Even before the Volkswagen diesel scandal, diesel passenger cars were never popular in the U.S.
But in other parts of the world—especially Europe—diesels have been the de facto choice of many buyers for decades.
Increasing concern over air pollution and the VW scandal are beginning to change that, though.
The mayors of Athens, Madrid, Mexico City, and Paris now say they plan to ban all diesel cars and trucks by 2025.
The agreements to ban diesel vehicles were made at the biennial C40 meeting of city leaders in Mexico, according to the BBC.
There is also a campaign in the U.K. to get London's mayor to sign on to the diesel ban, the British news organization said.
As well as banning diesels, the mayors agreed to "commit to do everything in their power to incentivize the use of electric, hydrogen, and hybrid vehicles."
The move was reportedly made mainly out of concern for emissions of both nitrogen oxides (NOx) and particulate matter (PM).
Both pollutants can be drastically cut by selective catalytic reduction (also known as urea injection) exhaust treatment systems, which have been commonplace in the U.S. since a strict set of emissions standards known as Tier 2, Bin 5 was enacted in 2008.
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But these systems are only arriving in European-market cars in large numbers now, to allow them to comply with the Euro 6b standards that take effect January 1.
The campaign about against diesels represents a major turnaround for the European cities.
Diesels were previously promoted by European governments because of their low carbon-dioxide emissions, and because their generally high fuel economy helped offset high fuel prices.
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That was the case particularly in France, the capital city of which is now taking some of the most aggressive measures to curb diesels.
In July, the city banned most cars made before 1997 from entering its center, on weekdays, although an exception was made for what are deemed "historic vehicles."
Mayor Anne Hidalgo has said she would like to ban all diesel cars from Paris streets, and is reportedly considering a ban on all internal-combustion engine cars registered before 2010, to be enacted in 2020.
Paris has also enacted temporary bans on internal-combustion cars, limited to certain areas of the city.
It's worth noting that the French capital has many alternatives to driving, including a robust public transit system, bike sharing, and even the Autolib electric-car sharing service.
Other cities don't yet have this infrastructure in place, which could make bans on a large swath of vehicles more difficult to implement.