As far as "quiet" inside goes....I doubt there is anyone, anywhere who could produce one with an eerie silence that the 500 & 600 140's have! It's a result of two and a half tons of steel, glass, plastic, rubber and whatever else they used, combined with double-pane windows and vacuum seals on the doors. The car, as has been well-referensed (sp) in this respect, is over-engineered...but is in this case better off for it. For those who have not ever experienced this quietness....it is awesome. You have no idea what music sounds like inside of a vehicle traveling down a road at 75mph!

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1996 SL320 97K miles
1996 C220 130k miles
1992 500SEL 170k miles <---sold
1986 300E 216k miles <---sold