Re: That was never the test
"But nobody else actually changed how their engines ran based on whether they were actively being tested."
You didnt watch that video did you?
The bit where the Zafira reduces adblue injection when its going faster than the max test speed, or outside the testing temperature window, or as you mentioned altitude if its being driven at a higher altitude than the highest European testing station or reducing the amount of EGR if accelerated harder that than required for the test (which is fine as EGR works best at low powers) but keeping it reduced even after returning to normal lower power use.
This isnt changing how the engines run if they are being tested?
The rest of your reply suggests that the only data that counts is the test data and "It is meaningless to compare the emissions in unknown conditions to the emissions in specified conditions." that's exactly how the manufacturers view it too, which is why they are all on the fiddle with the engines behaving nicely under the test conditions and turning off or reducing emissions features when they aren't operating under conditions that correspond to testing.
There is a very nice slide at 50m45s showing the results of testing the Zafira with a portable testing system in real world use with both the old cheating software, and their revised not cheating software after Germany had some stern words with them , its almost miraculous.
(it will use more adblue though)