Best bits of Tarmac in Europe?

[IanMorewood]

The early day motion currently under discussion in our household is that next year we will take a driving holiday. The plan as far as it exists so far is to go from Dunkerque down into Germany and do some of Italy and Austria and then head back home as the week draws to a close.

Any stretches of road that either for the driving challenge, the scenery or the location that you end up at that are a must?