The elements have a way of breaking down metal and plastic. Intense heat and sun can quickly weather a vehicle under certain circumstances, as can snow and rain. While rain can sometimes be considered a good thing for your vehicle's paint, it can also promote paint damage in areas prone for acid rain. To slow down the process of paint oxidation and rust, storing your vehicle inside a sealed garage, or at least underneath a carport or breathable car cover. This will aid in keeping your vehicle's exterior looking like new. Why would you want to do this, beyond aesthetic reasons? It will boost the vehicle's overall longevity, and your chances of selling the vehicle in the future. A well kept vehicle will bring more buyers and greater profit, thus increasing the ultimate reuseability of your vehicle.