Study by The Technical University of Munich


To make the test as realistic as possible, typical family sedans were used - with a few hundred miles on the odometer. It was stipulated that each car was to receive the equivalent of one year's wash stress (about 25 washes) - some cars by hand washing methods, others by automatic carwashing equipment.


The Hand Wash

Without having been told the why's or the wherefore's, four men were given the chore of washing four of the test cars by hand. Each person was to do as thorough a job as possible. Since there were four people involved, and since each person used their favorite "tools", together they presented a cross-section of various hand washing techniques commonly used by average car owners.


The Automatic Wash

As the alternative to the perspiring hand washers, automatic carwashing equipment was used to wash the fifth test car. To keep the test above board, the test vehicle arrived unannounced during the hours when the car wash was open for business. The car was washed along with other cars.

The Examination



The Result


How does the paintwork of a car appear after 25 washes - equivalent of a year's worth of washing?

The results are depressing, at least to the car owner who, up to now, has firmly believed in hand washing. The deepest scratches after hand washing had a depth of more than one-tenth of the paint surface. Under the microscope, the paintwork looked like a cratered landscape. The paintwork was deeply scored and scratched - the result of dirt and trapped sand particles.


By comparison, the surfaces of the test vehicle washed with automatic carwashing equipment appeared different. Compared with the hand washed surfaces, it was remarkably smooth, with many very fine markings virtually parallel and uniform - less than .0003mm - the result of evenly moving and rotating cloth pads and curtains. The machine-washed surfaces were in very good condition after 25 washes.

Wash a car by hand or by machine, in either case, it looks immaculate right after the wash. The sophisticated test described suggests that looks are deceiving: The paintwork on a car washed by automatic carwashing equipment is in much better condition than one washed by hand - even though the car owner lavishes tender, loving care on their vehicle.


