We’re used to seeing the South Korean automotive business flourishing, which is why we were a bit surprised when Hyundai Motor and its smaller sibling Kia Motors revealed these poor sales for May. These car companies registered double-digit fall against a year-ago period as they face tougher challenge from Chinese rivals in the largest automobile market. Hyundai Motor and Kia Motors shipped out a total of 482,968 vehicles last month, down 14.3 percent from a year earlier. Overseas sales of Hyundai Motor came to 307,362 units, down 16.5 percent on year, while those of Kia Motors dropped 10.1 percent to 175,606 units last month. Their sales have been drooping for the fifth consecutive month, helped little by the traditionally strong March-April period.