Engine

The car's engine burns fuel (usually petrol or diesel) to make power.  The engine is the vertical silver part in the pictures.

The power twists one end of a shaft, like a ship's propeller which drives it through water.  The shaft here is also silver.

The other end of that shaft connects to the driving wheels.  When these turn, tyres on those wheels "drag the road under the car", so the car moves forward.

Between engine and driving wheels are a clutch ( = a link, which allows the front part of the shaft to keep turning if the rear part stops), and some gears ( = a set of cogs like a bike's, to change how fast the rear half turns when the front half turns).

Roar !