...but not on E85.
I had to go to Tulsa on business, and because of the hurricane, there was literally only one rental car left, a Lincoln Town Car.
Lo and behold, it had a yellow gas cap indicating that it was a flex fuel vehicle.
Sadly, I couldn't find an E85 station in Tulsa, and the car had a full tank anyway.
But if you're in the market for a FFV, maybe a used Towncar is the way to go. There aren't that many FFV cars, they're mostly SUVs.