a multilayer plastic pipe having improved barrier action against diffusion of the substance being transported , particularly methanol - containing fuels , dimensional stability , and resistance to mechanical stress , is provided comprising : an inner layer and an outer layer , each of which comprise a polyamide - based molding composition , wherein the inner layer and outer layer may be the same or different , and at least one intermediate layer comprising a linear , crystalline polyester - based molding composition interposed between and bonding together the inner and outer layers .