Cars have been powered in a lot of different ways since their invention! Steam, electricity, gasoline and diesel have all been used for over a century. Engineers also tried to use nuclear-powered engines in the 1950s and 1960s, but these didn't work. Nuclear cars were never more than scale models.
Electric cars are becoming popular again today. Many companies have plans to start making mostly or only electric or hybrid cars. But most cars still use an internal combustion engine that runs on either gasoline or diesel fuel. The engine contains a number of cylinders (usually four, six or eight). Each cylinder contains one piston that moves up and down in a pattern with the other pistons.
The piston first moves down, which sucks fuel and air into the cylinder. Next, the piston moves up and squeezes the fuel and air. A small spark in the cylinder lights the fuel on fire, causing an explosion that pushes the piston down again. The final movement is when the piston moves up and blows out all of the exhaust from the cylinder.
Now it's ready to repeat this cycle. The cycles happen very quickly. Even when a car is stopped at a red light, each piston is still making hundreds of cycles every minute. The revolutions per minute (RPM) increase when a car is moving. Vroom vroom!
