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.