In my experience, the two most common problems with the Air-Matic system are failed compressors, and leaky front struts. The struts can be repaired inexpensively ($300-400?), but the compressor will set you back about $1500? In many cases, the leaky struts cause the compressor to work overtime to meet the air demand, resulting in premature compressor failure, so having the struts inspected for leaks can save S-Class owners a costly headache. The inspection only takes a few minutes under the hood, but you've got to know what to look for. Sorry, but I'm not sure of the exact cost, since I let the Service Advisors work up the estimates. My job is to make sure the car is fixed correctly. I hope you find this information helpful.