FWIW I had a 2005 Explorer that would burn E-85 or regular gas. There was a drop in mileage with the E-85. I found that E-85 had to be at least 30 cents a gallon cheaper than regular gas for it to be cost effective.
That sounds about right Bill. I have a friend that blends half E85 and half E10 in an Escalade and swears he gets no mileage penalty with the blend. He claims a slight mileage penalty with E10, a big penalty for E85 (which should be expected) but none for the intermediate blend. This is a non-flex vehicle. For some reason he thinks there is a sweet spot with that engine where the computer cqan take advantage of the higher octane that offsets the lower BTU of the alcohol. Dunno. He is not even a corn farmer so no reason to promote it. But whenever he is around E85 he tank blends. Been doing it for at least 5 years. Think the truck is around 200k miles. Illegal, but he speeds all the time anyway so legality is not a big stumbling block for him.
