So, I got my hands on that hydrogen toy car I was wittering about last month. It's quite good. It works and everyone I've shown it to is fascinated by the thing. My only gripe is longevity: it's probably not going to have the staying power of, say, a chemistry set. But what do I know? Let your kids decide. It's £60 from IWOOT. Anyone else played with it? Thoughts on a comment, please.