GM and Toyota have been partners for years, co-producing Nova's and Corollas, Geo and other Toyota models. GM is also partners with Subaru, Suzuki, Izusa, Kia and other companies in Europe. The motor in the Saturn Vue is made by Honda. Very reliable.
Ford is part owner of Mazda, and builds cars in Flat Rock MI that roll off the line as both Ford & Mazda.
Chrysler has been part owner of Mitsubishi for years, etc. etc.
It's a global market. Get over it.