Red Flag 1:
If you're still digging, and still interested, here are some numbers behind The Reaper's point:
Heats of combustion for fuels
[Jargon alert!] Pretend for the moment that gasoline is just octane (not literally true, but close enough to make the point). Weight for weight, ethanol contains about 63% of the potential energy that gasoline does. Whereas octane is a hydrocarbon, you can think of ethanol as a hydrocarbon that's already been partly burned, with the energy given off before you had the chance to collect any of it.
Ethanol is denser than octane, so in a volume-for-volume comparison it does a little better, about 71% of the potential energy of octane.
On its own terms ethanol is a fine fuel, and if we had underground lakes of it ready to be extracted and burned, we'd accept the lower mpg with little complaint. But since it has to be made, we get into the other objection, about the energy you invest in making it.
Putting three times as much energy into it as you get out sounds high to me, but even optimistic estimates suggest that with a national-level infrastructure you could break even, but not by much. That's given current crops and technologies, which would need to improve for ethanol to be an attractive competitor to gasoline on that national level.