[basjoos]

Having to clean the road salt off of your car is just another one of the pains of winter driving, but if you take a close look at where the salt is being deposited on your car before washing it off, it can give you some insights into your car's aerodynamics. Brine (salt water) is much denser than rain water, so it tends to impact heavily on your car's surfaces where there are sudden changes in wind direction as it flows around your car. On normal cars, the heaviest deposition zones tends to be on flat surfaces on the bumper and grill, in the recirculating eddy behind the car, on the leading edge of the side mirrors, and in the turbulent airflow coming out of each wheel well opening.

Looking at my car, the heaviest areas of salt deposition was inside the wheel wells and on the underside just behind the rear wheels. There was a small amount on the trailing edge of the front wheel well skirts and the on the underside of the boattail. There was only a fine mist of salt on the front windshield and none on the side and rear windows. Keeping the the wheel air tubulence confined inside the wheel well skirts does wonders for keeping the sides of the car clean of salt.