WASHINGTON, Sept 13 (Reuters) - Toyota Motor Corp (7203.T) said on Monday that a proposal by Democrats in the U.S. House of Representatives to give union-made electric vehicles in the United States an additional $4,500 tax incentive discriminates against nearly half of American autoworkers. In a letter to Congress from Toyota executives in nearly a dozen U.S. states, the Japanese automaker urged lawmakers to "reject using the country’s limited resources to give exorbitant tax breaks to those wealthy enough to buy high-priced cars and trucks."