Automobiles, which usually burn gasoline, are vehicles for the transportation of people and small amounts of cargo. They are a common part of the modern world, and the number of automobiles in use has exceeded three trillion miles (five trillion kilometers). A car has four wheels, an engine, and a body. Its power may be transmitted to the front or to all of its wheels. The engine can be either water-cooled or air-cooled. Air-cooled engines are less efficient than the water-cooled ones. The motor in most modern cars is a piston-type internal combustion engine. A few models are designed with electric motors that take over braking and acceleration while the gas engine is idling, recharging the battery.
The technological foundations for the modern automobile date back to the late 1600s, when Dutch scientist Christiaan Huygens invented a type of internal combustion engine sparked by gunpowder. During the early 1900s, the automobile evolved to become a practical means of transporting people and goods. By the 1920s, it had largely replaced horses as a primary mode of land travel.
Henry Ford’s use of industrial assembly line techniques revolutionized automobile production, lowering the price of his Model T to the point that it became affordable for many middle-class families. The car’s popularity also spawned dozens of spin-off industries, such as the vulcanization of rubber to make tires and the construction of highways.
Today, automobiles are the dominant form of personal transportation, with more than 23 million registered in the United States alone. There are an estimated 1.4 billion passenger cars in operation worldwide, and they move more than three trillion miles (five trillion kilometers) each year. The car has become an essential part of everyday life and a symbol of the promise—and the perils—of modern civilization.
One of the most important benefits of owning a car is independence and freedom. A person can leave work, go shopping, and visit friends without having to depend on schedules set by others. In addition, a car can help reduce the cost of living by eliminating the need to pay for expensive public transportation tickets.
Another benefit of having a car is that it allows for greater flexibility when taking vacations. Having a car can mean avoiding airport security lines and allowing travelers to avoid having to travel on busy holidays or weekends. The ability to travel at leisure also means that family members can spend more time together, whether they are going on an outing or visiting relatives.
In some countries, having a car has the additional advantage of being a status symbol and a mark of wealth. Those who can afford to do so often customize their cars with accessories, such as stereos and custom paint jobs. In addition, the availability of automobiles has helped encourage women to enter occupations that were traditionally male-dominated, such as working in factories and other professions. During the 1910s and 1920s, many women even drove around with “vote for women” banners on their cars.
