Once they bring out efficient solar panels to the market, this will be an even better car. Even with current solar panels, some customers can run a surplus that they would normally store or send back to the grid. With an electric car, that surplus would easily be, essentially, free fuel (well, aside from the cost of panels and their installation).

In the meantime, Fisker Karma is coming out, albeit it is considerably more money than the Model S. But it promises to have a gasoline engine, which makes it more usable for longer trips.