Unlike many countries to buy and own a car in Italy you have to be a resident, so you can’t buy one and keep it for holidays or travelling around Europe.
So you need to declare you are resident, or have a certificate of residence from your comune, have a codice fiscale and a permesso/carta di sorgiono, plus proof of identity.
If you don’t know about cars often best to use a garage, but buying privately is easy as well, get a mechanic to give the car a once over.
Check how up to date the car tax ( bollo) is as you will be responsible for paying any arrears. If you are buying the car from a dealership, they will organise the documents for the transfer of ownership. If you are buying privately, you need to go to the local office of the Automobile Club Italiano (ACI – http://www.aci.it/) or the office of the mottorizzazione civile with the previous owner to transfer ownership. In each case you will have to pay ownership transfer fees ( Passagio di proprietà). This transfer should be done within 10 days of buying the car.
You will be required to pay car tax (bollo) once a year, which is normally January or August, often worth going a bit early, Italians love doing it last minute.
For cars over 4 years, you will need to get an MOT or Revisione every 2 years, this checks your car is road worthy, most car garages can arrange that for you.
Car Insurance in Italy tends to be expensive, so most Italians have the absolute minimum, hence you often see cars driving around with dents and so on. Comprehensive insurance is wise, Italians are not the best drivers. If you don’t believe it, just walk down any street with parked cars and see how many have damage.
In Italy, you may have a licence once you reach 18 and it is valid for 10 years (5 years if you are over 50 and 3 years if you are over 70). You can only drive on a different countries licence for the first 12 months you are resident, so ensure you either exchange your licence or sit the test.