Testimony of the 

National Association of Clean Air Agencies 

before the 

U.S. Environmental Protection Agency 

and the 

National Highway Traffic Safety Administration 

on the 

Proposed Greenhouse Gas and Fuel Efficiency Standards for 

Medium- and Heavy-Duty Engines and Vehicles – Phase 2 

Docket ID No. EPA-HQ-OAR-2014-0827 

August 6, 2015 

Chicago, Illinois 

The National Association of Clean Air Agencies (NACAA) appreciates this 

opportunity to provide testimony on the U.S. Environmental Protection Agency’s (EPA) 

and the U.S. Department of Transportation National Highway Traffic Safety 

Administration’s (NHTSA) Proposed Phase 2 Greenhouse Gas and Fuel Efficiency 

Standards for Medium- and Heavy-Duty Engines and Vehicles, as published in the 

Federal Register on July 13, 2015 (80 Fed. Reg. 40,137). NACAA is a national, nonpartisan, non-profit association of air pollution control agencies in 41 states, the District of 

Columbia, four territories and 116 metropolitan areas. The air quality professionals in our 

member agencies have vast experience dedicated to improving air quality in the U.S. 

This testimony is based upon that experience. The views expressed in this testimony do 

not represent the positions of every state and local air pollution control agency in the 

country.

According to EPA, although heavy-duty trucks account for less than 5 percent of 

vehicles on U.S. roads, they are responsible for about 20 percent of the U.S. 

transportation sector’s energy use and GHG emissions and are the second largest 

source of GHG emissions in the transportation sector after passenger cars and light 

trucks. These vehicles consume about 2.5 million barrels of oil a day and produce 

almost a half billion tons of carbon a year. 

NACAA supported EPA’s and NHTSA’s efforts to adopt the first phase of GHG 

and fuel efficiency standards for heavy-duty vehicles and engines, which took effect with 

Model Year (MY) 2014 and is being phased in through MY 2018. Now, we are pleased 

to support your agencies’ efforts to advance this program by establishing Phase 2 

standards. We believe your proposal holds great promise for achieving further GHG 

reductions and better fuel efficiency from heavy-duty combination tractors, trailers, 

vocational vehicles and heavy-duty pickups and vans. Fulfilling that promise, however, 

will require some key improvements to the proposal. 
But before addressing those, NACAA would like to commend EPA and NHTSA on several of the 

various aspects of the proposed rule that our association strongly supports. First, we fully endorse the 

continued inclusion of separate but complementary standards for engines and full vehicles – this is a 

fundamental aspect of the rule. Second, the inclusion of standards for trailers, particularly box trailers, is 

critical given their significant contribution to fuel consumption by long-haul trucks. Third, we are very much 

in favor of EPA’s proposal to close the existing loophole for glider kits, under which used pre-2013 engines 

– with no limit on age – may be installed into new glider kits without meeting applicable standards. We 

agree with EPA that its regulations should be revised to require that only engines that have been certified to 

meet the prevailing standards be eligible for installation into new glider kits. 

Now NACAA would like to highlight aspects of the rule our association believes should be 

improved. 

 In a March 18, 2015 letter to your respective agencies,1 NACAA provided our recommendations for 

essential components of a Phase 2 rule. In those recommendations, we urged for a rule that would reduce 

GHG emissions and fuel consumption across the entire fleet by at least 40 percent, on average, compared 

to 2010. Unfortunately, we find the overall effectiveness of the Phase 2 proposal to fall short of our 

recommendation and, more importantly, significantly short of what can and should be achieved. 

Accordingly, we believe the overall stringency of the proposal should be enhanced to take advantage of

missed opportunities that, if incorporated into the final rule, would drive technology and ensure that

maximum benefits are gained. 

Toward this end, we believe the proposed engine standard must be strengthened. Others – 

including the California Air Resources Board (CARB),

2

 engine makers3 and independent non-governmental 

organizations4 – have suggested engine efficiency can be improved by 15 percent or more, compared to 

the 4.2 percent proposed by EPA. Further, their analyses, as well as those of EPA, indicate that 

technologies to achieve this degree of improvement are currently available and highly cost effective. We 

believe it is imperative that EPA strengthen the engine standard in the final rule to reflect this. 

