I do not know ethanol well. I do know that there is a lower energy density and that there is a loss of fuel economy as a result, and I think for low-level blends you would just have to look at the particular chemistry. Biodiesel in its pure form has less energy density, but it has other properties that more than make up for that. So at the low-level blends that we are looking at for renewable fuel standard, there is no difference in fuel economy whatsoever.
On February 25th, 2008. See this statement in context.