My two cents, salt on the roads is very bad, my experience, even if the road is dry in sunshine and white due to the salt. When it is dry, the pulverised fine salt is distributed over the car. After a single journey 8 years ago with the 4/4 that only lasted an hour, both side mirrors were full of rusty stains after two weeks in the garage. I immediately washed all the salt off the underbody and the chassis on the lift.
