity660 for the U.S. This section discusses econometric analyses of 

other related elasticities that could potentially be used as a proxy for measuring HDV VMT 

rebound, as well as other analyses that may provide insight into the magnitude of HDV VMT

rebound. We seek comment on the applicability of the findings from these analyses, as well as 

additional data and research on the topic of HDV VMT rebound. 

One of the challenges to developing robust econometric analyses of HDV VMT rebound

in the U.S. is data limitations. For example, the main source of time-series HDV fuel efficiency

data in the U.S. is derived from aggregate fuel consumption and HDV VMT data. This may

introduce interdependence or “simultaneity” between measures of HDV VMT and HDV fuel 

efficiency, because estimates of HDV fuel efficiency are derived partly from HDV VMT. This 

mutual interdependence makes it difficult to isolate the causal effect of HDV fuel efficiency on 

HDV VMT and to measure the response of HDV VMT to changes in HDV fuel efficiency. 

 

660 Elasticity is the measurement of how responsive an economic variable is to a change in another. For example:

price elasticity of demand is a measure used in economics to show the responsiveness, or elasticity, of the quantity 

demanded of a good or service to a change in its price. More precisely, it gives the percentage change in quantity 

demanded in response to a one percent change in price.
Page 633 of 850

Data on other important determinants of HDV VMT, such as freight shipping rates, 

shipment sizes, HDV payloads, and congestion levels on key HDV routes is also limited, of 

questionable reliability, or unavailable. Additionally, data on HDVs and their use is usually only 

available at an aggregate level, making it difficult to evaluate potential differences in 

determinants of VMT for different types of HDV operations (e.g., long-haul freight vs. regional 

delivery operations) or vehicle sub-classes (e.g., utility vehicles vs. school buses). 

Another challenge inherent in using econometric techniques to measure the response of 

HDV VMT to HDV fuel efficiency is developing model specifications that incorporate the 

mathematical form and range of explanatory variables necessary to produce reliable estimates of 

HDV VMT rebound. Many different factors can influence HDV VMT, and the complex 

relationships among those factors should be considered when measuring the rebound effect.661 

In practice, however, most studies have employed simplified models. Many use price 

variables (e.g., price per gallon of fuel, or fuel cost per mile driven) and some measure of 

aggregate economic activity, such as GDP. However, some of these studies exclude potentially

important variables such as the amount of road capacity (which affects travel speeds and may be 

related to other important characteristics of highway infrastructure), or the price or availability of 

competing forms of freight transport such as rail or barge (i.e., characteristics of the overall 

freight transport network). 

(a) Fuel Price and Fuel Cost Elasticities

This sub-section reviews econometric analyses of the change in HDV use (measured in 

VMT, ton-mile, or fuel consumption) in response to changes in fuel price ($/gallon) or fuel cost 

($/mile or $/ton-mile). The studies presented below attempt to estimate these elasticities in the 

HDV sector using varying approaches and data sources. 

Gately (1990) employed an econometric analysis of U.S. data for the years 1966 – 1988 

to examine the relationship between HDV VMT and average fuel cost per mile, real Gross 

National Product (GNP), and variables capturing the effects of fuel shortages in 1974 and 

1979.662 The study found no statistically significant relationship between HDV VMT and fuel 

cost per mile. Gately’s estimates of the elasticity of HDV VMT with respect to fuel cost per 

mile were -0.035 with and -0.029 without the fuel shortage variables, but both estimates had 

 

661 A useful framework for understanding how various responses interact to determine the rebound effect is 

presented in Section 2 and Appendix B of De Borger, B. and Mulalic, I. (2012), “The determinants of fuel use in the 

trucking industry – volume, fleet characteristics and the rebound effect”, Transportation Policy, Volume 24, pp. 

284–295. See also Section 3.4 of EERA (2014), “Research to Inform Analysis of the Heavy-Duty vehicle Rebound 

Effect”, Excerpts of Draft Final Report of Phase 1 under EPA contract EP-C-13-025. 

662 Gately, D., The U.S. Demand for Highway Travel and Motor Fuels, The Energy Journal, Volume 11, No. 3, July 

1990, pp.59-73.
Page 634 of 850

large standard errors. However, Gately’s study was beset by numerous statistical problems, 

which raise serious questions about the reliability of its results.663

More recently, Matos and Silva (2011) analyzed road freight transportation sector data 

for the years 1987 – 2006 in Portugal to identify the determinants of demand for HDV freight 

transportation.

664 Using a reduced-form equation relating HDV use (measured in ton-km) to 

economic activity (GDP) and the energy cost of HDV use (measured in fuel cost per ton-km 

carried), these authors estimated the elasticity of HDV ton-km with respect to energy costs to be 

-0.241. An important strength of Matos and Silva’s study is that it also estimated this same 

elasticity using a procedure that accounted for the effect of potential mutual causality between 

HDV ton-km and energy costs, and arrived at an identical value. 

Differences between HDV use and the level of highway service in Portugal and in the 

U.S. might limit the applicability of Matos and Silva’s result to the U.S. The volume and mix of 

commodities could differ between the two nations, as could the levels of congestion on their 

respective highway networks, transport distances, the extent of intermodal competition, and the 

characteristics of HDVs themselves. HDVs also operate over a more limited highway network 

in Portugal than in the United States. Unfortunately, it is difficult to anticipate how these 

differences might cause Matos and Silva’s elasticity estimates to differ from what we might find 

in the U.S. Finally, their analysis focused on HDV freight transport and did not consider nonfreight uses of HDVs, which somewhat limits its usefulness in the analysis of this proposed 

rulemaking. 

De Borger and Mulalic (2012) examined the determinants of fuel use in the Denmark 

HDV freight transport sector for the years 1980 – 2007. The authors developed a system of 

equations that capture linkages among the demand for HDV freight transport, HDV fleet 

characteristics, and HDV fuel consumption.665 As De Borger and Mulalic state, “we precisely

define and estimate a rebound effect of improvements in fuel efficiency in the trucking industry: 

behavioral adjustments in the industry imply that an exogenous improvement in fuel efficiency

reduces fuel use less than proportionately. Our best estimate of this effect is approximately 10 

percent in the short run and 17 percent in the long run, so that a 1 percent improvement in fuel 

efficiency reduces fuel use by 0.90 percent (short-run) to 0.83 percent (long-run).”

While De Borger and Mulalic capture a number of important responses that contribute to 

the rebound effect, some caution is appropriate when using their results to estimate the VMT

rebound effect for this proposal. Like the Matos and Silva study, this study examined HDV 

 

663 The most important of these problems – similar historical time trends in the model’s dependent variable and the 

measures used to explain its historical variation – can lead to “spurious regressions,” or the appearance of behavioral 

relationships that are simply artifacts of the similarity (or correlation) in historical trends among the model’s 

variables.

664 Matos, F. J. F., and Silva, F. J. F., “The Rebound Effect on Road Freight Transport: Empirical Evidence from 

Portugal,” Energy Policy, 39, 2011, pp. 2833–2841.

665 De Borger, B. and Mulalic, I., “The determinates of fuel use in the trucking industry – volume, fleet 

characteristics and the rebound effect”, Transportation Policy, Volume 24, November 2012, pp. 284–295.
Page 635 of 850

activity in another country, Denmark, which has a less-developed highway system, lower levels 

of freight railroad service than the U.S., and is also likely to have a different composition of 

freight shipping activity. Although the effect of some of these differences is unclear, greater 

competition from rail shipping in the U.S. and the resulting potential for lower trucking costs to 

divert some rail freight to truck could cause the VMT rebound effect to be larger in the U.S. than 

De Borger and Mulalic’s estimate for Denmark. 

On the other hand, if freight networks are denser and commodity types are more 

homogenous in Denmark than the U.S., then shippers may have wider freight trucking options.

If this is the case, shippers in Denmark might be more sensitive to changes in freight costs, 

which could cause the rebound effect in Denmark to be larger than the U.S. Like the Matos and 

Silva study, this analysis also focuses on freight trucking and does not consider non-freight 

HDVs (e.g. vocational vehicles). We have been unable to identify adequate data to employ De 

Borger and Mulalic’s model for the U.S. (mainly because time-series data on freight carriage by

trucks, driver wages, and vehicle prices in the U.S. are limited).

The Volpe National Transportation Systems Center previously has developed a series of 

travel forecasting models for the Federal Highway Administration (FHWA).666 Work conducted 

by the Volpe Center during 2009-2011 to develop the original version of FHWA’s forecasting 

model was presented in the Regulatory Impact Analysis for the HD GHG Phase 1 rule (see Table 

9-2 in that document, which is reproduced below as Table IX-11).668 In the analysis for the 

Phase 1 rule, Volpe estimated both state-level and national aggregate models to forecast HDV 

single unit and combination truck VMT that included fuel cost per mile as an explanatory

variable. This analysis used data from 1970 – 2008 for its national aggregate model, and data for 

the 50 individual states from 1994 – 2008 for its state-level model.669, 670

 

666 FHWA Travel Analysis Framework Development of VMT Forecasting Models for Use by the Federal Highway 

Administration May 12, 2014 http://www.fhwa.dot.gov/policyinformation/tables/vmt/vmt_model_dev.pdf. Volpe’s 

work was advised by a panel of approximately 20 experts in the measurement, analysis, and forecasting of travel, 

including academic researchers, transportation consultants, and members of local, state, and federal government 

transportation agencies. It was also summarized in the paper “Developing a Multi-Level Vehicle Miles of Travel 

Forecasting Model,” November, 2011, which was presented to the Transportation Research Board’s 91st Annual 

Meeting in January, 2012. 

668 EPA/NHTSA, August 2011. Chapter 9.3.3, Final Rulemaking to Establish Greenhouse gas Emission Standards & 

Fuel Efficiency Standards for Medium-and Heavy-Duty Engines and Vehicles, Regulatory Impact Analysis. EPA420-R-11-901. (http://www.epa.gov/otaq/climate/documents/420r11901.pdf)

669 Combination trucks are defined as “all [Class 7/8] trucks designed to be used in combination with one or more 

trailers with a gross vehicle weight rating over 26,000 lbs.” (AFDC, 2014; ORNL, 2013c). Single-unit trucks are 

defined as “single frame trucks that have 2–axles and at least 6 tires or a gross vehicle weight rating exceeding 

10,000 lbs.” (FHWA, 2013).

670 The national-level and functional class VMT forecasting models utilize aggregate time-series data for the nation 

as a whole, so that only a single measure of each variable is available during each time period (i.e., year). In 

contrast, the state-level VMT models have an additional data dimension, since both their dependent variable (VMT) 

and most explanatory variables have 51 separate observations available for each time period (one for each of the 50 

states as well as Washington, DC). In this context, the states represent a “cross-section,” and a continuous annual 

sequence of these cross-sections is available.
Page 636 of 850

Volpe analysts tested a large number of different specifications for its national and state 

level models that incorporated the effects of factors such as aggregate economic activity and its 

composition, the volume of U.S. exports and imports, and factors affecting the cost of producing 

trucking services (e.g., driver wage rates, truck purchase prices, and fuel costs), and the extent 

and capacity of the U.S. and states’ highway networks. 

Table IX-11 summarizes Volpe’s Phase 1 estimates of the elasticity of truck VMT with 

respect to fuel cost per mile.672 As it indicates, these estimates vary widely, and the estimates 

based on state-level and national data differ substantially. 

Table IX-11 Summary of Volpe Center Estimates of Elasticity of Truck VMT with Respect to Fuel Cost per 

Mile

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%

Volpe staff conducted additional analysis of the models that yielded the estimates of the 

elasticity of truck VMT with respect to fuel cost per mile reported in Table IX-11, using updated 

information on fuel costs and other variables appearing in these models, together with revised 

historical data on truck VMT provided by DOT’s Federal Highway Administration. The newlyavailable data, statistical procedures employed in conducting this additional analysis, and its 

results are summarized in materials that can be found in the docket for this rulemaking. This 

new Volpe analysis was not available at the time the agencies selected the values of the rebound 

effect for this proposal, but the agencies will consider this work and any other work in the 

analysis supporting the final rule.

Finally, EPA has contracted with Energy and Environmental Research Associates 

(EERA), LLC to analyze the HDV rebound effect for regulatory assessment purposes. Excerpts 

of EERA’s initial report to EPA are included in the docket and contain detailed qualitative 

discussions of the rebound effect as well as data sources that could be used in quantitative 

analysis.674 EERA also conducted follow-on quantitative analyses focused on estimating the 

impact of fuel prices on VMT and fuel consumption. We have included a working paper in the 

 

672 One drawback of the fuel cost measure employed in Volpe’s models is that it is based on estimates of fuel 

economy derived from truck VMT and fuel consumption, which introduces the potential for mutual causality (or 

“simultaneity”) between VMT and the fuel cost measure and makes the effect of the latter difficult to isolate. This 

may cause their estimates of the sensitivity of truck VMT to fuel costs to be inaccurate, although the direction of any 

resulting bias is difficult to anticipate.

674 EERA (2014), “Research to Inform Analysis of the Heavy-Duty vehicle Rebound Effect”, Excerpts of Draft Final 

Report of Phase 1 under EPA contract EP-C-13-025. 
Page 637 of 850

docket on this work, and we seek comment on this work.675 Note that EERA’s working paper 

was not available at the time the agencies conducted the analysis of the rebound effect for this 

proposal, but the agencies will consider this work and any other work in the analysis supporting 

the final rule.

There are reasons to be cautious about interpreting the elasticities from the studies

reviewed in this section as a measure of VMT rebound resulting from our proposed standards. 

For example, vehicle capacity and loaded weight can vary dynamically in the HDV sector –

possibly in response to changes in fuel price and fuel efficiency – and data on these measures are 

limited. This makes it difficult to confidently infer a direct relationship between trucking output 

(e.g., ton-miles carried) and VMT assuming a constant average payload. 

In addition, fuel cost per mile – calculated by multiplying fuel price per gallon by fuel 

efficiency in gallons per mile – and fuel price may be imprecise proxies for an improvement in 

fuel efficiency, because the response of VMT to these variables may differ. For example, if 

truck operators are more attentive to variation in fuel prices than to changes in fuel efficiency, 

then fuel price or fuel cost elasticities may overstate the true magnitude of the rebound effect. 

Similarly, there is some evidence in the literature that demand for fuel is more responsive 

to fuel price increases than to decreases.676 Since improved fuel efficiency typically causes fuel 

costs for HDVs to fall (and assuming fuel costs are not fully offset by increases in vehicle 

purchase prices), fuel price or cost elasticities derived from historical periods when fuel prices 

were increasing or fuel efficiency was declining may also overstate the magnitude of the rebound 

effect. An additional unknown is that HDV operators may factor fuel prices and fuel costs into 

their decision-making about rates to charge for their service differently from the way they 

incorporate initial vehicle purchase costs. 

Despite these limitations, elasticities with respect to fuel price and fuel cost can provide 

some insight into the magnitude of the HDV VMT rebound effect. The agencies request 

comment on all of the studies presented in this section. 

(b) Freight Price Elasticities

Freight price elasticities measure the percent change in demand for freight in response to 

a percent change in freight prices, controlling for other variables that may influence freight 

demand such as GDP, the extent that goods are traded internationally, and road supply and 

capacity. This type of elasticity is only applicable to the HDV subcategory of freight trucks (i.e., 

 

675 EERA (2015), “Working Paper on Fuel Price Elasticities for Heavy Duty Vehicles”, Draft Final Report of Phase 

2 under EPA contract EP-C-11-046. 

676 Gately, D. 1993. The Imperfect Price-Reversibility of World Oil Demand. The Energy Journal, International 

Association for Energy Economics, vol. 14 (4), pp. 163-182; Dargay, J.M., Gately, D. 1997. The demand for 

transportation fuels: imperfect price-reversibility? Transportation Research Part B 31(1); and Sentenac-Chemin, E., 

2012. Is the price effect on fuel consumption symmetric? Some evidence from an empirical study. Energy Policy, 

vol. 41, pp. 59-65.
Page 638 of 850

combination tractors and vocational vehicles that transport freight). One desirable attribute of 

such measures for purposes of this analysis is that they show the response of freight trucking 

activity to changes to trucking rates, including changes that result from fuel cost savings as well 

as increases in HDV technology costs.677 

Freight price elasticities, however, are imperfect proxies for the rebound effect in freight 

trucks for a number of reasons.678 For example, in order to apply these elasticities we must 

assume that our proposed rule’s impact on fuel and vehicle costs is fully reflected in freight rates. 

This may not be the case if truck operators adjust their profit margins or other operational 

practices (e.g., loading practices, truck driver’s wages) instead of freight rates. It is not well 

understood how trucking firms respond to different types of cost changes (e.g., changes to fuel 

costs versus labor costs).

Freight price elasticity estimates in the literature typically measure freight activity in tons 

or ton-miles, rather than VMT. As discussed in the previous section, average truck capacity and 

payload in the HDV sector varies dynamically – possibly in response to changes in fuel price and 

fuel efficiency – and data on these measures are limited. This makes it difficult to confidently

infer a direct relationship between ton-miles and VMT by assuming a constant average payload. 

Inferring a direct relationship between tons and VMT is even less straightforward. Additionally, 

there are significant limitations on national freight rate and freight truck ton-mile data in the 

U.S., making it difficult to confidently measure the impact of a change in freight rates on tonmiles.679

 

Finally, freight price elasticity estimates in the literature vary significantly based on 

commodity type, length of haul, region, availability of alternative modes (discussed further in 

Section IX.E.b.iii below), and functional form of the model (i.e., log-linear, linear, translog) 

making it difficult to confidently apply any single estimate reported in the literature to 

nationwide freight activity. For example, elasticity estimates for longer trips tend to be larger in 

magnitude than those for shorter trips, while demand to ship bulk commodities tends to be less 

elastic than for non-bulk commodities. 

Although these factors explain some of the differences among reported estimates, much 

of the observed variation cannot be explained quantitatively. For example, one study that 

controlled for mode, commodity class, demand elasticity measure (i.e., tons or ton-miles), model 

 

677 Note however that a percent change in freight activity in response to a percent change in freight rates should 

theoretically be larger than a percent change in freight activity in response to a percent change in fuel efficiency 

because fuel efficiency only impacts a portion of freight operating costs (e.g., fuel and vehicle costs, but not likely 

driver wages or highway tolls).

678 Winebrake, J.J., Green, E.H., Comer, B., Corbett, J.J., Froman, S., 2012. Estimating the direct rebound effect for 

on-road freight transportation. Energy Policy 48, 252-259.

679 See, for example, Appendix E in EERA (2014), “Research to Inform Analysis of the Heavy-Duty Vehicle 

Rebound Effect”, Draft Final Report of Phase 1 under EPA contract EP-C-13-025. 
Page 639 of 850

estimation form, country, and temporal nature of data only accounted for about half of the 

observed variation.680 

(c) Mode Shift Case Study

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 HDVs. This is because 

the United States has extensive rail, waterway and air transport networks in addition to an 

extensive highway network; these networks often closely parallel each other and are often viable 

choices for freight transport for many long-distance shipping routes within the continental U.S. 

If rates for one mode decline, demand for that mode is likely to increase, and some of this new 

demand could represent shifts from other modes.681 The “cross-price elasticity of demand,” 

which measures the percentage change in demand for shipping by another mode (e.g., rail) given 

a percentage change in the price of HDV freight transport services, provides a measure of the 

importance of such mode shifting. Aggregate estimates of cross-price elasticities vary widely

682

, 

and there is no general consensus on the most appropriate value to use for analytical purposes. 

When considering intermodal shift, one of the most relevant kinds of shipments are those 

that are competitive between rail and HDV modes. These trips generally include long-haul 

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 HDV and rail modes, 

so they would not be expected to shift modes except under an extreme price change. However, 

to the best of our knowledge, the total amount of freight that could potentially be subject to mode 

shifting has not been studied extensively. 

In order to explore the potential for HDV fuel efficiency standards to produce economic 

conditions that favor a mode shift from rail to HDVs, EPA commissioned GIFT Solutions, LLC 

to perform case studies on the HD GHG Phase 1 rule using a number of data sources, including 

the Commodity Flow Survey, interviews with trucking firms, and the Geospatial Intermodal 

Freight Transportation (GIFT) model developed by Winebrake and Corbett, which includes 

information on infrastructure and other route characteristics in the U.S.683,684 

 

680 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.

681 Rail lines in parts of the U.S. are thought to be currently oversubscribed. If that is the case, and new freight 

demand is already being satisfied by trucks, then this would limit the potential for intermodal freight shifts between 

trucks and rail as the result of this proposed rule. 

682 Winebrake, J.J., Green, E.H., Comer, B., Corbett, J.J., Froman, S., 2012. Estimating the direct rebound effect for 

on-road freight transportation. Energy Policy 48, 252-259.

683 Winebrake, James and James J. Corbett (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
Page 640 of 850

A central assumption in the case studies was that economic conditions would favor a shift 

from rail to HDVs if either the price per ton-mile to ship a commodity by HDV, or the price to 

ship a given quantity of a commodity by HDV, became lower relative to rail transport options 

post-regulation. The results of the case studies indicate that the HD Phase 1 rule would not seem 

to create obvious economic conditions that lead to a mode shift from rail to truck, but there are a 

number of limitations and caveats to this analysis, which are discussed in the final report to EPA 

by GIFT.685,686 For example, even if trucking did not become less expensive than rail postregulation, a relative decrease in the truck versus rail rates might be enough to produce a shift,

given that other factors could influence shippers’ decisions on modal choice. The study did not, 

however, consider these other factors such as time-of-delivery and modal capacity. As another 

example, the analysis assumes all fuel cost savings and incremental vehicle costs from the HD 

Phase 1 rule would be passed on to shippers via changes in freight rates, even though the analysis 

found some evidence that this might not occur (in two cases, the charges for shipping a truckload 

over a given route and distance were the same despite differences in payloads that should have 

been reflected in their fuel costs). Given these limitations, more work is needed in this area to 

explore the potential for mode shift in response to HD fuel efficiency standards.

(d) Case Study Using Freight Price Elasticities

Cambridge Systematics, Inc. (CSI) employed a case study approach using freight price 

elasticity estimates in the literature to show several examples of the magnitude of the HDV 

rebound effect.687 In their unpublished paper commissioned by the National Research Council of 

the National Academies in support of its 2010 HDV report, CSI estimated the effect on HDV 

VMT from a net decrease in operating costs associated with fuel efficiency improvements, using 

two different technology cost and fuel savings scenarios for Class 8 combination tractors. 

Scenario 1 increased average fuel efficiency of the tractor from 5.59 miles per gallon to 6.8 miles 

per gallon, with an additional cost of $22,930 for purchasing the improved tractor. Scenario 2 

increased the average fuel efficiency to 9.1 miles per gallon, at an incremental cost of $71,630 

per tractor. Both of these scenarios were based on the technologies and targets from a report 

authored by the Northeast States Center for a Clean Air Future (NESCCAF) and International 

Council on Clean Transportation (ICCT).688

 

684 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).

685 See GIFT Solutions, LLC, “Potential for Mode Shift due to Heavy Duty Vehicle Fuel Efficiency Improvements”. 

February, 2012.

686 Winebrake, James, J. Corbett, J. Silberman, E. Erin, & B. Comer, 2012. Potential for Mode Shift due to Heavy 

Duty Vehicle Fuel Efficiency Improvements: A Case Study Approach. GIFT Solutions, LLC. 

687 Cambridge Systematics, Inc., Assessment of Fuel Economy Technologies for Medium and Heavy Duty Vehicles: 

Commissioned Paper on Indirect Costs and Alternative Approaches, 2009. 

688 Northeast States Center for a Clean Air Future, Southeast Research Institute, TIAX, LLC., and International 

Council on Clean Transportation, Reducing Heavy-Duty Long Haul Truck Fuel Consumption and CO2 Emissions, 

September 2009. See http://www.nescaum.org/documents/heavy-duty-truck-ghg_report_final-200910.pdf
Page 641 of 850

The CSI estimates were based on a range of direct (or “own-price”) freight elasticities (-

0.5 to -1.5)689 and cross-price freight elasticities (0.35 to 0.59) 690 obtained from the literature.691 

In their calculations, CSI assumed 142,706 million miles of tractor VMT and 1,852 billion tonmiles were affected. The tractor VMT was based on the Bureau of Transportation Statistics’ 

(BTS) estimate of highway miles for combination tractors in 2006, and the rail ton-miles were 

based on the BTS estimate of total railroad miles during 2006. This assumption is likely to 

overstate the rebound effect, since not all freight shipments occur on routes where tractors and 

rail service shipments compete directly. Nevertheless, this assumption appears to be reasonable 

in the absence of more detailed information on the percentage of total miles and ton-miles that 

are subject to potential mode shifting. 

For CSI’s calculations, all costs except fuel costs and vehicle costs were taken from a 

2008 ATRI study.

692

 It is not clear from the report how the new vehicle costs were incorporated 

into CSI’s calculations of per-mile tractor operating costs. For example, neither the ATRI report 

nor the CSI report discusses assumptions about depreciation, useful lifetimes of tractors, and the 

opportunity cost of capital. 

Based on these two scenarios, CSI estimated the change in tractor VMT in response to a 

net decrease in operating costs (i.e., accounting for fuel cost and changes in tractor purchase 

costs) associated with fuel efficiency improvement of 11-31 percent for Scenario 1 and 5-16 

percent for Scenario 2, without accounting for any fuel savings from reduced rail service. When 

the fuel savings from reduced rail usage were included in the calculations, they estimated the 

change in tractor VMT in response to a net decrease in operating costs associated with fuel 

efficiency improvement would be 9-30 percent for Scenario 1, and 3-15 percent for Scenario 2. 

Note that these estimates reflect changes to tractor VMT with respect to total operating 

costs, so they should theoretically be larger than a percent change in tractor VMT with respect to 

a percent change in fuel efficiency because fuel efficiency only impacts a portion of truck 

operating costs (e.g., fuel and vehicle costs, but not likely driver wages or highway tolls).

CSI included caveats associated with these calculations. For example, their report states 

that freight price 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), 

geography, trip lengths, markets served, and commodities transported.” These factors can 

increase variability in the results. Also, estimates in CSI’s study have the limitation of using 

 

689 Graham and Glaister, “Road Traffic Demand Elasticity Estimates: A Review,” Transport Reviews Volume 24, 3, 

pp. 261-274, 2004.

690 Based upon a study for the National Cooperative Highway Research Program by Cambridge Systematics, Inc., 

Characteristics and Changes in Freight Transportation Demand: A Guidebook for Planners and Policy Analysts 

Phase II Report, National Cooperative Highway Research Program Project 8-30, June 1995. 

691 The own (i.e., self) price elasticity provides a measure for describing how the volume of truck shipping (demand) 

changes with its price while the cross-price elasticity provides a measure for describing how the volume of rail 

shipping changes with truck price. In general, an elasticity describes the percent change in one variable (e.g. demand 

for trucking) in response to a percent-change in another (e.g. price of truck operations).

692 American Transportation Research Institute, “An Analysis of the Operational Costs of Trucking”, October 2008.
Page 642 of 850

freight price elasticities to estimate the HDV rebound effect discussed previously in Section 

IV.D.2.b. 

(e) Simulation Model Study Using Freight Price Elasticities

Guerrero (2014) constructs a freight simulation model of the California trucking sector to 

measure the impact of fuel saving investments and fleet management on GHG emissions.693

Rather than estimating these impacts using econometric analysis of raw data, the study uses 

values from the existing literature. Guerrero determines that “...improving the performance of 

trucking also increases the number of trips demanded because the market price also decreases. 

This ‘rebound’ effect offsets around 40-50 percent of these vehicle efficiency emission 

reductions, with 9-14 percent of the effect coming from increased pavement deterioration and 

31-36 percent coming from increased fuel combustion.” Note that to the extent that trip lengths 

also vary in response to improvements in HDV fuel efficiency, changes in the number of HDV 

trips may not exactly reflect changes in the total number of miles the vehicles are operated. 

However, these findings are based on freight price elasticities, which – as we discuss in 

Section IV.D.2.b and in the context of the CSI study above – have significant limitations. The 

study also simulates only one state’s freight network (California), which may not be a good 

representation of national activity.

(3) How the Agencies Estimated the HDV Rebound Effect for this Proposal

(a) Values Used in the Phase 1 Analysis

At the time the agencies conducted their analysis of the Phase 1 fuel efficiency and GHG 

emissions standards, the only evidence on the HDV rebound effect were the previously described 

studies from CSI and the Volpe Center.694 On the basis of this evidence, the agencies chose 

rebound effects of 15 percent for vocational vehicles and 5 percent for combination tractors, both 

of which were toward the lower end of the range of values from these studies. The agencies 

found no evidence on the rebound effect for HD pickup trucks and vans, but concluded it would 

be inappropriate to use the values selected for vocational vehicles or combination tractors for 

those vehicles. Because the usage patterns of HD pickup trucks and vans can more closely 

resemble those of large light-duty vehicles, the agencies used the 10 percent rebound effect we

had employed in our most recent light-duty rulemaking to analyze the Phase 1 standards for 2b/3 

vehicles.

(b) How the Agencies Analyzed VMT Rebound in this Proposal

After considering the new evidence that has become available since the HD Phase 1 final 

rule, the agencies elected to continue using the rebound effect estimates we used previously in 

 

693 Guerrero, Sebastian. Modeling fuel saving investments and fleet management in the trucking industry: The 

impact of shipment performance on GHG emissions. Transportation Research Part E, May 2014.

694 The Gately study was also available, however, the agencies were not aware of the work at the time.
Page 643 of 850

the HD Phase 1 rule in our analysis of Phase 2 proposed standards. In arriving at this decision, 

the agencies considered the shortcomings and limitations of the newly-available studies 

described previously, particularly the limited applicability of the two published studies using 

data from European nations to the U.S. context. After weighing these attributes of the more 

recent studies, the agencies concluded that we had insufficient evidence to justify revising the 

rebound effect values that were used in the Phase 1 analysis.

In our assessment, we do not discern between short-run and long-run rebound effects, 

although these effects may differ. The vocational and combination truck estimates are based on 

the Volpe Center analysis presented in the HD Phase 1 rule and the case study from CSI. As

with the HD Phase 1 rule, we did not find any literature specifically examining the HD pickup 

and truck sector. Since these vehicles are used for very different purposes than combination 

tractors and vocational vehicles, and they are more similar in use to large light-duty vehicles, we 

have chosen the light-duty rebound effect of 10 percent used in the final rule establishing fuel 

economy and GHG standards for MYs 2017-2025 light-duty vehicles in our analysis of HD 

pickup trucks and vans. 

While for this proposal, the agencies have selected to use these rebound effect values, we 

acknowledge the literature shows a wide range of rebound effect estimates. Therefore, we will 

review and consider revising these estimates in the final rule, taking into consideration all 

available data and analysis, including submissions from public commenters and new research on 

the rebound effect. 

It should be noted that the rebound estimates we have selected for our analysis represent 

the VMT impact from our proposed standards with respect to changes in the fuel cost per mile 

driven. As described previously, the HDV rebound effect should ideally be a measure of the 

change in fuel consumed with respect to the change in overall operating costs due to a change in 

HDV fuel efficiency. Such a measure would incorporate all impacts from our proposal, 

including those from incremental increases in vehicle prices that reflect costs for improving their 

fuel efficiency. Therefore, VMT rebound estimates with respect to fuel costs per mile must be 

“scaled” to apply to total operating costs, by dividing them by the fraction of total operating 

costs accounted for by fuel. 

The agencies made simplifying assumptions in the VMT rebound analysis for this 

proposal, similar to the approach taken during the development of the HD GHG Phase 1 final 

rule. However, for the HD Phase 2 final rulemaking, we plan to use a more comprehensive 

approach. Due to timing constraints during the development of this proposal, the agencies did 

not have the technology package costs for each of the alternatives prior to the need to conduct 

the inventory analysis, except for the pickup truck and van category in analysis Method A. 

Therefore, the same "overall" VMT rebound values were used for Alternatives 2 through 5 (as 

discussed in Chapter 8.3.3 of the Draft RIA and analyzed in Chapter 6 of the Draft RIA), despite 

the fact that each alternative results in a different change in incremental technology and fuel 

costs. For the final rulemaking, we plan to determine VMT rebound separately for each HDV 

category and for each alternative. Tables 64 through 66 in Chapter 7 of the Draft RIA present 

VMT rebound for each HDV sector that we estimated for the preferred alternative. These VMT 

impacts are reflected in the estimates of total fuel savings and reductions in emissions of GHG 

and other air pollutants presented in Section VI and VII of this preamble for all categories.
Page 644 of 850

Section 9.3.3 in the draft RIA provides more details on our assessment of HDV VMT 

rebound. We invite comment on our approach, the rebound estimates, and the related 

assumptions we made. In particular, we invite comment on the most appropriate methodology

for factoring new vehicle purchase or leasing costs into the per-mile operating costs. For the 

purposes of this proposal, we have not taken into account any potential fuel savings or GHG 

emission reductions from the rail sector due to mode shift because estimates of this effect seem

too speculative at this time. We invite comment on this assumption, as well as suggestions on 

alternative modeling frameworks that could be used to assess mode shifting implications of our

proposed regulations. Similarly, we have not taken into account any fuel savings or GHG 

emissions reductions from the potential shift in VMT from older HDVs to newer, more efficient 

HDVs because we have found no evidence of this potential effect from fuel efficiency standards. 

We invite comment on suggested modeling frameworks or data that could be used to assess the 

potential for activity to shift from older to newer, more efficient HDVs in response to our 

proposed standards.

Note that while we focus on the VMT rebound effect in our analysis of this proposed 

rule, there are at least two other types of rebound effects discussed in the economics literature. 

In addition to VMT rebound effects, there are “indirect” rebound effects, which refers to the 

purchase of other goods or services (that consume energy) with the costs savings from energy

efficiency improvements; and “economy-wide” rebound effects, which refers to the increased 

demand for energy throughout the economy in response to the reduced market price of energy 

that happens as a result of energy efficiency improvements.

Research on indirect and economy-wide rebound effects is nascent, and we have not 

identified any that attempts to quantify indirect or economy-wide rebound effects for HDVs. In 

particular, the agencies are not aware of any data to indicate that the magnitude of indirect or 

economy-wide rebound effects, if any, would be significant for this proposed rule.696 Therefore, 

we rely the same analysis of vehicle miles traveled to estimate the rebound effect in this proposal 

that we did for the HD Phase 1 rule, where we attempted to quantify only rebound effects from 

our rule that impact HDV VMT. We welcome comments and any new work in this area that 

helps to assess and quantify different rebound effects that could result from improvements in 

HDV efficiency, including different types of more intensive truck usage that affect fuel 

consumption but not VMT such as loaded weight, truck routing, and scheduling.

In order to test the effect of alternative assumptions about the rebound effect, NHTSA 

examined the sensitivity of its estimates of benefits and costs of the Phase 2 Preferred 

Alternative for HD pickups and vans to alternative assumptions about the rebound effect. While 

 

696 One entity sought reconsideration of the Phase 1 rule on the grounds that indirect rebound effects had not been 

considered by the agencies and could negate all of the benefits of the standards. This assertion rested on an 

unsupported affidavit lacking any peer review or other indicia of objectivity. This affidavit cited only one published 

study. The study cited did not deal with vehicle efficiency, has methodological limitations (many of them 

acknowledged), and otherwise was not pertinent. EPA and NHTSA thus declined to reconsider the Phase 1 rule 

based on these speculative assertions. See generally 77 FR 51703-04 (Aug. 27, 2012) and 77 FR 51502-03 (Aug. 

24, 2012).
Page 645 of 850

the main analysis for pickups and vans assumes a 10 percent rebound effect, the sensitivity

analysis estimates the benefits and costs of the proposed standards under the assumptions of 5, 

15, and 20 percent rebound effects. 

Alternative values of the rebound effect change the estimates of benefits and costs from 

the proposed standards in three ways. First, higher values of the rebound effect increase the 

amount of additional VMT that results from improved fuel efficiency; this increases costs 

associated with additional congestion, accidents, and noise, thus increasing total costs associated 

with the proposed standards. Conversely, smaller values of the rebound effect reduce costs from 

additional congestion, accidents, and noise, so they reduce total costs of the proposed standards. 

Larger increases in VMT associated with higher values of the rebound effect reduce the value of 

fuel savings and related benefits (such as reductions in GHG emissions) by progressively larger 

amounts, while smaller values of the rebound effect cause smaller reductions in these benefits. 

At the same time, however, a higher rebound effect generates larger benefits from increased 

vehicle use, while a smaller rebound effect reduces these benefits. Thus the impact of alternative 

values of the rebound effect on total benefits from the proposed standards depends on the exact 

magnitudes of these latter two effects. On balance, these three effects can cause net benefits to 

increase or decrease for alternative values of the rebound effect. 

Table IX-12 Sensitivity of Preferred Alternative Impacts under Different Assumptions about Rebound Effect 

for Pickups and Vans, using 3% Discount Rate

HD Pickups and Vans Rebound Effect

Main 

Analysis

Sensitivity Cases Using 

Alternative Rebound 

Assumptions

10 % 5 % 15 % 20 %

Fuel Reductions (Billion Gallons) 7.8 8.2 7.5 7.1

GHG Reductions (MMT CO2 eq) 94.1 95.7 87.2 83.0

Total Costs ($ billion) 5.5 5.0 6.5 7.2

Total Benefits ($ billion) 23.5 23.0 22.9 22.8

Net Benefits ($ billion) 18.0 18.0 16.4 15.5

Table IX-12 summarizes the impact of these alternative assumptions on fuel and GHG 

emissions savings, total costs, total benefits, and net benefits. As it indicates, using a 5% value 

for the rebound effect reduces benefits and costs of the proposed standards by identical amounts, 

leaving net benefits unaffected. As the table also shows, rebound effects of 15 percent and 20 

percent increase costs and reduce benefits compared to their values in the main analysis, thus 

reducing net benefits of the proposed standards. Nevertheless, the preferred alternative has 

significant net benefits under each alternative assumption about the magnitude of the rebound 

effect for HD pickups and vans. Thus, these alternative values of the rebound effect would not 

have affected the agencies’ selection of the preferred alternative, as that selection is based on 

NHTSA’s assessment of the maximum feasible fuel efficiency standards and EPA’s selection of 

appropriate GHG standards to address energy security and the environment. 
Page 646 of 850

F. Impact on Class Shifting, Fleet Turnover, and Sales

The agencies considered two additional potential indirect effects which may lead to 

unintended consequences of the program to improve the fuel efficiency and reduce GHG 

emissions from HD trucks. The next sections cover the agencies’ qualitative discussions on 

potential class shifting and fleet turnover effects.

(1) Class Shifting

Heavy-duty vehicles are typically configured and purchased to perform a function. For 

example, a concrete mixer truck is purchased to transport concrete, a combination tractor is 

purchased to move freight with the use of a trailer, and a Class 3 pickup truck could be 

purchased by a landscape company to pull a trailer carrying lawnmowers. The purchaser makes 

decisions based on many attributes of the vehicle, including the gross vehicle weight rating of the 

vehicle, which in part determines the amount of freight or equipment that can be carried. If the 

proposed Phase 2 standards impact 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.697 NHTSA and EPA qualitatively evaluated the 

proposed 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 GHG/CAFE Phase 1 program and will meet GHG/CAFE Phase 2 

emission standards beginning in 2017. The increased stringency of the light-duty 2017-2025 

MY vehicle rule has led some to speculate that vehicle consumers may choose to purchase 

heavy-duty pickup trucks that are currently regulated under the HD Phase 1 program 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. These proposed rules would 

continue to diminish any incentive for such a class shift because they would narrow the GHG 

and fuel efficiency performance gap between light-duty and heavy-duty pickup trucks. The 

proposed 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 lightduty 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 proposed regulation of heavy-

 

697 See 2010 NAS Report, page 152.
Page 647 of 850

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 have significantly better fuel economy ratings than 

heavy-duty pickup trucks.

The projected cost increases for this proposed action differ between Class 8 day cabs and 

Class 8 sleeper cabs, reflecting our expectation that compliance with the proposed standards 

would lead truck consumers to specify sleeper cabs equipped with APUs while day cab 

consumers would 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 would occur for the following reasons. The addition of a 

sleeper berth to a tractor cab is not a consumer-selectable attribute in quite the same way as other 

vehicle features. The sleeper cab provides a utility that long-distance trucking fleets need to 

conduct their operations -- an on-board sleeping berth that lets a driver comply with federallymandated 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.698 A day cab simply 

cannot provide this utility with a single driver. The need for this utility would not be changed 

even if the additional costs to reduce greenhouse gas emissions from sleeper cabs exceed those 

for reducing greenhouse gas emissions from day cabs.699

A trucking fleet could instead 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 proposed 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 proposed 

regulations is small. We are proposing 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 would automatically eliminate any additional idling through the 

shutdown software. If trucking businesses choose this option, then costs based on purchase of 

APUs may overestimate the costs of this program to this sector.

 

698 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 EPA-HQ-OAR-2014--0827.

699 The average marginal cost difference between sleeper cabs and day cabs in the proposal is roughly $2,500.
Page 648 of 850

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 proposing to continue 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 proposed regulatory program would cause class 

shifting within the vocational vehicle class. The marginal cost difference due to the regulation of 

vocational vehicles is minimal. The cost of LRR tires on a per tire basis is the same for all 

vocational vehicles so the only difference in marginal cost of the vehicles is due to the number of 

axles. The agencies believe that the utility gained from the additional load carrying capability of 

the additional axle would outweigh the additional cost for heavier vehicles.700

In conclusion, NHTSA and EPA believe that the proposed regulatory structure for HD 

trucks would not significantly change the current competitive and market factors that determine 

purchaser preferences among truck types. Furthermore, even if a small amount of shifting would 

occur, any resulting GHG impacts would 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 

proposed program. 

(2) Fleet Turnover and Sales Effects

A regulation that affects the cost to purchase and/or operate trucks could affect 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 lowbuys, 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 2010 NAS HD Report discussed 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 

 

700 The proposed rule projects the difference in costs between the HHD and MHD vocational vehicle technologies is 

approximately $30.
Page 649 of 850

costs.701 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, pre-buy 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.702 

The proposed regulations are projected to return fuel savings to the truck owners that 

offset the cost of the regulation within a few years. The effects of the regulation on purchasing 

behavior and sales 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 IX. A. this scenario may occur if this 

proposed 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. In addition, the proposed standards are expected to lead 

manufacturers to install more fuel-saving technologies and promote their purchase; the increased 

availability and promotion may encourage sales. 

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 IX. A. ) 

between truck purchasers (who may 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 

 

701 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., pp. 150-151

702 See NAS Report, Note 701, page 151.
Page 650 of 850

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. 

Whether vehicle sales appear to be affected by the HD Phase 1 standards could provide 

some insight into the impacts of the proposed standards. At the time of this NPRM, sales data 

are not yet available for 2014 model year, the first year of the Phase 1 standards. In addition, any

trends in sales are likely to be affected by macroeconomic conditions, which have been 

recovering since 2009-2010. As a result, it is unlikely to be possible, even when vehicle sales 

data are available, to separate the effects of the existing standards from other confounding 

factors. 

G. Monetized GHG Impacts

(1) Monetized CO2 Impacts – The Social Cost of Carbon (SC-CO2)

We estimate the global social benefits of CO2 emission reductions expected from the 

proposed heavy-duty GHG and fuel efficiency standards using the social cost of carbon (SCCO2) estimates presented in the 2013 Technical Support Document: Technical Update of the 

Social Cost of Carbon for Regulatory Impact Analysis Under Executive Order 12866 (2013 SCC 

TSD).703 (The SC-CO2 estimates are presented in Table IX-11). We refer to these estimates, 

which were developed by the U.S. government, as “SC-CO2 estimates.” The SC-CO2 is a metric 

that estimates the monetary value of impacts associated with marginal changes in CO2 emissions 

in a given year. It includes a wide range of anticipated climate impacts, such as net changes in 

agricultural productivity and human health, property damage from increased flood risk, and 

changes in energy system costs, such as reduced costs for heating and increased costs for air 

conditioning. It is used in regulatory impact analyses to quantify the benefits of reducing CO2

emissions, or the disbenefit from increasing emissions. 

The SC-CO2 estimates used in this analysis were developed over many years, using the 

best science available, and with input from the public. Specifically, an interagency working 

 

703 Docket ID EPA–HQ–OAR–2014-0827, Technical Support Document: Technical Update of the 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 (May 2013, Revised November 

2013). Available at: http://www.whitehouse.gov/sites/default/files/omb/assets/inforeg/technical-update-social-costof-carbon-for-regulator-impact-analysis.pdf.
Page 651 of 850

group (IWG) that included EPA, DOT, and other executive branch agencies and offices used 

three integrated assessment models (IAMs) to develop the SC-CO2 estimates and recommended

four global values for use in regulatory analyses. The SC-CO2 estimates were first released in 

February 2010705 and updated in 2013 using new versions of each IAM. These estimates were 

published in the 2013 SCC TSD. The 2013 update did not revisit the 2010 modeling decisions 

(e.g., with regard to the discount rate, reference case socioeconomic and emission scenarios or 

equilibrium climate sensitivity). Rather, improvements in the way damages are modeled are 

confined to those that have been incorporated into the latest versions of the models by the 

developers themselves and used for analyses in peer-reviewed publications. The 2010 SCC 

Technical Support Document (2010 SCC TSD) provides a complete discussion of the methods 

used to develop these estimates and the 2013 SCC TSD presents and discusses the updated 

estimates.

 

The 2010 SCC TSD noted a number of limitations to the SC-CO2 analysis, including the 

incomplete way in which the IAMs 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. Current IAMs do not 

assign value to all of the important physical, ecological, and economic impacts of climate change 

recognized in the climate change literature due to a lack of precise information on the nature of 

damages and because the science incorporated into these models understandably lags behind the 

most recent research. Nonetheless, these estimates and the discussion of their limitations 

represent the best available information about the social benefits of CO2 reductions to inform 

benefit-cost analysis; see RIA of this rule and the SCC TSDs for additional details. The new 

versions of the models used to estimate the values presented below offer some improvements in 

these areas, although further work is warranted. 

Accordingly, EPA and other agencies continue to engage in research on modeling and 

valuation of climate impacts with the goal to improve these estimates. The EPA and other 

federal agencies have considered the extensive public comments on ways to improve SC-CO2

estimation received via the notice and comment periods that were part of numerous rulemakings.

In addition, OMB’s Office of Information and Regulatory Affairs sought public comment on the 

approach used to develop the SC-CO2 estimates (78 FR 70586; November 26, 2013). The 

comment period ended on February 26, 2014, and OMB is reviewing the comments received. 

 

705 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 the 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://www.whitehouse.gov/sites/default/files/omb/inforeg/for-agencies/Social-Cost-of-Carbon-for-RIA.pdf.
Page 652 of 850

OMB also responded in January 2014 to concerns submitted in a Request for Correction on the 

SCC TSDs.706

The four global SC-CO2 estimates, updated in 2013, are as follows: $13, $46, $68, and 

$140 per metric ton of CO2 emissions in the year 2020 (2012$).707 The first three values are 

based on the average SC-CO2 from the three IAMs, at discount rates of 5, 3, and 2.5 percent, 

respectively. SC-CO2 estimates for several discount rates are included because the literature 

shows that the SC-CO2 is quite sensitive to assumptions about the discount rate, and because no 

consensus exists on the appropriate rate to use in an intergenerational context (where costs and 

benefits are incurred by different generations). The fourth value is the 95th percentile of the SCCO2 from all three models at a 3 percent discount rate. It is included to represent higher-thanexpected impacts from temperature change further out in the tails of the SC-CO2 distribution

(representing less likely, but potentially catastrophic, outcomes). The SC-CO2 increases over 

time because future emissions are expected to produce larger incremental damages as economies 

grow and physical and economic systems become more stressed in response to greater climate 

change. The SC-CO2 values are presented in Table IX-11.

Applying the global SC-CO2 estimates, shown in Table IX-13, to the estimated 

reductions in domestic CO2 emissions for the proposed program, yields estimates of the dollar 

value of the climate related benefits for each analysis year. These estimates are then discounted 

back to the analysis year using the same discount rate used to estimate the SC-CO2. For internal 

consistency, the annual benefits are discounted back to net present value terms using the same 

discount rate as each SC-CO2 estimate (i.e. 5 percent, 3 percent, and 2.5 percent) rather than the 

discount rates of 3 percent and 7 percent used to derive the net present value of other streams of 

costs and benefits of the proposed rule.708 The SC-CO2 benefit estimates for each calendar year 

are shown in Table IX-14. The SC-CO2 benefit estimates for each model year are shown in 

Table IX-15.

 

706 OMB’s 1/24/14 response to the petition is available at 

https://www.whitehouse.gov/sites/default/files/omb/inforeg/ssc-rfc-under-iqa-response.pdf

707 The 2013 SCC TSD presents the SC-CO2 estimates in $2007. These estimates were adjusted to 2012$ using the 

GDP Implicit Price Deflator. Bureau of Economic Analysis, Table 1.1.9 Implicit Price Deflators for Gross Domestic 

Product; last revised on March 27, 2014. 

708 See more discussion on the appropriate discounting of climate benefits using SC-CO2 in the 2010 SCC TSD. 

Other benefits and costs of proposed regulations unrelated to CO2 emissions are discounted at the 3% and 7% rates 

specified in OMB guidance for regulatory analysis.
Page 653 of 850

Table IX-13 Social Cost of CO2, 2012 – 2050a(in 2012$ per Metric Ton)

Calendar

Year

5%

Average

3%

Average

2.5%

Average

3%,

95th Percentile

2012 $12 $37 $58 $100

2015 $12 $40 $61 $120

2020 $13 $46 $69 $140

2025 $15 $51 $74 $150

2030 $17 $56 $81 $170

2035 $20 $60 $86 $190

2040 $23 $66 $93 $210

2045 $26 $71 $99 $220

2050 $28 $77 $100 $240

Note:

a The SC-CO2values are dollar-year and emissions-year 

specific and have been rounded to two significant digits. 

Unrounded numbers from the 2013 SCC TSD were used to 

calculate the CO2 benefits.

Table IX-14 Upstream and Downstream Annual CO2 Benefits for the Given SC-CO2 Valueausing Method B 

and Relative to the Less Dynamic Baseline (Millions of 2012$) b

Calendar

Year

5%

Average

3%

Average

2.5%

Average

3%,

95th Percentile

2018 $13 $43 $65 $130

2019 $26 $91 $130 $270

2020 $40 $140 $210 $420

2021 $92 $330 $500 $1,000

2022 $170 $590 $880 $1,800

2023 $250 $860 $1,300 $2,600

2024 $400 $1,300 $1,900 $4,000

2025 $540 $1,800 $2,600 $5,500

2026 $720 $2,300 $3,400 $7,000

2027 $890 $2,900 $4,200 $8,900

2028 $1,100 $3,500 $5,100 $11,000

2029 $1,300 $4,200 $5,900 $13,000

2030 $1,500 $4,800 $6,900 $15,000

2035 $2,500 $7,400 $11,000 $23,000

2040 $3,300 $9,700 $14,000 $30,000

2050 $5,000 $14,000 $19,000 $42,000

NPV $22,000 $100,000 $160,000 $320,000

Notes:

a The SC-CO2 values are dollar-year and emissions-year specific. 

b For an explanation of analytical Methods A and B, please see Section I.D; for an 

explanation of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see 

Section X.A.1.
Page 654 of 850

Table IX-15 Upstream and Downstream Discounted Model Year Lifetime CO2 Benefits for the Given SCCO2 Value using Method B and Relative to the Less Dynamic Baseline (Millions of 2012$)a, b

Model

Year

5%

Average

3%

Average

2.5%

Average

3%,

95th Percentile

2018 $93 $380 $580 $1,100

2019 $90 $370 $570 $1,100

2020 $87 $360 $560 $1,100

2021 $520 $2,200 $3,400 $6,600

2022 $540 $2,300 $3,500 $6,900

2023 $550 $2,300 $3,600 $7,200

2024 $870 $3,700 $5,800 $11,000

2025 $900 $3,900 $6,100 $12,000

2026 $920 $4,000 $6,300 $12,000

2027 $1,100 $4,800 $7,600 $15,000

2028 $1,100 $4,800 $7,600 $15,000

2029 $1,100 $4,900 $7,700 $15,000

Sum $7,800 $34,000 $53,000 $100,000

Notes:

a The SC-CO2 values are dollar-year and emissions-year specific. 

b For an explanation of analytical Methods A and B, please see Section I.D; for an explanation 

of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

(2) Sensitivity Analysis - Monetized Non-CO2 GHG Impacts 

One limitation of the primary benefits analysis is that it does not include the valuation of 

non-CO2 GHG impacts (e.g., CH4, N2O, HFC-134a). Specifically, the 2010 and 2013 SCC 

TSDs do not include estimates of the social costs of non-CO2 GHG emissions using an approach 

analogous to the one used to estimate the SC-CO2. However, EPA recognizes that non-CO2

GHG impacts associated with this rulemaking (e.g., net reductions in CH4,N2O, and HFC-134a) 

would provide additional benefits to society. To understand the potential implication of omitting 

these benefits, EPA has conducted sensitivity analysis using two approaches: 1) an 

approximation approach based on the global warming potentials (GWP) of non-CO2 GHGs, 

which has been used in previous rulemakings, and 2) a set of recently published SC-CH4 and SCN2O estimates that are consistent with the modeling assumptions underlying the SC-CO2

estimates (Marten et al. 2014). This section presents estimates of the non-CO2 benefits of the 

proposed rulemaking using both approaches. Other unquantified non-CO2 benefits are discussed 

in this section as well. Additional details are provided in the RIA of these rules.

Currently, EPA is undertaking a peer review of the application of the Marten et al. (2014) 

non-CO2 social cost estimates in regulatory analysis. Pending a favorable peer review, EPA 

plans to include monetized benefits of CH4 and N2O emission reductions in the main benefit-cost 

analysis of the RIA for the final rule, using the directly modeled estimates of SC-CH4 and SCN2O from Marten et al. EPA seeks comments on the use of directly modeled estimates for the 

social cost of non-CO2 GHGs.
Page 655 of 850

(a) Non-CO2 GHG Benefits Based on the GWP Approximation Approach

In the absence of directly modeled estimates, one potential method for approximating the 

value of marginal non-CO2 GHG emission reductions is to convert non-CO2 emissions 

reductions to CO2-equivalents that may then be valued using the SC-CO2. Conversion to CO2-

equivalents is typically based on the global warming potentials (GWPs) for the non-CO2 gases. 

This approach, henceforth referred to as the “GWP approach,” has been used in sensitivity

analyses to estimate the non-CO2 benefits in previous EPA rulemakings (see U.S. EPA 2012, 

2013).709 EPA has not presented these estimates in a main benefit-cost analysis due to the 

limitations associated with using the GWP approach to value changes in non-CO2 GHG 

emissions, and considered the GWP approach as an interim method of analysis until social cost 

estimates for non-CO2 GHGs, consistent with the SC-CO2 estimates, were developed.

The GWP is a simple, transparent, and well-established metric for assessing the relative 

impacts of non-CO2 emissions compared to CO2 on a purely physical basis. However, as 

discussed both in the 2010 SCC TSD and previous rulemakings (e.g., U.S. EPA 2012, 2013), the 

GWP approximation approach to measuring non-CO2 GHG benefits has several welldocumented limitations. These metrics are not ideally suited for use in benefit-cost analyses to 

approximate the social cost of non-CO2 GHGs because the approach would assume all 

subsequent linkages leading to damages are linear in radiative forcing, which would be 

inconsistent with the most recent scientific literature. Detailed discussion of limitations of the 

GWP approach can be found in the RIA.

Similar to the approach used in the RIA of the Final Rulemaking for 2017-2025 LightDuty Vehicle Greenhouse Gas Emission Standards and Corporate Average Fuel Economy 

Standards (U.S. EPA, 2013), EPA applies the GWP approach to estimate the benefits associated

with reductions of CH4, N2O and HFCs in each calendar year. Under the GWP Approach, EPA 

converted CH4, N2O and HFC-134a to CO2 equivalents using the AR4 100-year GWP for each 

gas: CH4 (25), N2O (298), and HFC-134a (1,430).710 These CO2-equivalent emission reductions 

are multiplied by the SC-CO2 estimate corresponding to each year of emission reductions. As 

with the calculation of annual benefits of CO2 emission reductions, the annual benefits of nonCO2 emission reductions based on the GWP approach are discounted back to net present value 

terms using the same discount rate as each SC-CO2 estimate. The estimated non-CO2 GHG 

benefits using the GWP approach are presented in Table IX-16 through Table IX-18. The total 

net present value of the GHG benefits for this proposed rulemaking would increase by about 

 

709 U.S. EPA. (2012). “Regulatory impact analysis supporting the 2012 U.S. Environmental Protection Agency final 

new source performance standards and amendments to the national emission standards for hazardous air pollutants 

for the oil and natural gas industry.” Retrieved from 

http://www.epa.gov/ttn/ecas/regdata/RIAs/oil_natural_gas_final_neshap_nsps_ria.pdf

U.S. EPA. (2013). “Regulatory impact analysis: Final rulemaking for 2017–2025 light-duty vehicle greenhouse gas 

emission standards and corporate average fuel economy standards.” Retrieved from 

http://www.epa.gov/otaq/climate/documents/420r12016.pdf

710 Source: Table 2.14 (Errata). Lifetimes, radiative efficiencies and direct (except for CH4) GWPs relative to 

CO2. IPCC Fourth Assessment Report "Climate Change 2007: Working Group I: The Physical Science Basis."
Page 656 of 850

$760 million to $11 billion (2012$), depending on discount rate, or roughly 3 percent if these 

non-CO2 estimates were included. 

Table IX-16 Annual Upstream and Downstream CH4 Benefits for the Given SC-CO2 Value using Method B 

and Relative to the Less Dynamic Baseline, Using the GWP Approacha,b (Millions of 2012$) b

CH4

Calendar

Year

5%

Average

3%

Average

2.5%

Average

3%,

95th Percentile

2018 $0.3 $1.1 $1.6 $3.2

2019 $0.6 $2.2 $3.3 $6.6

2020 $1.0 $3.5 $5.2 $10

2021 $3.1 $11 $17 $33

2022 $6.0 $20 $30 $62

2023 $8.8 $30 $45 $93

2024 $14 $46 $68 $140

2025 $19 $62 $91 $190

2026 $25 $79 $120 $240

2027 $30 $99 $140 $300

2028 $36 $120 $170 $360

2029 $43 $140 $200 $420

2030 $49 $160 $230 $480

2035 $82 $240 $350 $760

2040 $110 $320 $440 $990

2050 $160 $440 $600 $1,400

NPV $730 $3,400 $5,400 $11,000

Notes:

a The SC-CO2 values are dollar-year and emissions-year specific

b For an explanation of analytical Methods A and B, please see Section 

I.D; for an explanation of the less dynamic baseline, 1a, and more 

dynamic baseline, 1b, please see Section X.A.1.

. 
Page 657 of 850

Table IX-17 Annual Upstream and Downstream N2O Benefits for the Given SC-CO2 Value using Method B 

and Relative to the Less Dynamic Baseline, Using the GWP Approacha,b (Millions of 2012$) b

N2O

Calendar

Year

5%

Average

3%

Average

2.5%

Average

3%,

95th Percentile

2018 $0.0 $0.0 $0.1 $0.2

2019 $0.0 $0.1 $0.2 $0.3

2020 $0.0 $0.2 $0.2 $0.5

2021 $0.1 $0.4 $0.5 $1.1

2022 $0.2 $0.6 $1.0 $1.9

2023 $0.3 $0.9 $1.4 $2.8

2024 $0.4 $1.4 $2.1 $4.4

2025 $0.6 $2.0 $2.9 $6.0

2026 $0.8 $2.6 $3.7 $7.8

2027 $1.0 $3.2 $4.7 $10

2028 $1.2 $3.9 $5.7 $12

2029 $1.5 $4.6 $6.6 $14

2030 $1.6 $5.3 $7.7 $16

2035 $2.8 $8.3 $12 $26

2040 $3.8 $11 $15 $34

2050 $5.6 $15 $21 $47

NPV $25 $120 $180 $360

Notes:

a The SC-CO2 values are dollar-year and emissions-year specific. 

b For an explanation of analytical Methods A and B, please see 

Section I.D; for an explanation of the less dynamic baseline, 1a, 

and more dynamic baseline, 1b, please see Section X.A.1.
Page 658 of 850

Table IX-18 Annual Upstream and Downstream HFC-134a Benefits for the Given SC-CO2 Value using 

Method B and Relative to the Less Dynamic Baseline, Using the GWP Approacha,b (Millions of 2012$) b

HFC-134a

Calendar

Year

5%

Average

3%

Average

2.5%

Average

3%,

95th Percentile

2018 $0.0 $0.0 $0.0 $0.0

2019 $0.0 $0.0 $0.0 $0.0

2020 $0.0 $0.0 $0.0 $0.0

2021 $0.2 $0.8 $1.3 $2.6

2022 $0.5 $1.7 $2.6 $5.3

2023 $0.8 $2.7 $4.0 $8.1

2024 $1.1 $3.7 $5.4 $11

2025 $1.4 $4.7 $6.9 $14

2026 $1.8 $5.9 $8.6 $18

2027 $2.2 $7.1 $10 $22

2028 $2.5 $8.3 $12 $25

2029 $3.0 $10 $14 $29

2030 $3.4 $11 $16 $34

2035 $5.2 $15 $22 $48

2040 $6.1 $18 $25 $56

2050 $8.4 $23 $31 $71

NPV $44 $200 $320 $630

Notes:

a The SC-CO2 values are dollar-year and emissions-year specific. 

b For an explanation of analytical Methods A and B, please see 

Section I.D; for an explanation of the less dynamic baseline, 1a, 

and more dynamic baseline, 1b, please see Section X.A.1.

(b) Non-CO2 GHG Benefits Based on Directly Modeled Estimates

Several researchers have directly estimated the social cost of non-CO2 emissions using 

integrated assessment models (IAMs), though the number of such estimates is small compared to 

the large number of SC-CO2 estimates available in the literature. As discussed in previous RIAs 

(e.g., EPA 2012), there is considerable variation among these published estimates in the models 

and input assumptions they employ. These studies differ in the emission perturbation year, 

employ a wide range of constant and variable discount rate specifications, and consider a range 

of baseline socioeconomic and emissions scenarios that have been developed over the last 20 

years. However, none of the other published estimates of the social cost of non-CO2 GHG are 

consistent with the SC-CO2 estimates, and most are likely underestimates due to changes in the 

underlying science since their publication. 
Page 659 of 850

Recently, a paper by Marten et al. (2014) provided the first set of published SC-CH4 and 

SC-N2O estimates that are consistent with the modeling assumptions underlying the SC-CO2.

711

Specifically, the estimation approach of Marten et al. (2014) used the same set of three IAMs, 

five socioeconomic-emissions scenarios, equilibrium climate sensitivity distribution, three 

constant discount rates, and aggregation approach used to develop the SC-CO2 estimates.

The resulting SC-CH4 and SC-N2O estimates are presented in Table IX-19. More 

detailed discussion of their methodology, results and a comparison to other published estimates 

can be found in the RIA and in Marten et al. (2014). The tables do not include HFC-134a

because EPA is unaware of analogous estimates.

Table IX-19 Social Cost of CH4 and N2O, 2012 – 2050a[in 2012$ per metric ton] (Source: Marten et al., 2014)

Year SC-CH4 SC-N2O

5%

Average

3%

Average

2.5%

Average

3%

95th

percentile

5%

Average

3% 

Average

2.5% 

Average

3%

95th

percentile

2012 $440 $1000 $1400 $2800 $4000 $14000 $20000 $37000

2015 500 1200 1500 3100 4400 15000 22000 39000

2020 590 1300 1700 3500 5200 16000 24000 44000

2025 710 1500 19000 4100 6000 18000 27000 50000

2030 840 1700 2300 4600 7000 20000 29000 55000

2035 990 2000 2500 5400 8100 23000 32000 61000

2040 1200 2300 2800 6000 9300 25000 35000 67000

2045 1300 2500 3100 6800 11000 27000 38000 73000

2050 1500 2700 3300 7400 12000 290000 41000 80000

Notes:

a The values are emissions-year specific and have been rounded to two significant digits. Unrounded numbers were 

used to calculate the GHG benefits.

The application of directly modeled estimates from Marten et al. (2014) to benefit-cost 

analysis of a regulatory action is analogous to the use of the SC-CO2 estimates. Specifically, the 

SC-CH4 and SC-N2O estimates in Table IX-19 are used to monetize the benefits of changes in 

CH4 and N2O emissions expected as a result of the proposed rulemaking. Forecast changes in 

CH4 and N2O emissions in a given year resulting from the regulatory action are multiplied by the 

SC-CH4 and SC-N2O estimate for that year, respectively. To obtain a present value estimate, the 

monetized stream of future non-CO2 benefits are discounted back to the analysis year using the 

same discount rate used to estimate the social cost of the non-CO2 GHG emission changes.

The CH4 and N2O benefits based on Marten et al. (2014) are presented for each calendar 

year in Table IX-20. Including these benefits would increase the total net present value of the

GHG benefits for this proposed rulemaking by about $1.5 billion to $12 billion (2012$), or 

roughly 4 to 7 percent, depending on discount rate. 

 

711 Marten, A. L., E. A. Kopits, C. W. Griffiths, S. C. Newbold & A. Wolverton (2014). Incremental CH4 and N2O 

mitigation benefits consistent with the U.S. Government's SC-CO2 estimates, Climate Policy, DOI: 

10.1080/14693062.2014.912981.
Page 660 of 850

Table IX-20 Annual Upstream and Downstream non-CO2 GHG Benefits for the Given SC-non-CO2 Value

using Method B and Relative to the Less Dynamic Baseline, Using the Directly Modeled Approacha,b (Millions 

of 2012$) c

CH4 N2O

Calendar

Year

5%

Average

3%

Average

2.5%

Average

3%,

95th Percentile

5%

Average

3%

Average

2.5%

Average

3%,

95th Percentile

2018 $0.6 $1.3 $1.6 $3.3 $0.0 $0.1 $0.1 $0.2

2019 $1.1 $2.6 $3.4 $6.8 $0.0 $0.1 $0.2 $0.3

2020 $1.8 $3.9 $5.2 $10 $0.1 $0.2 $0.3 $0.5

2021 $5.8 $13 $17 $35 $0.1 $0.4 $0.6 $1.2

2022 $11 $24 $31 $65 $0.3 $0.8 $1.1 $2.1

2023 $17 $35 $49 $97 $0.4 $1.1 $1.7 $3.1

2024 $26 $56 $72 $150 $0.6 $1.8 $2.5 $4.7

2025 $35 $74 $95 $200 $0.8 $2.4 $3.5 $6.5

2026 $46 $99 $130 $260 $1.0 $3.0 $4.5 $8.4

2027 $57 $120 $150 $320 $1.3 $4.0 $5.8 $11

2028 $69 $140 $190 $390 $1.6 $4.8 $6.9 $13

2029 $82 $170 $220 $460 $1.9 $5.8 $8.2 $15

2030 $95 $190 $260 $520 $2.2 $6.5 $9.3 $18

2035 $160 $330 $400 $870 $3.7 $10 $15 $28

2040 $230 $430 $540 $1,200 $5.2 $14 $19 $37

2050 $350 $620 $770 $1,700 $7.9 $20 $27 $53

NPV $1,500 $4,600 $6,400 $12,000 $34 $150 $230 $400

Notes:

a The SC-CH4 and SC-N2O values are dollar-year and emissions-year specific. 

b Note that net present discounted values of reduced GHG emissions is are calculated differently than other 

benefits. The same discount rate used to discount the value of damages from future emissions (SC-CH4 and SCN2O at 5, 3, and 2.5 percent) is used to calculate net present value discounted values of SC-CH4 and SC- N2O for 

internal consistency. Refer to SCC TSD for more detail.

c For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

As illustrated above, compared to the use of directly modeled estimates the GWP-based 

approximation approach underestimates the climate benefits of the CH4 emission reductions by

12 percent to 52 percent and the climate benefits of N2O reductions by 10 percent to 26 percent, 

depending on the discount rate assumption.

