A motor vehicle tank of plastic material has at least one opening for a connecting means which comprises a pipe portion of a plastic material which is at least substantially impermeable to the fuel and which is enclosed by a sheathing of a different plastic material which can be joined to the tank wall. At its end towards the tank the pipe portion has a part which projects beyond the sheathing and extends into the opening in the tank wall. The region of the tank wall which defines the opening is sealed with respect to the outside peripheral surface of the projecting part of the pipe portion.
