I don't know who it was but it was an ESPN special on a young NASCAR driver that was visually in incredible shape. However he pretty much lives on the Atkins diet...I wouldn't call that healthy. I'm sure most of them are hard core middle america meat eaters as well...meaning they eat more meat than the normal american that eats too much already. A heck of a lot of them are alcoholics too judging by somewhat regular incidents with the law...a far cry from taking care of themselves. As for the crewmembers you're correct...they need to be fast and pretty strong...unlike the drivers. However they don't really need any endurance at all...its sort of like being a designated hitter in baseball.
I'll have to give ya the last word on this since I didn't read the initial post excluding motorsports.
I'm still a newbie and will have more to learn than to teach for quite awhile I suspect. So I don't need to hijack threads yet.