I didn't know this but here's the scoop. BMW did associate the logo with a propeller once in a 1929 illustration, but that was 12 years after the logo had already been in existence. So it's difficult to say that the logo was inspired by a propeller and there's no concrete evidence to say that it was. I didn't know that. Below is a good explanation video:
Check this video out:
http://www.bmwcoop.com/2010/06/09/sh...-the-bmw-logo/