In the U.S., the Volkswagen diesel scandal was a case of an automaker betraying the trust of more than half a million owners.
But in the Europe, the issue of diesel emissions looms far larger yet.
Diesels have represented roughly half of European car sales for decades, their good fuel economy being an asset in a region with very high fuel prices.
Now, though, policymakers are confronted with severe air pollution in major cities—and serious questions over whether automakers are willing to make their diesels compliant with stricter emissions standards.
Or even capable of doing so.
That combination of factors has led to a bold prediction: diesels will go from representing around half of European new-car sales to near zero in around 10 years, argues a recent Bloomberg piece.
2010 Volkswagen Golf TDI
While the Volkswagen scandal highlighted the issue, the gap between real-world emissions and results from laboratory testing has been a problem for years.
Since 2010, European automakers have sold more than 30 million vehicles that emit levels of nitrogen oxides three times above legal limits, according to advocacy group Transport & Environment.
A recent T&E study found that every automaker selling diesel cars in Europe surpassed emissions limits—and that VW wasn't even close to being the worst offender.
ALSO SEE: Every diesel brand in Europe emits more than VW, says new report (Sep 2016)
While Volkswagen diesels averaged emissions two times the legal limits, those from Fiat Chrysler Automobiles and Suzuki registered emissions up to 15 times as high.
It's been known for some time that European testing procedures aren't very realistic, but regulators plan to add an on-road testing component in the wake of the VW scandal.
That, combined with stricter emissions standards, has many automakers contemplating diesel downsizing.
2017 Fiat 500L
In January 2015, the European Union began phasing in Euro 6 standards, equivalent to those in place in the U.S. since January 2008.
FCA CEO Sergio Marchionne recently said that transitioning 80 percent of the company's diesels to Euro 6 standards will cost over $500 million, and that stricter standards may soon make diesels financially impractical.
MORE: Mayors of 4 capital cities to ban all diesel vehicles by 2025 (Dec 2016)
Even if automakers can consistently meet the stricter emission limits, they may face a European public that is less receptive to them.
Last month, Oslo banned diesel cars from its streets for two days, and in December the mayors of Athens, Madrid, Mexico City, and Paris vowed to ban diesels from their jursidictions by 2025.
Eiffel Tower in Paris, France (photo by Rijin, via Wikimedia Commons)
Paris already bans most older cars from entering its city center on weekdays, and the French government has discussed eliminating the tax incentives that help make diesel cars substantially cheaper to own than gasoline cars.
The end of the European love affair with diesel cars would represent a major turnabout.
Considering that diesels have been far more popular in Europe than just about anywhere else, it could also portend the end of mainstream diesel cars as a whole.