Yes, Singapore is probably the most suitable example because it is a city-state, and an island, and so it has complete control over the number of vehicles within its territory. There is a quota in place (adjusted annually) for every type of private vehicle, administered through a Certificate of Entitlement (COE).
A number of Chinese cities including Beijing, Shanghai, Guangzhou, Guiyang and Tianjin have introduced a ceiling on the number of new car plates allocated each year. This works towards determining the maximum number of vehicles that can circulate.
Many MEGA cities in China are defining a kind of maximum amount of vehicles. For instance, Beijing vehicles increased 100,000 every year, compare to its total amount 6,000,000. It almost set the largest amount.