Originally Posted by PratoN
You're killing me.
EDIT: I think everyone really should shop around, though. I've found a Thornton's station in Illinois nets me 38-39mpg per tank on 93 and then I fill up at the BP and my gas mileage instantly drops to 33mpg. It's happened more than once and I think it's more than just a coincidence / weather / driving style changes.
For consistancy's sake I've not been "shopping around" too much, but I'm not sure if that is helping or hurting in this case. The one tank of shell v-power I ran following many from the local BP didn't seem to net any positve reaction either. Either the regular fuel is actually always 93 octane (which would cost too much), the 93 octane isn't really 93 octane, or the computer is so sophisticated that it can tune out the differences and gain nor lose efficiency in the process?
Car has 8700+ miles now afaik. Original testing was done between 0-4200+ miles. Latest tests were these last few tanks.