Abstract: This invention relates to a mobile system for washing vehicles which supplies water at high pressure through a discharge hose to a user-operated spray gun or wand. The mobile washing system contains means to receive water at low pressure from the municipal or domestic well water supply. There is an engine and pump that pressurizes the water received; an onboard sdelf regenerating water softening unit to remove impurities from the wash and rinse water so that washed vehicles may dry virtually spot-free without manual drying; reservoirs for storing a liquid cleaning agent and a liquid wax which can be introduced into the discharge stream under operator control to eliminate the need to manually apply soap or wax; and valves and controls to effectively operate the wash system. All components are mounted on a wheeled cart which can be easily rolled from vehicle to vehicle by the operator or rolled to a convenient washing location.