This is a fantastic mod, and a great improvement on the old PolicingTools, but I do have the same problem as willpv23 does. Pressing ALT+R again to disable the radar, until the police car has moved off the scene, seems to work; it starts moving again at normal speed as soon as the radar is turned back off.
Also, the radar gun - for me - was being held by the PC up towards the sky. I fixed it with the WeaponsInfo patch given in an earlier comment, so it's now pointing horizontally, but the radar gun sits below the PC's hands - not in them - so I'm not sure if I've done something else wrong...
Great work! :-)