Car makers will want to sell cars. Car makers will better be able to sell their cars if they are attractive. It won't take long for them to integrate solar cells, modify the shapes into aesthetically pleasing and compete on selling these types of cars.

I like hydrogen on demand approach. Still very much a traditional internal combustion machine. Of course if you can produce cheap, plentiful, non-pollution producing fuel, then who knows? Maybe the Wenkel engine will make a come back.