In a letter sent at the weekend to General Motors and the Opel Trust, which is overseeing the sale of Opel, the German government said that its aid of up to €4.5bn ($6.7bn) for the US carmaker’s European unit was not conditional on Berlin’s preferred bidder winning control.

For anyone who has followed the tortuous sale of a majority stake in Opel to Canada’s Magna International and Russia’s Sberbank, the assurance – made to allay Brussels’ warning that such conditions might violate state aid rules – represents a startling about-face in Berlin’s stance to date.