can't say, i "prefer" that everything running through my engine is gas, i don't even like the 10% ethanol. But i have to live with it.

BP and sunoco do great in my aveo. All our local gas comes from the same distribution hub, its just the "cocktail" of additives is varied depending on which companies gas it is. I guess its one of those additives (or even a higher abundance of ethanol?) that i feel the mileage slip away.. i dont know the chemical make ups, or the differences between companies otherwise. but that is my observation.