Just imagine the rust problems with a car emitting so much water. Or even higher cost to use composite and other rustproof materials.
Water power is a joke because even where there are large damns producing it, that cannot supply enough power for even the cars in that production region. It's like saying a fart powered car is viable because a fart has a tiny bit of fuel potential but there (thankfully) aren't enough farts to go around.
Yes we should use solar and wind when feasible, as an ideal at least. The problem is practicality, that there is a finite budget with which we have to produce all power needed and developing several lower yield sources of power is a better project down the road, after we had already developed a better infrastructure for nuclear, and for more economical use of power. Right now for example, the average US household with someone home is consuming at least a few hundred watts. Is it our entitlement to this? Or is it something we are doing only until we run out of fuel reserves? It would have to be the latter, as the population is still growing and ultimately people and farmland take up the space till there is not enough room for a sufficient amount of power producing equipment even if all solar wind geothermal nuclear etc etc is used as much as possible.
The answer is a new transportation system that does not have individuals driving cars, that everyone who needs to be mobile will have to live along a track for this public system or else generate their own power on-site for a personal electric vehicle, only being able to travel as much as their personal property (geographical) resources allow - not being sold power at all beyond an allotment for essential services, like minimal lighting, cooling, refrigeration, low power entertainment, communication.