VW faces multiple probes in the U.S. which could result in huge financial damage.
The company, the world’s biggest carmaker, has admitted it deceived U.S. regulators in exhaust emissions tests.
There is speculation over the future of VW Chief Executive, Martin Winterkorn.
Reports in Germany suggest that Mr Winterkorn has lost the support of key investors, following the revelation that the firm installed a device to circumvent emission test requirements for diesel cars in the U.S.
Volkswagen has said that 11 million vehicles worldwide are involved and it is setting aside €6.5bn (£4.7bn) to cover costs of the scandal.
In the US, the Environmental Protection Agency and the California Air Resources Board are investigating the way VW cheated tests to measure the amount of pollutants coming from its diesel cars.
According to news agencies Bloomberg and AFP, the Department of Justice is also looking into the issue, which raises the possibility of the company and individual executives facing criminal charges.
A DoJ criminal investigation would be serious, as federal authorities can bring charges with severe penalties against a firm and individuals.
Late on Tuesday, New York state’s top lawyer also announced an investigation.