1

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

NATIONAL VEHICLE AND FUEL EMISSIONS LABORATORY

2000 TRAVERWOOD DRIVE

ANN ARBOR, MI 48105-2498

 OFFICE OF

AIR AND RADIATION

Memorandum

From: Edward Nam, Director, Light Duty Vehicle and Small Engine Center, Assessment 

and Standards Division

To: Docket EPA-HQ-OAR-2010-0799

Date: August 10, 2012

Subject: Comparison of the Calendar Year Analyses for the Greenhouse Gas Emissions 

and Fuel Economy Programs for Model Year 2017-2025 Standards

This memorandum compares the benefits shown in the EPA’s and NHTSA’s respective 

analyses in the context of calendar years 2030, 2040 and 2050.1 A comparison of the agencies’ 

analyses shows the EPA GHG standards are projected to produce additional greenhouse gas 

emission reductions and fuel savings in these years. These additional savings are due to several 

differences between the GHG and CAFE standards, as discussed in Preamble Section I.C.2 The 

most significant of these include:

The GHG standards account for hydrofluorocarbon (HFC) emission reductions not 

required under CAFE. The HFC leakage control program will account for significant 

additional GHG benefits relative to the CAFE standards.

Under the EPA GHG program, there is no ability for a manufacturer to pay civil penalties 

in lieu of meeting the standard. Under EPCA, however, vehicle manufacturers are 

allowed to pay civil penalties as an alternative to compliance with applicable CAFE 

standards. NHTSA’s analysis explicitly (and properly) estimates the level of voluntary 

civil penalty payment by individual manufacturers, which reduces NHTSA’s estimates 

of both the costs and benefits of the CAFE standards. In contrast, as noted, the CAA 

does not allow for civil penalties in lieu of compliance with emission standards.

A number of smaller differences in the implementation of program flexibilities (flexible 

fueled vehicle credits during MY 2017-MY 2019, intermediate volume manufacturer 

standards, different treatment of alternative fueled vehicles, etc).

Modeling differences, as discussed in Preamble I.C.3

 

1 Results are from preamble tables III-62, IV-67 and IV-68 in the Final Rulemaking 2017 and Later Model Year 

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

2 A similar discussion of the differences in the EPA and NHTSA statutory authorities and resulting modeling 

techniques is shown in the MYs 2012-2016 rule (75 FR at 25343). 

3 As noted in preamble tables I-1 and I-2, NHTSA projects a fleet average shortfall of 2.3 MPG between the 

achieved and the required fuel economy in MY 2025. Under NHTSA Environmental Impact Analysis approach A1, 

fuel economy levels are held constant after MY 2025, and this gap continues indefinitely. See Final EIS page 2-36 

(Docket No. NHTSA-2011-0056).
2

Table 1 - Comparison of Calendar Year Benefits4

GHG reductions

GHG stds.

(MMT CO2eq)

CAFE stds.

(MMT CO2)

Additional Benefit

from GHG stds.

(%)

Additional Benefit

from GHG stds.

(MMT CO2eq)

2030 271 224 17% 47

2040 455 349 23% 106

2050 569 416 27% 153

Fuel Savings (B. Gallons)

GHG stds.

(B. Gallons)

CAFE stds.

(B. Gallons)

Additional Benefit

from GHG stds.

(%)

Additional Benefit

from GHG stds.

(B. Gallons)

2030 23 21 9% 2

2040 39 32 18% 7

2050 49 39 20% 10

 

4 Results are from preamble tables III-62, IV-67 and IV-68