Renault has flat-out denied any misdeeds.
France's consumer watchdog agency is accusing Renault of cheating emissions test results for a quarter century.
According to Deutsche Welle, the French newspaper Liberation reported Wednesday that France's anti-fraud Direction Générale de la Concurrence, de la Consommation et de la Répression des Fraudes (DGCCRF), accuses Renault of using a cheating device to pass emissions tests and deceiving consumers about the cleanliness of their vehicles.
Specifically, Renault is suspected of using the device to suppress nitrous oxide emissions during certification tests. The claim recalls methods Volkswagen has admitted to using in their own diesel cheating scandal, which was exposed in 2015 and has been plaguing the company since.
What's more, the report alleges that Renault's cheating goes back 25 years, and says that top level executives, including CEO Carlos Ghosn, bear some responsibility.
For its part, Renault has vehemently denied the accusation, calling the Liberation article "unbalanced" and issuing a statement that says, "Renault vehicles are not equipped with cheating software affecting anti-pollution systems."
Still, Renault shares fell 5 percent on Thursday after the article was published.