The biofuel footprint.
 

After reading the pick your poison thread. I have changed my prospective on ethanol and biodiesel. Sounds like most of the poluting is done before the gas ever gets to the car with petro based fuels.
The path from oil seeds and biomass to the pump is relatively short. Distilleries are being built close to where they are needed and the byproducts used as high protein feed. They have not been blocked by the public like the petro-oil refineries.