Cage systems or bar systems that are fitted to the front of a 4x4 car, pick-up or other vehicle are called 4x4 bullbars. They are most commonly seen on 4x4 vehicles but can be fitted to any form of four-wheeled vehicle. The primary function of a bullbar system is protruding from the front end of a vehicle to prevent damage and to protect the occupants in the event of striking an animal. The use of 4x4 bullbars as a style accessory also is common, even in urban areas.
Bullbars originally were intended as a means to protect the vehicle and occupants in cattle farming applications. This intended use coined the term "bullbars," because the risk of hitting one of the farmer’s cattle was ever-present when 4x4 vehicles were being used in that situation. National differences have led to the same cage system being termed "roobars" — as in kangaroo bars — in Australia because of the risk of striking a kangaroo on the roads. Various uses for the bars in farming applications have also given rise to the nickname "nudgebars," because the cage system can be used to coerce and nudge stubborn animals, encouraging them to move without causing damage to the vehicle.
Since 4x4 bullbars were designed to protect the occupants of a vehicle in a collision with a large animal, almost all bullbar systems originally were made from solid steel sections with a view to providing the highest level of protection. As 4x4 bullbars became an ever-more-popular accessory for urban off-road vehicle owners, however, the the risk to pedestrians if involved in a collision was greatly increased in comparison to the same 4x4 vehicle without a bullbar installation. In addition, the damage caused to another vehicle in a collision was greatly increased by the presence of 4x4 bullbars. These factors led to a 2001 European Union (EU) directive banning the use of steel bullbars on any vehicle.
Since the implementation of the 2001 EU directive, 4x4 bullbars have continued to be manufactured and installed on vehicles. These more modern bullbar systems are often made of polyethylene material and are designed to absorb impact shocks, leading to a reduced effect on both pedestrians and other vehicles if a collision occurs. Some companies also offer bullbar systems that are fully integrated with a vehicle’s impact crumple zones and airbag triggers. Modern bullbars are also still used for their originally intended purpose and are designed to absorb impacts with large animals while maintaining the drive-ability of the vehicle after a collision.