In Germany there are rumors going around, that not alone VW did cheat at those emission tests and not only at those tests. And the rumors are around for a long time now.
It is a well known fact, that in the EU, the emission tests used in the EU are absolute ridiculous (not only the NOX-tests -- all of them). They are totally artificial, so that they have nothing to do with normal car usage. But they are still used. The reason is, that particularly the German government are blocking all initiatives to change them. This does suggest, that they know about the cheating or at least where influenced from the big car industry. The German car industry is very influential in Germany.
Also it is a well known fact, that the gap between the official fuel usage figures and the fuel usage experienced in real world situation is growing and growing for many (maybe most) car brands. I would say, this is the same thing, because those numbers are determined by tests operated by the manufacturers -- and they are also artificial test situations like the emission tests. Officially, the fuel usage of new cars was reduced very much, but some say, that the real numbers have maybe even growing instead.
All this is known for years, if not decades.
Because of the the German government, the EU still takes a blind eye on this.