I'm sure we've all been in the situation before - doing 10-15 of PSL at night and rapidly closing on a crown vic with no lightbar. Is it a cop or not? It can be almost impossible to tell at night without pulling right next to them, which is of course putting yourself at risk for a stop if it is indeed a stealth car or an unmarked.
What are some easy ways to tell?
For me, I look at the wheels - 95% of the time, if it's a cop it will have the black steel rims. Also, look for NMO antenna mounts on the trunk - most organizations won't buy a new car for an unmarked or stealth, they will convert a normal crown vic which leaves the antenna mounts in place.
Any other methods?