GM has abandoned its planned sale of Opel to Canada’s Magna and Russia’s Sberbank, dealing a blow to Germany, which has spent months negotiating the controversial deal, as well as to the buyers. After a board meeting on Tuesday, the US carmaker said it had decided to keep Opel and restructure its European unit, including the UK’s Vauxhall. The decision reflects improved confidence in the car sector, highlighted on Tuesday by another positive month of increased US car sales.