The protests, organised by the IG Metall union, were held against possible savings proposals announced by Mercedes.
According to the union, more than 33,000 workers across the country took part in the protests. Mercedes-Benz said nearly 16,000 people demonstrated at six of its factories.
IG Metall says Friday's action is the beginning of a wave of protests against cuts in the industry. Last week, it was reported that Volkswagen will cut nearly 100,000 jobs in the coming years.
The German automotive industry is under severe pressure from, among other things, declining demand in China and the effects of the war in Iran.
