Bert, you seem to possess sound knowledge of the situation and are interesting to read, but just once I'd like to read your takes on autos without you inserting your grouchy prejudice against SUVs and trucks. Its gratuitous and unecessary.
Les, the specific problem of limiting NOx emission in diesel engines, with techniques that we know of and are implementing today, goes entirely against what makes diesel engines more efficient than gasoline engines. Limiting the peak temperatures, limiting the duration of peak temperatures, and limiting the amount of excess air in the mixture, is precisely the opposite of what makes diesel engines efficient.
So, if I were a VW owner, I would groan. No, not in jaw-jutting and self-righteous indignation. I'd groan because now my car is likely to get worse fuel economy, be more sluggish, and have a catalytic converter that is no longer maintenance free.
The idea that engineers have to make compromises, either carbon... or nitrides, is totally bogus.
You need to inform yourself, Les. The main pollutants are CO, unburned hydrocarbons, NOx, and now the new one is CO2. To limit CO, CO2, and unburned hydrocarbons, you use techniques that make the combustion process as hot and efficient as possible. To limit NOx, you cannot do this. It's a simple fact. Either that, or you have to eliminate the nitrogen from the intake air, and feed the engine pure O2. Good luck with that.
The idea that someone driving an SUV is just as guilty is nonsense.
Let's be more precise. Moral outrage, from someone who drives one of the aforementioned obscenities, is a sign of both shameless hypocrisy and a good measure of cluelessness too. None of this to excuse the fraud. It's just to put this all in perspective. The heavy and blunt-nosed vehicles pollute more in terms of CO2 emissions for sure (in inverse proportion with mpg), but also the other pollutants:
When I first read about the draconian new emission standards for diesels, my first reaction was, it's probably time to quit making diesels.
The figure of emissions 40x the limit has been mentioned several times above. Also the fact that urea can reduce the NOx emissions around 80-90%. Let's say 85%. That leaves 15% of the original emissions, or 40 x 15/100 or still 6 x the limit.
Maybe that's why VW did it. They couldn't get to the limit so decided they may as well be hung for a sheep as for a lamb??
Bert, I'm one of the morally outraged ones. My favorite car that I've ever owned was a 2010 Golf TDI, it seemed to have everything, comfort, quite reasonable performance, fuel economy... and was supposedly clean.
We, as citizens, and consumers, have every reason to expect, that what we choose to buy reasonably meets both advertising claims, manufacturer's specifications... and mandated safety and environmental requirements.
The idea that someone driving an SUV is just as guilty is nonsense. Regulations, and targets, take into account such vehicles... and the goal is... to get the pollution footprint of the whole fleet, minimized. VW, and who knows what others, can throw a serious monkey wrench into efforts on the whole.
The idea that engineers have to make compromises, either carbon... or nitrides, is totally bogus. When an entity is producing products under a regulated regime, it is incumbent that all criteria are met, unless otherwise explicitly allowed for.