There's good and bad news about driving in Greece. Here's the good news: most people have no trouble driving the main roads of Greece, and there are main roads leading to all of the major tourist destinations. Particularly good areas for road trips are the Peloponnese peninsula and Crete.
Now, the bad news. Greece has the highest car accident rate in Europe. If you're an inexperienced driver, Greece's roads may not be for you.
Car rental fees and gas are both expensive, especially from a USA-based perspective. Greece is a mountainous country, and many roads will be curvy. In late fall and winter, they may be wet, snowy, or icy. Athens' traffic and parking in Athens can be a nightmare.
Renting a Car
A good option for small groups is a minivan like the Nissan Serena. Big warning - these and other minivans have poor luggage capacity. Although they can technically take up to 8 passengers, they can hold only a few bags. The Serena admits to holding only two "large" bags and three "small" ones for a group of eight! Figure 5-6 people tops, and use the "extra" space for your bags, unless you can strap more on top. Of course, if you are only using the vehicle for day trips, this shouldn't be as much of a problem, though the drive to and from the hotel may be memorably uncomfortable.
4x4s are popular choices for many travelers.
One company offering the Vitara model among other vehicles is Ace Car Rentals located in Athens at the Athens airport. Reservations can be made on-line through an interactive reseravation system.
If you are accustomed to automatic transmission, try to get an automatic vehicle, though these are relatively scarce and more expensive.
Learning to drive a stick shift for the first time on Greek roads is not recommended by me. An Opel Astra is often offered as the only automatic-transmission choice.
In any case, take the offered insurance coverage. And if you're certain your regular policy covers travel in Greece, please double-check. Not all of them will, and it's an expensive mistake to make if you do have a problem.
When you rent a vehicle in Greece, the quoted price will usually NOT include the VAT tax of 18% and the 3 - 6% airport rental tax. To be safe, allow about 25% extra to cover these costs. Also, the listed prices on rentals usually exclude the summer premium - allow $10-$15 a day extra for rentals from June through September. The actual "premium" dates will vary by the provider.
For US residents, the "mini" and "economy" offerings will usually be simply too small both physically and psychologically. Stick with "Compact" class and up for comfort and room, though they will be more of a challenge to park.
Many of the gas stations are the BP chain, with clean, big stations, good toilet facilities, and a few snacks and other items such as maps. Silk stations and even the occasional Shell are also found along the highways.
Gas stations are not that common -take advantage of them when you see them, and try to never let the tank get below half-full. And beware - many of them are closed on Sunday. If you're having trouble finding a gas station, stop and ask. Locals will usually know what ones are open on Sunday.
Now - on to the Rules of the Road in Greece. Happy driving!
Find cars to rent in Greece here: Find Greek Car Rentals
Compare airfares to Greece here: Find Greek Airfares