The key component in making car wheels move (and ultimately drive the car) is the internal combustion engine. Most cars on the road today burn gasoline to power the engine, which in turn moves the car. The entire process can be broken down into several parts.
Source of Energy: Fuel
The gasoline you put in your car is derived from crude oil. Once the oil has been extracted from the ground, it is taken to a refinery where it is heated and separated into different parts. The lightest parts containing gasoline evaporate and condense in a separate tank while the heavier parts sink to the bottom. After further treatment, the gasoline is ready for use as fuel for cars.
Combustion: Burning Fuel
The car's engine burns gasoline to produce energy. It works by drawing gasoline from the tank along a fuel line and into one of its cylinders. Engines differ, but a typical one has four or six cylinders. Each one, in sequence, draws in a small amount of gasoline along with a small amount of air before igniting it with a spark from the spark plugs. The small explosion resulting from the burning fuel forces a piston at the bottom of the cylinder downward. This downward motion from each of the cylinders turns the engine's drive shaft. The gases produced from the combustion, including carbon dioxide and water vapor, are drawn out of the cylinder and leave the car's tailpipe as exhaust.
Connecting the Power: Drive Shaft
A car's drive shaft is a mechanical part that connects the engine to the wheels. The drive shaft, which on most cars runs the length of the vehicle to the rear wheels, turns as the combustion engine burns gasoline. The turning drive shaft sends power to the rear axle and wheels, which cause them to turn as well, moving the car forward.
Wheels and Tires
Most cars have four metal wheels attached to the ends of the axles, front and rear. Although the wheels would turn without tires, the car would not get very far. The tires give the wheels grip on the road surface. Without them, the car's wheels would rapidly spin on the road without moving the car forward. The wheels would also damage the asphalt road. Tires are made of a special hardened rubber that fits tightly around the car wheels (rubber is liquid without being hardened first).
Different Types of Engines
Not all cars are powered by internal combustion engines. In recent years electric cars have been the focus of increased attention as an alternative to gasoline-powered vehicles. They get their energy from electricity, which provides the power to turn the car's wheels.