Performance tuning focuses on tuning an engine for motor sport, although many such cars never compete but rather are built for show or leisure driving. In this context, the power output, torque, and responsiveness of the engine are of premium importance, but reliability and fuel economy are also relevant. In races, the engine must be strong enough to withstand the additional stress placed upon it, and so is often far stronger than any mass-produced design on which it may be based, and also that the vehicle must carry sufficient fuel.

In particular, the transmission, driveshaft and any other load-bearing powertrain components may need be modified to withstand the load from increased power.In most cases, people are interested in increasing the power output of an engine. Many well tried and tested techniques have been devised to achieve this