Car Modification is done in order to improve its performance, handling and presentation and improve the owner's driving style. Modification has become a way to personalize the characteristics of the vehicle to the owner's preference. For example, they may be altered to provide better fuel economy, produce more power at high RPM or the ride comfort may be sacrificed to provide better handling.

Car Modification is related to auto racing, although most performance cars never compete. Rather they are built for the pleasure of owning and driving such a vehicle. Another major facet of modification includes performance modification to the car exterior. This includes changing the aerodynamic characteristics of the vehicle via side skirts, front and rear bumpers, adding spoilers, splitters, air vents and light weight wheels.