(c) Additional non-CO2 GHGs Co-benefits

In determining the relative social costs of the different gases, the Marten et al. (2014) 

analysis accounts for differences in lifetime and radiative efficiency between the non-CO2 GHGs 

and CO2. The analysis also accounts for radiative forcing resulting from methane’s effects on 

tropospheric ozone and stratospheric water vapor, and for at least some of the fertilization effects 

of elevated carbon dioxide concentrations. However, there exist several other differences 

between these gases that have not yet been captured in this analysis, namely the non-radiative 

effects of methane-driven elevated tropospheric ozone levels on human health, agriculture, and 

ecosystems, and the effects of carbon dioxide on ocean acidification. Inclusion of these 
Page 661 of 850

additional non-radiative effects would potentially change both the absolute and relative value of 

the various gases.

Of these effects, the human health effect of elevated tropospheric ozone levels resulting 

from methane emissions is the closest to being monetized in a way that would be comparable to 

the SCC. Premature ozone-related cardiopulmonary deaths resulting from global increases in 

tropospheric ozone concentrations produced by the methane oxidation process have been the 

focus of a number of studies over the past decade (e.g., West et al. 2006712). Recent studies have 

produced an estimate of a monetized benefit of methane emissions reductions, with results on the 

order of $1000 per metric ton of CH4 emissions reduced (Anenberg et al. 2012713; Shindell et al. 

2012714), an estimate similar in magnitude to the climate benefits of CH4 reductions estimated by

the Marten et al. or GWP methods. However, though EPA is continuing to monitor this area of 

research as it evolves, EPA is not applying them for benefit estimates at this time. 

H. Monetized Non-GHG Health Impacts

This section analyzes the economic benefits from reductions in health and environmental 

impacts resulting from non-GHG emission reductions that can be expected to occur as a result of 

the proposed Phase 2 standards. CO2 emissions are predominantly the byproduct of fossil fuel 

combustion processes that also produce criteria and hazardous air pollutant emissions. The 

vehicles that are subject to the proposed standards are also significant sources of mobile source 

air pollution such as direct PM, NOX, VOCs and air toxics. The proposed standards would affect 

exhaust emissions of these pollutants from vehicles and would also affect emissions from 

upstream sources that occur during the refining and distribution of fuel. Changes in ambient 

concentrations of ozone, PM2.5, and air toxics that would result from the proposed standards are 

expected to affect human health by reducing premature deaths and other serious human health 

effects, as well as other important improvements in public health and welfare. 

It is important to quantify the health and environmental impacts associated with the 

proposed standards because a failure to adequately consider these ancillary impacts could lead to 

an incorrect assessment of their costs and benefits. Moreover, the health and other impacts of 

exposure to criteria air pollutants and airborne toxics tend to occur in the near term, while most

effects from reduced climate change are likely to occur only over a time frame of several decades 

or longer. 

 

712 West JJ, Fiore AM, Horowitz LW, Mauzerall DL (2006) Global health benefits of mitigating ozone pollution 

with methane emission controls. Proc Natl Acad Sci USA 103 (11):3988-3993. doi:10.1073/pnas.0600201103 

713 Anenberg SC, Schwartz J, Shindell D, Amann M, Faluvegi G, Klimont Z, ..., Vignati E (2012) Global air quality 

and health co-benefits of mitigating near-term climate change through methane and black carbon emission controls. 

Environ Health Perspect 120 (6):831. doi:10.1289/ehp.1104301

714 Shindell D, Kuylenstierna JCI, Vignati E, van Dingenen R, Amann M, Klimont Z, ..., Fowler D (2012) 

Simultaneously Mitigating Near-Term Climate Change and Improving Human Health and Food Security. Science 

335 (6065):183-189. doi:10.1126/science.1210026
Page 662 of 850

Although EPA typically quantifies and monetizes the health and environmental impacts 

related to both PM and ozone in its regulatory impact analyses (RIAs), it was unable to do so in 

time for this proposal. Instead, EPA has applied PM-related “benefits per-ton” values to its 

estimated emission reductions as an interim approach to estimating the PM-related benefits of 

the proposal.715,716 EPA also characterizes the health and environmental impacts that will be 

quantified and monetized for the final rulemaking. 

This section is split into two sub-sections: the first presents the benefits-per-ton values 

used to monetize the benefits from reducing population exposure to PM associated with the 

proposed standards; the second explains what PM- and ozone-related health and environmental 

impacts EPA will quantify and monetize in the analysis for the final rule. EPA bases its analyses 

on peer-reviewed studies of air quality and health and welfare effects and peer-reviewed studies 

of the monetary values of public health and welfare improvements, and is generally consistent 

with benefits analyses performed for the analysis of the final Tier 3 Vehicle Rule,717 the final 

2012 PM NAAQS Revision,718 and the final 2017-2025 Light Duty Vehicle GHG Rule.719 

Though EPA is characterizing the changes in emissions associated with toxic pollutants, 

we are not able to quantify or monetize the human health effects associated with air toxic 

pollutants for either the proposal or the final rule analyses (see Section VIII.G.1.b.iii for more 

information). Please refer to Section VIII for more information about the air toxics emissions 

impacts associated with the proposed standards.

(1) Economic Value of Reductions in Criteria Pollutants

As described in Section VIII, the proposed standards would reduce emissions of several 

criteria and toxic pollutants and their precursors. In this analysis, EPA estimates the economic 

value of the human health benefits associated with the resulting reductions in PM2.5 exposure. 

Due to analytical limitations with the benefit per ton method, this analysis does not estimate 

 

715 Fann, N., Baker, K.R., and Fulcher, C.M. (2012). Characterizing the PM2.5-related health benefits of emission 

reductions for 17 industrial, area and mobile emission sectors across the U.S., Environment International, 49, 241-

151, published online September 28, 2012.

716 See also: http://www.epa.gov/airquality/benmap/sabpt.html. The current values available on the webpage have 

been updated since the publication of the Fann et al., 2012 paper. For more information regarding the updated 

values, see: http://www.epa.gov/airquality/benmap/models/Source_Apportionment_BPT_TSD_1_31_13.pdf

(accessed September 9, 2014).

717 U.S. Environmental Protection Agency. (2014). Control of Air Pollution from Motor Vehicles: Tier 3 Motor 

Vehicle Emission and Fuel Standards Final Rule: Regulatory Impact Analysis, Assessment and Standards Division, 

Office of Transportation and Air Quality, EPA-420-R-14-005, March 2014. Available on the internet: 

http://www.epa.gov/otaq/documents/tier3/420r14005.pdf

718 U.S. Environmental Protection Agency. (2012). Regulatory Impact Analysis for the Final Revisions to the 

National Ambient Air Quality Standards for Particulate Matter, Health and Environmental Impacts Division, Office 

of Air Quality Planning and Standards, EPA-452-R-12-005, December 2012. Available on the internet: 

http://www.epa.gov/ttnecas1/regdata/RIAs/finalria.pdf

719 U.S. Environmental Protection Agency (U.S. EPA). (2012). Regulatory Impact Analysis: Final Rulemaking for 

2017-2025 Light-Duty Vehicle Greenhouse Gas Emission Standards and Corporate Average Fuel Economy 

Standards, Assessment and Standards Division, Office of Transportation and Air Quality, EPA-420-R-12-016, 

August 2012. Available on the Internet at: http://www.epa.gov/otaq/climate/documents/420r12016.pdf
Page 663 of 850

benefits resulting from reductions in population exposure to other criteria pollutants such as 

ozone. 720 Furthermore, the benefits per-ton method, like all air quality impact analyses, does not 

monetize all of the potential health and welfare effects associated with reduced concentrations of 

PM2.5.

This analysis uses estimates of the benefits from reducing the incidence of the specific 

PM2.5-related health impacts described below. These estimates, which are expressed per ton of

PM2.5-related emissions eliminated by the proposed rules, represent the monetized value of

human health benefits (including reductions in both premature mortality and premature 

morbidity) from reducing each ton of directly emitted PM2.5 or its precursors (SO2 and NOx), 

from a specified source. Ideally, the human health benefits would be estimated based on changes 

in ambient PM2.5 as determined by full-scale air quality modeling. However, the length of time 

needed to prepare the necessary emissions inventories, in addition to the processing time 

associated with the modeling itself, has precluded us from performing air quality modeling for 

this proposal. We will conduct this modeling for the final rule. 

The dollar-per-ton estimates used in this analysis are provided in Table IX-21. As the 

table indicates, these values differ among pollutants, and also depend on their original source, 

because emissions from different sources can result in different degrees of population exposure 

and resulting health impacts. In the summary of costs and benefits, Section IX.K of this

preamble, EPA presents the monetized value of PM-related improvements associated with the 

proposal.

 

720 The air quality modeling that underlies the PM-related benefit per ton values also produced estimates of ozone 

levels attributable to each sector. However, the complex non-linear chemistry governing ozone formation prevented 

EPA from developing a complementary array of ozone benefit per ton values. This limitation notwithstanding, we 

anticipate that the ozone-related benefits associated with reducing emissions of NOX and VOC could be substantial.
Page 664 of 850

Table IX-21 Benefits-per-ton Values (Thousands, 2012$)a

Yearc On-road Mobile Sources Upstream Sourcesd

Direct PM2.5 SO2 NOX Direct PM2.5 SO2 NOX

Estimated Using a 3 Percent Discount Rateb

2016 $380-$850 $20-$45 $7.7-$18 $330-$750 $69-$160 $6.8-$16

2020 $400-$910 $22-$49 $8.1-$18 $350-$790 $75-$170 $7.4-$17

2025 $440-$1,000 $24-$55 $8.8-$20 $390-$870 $83-$190 $8.1-$18

2030 $480-$1,100 $27-$61 $9.6-$22 $420-$950 $91-$200 $8.7-$20

Estimated Using a 7 Percent Discount Rateb

2016 $340-$770 $18-$41 $6.9-$16 $290-$670 $63-$140 $6.2-$14

2020 $370-$820 $20-$44 $7.4-$17 $320-$720 $67-$150 $6.6-$15

2025 $400-$910 $22-$49 $8.0-$18 $350-$790 $75-$170 $7.3-$17

2030 $430-$980 $24-$55 $8.6-$20 $380-$850 $81-$180 $7.9-$18

Notes:

a The benefit-per-ton estimates presented in this table are based on a range of premature mortality estimates derived 

from the ACS study (Krewski et al., 2009) and the Six-Cities study (Lepeule et al., 2012). See Chapter VIII of the 

RIA for a description of these studies.

b The benefit-per-ton estimates presented in this table assume either a 3 percent or 7 percent discount rate in the 

valuation of premature mortality to account for a twenty-year segmented premature mortality cessation lag. 

c Benefit-per-ton values were estimated for the years 2016, 2020, 2025 and 2030. We hold values constant for 

intervening years (e.g., the 2016 values are assumed to apply to years 2017-2019; 2020 values for years 2021-2024; 

2030 values for years 2031 and beyond). 

d We assume for the purpose of this analysis that total “upstream emissions” are most appropriately monetized using 

the refinery sector benefit per-ton values. The majority of upstream emission reductions associated with the NPRM 

are related to domestic onsite refinery emissions and domestic crude production. While total upstream emissions 

also include storage and transport sources, as well as sources upstream from the refinery, we have chosen to simply 

apply the refinery values. Full-scale air quality modeling, and the associated benefits analysis, will include upstream 

emissions from all sources in the FRM.

The benefit-per-ton technique has been used in previous analyses, including EPA’s 2017-

2025 Light-Duty Vehicle Greenhouse Gas Rule,721 the Reciprocating Internal Combustion 

Engine rules,722,723 and the Residential Wood Heaters NSPS.724 Table IX-22 shows the 

 

721 U.S. Environmental Protection Agency (U.S. EPA). (2012). Regulatory Impact Analysis: Final Rulemaking for 

2017-2025 Light-Duty Vehicle Greenhouse Gas Emission Standards and Corporate Average Fuel Economy 

Standards, Assessment and Standards Division, Office of Transportation and Air Quality, EPA-420-R-12-016, 

August 2012. Available on the Internet at: http://www.epa.gov/otaq/climate/documents/420r12016.pdf

722 U.S. Environmental Protection Agency (U.S. EPA). (2013). Regulatory Impact Analysis for the Reconsideration 

of the Existing Stationary Compression Ignition (CI) Engines NESHAP, Office of Air Quality Planning and 

Standards, Research Triangle Park, NC. January. EPA-452/R-13-001. Available at 

<http://www.epa.gov/ttnecas1/regdata/RIAs/RICE_NESHAPreconsideration_Compression_Ignition_Engines_RIA_

final2013_EPA.pdf>

723 U.S. Environmental Protection Agency (U.S. EPA). (2013). Regulatory Impact Analysis for Reconsideration of 

Existing Stationary Spark Ignition (SI) RICE NESHAP, Office of Air Quality Planning and Standards, Research 

Triangle Park, NC. January. EPA-452/R-13-002. Available at 

<http://www.epa.gov/ttnecas1/regdata/RIAs/NESHAP_RICE_Spark_Ignition_RIA_finalreconsideration2013_EPA.

pdf>

724 U.S. Environmental Protection Agency (U.S. EPA). (2015). Regulatory Impact Analysis for Residential Wood 

Heaters NSPS Revision. Office of Air Quality Planning and Standards, Research Triangle Park, NC. February. 
Page 665 of 850

quantified PM2.5-related co-benefits captured in those benefit per-ton estimates, as well as 

unquantified effects the benefit per-ton estimates are unable to capture.

Table IX-22 Human Health and Welfare Effects of PM2.5

Pollutant / 

Effect

Quantified and Monetized 

in Primary Estimates

Unquantified Effects 

Changes in:

PM2.5 Adult premature mortality 

Acute bronchitis

Hospital admissions: respiratory and 

cardiovascular

Emergency room visits for asthma

Nonfatal heart attacks (myocardial infarction)

Lower and upper respiratory illness

Minor restricted-activity days

Work loss days

Asthma exacerbations (asthmatic population)

Infant mortality

Chronic and subchronic bronchitis cases

Strokes and cerebrovascular disease

Low birth weight

Pulmonary function

Chronic respiratory diseases other than chronic 

bronchitis

Non-asthma respiratory emergency room visits

Visibility

Household soiling

A more detailed description of the benefit-per-ton estimates is provided in Chapter VIII 

of the Draft RIA that accompanies this rulemaking. Readers interested in reviewing the 

complete methodology for creating the benefit-per-ton estimates used in this analysis can consult 

EPA’s “Technical Support Document: Estimating the Benefit per Ton of Reducing PM2.5

Precursors from 17 Sectors.”725 Readers can also refer to Fann et al. (2012)726 for a detailed 

description of the benefit-per-ton methodology. 

As Table IX-20 indicates, EPA projects that the per-ton values for reducing emissions of 

non-GHG pollutants from both vehicle use and upstream sources such as fuel refineries will 

increase over time.

727

 These projected increases reflect rising income levels, which increase 

affected individuals’ willingness to pay for reduced exposure to health threats from air 

pollution.728 They also reflect future population growth and increased life expectancy, which 

 

EPA-452/R-15-001. Available at <http://www2.epa.gov/sites/production/files/2015-02/documents/20150204-

residential-wood-heaters-ria.pdf>

725 For more information regarding the updated values, see: 

http://www.epa.gov/airquality/benmap/models/Source_Apportionment_BPT_TSD_1_31_13.pdf (accessed 

September 9, 2014).

726 Fann, N., Baker, K.R., and Fulcher, C.M. (2012). Characterizing the PM2.5-related health benefits of emission 

reductions for 17 industrial, area and mobile emission sectors across the U.S., Environment International, 49, 241-

151, published online September 28, 2012.

727 As we discuss in the emissions chapter of the DRIA (Chapter V), the rule would yield emission reductions from 

upstream refining and fuel distribution due to decreased petroleum consumption.

728 The issue is discussed in more detail in the 2012 PM NAAQS RIA, Section 5.6.8. See U.S. Environmental 

Protection Agency. (2012). Regulatory Impact Analysis for the Final Revisions to the National Ambient Air Quality 

Standards for Particulate Matter, Health and Environmental Impacts Division, Office of Air Quality Planning and 

Standards, EPA-452-R-12-005, December 2012. Available on the internet: 

http://www.epa.gov/ttnecas1/regdata/RIAs/finalria.pdf
Page 666 of 850

expands the size of the population exposed to air pollution in both urban and rural areas, 

especially among older age groups with the highest mortality risk.729 

(2) Human Health and Environmental Benefits for the Final Rule 

(a) Human Health and Environmental Impacts 

To model the ozone and PM air quality benefits of the final rule, EPA will use the 

Community Multiscale Air Quality (CMAQ) model (see Section VIII for a description of the 

CMAQ model). The modeled ambient air quality data will serve as an input to the 

Environmental Benefits Mapping and Analysis Program – Community Edition (BenMAP CE).730 

BenMAP CE is a computer program developed by EPA that integrates a number of the modeling 

elements used in previous RIAs (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. 

Chapter VIII in the DRIA that accompanies this proposal lists the co-pollutant health 

effect concentration-response functions EPA will use to quantify the non-GHG incidence 

impacts associated with the proposed heavy-duty vehicle standards. These include PM- and 

ozone-related premature mortality, nonfatal heart attacks, hospital admissions (respiratory and 

cardiovascular), emergency room visits, acute bronchitis, minor restricted activity days, and days 

of work and school lost.

(b) Monetized Impacts

To calculate the total monetized impacts associated with quantified health impacts, EPA 

applies values derived from a number of sources. For premature mortality, EPA applies a value 

of a statistical life (VSL) derived from the mortality valuation literature. For certain health 

impacts, such as a number of respiratory-related ailments, EPA applies willingness-to-pay

estimates derived from the valuation literature. For the remaining health impacts, EPA applies 

values derived from current cost-of-illness and/or wage estimates. Chapter VIII in the DRIA that 

accompanies this proposal presents the monetary values EPA will apply to changes in the 

incidence of health and welfare effects associated with reductions in non-GHG pollutants that 

will occur when these GHG control strategies are finalized.

(c) Other Unquantified Health and Environmental Impacts

In addition to the co-pollutant health and environmental impacts EPA will quantify for 

the analysis of the final standard, there are a number of other health and human welfare 

endpoints that EPA will not be able to quantify or monetize because of current limitations in the 

methods or available data. These impacts are associated with emissions of air toxics (including 

 

729 For more information about EPA’s population projections, please refer to the following: 

http://www.epa.gov/air/benmap/models/BenMAPManualAppendicesAugust2010.pdf (See Appendix K)

730 Information on BenMAP, including downloads of the software, can be found at http://www.epa.gov/air/benmap/
Page 667 of 850

benzene, 1,3-butadiene, formaldehyde, acetaldehyde, acrolein, naphthalene and ethanol), 

ambient ozone, and ambient PM2.5 exposures. Chapter VIII of the DRIA lists these unquantified 

health and environmental impacts.

While there will be impacts associated with air toxic pollutant emission changes that 

result from the final standard, EPA will 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). EPA’s 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.731 While EPA has since 

improved the tools, there remain critical limitations for estimating incidence and assessing 

benefits of reducing mobile source air toxics.732 EPA continues to work to address these 

limitations; however, EPA does not anticipate having methods and tools available for nationalscale application in time for the analysis of the final rules.733

 

I. Energy Security Impacts

The Phase 2 standards are designed to require improvements in the fuel efficiency of 

medium- and heavy-duty vehicles and, thereby, reduce fuel consumption and GHG emissions.

In turn, the Phase 2 standards help to reduce U.S. petroleum imports. A reduction of U.S. 

petroleum imports reduces both financial and strategic risks caused by potential sudden 

disruptions in the supply of imported petroleum to the U.S., thus increasing U.S. energy security. 

This section summarizes the agency’s estimates of U.S. oil import reductions and energy security 

benefits of the proposed Phase 2 standards. Additional discussion of this issue can be found in 

Chapter 8 of the draft RIA.

 

731 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.

732 Examples include gaps in toxicological data, uncertainties in extrapolating results from high-dose animal 

experiments to estimate human effects at lower does, limited ambient and personal exposure monitoring data, and 

insufficient economic research to support valuation of the health impacts often associated with exposure to 

individual air toxics. See Gwinn et al., 2011. Meeting Report: Estimating the Benefits of Reducing Hazardous Air 

Pollutants – Summary of 2009 Workshop and Future Considerations. Environ Health Perspect. Jan 2011; 119(1): 

125-130. 

733 In April, 2009, EPA hosted a workshop on estimating the benefits of reducing hazardous air pollutants. This 

workshop built upon the work accomplished in the June 2000 in an earlier (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.
Page 668 of 850

(1) Implications of Reduced Petroleum Use on U.S. Imports

U.S. energy security is broadly defined as the continued availability of energy sources at 

an acceptable price. Most discussion of U.S. energy security revolves around the topic of the 

economic costs of U.S. dependence on oil imports. However, it is not imports alone, but both 

imports and consumption of petroleum from all sources and their role in economic activity, that 

expose the U.S. to risk from price shocks in the world oil price. The relative significance of 

petroleum consumption and import levels for the macroeconomic disturbances that follow from 

oil price shocks is not fully understood. Recognizing that changing petroleum consumption will 

change U.S. imports, this assessment of oil costs focuses on those incremental social costs that 

follow from the resulting changes in imports, employing the usual oil import premium measure. 

The agencies request comment on how to incorporate the impact of changes in oil consumption, 

rather than imports exclusively, into our energy security analysis. 

While the U.S. has reduced its consumption and increased its production of oil in recent 

years, it still relies on oil from potentially unstable sources. In addition, oil exporters with a 

large share of global production have the ability to raise the price of oil by exerting the 

monopoly power associated with a cartel, the Organization of Petroleum Exporting Countries 

(OPEC), to restrict oil supply relative to demand. These factors contribute to the vulnerability of 

the U.S. economy to episodic oil supply shocks and price spikes. In 2012, U.S. net expenditures 

for imports of crude oil and petroleum products were $290 billion and expenditures on both 

imported oil and domestic petroleum and refined products totaled $634 billion (see Figure IX1).734

 Import costs have declined since 2011 but total oil expenditures (domestic and imported) 

remain near historical highs, at roughly triple the inflation-adjusted levels experienced by the 

U.S. from 1986 to 2002. 

In 2010, just over 40 percent of world oil supply came from OPEC nations and the AEO 

2014 (Early Release)735 projects that this share will rise gradually to over 45 percent by 2040.

Approximately 31 percent of global supply is from Middle East and North African countries 

alone, a share that is also expected to grow. Measured in terms of the share of world oil 

resources or the share of global oil export supply, rather than oil production, the concentration of 

global petroleum resources in OPEC nations is even larger. As another measure of 

concentration, of the 137 countries/principalities that export either crude or refined products, the 

top 12 have recently accounted for over 55 percent of exports.736 Eight of these countries are 

members of OPEC, and a ninth is Russia.737 In a market where even a 1-2 percent supply loss 

can raise prices noticeably, and where a 10 percent supply loss could lead to an unprecedented 

 

734

 See EIA Annual Energy Review, various editions. For data 2011-2013, and projected data: EIA Annual Energy 

Outlook (AEO) 2014 (Reference Case). See Table 11, file "aeotab_11.xls"

735 The agencies used the AEO 2014 (Early Release) since this version of AEO was available at the time that fuel 

savings from the rule were being estimated. The AEO 2014 (Early Release) and the AEO 2014 have very similar 

energy market and economic projections. For example, world oil prices are the same between the two forecasts.

736 Based on data from the CIA, combining various recent years, https://www.cia.gov/library/publications/the-worldfactbook/rankorder/2242rank.html

737 The other three are Norway, Canada, and the EU, an exporter of product.
Page 669 of 850

price shock, this regional concentration is of concern.738 Historically, the countries of the Middle 

East have been the source of eight of the ten major world oil disruptions739, with the ninth 

originating in Venezuela, an OPEC country, and the tenth being Hurricanes Katrina and Rita.

 

738 For example, the 2005 Hurricanes Katrina/Rita and the 2011 Libyan conflict both led to a 1.8 percent reduction 

in global crude supply. While the price impact of the latter is not easily distinguished given the rapidly rising postrecession prices, the former event was associated with a 10-15 percent world oil price increase. There are a range of 

smaller events with smaller but noticeable impacts. Somewhat larger events, such as the 2002/3 Venezuelan Strike 

and the War in Iraq, corresponded to about a 2.9 percent sustained loss of supply, and was associated with a 28 

percent world oil price increase. 

Compiled from EIA oil price data, IEA2012 [IEA Response System for Oil Supply Emergencies 

(http://www.iea.org/publications/freepublications/publication/EPPD_Brochure_English_2012_02.pdf) 

See table on P. 11.and Hamilton 2011 "Historical Oil Shocks,"(http://econweb.ucsd.edu/~jhamilto/oil_history.pdf) 

in *Routledge Handbook of Major Events in Economic History*, pp. 239-265, edited by Randall E. Parker and 

Robert Whaples, New York: Routledge Taylor and Francis Group, 2013).

739 IEA 2011 “IEA Response System for Oil Supply Emergencies.”
Page 670 of 850

Figure IX-1 U.S. Expenditures on Crude Oil from 1970 through 2015740

 

740 For historical data: EIA Annual Energy Review, various editions. For data 2011-2013, and projected data: EIA 

Annual Energy Outlook (AEO) 2014 (Reference Case). See Table 11, file "aeotab_11.xls"
Page 671 of 850

The agencies used EPA’s MOVES model to estimate the reductions in U.S. fuel 

consumption due to this proposed rule for vocational vehicles and tractors. For HD pickups and 

vans, the agencies used both DOT’s CAFE model and EPA’s MOVES model to estimate the fuel 

consumption impacts. (Detailed explanations of the MOVES and CAFE models can be found in 

Chapters 5 and 10 of the draft RIA. See IX.C of the preamble for estimates of reduced fuel 

consumption from the proposed rule). Based on a detailed analysis of differences in U.S. fuel 

consumption, petroleum imports, and imports of petroleum products, the agencies estimate that 

approximately 90 percent of the reduction in fuel consumption resulting from adopting improved 

GHG emission standards and fuel efficiency standards is likely to be reflected in reduced U.S. 

imports of crude oil and net imported petroleum products.741 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 0.90 gallons.742 Based upon the fuel savings estimated 

by the MOVES/CAFE models and the 90 percent oil import factor, the reduction in U.S. oil 

imports from these proposed rules are estimated for the years 2020, 2025, 2030, 2040, and 2050 

(in millions of barrels per day (MMBD)) in Table IX-25 below. For comparison purposes, Table 

IX-25 also shows U.S. imports of crude oil in 2020, 2025, 2030 and 2040 as projected by DOE 

in the Annual Energy Outlook 2014 (Early Release) Reference Case. U.S. Gross Domestic 

Product (GDP) is projected to grow by roughly 59 percent over the same time frame (e.g., from 

2020 to 2040) in the same AEO projections.

 

741 We looked at changes in crude oil imports and net petroleum products in the Reference Case in comparison to 

two cases from the AEO 2014. The two cases are the Low (i.e., Economic Growth) Demand and Low VMT cases. 

See the spreadsheet “Impacts on Fuel Demands and ImportsJan9.xlsx” comparing the AEO 2014 Reference Case to 

the Low Demand Case. See the spreadsheet “Impact of Fuel Demand and Impacts January20VMT.xlsl” for a 

comparison of AEO 2014 Reference Case and the Low VMT Case. We also considered a paper entitled “Effect of a 

U.S. Demand Reduction on Imports and Domestic Supply Levels” by Paul Leiby, 4/16/2013. This paper suggests 

that “Given a particular reduction in oil demand stemming from a policy or significant technology change, the 

fraction of oil use savings that shows up as reduced U.S. imports, rather than reduced U.S. supply, is actually quite 

close to 90 percent, and probably close to 95 percent”.

742 The NHTSA analysis uses a slightly different value that was estimated using unique runs of the National Energy 

Modeling System (NEMS) that forms the foundation of the Annual Energy Outlook. NHTSA ran a version of 

NEMS from 2012 (which would have been used in the 2013 AEO) and computed the change in imports of 

petroleum products with and without the Phase 1 MDHD program to estimate the relationship between changes in 

fuel consumption and oil imports. The analysis found that reducing gasoline consumption by 1 gallon reduces 

imports of refined gasoline by 0.06 gallons and domestic refining from imported crude by 0.94 gallons. Similarly, 

one gallon of diesel saved by the Phase 1 rule was estimated to reduce imports of refined diesel by 0.26 gallons and 

domestic refining of imported crude by 0.74 gallons. The agencies will update this analysis for the Final Rule using 

the model associated with AEO2014, modeling the Phase 2 Preferred Alternative explicitly.
Page 672 of 850

Table IX-23 Projected U.S. Imports of Crude Oil and U.S. Oil Import Reductions Resulting from the 

Proposed Phase 2 Heavy-Duty Vehicle Rule in 2020, 2025, 2030, 2040 and 2050 using Method B and Relative 

to the Less Dynamic Baseline

(Millions of barrels per day (MMBD) b

Year U.S. Oil 

Imports

Reductions from 

Proposed HD Rule

2020 4.93 0.01

2025 5.04 0.16

2030 5.35 0.37

2040 5.92 0.65

2050 * 0.78

Notes:

* The AEO 2014 (Early Release) only projects energy market 

and economic trends through 2040.

b For an explanation of analytical Methods A and B, please see 

Section I.D; for an explanation of the less dynamic baseline, 1a, 

and more dynamic baseline, 1b, please see Section X.A.1.

(2) Energy Security Implications

In order to understand the energy security implications of reducing U.S. oil imports, EPA 

has worked with Oak Ridge National Laboratory (ORNL), which has developed approaches for 

evaluating the social 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 ORNL study is an updated version of the approach used for estimating the energy

security benefits of U.S. oil import reductions developed in a 1997 ORNL Report.

743 For EPA 

and NHTSA rulemakings, the ORNL methodology is updated periodically to account for 

forecasts of future energy market and economic trends reported in the U.S. Energy Information 

Administration’s Annual Energy Outlook. 

When conducting this analysis, ORNL considered the full cost of importing petroleum 

into the U.S. The full economic cost 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 U.S. demand on the world oil price (i.e., the “demand” or “monopsony” costs); and 

(2) the risk of reductions in U.S. economic output and disruption to the U.S. economy caused by 

sudden disruptions in the supply of imported oil to the U.S. (i.e., macroeconomic 

disruption/adjustment costs). 

 

743 Leiby, Paul N., Donald W. Jones, T. Randall Curlee, and Russell Lee, Oil Imports: An Assessment of Benefits 

and Costs, ORNL-6851, Oak Ridge National Laboratory, November, 1997.
Page 673 of 850

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 value for the Social Cost 

of Carbon (SCC) the question arises: how should the energy security premium be used when 

some benefits from the rule, such as the benefits of reducing greenhouse gas emissions, are 

calculated from a global perspective? Monopsony benefits represent avoided payments by U.S. 

consumers to oil producers that result from a decrease in the world oil price as the U.S. decreases 

its demand for oil. Although there is clearly an overall benefit to the U.S. when considered from 

a domestic perspective, the decrease in price due to decreased demand in the U.S. also represents 

a loss to oil producing countries, one of which is the United States. Given the redistributive 

nature of this monopsony effect from a global perspective, and the fact that an increasing fraction 

of it represents a transfer between U.S. consumers and producers, it is excluded in the energy

security benefits calculations for these proposed rules. 

In contrast, the other portion of the energy security premium, the avoided U.S. 

macroeconomic disruption and adjustment cost that arises from reductions in U.S. petroleum 

imports, does not have offsetting impacts outside of the U.S., and, thus, is included in the energy

security benefits estimated for these proposed rules. To summarize, the agencies have included 

only the avoided macroeconomic disruption portion of the energy security benefits to estimate 

the monetary value of the total energy security benefits of these proposed rules. 

For this rulemaking, ORNL updated the energy security premiums by incorporating the 

most recent oil price forecast and energy market trends, particularly regional oil supplies and 

demands, from the AEO 2014 (Early Release) into its model.744 ORNL developed energy

security premium estimates for a number of different years. Table IX-24 provides estimates for 

energy security premiums for the years 2020, 2025, 2030 and 2040,

745 as well as a breakdown of 

the components of the energy security premiums for each year. The components of the energy

security premiums and their values are discussed below. 

 

744 Leiby, P., Factors Influencing Estimate of Energy Security Premium for Heavy-Duty Phase 2 Proposed Rule, 

11/1/2014, Oak Ridge National Laboratory.

745 AEO 2014 (Early Release) forecasts energy market trends and values only to 2040. The post-2040 energy 

security premium values are assumed to be equal to the 2040 estimate.
Page 674 of 850

Table IX-24 Energy Security Premiums in 2020, 2025, 2030 and 2040 (2012$/Barrel)*

Year 

(range)

Monopsony

(Range)

Avoided Macroeconomic 

Disruption/Adjustment Costs

(Range)

Total Mid-Point

(Range)

2020 $4.91

(1.63 – 9.15)

$6.35

(3.07 – 10.15)

$11.25

(6.67 – 16.53)

2025 $5.46

(1.81 – 10.47)

$7.29

(3.57 – 11.67)

$12.75

(7.58 – 18.65)

2030 $6.04

(2.00 – 11.67)

$8.39

(4.12 – 13.41)

$14.43

(8.54 – 21.13)

2040 $7.17

(2.32 – 14.03)

$10.74

(5.36 – 17.22)

$17.91

– 26.14)

Note:

* Top values in each cell are the midpoints, the values in parentheses are the 90 percent confidence intervals.

(a) Effect of Oil Use on the Long-Run Oil Price

The first component of the full economic costs of importing petroleum into the U.S. 

follows from the effect of U.S. import demand on the world oil price over the long-run. Because 

the U.S. is a sufficiently large purchaser of global oil supplies, its purchases can affect the world 

oil price. This monopsony power means that increases in U.S. petroleum demand can cause the 

world price of crude oil to rise, and conversely, that reduced U.S. petroleum demand can reduce 

the world price of crude oil. Thus, one benefit of decreasing U.S. oil purchases, due to 

improvements in the fuel efficiency of medium- and heavy-duty vehicles, is the potential

decrease in the crude oil price paid for all crude oil purchased.

A variety of oil market and economic factors have contributed to lowering the estimated 

monopsony premium compared to monopsony premiums cited in recent EPA/NHTSA 

rulemakings. Three principal factors contribute to lowering the monopsony premium: lower 

world oil prices, lower U.S. oil imports and less responsiveness of world oil prices to changes in 

U.S. oil demand. For example, between 2012 (using the AEO 2012 (Early Release)) and 2014 

(using the AEO 2014 (Early Release)), there has been a general downward revision in world oil 

price projections in the near term (e.g. 19 percent in 2020) and a sharp reduction in projected 

U.S. oil imports in the near term, due to increased U.S. supply (i.e., a 41 percent reduction in

U.S. oil imports by 2017 and a 36 percent reduction in 2020). Over the longer term, oil’s share 

of total U.S. imports is projected to gradually increase after 2020 but still remain 27 percent 

below the AEO2012 (Early Release) projected level in 2035.

Another factor influencing the monopsony premium is that U.S. demand on the global oil 

market is projected to decline, suggesting diminished overall influence and some reduction in the 

influence of U.S. oil demand on the world price of oil. Outside of the U.S., projected OPEC 

supply remains roughly steady as a share of world oil supply compared to the AEO2012 (Early 

Release). OPEC’s share of world oil supply outside of the U.S. actually increases slightly. Since 

OPEC supply is estimated to be more price sensitive than non-OPEC supply, this means that 

under AEO2014 (Early Release) world oil supply is slightly more responsive to changes in U.S. 
Page 675 of 850

oil demand. Together, these factors suggest that changes in U.S. oil import reductions have a 

somewhat smaller effect on the long-run world oil price than changes based on 2012 estimates. 

These changes in oil price and import levels lower the monopsony portion of energy

security premium since this portion of the security premium is related to the change in total U.S. 

oil import costs that is achieved by a marginal reduction in U.S oil imports. Since both the price 

and the quantity of oil imports are lower, the monopsony premium component is 46 – 57 percent

lower over the years 2017 – 2025 than the estimates based upon the AEO 2012 (Early Release) 

projections. 

There is disagreement in the literature about the magnitude of the monopsony

component, and its relevance for policy analysis. Brown and Huntington (2013),

746 for example, 

argue that the United States’ refusal to exercise its market power to reduce the world oil price 

does not represent a proper externality, and that the monopsony component should not be 

considered in calculations of the energy security externality. However, they also note in their 

earlier discussion paper (Brown and Huntington 2010)747 that this is a departure from the 

traditional energy security literature, which includes sustained wealth transfers associated with 

stable but higher-price oil markets. On the other hand, Greene (2010)748 and others in prior 

literature (e.g., Toman 1993)749 have emphasized that the monopsony cost component is policyrelevant because the world oil market is non-competitive and strongly influenced by cartelized 

and government-controlled supply decisions. Thus, while sometimes couched as an externality, 

Greene notes that the monopsony component is best viewed as stemming from a completely 

different market failure than an externality (Ledyard 2008),750 yet still implying marginal social 

costs to importers.

There is also a question about the ability of gradual, long-term reductions, such as those 

resulting from this proposed rule, to reduce the world oil price in the presence of OPEC’s 

monopoly power. OPEC is currently the world’s marginal petroleum supplier, and could 

conceivably respond to gradual reductions in U.S. demand with gradual reductions in supply

over the course of several years as the fuel savings resulting from this rule grow. However, if 

OPEC opts for a long-term strategy to preserve its market share, rather than maintain a particular 

price level (as they have done recently in response to increasing U.S. petroleum production), 

reduced demand would create downward pressure on the global price. The Oak Ridge analysis 

assumes that OPEC does respond to demand reductions over the long run, but there is still a price 

effect in the model. Under the mid-case behavioral assumption used in the premium 

 

746 Brown, Stephen P.A. and Hillard G. Huntington. 2013. Assessing the U.S. Oil Security Premium. 

Energy Economics, vol. 38, pp 118-127.

747 Reassessing the Oil Security Premium. RFF Discussion Paper Series, (RFF DP 10-05). doi: RFF DP 10-05

748 Greene, D. L. 2010. Measuring energy security: Can the United States achieve oil independence? Energy Policy, 

38(4), 1614–1621. doi:10.1016/j.enpol.2009.01.041

749 Reassessing the Oil Security Premium. RFF Discussion Paper Series, (RFF DP 10-05). doi:RFF DP 10-05

750 Ledyard, John O. "Market Failure." The New Palgrave Dictionary of Economics. Second Edition. Eds. Steven N. 

Durlauf and Lawrence E. Blume. Palgrave Macmillan, 2008
Page 676 of 850

calculations, OPEC responds by gradually reducing supply to maintain market share (consistent 

with the long-term self-interested strategy suggested by Gately (2004, 2007)).751 

It is important to note that the decrease in global petroleum prices resulting from this 

rulemaking could spur increased consumption of petroleum in other sectors and countries, 

leading to a modest uptick in GHG emissions outside of the United States. This increase in 

global fuel consumption could offset some portion of the GHG reduction benefits associated 

with these proposed rules. The agencies have not quantified this increase in global GHG 

emissions. We request comments, data sources and methodologies for how global rebound 

effects may be quantified.

(b) Macroeconomic Disruption Adjustment Costs 

The second component of the oil import premium, “avoided macroeconomic 

disruption/adjustment costs”, arises from the effect of oil imports on the expected cost of supply 

disruptions and accompanying price increases. A sudden increase in oil prices triggered by a 

disruption in world oil supplies has two main effects: (1) it increases the costs of oil imports in 

the short-run and (2) it can lead to macroeconomic contraction, dislocation and Gross Domestic 

Product (GDP) losses. For example, ORNL estimates the combined value of these two factors to 

be $6.34/barrel when U.S. oil imports are reduced in 2020, with a range from $3.07/barrel to 

$10.15/barrel of imported oil reduced.

Since future disruptions in foreign oil supplies are an uncertain prospect, each of the 

disruption cost components must be weighted by the probability that the supply of petroleum to 

the U.S. will actually be disrupted. Thus, the “expected value” of these costs – the product of the 

probability that a supply disruption will occur and the sum of costs from reduced economic 

output and the economy’s abrupt adjustment to sharply higher petroleum prices – is the relevant 

measure of their magnitude. Further, when assessing the energy security value of a policy to 

reduce oil use, it is only the change in the expected costs of disruption that results from the 

policy that is relevant. The expected costs of disruption may change from lowering the normal 

(i.e., pre-disruption) level of domestic petroleum use and imports, from any induced alteration in 

the likelihood or size of disruption, or from altering the short-run flexibility (e.g., elasticity) of 

petroleum use.

With updated oil market and economic factors, the avoided macroeconomic disruption 

component of the energy security premiums is slightly lower in comparison to avoided 

macroeconomic disruption premiums used in previous rulemakings. Factors that contribute to 

moderately lowering the avoided macroeconomic disruption component are lower projected 

GDP, moderately lower oil prices and slightly smaller price increases during prospective shocks. 

For example, oil price levels are 5 – 19 percent lower over the 2020 – 2035 period, and the likely 

increase in oil prices in the event of an oil shock are somewhat smaller, given small increases in

 

751 Gately, Dermot 2004. “OPEC's Incentives for Faster Output Growth”, The Energy Journal, 25 (2):75-96; Gately, 

Dermot 2007. "What Oil Export Levels Should We Expect From OPEC?", The Energy Journal, 28(2):151-173.
Page 677 of 850

the responsiveness of oil supply to changes in the world price of oil. Overall, the avoided 

macroeconomic disruption component estimates for the oil security premiums are 2 – 19 percent

lower over the period from 2020 – 2035 based upon different projected oil market and economic 

trends in the AEO2014 (Early Release) compared to the AEO2012 (Early Release). 

There are several reasons why the avoided macroeconomic disruption premiums change 

only moderately. One reason is that the macroeconomic sensitivity to oil price shocks is 

assumed unchanged in recent years since U.S. oil consumption levels and the value share of oil 

in the U.S. economy remain at high levels. For example, Figure IX-2 below shows that under 

AEO2014 (Early Release), projected U.S. real annual oil expenditures continue to rise after 2015 

to over $800 billion (2012$) by 2030. The value share of oil use in the U.S. economy remains 

between three and four percent, well above the levels observed from 1985 to 2005. A second 

factor is that oil disruption risks are little changed. The two factors influencing disruption risks 

are the probability of global supply interruptions and the world oil supply share from OPEC.

Both factors are not significantly different from previous forecasts of oil market trends.

The energy security costs estimated here follow the oil security premium framework, 

which is well established in the energy economics literature. The oil import premium gained 

attention as a guiding concept for energy policy around the time of the second and third major 

post-war oil shocks (Bohi and Montgomery 1982, EMF 1982) .

752

 Plummer (1982)

753 provided 

valuable discussion of many of the key issues related to the oil import premium as well as the 

analogous oil stockpiling premium. Bohi and Montgomery (1982)754 detailed the theoretical 

foundations of the oil import premium established many of the critical analytic relationships 

through their thoughtful analysis. Hogan (1981)

755 and Broadman and Hogan (1986, 1988)756

revised and extended the established analytical framework to estimate optimal oil import premia 

with a more detailed accounting of macroeconomic effects. 

Since the original work on energy security was undertaken in the 1980’s, there have been 

several reviews on this topic. For example, Leiby, Jones, Curlee and Lee (1997)757 provided an 

extended review of the literature and issues regarding the estimation of the premium. Parry and 

 

752 Bohi, Douglas R. And W. David Montgomery 1982. Social Cost of Imported and U.S. Import Policy, Annual 

Review of Energy, 7:37-60. Energy Modeling Forum, 1981. World Oil, EMF Report 6 (Stanford University Press: 

Stanford 39 CA. https//emf.stanford.edu/publications/emf-6-world-oil.

753 Plummer, James L. (Ed.) 1982. Energy Vulnerability, “Basic Concepts, Assumptions and Numerical Results”, 

pp. 13 - 36, (Cambridge MA: Ballinger Publishing Co.)

754 Bohi, Douglas R. And W. David Montgomery 1982. Social Cost of Imported and U.S. Import Policy, Annual 

Review of Energy, 7:37-60.

755 Hogan, William W., 1981. “Import Management and Oil Emergencies”, Chapter 9 in Deese, 5 David and Joseph 

Nye, eds. Energy and Security. Cambridge, MA: Ballinger Publishing Co.

756 Broadman, H. G. 1986. “The Social Cost of Imported Oil,” Energy Policy 14(3):242-252. Broadman H.G. and 

W.W. Hogan, 1988. “Is an Oil Import Tariff Justified? An American Debate: The Numbers Say ‘Yes’.” The Energy 

Journal 9: 7-29.

757 Leiby, Paul N., Donald W. Jones, T. Randall Curlee, and Russell Lee, Oil Imports: An Assessment of Benefits 

and Costs, ORNL-6851, Oak Ridge National Laboratory, November 1, 1997.
Page 678 of 850

Darmstadter (2004)758 also provided an overview of extant oil security premium estimates and 

estimated of some premium components. 

The recent economics literature on whether oil shocks are a threat to economic stability

that they once were is mixed. Some of the current literature asserts that the macroeconomic 

component of the energy security externality is small. For example, the National Research 

Council (2009) argued that the non-environmental externalities associated with dependence on 

foreign oil are small, and potentially trivial.759 Analyses by Nordhaus (2007) and Blanchard and 

Gali (2010) question the impact of more recent oil price shocks on the economy.

760

 They were 

motivated by attempts to explain why the economy actually expanded immediately after the last 

shocks, and why there was no evidence of higher energy prices being passed on through higher 

wage inflation. Using different methodologies, they conclude that the economy has largely 

gotten over its concern with dramatic swings in oil prices.

One reason, according to Nordhaus, is that monetary policy has become more 

accommodating to the price impacts of oil shocks. Another is that consumers have simply 

decided that such movements are temporary, and have noted that price impacts are not passed on 

as inflation in other parts of the economy. He also notes that real changes to productivity due to 

oil price increases are incredibly modest,

761 and that the general direction of the economy matters 

a great deal regarding how the economy responds to a shock. Estimates of the impact of a price 

shock on aggregate demand are insignificantly different from zero.

Blanchard and Gali (2010) contend that improvements in monetary policy (as noted 

above), more flexible labor markets, and lessening of energy intensity in the economy, combined 

with an absence of concurrent shocks, all contributed to lessen the impact of oil shocks after 

1980. They find “... the effects of oil price shocks have changed over time, with steadily smaller 

effects on prices and wages, as well as on output and employment.”762 In a comment at the 

chapter’s end, this work is summarized as follows: “The message of this chapter is thus 

optimistic in that it suggests a transformation in U.S. institutions has inoculated the economy

against the responses that we saw in the past.”

 

758 Parry, Ian W.H. and Joel Darmstadter 2004. “The Costs of U.S. Oil Dependency,” Resources for the Future, 

November 17, 2004 (also published as NCEP Technical Appendix Chapter 1: Enhancing Oil Security, the National 

Commission on Energy Policy 2004 Ending the Energy Stalemate - A Bipartisan Strategy to Meet America’s 

Energy Challenges.)

759 National Research Council, 2009. Hidden Costs of Energy: Unpriced Consequences of Energy Production and 

Use. National Academy of Science, Washington, DC.

760 See, William Nordhaus, “Who’s Afraid of a Big Bad Oil Shock?,” available at 

http://aida.econ.yale.edu/~nordhaus/homepage/Big_Bad_Oil_Shock_Meeting.pdf , and Olivier Blanchard and Jordi 

Gali, “The macroeconomic Effects of Oil price Shocks: Why are the 2000s so different from the 1970s?,” pp. 373-

421, in The International Dimensions of Monetary Policy, Jordi Gali and Mark Gertler, editors, University of 

Chicago Press, February 2010, available at http://www.nber.org/chapters/c0517.pdf

761 In fact, “... energy-price changes have no effect on multifactor productivity and very little effect on labor 

productivity.” Page 19. He calculates the productivity effect of a doubling of oil prices as a decrease of 0.11 percent 

for one year and 0.04 percent a year for ten years. Page 5. (The doubling reflects the historical experience of the 

post-war shocks, as described in Table 7.1 in Blanchard and Gali, p. 380.)

762 Blanchard and Gali, p. 414.
Page 679 of 850

At the same time, the implications of the “Shale Oil Revolution” are now being felt in the 

international markets, with current prices at four year lows. Analysts generally attribute this 

result in part to the significant increase in supply resulting from U.S. production, which has put 

liquid petroleum production on par with Saudi Arabia. The price decline is also attributed to the 

sustained reductions in U.S. consumption and global demand growth from fuel efficiency

policies and high oil prices. The resulting decrease in foreign imports, down to about one-third 

of domestic consumption (from 60 percent in 2005, for example763), effectively permits U.S.

supply to act as a buffer against artificial or other supply restrictions (the latter due to conflict or 

natural disaster, for example).

However, other papers suggest that oil shocks, particularly sudden supply shocks, remain 

a concern. Both Blanchard and Gali’s and Nordhaus work were based on data and analysis 

through 2006, ending with a period of strong global economic growth and growing global oil 

demand. The Nordhaus work particularly stressed the effects of the price increase from 2002-

2006 that were comparatively gradual (about half the growth rate of the 1973 event and one-third 

that of the 1990 event). The Nordhaus study emphasizes the robustness of the U.S. economy 

during a time period through 2006. This time period was just before rapid further increases in 

the price of oil and other commodities with oil prices more-than-doubling to over $130/barrel by

mid-2008, only to drop after the onset of the largest recession since the Great Depression. 

Hamilton (2012) reviewed the empirical literature on oil shocks and suggested that the 

results are mixed, noting that some work (e.g. Rasmussen and Roitman (2011) finds less 

evidence for economic effects of oil shocks, or declining effects of shocks (Blanchard and Gali 

2010), while other work continues to find evidence regarding the economic importance of oil 

shocks. For example, Baumeister and Peersman (2011) found that an oil price increase of a 

given size seems to have a decreasing effect over time, but noted that the declining priceelasticity of demand meant that a given physical disruption had a bigger effect on price and 

turned out to have a similar effect on output as in the earlier data.”764 Hamilton observes that “a

negative effect of oil prices on real output has also been reported for a number of other countries, 

particularly when nonlinear functional forms have been employed” (citing as recent examples 

Kim 2012, Engemann, Kliesen, and Owyang 2011 and Daniel, et. al. 2011). Alternatively, rather 

than a declining effect, Ramey and Vine (2010) found “remarkable stability in the response of 

aggregate real variables to oil shocks once we account for the extra costs imposed on the 

economy in the 1970s by price controls and a complex system of entitlements that led to some 

rationing and shortages.”765

Some of the recent literature on oil price shocks has emphasized that economic impacts 

 

763 See, Oil Price Drops on Oversupply, http://www.oil-price.net/en/articles/oil-price-drops-on-oversupply.php,

10/6/2014.

764 Hamilton, J. D. (2012). Oil Prices, Exhaustible Resources, and Economic Growth. In Handbook of Energy and 

Climate Change. Retrieved from http://econweb.ucsd.edu/~jhamilto/handbook_climate.pdf

765 Ramey, V. A., & Vine, D. J. (2010). “Oil, Automobiles, and the U.S. Economy: How Much have Things Really 

Changed?”, National Bureau of Economic Research Working Papers, WP 16067 (June). Retrieved from 

http://www.nber.org/papers/w16067.pdf
Page 680 of 850

depend on the nature of the oil shock, with differences between price increases caused by sudden 

supply loss and those caused by rapidly growing demand. Most recent analyses of oil price 

shocks have confirmed that “demand-driven” oil price shocks have greater effects on oil prices 

and tend to have positive effects on the economy while “supply-driven” oil shocks still have 

negative economic impacts (Baumeister, Peersman and Robays, 2010). A recent paper by Kilian 

and Vigfusson (2014), for example, assigned a more prominent role to the effects of price 

increases that are unusual, in the sense of being beyond range of recent experience. Kilian and 

Vigfussen also conclude that the difference in response to oil shocks may well stem from the 

different effects of demand- and supply-based price increases: “One explanation is that oil price 

shocks are associated with a range of oil demand and oil supply shocks, some of which stimulate 

the U.S. economy in the short run and some of which slow down U.S. growth (see Kilian 2009a). 

How recessionary the response to an oil price shock is thus depends on the average composition 

of oil demand and oil supply shocks over the sample period.” 

The general conclusion that oil supply-driven shocks reduce economic output is also 

reached in a recently published paper by Cashin et al. (2014) for 38 countries from 1979-2011. 

“The results indicate that the economic consequences of a supply-driven oil-price shock are very

different from those of an oil-demand shock driven by global economic activity, and vary for oilimporting countries compared to energy exporters,” and “oil importers [including the U.S.] 

typically face a long-lived fall in economic activity in response to a supply-driven surge in oil 

prices” but almost all countries see an increase in real output for an oil-demand disturbance. 

Note that the energy security premium calculation in this analysis is based on price shocks from 

potential future supply events only.

Finally, despite continuing uncertainty about oil market behavior and outcomes and the 

sensitivity of the U.S. economy to oil shocks, it is generally agreed that it is beneficial to reduce 

petroleum fuel consumption from an energy security standpoint. Reducing fuel consumption 

reduces the amount of domestic economic activity associated with a commodity whose price 

depends on volatile international markets. Also, reducing U.S. oil import levels reduces the 

likelihood and significance of supply disruptions. 
Page 681 of 850

Figure IX-2 Projected and Historical U.S. Expenditures, and Expenditure Share, on Crude Oil766

 

766 Historical data are from EIA Annual Energy Review, various editions. For data since 2011 and projected data: 

source is EIA Annual Energy Outlook (AEO) 2014 (Reference Case). See Table 11, file "aeotab_11.xlsx" and Table 

20 (Macroeconomic Indicators,” (file “aeotab_20.xlsx”).
Page 682 of 850

(c) Cost of Existing U.S. Energy Security Policies

The last often-identified component of the full economic costs of U.S. oil imports are the 

costs to the U.S. taxpayers of existing U.S. energy security policies. The two primary examples 

are maintaining the Strategic Petroleum Reserve (SPR) and maintaining a military presence to 

help secure a stable oil supply from potentially vulnerable regions of the world. The SPR is the 

largest stockpile of government-owned emergency crude oil in the world. Established in the 

aftermath of the 1973/1974 oil embargo, the SPR provides the U.S. with a response option 

should a disruption in commercial oil supplies threaten the U.S. economy. It also allows the U.S.

to meet part of its International Energy Agency obligation to maintain emergency oil stocks, and 

it provides a national defense fuel reserve. While the costs for building and maintaining the SPR

are more clearly related to U.S. oil use and imports, historically these costs have not varied in 

response to changes in U.S. oil import levels. Thus, while the effect of the SPR in moderating 

price shocks is factored into the ORNL analysis, the cost of maintaining the SPR is excluded.

U.S. military costs are excluded from the analysis performed by ORNL because their 

attribution to particular missions or activities is difficult, and because it is not clear that these 

outlays would decline in response to incremental reductions in U.S. oil imports. Most military

forces serve a broad range of security and foreign policy objectives. The agencies also recognize 

that attempts to attribute some share of U.S. military costs to oil imports are further challenged 

by the need to estimate how those costs might vary with incremental variations in U.S. oil 

imports.

(3) Energy Security Benefits of this Program 

Using the ORNL “oil premium” methodology, updating world oil price values and 

energy trends using AEO 2014 (Early Release) and using the estimated fuel savings from the 

proposed rules estimated from the MOVES/CAFE models, the agencies has calculated the 

annual energy security benefits of this proposed rule through 2050.767 Since the agencies are 

taking a global perspective with respect to valuing greenhouse gas benefits from the rules, only 

the avoided macroeconomic adjustment/disruption portion of the energy security premium is 

used in the energy security benefits estimates present below. These results are shown below in 

Table IX-25. The agencies have also calculated the net present value at 3 percent and 7 percent 

discount rates of model year lifetime benefits associated with energy security; these values are 

presented in Table IX-26.

 

767 In order to determine the energy security benefits beyond 2040, we use the 2040 energy security premium 

multiplied by the estimate fuel savings from the proposed rule. Since the AEO 2014 (Early Release) only goes to 

2040, we only calculate energy security premiums to 2040. 
Page 683 of 850

Table IX-25 Annual U.S. Energy Security Benefits of the Preferred Alternative and Net Present Values at 

3% and 7% Discount Rates using Method B and Relative to the Less Dynamic Baseline (In Millions of 2012$)

a

YEAR BENEFIT

S (2012$)

2018 $10

2019 $20

2020 $31

2021 $77

2022 $140

2023 $211

2024 $328

2025 $456

2026 $596

2027 $770

2028 $947

2029 $1,126

2030 $1,306

2035 $2,156

2040 $2,920

2050 $3,498

NPV, 3% $28,947

NPV, 7% $11,857

Note:

a For an explanation of analytical Methods A and B, please see Section I.D; for an explanation 

of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table IX-26 Discounted Model Year Lifetime Energy Security Benefits due to the Preferred Alternative at 

3% and 7% Discount Rates using Method B and Relative to the Less Dynamic Baseline (Millions of 2012$) a

Calendar

Year

3%

Discount Rate

7%

Discount Rate

2018 $86 $60

2019 $85 $56

2020 $84 $53

2021 $534 $326

2022 $579 $341

2023 $621 $353

2024 $996 $546

2025 $1,060 $560

2026 $1,121 $571

2027 $1,375 $676

2028 $1,388 $657

2029 $1,397 $637

Sum $9,325 $4,837

Note:

a For an explanation of analytical Methods A and B, please see Section I.D; for an explanation 

of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.
Page 684 of 850

J. Other Impacts

(1) Costs of Noise, Congestion and Accidents Associated with Additional (Rebound) 

Driving

Although it provides benefits to drivers as described above, increased vehicle use 

associated with the rebound effect also contributes to increased traffic congestion, motor vehicle 

accidents, and highway noise. Depending on how the additional travel is distributed over the day

and where it takes place, additional vehicle use can contribute to traffic congestion and delays by

increasing the number of vehicles using facilities that are already heavily traveled. These added 

delays impose higher costs on drivers and other vehicle occupants in the form of increased travel 

time and operating expenses. At the same time, this additional travel also increases costs 

associated with traffic accidents and vehicle noise. 

The agencies estimate these costs using the same methodology as used in the two lightduty and the HD Phase 1 rule analyses, which relies on estimates of congestion, accident, and 

noise costs imposed by automobiles and light trucks developed by the Federal Highway

Administration to estimate these increased external costs caused by added driving.768 We 

provide the details behind the estimates in Chapter 8.7 of the draft RIA. The agencies request 

comment on all input metrics used in the analysis of accidents, congestion and noise and on the 

calculation methodology. Table IX-27 presents the estimated annual impacts associated with 

accidents, congestion and noise along with net present values at both 3 percent and 7 percent 

discount rates. Table IX-28 presents the estimated discounted model year lifetime impacts 

associated with accidents, congestion and noise. 

 

768 These estimates were developed by FHWA for use in its 1997 Federal Highway Cost Allocation

Study; http://www.fhwa.dot.gov/policy/hcas/final/index.htm (last accessed July 8, 2012).
Page 685 of 850

Table IX-27 Annual Costs Associated with Accidents, Congestion and Noise and Net Present Values at 3% 

and 7% Discount Rates using Method B and Relative to the Less Dynamic Baseline (Millions of 2012$) a

Calendar

Year

Costs of

Accidents, 

Congestion,

And Noise

2018 $0

2019 $0

2020 $0

2021 $117

2022 $172

2023 $226

2024 $279

2025 $330

2026 $379

2027 $425

2028 $467

2029 $506

2030 $542

2035 $676

2040 $758

2050 $871

NPV, 3% $9,334

NPV, 7% $4,202

Note:

a For an explanation of analytical Methods A and B, please see Section I.D; for an explanation 

of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table IX-28 Discounted Model Year Lifetime Costs of Accidents, Congestion and Noise at 3% and 7% 

Discount Rates using Method B and Relative to the Less Dynamic Baseline (Millions of 2012$) a

Calendar

Year

3%

Discount Rate

7%

Discount Rate

2018 $132 $85

2019 $146 $94

2020 $162 $103

2021 $450 $284

2022 $438 $266

2023 $427 $250

2024 $424 $239

2025 $422 $229

2026 $420 $219

2027 $415 $209

2028 $409 $198

2029 $402 $187

Sum $4,247 $2,362

Note:

a For an explanation of analytical Methods A and B, please see Section I.D; for an explanation 

of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.
Page 686 of 850

(2) Benefits Associated with Reduced Refueling Time

By reducing the frequency with which drivers typically refuel their vehicles and by 

extending the upper limit of the range that can be traveled before requiring refueling (i.e., future 

fuel tank sizes remain constant), savings would be realized associated with less time spent 

refueling vehicles. Alternatively, refill intervals may remain the same (i.e., future fuel tank sizes 

get smaller), resulting in the same number of refills as today but less time spent per refill because 

there would be less fuel to refill. The agencies have estimated this impact using the former 

approach—by assuming that future tank sizes remain constant.

The savings in refueling time are calculated as the total amount of time the driver of a 

typical truck in each class would save each year as a consequence of pumping less fuel into the 

vehicle’s tank. The calculation does not include any reduction in time spent searching for a 

fueling station or other time spent at the station; it is assumed that time savings occur only when 

truck operators are actually refueling their vehicles. 

The calculation uses the reduced number of gallons consumed by truck type and divides 

that value by the tank volume and refill amount to get the number of refills, then multiplies that 

by the time per refill to determine the number of hours saved in a given year. The calculation 

then applies DOT-recommended values of travel time savings to convert the resulting time 

savings to their economic value, including a 1.2 percent growth rate in those time savings going 

forward.769 The input metrics used in the analysis are presented in greater detail in draft RIA 

Chapter 9.7. The annual benefits associated with reduced refueling time are shown in Table 

IX-29 along with net present values at both 3 percent and 7 percent discount rates. The 

discounted model year lifetime benefits are shown in Table IX-30

 

769 U.S. Department of Transportation, Valuation of Travel Guidance, July 9, 2014, at page 14.
Page 687 of 850

Table IX-29 Annual Refueling Benefits and Net Present Values at 3% and 7% Discount Rates using Method 

B and Relative to the Less Dynamic Baseline (Millions of 2012$) a

Calendar

Year

Refueling

Benefits

2018 $3

2019 $6

2020 $9

2021 $25

2022 $47

2023 $72

2024 $113

2025 $157

2026 $205

2027 $266

2028 $327

2029 $386

2030 $444

2035 $698

2040 $890

2050 $1,195

NPV, 3% $9,410

NPV, 7% $3,868

Note:

a For an explanation of analytical Methods A and B, please see Section I.D; for an explanation 

of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table IX-30 Discounted Model Year Lifetime Refueling Benefits using Method B and relative to the Less 

Dynamic Baseline (Millions of 2012$) a

Model

Year

3%

Discount Rate

7%

Discount Rate

2018 $23 $16

2019 $22 $15

2020 $21 $14

2021 $163 $101

2022 $184 $110

2023 $203 $117

2024 $325 $181

2025 $349 $187

2026 $372 $191

2027 $466 $231

2028 $465 $222

2029 $463 $213

Sum $3,055 $1,597

Note:

a For an explanation of analytical Methods A and B, please see Section I.D; for an explanation 

of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.
Page 688 of 850

(3) Benefits of Increased Travel Associated with Rebound Driving

The increase in travel associated with the rebound effect produces additional benefits to 

vehicle owners and operators, which reflect the value of the added (or more desirable) social and 

economic opportunities that become accessible with additional travel. The analysis estimates the 

economic benefits from increased rebound-effect driving as the sum of fuel expenditures 

incurred plus the consumer surplus from the additional accessibility it provides. As evidenced 

by the fact that vehicles make more frequent or longer trips when the cost of driving declines, the 

benefits from this added travel exceed added expenditures for the fuel consumed. The amount 

by which the benefits from this increased driving exceed its increased fuel costs measures the net 

benefits from the additional travel, usually referred to as increased consumer surplus. 

The agencies’ analysis estimates the economic value of the increased consumer surplus 

provided by added driving using the conventional approximation, which is one half of the 

product of the decline in vehicle operating costs per vehicle-mile and the resulting increase in the 

annual number of miles driven. Because it depends on the extent of improvement in fuel 

economy, the value of benefits from increased vehicle use changes by model year and varies 

among alternative standards. Under even those alternatives that would impose the highest 

standards, however, the magnitude of the consumer surplus from additional vehicle use 

represents a small fraction of this benefit.

The annual benefits associated with increased travel are shown in Table IX-31 along with 

net present values at both 3 percent and 7 percent discount rates. The discounted model year 

lifetime benefits are shown in Table IX-32.

Table IX-31 Annual Value of Increased Travel and Net Present Values at 3% and 7% Discount Rates using 

Method B and Relative to the Less Dynamic Baseline(Millions of 2012$ a)

Calendar

Year

Benefits of 

Increased Travel

2018 $0

2019 $0

2020 $0

2021 $445

2022 $636

2023 $821

2024 $1,001

2025 $1,179

2026 $1,346

2027 $1,506

2028 $1,647

2029 $1,783

2030 $1,909

2035 $2,445

2040 $2,873

2050 $3,286

NPV, 3% $34,240

NPV, 7% $15,316

Note:
Page 689 of 850

a For an explanation of analytical Methods A and B, please see Section I.D; for an explanation 

of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

Table IX-32 Discounted Model Year Lifetime Value of Increased Travel at 3% and 7% Discount Rates using 

Method B and Relative to the Less Dynamic Baseline (Millions of 2012$) a

Calendar

Year

3%

Discount Rate

7%

Discount Rate

2018 $554 $353

2019 $618 $390

2020 $686 $429

2021 $1,510 $942

2022 $1,488 $894

2023 $1,463 $847

2024 $1,434 $799

2025 $1,442 $774

2026 $1,447 $748

2027 $1,421 $708

2028 $1,415 $678

2029 $1,406 $649

Sum $14,884 $8,211

Note:

a For an explanation of analytical Methods A and B, please see Section I.D; for an explanation 

of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

K. Summary of Benefits and Costs

This section presents the costs, benefits, and other economic impacts of the proposed 

Phase 2 standards. It is important to note that NHTSA’s proposed fuel consumption standards 

and EPA’s proposed GHG standards would both be in effect, and would jointly lead to increased 

fuel efficiency and reductions in GHG and non-GHG emissions. The individual categories of 

benefits and costs presented in the tables below are defined more fully and presented in more 

detail in Chapter 8 of the draft RIA. These include: 

• the vehicle program costs (costs of complying with the vehicle CO2 and fuel 

consumption standards),

• changes in fuel expenditures associated with reduced fuel use by more efficient vehicles 

and increased fuel ue associated with the “rebound” effect, both of which result from the 

program,

• the global economic value of reductions in GHGs,

• the economic value of reductions in non-GHG pollutants,

• costs associated with increases in noise, congestion, and accidents resulting from 

increased vehicle use, 

• savings in drivers’ time from less frequent refueling,

• benefits of increased vehicle use associated with the “rebound” effect, and 

• the economic value of improvements in U.S. energy security impacts.
Page 690 of 850

For a discussion of the cost of ownership and the agencies’ payback analysis of vehicles covered 

by this proposal, please see Section IX.M.

