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Annual surveys on Octane Number Requirement(ONR) of Japanese model passenger cars have been conducted, and the trend covering the period of 1982-1992 is described as a follow-up of the earlier report-SAE 830510. The ONRs showed a gradual decrease until 1990, but increased in later two years, reaching 91.2 and 95.3 ON at 50% and 90% car satisfaction levels, respectively, in 1992. The ONR at high speed range(80-120 km/hr) tended to increase and its differences from the low speed ONR(30-120 km/hr) have become gradually smaller for 1985-1992. Also, engine speed distribution at the maximum ONR values shifted to higher speed range above 2050rpm. Reflecting the recent increasing use of premium gasoline-spec cars, ONR distribution of these cars was separately measured, and resulted in 97.5 and 100.5 RON at 50% and 90% satisfaction levels respectively, in 1992 year model cars. This value is approximately 5 RON higher than regular gasoline spec cars at 90% satisfaction level.

According to the recent dieselization and the decrease in the amount of crude oil processed in Japan, the shortage of middle distillate including diesel fuels is problem. The useful methods for increasing the yield of the middle distillate are the deeper-cut and blending of cracked distillate such as light cycle oil from FCC. For the use of these methods to the diesel fuel design, effects of fuel properties such as viscosity, distillation range, cetane number on diesel performance were studied. Especially, the effects on gaseous and smoke emissions, diesel knock, startability, fuel consumption in passenger cars equipped with indirect injection engines and trucks equipped with direct injection engines were evaluated. In addition, cold performance of both cars was also investigated. One of the main conclusions of this study is that lower cetane fuels is generally associated with increased emissions and fuel consumption.