This is meant as a follow-up to my earlier thread, AP2 / 8.1 Test Drive Perspective from AP1 Owner I now have 3500 miles on my AP2 S100D, including ~1000 miles driving from SJ to Las Vegas this past weekend. I've made this trip 8 or so times with AP1, and this is my first time with AP2, on 17.17.4. Overall, 17.17.4 feels very solid and great for long-distance highway travel. The trip felt a lot like it did with AP1, and for really the first time with AP2, I feel like there's situations that AP2 handles better than AP1 as well as vice-versa! ----- I'd first like to update a bit on my original impressions now that I've had a month with the car to understand it better: - With 17.17.4, the sudden overpass braking is basically gone. I experienced 2 cases in unfamiliar areas where the car started coasting and gradually slowing down approaching an overpass (generally, it's a hill leading to an overpass so it looks from a 2-D perspective like you are driving into the overpass). It wasn't scary at all, and lightly tapping the accelerator snaps the car out of it. - One thing that I understand better with more miles: AP2 is more likely to get confused about cars in adjacent lanes. If you are in a carpool lane driving 50mph and the lane next to you is at a standstill, once in a while, AP2 suddenly believes a car next to you is in your lane, which can result in sudden braking. This behavior was far worse on 17.4.x/17.11.x, and is much much reduced on 17.17.11, but still not entirely gone. It seems like there's a fundamental limitation of AP1/2 where the car makes a binary decision: Either a car is in your lane, or it's not. As humans, we understand when a car gets close to your lane, and we drive offset in our lane to compensate for it. It seems like as AP2 gets more mature, to handle this situation it really needs to understand how to proactively offset itself when driving next to really slow traffic. While the AP1 behavior is less annoying, I cannot say it's safer. I've had numerous occasions where I felt like my AP1 car would've clipped a car that strayed into my lane, had I not intervened. This is a ton improved in 17.17.4. When AP2 is driving on straight roads, it no longer shuffles constantly in the lane. These statements still feel largely true. 17.17.x improved the behavior going through intersections a bit, but not much. AP2 is still very erratic when the lane lines disappear for a while. Especially if the road curves. And I rarely see the "blue car" following mode on AP2. Most of the times, AP2 feels dead confident about the lane lines, even when it really shouldn't be, and the car in front is doing the right thing. ------ But notes from my trip: - Truck lust is GONE! Long live AP2! On I-5, I would say 17.17.4 was more relaxing compared to AP1. For those who are not familiar: I-5 is an industrial corridor with 2 lanes in each direction. The right lane is filled with large trucks transporting goods between NorCal/SoCal, and the left lane you pretty much have to drive at 75-80mph (10-20mph faster than the trucks) to avoid being tailgated or being discourteous to a faster driver. With AP1, quite frequently when driving next to a truck, AP1 would lose the lane line between you and the truck, and the car will suddenly make a steering adjustment into the truck. With AP2, I'm finding the lane lines stay solid regardless of trucks, and the car no longer suddenly changes lane position when passing trucks. - "Improved ultrasonics" do a slightly better job of detecting cars and barriers. But it's a subtle improvement — I would say around 10-20% better (1-2 feet more detection range). This is more reassuring when driving alongside another car, because the screen will show you that AP2 does see the car next to you, which provides some reassurance that your car will maintain its distance. - As mentioned above: Overpass braking seems gone. Overpass "coasting" happens extremely rarely. - When the road is straight or nearly straight, AP2 performs extremely well. I used it on undivided country roads as well as freeways. It stayed firmly planted in the center of the road. - Curves are still a bit dodgy with AP2. It's almost as if AP2 has really conservative caps on both the max steering angle and the max turning rate of the wheel…. Around more than shallow curves, it does not take the curve sharply enough, which results in departure of the lane. But you can see from the screen, the car is very aware that it is exiting the lane! I hope this is just a matter of tweaking some steering parameters in a future update. - Hilly roads with slight curves used to be pretty bad for AP1, but on AP2, it's handled quite well! I feel like as soon as they fix the above problem with AP2's steering aggressiveness, AP2 will perform very well on hills compared to AP1. - Bug/Feature: On completely unrecognized stretches of road, AP2 seems to assume no speed limit on 17.17.x, and allows Autosteer to be used at up to 90mph. This is contrary to the release notes, which implied that the speed limit is 45 if it can't be detected. This came in super handy, because the stretch of CA-58 between Bakersfield and Mojave is all new construction, and easy for AP2 to handle because it's mostly straight. Overall, though, I'm glad I waited until 17.17.4 to take this trip. It was basically as relaxing as AP1. AP2 handled some situations better than AP1, and AP1 handled other situations (sharp turns on leveled roads) much better than AP2. But given that most of the challenging parts of this route are winding mountain passes (curves + hills), both AP1 and AP2 required manual steering for those challenging sections, so it was really a moot point which system was slightly less scary. But a key point of AP (1 and 2) was that it made 100+ miles of monotonous driving down I-5 and the Mojave Desert basically effortless. So when it came to a mountain pass, I felt refreshed and ready to take over the steering, as opposed to fatigued from making micro adjustments to the steering for 2 hours before that.