You could have saved a LOT of time if you'd realised that there aren't actually that many major car manufacturers...
Daimler-Chrysler encompasses your Dodge/Chrysler, Plymouth and Mercedes-Benz.
Lexus are part of the huge Toyota group.
The VAG (Volkswagen-Audi Gruppen) owns VW, Audi, SEAT, Lamborghini, Bentley, Bugatti.
Acura is Honda but rebadged to fool Americans.
Ford own Jaguar, Aston Martin (no hyphen), Volvo and have a controlling share in Mazda (33%).
BMW own Rolls-Royce.
FIAT SpA own FIAT, Ferrari and Maserati.
PSA is a group made from Peugeot/Citroen
Nissan and Renault are effectively partners.
GM own Hummer, Chevrolet, Vauxhall, Opel, Holden (and so on).
And as already pointed out "Miata" isn't a company, but a rebadged Mazda MX-5/Eunos Roadster.