German transport minister Alexander Dobrindt said the Federal Motor Transport Authority (KBA) will meet with the car makers next week.
Opel’s official statement said: “Opel once again wants to stress the fact that we do not deploy any software that recognises whether a car is undergoing an exhaust emissions test.
It continued: “This statement is backed by extensive tests conducted in various countries, for example in the report of the German Federal Ministry of Transport and Digital Infrastructure published on April 22. The report of the German authority concludes that during the field study – apart from certain cars of a competitor – no other vehicle has been found that has an illegal defeat device. Commissions in France and the United Kingdom already came to the same conclusion.”
When contacted by Autocar, Vauxhall said that its cars conform to rules and that any discrepancies between published figures and real-world figures are to do with the test procedure itself, and not wrongdoing.
Fiat has so far not yet commented on the news.
It was first reported late last month by German newspaper Bild am Sonntag that Fiat was under investigation by German authorities trying to establish whether the car maker has been running a system to manipulate European emissions tests.
At the time, German transport minister Alexander Dobrindt singled out Fiat and said it would need to carry out more tests on Fiat models.
Tests conducted by Germany’s Federal Motor Transport Authority (KBA) are reported to have found that some Fiat vehicles' pollution-reducing systems were running for just 22 minutes before cutting back their effectiveness. An official laboratory emissions test runs for about 20 minutes. Reports suggested that it was a test on a Fiat 500X that exposed the issue.
In March, Opel/Vauxhall announced it had instigated plans to improve NOx emissions of SCR (Selective Catalytic Reduction) diesel engines.
This latest development follows the initial findings from the German investigation, which has led to many manufacturers announcing voluntary recalls on affected vehicles. In the UK, Mercedes, Audi, Vauxhall and Suzuki are offering customers voluntary recalls.