Most of the people who can afford this car most likely use it as a fair weather summer vehicle and have something like a Range Rover for the winter.
If I owned something like this it would not see winter.
what the point of having 4S then? if i had 4S, i would drive it all year, including winter.
if i had regular carrera S, i would STILL drive it all winter, with the exception of truly horrible days.
(like -30 or snowstorm days)
I won't drive my TTRS in Southern Ontario brine shushed roads. I only take it out when the roads are bare, dry, and the salt dust is gone. If I had a $140k to spend on a 4S there is no way I would drive it in the winter and I would have a winter beater. My current one is my Mom's Rav4 
You do realize your Audi is made of galvanized steel that won't rust? Why does Audi, VW, Porsche and BMW give a 12 year rust warranty? Because of this fact. Still, your choice. If I had the means, I would drive one in the winter.
I have a 23 year old Audi as a winter beater, it doesn't have any rust holes in the body, galvanized as you mentioned, but it does have corroded bits underneath, I've replaced brake and fuel lines because of corrosion, some electrical connectors and wires, fuel tank repairs, heat shields, etc. not to mention a front air-dam from hitting a large chunk of snow/ice. Fasteners are also getting quite rusty and often strip heads or break off. Compare this to my even older 911 which has never seen winter and the difference is night and day once you look underneath.
But yeah, if I had the means I'd be driving a new 911C4S all winter.
