A light duty vehicle includes a vehicle frame, including a pair of vehicle longitudinal beams connected to each other by a plurality of cross-members and a cabin frame, having a pair of cabin longitudinal beams rigidly connected to front ends of the vehicle longitudinal beams. A supporting structure for auxiliary units, such as gaseous fuel tanks or electric batteries, which is carried by the vehicle frame, and includes an auxiliary frame extending between the vehicle longitudinal beams and having connection plates arranged in vertical planes parallel to a longitudinal direction of the vehicle frame and which are in contact with mutually facing inner lateral walls of the vehicle longitudinal beams and are rigidly connected to these longitudinal beams. The auxiliary frame fulfills a structural function equivalent to the structural function of one or more cross-members at an area of the vehicle frame where the cross-members are omitted.