A volumetrically efficient plastic hot fill container at least one vacuum panel defined by a vacuum panel area of a sidewall that is constructed and arranged to flex inwardly in order to accommodate volumetric shrinkage that may occur within the container as a result of the conventionally known hot fill process. Advantageously, at least a portion of the vacuum panel area of the sidewall is formed as a plurality of undulations. The undulations preferably have a horizontal component and provide an increased surface area to the vacuum panel area relative to what a flat surface would provide. As a result, the amount of volumetric shrinkage that may be accommodated through inward deflection of said vacuum panel area of said sidewall is increased relative to a flat surface would provide.