There is a lot of demand for this kind of game, especially among players of the popular Police Quest series and SWAT 3.
You're a police officer in a large metropolitan city (a SimCity would be nice). You start out as a rookie (there can be a short training period or rookie school at the beginning to familiarize you with the way the game is played).
This game would be played much like SimCopter and Police Quest. The car would be driven like Need For Speed or Streets of SimCity. You patrol your beat at your own leisure and answer game-generated calls for service (armed robberies, speeding vehicles, riots, wrecks, medical emergencies, traffic jams, fights, drunk drivers, burglar alarms, shootings, fires, etc). There is a map on your car console, that displays an icon showing you where the call is. You have several AI partners on the streets with you. You can call them by radio for backup, also you can hear what they are doing and back them up. You can also notify dispatch for fire and ambulance help. You can also come across speeders, drunks, etc, at random. Whether they pull over and how long it takes them to pull over is up to the computer AI. You may have to chase them.
You have a good bit of equipment to use:
Shotgun (stored in trunk of car)
You also have a choice of several cars to drive such as marked and unmarked Crown Vics and Camaros. Promotions and paychecks are based on points, and money can be used in convenience stores, coffee shops, and to buy new equipment (or maybe to pay informants) etc.
You car also has the basic equipment of a police cruiser. Police radio, spotlight, radar, lights and siren (the siren should have several tones, adjustable by the player, and the lightbar and siren should be on separate switches, this a serious flaw in Need For Speed and other games).
You can interact with people, and you can walk inside building to do things (eat, do paperwork, answer calls, etc.).
There is a central police station, a jail, hospitals, fire stations, bars, gas stations, and a small substation for you and your partners to hang out. There are "big city" areas as well as suburban areas and "bad" neighborhoods. suburban areas and "bad" neighborhoods.
Driver 2 gave the player possibility to step out of the car, and hi-jack another one. Suddenly a car game is not all about driving. I think gamers demand more and more from games in the future, it's not enough just driving the car ennymore, the player wishes to totally interact with the surroundings. A police game where you can do "everything" (just not all the booring paperwork) would be very fun. Just imagine, buying donuts before you set of to investigate a robbery.
Think GTA: Role Reversal