Drive from Bilbao to Portugal back to Madrid?

How much time do you have? What to you want to see and do? What attracts you to Portugal.

But options you mention are possible, and there are many other options available as well.

We have 6 days for Portugal. We like history, wine, food and local flavor. We generally spend in 2 days in a large city and then want to see smaller cities/towns. We drive most of the time. Portugal was recommended by friends

Flying will be way faster. And between gas and tolls, probably cheaper.

Edit to add: Return the Spanish car in Portugal would be very expensive, so driving in nearly obligates you to then drive out.

Also, not sure what the rest of your trip plans look like, but it could be a good candidate for an open-jaw/multi-city itinerary for your transatlantic flights.

Thank you for all your responses

6 days in total between Bilbao and Madrid? I agree that it would be helpful to know a bit more about what the rest of the trip looks like and what you want to see and do.

But, based on the limited information we have available, here is a suggestion:

Drive from Bilbao towards Porto along the Spanish northern coast. Spend at least one night somewhere along the way. Since you mentioned that you prefer smaller towns, and since you'll have a car, I'd suggest staying somewhere a bit outside Porto where you can to a daytrip or two to Porto by train or bus, and use the rest of the time to explore the town you're staying in and the surrounding area. Then drive back across the border to Vigo to return the car, and take the train to Madrid.