unit, is a police car tasked with enforcing traffic laws and conducting traffic stops, typically on major roadways such as highways. They are often relatively high-performance vehicles compared to patrol cars, as they must be capable of catching up to fast-moving vehicles. They may have specific markings or special emergency lights to either improve or hinder visibility. Alternatively, some traffic cars may use the same models as patrol cars, and may barely differ from them aside from markings, radar speed guns, and traffic-oriented equipment. Unmarked car An unmarked car is a police car that lacks markings and often easily-visible or roof-mounted emergency lights. They are generally used for varying purposes, ranging from standard patrol and traffic enforcement to sting operations and detective work. They have the advantage of not being immediately recognizable, and are considered a valuable tool in catching criminals while the crime is still taking place. The resemblance an unmarked police car has to a civilian vehicle varies based on their application: they may use the same models as marked patrol cars, and may be virtually identical to them aside from the lack of roof-mounted emergency lights, with pushbars and spotlights clearly visible; alternatively, they may use common civilian vehicle models that blend in with traffic, with emergency lights embedded in the grille or capable of being hidden and revealed, such as Japanese unmarked cars having retractable beacons built into the car's roof. Unmarked cars typically use regular civilian license plates, occasionally even in jurisdictions where emergency vehicles and government vehicles use unique license plates, though some agencies or jurisdictions may be able to use the unique plates anyway; for example, American federal law enforcement agencies may use either government plates or regular license plates. The term "undercover car" is often used to describe unmarked cars. However, this usage is erroneous; unmarked cars are police cars that lack markings but have police equipment, emergency lights, and sirens, while undercover cars lack these entirely and are essentially civilian vehicles used by law enforcement in undercover operations to avoid detection. The close resemblance of unmarked cars to civilian cars has created concerns of police impersonation. Some police officers advise motorists that they do not have to pull over in a secluded location and instead can wait until they reach somewhere safer. In the UK, officers must be wearing uniforms in order to make traffic stops. Motorists can also ask for