Volkswagen will “support” the German transport ministry’s investigation into the automaker’s emissions scandal, CEO Martin Winterkorn has said.
VW shares plunged more than 18% on September 21 after the Environmental Protection Agency (EPA) found that some of its cars could manipulate official emissions tests.
The EPA found that software in several diesel cars could deceive regulators.
VW was ordered to recall half a million cars in the US on September 18.
In addition to paying for the recall, VW faces fines that could add up to billions of dollars. There may also be criminal charges for VW executives.
The White House in Washington also reportedly said it was “quite concerned” about VW’s conduct.
“I personally am deeply sorry that we have broken the trust of our customers and the public,” he said.
He has launched an investigation into the software that allowed VW cars to emit less during tests than they would while driving normally.
The EPA found the “defeat device” in diesel cars including the Audi A3 and the VW Jetta, Beetle, Golf and Passat models.
VW has stopped selling the relevant diesel models in the US, where diesel cars account for about a quarter of sales.
The EPA said that the fine for each vehicle that did not comply with federal clean air rules would be up to $37,500. With 482,000 cars sold since 2008 involved in the allegations, it means the fines could reach $18 billion.
Volkswagen has ordered an external investigation, although it has not revealed who will be conducting it.
“We do not and will not tolerate violations of any kind of our internal rules or of the law,” Martin Winterkorn said.
The scandal comes five months after former VW chairman Ferdinand Piech left the company following disagreements with Martin Winterkorn.
“This disaster is beyond all expectations,” Ferdinand Dudenhoeffer, head of the Centre of Automotive Research at the University of Duisburg-Essen, said.
The VW board is due to meet on September 25 to decide whether to renew Martin Winterkorn’s contract until 2018, and some analysts speculated he may be on his way out.
VW had been promoting its diesel cars in the US as being better for the environment.
Class action law firm Hagens Berman is launching a suit against VW on behalf of people who bought the relevant cars.
“While Volkswagen tells consumers that its diesel cars meet California emissions standards, vehicle owners are duped into paying for vehicles that do not meet this standard and unknowingly pay more for quality they never receive,” Hagens Berman alleged.