I had an incident the other day that impressed me. I was on the interstate, three lanes, navigate on autopilot. The car likes the middle lane and I was traveling about 10 mph faster than the cars I was overtaking. My car slowed behind a vehicle ahead of me, there was a car to his right and another to my right in the right hand lane, the left lane was clear. My description sucks, basically we were in a square and I was the left rear car of the four. The car notified me it was changing to the left lane because it was faster, I checked the rear view mirror, no car within 300 feet of me, checked the left mirror and the left lane was completely clear. The car moved about 1/3 way into the left land, then yanked back into the center lane as a woman in an Audi ripped past me on the left at well over 100 mph. She had been in the right lane, closed at high speed, and at the last second jerked her car across the three lanes to whip around me on my left. Had the car not moved back into the middle lane there is no way she would have been able to get around me without hitting me and causing a multi car accident.
Now, it is possible I would have looked back into my rear view mirror one more time and seen her flying up from behind and avoided the accident if I were driving the car, but realistically probably not since I had just checked and nobody was even remotely close to me. And had I jerked the car back into the center lane I could/would have overcorrected and hit the car in the right hand lane. Instead the car yanked itself back to the center of the middle lane. Then it calmly signalled and moved back into the left lane to pass.
I was so startled I forgot to toot the horn to save the video. :/