SEOUL, Jan 29 : Hyundai Motor on Thursday warned U.S. tariffs would continue to hurt its financials this year, after they led it to report a worse-than-expected 40 per cent plunge in fourth-quarter operating profit. South Korea's largest automaker said, however, it aimed to improve margins and revenue this year and increase spending on development of robotics and autonomous vehicles, sending its shares up 7 per cent. Hyundai reported operating profit of 1.7 trillion won ($1.19 billion) for the