Maggiore, the largest independently owned car rental agency in Italy is offering members of Alitalia's MilleMiglia program 900 miles just for joining their frequent renter program Maggiore Club. Joining is free which means the 900 miles are free as well. To ensure you get the miles you have to input your MilleMiglia number at the time of registration. Here is a screen shot of the first page of the registration showing you where you need to input your number.
entire registration process is in Italian so we suggest you open up a
second window and use Google Translate to help you along with the
registration. For the box titled "N° Patente italiana:*" use your own
Driver's Licence number even if it isn't Italian. It accepted my Alberta
number no problem.
For complete details and to join Maggiore Club click here
Here is a screen shot from the English page stating the offer as well