In a vehicle demonstration programme the high compression lean burn technology showed good potential for further improving emissions and energy effiency of the average European car. At the US ‘83 emission control level a 10 per cent improvement in fuel consumption over the equivalent presentday vehicle was found under European city and highway driving conditions. An oxidation catalyst was found an essential and effective element of the set-up.Special attention should be paid to the representation of actual driving patterns in Europe in relation to the type approval test procedures. Especially for control of NOx emissions the situation is very unsatisfactory. Suggestions for improvement are made.