I think you are a bit confused with options and what was offered for 2016, there are 3 different options we are talking about here from your build list, I don't have a 2016 build guide but according to 2014 version:
ZDA- Driver assistance package includes rear view camera and head up display.
ZDB- Driver assistance plus package includes blind spot assistant, surround view, speed limit and sign detection and comes with 2 options 5AT or 5AS. You have 5AT which adds Active Driving Assistant (includes Lane Departure Warning, Forward Collision Warning,
Pedestrian Warning, and City Collision Mitigation) plus ACC Stop & Go (adaptive cruise control which can also brake in case of obstacles or pedestrians ahead) and option 5AR (Traffic Jam Assistant) can be retrofitted.
The feature you are asking for was not really available on F15, you can only get the active steering with traffic tam assist retrofit described here:
https://f15.bimmerpost.com/forums/sh...d.php?t=875827
And then you can code it to higher speed even it was not eventually made for it and originally was limited to 37 mph. So the answer to your question is:
This car AS IS can not actively keep your car in lane even with adaptive cruise control no matter how fast or slow you are going, but since you have ZDB+5AT you can retrofit 5AR and code it to higher speed. I hope this is not too long to read and makes sense. :-)