Here's a funny one.. I was just clearing some stuff in my place and came across some of the gifts we have received in the past from BMW NA. One of them is a small hardcover book with things about BMW, one of them is the roundel...
Here is what it says:
The BMW Roundel
One of the most recognizable logos in the world, the blue-and-white BMW insignia is known as the roundel. It's the only automotive emblem to depict motion as it portrays the movement of an airplane propeller against a clear blue Bavarian sky. This hearkens back to BMW's early days as a manufacturer of airplane engines that set many altitude records in the early 1900s.
This was published in 2008 by BMW of North America, LLC. Next to this article is that old image of the airplane with the roundel as propellers.