Now come on Lu... this sounds like the magic water-powered car one reads about on some forums. In order to do any useful work a motor has to get energy from somewhere.
Moreover I hoped you might be able to chip in with a bit of the engineering knowledge, such as the weights of components I mentioned. Any chance? Then we can know how much weight we've got to play with!
Cran: I'm not aiming to develop a hybrid, where electric motors are used purely for transmission. We have hybrid cars nowadays - to my mind they are horribly over-engineered.
I'm hoping someone with knowledge of battery systems can throw in some numbers as well. I've read that Li-ion batteries store about 120 watt/hours per kg, for starters...
Benet