Is the term used to describe the audio or video system installed in the car. A stock car audio system refers to one that was specified by the manufacturer when the car was built. A Car Audio Custom installation may include anything from upgrading the radio to a full customization of a car based around its audio equipment. Events are held where entrants compete for the loudest and most innovative sound systems.
 Tuning Interior
Interior tuning is a term used for changes in the interior of the car. For example, removing the back seats to make room for the sound system, or taking in the front seats and replace them with bucket seats (Sports seats).
Another recent form of the interior tuning is a replacement OEM Shift knob with Aftermarket versions, such as a weighted shift knob for the cosmetic and / or to meet the goals.
 Tuning the engine
Main article: Tuning the engine
Tuning the engine, as have recently been marketed as a replacement for the basic engine components with after-market versions that perform the same functions, which are replaced with the prospective increase in power. Car tuners tend to install new turbines, to change the car engine cooling unit, to replace the air filter, but they can also establish a more powerful engine in the car to change them.
For example the tuner can change the ECU to get more power. Another example is the modification and / or replacement of the OEM Stick Shift manual transmission is also known as channel-optimized Aftermarket Stick to the design known as a short SHIFTER to as "thin" driver may include the installation of a weighted shift knob, which combines the shape tuning of interior with function, further increasing productivity.
 Tuning the suspension
Suspension involves changing your springs, shock absorbers, swaybars, and other related components of the car. Short springs offer improved lowered look and a lower center of gravity. Rigid shock absorbers improve the dynamic changes in body weight during cornering and normally have internal short to stop them, to change, when the short spring is used. Hard impact bars reduce body roll when cornering, thereby improving the grip that the inside tire on the surface, which improves handling response. Other components, which are sometimes added a bar, which increases the rigidity of the body, as well as help to preserve the proper suspension geometry during cornering. On some cars certain braces, anti-roll bars, etc., can be retro fitted to lower specification cars from sports models.
For vehicles, Offroad, the emphasis is on lengthening the suspension travel and larger tires to increase ground clearance.
Lowriders with hydraulic / pneumatic suspensions use another unique kind of suspension setup, in which the height of each wheel can be quickly adapted the system of rams, even to the extent that it is possible to "bounce" the wheels completely remove from the land.
 Body Tuning
Body tuning involves adding or changing spoilers and body. Sometimes this is done to improve the aerodynamic performance in the vehicle, as in the case of some wings and bumper horizontal, or to facilitate vehicle by replacing the body, such as hoods and rear-view mirror with components made of light composite materials, such as CRFP. Lateral speed and adhesion can be improved through the generation of downforce.
More often, however, these changes are made primarily to improve the look of the car, as in the case of non-functioning scoops, spoilers, wide arches or any aesthetic modification, which does not benefit performance. Very rarely does the market after the spoiler or body to improve performance, the majority add weight and increase the resistance coefficient of the vehicle and thus reduce its performance.
Increased gauge through the brace and wide body kits enhance the cars cornering abilities. Reducing the center of gravity of the other objective of the body seen through the tuning of the suspension modifications.
Detuning provides for the return of a modified car to its original factory condition. This is akin to automotive restoration. Detuning term may also refer to a reduction or decrease in performance in any area of tuning. An example of this may be where the engine is "detuned", to provide increased traction in the day when the track is not enough grip.
"Streeted" or "Auto-tuner" are Japanese imports, such as the Toyota Supra, Mazda RX-7, Subaru Impreza and Mitsubishi Lancer Evolution series. These machines are the most common change to more expensive Mods there. The most popular modifications include upgrading the suspension, exhaust system and turbos.
 Legal requirements
In many countries there are legal requirements as to what car owners can and can not do in relation to vehicle modifications. For example, all vehicles in the state of Victoria, Australia, must conform to design standards to ensure vehicles provide drivers and passengers with a maximum level of security.  There are also restrictions on P Plate drivers, which can prevent young drivers from driving modified vehicles. 
In the United Kingdom and the Netherlands it is illegal for any vehicle to have blue lights, as they are used for emergency vehicles.
In Scotland and Denmark, it is unlawful for any vehicle to have neon underlights by car, as it distracts other drivers. In the Netherlands, neon is permitted under the car, but only when the car is on display when the machine is in the way of general lighting should be turned off.
Recently, Belgium has issued a new law that describes what bodykit parts must be approved on safety issues.