Obviously this does not apply to licensed vans that work together with travel agencies on tours and events. Rio's most popular means of transportation, yet the trickiest to master. There are bus lines connecting the whole city, and unlike in the US do not need exact change. There is a professional known as cobrador sitting behind a turnstile to collect your money and give you change. Buses are not air-conditioned, and at rush hours they look more like sardine cans.
Safety is an issue to consider.
Sometimes pickpockets and petty thieves take advantage of crowded buses to prey upon commuters. With a new driving code and heaver fines and penalites, drivers in Rio de Janeiro are starting to act almost civilized. Now most cars actually stop at red lights, at least during the day, and drivers and passengers do wear a seatbelt. Hidden cameras forced speedsters to slow down in roads like the Red Line connecting to the airport, and at other problem areas. You do not need a car to get around the South Side, but it makes sense to rent one if you choose to stay in Barra or take short trips off-Rio.