For motorists in both cities alike, that usually involves crawling through crowded streets, bumper to bumper with other cars and trucks, mostly carrying only one person.
But today is meant to be different. It's world "car-free" day, and both Prague and Rio are among more than 1,000 communities around the globe participating in the event.
In Prague at least, traffic was thinner than usual, as citizens sought to leave their cars at home and use the city's well-developed public-transport system.
Since it began in France in 1996, the car-free day has gained widening international support, mainly in Europe, but also in Asia and Latin America. In Europe this year, communities in Spain, Austria, and France are reported to be backing the scheme most enthusiastically. In Latin America, Brazil is the leading participant. In Asia, the Japanese city of Yokohama is the leader.
The event is meant to make people pause and think about how the car, the 20th century's symbol of personal freedom of movement, has become an instrument of pollution, noise, and frustration in overcrowded city streets.
As a spokeswoman for the British Royal Automobile Club (RAC), Suzy Haywood, puts it: "A car-free day certainly gives people other ideas [of how to commute] and makes them realize it is not as difficult as they thought."
However, the strength of modern man's love affair with the car is shown by the fact that even in participating communities today, many people continued to drive. City mayors and government ministers used the occasion ostentatiously to ride bicycles, but they were, of course, aware of the possibility of publicity.
Spokeswoman Haywood says motorists must be persuaded to get out of their cars by being offered better alternatives: "We are very much in love with our cars, for certain, but I mean a lot of that is caused because we do not have a viable alternative; until public transport becomes much cheaper, becomes more effective, and gets us to where we want to go quickly, we are unlikely to get out of our cars."
With traffic chaos threatening to strangle major urban centers today, city authorities are seeking other measures. For instance London has introduced a "congestion charge," which has brought about a 30-35 percent reduction in traffic during peak hours.
Under the scheme, surveillance cameras have been placed around the perimeter of the designated congestion zone in London city center. On entering the zone by car, each motorist becomes liable for a daily charge of nearly $8.
The fee is payable either over the Internet or by buying a ticket. Once he or she has paid this fee, the motorist may drive freely in and out of the congestion zone as many times as they like. But if they fail to pay, a fine is imposed which increases exponentially with every day's delay.
This system has the advantage of preserving personal freedom -- no one is forbidden to bring their car into the city center -- but at the same time, it reminds motorists of the social and environmental costs of their behavior.
Communities which are suffering from the pollution, noise and safety risks which result from heavy traffic are also demanding solutions. For instance, the German Alpine resort of Garmisch-Partenkichen lies on a main road for traffic between Germany, Austria, and Italy. Local government official Wolfgang Olexiuk says the traffic flow is enormous: "I estimate that it amounts to some 30,000 cars per weekend."
Placards have now appeared on the road demanding action on a long-sought after tunnel or ring road which would relieve the town of the traffic.
Olexiuk notes that the neighboring village of Farchant has been given a new lease on life. A tunnel was recently built allowing motorists to avoid the village.