DETROIT – Detroit Three brands, as a group, have surpassed import brands on the initial quality of their new cars and trucks for the first time since J.D. Power and Associates started tracking their performance a quarter century ago.

It’s a positive development for the Detroit auto industry a year after a crisis that ravaged the domestic auto firms and sent GM and Chrysler through government-backed bankruptcies.

Among consumers, quality is a major concern when shopping for a new car or truck, and vehicles with higher quality rankings tend to be purchased in higher numbers, suggesting some more purchasing shifts might be on the horizon.

Ford is now the top mainstream brand in the study, according to J.D. Power and Associates’ respected Initial Quality Survey, which measures problems after 90 days of ownership.

While Porsche and several luxury names led the survey, among mainstream brands, Ford led, with 0.93 problems per vehicle, followed by Honda (0.95 problems per vehicle) and Hyundai (1.02 problems per vehicle).

The study showed that most consumers have one design or defect complaint in the first 90 days of owning a new car and truck – about the same as last year. The average number of problems per vehicle across the industry was 1.09 in this year’s study, compared with 1.08 last year.

Ford’s Lincoln brand was the only other domestic brand with an above-average score. GM and Chrysler posted mixed results, with some improvements, and Toyota plummeted to below-average.

Toyota, which has suffered because of a drawn-out recall crisis, fell from above seventh place in last year’s study, with 1.01 problems per vehicle, to 15th, with 1.17 problems per vehicle, in the 2010 report.

“Clearly, Toyota has endured a difficult year,” Sargent said. “Recent consumer concerns regarding Toyota’s quality are reflected in the nameplate’s performance in the 2010 study.”

The gains by Detroit and the decline by Toyota resulted in a shift of balance. Collectively, domestic brands reported 1.08 problems per vehicle, compared with 1.09 for import brands, in this year’s study.

The results show that domestic automakers are not just closing the quality gap on imports but are actually surpassing them in some cases, especially at Ford.

“Domestic automakers have made impressive strides in steadily improving vehicle quality, particularly since 2007,” David Sargent, vice president of global vehicle research at J.D. Power and Associates, said in a statement. “This year may mark a key turning point for U.S. brands as they continue to fight the battle against lingering negative perceptions of their quality.”

The annual Initial Quality Study focuses on design-related problems and defects in a vehicle’s first 90 days on the road by measuring problems per 100 vehicles.

When you break down the numbers, however, it shows that the variation between the best and worst performer is actually quite small.

Porsche topped the study showing 83 problems per 100 vehicles, which boils down to 0.83, or less than one problem per vehicle. Land Rover came in last at 1.70 problems per vehicle, or fewer than 2 problems per vehicle.

While this study doesn’t measure long-term quality over years, good initial quality scores correlate with better long-term quality numbers, officials at J.D. Power have said.