General Motors Corp. announced plans to invest $380 million in its assembly plant in Wentzville, Mo., according to the St. Louis Business Journal. The deal, which will add a second shift at the St. Louis-area plant, is part of a tentative four-year contract with the United Auto Workers. The automaker also agreed to add or keep 6,400 jobs in the United States and invest $2.5 billion in its factories, including the reopening of a plant in Spring Hill, Tenn. more