I'm not sure what you saw. But like I said, it would depend entirely on the engine. On average though, you'd expect hydrogen to be better than a current cars range. Somewhere at least around 300+ miles. UPS runs it's fleet on propane, maybe they 'junkyard mechaniced' an old propane engine? I can pretty much gaurantee it wasn't a engine professionally set to run on hydrogen though.

Anyway, a true hydrogen designed engine, would be different than a air breathing gasoline engine. It would be similar to a propane engine. Look at forklifts designed for propane, but then subtract the exhaust. Hydrogen is going to need a new way of handling exhaust.