19: Rotating License Plate
The rotating license plate is not common but it has a purpose. Most of the time, that purpose involves some sort of government agency or a criminal that needs to hide the identity of a car. Rotating license plates are not easy to install, and there are very few shops who will perform this modification (via CarBuzz).

A rotating license plate can also be used on a show car when a club or shop name needs to be displayed instead of the stock plate. A rotating plate can make this easier than having to unscrew the original license plate every time you go to a car show. Either way, this is a unique feature that you’ll seldom see often.