I don't mean to argue, but I've got to point out that this is bad advice...Briankey wrote:
Forget calling the Cops on 911, they aren't going to do anything. Found that out myself once.
Even if the police can't get there in time to help you, you will be much better off if the situation does escalate if you have called and documented the situation.
I can also tell you that in the city I work in every time a call like this comes in the dispatcher puts it out over the radio with a vehicle description, location, direction of travel, and wheter the caller is following the vehicle or not.