A hydropneumatic vehicle suspension system has a cylinder with an accumulator and a damper at each wheel. There is a supplementary hydropneumatic accumulator for each axle of the vehicle and first and second supplementary dampers connected respectively between the cylinders of the wheels of an axle and the supplementary accumulator. A valve is provided for selectively switching the supplementary accumulators into and out of communication with the cylinders of the corresponding axles. Each supplementary damper has a selectively actuable throttle for varying its damping. A soft suspension is obtained when the supplementary accumulators are switched in, a medium suspension is obtained when the throttles of the supplementary dampers are also actuated, and a firm suspension is obtained when the supplementary accumulators are switched out of the circuit.