 With respect to timing, NACAA strongly supports EPA’s proposed Alternative 4, under which the 

standards would be fully implemented by 2024. This implementation deadline is entirely feasible and vitally 

important to spur much-needed near-term emissions reductions and technological innovation. NACAA 

urges EPA to finalize Alternative 4 rather than Alternative 3, which would unnecessarily extend full 

implementation by three years to 2027. 

Our March 18, 2015 letter also included a recommendation that EPA articulate in the proposal the 

need for significantly lower national heavy-duty nitrogen oxide (NOx) standards beyond the current 2010 

onroad heavy-duty NOx exhaust emission standards and nonroad heavy-duty engine exhaust emission 

standards. We are very disappointed that EPA has not included such a discussion in this proposal. 

 

1

NACAA Letter to EPA and NHTSA providing recommendations on a Phase 2 regulatory proposal (March 18, 2015), 

http://www.4cleanair.org/sites/default/files/Documents/NACAA-Letter_to_EPA_DOT-Ph2_HD_Fuel_EffGHG_Stds-031815.pdf. 

2

 California Air Resources Board, Draft Technology Assessment: Engine/Powerplant and Drivetrain Optimization and Vehicle 

Efficiency (June 2015), http://www.arb.ca.gov/msprog/tech/techreport/epdo_ve_tech_report.pdf. 

3

 Cummins, Engine Technologies for GHG and Low NOx (April 2015), 

http://www.arb.ca.gov/msprog/onroad/caphase2ghg/presentations/2_7_wayne_e_cummins.pdf. 

4

 International Council on Clean Transportation, Advanced Tractor-Trailer Efficiency Technology Potential in the 2020-2030 

Timeframe (April 2015), http://www.theicct.org/sites/default/files/publications/ICCT_ATTEST_20150420.pdf. 
3 

Although there is the potential for ancillary NOx reductions from the Phase 2 rule, the achievement of these 

reductions is not certain (we note that predicted ancillary benefits of Phase 1 did not occur). Moreover, 

even if ancillary NOx benefits do accrue under the Phase 2 rule, they will not be nearly sufficient given the 

challenges state and local agencies face in attaining and maintaining current and upcoming ozone and fine 

particulate matter (PM) standards and protecting against visibility impairment and eutrophication of water 

bodies. We urge that EPA include in the final Phase 2 rule a clear and comprehensive discussion of the 

need for very substantial additional NOx reductions from heavy-duty vehicles and engines and, even more 

critically, an explicit commitment to begin immediately a separate rulemaking initiative to capture those 

reductions. 

Finally, EPA projects an increase in the use of auxiliary power units (APUs) in Phase 2 and an 

associated 10-percent increase in PM emissions. The agency seeks comment on this, but proposes 

nothing to address the unacceptable and unnecessary expected rise in PM pollution. NACAA recommends 

that EPA include in the final rule a requirement, similar to CARB’s, that APUs be equipped with diesel

particulate filters to capture the PM. 

 In conclusion, NACAA believes EPA and NHTSA have a tremendous opportunity to finalize a rule 

that will effectively address heavy-duty vehicle and engine GHG emissions and fuel consumption and set

the stage for a separate rule to achieve meaningful additional NOx reductions. We urge you to make the 

most of this opportunity. Further, in doing so, we encourage that your agencies collaborate with experts at 

CARB, given California’s unique ability to regulate these same source categories, its decades of 

experience in doing so and the past success that has been achieved when EPA, and more recently 

NHTSA, have collaborated with CARB. 

In the coming weeks, we will continue to study issues related to the Phase 2 proposal and will offer 

additional comments in writing by the September 17, 2015 deadline. In the meantime, we appreciate the

chance to provide the comments we have offered today and look forward to continuing to work with EPA and 

NHTSA on this important initiative.