Again, back to the o2 sensors... It doesn't matter what the ethanol percentage is between 0 and 10%, the car will run fine so what does it matter? All fuel will have some percentage of ethanol in it, some more than others. How would you know otherwise? It won't matter soon, the minimum will be 10% then slowly get higher as the price of dino fuel goes up.
If a car has been designed for 10% ethanol use, then it is fine for more percentage imo, as long as it's tuned for it. Ethanol isn't corrosive in late model cars from my extensive testing, no more than petrol anyway.
If you saw how clean my engine internals were when I pulled it down, you would be fapping too.