Automobiles are self-propelled vehicles that are used for passenger transportation. They have four to eight wheels and are powered by an internal combustion engine or electric motor. The branches of engineering that study the manufacture and technologies of automobiles are known as automotive engineering.
Automobiles can be made in many shapes and sizes to suit different needs. For example, sports cars are designed to be fast and have a high power-to-weight ratio. Other vehicles are more spacious and practical, such as SUVs, which offer off-road capability, space, and four-season utility. Some have a convertible roof that can be opened for an open-air drive. Others are designed for comfort and have features such as air conditioning and satellite navigation systems.
The benefits of automobiles include the freedom and independence they provide to their owners, as well as their ability to carry goods. But they also come with costs, such as maintenance and the need to find a parking space. They can also produce pollution when too many are driven in urban areas, contributing to climate change. Accidents and other incidents involving automobiles can cause serious injuries or death. This can be due to human error such as a mistake by the driver, or because of faulty car design such as a vehicle with a high centre of gravity that rolls over easily.
The safety of automobiles has improved greatly over the years. This is partly because of laws requiring the use of seat belts, and the introduction of advanced airbags. It is also because of advances in technology such as electronic computers, high-strength plastics, and new alloys of steel and nonferrous metals.