Hydrogen for cars is not… let’s just say it’s not great.
Granted: the cars drive very well (try it if you have the chance) and the fuel cells give them a serious range. However, distribution of fuel similar to regular gas is hard. Storage is dangerous, and pipelines continuously leak (H2 molecules are very small). Hydrogen gas cannot be mixed with stinky stuff that will warn you if the gas is leaking. It is much harder to keep under pressure than oil or regular natural gas. And last but not least: it is very inefficient to generate, the electricity used to generate it from (sea)water is significant and could have been used to charge batteries directly (note that it’s currently mostly distilled from natural gas, about 90% iirc). Mind you: I know it’s useful, just not for cars.