I guess you could call it 'detailing' but those cars are stripped down to component level after each race and rebuilt...
they are spotless, visually and mechanically...
watch a race on TV, they are always cleaning, wiping down, etc., those cars...
just saw a Lemans R8 Tdi today at a show, vry clean...the paint and so forth is dinged up from debris, but the car is spotless
sometimes when they 'retire' a car they will leave it as is for effect, ie, rubber streaks, bugs, etc.