I think the location of the car is more important than the mileage, live anywhere near a coastal location ( as I do) the salty environment soon attacks the brightwork, body, plastics, rubber and paint in no time at all. And there is really very little you can really do to prevent the degradation, other than try to stay on top of it with regular cleaning including the underside. If you just lieave a car for years under cover with no intervention they soon deteroiate quite quickly around here.
I live in an area that has a very shallow sea bed and that for some reason promotes more salt and sand being carried on the wind and it gets everywhere. For example a few miles away a couple was killed whilst sleeping, when their bedroom ceiling collapsed under the weight of the sand that had accumulatived in their loft over the years
