Speed limits set a given maximum speed for the truck. Lowering the truck speed will have significant fuel savings due to decreased aerodynamic drag and tire rolling resistance. Some fleets allow higher speeds for limited periods of time such as for passing slower vehicles. Driver fuel economy bonuses oftentimes include time at cruise control speeds as a key determination of the level of cost savings shared with drivers.
A technology overview has been published, and a more detailed Confidence Report is not planned at this time, given the simplicity of the solution.
Fuel savings result from reduced drag
In an informal survey of large fleets, fleets reported that when they lowered their speed by about 5 mph (e.g. 68 to 63 mph) their daily trip times only increased about 18 minutes.