Navigating around the Peloponnese with a rental car

I used Google Maps and for the most part got me where I wanted to go with just a few "hiccups" along the way but overall was good.

I'm not sure if there is anything better but I was happy with it.

I bought a Greek Sim card once in Greece for my cell phone which is just a basic model but worked fine in Greece with the Sim Card. A Cosmote Sim Card is the one most recommended

Having said that expect it to take longer than think getting from Point A to Point B not because the roads are bad but due to the terrain, mountains, curving coastline, going through villages and the constant stops for photo ops.

I would recommend a good guide book and the best is Cadogan Guide. While last published in 2010 it's still relevant and has more info than any other guide.

You can get used copies from abebooks or ebay.

if interested you can read my trip report with photos from another forum:

https://www.tripadvisor.com/ShowTopic-g189483-i1277-k14200587-Peloponnese_Trip_Report_Sept_25_Oct_12-Peloponnese.html

In the Peloponnese last year we had a car with integrated GPS which was sometimes a little more reliable (especially in terms of travel time) but Google Maps generally works quite well.

Being European, I don't have roaming charges, but just for fun I also used the Here WeGo app which is the navigation system installed in the vast majority of on-board GPS (it's free and available on the 'Apple Store and for Android)
The advantage of Here Wego is that you can pre-download an entire country and then use it offline (Google Maps can only pre-download an area) .This can be useful if you are in a dead zone without any cell phone signal.

There are not a lot of roads in the Peloponnese, so generally there is little risk of making a mistake. Like everywhere in the world it's best to trust the signs on the road, especially when navigating through towns or villages as the GPS may want to take you over impossible roads just to save you 200 meters.

I usually just use Google Maps on my phone... I have a small suction mount that packs easy and it works great for me... CarPlay is grat if the car is equipped but that is often hit and miss. On longer driving trips I have a nice Garmin with a large screen that I sometimes put on the dashboard which is nice on longer driving trips. I never use GPS from rental car companies as they are overprized and often not that great. You could pay for a really nice Garmin for the cost of 20 days of rental car GPS for $15 or $20 a day. I also like using my own (Either Garmin or Google Maps) as I am familiar and it seems like a lot of GPS aren't very intuitive.

As far as mobile phones... I travel a lot to Europe on business and for about the last 10 years I don't bother with getting local SIM cards. Too much of a hassle.... Most of the major Mobile Providers in the US (AT&T, Verizon etc) now have options which you can roam for $10 a day in just about any country. (If you don't use data on a particular day you don't pay). And then I can get texts to my normal phone number. It works very well and I don't have to worry about how much data I am using any more than I do at home. WHen I"m on WiFI any calls are accomplished automatically via WiFi calling being enabled. Most of the newer phones can handle multiple eSIMs which are easier to deal with but I honestly find no reason to bother with it given the ease of the International Roaming plan I have.

As you can see, there are a variety of solutions. I do two things:
1. First I “save” locations that I plan to go. I then download offline Google Maps on my phone so that I can access maps and routes even without data. Jo Lui is correct that usually a whole country will not download in one map, so I often do multiple maps - but it moves seamlessly between. You would never know you downloaded them separately.
2. I buy an eSim that gives me just data.

So my phone maps, that am familiar with, is available in any eventuality. Just for myself, I like using what I am familiar with as opposed to trying a new GPS system in an unfamiliar place. Been there, done that.

I am going to the Peloponnese in April. Renting a car. I will use google maps or maps.me. I have used both before with cars in Spain, Croatia, Scotland. I usually buy a prepaid SIM card on arrival. If I am without that for a period of time I use maps.me because it does not need an internet connection.
That’s it. Google maps or maps.me. You don’t need anything else.

Thanks everyone for the very useful information!

I have never done Google Maps downloaded/offline, but it sounds straightforward.
I also just added the HereWeGo app to my phone.

If you want to take your US portable GPS to Europe, make sure it already has or you can buy European maps for it. Home downloaded smartphone or tablet maps (HereWeGo, maps.me, etc) are the easiest and cheapest solution. Your device's built-in GPS usually works well and does not require internet while on the move. Having driven a few times in Greece (especially the Peloponnese), do not believe Google optimistic drive times or any programs maps in the details. Be prepared to back track on narrow roads. That said, driving is often easy or at least interesting in Greece.

The best advice we were given by our Greek travel agent for driving in the Peloponnese was that all drives will take longer than expected. It was true.

I might as well ask about which rental car companies folks have been happy with. Athens Car Rental gets great reviews on TA, but I was surprised that their quote was (much) higher than some of the big national rental companies. I'm looking at a Compact size and want it to be newer and in good condition/good engine for a long road trip. Thanks!

I was happy with Athens Car Rental, but it was also less expensive. So I am surprised also. Be sure you are looking at comparable included (or not) insurance.

We used Google Maps on our trip around the Peloponnese. It worked well. At one point on the way out of Sparti it took us through an olive grove on a gravel road. We thought this cant be right, but followed instructions. Turns out there was a marathon race that day and there were street closures. The olive grove was the only way to get back to the highway.

We used ACR and had a good experience. One thing to remember when you do the walk around the car at time of rental video the inspection. I missed a dent on the door but my wife's video the dent was quite clear
Perhaps I can whet your appetite with some photos of our trip.
Peloponnese, Mani and Monemvassia. https://www.flickr.com/photos/stanbr54/albums/72157711323535897

Great pics stanbr! Appetite fully whetted!

I always book rental cars in Europe through ‘Auto Europe’. We rented a car for ten days in Greece this upcoming spring and it was only $240 Canadian.

Thanks for the Auto Europe suggestion. I looked at their European (.eu) website a couple days ago and found a very good deal with Enterprise at the Athens airport. So that's what I booked -- and I will continue to check over the next several months to see if prices drop further.