In keeping with the style of many show vehicles and motorbikes, the owners tend to choose number plates that are current fashion for the era that the car was manufactured.  These show cars are not driven on the road, and are not owned for cruising, but owned for showman purposes only.  These drivers tend to choose the black and silver pressed metal plates that showcase the car in it’s best light.  However, some show owners choose to stick with a different theme or color scheme for their plates, and these changes are allowed.  There is more leeway given to show car owners regarding their plates.