My first ever car was a wee Toyota glanza and I had it mapped on v-power and I would always fill up on v-power. One day I was driving by Tesco and decided to give momentum a try. Not a word of a lie the car drove like a bag of @*!# and actually cut out on me in my housing estate. Went back to shell and brimmed the tank with v-power and it was fine from then on. Always used v-power since and woulnt dare putting supermarket fuel in my zed.