Floorplan refers to the biggest part of the car's body. It is a stamped metal part that contains several smaller attached stampings. It is also called the foundation of the vehicle structure. This large metal stamping often incorporates several smaller welded stampings to form the floor of a large vehicle and the position of its external and structural panels. In the case of a monocoque design, the floorpan is the most important metal part establishing the chassis, body, and thus the car size. It serves as the foundation of most of the structural and mechanical components of a unibody automobile to which the powertrain, suspension system, and other parts are attached.