This paper presents the results of a gasoline reformulation project carried out in Finland during 1991. The target was to evaluate MTBE and ETBE as gasoline components with respect to operability and exhaust emission performance. The oxygenated fuels contained 2 to 2.7 per cent oxygen by weight.The oxygenated fuels reduced exhaust emissions significantly at normal ambient temperature. For non-catalyst cars the reduction of CO was 15 to 30 % and the reduction of HC was approx. 5 %. For three way catalyst (TWC) cars the CO emission decrease varied from 0 to 10 % and HC approx. 10 %. The use of oxygenates reduced exhaust emissions also at low ambient temperature, but not as much as at normal temperature. Cold starting was quicker and cold driveability was better when oxygenated fuels were used.