You forgot safety.
Hydrogen poses some serious dangers as it is odorless and colorless if it leaks. It is very easy to ignite and it is explosive at a wide range of mixtures with oxygen. [0]
An hydrogen leak in an underground parking garage will be a very dangerous situation.
Obviously any dense concentration of energy will be dangerous. The gasoline in a traditional car is also highly flammable (though less likely to be explosive), and lithium reactions also also very hard to extinguish. But with both gasoline and lithium fire, you have some time to get yourself to a safe distance, with hydrogen... not so much.