Son of 550! The Porsche 718!S

We're not sure, but the instance of the Porsche 718 has to be one of the last times a GP car was derived from a roadgoing vehicle. In this case, it was the 550 Spyder, which itself was born as a derivation of the 356 — which of course is the scion of the Beetle, only with a meth problem. In any event, the 718 didn't fare particularly well (cursed Enzo!), in competition, but it didn't exactly shame itself either. In the end, it took two cars to replace the 718 on the track — the badical 904 in the sports car arena and the 804, which competed in Porsche's final F1 effort in '62. Stick that in your 968 and smoke it, Pepe.

Porsche 718 [Wikipedia]

Related:
We May Never Taste Sheer Deliciousness Like This Again: The Porsche 907 [Internal]