And there's this neat bridge in New York ....
This is kind of stupid. All that extra weight, expense and complexity, and it likely won't take your driving costs down very much. Might as well get a Toyota or Honda hybrid and save gas that way.
However, a purpose-built hydrogen car could save you loads of money. And, yes, you can recharge at home because you can produce hydrogen from water from your wall outlet -- but I wouldn't put the generator in an enclosed space unless you want an oxygen fire. Setups like this don't give you free gas, they're simply making your home electricity portable in an efficient manner. Gas bill goes to zero, electricity bill goes up a bit.