Of course, using something like switch grass which would produce a much
higher BTU and thus better MPGs won't happen
It does not matter what the feed stock is used the BTUs are about the same.
Methanol is 57,000 BTUS/Gal.
Ethanol is about 76,000 BTUs per gallon.
Gasoline is about 115,000 BTUs.
So you can see that both Methanol and Ethanol will give lower fuel mileage
than gasoline.
To properly burn alcohol the Fuel Air ratio needs to be increased to allow
more fuel to pass.