I believe all Hydrogen vehicles are using proton exchange membranes still, which have roughly 40-50% efficiency.
And that's before you take into account that even the most cutting edge hydrogen refining processes are around 70% efficient.
So 1kWh of energy input (electricity) will net you 3X the motive power when used directly in a BEV than first being coverted to hydrogen, and then converted back into electricity.[1]
I don't think any hydrogen vehicle in actual use has a fuel cell (and if there's any, it's an incredibly rare exception). They are all internal combustion engines.
Proton exchange membranes are very unreliable and expensive. They are also not power-dense, one that powers a bus will be very large.
It‘s actually the opposite: some hydrogen cars that use combustion exist, but they are really, really rare. Almost all hydrogen cars that are road legal use a fuel cell in combination with BEV parts to smooth out/extend power delivery.
