If it came from a large department then you will most likely have no worries about how it has been maintained. Ours are required to have oil changes every 3k and other periodic maintainance at 6k, 12k and 24k, those being more and more thorough. My old car was a 99 model with 128k on it. It was still a very good car even though it was "driven hard." Police package cars are designed to take abuse and keep on going. How many car chases have you seen on TV where the offender car blows up? Ever seen a police car give up its guts first?
The police package has heavier suspension, brakes, cooling, charging, etc. There is however no special "chip" or anything like that. Some cars for highway use may have different gearing in the differential for better top speed or gas mileage. Ours were for city use and were governed to 120 mph top end. Never needed more than that to get the job done.
As far as the endless idling, I wouldnt worry about that either. That is what the extra cooling is for on the police package. My new 06 actually has an hour meter on it. My 99 would idle so long that it would be making gurgling sounds from the condensation building up in the exhaust. Big fun to rev it up and clear out the exhaust when someone is walking behind the car.
A little advice about police cars. Pull the back seat out and search it REALLY WELL before driving it home. Ive seen some cars from small departments that had a lot of contraband hidden in/under the back seat. I pull my back seat up the day I get a car to make it easier to search after someone sits back there. Dont want to get tagged for someone elses dope a couple months down the road.
Also clean that mother with bleach or something strong. It will smell for a little while but if you had any idea of how many people crap, pee, spit and bleed in the back of police cars you wouldnt think twice about doing it.
Most of the cars have had the gas tank recall done by Ford dealerships as part of the lawsuit. All they do is grind off a couple small metal tabs off the rear end that were pointing towards the gas tank. When hit from behind the gas tank was being pushed towards the rear end causing the tabs to penetrate the gas tank. The leaking gas would then catch fire. I watched a couple get done.
Other than that nothing else comes to mind. If you have any ?s just send me a message.