The importance of the fuel in providing improved vehicle performance and reduced emissions has become widely recognized in the past ten years. However, few if any systematic analyses of gasoline quality have ever been published.A methodology has been developed for analyzing the vehicle performance and emissions characteristics of gasolines. It has been applied to data obtained from surveys of United States' service station gasoline samples obtained in 23 cities during 1996. Results are presented for: gasoline type (California RFG - reformulated gasoline, Federal RFG, low RVP - Reid Vapor Pressure, and conventional); gasoline grade (regular, intermediate and premium); individual cities; individual brands (coded); and for sulfur content, the fuel property with the greatest current interest. It is concluded that large differences exist among commercial gasolines for all of the items evaluated.