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In response to growing concern over the validity of the EPA fuel economy numbers, the Department of Energy undertook a study of actual on-road fuel economy as it compares to the EPA numbers. This report covers the development of the data base for that study, the analysis techniques used for the initial phases of the work, and the preliminary results of that analysis. Data on over 5000 in-use vehicles were collected for model years 1974-1977. Data were obtained from a number of private and government groups for vehicles in fleet and typical consumer use, from on-road tests, and from in-use dynamometer tests. Comparisons using linear regressions were made between these mpg values and the EPA certification results for the same models. The results describe these differences as a function of vehicle mpg and model year. Other more specific comparisons are also made. An analysis of in-use fuel economy ranking, compared to the ranking by the EPA mpg numbers, is presented.

This paper is the latest in a series of reports on the U.S. Department of Energy’s (DOE) comparison of Environmental Protection Agency (EPA) fuel economy estimates and on-road fuel economy performance. Earlier reports described a variety of analysis techniques, described DOE’s expanding inuse fuel economy data base, and presented analysis of trends in EPA- versus on-road fuel economy. The focus of this paper is the most recent additions to the data base (including data on light trucks and 1981 model-year cars), the development of DOE analysis techniques, and some of the more interesting trends revealed in this year’s analysis. Particular attention is given to model-year and vehicle-type differences, including driveline technology and model-type trends. The application of these results to improving fuel economy information programs and advertising for consumers is examined.

The cost effectiveness of the current automobile fuel economy standards program is evaluated. A life cycle cost analysis is used to quantify the costs and benefits of fuel economy improvements stimulated by the program. The magnitude of these improvements is estimated by measuring the difference between the standards and a baseline “no standards” case. Due to the uncertainty associated with technology cost estimates, two scenarios are developed to bound the cost of fuel economy improvement; an “optimistic” scenario using technology cost and MPG gains documented by DOT and another “pessimistic” scenario based on conservative technology cost and fuel economy estimates. A review of fuel economy legislation concludes that marginal cost effectiveness to the nation be a significant criterion for setting future fuel economy standards.

Data were collected on alternative estimates of factors influencing fuel demand. These factors include: new vehicle registrations, vehicle miles of travel, vehicle scrappage and fuel economy. A methodology was then applied to assess the sensitivity of fuel demand to variations of each individual factor (within the range of the available data sources). A Base Case projection of fuel demand by vehicle type and fuel type is presented in detail. In addition, the impacts of two realistic alternative cases representing increased conservation efforts and increased fuel consumption are also analyzed.