I second this...Best thing for rust is to leave it outside and cold all winter long.
Cold, and more importantly, dry air will help slow down corrosion. Salt doesn't cause rust, water and oxygen cause rust. Salt is just like a really bad influence that allows oxidation to happen faster. Salt and especially mag-chloride (both in road salt) are also hygroscopic (attract moisture.) Keeping the car dried out as much as possible rather than constantly damp in a luke-warm garage is preferred.
Only when the car is really caked in road salt will I rinse it with Salt-Away and then let it freeze up and dry out in the cold, dry winter air.