Fastest car I've ever driven was probably this '87 N/A 944 I was looking at 3 or 4 years ago... the engine had been thoroughly massaged. I never really opened it up, so I can't give you a number.
Fastest car I've ever ridden in was probably my uncle's '66 427/435 Stingray convertible that he bought new when I was in high school. He never really opened it up when I was in it, so I can't give you a number.
