Nope, thats fine, run it in the winter if you want, apparently it will go fine. And no, it wont rust completely out because of a season, but it wont do it any favors either.

Remember, it is 23 yrs old, the undercoating and metalurgy etc. is old technology so it doesn't resist salt (an ionization catalyst) as well as todays cars.

I guarantee you the car didn't make it this long by being driven in the sand and salt. Its just a shame to take a car, especially a Mercedes, that has been cared for sooo many years, recently had a ton of new work done to it to make it a gem, and start driving it in weather that will cause it cancer.

Everything has an intended application. Your FX45 was designed for winter stuff, the MB was designed for dry, warm days with the top down...

But your car, your money- oh and by the way, you reduce your resale value if the buyer gets wind of it being a winter-driver...

I think your bating a conversation. I don't believe you would consider driving it in the winter anyway.