I dont know how accurate the DUST TO DUST study was that is being picked at, but I think what we're eventually going to find out is that like the whole "biofuels" bruha, this is sound and fury over nothing that would "save the Planet" and other handy sloganeering.
AS you might know biofuels made from methonol or ethanol (or biodeisel from soy) were also touted as saving energy, and to boot the carbon emitted was a wash since much carbon uptake was done in the growing of the plants themselves. We know now this is pure myth. The factors left out like production and transport costs of shipment of corn and beans is high, as is the fact of hiking the price of food. AS one chemist said, the most efficient use of corn and beans is to eat it or feed it to animals. That being said also left out, all else being even, is that it is odd principle to burn a large fraction of food supply to power cars with an energy output that pales next to good old gasoline. Then too the creation of NEW farmland demands and intensity of fertilizer and (especially in more sensitive areas like South America) clearing of rain forests and poor soil zones to make room for sugarcane and beans, etc. This is hardly a wash on carbon uptake, if that's your concern.
As to the Prius itself, I can't drive something that looks like a pregnant roller blade.
