I know I've posted this in several places, but reading more of it today, it breaks down emission per mile, so most likely best MPG has the lowest emissions per mile. But it isn't E0, E15 might not hurt all of our MPG's. E20 peaked in some E30 others. Well worth book marking.
http://www.rhapsodyingreen.com/rhaps...evel_study.pdf
One of the place we do a little structual engineering for, a rendering plant, but was bought out by a bio diesel manufactor to they could get the fat. Nasty place, but better than burying the carcusses.