How many cars are there in the world?

How to get close to this number

Scale up from a country you know. If a wealthy country has close to one vehicle per person and holds roughly a fifth of the global fleet, as the explanation says, then the world total is about five times that country's count. Using a known share to scale a known quantity is one of the most robust estimation moves available.

The rich-country bias cuts the other way here than people expect. Car ownership is far lower across most of the world, so the global ratio is closer to one car per five people than to one per person. But the fleet is still enormous because the population is, and the growth is happening where ownership was recently negligible.

The China figure in the explanation is the story behind this number: from twenty million cars to over three hundred million within about two decades. Essentially all net growth in the global fleet is that one transition, which means projections of future car numbers are really projections about a small number of large countries. Global fleet estimates are also compiled from national registration data of varying quality, so they are good estimates rather than counts.