Most of the Gov't types I have worked with in the past are pretty good about checking fluids on issued rigs. By the tiem you have convinced the powers that be that your job need a a car or truck, you don't want to go through that mill again. you feel the need to keep it going as long as possible ...
Most of my guys and gals were Park Rangers and not city cops, but I think it still holds. They could get quite far out in the back country and that vehicle was their lifeline if anything went seriously sideways... What really used to tee them off was warranty breakage as they were made to feel like lab rats for some new models.
Break-downs and walk-homes are not fun. Especially if you've just been observing a Meth Lab in an abandoned cabin or motor home in an out of the way location. Those folks are shooters. You need to keep moving and you need your vehicle to be reliable. I've seen more than one experienced Ranger turn down a new model vehicle and let management have it for the first 30K
Most went to auction between 150,000 and 200,000 miles. Of course our program was just the opposite of that discussed. Oil changes at 6,000 and filters every other time.
Now that the vehicle are getting more data intensive with lap-top docks and full time communications with the LE Network, they will leave them running to keep the links up. I always thought they should all have solar panels on the roof to boost daytime 12v capability...
I could see new vehicle systems going to 12,000 mile oil changes. But I don't see anyone being comfy with 30,000 ...