The present invention provides an assembly of an aluminum-based element and an element made of steel provided on at least one of the surfaces thereof with a metal coating. The metal coating is made of a zinc-aluminum-magnesium alloy including from 2.3% to 3.3% by weight of magnesium and from 3.5% to 3.9% by weight of aluminum. The remainder of the metal coating is zinc, inevitable impurities and possibly one or more additional elements selected from among Si, Sb, Pb, Ti, Ca, Mn, Sn, La, Ce, Cr, Ni or Bi. The coated surface of the steel element is in at least partial contact with the the aluminum-based element. The contact is brought about by a layer of adhesive or sealant having a thickness of less than 5 mm. The present invention also provides a part for a vehicle including at least one assembly and a vehicle.