The Department has not conducted its own testing on the effectiveness of fuel additives. However, there is a substantial amount of evidence demonstrating the benefits of detergent additives. These reduce build-up of deposits within the fuel system, fuel injectors and cylinders and are effective at reducing deterioration in fuel economy over time. A 1995 automotive and fuel industry review suggested that use of detergent additives delivered fuel economy benefits of around 2 per cent. for diesel vehicles and 4 per cent. for petrol vehicles.
Practically all UK road fuel contains detergents, with some companies offering speciality fuels with particularly high doses of detergent additives marketed on their engine protection, power and fuel economy benefits.
Fewer data are available on other types of fuel additives.