The supervisory board of German carmaker Volkswagen announced on Friday that Porsche head Matthias Müller (behind the wheel in the photo) would take over as the company’s new chief executive.

Volkswagen is expected to name Matthias Mueller, the head of its Porsche division, as chief executive on Friday and purge other managers to show it is acting decisively to end a crisis over its rigging of USA diesel emission tests.

Last week, the Environmental Protection Agency and California Air Resources Board said they had caught Volkswagen using sophisticated software to cheat on pollution tests on 482,000 diesel vehicles sold in the U.S.

The software at the center of Volkswagen’s emissions scandal in the US was built into the automaker’s cars in Europe as well, Germany said Thursday, though it isn’t yet clear if it helped cheat tests as it did in the U.S.

Discovery of Volkswagen’s defeat device software also prompted a rash of class-action lawsuits from customers.

In his own words, Müller states: “My most urgent task is to win back trust for the Volkswagen Group – by leaving no stone unturned and with maximum transparency, as well as drawing the right conclusions from the current situation”.

Mueller said the company would introduce “even tougher compliance rules” and pledged to make VW “an even stronger company“.

Winterkorn on Wednesday announced his resignation, saying he accepted responsibility for the “irregularities” that had been found in diesel engines.

Authorities will continue working with Volkswagen to determine what cars exactly are involved.

Other vehicle companies have seen the Volkswagen scandal weigh down their shares.

EPA officials insisted on a call with reporters Friday that the previous testing procedures were sophisticated and sufficient to accurately detect the emissions from the diesel cars as long as a manufacturer is not deliberating trying to cheat the process.

The automaker could face $18 billion in fines in the US alone.

He said the European Union could change its laws to introduce stricter emissions tests.

But the dealers, left with unsold vehicles on their auto lots, say they have yet to hear from Volkswagen on what repairs are needed.

The company’s Jetta, Beetle, Golf and Audi A3 models in the U.S. from 2009 to 2015, and the Passat from 2014-15, were fitted with the devices which produced doctored results.