A vehicle heat exchanger tube comprising an internal reinforcement structure, the vehicle heat exchanger tube comprising at least a first and a second separate fluid channel (14, 16) extending along the tube and being parallel with each other and being separated from each other by at least one separating wall extending along at least a portion of the tube, each fluid channel (14, 16) having an inner height, measured in a direction being parallel with the height of the at least one separating wall, which is smaller than its width, the first channel having a first large surface, and an opposing second large surface, the second channel having a first large surface, and an opposing second large surface, wherein the internal reinforcement structure is a tube stiffener having a first stiffening portion stiffening the first channel of the tube, and a second stiffening portion stiffening the second channel of the tube, wherein the first and second stiffening portions (40, 42) of the tube stiffener are joined to each other at a joining portion, wherein the first stiffening portion comprises a first supporting surface supporting the first larger surface of the first channel, a second supporting surface supporting the second larger surface of the first channel, and an intermediate portion connecting the first supporting surface to the second supporting surface, and wherein the second stiffening portion comprises a first supporting surface supporting the first larger surface of the second channel, a second supporting surface supporting the second larger surface of the second channel, and an intermediate portion connecting the first supporting surface to the second supporting surface, wherein the tube comprises an inlet or outlet end portion (10, 34) at which the at least one separating wall has been discontinued, giving the first and second channels (14, 16) contact with each other at said end portion (10, 34), wherein the tube stiffener is at least partly received in said end portion (10, 34), and wherein the tube is characterized in that the joining portion of the tube stiffener is provided with a cut-out to receive at least a portion of the at least one separating wall, wherein the first portion of the tube stiffener extends into the first channel at least partly into that part thereof where the first and second channels (14, 16) are separated from each other by the at least one separating wall, and wherein the second portion of the tube stiffener extends into the second channel at least partly into that part thereof where the channels (14, 16) are separated from each other by the at least one separating wall. the tube comprises an inlet or outlet end portion (10, 34) at which the at least one separating wall has been discontinued, giving the first and second channels (14, 16) contact with each other at said end portion (10, 34), wherein the tube stiffener is at least partly received in said end portion (10, 34), and wherein the tube is characterized in that the joining portion of the tube stiffener is provided with a cut-out to receive at least a portion of the at least one separating wall, wherein the first portion of the tube stiffener extends into the first channel at least partly into that part thereof where the first and second channels (14, 16) are separated from each other by the at least one separating wall, and wherein the second portion of the tube stiffener extends into the second channel at least partly into that part thereof where the channels (14, 16) are separated from each other by the at least one separating wall.