The domestic market share of Hyundai Motor Co., the country’s largest carmaker, fell to a 15-year low last year amid intensifying competition with foreign and local rivals.

According to market reports Friday, Hyundai sold 714,121 cars in Korea in 2015, the most in decades. The company’s market share, however, came in at 39 percent, down 2.3 percentage points from the previous year.

Hyundai Motor’s sister company, Kia Motors, sold 527,500 units here last year.

The combined market share of the two, which together form the world’s fifth-largest auto group Hyundai Motor Group, came in at 67.7 percent, the lowest ever.

The group once ruled more than 70 percent of the local car market, with Hyundai Motor’s share alone peaking at 49.3 percent in 2004. However, its share has been on a constant decline since 2010 as competition has turned fiercer, particularly with the popularity of imported vehicles among Korean drivers.

According to the Korea Automobile Importers & Distributors Association, 243,900 units of imported cars were sold last year, taking over 15.6 percent of the market, the highest ever. German labels such as Mercedes-Benz, BMW, Volkswagen and Audi all sold more than 30,000 cars during the same period, despite economic woes and the infamous Volkswagen emission test-rigging scandal.

“Domestic contemporaries’ record-breaking success with GM Korea’s Impala, Renault Samsung’s QM3 and Ssangyong’s Tivoli have also intimidated Hyundai Motor Group’s status,” an industry insider said.

Hyundai chairman Chung Mong-koo on Monday admitted that this year would be tougher on car sales.

Hyundai is planning to recoup its market status with its high-end Genesis cars, as well as eco-friendly Ioniq plug-in hybrid vehicle alongside popular models. Kia is also to release its first hybrid compact SUV Niro. Together, Hyundai Motor Group is hoping to sell 8.01 million cars worldwide, including 1.21 million at home.

By Bae Ji-sook (baejisook@heraldcorp.com)