If the police car was marked as such and not appearing to be a civilian vehicle, you are correct. Common sense would indicate that if you were going 16 mph above the posted speed and saw a police car, you slow down, and take your chances of either bring pulled over or not.
The problem with common sense is that it is not all that common. With respect to driving, anyone driving on the road has the responsiblity to be alert to potential hazards, which does not just mean vehicles or pedestrians that are near you, but also down the road. And, the faster you are traveling, the farther down the road you should be looking for hazards.