The four-hour work stoppage was called at nine Volkswagen factories across the country. The action is twice the length of the first "warning strike" organised by union IG Metall last week, which saw some 100,000 workers down tools. The walkout was timed to coincide with the latest round of negotiations between unions and management over VW's savings plan. The two sides have been locked in bitter talks since Volkswagen said in September it was considering closing factories in Germany for the first time in its history. The situation at the group's eponymous Volkswagen brand is "serious" according to executives, with drastic action needed to put the company on a sustainable footing. The auto manufacturer has struggled with the switch to electric vehicles as it battles high costs at home and rising competition from Chinese carmakers. According to unions, management has laid out plans to close at least three plants in Germany, where the Volkswagen brand employs some 120,000 people.