The biggest question mark hanging over General Motors is whether the Detroit carmaker’s chief executive Fritz Henderson and his team can impose “the massive cultural change that is essential”, according to Steve Rattner, former head of the US government’s auto industry task force .

In a detailed and colourful account of the six months he spent overseeing the restructuring of GM and Chrysler, Mr Rattner says that, even by the low standards of Detroit, GM was marked by “stunningly poor management” prior to its restructuring last summer. His tale is in the latest edition of Fortune magazine.