linky no worky, but this is pretty common. The down-side is that with ethanol, you have to tune your car to run very rich, as ethanol burns in about a 6:1 ratio with (approx) and gas burns 14:1. If you really want to make a replacement for gasoline, research fermenting Butanol. Butanol is much heavier than ethanol and burns in a ratio close enough to gasoline that no engine re-working is needed. There is a new fermentation process that yields just as much butanol as ethanol per pound of bio-mass feedstock, but i am not exactly sure what the process entails. In that same process, hydrogen is also released in capturable quantities, so that can be burned to run the still used in alcohol production.
ethanol has a lower amount of energy per gallon (ethanol contains 77815 btu/gal while gasoline contains 114132 btu/gal). This means you have to burn more gallons of ethanol to generate the same amount of energy (heat) as gasoline. Butanol has an energy content very close to gasoline (110 kbtu/gal IIRC), so it can be used in gas-powered engines with very little modification. I've been doing ongoing research on butanol as a fuel, and it seems that the only downsides so far are that butanol has a foul smell (and gasoline doesn't?) and some of the after-productions of butanol production are highly toxic.