South Korea's three vehicle brands belonging to the Hyundai Kia Automotive Group have swept the top three spots in a U.S. auto quality ranking conducted by U.S. market researcher J.D. Power.

Hyundai's premium brand Genesis as well as Kia Motors and Hyundai Motor ranked first, second and third respectively out of 31 global car brands in the J.D. Power 2018 U.S. Initial Quality Study released Wednesday.

It's the first time the three brands owned by the Hyundai Kia Automotive Group have all ranked top higher than their foreign rivals in the J.D. Power survey.

The annual study by the vehicle quality tracker measures the number of problems experienced during the first 90 days of ownership of a 2018 model. 

A lower score means higher quality and fewer glitches.

There were 31 ranked brands in this year's study, including 18 mass market brands and 13 premium brands. 

Hyundai's Genesis ranked highest in overall initial quality with a score of 68 problems per 100 cars. It was also the top among premium brands.

Kia Motors, with a score of 72, was the second highest in the overall ranking. J.D. Power said it's the fourth consecutive year that Kia is the highest-ranking mass market brand. 

Hyundai Motor, meanwhile, ranked third overall and second among mass market brands with a score of 74, the highest it has ever received in the survey.