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.