Seoul: Hyundai Motor and its affiliate Kia Motors said on Thursday they aim to raise the average fuel economy of their vehicles by 25 per cent by 2020 to meet emissions regulations in South Korea, the United States and Europe.

The announcement came after the South Korean duo on Monday agreed to pay $350 million (Dh1.28 billion) in penalties to the US government for overstating fuel economy ratings. At home, they have also struggled to fend off imported rivals which have surged in popularity thanks to their fuel-efficient, diesel-powered engines. In a statement, the South Korean automakers said they would develop next-generation engines and transmissions, reduce the weight of key models and expand their line-up of environmentally friendly vehicles to reach the target.