In November 1976, the Environmental Protection Agency promulgated rules covering the classification of automobiles for the purpose of fuel economy labeling and the Gas Mileage Guide. Since that time a number of changes have been made in the classification system and the interior volume measurements on which that system is based. This paper reports on the reasons for those changes and their impact on the classification of model year 1978 vehicles.
The paper also discusses various trends in vehicle design as measured by interior and exterior volume, weight and fuel economy. Trends in varous design efficiency factors are examined for model years 1976-1978 and a data base is presented for future analysis.