The agencies conducted coordinated and complementary analyses using two analytical 

methods referred to as Method A and Method B. For an explanation of these methods, please 

see Section I.D. And as discussed in Section X.A.1, the agencies present estimates of benefits 

and costs that are measured against two different assumptions about improvements in fuel 

efficiency that might occur in the absence of the Phase 2 standards. The first case (Alternative 

1a) uses a baseline that projects very little improvement in new vehicles in the absence of new 

Phase 2 standards, and the second (Alternative 1b) uses a more dynamic baseline that projects 

more significant improvements in vehicle fuel efficiency.

Table IX-33 shows benefits and costs for the proposed standards from the perspective of 

a program designed to improve the nation’s energy security and conserve energy by improving 

fuel efficiency. From this viewpoint, technology costs occur when the vehicle is purchased. 

Fuel savings are counted as benefits that occur over the lifetimes of the vehicles produced during 

the model years subject to the Phase 2 standards as they consume less fuel. The table shows that 

benefits far outweigh the costs, and the preferred alternative is anticipated to result in large net 

benefits to the U.S economy.
Page 691 of 850

Table IX-33 Lifetime Benefits & Costs of the Preferred Alternative for Model Years 2018 - 2029 Vehicles 

Using Analysis Method A (Billions of 2012$ discounted at 3% and 7%)

Category Baseline 1a Baseline 1b

3% 7% 3% 7%

Vehicle Program: Technology and 

Indirect Costs, Normal Profit on 

Additional Investments

25.4 17.1 25.0 16.8

Additional Routine Maintenance 1.1 0.6 1.0 0.6

Congestion, Accidents, and Noise 

from Increased Vehicle Use

4.7 2.8 4.5 2.6

Total Costs 31.1 20.5 30.5 20.0

Fuel Savings (valued at pre-tax prices) 175.1 94.2 165.1 89.2

Savings from Less Frequent Refueling 3.1 1.6 2.9 1.5

Economic Benefits from Additional 

Vehicle Use

15.1 8.4 14.7 8.2

Reduced Climate Damages from GHG 

Emissions a

27.4 27.4 25.7 25.7

Reduced Health Damages from NonGHG Emissions

12.7 6.6 12.4 6.6

Increased U.S. Energy Security 8.9 4.7 8.1 4.3

Total Benefits 242.2 143.0 229.0 135.6

Net Benefits 211.1 122.5 198.5 115.6

a Benefits and net benefits use the 3 percent average global SCC value applied only to CO2 emissions; 

GHG reductions include CO2, CH4, N2O and HFC reductions, and include benefits to other nations as well as the 

U.S. See Draft RIA Chapter 8.5 and Preamble Section IX.G for further discussion.

Table IX-34, Table IX-35, and Table IX-36 report benefits and cost from the perspective 

of reducing GHG. Table IX-34 shows the annual impacts and net benefits of the preferred 

alternative for selected future years, together with the net present values of cumulative annual 

impacts from 2018 through 2050, discounted at 3 percent and 7 percent rates. Table IX-35 and 

Table IX-36 show the discounted lifetime costs and benefits for each model year affected by the 

Phase 2 standards at 3 percent and 7 percent discount rates, respectively.
Page 692 of 850

Table IX-34 Annual Benefits & Costs of the Preferred Alternative and Net Present Values at 3% and 7% 

Discount Rates using Method B and Relative to the Less Dynamic Baseline (Billions of 2012$) a, b

2018 2021 2024 2030 2035 2040 2050 NPV, 

3%

NPV, 

7%

Vehicle program -$0.1 -$2.4 -$3.7 -$5.4 -$5.9 -$6.3 -$7.0 -$86.8 -$41.1

Maintenance $0.0 $0.0 -$0.1 -$0.1 -$0.1 -$0.1 -$0.1 -$1.8 -$0.9

Pre-tax fuel $0.2 $1.7 $6.9 $24.0 $37.2 $47.8 $57.5 $495.6 $206.7

Energy security $0.0 $0.1 $0.3 $1.3 $2.2 $2.9 $3.5 $28.9 $11.9

Accidents/Congestion/Noise $0.0 -$0.1 -$0.3 -$0.5 -$0.7 -$0.8 -$0.9 -$9.3 -$4.2

Refueling impacts $0.0 $0.0 $0.1 $0.4 $0.7 $0.9 $1.2 $9.4 $3.9

Travel value $0.0 $0.4 $1.0 $1.9 $2.4 $2.9 $3.3 $34.2 $15.3

Non-GHG impacts $0.0 

to 

$0.1

$0.4 

to 

$0.9

$1.0 

to

$2.4

$3.3 

to 

$8.3

$4.8 

to 

$12.1

$5.7 

to 

$14.3

$7.0 to 

$17.5

$69.7 

to 

$157.0

$26.6 

to 

$60.4

SCCb,c

SCC_CO2; 5% Avg $0.0 $0.1 $0.4 $1.5 $2.5 $3.3 $5.0 $22.1 $22.1

SCC_CO2; 3% Avg $0.0 $0.3 $1.3 $4.8 $7.4 $9.7 $13.6 $103.1 $103.1

SCC_CO2; 2.5% Avg $0.1 $0.5 $1.9 $6.9 $10.6 $13.7 $18.5 $164.1 $164.1

SCC_CO2; 3% 95th $0.1 $1.0 $4.0 $14.6 $23.2 $30.3 $42.0 $320.5 $320.5

Net benefits d

SCC_CO2; 5% Avg $0.2 $0.4 $6.4 $28.8 $46.8 $60.6 $74.6 $605.8 $257.1

SCC_CO2; 3% Avg $0.2 $0.7 $7.3 $32.1 $51.7 $66.9 $83.2 $686.8 $338.1

SCC_CO2; 2.5% Avg $0.2 $0.8 $7.9 $34.2 $54.9 $70.9 $88.2 $747.8 $399.1

SCC_CO2; 3% 95th $0.3 $1.3 $10.0 $41.9 $67.5 $87.6 $111.7 $904.1 $555.5

Notes: 

a Positive values denote decreased social costs (benefits); negative values denote increased social costs. For an 

explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic baseline, 

1a, and more dynamic baseline, 1b, please see Section X.A.1.

c 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 (SC-CO2at 5, 3, 2.5 percent) is used to calculate net 

present value of SC-CO2for internal consistency. Refer to the SCC TSD for more detail. 

d Section IX.G notes that SCCO2 increases over time. For the years 2012-2050, the SC-CO2 estimates range as 

follows: for Average SC-CO2 at 5%: $12-$28; for Average SC-CO2 at 3%: $37-$77; for Average SC-CO2 at 2.5%: 

$58-$105; and for 95th percentile SC-CO2 at 3%: $105-$237. Section IX.G also presents these SC-CO2 estimates.

e Net impacts are the summation of results within columns of the table with the exception that the net impacts at 

each SC-CO2 value include only the SC-CO2 impacts at that value.
Page 693 of 850

Table IX-35 Discounted Model Year Lifetime Benefits & Costs of the Preferred Alternative using Method B 

and Relative to the Less Dynamic Baseline (Billions of 2012$ discounted at 3%) a ,b

2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 Sum

Vehicle

program

-

$0.1

-

$0.1

-

$0.1

-$2.0 -$1.9 -$1.9 -$2.8 -$2.7 -$2.7 -$3.7 -$3.6 -$3.5 -$25.1

Maintenance -

$0.1

$0.0 $0.0 -$0.1 -$0.1 -$0.1 -$0.1 -$0.1 -$0.1 -$0.1 -$0.1 -$0.1 -$1.1

Pre-tax fuel $1.9 $1.9 $1.8 $11.1 $11.5 $11.9 $18.9 $19.6 $20.2 $24.1 $24.1 $24.1 $171.1

Energy 

security

$0.1 $0.1 $0.1 $0.5 $0.6 $0.6 $1.0 $1.1 $1.1 $1.4 $1.4 $1.4 $9.3

Accidents/

Congestion/

Noise

-

$0.1

-

$0.1

-

$0.2

-$0.4 -$0.4 -$0.4 -$0.4 -$0.4 -$0.4 -$0.4 -$0.4 -$0.4 -$4.2

Refueling $0.0 $0.0 $0.0 $0.2 $0.2 $0.2 $0.3 $0.3 $0.4 $0.5 $0.5 $0.5 $3.1

Travel value $0.6 $0.6 $0.7 $1.5 $1.5 $1.5 $1.4 $1.4 $1.4 $1.4 $1.4 $1.4 $14.9

Non-GHG $0.2 

to 

$0.5

$0.2 

to 

$0.4

$0.2 

to 

$0.4

$2.0 

to 

$4.5

$2.0 

to 

$4.5

$2.0 

to 

$4.5

$2.9 

to 

$6.6

$3.0 

to 

$6.8

$2.6 

to 

$5.9

$3.1 

to 

$6.9

$3.1 

to 

$6.9

$3.1 

to 

$7.0

$24.4 

to 

$55.0

SCC b,c

SCC_CO2;

5% Avg

$0.1 $0.1 $0.1 $0.5 $0.5 $0.5 $0.9 $0.9 $0.9 $1.1 $1.1 $1.1 $7.8

SCC_CO2;

3% Avg

$0.4 $0.4 $0.4 $2.2 $2.3 $2.3 $3.7 $3.9 $4.0 $4.8 $4.8 $4.9 $34.0

SCC_CO2;

2.5% Avg

$0.6 $0.6 $0.6 $3.4 $3.5 $3.6 $5.8 $6.1 $6.3 $7.6 $7.6 $7.7 $53.4

SCC_CO2;

3% 95th

$1.1 $1.1 $1.1 $6.6 $6.9 $7.2 $11.5 $12.0 $12.4 $14.9 $15.0 $15.1 $105.0

Net benefits

d

SCC_CO2;

5% Avg

$2.8 $2.7 $2.7 $14.6 $15.1 $15.5 $23.9 $25.0 $25.1 $29.2 $29.4 $29.4 $215.5

SCC_CO2;

3% Avg

$3.0 $3.0 $3.0 $16.2 $16.8 $17.3 $26.8 $28.0 $28.2 $33.0 $33.1 $33.2 $241.7

SCC_CO2; 

2.5% Avg

$3.2 $3.2 $3.2 $17.4 $18.1 $18.6 $28.9 $30.2 $30.5 $35.7 $35.9 $36.0 $261.1

SCC_CO2;

3% 95th

$3.8 $3.8 $3.7 $20.7 $21.5 $22.1 $34.5 $36.0 $36.6 $43.1 $43.3 $43.5 $312.7

Notes: 

a Positive values denote decreased social costs (benefits); negative values denote increased social costs. For an 

explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic baseline, 

1a, and more dynamic baseline, 1b, please see Section X.A.1.c 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 (SC-CO2 at 5, 3, 2.5 percent) is used to calculate net present value of SC-CO2 for internal consistency. 

Refer to the SCC TSD for more detail. 

d

Section IX.G notes that SCC increases over time. For the years 2012-2050, the SCC estimates range as follows: 

for Average SC-CO2 at 5%: $12-$28; for Average SC-CO2 at 3%: $37-$77; for Average SC-CO2 at 2.5%: $58-

$105; and for 95th percentile SC-CO2 at 3%: $105-$237. Section IX.G also presents these SCC estimates.

e Net impacts are the summation of results within columns of the table with the exception that the net impacts at 

each SC-CO2 value include only the SCCO2 impacts at that value.
Page 694 of 850

Table IX-36 Discounted Model Year Lifetime Benefits & Costs of the Preferred Alternative using Method B 

and Relative to the Less Dynamic Baseline (Billions of 2012$ discounted at 7%) a ,b

2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 Sum

Vehicle

program

-

$0.1

-

$0.1

-

$0.1

-$1.6 -$1.4 -$1.4 -$1.9 -$1.8 -$1.7 -$2.3 -$2.1 -$2.0 -$16.6

Maintenance $0.0 $0.0 $0.0 -$0.1 -$0.1 -$0.1 -$0.1 -$0.1 -$0.1 -$0.1 -$0.1 $0.0 -$0.6

Pre-tax fuel $1.4 $1.3 $1.2 $6.9 $6.9 $6.8 $10.5 $10.4 $10.4 $11.9 $11.5 $11.0 $90.1

Energy 

security

$0.1 $0.1 $0.1 $0.3 $0.3 $0.4 $0.5 $0.6 $0.6 $0.7 $0.7 $0.6 $4.8

Accidents/

Congestion/

Noise

-

$0.1

-

$0.1

-

$0.1

-$0.3 -$0.3 -$0.2 -$0.2 -$0.2 -$0.2 -$0.2 -$0.2 -$0.2 -$2.4

Refueling $0.0 $0.0 $0.0 $0.1 $0.1 $0.1 $0.2 $0.2 $0.2 $0.2 $0.2 $0.2 $1.6

Travel value $0.4 $0.4 $0.4 $0.9 $0.9 $0.8 $0.8 $0.8 $0.7 $0.7 $0.7 $0.6 $8.2

Non-GHG $0.1 

to 

$0.3

$0.1 

to 

$0.3

$0.1 

to 

$0.3

$1.1 

to 

$2.5

$1.1 

to 

$2.4

$1.0 

to 

$2.3

$1.4 

to 

$3.3

$1.4 

to 

$3.2

$1.2 

to 

$2.7

$1.3 

to 

$3.0

$1.3 

to 

$2.9

$1.3 

to 

$2.8

$11.5 

to 

$26.0

SCC b,c

SCC_CO2;

5% Avg

$0.1 $0.1 $0.1 $0.5 $0.5 $0.5 $0.9 $0.9 $0.9 $1.1 $1.1 $1.1 $7.8

SCC_CO2;

3% Avg

$0.4 $0.4 $0.4 $2.2 $2.3 $2.3 $3.7 $3.9 $4.0 $4.8 $4.8 $4.9 $34.0

SCC_CO2;

2.5% Avg

$0.6 $0.6 $0.6 $3.4 $3.5 $3.6 $5.8 $6.1 $6.3 $7.6 $7.6 $7.7 $53.4

SCC_CO2;

3% 95th

$1.1 $1.1 $1.1 $6.6 $6.9 $7.2 $11.5 $12.0 $12.4 $14.9 $15.0 $15.1 $105.0

Net benefits

d

SCC_CO2;

5% Avg

$1.9 $1.8 $1.7 $8.7 $8.7 $8.7 $13.0 $13.1 $12.7 $14.3 $13.8 $13.4 $111.8

SCC_CO2;

3% Avg

$2.2 $2.1 $2.0 $10.3 $10.4 $10.5 $15.8 $16.1 $15.8 $18.0 $17.6 $17.2 $138.0

SCC_CO2; 

2.5% Avg

$2.4 $2.3 $2.2 $11.5 $11.7 $11.8 $17.9 $18.3 $18.1 $20.7 $20.4 $20.0 $157.4

SCC_CO2;

3% 95th

$2.9 $2.8 $2.8 $14.8 $15.1 $15.3 $23.6 $24.2 $24.2 $28.1 $27.8 $27.4 $209.0

Notes:

a Positive values denote decreased social costs (benefits); negative values denote increased social costs. For an 

explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic baseline, 

1a, and more dynamic baseline, 1b, please see Section X.A.1. 

b 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 (SC-CO2 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. 

c Section IX.G notes that SC-CO2 increases over time. For the years 2012-2050, the SC-CO2 estimates range as 

follows: for Average SC-CO2 at 5%: $12-$28; for Average SC-CO2 at 3%: $37-$77; for Average SC-CO2 at 2.5%: 

$58-$105; and for 95th percentile SCCO2 at 3%: $105-$237. Section IX.G also presents these SC-CO2 estimates.

d Net impacts are the summation of results within columns of the table with the exception that the net impacts at 

each SC-CO2 value include only the SC-CO2 impacts at that value.
Page 695 of 850

L. Employment Impacts

Executive Order 13563 (January 18, 2011) directs federal agencies to consider regulatory 

impacts on, among other criteria, job creation. 770 According to the Executive Order “Our 

regulatory system must protect public health, welfare, safety, and our environment while 

promoting economic growth, innovation, competitiveness, and job creation. It must be based on 

the best available science.” Analysis of employment impacts of a regulation is not part of a 

standard benefit-cost analysis (except to the extent that labor costs contribute to costs).

Employment impacts of federal rules are of general interest, however, and have been particularly

so, historically, in the auto sector during periods of challenging labor market conditions. For this 

reason, we are describing the connections of these proposed standards to employment in the 

regulated sector, the motor vehicle manufacturing sector, as well as the motor vehicle body and 

trailer and motor vehicle parts manufacturing sectors.

The overall effect of the proposed rules on motor vehicle sector employment depends on 

the relative magnitude of output and substitution effects, described below. Because we do not 

have quantitative estimates of the output effect, and only a partial estimate of the substitution 

effect, we cannot reach a quantitative estimate of the overall employment effects of the proposed 

rules on motor vehicle sector employment or even whether the total effect will be positive or 

negative. 

According to the U.S. Bureau of Labor Statistics, in 2014, about 850,000 people in the 

U.S. were employed in the Motor Vehicle and Parts Manufacturing Sector (NAICS 3361, 3362, 

and 3363),

771 the directly regulated sector. The employment effects of these proposed rules are 

expected to expand beyond the regulated sector. Though some of the parts used to achieve the 

proposed standards are likely to be built by motor vehicle manufacturers (including trailer 

manufacturers) themselves, the motor vehicle parts manufacturing sector also plays a significant 

role in providing those parts, and will also be affected by changes in vehicle sales. Changes in 

truck sales, discussed in Section IX. F. (2) , could also affect employment for truck and trailer 

vendors. As discussed in Section IX. C. , this proposed rule is expected to reduce the amount of 

fuel these vehicles use, and thus affect the petroleum refinery and supply industries as well. 

Finally, since the net reduction in cost associated with these proposed 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). The proposed rules are not expected to have any notable inflationary

or recessionary effect. 

The employment effects of environmental regulation are difficult to disentangle from 

other economic changes and business decisions that affect employment, over time and across 

regions and industries. In light of these difficulties, we lean on economic theory to provide a 

 

770 Available at http://www.whitehouse.gov/sites/default/files/omb/inforeg/eo12866/eo13563_01182011.pdf

771 U.S. Department of Labor, Bureau of Labor Statistics. “Automotive Industry; Employment, Earnings, and 

Hours.” http://www.bls.gov/iag/tgs/iagauto.htm , accessed 8/18/14.
Page 696 of 850

constructive framework for approaching these assessments and for better understanding the 

inherent complexities in such assessments. Neoclassical microeconomic theory describes how 

profit-maximizing firms adjust their use of productive inputs in response to changes in their 

economic conditions.772 Berman and Bui (2001, pp. 274-75) model two components that drive 

changes in firm-level labor demand: output effects and substitution effects.773 Regulation can affect 

the profit-maximizing quantity of output by changing the marginal cost of production. If regulation 

causes marginal cost to increase, it will place upward pressure on output prices, leading to a decrease 

in the quantity demanded, and resulting in a decrease in production. The output effect describes how, 

holding labor intensity constant, a decrease in production causes a decrease in labor demand. As 

noted by Berman and Bui, although many assume that regulation increases marginal cost, it need not 

be the case. A regulation could induce a firm to upgrade to less polluting and more efficient 

equipment that lowers marginal production costs, or it may induce use of technologies that may

prove popular with buyers or provide positive network externalities (see Section IX. A. for 

discussion of this effect). In such a case, output could increase.

The substitution effect describes how, holding output constant, regulation affects labor

intensity of production. Although increased environmental regulation may increase use of 

pollution control equipment and energy to operate that equipment, the impact on labor demand is 

ambiguous. For example, equipment inspection requirements, specialized waste handling, or 

pollution technologies that alter the production process may affect the number of workers 

necessary to produce a unit of output. Berman and Bui (2001) model the substitution effect as 

the effect of regulation on pollution control equipment and expenditures required by the 

regulation and the corresponding change in labor intensity of production. 

In summary, as output and substitution effects may be positive or negative, theory alone 

cannot predict the direction of the net effect of regulation on labor demand at the level of the 

regulated firm. Operating within the bounds of standard economic theory, empirical estimation 

of net employment effects on regulated firms is possible when data and methods of sufficient 

detail and quality are available. The literature, however, illustrates difficulties with empirical 

estimation. For example, studies sometimes rely on confidential plant-level employment data 

from the U.S. Census Bureau, possibly combined with pollution abatement expenditure data that 

are too dated to be reliably informative. In addition, the most commonly used empirical methods 

do not permit estimation of net effects.

 

772 See Layard, P.R.G., and A. A. Walters (1978), Microeconomic Theory (McGraw-Hill, Inc.), Chapter 9 (Docket 

ID EPA-HQ-OAR-2014-0827), a standard microeconomic theory textbook treatment, for a discussion. 

773 Berman, E. and L. T. M. Bui (2001). “Environmental Regulation and Labor Demand: Evidence from the South 

Coast Air Basin.” Journal of Public Economics 79(2): 265-295 (Docket EPA-HQ-OAR-2014-0827). The authors 

also discuss a third component, the impact of regulation on factor prices, but conclude that this effect is unlikely to 

be important for large competitive factor markets, such as labor and capital. Morgenstern, Pizer and Shih 

(Morgenstern, Richard D., William A. Pizer, and Jhih-Shyang Shih (2002). “Jobs versus the Environment: An 

Industry-Level Perspective.” Journal of Environmental Economics and Management 43: 412-436) use a similar 

model, but they break the employment effect into three parts: 1) a demand effect; 2) a cost effect; and 3) a factorshift effect. 
Page 697 of 850

The conceptual framework described thus far focused on regulatory effects on plant-level 

decisions within a regulated industry. Employment impacts at an individual plant do not 

necessarily represent impacts for the sector as a whole. The approach must be modified when 

applied at the industry level. 

At the industry level, labor demand is more responsive if: (1) the price elasticity of 

demand for the product is high, (2) other factors of production can be easily substituted for labor, 

(3) the supply of other factors is highly elastic, or (4) labor costs are a large share of total 

production costs.774 For example, if all firms in an industry are faced with the same regulatory

compliance costs and product demand is inelastic, then industry output may not change much, 

and output of individual firms may change slightly.775 In this case, the output effect may be 

small, while the substitution effect depends on input substitutability. Suppose, for example, that 

new equipment for fuel efficiency improvements requires labor to install and operate. In this 

case, the substitution effect may be positive, and with a small output effect, the total effect may

be positive. As with potential effects for an individual firm, theory cannot determine the sign or 

magnitude of industry-level regulatory effects on labor demand. Determining these signs and 

magnitudes requires additional sector-specific empirical study. For environmental rules, much 

of the data needed for these empirical studies is not publicly available, would require significant 

time and resources in order to access confidential U.S. Census data for research, and also would 

not be necessary for other components of a typical RIA. 

In addition to changes to labor demand in the regulated industry, net employment impacts 

encompass changes in other related sectors. For example, the proposed standards are expected to 

increase demand for fuel-saving technologies. This increased demand may increase revenue and 

employment in the firms providing these technologies. At the same time, the regulated industry

is purchasing the equipment, and these costs may impact labor demand at regulated firms. 

Therefore, it is important to consider the net effect of compliance actions on employment across 

multiple sectors or industries. 

If the U.S. economy is at full employment, even a large-scale environmental regulation is 

unlikely to have a noticeable impact on aggregate net employment.776 Instead, labor would 

primarily be reallocated from one productive use to another, and net national employment effects 

from environmental regulation would be small and transitory (e.g., as workers move from one 

job to another).777

 

774 See Ehrenberg, Ronald G., and Robert S. Smith (2000), Modern Labor Economics: Theory and Public Policy 

(Addison Wesley Longman, Inc.), p. 108. 

775 This discussion draws from Berman, E. and L. T. M. Bui (2001). “Environmental Regulation and Labor Demand: 

Evidence from the South Coast Air Basin.” Journal of Public Economics 79(2): 265-295 (Docket EPA-HQ-OAR2014-0827), p. 293. 

776 Full employment is a conceptual target for the economy where everyone who wants to work and is available to 

do so at prevailing wages is actively employed. The unemployment rate at full employment is not zero. 

777 Arrow et al. (1996). “Benefit-Cost Analysis in Environmental, Health, and Safety Regulation: A Statement of 

Principles.” American Enterprise Institute, the Annapolis Center, and Resources for the Future. See discussion on 
Page 698 of 850

Affected sectors may experience transitory effects as workers change jobs. Some workers 

may retrain or relocate in anticipation of new requirements or require time to search for new 

jobs, while shortages in some sectors or regions could bid up wages to attract workers. These 

adjustment costs can lead to local labor disruptions. Although the net change in the national 

workforce is expected to be small, localized reductions in employment may adversely impact 

individuals and communities just as localized increases may have positive impacts. 

If the economy is operating at less than full employment, economic theory does not 

clearly indicate the direction or magnitude of the net impact of environmental regulation on 

employment; it could cause either a short-run net increase or short-run net decrease.778 An 

important research question is how to accommodate unemployment as a structural feature in 

economic models. This feature may be important in assessing large-scale regulatory impacts on 

employment.779

Environmental regulation may also affect labor supply. In particular, pollution and other 

environmental risks may impact labor productivity or employees’ ability to work.780 While the 

theoretical framework for analyzing labor supply effects is analogous to that for labor demand, it 

is more difficult to study empirically. There is a small emerging literature described in the next 

section that uses detailed labor and environmental data to assess these impacts. 

To summarize, economic theory provides a framework for analyzing the impacts of 

environmental regulation on employment. The net employment effect incorporates expected 

employment changes (both positive and negative) in the regulated sector and elsewhere. Labor 

demand impacts for regulated firms, and also for the regulated industry, can be decomposed into 

output and substitution effects which may be either negative or positive. Estimation of net 

employment effects for regulated sectors is possible when data of sufficient detail and quality are 

available. Finally, economic theory suggests that labor supply effects are also possible. In the 

next section, we discuss the empirical literature.

(1) Current State of Knowledge Based on the Peer-Reviewed Literature

In the labor economics literature there is an extensive body of peer-reviewed empirical 

work analyzing various aspects of labor demand, relying on the above theoretical framework.781

This work focuses primarily on the effects of employment policies, e.g. labor taxes, minimum 

 

bottom of p. 6. In practice, distributional impacts on individual workers can be important, as discussed later in this 

section. 

778 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.

779 Klaiber, H. Allen, and V. Kerry Smith (2012). “Developing General Equilibrium Benefit Analyses for Social 

Programs: An Introduction and Example.” Journal of Benefit-Cost Analysis 3(2). 

780 E.g. Graff Zivin, J., and M. Neidell (2012). “The Impact of Pollution on Worker Productivity.” American 

Economic Review 102: 3652-3673.

781 See Hamermesh (1993), Labor Demand (Princeton, NJ: Princeton University Press), Chapter 2 (Docket EPAHQ-OAR-2014-0827) for a detailed treatment. 
Page 699 of 850

wage, etc.782 In contrast, the peer-reviewed empirical literature specifically estimating 

employment effects of environmental regulations is very limited. Several empirical studies783

suggest that net employment impacts may be zero or slightly positive but small even in the 

regulated sector. Other research suggests that more highly regulated counties may generate 

fewer jobs than less regulated ones.784 However, since these latter studies compare more

regulated to less regulated counties, they overstate the net national impact of regulation to the 

extent that regulation causes plants to locate in one area of the country rather than another. List 

et al. (2003)785 find some evidence that this type of geographic relocation may be occurring. 

Overall, the peer-reviewed literature does not contain evidence that environmental regulation has

a large impact on net employment (either negative or positive) in the long run across the whole 

economy.

Analytic challenges make it very difficult to accurately produce net employment 

estimates for the whole economy that would appropriately capture the way in which costs, 

compliance spending, and environmental benefits propagate through the macro-economy. 

Quantitative estimates are further complicated by the fact that macroeconomic models often have 

very little sectoral detail and usually assume that the economy is at full employment. EPA is 

currently in the process of seeking input from an independent expert panel on modeling 

economy-wide impacts, including employment effects. For more information, see: 

https://federalregister.gov/a/2014-02471.

(2) Employment Impacts in the Motor Vehicle and Parts Manufacturing Sector

This section describes changes in employment in the motor vehicle, trailer, and parts 

(hence, motor vehicle) manufacturing sectors due to these proposed rules. We focus on the 

motor vehicle manufacturing sector because it is directly regulated, and because it is likely to 

bear a substantial share of changes in employment due to these proposed rules. We include 

discussion of effects on the parts manufacturing sector, because the motor vehicle manufacturing 

sector can either produce parts internally or buy them from an external supplier, and we do not 

have estimates of the likely breakdown of effort between the two sectors.

 

782 See Ehrenberg, Ronald G., and Robert S. Smith (2000), Modern Labor Economics: Theory and Public Policy 

(Addison Wesley Longman, Inc.), Chapter 4 (Docket EPA-HQ-OAR-2014-0827), for a concise overview. 

783 Berman, E. and L. T. M. Bui (2001). “Environmental Regulation and Labor Demand: Evidence from the South 

Coast Air Basin.” Journal of Public Economics 79(2): 265-295 (Docket EPA-HQ-OAR2014-0827). 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; Gray et al (2014), and 

Ferris, Shadbegian and Wolverton (2014).

784 Greenstone, M. (2002). “The Impacts of Environmental Regulations on Industrial Activity: Evidence from the 

1970 and 1977 Clean Air Act Amendments and the Census of Manufactures,” Journal of Political Economy 110(6): 

1175-1219 (Docket EPA-HQ-OAR-2014-0827); Walker, Reed. (2011). “Environmental Regulation and Labor 

Reallocation." American Economic Review: Papers and Proceedings 101(3): 442-447 (Docket EPA-HQ-OAR2014-0827).

785List, J. A., D. L. Millimet, P. G. Fredriksson, and W. W. McHone (2003). “Effects of Environmental 

Regulations on Manufacturing Plant Births: Evidence from a Propensity Score Matching Estimator.” The Review of 

Economics and Statistics 85(4): 944-952 (Docket EPA-HQ-OAR2014-0827).
Page 700 of 850

We follow the theoretical structure of Berman and Bui 786 of the impacts of regulation in 

employment in the regulated sectors. In Berman and Bui’s (2001, p. 274-75) theoretical model, 

as described above, the change in a firm’s labor demand arising from a change in regulation is 

decomposed into two main components: output and substitution effects.787 As the output and 

substitution effects may be both positive, both negative, or some combination, standard 

neoclassical theory alone does not point to a definitive net effect of regulation on labor demand 

at regulated firms. 

Following the Berman and Bui framework for the impacts of regulation on employment 

in the regulated sector, we consider two effects for the motor vehicle sector: the output effect 

and the substitution effect. 

(a) The Output Effect

If truck or trailer sales increase, then more people will be required to assemble trucks, 

trailers, and their components. If truck or trailer sales decrease, employment associated with 

these activities will decrease. The effects of this proposed rulemaking on HD vehicle sales thus 

depend on the perceived desirability of the new vehicles. On one hand, this proposed 

rulemaking will increase truck and trailer costs; by itself, this effect would reduce truck and 

trailer sales. In addition, while decreases in truck performance would also decrease sales, this 

program is not expected to have any negative effect on truck performance. On the other hand, 

this proposed rulemaking will reduce the fuel costs of operating the trucks; by itself, this effect 

would increase truck sales, especially if potential buyers have an expectation of higher fuel 

prices. The agencies have not made an estimate of the potential change in truck or trailer sales. 

However, as discussed in IX. E. , the agencies have estimated an increase in vehicle miles 

traveled (i.e., VMT rebound) due to the reduced operating costs of trucks meeting these proposed 

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). 

(b) The Substitution Effect

The output effect, above, measures the effect due to new truck and trailer sales only. The 

substitution effect includes the impacts due to the changes in technologies needed for vehicles to 

 

786Berman, E. and L. T. M. Bui (2001). “Environmental Regulation and Labor Demand: Evidence from the South 

Coast Air Basin.” Journal of Public Economics 79(2): 265-295 (Docket EPA-HQ-OAR2014-0827). 

787 The authors also discuss a third component, the impact of regulation on factor prices, but conclude that this effect 

is unlikely to be important for large competitive factor markets, such as labor and capital. Morgenstern, Pizer and 

Shih (2002) use a similar model, but they break the employment effect into three parts: 1) the demand effect; 2) the 

cost effect; and 3) the factor-shift effect. See 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 (Docket EPA-HQ-OAR-2014-0827).
Page 701 of 850

meet the proposed standards, separate from the effect on output (that is, as though holding output 

constant). This effect includes both changes in employment due to incorporation of abatement 

technologies and overall changes in the labor intensity of manufacturing. We present estimates 

for this effect to provide a sense of the order of magnitude of expected impacts on employment, 

which we expect to be small in the automotive sector, and to repeat that regulations may have 

positive as well as negative effects on employment.

One way to estimate this effect, given the cost estimates for complying with the proposed 

rule, is to use the ratio of workers to each $1 million of expenditures in that sector. The use of 

these ratios has both advantages and limitations. It is often possible to estimate these ratios for 

quite specific sectors of the economy: for instance, it is possible to estimate the average number 

of workers in the motor vehicle body and trailer manufacturing sector per $1 million spent in the 

sector, rather than use the ratio from another, more aggregated sector, such as motor vehicle 

manufacturing. As a result, it is not necessary to extrapolate employment ratios from possibly

unrelated sectors. On the other hand, these estimates are averages for the sectors, covering all 

the activities in those sectors; they may not be representative of the labor required when 

expenditures are required on specific activities, or when manufacturing processes change 

sufficiently that labor intensity changes. For instance, the ratio for the motor vehicle 

manufacturing sector represents the ratio for all vehicle manufacturing, not just for emissions 

reductions associated with compliance activities. In addition, these estimates do not include 

changes in sectors that supply these sectors, such as steel or electronics producers. They thus 

may best be viewed as the effects on employment in the motor vehicle sector due to the changes 

in expenditures in that sector, rather than as an assessment of all employment changes due to 

these changes in expenditures. In addition, this approach estimates the effects of increased 

expenditures while holding constant the labor intensity of manufacturing; it does not take into 

account changes in labor intensity due to changes in the nature of production. This latter effect 

could either increase or decrease the employment impacts estimated here.788

Some of the costs of these proposed rules will be spent directly in the motor vehicle

manufacturing sector, but it is also likely that some of the costs will be spent in the motor vehicle 

body and trailer and motor vehicle parts manufacturing sectors. The analysis here draws on 

estimates of workers per $1 million of expenditures for each of these sectors.

There are several public sources for estimates of employment per $1 million 

expenditures. The U.S. Bureau of Labor Statistics (BLS) provides its Employment 

Requirements Matrix (ERM),789 which provides direct estimates of the employment per $1 

million in sales of goods in 202 sectors. The values considered here are for Motor Vehicle 

Manufacturing (NAICS 3361), Motor Vehicle Body and Trailer Manufacturing (NAICS 3362),

and Motor Vehicle Parts Manufacturing (NAICS 3363) for 2012. 

 

788 As noted above, Morgenstern et al. (2002) separate the effect of holding output constant into two effects: the cost 

effect, which holds labor intensity constant, and the factor shift effect, which estimates those changes in labor 

intensity.

789 http://www.bls.gov/emp/ep_data_emp_requirements.htm.
Page 702 of 850

The Census Bureau provides the Annual Survey of Manufacturers

790 (ASM), a subset of 

the Economic Census, based on a sample of establishments; though the Census itself is more 

complete, it is conducted only every 5 years, while the ASM is annual. Both include more 

sectoral detail than the BLS ERM: for instance, while the ERM includes the Motor Vehicle 

Manufacturing sector, the ASM and Economic Census have detail at the 6-digit NAICS code 

level (e.g., light truck and utility vehicle manufacturing). While the ERM provides direct 

estimates of employees/$1 million in expenditures, the ASM and Economic Census separately

provide number of employees and value of shipments; the direct employment estimates here are 

the ratio of those values. At this time, the Economic Census values for 2012 (the most recent 

year) are not fully available; we therefore do not report them, and instead provide the 2011 ASM 

results (the most recent available). The values reported are for Motor Vehicle Manufacturing 

(NAICS 3361), Light Truck and Utility Vehicle Manufacturing (NAICS 336112), Heavy Duty

Truck Manufacturing (33612), Motor Vehicle Body and Trailer manufacturing (3362), and 

Motor Vehicle Parts Manufacturing (NAICS 3363).

Draft RIA Chapter 9.9 provides the details on the values of workers per $1 

million in expenditures for the sectors mentioned above. In 2012$, these range 

from 0.4 workers per $1 million for light truck & utility vehicle manufacturing in the 

ASM, to 2.8 workers per $1 million in expenditures for Motor Vehicle Body and 

Trailer Manufacturing in the ASM. These values are then adjusted to remove the 

employment effects of imports through use of a ratio of domestic production to domestic sales of 

0.78.

791

 

Over time, the amount of labor needed in the motor vehicle industry has 

changed: automation and improved methods have led to significant productivity 

increases. The BLS ERM, for instance, provided estimates that, in 1993, 1.33

workers in the Motor Vehicle Manufacturing sector were needed per $1 million, but only 0.46 

workers by 2012 (in 2012$).

792

 Because the ERM is available annually for 1993-2012, 

we used these data to estimate productivity improvements over time. We then used 

these productivity estimates to project the ERM through 2027, and to adjust the 

ASM values for 2011. RIA Chapter 9.9.2.2 provides detail on these calculations.

Finally, to simplify the presentation and give a range of estimates, we 

compared the projected employment among the 3 sectors for the ERM and ASM, 

 

790 http://www.census.gov/manufacturing/asm/index.html.

791 To estimate the proportion of domestic production affected by the change in sales, we use data from Ward’s 

Automotive Group for total truck production in the U.S. compared to total truck sales in the U.S. For the period 

2004-2013, the proportion is 78 percent (Docket EPA-HQ-OAR-2014-0827), ranging from 68 percent (2009) to 83 

percent (2012) over that time. 

792 http://www.bls.gov/emp/ep_data_emp_requirements.htm; this analysis used data for sectors 81 (Motor Vehicle 

Manufacturing), 82 (Motor Vehicle Body and Trailer Manufacturing), and 83 (Motor Vehicle Parts Manufacturing) 

from “Chain-weighted (2005 dollars) real domestic employment requirements tables.”
Page 703 of 850

and we provide only the maximum and minimum employment effects estimated for 

the ERM and the ASM. We provide the range rather than a point estimate because 

of the inherent difficulties in estimating employment impacts; the range gives an 

estimate of the expected magnitude. The ERM estimates in the Motor Vehicle 

Parts Manufacturing Sector are consistently the maximum values. The ERM 

estimates in the Motor Vehicle Body and Trailer Manufacturing Sector are the 

minimum values for all years but 2018-2019, when the ASM values for Light Truck 

and Utility Vehicle Manufacturing provide the minimum values.

Section 0 of the Preamble discusses the vehicle cost estimates developed for 

these proposed rules. The final step in estimating employment impacts is to multiply 

costs (in $ millions) by workers per $1 million in costs, to estimate employment 

impacts in the regulated and parts manufacturing sectors. Increased costs of 

vehicles and parts would, by itself, and holding labor intensity constant, be 

expected to increase employment between 2018 and 2027 from none to a few 

thousand jobs each year.

While we estimate employment impacts, measured in job-years, beginning with program 

implementation, some of these employment gains may occur earlier as motor vehicle

manufacturers and parts suppliers hire staff in anticipation of compliance with the standards. A 

job-year is a way to calculate the amount of work needed to complete a specific task. For 

example, a job-year is one year of work for one person. 

Table IX-37 Employment Effects due to Increased Costs of Vehicles and Parts (Substitution Effect), in JobYears

Year Costs (Millions 

of 2012$)

Minimum Employment Due to 

Substitution Effect (ERM 

estimates, expenditures in the 

Parts Sectora)

Maximum Employment Due to 

Substitution Effect (ERM 

estimates, expenditures in the Body 

and Trailer Mfg Sector)

2018 $ 116 0 100 

2019 $ 113 0 100 

2020 $ 112 0 100 

2021 $ 2,173 300 2,300 

2022 $ 2,161 300 2,200 

2023 $ 2,224 200 2,100 

2024 $ 3,455 300 3,200 

2025 $ 3,647 200 3,200 

2026 $ 3,736 200 3,100 

2027 $ 5,309 200 4,200 

Note:

a For 2018 and 2019, the minimum employment effects are associated with the ASM’s Light Truck and Utility 

Vehicle Manufacturing sector.
Page 704 of 850

(c) Summary of Employment Effects in the Motor Vehicle Sector

The overall effect of these proposed rules on motor vehicle sector employment depends 

on the relative magnitude of the output effect and the substitution effect. Because we do not 

have quantitative estimates of the output effect, and only a partial estimate of the substitution 

effect, we cannot reach a quantitative estimate of the overall employment effects of these

proposed rules on motor vehicle sector employment or even whether the total effect will be 

positive or negative. 

The proposed standards are not expected to provide incentives for manufacturers to shift 

employment between domestic and foreign production. This is because the proposed standards 

will apply to vehicles sold in the U.S. regardless of where they are produced. If foreign 

manufacturers already have increased expertise in satisfying the requirements of the standards, 

there may be some initial incentive for foreign production, but the opportunity for domestic 

manufacturers to sell in other markets might increase. To the extent that the requirements of 

these proposed rules might lead to installation and use of technologies that other countries may

seek now or in the future, developing this capacity for domestic production now may provide 

some additional ability to serve those markets. 

(3) Employment Impacts in Other Affected Sectors

(a) Transport and Shipping Sectors

Although not directly regulated by these proposed 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 some of these costs 

savings, depending on the relative elasticities of supply and demand, will be passed along to 

customers. With lower prices, demand for shipping would lead to an increase in demand for 

truck shipping services (consistent with the VMT rebound effect analysis) and therefore an 

increase in employment in the truck shipping sector. In addition, if the relative cost of shipping 

freight via trucks becomes cheaper than shipping by other modes (e.g., rail or barge), then 

employment in the truck transport industry is likely to increase. If the trucking industry is more 

labor intensive than other modes, we would expect this effect to lead to an overall increase in 

employment in the transport and shipping sectors.793,794 Such a shift would, however, be at the 

expense of employment in the sectors that are losing business to trucking. The first effect – a 

gain due to lower shipping costs – is likely to lead to a net increase in employment. The second 

effect, due to mode-shifting, may increase employment in trucking, but decrease employment in 

other shipping sectors (e.g., rail or barge), with the net effects dependent on the labor-intensity of 

the sectors and the volumes.

 

793 American Transportation Research Institute, “An Analysis of the Operational Costs of Trucking: 2011 Update.” 

See http://www.atri-online.org/research/results/Op_Costs_2011_Update_one_page_summary.pdf. 

794 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
Page 705 of 850

(b) Fuel Suppliers

In addition to the effects on the trucking industry and related truck parts sector, these 

proposed 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. 

Section IX. C. of this Preamble provides estimates of the effects of these proposed 

standards on expected fuel consumption. While reduced fuel consumption represents savings for 

purchasers of fuel, it also represents a loss in value of output for the petroleum refinery industry, 

which will result in reduced sectoral employment. Because this sector is material-intensive, the 

employment effect is not expected to be large.795

(c) Fuel Savings

As a result of this proposed rulemaking, it is anticipated that trucking firms will 

experience fuel savings. Fuel savings lower the costs of transportation goods and services. In a 

competitive market, some of the fuel savings that initially accrue to trucking firms are likely to 

be passed along as lower transportation costs that, in turn, could result in lower prices for final 

goods and services. Some of the savings might also be retained by firms for investments or for 

distributions to firm owners. Again, how much accrues to customers versus firm owners will 

depend on the relative elasticities of supply and demand. Regardless, the savings will accrue to 

some segment of consumers: either owners of trucking firms or the general public, and 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 described in Section IX. C. (2) the value of fuel savings from this proposed rulemaking is 

projected to be $15.1 billion (2012$) in 2027, according to Table IX-6. If all those savings are 

spent, the fuel savings will stimulate increased employment in the economy through those 

expenditures. If the fuel savings accrue primarily to firm owners, they may either reinvest the 

money or take it as profit. Reinvesting the money in firm operations could increase employment 

directly. If they take the money as profit, to the extent that these owners are wealthier than the 

general public, they may spend less of the savings, and the resulting employment impacts would 

be smaller than if the savings went to the public. Thus, while fuel savings are expected to 

decrease employment in the refinery sector, they are expected to increase employment through 

increased consumer expenditures.

(4) Summary of Employment Impacts

The primary employment effects of these rules are expected to be found throughout 

several key sectors: truck and engine manufacturers, the trucking industry, truck parts 

manufacturing, fuel production, and consumers. These rules initially takes effect in model year 

 

795 In the 2012 BLS ERM cited above, the Petroleum and Coal Products Manufacturing sector has a ratio of workers 

per $1 million of 0.242, lower than all but two of the 181 sectors with non-zero employment per $1 million.
Page 706 of 850

2018, a time period sufficiently far in the future that the unemployment rate at that time is 

unknowable. In an economy with full employment, the primary employment effect of a 

rulemaking is likely to be to move employment from one sector to another, rather than to 

increase or decrease employment. For that reason, we focus our partial quantitative analysis on 

employment in the regulated sector, to examine the impacts on that sector directly. We discuss 

the likely direction of other impacts in the regulated sector as well as in other directly related 

sectors, but we do not quantify those impacts, because they are more difficult to quantify with 

reasonable accuracy, particularly so far into the future.

For the regulated sector, we have not quantified the output effect. The substitution effect 

is associated with potential increased employment from none to a few thousand jobs per year 

between 2018 and 2027, depending on the share of employment impacts in the affected sectors 

(Motor Vehicle Manufacturing, Motor Vehicle Body and Trailer Manufacturing, and Motor 

Vehicle Parts Manufacturing). These estimates do not include potential changes, either greater 

or less, in labor intensity of production. As mentioned above, some of these job gains may occur 

earlier as auto manufacturers and parts suppliers hire staff to prepare to comply with the 

standard. 

Lower prices for shipping are expected to lead to an increase in demand for truck 

shipping services and, therefore, an increase in employment in that sector, though this effect may

be offset somewhat by changes in employment in other shipping sectors. Reduced fuel 

production implies less employment in the fuel provision sectors. Finally, any net cost savings 

would be expected to be passed along to some segment of consumers: either the general public or 

the owners of trucking firms, who are expected then to increase employment through their 

expenditures. Under conditions of full employment, any changes in employment levels in the 

regulated sector due to this program are mostly expected to be offset by changes in employment 

in other sectors.

M. Cost of Ownership and Payback Analysis

This section examines the economic impacts of the Phase 2 proposed standards from the 

perspective of buyers, operators, and subsequent owners of new HD vehicles, first in the 

aggregate and then at the level of individual purchasers of different types of vehicles. In each 

case, the analysis assumes that HD vehicle manufacturers are able to recover their costs for 

improving fuel efficiency – including direct technology outlays, indirect costs, and normal 

profits on any additional capital investments – by charging higher prices to HD vehicle buyers. 

As summarized below, HDV buyers in the aggregate would experience substantial savings in 

fuel costs that would more than offset higher initial outlays to buy more fuel-efficient new 

vehicles.

Table IX-38 reports aggregate benefits and costs to buyers and operators of new HD 

vehicles for the Preferred Alternative using Method A. The table reports economic impacts on 

buyers using only the 7 percent discount rate, since that rate is intended to represent the 

opportunity cost of capital that HD vehicle buyers and users must divert from other investment 

opportunities to purchase more costly vehicles. As it shows, fuel savings and the other benefits 

from increased fuel efficiency – savings from less frequent refueling and benefits from additional 

truck use – far outweigh the higher costs to buyers of new HD vehicles. As a consequence, 
Page 707 of 850

buyers, operators, and subsequent owners of HD vehicles subject to the Phase 2 standards are

together projected to experience large economic gains under the Preferred Alternative. It should 

be noted that, because the original buyers may not hold the vehicles for their lifetimes, and 

because those who own or operate the vehicles may not pay for the fuel, these benefits and costs 

do not necessarily represent benefits and costs to identifiable individuals.

As Table IX-38 shows, the agencies have estimated the increased costs for maintenance 

of the new technologies that HD vehicle manufacturers would employ to decrease fuel 

consumption, and these costs are included together with those for purchasing more fuel-efficient 

vehicles. Manufacturers’ efforts to comply with the Phase 2 standards could also result in 

changes to vehicle performance and capacity for certain vehicles. For example, reducing the 

mass of HD vehicles in order to improve fuel efficiency could be used to improve their loadcarrying capabilities, while some engine technologies and aerodynamic modifications could 

reduce payload capacity. The agencies request comment on possible changes to vehicle 

performance and load-carrying capacity as a result of the proposal along with supporting 

information.

Table IX-38 MY2018-2029 Lifetime Aggregate Impacts of the Preferred Alternative on All HD Vehicle 

Buyers and Operators using Method A (billions of 2012$, discounted at 7%) a

Baseline 1a Baseline 1b

Vehicle costs 17.1 16.8

Maintenance costs 0.6 0.6

 Total costs to HD vehicle buyers 17.7 17.4

Fuel savings b

(valued at retail prices)

104.6 99.1

Refueling benefits 1.6 1.5

Increased travel benefits 8.4 8.2

 Total benefits to HD vehicle buyers/operators 114.7 108.9

Net benefits to HD vehicle buyers/operators c

97.0 91.5

Notes:

a For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the 

less dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

b Fuel savings includes fuel consumed during additional rebound driving.

c Net benefits shown do not include benefits associated with carbon or other co-pollutant emission 

reductions, accidents/congestion/noise impacts, energy security, etc.

Table IX-38 shows aggregate benefits and costs to buyers and operators of new HD 

vehicles for the Preferred Alternative using Method B, again for only the 7 percent discount rate. 

As it shows, fuel savings and the other benefits outweigh the higher prices and added 

maintenance costs that buyers and operators of new HD vehicles pay, so they are again expected 

to experience large economic gains from the Preferred Alternative. Again, because the original 

buyers may not hold the vehicles for their lifetimes, and because those who own or operate the 

vehicles may not pay for the fuel, these benefits and costs do not necessarily represent benefits 

and costs to identifiable individuals.
Page 708 of 850

Table IX-39 MY2018-2029 Lifetime Aggregate Impacts of the Preferred Alternative on All HD Vehicle 

Buyers and Operators using Method B (billions of 2012$, discounted at 7%) a

Baseline 1b

Vehicle costs $16.6

Maintenance costs $0.6

 Total costs to HD vehicle buyers $17.2

Fuel savings b

(valued at retail prices)

$100.1

Refueling benefits $1.6

Increased travel benefits $8.2

 Total benefits to HD vehicle buyers/operators $109.9

Net benefits to HD vehicle buyers/operators c

$92.7

Notes:

a For an explanation of analytical Methods A and B, please see Section I.D; for an 

explanation of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please 

see Section X.A.1.

b Fuel savings includes fuel consumed during additional rebound driving.

c Net benefits shown do not include benefits associated with carbon or other 

co-pollutant emission reductions, accidents/congestion/noise impacts, energy 

security, etc.

It is also useful to examine the cost of purchasing and owning a new vehicle that 

complies with the Phase 2 standards and its payback period – the point at which cumulative 

savings from lower fuel expenditures outpace increased vehicle costs. For example, a new 

MY2027 tractor is estimated to cost roughly $11,684 more (on average, or roughly 12 percent of 

a typical $100,000 reference case tractor) due to the addition of new GHG reducing/fuel 

consumption improving technology. This new technology would result in lower fuel 

consumption and, therefore, reduced fuel expenditures. But how many months or years would 

pass before the reduced fuel expenditures would surpass the increased upfront costs? 

Table IX-40 presents the discounted annual increased vehicle costs and fuel savings 

associated with owning a new MY2027 HD pickup or van using both 3 percent and 7 percent 

discount rates. Table IX-41 and Table IX-42 show the same information for a MY2027 

vocational vehicle and a tractor/trailer, respectively. These comparisons include sales taxes, 

excise taxes (for vocational and tractor/trailer) and increased insurance expenditures on the 

higher value vehicles, as well as maintenance costs associated with replacement of lower rolling 

resistance tires throughout the lifetimes of affected vehicles. Importantly, the values behind the 

tables in this payback analysis do not include rebound miles driven and/or rebound gallons 

consumed. Instead, the tables use reference case miles driven combined with policy case fuel 

consumption. We detail these input metrics in Chapter 7 of the draft RIA.
Page 709 of 850

The fuel expenditure column uses retail fuel prices specific to gasoline and diesel fuel as 

projected in AEO2014.796 This payback analysis does not include other impacts, such as reduced 

refueling events, the value of driving potential rebound miles, or noise, congestion and accidents. 

We use retail fuel prices and exclude these other private and social impacts because the analysis

is intended to focus on those factors that are most important to buyers when considering a new 

vehicle purchase, and to include only those factors that have clear dollar impacts on HD vehicle 

buyers. 

As shown, payback would occur in the 3rd year of ownership for HD pickups and vans 

(the first year where cumulative net costs turn negative), in the 5th year for vocational vehicles (at 

a 3 percent discount rate, 6th year at a 7 percent discount rate) and early in the 2nd year for 

tractor/trailers. Note that each table reflects the average vehicle and reflects proper weighting of 

fuel consumption/costs (gasoline vs. diesel). We request comment and supporting data on all 

aspects of our payback analysis.

Table IX-40 Discounted Annual Incremental Expenditures for a MY2027 HD Pickup or Van using Method B 

and Relative to the Less Dynamic Baseline (2012$) a

Age in 

years

3% Discount Rate 7% Discount Rate

Vehicleb MaintcFueld Cumulative

Net

Vehicleb MaintcFueld Cumulati

ve

Net

1 $1,587 $4 -$759 $832 $1,558 $3 -$745 $817

2 $25 $3 -$734 $126 $23 $3 -$694 $150

3 $23 $3 -$714 -$561 $21 $3 -$649 -$476

4 $22 $3 -$693 -$1,229 $19 $3 -$606 -$1,060

5 $20 $3 -$651 -$1,857 $17 $2 -$549 -$1,590

6 $19 $3 -$611 -$2,446 $15 $2 -$496 -$2,067

7 $18 $2 -$571 -$2,997 $14 $2 -$446 -$2,497

8 $16 $2 -$536 -$3,514 $12 $2 -$403 -$2,886

Notes:

a For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

b Includes new technology costs, insurance costs and sales taxes.

c Maintenance costs.

d Uses AEO2014 retail fuel prices.

 

796 U.S. Energy Information Administration, Annual Energy Outlook 2014, Early Release; Report Number 

DOE/EIA-0383ER(2014), December 16, 2013.
Page 710 of 850

Table IX-41 Discounted Annual Incremental Expenditures for a MY2027 Vocational Vehicle using Method B 

and Relative to the Less Dynamic Baseline (2012$) a

Age in 

years

3% Discount Rate 7% Discount Rate

Vehicleb MaintcFueld Cumulative

Net

Vehicleb MaintcFuel

c Cumulati

ve

Net

1 $3,998 $10 -$965 $3,043 $3,924 $10 -$947 $2,987

2 $63 $9 -$937 $2,178 $59 $9 -$885 $2,169

3 $59 $9 -$914 $1,331 $53 $8 -$832 $1,399

4 $55 $9 -$891 $504 $48 $8 -$780 $675

5 $51 $8 -$829 -$265 $43 $7 -$699 $27

6 $48 $7 -$771 -$981 $39 $6 -$625 -$554

7 $45 $7 -$716 -$1,645 $35 $5 -$559 -$1,073

8 $42 $6 -$667 -$2,264 $31 $5 -$501 -$1,538

Notes:

a For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

b Includes new technology costs, insurance costs, excise and sales taxes.

c Maintenance costs.

d Uses AEO2014 retail fuel prices.

Table IX-42 Discounted Annual Incremental Expenditures for a MY2027 Tractor/Trailer using Method B 

and Relative to the Less Dynamic Baseline (2012$ a)

Age in 

years

3% Discount Rate 7% Discount Rate

Vehicleb MaintcFueld Cumulative

Net

Vehicleb MaintcFueld Cumulati

ve

Net

1 $15,194 $48 -$14,649 $593 $14,914 $47 -$14,379 $582

2 $238 $46 -$14,204 -$13,327 $225 $43 -$13,421 -$12,571

3 $223 $44 -$13,809 -$26,869 $203 $40 -$12,561 -$24,889

4 $209 $42 -$13,416 -$40,034 $183 $37 -$11,746 -$36,415

5 $195 $39 -$12,391 -$52,191 $164 $33 -$10,443 -$46,661

6 $182 $35 -$11,411 -$63,385 $148 $29 -$9,258 -$55,743

7 $170 $32 -$10,511 -$73,694 $133 $25 -$8,209 -$63,794

8 $158 $29 -$9,704 -$83,211 $119 $22 -$7,295 -$70,949

Notes:

a For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less dynamic 

baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.

b Includes new technology costs, insurance costs, excise and sales taxes.

c Maintenance costs.

d Uses AEO2014 retail fuel prices.

N. Safety Impacts

(1) Summary of Supporting HD Vehicle Safety Research

NHTSA and EPA considered the potential safety impact of technologies that improve HD 

vehicle fuel efficiency and GHG emissions as part of the assessment of regulatory alternatives. 

The safety assessment of the technologies in this proposal was informed by two NAS reports, an 

analysis of safety effects of HD pickups and vans using estimates from the DOT report on the 
Page 711 of 850

effect of mass reduction and vehicle size on safety, and agency-sponsored safety testing and 

research. A summary of the literature and work considered by the agencies follows. 

(2) National Academy of Sciences HD Phase 1 and Phase 2 Reports

As required by EISA, the National Research Council has conducted two studies of the 

technologies and approaches for reducing the fuel consumption of medium- and heavy-duty 

vehicles. The first was documented in a report issued in 2010, “Technologies and Approaches to 

Reducing the Fuel Consumption of Medium- and Heavy-Duty Vehicles’’ (“NAS Report”). The 

second was documented in a report issued in 2014, “Reducing the Fuel Consumption and 

Greenhouse Gas Emissions of Medium- and Heavy-Duty Vehicles, Phase Two-First Report” 

(“NAS HD Phase 2 First Report”). While the reports primarily focused on reducing vehicle fuel 

consumption and emissions through technology application, and examined potential regulatory

frameworks, both reports additionally contain findings and recommendations on safety. In 

developing this proposal, the agencies carefully considered both of the reports’ findings related 

to safety. Some of the reports’ key findings related to safety follow.

NAS commented that idle reduction strategies in actual can be sophisticated to provide for the 

safety of the driver in hot and cold weather.

797

 The agencies considered this comment in our 

approach for idle reduction technologies and allow override provisions, as discussed in Section 

III. Override is allowed if the external ambient temperature reaches a level below which or 

above which the cabin temperature cannot be maintained within reasonable heat or cold exposure 

threshold limit values for the health and safety of the operator (not merely comfort).NAS 

commented extensively on the recent emergence of natural gas (NG) as a viable technology

option for commercial vehicles, but alluded to the existence of uncertainties regarding its safety. 

The committee found that while the public crash databases do not contain information on vehicle 

fuel type, the existing information indicates that the crash-related safety risk for NG storage on 

vehicles does not appear to be appreciably different from diesel fuel risks. The committee also 

found that while there are two existing SAE-recommended practice standards for NG-powered 

HD vehicles, the industry could benefit from best practice directives to minimize crash risks for 

NG fuel tanks, such as on shielding to prevent punctures during crashes. As a final point, NAS 

stated that manufacturers and operators have a great incentive to prevent possible NG leakage 

from a vehicle fuel system because it would be a significant safety concern and reduce vehicle 

range. No recommendations were made for additional Federal safety regulations for these 

vehicles. In response, the agencies have reviewed and discuss the existing NG vehicle standards 

and best practices cited by NAS in Section XI.

In the NAS Committee’s Phase 1 report, the Committee commented that aerodynamic fairings 

detaching from trucks on the road was a potential safety issue. However, the Phase 2 interim 

report stated that “Anecdotal information gained during the observations of on-road trailers 

 

797 Id., p. 33.
Page 712 of 850

indicates a few skirts badly damaged or missing from one side. The skirt manufacturers report no 

safety concerns (such as side skirts falling off) and little maintenance needed.” 

The NAS report also identified the link between tire inflation and condition and vehicle stopping 

distance and handling, which impacts overall safety. The committee found that tire pressure 

monitoring systems and automatic tire inflation systems are being adopted by fleets at an 

increasing rate. However, the committee noted that there are no standards for performance, 

display, and system validation. The committee recommended that NHTSA issue a white paper 

on the minimum performance of tire pressure systems from a safety perspective. 

The agencies considered the safety findings in both NAS reports in developing this proposal and 

conducted additional research on safety to further examine information and findings of the 

reports.

(3) DOT CAFE Model HD Pickup and Van Safety Analysis

This analysis considered the potential effects on crash safety of the technologies manufacturers 

may apply to their HD pickups and vans to meet each of the regulatory alternatives evaluated. 

NHTSA research has shown that vehicle mass reduction affects overall societal fatalities 

associated with crashes and, most relevant to this proposal, that mass reduction in heavier lightand medium-duty vehicles has an overall beneficial effect on societal fatalities. Reducing the 

mass of a heavier vehicle involved in a crash with another vehicle(s) makes it less likely that 

there will be fatalities among the occupants of the other vehicles. In addition to the effects of 

mass reduction, the analysis anticipates that the proposed standards, by reducing the cost of 

driving HD pickups and vans, would lead to increased travel by these vehicles and, therefore, 

more crashes involving these vehicles. The Method A analysis considers overall impacts from 

both of these factors, using a methodology similar to NHTSA’s analyses for the MYs 2017 –

2025 CAFE and GHG emission standards.

The Method A analysis includes estimates of the extent to which HD pickups and vans produced 

during MYs 2014-2030 may be involved in fatal crashes, considering the mass, survival, and 

mileage accumulation of these vehicles, taking into account changes in mass and mileage 

accumulation under each regulatory alternative. These calculations make use of the same 

coefficients applied to light trucks in the MYs 2017-2025 CAFE rulemaking analysis. As 

discussed above, vehicle miles traveled may increase due to the fuel economy rebound effect, 

resulting from improvements in vehicle fuel efficiency and cost of fuel, as well as the assumed 

future growth in average vehicle use. Increases in total lifetime mileage increase exposure to 

vehicle crashes, including those that result in fatalities. Consequently, the modeling system 

computes total fatalities attributed to vehicle use for vehicles of a given model year based on 

safety class and weight threshold. These calculations also include a term that accounts for the 

fact that vehicles involved in future crashes will be certified to more stringent safety standards 

than those involved with past crashes upon which the base rates of involvement in fatal crashes 

were estimated. Since the use of mass reducing technology is present within the model, safety 

impacts may also be observed whenever a vehicle’s base weight decreases. Thus, in addition to 

computing total fatalities related to vehicle use, the modeling system also estimates changes in 

fatalities due to reduction in a vehicle’s curb weight. 
Page 713 of 850

The total fatalities attributed to vehicle use and vehicle weight change for vehicles of a given 

model year are then summed. Lastly, total fatalities occurring within the industry in a given 

model year are accumulated across all vehicles. In addition to using inputs to estimate the future 

involvement of modeled vehicles in crashes involving fatalities, the model also applies inputs 

defining other accident-related externalities estimated on a dollar per mile basis. For vehicles 

above 4,594 pounds—i.e., the majority of the HD pickup and van fleet—mass reduction is 

estimated to reduce the net incidence of highway fatalities by 0.34 percent per 100 pounds of 

removed curb weight. For the few HD pickups and vans below 4,594 pounds, mass reduction is 

estimated to increase the net incidence of highway fatalities by 0.52 percent per 100 pounds. 

Because there are many more HD pickups and vans above 4,594 pounds than below 4,594 

pounds, the overall effect of mass reduction in the segment is estimated to reduce the incidence 

of highway fatalities. The estimated increase in vehicle miles traveled due to the fuel economy 

rebound effect is estimated to increase exposure to vehicle crashes and offset these reductions. 

(4) Volpe Research on MD/HD Fuel Efficiency Technologies

The 2010 National Research Council report “Technologies and Approaches to Reducing the Fuel 

Consumption of Medium- and Heavy-Duty Vehicles” recommended that NHTSA perform a 

thorough safety analysis to identify and evaluate potential safety issues with fuel efficiencyimproving technologies. The Department of Transportation Volpe Center’s 2015 report titled 

“Review and Analysis of Potential Safety Impacts and Regulatory Barriers to Fuel Efficiency

Technologies and Alternative Fuels in Medium- and Heavy-Duty Vehicles” summarizes research 

and analysis findings on potential safety issues associated with both the diverse alternative fuels 

(natural gas-CNG and LNG, propane, biodiesel, and power train electrification), and the specific 

FE technologies recently adopted by the MD/HDV fleets. These include Intelligent 

Transportation Systems (ITS) and telematics, speed limiters, idle reduction devices, tire 

technologies (single-wide tires, and tire pressure monitoring systems-TPMS and Automated Tire 

Inflation Systems-ATIS), aerodynamic components, vehicle light-weighting materials, and Long 

Combination Vehicles (LCVs). 

Chapter 1 provides an overview of the study’s rationale, background, and key objective, namely, 

to identify the technical and operational/behavioral safety benefits and disbenefits of MD/HDVs 

equipped with FE technologies and using emerging alternative fuels (AFs). Recent MD/HDV 

national fleet crash safety statistical averages are also provided for context, although no 

information exists in crash reports relating to specific vehicle FE technologies and fuels. 

(NHTSA/FARS and FMCSA/CSA databases do not include detailed information on vehicle fuel

economy technologies, since the state crash report forms are not coded down to an individual 

fuel economy technology level).

