I don't know about other areas but in Georgia, so long as they are not blue or red, oscillating lights are not illegal. At one time, I had planned to use Amber and Green on my vehicles but found it to be overkill for my purposes. As far as the cars go, I know that many BEA/FRA use Crown Vic/Charger/other "LE" vehicles. I do not but I have never seen a problem with it.....except the "newbie" in my AO that has a huge badge and the words "Fugitive Squad" plastered on the sides and hood. He came into the MMA gym looking for training. The first words out of his mouth were "I am a bounty hunter and I want to see about some hand to hand or tactical take down training." Needless to say, he will be getting neither from me or the other trainers. Even they have seen professionalism....he had none. I digress.....back to the cars. There are reasons that these vehicles are used by LE. They are roomy with power and they are reliable. Picking one of the retired ones up from auction can save a ton of money and allow a person the upgrades that are added to these vehicles by city, county, and state agencies. Heck, if I had the money to get something besides the (second hand) Yugo I drive, I might have a fleet of them
I never had the "wanna be" syndrome, for a reason.
Not to mention that nobody suspects you in a Prius LOL