OFFICE OF


AIR AND RADIATION 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 


WASHINGTON, D.C. 20460

The Honorable James M. inhofe 

Ranking Member 

Committee on Environment and Public Works 

United States Senate 

Washington, D.C. 20510 

Dear Senator Irthofe: 

Thank you for your February 28, 2012, letter regarding the U.S. Environmental Protection Agency's and 

the Department of Transportation's (DOT) proposal to improve fuel economy and reduce greenhouse 

gas emissions for model year 2017-2025 light-duty vehicles. The Administrator asked that I respond on 

her behalf. 

I welcome the opportunity to provide you with an overview of this proposed rulemaking and respond to 

your specific questions. Under the President's leadership, the EPA and DOT have developed a proposed 

rule, which is good for the American economy and consumers, improves our environment, reduces our 

dependence on foreign oil, and strengthens the nation's energy security. 

The first phase of the national program to improve fuel economy and reduce greenhouse gas emissions 

from passenger cars and light trucks, including SUVs, crossovers, and rninivans, for model years (MY) 

2012-2016 was finalized in April, 2010. The MY 2017-2025 light-duty proposal, released on November 

16, 2011, builds on the success of the 2012-20 16 program. This second phase is projected to save 

approximately 4 billion barrels of oil and 2 billion metric tons of greenhouse gas emissions over the 

lifetimes of those vehicles. 

Consumers purchasing MY 2017-2025 vehicles would also experience significant fuel savings at the 

pump, far outweighing higher vehicle cost. On average, consumers who buy a new MY 2025 vehicle 

will save $5,200 to $6,600 in fuel costs during the lifetime of the vehicle. These fuel savings more than 

offsets the higher lifetime costs for new vehicle technology (about $2,200 on average), for a net lifetime 

savings of $3,000 to $4,400. 

These important national programs have garnered wide-spread support as models for how government 

can effectively work with a wide range of stakeholders to develop thoughtful, data-driven standards, 

which are supported by the regulated industry, consumer groups, labor unions, states, environmental 

organizations, and industry suppliers. We are proud of how the EPA and DOT have successfully worked 

together to create common sense standards that benefit all Americans. 

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As you are aware, the MY 2017-2025 light-duty proposed rule was released on November 16, 2011. 

Between January 17 and 24, the EPA and the National Highway Traffic Safety Administration held 

three public hearings in Detroit, Philadelphia and San Francisco. Nearly 400 people testified and many 

more attended the hearings. The written comment period closed on February 13, 2012, and to date we 

have received more than 290,000 comments, including extensive written comments from more than 140 

organizations. The agency is fully reviewing and analyzing the public comments as we work toward a 

final rule. 

Your letter posed five specific questions, and our responses are provided in the enclosure. 

Again, thank you for your letter. If you have further questions, please contact me or your staff may call 

Patricia Haman in EPA's Office of Congressional and Intergovernmental Relations at (202) 564-2806. 

Gina McCarthy 

Assistant Administrator
Responses to Ouestions from Senator Inhofe's February 28. 2012 Letter 

1. On what basis does EPA conclude that its proposed rule's deleterious effect on PM2.5 emissions 

will be offset within the proposed GHG regulations? 

In the Joint EPA/DOT rulemakin, the EPA proposed greenhouse gas emissions standards that will 

result in a net reduction of PM2, 5 . In 2030, the EPA estimates that the MY 20 17-2025 light-duty 

standards would reduce total PM inventories by 3,123 short tons. 2 The EPA analyzed the impact the 

proposed MY 2017-2025 light-duty vehicle GHG rule would have on PM 2.5 and other non-GHG 

pollutants in both 2020 and 2030. For PM2.5 , the EPA estimates reductions in "upstream" PM2.5 

emissions, including reductions from fuel refining, distribution and transport as a result of the proposed 

standards, We also estimated "downstream" increase in PM 2.5 due to people driving more. The rule 

effectively makes the cost per mile of driving lower for consumers, increasing the likelihood that they 

will drive more. This is known as the "rebound effect." Thus this downstream PM 2.5 increase is a result 

of a predicted change in driving behavior consistent with the economic literature, as well as the past four 

Corporate Average Fuel Economy (CAFE) rulemakings. In addition, we also estimate a small increase 

in PM2, 5 from power plants as electric powertrain vehicles increase in prevalence as a result of this rule. 

With regard to advanced engine technologies, such as "gasoline direct injection fuel systems" or GDI, 

there are various forms of this technology in production today. While some initial designs are not yet 

optimized for PM emissions performance, the EPA believes that industry will have adopted the cleanest 

forms of ODI by the timeframe of this rule, It should be noted that all light-duty vehicles must meet the 

same PM emissions standards under this proposed rule. 

2. If the GHG regulations will not themselves offset EPA's own increase In PM 2.5 emissions, then 

on what basis does EPA have authority to increase public exposure to this pollutant? 

As explained in our response to question 1, the EPA's proposed greenhouse gas emissions standards for 

MY 20 17-2025 light-duty vehicles will result in a net reduction 3,123 short tons of PM2.5. 

3. How much of the PM2,5 emissions problem created by EPA's GHG standards will be offset by 

the proposed Tier 3 fuel regulations? 

As explained in response to question 1, the EPA estimates that the MY 2017-2025 proposed GHG 

standards will reduce total PM inventories. The vehicles we expect to be produced as a result of the MY 

2017-2025 light-duty vehicle standards will not increase PM 2.5 ; all vehicles must meet the EPA's 

existing PM standards. 

The Tier 3 proposal would reduce motor vehicle emissions and help state and local areas attain and 

maintain the existing health-based air quality standards, including the National Ambient Air Quality 

Standard (NAAQS) for ozone, in a cost-effective and timely way. 

4. On what basis can EPA guarantee that its GHG regulations, lacking a "0.15 multipLier" for 

CNG and alternative fuel vehicles, will not limit auto companies' utilization of NHTSA's own 

proposed 0.15 "multiplier?" 

The proposed greenhouse gas standards in no way limit the number of natural gas vehicles auto 

companies can introduce into the market. We proposed that compliance values for natural gas vehicles 

'76 Fed. Reg. 74,854, 75,100-75,101 (Dec. 1,2011). 

2 76 Fed. Reg. at 75,101.
be based on their demonstrated emissions performance. Because of natural gas' fuel properties, natural 

gas vehicles typically have lower greenhouse gas emissions (up to 25% lower) than a comparable 

gasoline vehicle. If the natural gas vehicle is optimized for the high octane of natural gas fuel, its 

greenhouse gas emissions could be even lower. It is true that this greenhouse gas emissions compliance 

benefit is not as great as the CAFE credits that are currently available to natural gas vehicles. The EPA 

has received public comments on this matter, and is considering whether to offer additional regulatory 

incentives in the final rule. 

5. If there is a residual possibility for conflict between EPA's and NHTSA's proposed rules, with 

respect to NHTSA's 0.15 "multiplier," then on what basis does EPA have authority to limit 

NHTSA's implementation of Congress's statutes and policies favoring that incentive program for 

CNG and alternative fuel vehicles? 

The EPA's proposal to base greenhouse gas emissions compliance on actual emissions performance is 

based on our Clean Air Act authority. We believe that basing emissions compliance on demonstrated 

emissions performance is a reasonable exercise of our discretion under the Clean Air Act. We 

requested comments on mechanisms to create incentives for CNG and CNG vehicles in the proposal. 

As stated in question 4, the EPA has received public comments on this matter, and will be considering 

whether it is appropriate to grant additional regulatory incentives to CNG vehicles in the final MY 2017-

2025 greenhouse gas standards.