Chapters 2 and 3 are organized by clusters of functionally-related FE technologies for vehicles 

and trailers (e.g., tire systems, ITS, light-weighting materials, and aerodynamic systems) and 

alternative fuels, which are described and their respective associated potential safety issues are 

discussed. Chapter 2 summarizes the findings from a comprehensive review of available 

technical and trade literature and Internet sources regarding the benefits, potential safety hazards, 

and the applicable safety regulations and standards for deployed FE technologies and alternative 

fuels. Chapter 2 safety-relevant fuel-specific findings include:
Page 714 of 850

• Both CNG- and LNG-powered vehicles present potential hazards, and call for well-known 

engineering and process controls to assure safe operability and crashworthiness. However, 

based on the reported incident rates of NGVs and the experiences of adopting fleets, it 

appears that NGVs can be operated at least as safely as diesel MD/HDVs. 

• There are no safety contraindications to the large scale fleet adoption of CNG or LNG 

fueled heavy duty trucks and buses, and there is ample experience with the safe operation 

of large public transit fleets. Voluntary industry standards and best practices suffice for 

safety assurance, though improved training of CMV operators and maintenance staff in 

natural gas safety of equipment and operating procedures is needed.

• Observing CNG and LNG fuel system and maintenance facility standards, coupled with 

sound design, manufacture, and inspection of natural gas storage tanks will further reduce 

the potential for leaks, tank ruptures, fires, and explosions.

• Biodiesel blends used as drop-in fuels have presented some operational safety concerns 

dependent on blending fraction, such as material compatibility, bio-fouling sludge 

accumulation, or cold-weather gelling. However, best practices for biodiesel storage, and 

improved gaskets and seals that are biodiesel resistant, combined with regular maintenance 

and leak inspection schedules for the fuel lines and components enable the safe use of 

biodiesel in newer MD/HDVs.

• Propane (LPG, or autogas) presents well-known hazards including ignition (due to leaks or 

crash) that are preventable by using Overfill Prevention Devices (OPDs), which 

supplement the automatic stop-fill system on the fueling station side, and pressure release 

devices (PRDs). Established best practices and safety codes (e.g., NFPA) have proven that 

propane fueled MD/HDVs can be as operationally safe as the conventionally-fueled 

counterparts. 

• As the market penetration of hybrid and electric drivetrain accelerates, and as the capacity 

and reliability of lithium ion batteries used in Rechargeable Energy Storage Systems 

(RESS) improve, associated potential safety hazards (e.g., electrocution from stranded 

energy, thermal runaway leading to battery fire) have become well understood, 

preventable, and manageable. Existing and emerging industry technical and safety 

voluntary standards, applicable NHTSA regulations and guidance, and the growing 

experience with the operation of hybrid and electric MD/HDVs will enable the safe 

operation and large-scale adoption of safer and more efficient power-train electrification 

technologies. 

The safety findings from literature review pertaining to the specific FE technologies 

implemented to date in the MD/HDV fleet include:

• Telematics—integrating on-board sensors, video, and audio alerts for MD/HDV drivers—

offer potential improvements in both driver safety performance and fuel efficiency. Both 

camera and non-camera based telematics setups are currently integrated with available 

crash avoidance systems (such as ESC, RSC, LDWS, etc.) and appear to be well accepted 

by MD/HDV fleet drivers. 
Page 715 of 850

• Both experience abroad and the cited US studies of trucks equipped with active speed 

limiters indicated a safety benefit, as measured by up to 50% reduced crash rates, in 

addition to fuel savings and other benefits, with good CMV driver acceptance. Any 

negative aspects were small and avoidable if all the speed limitation devices were set to the 

same speed, so there would be less need for overtaking at highway speeds.

• No literature reports of adverse safety impacts were found regarding implementation of onboard idle-reduction technologies in MD/HDVs (such as automatic start-stop, direct-fired 

heaters, and APUs).

• There was no clear consensus from the literature regarding the relative crash rates and

highway safety impacts of LCVs, due to lack of sufficient data and controls and 

inconsistent study methodologies. Recent safety evaluations of LCVs and ongoing MAP-21 

mandated studies will clarify and quantify this issue.

• Tire technologies for FE (including ATIS, TPMS, LRR and single-wide tires) literature 

raised potential safety concerns regarding lower stability or loss of control, e.g., when tire 

pressure is uneven or a single wide tire blows out on the highway. However, systems such 

as automated tire monitoring systems and stability enhancing electronic systems (ABS, 

ESC, RSC) may compensate and mitigate any adverse safety impacts. 

• Aerodynamic technologies that offer significant fuel savings have raised potential concerns 

about vehicle damage or injury in case of detached fairings or skirts, although there were 

no documented incidents of this type in the literature. 

• Some light weighting materials may pose some fire safety and crashworthiness hazards, 

depending on their performance in structural or other vehicle subsystem applications 

(chassis, power-train, crash box or safety cage). Some composites (fiberglass, plastics, 

CFRC, foams) may become brittle on impact or due to weathering from UV exposure or 

extreme cold. Industry has developed advanced, high performance lightweight material 

options tailored to their automotive applications, e.g., thermoplastics resistant to UV and 

weathering. No examples of such lightweight material failures on MD/HDVs were 

identified in the literature. 

Chapter 3 provides complementary inputs on the potential safety issues associated with FE 

technologies and alternative fuels obtained from Subject Matter Experts (SMEs). The broad 

cross-section of SMEs consulted had experience with the operation of “green” truck and bus 

fleets, were Federal program managers, or were industry developers of FE systems for 

MD/HDVs. Safety concerns raised by the SMEs can be prevented or mitigated by complying 

with applicable regulations and safety standards and best practices, and are being addressed by

evolving technologies, such as electronic collision prevention devices. Although SMEs raised 

some safety concerns, their experience indicates that system- or fuel-specific hazards can be 

prevented or mitigated by observing applicable industry standards, and by training managers, 

operators and maintenance staff in safety best practices. Specific safety concerns raised by SMEs 

based on their experience included:
Page 716 of 850

• Alternative fuels did not raise major safety concerns, but generally required better 

education and training of staff and operators. There was a concern expressed regarding 

high pressure (4000 psi) CNG cylinders that could potentially explode in a crash scenario 

or if otherwise ruptured. However, aging CNG fuel tank safety can be assured by 

enforcing regulations such as FMVSS No. 304, and by periodic inspection and end-of-life 

disposal and replacement. A propane truck fleet manager stated that the fuel was as safe as 

or safer than gasoline, and reported no safety issues with the company’s propane, nor with 

hybrid gasoline-electric trucks. OEMs of drivetrain hybridization and electrification 

systems, including advanced Lithium Ion batteries for RESS, indicated that they undergo 

multiple safety tests and are designed with fail-safes for various misuse and abuse 

scenarios. Integration of hybrid components downstream by bodybuilders in retrofits, as 

opposed to new vehicles, was deemed a potential safety risk. Another potential safety 

concern raised was the uncertain battery lifetime due to variability of climate, duty-cycles, 

and aging. Without state-of-charge indicators, this could conceivably leave vehicles 

underpowered or stranded if the battery degrades and is not serviced or replaced in a timely 

manner. 

• ITS and telematics raised no safety concerns; on the contrary, fleet managers stated that 

“efficient drivers are safer drivers.” Monitoring and recording of driver behavior, combined 

with coaching, appeared to reduce distracted and aggressive driving and provided 

significant FE and safety benefits. 

• A wide-base single tire safety concern was the decrease in tire redundancy in case of a tire 

blowout at highway speeds. For LRRs, a concern was that they could negatively affect 

truck stopping distance and stability control.

• A speed-limiter safety concern was related to scenarios when such trucks pass other 

vehicles on the highway instead of staying in the right-hand lane behind other vehicles. By

combining speed limiters with driver training programs, overall truck safety could actually 

improve, as shown by international practice. 

• Aerodynamic systems’ safety performance to date was satisfactory, with no instances of 

on-road detaching. However, covering underside or other components with aerodynamic 

fairings can make them harder to inspect, such as worn lugs, CNG relief valve shrouds, 

wheel covers, and certain fairings. Drivers and inspectors need to be able to see through 

wheel covers and to be able to access lug nuts through them. These covers must also be 

durable to withstand frequent road abuse. 

• For lightweighting materials, the safety concern raised was lower crashworthiness 

(debonding or brittle fracture on impact) and the potential for decreased survivability in 

vehicle fires depending on the specific material choice and its application. 

The key finding from the literature review and SME interviews is that there appear to be no 

major safety hazards preventing the adoption of FE technologies, or the increased use of 

alternative fuels and vehicle electrification. In view of the scarcity of hard data currently 

available on actual highway crashes that can be directly or causally attributed to adoption of FE 

technologies and/or alternative fuels by MD/HDVs, and the limited experience with commercial 
Page 717 of 850

truck and transit bus fleets operations equipped with these technologies, it was not possible to 

perform a quantitative, probabilistic risk assessment, or even a semi-quantitative preliminary

hazard analysis (PHA). Chapter 4 employs a deterministic scenario-based hazard analysis of 

potential crash or other safety concerns identified from the literature review or raised by subject 

matter experts (SMEs) interviewed (e.g., interfaces with charging or refueling infrastructure). 

For each specific hazard scenario discussed, the recommended prevention or mitigation options, 

including compliance with applicable NHTSA or FMCSA regulations, and voluntary industry

standards and best practices are identified, along with FE technology or fuel-specific operator 

training. SMEs safety concerns identified in Sec 3.3 were complemented with actual incidents, 

and developed into the hazard scenarios analyzed in Chapter 4.

The scenario-based deterministic hazard analysis reflected not only the literature findings and 

SMEs’ safety concerns, but also real truck or bus mishaps that have occurred in the past. Key

hazard analysis scenarios included: CNG-fueled truck and bus vehicle fires or explosions due to 

tank rupture, when pressurized fuel tanks were degraded due to aging or when PRDs failed; LNG 

truck crashes leading to fires, or LNG refueling-related mishaps; the flammability or brittle 

fracture issues related to lightweighting materials in crashes; reduced safety performance for 

either LRR or wide-base tires; highway pile-ups when LCVs attempt to pass at highway speeds; 

aerodynamic components detaching while the vehicle traveled on a busy highway or urban 

roadway; and fires resulting in overheated lithium ion batteries in electric or hybrid buses. These 

hypothetical worst case scenarios appear to be preventable or able to be mitigated by observing 

safety regulations and voluntary standards, or with engineering and operational best practices. 

Chapter 5 reviews and discusses the existing federal and state regulatory framework for safely 

operating MD/HDVs equipped with FE technologies or powered by alternative fuels. The 

review identifies potential regulatory barriers to their large-scale deployment in the national fleet 

that could delay achievement of desired fuel consumption and environmental benefits, while 

ensuring equal or better safety performance.

Chapter 6 summarizes the major findings and recommendations of this preliminary safety 

analysis of fuel efficiency technologies and alternative fuels adopted by MD/HDVs. The 

scenario-based hazard analysis, based on the literature review and experts’ inputs, indicates that 

MD/HDVs equipped with advanced FE technologies and/or using alternative fuels have 

manageable potentially adverse safety impacts. The findings suggest that the potential safety 

hazards identified during operation, maintenance, and crash scenarios can be prevented or 

mitigated by complying with safety regulations and voluntary standards and industry best 

practices. The study also did not identify any major regulatory barriers to rapid adoption of FE 

technologies and alternative fuels by the MD/HDV fleet. 

(5) Oak Ridge National Laboratory (ORNL) Research on Low Rolling Resistance 

Truck Tires

DOT’s Federal Motor Carrier Safety Administration and NHTSA sponsored a test program 

conducted by Oak Ridge National Laboratory to explore the effects of tire rolling resistance 

levels on Class 8 tractor-trailer stopping distance performance over a range of loading and 

surface conditions. The objective was to determine whether there is a relationship between tire 

rolling resistance and stopping distance for vehicles of this type. The overall results of this 
Page 718 of 850

research suggest that tire rolling resistance is not a reliable indicator of Class 8 tractor-trailer 

stopping distance. The correlation coefficients (R2 values) for linear regressions of wet and dry

stopping distance versus overall vehicle rolling resistance values did not meet the minimum 

threshold for statistical significance for any of the test conditions. Correlation between CRR and 

stopping distance was found to be negligible for the dry tests for both loading conditions. While 

correlation was higher for the wet testing (showing a slight trend in which lower CRRs 

correspond to longer stopping distances), it still did not meet the minimum threshold for 

statistical significance. In terms of compliance with Federal safety standards, it was found that 

the stopping distance performance of the vehicle with the four tire sets studied in this research 

(with estimated tractor CRRs which varied by 33%), were well under the FMVSS No. 121 

stopping distance requirements. 

(6) The Agencies’ Assessment of Potential Safety Impacts

NHTSA and EPA considered the potential safety impact of technologies that improve HD 

vehicle fuel efficiency and GHG emissions as part of the assessment of regulatory alternatives. 

The safety assessment of the technologies in this proposal was informed by two NAS reports, an 

analysis of safety effects of HD pickups and vans using estimates from the DOT report on the 

effect of mass reduction and vehicle size on safety, and agency-sponsored safety testing and 

research. The agencies considered safety from the perspective of both direct effects and indirect 

effects.

In terms of direct effects on vehicle safety, research from NAS and Volpe, and direct testing of 

technologies like the ORNL tire work, indicate that there are no major safety hazards associated 

with the adoption of technologies that improve HD vehicle fuel efficiency and GHG emissions or 

the increased use of alternative fuels and vehicle electrification. The findings suggest that the 

potential safety hazards identified during operation, maintenance, and crash scenarios can be 

prevented or mitigated by complying with safety regulations and voluntary standards and 

industry best practices. Tire testing showed tire rolling resistance did not impact of Class 8 

tractor-trailer stopping distance for the tires tested. Also, because the majority of HD pickup and 

van fleet are above 4,594 pounds, the vehicle mass reduction in HD pickup and vans is estimated 

to reduce the net incidence of highway fatalities. Taken together, these studies suggest that the 

fuel efficiency improving technologies assessed in the studies can be implemented with no 

degradation in overall safety.

However, analysis anticipates that the indirect effect of the proposed standards, by

reducing the operating costs, would lead to increased travel by tractor-trailers and HD pickups 

and vans and, therefore, more crashes involving these vehicles. 
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Page 719 of 850

X. Analysis of the Alternatives

As discussed throughout this preamble, in developing this proposal the agencies

considered a number of regulatory alternatives that could result in potentially fewer or greater 

GHG emission and fuel consumption reductions than the program we are proposing. This 

section summarizes the alternatives we considered and presents estimates of technology costs, 

CO2 reductions, fuel savings, and other costs and benefits associated with each alternative. The 

agencies request comment on each of these alternatives, as well as other potential levels of 

stringency and implementation timing. Note that since the impacts of these alternatives differ 

among the various heavy-duty vehicle categories, commenters are encouraged to address the 

alternatives separately for each vehicle category.

In developing alternatives, both agencies must consider a range of stringency. NHTSA 

must consider EISA's requirement for the MD/HD fuel efficiency program. In particular, 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, cost-effective, 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. 

As explained in the Phase 1 rule, NHTSA has broad discretion in balancing the above 

factors in determining the improvement that the manufacturers can achieve. The fact that the 

factors may often be conflicting gives NHTSA significant discretion to decide what weight to 

give each of the competing policies and concerns and then determine how to balance them—as 

long as NHTSA’s balancing does not undermine the fundamental purpose of the EISA: energy

conservation, and as long as that balancing reasonably accommodates ‘‘conflicting policies that 

were committed to the agency’s care by the statute.”798

EPA also has significant discretion in considering a range of stringency. Section 

202(a)(2) of the Clean Air Act requires only that the standards “take effect after 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.” This 

language affords EPA considerable discretion in how to weight the critical statutory factors of 

emission reductions, cost, and lead time. See 76 FR 57129-130.

As discussed in this Preamble’s Sections II (engines), III (tractors), IV (trailers), V 

(vocational vehicles), and VI (pickups and vans), although NHTSA and EPA are proposing 

Alternative 3 for each vehicle category, we have also closely examined the potential feasibility

 

798 Center for Biological Diversity v. National Highway Traffic Safety Admin., 538 F.3d 1172, 1194 (9th Cir. 2008). 

For further discussion see 76 FR 57198.
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Page 720 of 850

of Alternative 4 for each category, and specifically direct commenters’ attention to the analysis 

and discussions contained in those sections for both Alternatives 3 and 4. As discussed in those 

sections, if we reanalyze relevant existing information or receive relevant comments or new 

information between the proposal and final rule that supports a more accelerated implementation 

of the proposed standards, the agencies may consider establishing final fuel consumption and 

GHG standards at the Alternative 4 levels and timing if we deem them to be maximum feasible 

and reasonable for NHTSA and EPA, respectively. This Section X describes all of the

alternatives considered, and provides context for the relative stringency, costs, and benefits 

associated with Alternatives 3 and 4, as compared to the other alternatives. The agencies seek 

comment on all of the alternatives, as well as whether we should consider more, fewer or 

different alternatives for the final rule analysis.

A. What Are the Alternatives that the Agencies Considered?

The five alternatives below represent a broad range of potential stringency levels, and 

thus a broad range of associated technologies, costs and benefits for a HD vehicle fuel efficiency

and GHG emissions program. All of the alternatives were modeled using the same 

methodologies described in Chapter 5 of the draft RIA. The alternatives in order of increasing 

fuel efficiency and GHG emissions reductions are as follows:

(1) Alternative 1: No Action (the Baseline for Phase 2)

OMB guidance regarding regulatory analysis indicates that proper evaluation of the 

benefits and costs of regulations and their alternatives requires agencies to identify a baseline:

“You need to measure the benefits and costs of a rule against a baseline. This 

baseline should be the best assessment of the way the world would look absent the 

proposed action. The choice of an appropriate baseline may require 

consideration of a wide range of potential factors, including:

• evolution of the market,

• changes in external factors affecting expected benefits and costs,

• changes in regulations promulgated by the agency or other government entities, 

and

• the degree of compliance by regulated entities with other regulations.

It may be reasonable to forecast that the world absent the regulation will 

resemble the present. If this is the case, however, your baseline should reflect the 

future effect of current government programs and policies. For review of an 

existing regulation, a baseline assuming no change in the regulatory program 

generally provides an appropriate basis for evaluating regulatory alternatives.

When more than one baseline is reasonable and the choice of baseline will 

significantly affect estimated benefits and costs, you should consider measuring 

benefits and costs against alternative baselines. In doing so you can analyze the 
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Page 721 of 850

effects on benefits and costs of making different assumptions about other 

agencies’ regulations, or the degree of compliance with your own existing rules. 

In all cases, you must evaluate benefits and costs against the same baseline. You 

should also discuss the reasonableness of the baselines used in the sensitivity 

analyses. For each baseline you use, you should identify the key uncertainties in 

your forecast.”799

A no-action alternative is also required as a baseline against which to measure 

environmental impacts of the proposed standards and alternatives. NHTSA, as required by the 

National Environmental Policy Act, is documenting these estimated impacts in the draft EIS 

published with this NPRM.800

As discussed later in this section, the agencies are requesting comment on Alternative 1 

in order to ensure an appropriate analytical baseline (also termed ‘reference case’) for the Phase 

2 rulemaking. Alternative 1 is an analytical tool, but, as discussed below, no new standards 

beyond Phase 1 is not a potential outcome of the Phase 2 rulemaking, as that outcome would not 

meet the requirements of either EISA or the CAA.

The No Action Alternative for today’s analysis, alternatively referred to as the “baseline” 

or “reference case,” assumes that the agencies would not issue new rules regarding MD/HD fuel 

efficiency and GHG emissions. That is, this alternative assumes that the Phase 1 MD/HD fuel 

efficiency and GHG emissions program’s model year 2018 standards would be extended 

indefinitely and without change.

The agencies recognize that there are a number of factors that create uncertainty in 

projecting a baseline against which to compare the future effects of the proposed action and the 

remaining alternatives. The composition of the future fleet—such as the relative position of 

individual manufacturers and the mix of products they each offer—cannot be predicted with 

certainty at this time. As reflected, in part, by the market forecast underlying the agencies’ 

analysis, we anticipate that the baseline market for medium- and heavy-duty vehicles will 

continue to evolve within a competitive market that responds to a range of factors. Additionally, 

the heavy-duty vehicle market is diverse, as is the range of vehicle purchasers. 

Heavy-duty vehicle manufacturers have reported that their customers’ purchasing 

decisions are influenced by their customers’ own determinations of minimum total cost of 

 

799 OMB Circular A-4, September 17, 2003. Available at http://www.whitehouse.gov/omb/circulars_a004_a-4.

800 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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Page 722 of 850

ownership, which can be unique to a particular customer’s circumstances. For example, some 

customers (e.g., less-than-truckload or package delivery operators) operate their vehicles within a 

limited geographic region and typically own their own vehicle maintenance and repair centers 

within that region. These operators tend to own their vehicles for long time periods, and 

sometimes for the entire service life of the vehicle. Their total cost of ownership is influenced by 

their ability to better control their own maintenance costs, and thus they can afford to consider 

fuel efficiency technologies that have longer payback periods, outside of the vehicle 

manufacturer’s warranty period. Other customers (e.g. truckload or long-haul operators) tend to 

operate cross-country, and thus must depend upon truck dealer service centers for repair and 

maintenance. Some of these customers tend to own their vehicles for about four to seven years, 

so that they typically do not have to pay for repair and maintenance costs outside of either the 

manufacturer’s warranty period or some other extended warranty period. Many of these 

customers tend to require seeing evidence of fuel efficiency technology payback periods on the 

order of 18 to 24 months before seriously considering evaluating a new technology for potential 

adoption within their fleet (NAS 2010, Roeth et al. 2013, Klemick et al. 2014). Purchasing 

decisions, however, are not based exclusively on payback period, but also include the 

considerations discussed in this section. For the baseline analysis, the agencies use payback 

period as a proxy for all of these considerations, and therefore the payback period for the 

baseline analysis is shorter than the payback period industry uses as a threshold for the further 

consideration of a technology. 

Purchasers of HD pickups and vans wanting better fuel efficiency will demand that fuel 

consumption improvements pay back within approximately one to three years, but not all 

purchasers fall into this category. Some HD pickup and van owners accrue relatively few 

vehicle miles traveled per year, such that they may be less likely to adopt new fuel efficiency

technologies, while other owners who use their vehicle(s) with greater intensity may be even 

more willing to pay for fuel efficiency improvements. Regardless of the type of customer, their 

determination of minimum total cost of ownership involves the customer balancing their own 

unique circumstances with a heavy-duty vehicle’s initial purchase price, availability of credit and 

lease options, expectations of vehicle reliability, resale value and fuel efficiency technology

payback periods. The degree of the incentive to adopt additional fuel efficiency technologies also 

depends on customer expectations of future fuel prices, which directly impacts customer 

expectations of the payback period.

Another factor the agencies considered is that other federal and state-level policies and 

programs are specifically aimed at stimulating fuel efficiency technology development and 

deployment. Particularly relevant to this sector are DOE’s 21st Century Truck Partnership, 

EPA’s voluntary SmartWay Transport program, and California’s AB32 fleet 

requirements.801,802,803 The future availability of more cost-effective technologies to reduce fuel 

consumption could provide manufacturers an incentive to produce more fuel-efficient medium-

 

801 http://energy.gov/eere/vehicles/vehicle-technologies-office-21st-century-truck

802 http://www.epa.gov/smartway/

803 State of California Global Warming Solutions Act of 2006 (Assembly Bill 32, or AB32)
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and heavy-duty vehicles, which in turn could provide customers an incentive to purchase these 

vehicles. The availability of more cost-effective technologies to reduce fuel consumption could 

also lead to a substitution of less cost-effective technologies, where overall fuel efficiency could 

remain fairly flat if buyers are less interested in fuel consumption improvements than in reduced 

vehicle purchase prices and/or improved vehicle performance and/or utility.

Although we have estimated the cost and efficacy of fuel-saving technologies assuming 

performance and utility will be held constant, some uncertainty remains regarding whether these 

conditions will actually be observed. In particular, we have assumed payload will be preserved 

(and possibly improved via reduced vehicle curb weight); however, some fuel-saving 

technologies, such as natural gas fueled vehicles and hybrid electric vehicles, could reduce 

payload via increased curb weight due to the fuel tanks or added electrical machine, batteries and 

controls. It is also possible that under extended high power demand resulting from a vehicle 

towing up a road grade, certain types of hybrid powertrains could experience a temporary loss of 

towing capacity if the capacity of the hybrid’s energy storage device (e.g., batteries, hydraulic 

accumulator) is insufficient for the extended power demand. We have also assumed that fuelsaving technologies will be no more or less reliable than technologies already in production. 

However, if manufacturers pursue risky technologies or if the agencies provide insufficient leadtime to fully develop new technologies, they could prove to be less reliable, perhaps leading to 

increased repair costs and out-of-service time. This was observed as an unintended consequence 

of certain manufacturers’ initial introduction of certain emissions control technologies to meet 

EPA’s most stringent heavy-duty engine standards. If the fuel-saving technologies considered 

here ultimately involve similar reliability problems, overall costs will be greater than we have 

estimated. We have assumed drivers will be as accepting of new fuel-saving technologies as 

they are of technologies already in service. However, drivers could be less accepting of newer 

technologies -- particularly any that must be deployed manually. Except for increased costs to 

replace more efficient tires, we have assumed that routine maintenance costs will not increase or 

decrease. However, maintenance of new technologies could involve unique tools and parts. 

Therefore, maintenance costs could increase, and maintenance could involve increased vehicle 

out-of-service time. On the other hand new technologies can sometimes prove to be more 

reliable and require less maintenance than the technologies they replace. One example of this is 

the auxiliary power unit (APU) frequently installed on heavy-duty sleeper cab tractors. In the 

past these have been typically powered by small nonroad diesel engines that can require more 

frequent maintenance than the main engine of the tractor itself. However, more recently, as 

electric battery technology has advanced, some tractor manufacturers have introduced battery

APUs instead of engine-driven APUs. A comparison of recent sales of small engine driven 

APUs versus battery APUs suggests that customers may prefer battery APUs804, and some 

operators and tractor dealerships have also told the agencies that the decrease in routine 

maintenance was an important factor in purchase decisions in favor of battery APUs. Again, 

insofar as these unaccounted-for costs or savings actually occur, overall costs could be larger or 

smaller than we have estimated. We have also applied the EIA’s AEO estimates of future fuel 

 

804 Confidence Report: Idle-Reduction Solutions, North American Council for Freight Efficiency, Lee, Tessa, 2014, 

p. 13.
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prices; however, heavy-duty vehicle customers could have different expectations about future

fuel prices, and could therefore be more inclined or less inclined to apply new technology to 

reduce fuel consumption than might be expected based on EIA’s forecast. We expect that 

vehicle customers will be uncertain about future fuel prices, and that this uncertainty will be 

reflected in the degree of enthusiasm to apply new technology to reduce fuel consumption.

Considering all of these factors, the agencies have approached the definition of the No 

Action Alternative separately for each vehicle and engine category covered by today’s proposal.

For trailers, the agencies considered two No Action alternatives to cover a nominal range 

of uncertainty. The trailer category is unique in the context of this rulemaking because it is the 

only heavy-duty category not regulated under Phase 1. In both No Action cases, the agencies 

projected that the combination of EPA’s voluntary SmartWay program, DOE’s 21st Century

Truck Partnership, California’s AB32 trailer requirements for fleets, and the potential for 

significantly reduced operating costs should result in continuing improvement to new trailers. 

Taking this into account, the agencies project that in 2018, 50 percent of new 53’ dry van and 

reefer trailers would have technologies qualifying for the SmartWay label (5 percent 

aerodynamic improvements and lower rolling resistance tires) and 50 percent would have 

automatic tire inflation systems to maintain optimal tire pressure. We also project that adoption 

of those same technologies would increase 1 percent per year until each technology is being used 

on 60 percent of new trailers. In the first case, Alternative 1a, this means that the agencies 

project that in the absence of new standards, the new trailer fleet technology would stabilize in 

2027 to a level of 60 percent adoption in 2027 for the No Action alternative. In the second case, 

Alternative 1b, the agencies projected that the fraction of the in-use fleet qualifying for 

SmartWay would continue to increase beyond 2027 as older trailers are replaced by newer 

trailers. We projected that these improvements would continue until 2040 when 75 percent of 

new trailers would be assumed to include skirts.

For vocational vehicles, the agencies considered one No Action alternative. For the 

vocational vehicle category the agencies recognized that these vehicles tend to operate over 

fewer vehicle miles travelled per year. Therefore, the projected payback periods for fuel 

efficiency technologies available for vocational vehicles are generally longer than the payback 

periods the agencies consider likely to lead to their adoption based solely on market forces. This 

is especially true for vehicles used in applications in which the vehicle operation is secondary to 

the primary business of the company using the vehicle. For example, since the fuel consumption 

of vehicles used by utility companies to repair power lines would generally be a smaller cost 

relative to the other costs of repairing lines, fuel saving technologies would generally not be as 

strongly demanded for such vehicles. Thus, the agencies project that fuel-saving technologies 

would either not be applied or only be applied as a substitute for more expensive fuel efficiency

technologies, except as necessitated by the Phase 1 fuel consumption and GHG standards. 

For tractors, the agencies considered two No Action alternatives to cover a nominal range 

of uncertainty. For Alternative 1a the agencies project that fuel-saving technologies would either 

not be applied or only be applied as a substitute for more expensive fuel efficiency technologies 

to tractors (thereby enabling manufacturers to offer tractors that are less expensive to purchase), 

except as necessitated by the Phase 1 fuel consumption and GHG standards. In Alternative 1b 

the agencies estimated that some available technologies would save enough fuel to pay back 
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fairly quickly – within the first six months of ownership. The agencies considered a range of 

information to formulate these two baselines for tractors.

Both public805 and confidential historical information shows that tractor trailer fuel 

efficiency improved steadily through improvements in engine efficiency and vehicle 

aerodynamics over the past 40 years, except for engine efficiency which decreased or was flat 

between 2000 and approximately 2007 as a consequence of incorporating technologies to meet 

engine emission regulations. Today vehicle manufacturers, the Federal Government, academia 

and others continue to invest in research to develop fuel efficiency improving technologies for 

the future.

There is also evidence that manufacturers have, in the past, applied technologies to 

improve fuel efficiency absent a regulatory requirement to do so. Some manufacturers have 

even taken regulatory risk in order to increase fuel efficiency; in the 1990s, when fuel was 

comparatively inexpensive, some tractor manufacturers designed tractor engine controls to 

determine when the vehicle was not being emissions tested and, under such conditions, shift to 

more fuel-efficient operation even though doing so caused the vehicles to violate federal 

standards for NOx emissions. Also, some manufacturers have recently expressed concern that 

the Phase 1 tractor standards do not credit them for fuel-saving technologies they had already

implemented before the Phase 1 standards were adopted.

In public meetings and in meetings with the agencies, the trucking industry stated that 

fuel cost for tractors is the number one or number two expense for many operators, and therefore 

is a very important factor for their business. However, the pre-Phase 1 market suggests that, 

tractor manufacturers and operators could be slow to adopt some new technologies, even where 

the agencies have estimated that the technology would have paid for itself within a few months 

of operation. Tractor operators have told the agencies they generally require technologies to be 

demonstrated in their fleet before widespread adoption so they can assess the actual fuel savings 

for their fleet and any increase in cost associated with effects on vehicle operation, maintenance, 

reliability, mechanic training, maintenance and repair equipment, stocking unique parts and 

driver acceptance, as well as effects on vehicle resale value. Tractor operators have publicly 

stated they would consider conducting an assessment of technologies when provided with data 

that show the technologies may payback costs through fuel savings within 18 to 24 months, 

based on their assumptions about future fuel costs. In these cases, an operator may first conduct 

a detailed paper study of anticipated costs and benefits. If that study shows likely payback in 18 

to 24 months for their business, the fleet may acquire one or several tractors with the technology

to directly measure fuel savings, costs and driver acceptance for their fleet. Small fleets may not 

have resources to conduct assessments to this degree and may rely on information from larger 

fleets or observations of widespread acceptance of the technology within the industry before 

 

805 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 2010”). 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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adopting a technology. This uncertainty over the actual fuel savings and costs and the lengthy 

process to assess technologies significantly slows the pace at which fuel efficiency technologies 

are adopted. 

The agencies believe that using the two baselines addresses the uncertainties we have 

identified for tractors. The six-month payback period of Alternative 1b reflects the agencies’ 

consideration of factors, discussed above, that could limit—yet not eliminate—manufacturers’ 

tendencies to voluntarily improve fuel consumption. In contrast, Alternative 1a reflects a 

baseline for vehicles other than trailers wherein manufacturers either do not apply fuel efficiency

technologies or only apply them as a substitute for more expensive fuel efficiency technologies, 

except as necessitated by the Phase 1 fuel consumption and GHG standards.

For HD pickups and vans, the agencies considered two No Action alternatives to cover a 

nominal range of uncertainty. In Alternative 1b the agencies considered additional technology

application, which involved the explicit estimation of the potential to add specific fuel-saving 

technologies to each specific vehicle model included in the agencies’ HD pickup and van fleet 

analysis, as discussed in Chapter VI. Estimated technology application and corresponding 

impacts depend on the modeled inputs. Also, under this approach a manufacturer that has 

improved fuel consumption and GHG emissions enough to achieve compliance with the 

standards is assumed to apply further improvements, provided those improvements reduce fuel 

outlays by enough (within a specified amount of time, the payback period) to offset the 

additional costs to purchase the new vehicle. These calculations explicitly account for and 

respond to fuel prices, vehicle survival and mileage accumulation, and the cost and efficacy of 

available fuel-saving technologies. Therefore, all else being equal, more technology is applied 

when fuel prices are higher and/or technology is more cost-effective. Manufacturers of HD 

pickups and vans have reported to the agencies that buyers of these vehicles consider the total 

cost of vehicle ownership, not just new vehicle price, and that manufacturers plan as if buyers 

will expect fuel consumption improvements to “pay back” within periods ranging from 

approximately one to three years. For example, some manufacturers made decisions to introduce 

more efficient HD vans and HD pickup transmissions before such vehicles were subject to fuel 

consumption and/or GHG standards. However, considering factors discussed above that could 

limit manufacturers’ tendency to voluntarily improve HD pickup and van fuel consumption, 

Alternative 1b applies a 6-month payback period. In contrast for Alternative 1a the agencies 

project that fuel-saving technologies would either not be applied or only be applied as a 

substitute for more expensive fuel efficiency technologies, except as necessitated by the Phase 1 

fuel consumption and GHG standards. The Method A sensitivity analysis presented above in 

Section VI also examines other payback periods. In terms of impacts under reference case fuel 

prices, the payback period input plays a more significant role under the No-Action Alternatives 

(defined by a continuation of model year 2018 standards) than under the more stringent 

regulatory alternatives described next.

(2) Alternative 2: Less Stringent than the Preferred Alternative

For vocational vehicles and combination tractor-trailers, Alternative 2 represents a 

stringency level which is approximately half as stringent overall as the preferred alternative. The 

agencies developed Alternative 2 to consider a continuation of the Phase 1 approach of applying 

off-the-shelf technologies rather than requiring the development of new technologies or 
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fundamental improvements to existing technologies. For tractors and vocational vehicles, this 

also involved less integrated optimization of the vehicles and engines. Put another way, 

Alternative 2 is not technology-forcing. See, e.g., Sierra Club v. EPA, 325 F. 3d 374, 378 (D.C. 

Cir. 2003) (under a technology-forcing provision, EPA “must consider future advances in 

pollution control capability”); see also similar discussion in Husqvarna AB v. EPA, 254 F. 3d 

195, 201 (D.C. Cir. 2001).

The agencies’ decisions regarding which technologies could be applied to comply with 

Alternative 2 considered not only the use of off-the shelf technologies, but also considered other 

factors as well, such as how broadly certain technologies fit in-use applications and regulatory

structure. The resulting Alternative 2 could be met with most of the same technologies the 

agencies project could be used to meet the proposed standards, although at lower application 

rates. Alternative 2 is estimated to be achievable without the application of some technologies, 

at any level. These and other differences are described below by category.

The agencies project that Alternative 2 combination tractor standards could be met by

applying lower adoption rates of the projected technologies for Alternative 3. This includes a 

projection of slightly lower per-technology effectiveness for Alternative 2 versus 3. Alternative 

2 also assumes that there would be little optimization of combination tractor powertrains. 

The agencies project that the Alternative 2 vocational vehicle standard could be met 

without any use of strong hybrids. Rather, it could be met with lower adoption rates of the other 

technologies that could be used to meet Alternative 3, our proposed standards. This includes a 

projection of slightly lower per-technology effectiveness for Alternative 2 versus 3 and little 

optimization of vocational vehicle powertrains. 

The Alternative 2 trailer standards would apply to only 53-foot dry and refrigerated box 

trailers and could be met through the use of less effective aerodynamic technologies and higher 

rolling resistance tires versus what the agencies projected could be used to meet Alternative 3.

As discussed above in Section VI.D., the HD pickup truck and van alternatives are 

characterized by an annual required percentage change (decrease) in the functions defining 

attribute-based targets for per-mile fuel consumption and GHG emissions. Under the standards 

in each alternative, a manufacturer’s fleet would, setting aside any changes in production mix, be 

required to achieve average fuel consumption/GHG levels that increase in stringency every year 

relative to the standard defined for MY2018 (and held constant through 2020) that establishes 

fuel consumption/GHG targets for individual vehicles. A manufacturer’s specific fuel 

consumption/GHG requirement is the sales-weighted average of the targets defined by the workfactor curve in each year. Therefore, although the alternatives involve steady increases in the 

functions defining the targets, stringency increases faced by any individual manufacturer may 

not be steady if changes in the manufacturer’s product mix cause fluctuations in the average fuel 

consumption and GHG levels required of the manufacturer. See Section VI.D. for additional 

discussion of this topic. Alternative 2 represents a 2.0 percent annual improvement through 2025 

in fuel consumption/GHG emissions relative to the work-factor curve in 2020. This would be 

0.5 percent less stringent per year compared to the proposed standards of Alternative 3. 
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For HD pickups and vans the agencies project that most manufacturers could comply

with the standards defining Alternative 2 by applying technologies similar to those that could be 

applied in order to comply with the proposed standards, but at lower application rates than could 

be necessitated by the proposed standards. The biggest technology difference the agencies 

project between Alternative 2 and the proposed standards of Alternative 3 would be that we 

project that most manufacturers could meet the Alternative 2 standards without any use of stopstart or other mild or strong hybrid technologies.

Of course, these estimates depend not only on the stringency of the standards defining

this regulatory alternative, but also on other input estimates, in particular the detailed 

composition of the agencies’ HD pickup and van market forecast; the agencies’ estimates of the 

future availability, cost, and efficacy of fuel-saving HD pickup and van technologies; and the 

agencies’ estimates of future fuel prices. Even without changes to the standards defining this 

regulatory alternative, changes to analysis inputs would lead to different estimates of the extent 

to which various technologies might be applied under this regulatory alternative.

The agencies are not proposing Alternative 2 as a matter of both policy and law. Based 

on our current analysis for each of the subcategories, it presently appears that technically feasible 

alternate standards are available that provide for greater emission reductions and reduced fuel 

consumption, including the proposed standards. Such alternative standards, including the 

proposed standards and potentially Alternative 4, are feasible at reasonable cost, considering 

both per-vehicle and per-engine cost, cost-effectiveness, and lead time. Consequently, at this 

point the agencies do not believe that the modest improvements in Alternative 2 would be 

appropriate or otherwise reasonable under Section 202 (a) (1) and (2) of the Clean Air Act, or 

represent the “maximum feasible improvement” within the meaning of 49 U.S.C. Section 

32902(k)(2). 

(3) Alternative 3: Preferred Alternative and Proposed Standards

The agencies are proposing Alternative 3 for HD engines, HD pickup trucks and vans, 

Class 2b through Class 8 vocational vehicles, Class 7 and 8 combination tractors, and most

categories of trailers. Details regarding modeling of this alternative are included in Chapter 5 of 

the draft RIA. 

Unlike the Phase 1 standards where the agencies projected that manufacturers could meet 

the Phase 1 standards with off-the-shelf technologies only, the agencies project that Alternative 3 

standards could be met through a combination of off-the-shelf technologies applied at higher 

market penetration rates and new technologies that are still in various stages of development and 

not yet in production. Although this alternative is technology-forcing, it must be kept in mind 

that the standards themselves are performance-based and thus do not mandate any particular 

technology be used to meet the standards. The agencies recognize that there is some uncertainty 

in projecting costs and effectiveness for those technologies not yet available on the market, but 

we do not believe, as discussed comprehensively in Sections II, III, IV, V, and VI, that such 

uncertainty is not sufficient to render Alternative 3 beyond the reasonable or maximum feasible 

level of stringency for each of the vehicle categories covered by this program. Given that all of 

the proposed standards are performance-based rather than mandates of specific technologies, and 

given that the lead time for the most stringent standards in Alternative 3 is greater than 10 years, 
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the agencies believe that the performance that would be required by these stringency levels of 

Alternative 3 would allow each manufacturer to choose to develop technology and apply it to 

their vehicles in a way that balances their unique business constraints and reflects their specific 

market position and customers’ needs.

We have described in detail above, and also in Chapter 2 of the draft RIA, the precise 

bases for each of the proposed standards (that is, for each segment covered under the program).

For HD pickups and vans, Alternative 3 represents a 2.5 percent compounded annual 

improvement through 2027 in fuel consumption/GHG emissions relative to the work-factor 

curve in 2020. 

Sections II through VI of this notice provide comprehensive explanations of the 

consideration that the agencies gave to proposing standards that are more accelerated than 

Alternative 3, based on the agencies’ projection of how such standards could be met through the 

accelerated application of technologies and our reasons for concluding that the identified 

technologies for each of the vehicle and engine standards that constitute Alternative 3 represent 

the maximum feasible (within the meaning of 49 USC 32902 (k)) and reasonable (for purposes 

of CAA section 202 (a)) based on all of the information available to the agencies at the time of 

this proposal. 

(4) Alternative 4: More Accelerated than the Preferred Alternative

As indicated by its description in the title above, Alternative 4 represents standards that 

are effective on a more accelerated timeline in comparison to the timeline of the proposed 

standards in Alternative 3. The agencies believe that Alternative 4 could potentially be 

maximum feasible and appropriate, but at this time the agencies have identified sufficient 

uncertainty in the information that the agencies have considered with respect to the technologies’ 

readiness, effectiveness and costs such that the agencies cannot yet conclude that Alternative 4 

represents maximum feasible and appropriate standards. Accordingly, although we are not 

proposing Alternative 4, we are requesting comment on adopting some or all of Alternative 4 in 

the final rule. The agencies would especially welcome data on the projected readiness, 

effectiveness, and costs of technologies the agencies consider for compliance with Alternative 4 

standards, which in many cases are identical to the technologies considered for the Alternative 3 

standards. It would be especially helpful if commenters addressed each category separately;

namely, tractors and vocational vehicles and their engines; trailers, and pickups and vans. The 

agencies would consider adopting Alternative 4’s stringencies and lead time for the final rule, 

depending on the information and comments received in response to this notice and based on 

additional consideration of the information we already have in-hand.

Alternatives 3 and 4 were both designed to achieve similar fuel efficiency and GHG 

emission levels in the long term but with Alternative 4 being accelerated in its implementation 

timeline. Specifically, alternative 4 reflects the same or similar standard stringency levels as 

alternative 3, but 3 years sooner (2 years for heavy-duty pickups and vans), so that the final 

phase of the standards would occur in MY 2024, or (for heavy duty pickups and vans) 2025.

As discussed above and in the feasibility discussions in Sections II-VI, we are not 

proposing Alternative 4. By accelerating the adoption schedule, this option would result in 
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several model years of incrementally greater fuel consumption and GHG emission reductions 

than Alternative 3, but it does raise concerns about adequacy of lead time. The agencies have 

outstanding questions regarding relative risks and benefits of Alternative 4 due to the timeframe 

envisioned by that alternative. 

The agencies recognize the potential for larger net benefits if Alternative 4 were selected, 

and we therefore welcome comments addressing the feasibility and availability of relevant 

technologies in the identified lead time. Commenters are particularly encouraged to address all 

aspects of feasibility analysis, including effectiveness and costs, the likelihood of developing 

available technologies to achieve sufficient reliability within the proposed lead time, and the 

extent to which the heavy-duty vehicle market would accept and utilize the technology. 

Comments should ideally address these issues separately for each type of technology, especially 

with respect to advanced technologies like waste heat recovery systems and hybrid powertrains. 

Although we summarize the specific differences below, readers are encouraged to see Sections II 

through VI for more detailed descriptions of how the agencies projected how manufacturers 

could implement certain technologies in order to meet the standards of Alternative 4. 

The agencies project that Alternative 4 combination tractor standards could be met by

applying initially higher adoption rates of the projected technologies for Alternative 3. This 

includes a projection of slightly higher per-technology effectiveness for Alternative 4 versus 3. 

Alternative 4 also assumes that there would be more optimization of combination tractor 

powertrains and earlier market penetration of engine waste heat recovery systems. 

The agencies project that the Alternative 4 vocational vehicle standard could be met 

through earlier adoption rates of the same technology packages projected for Alternative 3. This 

includes a projection of slightly higher per-technology effectiveness for Alternative 4 versus 3. 

The Alternative 4 trailer standards could be met through earlier implementation of more 

effective aerodynamic technologies, including the use of aerodynamic skirts and boat tails. This 

would be in addition to implementing lower rolling resistance tires for nearly all trailers. 

HD pickup truck and van standards defining Alternative 4 represent a 3.5 percent annual 

improvement in fuel consumption and GHG emissions through 2025 relative to the work-factor 

curves in 2020. Of course, this finding depends not only on the stringency of the standards 

defining this regulatory alternative, but also on other input estimates, in particular the detailed 

composition of the agencies’ HD pickup and van market forecast; the agencies’ estimates of the 

future availability, cost, and efficacy of fuel-saving HD pickup and van technologies; and the 

agencies’ estimates of future fuel prices. Even without changes to the standards defining this 

regulatory alternative, changes to analysis inputs will lead to different estimates of the extent to

which various technologies might be applied under this regulatory alternative.

(5) Alternative 5: Even More Stringent Standards with No Additional Lead-time 

Alternative 5 represents even more stringent standards compared to Alternatives 3 and 4, 

as well as the same implementation timeline as Alternative 4. As discussed above and in the 

feasibility discussions in Sections II-VI, we are not proposing Alternative 5 because we cannot 

project that manufacturers can develop and introduce in sufficient quantities the technologies that 
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could be used to meet Alternative 5 standards. We believe that for some or all of the categories, 

the Alternative 5 standards are technically infeasible within the lead time allowed. We have not 

fully estimated costs for this alternative for tractors and vocational vehicles because we believe 

that there would be such substantial additional costs related to pulling ahead the development of 

so many additional technologies that we cannot accurately predict these costs. We also believe 

this alternative could result in a decrease in the in-use reliability and durability of new heavyduty vehicles and that we do not have the ability to accurately quantify the costs that would be 

associated with such problems. Instead we merely note that costs would be significantly greater 

than the estimated costs for Alternatives 3 and 4.

B. How Do These Alternatives Compare in Overall Fuel Consumption and 

GHG Emissions Reductions and in Benefits and Costs?

The following tables compare the overall fuel consumption and GHG emissions 

reductions and benefits and costs of each of the regulatory alternatives the agencies considered.

Note that for tractors, trailers, pickups and vans the agencies compared overall fuel 

consumption and GHG emissions reductions and benefits and costs relative to two different 

baselines, described above in the section on the No Action alternative. Therefore, for tractors, 

trailers, pickups and vans two results are listed; one relative to each baseline, namely Alternative 

1a and Alternative 1b.

Also note that the agencies analyzed pickup and van overall fuel consumption and 

emissions reductions and benefits and costs using the NHTSA's CAFE model (Method A). In 

addition, the agencies used EPA’s MOVES model to estimate pickup and van fuel consumption 

and emissions and a cost methodology that applied vehicle costs in different model years 

(Method B). In both cases, the agencies used the CAFE model to estimate average per vehicle 

cost, and this analysis extended through model year 2030.806 The agencies concluded that in 

these instances the choice of baseline and the choice of modeling approach (Method A versus 

Method B) did not impact the agencies’ decision to propose Alternative 3 as the preferred 

alternative and hence the proposed standards for HD pickups and vans.

Table X-1 compares fuel savings, technology costs, avoided emissions, total costs, and 

benefits for the above regulatory alternatives as estimated under Method A. 

Table X-2 provides the same comparisons for Method B. Subsequent tables summarize 

segment-specific results and projections for longer-term impacts. The regulatory impact analysis 

(RIA) accompanying today’s notice presents more detailed results of the agencies’ analysis.

 

806 Although the agencies have considered regulatory alternatives involving standards increasing in stringency 

through, at the latest, 2027, the agencies extended the CAFE modeling analysis through model year 2030 rather than 

model year 2027 in order to obtain more fully stabilized results given projected product cadence, multiyear 

planning, and application of earned credits.
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(1) Method A Tables

Table X-1 Summary of Costs And Benefits through MY 2029 by Alternative, Discounted at 3% (Relative to 

Baseline 1a), Method A

a

Vehicle segment Alt 2 Alt 3 Alt 4 Alt 5

Discounted pre-tax fuel savings ($billion)

HD pickups and Vans 11.7 18.3 22.3 24.8

Vocational Vehicles 5.6 18.4 24.3 38.5

Tractors/Trailers 88.1 138.4 151.7 196.8

Total 105.4 175.1 198.3 260.2

Discounted Total technology costs ($billion)

HD pickups and Vans 3.0 5.0 8.2 9.9

Vocational Vehicles 1.2 7.6 10.8 26.0

Tractors/Trailers 9.2 12.8 15.3 34.8

Total 13.4 25.4 34.3 70.6

Discounted value of emissions reductions ($billon)

HD pickups and Vans 3.0 4.8 5.9 6.6

Vocational Vehicles 1.7 6.1 8.1 13.1

Tractors/Trailers 40.7 62.7 67.9 87.7

Total 45.4 73.7 82.0 107.4

Total costs($billion)

HD pickups and Vans 3.5 5.7 9.1 15.2

Vocational Vehicles 3.0 9.5 12.8 28.1

Tractors/Trailers 11.5 15.5 18.1 37.5

Total 18.0 30.8 40.0 80.8

Total benefits($billion)

HD pickups and Vans 17.2 27.0 33.0 36.7

Vocational Vehicles 12.7 31.2 39.7 60.2

Tractors/Trailers 142.5 217.5 236.7 304.2

Total 172.4 275.8 309.4 401.1

Net benefits($billion)

HD pickups and Vans 13.7 21.3 23.9 21.5

Vocational Vehicles 9.6 21.7 26.9 32.1

Tractors/Trailers 131.0 202.0 218.7 266.7

Total 154.3 245.0 269.4 320.3

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an 

explanation of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see 

Section X.A.1.
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Table X-2 Summary of Program Benefits and Costs through MY 2029, Discounted at 3% (Relative to 

Baseline 1b), Method Aa

Vehicle segment Alt 2 Alt 3 Alt 4 Alt 5

Discounted pre-tax fuel savings ($billion)

HD pickups and Vans 9.6 15.9 19.1 22.2

Vocational Vehicles 5.6 18.4 24.3 38.5

Tractors/Trailers 80.5 130.8 144.0 189.2

Total 95.6 165.1 187.4 250.0

Discounted Total technology costs ($billion)

HD pickups and Vans 2.5 5.0 7.2 9.7

Vocational Vehicles 1.2 7.6 10.8 25.9

Tractors/Trailers 8.9 12.5 15.0 34.4

Total 12.5 25.0 32.9 70.0

Discounted value of emissions reductions ($billon)

HD pickups and Vans 2.8 4.5 5.4 6.3

Vocational Vehicles 1.7 6.1 8.1 13.1

Tractors/Trailers 37.5 59.4 64.6 84.4

Total 41.9 70.1 78.2 103.8

Total costs($billion)

HD pickups and Vans 2.8 5.5 7.8 10.4

Vocational Vehicles 3.0 9.5 12.8 28.0

Tractors/Trailers 11.2 15.2 17.7 37.2

Total 17.0 30.3 38.4 75.7

Total benefits($billion)

HD pickups and Vans 14.1 23.5 28.3 32.9

Vocational Vehicles 12.7 31.2 39.7 60.2

Tractors/Trailers 131.1 206.2 225.4 292.8

Total 157.9 260.9 293.3 385.9

Net benefits($billion)

HD pickups and Vans 11.3 18.0 20.4 22.5

Vocational Vehicles 9.6 21.7 26.9 32.1

Tractors/Trailers 119.9 191.0 207.6 255.6

Total 140.9 230.7 254.9 310.3

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an 

explanation of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see 

Section X.A.1.

The following two tables summarize results for each of the segments covered by today’s 

proposal, discounted at 7 percent.
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Table X-3 Summary of Program Benefits and Costs through MY 2029, discounted at 7% (Relative to 

Baseline 1a), Method A a

Vehicle segment Alt 2 Alt 3 Alt 4 Alt 5

Discounted pre-tax fuel savings ($billion)

HD pickups and Vans 6.4 9.9 12.2 13.6

Vocational Vehicles 2.9 9.7 13.0 20.9

Tractors/Trailers 47.7 74.6 82.3 107.3

Total 57.0 94.2 107.5 141.8

Discounted Total technology costs ($billion)

HD pickups and Vans 2.1 3.4 5.7 6.9

Vocational Vehicles 0.8 5.0 7.3 17.8

Tractors/Trailers 6.3 8.7 10.5 23.9

Total 9.1 17.1 23.5 48.6

Discounted value of emissions reductions ($billon)

HD pickups and Vans 2.7 4.3 5.3 5.9

Vocational Vehicles 1.4 5.0 6.6 10.6

Tractors/Trailers 29.9 46.3 50.4 65.4

Total 34.0 55.6 62.3 81.8

Total costs($billion)

HD pickups and Vans 2.4 3.8 6.2 10.1

Vocational Vehicles 1.8 6.1 8.4 19.0

Tractors/Trailers 7.6 10.3 12.1 25.5

Total 11.8 20.2 26.7 54.6

Total benefits($billion)

HD pickups and Vans 10.4 16.3 20.1 22.3

Vocational Vehicles 7.3 18.3 23.6 36.2

Tractors/Trailers 85.1 130.0 142.2 183.5

Total 102.9 164.6 185.8 242.1

Net benefits($billion)

HD pickups and Vans 8.1 12.4 13.9 12.2

Vocational Vehicles 5.5 12.2 15.2 17.2

Tractors/Trailers 77.5 119.7 130.1 158.0

Total 91.1 144.4 159.1 187.5

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an 

explanation of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see 

Section X.A.1.
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Table X-4 Summary of Program Benefits and Costs through MY 2029, discounted at 7% (Relative to

Baseline 1b), Method A a

Vehicle segment Alt 2 Alt 3 Alt 4 Alt 5

Discounted pre-tax fuel savings ($billion)

HD pickups and Vans 5.2 8.5 10.4 12.2

Vocational Vehicles 2.9 9.7 13.0 20.9

Tractors/Trailers 44.0 71.0 78.6 103.7

Total 52.2 89.2 102.0 136.8

Discounted Total technology costs ($billion)

HD pickups and Vans 1.7 3.4 4.9 6.7

Vocational Vehicles 0.8 5.0 7.3 17.8

Tractors/Trailers 6.0 8.4 10.3 23.7

Total 8.5 16.8 22.5 48.2

Discounted value of emissions reductions ($billon)

HD pickups and Vans 2.5 4.0 4.8 5.5

Vocational Vehicles 1.4 5.0 6.6 10.6

Tractors/Trailers 27.5 43.9 48.0 63.0

Total 31.4 52.9 59.4 79.1

Total costs($billion)

HD pickups and Vans 1.9 3.7 5.3 7.1

Vocational Vehicles 1.8 6.1 8.4 19.0

Tractors/Trailers 7.3 10.0 11.9 25.3

Total 11.1 19.8 25.6 51.4

Total benefits($billion)

HD pickups and Vans 8.6 14.1 17.1 20.0

Vocational Vehicles 7.3 18.3 23.6 36.2

Tractors/Trailers 78.9 123.7 135.9 177.3

Total 94.8 156.2 176.6 233.5

Net benefits($billion)

HD pickups and Vans 6.7 10.5 11.9 12.9

Vocational Vehicles 5.5 12.2 15.2 17.2

Tractors/Trailers 71.5 113.7 124.0 152.0

Total 83.7 136.4 151.1 182.2

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an 

explanation of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see 

Section X.A.1.
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While the agencies’ explicit analysis of manufacturers’ potential responses to today’s

proposed standards extends through model year 2030, the resulting fuel savings and avoided 

emissions summarized in the following two tables occur as those vehicles .

Table X-5 Fuel Savings and GHG Emissions Reductions by Vehicle Segment, Relative to Baseline 1a, Method 

A

a

MY 2018 - 2029 Total Fuel 

Reductions

Upstream & 

Downstream 

GHG 

reductions

(billion 

gallons)

(MMT)

Alternative 2

HD Pickup 

Trucks/Vans 

5.5 67.5

Vocational Vehicles 2.5 33.6

Tractors and Trailers 37.8 518.8

Total 45.8 619.9

Alt. 3 - Preferred Alternative

HD Pickup 

Trucks/Vans 

8.8 107.6

Vocational Vehicles 8.3 110.3

Tractors and Trailers 59.5 816.4

Total 76.7 1,034.3

Alt. 4

HD Pickup 

Trucks/Vans 

10.7 130.5

Vocational Vehicles 10.9 143.8

Tractors and Trailers 65.0 892.1

Total 86.7 1,166.4

Alt. 5

HD Pickup 

Trucks/Vans 

12.0 145.4

Vocational Vehicles 17.3 226.9

Tractors and Trailers 84.2 1,155.1

Total 113.4 1,527.4

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an 

explanation of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see 

Section X.A.1.

Table X-6 Fuel Savings and GHG Emissions Reductions by Vehicle Segment, Relative to Baseline 1b, Method 

A

a
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MY 2018 - 2029 Total Fuel 

Reductions

Upstream & 

Downstream 

GHG 

reductions

(billion 

gallons)

(MMT)

Alternative 2

HD Pickup Trucks/Vans 4.5 55.5

Vocational Vehicles 2.5 33.6

Tractors and Trailers 34.4 471.9

Total 41.4 561.0

Alt. 3 - Preferred Alternative

HD Pickup Trucks/Vans 7.8 94.1

Vocational Vehicles 8.3 110.3

Tractors and Trailers 56.1 769.4

Total 72.2 973.8

Alt. 4

HD Pickup Trucks/Vans 9.3 112.8

Vocational Vehicles 10.9 143.8

Tractors and Trailers 61.6 845.2

Total 81.8 1,101.8

Alt. 5

HD Pickup Trucks/Vans 10.8 130.5

Vocational Vehicles 17.3 226.9

Tractors and Trailers 80.7 1,108.2

Total 108.8 1,465.6

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an 

explanation of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see 

Section X.A.1.

Results presented above are cumulative, spanning model years 2018-2029. Underlying 

these results are estimates of impacts for each specific model year. As an example, Table X-7

shows costs, benefits, and net benefits specific to model year 2029.

Table X-7 Summary of Costs And Benefits for MY 2029 by Alternative, Discounted at 3% (Relative to 

Baseline 1b), Method Aa
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Vehicle segment Alt 2 Alt 3 Alt 4 Alt 5

Total Costs ($billion)

HD pickups and Vans 0.3 0.8 0.9 1.1

Vocational Vehicles 0.3 1.5 1.5 2.9

Tractors/Trailers 1.2 1.9 1.9 3.9

Total 1.9 4.1 4.3 7.9

Total Benefits ($billion)

HD pickups and Vans 1.9 3.6 3.8 4.2

Vocational Vehicles 1.8 5.2 5.2 7.3

Tractors/Trailers 14.4 25.4 25.4 32.0

Total 18.0 34.1 34.4 43.6

Net Benefits ($billon)

HD pickups and Vans 1.5 2.8 2.9 3.1

Vocational Vehicles 1.4 3.7 3.7 4.4

Tractors/Trailers 13.2 23.5 23.5 28.1

Total 16.1 30.0 30.1 35.6

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an 

explanation of the less dynamic baseline, 1a, and more dynamic baseline, 1b, please see 

Section X.A.1.
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(2) Method B Tables

Table X-8 Annual GHG and Fuel Reductions in 2035 and 2050 using Method B and Relative to the 

Less Dynamic Baseline a

UPSTREAM & 

DOWNSTREAM GHG 

REDUCTIONS

(MMT)

FUEL REDUCTIONS

(BILLION GALLONS)

2035 2050 2035 2050

Alt. 2 Less Stringent - Total 72 101 5.2 7.3

Tractors and Trailers 59 84 4.2 6.0

HD Pickup Trucks 8 11 0.7 0.9

Vocational Vehicles 5 7 0.3 0.5

Alt. 3 Preferred – Total 127 183 9.3 13.4

Tractors and Trailers 97 141 7.0 10.1

HD Pickup Trucks 14 19 1.1 1.6

Vocational Vehicles 16 23 1.2 1.7

Alt. 4 More Stringent – Total 132 184 9.7 13.5

Tractors and Trailers 100 141 7.2 10.1

HD Pickup Trucks 15 19 1.2 1.6

Vocational Vehicles 17 23 1.3 1.7

Alt. 5 More Stringent – Total 168 232 12.4 17.0

Tractors and Trailers 126 176 9.0 12.6

HD Pickup Trucks 17 22 1.4 1.8

Vocational Vehicles 26 34 1.9 2.5

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an explanation of the less 

dynamic baseline, 1a, and more dynamic baseline, 1b, please see Section X.A.1.
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Table X-9 Benefit & Cost Comparison for each Alternative using Method B and Relative to Less Dynamic 

Baseline 

(Monetary Values in Billions of 2012$, GHG Reductions in Million Metric Tons) a

Benefit-Cost

Category

Alt 2 Alt 3 Alt 4 Alt 5

2035 Vehicle program -$2.6 -$5.9 -$6.2 N/A

Maintenance -$0.06 -$0.13 -$0.14 N/A

Fuel (pre-tax) $20.9 $37.2 $38.7 $49.4

Benefits $12.8 $20.5 $21.1 $26.3

Net benefits $31.1 $51.7 $53.5 N/A

GHG reductions (MMT) 71.9 127.1 132.0 168.3

2050 Vehicle program -$3.1 -$7.0 -$7.4 N/A

Maintenance -$0.06 -$0.13 -$0.14 N/A

Fuel (pre-tax) $31.5 $57.5 $57.6 $72.7

Benefits $19.9 $32.9 $32.9 $40.6

Net benefits $48.3 $83.2 $83.0 N/A

GHG reductions (MMT) 101.2 183.4 183.8 231.8

NPV, 3% Vehicle program -$39.8 -$86.8 -$98.6 N/A

Maintenance -$0.88 -$1.80 -$1.91 N/A

Fuel (pre-tax) $280.0 $495.6 $517.6 $664.3

Benefits $175.2 $279.7 $289.7 $361.5

Net benefits $414.5 $686.8 $706.8 N/A

NPV, 7% Vehicle program -$19.3 -$41.1 -$48.4 N/A

Maintenance -$0.42 -$0.86 -$0.92 N/A

Fuel (pre-tax) $118.1 $206.7 $219.0 $283.0

Benefits $105.5 $173.5 $180.7 $228.0

Net benefits $203.8 $338.1 $350.5 N/A

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an 

explanation of the less dynamic baseline, 1a, and more dynamic baseline, 1b, 

please see Section X.A.1.
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Table X-10 Benefit & Cost Comparison for each Alternative using Method B and Relative to Less Dynamic 

Baseline

HD Pickup and Vans only 

(Monetary Values in Billions of 2012$, GHG Reductions in Million Metric Tons) a

Benefit-Cost

Category

Alt 2 Alt 3 Alt 4 Alt 5

2035 Vehicle program -$0.5 -$0.9 -$1.2 N/A

Maintenance -$0.01 -$0.01 -$0.01 N/A

Fuel (pre-tax) $2.5 $4.2 $4.4 $5.0

Benefits $1.4 $2.2 $2.3 $2.6

Net benefits $3.4 $5.5 $5.5 N/A

GHG reductions (MMT) 8.1 13.9 14.6 16.6

2050 Vehicle program -$0.5 -$1.0 -$1.4 N/A

Maintenance -$0.01 -$0.01 -$0.01 N/A

Fuel (pre-tax) $3.5 $6.3 $6.3 $7.2

Benefits $2.1 $3.5 $3.5 $4.0

Net benefits $5.1 $8.7 $8.4 N/A

GHG reductions (MMT) 10.8 19.3 19.4 22.1

NPV, 3% Vehicle program -$7.5 -$13.5 -$19.6 N/A

Maintenance -$0.18 -$0.18 -$0.18 N/A

Fuel (pre-tax) $31.4 $53.5 $56.8 $64.9

Benefits $18.7 $29.2 $30.7 $34.6

Net benefits $42.4 $69.1 $67.7 N/A

NPV, 7% Vehicle program -$3.7 -$6.5 -$9.7 N/A

Maintenance -$0.08 -$0.08 -$0.08 N/A

Fuel (pre-tax) $13.1 $21.9 $23.7 $27.1

Benefits $11.4 $18.2 $19.3 $21.8

Net benefits $20.7 $33.5 $33.2 N/A

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an 

explanation of the less dynamic baseline, 1a, and more dynamic baseline, 1b, 

please see Section X.A.1.
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Table X-11 Benefit & Cost Comparison for each Alternative using Method B and Relative to Less Dynamic 

Baseline

Vocational Vehicles only 

(Monetary Values in Billions of 2012$, GHG Reductions in Million Metric Tons) a

Benefit-Cost

Category

Alt 2 Alt 3 Alt 4 Alt 5

2035 Vehicle program -$0.2 -$2.1 -$2.1 N/A

Maintenance -$0.02 -$0.03 -$0.04 N/A

Fuel (pre-tax) $1.3 $4.7 $5.1 $7.6

Benefits $1.1 $2.6 $2.8 $3.9

Net benefits $2.2 $5.2 $5.8

GHG reductions (MMT) 4.7 16.1 17.4 25.8

2050 Vehicle program -$0.3 -$2.4 -$2.4 N/A

Maintenance -$0.02 -$0.03 -$0.04 N/A

Fuel (pre-tax) $2.0 $7.3 $7.3 $10.7

Benefits $1.7 $4.2 $4.2 $5.9

Net benefits $3.4 $9.0 $9.1 N/A

GHG reductions (MMT) 6.5 23.2 23.3 33.9

NPV, 3% Vehicle program -$3.6 -$29.6 -$32.8 N/A

Maintenance -$0.22 -$0.42 -$0.52 N/A

Fuel (pre-tax) $16.9 $60.6 $66.3 $99.9

Benefits $14.8 $34.8 $37.4 $52.7

Net benefits $27.9 $65.4 $70.3 N/A

NPV, 7% Vehicle program -$1.7 -$13.8 -$16.0 N/A

Maintenance -$0.10 -$0.19 -$0.24 N/A

Fuel (pre-tax) $6.9 $24.7 $27.9 $42.5

Benefits $8.3 $21.5 $23.4 $33.8

Net benefits $13.4 $32.2 $35.0 N/A

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an 

explanation of the less dynamic baseline, 1a, and more dynamic baseline, 1b, 

please see Section X.A.1.
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Table X-12 Benefit & Cost Comparison for each Alternative using Method B and Relative to Less Dynamic 

Baseline

Tractor/Trailers only 

(Monetary Values in Billions of 2012$, GHG Reductions in Million Metric Tons) a

Benefit-Cost

Category

Alt 2 Alt 3 Alt 4 Alt 5

2035 Vehicle program -$1.9 -$2.9 -$2.9 N/A

Maintenance -$0.03 -$0.08 -$0.08 N/A

Fuel (pre-tax) $17.2 $28.4 $29.2 $36.8

Benefits $10.3 $15.7 $16.0 $19.7

Net benefits $25.6 $41.0 $42.2 N/A

GHG reductions (MMT) 59.1 97.2 100.0 125.9

2050 Vehicle program -$2.3 -$3.6 -$3.6 N/A

Maintenance -$0.03 -$0.08 -$0.08 N/A

Fuel (pre-tax) $26.1 $44.0 $44.0 $54.8

Benefits $16.1 $25.2 $25.2 $30.7

Net benefits $39.9 $65.5 $65.6 N/A

GHG reductions (MMT) 83.8 140.9 141.1 175.7

NPV, 3% Vehicle program -$28.8 -$43.7 -$46.2 N/A

Maintenance -$0.47 -$1.19 -$1.22 N/A

Fuel (pre-tax) $231.7 $381.5 $394.5 $499.5

Benefits $141.7 $215.7 $221.6 $274.2

Net benefits $344.1 $552.3 $568.8 N/A

NPV, 7% Vehicle program -$13.9 -$20.9 -$22.7 N/A

Maintenance -$0.23 -$0.59 -$0.60 N/A

Fuel (pre-tax) $98.1 $160.1 $167.5 $213.4

Benefits $85.8 $133.8 $138.1 $172.4

Net benefits $169.8 $272.4 $282.3 N/A

Note:

a

For an explanation of analytical Methods A and B, please see Section I.D; for an 

explanation of the less dynamic baseline, 1a, and more dynamic baseline, 1b, 

please see Section X.A.1.
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Page 744 of 850

XI. Natural Gas Vehicles and Engines

Both gasoline and diesel vehicles can be designed or modified to use natural gas. NGV 

America estimates that approximately 0.5 percent of the heavy-duty vehicle fleet use natural gas. 

