Süddeutsche Zeitung reports (article in German) about German car makers, German politicians and Science clashing, hard.
So recently it was found that under non-lab conditions Euro 5 and Euro 6 Diesel cars are actually emitting more NOx than Euro 4 Diesels. In fact, they are a factor of six to seven over the limits.
That’s kind of a problem, because in cities like Stuttgart (a classic german car maker city, by the way) there are literally hundreds of days in a year where these cars by European and German law have to be banned from entering the city. Which is kind of making the cars pretty worthless, which in turn won’t make the politicians seen as being responsible for this happening more popular.
On the other hand making exemptions for these cars also won’t work, because there is a risk that people die from car exhaust and their relatives or somebody else is going to prove pollution as actually being the cause of that, in which case the politicians legalizing these things also won’t be popular, or worse, might even end up in jail.
And the third option, finding a piece of magic science that does make these cars cleaner, seems to violate the laws of reality and kind of eludes everybody. Especially if additional constraints are being added like “Can’t cost another 5000 Euro”, “Can’t reduce the acceleration of the car noticeably” and “Must not worsen fuel efficiency”.
TL;DR: Everybody is unhappy, no magic unicorns available to make the Diesel problem go away.