Development mule
A development mule or a test mule in the automotive industry is a vehicle equipped with experimental or prototype components for testing. Automakers evaluate aspects of vehicles before a full pre-production car is built to find problems. Mule cars are drivable and may come after concept cars that sometimes lack critical mechanical components.
Mules are often heavily altered and the exteriors may be disguised as current production vehicles or as completely different models. Some noticeable alterations include simpel cylindric shapes for the lamps in the taillights, different rims on the front and back without centrecaps, and a severe amount of added plastic and dark tape to hide the actual shape and design of the vehicle. They are most often used very heavily during testing and are scrapped.