A small but growing number of medium and heavy-duty natural gas vehicles have been produced 

and are in current use. Although these natural gas versions are similar in many ways to their 

petroleum counterparts, there are significant differences. There are also both similarities and 

differences in the production and distribution of natural gas relative to gasoline and diesel fuel.

This combined rulemaking by EPA and NHTSA is designed to regulate two separate 

characteristics of heavy duty vehicles: emissions of GHGs and fuel consumption. The use of 

natural gas as a heavy-duty fuel can impact both of these. In the case of diesel or gasoline 

powered vehicles, there is a close relationship between these two characteristics. For natural gas

fueled vehicles, which reduce or eliminate the use of petroleum, the situation is different. For 

example, a natural gas vehicle that achieves approximately the same fuel efficiency as a diesel 

powered vehicle would emit about 20 percent less CO2 when operating on natural gas; and a 

natural gas vehicle with the same fuel efficiency as a gasoline vehicle would emit about 30 

percent less CO2. In Phase 1, the agencies balanced these facts by applying the gasoline and 

diesel CO2 standards to natural gas engines based on the engine type of the natural gas engine. 

Fuel consumption for these vehicles is then calculated according to their tailpipe CO2 emissions. 

In essence, this applies a one-to-one relationship between fuel efficiency and tailpipe CO2

emissions for all vehicles, including natural gas vehicles. The agencies determined that this 

approach would likely create a small balanced incentive for natural gas use. See 76 FR 57123; 

see also 77 FR at 51705 (Aug. 24. 2012) and 77 FR at 51500 (Aug. 27, 2012) (EPA and NHTSA, 

respectively, further elaborating on basis for having Phase 1 apply at the tailpipe only, including 

for alternative fueled vehicles); see also Delta Const. Co. v. EPA, . 2015 U.S. App. LEXIS 6780, 

F.3d (D.C. Cir. April 24, 2015) (dismissing challenge to Phase 1 GHG standards as being 

arbitrary for applying only on a tailpipe basis).

For Phase 2, the agencies have reevaluated the potential use of natural gas in the heavyduty sector and the impacts of such use. As discussed below, based on our review of the 

literature and external projections we believe that the use of natural gas is unlikely to become a 

major fuel source for medium and heavy-duty vehicles during the Phase 2 time frame. Thus, 

since we project natural gas vehicles to have little impact on both overall GHG emissions and 

fuel consumption during the Phase 2 time frame, the agencies see no need to propose 

fundamental changes to the Phase 1 approach for natural gas engines and vehicles.

In the following sections, we present a lifecycle analysis of natural gas used by the 

heavy-duty truck sector. We also present the results of an analysis by the Energy Information 

Administration projecting the future use of natural gas by heavy-duty trucks. Finally, we list a 

number of potential technologies and discuss the approaches that could be pursued help to reduce 

the methane emissions from natural gas trucks. A more detailed discussion of these analyses and 

issues can be found in the draft RIA. 
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A. Natural Gas Engine and Vehicle Technology

Several engine parameters and characteristics come into play in comparing engines 

powered by natural gas with engines powered by conventional fuels. 

Gasoline-fueled engines are typically spark-ignition engines that rely on stoichiometric 

combustion, which means that essentially all the oxygen from the engine’s intake air is 

consumed in the combustion process. Converting a gasoline-fueled engine to run on natural gas 

involves changing the hardware used to store and deliver fuel to the engine, but the combustion 

strategy remains largely unchanged. The engine must be recalibrated for the different fuel 

properties, but combustion remains stoichiometric. In addition, the catalysts may require 

significant changes to enable the heavy-duty engine to comply with the emission standards. 

Diesel-fueled engines are compression-ignition engines that rely on lean-burn 

combustion, which means that the engine takes in a substantial quantity of excess air (oxygen) 

that is not consumed in the combustion process. Engines usually have turbochargers to compress 

the intake air, which allows for greater power output and thermodynamic efficiency. Converting 

a diesel-fueled engine to run on natural gas may involve a minimal set of changes to engine 

calibrations to maintain lean-burn operation and the overall operating characteristics of a 

compression-ignition engine, although there would be substantial changes to the fuel storage and 

delivery systems. This could require the use of a pilot injection of a small amount of diesel fuel 

to initiate the combustion event, or more commonly, a mixture (never more than 50 percent 

natural gas) of natural gas and diesel fuel is combusted. It is also possible to convert a dieselfueled engine to run on natural gas by adding a spark plug and changing the calibration strategy 

to rely on stoichiometric combustion. This allows for simpler engine design and operation, but 

comes at a cost of higher fuel consumption and CO2 emissions. 

Engines running on natural gas are capable of meeting the same criteria and GHG 

emission standards that apply for gasoline and diesel engines. In the case of reducing PM and 

CO2 emissions, there is an inherent advantage for natural gas. In contrast, engines must be 

properly calibrated and maintained to avoid high emission rates for NOX, HC, and CO.

On-vehicle fuel storage for natural gas is also an important design parameter. The most 

common method today is compressed natural gas (CNG), which involves storing the fuel as a gas 

at very high pressure (up to ~3500 psi) to increase the density of the fuel. This increases vehicle 

weight and generally reduces the range relative to gasoline or diesel vehicles, but the technology

is readily available and does not involve big changes for operators. The alternative is to cool the 

fuel so that it can be stored as liquefied natural gas (LNG), which involves more extensive

hardware changes for managing the fuel as a cryogenic liquid. LNG fuel storage also involves a 

substantial weight increase, but LNG has a higher density than CNG so LNG vehicles can store 

much more fuel than CNG vehicles in the same volume. LNG technology is available for a 

limited number of truck models, mostly for line-haul service where range is a paramount 

consideration. The cryogenic fuel requires substantial changes in hardware and procedures for 

refueling stations and operators. An additional factor in considering LNG technology is that a 

parked vehicle could vent the fuel as it takes on heat from the surrounding environment over a 

period of several days. 
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B. GHG Lifecycle Analysis for Natural Gas Vehicles

This section is organized into three sections. The first section summarizes the upstream 

emissions. The second section summarizes the downstream emissions. The last section 

summarizes the results of the lifecycle emissions and provides a comparison between natural gas 

lifecycle and diesel fuel lifecycle emissions. Only the overall results of the lifecycle emissions 

comparison between natural gas and diesel fuel are presented here, much more detail is provided 

in Chapter 13 of the DRIA. 

(1) Upstream Emissions

Upstream methane emissions, occurring in the natural gas production, natural gas 

processing, transmission, storage and distribution stages of natural gas production, are estimated 

and summarized in the annual EPA report Inventory of U.S. Greenhouse Gas Emissions and 

Sinks (GHG Inventory) for the United Nations Framework Convention on Climate Change 

(UNFCCC). As a basis for estimating the life-cycle impact of natural gas use by heavy-duty 

trucks, we used the year 2012 methane emission estimates in the most recent GHG Inventory, 

published in 2014. The GHG Inventory also includes the quantity of carbon dioxide which is 

coproduced with methane throughout the natural gas system and emitted to the atmosphere 

through venting, flaring, and as fugitive emissions. 

The GHG Inventory is updated annually to account for new emission sources (e.g., new 

natural gas wells), updated data, emission factors and/or methodologies, and to account for 

changes in emissions due to policy changes, regulatory changes and changes in industry

practices. The GHG Inventory reflects emission reductions due to existing state regulations, 

National Emission Standards for Hazardous Air Pollutants (NESHAP) promulgated by EPA in 

1999, the New Source Performance Standards (NSPS) promulgated by EPA in 2012,807 and 

Natural Gas Star (a flexible, voluntary partnership that encourages oil and natural gas companies 

to adopt proven, cost-effective technologies and practices that improve operational efficiency

and reduce methane emissions).808

Emission estimates in the GHG Inventory are generally bottom-up estimates which are 

per-unit (compressor, pneumatic valve, etc.) emission estimates based on measured or calculated 

emission rates from such emission sources. 

In addition to the national-level data available through the GHG Inventory, facility-level 

petroleum and natural gas systems data are also available through EPA’s Greenhouse Gas 

Reporting Program (GHGRP). This data represents a significant step forward in understanding 

GHG emissions from this sector and EPA expects that this data will be an important tool for the 

agency and the public to analyze emissions, and understand emission trends. For some sources, 

 

807 Oil and Natural Gas Sector: New Source Performance Standards and National Emission Standards for Hazardous 

Air Pollutants Reviews; Final Rule, 40 CFR Parts 60 and 63, Environmental protection Agency, August 16, 2012.

808 www.epa.gov/gasstar/
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EPA has already used GHGRP data to update emission estimates in the GHG inventory, and 

EPA plans to continue to leverage GHGRP data to update future GHG Inventories. 

The EPA-promulgated 2012 New Source Performance Standards (NSPS) will reduce 

emissions of ozone precursors from natural gas facilities and have methane and hazardous air 

pollutant reduction co-benefits. The NSPS standards require that natural gas wells which are 

hydraulically fractured control emissions using flaring or reduced emission completion (REC) 

technology from completions and workovers starting in 2012. RECs used by natural gas well 

drillers capture the natural gas emissions that occur during well completion, instead of venting or 

flaring the emissions. Starting January 2015, RECs are required for natural gas well completions 

and workovers. The NSPS also regulates the emissions from certain new natural gas production 

equipment, including dehydrator vents and condensate tanks. In the 2013 Climate Action Plan, 

EPA projects future emissions of methane to increase modestly, by about 4 percent between now 

and 2025. As estimated for the recent power plant proposed rulemaking, natural gas production 

is expected to increase by about 20 percent during this timeframe, thus, methane emissions in 

2025 are expected to be 14 percent lower than in 2012 based on an equivalent volume of natural 

gas being produced. As announced by the White House, EPA will further regulate methane 

emissions from new natural gas production facilities.809,810

In the GHG Inventory, emissions associated with powering the units or equipment (i.e., 

compressors, pumps) used in natural gas production, processing, transmission and distribution 

are aggregated with all the other fossil fuel combustion activities. Rather than attempt to 

disaggregate those specific GHG emissions from the rest of the process emissions in the GHG 

Inventory, we instead used the estimated emissions for these sources provided by GREET.

(2) Downstream Emissions

Natural gas can be used by vehicles either as a compressed gas (CNG) or as liquefied 

natural gas (LNG). We discuss the emissions of both below.

(a) Compressed Natural Gas (CNG)

The natural gas that comprises CNG is typically off-loaded from the natural gas system 

where the vehicles using CNG are refueled. This is because the natural gas used as CNG is 

compressed at the retail stations that sell the CNG and the fleet facilities which fuel the CNG 

fleet vehicles. To get the natural gas to the CNG retail facilities which are mostly located in or 

near urban areas, the natural gas is expected to be shipped through the distribution system 

downstream of the natural gas transmission system. CNG trucks are then refueled at the retail 

stations providing CNG. Each time a CNG refueling event occurs, a small amount of natural gas 

is released to the environment. Because of a lack of data or an estimate by GREET or CARB, 

 

809 FACT SHEET: Administration Takes Steps Forward on Climate Action Plan Announcing Actions to Cut 

Methane Emissions, The White House, January 14, 2015. 

810 FACT SHEET; EPA’s Strategy for Reducing Methane and Ozone-Forming Pollution from the Oil and Natural 

Gas Industry; Environmental Protection Agency, January 14, 2015.
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this small amount of natural gas has not been estimated and therefore are not included in the 

lifecycle analysis presented here. Since these systems are designed to have no leaks, the CNG 

could remain stored in the CNG tanks indefinitely. However, the very high pressure at which 

CNG is stored dramatically increases fugitive emissions if a fitting were to develop a leak. The 

level of fugitive emissions for a certain sized hole is directly proportional to the pressure. We do 

not have any data on the fugitive emissions from CNG trucks. In our lifecycle analysis, we 

assume that CNG fugitive emissions are zero, which likely underestimates the methane 

emissions.

When CNG is stored at high pressure (i.e., 3600 psi) it contains only about 25 percent the 

energy density of diesel fuel. This low fuel storage density is a disincentive for using CNG in 

long haul trucks. An adsorbent for natural gas (ANG),811 called metal organic framework (MOF) 

for storing CNG, has been invented and is being tested for large scale use. The technology

involves filling the CNG tank with a specially designed substance that looks similar to a 

pelletized catalyst. The substance establishes a matrix which causes the methane molecules to 

become better organized and store the same quantity of natural gas in a smaller volume at the 

same pressure (about 60 percent of the energy density of diesel fuel), or store the same density of 

natural gas at a lower pressure. This MOF could improve the energy density of CNG which 

would make it a better candidate for natural gas storage for long range combination trucks. Or, if 

used to store CNG at the same density, could reduce the compression energy required to 

compress the CNG since it could be stored at a lower pressure.

(b) Liquified Natural Gas (LNG)

A primary reason for liquefying natural gas is that it allows storing the natural gas at 

about 60 percent of the density of diesel fuel. For this reason, LNG is a primary fuel being 

considered by long haul trucks.

The first step downstream of the natural gas production, processing and distribution 

system for making LNG available to trucks is the liquefaction step. This step involves the 

removal of heat from the natural gas until it undergoes a phase change from a gas to a liquid at a 

low pressure. LNG plants are configured depending on their ultimate capacity. World class 

LNG plants produce 5 million metric tons, or more, per year of LNG and the economy of scale 

of these large plants supports the significant addition of capital to reduce their operating costs 

and energy use. An LNG plant solely producing LNG for truck fuel is expected to be 

significantly smaller than the world class LNG export plants with a poorer economy of scale. 

Their energy efficiency would be expected to be much lower on a percentage basis. The 

California Air Resources Board estimates the liquefaction plants used for producing truck LNG 

fuel are 80 percent efficient, compared to 90 percent efficient for world class LNG plants.812 In

 

811 Menon, V.C., Komarneni, S. 1998 “Porous Adsorbents for Vehicular Natural Gas Storage: A Review”, Journal of 

Porous Materials 5, 43-58 (1998); Burchell, T “Carbon Fiber Composite Adsorbent Media for Low Pressure Natural 

Gas Storage” Oak Ridge National Laboratory

812 Detailed California-Modified GREET Pathway for Liquid Natural Gas (LNG) from North American and Remote 

Natural Gas Sources, Version 1.0, California Air Resources Board, July 20, 2009.
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our lifecycle analysis of LNG as a truck fuel, we also assumed that LNG plants are 80 percent 

efficient. The LNG producer is not only responsible for the LNG fugitive emissions at the plant, 

but it is also responsible for the GHG and other process emissions emitted when liquefying the 

natural gas. Because LNG plants are located separate from the retail facilities, they can be 

located to access the lowest cost feedstock. This means the natural gas for LNG can be sourced 

from the larger natural gas transmission pipelines which are upstream of the distribution 

pipelines. Once the natural gas is liquefied at the liquefaction plant, it is stored in an insulated 

storage tank to keep the LNG liquefied. 

To transport the LNG to the retail station, the LNG is loaded into an insulated horizontal 

trailer designed specifically for transporting LNG. If the LNG in the truck trailer were to warm 

sufficiently to cause the LNG to reach the pressure relief valve venting pressure, there would be 

boil-off emissions from the truck trailer. However, since the LNG is super cooled, boil off 

events are likely to be rare. We did not have access to any specific data to estimate these 

emissions so we used a CARB estimate of boil-off emissions for LNG transportation by the 

tanker truck between the LNG plant and retail outlets.813

LNG is stored in an insulated storage tank at the retail facility. Heat gain in the storage 

tank could eventually lead to boil-off emissions. Service stations with little LNG demand are at 

a higher risk of boil-off emissions compared to service stations which have a significant 

throughput volume. LNG stations could be configured to avoid boil-off events to the 

atmosphere, such as venting to a co-located CNG facility, or venting to a nearby natural gas 

pipeline. We did not have access to any specific data to estimate these emissions so we used a 

CARB emission estimates for the boil-off emissions from LNG retail facilities.814

Vehicles requiring LNG fuel drive up to an LNG retail outlet or fleet refueling facility

and fill up with LNG fuel. When the refueling nozzle is disconnected from the LNG tank 

nozzle, a small amount of methane is released to the environment. In addition, it may be 

necessary prior to refueling, due to high pressure in the truck’s LNG tank, to reduce the pressure 

in the truck’s LNG tank to speed up the refueling process. In some cases the retail station is 

equipped with another hose and associated piping to vent the excess gas to the retail stations’ 

storage tank where it would usually condense back to a liquid due to the lower temperature of 

that tank, or perhaps be vented to a natural gas pipeline. However, for those retail outlets 

without such vent lines to the storage tank, the truck driver may simply vent the truck’s storage 

tank to the atmosphere. As part of a sensitivity analysis for our lifecycle analysis, we estimate 

the emissions for venting an LNG tank prior to refueling. 

(c) Comparing CNG to LNG 

There is an important difference in providing CNG and LNG which is important to 

highlight. For making CNG available to trucks, only a single facility, the retail outlet, is required 

 

813 Ibid. 

814 Ibid.
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for distributing CNG, while LNG requires both a liquefaction plant and a retail outlet and a 

means for transporting the LNG from the liquefaction plant to retail. Relying on a single facility 

simplifies the logistics of providing CNG and reduces the opportunity for methane leakage to the 

environment. However, this emissions disadvantage of LNG compared to CNG is offset 

somewhat because LNG is expected to access the lower priced natural gas from the upstream 

transmission system, therefore, the methane emissions associated with the downstream natural 

gas distribution system are avoided. 

(d) Vehicle Emissions

There are several different ways that diesel heavy duty engines can be configured to use 

natural gas as a fuel. The first is a spark ignition natural gas (SING), Otto cycle SING heavy

duty engine burns the fuel stoichiometrically and uses a three-way catalyst, and some also add an 

oxidation catalyst to provide the greatest emissions reduction. In this case the 

engine compression ratio is reduced similar to that of a gasoline engine and thus its thermal 

efficiency is lower than a diesel-like engine by about 10 - 15 percent.

The second is a direct injection natural gas (DING), diesel cycle. The DING engine uses 

a small quantity of diesel fuel (pilot injection) or a glow plug as ignition sources. As the 

injection system for the diesel fuel does not have the capability of greater injection quantities, 

this option has no dual-fuel properties. On the other hand, an optimization of the pilot injection 

can be made to achieve lower emissions. An advanced high pressure direct injection (HPDI) fuel 

system combining the injection of both diesel fuel and natural gas can be used for lean burn 

combustion. This enables the engine to maintain the efficiency advantage of a compression ignition 

engine while running mainly CNG/LNG.

The third is a mixed-fuel natural gas (MFNG), diesel cycle. In a mixed-fuel engine, 

natural gas is mixed with intake air before induction to the cylinder and diesel fuel is used as 

ignition source. Mixed-fuel vehicle/engine means any vehicle/engine engineered and designed 

to be operated on the original fuel(s), or a mixture of two or more fuels that are combusted 

together. Engine results showed that the efficiency of the engine could decrease by about 2-5

percent in mixed-fuel mode compared to diesel mode and that the diesel replacement was 

approximately 40-60 percent.

Each of these natural gas engine types has its merits. The SING engine is less costly, but 

is less fuel efficient and because of the lower compression ratio it has less torque than the two 

diesel cycle engines. The DING engine is likely the most expensive because of the special 

natural gas/diesel fuel injection system and large required amount of natural gas (LNG or CNG) 

storage since the truck must run on natural gas. However, because the truck can run almost 

completely on natural gas, the DING engine has the potential to more quickly pay down the 

higher investment cost of the natural gas truck. The MFNG engine provides the truck owner the 

flexibility to operate on natural gas or diesel fuel, but at the expense of a slower natural gas 

investment paydown rate because it can operate at most 50 percent of the time on natural gas. 

When assessing the methane emissions from both CNG and LNG trucks, it is important 

to separate those trucks built or converted before 2014 to those built or converted in 2014 and 

later. The trucks built before 2014 only needed to meet a nonmethane hydrocarbon (NMHC) 
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standard, which means that the methane emissions from these trucks are unregulated. Our 

certification data show that the methane tailpipe emissions from these trucks/buses ranges from 2 

– 5 g/bhp-hr for both spark ignition (gasoline type) and compression ignition (diesel type) 

engines. 

For 2014 and later OEM compression ignition natural gas trucks or natural gas 

conversions of 2014 and later diesel trucks, the trucks must meet a 0.1 g/bhp-hr methane 

emission standard in the case of a larger truck engine tested with an engine dynamometer, and a 

0.05 g/mile methane emission standard in the case of smaller trucks tested on a chassis 

dynamometer. For spark ignition (gasoline style) engines, the standards take effect in 2016.815 

Natural gas truck manufacturers are allowed to offset methane emissions exceeding the methane 

emission standard by converting the methane emission exceedances into CO2 equivalent 

emissions and using CO2 credits. For the initial natural gas engine certifications that EPA 

received for 2014, the truck manufactures chose to continue to emit high levels of methane 

(around 2 g/bhp-hr) and use carbon dioxide credits to offset those emissions. We don’t know if 

this practice of will continue in the future, however, for evaluating the lifecycle impacts of 

natural gas heavy-duty trucks, the 2014 and later natural gas heavy-duty trucks may in fact have 

an emissions profile more like the pre-2014 trucks and not like the 2014 and later trucks as 

depicted below in the figures. It is worth noting that the potential exists for deterioration or 

malfunction of the engines, fuel supplies, or associated emission control devices on these trucks 

to occur in such a manner to result in higher methane emissions in actual use. We have not 

specifically accounted for the potential for increased methane emissions caused from high 

emitter natural gas trucks. See generally Section II above.

The crankcase of these engines receives leakage from across the piston rings, which can 

contain methane. The crankcase of the spark ignition engines is normally vented into the intake 

of the engines, thus, any methane emissions from the crankcase which is not combusted in the 

engine would be accounted for in the tailpipe emissions. For compression ignition engines, 

however, the crankcase emissions are allowed to be vented into the exhaust pipe downstream of 

the aftertreatment devices, and therefore the crankcase emissions are released to the atmosphere 

even though they are included in the emissions test for the Methane standard that was introduced 

in Phase 1 on the rule. Another potential source of methane emissions from CNG and LNG 

trucks is fugitive emissions from the engine and the piping which routes the fuel to the engine. 

Thus, either while parked or operated, this part of the vehicle fuel and engine systems could leak 

methane to the environment (which is different from boil-off emissions from LNG trucks 

discussed below). We do not have data nor did we develop an estimate for these potential 

fugitive emissions from these types of in-use leaks. If the natural gas vehicles are well 

maintained, these emissions are likely to be very low.

The thermal efficiency (the ratio of energy converted to work versus energy consumed) 

of the natural gas engine also plays a role in the lifecycle emissions of the truck. Natural gas 

engines are generally less efficient than their gasoline and diesel counterparts. Furthermore, 

 

815 See 40 CFR sections 1036.108(a)(2) and 1037.104(c) and 76 FR 57192.
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manufacturers choose to produce spark-ignition stoichiometric natural gas engines for use in 

diesel applications. Spark-ignition natural gas engines can be as much as 15 percent less 

efficient than compressed ignition engines which operate on diesel fuel. In our lifecycle 

analysis, we provide two different sensitivities for natural gas vehicles assuming that they may

be 5 percent and 15 percent less efficient.

An important difference between CNG and LNG is way in which the fuels are stored on 

the vehicle. The CNG is contained in a sealed system while the LNG system is ultimately open 

to the environment. Providing that there are no leaks in the storage system, the CNG truck is 

inherently low (zero) emitting and a parked truck would contain the CNG indefinitely. An LNG 

truck is inherently high emitting since if the truck were to be parked long enough its entire 

contents would be emitted to the environment. 

Thus, a major GHG issue for LNG trucks is boil-off emissions from the truck’s fuel 

storage systems. When the liquefied natural gas is pumped into the truck LNG tanks, it is 

“supercooled,” meaning that the pressure of the LNG is well below the pressure at which the 

natural gas vent valve would relieve the LNG pressure. If the truck is driven extensively, the 

drawdown of liquid level will cause a vacuum which will cause some of the fuel to boil off and 

the heat of vaporization would thus cool the rest of the liquid in the LNG storage tank. It is 

possible that the fuel would maintain its supercooled temperature, or possibly even cool further 

below its supercooled temperature, the entire time until the LNG is completely consumed. 

If the truck is not driven at all or is driven very little, the very low temperature and low 

pressure LNG warms due to the ambient temperature gradient through the tank wall, and 

vaporizes, causing the temperature and pressure of the LNG to rise. When the pressure reaches a 

maximum of 230 psi a safety release valve releases the methane gas to vent excess pressure. 

There are two industry standards used to design tanks to reduce the temperature increase, one for 

a 3 day hold time816 and one for a 5 day hold time.817 Hold time is the time elapsed between the 

LNG refueling and venting.

If there is a boil-off event, a large amount of methane would be released. If aware of the 

impending boil-off, such as when the truck is being maintained, the truck driver could hook up 

the LNG tank to a hose which would vent the natural gas emissions to a CNG system which 

could reuse the boil-off natural gas as CNG, or vent the natural gas emission to a natural gas 

pipeline. Otherwise the boil-off emission would simply vent to the atmosphere. If the truck had 

200 gallons of LNG storage capacity, the estimated quantity of boil-off emissions would range 

from 3 to 9 gallons of LNG for each boil off event depending on the fill level of the LNG tank. 

Each boil off event has the potential to release on the order of 5,300 – 15,800 grams of CH4

which equates to 132 – 400K grams of CO2 equivalent emissions, assuming that methane has a 

global warming potential (GWP) of 25 (assessed over 100 years). If the vehicle continues to sit 

 

816 National Fire Protection Association 52, Compressed Natural Gas (CNG) Vehicular Fuel System Code, 2002 

Edition. 

817 SAE International (2008) SAE J2343: Recommended Practice for LNG Medium and Heavy-Duty Powered 

Vehicles. Warrendale, Pennsylvania.
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for five more days and boil-off events occur each day to several times per day as the tank vents 

and rebuilds in pressure, the sum total of the boil-off events can result in over a million grams of 

CO2 -equivalent emissions.

(3) Results of Life Cycle Analysis

To estimate the lifecycle impact of natural gas used by heavy-duty trucks, we totaled the 

carbon dioxide, methane (CH4) and the nitrous oxide (N2O) emissions for the upstream and 

downstream portions of the natural gas system. The methane and nitrous oxide emissions are 

converted to carbon dioxide-equivalent emissions using the appropriate GWP conversion factors. 

The GWP conversion factors EPA currently uses are for a 100-year timeframe, are 25 and 298

for methane and nitrous oxide, respectively.818 

To establish the impacts of natural gas use in the heavy-duty fleet, it was necessary to 

compare the lifecycle impacts of natural gas against the base fuel it is replacing, which is diesel 

fuel. The lifecycle impact of diesel fuel was estimated by the National Energy Technology

Laboratory (NETL) for the production and use of diesel fuel in 2005. EPA used this lifecycle 

assessment for the 2010 Renewable Fuel Standard Rulemaking and we are using this NETL 

diesel fuel lifecycle estimate as the reference for comparison with the natural gas lifecycle 

assessment. NETL is in the process of revising its lifecycle analysis of diesel fuel to 2009, 

which should be available sometime in 2015. According to the lead analyst, the 2009 lifecycle 

analysis appears to be similar in magnitude to the 2005 analysis.819 However, the 2009 analysis 

will not capture the lifecycle effects of the large increase in hydraulically fractured crude oil (i.e., 

Bakken, Eagle Ford) which has occurred in the U.S. during the first part of this decade. 

To illustrate the relative full lifecycle impact of natural gas-fueled heavy-duty vehicles 

compared to diesel fueled heavy-duty vehicles, we assessed several different scenarios. The first 

is a conversion of a diesel engine to use compressed natural gas. Of the tens of thousands of 

heavy-duty natural gas trucks currently in use, over 90 percent are of this type. These are 

conversions of older trucks so they are not regulated by the 2014 methane standard. For future 

year heavy-duty trucks, we also estimated the lifecycle emissions if the trucks were meeting a 

0.1 g/bhp-hr or a 0.05 g/mile methane tailpipe standard. We provide two sensitivities to capture 

the lower thermal efficiencies of natural gas trucks: 5 percent less thermally efficient (thermal 

low) and 15 percent less energy efficient (thermal high, which is 10 percent worse thermal 

efficiency than the 5 percent less thermally efficient case). The relative life cycle assessment is 

shown in Figure XI-1.

 

818 These global warming potential values are based on the Fourth Assessment Report authored by the 

Intergovernmental Panel on Climate Change. 

819 Conversation with Timothy J. Skone P.E., National Energy Technology Laboratory, Department of Energy, June 

2014.
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Figure XI-1 Full Lifecycle Analysis (except tailpipe only emissions) of a CNG Truck 

(Projected Upstream Methane Emissions in 2025, methane GWP of 25)

0

20,000

40,000

60,000

80,000

100,000

120,000

Diesel

Tailpipe

CNG

Tailpipe

Diesel CNG pre2014CNG 2014

and later

Emissions (gC

O2eq/m

m

Btu)

Thermal High

Thermal Low

CH4:&N2O

CO2
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The first two bars of Figure XI-1 show that based solely on CO2 tailpipe emissions (with 

and without thermal efficiency adjustments and assuming no increased methane emissions at the 

truck), CNG trucks are estimated to emit about 20 percent less GHG emissions than diesel 

engines. But this advantage decreases if the natural gas engine is less thermally efficient. The 

three full lifecycle analyses represented by the right three bars in the figure show that pre-2014 

CNG trucks are estimated to emit less GHG emissions as diesel trucks, although if their thermal 

efficiency is much lower (15 percent less than the diesel fueled engine) they could emit about the 

same GHG emissions. When such trucks are complying with the 2014 and later methane 

emission standards, their methane emissions are much lower and these trucks are expected to be 

lower emitting than diesels, even if they are less thermally efficient. 

The second scenario presented in Figure X1-2 is a combination LNG truck which in one 

case is assumed to be emitting methane at pre-2014 emission standards and in another case is 

assumed to comply with the 2014 methane standard. It is an OEM natural gas truck with a high 

pressure direct injection engine, and because of the extensive mileage, the truck most 

realistically would use LNG as a fuel to provide the necessary range for the dedicated natural gas 

engine. We make two different assumptions with respect to refueling and boil off emissions. In 

the LNG average case, we assume a modest quantity of refueling and boil-off methane emissions 

which is estimated by GREET. The second boil-off emission estimate (assumed to be complying 

with the 2014 methane emission standard) is based on venting the LNG storage tank to the 

atmosphere each time the driver refills his tank, and one LNG boil-off event between each time 

the driver must refuel his tank. As discussed above, we do not expect such high refueling and 

boil-off emissions to be common practices for newer trucks that are operated regularly. 

However, as the use of these trucks decreases as they age and are sold into the secondary market, 

the risk for refueling and boil-off emission events increases – this estimate provides a simple 

sensitivity emission estimate. The lifecycle assessment is shown in Figure XI-2.
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Figure XI-2 Full Life Cycle Analysis (except tailpipe only emissions) of an LNG Truck 

(Projected Upstream Methane Emissions in 2025, Low and High Refueling and Boil-Off Emissions, 

Methane GWP of 25)

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

Emissions (gC

O2 eq/m

m

Btu)

Thermal High

Thermal Low

CH4:&N2O

CO2
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Figure XI-2 shows that LNG trucks have about the same greenhouse gas footprint as 

diesel trucks providing that they are complying with the methane emission standard and 

providing we assume a low quantity of refueling and boil-off emissions. In comparing CNG to 

LNG, the LNG trucks appear higher emitting than CNG trucks because of the low thermal 

efficiency of the small liquefaction facilities. If these LNG trucks emit high levels of methane 

when refueling and by experiencing boil-off events or if they emit methane at pre-2014 emission 

standard levels, their GHG emissions can potentially be much greater than that from diesel 

trucks.

It is important to point out the uncertainties associated with the lifecycle estimates 

provided in the above figures. As discussed above, there is uncertainty in both the upstream and 

downstream methane emission estimates for natural gas facilities and equipment, and the trucks 

that consume natural gas. There is also uncertainty in the diesel fuel lifecycle analysis conducted 

by NETL. As new information becomes available, we can update our lifecycle emission 

estimates which would reduce the uncertainty of this analysis. A number of studies are being 

conducted to quantify the methane emissions (upstream and downstream) and life cycle impacts 

of natural gas by the Environmental Defense Fund (EDF). The final reports for these studies 

have not yet been released but we will review them once they are available. Finally, the lifecycle 

analysis is sensitive to the GWP factor used to assess methane and nitrous oxide, and if a 

different GWP value were to be used, it would affect the relative lifecycle impact of natural gas 

relative to diesel in heavy-duty trucks (see Chapter 13 of the draft RIA for sensitivity analyses 

regarding upstream methane emissions and the use of different GWP factors).

We compared our lifecycle emission estimates for natural gas, relative to diesel fuel, with 

the estimates provided by the California Air Resources Board (CARB) for its Low Carbon Fuel 

Standard (LCFS). For our emissions estimate used in the comparison we used the carbon 

dioxide-equivalent (CO2 eq) emissions estimated for 2014 and later engines, which must comply

with a methane tailpipe emissions standard, and assumed that the engine was 5 percent less 

thermally efficient than a comparable diesel engine. For the CARB emissions estimates, we used 

the estimates made for illustrative purposes using the 2013 version of the CARB GREET model 

as published in August, 2014.820 821 CARB estimates that CNG engines emit 76 percent of the 

CO2 eq emissions as a diesel truck, while our analysis estimates that CNG engines emit 81 

percent of the CO2 eq emissions as a diesel truck. The most likely explanation for CARB’s 

lower estimated CO2 eq emissions for CNG engines is that a much larger portion of the 

electricity used to compress natural gas is renewable in California than the rest of the country. 

 

820 Low Carbon Fuel Standard Reconsideration: CA-GREET Model Update, California Air Resources Board, 

August 22, 2014.

821 Per Anthy Alexiades of CARB: CARB is planning to propose a new draft lifecycle analysis for CNG and LNG 

trucks at an April 2015 public meeting. While the CNG lifecycle GHG emissions are expected to be about the same, 

the LNG lifecycle emissions are expected to be lower based on using a 90% efficiency for liquefaction plants 

instead of the 80% efficiency that CARB was using previously. Lifecycle emissions for both CNG and LNG trucks 

will be adjusted to be 10% higher if using a spark ignition engine to account for their lower thermal efficiency. 

These estimates are solely for hypothetical analyses. LCFS credits are awarded based on GHG emissions for each 

specific application. 
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CARB estimates LNG engines emit 94.5 percent of the CO2 eq emissions as a diesel truck while 

our analysis estimates LNG trucks emit 96 percent of the CO2 eq emissions as a diesel truck. 

CARB assumes no boil-off or venting emissions for LNG trucks and for this comparison, we 

used our more modest boil-off and venting assumption, as described above, which is close to 

CARB’s. Overall, our estimates are very similar to those estimated by CARB and when there 

are differences, the differences are as expected.

A UC Davis report recently released estimated that CNG and LNG trucks using spark 

ignition engines (SING) emit about the same amount of CO2 -equivalent emissions, and these 

emissions are slightly higher than that of diesel engines.822 The HPDI engines (DING) fueled by 

LNG are estimated to be the lowest emitting of the several scenarios analyzed by the study. 

Because the study did not discuss vehicle boil-off emissions, it is likely that the study either 

assumed that these emissions are zero or assumed the default vehicle boil-off emission estimates 

made by GREET. It is likely that the study assumed that the liquefaction plants are 90 percent 

efficient as this is the default assumption in GREET, which leads to lower GHG emissions by

LNG trucks.

C. Projected Use of LNG and CNG

We reviewed several sources to estimate how much natural gas is currently being used

and is projected to be used by heavy-duty trucks. Projections for this emerging technology range 

from 7 percent of new heavy-duty vehicle sales to over 40 percent by 2040. Large uncertainties 

exist even since the 2014 NAS First Report was written.823 Among the range of projections we 

assessed, that produced by the Energy Information Administration (EIA) seemed the most 

credible for capturing recent trends, and for projecting future natural gas use by heavy-duty 

trucks. There are several factors that support this assessment. 

First, in its 2014 Annual Energy Outlook, EIA estimates that natural gas fueled 0.4

percent of the energy use of heavy-duty trucks in 2014. This estimate is consistent with the 

fraction of the heavy-duty fleet which is fueled by natural gas as estimated by the industry.

824

Conversely, other studies referenced by the NAS report assume that current use is already about 

2 percent (the DRIA contains more discussion about these other projections).

Second, the EIA projection is based on an economic analysis which considers the 

increased cost of manufacturing a natural gas truck over a diesel truck, the fuel savings for using 

natural gas instead of diesel fuel, and whether the payback time of the fuel savings against the 

increased truck cost would result in purchases of natural gas trucks. As part of this analysis, EIA 

assumes that lighter heavy-duty trucks would use CNG, which is a lower cost technology suited 

for the shorter driving distances for these trucks. The long haul trucks, however, require larger

 

822 Jaffe, Amy Myers, Exploring the role of Natural Gas in U.S. Trucking, NextSTEPS Program, UC Davis Institute 

of Transportation Studies, February 18, 2015.

823 B. Tita, Slow Going for Natural-Gas Powered Trucks; Wall Street Journal, 8/26/2014

824 NGV America estimates that there are 62,000 natural gas fueled heavy-duty trucks and buses operating in the 

U.S. out of a total of 12.3million heavy-duty trucks and buses operating in the U.S., which equates to 0.5%. 
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on-board stores of fuel to extend the driving range which is satisfied by storing the natural gas as 

a liquid. LNG has about 60 percent of the energy density of diesel fuel, compared to CNG which 

has only 25 percent of the energy density of diesel fuel. To satisfy the long driving range of the 

long haul trucks, EIA assumed that they would use LNG as a fuel. The assumptions used by EIA 

for conducting its economic analysis all seem reasonable.

Third, EIA is one of the several organizations in the world which collects fuel pricing 

data and projects future fuel prices using a sophisticated modeling platform. One of the most 

important assumptions in projecting the future use of natural gas in the transportation sector is 

the relative price of natural gas to the price of diesel fuel. In 2014, the natural gas price 

purchased by industrial users was about $6 per million BTU. The price of crude oil has been 

volatile during 2014 as the Brent crude oil price started at about $110 per barrel, but decreased to 

under $50 per barrel. From EIA’s website, the average retail diesel fuel price in the first part of 

2014 was about $3.80 cents per gallon. When comparing the natural gas spot market price on a 

diesel equivalent basis to the diesel fuel price, it appears that natural gas is priced about one 

quarter of the diesel fuel price. However, if used as compressed natural gas, the natural gas must 

be distributed through smaller distribution pipeline system that exists in cities, which increases 

the price of the natural gas. Then the natural gas must be compressed and stored at a retail 

outlet, and then dispensed to CNG trucks. The estimated retail price of CNG is $2.35 on a diesel 

gallon equivalent (DGE) basis, or about $1.45 DGE less than diesel fuel. LNG plants are 

assumed to be located close to large transmission pipelines away from cities, thus, it is sourced 

from lower cost natural gas. However, for producing LNG, the natural gas must be liquefied, 

shipped to retail outlets, stored and then dispensed to LNG trucks. These steps add substantially

to the price of the LNG and the estimated retail price of LNG is $2.65 DGE, or $1.15 DGE less

than diesel fuel.

In its 2014 AEO projections, EIA estimates that crude oil prices in the upcoming years 

will decline modestly until after 2020 when they start increasing until they reach $140/bbl in 

2040. Natural gas prices are expected to only slightly increase over this period. 

Fifth, the assumptions regarding payback used by EIA seemed reasonable. EIA projects 

that natural gas trucks begin to be purchased when the payback times are 4 years or less based on 

a survey conducted by the American Trucking Association. This is consistent with conversations 

the agencies have had with some fleet owners. Since EIA does not report the payback times as 

an output of its projections, it is useful to understand payback times. The 2014 NAS Phase 2 

First Report cites the payback for the extra cost of natural gas trucks as 2 years, but other sources 

report a longer return closer to 4 years.825 

EPA assessed the time required for the lower fuel cost of CNG and LNG to payback the 

incremental truck cost of using LNG and CNG. The CNG tank plus fuel weighs on the order of 

four times as much as the diesel counterpart, and typically adds $40,000 - $50,000 to the cost of 

a heavy-duty truck. In 2014, we estimated the payback time to be over 5 years when we assessed 

 

825 Early LNG Adopters Experience Mixed Results; Truck News, October 1, 2013
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the payback at the higher crude oil prices at the beginning of the year. The payback rates would 

be even higher if we would have assessed the payback rates at the end of the year when the crude 

oil prices were much lower. However, for many fleets, even the payback rates at the higher 

crude oil prices would not be sufficiently attractive, and generally explains the low penetration of 

natural gas in the heavy-duty sector today. It appears that when the payoff time is longer than 4 

years, few fleets are interested in purchasing natural gas trucks without subsidies to compensate 

for the higher purchase price of natural gas trucks. According to EIA, half the natural gas 

consumption by cars and trucks is in California, a state that subsidizes the purchase price of 

natural gas vehicles, and also subsidizes the cost of natural gas dispensing stations. The Low 

Carbon Fuel Standard in place in California also incentivizes natural gas use because natural gas 

is considered to cause less of an impact on the climate than petroleum-based gasoline and diesel 

fuel.826 The majority of the other half of the NG fleet resides in states which subsidize the cost 

of using natural gas by motor vehicles.

Based on the EIA projections for crude oil and natural gas prices, the payoff time of LNG 

trucks is expected to remain long (more than 5 years) until sometime after 2020 when crude oil 

prices are projected to begin increasing. Thus, natural gas use by heavy-duty trucks is not 

projected by EIA to increase above 1 percent of the heavy-duty fuel demand until after 2025.

If the apparent payback time for CNG and LNG trucks use is favorable to fleet owners, 

fuel availability could still slow the transition to CNG and LNG. This is because CNG and LNG 

availability at service stations is currently 1 percent or less of the availability of gasoline and 

diesel fuel and therefore not available for most fleets. LNG availability is particularly 

challenging because in addition to an LNG service station, a LNG liquefaction plant would be 

needed as well. 

To the extent that natural gas displaces diesel fuel and impacts truck greenhouse gas 

emissions, either positive or negative, there would be little impact on overall greenhouse gas 

emissions because of the low natural gas truck sales that are expected to occur over the next 

decade. The low natural gas use by the heavy-duty sector during the Phase 2 timeframe will give 

us time to learn more about both upstream and downstream methane emissions to gain a better 

understanding of the lifecycle impacts of natural gas use by heavy-duty trucks. It will allow us 

more time to consider the best additional steps to take to further reduce upstream and 

downstream methane emissions to improve the lifecycle impacts of natural gas use by heavyduty trucks should the heavy duty truck fleet begin consuming natural gas in much larger 

quantities. 

 

826 CARB currently estimates for the LCFS that CNG and LNG trucks reduce GHG-equivalent emissions by 32% 

and 17%, respectively, compared to gasoline and diesel fuel. In August 2014, CARB proposed reducing the GHGequivalent benefit of CNG and LNG trucks to 22% and 3%, respectively, compared to gasoline and diesel fuel. 
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D. Natural Gas Emission Control Measures

As interest in the potential use of natural gas as a heavy-duty fuel has increased, industry

has begun to investigate how to improve the overall emission performance of natural gas 

vehicles, especially with respect to reducing methane leaks. EPA is proposing two control 

measures which are discussed in Section XI. There are additional items discussed in Section XI. 

D. (2) on which we request comment. Included in this list are several control options.

(1) Proposed Control Measures

As is discussed earlier in this preamble in Sections II and XIII. EPA is proposing some 

control measures to reduce potential methane emissions from natural gas vehicles. These are 

summarized here. Note that since these controls are being proposed to address GHG emissions 

rather than fuel consumption, NHTSA is not proposing equivalent requirements. 

(a) Proposed Closed Crankcase Requirement for NG Fueled Engines and Vehicles

EPA is proposing to require that all natural gas engines have closed crankcases, rather 

than continuing the provision that allows compression-ignition engines to separately measure 

and account for crankcase emissions that are vented to the atmosphere. This allowance has 

historically been in place to account for the technical limitations related to recirculating 

crankcase gases with high PM emissions back into the engine’s air intake. Natural gas engines 

have inherently low PM emissions, so there is no technological limitation that would prevent 

manufacturers from closing the crankcase and recirculating all crankcase gases into the engine’s 

air intake. The methane standard that was introduced in Phase 1 of this rule accounts for 

crankcase emissions, but when the system is sealed and emissions are routed to the engine 

intake, those emissions will be considered in determining the deterioration factor. See the 

Preamble Section II. D. for a description of the proposed closed crankcase requirement for 

natural gas fueled engines. This requirement would apply to the manufacturer responsible for 

criteria emission compliance: the vehicle manufacturer for complete pickups and vans, and the 

engine manufacturers for all other vehicles.

(b) Proposal to Require 5 Day Hold Time for LNG vehicles

Boil-off emissions from LNG vehicles were not addressed in the Phase 1 rulemaking. As 

more testing has been done in this area since that time for this rising issue, as described in the 

Preamble Section XII, EPA is proposing to require manufacturers to follow current industry

recommended practice, SAE J2343 for five day hold time to limit boil-off emissions from LNG 

vehicles. The specifications of this safety related standard has an effect which helps new LNG 

vehicles prevent boil-off. This SAE standard will only affect new LNG vehicles. It will not 
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address aging vehicles as their insulating properties diminish such as loosing vacuum over time

and may eventually result in much shorter hold times.

827

EPA proposes to require the certificate holder for the chassis to also comply with the 

proposed requirements for LNG fuel systems, but to apply the delegated assembly and secondary

manufacturer allowances for these requirements. We request comment on this approach 

generally, as well as on: 

 The need for additional requirements for manufacturers not holding certificates, 

such as requiring that fuel system manufacturers participate in recalls for defects 

in their components. 

 The appropriateness of requiring or allowing separate certification of fuel systems 

(or similar provisions) where they are installed by manufacturers not holding the 

certificate for the chassis with respect to CO2 and fuel consumption.

(2) Additional Natural Gas Topics for Comment

In this section we request comment on several additional areas related to potential 

regulatory requirements for natural gas fueled vehicles. See Chapter 13 of the Draft RIA for 

additional details on these topics.

(a) Request for Comment on Changing Global Warming Potential Values in the Credit 

Program for CH4 (see also Preamble Section II.(D)(5)(b))

The phase 1 heavy-duty vehicle rulemaking establishing greenhouse gas emission 

standards included a compliance alternative allowing heavy-duty manufacturers and conversion 

companies to comply with the respective methane or nitrous oxide standards by means of overcomplying with CO2 standards (40 CFR 85.525 (ii)). The heavy-duty rules allow averaging 

only between vehicles or engines of the same designated type (referred to as an “averaging set” 

in the rules). Specifically, the phase 1 heavy-duty rulemaking added a CO2 credits program 

which allowed heavy-duty manufacturers to average and bank pollutant emissions to comply

with the methane and nitrous oxide requirements after adjusting the CO2 emission credits

(generated from the same averaging set) based on the relative GHG equivalents. To establish 

the GHG equivalents used by the CO2 credits program, the phase 1 heavy-duty vehicle 

rulemaking incorporated the IPCC Fourth Assessment Report global warming potential (GWP) 

values of 25 for CH4 and 298 for N2O, which are assessed over a 100 year lifetime.

Since the Phase 1 rule was finalized, a new IPCC report has been released (the Fifth 

Assessment Report), with new GWP estimates. This is prompting us to look again at the relative 

CO2 equivalency of methane and to seek comment on whether the methane GWP used to 

establish the GHG equivalency value for the CO2 Credit program should be updated to those 

 

827 The LNG storage tanks achieve some of their insulating properties due to a vacuum created between the two 

walls of the double-walled LNG storage tank.
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established by IPCC in its Fifth Assessment Report. The Fifth Assessment Report provides four 

100 year GWPs for methane ranging from 28 to 36. Therefore, we not only request comment on 

whether to update the GWP for methane to that of the Fifth Assessment Report, but also on 

which value to use from this report. 

(b) Request for Comment on Appropriate Deterioration Factors for NG Tailpipe Emissions

The current assigned deterioration factors for CO2, N2O, and CH4 are based on diesel 

technology. While EPA still believes this is likely appropriate, we would welcome data to 

support this policy or other comments on how appropriate these factors are applied to NG 

engines and vehicles. 

(c) Request for Comment on LNG Vehicle Boil-Off Warning System

A simple means to help limit boil-off emissions would be to require that natural gas 

truck drivers be alerted to expected near-future boil-off events. Such an alert could be in the

form of a warning light and associated audible alarm that would indicate that the LNG storage 

tank is approaching a pressure which would require the tank to vent. Knowing this, the truck 

driver could take action to prevent such a release, such as starting to drive the vehicle, which 

likely would reduce the pressure in the tank, or connecting the vent line to either a LNG storage 

tank or natural gas pipeline for venting. EPA requests comment on the feasibility and 

appropriateness of a regulatory requirement that LNG fueled vehicles include a warning system 

that would notify the driver of a pending boil-off event as one means reduce the frequency of 

such events and thus limit the release of methane. 

(d) Request for Comment on Extending the 5 Day Hold Time for LNG Vehicles

The specifications of the proposed 5 Day Hold Time SAE 2343 safety related standard 

will only affect new LNG vehicles to prevent boil-off initially and does not address aging 

vehicles as their insulating properties diminish such as loosing vacuum over time that may

eventually result in much shorter hold times. LNG tank manufacturers are further developing 

their technologies for improvement of hold times and reducing boil-off from LNG storage tanks 

on trucks. These improvements can be incorporated by requiring longer hold times. EPA is 

soliciting comment on the ability of these emerging technologies to address an extension of 5 

days to a longer period of time such as 10 days and the ability to achieve the hold times for the 

duration of the vehicle’s useful life.

(e) Capturing and/or Converting Methane Refueling or Boil-off Emissions

We would like input on how effective and feasible the following potential emissions 

control technologies are for achieving longer hold times in LNG vehicles. 

A methane canister using adsorbents such as ANG (adsorbed natural gas) could be added 

to capture the methane which otherwise would be released to the environment during a refueling 

or boil-off event. Once captured, steps could be taken to route the methane to the engine intake 

once the vehicle is operating again, or to take steps to converting the methane to less GHGpotent CO2. 
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Instead of discharging methane to the environment, the methane potentially could be 

burned to CO2 using a burner. Another potential option would be to convert the methane capture 

in a canister to CO2 over a catalyst. 

(f) Request for Comment on Reducing Refueling Emissions

When refueling a natural gas vehicle, methane is vented to the atmosphere. As of Tier 3 it 

is required by EPA to use the ANSI-NGV1-206 standard practice to meet the evaporative 

emissions refueling requirement. Small puffs of up to 200 cc/hr (which equates to 72 grams of 

methane per hour) of leakage are allowed with these tests. Often there is a vent line which carries 

these puffs away from the nozzle interface for safety reasons but is then vented to the 

atmosphere. EPA is requesting comment on ways to eliminate or reduce these losses. If there 

must be allowances for losses, then how can this methane gas be captured during refueling using 

systems that route methane emissions back to the fuel storage tank, whether it is a CNG tank, a 

CNG pipeline or re-liquefying system for LNG. For LNG, in addition to the boil-off issue is the 

recurrence of manual venting at refueling by truck operators. Under high pressure circumstances, 

such as when the vehicle has been sitting for some time period in warmer temperatures, it is 

necessary to decrease the pressure in the fuel tank before new fuel can enter the tank. The 

recommended practice is to transfer the extra vaporized fuel to the gas station or natural gas 

pipeline, but this can take extra time. In some areas it has turned into common practice to just 

vent to the atmosphere to keep the down time at the refueling station to a minimum. In other

areas there is an incentive to reroute the gas into the station storage tank or natural gas pipeline 

with credit towards the fuel purchase. EPA is requesting comment on approaches to reduce 

refueling emissions for LNG vehicles.

(g) On-board Monitoring Requirements for Boil-Off Events and Venting at Refueling 

Onboard diagnostics for engines used in vehicle applications greater than 14,000 lbs 

GVWR are already required to detect and provide a warning for when methane leaks occur due 

to wear of connections and components of the CNG or LNG fuel system (74 FR 8310 February

24, 2009). We are requesting comments on requiring on-board monitoring to track boil-off 

events as well as whether the excess vapors were properly vented to the station storage tanks or 

NG pipeline, or whether the gaseous methane emissions were vented to atmosphere during 

refueling events. Each boil off event has the potential to release on the order of 5,300 – 15,800 

grams of CH4 which translates to 132K – 400K grams CO2 equivalent with a GWP of 25 for 100 

years.

(h) Separate Standards for Natural Gas Vehicles

As described above, the climate impact of leaks and other methane emissions that occur 

upstream of the vehicle can potentially be large enough to more than offset the CO2 benefit of 

natural gas vehicles as measured at the vehicle tailpipe. EPA is considering separate action to 

control these upstream emissions. Nevertheless, we have some concern that the impact of 

upstream emissions for natural gas much higher than for gasoline or diesel fuel because of the 

high Global Warming Potential (GWP) for methane that makes even small leaks of natural gas of 

concern. In this way, natural gas is very different than other alternative fuels. 
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While we are not proposing any provisions to address this, we may consider adopting 

such provisions in the final rule and are asking for comments on this topic. Would it be 

appropriate to adjust the tailpipe GHG emission standard for natural gas vehicles by a factor to 

reflect the life cycle emissions of natural gas vehicles relative to diesel vehicles? For example, if 

we were to determine that the life-cycle climate impacts of natural gas vehicles were 150 percent 

of the tailpipe GHG emissions, while the life-cycle climate impacts of diesel vehicles were 135 

percent of the tailpipe GHG emissions, we could approximate the relative climate impacts by

setting the natural gas tailpipe emission standard 10 percent lower than the diesel tailpipe 

standard. We recognize that there is significant uncertainty is assessing these relative climate 

impacts, and that they could change as new production methods and/or regulations go into effect. 

Thus commenters supporting making such an adjustment are encouraged to address this 

uncertainty. Commenters are also encouraged to address how such an adjustment for GHG 

emissions would impact the closely coordinated EPA and NHTSA heavy-duty Phase 2 program 

including how a potential adjustment for upstream methane emissions for natural gas fueled 

vehicles would impact the coordination of EPA GHG regulations with the NHTSA fuel 

consumption regulations.

E. Dimethyl Ether

Although NAS (2014) focused its recommendations on natural gas, it also discussed 

dimethyl ether (DME), which is a potential heavy-duty truck fuel sourced from natural gas. 

Dimethyl ether has a high cetane number (more than 55), although its energy density is about 60 

percent of that of diesel fuel. Dimethyl ether is a volatile fuel, like liquid petroleum gas, that can 

be stored as a liquid at normal ambient temperatures under moderate pressure. Typical DME 

fuel tanks would be designed to prevent any significant evaporative emissions.

A DME fueled truck is only modestly more expensive than a diesel fuel truck. The fuel 

tank is more expensive than a diesel fuel tank, but much less expensive than an LNG tank since 

it does not need to be heavily insulated. The engine modifications to enable using DME are also 

modest. Because DME does not have carbon-carbon bonds that form particulate matter particles 

during combustion, the particulate filter, which is standard equipment on new diesel trucks, can 

be eliminated. This offsets some of the engine and fuel tank costs.

Although DME is sourced from cheap natural gas, the conversion of natural gas to DME 

and moving the fuel to retail outlets greatly increases the cost of the fuel. DME is more 

expensive than LNG, but still lower in cost than diesel fuel based on the fuel prices in early 

2014. DME is estimated to cost $3.50/ DGE, or $0.30 DGE less than diesel fuel. 

Because there is very little DME use in the U.S. (there is only a very small fleet of trucks 

in California), we did not conduct a lifecycle assessment of DME, but note here a few aspects of 

a lifecycle analysis for DME. First, since DME is sourced from natural gas, the upstream 

methane emissions from the natural gas industry would still be allocated to DME. Second, there 

are not venting issues associated with DME as with LNG or CNG refueling. Third, DME itself 

has a much lower global warming potential than methane. DME’s global warming potential is 

estimated to be 0.3 when assessed over a 100 year lifetime, which is about 1 percent of 

methane’s GWP.
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XII. Agencies’ Response to Recommendations from the National 

Academy of Sciences

A. Overview

As part of the Phase 1 standards, the agencies were informed by a report generated by the 

National Academy of Sciences (NAS), as required by Congress in EISA.828 In addition to that 

initial report, Section 107 of EISA requires that the report be updated in five year intervals 

through 2025.829 On September 24, 2016, NAS will release its updated report under Congress’ 

quinquennial update requirement. However, because the Phase 2 rules will be completed prior to 

the issuance of the first update, NAS issued an interim report in the form of a First Report (NAS 

HD Phase 2 First Report) published on April 3, 2014.830 The agencies have consulted the report 

and considered its findings in creating this proposal. The National Research Council formed the 

Committee on Technologies and Approaches for Reducing the Fuel Consumption of Mediumand Heavy-Duty Vehicles, Phase Two (the Committee or NAS Committee) in order to prepare 

the NAS HD Phase 2 First Report. In its Phase 2 First Report, the Committee seeks to advise 

NHTSA on the HD Phase 2 rules while meeting the agencies’ objectives of: 

 Reducing in-use emissions of carbon dioxide from medium- and heavy-duty vehicles

 Reducing in-use emissions of other GHGs from medium- and heavy-duty vehicles

 Improving the in-use efficiency of fuel use in medium- and heavy-duty vehicles—by

driving innovation, advancement, adoption, and in-use balance of technology through 

regulation

In providing the First Report recommendations, the committee acknowledged the 

following constraints:

 Holding life-cycle cost of technology change or technology addition to an acceptable 

level

 Holding capital cost of acquiring required new technology to an acceptable level

 Acknowledging the importance of employing a balance of energy resources that offers 

national security

 Avoiding near-term, precipitous regulatory changes that are disruptive to commercial 

planning

 

828 Energy Independence and Security Act of 2007, Pub. L. No. 110-140, §108(a).

829 EISA further states that the NAS must submit the report to DOT, the Senate Committee on Commerce, Science, 

and Transportation, and the House Committee on Energy and Commerce not later than one year after the date on 

which the Secretary executed the agreement with the NAS.

830 Transportation Research Board 2014. “Reducing the Fuel Consumption and Greenhouse Gas Emissions of 

Medium- and Heavy-Duty Vehicles, Phase Two.” (“Phase 2 First Report”) Washington, D.C., The National 

Academies Press. Cooperative Agreement DTNH22-12-00389. Available electronically from the National 

Academy Press Website at http://www.nap.edu/catalog.php?record_id=12845 (last accessed December 2, 2014). 
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 Ensuring that the vehicles offered for sale remain suited to their intended purposes and 

meet user requirements

 Ensuring that the process used to demonstrate compliance is accurate, efficient, and not 

excessively burdensome

 Not eroding control of criteria pollutants or unregulated species that may have health 

effects

Although the Phase 2 First Report was developed and written in terms of reducing fuel 

consumption, its findings and recommendations in general apply equally to a program that 

reduces GHG emissions, given the close relationship between the two.

B. Major Findings and Recommendations of the NAS Phase 2 First Report

While the agencies have addressed many NAS recommendations as they pertain to 

individual areas of the Phase 2 standards, this section consolidates all of the recommendations 

from the NAS HD Phase 2 First Report and discusses the extent to which the agencies’ proposed 

program is consistent with them. The NAS HD Phase 2 First Report contains more than 40 

recommendations to the agencies. All of the Committee’s recommendations have been 

considered, and many of them have been incorporated in the Phase 2 standards. In some 

instances, the agencies have chosen a different course from the one charted by the NAS 

Committee’s recommendations. 

Instead of discussing the NAS report findings and recommendations in the order 

presented in the Phase 2 First Report itself, this section divides the NAS findings and 

recommendations in three categories: findings and recommendations with which (1) the Phase 2 

standards are consistent; (2) the Phase 2 Standards are significantly inconsistent; and (3) the 

Phase 2 standards are less-significantly inconsistent. 

(1) NAS Findings and Recommendations with which Phase 2 Standards are

Consistent

(a) How Should the Agencies Address Standards for Trailers in the Phase 2 Rulemaking?

Given the exclusion of trailers from the Phase 1 standards, the Committee focused on a 

wide array of opportunities by which the agencies could reduce fuel consumption and GHG 

emissions. The Committee evaluated potential fuel consumption- and GHG-reducing 

technologies that can be incorporated on a trailer as well as components of a trailer, such as tirerelated technologies. 

The Committee found that many opportunities exist for trailers to reduce fuel 

consumption and GHG emissions of the pulling tractor. More specifically, the Committee 

evaluated trailer aerodynamics, tire rolling resistance, and tire pressure monitoring systems. 
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Despite the fuel consumption- and GHG-reducing possibilities of the trailer technologies 

the Committee evaluated, a survey it conducted found that only 40 percent of new van trailers 

came equipped with fuel-saving aerodynamic devices.831 Further, the Committee found that 

most trailer devices on average, within one year, saved enough in fuel cost to pay for the added 

cost of the device. The Committee observed that when a trailer is not owned by the tractor 

operator, there is no incentive for the trailer owner to purchase fuel-saving devices. Moreover, 

the Committee stated that in absence of regulation, many trailer owners do not choose to employ

fuel saving devices. 

The Committee recommended that NHTSA, in coordination with EPA, adopt a regulation 

requiring that all 53 foot and longer dry van and refrigerated van trailers meet performance 

standards that reduce fuel consumption and GHG emissions.832 It also recommended that 

NHTSA assess the benefit of using GEM to address all tractors in combination with trailers.833 

The Committee also recommended the agencies collect real-world data on fleet use of 

aerodynamic trailers to help inform standards.834

As discussed in more detail in Section IV, the agencies are proposing to adopt Phase 2 

standards for all new dry van and refrigerated van trailers, including both those above and below 

53 feet in length. The agencies have carefully evaluated the lead time for implementation of this 

potential program to take into consideration factors such as existing market conditions and the 

fact that a regulation of new trailers will include companies that have not previously been 

regulated for fuel consumption and GHG emissions. To the degree that it is available, the 

agencies are gathering data on real world fleet use of aerodynamic devices, both to understand 

the overall context of the rules and for specific analytical purposes such as the appropriate role of 

aerodynamic devices on the reference trailer used for tractor aerodynamic assessment. The 

agencies have also assessed the benefit of using GEM to address all tractors in combination with 

trailers and are proposing that, for the long-term program, GEM be used to demonstrate 

compliance with both the tractor and the trailer requirements of the Phase 2 program.

In addition to the Committee’s recommendation that NHTSA and EPA regulate 53 foot 

and longer box trailers, the Committee recommended that NHTSA and EPA assess the 

practicability and cost-effectiveness of including pups, flat-beds, and container chassis.835 The 

Committee found that pups, flat-beds, and container chassis demonstrated fuel savings, however, 

factors such as average speed, mileage, and practical concerns such as access to equipment 

underneath the trailer needed to be assessed.836 

The agencies have evaluated whether it would be practical and cost effective to include 

pups (in tandem or separately), other box trailers of lengths between that of pups and standard 

 

831 See Note [2] at 38. 

832 Id., Recommendation 6.1. 

833 Id., Recommendation 3.12.

834 Id., Recommendation 6.1. 

835 Id., 6.2.

836 Id. at 83. 
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53-foot trailers, flatbeds, container chassis (with and without containers attached), tankers, and 

other trailer types in the Phase 2 regulation. As a result of this analysis, the agencies are 

proposing to include pups as well as box vans between 28 feet and 53 feet long in Phase 2. With 

regard to other types of trailers, such as tankers, flatbeds, and container chassis, the agencies 

have evaluated issues such as trailer plumbing, flat bed ground clearance, chassis stacking, trailer 

duty cycles, cost of technologies, and other issues. The agencies are proposing that these and 

other non-box trailers be included in Phase 2 requirements. However the agencies are assuming 

compliance with the Phase 2 program for these non-box trailers will be limited to tire 

technologies. 

Finally, the Committee examined the use of GEM for tractor and trailer compliance. It 

asserted that tractors and trailers are fundamentally inseparable when addressing aerodynamic 

drag and design. As applied to GEM simulation, the Committee opined that considering tractors 

and trailers separately for simulation purposes might prove counterproductive, because 

components on a tractor and trailer might compromise aerodynamic optimization. The 

Committee recommended that NHTSA assess the benefit of using GEM to address all tractors in 

combination with trailers.837

As stated above, the agencies have assessed the benefit of using GEM to address all 

tractors in combination with trailers and are proposing to use GEM for both tractors and trailers 

for the Phase 2 program for tractors and trailers, similar to what was done in Phase 1. In Phase 

1, which did not regulate trailers, this meant simulating each tractor being certified as being used 

in combination with a standard reference trailer. For these rules, we are proposing to simulate 

each trailer being certified as being used in combination with a standard reference tractor. 

