A tuner car, often from Japanese, Asian or European manufacturers, is a car that combines comfort, practicality and high gas mileage with performance modifications, primarily to its engine. Tuners are normally good-handling vehicles, due to their light weight and more sophisticated suspensions.

Tuners are different from supercars in many respects, from price to engine displacement and horsepower. However, they're not the typical imported sedans or SUVs; they are lighter, faster and have better handling.

What distinguishes a tuner from the rest of the cars is that the owner is - in many ways - expected to customize and personalize the car to their liking. They are manufactured in a way that makes it easy for the owners to improve the cars. Some are even de-tuned to meet horsepower limits of other countries. Popular modifications range from visual upgrades such as changing the rims, tinting the windows and installing bodykits, to a variety of performance modifications (primarily to the engine), such as installing a short shifter and a Weighted Gear Knob, depending on what the car is "tuned" or set up for.

Some tuner manufacturers offer variants of their cars with performance modifications already installed, such as the Subaru Impreza STi and the Mitsubishi Lancer Evolution. Due to their smaller engines, these cars are often manufactured with turbo-chargers and super-chargers in order to compete with other sports cars.

A Tuner also can refer to the driver of a tuner car.