Recommendation 2.1: Because differences in the fuel consumption of vehicles relate directly to fuel savings, the labeling on new cars and light-duty trucks should include information on the gallons of fuel consumed per 100 miles traveled in addition to the already-supplied data on fuel economy so that consumers can become familiar with fuel consumption as a fundamental metric for calculating fuel savings.
Finding 2.2: Fuel consumption in this report is evaluated by means of the two EPA schedules: UDDS and HWFET. In the opinion of the committee, the schedules used to compute CAFE should be modified so that vehicle test data better reflect actual fuel consumption. Excluding some driving conditions and accessory loads in determining CAFE discourages the introduction of certain technologies into the vehicle fleet. The three additional schedules recently adopted by the EPA for vehicle labeling purposes—ones that capture the effects of higher speed and acceleration, air-conditioner use, and cold weather—represent a positive step forward, but further study is needed to assess to what degree the new test procedures can fully characterize changes in in-use vehicle fuel consumption.
Recommendation 2.2: The NHTSA and the EPA should review and revise fuel economy test procedures so that they better reflect in-use vehicle operating conditions and also better provide the proper incentives to manufacturers to produce vehicles that reduce fuel consumption.
EPA (U.S. Environmental Protection Agency). 2008. Light-Duty Automotive Technology and Fuel Economy Trends: 1975 Through 2008. EPA420-R-08-015. September. Washington, D.C.
Fischer, C. 2009. Let’s turn CAFE regulation on its head. Issue Brief No. 09-06. May. Resources for the Future, Washington, D.C.
Foljambe, E.S. 1916. The automobile fuel situation. SAE Transactions, Vol. 11, Pt. I.
General Motors Company. 2009. Chevy Volt gets 230 mpg city EPA rating. Press release. August 11.
Heywood, J.B., 1988. Internal Combustion Engine Fundamentals. McGraw-Hill, New York.
Kettering, C.F. 1918. Modern aeronautic engines. SAE Transactions, Vol. 13, Pt. II.
Larrick, R., and J. Soll. 2008. The mpg illusion. Science 320(5883):1593-1594.
Ricardo, Inc. 2008. A Study of Potential Effectiveness of Carbon Dioxide Reducing Vehicle Technologies. Prepared for the U.S. Environmental Protection Agency. EPA420-R-08-004. Contract No. EP-C-06-003. Work Assignment No. 1-14. Ann Arbor, Michigan.
Sovran, G., and D. Blaser. 2003. A contribution to understanding automotive fuel economy and its limits. SAE Paper 2003-01-2070. SAE International, Warrendale, Pa.
Sovran, G., and D. Blaser. 2006. Quantifying the potential impacts of regenerative braking on a vehicle’s tractive-fuel consumption for the US, European and Japanese driving schedules. SAE Paper 2006-01-0664. SAE International, Warrendale, Pa.