Has anyone had any direct experience with any of the rental car companies at the Avignon TGV station in terms of returning your rental car before it opens in the morning? In the US there are frequently drop boxes at the rental car office where if necessary you just leave the keys, but that sort of service varies widely in Europe.
I rented from Hertz there and although I didn't need to drop off my car early I do believe you can do that. Don't know about the other companies.
I recently rented from Avis there in May but dropped off just after 7:30 AM when their office opened. I would think they would have a key drop box. The biggest problem was finding the way back to their office through the rental lot when I got to the station, as the rental car return signage was nonexistent. Make mental notes when you pick up the car.