They look like they'd be ultimate diesel cross country cruisers. I have an '07 S550 4matic. Great highway car. The W221 is great chassis. Be aware, some of the systems are very expensive.....air strut is $1500 each I believe. Set of tires is $750 plus. They historically have depreciated steeply. Definitely do your due diligence/ pre-purchase inspection.

I think if I were buying a newer diesel, I'd opt. for the E250 with twin turbo I4 2WD version. Not as big or luxurious, but easier to drive in town and get's phenomenal mileage.

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-- Chris

'95 E300, 216k miles, Silver Surfer
'05 E320 CDI, 138k miles
'07 S550 4matic, 69k miles

Gone but not forgotten:

'76 300D, 350k miles?, SOLD in 1995
'75 240D, 300k miles, SOLD in 1991