I think you'd do better by covering all the exposed surfaces with solar cells to gererate your extra power. They wouldn't add that much mass and could be accounted for in other areas. As well, instead of alternators on the wheels, adding flywheels that would act as brakes (when you DO decide you want to stop) to capture the engery of the spinning wheels and convert that motion into electricity. Combine this with a high temperature, ceramic, hydrogen burning engine, and there would be virually no pollution from this vehicle, not counting the pollution from its manufacture.
I read about a man from the southern US that had a car which theoretically ran off of water. He filled his "gas tank" with water, had battery packs and solar cells to electrolize the water into H and O2. They were then both pumped into two different cylinders and mixed and burned in a regular engine. It took a few days to get enough fuel and it would only run for a few minutes until it ran out. Not very efficient if you ask me, but a hell-of-an idea.