This might be abit of novice question but im confused as different models come with sort of suspensions with different settings and different issues but all the terms used for them seem to be the same. The one thing i have learned is that the ABC system is quite prone to failure and very expensive to repair. But sometimes iv read its filled with hydraulic oil, others its full of air, so i just want to know what what really. The car im looking at buying is a 2003-2005 S55K. Im sure thats got airmatic, but its also got the ABC button on it aswell. At the same time people are saying that CL500/600's of the same era have ABC which is unreliable!!! Anyone care to break this down for me? Do both systems run alike? And are they both quite unreliable as each other or is the air one any better? Thanks.