This morning, I was in bumper to bumper traffic when AP (TACC) did something completely wrong. From a stop, it began to accelerate toward a stationary truck right in front of me. This was a wake-up call for me because I've been using EAP on this exact commute for over a year now, and TACC has never had trouble keeping pace with changing traffic speeds. Even on this drive, I had been following this truck in stop and go conditions for over 20 minutes with zero issues. Basically the truck comes to a stop, and I come to a stop. When truck goes, I start to go. Very routine. And then it happened. The truck stopped. I came to a stop. And then 5 seconds later, I started to go. But the truck had not moved an inch. I slammed on the brakes with about a foot of space remaining between us. Now alert of the issue, I started to pay attention to the screen to see what the car was seeing. Sure enough, on the next stop, I see the truck disappear from the radar's view. And my car starts to accelerate again. I immediately brake. For the next mile or so, this would happen periodically. Sometimes when the truck disappeared from the radar's view, my car would not move forward. So there must be some failsafes in place. But clearly those failsafes are not robust enough. By the time I pulled out my phone to try to catch this issue on video, TACC was starting to do better. I managed to capture one unintended acceleration by the car, but the truck comes back into radar view, and my car brakes before I had to intervene. You can see this incorrect acceleration at around the 1:03 mark. In my last year of using EAP/TACC, never once has my car move forward from a stop, even a little bit, unless the car in front starts to move first. Several variables to consider here: - it was raining, and that could have affected radar performance. But this was not an issue for most of the drive, and rain conditions were steady. I've also done the same drive thru rain countless times. - I just got 2019.8.5, and I hear the AI has been revamped - something about the truck could have been giving the radar difficulties (though it doesn't explain the flawless 20 min before the UA occurred). Notably, the radar couldn't see one car past the truck. - something could have jammed the radar in the vicinity where these UAs were happening Description has timestamp links to notable situations: Bottom line: stay alert on AP/TACC and don't get complacent. It only takes the one glitch to cause an accident if you're not paying attention.