Plastic fuel tank with increased deformation stability

A plastic fuel tank comprising an upper wall, a lower wall and at least two compartments, said compartments being established by a dividing wall comprising a part of the tank upper and lower walls, said dividing wall having at least one communication means enabling free flow of liquids between at least two compartments and at least one communication means enabling free flow of vapors between at least two compartments, and formed by welding together a multiplicity of contact points of the upper and lower walls.