German carmakers Mercedes-Benz and Porsche AG have faced deeper financial challenges as tariffs, price wars, and slowing demand in key markets have hit sales.Mercedes' Q3 net profit tumbled 31% to €1.19 billion, topping FactSet's €1.09 billion consensus. Porsche had a net operating loss of €967 million in Q3, a sharp downturn from a €974 million net operating profit a year earlier. Analysts had expected a €611 million loss.Germany's once competitive automakers have struggled to maintain sales across Europe, ...