Like the previous Aaron Spelling produced/Rick Husky created series S.W.A.T. (1975), which used the fictional "WCPD" police department, "T.J. Hooker" does not use the LAPD as the police department for which Hooker and the others are working. Despite the fact that they are obviously a part of the LAPD, with the look of the uniforms, and the design of the patrol cars, Hooker is part of the fictitious "LCPD". While there is a Los Angeles County Sheriff's Department, their uniforms and cars are different.
The exterior shots of Hooker and Romano's patrol car almost never match the background processing plates used for the shots of the car interior. For instance, if the exterior shots show them driving through a business district, the interior shots will show them driving through a residential area and vice versa.