[waste_monk]

I have heard that the problem with ex-emergency services vehicles is they tend to have low distance on the odometer but drastically higher engine hours, particularly idle hours. That is, they may sit with the engine idling for hours at a time to maintain power to the lights, radios, and other vehicle systems, and are generally closer in wear and tear to a vehicle with several times the mileage.

Another problem I have heard of is that while the actual mileage may be low, the miles that are driven tend to be much "harder", in the sense that an emergency services vehicle may be accelerating and stopping rapidly, and generally being thrashed without regard for the vehicle, leading to increased wear on the engine and transmission.

It reminds me of the saying attributed to Jeremy Clarkson, about the fastest car in the world being a rental.

[trailrunner46]

Yes, trucks typically are running with the generator constantly on scene. Also many pumps are run on a PTO system where the transmission is put into a pump gear, further wearing on it since pumps can be run a lot on scene.