When Alexander Calder's friend, Herve Poulain, asked him to design a "rolling canvas" for his BMW 3.0 CSL, we bet he never thought he'd start a tradition that would be around 30 years later: the BMW Art Car. With swooping curves and bold colors, Calder's design stood out among the rest of the entrants in the 1975 24 Hours of Le Mans. And it still stands out today in BMW's museum.