An owner survey was conducted to determine the owner-measured in-use fuel economy of 1980 model passenger cars for a number of manufacturers. The in-use fuel economy is compared to the laboratory tested fuel economy ratings as established by the Environmental Protection Agency. An analysis of how this comparison has changed between 1975, 1976, 1978, and 1980 models is presented. Finally, an analysis was done on the influence of vehicle design parameters on the differences between EPA laboratory ratings and in-use fuel economy. The design parameters studied include front wheel drive, diesel engines, and manual transmissions.