When the soot gets burned off during a DPF regen, the end result is a little bit of ash, which ends up accumulating in the DPF over time. Normally to reach "capacity" this should take in excess of 100,000 miles for a car driven a normal driving cycle. Even if the DPF costs $950-1600 or thereabouts if it has to be replaced entirely.....that cost over 100,000+ miles is pretty small....not even 1.5 cents per 100 miles driven.

The adblue fluid also lasts for ages. My GLK seems to only use about 5-6 gallons per 15,000 miles....less than $25 worth (from the dealer)

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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)