Every car must display a coloured disc 10cm in diameter as follows, depicting which class their vehicle belongs to:
Blue – Classes 1 & 2
White – Classes 3, 4 and 5
Yellow – Classes 6, & 7
Red – Class 8
In the centre of the disc should be displayed the class number using a motorcycle number plate sized numeral. On vehicles with full height windscreens the sticker should be centrally mounted at the top of the screen in that area where the forward vision is already obscured by the rear view mirror. On vehicles with a small or no windscreen, the sticker should be mounted on a flat vertical surface approximate to the competition number. If this results in the sticker being mounted on a background of a similar colour to itself, then the sticker must be mounted on a white rectangle measuring 155mm x 105mm (the size of a standard competition number).
Discs are generally supplied by the organisers, class numbers must be supplied by the competitor.