To be clear, it's not that VW was able to get wildly better figures than competing companies, it's that, in one engine map, they get NOx emissions levels that are around the same as other companies (i.e. it meets emissions criteria). Then, in another engine map, when it only uses when it suspects it isn't being tested for emissions, it runs a different fuel/air mixture that allows increased economy (which might only be a 10% improvement or whatever), but at the expense of severely increased emissions.

Other companies running the same sort of emission map that optimizes for fuel efficiency at the expense of all emissions would get similar figures of 40X for emitting way too much emission. VW is the main one we're aware of that's cheating in this manner.