"If the hood dents, the car doesn't qualify. It's horrible," Trump told the donors.
Trump did not go into further details. But Japan and other international markets do have higher safety standards for automobiles, particularly to protect pedestrians' heads when they are struck by vehicles, Grant Faulkner, vice president of auto industry consultants LMC Automotive, told CNN.
White House press secretary Sarah Sanders, asked about the comment on Thursday, said Trump was "obviously ... joking."
"The President has been talking about unfair trade practices for decades. It is not new for him. Part of the reason he was elected was to end unfair trade practices and push for free, fair and reciprocal trade so American goods can compete in more foreign markets," she said. "Obviously, he is joking about this particular test but it illustrates the creative ways some countries are able to keep American goods out of their markets."
There are other reasons US auto manufacturers struggle to sell to Japanese consumers. In particular, drivers there typically prefer much smaller cars given the nation's dense urban environments and tight parking spaces, Faulkner said.
The President also said he is looking to use his administration's new tariffs on steel and aluminum imports to persuade Japan to manufacture more automobiles in the US.