If you are renting a car in France, we had a terrible experience with Europcar (rented from them on two occasions for a number of days, different locations)
With the first one the agency just wasn't open when the hours said they SHOULD be open. When the employee DID show up, a huge line formed. Our car was dirty and the cigarette lighter (which was used to power the GPS) was broken.
Then with the second rental I had reserved an automatic, which they did not have, nor was the class of car that I had reserved available, and the car was in poor condition. They tried to charge me more than 100 Euros more than my reserved quote (which read "Guaranteed Quote" on my paperwork, and when I questioned them they said "Guaranteed" meant nothing, that the price would be whatever came up on their computer when I showed up. Even though it was a lower class, and not an automatic, that they were providing me with. It took a lot of arguing to get it back to the "Guaranteed Price" they had emailed me as a quote (that I had a copy of with me). They were not helpful at all.
I have rented a lot of cars in Europe and never had a bad experience like this, but I have not used Europcar. Next time I will go back to Avis or one of the other rental companies that have always been helpful and at least upgraded you when your car class was unavailable.