Trying too hard
What is going on here is that the consequences of trying to be too Green.
Hydrogen is apparently the ultimate Green fuel, but apart from being ultra low emission it has a very long list of major disadvantages. For a start, it is not energy dense, so you need to carry a lot of it and refuel frequently. It is difficult to store, so there are few hydrogen fuel stations out there, reducing the vehicle's utility still further. Hydrogen also explodes very readily, burns with a flame invisible to human eyes and isn't all that easy to make.
If the car makers had only tried a little less hard on the environmental front, then all manner of exciting things are possible. Ammonia is another, better candidate for a zero-carbon fuel. It can be made fairly easily, especially if you have access to electricity from a nuclear reactor, and can be contained in the same sort of technology as LPG is stored in. It can be burned in fairly conventional engines, in gas turbines and (with recently-developed catalytic systems) in conventional fuel cells.
Similarly LPG or methane are also good candidates for Green energy, as is pure ethanol. Once again, these sorts of fuels can be easily made, stored and used with conventional technology and systems, and don't require an absurd new car design to use them in.