I don't know about routine services, I work for a fleet in a city, and out services can get pretty far out, near by cities have similar results (in talking with other shops). Some cars get lost in the mix, if a fleet is large enough. While I totally agree that for 90% of most police vehicles lives are spent at idle, and or start/stop mode.
Buy it. !!!! Rare police vehicles are cool. Get an okay to run all the police lights on it too......you can usally get with the local law and tell them what you plan to do.