This integral car part is typically welded on to the area between the rear door and the truck, wrapping around the wheel well.
Answer Quarter Panel
The quarter panel is typically made of sheet metal. However, it can be made from fiberglass, fiber reinforced plastic, or carbon fiber. In British English, it is known as the rear wing.
Asked by DRay585 · Last updated 5 years ago · 12.4K views · SOURCE
