It's relatively simple. If you have AdBlue, you pretty much eliminate NOx. PM2.5 should be fix-able with either filters or driving the engine iirc more lean, to

It's relatively simple. If you have AdBlue, you pretty much eliminate NOx. PM2.5 should be fix-able with either filters or driving the engine iirc more lean, to incentivize full combustion. That might increase the use of AdBlue required, but I am not sure. If I were driving, I'd look for a car that, based on my own testing (e.g., during a test drive at the dealer), measures sane emissions and drinks AdBlue. But for all I know, such a car does not exist. I really wish they make them take all the dirty cars from the streets, mandating a retrofit AdBlue system to allow them back onto the street. With an allowance for those that have an AdBlue system already to measure at a test drive, i.e., with a probe shoved up the tailpipe, and the mechanic/owner driving a loop around the block or so, maybe with some mandatory measuring for the first 100km after installation or so, and if the car at any point during this fails the standards, don't allow it back on the road. The effect from this would be that teaching the car to cheat would be next to impossible, especially if you could mandate another test e.g. at any point between 10000 and 15000km, as best fits the owner schedule. While it should be possible to engineer a cheat for this, it would be hard to conceal as an accidental bug, which would be what they'd have to make it look like to avoid potential criminal liability (they could certainly create suitable criminal statutes along with the testing requirements, and make sure these hit those that actually do it, along with everyone up the chain. Make it conspiracy or so, and catch all at once. Some prosecutor would have a lot of fun.)