(b) Have the Agencies Revisited Dieselization of Class 2b Through 7 Vehicles? 

The Committee reiterated a recommendation from its Phase 1 report regarding the study 

of dieselization of Class 2b through 7 vehicles.838 The Committee stated that diesel engines 

present an opportunity for incremental fuel efficiency gains. The NAS Committee recommended 

that NHTSA conduct a study of Class 2b to 7 vehicles to consider the incremental fuel 

consumption reduction of diesels, the price of diesel versus gasoline, and the diesel advantage in 

durability.

839

As part of the Phase 2 NPRM analysis, the agencies evaluated many potential fuel 

efficiency and greenhouse gas reduction (FE/GHG) technologies for both gasoline and diesel 

fueled vehicles. As will be discussed in detail in later responses, NHTSA sponsored research at 

Southwest Research Institute (SwRI) included simulations of baseline and projected Phase 2 

 

837 Id. at 38, Recommendation 3.12. 

838 Id. at 14-15. 

839 Id. 
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FE/GHG technologies for Class 2b through 7 vehicles over a range of appropriate duty cycles.840

A HD pickup truck (Class 2b), the Dodge Ram 2500, was modeled using a 385-hp 6.7-liter 

diesel engine as the baseline. The vehicle’s baseline performance and the effectiveness of 

FE/GHG technologies with the diesel engine were compared over identical duty cycles to two 

gasoline engines, a 6.2-liter naturally aspirated gasoline V-8 and 3.5-liter turbocharged direct 

injection V-6, with their corresponding engine technologies. Similarly, two medium-duty trucks 

(Class 6), the Ford F-650 and Kenworth T-270, were modeled using a 300-hp 6.7-liter diesel 

engine as the baseline and compared to the two aforementioned medium-duty V-8 and V-6 

gasoline engines. 

Many of the diesel engine technologies evaluated in supporting Phase 2 research are 

currently available, proven, and on the path to increased penetration across the fleet. Other 

technologies are still in development and looking for the opportunity to enter the mainstream 

production lifecycle. For the latter, the agencies believe, as informed through the NPRM 

development research, that costs, reliability, durability, and clear user benefits are important 

when determining potential future technology applications to achieve attainable standards 

resulting in real-world reductions. As identified in the proposal, the agencies considered these 

important factors when developing the proposed standards and, included in the analysis, are 

technologies that recognize the value of the current and future fleet dieselization.

However, the agencies recognize that there are valid reasons for why medium and heavyduty vehicle purchasers sometimes choose gasoline engines over diesels. Gasoline engines are 

generally lighter and less expensive than diesels, although they typically do not last as long in 

heavy-service. For applications in which the vehicle is not expected to travel many miles each 

year, gasoline engines may be the best choice. On the other hand, for applications in which the 

vehicle is expected to travel many miles each year, diesels can be a more appropriate choice.

(c) What Kind of Analyses are the Agencies Doing on Upstream Emissions Related to Natural 

Gas?

The NAS Committee discussed the potential natural gas presents for reducing fuel 

consumption and GHG emissions in medium- and heavy-duty vehicles. The Committee stated 

that while tailpipe emissions are often the most observable instance of fuel consumption and 

tailpipe emissions, the fuel production, distribution, and processing components of obtaining 

natural gas for use in vehicles also factors into any calculation of overall benefits derived from 

natural gas vehicles.841 The Committee recommended that NHTSA, in coordination with EPA, 

begin to consider the well-to-wheel, life-cycle energy consumption and greenhouse emissions 

associated with different vehicle and energy technologies to ensure future rulemakings best 

accomplish their overall goals.842

 

840 Reinhart, Thomas. (2015, XXXXXX). Commercial Medium- and Heavy-Duty (MD/HD) Truck Fuel Efficiency 

Technology Study – Report #1. (Report No. DOT HS 8XX XXX). Program Reference: DOT Contract DTNH22-12-

F-00428. Contract Prime: Southwest Research Institute (SwRI).

841 Id. at 19-20.

842 Id. at 20, Recommendation 1.10.
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The agencies recognize that understanding the life-cycle implications of vehicle and 

energy technologies is important to ensure that the rulemaking accomplishes its overall goals. In 

the Draft and Final Environmental Impact Statement (EIS) prepared for the 2017 and Later 

Model Year Light-Duty Vehicle GHG Emissions and CAFE Standards rulemaking, NHTSA 

introduced a literature synthesis of life-cycle environmental impacts of certain vehicle materials 

and technologies. Consistent with that approach, in the Draft EIS for Phase 2, NHTSA has again

provided a literature synthesis of life-cycle environmental impacts, focusing on the unique 

vehicle technologies for the HD sector and incorporating by reference the literature synthesis 

prepared for the MY 2017 and beyond CAFE Final EIS. The Draft EIS also uses the GREET 

fuel-cycle model to assess upstream emissions from extraction, refining, and transportation of 

medium- and heavy-duty vehicle fuels. This information in the Draft EIS informs both the 

agency and the public about the potential life-cycle implications of the various technologies 

under consideration in this rulemaking. NHTSA invites comments on the Draft EIS and its 

literature synthesis of life-cycle environmental impacts.

EPA has also evaluated the lifecycle impact of heavy-duty trucks being fueled with 

natural gas in comparison to other heavy-duty trucks. This analysis is presented in Section XI 

along with a discussion of projections for future use of natural gas by heavy-duty trucks. 

(d) How Have the Agencies Evaluated Aerodynamic Testing Methods for the Phase 2 

Program? 

With regard to aerodynamic devices, the NAS Committee reviewed aerodynamic test 

procedures related to evaluating aerodynamic effectiveness. The Committee found that industry 

testing procedures can vary widely because of the precision of the standards themselves.843 

Further, the Committee found that fidelity of test results from coastdown procedures versus 

results from a powered on-track test is not known. The Committee recommended that NHTSA 

and EPA evaluate the relative fidelities of the coast-down procedure and candidate powered 

procedures to define and optimum prescribed full-vehicle test procedure and process and validate 

the improved procedure against real world vehicle testing.844 It also recommended that NHTSA 

and EPA assess whether adding yaw loads provides significantly increased value to the Cd 

result. The Committee recommended providing updated test data to manufacturers to increase 

consumer confidence in the accuracy (and real-world applicability) of the testing measures as 

related to aerodynamic devices.845,846 

The agencies have undertaken a coordinated research program to inform the Phase 2 

certification test procedure for aerodynamic drag and tire rolling resistance. The U.S. EPA and 

its contractors have evaluated coastdown, constant speed, CFD, and scale wind tunnel testing for 

tractors and trailers. The goals of this research effort were to: assess variability between test 

methods; assess how yaw impacts aerodynamic performance; evaluate correlation of different 

 

843 Id. at 83-84.

844 Id. at 84, Recommendation 6.3. 

845 Id. at 36, Recommendation 3.5. 

846 Id. at 84, Recommendation 6.3. 
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test methods one to another; assess the impact of different tractor/trailer design attributes on the 

test results; examine how differences between manufacturers’ products impact aerodynamics; 

and measure Cd improvements from a variety of aerodynamic devices in combination and alone. 

NHTSA and its contractors conducted simulation modeling to: evaluate aerodynamic drag and 

tire rolling resistance improvements in combination with other vehicle and engine technologies, 

and determine the impact of different duty cycles on aerodynamic drag performance. Finally, 

EPA has conducted an analysis to determine whether or not adding yaw adjustments to the 

certification process improves the Cd result. As a result, the agencies are proposing to add yaw 

adjustments to the certification process for tractors. The agencies are disseminating the results of 

these test programs and conclusions at association meetings and public meetings such as SAE 

COMVEC. 

Through the research programs described above, the agencies have evaluated 

aerodynamic data that better reflects real-world experience. And, to the extent available, the 

agencies have collected aerodynamic performance data that reflect real-world experience. This 

information has informed the Phase 2 proposal. For example, in addition to the agencies are 

proposing to account for yaw in the aerodynamic assessment for Cd, we are also proposing 

changes to vehicle speeds used in the aerodynamic reference test procedure to facilitate 

improved estimation of Cd. 

(e) What Kind of New Modeling Research has Been Conducted to Inform Phase 2? 

With a wide range of potential fuel consumption- and GHG emissions reducing 

technologies, the NAS Committee found that it is proper to assess the various combinations of 

technologies in real-world testing and in modeling. The Committee recommended that NHTSA 

conduct detailed simulation modeling in addition to physical testing.847 

In September 2012, NHTSA contracted with the Southwest Research Institute (SwRI) to 

conduct research in support of the next phase of Federal fuel efficiency (FE) and GHG 

standards.848 Tasks included determining the baseline fuel efficiency and emissions levels and 

technologies of current model year commercial medium- and heavy-duty on-highway vehicles 

and work trucks, as well as projections of Phase 2 fuel efficiency and emission reduction 

technologies for diesel and gasoline powered vehicles. The scope encompassed technologies for 

chassis and final-stage manufacturer vehicles and trailers, maintenance cost, material application, 

future design, capital investment, retail cost/payback and any other applicable advanced 

technologies. Estimates of the costs, fuel savings effectiveness, availability, and applicability of 

technologies were done for each individual vehicle class category (e.g., segment). 

Selection of FE/GHG technologies, engines, vehicles, drive-cycles, etc. for the simulation 

modeling at SwRI was done in coordination with EPA, which had complimentary HD research 

programs involving vehicle road testing and engine dynamometer testing that informed the 

 

847 Id. at 24, Recommendation 2.1. 

848 Id. 
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simulation efforts. The SwRI analysis relied on a technology list that was developed from recent 

NAS HD vehicle fuel consumption reports as well as an extensive literature review. Four base 

engines and four vehicles spanning the class 2b to class 8 vehicle segments were selected for 

simulation. Experimental data was available from other projects for all of the vehicles and 

engines simulated, and full use of experimental data was made to calibrate the models before 

additional technologies were evaluated. 

SwRI used a vehicle simulation tool developed in-house to model vehicle performance 

over a range of drive cycles. The commercial software GT-POWER (Gamma Technologies, 

Inc.) was used to model engine performance, fuel consumption, and CO2 emissions over the full 

speed-load range. Results of the agency-sponsored simulation modeling at SwRI will be issued 

in peer-reviewed research reports.

(f) How has GEM been Modified by EPA? 

In its report, the NAS Committee focused many of its recommendations on EPA’s GEM . 

The Committee concentrated on what features could be incorporated into GEM in order to 

improve the model’s ability to provide outputs representative of real-world use. 

More specifically, the Committee found that GEM output was unaffected by the actual 

use of a smaller or larger engine in the same subcategory because the engine map used by GEM 

is predefined.849 The NAS Committee recommended that the agencies should assess whether a 

single steady-state speed-torque map is sufficient for GEM accuracy in engine efficiency

prediction.850 EPA has evaluated this question and is modifying GEM to allow for different 

maps as an input. 

Additionally, the Committee emphasized that a certification test must be highly accurate 

and repeatable. It stated that the need to account for the close interaction of the engine with 

other components, including the aftertreatment subsystem and transmission.851 NAS

recommended that the agencies allow powertrain testing for certification. 852 As described in 

Section II, the agencies are doing so in conjunction with GEM. See the proposed provisions in 

40 CFR1037.550, which further discusses powertrain testing and certification.

More generally, the NAS Committee recommended revising GEM to reflect the benefit 

of integrating an engines, aftertreatment, and transmissions and to cover as large a fraction of 

over-the-road tractor operation as possible without becoming overly cumbersome.853 As 

described in Section II and in Chapter 4 of the draft RIA, the agencies believe the proposed 

revisions to GEM reflect this. 

 

849 Id. at 37. 

850 Id., Recommendation 3.8. 

851 Id. at 14. 

852 Id, Recommendation 1.6. 

853 Id. at 37, Recommendations 3.10, 3.11. 
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(g) What have the Agencies Done to Validate GEM Testing?

The NAS Committee expressed concern over GEM’s ability to translate to real world 

reductions in fuel consumption and GHG emissions. In particular, the Committee found that 

GEM’s current certification procedures have limited unbound variables that can be userspecified and do not allow for synergy between components.854

 Moreover, the NAS Committee 

found that GEM does not allow for the operation of components in the most efficient way or 

efficiency that could be gained by the operation of a component at a higher relative load, 

concluding that vehicle designs that are optimized for the conditions of the simulation might not 

be optimized in real world operation. 855 The Committee recommended that NHTSA conduct a 

real world evaluation to validate GEM inputs with the fuel consumption outputs.856 

Additionally, it recommended that EPA and NHTSA should assess whether a steady-state torque 

map is sufficient for GEM accuracy in engine efficiency prediction.857 

Recently, EPA and NHTSA sponsored a technical workshop at the Southwest Research 

Institute (SwRI). At this workshop, SwRI presented a multi-year research effort sponsored by

EPA to validate GEM. The development version of GEM incorporates several engine, 

transmission, driveline, and vehicle technologies being considered to meet FE and GHG 

standards for MD/HD vehicles. GEM (including the steady-state fuel map approach) was 

validated by the agencies against over 130 test cases (multiple runs) of different size vehicles. 

See Section II of this notice and Chapter 4 of the draft RIA for further information about this 

validation work.

(h) Has NHTSA Considered Non-Vehicular Strategies to Reduce Fuel Consumption?

In examining the broader picture of reducing fuel consumption, the NAS Committee 

found that there are opportunities to reduce fuel consumption in ways that that exceed NHTSA’s 

statutory authority.

858

 The Committee recommended that NHTSA work with and encourage 

EPA, DOE, and FHWA to reduce fuel consumption and GHG emissions by exploring nonvehicle approaches.859

NHTSA is jointly releasing this rulemaking with EPA, and has involved EPA as a codrafter throughout the development of these rules. NHTSA has also worked with DOE, and has 

been in touch with FHWA about medium- and heavy duty fuel efficiency. While the majority of 

NHTSA’s work with these agencies has been vehicle-related, NHTSA supports research and 

development on nonvehicle methods to reduce fuel consumption. 

 

854 Id. at 11. 

855 Id. 

856 Id., Recommendation 1.2. 

857 Id. at 37, Recommendation 3.8. 

858 Id. at 15. 

859

 Id., Recommendation 1.9. 
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(2) NAS Findings and Recommendations with Which the Phase 2 Standards Are 

Significantly Inconsistent and Why the Agencies Chose a Different Course

(a) Should the Agencies Propose Separate Standards for Natural Gas Vehicles? 

The NAS Committee found that natural gas is a viable option to reduce fuel consumption 

and can also contribute to a reduction in GHG emissions, “unless additional findings of methane 

leakage alter this vision.”860 It noted that natural gas engines are well-developed and are ready

for use for medium- and heavy-duty vehicles, including Class 8 trucks. The Committee stated 

that while the load-specific CO2 emissions from natural gas engines are less than a comparable 

diesel engine, that benefit is partially negated by lower engine efficiency and methane 

emissions.861 The NAS Committee recommended that NHTSA and EPA develop a separate 

standard for natural gas vehicles, similar to that in diesel- and gasoline-fueled engines. 862 We 

interpret this to mean standards that require natural gas-fueled engines to achieve similar thermal 

efficiency to diesel- and gasoline-fueled engines; in other words more stringent standards than 

would apply under a continuation of the Phase 1 approach. Further, the Committee 

recommended the agencies do this without disrupting commercial transportation business 

models, though the Committee did not provide specific recommendations for how to achieve this 

goal.863 It recommended that GEM certification tools need to include natural gas engine maps to 

accurately quantify the emissions and fuel economy of natural gas vehicles. The Committee also 

requested that EPA and NHTSA assemble a best estimate of well-to-tank GHG emissions to be 

used for developing future rulemakings.864 

The agencies closely evaluated the recommendation for NHTSA and EPA to develop a 

separate natural gas standard for HD vehicles. The agencies are not proposing a separate 

standard for natural gas engines or for natural gas powered vehicles for the Phase 2 program 

primarily, because the current market share is still at or below one percent of the total heavy-duty 

fleet and we do not project a significant increase in natural gas use during the Phase 2 timeframe. 

Given its current status, we do not want to inhibit the adoption of this potentially promising 

alternative fuel through more stringent standards. Other reasons to hold back on potentially 

establishing separate natural gas fuel standards at this time include the fact that there is 

uncertainty in the quantification of methane emissions, both upstream emissions as well as 

potential leakage on a vehicle, particularly the LNG vehicle boil-off emissions, which makes it 

very difficult to perform a rigorous analysis regarding the potential impacts of a separate natural 

gas standard; the industry itself is in the process of developing its technology and as it matures 

there is potential for self-correction to address methane leaks in recognition of environmental 

concerns that might affect its status as a potential green alternative fuel. 

 

860 Id. at 65.

861 Id. 

862 Id. at 65, Recommendation 5.2. 

863 Id. at 65, Recommendation 5.3.

864 Id. at 65, Recommendation 5.1. 
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With regard to well-to-tank or upstream emissions, the medium- and heavy-duty fuel 

efficiency program focuses on the tailpipe emissions of these vehicles for multiple reasons, 

including test measurement capabilities and the use of simulated output tools calibrated to test 

lab measurements. The agencies continues to evaluate the potential impacts and the benefits of a 

holistic approach for incorporating well-to-tank emissions into future rulemakings. 

As data comes available a better estimate can be made on the emissions impact from any 

potential regulations. The agencies will closely monitor developments in natural gas adoption 

over the course of the rulemaking timeframe and determine if additional action may be necessary

to prevent methane emissions increases. See Section XI of this preamble for additional 

discussion regarding the treatment of natural gas fuel, engines and vehicles in this proposal, as 

well as for a detailed discussion of lifecycle emissions.

(b) How are the Agencies Handling Uniformity and Accuracy Regarding Tire Rolling 

Resistance Characteristics? 

The NAS Committee expressed concern about the process by which rolling resistance 

values are established.865 Specifically, the Committee noted that the process for determining tire 

rolling resistance is new and variability is not as well known. The Committee recommended that 

the agencies implement a mechanism for obtaining accurate tire rolling resistance factors, 

including establishing a tire alignment laboratory.

866,867

 Additionally, the Committee 

recommended that this data be available in the through the Uniform Tire Quality Grading 

system.868 

In Phase 1, the agencies received comments from stakeholders highlighting a need to 

develop a reference lab and alignment tires for the HD sector. The agencies noted the lab-to-lab 

comparison conducted in the Phase 1 EPA tire test program. The agencies reviewed the rolling 

resistance 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 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 

rolling resistance values. Based on the test data, the agencies judge that it is reasonable to 

continue the HD Phase 2 program with current levels of variability, and consider the use of either 

Smithers or STL laboratories to be acceptable for determining the tire rolling resistance value in 

Phase 2. Note that the agencies have not made similar findings for other laboratories. However, 

we welcome comment on the need to establish a reference machine for the HD sector and 

interest from tire testing facilities to commit to developing a reference machine.

 

865 Id. at 35-36.

866 Id. at 36, Recommendation 3.4, 6.6 p 84.

867 Id. at 84, Recommendation 6.6.

868 Id. at 36, Recommendation 3.4.
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In the final rule for the Phase 1 program, the agencies stated that compliance values 

submitted to the agencies should be derived using the ISO 28580 test method for drive tires and 

steer tires planned for fitment to the vehicle being certified.869 The agencies believe that 

following a defined, standardized test procedure will provide levels of consistency in submitted 

compliance values. The agencies conducted substantive testing to develop the final tire Crr 

standards in the Phase 1 rule at two different testing laboratories for comparison to test for 

variability. The agencies concluded that although laboratory-to-laboratory and test machine-totest machine measurement variability exists, the level observed is not excessive relative to the 

distribution of absolute measured Crr performance values and relative to the proposed standards. 

Based on this, the agencies concluded that the test protocol and the proposed standards are 

reasonable for this program.

The agencies are considering publishing the tire Crr levels from fuel efficiency and GHG 

emission program compliance data. Because compliance data are submitted by vehicle 

manufacturers rather than directly from the tire manufacturers or agency directed testing they

could vary for a given tire model among vehicle manufacturer submissions, or lag when tires are 

redesigned. Based on considerations such as this, the agencies are not proposing to establish a 

public database for heavy-duty vehicle tire rolling resistance information at this time. 

(c) Have the Agencies Considered Industry Standards for Medium- and Heavy-Duty Tire 

Pressure Systems (TPS)? 

The NAS Committee found that tire pressure monitoring systems and automatic tire 

inflation systems are being adopted by fleets at an increasing rate.870 However, the Committee 

noted that there are no standards for performance, display, and system validation. The 

Committee recommended that NHTSA issue a white paper to clarify the minimum performance 

needed from these systems from a safety perspective.871 This recommendation addresses the 

effects of tire pressure systems on vehicle safety. Because the recommendation for a white paper 

relates to safety, and is not directed at fuel efficiency or GHG emissions effects, the agencies are 

not responding to the NAS recommendation in this proposal.

Nevertheless, the agencies note that automatic tire inflation systems can improve fuel 

efficiency and greenhouse gas emissions (see Preamble Section III / draft RIA Chapter 2) by 

maintaining tire pressure close to the tire pressure specification. The agencies are proposing to 

recognize automatic tire inflation systems as a technology that improves fuel efficiency for 

tractors, trailers and vocational vehicles in the GEM vehicle compliance model. 

 

869 76 FR 57182-85. 

870 Phase 2 First Report at 84.

871 Id., Recommendation 6.4. 
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(d) Will NHTSA Survey Private Fleets or Leverage Government Fleets to Gather Information 

for the Phase 2 Rulemaking? 

In its report, the NAS Committee found that there are many additional methods by which 

NHTSA could gather fleet information to inform the Phase 2 rulemaking. The Committee 

recommended that NHTSA gather data from private fleets, and work with the General Services 

Administration or United States Postal Service to evaluate the fleet of vehicles they

possess.872,873

NHTSA understands that additional fleet information could be helpful for purposes of 

formulating medium- and heavy-duty fuel efficiency standards. Due to the length of time 

necessary to capture useful, relevant data from fleets, NHTSA was unable to conduct public or 

private fleet studies to inform this rulemaking. NHTSA will take these recommendations under 

advisement to inform the agency in the future. For the time being, the agencies have utilized 

data from FHWA, EPA’s SmartWay program, Polk, and other sources of fleet information. 

(e) GEM Inputs and Outputs

The NAS Committee found that GEM Version 2.0.1 is not compatible with automated 

order entry systems of OEMs.874 It recommended that the GEM programmers configure GEM to 

be compatible with existing OEM order entry systems875 and provide a more useful output that 

includes graphs and other presentation methods.876 However, EPA believes these 

recommendations are beyond the scope of this rulemaking. 

(f) OEM-Specific Code

The NAS committee stated models should be capable of simulating real-world 

component behavior, and should not be oversimplified.877 It recommended allowing OEMs to 

substitute OEM-specific models or code for the fixed models in the current GEM, including 

substituting a power pack (the engine, aftertreatment, transmission).878 However, as described in 

Section II, we are not proposing to allow this for a number of reasons. NAS explained that its 

goal was to reflect real-world operation accurately. We believe the powertrain test option could 

be used to achieve this goal. 

 

872Id. at 43, Recommendation 4.2, 4.3, and 4.4. 

873 Id. at 11, Recommendation 1.3. 

874 Id. at 35. 

875 Id., Recommendation 3.2.

876 Id., Recommendation 3.3. 

877 Id. at 37. 

878 Id., Recommendation 3.7. 
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(3) NAS Findings and Recommendations with Which the Phase 2 Standards Are 

Less-Significantly Inconsistent 

(a) What are the Agencies Doing with Respect to Fuel Specifications for Natural Gas?

The Committee found that natural gas provides a potential long-term price advantage 

backed by an abundant supply.

879

 In addition to its other natural gas (NG) -specific 

recommendations, the Committee recommended government and the private sector should 

support further technical improvements in engine efficiency and operating costs, reduction of 

storage costs, and emission controls (as is done for diesel engines). 880 Further, it recommended 

that NHTSA and EPA should also evaluate the need for and benefits and costs of an in-use NG 

fuel specification for motor vehicle use.

The agencies recognize the value in evaluating an in-use NG fuel specification for motor 

vehicle use. EPA has developed and promulgated fuel specifications for other motor vehicle fuel 

types, both for test fuels and for in-use fuels. Such fuel specifications established by EPA 

usually complement fuel specifications established by third party organizations such as ASTM. 

EPA has established fuel specifications for natural gas used as test fuels for emissions 

testing,881 but has not adopted specifications for in-use natural gas used as a motor vehicle or 

off-highway fuel. However, states have set natural gas quality limits on the natural gas sold 

within the state, and natural gas pipelines have established specifications for the natural gas 

either for their own purposes or to ensure that the natural gas being transported by its pipeline 

will be usable within the states to which the pipeline transports the natural gas. These 

specifications would apply to natural gas used as a motor vehicle fuel.

EPA may consider establishing in-use specifications for natural gas used as a motor

vehicle or off-highway fuel in the future. However, because natural gas use within the 

transportation sector is currently so small (less than 1 percent of total natural gas demand and 

less than 1 percent of heavy-duty fuel demand), its use for transportation would not have a 

separate fuel supply system, and it would not make sense that such a small user segment should 

dictate fuel quality for the overall fuel supply. Like other potential regulations that EPA might 

consider, EPA will consider establishing fuel quality regulations on natural gas if and when its 

use increases as a fuel for the transportation sector.

(b) Have the Agencies Considered Low Rolling Resistance Standards for All New Tires? 

With regard to low rolling resistance tires, the NAS Committee found that 70 percent of 

new tires sold in 2012 were for replacement of existing tires.882 It found that although most new 

 

879 Id. at 65. 

880 Id., Recommendation 5.4. 

881 EPA set natural gas test fuel quality for light-duty and heavy-duty engines in 1994 (40CFR 86.113-94 and 

86.1313-94, respectively), and for nonroad engines in 2002 (40CFR 1065.715).

882 Id. at 84.
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tractors and trailers come equipped with SmartWay verified tires, only 42 percent of replacement 

tires are SmartWay verified.883 The Committee recommended that NHTSA and EPA evaluate 

rolling resistance of new tires, especially those sold as replacements.884 It recommended that 

NHTSA adopt a regulation establishing a low rolling resistance standard for all new tires 

designed for tractor and trailer use.885 

The agencies are proposing to include low rolling resistance tires as a technology that 

may be used for compliance for fuel efficiency and GHG standards. The agencies conducted tire 

rolling resistance testing and considered confidential business information data provided by 

several tire manufacturers, which is discussed in Preamble Sections III, IV, and V and draft RIA 

Chapter 2. The agencies have focused our resources and attention to develop standards for new 

vehicles and engines. NHTSA has not conducted work to consider a rolling resistance 

performance standard for replacement tires at this time and will take the Committee’s 

recommendation under advisement. 

(c) Have the Agencies Considered A Protocol for Measuring And Reporting the Coefficient of 

Rolling Resistance to Aid In Consumer Selection? 

The Committee recommended that the agencies consider establishing a protocol for 

measuring and reporting the coefficient of rolling resistance to aid in consumer selection, similar 

to passenger car tires.886 At this time, the agencies are taking the Committee’s recommendation 

under advisement. 

(d) What Other Revisions Are the Agencies Making to GEM?

Consistent with the NAS Committee’s recommendations, the agencies are proposing to 

make the following revisions to GEM, as also detailed Preamble Section II:

Allowing manufacturers to input parameters related to engines, transmissions, and axles

 Basing GEM on a steady-state fuel map

 Allowing separate fuel maps for alternative fuels

 Including real-world road grade to highway cycles

 Use of wind-average drag coefficients for aerodynamic inputs

However, the agencies are not making other changes recommended by NAS. We are not making 

the user interface changes recommended by the Committee on behalf of manufacturers. Our 

recent discussions with manufacturers indicate that they have adopted ordering systems that are 

consistent with the current interface. We are also not revising GEM to allow manufacturers to 

 

883 Id. 

884 Id., Recommendation 6.5. 

885 Id. 

886 Id. at 14, Recommendation 1.8. 
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input their own shift strategies. Instead, we are proposing a powertrain test option that would 

serve the same purpose.

The NAS Committee also recommended that we broaden GEM to allow for additional 

duty-cycles and actual vehicle weights. We believe that such changes would not significantly 

improve the overall program, but would add significant complexity. 

(e) Vehicle Weight and Payload In GEM

The NAS Committee recommended that NHTSA evaluate the load specific fuel 

consumption (LSFC) at more than one payload to ensure there is not an undesirable acute 

sensitivity to payload by a particular truck power train and to reflect the fact that some states 

allow vehicles to operate with gross combination vehicle weight ratings well in excess of the 

values adopted for the simulation. NAS also recommended that GEM allow manufacturers to 

input actual vehicle weights.887

As described in Section III, the agencies are proposing to modify GEM to allow heavyhaul vehicles to be certified separately, to reflect their unique weight and payload attributes. 

However, are not proposing to allow for other payloads or weights to minimize complexity

during the compliance process. 

(f) Is NHTSA Conducting Any Campaigns Related to Fuel Efficient Driving Behaviors?

In the NAS Committee’s Phase 1 report,888 the Committee concluded that fuel saving 

opportunities exist if drivers are educated about fuel efficient driving techniques.889 The Phase 2 

reiterated this finding, and recommended NHTSA encourage and incentivize the dissemination 

of information related to the relationship between driver behavior and fuel savings.890 

Based on NHTSA’s understanding of the medium- and heavy-duty segments, a large 

portion of the vehicles are driven professionally. Professional drivers operate these vehicles as 

independent drivers and in trucking fleets. In some instances, particularly larger fleet operations, 

management will track and encourage driver fuel efficiency. It is not uncommon for 

professional drivers across all types of trucking operations to undergo private fuel efficiency

training. For these reasons, NHTSA has not yet undertaken dissemination of information related 

to the relationship between driver behavior and fuel savings. 

 

887 Id. at 9, Recommendation 1.1. 

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

Council; Transportation Research Board (2010). ‘‘Technologies and Approaches to Reducing the Fuel Consumption 

of Medium- and Heavy-Duty Vehicles,’’ (‘‘NAS Report’’), at page 9. Washington, DC, The National Academies 

Press. Contract DTNH22–08–H–00222. Available electronically from the National Academy Press Web site at

http://www.nap.edu/catalog.php?recordid=12845 (last accessed September 10, 2014).

889 Id. at 177. 

890 Phase 2 First Report at 14, Recommendation 1.8. 
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XIII. Amendments to Phase 1 Standards

The agencies are proposing revisions to the regulatory text specifying test procedures and 

compliance provisions used for Phase 1. For the most part, these amendments would apply

exclusively to the Phase 2 rules. In a few limited instances, the agencies are proposing to apply

some of these changes to Phase 1. These limited changes to the Phase 1 program are largely 

conforming amendments, and are described below, along with other proposed minor changes to 

the Phase 1 compliance program. We note, however, that we are not reopening the Phase 1 rules 

in a general sense, nor are we requesting comment on the stringency of the Phase 1 standards or 

other fundamental aspects of the Phase 1 program.

A. EPA Amendments

(1) Pickups and Vans

EPA is proposing to relocate the GHG standards and other regulatory provisions for 

chassis-certified HD pickups and vans in the Code of Federal Regulations from 40 CFR 

1037.104 to 40 CFR 86.1819. Accordingly, NHTSA will modify any of EPA’s references in 49 

CFR 523 and 535 to accommodate the migration. EPA is making this change largely to address 

ambiguities regarding the application of additional provisions from 40 CFR part 86, subpart S, 

for these vehicles. The approach in 40 CFR 1037.104 was to state that all of 40 CFR part 86, 

subpart S, applies except as specified in 40 CFR 1037.104; however, the recent standards 

adopted for light-duty vehicles and light-duty trucks included several changes to 40 CFR part 86, 

subpart S, that should not apply for chassis-certified HD pickups and vans. Based on our 

experience implementing the Phase 1 program, we believe it is appropriate to include the GHG 

standards for chassis-certified HD pickups and vans in the same part as light-duty vehicles (40 

CFR part 86, subpart S). All other certification requirements for these heavy-duty vehicles—

criteria exhaust standards, evaporative and refueling standards, provisions for onboard 

diagnostics, and the range of certification and compliance provisions—are in that subpart. We 

note that we have not experienced the same challenges for other heavy-duty vehicles, and are 

therefore not proposing to relocate the other provisions of 40 CFR part 1037.

This migration has highlighted a few areas where we need to clarify how the regulations 

apply for chassis-certified HD pickups and vans. In particular, EPA is proposing to make the 

following changes:

 Clarify that the GHG standards apply at high-altitude conditions

 State that fleet-average calculation of carbon-related exhaust emissions (CREE) is not 

required for chassis-certified HD pickups and vans

 Clarify that requirements related to model types and production-weighted average 

calculation apply on any passenger automobiles and light trucks

 State that the credit and debit provisions of 40 CFR 86.1865-12(k)(5) do not apply for 

chassis-certified HD pickups and vans

 Clarify that the Temporary Lead Time Allowance Alternative Standards in 40 CFR 

86.1865-12(k)(7) do not apply for chassis-certified HD pickups and vans
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 State that the early credit provisions of 40 CFR 86.1866-12, 86.1867-12, 86.1868-12, 

86.1869-12, 86.1870-12, and 86.1871-12 do not apply for chassis-certified HD pickups 

and vans

(2) Heavy-Duty Engines

As described in Section II, EPA is proposing to revise the approach to classifying 

gaseous-fuel engines with respect to both GHG and criteria emission standards. This does not 

affect the vehicle-based standards that apply under 40 CFR part 1037. The general approach 

would be to continue to divide these engines into spark-ignition and compression-ignition 

categories, but we propose to always apply the compression-ignition standards to gaseous-fuel 

engines that qualify as medium heavy-duty or heavy heavy-duty engines. Currently, any

gaseous-fuel engine derived from a gasoline engine would be subject to the spark-ignition 

standards no matter the weight class of the vehicle. As described in Section II, EPA now 

believes this approach does not reflect the reality that gaseous-fuel engines used in Class 6, 7, or 

8 vehicles compete with diesel engines rather than gasoline engines. Such engines compete 

directly with diesel engines, and we believe they should be required to meet the same emission 

standards. Because all current gaseous-fuel engines for these large vehicles are already being 

certified to the compression-ignition engine standards we can propose to also apply this approach 

to engines subject to the HD GHG Phase 1 standards without adverse impacts on any

manufacturers 

EPA is also proposing to revise the regulation to spell out how to apply enforcement 

liability for a situation in which the engine manufacturer uses deficit credits for one or more 

model years. Simply put, any time an engine manufacturer is allowed to carry a deficit to the 

next year, all enforcement liability for the engines that generated the deficit are extended for 

another year. These provisions are the same as what we have already adopted for heavy-duty 

vehicles subject to GHG standards under 40 CFR part 1037.

(3) Evaporative Emission Testing for LNG Vehicles

Heavy-duty vehicles fueled by natural gas have for many years been subject to 

evaporative emission standards and test procedures. While fuel systems containing gasoline 

require extensive design features to handle vented fuel, fuel systems containing natural gas 

generally prevent evaporative losses by remaining sealed. In the case of compressed natural gas, 

there is a voluntary consensus standard, ANSI NGV1-2006, that is designed to ensure that there 

are no leaks or losses during a refueling event. Since compressed natural gas systems remain 

sealed indefinitely once the refueling event is complete, we understand that complying with the 

ANSI refueling standard is sufficient to demonstrate that the vehicle also complies with all 

applicable evaporative emission standards. The Light-Duty Tier 3 final rule included provisions 

to clarify that compressed natural gas systems meeting the applicable ANSI standard are deemed 

to comply with EPA’s evaporative emission standards.

Systems using liquefied natural gas (LNG) behave similarly, except that the 

cryogenically stored fuel needs to be vented to prevent an over-pressure situation if the vehicle is 

not used for an extended time, as described in Section XI. Such vehicles are currently subject to 

evaporative emission standards and test procedures, though there are some substantial questions 
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about how one can best apply the procedures to these systems; not all of the instructions about 

preconditioning the vehicle are straightforward for cryogenic fuel systems with no evaporative 

canister. EPA is interested in pursuing an approach that is similar to what applies for 

compressed natural gas systems, which would need some additional attention to address boil-off 

emissions. There are two voluntary consensus standards that specify recommended practices to 

lengthen the time before boil-off starts to occur for LNG systems. SAE J2343 specifies a 

minimum five-day hold time and NFPA 52 specifies a minimum three-day hold time. EPA is 

proposing to require that manufacturers of LNG vehicles meet the SAE J2343 standard as a 

means of demonstrating compliance with the evaporative emission standards. 

While the hold-time requirements of SAE J2343 and NFPA 52 are clear, there appears to 

be very little description of the procedure to determine how much time passes between a 

refueling event and initial venting. To ensure that all manufacturers are subject to the same set 

of requirements, we are proposing to include a minimal set of specifications corresponding to the 

demonstration under SAE J2343. In particular, EPA proposes to specify that the vehicle must 

remain parked throughout the measurement procedure, ambient temperatures must remain 

between 20 and 30 °C, the refueling event must follow conventional procedures corresponding to 

the vehicle’s hardware, and no stabilization step is allowed after the refueling event.

The proposed rules provides for relying on compliance with SAE J2343 as a means of 

demonstrating compliance with evaporative emission standards immediately upon completion of 

the final rule. EPA is proposing to make this mandatory for vehicles produced on or after 

January 1, 2020.

EPA requests comment on all aspects of the proposed provisions for LNG vehicles.

(4) Compliance and Other General Provisions

EPA proposes the following changes that apply broadly for different types of vehicles or 

engines:

 Add a requirement for vehicle manufacturers that sell incomplete vehicles to secondary

vehicle manufacturers to provide emission-related assembly instructions to ensure that the 

completed vehicle will be in a certified configuration.

 Specify parameters for determining a vehicle’s curb weight, consistent with current practice 

for vehicles certified under 40 CFR part 86, subpart S.

 Revise the recordkeeping requirement to specify a uniform eight-year retention period for all 

data supporting an application for certification. The provision allowing for one-year 

retention for “routine data” is no longer necessary now that data collection is all recorded in 

electronic format. EPA is also clarifying that the eight-year retention period is calculated 

relative to the latest associated application for certification, not from the date the data were 

generated.

 Change the rounding for analytically derived CO2 emission rates and target values from the 

nearest 0.1 g/mile to the nearest 1 g/mile.

 Clarify that manufacturers may not amend an application for certification after the end of the 

model year, other than to revise maintenance instructions or family emission limits, as 
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allowed under the regulations. Remove the general recordkeeping provisions from 40 CFR 

1037.735 that are already described in 40 CFR 1037.825.

 Require a different equation with a ratio of 0.8330 in 40 CFR 1037.525(f) when full yaw 

sweep measurements are used to determine wind averaged drag correction to establish an 

equivalent method to the equation using +/- 6 degree measurements. This proposed change 

would not impact stringency because manufacturers are already subject to compliance using 

both methods – full yaw sweep and +/- 6 degree measurements. In addition, this Phase 1 

flexibility was not used in setting the level of the Phase 1 standards.

 Clarify how EPA would conduct selective enforcement audits (SEAs) for engines (in 40 CFR 

1036.301) and vehicles (in 40 CFR 1037.301) with respect to GHG emissions.

B. Other Compliance Provisions for NHTSA

(1) Standards and Credit Alignment

In Phase 1, the agencies intended GHG and fuel consumption standards for segments of 

the National Program to be in alignment so that manufacturers would not be required to build 

vehicles to meet in equivalent standards. Despite the intent, NHTSA and EPA have identified 

several scenarios where credits and compliance to both sets of standards are not aligned. This 

misalignment can have various impacts on compliance with the National Program. 

For example, a manufacturer of tractors could have two vehicle families that with same 

number of vehicles but with opposite and equal compliance margins with standards. In this 

scenario, the first family would over-comply with the GHG standard while the second family

would under-comply with the GHG standard by the same amount of grams CO2/ton-mile. In

calculating credits, the manufacturer would have a net of zero GHG credits and exactly meet 

compliance; however, based on conversions and rounding of the standard and performance 

results that manufacturer could end up earning credits or having a credit deficit under NHTSA’s 

fuel efficiency program.

In order to correct this misalignment, NHTSA is proposing to amend the existing fuel 

consumption standards and the method for calculating performance values for all compliance 

categories by increasing the significant digits in these conversion values. Increasing the 

significant digits in these values will result in more precise alignment when converting from 

GHG consumption standards to fuel consumption standards. 

The rounding approach differs for heavy-duty pickup trucks and vans set apart from other 

vehicle and engine compliance categories. Heavy Duty Pickup Trucks and Vans (HD PUV) use 

the same approach for calculating standards and performance values as the LD CAFE and GHG 

programs. As such, NHTSA proposes to increase the required significant values for each 

components used in these calculations. More specifically, NHTSA proposes to increase the 

number of decimal places for sub-configuration target standards, the sub-configuration fuel 

consumptions, the fleet average target standard and the fleet average fuel consumption values 

from two fixed values and increases them by one additional significant digit. The regulation 

currently specifies rounding to these values nearest 0.01 and under the proposed approach the 

values would be rounded to the nearest 0.001. 
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NHTSA is also proposing to modify the c and d target coefficients used for deriving HD 

PUV target standards. These values are directly convertible from the EPA a and b target 

coefficients, respectively. Currently, the c target coefficient contains six decimal places and the 

d target coefficient contains two decimal places. Each coefficient would be increased by one 

decimal—meaning the c target coefficient would have seven decimal places, with the last four 

being significant digits—and the d target coefficient would be increased to three decimal places, 

with there being a total of four significant digits. The modifications to the rounding and level of 

precision of these six values will not entirely eliminate the misalignment of the credits being 

calculated for EPA and NHTSA but will reduce it to an insignificant variance. 

For other compliance categories, a similar approach can be used to address the 

misalignment of calculated credits as it pertains to vocational vehicles, tractors, and heavy duty 

engines. NHTSA proposes to increase the number of significant digits by increasing the decimal 

places contained in the standards and the FEL for the vocational vehicle and tractor segments 

and the FCL for the engine segments to four decimal places. Currently, the vocational vehicle 

and tractor standards and FELs contain one decimal place while engines standards and FELs 

contain two decimal places. The standards will be identified directly in the regulation while the 

FEL and FCL will be a calculated value rounded to the nearest 0.0001. 

The modifications to the rounding and level of precision of these values should eliminate 

the misalignment of the credits being calculated. 

These changes are planned for implementation retroactively starting for the model year 

2013 standard. However, because the stringency of the Phase 1 fuel consumption standards may

be adversely impacted for certain manufacturers who have already developed engineering plans 

considering previous credit balance, we propose to seek comments on whether optional 

compliance should be allowed. 

(2) Off-road Exclusion Petition Process for Tractors and Vocational Vehicles 

In the Phase 1 final rule, the agencies added provisions for certain types of vocational 

tractors and vocational vehicles that operate off-road to be exempt from standards, although 

standards would still apply to the engines installed in these vehicles. An exemption was 

warranted because these vehicles operate in a manner essentially making them incompatible with 

fuel saving and emission reduction technologies, such as performing work in an off-road 

environment, being speed restricted, or having off-road components or other features making 

them incompatible for roadways. For the Phase 1 program, off-road vehicle manufacturers 

meeting the exemption provisions are required to provide EPA and NHTSA, through the EPA 

database, a report within 90 days after the end of each model year identifying its off-road 

vehicles. The report must provide a description of each excluded vehicle configuration, 

including an explanation of why it qualifies for the exclusion and the production volume. A 

manufacturer having an off-road vehicle failing to meet the criteria under the agencies’ off-road 

exemptions explained in 40 CFR 1037.631 and 49 CFR 523 is allowed to submit a petition as 

required in 49 CFR 535.8(h)(6) describing how and why its vehicles should qualify for 

exclusion. 
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Under Phase 1 compliance processes, manufacturers have not been using the petitioning 

process when seeking clarification on off-road vehicles not meeting the strict interpretation of 

the provision. Instead, manufacturers are submitting information to EPA in advance of the end 

of the model year to determine whether or not these vehicles are exempted and to determine 

whether it is necessary to submit any applications for certificates of conformity as required by 40 

CFR 1037.201. EPA and NHTSA collaboratively determine whether manufacturers are 

exempted and EPA shares the decision with the manufacturer. The current process followed by 

the agencies makes it unnecessary to use the petitioning process and has the added advantage of 

providing a joint determine early enough in the model year whereas disapproved manufacturer 

have adequate enough time to submit applications for certificates of conformity. 

For the Phase 1 standards, the agencies are proposing to delete the petitioning process 

and add provisions for manufacturers seeking clarification on the qualifications of an off-road 

vehicle exemption to send information to the agencies through EPA in advance of the model year 

in order for us to make an appropriate determination. EPA plans to add these provisions into its 

regulations as a part of 40 CFR 1037.210. Removal of the formal petition process is intended to 

minimize the impact on manufacturers that are seeking an off-road exemption while allowing the 

agencies to be proactive in making a determination based on the criteria and individual merits of 

the vehicles being requested for an exemption. Collaboration between the agencies in making a 

decision about exemptions outside a formal petition process should streamline the timing for a 

response and reduce the burden upon the agencies and manufacturers. 

(3) Innovative Technology Request Documentation Specifications

For vehicle and engine technologies that can reduce GHG and fuel consumption, but for 

which there is not yet an established method for quantifying reductions, the agencies encourage 

the development of such technologies through providing “innovative technology” credits. 

Manufacturers seeking innovative technology credits must quantify the reductions in fuel 

consumption and GHG emissions that the technology is expected to achieve, above and beyond 

those achieved on the existing test procedures.

Manufacturers submitting innovative technology requests must send a detailed 

description of the technology and a recommended test plan to EPA as detailed in 40 CFR 

1036.610 and 40 CFR 1037.610. The test plan must include whether the manufacturer is 

applying for credits using the improvement factor method or the separate-credit method. It is 

recommended that manufacturers not conduct testing until the agencies can collaboratively 

approve the test plan in which a determination is made on the qualification of the technology as 

innovative. EPA and NHTSA also make the decision at that time whether to seek public 

comments on the test plan if there are unknown factors in the test methodology. 

Under the current regulations, EPA and NHTSA have reviewed several test plans from 

manufacturers seeking innovative technology credits. The agencies have received feedback from 

manufacturers that the final approval process is not clearly defined, which has caused a 

substantial time commitment from manufacturers. To address this feedback, the agencies are 

proposing to add further clarification in 40 CFR 1036.610 and 40 CFR 1037.610 defining the 

steps manufacturers must follow after an approval is granted for a test plan. This includes 

specifications for submitting the final documentation to the agencies for final approval and for 
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determining credit amounts. The agencies are adding the same level of detail as required for the 

final documentation required in EPA’s light duty off-cycle program in 40 CFR 86.1869-12(e)(2). 

These specifications should provide manufacturers with a clear understanding of the required 

documentation and approval process to reduce the time burden placed on manufacturers. 

NHTSA also proposes to add similar provisions from its light duty CAFE program 

specified in 49 CFR 531.6(b)(2) and 533(c)(2) for limiting the approval of innovative 

technologies under its program for those technologies related to crash-avoidance technologies, 

safety critical systems or systems affecting safety-critical functions, or technologies designed for 

the purpose of reducing the frequency of vehicle crashes. NHTSA prohibited credits for these 

technologies under any circumstances in its CAFE program (see 77 FR 62730). NHTSA 

believes a similar strategy is warranted for heavy-duty vehicle as well. Further, the evaluation of 

crash avoidance technologies is better addressed under NHTSA’s vehicle safety authority than 

under a case-by-case innovative technology credit process.

(4) Credit Acquisition Plan Requirements

The National Program was designed to provide manufacturers with averaging, banking 

and trading (ABT) flexibilities for meeting the GHG and fuel efficiency standards to optimize 

the effectiveness of the program. As a part of these flexibilities, manufacturers generating a 

shortfall in fuel consumption credits for a given model year must submit a credit plan to NHTSA 

describing how it plans to resolve its deficits within 3 models year. To assist manufacturers, 

NHTSA is proposing to modify 49 CFR 535.9(a)(6) of its regulation to clarify and provide 

guidance to manufacturers on the requirements for a credit allocation plan which contains 

provisions to acquire credits from another manufacturer which will be earned in future model 

years. 

The current regulations do not specify if future credit acquisition is permitted or not and 

the revision is intended to clarity that it is, with respect to the limitation a credit shortfall can 

only be carried forward three years. Providing this clarification is intended to increase 

transparency within the program and ensure all manufacturers are aware of its available 

flexibilities.

In addition to providing this clarification, the regulation is also being amended to outline 

the requirement that in order for a credit allocation plan containing this provision to be reviewed 

for approval, NHTSA will require an agreement signed by both manufacturers. This requirement 

will assist NHTSA with its determination that the credits will become available to the acquiring 

manufacturer given they are earned.

(5) New Vehicle Field Inspections and Recordkeeping Requirements

Previously, NHTSA decided not to include recordkeeping provisions in its regulations for 

the Phase 1 program. EPA regulations include recordkeeping requirements in 40 CFR 1036.250, 

1036.735, 1036.835, 1037.250, 1037.735 and 1037.835. For the Phase 2 program, NHTSA is 

proposing to add recordkeeping provisions to facilitate its compliance validation program. For 

the Phase 1 program, manufacturers test and conduct modeling to determine GHG emissions and 

fuel consumption performance, and EPA and NHTSA perform validation testing. EPA uses the 
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results of the validation tests to create a finalized report that confirms the manufacturer’s final 

model year GHG emissions and fuel consumption results. Each agency will use this report to 

enforce compliance with its standards. 

NHTSA assesses compliance with fuel consumption standards each year, based upon 

EPA final verified data submitted to NHTSA for its heavy-duty vehicle fuel efficiency program 

established pursuant to 49 U.S.C. 32902(k). NHTSA may also conduct verification testing 

throughout a given model year in order to validate data received from manufacturers and will 

discuss any potential issues with EPA and the manufacturer. See 49 CFR 535.9. After the end 

of the model year, NHTSA may also decide to conduct field inspections in order to confirm 

whether or not a new vehicle was manufactured as originally certified. NHTSA may conduct 

field inspections separately or in coordination with EPA. To facilitate inspections, the agencies 

propose to add additional provisions to the EPA recordkeeping provisions to require 

manufacturers to keep build documents for each manufactured tractor or vocational vehicle. 

Each build document would be required to contain specific information on the design, 

manufacturing, equipment and certified components for a vehicle. NHTSA would request build 

documents through EPA and the agencies would collaborate on the finding of all field 

inspections. Manufacturers would be required to keep records of build documents for a period of 

8 calendar years. 
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XIV. Other Proposed Regulatory Provisions

In addition to the new GHG standards proposed in these rules, EPA and NHTSA are 

proposing to amend various aspects of the regulations as part of the HD GHG Phase 1 standards 

for heavy-duty highway engines and vehicles. EPA is also taking the opportunity to propose to 

amend regulatory provisions for other requirements that apply for heavy-duty highway engines, 

and for certain types of nonroad engines and equipment. 

A. Proposed Amendments Related to Heavy-Duty Highway Engines and 

Vehicles

This section describes a range of proposed regulatory amendments for heavy-duty 

highway engines and vehicles that are not directly related to GHG emission standards. Section 

XIV.D describes additional changes related to test procedures that affect heavy-duty highway 

engines.

(1) Alternate Emission Standards for Specialty Heavy-Duty Vehicles

Motor vehicles conventionally comprise a familiar set of vehicles within a relatively

narrow set of parameters — motorcycles, cars, light trucks, heavy trucks, buses, etc. The 

definition of “motor vehicle;” however, is written broadly to include a very wide range of 

vehicles. Almost any vehicle that can be safely operated on streets and highways is considered a 

motor vehicle. Development of EPA’s emission control programs is generally focused on a 

consideration of the technology, characteristics, and operating parameters of conventional 

vehicles, and typically includes efforts to address concerns for special cases. For example, the 

driving schedule for light-duty vehicles includes a variation for vehicles that are not capable of 

reaching the maximum speeds specified in the Federal Test Procedure. 

Industry innovation in some cases leads to some configurations that make it particularly 

challenging to meet regulatory requirements. We are aware that plug-in hybrid-electric heavyduty vehicles are an example of this. An engine for such a vehicle would be expected to have a 

much lower power rating and duty cycle of engine speeds and loads than a conventional heavyduty engine. The costs of regulatory compliance and the mismatch to the specified duty cycle 

can make it cost-prohibitive for engine manufacturers to certify such an engine under the heavyduty highway engine program. EPA’s nonroad emission standards have reached a point that 

involves near parity with the level of emission control represented by the emission standards for 

heavy-duty highway engines. 

To address concerns about certifying heavy-duty engines to highway standards for use in 

hybrid vehicles, we are therefore proposing to allow manufacturers of heavy-duty highway

vehicles the option to install limited numbers of engines certified to alternate standards. 

Qualifying engines would be considered motor vehicle engines, but they would be certified to 

standards that are equivalent to those adopted for comparable nonroad engines. Vehicles with 

hybrid powertrains would be a focus of this allowance. EPA believes the same principles apply 

for amphibious vehicles and for vehicles with maximum speed at or below 45 miles per hour and 

we are therefore proposing to apply the same provisions to these additional vehicles.
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Under this approach, compression-ignition engines could be certified to alternate 

standards that are equivalent to the emission standards under 40 CFR part 1039, and sparkignition engines could be certified to alternate standards that are equivalent to the Blue Sky

emission standards under 40 CFR part 1048. Engines meeting these alternate emission standards 

would generally be expected to use the same technologies to control emissions as engines 

certified to the applicable emission standards for heavy-duty highway engines. EPA would 

disallow this approach for compression-ignition engines below 56 kW since the nonroad 

standards for those engines are substantially less stringent than the standards that apply for 

heavy-duty highway engines. Also, since the nonroad duty cycles would generally better 

represent the in-use operating characteristics of these vehicles, we would expect the nonroad test 

procedures to be at least as effective in achieving effective in-use emission control. The 

regulations at 40 CFR part 1048 include a simplified form of diagnostic controls, and we are 

proposing in these rules to include simplified diagnostic controls for 40 CFR part 1039. These 

engine-based diagnostic controls would substitute for the diagnostic requirements that would 

otherwise apply under 40 CFR part 86.010-18.

It may also be appropriate to allow manufacturers of such heavy-duty vehicles to use an 

engine from a smaller vehicle that is already covered by chassis-based certification under 40 

CFR part 86, subpart S. Many of the heavy-duty vehicles described under this section would be 

adequately powered by lower-displacement automotive engines, and the level of emission 

control would clearly be expected to match or exceed that of engines certified to the heavy-duty 

standards that would otherwise apply. However, engines used in chassis-certified vehicles 

involve some degree of calibration that relates engine operation to vehicle parameters. Adapting 

these engines to heavy-duty vehicles would therefore require some recalibration, which could 

involve changing the effectiveness of emission controls. It is also unclear how the heavy-duty

vehicle would be designed for onboard diagnostic controls. EPA requests comment on the 

technical and regulatory issues surrounding the use of engines from chassis-certified vehicles in 

certain heavy-duty vehicles.

These alternate standards relate only to the engine certification-based emission standards 

and certification requirements. All vehicle-based requirements for evaporative and greenhouse 

gas emissions would continue to apply as specified in the regulation.

This allowance is intended to lower the barrier to introducing innovative technology for 

motor vehicles. It is not intended to provide a full alternative compliance path to avoid 

certifying to the emission standards and control requirements for highway engines and vehicles. 

To accomplish this, EPA is proposing to allow a manufacturer to produce no more than 1,000 

hybrid vehicles in a single model year under this program, and no more than 200 amphibious 

vehicles or speed-limited vehicles. 

California ARB is in the process of developing similar provisions for a reduced 

compliance burden for a limited number of highway vehicles toward the goal of incentivizing 

hybrid vehicles and other advanced technology. EPA expects to be involved in that policy

development and would be interested in aligning programs as much as possible. It may be 

necessary or appropriate for the final rule to include a reference to any new policy that has been 

adopted by California ARB in the meantime.
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EPA requests comment on all aspects of this program to create alternate motor-vehicle 

emission standards that allow certified nonroad engines to be used in the identified types of 

heavy-duty highway vehicles.

(2) Chassis Certification of Class 4 Heavy-Duty Vehicles

In the HD Phase 1 rule, the agencies included a provision allowing manufacturers to 

certify Class 4 and larger heavy-duty vehicles to the chassis-based emission standards in 40 CFR 

part 86, subpart S. This applied for greenhouse gas emission standards, but not criteria emission 

standards. EPA revisited this issue in the recent Tier 3 final rule, where we revised the 

regulation to allow this same flexibility relative to exhaust emission standards for criteria 

pollutants. However, this change to the regulation conflicted with our response to a comment in 

that rulemaking that EPA should not change the certification arrangement for criteria pollutants. 

Manufacturers have taken opposing views of the proper approach for vehicles above 

14,000 lbs GVWR. EPA requests comment on how best to address this issue in a way that 

resolves the various and competing concerns. In particular, EPA requests comment on the 

following specific areas of interest:

 Should EPA treat 14,000 lbs as a bright line to disallow any certification of larger 

vehicles to the chassis-based exhaust emission standards?

 Should EPA allow for certifying the larger vehicles to the chassis-based 

standards, but identify certain criteria to narrow the scope of this allowance? For 

example, EPA could limit this to compression-ignition or spark-ignition engines, 

we could identify a maximum GVWR value above which chassis-based 

certification is not allowed, or EPA could limit this allowance to vehicles that 

share design characteristics with chassis-certified vehicles below 14,000 lbs 

GVWR (as California ARB has done).

 If EPA allows for certifying the larger vehicles to the chassis-based standards, 

what additional amendments are needed to clarify how to apply the requirements 

of 40 CFR part 86, subpart S? For example, some further specification may be 

needed to identify how to apply requirements related to emission standards, 

driving schedule, and emission credits?

(3) On-Board Diagnostics for Heavy-Duty Vehicles

EPA defines the onboard diagnostic requirements for heavy-duty vehicles above 14,000 

lbs GVWR in 40 CFR 86.010-18, but we allow manufacturers to meet OBD requirements based 

on the requirements adopted by the California Air Resources Board. Manufacturers in almost all 

cases certify based on the California procedures instead of EPA procedures. Certification based 

on EPA procedures is limited to certain spark-ignition engine families whose certification is 

limited to states other than California. EPA requests comment on a change to EPA regulation 

that simply requires that manufacturers meet the California requirements. EPA has taken a 

similar approach for vehicles at or below 14,000 lbs GVWR, as described in 40 CFR 86.1806-

17. Under this approach, EPA would recognize California ARB’s approval as valid for EPA 

certification. EPA requests comment on this approach. In particular, EPA requests comment on 

the need to preserve EPA specifications for on-board diagnostics for any special situations, and 
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on the need to make any adjustments or allowances from the California ARB regulations to work 

for EPA implementation.

(4) Nonconformance Penalties (NCPs)

The Clean Air Act requires that heavy-duty standards for criteria pollutants such as NOX

must reflect the greatest degree of emission reduction achievable through the application of 

technology that EPA determines will be available. Such “technology-forcing” standards create 

the risk that one or more manufacturers may lag behind in the development of their technology to 

meet the standard and, thus, be forced out of the marketplace. Recognizing this risk, Congress 

enacted CAA section 206(g) (42 U.S.C. 7525(g)), which requires EPA to establish 

“nonconformance penalties” to protect these technological laggards by allowing them to pay a 

penalty for engines that temporarily are unable to meet the applicable emission standard, while 

removing any competitive advantage those technological laggards may have. 

On September 5, 2012, EPA adopted final NCPs for heavy heavy-duty diesel engines that 

could be used by manufacturers of heavy-duty diesel engines unable to meet the current oxides 

of nitrogen (NOX) emission standard. On December 11, 2013, the U.S. Court of Appeals for the 

District of Columbia Circuit issued an opinion vacating that Final Rule. It issued its mandate for 

this decision on April 16, 2014, ending the availability of the NCPs for the current NOX

standard, as well as vacating certain amendments to the NCP regulations due to concerns about 

inadequate notice. In particular, the amendments revise the text explaining how EPA determines 

when NCP should be made available. EPA is proposing to remove the vacated regulatory text 

specifying penalties, and re-proposing most of the other vacated amendments to provide fuller 

notice. Finally, EPA is proposing a new 40 CFR 86.1103-2016 to replace the existing 40 CFR 

86.1103-87. 

(a) Vacated Penalties

In EPA’s regulations, NCP penalties are calculated from inputs specific to the standards 

for which NCPs are available. The input values are specified in 40 CFR 86.1105-87. EPA is 

proposing to remove paragraph (j) of this section which specifies the vacated inputs for the 2010 

NOX emission standard. EPA does not request comment on this change because this text has 

already been vacated by the Court. Since all manufacturers are currently complying with these 

standards, the text also no longer has any purpose.

(b) Re-proposed Text

The 2012 rule made amendments to four different sections in 40 CFR part 86. The 

amendments to 40 CFR 86.1104-91 and 86.1113-87 were supported during the rulemaking and 

were not questioned in the Court’s decision. Nevertheless, these revisions were vacated along 

with the rest of the rule. EPA is re-proposing these changes. Since we are proposing to vacate 

and restore the regulatory text, the proposal consists of leaving these sections of the regulations 

unchanged.
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(i) Upper Limits

The changes to 40 CFR 86.1104-91 affected the upper limit. The upper limit (UL) is the 

emission level established by regulation above which NCPs are not available. A heavy duty 

engine cannot use NCPs to be certified for a level above the upper limit. CAA section 206(g)(2) 

refers to the upper limit as a percentage above the emission standard, set by regulation, that 

corresponds to an emission level EPA determines to be “practicable.” The upper limit is an 

important aspect of the NCP regulations not only because it establishes an emission level above 

which no engine may be certified using NCPs, but it is also a critical component of the cost 

analysis used to develop the penalty rates. The regulations specify that the relevant costs for 

determining the COC50 and the COC90 factors are the difference between an engine at the upper 

limit and one that meets the applicable standards (see 40 CFR 86.1113-87). 

The regulatory approach adopted under the prior NCP rules sets the upper limit at the 

prior emission standard when a prior emission standard exists and is then changed to become 

more stringent. EPA concluded that this upper limit should be reasonably achievable by all 

manufacturers with engines or vehicles in the relevant class. It should be within reach of all 

manufacturers of HD engines or HD vehicles that are currently allowed so that they can continue 

to sell their engines and vehicles while finishing their development of fully complying engines. 

A manufacturer of a previously certified engine or vehicle should not be forced to immediately

remove a HD engine or vehicle from the market when an emission standard becomes more 

stringent. The prior emission standard generally meets these goals because manufactures have 

already certified their vehicles to that standard. 

EPA proposes to revise the regulations in 40 CFR 86.1104-91 to clarify that EPA may set 

the upper limit at a level below the previous standard if we determine that the lower level is 

achievable by all engines or vehicles in the relevant subclass. This was the case for the vacated 

NCP rule. EPA also proposes that we may set the upper limit at a level above the previous 

standard in unusual circumstances, such as where a new standard for a different pollutant or 

other requirement effectively increases the stringency of the standard for which NCPs would 

apply. This occurred for heavy heavy-duty engines with the 2004 standards.

(ii) Payment of Penalties

The proposed changes to 40 CFR 86.1113-87 correct EPA organizational units and mail 

codes to which manufacturers must send information. The previous information is no longer 

valid.

(c) Criteria for the Availability of NCPs

Since the promulgation of the first NCP rule in 1985, subsequent NCP rules generally 

have been described as continuing “phases” of the initial NCP rule. The first NCP rule (Phase I), 

sometimes referred to as the “generic” NCP rule, established three basic criteria for determining 

the eligibility of emission standards for nonconformance penalties in any given model year (50 

FR 35374, August 30, 1985). (For regulatory language, see 40 CFR 86.1103-87). The first 

criterion is that the emission standard in question must become more difficult to meet. This can 

occur in two ways, either by the emission standard itself becoming more stringent, or due to its 
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interaction with another emission standard that has become more stringent. Second, substantial 

work must be required in order to meet the emission standard. EPA considers “substantial work” 

to mean the application of technology not previously used in that vehicle or engine 

class/subclass, or a significant modification of existing technology, in order to bring that 

vehicle/engine into compliance. EPA does not consider minor modifications or calibration 

changes to be classified as substantial work. Third, EPA must find that a manufacturer is likely 

to be noncomplying for technological reasons (referred to in earlier rules as a “technological 

laggard”). Prior NCP rules have considered such a technological laggard to be a manufacturer 

who cannot meet a particular emission standard due to technological (not economic) difficulties 

and who, in the absence of NCPs, might be forced from the marketplace. During the 2012 

rulemaking, some commenters raised issues relating to EPA’s interpretation of these criteria:

 The extent to which the criteria are intended to constrain EPA’s ability to set 

NCPs

 The timing for evaluating the criteria

 The meaning of technological laggard

(i) Constraints on EPA

Several commenters argued (implicitly or explicitly) that EPA cannot establish NCPs 

unless all of the regulatory criteria for NCPs (in 40 CFR 86.1103-87) are met. Some went 

further to argue that EPA must demonstrate that the criteria are met. However, the actual 

regulatory text has never stated that EPA may establish NCPs only if all criteria are met, but 

rather that EPA shall establish NCPs “provided that EPA finds” the criteria are met. These 

criteria were included in the regulations to clarify that manufacturers should not expect EPA to 

initiate a rulemaking to establish NCPs where these criteria were not met. Moreover, the 

regulations clearly defer to EPA’s judgment for finding that the criteria are met. While EPA 

must explain the basis of our finding, the regulatory language does not require us to prove or 

demonstrate that the criteria are met.

This interpretation is consistent with the text of the Clean Air Act, which places no 

explicit restrictions on when EPA can set NCPs. In fact, it seems to create a presumption that 

NCPs will be available. The Act actually requires EPA to allow certification of engines that do 

not meet the standard unless EPA determines the practicable upper limit to be equal to the new 

emission standard.

To address this confusion, the new proposed regulatory text would explicitly state that 

where EPA cannot determine if all of the criteria have been met, we may presume that they have. 

In other words, EPA does not have the burden to prove they have been met.

(ii) Timing for Evaluating Criteria

In order to properly understand the appropriate timing for evaluating each of the NCP 

criteria, it is necessary to understand the purpose of each. When considered together, these 

criteria evaluate the likelihood that a manufacturer will be technologically unable to meet a 

standard on time. However, when EPA initially proposed the NCP criteria, we noted that the 

first two criteria addressed whether there was a possibility for a technological laggard to develop. 
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When the first criterion is met, it creates the possibility for a technological laggard to exist. 

