A review of passenger car performance trends over the past 18 years as observed from new car performance testing of a test car fleet (totaling 200 cars) is presented. The relation of the make-up of the test car fleet to the national average is shown. Trends in operating variables such as horsepower, thermal and volumetric efficiencies, fuel and air consumption, crankcase ventilation and blowby, octane requirement, vapor locking tendencies, and various temperatures are presented. Possible changes in these trends due to the incorporation of exhaust emission control devices on the vehicles of the 1966 through 1968 model years are considered.
