Listen to AGS.
Use that Heated Steering Wheel, Heated Front Seats, and Executive Package Heated Rear Seats during the winter. That's what you are paying for! Lol!
There are snow tires in 20" wheel sizes for our M5's. Also to protect against salt, either give your M5 a thorough washing weekly/daily or do what I did and just vinyl wrap the entire car. Time and money well spent! But yeah I survived this past winter just coming from San Diego last year, I think you can survive it with an M5 as well.
