(RTTNews) - Consumer prices in the U.S. were essentially flat in the month of September, according to a report released by the Labor Department on Thursday, with higher prices for shelter and food offset by declines in prices for energy and used cars and trucks. The Labor Department said its consumer price index was unchanged in September after inching up by 0.1 percent in August. Excluding food and energy prices, core consumer prices crept up by 0.1 percent in September after rising by 0.3 percent for three straight months.