There are many people who have taken time and money to restore an older car that can only be used for a few months of the year, and then put back in storage. There are also people who have a home in the north which they return to in the summer, and then in the winter, head back south to their winter home. In these two examples, and many more, there is the necessity to properly store the car. If you do not have the luxury of indoor storage, the only option is to store it outdoors, under automotive covers.
If you are forced to store outdoors, begin with a plywood base which is laid over a large sheet of heavy duty plastic sheeting. This sheet acts as a vapor barrier and it will help in keeping a lot of the windblown moisture from getting under the car. This procedure can be enhanced by tucking the plastic sheet inside the car and then closing the doors. Pay particular attention to keeping the plastic away from painted surfaces as rust can easily form. To avoid the possibility of rust, use automotive covers instead of pinching the plastic in the car doors. The automotive cover has an elastic border which allows the cover to actually go under the car by a few inches.
Car storage begins with a super clean vehicle, make sure the car, including the wheel wells and underside are cleaned of mud. Make a number of trays by folding aluminum foil, place the trays in each interior foot well and the trunk, fill the trays with moth balls.
Next, open the side windows approximately ¼” which will allow air into the car so the interior can breathe. To stop the entrance of any rodents or insects from entering the car through the window slits, take a piece of window screen, tuck the top into the opening and tape the bottom to the window, this making a barrier against insect and varmint entry.
Remove the battery and take it inside the home, connect it to a trickle charger which will ensure that it retains a charge for when you use it next.
Finally, automotive covers should be stretched over the entire vehicle. Although indoor storage is a superior method, if you do not have a garage, then automotive covers are the next best thing.
Covers are available in a wide range; there are cheap ones, expensive ones, big ones for vans and small ones for mini-cars. The important issue is fit. Of course, an inexpensive cover may let some air in but keep the water out, but there is nothing worse than an ills fitting cover that blows violently in the wind. When you uncover the car it will look like it was sandblasted.