How many different car models does General Motors have?

GM makes, Chevrolet, Buick, Pontiac, Cadillac, GMC, Saturn, Hummer, Saab, Holden, Opel, Daewoo, and Corvette.

GM does own Holden Opel and Daewoo, but they arent sold in the US. The Corvettes are made by Chevy and are not a separate brand