At the moment, BP are running an advertising campaign on British TV for BP Ultimate petrol and I know that all the "Big Brand" companies make some kind of super-clean-whizzy-go-juice, Esso Synergy Plus, Shell Optimax, etc.  This is usually 97 octane as against the more normal 95 and seems to have some kind of engine cleaning magic built in....It could be Cyllit Bang, for all I know! Anyway, with the Aygo being a three cylinder and falling into the zero tax band for emissions (If you owned i