Re: VW's billions...
Perhaps city buses with heavy diesel engines.
Err... Most of these already run adblue so they are fairly NOx clean compared to cars.
It is possible to make them even cleaner on other parameters (soot, etc) too. The tech has been well tested and is used extensively around Europe. It is called diesel fumigation - adding a small amount of LPG to the injection flow (AKA diesel blanco, etc). It is used on boats, buses, etc worldwide.
It improves fuel efficiency, reduces particular output roughly by an order of magnitude (before any filters take effect), but as with anything which improves diesel efficiency it also raises the NOx. If you are already adding "piss" to the exhaust that does not matter, you just adjust the amount of piss to add. It is also retrofittable.
The problem is that some governments like UK are so oil revenue addicted that they will do no anything to disallow a massive step-decrease in fuel consumption so you cannot get a fumigated diesel past a MOT in the UK and similarly, the LPG conversion guys are not allowed to do fumigations except on boats.
So the article is incorrect. You _CAN_ get a diesel to emit less off everything compared to gasoline on any metric, you just have to make it even more complex. You will be looking at 3 tanks - diesel fuel, LPG and Piss (adBlue). Similarly, if you are looking at pollution efficient vehicle that burns stuff, LPG _WITH_ adBlue is way ahead of gasoline too (switching to LPG raises NOx quite a bit). Gasoline trails all of them and once you take into account everything that is available for pollution reduction it is not any better.
Biting the hand that feeds IT
