Pardon me for hijacking this thread...
Thanks for sharing the link, Philippe! I have wondered who was behind the recreation of the 640, and their photo story about the recreation is really interesting! i never realised before that this car had a flat underbody! It was definitely years ahead in this respect. It's funny to see that the front page of the paper with (down?) force calculations, that the designer had anticipated the car to have a rear wing of the type then used on F1 cars. The exhaust system is also magnificent:
Unfortunately, the car isn't displayed well on the museum, where all the details are well hidden under the body and the car is in a corner, so you can only admire it from the front: