the adaptive suspension on this car is the only option i ordered and entirely because of the development effort put into them. for example the required damping and rebound force is measured and adjusted at each corner 400 times every second. on a 2 minute lap the suspension has adjusted 96000 times. i think its hilarious to compare the passive system as being the middle setting on the M adaptive suspension.
http://f80.bimmerpost.com/forums/sho...php?p=16219521
read that article if you haven't already. i only scratched the surface. no need to repeat.
as far as being limited to lowering the car the new KW HAS is designed to work with adaptive suspension. i will be comparing it to oem springs on various conditions including track in the next few weeks.
I drove an M4 with both passive and adaptive suspensions on the track. subjectively i really couldn't tell which suspension was faster as I wasn't there for that purpose. the car is fun to drive either way. where i notice real world the adaptive suspension really working is on highways and rough patches of road in and around the city at all different speeds. even on sport+ it does not feel overly damped. particularly in inclement weather the car feels very planted as well.
so if you plan to drive anywhere that may have an unplanned variance then i would say its likely the adaptive suspension will outperform the passive system. as for a fixed rate adjustable coilover compared to the adaptive suspension i will still say i highly doubt it will improve lap times and then you still variance in every lap you drive regardless of how much you know that particular track. just hit the sport+ button and done.