Let’s not forget the good old unmarked car, on which police have spilled oceans of cash to make it ever more stealthy. Now so-called patrol cars feature lightbars hidden behind the windshield just under the roofline, black-lettering-on-black-vehicle-paint to comply (only just) with ‘police cars must be marked as such’ laws, etc.
I have a long screed against unmarked cars to be posted elsewhere someday but a larger and larger percentage of police fleets are unmarked cars.
Unmarked cars are there to create cash flow.
If they wanted you to actually slow down their cars would be distinctively marked as a reminder to at least stay close to the limits.
Enriching city coffers is not a proper function of ‘law enforcement’.