South Korea’s Hyundai Motor Co plans to spend around $1.8 billion by 2020 on a major offensive in commercial vehicles, including entering the race in the United States, to catch up with rivals in a rapidly growing global market. Hyundai, the world’s No.5 automaker when paired with sister Kia Motors Corp, has targeted a market it sees growing almost 30 percent in each of the next five years, but where its share ex-China is a paltry 2.1 percent. In 2014, its commercial vehicle sales fell at home, in China and elsewhere.