here's why I wash my car more than most: I'm a clean freak. I'm in my car a lot and I like to be comfortable. Knowing it's clean makes me comfortable. My first car was a 1993 Nissan Alitma. I treated it the same way. My second car was a 2002 Maxima. Cleanest car on the block. My wife's previous car, an infiniti g35, stayed clean. her current car - a lexus rx350. stays clean. and so does my 550. it's just how I am and has little to do with BMW - although the car looks great when polished.
I'm a male, I guess I'm middle class, whatever that means and it wasn't a sacrafice to purchase my car. Interesting article but mostly useless.