"Do you think the US & China should have equal & fair rules for cars? Meaning, same import duties, ownership constraints & other factors," Musk said on Twitter in response to a Trump tweet about trade with China. "I am against import duties in general, but the current rules make things very difficult. It's like competing in an Olympic race wearing lead shoes." The auto executive said China puts a 25 percent import duty on American cars, while the U.S. only does 2.5 percent for Chinese cars. He added that no American car company is "allowed to own even 50% of their own factory" in the Asian country, but China's auto firms can own their companies in the U.S.