GM today is all about sourcing from Holden,Opel,and Daewoo...
Ford sources from Mazda,Volvo
Chrysler sources from FIAT.
Its much cheaper to bring in existing product than it is to start from scratch.
In todays economics,you would never see a Corvair,Toronado,Vega,Pinto,Prowler..etc....unless it was already sold somewhere else.