Stations dont mess with anything. Because of the high freezing point of straight E85 gas, gas stations receive deliveries of E70 in the winter, which has a much lower freezing point… ie - more gas, less ethonal.
I was tuned in the middle of winter when the gas stations run E70… so now that they are all running E85 I’m running pig-rich. Yeah ethonal is a little less regulated than gasoline, so just get a little more conservative tune than usual and you are fine.
STFU about gas mileage.