A silhouette racing car is a race car which, although bearing a superficial resemblance to a production model, differs mechanically in fundamental ways. The purpose of silhouette cars is to provide a manufacturer with a tangible link to their consumer product offering so as to derive maximum marketing benefit from their investment in the sport. They also provide spectators with familiar car models with which they can identify.
Entire championship fields can consist of silhouettes, or sometimes only a single class in a multi-class field may permit silhouettes. Notable racing classes where silhouette cars have been used include Trans-Am, NASCAR, Stock Car Brasil, Group 5 Special Production Cars, Group B rallying, DTM, JGTC/Super GT, Monster truck and the Australian Supercars Championship.
Silhouette cars often employ radically different chassis construction techniques such as tubular space frames or carbon fibre tubs in place of regular monocoques, and many also have completely different drivetrain configurations than their road-going counterparts. The bodyshells themselves are generally made of lightweight materials such as glass-reinforced plastic or carbon fibre and often few or no parts are shared between race and road versions of the cars. These changes are aimed at improving the desirable characteristics of the components, such as increasing the stiffness of the chassis, or the output of the engine.