i always hand wash mine in the summer but for winter i never really scrub the exterior. ill go to a car wash and use a pressure washer put not pull the handle to engage the power. its a more powerful but stream than my garden hose but not as powerful as the pressure washer fully powered stream. it gets the grime/sand off then i just clean the windows. u can always do that and get a rag that has a handle on it so your hands dont get cold handwashing. which is what i might do this year.