my friend owns a shop here in town called "mikasa performance" and he specialized in Volkswagens and Volkswagen diesels. he stocks both the Redline and stanadyne brands. I usually run about 1/3 of the bottle of redline on each fillup. now keep in mind I only see that much gain in mileage if my entire tank is highway driven. for in town I use it because the engine just seems to run happier and its not poppin and fartin or anything.

The Redline stuff costs about $9.00 a bottle and the Stanadyne is about $12.00 a bottle. on average in town I usually get about 700km/tank. its alot worse since its winter and theres quite a bit of idling time. im hoping to get over 800km/tank in the summer for in town driving