A body kit is a collection of exterior modifications to a car, typically comprised of front and rear bumpers (fenders), side skirts, and spoilers. Companies sell these replacements as alternatives to the traditional look of the vehicle from the factory. Body kits will be designed to complement 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 kit will be matched with the rear of another.
Automative body kits are usually constructed of either fiberglass or polyurethane. Most car modification entusiasts prefer polyurethane because it is more resistant to damage, and does not crack in cold weather. In some cases, body kits may also be constructed of carbon fiber, which is a popular, lightweight material. This type of modification is not as highly regarded among speed enthusiasts, though, because it is very costly, and the difference in weight is minimal, versus changing other parts such as the hood or trunk.
Factory fitted bodykits are now becoming more common, perhaps in response to the growth of the aftermarket tuning industry in the late nineties and onwards.
That ricers body kit makes me laugh!