Mercedes-Benz, famed for its engineering prowess, is suddenly facing tough questions about the quality of its cars, with several surveys showing that the stately German brand may now trail some decidedly down-market competition, according to a Wall Street Journal story by Scott Miller and Karen Lundegaard. A surprise blow to Mercedes's quality reputation came last week when a normally secretive study of car quality in Europe was leaked to a German trade publication. The report, conducted for the automakers themselves, showed Mercedes's quality and customer satisfaction falling since 1999 to levels below Opel, the German unit of General Motors Corp. and a brand with one of the worst images in Europe. A separate German survey ranked the German-built Ford Focus compact car No. 1 in a study of durability during the first three years of a car's life. The survey, conducted by TÜV, a German auto-inspection and research association, put half a dozen Toyota models ahead of the first Mercedes model -- the SLK, which came in 12th. Mercedes's quality rankings in the U.S. have also slipped, according to J.D. Power and Associates, an influential provider of automotive-quality ratings. In a fall study of vehicle dependability, the brand fell to 10th place in 2001 from sixth place the year earlier. Mercedes now ranks behind such brands as Lincoln, Cadillac and Jaguar, according to the Power ratings.