As S and B said I think they are motorised, not actually clockwork
on the "Beetalls" in the link, they apper to be where the VW badge is / was,
so I guessed they were just STUCK / bolted into the skin of the bodywork,
I CAN see the point of driving it from the rear wiper motor/ gear..,
but in my mind it would look "wrong" that high up.. - poking through glass really
Charlie