Import tuners are car mechanics are specialize in providing regular maintenance, or "tuning up" cars that come from other countries. Modifying and customizing cars, especially sports cars, has become a popular pastime. It has given rise to a whole new concept of tuning a car. Tuning a car could be either a cosmetic change or it could refer to changes made internally for optimizing performance. Cosmetic changes like spoilers, ground effects, neon lighting, differently-designed exhausts, loud sound systems, large wheels with low-profile tires and similar changes are common. These changes might satisfy the desire of the owners but are actually detrimental to the car's performance.

Making internal changes to a car is also popular and many expert tuners can be approached for this purpose. It has now become the norm for manufacturers, especially the Japanese ones, to export not-so-powerful models to the U.S. Tuners then take over and restore the car to its original engine capacity. Modifications like swapping engines and transmissions are done by expert tuners. Examples include the conversion of a Honda Civic into a Civic Type-R or Si or the conversion of the Toyota Celica GT or GT-S into a Celica GT-Four.

Tuning has become such a popular trend that manufacturers are altering their products suitably. A segment known as pre-tuned sport compacts has emerged. Honda, Toyota, Mazda and Nissan are key players in this segment. Accessories for this purpose are also provided by the manufacturers themselves. Not to be left behind, the U.S. domestic market has also opened up to this style of production.