Mythbuster: do adaptive dampers always need to... adapt?

Myth: “adaptive dampers always need to adapt”

If you're driving along a straight stretch of road at moderate speed and you switch the adaptive dampers from comfort to sport, nothing should change. Not if the dampers are truly adaptive. Because in a straight line they shouldn’t need to firm up (at least if the car isn’t heaving and pitching excessively).

But they nearly always do. Because going straight and gently is the exact circumstance when you can most easily look down and find the button or screen menu. So the engineers know that you’ll want to feel a difference, justifying the money you spent on the option.

Adaptive dampers, see, adapt. The clue’s in the name. If they have no need to be stiff, they should remain soft, as on a gently straight road. Then when you turn the wheel or brake or accelerate, they should stiffen up to control the body movement. They should also quell float over a crest or dip. They can even influence understeer or oversteer as you turn into a corner: if the rear ones firm up before the front ones, that’s the equivalent, for a brief time, of a stiffer rear anti-roll bar, which quells transient understeer. Vice versa for the front ones.

And in fact they can do this perfectly well without a mode switch. Their various sensors will feed into a map of bounce and rebound stiffness that’s right for any circumstance. The thing is, ‘right’ is a matter of preference, hence the mode switch. Different drivers can choose a different map: comfort or sport or indeed track mode. Because yes, ‘right’ is also a matter of circumstance and on a track almost anyone will trade a bit of ride comfort for better control.

All maps should be able to soften themselves off fully on occasions. Just less often and for shorter intervals if you’ve selected a more sporty map. But as I say, you can sense that many cars don’t do that.

Their engineers call it the ‘marketing switch’: drivers don’t understand the purpose of adaptive dampers and can’t sense them working, so they think the sport button should mean harsh always.

BMW for many years had a subtle trick to get round the issue. When you pressed the sport button the dampers would firm up by a double extent for 30 seconds, then gently relax back to the setting the engineers believed correct. Which was a firmer map than ‘comfort’ but not that firm.