One more thing to consider: if you arrive in Munich in the afternoon, even if you're out of the airport and in your car in an hour, most of your trip will be in the dark. Have you driven in Europe before? Are you sure the Alps, in the dark, in the winter, is the best place to start?
You're getting good advice here, if you don't want to take it, cool, but no need to be insulting to those giving it. I hope you come back and post your experiences driving in Central Europe in the winter.