A woman who would be deemed unacceptable in regular society due to her figure or scantily clad clothing is deemed hott while inside the confinements of NASCAR. Thus being deemed, race hot.
"Women wearing outfits that would be deemed illegal in 27 of the 50 states in America. Normal society would turn their heads at the women wearing these outfits . . . because it didn’t matter if they were 105 lbs or 280 lbs, the dress was all the same and it was beautiful." It was race hot!
--NASCAR 101: How to Mullet Hunt and Survive