I'd still question whether there's actually a problem at all; for a 175K car those numbers sound pretty good to me. If MB should run significantly tighter than these results, I'd be eager for one or another of our valued gurus to shed light on appropriate standards.
'97 SL500, 40th anniversary edition
'04 Olds Bravada (SWMBO's)
'06 Lexus ES330
'89 560SL (sold)
SL--Anything else is just a Mercedes.
(Kudos to whoever said it first)