Carmakers continually buy all sorts of competitors' models for comparison testing and R&D purposes. From what I remember, the company I interned for (one of the big 3 in Detroit) bought Ferraris, Porsches, BMWs, etc to compare drive quality and for R&D. Additionally, sometimes they don't want a new car, they want one that is 10 years old and has real world wear and tear. They essentially have a broker who will find any car they ask for. I worked on the alloy design team, and one of the more unique stories I heard was about 10 years ago, they bought a 20 year old Mercedes to essentially cut into pieces. Why? The model they bought was one of the first cars with a unique alloy in the body IIRC, and they wanted to run mechanical as well as characterization tests on it to see how it aged.