Peak car (also peak car use or peak travel) is a hypothesis that motor vehicle distance traveled per head of population, predominantly by private car, has peaked in at least eight major developed countries. There are two variants of the hypothesis, one (sometimes called 'saturation' or 'plateau') that having reached a peak, car use per head will continue at about the same level indefinitely into the future, the other that after peaking car use may in future show a prolonged declining trend. Places where it is suggested that car use has peaked include Australia, France, Germany, Iceland, Japan (early 1990s), Sweden, the United Kingdom (many cities from about 1994) and the United States. The theory has been disputed in the UK; the Department for Transport predicts a 50% growth in traffic in the coming 25 years and Stephen Glaister, Director of the RAC Foundation, has suggested that UK traffic will grow again as the economy improves.
Unlike the theory of peak oil, which is based on a reduction in the ability to extract oil from the ground, peak car appears to have more complex and less understood origins.
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor. Most definitions of the term specify that automobiles are designed to run primarily on roads, to have seating for one to eight people, to typically have four wheels, and to be constructed principally for the transport of people rather than goods.
The term motorcar has also been used in the context of electrified rail systems to denote a car which functions as a small locomotive but also provides space for passengers and baggage. These locomotive cars were often used on suburban routes by both interurban and intercity railroad systems.
There are approximately 600 million passenger cars worldwide (roughly one car per eleven people). Around the world, there were about 806 million cars and light trucks on the road in 2007; the engines of these burn over a billion cubic meters (260 billion US gallons) of petrol/gasoline and diesel fuel yearly. The numbers are increasing rapidly, especially in China and India.