Volkswagen has appointed Matthias Mueller, the head of its Porsche sports car brand, as its chief executive, as the fallout from the US vehicle emissions test rigging scandal broadened. Mueller, 62, succeeds Martin Winterkorn, who quit on Wednesday.

Volkswage’s biggest business crisis in its 78-year history deepened on Thursday as officials in Europe  and the US stepped up their investigations. Germany’s transport minister said Volkswagen had manipulated tests in Europe too.

“We have been informed that also in Europe, vehicles with 1.6 and 2.0 litre diesel engines are affected by the manipulations that are being talked about,” Alexander Dobrindt  said, adding it was unclear how many vehicles in Europe were affected.

Dobrindt said Europe would agree on new emissions tests in coming months that should take place on roads, rather than in laboratories, and that random checks would be made on all manufacturers.

Separately, a group of at least 27 US state attorneys general launched a multi-state investigation of Volkswagen’s representations to consumers about its diesel vehicles, and said it will send subpoenas to the automaker.

Volkswagen has said 11 million cars globally had the software fitted, but it was not activated in the bulk of them. As well as the cost of regulatory fines and potentially refitting cars, Volkswagen faces criminal investigations and lawsuits from cheated customers and possibly shareholders.

The European Commission urged all member states to investigate the use of so-called defeat devices by carmakers to cheat emissions tests and said there would be ‘zero tolerance’ of any wrongdoing.