Abstract: Devices and methods for improving fuel efficiency are disclosed herein. According to aspects illustrated herein, there is provided a device for improving fuel efficiency of a combustion engine. The device may include a housing for attachment to an exhaust pipe of a combustion engine and having a pathway extending therethrough. The device may further include a wound body disposed at a distal portion of the housing and designed to permit fluid from the exhaust pipe flowing along the housing to flow through the wound body. In addition, the device may include a barrier positioned within the pathway downstream from the wound body so as to generate a sufficient back pressure along the exhaust pipe to enhance piston stroke efficiency in the combustion system, resulting in an increase in fuel efficiency of the combustion engine.