WASHINGTON (Reuters) - A threat by the U.S. government to impose tariffs of up to 25 percent on imported auto parts could hit consumers in unexpected ways: higher repair costs, insurance premiums and even the theft of more cars for their parts, the industry said. Mechanics' tools are seen at a garage in San Diego, California April 17, 2014. REUTERS/Mike Blake U.S. President Donald Trump’s administration has launched an investigation into whether auto imports pose a national security threat...