Has anyone checked gas mileage (MPG) in the identical vehicle using an ethanol blended gasoline in one fill-up, and then pure (non-ethanol) gas in other fill-ups? All the gas pumps in my state have an ethanol blend, so I don't have a chance to compare with pure gasoline. I've had people tell me that pure gas delivers measurably better MPG ... better by 10% or more. Has anyone checked one gas against the other in the same car? Results? MrBear