This paper presents the progress in the introduction of fuels of higher content of ethanol and vehicle models adapted for fuelling with this type of fuels (FFV). Trends in the European legislation related to the standards of spark ignition engines exhaust emissions have been discussed. The results of a study of unleaded gasoline E10 proneness to forming deposits on the test engine intake valves in accordance with CEC F-20-98 test procedure have been presented. The paper also presents the results of a study of ethanol E85 proneness to forming deposits on the elements of the engine intake system when it contained inappropriate detergent additives.