I am with Snowy, so my answer's no.
I think Motorsport is too broad to have a pinnacle and it's a case of "horses for courses" too. While I watch as much motorsport as I can get away with it's F1 that I'm allowed to devote most TV time to so I feel I know it better, there are too many other forms of motorsport that are different and certain series/events are the pinnacle of those. T
he current "best" F1 driver may not be able ever to win a stage of the Dakar or a Nascar race. Has Carlos Sainz driven in the pinnacle of motorsport? He's certainly reached the top of two series that I have a deep interest in, and there are other truly great drivers who would be very uncomfortable if told that they hadn't reached the top because they hadn't driven in F1.
Good thread though, with some very lucid answers.