It is a common misconception that BMW’s logo is an homage to its origins as an aircraft manufacturer, as it resembles the rotations of a propeller.
Bavarian Motor Works originated after a restructuring of Rapp Motorenwerke in 1917. The logo was created out of a desire to retain the circular Rapp crest while flying Bavarian colors.
No longer able to make aircraft under the Treaty of Versailles, BMW shifted to motorcycles and their first automobiles until they resumed manufacturing aircraft for the Luftwaffe in the 1930s. Despite BMW’s colorful history, the crest has remained essentially unchanged for nearly a century.
– Chris Butsch, @CarTalkChris