Material costs are relative to where it is sourced from. Most of the “transplants” source material from their home countries, and assemble cars here, with foreign parts . The big three does the same. The one thing that most people don’t realize is that virtually all automakers in the U.S. buy parts from the same suppliers.
All of the manufacturers in the automotive business (cars, trucks, buses, rail) manufacture all the parts for everybody.
It's been that way a long time.
This doesn't mean that everybody makes everything all the time though ~ frequently a company will have a line free that everyone else has tied up, so the guy with the open slot gets subcontracts to build for the others.
Robotics make this much more flexible.
That's why I asked where GM comes up with $5,000 more in "materials costs" than Hyundai.Ain't no way~!