22 day Europe Adventure. 1st 9 days in France

You will have no problem crossing the border. Very probably you won't be even stopped.

Just a couple of comments that may or may not be relevant. I'll assume you've been to Paris before, otherwise why just 2 nights? Are you planning on doing the drive from Koblenz to Bayeux in one day? You won't have time to stop and see anything on the way, that's at least a 9 hr drive with a quick stop for lunch and a couple of potty breaks, not sure you'll have time to visit any Normandy beaches on the way. Also realize that in October you'll only have daylight until about 7:00 pm at the latest so that cuts your sightseeing days a bit.

ViaMichelin.com estimates the drive from CDG to Colmar at 6 hours without stops, and the consensus seems to be that those estimates are a bit light. Are you flying in that day from the US or Canada? If so, you surely should not attempt such a jetlagged drive. Instead, consider taking the train to Colmar (takes between 2-1/2 and 3-1/2 hours) and renting the car there. Check on the drop fee for a rental in Alsace and return to Paris.

Your Day 5 drive is estimated at 7 hr. 25 minutes without stops. You won't have much, if any, time for sightseeing on the way except from inside a moving car.

If this is your trip to Paris, I think it needs more time.

Check on parking costs in Paris. I imagine you'll want to drop the car rather than paying to park it while you sightsee in the city.

We are planning 1 night stay in Koblenz.
We looked at several sources for estimated drive times. Let me know if they sound correct.

Paris to Colmar area 5hr
Colmar to Koblenz 3.5hr
Koblenz to Bayeux 7hr

Bayeux to Paris 3hr

We have zero issues with Jet lag and will have no problems driving and sight see on our arrival day.
We would not have rental car in Paris.

We have never been to Europe before, only Ireland. We are just trying to see highlights. We looked at organized tour companies and they give less time for lots of $., not our cup of tea

This is a bit of a tricky plan. Linking the far western portion of Normandy to the far eastern portion of Alsace sounds tiring and inefficient. I went through your other posts (Germany and Italy) and saw that you don't have the Alps in your trip. I would find the trip more enjoyable overall if the two days in Normandy were replaced with the Alps. Something like this:

Fly into Paris - 2 nights
Drive to Colmar/Western Germany area - 4 nights
Drive to Chamonix - 1 night
Drive to Annecy - 1 night
Fly from Geneva to Rome (the drive from Annecy to the Geneva Airport is super easy and about 45 minutes)

You could also do this in reverse, spending both alps nights in Chamonix.

-Matt

Be advised that no matter where you get your 'drive' times, they are figured on being able to average the speed limits with no heavy traffic slowdowns, no road work/detours, etc (good luck with that) and, as far as I have seen, only viamichelin.com includes some kind of 'break' time. So meals and other stops need to be added to the time.

I too think your plan is problematic on such limited time.
Stick to Alsace-Rhine rather than heading to Normandy & Mont St Michel.
I would also do my 'road trip' before dropping the car back at an airport as you fly on to Rome.

Oct 1- arrive 7am at CDG Airport, Paris for 3 nights
2 Paris, sight see
3 Paris, sight see
4 Pick up car and drive to Koblenz Germany for 2 nights
5 Koblenz Germany for Rhine river cruise and castles and vineyards
6 Drive to Colmar for 3 nights
7 sight see Colmar area (Family roots, vineyards and black forest)
8 sight see Colmar area
9 Return car at CDG before flight to Rome