German carmaker Opel, the loss-making arm of US auto giant General Motors, said Friday it will press ahead with plans to phase out auto production at one of its key western German factories in Bochum at the end of 2014, earlier than planned. \"We\'ve made it clear that we won\'t hold any further discussions\" on the issue, an Opel spokesman said. A proposal for keeping Bochum open until the end of 2016 -- in exchange for a wage freeze, the giving up of some fringe benefits and other cost-saving measures -- was rejected by unions and employees on Thursday. \"We therefore assume that production will end earlier, in 2014,\" the spokesman said. Under a deal worked out by GM at the end of February, Opel had offered to keep car production in Bochum until the end of 2016 after which the plant would be retained as a components and logistics site employing 1,200 people, compared with 3,200 at present. But in a vote on Thursday, workers at the plant rejected the deal, which the IG Metall described as \"too vague\", with about 76 percent voting against. Opel currently produces its Zafira model in Bochum. Opel has three other sites in Germany -- in Eisenach in eastern Germany, which builds the Corsa and Adam models; a components factory in Kaiserslautern in the south west; and the core production plant at Ruesselsheim, near Frankfurt. GM estimates it stands to lose more than $1.5 billion (1.2 billion euros) on its European operations this year and wants to steer Opel and its British sister brand Vauxhall back to profit by 2015. Opel and Vauxhall are heavily dependent on the European market where industry-wide sales of passenger cars fell 8.2 percent in 2012, according to data published by the European automobile makers\' association.