A bit slow off the mark on this one, but better late than never. Of the countries that I know car sales of in the Americas, most are led by one of two brands, GM or Toyota. GM is the main brand on the continent but it will need to work hard to maintain that. It lost Mexico and Paraguay in 2009 and will lose at least another in 2010.
GM (7)
Canada
Chile
Colombia
Ecuador
Uruguay
USA
Venesuela
Toyota (4)
Dominican Rep
Panama
Peru
Puerto Rico
Fiat
Brazil
Kia
Paraguay
Nissan
Mexico
Volkswagen
Argentina
Surprisingly Ford doesn't feature on the list but they will for 2010.