Just b/c it fascinates me:
Ford owns
Aston Martin
Ford
Jaguar
Land Rover (bought from BMW)
Lincoln
[I]Mazda[/I] (Ford owns 33% of Mazda)
Mercury
Volvo cars
General Motors owns
Buick
Cadillac
Chevrolet
Daewoo (GM owns 44%)
Fiat (GM has decided to divorce itself from Fiat as of Feb '05, but will retain 10% ownership.)
GMC
Holden
Hummer
Oldsmobile (brand discontinued)
Opel
Pontiac
Saab
Saturn
Suzuki (2.5%, from 20%)
Vauxhall
Daimler/Chrysler owns
AMC (brand discontinued -- Chrysler bought AMC primarily for the Jeep brand which was owned by AMC)
Chrysler
Dodge
Eagle (brand discontinued)
Hyundai (Daimler/Chrysler only owns 10%)
Jeep
Maybach
Mercedes-Benz
Plymouth (brand discontinued)
Smart
Volkswagen owns
Audi
Bentley
Bugatti
Lamborghini
SEAT
Skoda
Volkswagen