For some reason I can't see 100HP 500s achieving classic status though, unlike the Panda 100HP which could well become sought after future cheap classic.
No, me neither - I think ten years from now, folks will be breaking up 1.4 500's to keep 100HP Pandas on the road.
Within the 500 range, the NA 1.4 occupies a relatively lowly place (sorry Ahmett). I'd say it's the esoteric A500SS variants which have the best chance of making it into a long retirement, whereas the 100HP sits at the top of its branch of the Panda family tree and its place in history is firmly reserved.