Hey Sixpkrt,
Sorry, I didn't mean to offend. As I said, I'm sure I'm in the minority. My view is a little different, I can get replacement parts all day long for my truck and my wife's Avenger RT. Having said that, we do NOT drive her 06 Charger in the winter and I'd feel the same about your 300. It is a shame that you have to drive such a nice car in the crap, so I guess we're fortunate that we can have it both ways. The Charger has never seen snow. The truck and the Avenger get taken through the car wash, with undercarriage spray every week, sometimes twice a week to keep them from rusting. It works pretty well.
The 96 Intrepid that I sold in 2012 with 169k miles, and was driven year round in all weather, had very little rust. The only rust to mention was a small blister on the trunk. Don't let anyone tell you washing them doesn't help. I had a mechanic tell me that it didn't matter but I think he was just hoping to increase exhaust and suspension work for himself. A woman I worked with told me her mechanic told her she didn't have to wash hers in the winter because she drove the interstate so all that water from the road was "washing" the undercarriage every time she drove it. I laughed and said, "What happens to salt when it melts snow? It dissolves, creating salt water, so you're washing the undercarriage with salt water. What happens to the salt when the water evaporates? It sticks to everything that the water was on." Hopefully she runs her car through the car was occasionally now but I doubt it.