Great. Now let's hope the American car companies are still around in a few years do the same thing. Detroit...learn a lesson here. Innovation creates market share. That is a very simple business tactic that should have been taught to you in college.

Now in SI units: Well, in urban operation you may well have 75 Wh per km, that gives you more range with solar (may be 2m²*0,5kW*4hrs*0,25=1kWh/75Wh=13km) - but the small vehicle should flip out more solar cells to be viable or position itself allways optimally in the sun. This introduces a new term "solar mover" fleeing shadow ;-)

The on-car solar cells are, for now, largely to "top off" the batteries and extend the range. The batteries are primarily charged by larger panels at home (or the plant, as the case may be). If the cells are large enough, you may also be able to park in the sun at work and get enough power to drive home, but you'll probably still need some power from external charging.

Solar cells powerful enough to directly drive the engine (with some extra energy to charge batteries for shady areas) are still a ways off, but that's where they're headed. Obviously, there will need to be an alternate charging method for rainy days, probably plugging it into a standard 120v outlet, but this is a valid alternate energy vehicle idea.

The key, however, will be keeping it affordable as a production model. Will Toyota be able to make these for under $30,000? Preferably under $20,000? If so, I'm all for it. Everyone will buy the free-energy cars, and it will drive Detroit out of business, despite Washington's efforts to prop them up. If it's just a concept and only affordable for the rich, it's a waste of time, other than as a scientific proof-of-concept.

At least somebody is thinking of the future. While any solar powered vehicle would have to be light in weight, there is nothing to say that the solar cells couldn't be used to charge up the batteries to some extent. At least this will help reduce the green house gas foot-print what-ever the energy source.