Re: Interesting justification.
2. The combination of fuel, air and temperature that maximise the power and minimise fuel consumption are not so great when it comes to NOx.
Not so. NOx is only a problem when you're burning very small quantities of fuel in lots of air, such as when idling. That is done to minimize fuel consuption when you don't need power, such as (for example) during some phases of the unrealistic emissions test cycle.
If they just tuned the cars to give decent power and fuel consumption during normal driving they wouldn't encounter the situation where the cheating was required. But then the eurocrats wouldn't be able to claim that they'd done something useful by imposing standardized tests