Ethanol has a much lower energy content than gasoline (~115k BTU/lb for gasoline vs ~70k BTU/lb for ethanol). So ethanol will always hurt your fuel economy.
That being said, you can make more power on ethanol (~105-110 octane), but you need to at least tune for it and ideally build (higher compression) for it and you will likely flow 30% more fuel to make equal power.
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