I have been running up to a 50% mix of E-85 in my 2002 Honda Civic. The vehicle is running normal, the mileage is a little less efficient but I am happy that at least I haven't needed to use an ethanol conversion kit.
One issue: The "Check Engine" light came on but went away after I went back to a complete gasoline tank. Dave Blume says it is because the car didn't know how to handle a non-toxic fuel combination.
Since the engine wasn't measuring the right level of "Toxic" gas, it thought something must be wrong with the engine, yet it turns out that the alcohol fuel was too clean for the engine!
Anyone else have this experience?