There are many examples of American Iron in specialty English and Italian sports cars. Today a large percentage of parts in every car are sourced from countries not of their origin.
Many auto companies are owned by other auto companies like Daimler-Chrysler. The new Crossfire has a Mercedes derived engine. This is a trend that will continue.
I knew an "English" Cal Tech professor who had a GM V8 installed in his Jaguar. He preferred more reliable power/torque at lower RPM.
The worlds auto designers are trained at 2 or 3 schools. Do you really think the Porsche designers are all German or the Honda designers are all Japanese?