On Tue, 29 Sep 2015 17:15:02 +0100, John Rumm wrote:

One article I read said that most diesels in the US use urea exhaust
treatment, but VW did not include that on the 2.0 TDIs making out they
have superior engine tech that did not need it. Of source that engine
tech (just more exhaust re-circulation during "test" mode ?) was not
active in normal driving.

I also heard it reported that they did include Urea treatment, but it
was switched off during normal driving so it would not run out.

Not sure which is correct.

Could be both... IIUC some of the later model 2L engines do have the
urea treatment system, while the earlier ones were claimed to not need
it.

The engines in question are Euro V in Europe, and were in production from
2009 on - they've been discontinued in Europe now.

AdBlue has basically only come in with Euro VI, legal requirement from
last year.