Ok, I'm a mechanic. If it wasn't for fords, I'd be unemployed. Also people forget the size of the big 2. Ford and GM. Chrysler is out of the picture since they are now owned by Diamler Benz. Ford owns and or is partnered with Ford, Lincoln, Mercury, Mazda, Merkur, and believe it or not Yamaha (they build the electrical fuel injection setups for the Tauras SHO). GM owns and or is partnered with, Chevy, Buick, Oldsmobile (which I'm not sure if the plug has been or is going to be pulled on), Cadillac (the original Henry Ford Motorcompany bought in 1908 by then named International Motors), Saab (you know the guys who make those nice fighter jets), GMC Trucks, Saturn, GEO (General Motors European Operations) which includes Isuzu, Toyota, and Suzuki.
As far as American vs. Import, Isuzu's, Toyota's and Hondas are being assembled in the US. Chevy's and Ford's are being built at Canadian and Mexican Plants. And Chyrysler is no longer an American company, technically, they are all imports.
And for the bonus question: Who Built the Chrysler 'Slant Six'??