Barman (Barry Bosman) once developed this prototype for a Technic car, based on the same principle as proposed by Audi RSQ [1, 2] (the car for the sci-fi movie I, Robot). Spheres instead of wheels, was the innovation then proposed by Audi and here by Barry.
The prototype used LEGO 51mm balls (those included with the NXT 1.0 kit for instance) for wheels, but it never worked as good as Barry intended. Thus the project was canceled and never finished.
However you can still find some additional photos from this proof of concept, at Barry's BS folder.
I don't know exactly what was wrong, as from the video, the model seems to work pretty well!
Maybe it was not following exactly the driving instructions being sent through the remote.
The prototype weight and balls friction, seems to be in the origin of the problem.
But anyway, Barry indicated another tentative developed much later by MrAliencat, to accomplish the same idea.
This another version got its weight reduced, as a measure to improve the performance.
It looked a really nice idea, if it worked good enough to support the weight from a complete and finished car model.