No cars for a day?

Sounds like an interesting concept:

Rome - Cars were banned in Rome, Milan and other Italian cities on Sunday, leaving residents to walk, ride bikes or use public transportation.

The ban on cars and motor scooters, lasting most of the day, was put into place to lower pollution levels.

There was no exemption for soccer fans going to stadiums, but public transportation was increased.

Anyone else intrigued by the idea of an entire day with near-empty streets?

But I'd like to do it voluntarily - before we reach Hong Kong-like levels of smog, and are forced to do it.