I found this information on Google about the 69 Polara police cars. There were other sites that stated the speed of 149.6 mph.

1969 Dodge Polara 440
When old-timers get together and talk squad cars, this is the one that gets reverence. The full-size 1969 Dodge Polara police special was relatively lightweight thanks to its unibody construction and definitely overpowered due to the 375-horsepower, 440-cubic-inch V8 under its hood.

Channeling all that power through a three-speed TorqueFlite automatic transmission, in testing conducted by the Michigan State Police, the ’69 Polara swept to 60 mph in only 6.3 seconds and blitzed through the quarter-mile in 14.4 seconds at 98 mph. And it sped around the big oval at the Chrysler Proving Grounds in Chelsea, Michigan, at an unheard of 147 mph. Even by 21st century standards, that’s astoundingly fast.

To many officers who drove one, the ’69 Polara will always be the greatest cop car of all time.