WOW....what a bunch of ignorant responses.....and some good ones. A pace is when he is driving behind you at a resonable distance and he can tell that you are going the same speed or pulling away(going faster). Police vehicles come from the factory with "Certified" speedometers, which means their acuracy is guaranteed at the time they leave the factory. Changes in tire circumference over time do lead to very minor changes in the speedometer reading. Due to these changes, secondary confirmation(radar) of the speedometer reading is necessary in Oregon. That secondary reading need not be at the same time as the pace, just within a reasonable amount of time(the same day). Maybe its different in other parts of the country, but we don't pick out speeders by the car they are driving. They tend to stick out on there own regardless of what they are driving, especially if they are driving 25 miles an hour over the speed limit.
If you don't want a speeding ticket, then stop speeding.