Underwater means they owe more on their current loan than the car is worth, and that share has risen for four consecutive years, according to new Edmunds data.
Federal regulations have raised fuel efficiency over the decades, even though the Trump administration and Congress have recently rolled those rules back.
In the 1960s, the German government put a tariff on American chickens. President Johnson then retaliated with a tariff on light-duty commercial vehicles and trucks. The back-and-forth has come to define the U.S. auto industry.