"While it is debatable whether using corn for cars really works, there is less corn available to eat."

A recent TV doco here in Oz pointed out that the mash left from the fermenter is suitable for feeding to livestock, so 2 lots of output CAN be got from it. The problem with that though is that the grain cannot be eaten directly, and the 'multiplication factor' for eating the meat involves several times the energy input for eating the grain directly.