Volkswagen France massaged sales figures reported to German HQ for four years, media reports said.
Reuters, citing a report in Der Spiegel maagzine said VW internal auditors found a number of cars were registered by their owners "several months or even years" after the deliveries were recorded by the French unit – a process that normally takes weeks – and that some of the vehicles classed as delivered didn't even have purchase contracts.
The magazine said inaccurate information was provided on almost 800,000 vehicles.
A VW spokesman declined to discuss the article with Reuters, saying the company "doesn't comment on internal documents".
The reports said the French unit started in 2010 and affected VW, Audi, Skoda and Seat brand models.
After VW group chief executive Matthias Mueller was given the auditors' report on 24 April, the head of the French operations, Jacques Rivoal, quit, the magazine said, according to Reuters.