How about ethanol. According to this:
How Much Energy Does It Take to Make a Gallon of Ethanol?
(sorry, I haven't made enough posts to post that as a link)
There is only a 38% energy gain from ethanol.
Then look at it from a CO2 stand point:
so for 1 gal of E .72gal of petroleum are used, some is in fertilizer, which is not burned, so let's say .65gal.
To make sugar into ethanol it ferments, which makes CO2. About 80% as much CO2 as it makes ethanol (by weight).
Then you burn the ethanol in your car, dose this make any sense? It wouldn't be at all economical if corn wasn't subsidized.
Okay I'm done ranting,
I just want a turbine drive nuclear powered car, just have to change the fuel rods every 70 years, or 10million miles (which ever come first)