anyone see a problem with renting a car at CDG and drop off at Chartres?

The only problem would be, as you said, a holiday that would close the rental offices - although some rental co's let you drop off a car even if the office is closed, others have done this but I'm not sure I'd do that,, seems like too much could go wrong that way. Other than that it's a good idea. I dropped my rental car in Chartres, spent a few hours seeing the cathedral and had a nice lunch in town then took the train to Paris.

I don't see a problem with this; in fact, I've done it. The train will arrive at Gare Montparnasse and you can take a taxi to your hotel. We also stayed in the Rue Cler neighborhood on that trip. I can't advise about the rental office being closed, but I can't imagine that it would be. Since you tell the agent when/where you will drop the car when you pick it up, they would probably tell you if there would be a problem.

We rented through EuropeCar and the rental office is right across from the train station, and it is an easy walk to the Cathedral. One point, however, we were expecting to leave our luggage in lockers at the station, but at that time (2000), they did not have luggage storage at the station. We asked the rental car agent if we could keep our luggage in the car until we were ready to leave and they accommodated us. Fifteen years later, maybe they have luggage storage now, but just to share my experience.

Would be a good idea to try to determine (might be difficult) whether:
1) the rental office you want to use is closed on Sundays or holidays. That would not happen in the US, but just might in France.
2) If it's closed, can you leave the car in the lot and drop the keys in a box; again, would not be a problem here or many places, but just could be in France. They take their holidays pretty seriously over there.

How much would the "one-way" drop off add to the rental cost? Some (most?) of the rental car companies consider a drop off at another Paris airport the same as a return to the original Paris area rental airport and don't charge extra for it. You could drive closer, drop the car at Orly, & maybe save on transport into the city. Rental office there should be open any day, also..

Thank you so much! I appreciate the advice. I think the children will enjoy the train and my husband will enjoy not driving in Paris

Good idea about Orly if the Chartres office is closed.

Drop fees are not the norm although there is a slight extra fee for renting from an airport. If the agency wants a drop fee within country find a better company; it is not the norm to charge such a fee.

French rental offices not only close on holidays, they often close for lunch -- usually there is a system for returning a car when the office is closed but I really like to have a receipt when I return a car so I don't get surprises later about gas fill or damage. The business model of rental companies is 'hose the customer' so one has to take steps to not get charged unfairly.

Dumb question - how do I get from the car rental agency to the train station. Not sure which car rental agency we will use but right now, I am looking at Autoeurope.

That's going to depend on where the car rental location is. When I used Hertz, it was no where near the train station and I tried to get a taxi but had some problems with that so the nice manager at the location dropped me off at the station when she closed up to go to lunch. So, be sure you know where the location is and research how to get from there to the station. Some rental places are near the station and you can walk. If you know you're going to need a taxi, arrange for that ahead of time if possible as it can be hard to find them at certain times of the day (I was there on a Weds around mid-day). To be on the safe side be sure to leave yourself a good chunk of time between when you drop off the car and when you plan to take the train.

Hi,
Hertz charges a one way drop off fee. I did a search for a simple three day rental using Autoeurope, a consolidator that I recommend highly. The low offer was from Hertz, it was a few bucks lower than Europecar. When I got the contract, it had a dead head fee almost as much as the rental. Don't worry, I canceled the Hertz contract.
I went back to Autoeurope and did Europecar. Europecar the assured me that their "higher" fee covered the one way rental.
I don't kow how Hertz was going to expect me to react when the fee was imposed locally. Was I going to run to Tripadvisor and rave about my good experience?
wayne iNWI

Hi,
Hertz charges a one way drop off fee. I did a search for a simple three day rental using Autoeurope, a consolidator that I recommend highly. The low offer was from Hertz, it was a few bucks lower than Europecar. When I got the contract, it had a dead head fee almost as much as the rental. Don't worry, I canceled the Hertz contract.
I went back to Autoeurope and did Europecar. Europecar the assured me that their "higher" fee covered the one way rental.
I don't kow how Hertz was going to expect me to react when the fee was imposed locally. Was I going to run to Tripadvisor and rave about my good experience?
wayne iNWI