you forgot to include unicorn farts....LOL But you're right. Hydrogen may have possibilities, but it is not going to be free. The energy to convert it from other compounds has to come from somewhere (fossil fuels or nuclear). The percentage of free hydrogen in the atmosphere is 0.000055% so that is not exactly a legitimate source
Its simple enough to separate hydrogen from oxygen in water and its a common 6th grade science experiment. The problem for cars is that it takes a lot of energy to do it at the rates a car would need it on demand.
If hydrogen is called a fuel, why can't electricity also be thought of as a fuel? Seems a subtle concept but it's key to avoid falling into the trap of trying to violate the Second Law of Thermodynamics.