An ongoing nationwide strike by union workers, including those in the car industry, has cost the South Korean economy 102.5 billion won (about $US86.4 million) in lost output so far, an official at the Ministry of Commerce, Industry and Energy told Dow Jones Newswires on Friday. Three car makers, Hyundai Motor, Kia Motors and Ssangyong Motor, have seen a combined 100.1 billion won in production losses and were hit hardest by the strike that began Wednesday, the official reportedly added.