My Model X is in a body shop awaiting $25-$30K in repairs. I was on a stretch of interstate with three, well-marked lanes in my direction of travel, and the car was on autopilot. Traffic was fairly light, and I was in the center lane. I am not one of those people who texts or reads a book while the car drives, although I do make and take hands-free calls. I keep an eye on the car while it is on autopilot, because it has had a couple of near misses before (at least it seemed so to me). I was looking through the rear view mirror, because as other owners know, as great as the rear camera display is, it is difficult (for me) to judge distances by it. I spent no more than three to four seconds looking, which I have to admit is longer than I would look in a car with no autopilot. I looked back at the windshield just in time to see the rear of a semi in front of me, and at about the same time, the Model X hit it HARD. I careened off the truck, across the left lane (thankfully there was not a vehicle in it), and into the center concrete divider between the two directions of travel. The right front of my car took the brunt of the impact with the truck. I told the investigating officer that I had been in the center lane and the truck changed lanes right in front of me (that was the best I could make out, because the lane in front of me had been empty for at least 1/8 mile before I checked the rear view). The truck was on the right shoulder, and I had not been keen on trying to cross the interstate on foot, so I did not talk to the trucker. He told the officer that he was in the right lane, and I just came up behind him and hit him - and in the end, that is what the wreck report said. There had not been a peep from autopilot; I had just responded to the prompt to apply pressure to the steering wheel before this happened. What really sucks is that I had read about the latest software update, and saw that I could record from the front camera now. I had ordered a high capacity USB drive for this purpose - it came the next day. So anyway, no matter who's story you believe, the autopilot system should have at least attempted to brake under either scenario. I don't know if the following was a factor, but the week before, the large screen would not come on. I got it to come on with a reboot, and notified Tesla, and the fellow I spoke with said they would look into it. The next day after that, I was getting a camera error, which said auto-lane change disabled. I tried to clear that with a reboot and afterwards, neither scroll wheel worked, nor did the buttons above and below them. The warning message later went away on it's own. I contacted Tesla again. The next time I spoke with one of the service guys, just a few days before the accident, I was told that they were sending a technician out to look at the car's problems. The technician did not make it in time. Whether or not these problems affected the autopilot, I could not say.