Active Body Control, or ABC, is the Mercedes-Benz brand name used to describe electronically controlled hydropneumatic suspension. This suspension combines a high level of ride quality with control of the vehicle body motions, and therefore virtually eliminates body roll in many driving situations including cornering, accelerating, and braking. Mercedes-Benz has been experimenting with these capabilities for automobile suspension since the air suspension of the 1963 600 and the hydropneumatic (fluid and air) suspension of the 1974 6.9. ABC was only offered on rear-wheel drive models, as all-wheel drive 4MATIC models were available only with Airmatic semi-active air suspension, with the 2019 Mercedes-Benz GLE 450 4MATIC being the first AWD to have ABC available. The production version was introduced at the 1999 Geneva Motor Show on the new Mercedes-Benz CL-Class C215. Description In the ABC system, a computer detects body movement from sensors located throughout the vehicle, and controls the action of the active suspension with the use of hydraulic servomechanisms. The hydraulic pressure to the servos is supplied by a high pressure radial piston hydraulic pump, operating at 3,000psi. Accumulators regulate the hydraulic pressure, by means of an enclosed nitrogen bubble separated from the hydraulic fluid by a membrane. A total of 13 sensors continually monitor body movement and vehicle level and supply the ABC controller with new data every ten milliseconds. Four level sensors, one at each wheel measure the ride level of the vehicle, three accelerometers measure the vertical body acceleration, one acceleration sensor measures the longitudinal and one sensor the transverse body acceleration. As the ABC controller receives and processes data, it operates four hydraulic servos, each mounted on an air and pressurized hydraulic fluid strut, beside each wheel. Almost instantaneously, the servo regulated suspension generates counter forces to body lean, dive and squat during various driving maneuvers. A suspension strut, consisting of a steel coil spring and a shock absorber connected in parallel, as well as a hydraulically controlled adjusting cylinder, are located between the vehicle body and wheel. These components adjust the cylinder in the direction of the suspension strut, and change the suspension length. This creates a force which acts on the suspension and dampening of the vehicle in the frequency range up to five hertz. The system also incorporates height adjustable suspension, which in this case lowers the vehicle up to between the speeds of for better aerodynamics, fuel consumption, and handling. The