Half of Rome's cars have been banned from circulating within the fascia verde, which roughly corresponds to the area inside the Grande Raccordo Anulare ring-road, from 15.00-19.00 on Wednesdays. Under new rules introduced on an experimental basis in January to combat smog, cars with license plates ending in an even number must not be driven within the restricted area on 28 January, while on the following Wednesday the ban applies to those with registrations ending in odd numbers, and so on alternately until the end of March. Two-wheeled vehicles are exempt from the ban.

The regulations were introduced by the city council in the face of continuing high levels of pollution in the city. Those in favour of the ban say that even if it has little effect on the amount of smog in the atmosphere, it will have a positive influence by reducing the public's reliance on private transport. Critics argue that the weekly prohibition is completely pointless and say that attention should be focused instead on car parks, electric shuttle buses and a new metro line.

The number of private vehicles in Rome continues to rise; in 2003 around 50,000 new cars were registered in the city, while only 20,000 were scrapped.