Just traded my P85 for my P85D. I am happy with everything, including the new awesome launch performance. Although Autopilot (at least its initial features) were not a major deciding factor of the trade up, I thought I would give TACC a try. My first impressions are this thing is simply not up to par. It feels like a beta test. I have used it for may 50 total miles, and there were at least 3 encounters that made me say "Holy sh*t" 1st encounter: I was cruising along at 74 MPH, distance setting at 4. A guy in a big stake-bed truck decided to change lanes about 7-8 car lengths in front of me. Nothing abrupt, he put his signal on and slowly changed lanes. He was probably traveling at 70mph when entering my lane, and was not speeding up so I was slowly approaching him. As he was halfway in my lane, my P85D maintained 74MPH and kept closing in on him, even while he was halfway in my lane. I thought, ok - I will go ahead and let this thing brake for me as I kept my foot hovering above the brake pedal. Sure enough, as he finally completely entered my lane, it waited until literally 2 car lengths to beep the collision warning sound and then abruptly hit the brakes (I have collision warning on the early setting). I still had plenty of time to brake on my own. The problem I see is it doesn't react until the car is completely in your lane, and its not smooth- it creates an erratic driving situation that other drivers might find strange or even cause a problem. 2nd encounter: Stop and go traffic, car in front of my slowly changes to lane to the right of me, and the car starts accelerating before the car completely changed lanes- getting me a bit close for comfort to the car. Very weird. 3rd encounter: Car in front of me changes lanes to the left, and car wants to suddenly brake- I hurried and pressed the accelerator, but it was a strange thing that it wanted to brake. Other than that it seemed to do well, it just needs to brake smoother. I guess I can't expect much as it the sensors and computer doesn't possess common sense, like slowing as a car seems to be changing lanes.. just kinda of disappointed and it seems like I am a tester for the technology still.