In reply to Pedro50:
> > Your mileage may vary etc...
> Thanks. Are you implying mpg may decline?
"Your mileage may vary" has been a standard form of words on the Internet dating back to Usenet days. It simply means "your experience may not be the same as mine". It is often abbreviated to YMMV. (I believe it derives from car adverts in the US where mpg figures would be quoted with that caveat.) I don't think that robhorton meant it literally in this instance.
https://en.wiktionary.org/wiki/your_mileage_may_vary
I'm not going to have the fix done to my Yeti - I will make a point of telling the dealer
not to do it when the car's next service is due. AFAIAC the car runs fine. The cheat is all about making the car do odd things when placed in the artificial situation of the laboratory emissions test. It's entirely unclear whether it makes any difference in real world driving. It's generally recognised - with supporting data collected by regulatory agencies and academic institutions - that the laboratory emissions tests aren't a good guide to emissions in real world driving. (But that didn't stop a recent shock horror "VW cars that have been fixed still emit high levels of NOx" story appearing in at least one newspaper recently. Next week's exclusive revelation will presumably centre on the defecatory habits of bears. Or Popes. I lose track sometimes. Aaaanyway...)
I've seen it asserted that the cheat wasn't even required to pass the EURO 5 test, only the more stringent US test, but VW were told to take it out anyway because it shouldn't have been there at all. (This reminds me of Bennetton's launch control software that was "present in the ECU but not activated" - they got away with that.) I've also seen it said that many of the faults that people report are due to poor implementation of the fix, and at least one reference to a key step often being missed out (this latter from a Yeti owner who had problems after the fix, who then found a mechanic who knew how it should have been done and got the car working properly again - yeah, I know, it's only anecdotal.)
As my car runs fine, and I've no evidence or reason to believe that the fix will make any difference to its emissions in day-to-day use, I am taking the stance of "if it ain't broke, don't fix it".
I doubt whether not having the fix will make much difference to a car's resale value. It might even
enhance its appeal to buyers who are paranoid about the fix. Anyone who buys an 'unfixed' car can get it done for free by a dealer if they want to. (My understanding is that any second hand vehicle sold through the dealer network will be fixed before sale.)