A colleague at work gave me a ride in his new tesla a couple years ago. I know that autopilot has improved a lot since then, but we were on a freeway and the left lane was merging onto the expressway and had come to a stop. The lane we were in was moving just fine. The tesla though we were in the left lane or something because it slammed on the breaks to prevent us rear-ending the stopped/slowing car in the left lane. This caused us to nearly get rear-ended for erratic driving. My colleague drove manually for the remainder of the commute :)