When manufacturers must perform substantial work, it is possible that at least one will be 

unsuccessful and will become a laggard. Thus, when evaluating these first two criteria, the 

purpose is to determine whether the standard created the possibility for a laggard to exist. The 

third criterion is different because it asks whether that possibility has turned into a likelihood that 

a technological laggard has developed. For example, a standard may become significantly more 

stringent and substantial effort might be required for compliance, but all manufacturers may be 

meeting the applicable standard. In that situation, a technological laggard is not likely and 

penalties would be unnecessary.

In this context, it becomes clear that since the first two of these criteria are intended to 

address the question of whether a given standard creates the possibility for this to occur, they are 

evaluated before the third criterion that addresses the likelihood that the possibility will actually 

happen. In most cases, it is possible to evaluate these criteria at the point a new standard is 

adopted. This is the value of these criteria, that they can usually be evaluated long before there is 

enough information to know whether a technological laggard is actually likely. For example, 

where EPA adopts a new standard that is not technology-forcing, but rather merely an antibacksliding standard, EPA could determine at the time it is adopted that the second criterion is 

not met so that manufacturers would know in advance that no NCPs will be made available for 

that standard.

One question that arose in the 2012 rule involved how to evaluate the second criterion if 

significant time has passed and some work toward meeting the standard has already been 

completed. To address this question, the proposed regulations would clarify that this criterion is 

to be evaluated based on actual work needed to go from meeting the previous standard to 

meeting the current standard, regardless of the timing of such changes. EPA looks at whether 

“substantial work” is or was required to meet the revised standard at any time after the standard 

was issued – the important question is whether manufacturers who were using technology that 

met the previous standard would need to build upon that technology to meet the revised standard. 

Other interpretations would seem to be directly contrary to the purpose of the statute, which is 

designed to allow technological laggards to be able to certify engines even if other manufacturers 

have met the standard. 

(iii) Technological Laggards

Questions also arose in 2012 about the meaning of the term “technological laggard”. 

While the regulations do not define “technological laggard”, EPA has previously interpreted this 

as meaning a manufacturer who cannot meet the emission standard due to technological 

difficulties, not merely economic difficulties (67 FR 51464 - 51465, Aug. 8, 2002). Some have 

interpreted this to mean that NCPs cannot be made available where a manufacturer tries and fails 

to meet a standard with one technology but knew that another technology would have allowed 

them to meet the standard. In other words, that it made a bad business decision. However, 

EPA’s reference to “economic difficulties” applies where a technological path exists – at the 

time EPA is evaluating the third criterion – that would allow the manufacturer to meet the 

standard on time, but the manufacturer chooses not to use it for economic reasons. The key

question is whether or not the technological path exists at the time of the evaluation. To address 

this confusion, the proposed regulations would clarify that where there is uncertainty about 
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whether a failure to meet the standards is a technological failure, EPA may presume that it was. 

Note that this does not mean that EPA might declare any failure to meet standards as a 

technological failure. It would only apply where it is not clear.

(5) In-use Testing

EPA and manufacturers have gained substantial experience with in-use testing over the 

last four or five years. This has led to important insights in ways that the test protocol can be 

adjusted to be more effective. EPA is accordingly proposing to make the following changes to 

the regulations in 40 CFR part 86, subparts N and T:

 Revise the NTE exclusion based on aftertreatment temperature to associate the exclusion 

with the specific aftertreatment device that does not meet the temperature criterion. For 

example, there should be no NOX exclusion if a diesel oxidation catalyst is below the 

temperature threshold. EPA is also proposing to revise the exclusion to include 

accommodation of CO emissions when there is a problem with low temperatures in the 

exhaust.

 Clarify that exhaust temperatures should be measured continuously to evaluate whether those 

temperatures stay above the 250 °C threshold. 

 Add specifications to describe where to measure temperatures for exhaust systems with 

multiple aftertreatment devices.

 Include a provision to add 0.00042 g/hp-hr to the PM measurement to account for PM 

emissions vented to the atmosphere through the crankcase vent.

 Increase the time allowed for submitting quarterly reports from 30 to 45 days after the end of 

the quarter.

(6) Miscellaneous Amendments to 40 CFR Part 86

As described elsewhere, EPA is proposing to make several changes to 40 CFR part 86. 

This includes primarily the GHG standards for Class 2b and 3 heavy-duty vehicles in subpart S. 

EPA is also proposing changes related to hearing procedures, adjustment factors for infrequent 

regeneration of aftertreatment devices, and the testing program for heavy-duty in-use vehicles. 

EPA is proposing to make several minor amendments to 40 CFR part 86, subpart A, 

including the following: 

 Revise 40 CFR 86.1823 to extend the default catalyst thermal reactivity coefficient for Tier 2 

vehicles to also apply for Tier 3 vehicles. This change was inadvertently omitted from the 

recent Tier 3 rulemaking. EPA is also interested in a broader review of the appropriate 

default value for the catalyst thermal reactivity coefficient. EPA would be interested in 

reviewing any available data related to this issue. In any case, EPA would plan to revisit this 

question in the future. 

 Establish a minimum maintenance interval of 1500 hours for DEF filters for heavy-duty

engines. This reflects the technical capabilities for filter durability and the expected 

maintenance in the field. 
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 Remove the idle CO standard from 40 CFR 86.007-11 and 40 CFR 86.008-10. This standard 

no longer applies, since all engines are now subject to diagnostic requirements instead of the 

idle CO standard.

EPA is also proposing several amendments to remove obsolete text, update cross 

references, and streamline redundant regulatory text. For example, paragraph (f)(3) of Appendix 

I includes a duty cycle for heavy-duty spark-ignition engines that is no longer specified as part of 

the certification process.

(7) Applying 40 CFR Part 1068 to Heavy-duty Highway Engines and Vehicles

As part of the Phase 1 standards, EPA applied the exemption and importation provisions 

from 40 CFR part 1068, subparts C and D, to heavy-duty highway engines and vehicles. EPA 

also specified that the defect reporting provisions of 40 CFR 1068.501 were optional. In an 

earlier rulemaking, EPA applied the selective enforcement auditing under 40 CFR part 1068, 

subpart E (75 FR 22896, April 30, 2010). EPA is proposing in this rule to adopt the rest of 40 

CFR part 1068 for heavy-duty highway engines and vehicles, with certain exceptions and special 

provisions.

40 CFR part 1068 captures a range of compliance provisions that are common across our 

engine and vehicle programs. These regulatory provisions generally provide the legal 

framework for implementing a certification-based program. 40 CFR part 1068 works in tandem 

with the standard-setting part for each type of engine/equipment. This allows EPA to adopt 

program-specific provisions for emission standards and certification requirements for each type 

of engine/equipment while taking a uniform approach to the compliance provisions that apply

generally. 

Many of the provisions in 40 CFR part 1068 were originally written to align with the 

procedures established in 40 CFR part 85 and part 86. EPA expects the following provisions 

from 40 CFR part 1068 to not involve a substantive change for heavy-duty highway engines and 

vehicles:

 Part 1068, subpart A, describes how EPA handles confidential information, how the 

Administrator may delegate decision-making within the agency, how EPA may enter 

manufacturers’ facilities for inspections, what information manufacturers must submit to 

EPA, and how EPA may require testing or perform testing. There is also a description of 

labeling requirements that apply uniformly for different types of engines/equipment.

 The prohibited acts, penalties, injunction provisions, and related requirements of 40 CFR 

1068.101 and 1068.125 correspond to what is specified in Clean Air Act sections 203 

through 207 (also see section 213(d)).

 40 CFR 1068.103 describes how a certificate of conformity applies on a model-year basis. 

With the exception of the stockpiling provisions in paragraph (f), as described below, these 

provisions generally mirror what already applies for heavy-duty highway engines.

 40 CFR 1068.115 describes manufacturers’ warranty obligations. EPA is proposing to 

amend this section to more carefully conform to the warranty provisions in Clean Air Act 

section 207, as described below. Note that EPA also includes a provision identifying the 
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warranty requirements from Clean Air Act section 203(a)(4), which are specific to motor 

vehicles.

 40 CFR 1068.120 describes requirements that apply for rebuilding engines. This includes 

more detailed provisions describing how the rebuild requirements apply for cases involving a 

used engine to replace a certified engine.

 40 CFR part 1068, subpart F, describes procedural requirements for voluntary and mandatory

recalls. As noted below, EPA is proposing to modify these regulations to eliminate a few 

instances where the part 1068 provisions differ from what is specified in 40 CFR part 86, 

subpart S.

 40 CFR part 1068, subpart G, describes how EPA would hold a hearing to consider a 

manufacturer’s appeal of an adverse compliance decision from EPA. These procedures 

apply for penalties associated with violations of the prohibited acts, recall, nonconformance 

penalties, and generally for decisions related to certification. As noted below, EPA is 

proposing to migrate these procedures from 40 CFR part 86, including an effort to align with 

EPA-wide regulations that apply in the case of a formal hearing.

Manufacturers are already required to use good engineering judgment in many cases 

related to certifying engines under 40 CFR part 86, Section 1068.5.

As noted above, the exemption provisions of 40 CFR part 86, subpart C, already apply

for heavy-duty highway engines. EPA is proposing to add a clarification that the exemption 

from the tampering prohibition for competition purposes does not apply to heavy-duty highway 

vehicles. This aligns with the statutory provisions for the racing exemption. 

EPA is proposing to require that manufacturers comply with the defect-reporting 

provisions in 40 CFR 1068.501. Defect reporting under 40 CFR 1068.501 involves a more 

detailed approach for manufacturers to track possible defects and establishes thresholds to define 

when manufacturers must perform an investigation to determine an actual rate of emissionrelated defects. These thresholds are scaled according to production volumes, which allows us to 

adopt a uniform protocol for everything from locomotives to lawn and garden equipment. 

Manufacturers that also produce nonroad engines have already been following this protocol for 

several years. These defect-reporting requirements are also similar to the rules that apply in 

California. 

40 CFR part 1068 includes a definition of “engine” to clarify that an engine becomes 

subject to certification requirements when a crankshaft is installed in an engine block. At that 

point, a manufacturer may not ship the engine unless it is covered by a certificate of conformity 

or an exemption. Most manufacturers have opted into this definition of “engine” as part of the 

replacement engine exemption as specified in 40 CFR 85.1714. We are proposing to make this 

mandatory for all manufacturers. A related provision is the definition of “date of manufacture”, 

which we use to establish that an engine’s model year is also based on the date of crankshaft 

installation. To address the concern that engine manufacturers would install a large number of 

crankshafts before new emission standards start to apply as a means of circumventing those 

standards, we state in 40 CFR 1068.103(f) that manufacturers must follow their normal 

production plans and schedules for building engines in anticipation of new emission standards. 

In addition to that broad principle, we state that we will consider engines to be subject to the 

standards for the new model year if engine assembly is not complete within 30 days after the end 
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of the model year with the less stringent standards (a longer time frame applies for engines with 

per-cylinder displacement above 2.5 liters). 

40 CFR part 1068 also includes provisions related to vehicle manufacturers that install 

certified engines. EPA states in 40 CFR 1068.105(b) that vehicle manufacturers are in violation 

of the tampering prohibition if they do not follow the engine manufacturers’ emission-related 

installation instructions, we approve as part of the certification process.

40 CFR part 1068 also establishes that vehicles have a model year and that installing 

certified engines includes a requirement that the engine be certified to emission standards 

corresponding to the vehicle’s model year. An exception to allow for normal production and 

build schedules is described in 40 CFR 1068.105(a). This “normal-inventory” allowance is 

intended to allow for installation of previous-tier engines that are produced under a valid 

certificate by the engine manufacturer shortly before the new emission standards start to apply. 

Stockpiling such engines would be considered an unlawful circumvention of the new emission 

standards. The range of companies and production practices is much narrower for heavy-duty

highway engines and vehicles than for nonroad engines and equipment. EPA is therefore 

proposing a further set of specifications to define or constrain engine-installation schedules that 

would be considered to fall within normal-inventory practices. In particular, vehicle 

manufacturers are limited to three months of production, once new emission standards start to 

apply, to install previous-tier engines without EPA approval. For any subsequent installation of 

previous-tier engines, EPA is proposing to require that vehicle manufacturers get EPA approval 

based on a demonstration that the excess inventory was a result of unforeseeable circumstances 

rather than circumvention of emission standards. EPA is proposing that approval in those 

circumstances would be limited to a maximum of 50 engines to be installed for up to three 

additional months for a single vehicle manufacturer. 

The existing prohibitions and exemptions in 40 CFR part 1068 related to competition 

engines and vehicles need to be amended to account for differing policies for nonroad and motor 

vehicle applications. In particular, we generally consider nonroad engines and vehicles to be 

“used solely for competition” based on usage characteristics. This allows EPA to set up an 

administrative process to approve competition exemptions, and to create an exemption from the 

tampering prohibition for products that are modified for competition purposes. There is no 

comparable allowance for motor vehicles. A motor vehicle qualifies for a competition exclusion 

based on the physical characteristics of the vehicle, not on its use. Also, if a motor vehicle is 

covered by a certificate of conformity at any point, there is no exemption from the tampering and 

defeat-device prohibitions that would allow for converting the engine or vehicle for competition 

use. There is no prohibition against actual use of certified motor vehicles or motor vehicle 

engines for competition purposes; however, it is not permissible to remove a motor vehicle or 

motor vehicle engine from its certified configuration regardless of the purpose for doing so.

It is relatively straightforward to apply the provisions of 40 CFR part 1068 to all engines 

subject to the criteria emission standards in 40 CFR part 86, subpart A, and the associated 

vehicles. Manufacturers of comparable nonroad engines are already subject to all these 

provisions. Class 2b and 3 heavy-duty vehicles subject to criteria emission standards under 40 

CFR part 86, subpart S, are covered by a somewhat different compliance program. EPA is 

therefore proposing to apply the provisions of 40 CFR part 1068 only as described in the next 
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section for light-duty vehicles, light-duty trucks, medium-duty passenger vehicles, and chassiscertified Class 2b and 3 heavy-duty vehicles. 

B. Amendments Affecting Gliders and Glider Kits

As noted in Sections III, and V the agencies are proposing not to exempt glider kits from 

the Phase 2 GHG emission and fuel consumption standards. 891 Gliders and glider kits are 

exempt from NHTSA’s Phase 1 fuel consumption standards. The EPA Phase 1 rules exempted 

gliders and glider kits produced by small businesses from CO2 standards (see 40 CFR 1037.150 

(c)) but did not include such a blanket exemption for other gliders and glider kits. EPA is 

proposing to amend its rules applicable to engines installed in glider kits, a proposal which 

would affect emission standards not only for GHGs but for criteria pollutants as well. NHTSA is 

also considering including gliders under its Phase 2 standards. Finally, EPA believes glider 

manufacturers may not understand how existing EPA regulations apply to them or otherwise are 

not complying with existing requirements, resulting in a number of uncertified vehicles. 

Therefore, EPA is also proposing to clarify its requirements for certification and to revise its 

definitions for glider manufacturers as described below.

It is important to emphasize that EPA is not proposing to ban gliders. Rather, as is 

described below, EPA proposing to restrict the number of gliders that may be produced using 

engines not meeting current standards.

EPA requests comment on its proposed amendments and clarifications regarding gliders. 

Commenters are encouraged to include technological information and production data for the 

current glider market, as well as for past practices. Commenters opposing the proposed 

provisions are also encouraged to suggest alternate approaches that would prevent glider kits 

from being used to circumvent the current emission standards.

(1) Background under the Clean Air Act

EPA notes that under the anti-tampering provisions of the Clean Air Act, and under 

EPA’s regulatory requirements applicable to rebuilding engines (see 40 CFR 86.004-40), rebuilt 

engines must continue to comply with emission standards applicable to the model year for which 

they were originally certified. These regulations specifically apply to rebuilt engines 

independent of the vehicle into which they are installed or reinstalled. As a general matter, EPA 

has considered the question of whether the vehicle into which the rebuilt engine is installed is a 

“new motor vehicle” separately from the status of the engine. The use of a rebuilt or other 

previously used engine in an otherwise newly manufactured vehicle (such as a glider kit) does 

not keep the vehicle from being “new” under the Clean Air Act. (Or, phrased positively, a newly 

manufactured vehicle remains “new” even if a rebuilt engine is installed in it.) This issue 

became of increased practical import with the advent of separate vehicle (i.e. non-engine) 

 

891 Glider vehicles are motor vehicles produced to accept rebuilt engines (or other used engines) along with used 

axles and/or transmissions. The common commercial term “glider kit” is used here primarily to refer to a chassis 

into which the used/rebuilt engine is installed. 
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standards for GHGs in the Phase 1 rule. Thus, before MY 2014, EPA did not have separate 

standards for vehicles over 14,000 pounds GVWR. However, EPA Phase 1 GHG vehicle 

standards apply for new MY 2014 and later vehicles over 14,000 pounds. Thus, EPA generally

considers glider kits to be subject to the Phase 1 vehicle standards, and to have been subject to 

them from the advent of the Phase 1 program.

However, with respect to engines installed in glider kits, an EPA Phase 1 provision in 40 

CFR 1037.150(j) provided an exception allowing the use of used or rebuilt engines892 that were 

certified to model year 2013 or earlier (or model year 2015 or earlier for spark ignition engines). 

The effect of this transition provision during Phase 1 was to allow glider kits to use engines not 

certified to meet the engine GHG or fuel consumption standards, although the glider kits were 

still required to have an EPA vehicle certificate with respect to GHG emissions. In addition,

another provision of Phase 1 in 40 CFR 1037.150(c) exempted gliders and glider kits produced 

by small businesses from the need to obtain a vehicle certificate, but did not include such a 

blanket exemption for non-small business gliders and glider kits. Thus, depending on the size of 

the business producing the glider kit, gliders and glider kits may currently be subject to the 

requirement to obtain a vehicle certificate prior to introduction into commerce as a new vehicle. 

(2) Proposed Amendment to EPA Vehicle Standards. 

EPA is proposing to end both 40 CFR 1037.150 provisions. EPA’s proposed program 

would generally treat glider vehicles the same as other new vehicles. As a result, glider vehicles 

would have to be certified to the Phase 2 vehicle standards, which (among other things) would 

require a fuel map for the actual engine in order to run GEM. In other words, manufacturers 

producing glider kits would need to meet the applicable GHG vehicle standards and, as part of its 

compliance demonstration, would need to have a fuel map for each engine that would be used. 

EPA is proposing this provision because we believe there has been adequate time for 

glider manufacturers to transition to a compliance regime. Moreover, as noted more fully below, 

with increased numbers of glider kits being produced, perpetuation of the interim exemption 

from Phase 1 would turn a transition provision into an on-going loophole. Nevertheless, EPA is 

proposing to replace this provision with a limited allowance for small business manufacturers as 

described in the proposed 40 CFR 1037.635. EPA is also proposing new definitions of “glider 

vehicle” and “glider kit” in 40 CFR 1037.801 that are generally consistent with the common 

understanding of these terms as meaning new chassis with a used engine or designed to accept a 

used engine.

(3) Proposed Change to EPA Engine Standards

EPA is also proposing to amend its rules to require that engines used in glider vehicles 

must be certified to the standards applicable to the calendar year in which assembly of the glider 

vehicle is completed. This requirement would apply to all pollutants, and thus would encompass 

 

892 Most glider vehicles being produced today are assembled with rebuilt engines. However, it is also possible to use

previously used engines that are not rebuilt.
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criteria pollutant standards as well as GHG standards. Used or rebuilt engines could be used, as 

long as they had been certified to the same standards as apply for the calendar year of glider 

vehicle assembly. For example, if assembly of a glider vehicle was completed in calendar year 

2020, the engine standards applicable to MY 2020 engines would have to be satisfied. (If the 

engine standards for model year 2020 were the same as for model years 2017 through 2019, then 

any model year 2017 or later engine could be used.)

EPA is proposing to amend these rules because, with the advent in MY 2007 of more 

stringent HD diesel engine criteria pollutant standards, continuation of provisions allowing 

rebuilt and reused engines to meet earlier MY criteria pollutant standards results in unnecessarily 

high in-use emissions. GHG emissions from these engines also are controllable. As more glider 

kits are produced, EPA believes that these emissions should be controlled to the same levels as 

other new engines.

Since EPA has already justified the criteria pollutant emission standards for heavy duty 

diesel engines pursuant to CAA section 202 (a)(3)(C), it is not clear that any further justification 

for applying those standards to engines used in glider kits is needed. The GHG engine standards 

for Phase 1 have likewise already been justified, and the proposed Phase 2 engine standards’ 

justification is set out in Section II above. If any further justification is required, EPA notes that 

the emission benefits of applying current criteria pollutant standards would be substantial, and at 

low cost. Glider vehicle production is not being reported to EPA, and we cannot determine 

precisely how much of an emission impact these vehicles are having. Nevertheless, since the 

current standards for NOX and PM are at least 90 percent lower than the most stringent 

previously applicable standards, we can be certain that the NOX and PM emissions of any glider 

vehicles using pre-2007 engines are at least ten times as high as emissions from equivalent 

vehicles being produced with brand new engines.893 Thus, each glider vehicle that is purchased 

instead of a new vehicle with a current MY engine results in significantly higher in-use 

emissions. EPA recognizes that the environmental impacts of gliders using 2010 and later 

engines would be much smaller, and requests comment on whether we should treat such gliders 

differently than gliders using older engines.

These emission impacts are being compounded by the increasing sales of these vehicles. 

Estimates provided to EPA indicate that production of glider vehicles has increased by an order 

of magnitude from what it was in the 2004-2006 time frame – from a few hundred each year to 

thousands.894 While the few hundred glider vehicles produced annually in the 2004-2006 

timeframe may have been produced for arguably legitimate purposes such as salvaging 

powertrains from vehicles otherwise destroyed in accidents, EPA believes the tenfold increase in 

glider kit production since the MY 2007 criteria pollutant emission standards took effect reflects 

an attempt to circumvent these more stringent standards and (ultimately) the Clean Air Act. 

 

893 The NOX and PM standards for MY 2007 and later engines are 0.20 g/hp-hr and 0.01 g/hp-hr, respectively. The 

standards for MY 2004 through 2006 engines were ten times these levels, and earlier standards were even higher. 

894 “Industry Characterization of Heavy Duty Glider Kits”, MacKay & Company, September 30, 2013.
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The cost for manufacturers to comply with the vehicle-based GHG standards is similar

for gliders as for other new vehicles. Similar to EPA’s analysis of emissions above, although we 

cannot precisely quantify the cost of complying with the proposed engine requirements for 

criteria pollutant standards because it is dependent on which engines would be used and which 

would have otherwise been used, EPA nevertheless believes that cost-effectiveness (dollars per 

ton) of the proposed requirement relative to any pre-2007 engine would be similar to the costeffectiveness of the NOX and PM standards for current model year engines, which EPA has 

already found to be cost effective. 

The agencies (as well as the broader SBAR Panel) are, however, concerned about adverse 

economic impacts on small businesses that assemble gliders and build glider kits, and we 

recognize that production of a smaller number of gliders by these small manufacturers may be 

appropriate for salvaged engines or other non-circumvention purposes. Therefore, EPA is 

proposing a new provision that would preserve its regulatory status quo for existing small 

businesses, but cap annual production based on recent sales. Thus, a limited number of glider 

kits produced by small businesses would not have to meet the GHG vehicle standards, and could 

use rebuilt or used engines provided those engines were certified to the year of the engine’s 

manufacture. For example, an existing small business that produced between 100 and 200 glider 

vehicles per year would be allowed to produce up to 200 glider vehicles per year under without 

having to certify them to the GHG standards, or re-certifying the engines to the now-applicable 

EPA standards for criteria pollutants and GHGs (so long as the engine is certified to criteria 

pollutant standards for the year of its manufacture). To be eligible for this provision, EPA is also 

proposing that no small entity could produce more than 300 glider vehicles in any given model 

year without certifying (or recertifying) to any EPA standards. EPA believes that this level 

reflects the upper end of the range of production that occurred before significant circumvention 

of the 2007 criteria pollutant standards began. We request comment on the appropriate caps

(including the appropriate magnitude of the caps) and on whether any other special provisions 

would be needed to accommodate glider kits. EPA also requests comment on whether we should 

allow larger manufacturers to produce some limited number of glider kits.

(4) Lead Time for Amended Standards

EPA is proposing that this requirement for gliders to meet engine and vehicle standards 

applicable to other new vehicles and engines take effect on January 1, 2018. EPA believes this 

provides sufficient time to “permit the development and application of the requisite control 

measures” (CAA section 202 (a)(3)(D)) because compliant engines are available today, although 

manufacturers would need several months to change business practices to comply. EPA also 

solicits comment on whether an earlier or later compliance date would be appropriate. We also 

request comment on whether we should include a production limit if we provide additional lead 

time in the Final Rule.

(5) Legal authority and Definitions under the Clean Air Act

With respect to statutory authority under the Clean Air Act, EPA notes first that it has 

broad authority to control all pollutant emissions from “any” rebuilt heavy duty engines 

(including engines beyond their statutory useful life). See CAA section 202 (a)(3)(D). EPA is to 

give “appropriate” consideration to issues of cost, energy, and safety in developing such 
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standards, and to provide necessary lead time to implement those standards. As noted above, if a 

used engine is placed in a glider kit, the engine would be considered a “new motor vehicle 

engine” because it is being used in a new motor vehicle (as explained in the following 

paragraph). See CAA section 216 (3). With respect to the vehicle-based GHG standards, there 

is no question that the completed glider is a “motor vehicle” under the Clean Air Act (as well as 

under NHTSA’s safety provisions). Some in the trucking industry have questioned whether a

glider kit (without an engine) is a motor vehicle. However, EPA considers glider kits to be 

incomplete motor vehicles, and EPA has the authority to regulate incomplete motor vehicles, 

including unmotorized chassis. 

Under the CAA, it is also important that “new” is determined based on legal title and 

does not consider prior use. Thus, glider kits that have a new vehicle identification number 

(VIN) and new title are considered to be “new motor vehicles” even if they incorporate 

previously used components. Note that under the Clean Air Act, EPA would not consider the 

fact that a vehicle retained the VIN of the donor vehicle from which the engine was obtained

determinative of whether or not the vehicle is new. 

The CAA also defines “manufacturer” to include any person who assembles new motor 

vehicles. EPA is proposing to revise its regulatory definitions of these terms in 40 CFR 

1036.801 and 1037.801 to more clearly reflect these aspects of the CAA definitions – that glider 

kits are “new motor vehicles”, previously used engines (whether rebuilt or not) installed into 

glider kits are “new motor vehicle engines”, and any person who completes assembly of a glider

is a “manufacturer”. EPA also notes that under the existing 40 CFR 1037.620, glider kit 

assemblers would generally be considered to be secondary vehicle manufacturers. That section, 

which EPA is proposing to redesignate as 40 CFR 1037.622, allows secondary vehicle 

manufacturers that have a valid certificate or exemption to receive incomplete vehicles (such as 

glider kits) from OEMs. 

). To further clarify that EPA considers both glider kits and completed glider vehicles to 

be motor vehicles, EPA is proposing to add a clarification to our definition of “motor vehicle” in 

40 CFR 85.1703 regarding vehicles such as gliders that clearly are intended for use on highways, 

consistent with the CAA definition of “motor vehicle” in CAA section 216 (2). The regulatory

definition presently contains a provision stating that vehicles lacking certain safety features 

required by state or federal law are not “motor vehicles”. This caveat needs a proper context: is 

the safety feature one that would prevent operation on highways. If not, absence of that feature 

does not result in the vehicle being other than a motor vehicle. The proposed amendment would 

consequently make clear that vehicles that are clearly intended for operation on highways are 

motor vehicles, even if they do not have every safety feature. (EPA is also considering whether 

to simply eliminate the clause “or safety features required by state and/or federal law” from the 

regulatory definition.) This clarifying provision would take effect upon promulgation. 

We note that NHTSA and EPA have separate definitions for motor vehicles under their 

separate statutory authorities. As such, EPA's determination of how its statute and regulations 

apply to glider kits and glider vehicles has no bearing on how NHTSA may apply its safety

authority with regard to them. See Section XIV. B. (6) for additional discussion of NHTSA’s 

consideration of glider vehicles. 
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(6) Relation to NHTSA Fuel Efficiency Program and Safety Regulations

NHTSA does not consider glider kits to be motor vehicles, but it does consider assembled 

glider vehicles to be motor vehicles. As stated above, NHTSA is considering including glider 

vehicles under its Phase 2 standards. NHTSA seeks comments from glider manufacturers on 

this consideration.

We believe that the agencies potentially having different policies for glider kits and glider 

vehicles under the Phase 2 program would not result in problematic disharmony between the 

NHTSA and EPA programs, because of the small number of vehicles that would be 

involved. EPA believes that its proposed changes would result in the glider market returning to 

the pre-2007 levels, in which fewer than 1,000 glider vehicles would be produced in most 

years. Given that a large fraction of these vehicles would be exempted from EPA regulations 

because they would be produced by qualifying small businesses, they would thus, in practice, be 

treated the same under EPA and NHTSA regulations. Only non-exempt glider vehicles would 

be subject to different requirements under the NHTSA and EPA regulations. However, we 

believe that this is unlikely to exceed a few hundred vehicles in any year, which would be few 

enough not to result in any meaningful disharmony between the two agencies.

With regard to NHTSA’s safety authority over gliders, the agency notes that it has 

become increasingly aware of potential noncompliances with its regulations applicable to 

gliders. NHTSA has learned of manufacturers who are creating glider vehicles that are new 

vehicles under 49 CFR 571.7(e), however, the manufacturers are not certifying them and 

obtaining a new VIN as required. NHTSA plans to pursue enforcement actions as applicable

against noncompliant manufacturers. In addition to enforcement actions, NHTSA may consider 

amending 49 CFR 571.7(e) and related regulations as necessary. NHTSA believes 

manufacturers may not be using this regulation as originally intended.

C. Applying the General Compliance Provisions of 40 CFR Part 1068 to 

Light-Duty Vehicles, Light-Duty Trucks, Chassis-certified Class 2B and 3 

Heavy-Duty Vehicles and Highway Motorcycles

As described above, EPA is proposing to apply all the general compliance provisions of 

40 CFR part 1068 to heavy-duty engines and vehicles. EPA proposes to also apply the recall 

provisions and the hearing procedures from 40 CFR part 1068 for highway motorcycles and for 

all vehicles subject to standards under 40 CFR part 86, subpart S. See the preceding section for a 

description of how the provisions from 40 CFR part 1068 compare to those in 40 CFR part 85 

and part 86.

EPA also requests comment on applying the rest of the provisions from 40 CFR part 

1068 to highway motorcycles and to all vehicles subject to standards under 40 CFR part 86, 

subpart S. EPA particularly requests comment on applying the defect-reporting provisions in 40 

CFR 1068.501 to these vehicles. The general approach is to replace a fixed threshold of 25 

defects as the basis for defect reporting with a scaled approach that would require defect 

reporting only after the manufacturer finds some larger number of actual emission-related 

defects. The regulation calls for manufacturers to monitor possible emission-related defects as 
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evidenced by warranty claims, in-use testing, and other indicators, and to start investigating for 

actual defects once possible defects exceed an established threshold. The existing regulation in 

40 CFR 1068.501 generally calls for investigating once possible defects exceed 5 to 10 percent 

of production, with a requirement to report defects if confirmed defects exceed a rate of 1 to 2 

percent of production. The percentage thresholds that apply for a given engine/vehicle model 

decrease with increasing production volumes. This approach is similar to defect-reporting 

requirements that already apply in California. Manufacturers may be interested in complying 

with a single set of defect-reporting provisions nationwide; EPA therefore also requests comment 

on simply requiring manufacturers to follow the California defect-reporting scheme for their 

EPA-certified vehicles.

Note that EPA is proposing to amend 40 CFR 85.1701 to specify that the exemption 

provisions apply to heavy-duty engines subject to regulation under 40 CFR part 86, subpart A. 

This is intended to limit the scope of this provision so that it does not apply for Class 2b and 3 

heavy-duty vehicles subject to standards under 40 CFR part 86, subpart S. This change corrects 

and inadvertently broad reference to heavy-duty vehicles in 40 CFR 85.1701.

D. Amendments to General Compliance Provisions in 40 CFR Part 1068

The general compliance provisions in 40 CFR part 1068 apply broadly too many different 

types of engines and equipment. This section describes how EPA is proposing to amend these 

procedures to make various corrections and adjustments. 

(1) Hearing Procedures

EPA is proposing to update and consolidate its regulations related to formal and informal 

hearings in 40 CFR part 1068, subpart G. This will allow us to rely on a single set of regulations 

for all the different categories of vehicles, engines, and equipment that are subject to emission 

standards. EPA also made an effort to write these regulations for improved readability. 

The hearing procedures specified in 40 CFR part 1068 apply to the various categories of 

nonroad engines and equipment (along with the other provisions of part 1068). EPA is 

proposing in these rules to apply these hearing procedures also to heavy-duty highway engines, 

light-duty motor vehicles, and highway motorcycles. EPA believes there is no reason to treat 

any of these sectors differently regarding hearing procedures.

EPA is proposing an introductory section that provides an overview of requesting a 

hearing for all cases where a person or a company objects to an adverse decision by the agency. 

In certain circumstances, as spelled out in the regulations, a person or a company can request a 

hearing before a Presiding Officer. Statutory provisions require formal hearing procedures for 

administrative enforcement actions seeking civil penalties. The Clean Air Act does not require a 

formal hearing for other agency decisions; EPA is therefore proposing to specify that informal 

hearing procedures apply for all such decisions. 

The introductory section also adds detailed provisions describing the requirements for 

submitting information to the agency in a timely manner. These provisions accommodate 

current practices for electronic submission, distinguish between postal and courier delivery and 
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provide separate requirements for shipments made from inside and outside the United States. 

The specified deadlines are generally based on the traditional approach of a postmark 

determining whether a submission is timely or not. Fax, e-mail and courier shipments are 

similarly specified as needing to be sent by close of business on the day of the deadline. A 

different approach applies for shipments originating from outside the United States. Because 

time in transit can vary dramatically, we are proposing to specify that foreign shipments need to 

be received in our office by the specified deadline to be considered timely. Given the option to 

send documents by e-mail or by fax, EPA expects this approach would not pose any

disadvantage to anyone making an appeal from outside the United States.

EPA is proposing to replace the current reference to 40 CFR 86.1853-01 for informal 

hearings with a full-text approach that captures this same material. EPA attempted to write these 

proposed regulations in a way that would not change the underlying hearing protocol. 

The regulations currently reference the formal hearing procedures in 40 CFR 85.1807, 

which were originally drafted to apply to light-duty motor vehicles. After we adopted the 

hearing procedures in 40 CFR 85.1807, EPA’s Office of Administrative Law Judges finalized a 

set of regulations defining formal hearing procedures that were intended to apply broadly across 

the agency for appeals under every applicable statute. See 40 CFR part 22, “Consolidated Rules 

of Practice Governing the Administrative Assessment of Civil Penalties and the 

Revocation/Termination or Suspension of Permits.” EPA is therefore revising the regulations in 

40 CFR part 1068 to simply refer to these formal hearing procedures in 40 CFR part 22. 

(2) Additional Changes to General Compliance Provisions

EPA is also proposing to make numerous changes across 40 CFR part 1068 to correct 

errors, to add clarification, and to make adjustments based on lessons learned from implementing 

these regulatory provisions. This includes the following proposed changes:

 §1068.1: Clarify applicability of part 1068 with respect to legacy parts (such as 40 CFR parts

89 through 94).

 §1068.20: Clarify that EPA’s inspection activities do not depend on having a warrant or a 

court order. As noted in the standard-setting parts, EPA may deny certification or suspend or 

revoke certificates if a manufacturer denies EPA entry for an attempted inspection or other 

entry.

 §1068.27: Clarify that EPA confirmatory testing may properly be performed before issuance 

of a certificate of conformity. We are also making an addition to state that we may require 

manufacturers to give us any special components that are needed for EPA testing.

 §1068.30: Add definitions of “affiliated companies”, “parent company”, and “subsidiaries” 

to clarify how small-business provisions apply for a range of business relationships.

 §1068.30: Clarify that a manufacturer can be considered a certificate holder based on the 

current or previous model year (to avoid problems from having a gap between model years).

 §1068.30: Spell out contact information for the “Designated Compliance Officer” to clarify

how manufacturers should submit information to the agency. This includes e-mail addresses 

for the various sectors.

 §1068.32: Add discussion to establish the meaning of various terms and phrases for EPA 

regulations; for example, we distinguish between standards, requirements, allowances, 
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prohibitions, and provisions. EPA is also clarifying terminology with respect to 

singular/plural, inclusive lists, notes and examples in the regulatory text, and references to 

“general” or “typical” circumstances. EPA also describes some of the approach to 

determining when “unusual circumstances” apply. 

 §1068.45: Allow manufacturers to use coded dates on engine labels; allow EPA to require 

the manufacturer to share information to read the coded information.

 §1068.45: Clarify that engine labels are information submissions to EPA.

 §§1068.101 and 1068.125: Update penalty amounts to reflect changes to 40 CFR part 19.

 §1068.101: Revise the penalty associated with the tampering prohibition to be an enginebased penalty, as opposed to assessing penalties per day of engine operation. This correction 

aligns with Clean Air Act section 205.

 §1068.103: Clarify the process for reinstating certificates after suspending, revoking, or 

voiding.

 §1068.103: Clarify that the prohibition against “offering for sale” uncertified engines applies 

only for engines already produced. It is not a violation to invite customers to buy engines as 

part of an effort to establish the economic viability of producing engines, as would be 

expected for market research.

 §1068.105: Require documentation related to “normal inventory” for stockpiling provision. 

EPA is also clarifying that there is no specific deadline associated with producing “normalinventory” engines under this section, but emphasizing that vehicle/equipment manufacturers 

may not delay engine installation beyond their normal production schedules. EPA is also 

clarifying that the allowance related to building vehicles/equipment in the early part of a 

model year, before the start of a new calendar year corresponding to new emission standards, 

applies only in cases where vehicle/equipment assembly is complete before the start of the 

new calendar year. This is intended to prevent manufacturers from circumventing new 

standards by initiating production of large numbers of vehicles/equipment for eventual 

completion after new standards have started to apply.

 §1068.115: Clarify warranty provisions to align with statute.

 §1068.120: Describe how the rebuilding provisions apply in the case of engine replacements 

where the new and old engines are subject to standards under different standard-setting parts 

(such as switching from spark-ignition to compression-ignition nonroad engines). 

 §1068.201: Describe how someone may sell an engine under a different exemption than was 

originally intended or used.

 §1068.210: Remove the requirement for companies getting approval for a testing exemption 

to send us written confirmation that they meet the terms and conditions of the exemption. 

We do not believe this submission is necessary for implementing the testing exemption.

 §1068.220: Add description of how we might approve engine operation under the display

exemption. This is intended to more carefully address circumstances in which engine 

operation is part of the display function in question. We would want to consider a wide 

range of factors in considering such a request; for example, we could be more inclined to 

approve a request for a display exemption if the extent of operation is very limited, or if the 

engine/equipment has emission rates that are comparable to what would apply absent the 

exemption. EPA is also removing the specific prohibition against generating revenue with 

exempted engines/equipment, since this has an unclear meaning and we can take any possible 
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revenue generation into account in considering whether to approve the exemption on its 

merits.

 §1068.230: Add provision allowing for engine operation under the export exemption only as 

needed to prepare it for export (this has already been in place in part 85, and in part 1068 for 

engines/equipment imported for export).

 §1068.235: Clarify that the standard-setting part may set conditions on an exemption for 

competition engines/equipment.

 §1068.240: Describe the logistics for identifying the disposition of engines being replaced 

under the replacement engine exemption. In particular, manufacturers would need to identify

the disposition of each engine by the due date for the report under §1068.240(c) to avoid 

counting them toward the production limit for untracked replacement engines. We are 

proposing to delay the due date for the report until September 30 following the production 

year to allow more time for manufacturers to make these determinations.

 §1068.240: Clarify the relationship between paragraphs (d) and (e).

 §1068.250: Simplify the deadline for requesting small-volume hardship.

 §1068.255: Clarify that hardship provisions for equipment manufacturers are not limited to 

small businesses, and that a hardship approval is generally limited to a single instance of 

producing exempt equipment for up to 12 months.

 §1068.260: State that manufacturers shipping engines without certain emission-related 

components need to identify the unshipped components either with a performance 

specification (where applicable) or with specific part numbers. We are also listing exhaust 

piping before and after aftertreatment devices as not being emission-related components for 

purposes of shipping engines in a certified configuration.

 §§1068.260 and 1068.262: Revise the text to clarify that provisions related to partially

complete engines have limited applicability in the case of equipment subject to equipmentbased exhaust emission standards (such as recreational vehicles). These provisions are not 

intended to prevent the sale of partially complete equipment with respect to evaporative 

emission standards. We intend to address this in the future by changing the regulation in 40 

CFR part 1060 to address this more carefully.

 §1068.262: Revise text to align with the terminology and description adopted for similar 

circumstances related to shipment of incomplete heavy-duty vehicles under 40 CFR part 

1037.

 §1068.301: Revise text to explicitly allow forelectronic submission of EPA declaration forms 

and other importation documents.

 §1068.305: Remove the provision specifying that individuals may need to submit taxpayer 

identification numbers as part of a request for an exemption or exclusion for imported 

engines/equipment. We do not believe this information is necessary for implementing the 

exemption and exclusion provisions.

 §1068.315: Allow for destroying engines/equipment instead of exporting them under the 

exemption for importing engines/equipment for repairs or alterations.

 §1068.315: Remove the time constraints on approving extensions to a display exemption for 

imported engines/equipment. EPA would continue to expect the default time frame of one 

year to be appropriate, and extension of one to three years is sufficient for most cases; 

however, we are aware that there are occasional circumstances calling for a longer-term 
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exemption. For example, an engine on display in a museum might appropriately be 

exempted indefinitely once its place in a standing exhibition is well established.

 §1068.315: Specify that engines under the ancient engine exemption must be substantially in 

the original configuration.

 §1068.360: Clarify the provisions related to model year for imported products by removing a 

circularity regarding “new” engines and “new” equipment.

 §1068.401: Add explicit statement that SEA testing is at manufacturer’s expense. This is 

consistent with current practice and the rest of the regulatory text.

 §1068.401: Allow for requiring manufacturers other than the certificate holder to perform 

selective enforcement audits in cases where multiple manufacturers are cooperatively 

producing certified engines.

 §1068.401: State that SEA non-cooperation may lead to suspended or revoked certificate 

(like production-line testing).

 §1068.415: Set up new criteria for lower SEA testing rate based on engine power to allow for 

a reduced testing rate of one engine per day only for engines with maximum engine power 

above 560 kW, but keep the allowance to approve a lower testing rate; that may be needed, 

for example, if engine break-in (stabilization) and testing are performed on the same 

dynamometer. EPA believes it is more appropriate to base reduced testing rates on engine 

characteristics rather than sales volumes, as has been done in the past.

 §1068.415: Revise the service accumulation requirement to specify a maximum of eight days 

for stabilizing a test engine. This is necessary to address a situation where an engine operates 

only six hours per day to achieve stabilization after well over 50 hours. For such cases, we 

would expect manufacturers to be able to run engines much more than six hours per day. As 

with testing rates, manufacturers may ask for our approval to use a longer stabilization period 

if circumstances don’t allow them to meet the specified service accumulation targets. 

 §1068.501, and Appendix I: Clarify that “emission-related components” include components 

whose failure would commonly increase emissions (not might increase), and whose primary

purpose is to reduce emissions (not sole purpose); current regulations are not consistent.

 §1068.501: Add “in-use testing” to list of things to consider for investigating potential 

defects.

 §1068.505: Clarify that manufacturers subject to a mandatory recall must remedy

noncompliant target vehicles without regard to their age or mileage at the time of repair, 

consistent with provisions that already apply under 40 CFR part 85.

 §1068.505: Revise the requirement for submitting a remedial report from a 60-day maximum 

to a 45-day minimum (or 30-day minimum in the event of a hearing). This adjusted approach 

already applies to motor vehicles under 40 CFR part 85.

 §1068.515: Clarify an ambiguity to require that manufacturers identify the facility where 

repairs or inspections are performed.

 §1068.530: Specify that recall records must be kept for five years, rather than three years. 

This is consistent with longstanding recall policy for motor vehicles and motor vehicle 

engines under 40 CFR part 85.

Manufacturers and equipment operators have raised an additional question about how the 

regulations apply for replacement engines where the replacement engine is of a different type 

than the engine being replaced. For example, someone operating a piece of industrial equipment 

may want to replace an old spark-ignition engine with a compression-ignition engine (or vice 
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versa). The replacement engine could be freshly manufactured, or it may have already been 

placed into service. The tampering prohibition would generally disallow “disabling emission 

controls,” but regulations do not directly address how this applies relative to the multiple 

emission standards that apply. It is important to note that the standard-setting part often specifies 

that a used replacement engine becomes new (and subject to certification requirements) if it is 

installed in a piece of equipment from a different category. For example, installing a used 

heavy-duty highway engine in land-based nonroad equipment would make the engine “new” and 

subject to certification requirements as a nonroad engine. This does not apply for spark-ignition 

engines and compression-ignition engines installed in heavy-duty highway vehicles, or for sparkignition engines and compression-ignition engines installed in land-based nonroad equipment. 

We request comment on the best approach to delineating how the tampering prohibition should 

apply for these scenarios.

E. Amendments to Light-Duty Greenhouse Gas Program Requirements

EPA is proposing to make minor changes to correct errors and clarify regulations in 40 

CFR part 86, subpart S, and part 600 relating to EPA’s light-duty greenhouse gas emission 

standards. This includes the following proposed changes:

 §86.1818-12: Correct a reference in paragraph (c)(4) and clarify that CO2-equivalent debits 

for N2O and CH4 are calculated in Megagrams and rounded to the nearest whole Megagram.

 §86.1838-01: Correct references in paragraph (d)(3)(iii).

 §86.1866-12: Correct a reference in paragraph (b). 

 §86.1868-12: Clarify language in the introductory paragraph explaining the model years of 

applicability of different provisions for air conditioning efficiency credits. In paragraph (e)(5) 

clarify that the engine-off specification of 2 minutes is intended to be cumulative time. In 

paragraphs (f)(1), (g)(1), and (g)(3), clarify language by pointing to the definitions in 

§86.1803-01.

 §86.1869-12: Make corrections to the language for readability in paragraph (b)(2). In 

paragraph (b)(4)(ii) delete the phrase “backup/reverse lights” because these lights were not 

intended to be part of the stated eligibility criteria for high-efficiency lighting credits. Correct 

references in paragraph (f). 

 §86.1870-12: Add language that clarifies that a manufacturer that meets the minimum 

production volume thresholds with a combination of mild and strong hybrid electric pickup 

trucks is eligible for credits. 

 §86.1871-12: Clarify that credits from model years 2010-2015 are not limited to a life of 5 

model years. A recent rule extended the life of 2010-2015 credits to model year 2021; thus,

language referring to a 5-year life for emission credits generated in these model years is 

being removed or revised.

 §600.113-12: Correct language in paragraph (m)(1), which relates to vehicles operating on 

LPG, that erroneously refers to methanol and methanol-fueled. 

 §600.113-12: Correct references in paragraph (n) and add a new paragraph (m) that reinstates 

language mistakenly dropped by a previous regulation. 
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 §600.116-12: Correct description of physical quantity to refer to “energy” rather than 

“current”, and correct various paragraph references.

 §600.208-12: Correct a reference in paragraph (a)(2)(iii).

 §600.210-12: Correct a reference and text in paragraph (c)(2)(iv)(C). 

F. Amendments to Highway and Nonroad Test Procedures and Certification 

Requirements

(1) Testing with Aftertreatment Devices Involving Infrequent Regeneration

Manufacturers generally rely on selective catalytic reaction and diesel particulate filters 

to meet EPA’s emission standards for highway and nonroad compression-ignition engines. 

These emission control devices typically involve infrequent regeneration, which can have a 

significant effect on emission rates. EPA has addressed that for each engine type by provisions 

for infrequent regeneration factors; this is a calculation methodology that allows manufacturers 

to incorporate the effect of infrequent regeneration into reported emission values whether or not 

that regeneration occurs during an emission test. EPA adopted separate provisions for highway, 

locomotive, marine, and land-based nonroad compression-ignition engines. EPA is proposing to 

harmonize the common elements of these procedures in 40 CFR part 1065, and to add clarifying 

specifications in each of the standard-setting parts for sector-specific provisions.

(2) Mapping for Constant-Speed Engines under 40 CFR Part 1065

EPA is proposing to revise this section as it applies to the two-point mapping method for 

certain constant-speed engines. The regulations currently cite a performance parameter in ISO 

8528-5 that does not apply for the design of these engines.

Common practice for engines that produce electric power is to use an isochronous 

governor for stand-alone generator sets. In some parallel operations of multiple generator sets, 

droop is added as a method for load sharing. The amount of droop can be tuned by the generator 

set manufacturer or the site system integrator. Such engines are commonly tested on an engine 

dynamometer with the isochronous governor.

Mapping with just two points works well for the case of 0 percent droop (i.e. isochronous 

governor). For this case, a persistent speed error is forced on the engine governor on the second 

point and this will cause the governor to wind up to its maximum command. The second point is 

effectively operating on the torque curve instead of the isochronous governor. So, the second 

point captures the full fueling torque (plus a small amount due to any rising torque curve). This 

measured torque is used as the maximum test torque for computing the emission test points. 

Since there is no designed-in droop, some target amount of speed error is needed for the second 

point. The regulation at 40 CFR 1065.510(d)(5)(iii) currently has a default target speed on the 

second point of 97.5 percent of the no-load speed measured on the first point. This results in a 

persistent speed error of 2.5 percent of the no-load speed. For an 1800 rpm no-load speed, this 

would give a target speed of 1755 rpm and a 45 rpm speed error on an isochronous governor. If 

the engine has a torque rise of 20 percent from 1800 to 1200 rpm (0.0333 percent torque rise per 

rpm), this 45 rpm error will cause a 1.5 percent of point error in the determination of the intended 
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maximum test torque. This error is larger than desired for this type of testing. Fortunately, 

engines and test cells have sufficient speed resolution to select a lower speed error, which 

reduces this error in maximum test torque. In practice, testing with a speed error at or below 0.5 

percent is more than adequate to cause the isochronous governor to wind up to maximum 

fueling. Using a target speed of 99.5 percent on the second point gives a target speed of 1791 

rpm for an 1800 rpm no-load speed and will reduce the error on the maximum test torque to a 

reasonable 0.3 percent of point for the 20 percent torque rise case described above.

For governors with droop, if we attempt the two-point method, we would have to 

calculate a target speed for the second point based on a designed amount of droop. 

Unfortunately, the actual governor may not have the same amount of droop as the design droop, 

which may cause error in the measured torque versus the maximum test torque associated with a 

complete torque map. Also, the design droop may be based on a torque value that is different 

from the intended maximum test torque. Thus, the two-point method is not sufficient to yield a 

maximum test torque equivalent to the value that would be obtained using a multi-point map. 

Also the allowed speed error on the second point is 20 percent of the speed droop, which allows 

an unacceptably large error in the maximum test torque.

Thus, for the reasons listed, we are proposing to limit the two-point mapping method to 

any isochronous governed engines, not just engines used to generate electric power.

(3) Calculating Maximum and Intermediate Test Speeds under 40 CFR Part 1065

EPA is proposing to improve the method for calculating maximum and intermediate test 

speeds by applying a more robust calculation method. The new calculation method would be 

consistent with the methodology used for the maximum test torque determination, which we 

revised in our light-duty Tier 3 rulemaking. Under the current regulations, the result is a 

measured maximum test torque at one of the map points. The proposed calculation method 

involves interpolation to determine the measured maximum test torque, yielding a more 

representative maximum test torque lbs. 

(4) Additional Test Procedure Amendments

EPA is proposing the following additional changes to test procedures in 40 CFR part 

1065 and part 1066:

 § 1065.15: Allow manufacturers to use NMOG measurements to demonstrate compliance 

with NMHC standards. We also request comment on whether other forms of hydrocarbon 

standards (such as VOC) should be allowed for alternative fuels. 

 § 1066.210: Revise the dynamometer force equation to incorporate grade, consistent with the 

coastdown procedures being proposed for heavy-duty vehicles. For operation at a level 

grade, the additional parameters cancel out of the calculation. 

 §1066.605: Adding an equation to the regulations to spell out how to calculate emission rates 

in grams per mile. This calculation is generally assumed, but we want to include the 

equation to remove any uncertainty about calculating emission rates from mass emission 

measurements and driving distance.
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 § 1066.815: Create an exception to the maximum value for overall residence time for PM 

sampling methods that involve PM samples collected for combined bags over a duty cycle. 

This is needed to accommodate the reduced sample flow rates associated with these 

procedures.

G. Amendments Related to Nonroad Diesel Engines in 40 CFR Part 1039

EPA is proposing two changes to 40 CFR 1039.5 to clarify the scope and applicability of 

standards under 40 CFR part 1039. First, EPA is stating that engines using the provisions of 40 

CFR 1033.625 for non-locomotive-specific engines remain subject to certification requirements 

as nonroad diesel engines under 40 CFR part 1039. Such engines would need to be certified as 

both locomotive engines and as nonroad diesel engines. Second, EPA is proposing to revise the 

statement about how manufacturers may certify under 40 CFR part 1051 for engines installed in 

recreational vehicles (such as all-terrain vehicles or snowmobiles). EPA is proposing to remove 

text that might be interpreted to mean that there are circumstances in which certification under 

neither part is required. The proper understanding of EPA’s policy in that regard is that 

certification under one part is a necessary condition for being exempted from the other part. 

In 2008, EPA adopted a requirement in 40 CFR part 1042 for manufacturers to design 

marine diesel engines using selective catalytic reduction with basic diagnostic functions to 

ensure that these systems were working as intended (73 FR 37096, June 30, 2008). EPA is

proposing to apply those same diagnostic control requirements to nonroad diesel engines

regulated under 40 CFR part 1039. This addresses the same fundamental concern that engines 

would not be controlling emissions consistent with the certified configuration if the engine is 

lacking the appropriate quantity and quality of reductant. While some lead time would be 

needed to make the necessary modifications, we believe it will be straightforward to apply the 

same designs from marine diesel engines to land-based nonroad diesel engines. EPA is 

accordingly proposing that manufacturers meet the proposed diagnostic specifications starting 

with model year 2018. These diagnostic controls would not affect the current policy related to 

adjustable parameters and inducements related to selective catalytic reduction. EPA requests

comment on adding these diagnostic requirements for nonroad diesel engines.

EPA is proposing to make numerous changes across 40 CFR part 1039 to correct errors, 

to add clarification, and to make adjustments based on lessons learned from implementing these 

regulatory provisions. This includes the following proposed changes:

 §1039.2: Add a clarifying note to say that something other than a conventional 

“manufacturer” may need to certify engines that become new after being placed into service 

(such as engines converted from highway or stationary use). This is intended to address a 

possible assumption that only conventional manufacturers can certify engines. 

 §§1039.30, 1039.730, and 1039.825: Consolidate information-collection provisions into a 

single section.

 §1039.107: Remove the reference to deterioration factors for evaporative emissions, since 

there are no deterioration factors for demonstrating compliance with evaporative emission 

standards.
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 §1039.104(g): Correct the specified FEL cap for an example scenario illustrating how

alternate FEL caps work.

 §1039.120: Reduce extended-warranty requirements to warranties that are actually provided 

to the consumer, rather than to any published warranties that are offered. The principle is 

that the emission-related warranty should not be less effective for emission-related items than 

for items that are not emission-related.

 §1039.125: Allow for special maintenance procedures that address low-use engines. For 

example, owners of recreational marine vessels may need to perform engine maintenance 

after a smaller number of hours than would otherwise apply based on the limited engine 

operation over time.

 §1039.125: Establish a minimum maintenance interval of 1500 hours for DEF filters. This 

reflects the technical capabilities for filter durability and the expected maintenance in the 

field. 

 §1039.125: Add fuel-water separator cartridges as an example of a maintenance item that is 

not emission-related. 

 §1039.135: Allow for including optional label content only if the manufacturer does not opt

to omit other information based on limited availability of space on the label, and identify

counterfeit protection as an additional item that manufacturers may include on the label.

 §1039.201: Clarify that manufacturers may amend their application for certification after the 

end of the model year in certain circumstances, but they may not produce engines for a given 

model year after December 31 of the named year.

 §1039.201: Establish that manufacturers may deliver to EPA for testing an engine that is 

identical to the test engine used for certification. This may be necessary if the test engine has 

accumulated too many hours, or if it is unavailable for any reason.

 §1039.205: Replace the requirement to submit data from invalid tests with a requirement to 

simply notify EPA in the application for certification if test was invalidated. 

 §1039.205: Add a requirement for manufacturers to include in their application for 

certification a description of their practice for importing engines, if applicable. Note that 

where a manufacturers’ engines are imported through a wide variety of means, EPA would 

not require this description to be comprehensive. In such cases, a short description of the 

predominant practices would generally be sufficient. We are also proposing to require 

manufacturers of engines below 560 kW to name a test lab in the United States for the 

possibility of us requiring tests under a selective enforcement audit. We have adopted these 

same requirements in many of our other nonroad programs.

 §1039.225: Clarify that manufacturers may amend the application for certification after the 

end of the model year only in certain circumstances, and not to add a new or modified engine 

configuration.

 §1039.235: Add an explicit allowance for carryover engine families to include the same kind 

of within-family running changes that are currently allowed over the course of a model year. 

The original text may have been understood to require that such running changes be made 

separate from certifying the engine family for the new model year.

 §§1039.235, 1039.240, and 1039.601: Describe how to demonstrate compliance with dualfuel and flexible-fuel engines. This generally involves testing with each separate fuel, or 

with a worst-case fuel blend. 
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 §1039.240: Add instructions for calculating deterioration factors for sawtooth deterioration 

patterns, such as might be expected for periodic maintenance, such as cleaning or replacing 

diesel particulate filters.

 §1039.240: Remove the instruction related to calculating NMHC emissions from measured 

THC results, since this is addressed in 40 CFR part 1065.

 §1039.250: Remove references to routine and standard tests, and remove the shorter 

recordkeeping requirement for routine data (or data from routine tests). All test records must 

be kept for eight years. With electronic recording of test data, there should be no advantage 

to keeping the shorter recordkeeping requirement for a subset of test data. EPA also notes 

that the eight-year period restarts with certification for a new model year if the manufacturer 

uses carryover data.

 §1039.255: Clarify that rendering information false or incomplete after submitting it is the 

same as submitting false or incomplete information. For example, if there is a change to any 

corporate information or engine parameters described in the manufacturer’s application for 

certification, the manufacturer must amend the application to include the new information.

 §1039.255: Clarify that voiding certificates for a recordkeeping or reporting violation would 

be limited to certificates that relate to the particular recordkeeping or reporting failure.

 §1039.505: Correct the reference to the ISO C1 duty cycle for engines below 19 kW.

 §1039.515: Correct the cite to 40 CFR 86.1370.

 §§1039.605 and 1039.610: Revise the reporting requirement to require detailed information 

about the previous year, rather than requiring a detailed projection for the year ahead. The 

information required in advance would be limited to a notification of plans to use the 

provisions of these sections.

 §1039.640: Migrate engine branding to §1068.45.

 §1039.701 1039.730: Describe the process for retiring emission credits. This may be referred 

to as donating credits to the environment.

 §1039.705: Change terminology for counting engines from “point of first retail sale” to 

“U.S.-direction production volume.” This conforms to the usual approach for calculating 

emission credits for nonroad engines. 

 §1039.710: Clarify that it is not permissible to show a proper balance of credits for a given 

model by using emission credits from a future model year.

 §1039.730: Clarify terminology for ABT reports.

 §1039.740: Clarify that the averaging-set provisions apply for credits generated by Tier 4 

engines, not for credits generated from engines subject to earlier standards that are used with 

Tier 4 engines.

 §1039.801: Update the contact information for the Designated Compliance Officer.

 §1039.801: Revise the definition of “model year” to clarify that the calendar year relates to 

the time that engines are produced under a certificate of conformity.

 §1039.815: Migrate provisions related to confidential information to 40 CFR part 1068.

EPA requests comment on removing regulatory provisions for Independent Commercial 

Importers in 40 CFR part 1039. These provisions, copied from highway regulations many years 

ago, generally allow for small businesses to modify small numbers of uncertified products to be 

in a certified configuration using alternative demonstration procedures. We are not aware of 

anyone using these provisions for nonroad engines in the last 15 years or more. We are therefore 
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interested in considering these provisions to be obsolete, in which case they can be removed 

without consequence.

H. Amendments Related to Marine Diesel Engines in 40 CFR Parts 1042 and 

1043

EPA’s emission standards and certification requirements for marine diesel engines under 

the Clean Air Act are identified in 40 CFR part 1042. 

(1) Continuous NOX Monitoring and On-off Controls

Manufacturers may produce certain marine diesel engines with on-off features that 

disable NOX controls when the ship is operating outside of a designated Emission Control Area 

(ECA) as long as certain conditions are met (§1042.115(g)). This provision, which applies to 

Category 3 engines meeting EPA Tier 3 standards, is intended to address the special operating 

conditions posed by an ECA and allows a ship that operates in and out of designated ECAs to 

downgrade engine NOX emission controls while the ship is operating outside of a designated 

ECA. This provision also applies for Tier 4 NOX standards for those Category 1 and Category 2 

auxiliary engines on Category 3 vessels covered by §1042.650(d); this provision does not apply

to any other auxiliary engines or to any non-Category 3 propulsion engines. Engines with 

allowable on-off controls must be certified to meet the previous tier of NOX standards when the 

advanced NOX control strategies are disabled (note that this would be Tier 2 for auxiliary engines 

as well as Category 3 engines, pursuant to §1042.650(d)).

Engines with on-off NOX controls are required to be equipped to continuously monitor 

NOX concentrations in the exhaust (§1042.110(d)). EPA has been asked to clarify what 

"continuous" means in the context of this requirement. Because the purpose of this requirement 

is to show that the engine complies with the NOX emission limits on a continuous basis, 

continuous monitoring must be frequent enough to demonstrate that the NOX controls are on and 

are properly functioning from the time the ship enters the ECA until it leaves, which, depending 

on the ECA and the ship's itinerary, could be a matter of hours or days. Since many

manufacturers equip their emission control systems with NOX sensors to monitoring and log the 

performance of the combined engine and emission control system, we are proposing that 

continuous monitoring means measuring NOX emissions at least every 60 seconds. EPA is also 

proposing that a manufacturer may request approval of an alternative measurement period if that 

is necessary for sufficiently accurate measurements. With regard to the functioning of 

continuous NOX monitoring, the continuous emission measurement device would be required to 

be included as part of the engine system for EPA certification. Continuous NOX monitoring 

would be required to be engaged before the ship enters an ECA and continue until after it exits 

the ECA. Verification of operation of the system would be included in required periodic vessel 

surveys and certification that cover nearly all commercial U.S. vessels. Enforcement is expected 

to be performed on a periodic basis by appropriate authorities when a ship is in port.

It should be noted that the above provisions with respect to on-off controls and 

continuous emission monitoring do not apply for the 40 CFR part 1042 PM standards. Engines 

certified to standards under 40 CFR part 1042 must meet the PM limits at all times, except when 

the operator has applied for and received permission to disable Tier 4 PM controls while 
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operating outside the United States pursuant to any of the provisions of 40 CFR 1042.650(a) 

through (c).

(2) Category 1 and Category 2 Auxiliary Engines on Category 3 Vessels

The regulation at 40 CFR 1042.650(d) exempts auxiliary Category 1 and Category 2 

engines installed on U.S.-flag Category 3 vessels from the part 1042 standards if those auxiliary

engines meet certain conditions. This is intended to allow operators of qualified vessels engaged 

in international trade to manage all their installed engines to meet international requirements 

without additional constraints related to any differences in EPA’s regulatory specifications, and 

to simplify compliance demonstrations while those vessels are operating in foreign ports and 

foreign waters.

EPA is proposing to revise the regulations to clarify that the urea reporting requirements 

in § 1042.660(b) (which requires an owner or operator of any vessel equipped with SCR to 

report to EPA within 30 days of any operation of such vessel without the appropriate reductant) 

also apply to Category 1 and Category 2 auxiliary engines on Category 3 vessels that are covered 

by § 1042.650(d). This will extend the urea reporting requirements to engines between 130 and 

600 kW if they rely on SCR to meet the Annex VI Tier III NOX limits. Engines covered by

§1043.650(d) would be subject to emission standards and testing requirements under MARPOL

Annex VI and the NOX Technical Code.

EPA is also proposing to revise 40 CFR 1042.650(d) to clarify that, while these Category

1 and Category 2 auxiliary engines may be designed with on-off NOX controls, they must be 

certified to meet IMO Tier II NOX standards anytime the IMO Tier III NOX configuration is 

disabled.

In addition, EPA has become aware that there is some uncertainty about how the scope of 

EPA’s implementation of Annex VI through 40 CFR part 1043 relates to engines with a power 

output of 130 kW or less. The existing regulations at §1043.30 state that an EIAPP certificate is 

required for engines with a power output above 130 kW, but the standards described in §1043.60 

might be interpreted to apply to engines of all sizes. EPA did not intend to create additional 

requirements or authority under part 1043 that is not contained in Annex VI or its implementing 

legislation (the Act to Prevent Pollution from Ships). EPA is therefore proposing to add 

clarifying language to §1043.60, consistent with Regulation 13 of Annex VI and APPS, to 

indicate that the international NOX limits do not apply to engines with a power output of 130 kW 

or less. Note that EPA will therefore not issue EIAPP certificates for engines with a power 

output of 130 kW or less even if manufacturers request it.

(3) Natural Gas Marine Engines

EPA is also proposing to expand provisions that apply for marine engines designed to 

operate on both diesel fuel and natural gas. Test requirements apply separately for each “fuel 

type”. EPA generally considers an engine with a single calibration strategy that combines an 

initial pilot injection of diesel fuel to burn natural gas to be a single fuel type. This applies even 

if the natural gas portion must be substantially reduced or eliminated to maintain proper engine 

operation at light-load conditions. If the engine has a different calibration allowing it to run only

on diesel fuel, or on continuous mixtures of diesel fuel and natural gas, we would consider it to 
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be a dual-fuel engine or a flexible-fuel engine, respectively. These terms are used consistently

across EPA programs for highway and nonroad applications. There is an effort underway to 

revise the definition of “dual-fuel” in MARPOL Annex VI, which may be different than EPA’s 

definition. It should be noted that the 40 CFR part 1042 certification testing requirement differs 

from that specified in MARPOL Annex VI and the NOX Technical Code. While the 

international protocol involves testing only on the engine calibration with the greatest degree of 

diesel fuel, EPA certification requires manufacturers to perform testing on each separate fuel 

type. This would involve one set of tests with natural gas (with or without a diesel pilot fuel, as 

appropriate), and an additional set of tests with diesel fuel alone. This has been required since 

we first adopted standards, and this is the same policy that applies across all our emission control 

programs. EPA also proposes to include amended regulatory language to more carefully 

describe these testing requirements, and to specify how this applies differently for dual-fuel and 

flexible-fuel engines.

