content: There's a Ted talk on this. For every mile you'd drive, if you were to use corn as the fuel stock for creating biodiesel, you'd have to have it he 8 miles wide.  I.e. It takes 8 sq miles of corn to push a car one mile. In all honesty, the future will probably lie with nuclear reactors and some variant of the fisher tropsch reaction.  Either that or someone will crack the genetic code to make bacteria poop out methane/propane at cost effective means.