Hyundai Motor workers leave the automaker’s Ulsan plant early on July 29 as the union begins its third round of partial strikes. (Yonhap) Hyundai Motor's labor union ramped up pressure on the automaker Wednesday by launching a fourth round of partial strikes, raising concerns that prolonged labor disruptions could undermine the automaker’s efforts to revive domestic sales with new models in the second half of the year.The Hyundai Motor branch of the Korea Metal Workers’ Union began four days of walkouts Wednesday, with industrial action scheduled through Tuesday after three previous rounds of partial strikes.Workers on each shift will strike for four hours Wednesday and Thursday, before the walkouts extend to six hours per shift Friday and next Monday.The latest action marks an escalation from the union’s July 29-31 walkouts, when workers stopped work for four hours per shift each day.The strikes are taking a financial toll on both the automaker and its employees. According to industry sources, Hyundai Motor estimated that the previous three rounds of partial strikes, totaling 60 hours, resulted in production losses of 42,510 vehicles.The company also estimated that each worker lost about 1.92 million won ($1,330) in wages under its “no work, no pay” principle.Prolonged disruptions could further weigh on employee compensation if production setbacks, delayed investments and weaker business performance affect future wage increases and bonuses, observers say.Further industrial action after Tuesday also remains possible if management and the union fail to narrow their differences.The two sides remain divided over key issues, including the reinstatement of dismissed workers and an extension of the retirement age.Hyundai and the union have not held formal wage negotiations for more than a month, since their 15th round of talks on July 8. Informal contacts have continued, but little progress has been made.At the July meeting, the company offered an 89,000-won increase in monthly base pay, a performance bonus equal to 350 percent of monthly base pay, 10 million won in cash and 15 Hyundai Motor shares per employee.The union rejected the offer. It is demanding a 149,600 won monthly base-pay increase, excluding regular seniority-based raises, and a performance bonus equivalent to 30 percent of the company’s 2025 net profit.