Yes it sure is. It is also very inefficient with the best precious metal catalyst based membranes reaching less than 70% efficiency. To add more insults to this terrible idea the fuel it uses must be unbelievably pure or else you get to junk your very expensive car.
This is a critique of natural gas derived hydrogen. It's also an argument for specific use cases where hydrogen is optimal and for using renewable energy to catalyze hydrogen creation. It's actually a pro-hydrogen article IMO.