What I see, on cars that have not been run since before the Ethanol Mandate is that the ethanol strips whatever residue that has been happily accumulating on the insides of the fuel system. Instant plugs, arteriosclerosis of the fuel system. Carbs are clogged, fuel pumps won't... Arrrrgggghhhh!!!! Also, some old British bikes have fiberglass fuel tanks, and it melts those.... Gee thanks. Evidently the environment is improved by Nortons and BSAs going up in flames... Who Knew? I agree with the fuel milage thing too. My Audi is frugal with steady state highway driving. I used to get 33-34 MPG, now I am lucky to break 30. And I worry about the ethanol mess clogging up the CISstuff. Metering units ain't cheap. or readily available either.