The car ships with a fully adjustable KW coilover setup, which owners cite as part of what makes it special and which supports different spring rates rather than being a simple lowering kit. One long-term owner reports the rear KW bump stops deteriorate over time (independent of mileage) into 'cornmeal' and cannot be rebuilt; another owner disputes this as track/lowering-induced rather than universal, making it a point of genuine disagreement.
KW coilover suspension and bump-stop wear
Mercedes-Benz CLK63 AMG Black Series (C209) · mechanical