of the "Mechanized Division", which used two-way radio communication between police command and police cars. Under Popkess, the Nottingham City Police began to use police cars as an asset that police tactics centered around, such as overlaying police car patrol sectors over foot patrol beats and using police cars to pick up foot patrol officers while responding to crimes. As car ownership increased in the post-World War II economic expansion, police cars became significantly more common in a majority of developed countries as car ownership increased, police jurisdictions expanded farther out into residential and suburban areas, car-oriented urban planning and highways dominated cities, vehicular crimes and police evasion in cars increased, and more equipment was issued to police officers, to the point that vehicles became practically necessary for modern law enforcement. Types Various types of police car exist. Depending on the organization of the law enforcement agency, the class of vehicle used as a police car, and the environmental factors of the agency's jurisdiction, many of the types below may or may not exist in certain fleets, or their capabilities may be merged to create all-rounded units with shared vehicles as opposed to specialized units with separate vehicles. Patrol car A patrol car is a police car used for standard patrol. Used to replace traditional foot patrols, the patrol car's primary function is to provide transportation for regular police duties, such as responding to calls, enforcing laws, or simply establishing a more visible police presence while on patrol. Driving a patrol car allows officers to reach their destinations more quickly and to cover more ground compared to other methods. Patrol cars are typically designed to be identifiable as police cars to the public and thus almost always have proper markings, roof-mounted emergency lights, and sirens. Response car A response car, also known as a pursuit car, area car, rapid response unit, or fast response car, is a police car used to ensure quick responses to emergencies compared to patrol cars. It is likely to be of a higher specification, capable of higher speeds, and often fitted with unique markings and increased-visibility emergency lights. These cars are generally only used to respond to emergency incidents and may carry specialized equipment not used in regular patrol cars, such as long arms. Traffic car A traffic car, also known as a highway patrol car, traffic enforcement unit, speed enforcement unit, or road policing