Car tuning is a generalized term to refer to the act of improving the performance or appearance of a vehicle. For actual "tuning" in the sense of automobiles or vehicles, see engine tuning. As most vehicles leave the factory set up for average driver expectations and average conditions, tuning has become a way to personalize the characteristics of the vehicle to the owner's preference. For example, cars may be altered to provide better fuel economy, produce more power, or to provide better handling.

Car tuning 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. Exterior modifications include changing the aerodynamic characteristics of the vehicle via side skirts, front and rear bumpers, spoilers, splitters, air vents and light weight wheels.