provided may be a wind propelled rolling vehicle with a self - adjusting sail that may be substantially formed in a relatively small , single sheet of material , or assembled onto a standard chassis . the exemplary embodiments may utilize bushings to spread dynamic loads so as to allow the use of very light structural material such as thin sheet foam thereby forming a safe , low - mass toy vehicle capable of achieving good acceleration and rolling speed relative to a given wind force , and configurable into many themes .