Bodykit or body kit is a collection of exterior modifications to a car, typically comprised of front and rear bumpers (fenders), side skirts, spoilers and sometimes front and rear side guards. There are many companies that offer alternatives to the original factory appearance of the vehicle. Body kits components are designed to compliment each other and work together as a complete design. Despite this, the 'mix and match' approach is often seen on cars, where the front of one body kit will be matched with the rear of another for example.

Automotive body kits are usually constructed of either fiberglass, polyurethane or in some cases carbon fiber - a popular and lightweight material. Polyurethane is popular with car enthusiasts because it is more resistant to damage and does not crack in cold weather. However, carbon fiber kits are not as highly regarded among automotive enthusiasts, because it is very costly for a minimal weight difference.
Factory fitted body kits are now becoming more common, perhaps in response to the growth of the aftermarket tuning industry in the late nineties and onwards. Many manufacturers now work in-house with their motor sport divisions to develop styling upgrades.

Ground effects
Ground effects are parts of an automobile's lower body designed to enclose the gap between the bottom of the fuselage and the ground. The purpose of ground effects are to deflect air around the car rather than under it, reducing the lifting effect of air passing under the car at high speed. Lift reduces the tires' contact with the road, resulting in reduced control. This effect differs from genuine Ground effect, in which airflow is manipulated in such a way as to create downforce on the car, pressing the tires harder onto the road.
Ground effects can be part of the vehicle's original design, or aftermarket parts added later (body kit). It should be noted that aftermarket body parts generally simulate the appearance of a vehicle in ground effect and usually do not provide significant aerodynamic benefit.

Chip tuning refers to changing or modifying an EPROM chip in a car's or other vehicle's electronic control unit (ECU) to achieve better performance, whether it be more power, cleaner emissions, or better fuel economy.
This was done with early engine computers in the 1980s and 1990s. Today, the term chip tuning can be misleading, as people

will often use it to describe ECU tuning that does not involve swapping the chip. Modern ECUs can be tuned by simply updating their software through a standard interface, such as OBDII. This procedure is commonly referred to as engine or ECU tuning. ECUs are a relatively recent addition to the automobile, having first appeared in the late 1970s.

As technology advanced, so did the electronics that go into cars. The ECU in a modern automobile, together with advanced engine technology, makes it possible to control many aspects of the engine's operation, such as spark timing and fuel injection. The ECU may also control electronic throttle control (drive-by-wire), valve timing, boost control (in turbocharged engines), ABS, the automatic transmission, and the electronic stability control system.
Performance gains are realized by adjusting the ignition timing advance. Higher timing may result in higher performance. However, to cope with advanced timing, one must run high-octane gasoline to avoid pre-ignition detonation or pinging. Manufacturers design for a specific timing and this may limit performance accordingly.
In addition, changing fuel maps to coincide with the stoichiometric ratio for gasoline combustion may also realize performance increase. Most manufacturers tune for optimum emissions and fuel economy purposes which can limit performance.
Cars with a turbo fitted can have the requested and allowable boost levels raised, these applications usually have the turbo fitted as a low pressure application leaving much room for improvement.
Another reason to change the ECU map is if there are engine, intake, or exhaust modifications to the car. These "bolt-on" modifications alter the way that the engine flows, often causing the air to fuel ratio to change. Without re-mapping the fuel tables, some of the performance gains from the modifications may not be realized.
A poorly tuned ECU can result in decreased performance, driveability, and may even cause engine damage.
The most common way to 'upgrade' the ECU is using either plug in modules as mentioned above or using a specialist tuner who will use an OBD Flash tool. These devices generally plug into the diagnostic port although in some cases the reprogramming it done directly on the circuit board. Maps are supplied by tuners.

Tuning is both an industry and a hobby, in which a car is modified in order to improve its performance and handling and improve the owner's driving style. As most cars leave the factory set up for average driver expectations and average conditions, tuning has become a way to personalize the characteristics of the vehicle to the owner's preference. For example cars may be altered to provide better fuel economy, produce more power at high RPM or the ride comfort may be sacrificed to provide better handling.Car tuning is related to auto racing, although most performance cars never compete. Rather they are built for the pleasure of owning and driving such a vehicle. Another major facet of tuning includes performance modification to the car exterior. This includes changing the aerodynamic characteristics of the vehicle via side skirts, front and rear bumpers, adding spoilers, splitters, air vents and light weight wheels.
Engine tuning
Engine tuning as of late has been marketed as the replacement of basic engine components with after-market versions that perform the exact same functions as those replaced while promising an increase in power output.
Suspension tuning
Suspension tuning involves modifying the springs, shock absorbers, swaybars, and other related components of a vehicle. Shorter springs offer an improved lowered look and a lower center of gravity. Stiffer shock absorbers improve the dynamic weight shifting during cornering and normally have shorter internals to stop them from bottoming out when shorter springs are used. Stiffer sway bars reduce body roll during cornering improving the grip that the inside tires have on the surface thus improving handling response. Other components that are sometimes added are strut bars which improve the body stiffness and help better maintain the proper suspension geometry during cornering. On some cars certain braces, anti-roll bars, etc can be retro fitted to lower spec cars from sports models.For offroad vehicles, 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 tuning in which the height of each individual wheel can be rapidly adjusted by system of rams, even to the extent that it is possible to "bounce" the wheels completely clear of the ground.
Body tuning
Body tuning involves adding or modifying spoilers and a body kit. Sometimes this is done to improve the aerodynamic performance of a vehicle, as in the case of some wings or bumper canards or to lighten the vehicle through replacing bodywork components such as hoods and rear view mirrors with components made from lighter composites such as CRFP. Cornering speeds and adhesion can be improved through the generation of down force which becomes effective at speeds of 120kmh and over.More often however, these modifications are done mainly to improve a vehicle's appearance, as in the case of non-functioning scoops, wide arches or any aesthetic modification which offers no benefit to performance. Very rarely does an after market body kit improve performance, the majority add weight and increase the drag coefficient of the vehicle and thus reduce its overall performance.Increasing the wheel base through spacers and wide body kits enhance the cars cornering ability. Lowering the center of gravity is another aim of body tuning dealt with via suspension modifications.
Detuning
Detuning involves returning a modified car to its original factory status. It is akin to automotive restoration. The term Detuning can also refer to the reduction or decrease of performance in a particular area of tuning. An example of this could be where the engine tune is "detuned" to allow for increased traction on a day where the track grip is not sufficient.