Governments have adopted these policies due to a combination of factors, such as environmental concerns, high oil prices, and less dependence on imported oil.Among the fuels other than traditional petroleum fuels (gasoline or diesel fuel), and alternative technologies for powering the engine of a motor vehicle, the most popular options promoted by different governments are: natural gas vehicles,  LPG powered vehicles, flex-fuel vehicles, use of biofuels, hybrid electric vehicles, plug-in hybrids, electric cars, and hydrogen fuel cell cars.Since the late 2000s, China, European countries, the United States, Canada, Japan and other developed countries have been providing strong financial incentives to promote the adoption of plug-in electric vehicle. As of 2020, the stock of light-duty plug-in vehicles in use totaled over 10 million units. As of 2019, in addition, the medium and heavy commercial segments add another 700,000 units to the global stock of plug-in electric vehicles. In 2020 the global market share of plug-in passenger car sales was 4.2%, up from 2.5% in 2019. Nevertheless, despite government support and the rapid growth experienced, the plug-in electric car segment represented just about 1 out of every 250 vehicles (0.4%) on the worlds roads by the end of 2018. China
The Peoples Republic of China had 322 million motor vehicles in use at the end of September 2018, of which, 235 million were passenger cars in 2018, making China the country with largest motor vehicle fleet in the world. In 2016, the motor vehicle fleet consisted of 165.6 million cars and 28.4 million trucks and buses.
About  13.6 million vehicles were sold in 2009, and motor vehicle registrations in 2010 increased to more than 16.8 million units, representing nearly half the worlds fleet increase in 2010. Ownership per capita rose from 26.6 vehicles per 1000 people in 2006 to 141.2 in 2016.The stock of highway-legal plug-in electric or new energy vehicles in China totaled 2.21 million units by the end of September 2018, of which, 81% are all-electric vehicles. These figures include heavy-duty commercial vehicles such buses and sanitation trucks, which represent about 11% of the total stock. China is also the worlds largest electric bus market, reaching about 385,000 units by the end of 2017.The number of cars and motorcycles in China increased 20 times between 2000 and 2010. This explosive growth has allowed China to become the worlds largest new car market, overtaking the US in 2009. Nevertheless, ownership per capita is 58 vehicles per 1000 people, or a ratio of 1:17.2 vehicles to people, still well below the rate of motorization of developed countries. United States
The United States has the second largest fleet of motor vehicles in the world after China. As of 2016, had a motor vehicles stock of 259.14 million, of which, 246 million were light duty vehicles, consisting of 112.96 million passenger cars and 133 million light trucks (includes SUVs).