Even though gas engines are not particularly common in trucks or cars, they are often found in buses and small powerplants. Their number can be expected to increase due to the great supply of gas. The focus of the division's gas engine research has varied over the years, beginning with studies of combustion chambers, continuing with combustion stability, controls and prechamber studies. At present the focus is on dual fuel, meaning that a small amount of diesel fuel is injected and compression-ignited in the cylinder, thereby acting as a powerful spark plug for the gas-air mixture. This technique is used in large, stationary gas engines and to some extent in truck engines, but there are only limited research results explaining how the process works.