Or really, motorsport as a whole, with the exception of rally and point-to-point offroad racing.
I think a lot of it is that for me, the real appeal of racing is the machines, not the drivers. So series like NASCAR or F1, where rules and regulations have more or less homogenized the field, there's not much to go on. If some team does come up with a really innovative solution and starts to dominate, they're quickly legislated back into the morass. See: Chapparal, Mazda.
But taking a massive 8x8 Tatra and racing it across the desert? That's pretty fucking awesome.
*I don't mean to imply that there's anything wrong with or inferior about F1 or other series, they're just not for me, and I wonder if that makes me unusual 'round these parts.