Should I even rent a car?

This is a personal decision. It depends on what you are doing. If most of the time is in the two cities do not rent a car. If you want to explore rural area rent a car.

We tasted port in Porto and that was a treat.

Lisbon is best without a car. When in the area visit Belem and the Royal carriage museum and sample the Belem pastries at the restaurant near by.

Have a fun trip

Wine tasting with a car is possibly a bad mix. Drinking limits are not the same in all countries, and some are very strict. I would look for other transportation methods if wine-tasting is your objective.

My sister and I decided to rent a car for 5 days to explore between the two main cities in 2019. Things have changed a bit, though, with higher prices for both car rentals and gas. There are excellent toll roads (get a transponder from your rental company), though we enjoyed exploring smaller roads and villages most of the time.

FYI, though I enjoy Rick Steve travel books, especially his city walks and maps, he doesn’t cover many areas in Portugal that we chose to see. Braga and Guimaraes were two smaller towns we enjoyed, with amazing Celtic ruins, castles, museums, churches, etc. We also visited a couple of Schist villages up in the mountains near Coimbra. (Our favorite city).

How many days and what time of year? There are lots of day trips via train from Lisbon and Porto where a car is not needed. I personally haven't been to the Douro valley, so I will leave others to answer the question regarding a car for that portion.

And yes, there are so many places that warrant a visit and where a car would make it easier, but then, that would also warrant having at least a couple of weeks or focusing on one area of Portugal.

I will second Braga and Guimaraes which can be done as a day trip from Porto (train).

I spend ten days in Portugal, starting in Lisbon and ending in Porto. I took trains all the way with stops in between. (I used a bus to get between Coimbra and Nazare for a day trip.) A car would have made it a little easier in between Lisbon and Porto, perhaps, especially allowing me more freedom to see more along the coat near Nazare. Otherwise, the trains and bus worked well enough for what I did. I was considering a day trip out to the Douro Valley from Porto for the scenery (not interested in wine), but it rained the day I had planned to do it so I didn't bother.

Perhaps make a "driving itinerary" and a "train itinerary" and choose once you get there (I like to be spontaneous on trips - I know, some people don't).

I agree with Paul. We always travel by car but I have gout which means no alcohol. The laws and enforcement are very strict on the continent so the very last thing I would do is go driving to a couple of wine tastings it's a good way to ruin a vacation.

It’s very possible to do the Douro for a couple of days without a car then you can actually enjoy the scenery and drink the wine! If you find a nice Quinta for a couple of nights, ask if they recommend a driver for you while you are there. I did that a couple of years ago and it worked great. The man picked us up and dropped us off at the train station and drove us several places in two days. He charged €40 for the entire stay.

And, yes, the rest of your trip looks quite easy without a car.

Two weeks around Sept/Oct. SOme wineries may be harvesting...so what was this rental guy for driving? I was thinking there is alot of Wineries that have lodging, so that would be cool. So it sounds like a lot of this trip can be done by train.

I want to do Lisbon, with day trips to Sintra..etc...so wouldnt need a car for that...and Porto and maybe just need to know the MUST visit places that require a car so I can schedule the rental.

Your itinerary is only Lisbon and Porto? Plus day trips? To see Portugal or a small part of it?
How long do have in Portugal?
Most people visit more towns and cities for overnights. Are you interested in ( from Lisbon) Evora, )Alcobaça? Batalha? Obidos? Tomar?
From Porto: Guimares? Braga? Ivano do Castelo? Douro River wineries? The Belem area of Lisbon???
You need to decide which towns, areas you want to visit? It is a small country but not so small that you can the major sites as day trips.
We rented a car when leaving Lisbon and dropped it off in Porto, approximately two weeks.

Yeah, two weeks. Wanted to limit cars tho

You definitely do not need a car. Travelling between Lisbon and Porto, with interesting day-trips in the area, is perfectly feasible by train. A car can be useful if visiting small, traditional villages that tourists normally don't see, but that was not a goal that you mentioned. Also, many people believe that a car gives you more flexibility, and in many ways they're right; but there are exceptions. For example, I like staying in quaint, independent hotels in the medieval centers of historic towns, and as a train rider, I can make reservations in any of them without having to worry about where I'm going to put a car in these antique neighborhoods. Also, if I'm not driving, I can have a wine or beer any time I want. And in Spain, I can cruise tapas bars late into the night without having to worry about whether I will be fit to drive the next day. (So as I train rider, I lose some aspects of flexibility, but gain others.) Finally, driving safely on the busy, confusing streets of metropolitan areas like Lisbon or Porto may not be easy.

Hello, we rented a car to go from Lisbon to Porto. We want to see all the cute little towns in between. Also driving from Porto to Lagos (I know it's a LOOOONG drive) so we can go East and West as our leisure and return to Lisbon. Hopefully make a quick stop in Evora. We'll see how time goes.

Also, we're going in Sept. and we rented in Apr for September. We belong to AAA and the price did save us some money, but WOW it's expensive. We also needed an automatic and that increased the price some.

Have fun!

Most of this conversation is about Lisbon and north to Porto. How easy is it to get to the Algarve region in the South by train? What about once you're there, how is public transportation? Has anyone taken the train from Lisbon to Barcelona?

Link to Seat 61 that has some info regarding trains

https://www.seat61.com/international-trains/trains-from-Lisbon.htm

WE've rented cars before, thats not an issue. I just enjoy trains. I was thinking just renting a car for a few days to hit some areas.