Porsche shot to the top of a closely watched study of long-term vehicle dependability, overtaking U.S. and Japanese rivals, according to J.D. Power and Associates. The German sports car brand took the No. 1 spot in the annual study, which gave it ninth place last year. Lincoln came in second, while Buick and Lexus tied for third. Mercury and Toyota rounded out the top five, the Associated Press reported. The annual study measures problems experienced by the original owners of vehicles after three years. In last year's study, Buick and Jaguar tied for fewest problems, but both brands lost ground to rivals this year. U.S. brands had a particularly strong showing this year, reflecting concerted efforts in Detroit to catch up to foreign rivals who have traditionally dominated the quality study, said David Sargent, J.D. Power's vice president for vehicle research. Top-five finishers Lincoln and Mercury are owned by Ford Motor Co., while Buick is owned by General Motors Co. The Cadillac DTS full-sized sedan, which is sold by GM, was named highest-quality car overall. "The domestics are moving a little bit faster catching up," Sargent said. Toyota, whose reputation has come under scrutiny in the face of massive recalls, fell two spots from its third-place standing last year. While average vehicle quality across the industry improved from last year's survey, Toyota's quality score fell slightly. However, the Japanese nameplate still swept four segment awards, more than any other brand, while its luxury Lexus brand took one segment award. Japanese rival Honda took three awards, while Ford Motor Co.'s Lincoln brand took two. The industry average was 155 problems per 100 vehicles, J.D. Power said, or less than two problems per vehicle. That's a decline from 167 problems per 100 vehicles last year. Sargent said that's roughly in line with the industry's historical rate of quality improvement. "If you don't improve by 5 to 10 percent every year, you will get left behind," he said. Chrysler Group LLC was the only Detroit automaker without any marques above the industry average. Land Rover owners reported the most problems among the 36 brands surveyed by J.D. Power. J.D. Power's 2010 dependability study surveyed more than 52,000 original owners of 2007 model-year vehicles between October and December 2009. The results are watched closely by automakers and are often used in advertising. Owners' opinion of a car after three years can be a major influence on their opinion to buy that brand again. The firm also releases an initial quality study, which measures problems in the first 90 days of ownership. That study usually comes out in June.