Driving in Spain June 25-28, 2023

Many people recommend Autoeurope, which is a broker but uses reliable companies. I tend to go with Hertz just because I have used them several times and have a discount.
Are you stopping en route?

You will need an international driving permit IDP (not technically a license) in addition to a valid home country driving license when driving a car in Spain.

There are plenty of rental car companies at Barcelona's El Prat Airport. I've tended to use Sixt for my rental cars - https://www.sixt.com/car-rental/spain/barcelona/barcelona-airport/

How many days will you have to make the drive? There are quite a few interesting places to stop in between Barcelona and Valencia like Tarragona, Reus, Poblet Monastery, the various medieval towns of Matarraña region, Ebro Delta Wetlands Preserve, Miravet, Peñíscola, ancient ruins of Saguntum etc.

When we rented a car at Barcelona Airport last October, I booked through Costco travel and got a very good price. The rental company was through Alamo, but we had to go the Enterprise desk at the airport. I had an IDL, but they didn't ask to see it. My passport was good enough for their record keeping, but that said, I would get an IDL because that's the law. Get one at your local AAA office. I had no problems renting a car in Barcelona or returning it to the Barcelona airport. The car rental return area is across the street (a 200 feet? walk) from the terminal.
In Munich, I rented a car to visit the Bavarian alps and we used SIXT. Again, no problems.
Both times I reserved and received a car with automatic transmission.

My last couple trips I’ve gone through Costco travel and the rental company choices were Alamo and Enterprise for Spain. When reserving a vehicle in advance check back from time to time to see if prices have gone down. For a trip to Spain later this year the rental price went from 990€ down to 872€. While most rental cars are still manual, in May 22 we got an automatic even though we reserved a manual.

Also, if you intend on plugging your phone into a USB for directions, the last rental we had in Spain only had USB-C ports so our USB2 cords were useless. For upcoming trips I bought a lighting to USB C cable for my iPhone.

Thank you for all the wonderful suggestions and advice.
One more question. Please post information about adding the navigation system that will be offered at the car rental agency in Spain. Did you find it useful? Or did you use Waze or Google Maps to get from one destination to another?

Rather than rent a satnav system, just use Google maps or a similar app. It works fine. Roads in Spain are very well marked as are the main attractions. Bookmark the places you want to go, download the map for the area you’ll be visiting (if you don’t have free data or an international plan) and you’ll get to where you’re going without any problem.

Google maps works great. Highly recommend getting data as otherwise you make one wrong turn and you’re completely lost (voice of experience. My phone company neglected to tell me they turned off roaming post Brexit).

I drove all over Andalusia last September (Hertz), and no one asked for IDL. I don't think it is required any more.

An IDP is still required unlike what EugeneD said. I’ve never been asked by anybody to see it, but it is required.

Be extremely mindful of speed limits and how quickly they fluctuate up and down. Cameras are everywhere; citations are expensive and the car rental companies also charge you a fee "to provide your information to Spanish authorities."

IDP: I have driven rental cars in Italy - twice, France, Scotland, and Ireland. Never got asked for it. Driven (and pulled over) in Costa Rica -- and was asked for it. So, I went to AAA and got one for the trip to Spain. $15. 15 minutes. I hope I don't have to show it!

Google maps and Waze worked like a charm in every other country. I expect both will work in Spain for us. The car we rented in Scotland had a nav system. We used that AND the others... It's like wearing a belt AND suspenders at the same time. But it also keeps the nap of the necks of all the car occupants down, too...