This is a short posting because my driving experience here was also very short. A few days ago we decided driving in Greece didn't look too difficult, so booked a rental car for our first few days in Crete. We picked it up at the airport, where the Avis man asked me if I have an International Driving Permit (IDP). I do not have one on this trip, so he advised me in an offhand way that I might be fined if stopped by the police. He made it sound like a minor issue.
We took the car and drove it the 30 minutes to our new place, in Agia Pelagia. That night I did some research on the internet and learned that if stopped by the police for any reason I could be fined 1,000 euros, or about $1,700 NZ! And also that if there was an accident my insurance could be invalid.
Next morning I drove the car straight back to the airport, in a state of heightened alert, and handed it back. No police were encountered. We came back to Agia Pelagia on the bus (3 euros) !
Next time I will get an IDP. In earlier trips to Europe when I expected to drive I have taken the trouble to get an IDP, but I have never been asked to show it to anyone.