Winter can be hard on both the exterior and the interior of your car. Road salt and grit are hard on the exterior, while these along with all the moisture tracked in are hard on carpeting and upholstery. Prompt cleaning as soon as the thaw occurs can help prevent major damage. The following are the key things you need to do.
Rinse the exterior
Don't go right for the sponge or brush when it comes to the exterior of your car, this will simply scratch your paint since there is a winter's worth of dirt and grit on the surface. Instead begin with a high pressure wash. You can do this at home if you have a high pressure hose nozzle, otherwise you will need to take it to a car wash. Rinse off the outer exterior, as well as inside the wheel wells, behind the fenders, and underneath the entire car. A drive-through wash that provides a thorough undercarriage rinse can help with this. Once this is done, you can wash with soap and a sponge or brush.
Don't skip the transition zones
The transition zones are those places in your car that are neither exterior or interior, such as the door threshold or the frame around doors and windows. Winter dirt and road salts also collect in these areas, which can then suffer rust, corrosion, or general damage. Rinse these areas with a soft cloth and hot water, removing all the dirt. Also, use your cloth to wipe down the rubber weatherstripping that trims in around the door frame or windows, since grit also collects here.
Steam the carpets
Vacuuming won't be enough to remove the dirt and moisture debris from winter. Chances are the moisture has penetrated pretty deeply into the carpet, even if you have mats down. In a few months, you may notice a musty mildew odor if you don't deal with the problem now. Mats can be removed and washed. As for the carpeting, use a steam cleaner or upholstery shampooer to fully clean the carpet and then extract as much moisture as possible. The same can be done for the seats, if needed. This is best done in the morning on a warm, sunny day. Then, you can roll down the windows and allow the warmth of the day to ensure everything dries out quickly.
Many self service car washes offer the equipment to do these tasks yourself, or you can visit a full service car wash and have your post winter cleaning done for you.