You'll never see a nuclear car, because the same greenies who want to not drill for oil are scared of the cleanest energy source we have. Not only that, but I'm sure if we did have a nuclear car, a terrorist would find a way to turn it into a suicide bomb.
Now, please turn your attention back to the matter at hand, a replacement for oil based gasoline, and leave the larger matter behind. Ethanol is the most efficient alternative we have right now.
Michael, a couple of points. First, if ethanol production actually consumes more energy than it provides, does it really matter how efficient it is relative to other alternative fuels. Is being the alternative fuel that wastes the least amount of energy really something to brag about? Second, the use of nuclear power to meet some transportation needs would not require nuclear reactors in our vehicles. We already have vehicles that are totally (not hybrid) electric - as in, you plug them in, charge them, and drive them (not very far, but they have a lot more range than they did a few years ago). If we were to move in that direction, with additional nuclear capacity for our production of electricity, there would be the potential to reduce our demand for oil. Add to that the fact that a good deal of our electicity is still generated from oil, and the case for nuclear looks even better.