Why aren't we using hydrogen fuel cell vehicles?
A hydrogen fuel cell is new technology. As with any new technology, the availability is low as is the availability of the accessories necessary for it. In the case of the hydrogen fuel cell it is the required hydrogen fueling stations. There are only a few dozen in the whole of North America. The cost for each hydrogen refueling station is about $2 million. So in order to get a good network you are looking at a huge investment.
Additionally, the cost of the fuel cell itself is higher than an electric car. At this point in time it seems that electric hybrid cars will be the car of choice for people not wanting gasoline engines.