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The EPEFE programme endeavoured to advance the scientific understanding of the individual and joint effects of both fuels and vehicles/engines on emissions. Testing protocols were developed to allow the effects of these changes to be estimated accurately and without bias. Pioneering testing practices such as specific vehicle/engine conditioning protocols were also developed. The use of these protocols enabled excellent repeatability and consistency to be achieved across the eighteen participating laboratories. The measurement data were reported for subsequent statistical analysis on a specifically developed spreadsheet format for easier and safer data handling. The protocols now form the basis of good testing practice in Europe.

Within EPEFE the relationship between exhaust emissions of five 1996 heavy duty engines including advanced technologies and an eleven diesel fuel matrix has been investigated. The fuel matrix was designed to study the effects of decorrelated fuel properties (density, polyaromatics, cetane number, back-end volatility (T95)). The main programme consisted of engine testing on the 88/77 EEC test cycle at standard engine settings. The findings were quantified using regression equations and showed, that fuel effects varied in both magnitude and direction between the four emission components. Individual engines had different emission levels and responded differently to fuel properties, due to engine technology. Additional tests were conducted with selected fuels at adjusted engine settings and timing. The observed density effect on emissions can be compensated for and fully explained by physical interactions with the injection system.