The Subaru boxer engine does not have pistons which move at an angle, like in a V-engine. In some other engines, called inline engines, the pistons move straight up and down. This engine though, has pistons that lie flat and move horizontally. This means that the engine has a lower center of gravity than the other types, which makes it more stable and balanced. Because this is more efficient than other types of piston systems, it allows for additional power to be directed to the all-wheel drive system. The boxer engine also experiences less vibration than other types of engines.