US President Donald Trump's vow to step-up protectionist policies to boost the US car industry could lead to a 10-percent drop in profits for German automakers, Germany's Center for Automotive Research (CAR) has warned. The trade barriers would see the European Union's alliance with America "deteriorate significantly," the center's director, Ferdinand Dudenhöffer told DW. He said Trump's desire to "punish" Washington's main trading partners in Europe would inevitably end in a messy divorce that would hurt US car manufacturers more.