We occasionally hear about people finding collectible cars where no one would suspect them, like the $18 million dollars worth of cars found in December of 2014 (http://www.businessinsider.com/18-million-cars-in-french-barn-2014-12). While this may be a rare occurrence we would like to provide some tips for this not to happen.
When storing any vehicle whether it be a car or ATV or a water vehicle it is best to unhook the battery from the cables. We may not realize it but there is a slow draw from the cars battery even when they are not running.
In storage you want to have the vehicle have a full tank of fuel. Gasoline is naturally a volatile liquid which means that there are components that evaporate over time and may make it difficult for the vehicle to run. Certain types of fuel also naturally collect moister out of the air. So make sure that your tank is full, and that your gas cap is on tightly and securely (http://www.cnn.com/2008/LIVING/wayoflife/04/09/aa.bad.gas/).
Most storage units also have the problem of collecting dust in them after a period of time. To protect your vehicle make sure that your cover it with a cover that will keep that dust and other contaminants from collecting on the surface of your vehicle.
Also dust can cause some internal problems with your vehicles engine. If you choose to do these next steps make sure that you leave a note to undo it before you drive away! Some people will place in their exhaust a cloth and steel wool to protect the back side of your engine. This keeps dust from traveling up the exhaust. But like I said if you drive away with your car still like this you will have problems! So leave a big obvious note to yourself!
Along with the dust effect make sure that all of the vehicles windows are up and tightly secured. There is nothing like returning to a dusty car with an even dustier interior.
Also make sure that you place either cardboard or other catching basin under the vehicle to catch oil or other fluids that make seep and drip from the car. This will save you a cleaning fee when you move out of your unit.