I agree that the W211 is underwhelming especially those with the M272 motor, my dad just sold his 2007 E350 wagon and moved on to a torque-monster 2013 ML350 Bluetec, way more fun!
I've become so accustomed to the mountains of low end torque the newer diesels and turbo gas motors churn out that anything NA just feels laggy and slow. My e320 wagon with the M112 has been a dependable beater for 5.5+ years but I'll be selling it soon as its just not needed anymore, and absolutely guzzles fuel around the city. It has never broken down but the body is rusting to no end.
Debating replacing it with a ~2014 Sprinter with the OM651
Hard to go wrong with the super long Bluetec scandal warranty coverage on the diesel powertrains now....
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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)