Concise Description of Auto Fuel Economy and Performance in Recent Model Years

The subject is treated by statistical and engineering analyses applied to extensive measurements of fuel economy and acceleration performance. Fuel economy data are provided by the EPA certification lists for the four years 1973 to 1976. The performance data are track measurements of 0 to 60 MPH acceleration times for 1974 and 1975 vehicles, as reported in the popular automotive literature. Several relations, supported by engineering analyses, are selected for making least-squares fits to the extensive measurements. The pivotal variables include: inertia weight, horsepower, engine displacement and rear axle ratio, individually and in combinations. Satisfactory fits are made by power factorial forms and the resulting algorithms have standard errors of estimate in the vicinity of 10% for fuel economy and in the range 10% to 15% for acceleration time. Basically similar power factorial forms fit equally well various data subsets obtained by model year, by driving schedule, by auto vs. truck, by Federal vs. California certification, by automatic vs. manual transmission, etc. The results are extensively discussed and interpreted, and sufficient comparisons are made with results from other statistical and engineering analyses.