I've owned an AP2 Model S since May of 2017, and have experienced the evolution of AP2 from drunk teen aged driver to better than I am on the highway, as long as nothing unusual happens. A week ago my car was in the shop for several days and I was given an AP1 P90D loaner (lovely car). So I got to use AP1 for the first time, and here are my impressions. Curves (freeway): Both versions are quite competent lane followers, and each has a flaw the other does not. On sharp curves at speed, AP2 does a noticeably better job of following the lane. Adjustments made during the curve are small, relatively infrequent, and smooth enough as to be almost unnoticeable. AP1 will typically make a few quite noticeable steering adjustments during the curve. These are minor, but much more evident than the AP2 adjustments which seem smaller. Edge to AP2. Merging on ramps: With AP2 in the rightmost lane and passing a merging on ramp, the car seems to think the lane has gotten wider and wobbles to the right and back again as the on ramp marking moves left to be come the rightmost lane marking again. AP1 does not do this at all. Edge to AP1. Vehicle display in adjacent lanes: AP2 shows all vehicles as cars, where AP1 distinguishes between cars and trucks. I've heard motorcycles are also displayed although I never saw that. Both AP1 and AP2 have issues here though. With AP1 I saw cases where the icon would pop back and forth several times per second between car and truck. I think how much one cares about this is pretty subjective. I rate them about equal. And really, none of what is currently displayed in adjacent lanes by either version matters too much to me. But if you gave me views of vehicles to the side or behind that I can't see without turning my head, then I would definitely care. So my subjective evaluation is that AP1 and AP2 are about equal, but I prefer the current AP2 implementation mostly because lane following on curves is so good now. I recently drove I-5 through southern Oregon where it is quite curvy, using AP2, and for the first time felt comfortable letting the car drive the whole way at the speed limit. Always previously there have been places where I was on high alert. So I think there have been some unannounced improvements being made to AP in some of the recent releases.