South Korea’s Hyundai Motor Co. and its sister firm Kia Corp. saw their US sales decline last month due to fewer selling days and weak market demand caused by the hurricane that hit the country's southeastern part.

Hyundai Motor Group said on Wednesday the combined US sales of Hyundai, its premium brand Genesis and Kia totaled 127,941 units in September, a 10.4% decrease from the same month a year earlier. The latest figure marks the automotive group’s first double-digit percentage decline in 26 months.

In August, the Korean duo posted driven by eco-friendly cars, including electric vehicles, hybrids and plug-in hybrids. Hyundai and Kia attributed their weak September performance to the sluggish market demand caused by the hurricane and fewer selling days than last year. By company, Hyundai Motor America's sales fell 8.

7% on-year to 69,028 units, while Kia America's sales decreased by 12.4% to 58,913 units. Genesis, Hyundai's luxury brand, saw a 1.

6% decrease, selling 6,536 units. Despite overall weak sales, eco-friendly vehicle sales increased, driven by the strong performance of (HEVs). Hyundai Motor Group sold 26,151 eco-friendly vehicles in the US last month, a 1.

8% increase from the same month a year earlier. Eco-friendly vehicles accounted for 20.4% of the group’s total sales in the US in September, keeping the ratio above 20% for the fifth consecutive month.

By fuel type, hybrid vehicle sales rose 12% on-year to 17,565 units, while pure electric vehicle (EV) sale.