The car jack comprises: a first pair of arms (1, 2), wherein each arm (1, 2) has a first end hinged to an upper striker (6); a second pair of arms (3, 4), wherein each arm (3, 4) has a first end hinged to a lower striker (8), and a second end constrained, with freedom to rotate, to a second end of an arm belonging to the first pair of arms (1, 2); an actuator (10) for moving closer / apart the points where the first pair of arms (1, 2) is constrained, in rotation, to the second pair of arms (3, 4), so as to adjust the distance between the upper striker (6) and the lower striker (8). The arms (1,2, 3, 4) and the strikers (6, 8) are made of a plastic material.