A motor vehicle has a passenger compartment and two side members provided with respective rear portions, arranged longitudinally at the passenger compartment, and respective struts, which project forward of the passenger compartment; the motor vehicle has a crossbar with front attachment portions and rear attachment portions fixed to the side members by means of connecting devices, so as to keep the crossbar suspended in relation to the struts; the connecting devices have at least one weakened zone, designed so as to cause at least part of the crossbar to detach from the side members when a given load threshold is exceeded; the connecting devices have a first pierced wall, which is part of the front or rear attachment portions, a second pierced wall, which is part of the side members, and a bolt that tightens the first and second wall together; the weakened zone is defined by at least one slot cut in the first wall, beginning from a hole edge of the first wall itself.