Marty -
While the following information is not scientific by any means, our VS is 12 years old and has 85K kilometers on the speedo. It is garaged but I drive it almost everyday (work, play) so it has been subjected to every climate condition (besides snow) without any discernible adverse affect.
I keep it waxed (every other month) to keep the paint from drying out and NEVER use dishwashing liquid to wash the car (use only quality car care products).
If a parking situation finds our car under a tree (any tree) or by an area with rogue water sprinklers (and usually spraying recycled water) I use my car cover as added protection.
Hope this helps!