The Coordinating Research Council, Inc. (CRC), under contract to the U.S. Department of Energy, conducted controlled tests to determine the effects of 10% ethanol-gasoline blends on emissions, fuel economy, and driveability of 14 - 1980 model year cars representing several emission-control technologies. Two types of ethanol blends were tested, a simple blend with no volatility adjustment, and two volatility-adjusted blends. Addition of 10% ethanol to gasoline resulted in statistically significant changes in emissions, driveability, and efficiency. Statistically significant effects were also found as a result of volatility adjustment. However, because of the limited fleet size, these results should not be used to quantitatively predict effects of the use of ethanol-gasoline blends in the total U.S. vehicle population.