A silly option but some videos outlined shapes with glowing lines for illustration purposes. What about LED glow strips as an option; since any aftermarket product would mess with the skin this would have to be new car option. Some people put those LED strips on the bottom edge or under the car; in this case they could be at glued in with the solar cells without much trouble... but maybe it wouldn't be too difficult to put in some more of them; purely for looks. Although, it would make it more visible on the road at night.
It was your idea in one of your videos; for illustration. maybe it could be an option to for real. Something to poll people perhaps?