European Programme on Emissions, Fuels and Engine Technologies (EPEFE) - Gasoline Aromatics/E100 Study

The effects of aromatics and mid-range volatility (E100) were investigated in a fleet of sixteen prototype European gasoline vehicles calibrated to meet the 1996 European emissions limits. A 3×3 fuel matrix was blended with independently varying aromatics and E100, other fuel properties being held constant. The test fleet was chosen with a wide variation in emissions, and vehicles fitted with close-coupled catalysts gave lowest emissions. There was also a wide variation in vehicle response to fuel properties. High HC emissions on some vehicles for fuels with low E100 (35% v/v) were attributed to driveability problems caused by these fuels. Reducing aromatics reduced composite cycle fleet average emissions of Carbon Monoxide (CO), Total Hydrocarbons (THC) and Carbon Dioxide (CO₂) but increased Oxides of Nitrogen (NOx). Increasing volatility reduced HC emissions, increased NOx, had no effect on Carbon Dioxide and showed minimum CO at 50% v/v aromatics. Benzene emissions reduced with decreasing aromatics, but emissions of other potential air toxics increased.