[Huz-Z]

Ditto to all the above - inside, washed, waxed, covered and on a battery tender gets my vote. BMW makes some nice ones and I understand that the company that makes the battery tender for BMW makes the same unit without the BMW name, and its cheaper as a result.

Also, when you are running the car before you store it, put the ventilation system in recirculation / no outside air mode. Per a comment I saw on one forum somewhere, that closes the vent system's outside air door(s) and thus eliminates a path for nasties to get in.