Moisture absorbing packs
Place moisture absorbing packs in the car, under the seats and on the floor. These are the “closet camel” or “silica dry packs” types, available from any supermarket or hardware store. Change them or re-dry in the oven every few weeks, depending on the climatic conditions. We use bigger ones throughout the shed in place of running dehumidifying machines, mainly due to the size of the areas we have. We find they are a lot of work in the wet season to keep the silica gel topped up and absorbing, but if we keep on top of it, they work well.