21 Feb 2004

Fuel effects on emissions from modern gasoline vehicles part 2 – aromatics, olefins and volatility effects

Report no. 2/04: The influence of gasoline quality on exhaust emissions has been evaluated using four modern European gasoline cars with advanced engine technologies/after treatment systems. Part 1 of this report described the short-term sensitivity of these four cars to gasoline sulphur content. This report describes the influence of other fuel effects: aromatics, olefins, volatility and final boiling point.

Emissions from the test vehicles were all very low, in compliance with the appropriate Euro 3 or Euro 4 emission limits. The measured effects of fuel changes on the regulated emissions: NOx, HC and CO, were small and often conflicting, with differing directional responses for different vehicles and emissions.

The three direct injection cars emitted higher levels of particulate mass (PM) than the advanced MPI car, although much lower than the Euro 4 diesel PM emission limit. Response to fuel effects was similar in the three direct injection cars. PM emissions from the advanced MPI car, which is more representative of the current fleet, were very low on all fuels tested and insensitive to fuel changes.

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