- It takes more energy to make hydrogen than what you get back out of it. You can't make this at home. But you can make electric power at home, for free.
- Hydrogen fuel necessitates a distribution network exactly the same as for petrol. This is why the oil crazies in the Bush regime pumped money into hydrogen and nothing into electric, even as electric cars worked and people loved them to death.
- Plus, it's unbelievably explosive - in concentrations between 2% to 98% it's explosive. So you either must have none or very close to 100% hydrogen for it not to explode. Now, when gasoline turns into a vapour and creeps along the ground then explode if lit you can get a 30 foot or more radius is vapour with corresponding explosion as the vapour ignites. And gasoline is a fairly heavy dense molecule compared to hydrogen which is the lightest molecule known, and since it's really a gas, unlike gasoline which will sit there as a liquid for days, hydrogen turns from a liquid to a gas in much less than one second. If you have a tank with 5 gallons of hydrogen and the tank is ruptured - and eventually this absolutely is going to happen one day - then the resultant break and explosion would very much on the order of what is definitely not conducive to human life. That is, you'll be ok unless that tank goes, then you're pretty much a goner, much more so than with gasoline.
Between the fact you have to buy it from the oil barons and can never make it your self for free and is the most explosive substance known, yeah, hydrogen is great. Not.
I think if we knew what we were doing we'd immediately stop anything to do with hydrogen cars and stick to electric. Keep in mind before the oil companies paid the car companies to stop making electrics, there were more electric cars than gas powered cars on the road in the early 1900s.