Diesel emissions are exaggerated. European emission standards set limits for diesel emissions that are just minutely different from gasoline emissions.
American limits for diesels are notorious for being more restrictive than for gas engines.
All of that considered, diesels are plainly more economical and more efficient on pretty much all common engine size ranges
First off, the big problem with diesel is not CO2, but NOx gases, which are way more immediately dangerous to human health. That's why some cities are thinking of banning them ASAP right now.
Second, besides VW which was creating even 40x the emissions than the standard you mentioned required, pretty much all the other car makers were creating 10-15x as many emissions, too, thus making that "strict standard" way looser. Forget Euro 6 or Euro 5. These cars weren't even compliant with the 25 year old Euro 2. In other words, all of these car makers "passing" the emissions tests over the past two decades has been all a bad joke played on the EU population.
Finally, a new stricter (than Euro 6) standard was supposed to arrive by 2021 or so, but Merkel once again intervened to make the standard even looser (by +50% more emissions allowed) than the previous one, which would be a first in the history of the Euro emissions standards, which have become increasingly stricter not looser, so far. All thanks to Merkel.
The industry was promoting the Diesel also with the smaller CO2 emissions of this engine.
The other negative effects of the Diesel boom was very visible for a long time and politics and authorities were ignoring it.
Merkel (and her coalition partner the CSU) is especially responsible for having a very weak minister Dobrindt, who was not willing or able to guide the automotive industry.
Merkel and the government is a part of the problem, but the automotive industry and the consumer is even more so. The automotive industry promoted the Diesel engine and the consumer bought especially the high-powered ones. The government is responsible for low Diesel taxes, supporting large company cars and a lack of regulation.
Diesel emissions are exaggerated. European emission standards set limits for diesel emissions that are just minutely different from gasoline emissions.
American limits for diesels are notorious for being more restrictive than for gas engines.
All of that considered, diesels are plainly more economical and more efficient on pretty much all common engine size ranges