A vehicle system and method that estimates or approximates the mass of a vehicle so that a more accurate vehicle mass estimate can be made available to other vehicle systems, such as an adaptive cruise control (ACC) system or an automated lane change (LCX) system. In an exemplary embodiment, the method compares an actual acceleration of the vehicle to an expected acceleration while the vehicle is under the control of an automated acceleration event. The difference between these two acceleration values, along with other potential input, may then be used to approximate the actual mass of the vehicle in a way that takes into account items such as passengers, cargo, fuel, etc. Once an accurate vehicle mass estimate is generated, the method may make this estimate available to other vehicle components, devices, modules, systems, etc. so that their performance can be improved.