Go to this thread where you can see a chart and read the discussion
http://f15.bimmerpost.com/forums/sho...d.php?t=913797
Active Steering changes the steering ratio so that you need fewer turns of the wheel at slow speeds (to make parking easier) but then makes steering tighter at higher speeds.
I have it on my E70 and it is a great feature but seems less needed on the F15 with electric steering versus the E70 steering (heavier). Just my 2c on Active Steering.
Good luck.