Automobile rental is highly discouraged in Italy, due to the fact of very limited parking and expensive gasoline (somewhere in the neighborhood of $US 8 per gallon). The street signs can be confusing, and the traffic can be atrocious. Italians tend to drive aggressively, so it is not for the faint of heart.
However there is a lot to see in Italy that is inaccessible by bus or train. Unlike the United States, there is so much art and history in every little town. You can easily stumble across some pleasant surprises. Therefore, renting a car is recommended in those instances.
So if you are feeling adventurous enough to try driving, here are the major road classifications:
1. Autostrada - Major highway or expressway (usually a toll-road)
2. Strada statale (S.S.) - State road, first class main road
3. Strada Provinciale (S.P.) - second class through road
You will not need a special driver's license if you are renting an automobile through an agency. However, US and Canadian citizens will need to secure an international driver's license if you will be driving a private vehicle. These can be secured at your local AAA (Automobile Association of America) office. In Italy, you drive on the right side of the road as you do in the US or Canada. You are not allowed to make a right on red. When driving on the highway, do not dilly-dally in the left lane...that lane is used strictly for passing.
Check with your automobile insurance carrier to ensure that you'll have the proper coverage.
Click here for a listing of the major rental car agencies you can contact prior to your trip.
For travel within any of the major cities, Italy provides a pretty good bus network. You can buy a biglietto at any of the local tobacco shops, indicated with a big black "T". The (intra-city) buses use an honor system, which is even a joke to the locals. Inspectors will do routine spot checks of the passengers to make sure that your ticket is validated by a validation machine that must be punched when you enter onto the bus. It's not worth the potential fine or hassle to try and beat the system by not validating your ticket.
The buses WITHIN the city bus system are usually orange in color. The buses that travel BETWEEN cities tend to be blue in color. For these routes, you will need to purchase your ticket in advance at the local office and will need it PRIOR to boarding the bus. Italy is served by many regional bus companies for long-distance travel. There is not one national bus-line like there is in the United States (i.e. Greyhound).
Catania - Milan - Naples - Rome - Torino
The Italian train system (Ferrovia dello Stato, or FS) is very good and usually on time in the northern part of the country. As you travel further south, or off the main lines, you can expect to experience some delays. However, the system is still pretty good for the most part. Traveling by train in Italy has a certain romantic ambiance about it, so it is highly recommended between cities. Beware of the summer months when the trains can be overly crowded.
There are a few different types of trains you must consider when traveling in Italy (from slowest to fastest)
Locale - slowest of all the trains that stops at all the local stops (avoid this one if you can!)
Diretto - faster than a locale, with less stops
Expresso - stops just at the main towns
Eurocity - will connect Italian cities to the major European cities
Eurostar - serves the main lines like Rome to Florence with few stops
Then you must also consider between first and second class. First class is worth the extra expense during peak times and during busy season.
Make sure you validate (stamp) your train ticket PRIOR to boarding the train. There is a little electronic, usually yellow, machine in every station where you can validate your ticket. Failure to do so may result in a fine.
Depending on how much train travel you intend to do, a Eurailpass will offer you significant discounts. There are also different types of passes that you can purchase that may beneficial to your situation. Check out RailEurope.com for more information and great deals.
Car ferries operate to Sicily and Sardinia. If you are traveling by train from Italy onto Sicily, they will load the train onto a ferry. Then you re-board the train once you are on the other side. Although the topic of conversation for many years, they have not, and probably never will construct a bridge to connect Sicily and the mainland.
Tirrenia and SNAV are the two main sea transport companies in Italy.