This paper presents the results of a gasoline reformulation project carried out in Finland during 1993. The project focused on the impact of gasoline sulfur and benzene content on exhaust emissions. Twelve 1990 - 1993 model vehicles were tested using two fuel sulfur levels, 500 and 100 ppm, and two benzene levels, 1 wt.% and 3 wt.%. Another subject of investigation was evaporative emissins during refuelling.
When the sulfur content of the fuel was reduced from 500 to 100 ppm, the regulated exhaust emissions from catalyst cars decreased at test temperatures 22°C as follows: carbon monoxide CO 14%, total hydrocarbons THC 7% and nitrogen oxides NOx 9%. At test temperatures -7°C the reduction of sulfur content gave smaller benefits expressed in percentages, but the absolute changes (g/km) were at the same level as at +22°C.
When the benzene content of the gasoline was decreased from 3 wt.% to 1 wt.%, the benzene emissions of cars were reduced by 20 - 30 % both at test temperatures 22°C and at test temperatures -7°C.
Total hydrocarbons and benzene evaporation was determined during refuelling. Total HC decreased in direct proportion to a 24 percent reduction in vapor pressure. Benzene evaporation decreased two thirds when low benzene fuel was used.