DETROIT ? Lexus maintained its top spot for the ninth year in automobile dependability rankings, while Kia was at the bottom, according to an annual study by market researcher J.D. Power and Associates.

Lexus, the luxury division of Toyota Motor Corp., was followed by Nissan Motor Co.’s Infiniti, General Motors Corp.’s Buick, Porsche AG and Honda Motor Co.’s Acura.

GM was the only one of Detroit’s Big Three automakers to score better than the industry average of 273 problems per 100 vehicles.

Besides Kia of Kia Motors America, the brands rated least dependable were Ford Motor Co.’s Land Rover, Daewoo Motor America’s Daewoo, American Suzuki Motor Corp.’s Suzuki and Volkswagen of America’s Volkswagen.

The closely watched study, released Tuesday, is based on responses from more than 55,000 original owners of 2000 model-year cars and light trucks.