DETROIT — Japan's Toyota Motor Corp. won top honors in eight categories of a closely watched vehicle dependability study, more than any other company, while mainstream brands closed in on luxury nameplates, J.D. Power and Associates said yesterday.

Lexus, Toyota's luxury brand, was the top-ranked nameplate for the 12th consecutive year. It was followed by Ford Motor Co.'s Mercury and General Motors Corp.'s Buick and Cadillac.

Last-place Land Rover, which is owned by Ford, lagged far behind the second-to-last brand, Saab, which is owned by GM. Land Rover owners reported 438 problems per 100 vehicles, while Saab owners reported 326.

For the study, Westlake Village, Calif.-based J.D. Power questions owners of three-year-old vehicles about problems they are experiencing. This year's survey questioned 47,620 original owners of 2003 model-year cars and trucks.

On average, vehicle owners reported 227 problems per 100 vehicles this year, 10 fewer than last year. The study gives all problems equal weight; the most common ones reported were wind noise and loud brakes.

"The voice of the customer is actually getting heard by the manufacturers," said Neal Oddes, director of product research and analysis for J.D. Power. "They are understanding what's getting replaced, what's going wrong, and then they're taking that information and designing better products."

Oddes said the gap between luxury and nonluxury brands was narrowing. This year, owners reported an average 213 problems per 100 vehicles for premium brands, 15 fewer than for mainstream brands.

Last year, the gap was 20, while in 2003, it was 31.

The improvement in dependability is good news both for consumers shopping for used vehicles and — because the vehicles retain more of their value — for owners planning to trade in their cars and trucks, Oddes said.

Toyota had winners this year in eight of 19 vehicle categories, while Honda and GM each took four segments. Ford had two winners, and Mazda Motor Corp. had one.