[azzarule]

a really waterproof cover will, if it gets damp from rain and condensation underneath the car, actually keep the moisture inside the cover, and thereby keeping the car damp. If it is covered, it should be removed once a week for a few hours or so to let the moisture evaporate.

Miss Daisy is covered, but she is also up on raised stands, dry and indoor, the cover is more for the dust that will build up on the paintwork, in three years.