There is a lot of confusion about whether a Mercedes S or CL-class has Active Body Control suspension or just standard Airmatic (air ride). The biggest difference is that the standard Airmatic suspension runs on air, whereas ABC runs on power steering fluid supplied by the power steering (tandem) pump and does not run on air at all. The car will have one system or the other, not both.
A couple of ways you can identify ABC vs Airmatic:
1. ABC cars will have a button marked "ABC Sport" on the center console, whereas the standard Airmatic suspension has a button has a picture of a spring with arrows.
2. Airmatic struts will have white plastic tubes running to the top which can be seen under hood