When software 8.0 was released by Tesla, one of the features that Elon Musk promised would be available was the ability to see a few cars ahead through enhanced radar.

That ability is tested here by Bjorn Nyland in this video showing that the Model X detects braking from two cars ahead and begins to react on its own.

Video description:

"With software version 8.0, the radar can now see two cars in front. When the frontmost car brakes, the car in the display will turn white. I did several tests and measured the time from when the brake lights on the middle car turned on to when my car slowed down to be 0.2-0.4 seconds."