. I think the conversation around washing it off and de-humidifier sounds like the most valuable step to remediate.
I agree 100%. I'm lucky in that the garage is integral with the house and is normally dry and warm. Nothing rusts..
I sort of wish I could put the car through a car wash where they spray the undersides. I've got a pressure washer, but usually end up soaked...fun in the summer but in winter less so!