Arnold's Hydrogen Hummer

Forbes does a report on Forbes.com: Arnold's Hydrogen Hummer:

The H2H uses a conventional internal combustion engine powered by compressed hydrogen, even though GM's plans for its future model range involve hydrogen cars powered by energy sources called 'fuel-cell stacks.' Supposing for the sake of argument that Schwarzenegger wanted to drive the H2H around California ('I don't think that's a common occurrence,' said the Hummer spokesperson), he could refuel the car at several stations.

The majority of California's 12 to 15 hydrogen refueling stations are in the southern part of the state, although Schwarzenegger could--for example--refuel the H2H at the University of California, Davis' station if he didn't stray too far from Sacramento. Hydrogen currently costs $4 to $10 per kilogram, the unit in which it is measured, and the H2H's fuel tank holds five to six kg of hydrogen. GM believes that if hydrogen is to be commercially viable it must cost $2 to $2.25 per kg--that is, it must be competitive with gasoline prices.

From the data I have seen, the cost of delivered hydrogen (i.e. when it is ready to be put in to your vehicle at no tax) is currently estimated at about 14-40$/GigaJoule of energy or $1.68 to 4.8 per kg at the lower heating value (LHV), with the higher cost number being more likely than the lower once. In general, this cost needs to halved if Hydrogen is to make sense. Not impossible, but not at all trivial or guaranteed.