Sao Paulo, the country's biggest and most polluted city with 5.8 million vehicles, joined the world event Saturday for the third straight year.
Sao Paulo Mayor Gilberto Kassab, who took the subway and bus to various meetings that he had scheduled for Saturday in a city where some 630 new cars are added to the traffic every day, led the initiative.
Sao Paulo's dreadful traffic jam, nevertheless, stretched to eight km on the main road network by 9.30 a.m. local time, traffic management authorities said Saturday.
Although no Brazilian city banned the use of automobiles, several closed their main avenues to cars and turned the passengers over to bikers and hikers while offering incentives for taking public transport and other alternatives.
According to organizers of the worldwide event who expect 1,800 cities to join in, the goal of the programme is to improve cities' air quality and citizens' quality of life.
The City Hall in Rio de Janeiro, which took part in the event for the first time, ordered some streets closed to traffic in districts like Copacabana and used them as a venue for recreational activities for pedestrians and cyclists.
World Car-Free Day was conceived by French activists and was launched on Sep 22, 1998, when 35 French cities launched the movement.
The first Brazilian cities started observing the day from 2001 and the number has gradually grown to Saturday's 56.