[jhbodle]

I have the Adaptive M Suspension on my 125d and when I press the Sport button I can feel the steering get heavier and the throttle get sharper, but the suspension doesn't really feel any different. I would say it feels maybe 5% stiffer, if any.

Should there be a noticeable difference in ride quality / stiffness when this button is pressed (ie is mine broken)?

[johnnydad]

Yes, you should notice a difference but of course it is only changing the damping rates, not the springs and further as the damping is Adaptive is varies a bit with speed and conditions anyway. So sometimes you can switch back and forth and think there's little in it, whereas at other times the change is more marked.

I find the most obvious differences are with low speed primary ride control - so try a large speed hump at, say, 25km/h in Comfort and it feels almost disturbingly underdamped - floating at the top of its travel and having a two-phase soft bob as you come off the other side. The same bump in sport has it crest and settle much more sharply, without any float or bob. Otherwise, drive along a chopped up bit of road and switch and the ride should feel flatter and with a bit more harshness transmitted - like you added 10psi to the tyres.