Ethanol lowers MPGs. In a comparative sense, the more fuel that passes through an engine per x distance, the more accelerated the wear per mile. How discernible is this accelerated wear factor? Couldn't tell ya, since it would be near impossible to run a comparison study in the real world.
Aside from lowering our MPGs, and thus raising the amount of fuel taxes to the revenuers as a result of this increased fuel usage, ethanol makes for a right dandy political tool for Bush to use against Chavez*. The EPA even has doubts about the health aspects of ethanol. Pardon my acute cynicism, but bio fuels are by and large, a further exercise in politicians stroking corporate wants & needs grab a--. The numbers don't work for bio fuels, but as you well know, little issues like economic viability and common sense never stopped us before. There are a number of other means to get to the end of "Please Lord, create a miracle that weans us off Persian Gulf oil" but corn squeezins ain't one of 'em.
{*Bush is going to pay a few gazillion to all of Venezuala's neighbors to produce alcohol as a motor fuel, EXCEPT for, you guessed it, Venezuela.}
