BERLIN — Germany's metalworkers' union, IG Metall, organized a "day of action" on Sept. 21, drawing 175,000 car-industry workers to 280 events across the country. Protests occurred at major automotive hubs including Wolfsburg, home to Volkswagen; Stuttgart, where Mercedes and Porsche are based; and Ingolstadt, a key Audi location.

The union, which represents 2.2 million members, is fighting to defend the long-standing 35-hour workweek. Workers also demand a 5 percent pay raise and commitments to protect jobs and factory sites within Germany.

Wage negotiations are scheduled to begin Oct. 7, with the possibility of strikes starting as early as Nov. 1.

Mercedes-Benz is at the forefront of efforts to roll back the 35-hour week. The automaker has threatened to close two German factories unless workers accept what it calls a "productivity offensive" — extending the workweek to 40 hours without additional compensation and re-evaluating benefits such as Christmas and holiday bonus payments.

Oliver Fenzl, a Mercedes spokesman, said "It simply does not make business sense to produce cars in Germany any more."

Germany's labor costs have historically been higher than those in other European countries and China. Once offset by inexpensive energy, open trade policies, and strong Chinese demand for premium German cars, these advantages have eroded.

Energy prices are now elevated, trade environments are less open, and Chinese manufacturers are producing premium models in large volumes. Mercedes' sales in China have fallen 27 percent over the past three years, with profits dropping 50 percent. Domestic Chinese carmakers have doubled their market share to 70 percent in the past five years.

This competition prompted Volkswagen earlier this month to announce plans to cut 50,000 jobs and close four factories in Germany.

The wage disparity with other European countries has widened. Hourly pay at Mercedes' Kecskemet factory in Hungary stands at approximately 15.60 euros, or $17.80. German workers earn 49.50 euros per hour.

Yasmin Fahimi, who chairs Germany's trade-union confederation, told workers at the Mercedes-Benz factory in Marienfelde that the 35-hour week was "a red line." Constantin Borchelt, head of the Berlin branch of IG Metall, displayed a red vest from the 1984 strike that successfully reduced the workweek from 40 to 35 hours.