In this footage from Europe, the autopilot on a Tesla warns driver Frank van Hoesel of an accident about to happen. He doesn't even realize why his car is braking suddenly until he sees the crash occur—forty yards away.

Original video, authorisation from the owner. Essential, no one could predict the accident but the radar did and acted by emergency braking. pic.twitter.com/70MySRiHGR — Hans Noordsij (@HansNoordsij) December 27, 2016

Thomas De Maesschalck summarizes what went on:

The Tesla Autopilot system registered that the SUV in front of the lead car was braking hard and the system recognized this as a major danger. The Forward Collision Warning send out an audible warning close to two seconds before the lead car slammed into the SUV and activated emergency braking well in time. At first, the driver was shocked that his car started braking heavily from about 110km/h but fractions of a second later it became clear to him why the car did this!

[Original YouTube Link]