Keeping your car's exterior clean is a good way to protect your investment, since things like dead bugs, bird droppings and dirt can strip away the protective wax on your car and eventually eat into the car's paint. While using an automatic car wash is the most energy- and water-efficient way to clean a car, some people like to do it themselves. If that's you, don't wash your car right after you've driven it. The body of the car will be too hot and will speed up the drying process of soap and water, making cleaning more difficult. Instead, wash it during the early morning or at night when the sun isn't out and won't make washing difficult.