You know one of the reasons why they won't allow hydrogen powered cars is because they're afraid of people tampering with it and creating a speeding weapon.
Imagine, rush hour on a hot NYC day. You're in the middle of 125th street, scare for your safety as it is. All of a sudden in your left mirror you see someone in a Ford Mustang going about 90 mph. You have no place to go. You're 30 cars from the front, as far as you can see, and at least 15 from the back. You could run. Yes you run. But BAM! The Mustang hits the car in the back. That tampered fuel cell car goes off, within split seconds all the cars within the blast radius go off. Those within their blast radius goes off. The blast radius goes over the Brooklyn Bridge, over the Verrazano Bridge, the Lincoln Tunnel, everything just going and going and going. It goes into Yonkers, it goes into Newark, it rips right into New Jersey, to Trenton, into Philidelphia, it moves down and hits Maryland, west into Cleveland, Detroit, it's just bad all over.
That is why we don't have fuel celled cars. We could make them as safe as possible but if some terrorist wanted to tamper with it he could.