Driving Madrid-Seville-Lisbon-Porto and back

The driving should be easy. Driving in the cities is a pain so look up parking beforehand. Expect daily parking rates between 15-25€. Unless you plan on stopping at places between those cities, it makes no sense to have a rental car. Drive at or below the speed limit to avoid getting a ticket.

Most major roads in Portugal are toll roads, so become familiar with its toll system for foreign registered vehicles. Most tolls are electronically collected, but for some you still need to get a paper ticket. In short, you’ll need to register the vehicle online once you pick it up. The registration is for 30 days, tolls are charged to the credit card you choose, and you can cancel it online once you leave the country for the last time.

yes, we plan on stopping. We like a "free form plan" so to speak.

Good plan as long as you return the car to Spain to avoid very large drop fee if dropping off in another country.

Only issue is having a car in Seville, Lisbon and Porto.

Don't miss visiting Salamanca, Avila and Segovia as well.

Pardon my tagging onto this thread, but somewhat related. My concern in driving are the environmental restricted driving zones. Difficult to decipher exactly where they are, but as best I can find is that the entire city limits of Madrid are such a zone. Driving a French-registered vehicle, is the zone of Madrid only enforced during certain atmospheric conditions, or every day? Are the main highways through Madrid still part of the restrictions, or is transit through on the highway logically less polluting than driving many kilometers around the city to avoid the "zone"? And finally, is a Spanish vignette is required for all roads in Spain, or just to enter a restricted zone?
Intending on picking up a French short-term leased car at the Madrid Airport area, and hoping to "slink" out of the City without incurring a bushel full of electronic tickets without even realizing such. Keeping an eye on the speedometer can be challenging enough as it is! The days of carefree driving are rapidly diminishing!

I use the Green-Zones app to figure out where the environmental zones are. If the lease vehicle is Spain registered it should have the appropriate sticker. Madrid, more than ever, is traffic free in most of the historic center. If you want a car in Madrid select a hotel away from that area and take the metro in. Madrid’s zones are permanent ones but do change based on current conditions. If the car is France registered, there’s no way I know of the get the sticker.

I just checked Madrid (22 May, 10:17PM) and it was a no drive zone because of CO2 levels.

I stopped driving in Madrid years ago.

Thanks very much for the tip on the Green Zone app!