Re: Hydrogen? Seriously?
If you have a tank of hydrogen which ruptures, you don't get an explosion. You need to mix the hydrogen with air. Actual tests have shown hydrogen fires rising more or less vertically.
If a petrol tank ruptures and the fuel spreads out and ignites, you'd better hope someone can lay a foam carpet if you want to escape alive.
There are reasons to doubt that hydrogen will ever work for cars, but this is not one of them.