Oh, they absolutely do. Pretty much every single sport has some form of sponsored features, and when you have a series where the sporting product are literally moving billboards, it's actually a far more seamless way to integrate those sponsorships.

Sponsorships that help offset the absolutely fucking ludicrous amount of money that networks are paying for the right to broadcast NASCAR (and other sports).

Hence why if you watch races prior to the 2001 TV deal (When NASCAR took over the TV negotiations for the whole series; prior to it was largely handled by the tracks with sanctioning body consultation) you almost never see it. (Although it was starting to creep in at ESPN in the last couple of years of the 90s - but it got dramatically worse when FOX and NBC took over)