When the snow begins to fall, salt is often put down onto roadways to melt the ice and snow so drivers can get around safely. However, the same road salt that keeps cars from sliding all over the place can also be damaging to a vehicle's exterior. When it is left on the vehicle for an extended length of time, it can promote rust and corrosion and may even cause damage to the engine.
The best way to stop salt from damaging your vehicle is to wash it frequently, which can be grueling in the cold winter months. The best bet is to wash the vehicle once every week or so, and going to a car wash when the temperatures aren't too low is ideal so it can have a chance to dry before temperatures drop at night. It is also important to remember to fiddle with the doors, locks and windows so they do not freeze open or shut as the vehicle is drying.
It is also crucial to pay attention to the underside of the vehicle - collected road salt can be corrosive to the components closest to the road's surface. The same goes for large piles of snow. If you haven't driven your vehicle since the last big snowfall, you should try to at least shovel as much of the snow out from under the vehicle. If the snow works its way into the car's undercarriage it can contribute to corrosion. This can lead to mechanical issues that will reduce braking ability and can restrict airflow, which will affect performance.
On the warmers days when snow melts, it is wise to avoid puddles, as they can be hotbeds of melted road salt. The danger zones on a car, when it comes to salt-related rust and corrosion, tend to be door, fenders, tailgates and hoods because they can retain moisture, so pay special attention to these areas to remove all of the salt and grime when washing the vehicle.
Before winter sets in, it can also be a smart move to wax your vehicle, as this action will create a protective barrier between the paint job and the elements of nature. It is not a permanent solution to weather damage, but it will definitely help keep the car's finish safe.