In the top 10 exported products from Japan to US in 2010, cars or car parts were involved in four of them.

Number 1:  Passenger automobiles   with a value of $13.7 billion
Number 4:  Medium sized station wagons and vans  with a value of $805 million
Number 5:  Motor vehicle parts   with a value of $746 million
Number 8: Vehicle gear boxes  with a value of $477 million

While on the other hand, in the top 10 exported products from US to Japan, vehicle or vehicle related products are not mentioned.  Food has a lot higher priority
Number 2:  yellow corn   with a value of $1.2 billion
Number 3: soybeans  with a value of $583 million
Number 5: fresh or chilled pork  with a value of $359 million
Number 7: frozen pork  with a value of $329 million
Number 9: wheat    with a value of $326 million

So Japan sells cars for food in its relationship with the US.

Provide Cars, the online used car auction shop