Vehicle design engineers intuitively know that an unplanned mass increase in a component during vehicle design has a ripple effect throughout the vehicle; subsystems need to be resized to function with this additional mass. This further increases vehicle mass even more than the initial mass increase. The phrase ‘mass begets mass’ describes this phenomenon. A more encouraging view of this behavior is considering a reduction in the mass of a component enabled by a new technology, which then results in a greater mass savings due to the resizing of other subsystems because of the initial mass reduction. These secondary mass changes can be significant, and it is important to consider them during the mass budgeting process. This is because important vehicle metrics, such as fuel consumption and greenhouse gas assessments, depend upon vehicle mass.