The comparison between Mac and BMW isn't really a one-to-one mapping... a BMW uses the same fuel as a Ford, drives on the same roads, and if you can drive a Ford, you can drive a BMW. The analogy would work if we got "The Mac Experience" by loading up Windows and if we could get our stuff done on Windows-based software (which, all the same, didn't *feel* like Windows-based software because -- hey! -- it was running on a Mac box).
A better analogy might be to compare the Mac to a helicopter. They both get you there, but one is faster, smoother and more stylish. And costs more. And has... what was the market share again?
Macintosh: The Computer for the Best of Us?