For the American oval track automobile racing series, see Modified racing
The term modified car is given to any vehicle that has been altered from its original state; most commonly with aftermarket components. The term denotes a car that has been significantly altered for the purpose of appearance or for increased engine or handling performance, the process by which this is carried out is known as car tuning. The term is generally used in reference to modern vehicles that have been altered, and not typically used to describe other types of modified cars such as Hot rods, however the definition can include this, as well as any other car that is not in its original form as was purchased from the manufacturer. Modified cars are commonly small hatchback and coupe cars such as superminis and small family cars.
For associated article see: Car_tuning#Areas_of_modification
A modified car can consist of any of the components associated with car tuning, however common upgrades include replacing the standard factory issue wheels with aftermarket alloy wheels, usually of a larger diameter to improve the aesthetics; lowering the suspension of the car to give it a more aerodynamic, stable look by replacing the springs (often in conjunction with shock absorbers) or torsion bars; replacing the existing exhaust system with one with less gas-flow restriction, louder and deeper sound and often small improvements in performance (due to exhaust gas-flow rate). Other common upgrades include the installation of a short shifter as well as an aftermarket shift knob, or a performance oriented Weighted Gear Knob. Common non-mechanical upgrades include a cars audio system; though not performance oriented, are nevertheless a very common-place modification. This includes upgrading the head unit itself, and upgrading and/or installing additional speakers.
Significant modification to a car could involve adding a fiberglass body kit to improve the aesthetics, a complete respray to a more unusual, distinctive and noticeable colour and finish, increasing the engine performance with ugraded components such as a high-flow air filter, additional components such as turbocharger kit, as well as more permanent modifications like port and polish.
Traditional customizing methods, more common when modifying classic cars to create cars such as Hot rods, include roof chops, two door stretches, suicide doors, channeling and lights, trim and sheet metal from another car. Sectioning is also used sometimes.