Thirteen million diesel cars producing “extreme” levels of toxic air pollution are still on the roads in Europe and the UK, according to a report, seven years after the Dieselgate scandal first exploded.

The non-profit research group, the International Council on Clean Transportation (ICCT), revealed in 2015 that many diesel cars were highly polluting, emitting far more nitrogen oxides on the road than in official testing. The scandal led to a more rigorous test being introduced in the EU in 2019.

However, based on extensive testing evidence, the ICCT has now revealed that about 13m highly polluting diesel vehicles sold from 2009 to 2019 remain on the roads. A further 6m diesels have “suspicious” levels of emissions, the ICCT said. The cars span 200 different models produced by all the major manufacturers.

The ICCT said the bestselling models from 2009-2019 in the EU27 and UK with “extreme” emissions are Euro 5 versions of the VW Passat and Tiguan, Renault Clio, Ford Focus and Nissan Qashqai.

The test data analysed included official government testing, independent measurements using equipment attached to exhausts and roadside measurements of the real-world emissions of vehicles as drivers passed by. The latter, comprising700,000 measurements in five European countries, showed that about 75% of diesel engine types exceed the “extreme” threshold.

The EU has set increasingly strict limits for exhaust emissions over the last three decades, with manufacturers meeting these by adding new technologies to all vehicles. The ICCT claim it is “almost certain” that cars with “extreme” emissions were using a defeat device, a piece of software that alters or deactivates the vehicle’s emissions technologies under certain conditions.

Rulings by the court of justice of the European Union (CJEU) since 2020 have clarified what constitutes an illegal defeat device, and the testing data, plus documents submitted by some manufacturers to governments, suggest many models still have these.

Environmental law charity ClientEarth and other groups have used the new ICCT evidence to send legal complaints to the UK, French and German governments, saying they have failed to tackle an apparent “epidemic” of defeat devices as the law requires them to do. Both the ICCT and ClientEarth said the proportion of highly polluting vehicles that have been recalled is small and that there is no transparency over whether repairs are effective.

Air pollution continues to be the biggest environmental health hazard in Europe, according to the European Environment Agency. Nitrogen dioxide emissions, largely produced by diesel vehicles, have been estimated to result in 64,000 early deaths every year.

“Over seven years have passed since the Dieselgate scandal first broke,” said Michelle Meyer, at the ICCT. “Yet, due to limited corrective action, these vehicles continue to operate across Europe today, harming the health of all who are exposed to the air pollution these emissions create.”

“[Dieselgate] is not over yet,” said Tim Dallmann, also at the ICCT. “There is a very strong base of evidence for taking action, and it’s up to the governments and other stakeholders. [Without action], it’s going to continue to fester. These are vehicles sold as recently as 2019, so they’re going to continue to be operating on the streets of European and UK cities for many years to come.”

The ClientEarth lawyer Katie Nield said: “It’s astounding to see that so little has changed [since 2015]. We’re sending legal complaints to three national governments to demand that the dirty legacy of Dieselgate is addressed once and for all. This was a betrayal of consumer and public trust and authorities cannot continue to let auto manufacturers off the hook.”

A spokesperson for the European Automobile Manufacturers’ Association said: “Court rulings and more recent European Commission guidance have shown all parties how important it is to have well written, clear legislation – particularly in this case, as emissions control is so complex. Previous Euro steps for cars and vans unfortunately did not deliver sufficient clarity. We note that the ICCT report acknowledges that official government reports did not conclusively identify any vehicles employing defeat devices.”

A spokesperson for Volkswagen said: “All Volkswagens comply with the legal limits of the emission standards that applied at the time of their initial registration. None of the Volkswagen vehicles mentioned contain an inadmissible defeat device.”

A spokesperson for Nissan said: “Nissan is committed to complying with applicable emissions requirements in all markets. Emissions standards and vehicle testing regimes have evolved considerably in recent years and continue to do so.”