I have just spoken to my local motor factor and he was telling me all about Terraclean. Apparently it is not a thing you just add to the petrol. They plug in a seperate fuel supply with the terraclean in it. They then run the car and this stuff then cleans the engine. The chap was telling me about a Range Rover which had its mpg go from 12 to 18 mpg just after the treatment. However, its about £150 a go. I might do some more research. However, I am just waiting for her to cool down before fitting the new plugs.
