Originally Posted by
WomBatt
As a US citizen an IDP or a Roumanian driving licence is certainly required in Roumania after you have been in the country 90 days.
And if you have been driving elsewhere in Europe an IDP is certainly required in many countries, with no time allowance.
Almost no country in western Europe requires an IDP. I've driven in virtually every country in Europe and have never used one. Most rental agencies will look at you quizzically if you show them one, in addition to your US or Canadian driving license. Citizenship is relevant neither to your ability to get a US or Canadian driving license, nor to your need for a special permit in a European country.
I cannot specifically speak for
Romania, as I have not rented a car there, but for pretty much every other place.