A conventional combustion engine is a type of internal combustion engine that relies on the classic process of burning fuel to generate power. This involves mixing air and fuel in a combustion chamber, where they are then ignited by a spark plug or compression ignition. The resulting explosion pushes a piston, which turns an crankshaft connected to the car's transmission, ultimately providing motion for driving wheels. Conventional engines typically use gasoline as fuel and have been in widespread use since the early 20th century.