I'm glad that alternative fuel vehicles are now starting to appear, but I really don't see that locally refuelled Hydrogen cars are the answer. These are basically electric cars with an on-board power station, whose fuel evaporates into the atmosphere if not used quickly.
Rather than build an expensive network of hydrogen filling stations, which will be stocked by thousands of hydrogen-carrying road tankers, why not build larger, more efficient energy converters in the form of Hydrogen-fuelled power stations, and distribute the power through an existing network, i.e. the national grid.
This would keep Hydrogen away from the general population and from terrorists, and avoid the issue which receives little attention - that of water (the exhaust) being spread across our roads. Not good in a cold climate!
The inefficiencies of distributing and storing the power on-board in batteries would surely be offset by the greater efficiency of a central energy converter. However, if we really do want to have a 'distributed power generation system', then why not have nuclear-powered cars?