Basically use the hydrogen as a battery using electrolysis. Refill at home or at a station by taking in H2 and O2 and giving back H_2O. Make it a closed system that simply takes rising ocean water out of the environment and otherwise is independent of the environment.

The car can convert the H2 and O2 into water and use the energy released to propel the car. We can also reuse energy absorbed by breaks and heat converters to create more H2 and O2 with electrolysis.

I don't really think this should be used to bail out GM, but we should fund and subsidize hydrogen cars.