Now I'm no scientiest, but considering that water vapor is a green-house gas, wouldn't water-powered cars be just as bad? Water-vapor absorbs more heat than CO2. And honestly, people are already fighting over water to drink. I personally, don't care to start fighting over water to fuel my car. I'm not sure of the logistics of this water-powered car, but I would put some serious consideration on it before jumping in... just my feeling.