Most unmarked cops i.ve seen are all Holden SS any colour, easiest way to tell is theres's 3 antennas on the rear window, tinted black ass, little box back right parcel shelf and little box where the passenger sun viser would go or infront of raer view mirror and no towing ball/hook.
But really best thing to do is just don't speed and race. not worth the risk life wise are poeples lives.