Higher prices will deter buyers and force automakers to curtail production, said Jonathan Smoke, chief economist at Cox Automotive. He forecast that U.S. factories would produce 20,000 fewer cars per week, about 30 percent less than usual.

President Donald Trump’s 25% tariffs on autos not made in the U.S. and certain auto parts will send ripple effects through an industry that is already being pummeled by steel and aluminum import duties and on-again,