Since the Apollo program - one would think something would have improved by now. About ten years ago Ford had a 75 amp fuel-cell Taurus prototype. I wonder what happened to it.
There is also an infrastructure problem. Where are you going to get hyrdrogen for your fuel cell vehicle? If you can't buy it except in limited places, you are stuck with a vehicle of limited range and thus no sales. If there are no customers for hydrogen, nobody will add it to their gas station inventory.
Natural gas has the same problem. It works only since the engine conversion is easy, and fleet vehicles can be serviced at the fleet depot every night.
The other major problem is Making hyrdrogen. It's very expensive. Iceland does it using geothermal electricity, ie it's free other than the capital cost of the power plant.