NEW YORK (CNN/Money) - For the first time, Korean carmakers, thanks to a strong performance by Hyundai, have surpassed both domestic and European carmakers in initial quality, a measure of the number of problems owners experience in a new car.

Hyundai Sonota

Brian Walters, senior director of vehicle research for Power, calls Hyundai's performance one of the largest improvements the firm has ever seen. Hyundai bolstered its quality 29 percent from last year and 62 percent since 1998, scoring only 102 problems per 100 vehicles for all its models. Among manufacturers, only Toyota Motor, with 101, did better, Honda, also at 102, did as well.

Toyota branded vehicles -- Toyota Motor Corp. also makes Lexus and Scion vehicles -- actually did slightly worse than Hyundai. Toyota cars had 104 problems per 100 vehicles.

Kia, the only other Korean auto brand now sold in the United States, languished far behind. Kia owners reported 153 problems per 100 vehicles. The average car brand had 119 problems per 100 vehicles. Kia's performance was still an improvement over last year, though, when owners reported 168 problems per 100 vehicles.

Among the American carmakers, General Motors scored best at 120 problems per 100 vehicles, followed by Daimler Chrysler at 123, and Ford at 127.

The top American nameplate, Cadillac, cruised into second place among all branded lines with a score of 93. Other above-average American nameplates were GM's Buick and Mercury, a division of Ford Motor Company, at 100 and the soon-to-be-defunct Oldsmobile division of GM at 110.

Top performers The best scoring models in various market segments Market Segment  Model  Compact car  Toyota Corolla  Entry midsize car  Hyundai Sonata  Premium midsize car  Buick Century  Entry luxury car  Acura TSX  Premium luxury car  Lexus SC 430  Sporty car  Dodge Stratus Coupe  Entry SUV  Honda Element  Full-size SUV  Chevrolet Suburban  Premium luxury SUV  Lexus LX 470   Source:  J.D.Power and Associates

The worst performer was also a General Motors brand. Hummer, tallied 173 problems per 100 vehicles. Others faring poorly were Volkswagen (164), Porsche (159), Mazda (157), and Nissan (154). Helping pull down Toyota's leading average was its new Scion line, which scored a clunky 158.

The best news for consumers is that a clear majority of existing models, 129 of 169, (76 percent) showed year-to-year improvement while only 35 (21 percent) declined. "We've seen improvement across the board," says Walters.

Since 1998, defects in American cars have dropped 32 percent from 182 per 100 vehicles. Power rated several domestic models tops in their class. Among premium midsize cars Buick Century led, as did the Mercury Grand Marquis in the full-size division. The highest ranked sporty car was the Dodge Stratus Coupe.

Three domestic trucks also led their divisions with Ford Explorer Sport Trac rated the best sport compact; the Dodge Ram HD the top heavy-duty, full-size pickup; and the Chevrolet Suburban the highest ranked full-size SUV.

Lexus SC430

Among all manufacturers, the cleanest individual model, the Lexus SC 430, recorded the best score ever recorded by Power, just 44 problems per 100 vehicles. Lexus also came in first among all nameplates, although Power reported that for all Lexus models, quality had declined 14 percent.

Hyundai's Sonata claimed the top spot for entry-level, mid-size cars. Toyota recorded three firsts with the top-rated compact (Corolla), light-duty, full-size pickup (Tundra), and midsize SUV (4Runner). The company also recorded four firsts with its Lexus line.

The Power survey measures a range of quality problems detected during the first 90 days of ownership. It compiles responses from 51,000 owners and lessees and is weighted toward defects and malfunctions, workmanship, drivability, ease of use, and safety factors.

"We have testimonials from manufacturers saying that they use the survey to help drive improvements in manufacturing quality," said Walters.