From Mercedes Wiki

Active Body Control (ABC Active Suspension) was developed by Mercedes-Benz. It is designed to minimize Body roll in corner, accelerating, and braking. The system uses 13 sensors which monitor body movement and vehicle level to supply the ABC computer with new information every 10 ms. The microprocessor then translates this data to tell the electronic servos (1 per wheel) how to respond. ABC made its debut in the 2000 CL500 model. Its availability remains limited, it is standard or optional only on the S-Class, CL-Class, and SL-Class models.