This Sunday is a rare moment for American motorsport.

This Sunday is a rare moment for American motorsport. GM says it will be the only automaker racing in the Indianapolis 500, Formula 1, and NASCAR on the same day. That says a lot about how wide car culture has become. For some fans, racing is about speed. For others, it is about engineering, brand identity, tradition, and the emotional link between road cars and race cars. Indy 500, NASCAR, and Formula 1 may look like different worlds, but they all remind us of the same thing: cars are sti