Winter storage
Thoroughly wash the car using a pressure washer to clear any salt residue from the underside and chassis crevices. Allow it to dry completely, then polish and wax. If stored in a garage, leave the windows open slightly to ventilate the interior. Use protective silicone spray ( e.g. WD40 ) over the engine to inhibit corrosion and moisture getting in. Consider the use of a dehumidifier.
The Battery must be kept in a charged state to sustain its performance. Modern mains operated battery management chargers may be left connected to the installed vehicle battery to continuously monitor battery charge and provide a trickle charge only when needed. However, if the car is stored with mains access, the battery ideally should be removed from the vehicle and bench charged.
Fill the fuel tank to reduce the air space and cover the interior walls of the tank which are susceptible to internal rusting.
Inflate the tyres to 44psi to reduce "flatspotting" and if possible, roll the car occasionally to a different tread patch.
Chock the wheels and leave the parking brake off to prevent the pads from sticking. Lightly spray the brake discs with WD40, but beware the first subsequent brake application!
Taken from a post by Dave Massey, Senior Technical Author for Lotus