I notice some of the cars in today’s race seem to have a windshield wiper. If so, why? If not, what is it?
if they do have one it’s likely to clean the windshield of dirt or debris that can get kicked up by other cars.
On non-ovals they do in fact run in the rain if it’s not too severe.
Presumably for the same reason these touring cars have windscreen wipers:
NASCAR in the rain with wipers running: