With seven models topping their vehicle segments and Lexus ranking highest among nameplates, Toyota Motor Sales USA took the top corporate ranking in the latest JD Power and Associates 2004 vehicle dependability study, which ranked 2001 model year vehicles.

The Toyota Corolla, which consistently performs well in the highly competitive compact car segment, improved an impressive 30 problems per 100 vehicles (PP100) from 2003. The MR2 Spyder also made significant improvements, recording 20 fewer problem incidences per 100 vehicles in the sporty car segment.

The Big Three US domestic manufacturers all recorded improvements in their corporate performances in the study over 2003. But General Motors, which improves 2 PP100, remained the only domestic manufacturer ranking above the industry average. However, Ford and DaimlerChrysler made significant headway, improving 12 and 9 PP100, respectively. The most improved domestic nameplates included Ford (improving 19 PP100), Lincoln (18), Mercury (16), Dodge (14), Cadillac (13), Plymouth (13), Chevrolet (10) and Chrysler (10).

"The domestics are putting their money where their mouths are in terms of consistent long-term quality improvement," said Joe Ivers at JD Power. "However, while the domestics continue to outpace the Europeans in long-term quality, the Japanese continue to dominate."

Segment-leading models highlighting the domestic quality improvements include the Chrysler Concorde and the Ford Ranger, each improving by more than 20% in their segment, and the redesigned GMC Sierra HD in the heavy-duty full-size pickup segment, which improved by more than 30% over its predecessor.

At the nameplate level, Lexus ranked highest for the 10th consecutive year, followed by Buick, Infiniti, Lincoln and Cadillac, respectively. The most improved brands over 2003 were Kia (77 PP100 improvement), Suzuki (38) and Audi (23), although all three continued to perform below the industry average.

The vehicle dependability study measures problem symptoms of three-year-old vehicles, primarily in categories representing malfunctions; noise, vibration and harshness; driveability; dependability; and safety.

The 2004 study was based on responses from more than 48,000 original owners of 2001 model-year cars and light trucks.