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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.

Although exhaust gas odorants are generally a product of engine and fuel parameters, it is the vehicle that the public associates with exhaust odor. The vehicle and its movements have a large influence on the dispersion of exhaust odorants and, therefore, on the actual public exposure to exhaust odor. A considerable amount of public exposure to vehicle exhaust odor results from municipal operation of diesel-powered buses, especially during the bus-stop sequence. Panel test procedures were developed for field evaluation of full-scale vehicle exhaust odor intensity during the idle and acceleration portions of a simulated bus-stop sequence. Odor tests, based on natural dilution of the vehicle exhaust to the odor threshold, were conducted in a controlled environment, indoors in large buildings. Different degrees of exhaust dilution were achieved by randomly varying the distance from the test vehicle to the panelists.

The importance of the fuel in providing improved vehicle performance and reduced emissions has become widely recognized, especially in the past ten years. In 1998, an SAE paper was presented providing a systematic analyses of 1996 United States gasoline quality. This paper extends the methodology of that paper to include the impact of fuel composition on evaporative emissions, and it provides analyses of gasoline quality for the years of 1996, 1997 and 1998. The vehicle performance and emissions characteristics of gasolines were determined using data from surveys of United States' service station gasoline samples. 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.