What is bad about using a car wash (automatic and touchless)?
A. Automatic car washes should be avoided for a couple of reasons: the M3’s DME is particularly susceptible to flooding (there have been numerous problems with this) and the more obvious is potential damage to the vehicle’s finish. The large rotary brushes and sponge-like devices may look clean, but after washing countless other vehicles, dirt, sand, and chemicals are trapped and ready to be redeposited on your finish. Your vehicle’s finish will suffer micro scratching and any useful layer of wax will most likely be removed. Another problem is the water filtration system used by car washes. Most of the water is recycled to keep operational costs down and the process retains dirt and chemicals in the closed loop system. This is the primary reason why touchless car washes, while somewhat better that the automatic washes, should be avoided as well.
