While I've visited Paris, I've never driven to/from there so can only offer recommendations for the German side of the border. From your title, I'm assuming you have 8 days to get from Munich to Paris (i.e. it doesn't include the time you plan to spend in Paris). As you're dropping away from Munich, winter tire rental won't be possible so hopefully your car has all-seasons. If not, I would have a back up plan of dropping the car in Munich and using public transit to get around Germany and France.
Assuming no weather complications, I would offer the following:
11/21 & 11/22: Munich
11/23 & 11/24: Southern Bavaria (FĂĽssen, Garmisch Partenkirchen, or similar) - this would also allow a trip to Innsbruck as well as some driving on the Alpine Road if conditions permit.
11/25 & 11/26: Rothenberg o.d. Tauber, Dinkelsbühl, Nördlingen and surrounds
11/26: Depart Germany for Paris - pick an interesting stop over town or two in France
Christmas markets will be opening throughout Europe towards the end of November. I'd definitely plan to incorporate at least a few those into your travels.
One thing to keep in mind is that Paris itself is an easy long weekend, fly in/out destination. Have you considered it as a separate trip/vacation, perhaps in fairer weather as you'll likely be spending quite a bit of time outdoors to explore or get to/from the various sites? Versailles, Eiffel Tour, various gardens, etc. This would also lend itself to doing a Munich drop off and make winter tire rental, if no all-seasons, feasible.
Hopefully others will chime in