The Police Patrol appears to be modeled after a eighth and ninth generation Chevrolet Impala Police Edition. It can be found on the streets of Liberty City along with the Police Cruiser. The vehicle is manufactured by Declasse, Rockstar's version of Chevrolet.
The Patrol is generally used as a patrol vehicle rather than a pursuit vehicle, due to it being slower and heavier than the Police Cruiser (the acceleration is about the same). One of the few advantages it has over the Police Cruiser is that it sports all wheel drive. Like the Cruiser, the Patrol's livery is clearly based on that of the New York Police Department's vehicles.
In GTA Chinatown Wars, the Patrol bears LAPD-style markings, rather than the NYPD style, making the car more immediately recognisable via the DS interface. Despite the Police Patrol being the only police car in Chinatown Wars, it is Police Cruisers that are seen in the cutscenes.
Use in side-missions
When the player is stationary in any police vehicle they can access the Police Computer (this is done by pressing the L1 button (PlayStation 3), the LB button (Xbox 360), or the E key (PC)), which lets Niko search for the most wanted criminals, see what the most recent crimes are, search the police records and even call for backup. This is where the player can start the Vigilante style side missions and the Most Wanted side missions.
Although distinct from the Police Cruiser, the Patrol has "Police Cruiser" badging.