My wife and I will be renting a car in SW France for five or six days. Any problem going into Spain, say Figueres and back the same day or next day. Car will be rented and returned in France (diferent cities).
That you need to check very carefully with the car rental. Some companies do not like having their cars in other countries -- especially Italy. Come back with too many dents. It would be hard for anyone on this board to accurate advise you without lots more details.
We recently rented a car from Europcar at Toulouse. The standard Europcar rental document states that the car can be driven in Germany, Austria, Andorra, Belgium, Denmark, Spain, Finland, France, Greece Ireland, Italy, Luxembourg, Monaco, Norway, Netherlands, Portugal, U.K., Sweden and Switzerland. Places specifically excluded are Spanish islands and Corsica. Some classes of car cannot be taken to Italy. Our rental was through Autoeurope, but these are the standard Europcar conditions.
I do it all the time. It's not an issue for France-Spain.
Thank you all very much.