I used to keep a record of my (cars) MPG. I found the mileage was affected in direct proportion to the amount of ethanol.
This was in a few different vehicles. E-10 would result in a 10% drop in MPG.
Ethanol does give less mileage than gas. It also will attack and eat through any rubber or aluminum in your fuel system. Another thing is it will wash down your cylinder walls, starving your pistons and piston rings of lubricant. Because of that it will also degrade the crankcase oil. The higher the ethanol percentage, the quicker it will eat your engine.
This move by Biteme gels well with his idiotic “too bad, just go buy an electric vehicle”