The "aggressive tailgater" is a very common incident. I myself have had to make the difficult decision that you are forced to make on impulse in regards to dealing with this particular situation. So many avenues that we have heard about in the past, "drive to a police station", "lock your doors, park the car, ready your weapon and call the police", "keep driving and call the police", etc.
There are so many variables to this situation that there is no universal answer for what specific actions to take. The best thing to do overall, is use good judgment.
1. A few years ago, I was in a Walmart parking lot, and turned into a lane with markings to drive opposite the direction I was driving, no one was in any danger, the lot was new, but an overzealous male driving a van saw this and began driving erratically behind my vehicle, honking his horn and attempting to wave me over. I drove to an empty part of the lot towards the back, and I noticed that there was a child most likely not many more than ten years old, sitting in the front passenger seat. The child looked scared. I made sure my doors were locked as the vehicle advanced. At the last minute, I pulled out of that lot and drove into another parking lot. I realized that even though my option of retreat was being blocked and there was a clearly ill intent (in the state I reside in, a firearm can be used to prevent or stop the commission of a felony), I had no witness. If I were to draw my weapon to ready, the only witnesses at that point were that boy, and a person who was most likely his father. I parked at a coffee shop and called my father, who was home a mile away. My father drove to where I was, and while he was en route I called the local police department. My father arrived, the other driver saw his truck pull up to my car, and that driver decided to leave. The right choice is the one that protects you, and whoever is with you.
2.In another situation similar, this time I was without a firearm. I was with a now ex-girlfriend and I was driving in an area I was unfamiliar with. An enraged driver began chasing us through a suburban townhouse complex around 10pm. I did the only thing I could think of: Broke every single traffic law I could, laying on the horn while doing so, in an effort to attract attention and hopefully generate a police call. At the beginning I had come to a stop as if to let the driver approach me, and when he ran towards the car I sped off... this didn't work well because I was unfamiliar with the area". I was blowing stop signs at 50mph in residential zones and such. Finally I hopped a curb in front of gas station, jumped out, locked the doors and ran inside and yelled call the police. They did. For some reason, it appeared that a tactical unit was already out looking for this guy.
3. I was leaving work and pulled onto the highway, a car pulled up behind my truck and began immediately tailgating. I knew the vehicle, and the driver, he was a drug dealer who I later found out was harassing everyone because he thought someone he worked with had ratted him out to management for selling speed to other employees. I immediately pulled into an empty parking lot, drove fast towards the middle, retrieved a full size .357 from my glovebox, and stepped behind my truck, revolver out of view. The car stopped just outside the parking lot then they sped away as fast as they could.
Every situation has different variables. Who, what, when, why, where and how.
The advice I give to friends when this subject has come up, based on what I have personally experienced is as follows:
1. Get attention. Do whatever you can to draw attention to your situation. If you can safely run a red light and get pulled over, better to have a traffic fine than a force use situation. Driving to a police station has been mentioned, but consider driving to a public place like a strip mall or some place you know is open. You may know how to get to the police station in the city you live in, but what about 5 cities over? There may be a higher probability of you knowing how to get to a strip mall.
2. Find a tactical advantage. If you stop, and they get out, stay in your vehicle! they are now out of their vehicle, and you now have the option of putting the pedal to the metal and getting away from them. If you don't know know the area, stay on the main roads/highway/freeway. If you know an area, use that to your benefit.
3. Call the police as soon as you can. Choose your words carefully, you want your call prioritized. "I think I am being followed" will not get the same interest as "I am being chased, I am really scared". One thing to remember is that banks often have cameras that are monitored on live feed. Driving into a bank drive up is an easy way to get your situation put on camera.
4. Keeping a can of pepper spray around can change an entire situation. Pepper spray is at a different place in the standard use of force continuum, and generally doesn't need the same justification as using a firearm. I work in the private security industry and have to follow a use of force continuum, I am very much a proponent of using pepper spray.