The influence of heavy gasoline components on the exhaust emissions of European vehicles. Part 1 – regulated emissions

Report no. 94/59: Ten European vehicles, meeting the requirements of the EU 'Consolidated Emissions Directive', have been tested on a matrix of seven gasolines over the current ECE+EUDC test cycle. The programme was designed to investigate the effects of heavy gasoline components in terms of both distillation and composition on the emissions performance of a fleet of modern fuel injected catalyst cars.Gasoline back end volatility and composition both had some effect on regulated emissions performance. For HC and CO emissions, back end volatility overall had a larger effect than composition. However, The back end effects were discontinuous, with no measurable effect between the 160°C and 180°C T90 fuels.

The fuel effects on NOx emissions were in the opposite direction to those for HC and CO, and compositional influences in this instance were greater than those due to back end volatility.The back end volatilities of all the test fuels differed to an increasing extent from mid range (T50) to final boiling point (FBP). It was not possible to ascribe the fuel effects to any one distillation point within this range; neither to distillation temperatures at percent volumes recovered (T values), nor to percent evaporated volumes at certain temperatures (E values). Throughout all the tests, it was evident that emissions performance differences between the cars were substantially higher than differences observed across the fuel matrix.