[Gay State Conservative]

The DEF urea (aka “cow piss” to industry insiders) is about 12 bucks a gallon at WM. Similar to motor oil prices. On big rigs it is consumed at about 2% rate of the diesel fuel consumed. Not sure about the VW.

No,it's $12 for a 2.5 gallon jug.And my car gets about 18K miles (mostly highway) on a 6 gallon tankful of DEF.I just refilled mine for the first time in August.And,IIRC,the Golf TDI (unlike several TDI models) doesn't require it.

[nascarnation]

That seems real reasonable.
You can put a couple gallons at each oil change and it’s just a bit of extra maintenance.

The stuff is pretty corrosive, we had to plumb our lab with stainless steel to port it to the test engines when we started running 2007 compliant engines.