Beijing's drivers found much less vehicles and a much smoother driving in the morning, partly because it was on the weekend but largely because of the vehicle use restriction.

According to a short-term traffic rule effective from July 20 through Sept. 20, vehicles with even and odd plate number run on alternate days in the metropolis, which boasts 3.29 million vehicles.

The city authorities said the restriction, along with an earlier ban on the use of vehicles which failed to meet emission standards, would drive 2 million cars off the roads to ease traffic and improve air quality for the Games.

Car emissions have been considered as one of the major sources of air pollution in Beijing.

An additional 4 million people were expected to resort to the public transport system due to the vehicle use control.