http://www.bmwblog.com/2012/05/25/world-premiere-2013-bmw-7-series-facelift/As long as your car has the the rear air suspension, the suspension is self levelleling and adjusts the height on the rear axle.
The ARS system on the other hand, works by using active antiroll bars to reduse body roll both front and rear.
All BMW 7 Series models are now equipped with self-leveling rear air suspension, which keeps the car riding at a constant height no matter what kind of driving conditions it encounters and regardless of the loads on board. This automatic self-leveling suspension responds to any change in load by adjusting the suspension at the relevant wheel. This means that only small interventions are required in response to spring movements caused by road imperfections and cornering lean. This feature was previously available only on long wheelbase models in the US.