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How many vehicles can the earth sustain?

by Michael Sivak.

​One of the hallmarks of the good life in developed countries is the freedom to move about as we choose in personal vehicles. However, as populous developing countries are gaining in economic power, people in those countries are asking for the same mobility that people in developed countries enjoy. Consequently, demand for personal vehicles has recently skyrocketed and this trend is likely to continue in the near future.

​We first reached the 10-million-vehicle level in the world in 1920, about 34 years after the first motor vehicle appeared on the road. From that level, a 10-fold increase to 100 million vehicles was reached by 1956, 36 years later. The next 10-fold increase took an additional 44 years. By 2010, we were at 1 billion vehicles. By 2015, there were 1.3 billion vehicles. Is the 10-billion level around the corner? It is not likely, given the following argument.

Let’s consider a possible scenario for 2050, when the United Nations forecasts that the world population will be 9.8 billion (up from the current 7.6 billion). This scenario is based on the situation in the United States—the country with the largest number of vehicles (about 22% of all vehicles in the world). In the United States, there is currently a vehicle for every 1.2 persons. Furthermore, the number per capita of light-duty vehicles (cars, pickup trucks, SUVs, and vans), which represent a vast majority (92%) of all vehicles in the United States, appears to have leveled off. Applying the current U.S. rate of 1.2 persons per vehicle to the projected 2050 world population of 9.8 billion leads to about 8.2 billion vehicles.

​However, there are at least three reasons why using the current U.S. motorization rate to estimate the number of vehicles in the world in 2050 is not realistic.

  • First, it is not reasonable to assume that, by 2050, every household in the world will be able to afford a vehicle.

  • Second, household size (which has an influence on vehicle demand) is greater in many countries than it is in the U.S. (The average household sizes in the most populous countries are 3.1 in China, 4.8 in India, 2.6 in the United States, 4.0 in Indonesia, and 3.3 in Brazil.)

  • Third, it is not clear whether the current focus on individually owned vehicles will continue in the future.

​Therefore, the above scenario is not a forecast, but it provides a very generous maximum that is unlikely to be reached. However, that conclusion provides no solace.

To the extent that developing countries aspire to reach motorization levels comparable to those in developed countries, the number of vehicles will likely continue to climb rapidly. We in the developed countries cannot successfully argue that the mobility afforded to us by personal vehicles is something to be curtailed in the developing countries for the benefit of us all. As a consequence, the required raw materials and energy will challenge our resources, and the resulting vehicle emissions will strain our ecological systems.

Michael Sivak is the managing director of Sivak Applied Research and the former director of Sustainable Worldwide Transportation at the University of Michigan.

​The numbers of vehicles in the world in different years came from the National Automobile Chamber of Commerce, the American Automobile Manufacturers Association, and Ward’s Communications.



A question we could ask is does everyone need a personally owned 4 wheeled ICE powered vehicle ?
Many developing nations have hoards of scooters and bicycles at a lower development level.
If you combine these with public transport (of whatever type), you have reasonable transport options (in cities and towns anyhow).
I cannot see the whole world driving around in 4 wheeled EV's either.

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