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A joint test programme has been carried out by CONCAWE and GFC to evaluate the impact of gasoline volatility and ethanol on the driveability performance of modern European vehicles. Eight vehicles, three with DISI fuel systems and five with MPI, were tested for hot driveability performance. After screening tests, a subset of four vehicles was selected and tested for cold driveability. The latest test procedures developed by GFC were used for both hot (20, 30 and 40°C) and cold (+5 and -10°C: representative of moderate winter conditions) weather testing on climate controlled chassis dynamometers. A matrix of four hydrocarbon test fuels at two levels of DVPE and E70 was blended for the hot weather testing, and three fuels with varying E100 but essentially parallel distillation curves for the cold weather tests. For each hydrocarbon fuel, two other fuels containing 10% ethanol were made, one splash blend and one with matched volatility.

The influence of gasoline quality on exhaust emissions has been evaluated using four modern European gasoline cars with advanced features designed to improve fuel economy and CO2 emissions, including stoichiometric direct injection, lean direct injection and MPI with variable valve actuation. Fuel effects studied included sulphur content, evaluated over a range from 4 to 148 mg/kg, and other gasoline properties, including aromatics content, olefins content, volatility and final boiling point (FBP). All four cars achieved very low emissions levels, with some clear differences between the vehicle technologies. Even at these low emissions levels, all four cars showed very little short-term sensitivity to gasoline sulphur content. The measured effects of the other gasoline properties were small and often conflicting, with differing directional responses for different vehicles and emissions.

Fuel volatility and vehicle characteristics have long been recognised as important parameters influencing the exhaust emissions and the driveability of gasoline vehicles. Limits on volatility are specified in a number of world-wide / national fuel specifications and, in addition, many Oil Companies monitor driveability performance to ensure customer satisfaction. However, the relationship between driveability and exhaust emissions is relatively little explored. A study was carried out to simultaneously measure driveability and exhaust emissions in a fleet of 10 European gasoline vehicles. The vehicles were all equipped with three-way catalysts and single or multi-point fuel injection. The test procedure and driving cycle used were based on the European Cold Weather Driveability test method.

An emissions programme has been undertaken to gain information on the effect of selected fuel parameters on gasoline direct injection (G-DI) vehicle technology(1) with respect to exhaust emissions. Seven fuel parameters, namely aromatic, methyl-tertiary-butyl ether (MTBE), sulphur and olefin content as well as 3 distillation parameters covering the whole boiling range, were independently investigated. It was found that, overall, the fuel effects on regulated (THC, CO, NOx), particulate (Pm), and CO2 emissions were relatively small.