E250 most likely has a bluetec/adblue system on it, and definatley does if its in North America. Same engine I have in my GLK250, an OM651. The bluetec system can have issues, but so can anything on any car. I've had mine about 22k miles and its been great other than a few sensor issues (and a DPF under warranty). I blame the DFP on my car's prior life of hanging out in Chicago traffic for 65k miles though.

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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)