U.S. automaker Ford has shown significant improvement in reliability, but Japanese and South Korean cars dominated the field in Consumer Reports' car rankings released Tuesday.

 Top 5 reliable family cars
 1. Toyota Prius
 2. Honda Accord
 3. Hyundai Sonata (4-cyl.)
 4. Toyota Camry Hybrid*
 5. Ford Fusion

The non-profit magazine based its ratings, which forecasts reliability for 2008 models, on reader surveys.

Toyota models accounted for 17 of the 39 most reliable vehicles. But Consumer Reports noted the Japanese automaker has "slipped" in performance, noting users reported problems with transmissions, four-wheel drive systems and accessories.

"We believe Toyota is aware of its issues and is trying to fix problems quickly," said David Champion, the senior director of Consumer Reports' Auto Test Center, in a release.

 Least reliable family cars
 1. Chevrolet Impala V8
 2. Volkswagen Passat
 3. Pontiac G6
 4. Volvo S40/V50

Meanwhile, Ford's rankings edged up, with the majority of its models receiving ratings of average or better.

Consumers reported performance issues with other U.S. automakers, with domestic cars making up half of the models named in the least reliable list. European automakers Mercedes-Benz and Volkswagen each had six models ranked least reliable.

With files from the Associated Press