Fuel economy and drivability have deteriorated as a result of engine changes made to reduce exhaust emissions in recent-model cars. To study this problem, chassis dynamometer tests were run with 1970 and 1972 cars using both cold-start and hot-start procedures. Fuel economy and drivability were evaluated during the first 2 miles and the last 3 miles of a 50°F cold-start driving cycle similar to the Coordinating Research Council road test. Fuel economy was also evaluated under warmed-up conditions at 72°F using the last half of the cold-start cycle. The effects of car year model, gasoline volatility, gasoline heat content, and car warmup are discussed in this paper.