One of the most basic maintenance tasks for your car is cleaning it. While this includes the art of washing your Porsche, it also includes the reconditioning and protection of both the exterior paint and chrome and the interior.
The first step in washing your car is to determine exactly what it needs. If the car is simply dusty and has been sitting in the garage, then you probably only need to wash it with plain water (no soap). Wet the car down and use a wash mitt to remove any dust that might have settled on the car inside the garage. When washing the car, remember to get the valance panels and the lower rockers. As these panels are closest to the ground, they have a tendency to get the dirtiest.
I don't recommended using a chamois to dry your car. The chamois can trap small particles of dirt in its porous material and can actually cause scratches in the surface of the paint when it's used to dry off the car. A really good alternative is 100 percent cotton terry towels. Make sure the towels have been washed at least once, and don't use a rinse or softener. The softener is an additive that can cause streaks, and it inhibits the towel's absorbency.
If your car suffers from more than simple dust accumulation, then you will need to use a bit of car wash soap. Make sure that you don't use normal household soap or detergent, as this will remove the wax from the surface of the paint. As the wax is oil-based, normal detergents will attack and remove it. The car wash soaps are very mild and shouldn't remove the layer of wax that you have on your car.
Rinse the car completely with water from a hose, taking care not to spray the water in any areas where your seals may be cracking. If your 911 is a few years old, the overall watertight seal of the interior may not be as solid as desired. If your car does leak water, then toss some towels inside the car near the windows or under the sunroof to make sure that you catch any water before it reaches the carpet and seats.
After the car is completely rinsed, start drying it immediately. The new thing for drying cars has become the use of blowing the excess water of the car with a ShopVac on reverse or a leaf blower. While these are both fine remember, if you use a ShopVac in blower mode, make sure the filter is clean or you will just end up washing your car again, and if you are using a leaf blower that is gas powered make sure it does not vent its exhaust gases out through the blower nozzle.
It's best to dry the car off out of the reach of sunlight. Pull the car into the garage and dry it off in there. Removing the car from the sun helps keep those ugly water spots from appearing.
The key to keeping the paint free of scratches is to make sure that the towels are clean and free of any debris. Handle the towels as if they were going to be used for surgery. Don't leave them outside, or if you drop them on the ground, don't use them again until they have been washed. Small particles of dirt trapped within the towels can cause nasty scratches in the paint. If you happen to encounter a water spot, use a section of a damp, clean terrycloth towel to gently rub it out.
When you are finished cleaning, it's time to tuck the car away. I recommend that you use a good-quality cotton car cover if your car is spending most of its life in the garage. The cover will protect it from dust accumulation and also might help protect against items falling on the car or cats jumping on it. For cars stored outdoors, covers usually are not a great idea. They have a tendency to trap water, and the wind can make the cloth cover wear against the paint. If your car is not perfectly clean, then dirt particles trapped between the car and the cover will have a tendency to scratch the paint.
One of the most interesting new products to hit the marketplace in recent years is a deionized water washing system. I have used these on several of my cars, and I've been very pleased with the results. Available in small hand-held units, or semi-permanent installed setups, the systems filter regular tap water through a deionizing filter and provide a quick and easy way to wash your car without having to dry it--the deionized water doesn't leave any ugly water spots. These systems work pretty well, although in practice I was not able to eliminate all of the water spots from the car, so I recommend using them with a set of traditional towels as well to help dry the car.
One of the most innovative and time-saving products I've seen in recent years are flow-through brushes from Carrand. These are the perfect car-washing tool for busy people on the go. Simply hook up the brushes to your hose, and water flows through the brush as your cleaning. Add an automatic soap dispenser, and you can clean an absolutely filthy car in about 10 minutes. My personal favorite is the flow-through wheel cleaning brush. It removes wheel dust and grime within about a minute of use. Used weekly, it's a great way to keep hard-to-remove grit and grime from building up on your wheels.