You can't put a Buick logo on a premium car like a Cadillac. First, a Cadillac costs more to make than people are willing to spend on a Buick. Second, doing tha

You can't put a Buick logo on a premium car like a Cadillac. First, a Cadillac costs more to make than people are willing to spend on a Buick. Second, doing that would reduce the demand for Cadillacs (since nobody wants something that is the "same as a Buick"). For non-premimum brands, GM and other manufacturers already do sell the same car with different names--even across coompanies. Most obviously, the Eagle Talon is/was the same as the Mitsubishi Eclipse except for the spoiler, and the Chevy Camero and the Pontiac Firebird were the same car with different body trim for a long time. Similarly, the Ford Taurus and the Mercury Sable are the same car except for some body styling. Toyota Corolla is the same as the Geo Prism, the Toyota Matrix is the same as the Pontiac Vibe, Ford Focus is sold under three different brands. Doing this keeps the prices of the good brands high while selling cars for a discount when necessary. If you bargain the price of a Ford Taurus down far enough, the dealer will tell you that you can't have the Taurus for that price, but you can have the equivalent Sable.