alt Hacker NewsThe ABC system does more than the earlier hydropneumatic systems of Citroen etc. Those earlier systems have a slow response that can compensate for things like ride height, not to actually move the struts up and down rapidly like the ABC system.
For example see the "rodeo test" where the car moves each corner up and down to test the system. ABC involves active feedback control of the body and rapidly adjusts force/displacement of individual struts, just like what the Bose system does with electric actuators.