I think the p6 shape has a lot of post production life left in it for shape development and judging by the numerous articles and images of redefined shapes a lot of other people do to, its just something about the original shape that inspires you make it even better.
there are few similar design genealogies out there which incorporate the styling que's of the p6 apart from the French Citroen similarity and a few less well known marques.
But then again maybe it's just a 70's thing or an art deco era, something that is so different from the day to day norms of post industrial western culture that people just desire that difference.
Would be good to see more images like that here just so it can inspire more creative developments.
Graeme