This is new to you? Thats sad. This idea has been around for ages. Hydrogen would be GREAT to put in our cars! The exhaust is water too, how sweet is that? The problem is that hydrogen is so incredibly small it leaks out of almost any container...and Hydrogen is incredibly combustable..so if it leaks, bang.
Also the tanks aren't very big, you can't get alot out of them. And how would you refill hydrogen? You would need stations, and not very far apart, no far distances. Hydrogen is a long way off, there is a lot of things they have to improve and work out first.