I think that being so far away from heat and airflow in the winter and spring hurts the back of the cars, especially trunks. Moisture trapped back there just lays because there's nothing to dry it out.
Plus a full gas tank stays really cold in the morning. I've gotten under the Eagle early in the morning and the gas tank is soaked with dew.
Just one small drip from the trunk, hatch, or a window and that water will stay there for weeks.