Basically any new car can potentially be a cop car.
XR6's, XR6T's, XR8's, SS's, S's, any standard holden/ford, magna's and VRX magna, camry's, corolla's, lancer wagons and VRX lancer and pathfinder's. There all the ones that are just in my area, so i'm sure in city areas there are plenty more including modified cars.
But not all of these cars will pull you over unless you are doing something stupid. Usually the big bangers are highway patrol