GPS/International Drivers License or not

Gps will work fine in mountains and so will old fashioned maps.

I've gone through a blue zillion road blocks and nobody ever said squat about absence of IDP. Haven't had one for maybe twenty-five years.

We decided to buy a GPS several years ago, before our trip to Central Europe. It did help, but wasn't the perfect solution - we found that we still needed large-scale maps, both on that trip, and a subsequent trip that included rural areas of the Marche region of Italy.

The GPS should do fine in the mountains. Where it tends to lose the signal, usually only momentarily, is tiny roads with lots of curves - it doesn't track all the curves.

The GPS will choose the shortest route (I think it factors distance and time). That means if you're in a rural area, and there's both a small road and a smaller road that will lead you to the same destination, and the smaller road is shorter, the GPS will select that route. But as a human who may not want to drive on a paved cow track, we may choose the larger road - that's where having a map comes in handy.

We found the GPS to be quite helpful when driving in large cities, which granted, we don't do too often.

Thanks to all of you for responding. Was in Romania last year and understood that the GPS would not be effective due to the inadequacy of the available downloaded maps. Suppose for the extra $20.00 might be worth the IDP - we're much stronger now against the Euro so we might have a few extra schillings. Big thing about last year's auto experience was having a car with the "manumatic" transmission; drive it like a stick in the rural areas then throw it into automatic mode for city driving. Thanks again.

You'll find that in Western Europe an IDP is only legally required in Italy, and even then the rental desk really couldn't care whether you have one - they're concerned about the real license and of course your credit card. OTOH I did take the time to get one from AAA for France last year.
I traded GPS units with a friend last May (we have identical form-factor Garmins but his has European maps in addition to North America) and thought it was great to have. There were a few tourist sights in Normandy that I might have found more easily with a Michelin map, but for getting around nothing beat the GPS. The POI info was basically useless - North of Bayeux it told me the closest grocery store was across the channel in the UK.

Do you really, really need and IDP in Italy?

Here's what happened to us a couple of months ago and rather contrasts with what's often posted here: "instant hoosegow or confiscation of life's saving".

On a main road in Italy, but not a freeway, we came across a roadblock with fuzz stopping everybody. We were last in line, with nobody behind us. I was motor-mouthing with cop and translating for Herself who had some other questions for him, while I was digging in my wallet.

Gave him license (no request for IDP) which he looked at while conversation went on for another five minutes or so. He gave it back as next car pulled in behind us. Herself was putting the license back in my wallet as we drove off and noted that instead of drivers license, I had given him my concealed weapon license (they look much alike in Florida).

Go figure.

Having been in an accident in France. Get the IDL. Do you really want to translate for the guy? Trust me, there were two Americans in the accident (Yes, they backed out into a road and hit me!) My paperwork with the IDL went much faster then the man who didn't have it. They waived me bye bye, while trying to figure everything out.

Now that I have GPS I am NOT going without it again.

A poster earlier in this thread said about the IDP:

"IDP is easy to get at the AAA, one cop will ruin your vacation."

Not in France as the OP asked. They're not required in France, although they are in Italy. So I just thought that should be clearer to avoid misinformation.

However, the spirit of the answer does make sense. If pulled over in France (as I have been), you'd like the officer to have an easy time filling out the ticket.