General Motors, the US carmaker, angered German trade unions on Friday by announcing that its Opel subsidiary would expand production of its new Zafira family car in Poland rather than at Rüsselsheim, its main German factory. The announcement comes a week after GM reorganised its European operations, which also include the Saab and Vauxhall brands, to centralise control in Zürich, Switzerland. Opel said its works in Gliwice, Poland, offered "significant competitive advantages" compared with the group's other production facilities. Production of the Zafira in Gliwice will be in addition to that in Bochum, Germany, it said. The expansion by GM...