Rent a car in France. Can I also go into Spain

Yes you can.

Probably. Check with the rental agency to be sure.

Also, assume you will be renting it in France, driving in Spain, then driving back to France to return it. Renting in one country and returning the car in a different country usually comes with a very high drop-off fee. If you want to do that you probably can, but you will definitely want to check what that drop-off fee would be before making plans.

The short answer is "yes you can".

The full answer is somewhat longer.

You can drive a French hire car in Spain, but some of the cheaper companies you have never heard of will make you pay through the nose for the privilege. Look for names like "happy cars" . You have to ask about driving in Spain before booking or the experience could be very costly.

The cheapest of hire companies doesn't charge extra for drinking in Spain, however. That's e.Leclerc at Saint Jean de Luz. I think we paid €180 for three days and 600km for a fiat 500 convertible.

It will be in the rental company’s Terms and Conditions which countries you can drive it in.

For example, for a Germany rental, Enterprise has: Vehicles can be driven in Andorra, Austria, Belgium, Denmark, Finland, France, Gibraltar, Great Britain, Ireland, Liechtenstein, Luxembourg, Monaco, Netherlands, Northern Italy, Norway, Portugal, Sweden, Switzerland and Spain. Vehicles can also be driven in Croatia, Southern Italy, the Vatican, San Marino, Poland, Slovakia, Slovenia, the Czech Republic and Hungary with exception of vehicles of the brands Audi, BMW, Mercedes, VW, Land Rover, Jaguar. Luxury Elite Electric Vehicles cannot be rented for cross border travels. In all cases, customers must inform the rental branch of their intention to leave the country with the vehicle …

Another reason to verify that your rental car contract includes driving across the border into Spain is to ensure that you don't inadvertently void your insurance coverage by doing so. Could be an expensive oversight.