If you look closely at the side of the car where it looks like an 88 next to the actual number. Those are a set of LED lights that allow fans to see where the car is as far as what current position the driver holds. So if he is 3rd it will light up a 3 next to his number. Sometimes it wasn't working right showing us a 33 or a 44 instead.

Taken at the 2014 USCR Prototype and Continental tire series race at Kansas Speedway.