I've always gone with the belief that if you occasionally start a car while in winter storage, water vapor never completely dissipates from engine/exhaust system.... a bad thing. I fill the tank, add either Stabil or Seafoam making sure the additive makes it through the injectors, leave the battery in but hook up a battery tender, and never start the car until it's time to bring it out of storage for Spring, Summer, and Fall use. I too store my Reatta in an unheated garage (actually a vinyl igloo) with a dust cover over it. I do the same with my '00 Eldorado and all previously owned hobby cars. I like to leave the car batteries in so that the car does not have to "re-learn" stuff when it's time to take it out of storage.