Went on a short drive on 2019.20.4.1 in the 3 (AP2.5). Seemed almost the same as 20.2.1 to me, though it ran wide on the freeway exit and over the lane line. You would think they'd have that down by now. 20.2.1 used to come a little close, not centered but not over the line. Lane changes were maybe a little crisper. It didn't slow down when changing just behind another car. Instead, it made the change and then slowed slightly to build the desired spacing. That was a first for me, but I'm not a frequent driver.