An electric-propulsion car includes: a main frame, a front axle unit, a rear axle unit, wherein the axle units each have an auxiliary frame for supporting the axle units and two suspension units that connect two respective wheel supports to the supporting auxiliary frame, wherein at least one of the axle units is a motorized axle with steering wheels including, mounted on said auxiliary frame, an electric motor for actuating the rotation of the wheels, a control unit for controlling said electric motor, a transmission unit for connecting the electric motor to the wheels, and a steering device for steering the wheel supports, and wherein each one of the main frame and auxiliary frames includes a reticular lattice structure including boxed elements made of steel, each one of the main frame and auxiliary frames being adapted to be pre-assembled separately and then assembled together. The main frame and auxiliary frames include elements made up of multiple segments connected together and derived from at least one boxed element made of high-tensile steel, wherein the at least one boxed element has at least one notch formed on at least one side of the boxed element without involving an ulterior side of the boxed element, the notch being made on the at least one side at the point where said ulterior side of the boxed element has to be bent to obtain the configuration of the finished boxed element.