​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 […]