We still have some plain white Camaros and a Mustang or two in Northern Calif. plus the local cops had a Viper for a short time. I haven't seen the Mustangs for a while but I saw the Camaro with three cars pulled over a couple of days ago. No markings except the CHP logo on the doors and the light bar which is small. The local force had to get rid of the Viper as they couldn't afford the upkeep on it.
Ron