Volkswagen, Mercedes-Benz, BMW and Porsche all posted China sales drops of 30% to 41% in April-June, with each down more than 20% for the first half.
Volkswagen's China deliveries fell 36.6% to 424,300 vehicles, pulling its global sales down 8.6% despite gains in Europe and the Americas.
China's property slump, weaker consumer sentiment and a prolonged price war have pushed buyers toward cheaper domestic brands, deepening pressure on foreign automakers.
German groups are especially exposed because they remain stronger in gasoline cars than EVs, while Chinese rivals refresh models faster and are expanding into Europe.
China passenger-car sales fell 24% in the first half to nearly 8.3 million, and AlixPartners expects the country's light-vehicle market to shrink about 10% this year.