In a perfect universe, if it were possible, one should start and drive the car once a month. Starting the engine and running it for five minutes, just won’t do it and will probably do more harm then good. Keep a modern maintenance charger (capable of a floating charge) on the battery to keep it up to snuff. Remember, in cold environments, a battery that loses it’s charge is capable of freezing.
Inflate the tires with an extra ten pounds of air pressure or put the car up on jack stands ( if it is to remain in place for more then six months). This avoids “Flat Spotting” the tires. Before the car is put to bed, we recommend changing the oil and filter. An engine is best stored without any moisture or corrosive elements in the oil.
As far as the body and bright-work are concerned, clean and polish before covering the car with a breathable cover (Technalon). Similarly clean and feed the leather in the interior. The last topic I want to address is the most problematic – Fuel . It used to be thought by most to fill up the tank to minimize condensation on the walls of the gas tank. However with new fuel standards, Ethanol has been added to gasoline. Ethanol absorbs moisture from the atmosphere . The amount of water in the fuel will increase with each month of storage. Ultimately this can lead to phase separation . In addition Ethanol can dislodge dirt and sludge within the tank and dissolve gaskets and other components within the fuel system. In my opinion it is best not to fill the tank up with fuel. I would however put a minimal amount of gas (with the highest octane available) into the tank with anticipation of filling the tank in the spring with fresh gas. I would also add some fuel stabilizer additive to the tank.
Lastly look under the cover periodically to make sure that rodents aren’t making a meal out of your interior.