I'm knocking on wood too. FJ battery is from September of 2006! Shows no signs of dying, but you can tell its harder to turn over a 3 degree engine.
Only thing I can think of for outdoor cars might be to make sure they are in the car port and wont get wet....a winter of snow, melt, seeps into all the cracks, freezes, thaws, ect. That can be a little bad for trim and such. If it cannot get snowy or wet in the first place...better off.