There are basically two types of hydrogen powered cars, those that burn hydrogen in a combustion engine and those that use fuel cells to generate electricity which powers an electric motor.
There are an increasing number of hydrogen powered cars to choose from sports cars like the Shelby Cobra with a 351 engine that runs on hydrogen, the Nissan Frontier pickup powered by fuel cells and even a hydrogen Hummer.
There are two significant catches. First you will have noticed the lack of filling stations. Getting the hydrogen to power your car could currenlty be a problem. And the second is that it take energy to split water into hydrogen and oxygen most of the energy used to do this is currently produced from fossile fuels so hydrogen may not be as green as it first appears. Well, at least not until it's generated from renewable energy.