The European Commission launched legal action on Thursday against authorities in seven EU nations including Germany and Britain for failing to crack down on emissions cheating exposed by the Volkswagen "Dieselgate" scandal.
The commission, the EU's executive arm, "is today acting against seven member states on the grounds that they have failed to fulfil their obligations" under EU law, said a statement.
The Dieselgate scandal blew open when Volkswagen admitted in September 2015 that it installed software in 11 million cars worldwide that reduced emissions of harmful nitrogen oxides when it detected the vehicle was undergoing tests.
Brussels drew sharp criticism for failing to act against Volkswagen compared to the US, where authorities not only exposed the wrongdoing, but secured a $16.5-billion (14.8-billion-euro) settlement from the Germany-based automaker.
But the Commission lacks the authority to fight Volkswagen. Day-to-day regulation of the auto sector, including approving new car models for the road, remains under the authority of national governments.
"Abiding by the law is first and foremost the duty of car manufacturers. But national authorities across the EU must ensure that car manufacturers actually comply with the law," said EU Industry Commissioner Elzbieta Bienkowska.
The commission's so-called infringement procedure is the first step in a long legal process that can see member states sent to EU court for breaking European law.
Germany, the bloc's most powerful nation, is accused of failing to apply the appropriate penalities when faced with proof of cheating by Volkswagen.
The commission also accuses Germany, along with Britain, of not turning over to Brussels evidence found in national probes of Dieselgate.
Other countries facing the EU's infringement action are the Czech Republic, Greece, Lithuania, Luxembourg and Spain.
The Dieselgate scandal exposed that some VW cars spewed out up to 40 times more harmful nitrogen oxide -- linked to respiratory and cardiovascular diseases -- than legally allowed in the EU.
The European Environment Agency said in a 2015 report that nitrogen oxide was responsible for around 72,000 premature deaths in Europe.
Still, one year after the scandal, nearly 30 million cars on Europe's roads were still way over air pollution limits, campaign group Transport and Environment said in a report in September.