VW needs more than a year to fix all cars

Volkswagen's new boss said Wednesday the auto giant would need more than a year to fix all its pollution-cheating cars, as the company suspended four employees suspected of being behind the global deception.

Matthias Mueller, who took over the driver's seat at VW at the height of the crisis, said he did not believe top management could have been aware of the scandal which threatens to cost the company billions in vehicle overhauls and fines.

The world's biggest carmaker by sales has launched investigations into who was behind the scam involving over 11 million diesel cars which were equipped with software that switches the engine to a low-emissions mode during tests.

The so-called defeat devices then turn off pollution controls when the vehicle is on the road, allowing it to spew out harmful levels of toxic gases.

The shock revelations have wiped more than 40 percent off Volkswagen's market capitalisation, but the direct and indirect costs are still incalculable as the company risks fines in several countries and possible damages from customers' lawsuits.

The powerful US Senate Finance Committee said Wednesday it is probing whether the company used the defeat devices to unfairly gain tax credits on diesel cars sold in the United States.