A number of public events and seminars are being staged to underscore the theme.
In the city of Jyväskylä, 3,000 free bus tickets are being handed out. In the Helsinki region, meanwhile, public transport tickets will be available for a special low price.
Car-free day culminates in International Mobility Week, during which people have been encouraged to ponder their own transport choices, and their impact on the environment and their own health.
Mobility Week is being observed in Finland for the eighth time.