[jacquesm]

All it takes is for a team and their direct managers to collude if oversight and review are lacking. As little as 5 people could have known about this, or possibly it went all the way to the top but given the risks I very much doubt that. It's one thing to have errors or bugs, quite another to deliberately mislead the authorities on a major benchmark for vehicle approval. That's way beyond the gray zone.

[theophrastus]

I reasoned that it would have to be 2 people or else any sensible person would know it would eventually get out. Including the executive who had to achieve some engine performance goal (but couldn't handle the software manipulation), and the software engineer (who wouldn't directly have to answer for engine performance goals)

    "Two may keep counsel when the third's away." --Shakespeare, Titus Andronicus

[marbu]

Given the sheer scale of this, I doubt it is the case.

[jacquesm]

It's just one engine type as far as I can see.

[marbu]

I see the initial code of this hack as just a begining. Then someone needs to test it with actual cars, maybe tweak it a bit and then make sure it gets deployed on the selected car models while assuring it works without breaking anything else. Moreover this hack was in place for few years ... On the other hand I'm not from the industry, so maybe it would be actually much easier.