I used to ride shotgun w/my Florida State Trooper brother in law. This was back in the era when 440 Fury III's ruled the roads. I have seen 135 mph on a certified speedo more than once- that's all the 440'd do in that application. Not the most aero platform, I'm sure all will agree.
A '09 cop car Charger w/the "Hemi" ran 146, the computer imposed limit. Unfettered by the computer, it ran 160-plus.
Michigan State Police 2010 police pursuit car tests: Dodge Charger, Ford, and Chevy
2013 testing has the Caprice 6.0L at 154, just ahead of the Hemi Charger.