6. Like, really slow
The original Shelby Cobra, the American icon of American icons, was aerodynamically limited to under 170 mph. When it raced in Europe, it was blindingly fast on short courses, but on longer tracks, the hard topped Ferraris of the world just laughed, put their foot down, and drove past them with top speeds nearly 30 mph faster. Shelby conceded and put a top on the car (granted, with some other aerodynamic shapes), and the Shelby Daytona absolutely obliterated everything in its path. Shelby became the first American manufacturer to win a World Championship, and it's because they went for the hard top.