Since most of my winter driving is spent doing donuts, my car is COVERED in salt and snow and dirt.
Being a new black subaru I NEVER hand wash my car in the winter… by using a hand mit to remove the dirt you will scratch the paint.
Insted I power wash the entire car and underneath the car…then use my autopia soap despenser to cover the entire car in a thick layer of my choice of car wash soap. then power wash the soap off.
It removes all the dirt and salt and road grim with out touching the paint and therfor scratching the shitty subaru paint.
(this is only my winter wash cycle, as soon as summer comes I obviously use a microfiber mit to wash my car)