I have it in my head that people buy these cars to pretend to be cops and get that reaction out of people-- many do and equip them with light bars or leave the stupid floodlight things on the side mirrors to imitate a cop car. I make it a point to drive like I usually do, not slow down if I'm speeding, sometimes speed past them for no reason, just to make the point that they're nobody special.
10 years ago that would have been the prime undercover car to look out for, but these days, folks with the intention of imitating cops are just fooling themselves. Around here all the Crown Vics have been relegated to transport duty for meter maids, mall cops, or sold off second hand. If I do see one that's a legitimate police vehicle, it's on the side of the road unoccupied with lights flashing in a construction zone only because they had no other vehicle available.