DETROIT — Amid steep gas prices, Toyota Motor Corp. rode its reputation for fuel-efficient cars to a double-digit sales increase in July and outsold Ford in the U.S. for the first month ever. Honda Motor Co. also reported robust sales. U.S. automakers experienced a moribund July as sales plummeted from a year ago, when heavy discounts spurred a near record month for the auto industry. For General Motors Corp., Ford Motor Co. and DaimlerChrysler AG’s Chrysler Group, the steepest declines were in trucks and sport utility vehicles, the high-margin items on which the three companies are heavily dependent. Both Honda and Toyota credited their reputations for fuel efficiency and strength in small cars for boosting them during a period when retail gasoline prices have been near $3 per gallon in most parts of the country. Overall, 1.49 million vehicles were sold last month, a 17.4 percent decrease from July 2005. The seasonally adjusted sales rate, which shows what total sales would be if they remained at the same rate for the entire year, was 17.24 million, according to Autodata Corp. Automakers sold 17 million vehicles in 2005. GM, the world’s largest automaker, said its sales fell […]