Abstract: For the feeding of gas to a vehicle motor, a reservoir of liquefied petroleum gas (100) is used in stages of pressure reduction (I to V). The final stage (V) in the intake conduit (T). The outlet stages (IV) and (V) comprising a plurality of pressure reducers (A.sub.1 . . . A.sub.i, respectively B.sub.1 . . . B.sub.i) with non-loaded diaphragm and operating at quasi nil excess pressure and, at starting up and slowing down, in transitory alternating working conditions with oscillatory motion of the diaphragms.Preferably, the pressure reducers of the outlet stages (IV and V) are arranged in space in accordance with the faces of a regular polyhedron.