(4) Additional Marine Diesel Amendments

EPA is proposing to make numerous changes across 40 CFR part 1042 to correct errors, 

to add clarification, and to make adjustments based on lessons learned from implementing these 

regulatory provisions. This includes the following proposed changes:

 §1042.1: Correct the tabulated applicability date for engines with per-cylinder displacement 

between 7 and 15 liters; this should refer to engines “at or above” 7 liters, rather than “above 

7 liters”. 

 §1042.1: Replace an incorrect reference to 40 CFR part 89 with a reference to 40 CFR part 

94 for marine engines above 37 kW.

 §1042.2: Add a clarifying note to say that something other than a conventional 

“manufacturer” may need to certify engines that become new after being placed into service 

(such as engines converted from highway or stationary use). This is intended to address a 

possible assumption that only conventional manufacturers can certify engines. 

 §§1042.30, 1042.730, and 1042.825: Consolidate information-collection provisions into a 

single section.

 §1042.101: Revise the text to more carefully identify engine subcategories and better 

describe the transition between Tier 3 and Tier 4 standards. These changes are intended to 

clarify which standards apply and are not intended to change the emission standards for any

particular size or type of engine. 

 §1042.101 and Appendix III: More precisely define applicability of specific NTE standards 

for different types of engines and pollutants; correct formulas defining NTE zones and 

subzones; and add clarifying information to identify subzone points that could otherwise be 

derived from existing formulas. None of these changes are intended to change the standards, 

test procedures, or other policies for implementing the NTE standards.

 §1042.101: Clarify the FEL caps for certain engines above 3700 kW.

 §1042.101: Add a specification to define “continuous monitor” for parameters requiring 

repeated discrete measurements, as described above. The proposal also includes further 

clarification on the relationship between on-off NOX controls and engine diagnostic systems.

 §1042.110: Remove the requirement to notify operators regarding an unsafe operating 

condition, since we can more generally rely on the broader provision in §1042.115 that 
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prohibits manufacturers from incorporating design strategies that introduce an unreasonable 

safety risk during engine operation. 

 §1042.120: Reduce extended-warranty requirements to warranties that are actually provided 

to the consumer, rather than to any published warranties that are offered. The principle is 

that the emission-related warranty should not be less effective for emission-related items than 

for items that are not emission-related.

 §1042.125: Allow for special maintenance procedures that address low-use engines. For 

example, owners of recreational marine vessels may need to perform engine maintenance 

after a smaller number of hours than would otherwise apply based on the limited engine 

operation over time.

 §1042.125: Establish a minimum maintenance interval of 1500 hours for DEF filters. This 

reflects the technical capabilities for filter durability and the expected maintenance in the 

field. 

 §1042.135: Clarify that ULSD labeling is required only for engines that use sulfur-sensitive 

technology. If an engine can meet applicable emission standards without depending on the 

use of ULSD, the manufacturer should not be required to state on the engine that ULSD is 

required.

 §1042.135: Allow for including optional label content only if the manufacturer does not opt 

to omit other information based on limited availability of space on the label.

 §1042.201: Clarify that manufacturers may amend their application for certification after the 

end of the model year in certain circumstances, but they may not produce engines for a given 

model year after December 31 of the named year.

 §1042.201: Establish that manufacturers may deliver to EPA for testing an engine that is 

identical to the test engine used for certification. This may be necessary if the test engine has 

accumulated too many hours, or if it is unavailable for any reason.

 §§1042.205 and 1042.840: Replace the requirement to submit data from invalid tests with a 

requirement to simply notify EPA in the application for certification if test was invalidated. 

 §1042.225: Clarify that manufacturers may amend the application for certification after the 

end of the model year only in certain circumstances, and not to add a new or modified engine 

configuration.

 §1042.235: Add an explicit allowance for carryover engine families to include the same kind 

of within-family running changes that are currently allowed over the course of a model year. 

The original text may have been understood to require that such running changes be made 

separate from certifying the engine family for the new model year.

 §§1042.235, 1042.240, and 1042.601: Describe how to demonstrate compliance with dualfuel and flexible-fuel engines. This generally involves testing with each separate fuel, or 

with a worst-case fuel blend. 

 §1042.240: Add instructions for calculating deterioration factors for sawtooth deterioration 

patterns, such as might be expected for periodic maintenance, such as cleaning or replacing 

diesel particulate filters.

 §1042.250: Remove references to routine and standard tests, and remove the shorter 

recordkeeping requirement for routine data (or data from routine tests). All test records must 

be kept for eight years. With electronic recording of test data, there should be no advantage 

to keeping the shorter recordkeeping requirement for a subset of test data. EPA also notes 
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that the eight-year period restarts with certification for a new model year if the manufacturer 

uses carryover data.

 §1042.255: Clarify that rendering information false or incomplete after submitting it is the 

same as submitting false or incomplete information. For example, if there is a change to any 

corporate information or engine parameters described in the manufacturer’s application for 

certification, the manufacturer must amend the application to include the new information.

 §1042.255: Clarify that voiding certificates for a recordkeeping or reporting violation would 

be limited to certificates that relate to the particular recordkeeping or reporting failure.

 §1042.302: Clarify that manufacturers may fulfill the requirement to test each Category 3 

production engine by performing the test before or after the engine is installed in the vessel. 

The largest Category 3 engines are assembled in the vessel, but some smaller Category 3 

engines are assembled at a manufacturing facility where they can be more easily tested. 

Manufacturers must perform such testing on fully assembled production engines rather than 

relying on test results from test bed engines. 

 §1042.501: Remove test procedure specifications that are already covered in 40 CFR part 

1065.

 §1042.505: Correct the reference to the ISO C1 duty cycle in 40 CFR part 1039.

 §1042.515: Remove an incorrect cite.

 §§1042.605 and 1042.610: Revise the reporting requirement to require detailed information 

about the previous year, rather than requiring a detailed projection for the year ahead. The 

information required in advance would be limited to a notification of plans to use the 

provisions of these sections.

 §1042.630: Clarify that dockside examinations are not inspections. Vessels subject to Coast 

Guard inspection are identified in 46 U.S.C. 3301.

 §1042.640: Migrate engine branding to §1068.45.

 §1042.650: Clarify that vessel operators may modify certified engines if they will be 

operated for an extended period outside the United States where ULSD will be unavailable. 

This does not preclude the possibility of vessel operators restoring engines to a certified 

configuration in anticipation of bring the vessel back to the United States.

 §1042.660: Identify the contact information for submitting reports related to operation 

without SCR reductant.

 §1042.670: Specify that gas turbine engines are presumed to have an equivalent power 

density below 35 kW per liter of engine displacement; this is needed to identify which Tier 3 

standards apply.

 §1042.701: Clarify that emission credits generated under 40 CFR part 94 may be used for 

demonstrating compliance with the Tier 3 and Tier 4 standards in 40 CFR part 1042.

 §§1042.701 and 1042.730: Describe the process for retiring emission credits. This may be 

referred to as donating credits to the environment.

 §1042.705: Change terminology for counting engines from “point of first retail sale” to 

“U.S.-direction production volume.” This conforms to the usual approach for calculating 

emission credits for nonroad engines.

 §1042.710: Clarify that it is not permissible to show a proper balance of credits for a given 

model by using emission credits from a future model year.

 §1042.730: Clarify terminology for ABT reports.
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 §1042.810: Clarify that it is only the remanufacturing standards of subpart I, not the 

certification standards that are the subject of the applicability determination in §1042.810.

 §1042.830: Add a provision to specifically allow voluntary labeling for engines that are not 

subject to remanufacturing standards, and to clarify that the label is required for engines that 

are subject to remanufacturing standards.

 §1042.901: Update the contact information for the Designated Compliance Officer.

 §1042.901: Revise the definition of “model year” to correct cites and clarify that the calendar 

year relates to the time that engines are produced under a certificate of conformity.

 §§1042.901 and 1042.910: Update the reference documents for Annex VI and NOX

Technical Code to include recent changes from the International Maritime Organization.

 §1042.915: Migrate provisions related to confidential information to 40 CFR part 1068.

I. Amendments Related to Locomotives in 40 CFR Part 1033

EPA’s emission standards and certification requirements for locomotives and locomotive 

engines under the Clean Air Act are identified in 40 CFR part 1033. 

EPA is proposing to revise the engine mapping provisions in 40 CFR part 1033 for 

locomotive testing to denote that manufacturers do not have to meet the cycle limit values in 40 

CFR 1065.514 when testing complete locomotives. Also, for engine testing with a 

dynamometer, while the validation criteria of CFR 1065.514 apply, EPA proposes to allow

manufacturers the option to check validation using manufacturer-declared values for maximum 

torque, power, and speed. This option would allow them to omit engine mapping under 40 CFR 

1065.510, which is already not required. These provisions would reduce test burden and cost for 

the manufacturer, while preserving the integrity of the certification requirements.

EPA is also proposing text that describes the alternate ramped-model cycle provisions in 

40 CFR part 1033 as some of the notch setting and durations are inconsistent with the description 

of the duty cycle in Table 1 of 40 CFR 1033.520. EPA has determined that the table is correct as 

published and the error lies in the text describing how to carry out the ramped-modal test.

We are also proposing to clarify that locomotives operating on a combination of diesel 

fuel and gaseous fuel are subject to NMHC standards, which is the same as if the locomotives 

operated only on gaseous fuel. With respect to in-use fuels, we are proposing a clarification in 

40 CFR 1033.815 regarding allowable fuels for certain Tier 4 and later locomotives. 

Specifically, we would note that locomotives certified on ultra-low sulfur diesel fuel, but that do 

not include sulfur sensitive emission controls, could use low sulfur diesel fuel instead of ultralow sulfur diesel fuel, consistent with good engineering judgment. For example, an obvious case 

where this would be appropriate (but not the only possible case), would be if a railroad had 

emission data showing the locomotive still met the applicable standards/FELs while operating on 

the higher sulfur fuel.

EPA is requesting comment on four additional locomotive provisions. The first is the 

allowance in 40 CFR 1033.101(g)(3) for shorter useful lives for non-locomotive-specific engines 

– that is, engines not specifically designed for use in locomotives. For normal locomotive 

engines, the minimum useful life is specified in terms of MW-hrs as the product of the rated 
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horsepower multiplied by 7.50. However, the regulations allow manufacturers/remanufacturers 

of locomotives with non-locomotive-specific engines to ask for a shorter useful life if the 

locomotives will rarely operate longer than the shorter useful life. Second, we request comment 

regarding the need for additional guidance on applying this provision. For example, would it be 

helpful if we specified that the default alternative minimum useful life under this provision 

would be 6.00 (instead of 7.50) times the rated horsepower? Third, we request comment on 

whether EPA should consider notch-specific engine/alternator efficiencies to be confidential 

business information, and whether we need to update the URL listed in 40 CFR 1033.150(a)(4). 

Fourth, we request comment on extending the provisions of 40 CFR 1033.101(i) to Tier 4 

locomotives. This generally involves a less stringent CO standard in tandem with overcomplying with the PM standard. Specifically, this option, which currently applies for Tier 2 

and earlier locomotives, requires PM emissions be at least 50 percent below the normally

applicable PM standard. The existing provisions were developed to provide a compliance path 

for natural gas locomotives that reflected both the technological capabilities of natural gas 

locomotives and the relative environmental significance of CO and PM emissions. This 

provision was not applied to Tier 4 locomotives, because the applicable Tier 4 PM standard is 

already very low (0.03 g/hp-hr). If we were to apply a similar provision corresponding to Tier 4 

standards, we would need to select PM and CO levels that are properly paired to manage this 

tradeoff. We request comment on whether it is appropriate to pursue such alternate standards, 

and on the specific numerical standards for PM and CO that would represent an equivalent level 

of stringency relative to the published standards.

EPA is proposing to make numerous additional changes across 40 CFR part 1033 to 

correct errors, to add clarification, and to make adjustments based on lessons learned from 

implementing these regulatory provisions. This includes the following proposed changes:

 §§1033.30, 1033.730, and 1033.925: Consolidate information-collection provisions into a 

single section.

 §1033.101: Allow manufacturers to certify Tier 4 and later locomotives using Low Sulfur 

Diesel fuel instead of Ultra-Low Sulfur Diesel fuel. Manufacturers may wish to do this to 

show that their locomotives do not include sulfur sensitive technology.§1033.120: Reduce 

extended-warranty requirements to warranties that are actually provided to customers, rather 

than to any published warranties that are offered. The principle is that the emission-related 

warranty should not be less effective for emission-related items than for items that are not 

emission-related.

 §1033.201: Clarify that manufacturers may amend their application for certification after the 

end of the model year in certain circumstances, but they may not produce locomotives for a 

given model year after December 31 of the named year.

 §1033.201: Establish that manufacturers may deliver to EPA for testing a locomotive/engine 

that is identical to the test locomotive/engine used for certification. This may be necessary if 

the test locomotive/engine has accumulated too many hours, or if it is unavailable for any

reason.

 §1033.225: Clarify that manufacturers may amend the application for certification after the 

end of the model year only in certain circumstances, and not to add a new or modified 

locomotive configuration.
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 §1033.235: Add an explicit allowance for carryover engine families to include the same kind 

of within-family running changes that are currently allowed over the course of a model year. 

The original text may have been understood to require that such running changes be made 

separate from certifying the engine family for the new model year.

 §§1033.235, 1033.245, and 1033.601: Describe how to demonstrate compliance with dualfuel and flexible-fuel locomotives. This generally involves testing with each separate fuel, or 

with a worst-case fuel blend. 

 §1033.245: Add instructions for calculating deterioration factors for sawtooth deterioration 

patterns, such as might be expected for periodic maintenance, such as cleaning or replacing 

diesel particulate filters.

 §1033.250: Remove references to routine and standard tests, and remove the shorter 

recordkeeping requirement for routine data (or data from routine tests). All test records must 

be kept for eight years. With electronic recording of test data, there should be no advantage 

to keeping the shorter recordkeeping requirement for a subset of test data. EPA also notes 

that the eight-year period restarts with certification for a new model year if the manufacturer 

uses carryover data.

 §1033.255: Clarify that rendering information false or incomplete after submitting it is the 

same as submitting false or incomplete information. For example, if there is a change to any 

corporate information or engine parameters described in the manufacturer’s application for 

certification, the manufacturer must amend the application to include the new information. 

 §1033.255: Clarify that voiding certificates for a recordkeeping or reporting violation would 

be limited to certificates that relate to the particular recordkeeping or reporting failure.

 §1033.501: Clarify how testing requirements apply differently for locomotive engines and for 

complete locomotives.

 §1033.501: Add paragraph (a)(4) to remove proportionality verification for discrete-mode 

tests if a single batch fuel measurement is used to determine raw exhaust flow rate. This 

verification involves statistical assessment that is not valid for the single data point. 

Requiring manufacturers instead to simply ensure constant sample flow should adequately 

address the concern,

 §§1033.515 and 1033.520: Update terminology by referring to “test intervals” instead of 

“phases”. This allows us to be consistent with terminology used in 40 CFR part 1065.

 §1033.520: Correct the example given to describe the testing transition after the second test 

interval. 

 §§1033.701 and 1033.730: Describe the process for retiring emission credits. This may be 

referred to as donating credits to the environment.

 §1033.710: Clarify that it is not permissible to show a proper balance of credits for a given 

model by using emission credits from a future model year.

 §1033.730: Clarify terminology for ABT reports.

 §1033.815: Add consideration of periodic locomotive inspections in 184-day intervals.

 §1033.901: Update the contact information for the Designated Compliance Officer.

 §1033.915: Migrate provisions related to confidential information to 40 CFR part 1068.
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J. Miscellaneous EPA Amendments

EPA is proposing to revise 40 CFR 85.1511 to allow companies other than certificate 

holders to import motor vehicles that are exempted because they are more than 20 years old. 

This aligns with the prevailing practice and Customs regulations at 19 CFR 12.73.

EPA is proposing to clarify that the cold NMHC standards specified in 40 CFR 86.1811-

17 do not apply at high altitude. We intended in recent amendments to state that the cold CO 

standards apply at both low and high altitude, but inadvertently placed that statement where it 

also covered cold NMHC standards, which contradicts existing regulatory provisions that clearly 

describe the cold NMHC standards as applying only for low-altitude testing. The proposed 

change would simply move the new clarifying language to apply only to cold CO standards. We 

are also proposing to restore the cold NMHC standards in paragraph (g)(2), which were 

inadvertently removed as part of the earlier amendments.

EPA is proposing to revise the specifications for Class 2b and Class 3 vehicles certifying 

early to the Tier 3 exhaust emission standards under 40 CFR 86.1816-18 to clarify that carryover 

values for PM and formaldehyde apply. The preamble to the earlier final rule described these 

standards properly, but the regulations inadvertently pointed to the Tier 3 values for PM and 

formaldehyde for these vehicles. 

EPA is proposing to make a minor correction to the In-Use Compliance Program under 

40 CFR 86.1846-01. A recent amendment describing how to use SFTP test results in the 

compliance determination inadvertently removed a reference to low-mileage SFTP testing. We 

are proposing to restore the removed text.

EPA is proposing to revise the instruction for creating road-load coefficients for cold 

temperature testing in 40 CFR 1066.710 to simply refer back to 40 CFR 1066.305 where this is 

described more generally. The text originally adopted in 40 CFR 1066.710 incorrectly describes 

the calculation for determining those coefficients.

EPA is also proposing two minor amendments related to highway motorcycles. First, we 

are proposing to correct an error related to the small-volume provisions for highway

motorcycles. The regulation includes an inadvertent reference to a small-volume threshold based 

on an annual volume of 3,000 motorcycles produced in the United States. As written, this would 

not consider any foreign motorcycle production for importation into the United States. This 

error is corrected by simply revising the text to refer to an annual production volume of 

motorcycles produced “for” the United States. This would properly reflect small-volume 

production as it relates to compliance with EPA standards. Second, we are proposing to clarify

the language describing how to manage the precision of emission results, both for measured 

values and for calculating values when applying a deterioration factor. This involves a new 

reference to the rounding procedures in 40 CFR part 1065 to replace the references to outdated 

ASTM procedures. EPA is proposing in 40 CFR 1037.601(a)(3) to clarify that the Clean Air Act 

does not allow any person to disable, remove, or render inoperative (i.e., tamper with) emission 

controls on a certified motor vehicle for purposes of competition. An existing provision in 40 

CFR 1068.235 provides an exemption for nonroad engines converted for competition use. This 

provision reflects the explicit exclusion of engines used solely for competition from the CAA 
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definition of “nonroad engine”. The proposed amendment clarifies that this part 1068 exemption 

does not apply for motor vehicles.

K. Amending 49 CFR Parts 512 and 537 to Allow Electronic Submissions and 

Defining Data Formats for Light-Duty Vehicle Corporate Average Fuel 

Economy (CAFE) Reports

To improve efficiency and reduce the burden to manufacturers and the agencies, NHTSA 

is proposing to modify 49 CFR part 537 eliminating the option for manufacturers to submit premodel, mid-model and supplemental reports on CD-ROMS and require only one electronic 

submission (for each report) electronically via a method proscribed by NHTSA. NHTSA is 

introducing a new electronic format to standardize the method for collecting manufacturer’s 

information. NHTSA also proposes to modify 49 CFR part 512 to include and protect submitted 

CAFE data elements that need to be treated as confidential business information.

49 CFR part 537 currently requires manufacturers to provide reports to NHTSA 

containing projected estimates of how manufacturers plan to comply with NHTSA standards. In 

the CAFE final rule for vehicles manufactured for model years 2017-2025, NHTSA modified its 

reporting requirements at 49 CFR 537.5(c)(4) to eliminate the option for manufacturers to mail 

hardcopy submissions of CAFE reports to NHTSA and required all reports to be submitted

electronically by CD-ROM (CBI and non-CBI versions) or by email (non-CBI version).895 

Currently, any data provided in the manufacturer’s report is required in MS-Excel spreadsheet 

format. Supporting documentation such as cover letters or requests for confidentiality is required 

to be provided in a pdf format. 

NHTSA is proposing to change the required format for CAFE data required under 49 

CFR 537.7(b) and (c) in order to standardize submissions and better align with data provided to 

EPA. For model year 2013 through 2015 most manufacturer reports received by NHTSA lacked 

the required format adopted in the 2017-2025 final rule. NHTSA is therefore adopting a 

standardized template for manufacturers to report model type level data. The template organizes 

the required data in a consistent manner, adopts formats for values consistent with those 

provided to EPA for similar values and calculates manufacturer’s target standard. Calculating 

target standards is preferred because it reduces errors in manufacturer’s determinations. 

However, NHTSA’s long-term goal is to standardize the required data for incorporation into an 

electronic database system and this first step facilities a structure for coding the electronic data

which will ultimately reduce manufacturer’s and the government’s burden for reporting. 

NHTSA rationalizes that establishing a required format is necessary because 

manufacturers may not understand how to provide the required CAFE data. In the 2017 to 2025 

final rule, NHTSA modified its base tire definition to better align with the approach 

 

895 77 FR 62624 (Oct. 15, 2012).
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manufacturers use to determine model type target standards. CAFE standards are attribute 

based, and thus each manufacturer has its own “standard,” or compliance obligation, defined by 

the vehicles it produces for sale in each fleet in a given model year. A manufacturer calculates 

its fleet standard from the attribute based target curve standards derived from the unique 

footprint values, which are the products of the average front and rear vehicle track width and 

wheelbase dimensions, of the vehicles in each model type. Vehicle track width dimensions are 

determined with a vehicle equipped with “base tires,” which NHTSA currently defines in 49 

CFR part 523 as (for passenger automobiles, light trucks, and medium duty passenger vehicles) 

the tire size specified as standard equipment by the manufacturer on each unique combination of 

a vehicle’s footprint and model type. Standard equipment is defined in 40 CFR 86.1803–01. 

NHTSA made these changes to provide a clear definition for footprint calculations and, thus, 

fleet compliance projections, calculations, finalizations and enforcement efforts. Beginning in 

model year 2013, as modified in 49 CFR 537.7(b), manufacturers were to provide attribute 

characteristics and standards in consideration of the change in the base tire definition for each 

unique model type and footprint combination of the manufacturer’s automobiles. Manufacturers 

were required to provide the data listed by model types in order of increasing average inertia 

weight from top to bottom down the left side of the table and list the information categories in 

the order specified in 49 CFR 537.7(b)(3)(i) and (ii) from left to right across the top of the table. 

Manufacturers could also provide the data using any format required by EPA, which contains all 

of the required information in a readily identifiable format.

In the 2017-2025 final rule, additional changes to NHTSA’s reporting requirements also 

included a modification to 49 CFR 537.7(b) to restructure and clarify how manufacturers report 

information used to make the determination that an automobile can be classified as a light truck 

for CAFE purposes. The agency felt that this proposed change was necessary because the 

previous requirements in 49 CFR part 537 specified that manufacturers must provide information 

on some, but not all, of the functions and features used to classify an automobile as a light truck, 

and it is important for compliance reasons to understand and be able to readily verify the 

methods used to ensure manufacturers are classifying vehicles correctly. Furthermore, the 

previous regulation required that the information be distributed in different locations throughout 

a manufacturer’s report, making it difficult for the agency to clearly determine exactly what 

functions or features a manufacturer is using to classify a vehicle as a light truck. Therefore, 

NHTSA streamlined the location of all its provisions for defining vehicle classifications into one 

consolidate section. With these changes, manufacturers can provide the agency with all the 

necessary data in a simpler format that allows the agency, and perhaps also the manufacturer, to 

understand quickly and easily how light truck vehicle classification determination decisions are 

made.

In reviewing manufacturers current reporting, most manufacturers are still failing to 

provide the required information for classifying light trucks. For the model year 2015 pre-model 

year reports, only a few manufacturers provided the required information and many provided the 

information incorrectly. Therefore, NHTSA is also proposing to incorporate an additional 

template for collecting vehicle configuration level data which includes vehicle classification 

information. Similarly, the template will standardize the format of the data with values required 

by EPA and structures the data for future incorporation into a database system. Finally, the 

template also simplifies reporting by not having manufacturers report all vehicle classification
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characteristics but only those used by the manufacturer in qualifying a vehicle as a light truck. 

NHTSA is adopting this provision to better align with EPA current database structure which uses 

a similar approach in accepting light truck level data.
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XV. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and Executive 

Order 13563: Improving Regulation and Regulatory Review

This action is an economically significant regulatory action that was submitted to the 

Office of Management and Budget (OMB) for review. Any changes made in response to OMB 

recommendations have been documented in the docket. The agencies prepared an analysis of the 

potential costs and benefits associated with this action. This analysis, the draft “Regulatory

Impact Analysis - Heavy-Duty GHG and Fuel Efficiency Standards NPRM,” is available in the 

docket. The analyses contained in this document are also summarized in Sections VII, VIII, and 

IX of this preamble.

B. National Environmental Policy Act

NHTSA has initiated the Environmental Impact Statement (EIS) process under the 

National Environmental Policy Act (NEPA), 42 U.S.C. 4321–4347, and implementing 

regulations issued by the Council on Environmental Quality (CEQ), 40 CFR part 1500, and 

NHTSA, 49 CFR part 520. On July 9, 2014, NHTSA published a notice of intent to prepare an 

EIS for this rulemaking and requested scoping comments (79 FR 38842). The notice invited 

Federal, State, and local agencies, Indian tribes, stakeholders, and the public to participate in the 

scoping process and to help identify the environmental issues and reasonable alternatives to be 

examined in the EIS.

Concurrently with this NPRM, NHTSA is releasing a Draft Environmental Impact 

Statement (DEIS). NHTSA prepared the DEIS to analyze and disclose the potential 

environmental impacts of the proposed HD fuel consumption standards and reasonable 

alternatives. Environmental impacts analyzed in the DEIS include those related to fuel and 

energy use, air quality, and climate change. The DEIS also describes potential environmental 

impacts to a variety of resource areas, including water resources, biological resources, land use 

and development, safety, hazardous materials and regulated wastes, noise, socioeconomics, and 

environmental justice. These resource areas are assessed qualitatively in the DEIS.

The DEIS analyzes five alternative approaches to regulating HD vehicle fuel 

consumption, including a “preferred alternative” and a “no action alternative.” The DEIS 

evaluates a reasonable range of alternatives under NEPA, and analyzes the direct, indirect, and

cumulative impacts of those alternatives in proportion to their significance.

Because of the link between the transportation sector and GHG emissions, NHTSA

recognizes the need to consider the possible impacts on climate and global climate change in the 

analysis of the effects of these fuel consumption standards. NHTSA also recognizes the 

difficulties and uncertainties involved in such an impact analysis. Accordingly, consistent with 

CEQ regulations on addressing incomplete or unavailable information in environmental impact 

analyses, NHTSA has reviewed existing credible scientific evidence that is relevant to this 

analysis and summarized it in the DEIS. NHTSA has also employed and summarized the results 

of research models generally accepted in the scientific community.
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Although the alternatives have the potential to decrease GHG emissions substantially, 

they do not prevent climate change, but only result in reductions in the anticipated increases in 

CO2 concentrations, temperature, precipitation, and sea level. They would also, to a small 

degree, delay the point at which certain temperature increases and other physical effects 

stemming from increased GHG emissions would occur. As discussed in the EIS, NHTSA 

presumes that these reductions in climate effects will be reflected in reduced impacts on affected 

resources.

The DEIS has informed NHTSA decision makers in their preparation of this NPRM and 

in the ongoing rulemaking process. NHTSA invites comments on the DEIS from Federal, State, 

and local agencies, Indian tribes, stakeholders, and the public. Instructions for submission of 

such comments are included in the DEIS.

For additional information on NHTSA’s NEPA analysis, please see the DEIS.

C. Paperwork Reduction Act

The information collection activities in these proposed rules have been submitted for 

approval to the Office of Management and Budget (OMB) under the PRA. The Information 

Collection Request (ICR) document that EPA prepared has been assigned EPA ICR number 

2394.04. You can find a copy of the ICR in the docket for these proposed rules, and it is briefly

summarized here. 

The agencies propose to collect information to ensure compliance with the provisions in 

this proposal. This includes a variety of testing, reporting and recordkeeping requirements for

vehicle and engine manufacturers. Section 208(a) of the CAA requires that 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.

Respondents/affected entities: Respondents are manufacturers of engines and vehicles 

within the North American Industry Classification System (NAICS) and use the coding structure 

as defined by NAICS. 336111, 336112, 333618, 336120, 541514, 811112, 811198, 336111, 

336112, 422720, 454312, 541514, 541690, 811198, 333618, 336510, for Motor Vehicle 

Manufacturers, Engine and Truck Manufacturers, Truck Trailer Manufacturers, Commercial 

Importers of Vehicles and Vehicle Components, and Alternative Fuel Vehicle Converters and 

Manufacturers.

Respondent’s obligation to respond: The information that is subject to this collection is 

collected whenever a manufacturer applies for a certificate of conformity. Under section 206 of 

the CAA (42 U.S.C. 7521), a manufacturer must have a certificate of conformity before a vehicle 

or engine can be introduced into commerce.

Estimated number of respondents: It is estimated that this collection affects 

approximately 155 engine and vehicle manufacturers.

Frequency of response: Annually
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Total estimated burden: The burden to the manufacturers affected by these rules has a 

range based on the number of engines and vehicles a manufacturer produces. The estimated 

average annual respondent burden associated with the first three implementation years of the 

Phase 2 program is 62,400 hours (See Table XV-1). This estimated burden for engine and 

vehicle manufacturers is an average estimate for both new and existing reporting requirements

for calendar years 2017, 2018 and 2019, in which trailer manufacturers will prepare for and 

begin certifying for Phase 2 while Phase 1 will continue for the other affected manufacturers. 

Burden is defined at 5 CFR 1320.3(b). Burden means the total time, effort, or financial resources 

expended by persons to generate, maintain, retain, or disclose or provide information to or for a 

Federal agency. This includes the time needed to review instructions; develop, acquire, install, 

and utilize technology and systems for the purposes of collecting, validating, and verifying 

information, processing and maintaining information, and disclosing and providing information; 

adjust the existing ways to comply with any previously applicable instructions and requirements;

train personnel to be able to respond to a collection of information; search data sources; complete 

and review the collection of information; and transmit or otherwise disclose the information. 

Table XV-1 Burden for Reporting and Recordkeeping Requirements

Number of Affected Vehicle Manufacturers 155

Annual Labor Hours for Each Manufacturer to Prepare and 

Submit Required Information

Varies 

Total Annual Information Collection Burden 62,400 Hours 

Total estimated cost: The estimated average annual cost associated with the first three 

implementation years of the Phase 2 program is approximately $8 million. This includes 

approximately $3.3 million in capital and operation & maintenance costs. This estimated cost for 

engine and vehicle manufacturers is an average estimate for both new and existing testing, 

recordkeeping, and reporting requirements for calendar years 2017, 2018 and 2019, in which 

trailer manufacturers will prepare for and begin certifying for Phase 2 while Phase 1 will 

continue for the other affected manufacturers.

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 in 40 CFR are listed in 40 CFR part 9. 

Submit your comments on the agencies’ need for this information, the accuracy of the 

provided burden estimates and any suggested methods for minimizing respondent burden to EPA

and NHTSA using the docket identified at the beginning of these proposed rules. You may also 

send your ICR-related comments to OMB’s Office of Information and Regulatory Affairs via 

email to oira_submissions@omb.eop.gov, Attention: Desk Officer for EPA. Since OMB is 

required to make a decision concerning the ICR between 30 and 60 days after receipt, OMB 

must receive comments no later than [insert date 30 days after publication in the Federal 

Register]. The agencies will respond to any ICR-related comments in the final rules.

NHTSA also separately submitted a request to OMB for approval of a change to an

information collection activity that is proposed in this rulemaking. The information collection 
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request was previously assigned ICR No. 2127-0019 for 49 CFR Part 537, “Automotive Fuel 

Economy Reports.” 

The existing collection involves vehicle manufacturers submitting reports to the Secretary

of Transportation with preliminary estimates demonstrating their ability to comply with 

corporate average fuel economy standards (CAFE) established by 49 USC 32902 for each model 

year. To improve efficiency and reduce manufacturers’ and the government’s burden, NHTSA 

is proposing to modify 49 CFR Part 537to require CAFE reports to be submitted electronically 

via an electronic database using a standardized data format. The total estimated amount of 

paperwork burden resulting from this action that the federal government is imposing on private 

businesses and citizens is summarized below.

Respondents: Automobile manufacturers.

Estimated Number of Respondents: 30.

Estimated Number of Responses: 54. Some manufacturers have multiple fleets (domestic 

passenger car, import passenger car, light truck) and 49 CFR part 537 requires a separate report 

for each fleet.

Estimated Total Annual Burden: Thirty automotive manufacturers must comply with 49 

CFR 537. For each current model year, each manufacturer is required to submit semi-annual

reports: A pre-model year report and a mid-model year report. The pre-model year report must 

be submitted during the month of December, and the mid-model year report must be submitted

during the month of July. The total number of responses submitted by automotive manufacturers 

is 54. We currently have a clearance based on reports being received from 22 manufacturers with 

an estimated total annual burden of 2,339 hours. Including 8 additional manufacturers, results in 

an additional reporting burden of 850 hours. Adding that burden to the existing burden of 2,339 

hours, results in a total of 3,189 hours.

Estimated Frequency: A pre-model report and a mid-model report are required to be 

submitted by manufacturers once per model year for each applicable fleet (domestic passenger 

car, imported passenger car and light trucks).

A copy of the 60 day notice for this ICR containing the proposed changes is included in 

the docket for this rule. NHTSA seeks public comments on all aspects of this information 

collection, including (a) whether the proposed collection of information is necessary for the 

Department’s performance, (b) the accuracy of the estimated burden, (c) ways for the 

Department to enhance the quality, utility and clarity of the information collection and (d) ways 

that the burden could be minimized without reducing the quality of the collected information. 

D. Regulatory Flexibility Act

Pursuant to section 603 of the RFA, the agencies prepared an initial regulatory flexibility

analysis (IRFA) that examines the impact of the proposed rules on small entities along with 
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regulatory alternatives that could minimize that impact. The complete IRFA is available for 

review in the docket and is summarized here. As required by section 609(b) of the RFA, EPA 

convened a Small Business Advocacy Review (SBAR) Panel to obtain advice and 

recommendations from small entity representatives that potentially would be subject to the rule's 

requirements. The SBAR Panel evaluated the assembled materials and small-entity comments 

on issues related to elements of an IRFA. A copy of the full SBAR Panel Report is available in 

the rulemaking docket.

(1) Overview

The Regulatory Flexibility Act (RFA) 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 today’s rules on small entities, small entity is 

defined as: (1) a small business as defined by the Small Business Administration’s (SBA) 

regulations at 13 CFR 121.201 (see table below); (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. 

Table XV-2 provides an overview of the primary SBA small business categories 

potentially affected by this regulation. 

Table XV-2 Primary Small Business Categories Potentially Affected by this Regulation

Industry Expected in 

Rulemaking

Industry 

NAICSa

Code

NAICS Description Defined as small entity by 

SBA if less than or equal to:

Alternative Fuel 

Engine Converters

333999 Misc. General Purpose Machinery 500 employees

811198 All Other Automotive Repair & 

Maintenance

$7.0 million (annual receipts)

Voc. Vehicle Chassis 

Manufacturers

336120 Heavy-Duty Truck Manufacturing 1,000 employees

HD Trailer Manufacturers 336212 Truck Trailer Manufacturing 500 employees

333924 Industrial Truck, Trailer & Stacker 

Machinery

750 employees

Note:

a North American Industrial Classification System

(2) Legal Basis for Agency Action

Heavy-duty vehicles are classified as those with gross vehicle weight ratings (GVWR) of 

greater than 8,500 lb. Section 202(a) of the Clean Air Act (CAA) allows EPA to regulate new 

vehicles and new engines by prescribing emission standards for pollutants which the 
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Administrator finds “may reasonably be anticipated to endanger public health or welfare.” In 

2009, EPA found that six greenhouse gases (GHGs) were anticipated to endanger public health 

or welfare, and new motor vehicles and new motor vehicle engines contribute to that pollution. 

This finding was upheld by the unanimous court in Coalition for Responsible Regulation v. EPA, 

684 F. 3d 102 (D.C. Cir. 2012). Acting under the authority of the CAA, EPA set the first phase 

of heavy-duty vehicle GHG standards (Phase 1) and specified certification requirements for 

emissions of four GHGs emitted by mobile sources: carbon dioxide (CO2), nitrous oxide (N2O), 

methane (CH4), and hydrofluorocarbons (HFC).

(3) Summary of Potentially Affected Small Entities

Table XV-2 above lists industries/sectors potentially affected by the proposed rules. EPA 

is not aware of any small businesses who manufacture complete heavy-duty pickup trucks and 

vans, heavy-duty engines, or Class 7 and 8 tractors. 

EPA used the criteria for small entities developed by the Small Business Administration 

under the North American Industry Classification System (NAICS) as a guide. Information 

about these entities comes from sources including EPA’s certification data, trade association 

databases, and previous rulemakings that have affected these industries. EPA then found 

employment information for these companies using the business information database Hoover’s 

Online (a subsidiary of Dan and Bradstreet). These entities fall under the categories listed in the 

table. 

(4) Potential Reporting, Recordkeeping and Compliance Burdens

For any emission control program, EPA must have assurances that the regulated products 

will meet the standards. The program that EPA is considering for manufacturers subject to this 

proposal will include testing, reporting, and recordkeeping requirements. Testing requirements 

for these manufacturers could include use of EPA’s Greenhouse gas Emissions Model (GEM) 

vehicle simulation tool to obtain the overall CO2 emissions rate for certification of vocational 

chassis and trailers, aerodynamic testing to obtain aerodynamic inputs to GEM for some trailer 

manufacturers and engine dynamometer testing for alternative fuel engine converters to ensure 

their conversions meet the proposed CO2, CH4 and N2O engine standards. Reporting 

requirements would likely include emissions test data or model inputs and results, technical data 

related to the vehicles, and end-of-year sales information. Manufacturers would have to keep 

records of this information.

(5) Related Federal Rules

The primary federal rule that is related to the proposed Phase 2 rules under consideration 

is the 2011 Greenhouse Gas Emissions and Fuel Efficiency Standards for Medium- and HeavyDuty Engines and Vehicles (76 FR 57106). This Phase 1 rulemaking would continue to be in 

effect in the absence of these proposed rules. Several Federal rules relate to heavy-duty vehicles 

and to the proposed Phase 2 rules under consideration. The Department of Transportation, 

through NHTSA, has several safety requirements for these vehicles. California adopted its own 

greenhouse gas initiative, which places aerodynamic requirements on trailers used in long-haul 
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applications. None of these existing regulations were found to conflict with the proposed 

rulemaking.

(6) Summary of SBREFA Panel Process and Panel Outreach

(a) Significant Panel Findings

The Small Business Advocacy Review Panel (SBAR Panel, or the Panel) considered 

regulatory options and flexibilities to help mitigate potential adverse effects on small businesses 

as a result of these rules. During the SBREFA Panel process, the Panel sought out and received 

comments on the regulatory options and flexibilities that were presented to SERs and Panel 

members. The recommendations of the Panel are described below and are also located in 

Section XX of the SBREFA Final Panel Report, which is available in the public docket.

(b) Panel Process

As required by Section 609(b) of the RFA, as amended by SBREFA, we also conducted 

outreach to small entities and convened an SBAR Panel to obtain advice and recommendations 

of representatives of the small entities that potentially would be subject to the rule’s 

requirements. On October 22, 2014, EPA’s Small Business Advocacy Chairperson convened a 

Panel under Section 609(b) of the RFA. In addition to the Chair, the Panel consisted of the 

Division Director of the Assessment and Standards Division of EPA’s Office of Transportation 

and Air Quality, the Chief Counsel for Advocacy of the Small Business Administration, and the 

Administrator of the Office of Information and Regulatory Affairs within the Office of 

Management and Budget. 

As part of the SBAR Panel process, we conducted outreach with representatives of small 

businesses that would potentially be affected by the proposed rulemaking. We met with these 

Small Entity Representatives (SERs) to discuss the potential rulemaking approaches and 

potential options to decrease the impact of the rulemaking on their industries. We distributed 

outreach materials to the SERs; these materials included background on the rulemaking, possible 

regulatory approaches, and possible rulemaking alternatives. The Panel met with SERs from the 

industries that would be directly affected by the Phase 2 rules on November 5, 2014 (trailer 

manufacturers) and November 6, 2014 (engine converters and vocational vehicle chassis 

manufacturers) to discuss the outreach materials and receive feedback on the approaches and 

alternatives detailed in the outreach packet. The Panel also met with SERs on July 19, 2014 for 

an initial, introductory outreach meeting, and held a supplementary outreach meeting with the 

trailer manufacturer SERs on October 28, 2014. The Panel received written comments from the 

SERs following each meeting in response to discussions had at the meeting and the questions 

posed to the SERs by the agency. The SERs were specifically asked to provide comment on 

regulatory alternatives that could help to minimize the rule’s impact on small businesses. 

The Panel’s findings and discussions were based on the information that was available 

during the term of the Panel and issues that were raised by the SERs during the outreach 

meetings and in their comments. It was agreed that EPA should consider the issues raised by the 

SERs and discussions had by the Panel itself, and that EPA should consider comments on 
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flexibility alternatives that would help to mitigate negative impacts on small businesses to the 

extent legally allowable by the Clean Air Act.

Alternatives discussed throughout the Panel process included those offered in previous or 

current EPA rulemakings, as well as alternatives suggested by SERs and Panel members. A 

summary of these recommendations is detailed below, and a full discussion of the regulatory

alternatives and hardship provisions discussed and recommended by the Panel can be found in 

the SBREFA Final Panel Report. A complete discussion of the provisions for which we are 

requesting comment and/or proposing in this action can be found in Sections IV.E and V.D of 

this preamble. Also, the Panel Report includes all comments received from SERs (Appendix B 

of the Report) and summaries of the two outreach meetings that were held with the SERs. In 

accordance with the RFA/SBREFA requirements, the Panel evaluated the aforementioned 

materials and SER comments on issues related to the IRFA. The Panel’s recommendations from 

the Final Panel Report are discussed below.

(c) Panel Recommendations

(i) Small Business Trailer Manufacturers

Comments from trailer manufacturer SERs indicated that these companies are familiar 

with most of the technologies described in the materials, but have no experience with EPA 

certification and do not anticipate they could manage the accounting and reporting requirements 

without additional staff and extensive training. Performance testing, which is a common 

requirement for many of EPA’s regulatory programs, is largely unfamiliar to these small 

business manufacturers and the SERs believed the cost of testing would be a significant burden 

on their companies. In light of this feedback, the Panel recommended a combination of 

streamlined compliance and targeted exemptions for these small businesses based on the specific 

trailer types that they manufacture. The Panel believed these strategies would achieve many of 

the benefits for the environment by driving adoption of CO2-reducing technologies, while 

significantly reducing the burden that these new regulations would introduce on small 

businesses.

(ii) Box Trailer Manufacturers

Box trailer manufacturers have the benefit of relying on the aerodynamic technology

development initiated through EPA’s voluntary SmartWay program. The Panel was aware that 

EPA was planning to propose a simplified compliance program for all manufacturers, in which 

aerodynamic device manufacturers have the opportunity to test and certify their devices with 

EPA as technologies that can be used by trailer manufacturers in their trailer certification. This 

pre-approved technology strategy was intended to provide all trailer manufactures a means of 

complying with the standards without the burden of testing. In the event that this strategy is 

limited to the early years of the trailer program for all manufactures, the Panel recommended that 

small manufacturers continue to be given the option to use pre-approved devices in lieu of 

testing. 

In the event that small trailer manufacturers adopt pre-approved aerodynamic 

technologies and the appropriate tire technologies for compliance, the Panel recommended an 
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alternative compliance pathway in which small business trailer manufacturers could simply

report to EPA that all of their trailers include approved technologies in lieu of collecting all of 

the required inputs for the GEM vehicle simulation. 

(iii) Non-Box Trailer Manufacturers

The Panel recommended no aerodynamic requirements for non-box trailers. The non-box 

trailer SERs indicated that they had no experience installing aerodynamic devices and had only

seen them in prototype-level demonstrations. In terms of the aerodynamic devices in use today, 

most non-box trailer SERs identified unique operations in which their trailers are used that 

preclude the use of those technologies. 

Some non-box trailer manufacturers had experience with LRR tires and ATI systems. 

However, the non-box trailer manufacturer SERs indicated that LRR tires are not currently 

available for some of their trailer types. The SERs noted that tire manufacturers are currently 

focused on box trailer applications and there are only a few LRR tire models that meet the needs 

of their customers. The Panel recommended EPA ensure appropriate availability of these tires in 

order for it to be deemed a feasible means of achieving these standards and recommended a 

streamlined compliance process based on the availability of technologies. The Panel suggested 

the best compliance option from a small business perspective would be for EPA to pre-approve 

tires, similar to the approach being proposed for aerodynamic technologies, and to maintain a list 

that could be used to exempt small businesses when no suitable tires are available. However, the 

Panel recognized the difficulties of maintaining an up-to-date list of certified technologies. The 

Panel recommended that, if EPA did not adopt the list-based approach, the agency consider a 

simplified letter-based compliance option that allows manufacturers to petition EPA for an 

exemption if they are unable to identify tires that meet the LRR performance requirements on a 

trailer family basis.

(iv) Non-Highway Trailer Manufacturers 

The Panel recommended excluding all trailers that spend a significant amount of time in 

off-road applications. These trailers may not spend much time at highway speeds and 

aerodynamic devices may interfere with the vehicle’s intended purpose. Additionally, tires with 

lower rolling resistance may not provide the type of traction needed in off-road applications.

(v) Compliance Provisions for All Small Trailer Manufacturers

Due to the potential for reducing a small business’s competitiveness compared to the 

larger manufacturers, as well as the ABT record-keeping burden, the Panel recommended that 

EPA consider small business flexibilities to allow small entities to opt out of ABT without 

placing themselves at a competitive disadvantage to larger firms that adopt ABT, such as a low 

volume exemption or requiring only LRR where appropriate. EPA was asked to consider 

flexibilities for small businesses that would ease and incentivize their participation in ABT, such 

as streamlined the tracking requirements for small businesses. In addition, the Panel 

recommended that EPA request comment on the feasibility and consequences of ABT for the 

trailer program and additional flexibilities that will promote small business participation. 
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(vi) Lead Time Provisions for All Small Trailer Manufacturers

For all trailer types that will be included in the proposal, the Panel recommended a 1-year 

delay in implementation for small trailer manufacturers at the start of the proposed rulemaking to 

allow them additional lead time to make the proper staffing adjustments and process changes and 

possibly add new infrastructure to meet these requirements. In the event that EPA is unable to 

provide pre-approved technologies for manufacturers to choose for compliance, the Panel 

recommended that EPA provide small business trailer manufacturers an additional 1-year delay

for each subsequent increase in stringency. This additional lead time will allow these small 

businesses to research and market the technologies required by the new standards.

(vii) Small Business Alternative Fuel Engine Converters

To reduce the compliance burden of small business engine converters who convert 

engines in previously-certified complete vehicles, the Panel recommended allowing engine 

compliance to be sufficient for certification. This would mean the converted vehicle would not 

need to be recertified as a vehicle. This flexibility would eliminate the need for these small 

manufacturers to gather all of the additional component-level information in addition to the 

engine CO2 performance necessary to properly certify a vehicle with GEM (e.g., transmission 

data, aerodynamic performance, tire rolling resistance, etc.). In addition, the Panel 

recommended that small engine converters be able to submit an engineering analysis, in lieu of 

measurement, to show that their converted engines do not increase N2O emissions. Many of the 

small engine converters are converting SI-engines, and the catalysts in these engines are not 

expected to substantially impact N2O production. Small engine converters that convert CIengines could likely certify by ensuring that their controls require changes to the SCR dosing 

strategies.

The Panel did not recommend separate standards for small business natural gas engine 

manufacturers. The Panel believes this would discourage entrance for small manufactures into 

this emerging market by adding unnecessary costs to a technology that has the potential to 

reduce CO2 tailpipe emissions. In addition, the Panel noted that additional leakage requirements 

beyond a sealed crankcase for small business natural gas-fueled CI engines and requirements to 

follow industry standards for leakage could be waived for small businesses with minimal impact 

on overall GHG emissions. 

Finally, the Panel recommended that small engine converters receive a one-year delay in 

implementation for each increase in stringency throughout the proposed rules. This flexibility

will provide small converters additional lead time to obtain the necessary equipment and perform 

calibration testing if needed. 

(viii) Emergency Vehicle Chassis Manufacturers

Fire trucks, and many other emergency vehicles, are built for high level of performance 

and reliability in severe-duty applications. Some of the CO2-reducing technologies listed in the 

materials could compromise the fire truck’s ability to perform its duties and many of the other 

technologies simply provide no benefit in real-world emergency applications. The Panel 

recommended proposing less stringent standards for emergency vehicle chassis manufactured by
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small businesses. The Panel suggested that feasible standards could include adoption of LRR 

tires at the baseline Phase 2 level and installation of a Phase 2-compliant engine. In addition, the 

Panel recommended a simplified certification approach for small manufacturers who make 

chassis for emergency vehicles that reduces the number of inputs these manufacturers must 

obtain for GEM. 

(ix) Off-Road Vocational Vehicle Chassis Manufacturers

EPA is planning to propose to continue the exemptions in Phase 1 for off-road and lowspeed vocational vehicles (see generally 76 FR 57175). These provisions currently apply for 

vehicles that are defined as “motor vehicles” per 40 CFR 85.1703, but may conduct most of their 

operations off-road. Vehicles qualifying under these provisions must comply with the applicable 

engine standard, but need not comply with a vehicle-level GHG standard. The Panel concluded 

this exemption is sufficient to cover the small business chassis manufacturers who design chassis 

for off-road vocational vehicles.

(x) Custom Chassis Manufacturers

The Panel concluded that chassis designed for specialty operations often have limited 

ability to adopt CO2- and fuel consumption-reducing technologies due to their unique use 

patterns. In addition, the manufacturers of these chassis have very small annual sales volumes. 

The Panel recommended that EPA propose a low volume exemption for these custom chassis 

manufacturers. The Panel did not receive sufficient information to recommend a specific sales 

volume, but recommended that EPA request comment on how to design a small business 

exemption by means of a volume exemption, and an appropriate annual sales volume threshold.

(xi) Glider Manufacturers

The Panel was aware that EPA would like to reduce the use of glider kits, which have 

higher emissions of criteria pollutants like NOX than current engines, and which could have 

higher GHG emissions than Phase 2 engines. However, the Panel estimates that the number of 

vehicles produced by the small businesses who manufacturer glider kits is too small to have a 

substantial impact on the total heavy-duty inventory and recommended that existing small 

businesses be allowed to continue assembling glider vehicles without having to comply with the 

GHG requirements. The Panel recommended that EPA establish an allowance for existing small 

business glider manufacturers to produce some number of glider kits for legitimate purposes, 

such as for newer vehicles badly damaged in crashes. The Panel recommended that any other 

limitations on small business glider production be flexible enough to allow sales levels as high as 

the peak levels in the 2010-2012 timeframe. 

(7) Summary of Projected Impact on Small Businesses

EPA has chosen to propose the Panel’s recommended regulatory flexibility provisions for 

small business alternative fuel converters and vocational vehicle chassis manufacturers and we 

believe that all of the small businesses in these industries will be impacted by less than one 

percent of their annual sales. EPA is also proposing many of the Panel’s recommendations for 

small business trailer manufacturers, including seeking comment on the possibility of a small 

volume exemption. A majority of the small trailer manufacturers produce non-box trailers, and 
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are not required to adopt aerodynamic devices in this proposal. Additionally, many of the 

smallest trailer manufacturers produce specialty trailers that are candidates for exemption under 

the proposed off-highway or heavy-haul provisions described in Section IV C. (5). At this time, 

EPA believes the additional flexibilities offered for small business trailer manufacturers will 

reduce their burden below three percent of their annual sales. A more detailed description of the 

analysis to quantify the impact on small businesses in each affected industry sector is included in 

the IRFA as presented in Chapter 12of the draft RIA for this rulemaking. EPA invites comment 

on all aspects of the proposal and its impacts on small entities.

E. Unfunded Mandates Reform Act

This action contains a federal mandate under UMRA, 2 U.S.C. 1531–1538, that may

result in expenditures of $100 million or more for state, local and tribal governments, in the

aggregate, or the private sector in any one year. Accordingly, the agencies have prepared a 

statement required under section 202 of UMRA. The statement is included in the docket for this 

action and briefly summarized here.

The agencies have prepared a statement of the cost-benefit analysis as required by

Section 202 of the UMRA; this discussion can be found in this preamble, and in the draft RIA.

The agencies believe that the proposal represents the least costly, most cost-effective approach to 

achieve the statutory requirements of the rules. Section IX explains why the agencies believe 

that the fuel savings that would result from this proposal would lead to lower prices economy 

wide, improving U.S. international competitiveness. The costs and benefits associated with the 

proposal are discussed in more detail above in Section IX and in the Draft Regulatory Impact 

Analysis, as required by the UMRA.

This action is not subject to the requirements of Section 203 of UMRA because it 

contains no regulatory requirements that might significantly or uniquely affect small 

governments. 

F. Executive Order 13132: Federalism 

This action does not have federalism implications. It will not have substantial direct 

effects on the states, on the relationship between the national government and the states, or on 

the distribution of power and responsibilities among the various levels of government.

In the spirit of Executive Order 13132, and consistent with EPA policy to promote 

communications between EPA and State and local governments, EPA specifically solicits 

comment on this proposed rules from State and local officials.

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 mediumand heavy-duty on-highway vehicles and work trucks are not “automobiles,” as defined in 49 

U.S.C. 32901(a)(3). In Phase 1 NHTSA concluded that EPCA’s express preemption provision 

would not reach the fuel efficiency standards to be established in this rulemaking. NHTSA is 

reiterating that conclusion here for the proposed Phase 2 standards. 
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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 to be 

established in this rulemaking. 

NHTSA seeks public comment on this issue.

G. Executive Order 13175: Consultation and Coordination with Indian 

Tribal Governments

This action does not have tribal implications as specified in Executive Order 13175. This 

proposal will be implemented at the Federal level and impose compliance costs only on vehicle 

and engine manufacturers. Tribal governments would be affected only to the extent they

purchase and use regulated vehicles. Thus, Executive Order 13175 does not apply to this action. 

The agencies specifically solicit comment on this proposal from Tribal officials.

H. Executive Order 13045: Protection of Children from Environmental 

Health Risks and Safety Risks

This action is subject to Executive Order 13045 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. Accordingly, we have evaluated the environmental health or safety effects of these 

risks on children. The results of this evaluation are discussed below.

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 this proposal. In making those 

findings, EPA Administrator placed weight on the fact that certain groups, including children, 

are particularly vulnerable to climate-related health effects. In those findings, EPA

Administrator also determined that the health effects of climate change linked to observed and 

projected elevated concentrations of GHGs include the increased likelihood of more frequent and 

intense heat waves, increases in ozone concentrations over broad areas of the country, an 

increase of the severity of extreme weather events such as hurricanes and floods, and increasing 

severity of coastal storms due to rising sea levels. These effects can all increase mortality and 

morbidity, especially in vulnerable populations such as children, the elderly, and the poor. In 

addition, the occurrence of wildfires in North America have increased and are likely to intensify

in a warmer future. PM emissions from these wildfires can contribute to acute and chronic 

illnesses of the respiratory system, including pneumonia, upper respiratory diseases, asthma, and 

chronic obstructive pulmonary disease, especially in children. 

The agencies have estimated reductions in projected global mean surface temperature and 

sea level rise as a result of reductions in GHG emissions associated with the standards finalized
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in this action (Section VII and NHTSA’s DEIS). Due to their vulnerability, children may receive 

disproportionate benefits from these reductions in temperature and the subsequent reduction of 

increased ozone and severity of weather events.

As discussed in Section VIII.D.2, based on the magnitude of the non-GHG co-pollutant 

emissions changes predicted to result from the proposed standards, the agencies expect that there 

will be improvements in ambient air quality, pending a more comprehensive analysis for the 

final rulemaking. Due to their vulnerability, children may receive disproportionate benefits from 

these reductions, as well. 

Children are also more susceptible than adults to many air pollutants because of 

differences in physiology, higher per body weight breathing rates and consumption, rapid 

development of the brain and bodily systems, and behaviors that increase chances for exposure. 

Even before birth, the developing fetus may be exposed to air pollutants through the mother that 

affect development and permanently harm the individual.

Infants and children breathe at much higher rates per body weight than adults, with 

infants under one year of age having a breathing rate up to five times that of adults.896 In 

addition, children breathe through their mouths more than adults and their nasal passages are less 

effective at removing pollutants, which leads to a higher deposition fraction in their lungs.897

Certain motor vehicle emissions present greater risks to children as well. Early lifestages 

(e.g., children) are thought to be more susceptible to tumor development than adults when 

exposed to carcinogenic chemicals that act through a mutagenic mode of action.898 Exposure at a 

young age to these carcinogens could lead to a higher risk of developing cancer later in life. 

The adverse effects of individual air pollutants may be more severe for children, 

particularly the youngest age groups, than adults. The Integrated Science Assessments and 

Criteria Documents for a number of pollutants affected by these rules, including those for NO2, 

SO2, PM, ozone and CO, describe children as a group with greater susceptibility. Section 

VIII.B.7 discusses a number of childhood health outcomes associated with proximity to 

roadways, including evidence for exacerbation of asthma symptoms and suggestive evidence for 

new onset asthma. In general, these studies do not identify the specific contaminants associated 

with adverse effects, instead addressing the near-roadway environment as one containing 

numerous exposures potentially associated with adverse health effects.

 

896 U.S. Environmental Protection Agency. (2009). Metabolically-derived ventilation rates: a revised approach 

based upon oxygen consumption rates. Washington, DC: Office of Research and Development. EPA/600/R–

06/129F. http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=202543.

897 Foos, B.; Marty, M.; Schwartz, J.; Bennet, W.; Moya, J.; Jarabek, A.M.; Salmon, A.G. (2008) Focusing on 

children’s inhalation dosimetry and health effects for risk assessment: an introduction. J Toxicol Environ Health 

71A: 149–165.

898 U.S. Environmental Protection Agency. (2005). Supplemental guidance for assessing susceptibility from earlylife exposure to carcinogens. Washington, DC: Risk Assessment Forum. EPA/630/

R-03/003F. http://www.epa.gov/raf/publications/pdfs/childrens_supplement_final.pdf
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There is substantial evidence that people who live or attend school near major roadways 

are more likely to be of a minority race, Hispanic ethnicity, and/or low SES. Within these highly

exposed groups, children’s exposure and susceptibility to health effects is greater than adults due 

to school-related and seasonal activities, behavior, and physiological factors.

Section VIII.D.2 describes the expected ambient air quality changes for non-GHG copollutants resulting from the proposed standards, which represent levels to which the general 

population is exposed. Children are not expected to experience greater ambient concentrations 

of air pollutants than the general population. However, because of their greater susceptibility to 

air pollution and their increased time spent outdoors, it is likely that the proposed standards 

would have particular benefits for children’s health.

I. Executive Order 13211: Actions Concerning Regulations That Significantly 

Affect Energy Supply, Distribution, or Use

This action is not a “significant energy action” because it is not likely to have a 

significant adverse effect on the supply, distribution or use of energy. In fact, this proposal has a 

positive effect on energy supply and use. Because the combination of the proposed fuel 

economy standards and the proposed GHG emission standards would result in significant fuel 

savings, this proposal encourages more efficient use of fuels. Therefore, we have concluded that 

this proposal is not likely to have any adverse energy effects. Our energy effects analysis is 

described above in Section IX.

J. National Technology Transfer and Advancement Act and 1 CFR Part 51

This action involves technical standards. 

The agencies propose to use the following voluntary consensus standards from SAE 

International:

 SAE J1263 (March 2010) and SAE J2263 (December 2008) are voluntary consensus standards that 

together establish a test protocol to determine road-load coefficients for properly testing vehicles on a 

chassis dynamometer to simulate in-use operating conditions. Heavy-duty vehicle testing already 

relies on these reference standards under 40 CFR part 1066.

 SAE J2343 (July 2008). This voluntary consensus standard establishes a minimum hold time for 

LNG-fueled vehicles following a refueling event before the tank vents to relieve pressure. This is 

described further in Section XIII.A.3.

We are also aware that updated standards are pending for three SAE standards that are 

already incorporated by reference in the regulations—SAE J2263, SAE J1526, and SAE J2071. 

We will consider referencing these updated standards if they are adopted before completion of 

the final rule. All SAE documents are available from the publisher’s website at www.sae.org.

We are proposing to adopt updated versions of two ASTM standards that already apply 

under 40 CFR part 1036. This applies for ASTM D240–14 and ASTM D4809-13, both of which 

specify test methods for determining the heat of combustion of liquid hydrocarbon fuels.
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This action also involves technical standards for which there is no available voluntary

consensus standard. First, the agencies are proposing greenhouse gas emission standards for 

heavy-duty vehicles that depend on computer modeling to predict and emission rate based on 

various engine and vehicle characteristics. Such a model is not available from other sources, so 

EPA has developed the Greenhouse Gas Emission Model as a simulation tool for demonstrating 

compliance with emission standards. See Section II for a detailed description of the model. A 

working version of this software is available for download at 

http://www.epa.gov/otaq/climate/gem.htm.

Second, we need to define a benchmark gear oil for establishing a reference point for 

establishing improvements in axle efficiency. There is no voluntary consensus standard for this 

purpose. As described in Section II.C.1.c, we are instead proposing to identify the technical 

specifications for a commonly used commercial product from BASF Corporation. These 

technical specifications have been placed in the docket for this rulemaking.

Third, 40 CFR part 1037 includes several test procedures involving calculation with 

numerous physical quantities. We are incorporating by reference NIST Special Publication 811 

to allow for standardization and consistency of units and nomenclature. This standard, which 

already applies for 40 CFR parts 1065 and 1066, is published by the National Institute of 

Standards and Technology (Department of Commerce) and is available at no charge at 

www.nist.gov.

Fourth, the amendments for marine diesel engines involve technical standards related to 

the requirements that apply internationally. There are no voluntary consensus documents that 

address these technical standards. In earlier rulemakings, EPA has adopted an incorporation by

reference for MARPOL Annex VI and the NOX Technical code in 40 CFR parts 1042 and 1043. 

The International Maritime Organization adopted changes to these documents in 2013 and 2014, 

which need to be reflected in 40 CFR parts 1042 and 1043. EPA recently adopted the updated 

reference documents in 40 CFR part 1043. As noted in Section XIV.H.4, this proposal includes 

the remaining step of incorporating the updated IMO documents by reference in 40 CFR part 

1042. All these documents are available at www.imo.org.

K. Executive Order 12898: Federal Actions to Address Environmental 

Justice in Minority Populations and Low-Income Populations

The agencies believe the human health or environmental risk addressed by this action 

will not have potential disproportionately high and adverse human health or environmental 

effects on minority, low-income or indigenous populations. The results of this evaluation are 

discussed below. 

With respect to GHG emissions, the agencies have determined that these proposed rules 

would not have disproportionately high and adverse human health or environmental effects on 

minority, low-income or indigenous 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,

low-income or indigenous population. The reductions in CO2 and other GHGs associated with 

the standards would affect climate change projections, and the agencies have estimated 
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reductions in projected global mean surface temperatures (Section VII). Within communities 

experiencing adverse impacts related to 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.899 

For non-GHG co-pollutants such as ozone, PM2.5, and toxics, the agencies have

concluded that it is not practicable to determine whether there would be disproportionately high 

and adverse human health or environmental effects on minority, low income and/or indigenous 

populations from these rules. As discussed in Section VIII.D.2, however, based on the 

magnitude of the non-GHG co-pollutant emissions changes predicted to result from the proposed 

standards, EPA and NHTSA expect that there will be improvements in ambient air quality that 

would likely help in mitigating the disparity in racial, ethnic, and economically-based exposures, 

pending a more comprehensive analysis for the final rulemaking.

 

899 See Endangerment TSD, Note 10, above.
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XVI. EPA and NHTSA Statutory Authorities

As described below, the proposed regulations are authorized separately for EPA and 

NHTSA under the agencies’ respective statutory authorities. See Section I for a discussion of 

these authorities. 

A. EPA

Statutory authority for the vehicle controls proposed today is found in 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), 202 (d), 203-209, 216, and 301 of the Clean Air Act, 42 U.S.C. 7521 

(a), 7521 (d), 7522, 7523, 7524, 7525, 7541, 7542, 7543, 7550, and 7601.

Pursuant to 42 U.S.C. Section 4365, EPA must make certain proposed rules available to 

the Science Advisory Board (SAB) for review. EPA may also voluntarily choose to make other 

rules available to the SAB. EPA notified the SAB of its plans for this rulemaking and on June 

11, 2014, the chartered SAB discussed the recommendations of its work group on the planned 

action and agreed that no further SAB consideration of the supporting science was merited. 

B. NHTSA

Statutory authority for the fuel consumption standards proposed today is found in Section 

103 of the Energy Independence and Security Act of 2007, 49 U.S.C. 32902(k). EISA 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 

implement appropriate test methods, measurement metrics, fuel economy standards, and 

compliance and enforcement protocols that are appropriate, cost-effective and technologically 

feasible. To the extent motor vehicle safety is implicated, NHTSA’s authority to regulate it is 

also derived from the National Traffic and Motor Vehicle Safety Act, 49 U.S.C. §§ 30101 et. 

seq.

C. List of Subjects

40 CFR Part 85

Confidential Business Information, Imports, Labeling, Motor vehicle pollution, Reporting 

and recordkeeping requirements, Research, Warranties.

40 CFR Part 86

Administrative practice and procedure, Confidential business information, Incorporation 

by reference, Labeling, Motor vehicle pollution, Reporting and recordkeeping requirements.

40 CFR Part 600

Administrative practice and procedure, Electric power, Fuel economy, Incorporation by

reference, Labeling, Reporting and recordkeeping requirements.
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40 CFR Part 1033

Administrative practice and procedure, Air pollution control.

40 CFR Parts 1036 and 1037

Environmental protection, Administrative practice and procedure, Air pollution control, 

confidential business information, Incorporation by reference, Labeling, Motor vehicle pollution, 

Reporting and recordkeeping requirements, Warranties.

40 CFR Part 1039

Environmental protection, Administrative practice and procedure, Air pollution control, 

Confidential business information, Imports, Labeling, Penalties, Reporting and recordkeeping 

requirements, Warranties.

40 CFR Part 1043

Environmental protection, Administrative practice and procedure, Air pollution control, 

Imports, Incorporation by reference, Vessels, Reporting and recordkeeping requirements.

40 CFR Parts 1065 and 1066

Administrative practice and procedure, Air pollution control, Incorporation by reference, 

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, 535, and 537

Fuel economy, Reporting and recordkeeping requirements.

49 CFR Part 512

Administrative practice and procedure, Confidential business information, Freedom of 

information, Motor vehicle safety, Reporting and recordkeeping requirements.
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Page 850 of 850

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