The "Certified" speedometer is interesting unto itself...
Back before radar existed, or many departments could afford to buy a radar gun, the police cars were equipped with "Certified" speedometers.
The reason they were "certified" is that when a speeding car was spotted, the police would catch up to it and drive the same speed, and record that speed for the speeding violation.
It was also a very unreliable way to determine speed of the suspect vehicle. But police cars came with "certified" speedometers up into the 70's and 80's... But most I remember went up to 140 or 150 mph.
