My dad's M116 in his 420 is original other than the valve guides/seals and a timing chain, still runs great at 305k+ Its all about maintenance.

I alllmost bought an E320 wagon recently but decided not to due to their fuel consumption and complexity. Ended up with a '13 TDI sportwagen 6-speed. Awesome vehicle. If MB would release a diesel C-class or E-class wagon here I'd have likely gone that route. The W203 C220 cdi we had in germany on a trip was awesome...too bad its not sold here.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)