Realistically, I agree with Ranger. When buying and using a commodity, which most automobiles really are, you might as well get the use and enjoyment out of it yourself; it is very unlikely that anyone else will value the car's condition, and be willing to pay you for that condition. So you might as well get all the pleasure and utility out of the item yourself.
That being said, there are certain items that you so value and enjoy that you want to prolong the experience for as long as possible. In the case of a particular car I can thoroughly sympathize. I would never buy a car as an investment, but I certainly would buy one for my own, personal pleasure. And I have been known to take very good care of a car so as to prolong my enjoyment. So I would say, if you have alternative mode of transportation to use for transportation when conditions are bad, by all means drive the alternative and save your favorite for those beautiful days!