Does anyone know what is causing these black water stain lines on my 2012 300?

They are under each door handle and mirror.

http://www.max-soft.com/Black-Lines.jpg

 

I too have a 2012 300 but mine is black so I don't see them. If I had to guess, the lines on your white car are caused by wash or rain water washing out dust/dirt from behind the door handles and mirrors. White cars do have issues.

 

I hear you, but this only started to happen within the last year - all 9 years before that, this didn't happen.

 

Do you wash the car or do you take it to a car wash? If a car wash, perhaps something has changed there like final rinse with dirty water.
I can't think of anything that would spontaneously in the car that would cause this. Anybody else ?

 

I never noticed it until this year, but this year is the first time I would go for many months in between car washes.

Maybe when I was doing washes more often, it didn't have a chance to build up for me to notice.