Walking the blurry line of politics and science, I'd like to offer at least a minor defense of ethanol. In the nineties, the EPA started requiring that an oxygenate be added to gas to reduce O3 & CO emissions (smog?). Maine, where I'm from originally, chose MTBE as an oxygenate to meet the rule. NY, where I live now, used E10 to meet the rules. When driving between the two, mileage dropped noticeably when running the MTBE. As an added bonus to the decreased mileage, the MTBE leaks out and poisons water supplies. The ethanol was a big improvement as an oxygenate, but this is much different than fueling cars entirely on ethanol.

Secondly, ethanol can be compressed further than gasoline without knock. If one were building high-boost or high-compression engines that utilized this property, the increased thermodynamic efficiency "might" offset the extra energy required to manufacture ethanol. Again..."might."

On the other hand, I still can't see the logic in converting oil (fuel) into corn into fuel. ...Especially when all our corn fields will soon have to change over to soy beans for export to China.