What kind of tires do you have? The optional All-Season Continental Touring Contacts (I think that they are no additional cost) are designed for 4 seasons driving. I have had these tires on previous cars and they worked great through a midwestern winter.

I agree that there may be some wheel slip before the traction control engages, but you should be able to drive in an inch.

If you have the Michelin Pilot Sport PS2's, you are right. You will have absolutely no chance in any type of snow conditions. They are definitely a three season tire only. I think the owner's manual actually has a warning about this.

Here in Europe, we switch to dedicated Winter Tires, like the Continental Winter Contact. You can drive full speed on the Autobahn, go sking in the Alps, through snow, and then home again in the same day. No problem.