NOVELTY - The thermoelectric generator comprises a bundle (11) comprising a first hot circuit capable of allowing a first fluid to pass through the bundle in a first direction and a second cold circuit capable of allowing the flow of a second fluid of a temperature lower than that of the first fluid; thermo-electric elements allowing an electric current to be generated in the presence of a temperature gradient generated by the first and second circuits; an inlet collector box (30) for the first fluid in the bundle; and an inlet tube (33) connected to the inlet collector box.    USE - The thermoelectric generator is useful for a motor vehicle.    ADVANTAGE - The thermoelectric generator ensures uniform distribution of the first fluid into the bundle thus improving the efficiency and electrical performance of the thermoelectric generator, and has reduced size.    DETAILED DESCRIPTION - The thermoelectric generator comprises a bundle (11) comprising a first hot circuit capable of allowing a first fluid to pass through the bundle in a first direction and a second cold circuit capable of allowing the flow of a second fluid of a temperature lower than that of the first fluid; thermo-electric elements allowing an electric current to be generated in the presence of a temperature gradient generated by the first and second circuits; an inlet collector box (30) for the first fluid in the bundle; and an inlet tube (33) connected to the inlet collector box. An extension of the bundle in a second direction, perpendicular to the first direction, is longer than an extension of the bundle in the first direction. The inlet tube is inclined relative to the second direction. The thermoelectric generator further comprises an outlet manifold (31) of the first fluid, and an outlet tube (34) connected to the outlet manifold. The outlet tube is inclined with respect to the second direction. The inlet tube and the outlet tube extend along a common axis. The inlet collector box comprises a level higher than the volume of the outlet manifold. The volume of the inlet collector box is 1-2 times higher than the outlet manifold. The inlet collector box is diverging from the inlet tube to the bundle. The inlet tube extends according to an input axis. An inclination of the inlet tube is 20-45 degrees . An inclination of the outlet tube is between 20-45 degrees . The inlet tube opens into the inlet collector box according to the second direction, and/or the outlet tube opens into the outlet manifold above the bundle in the second direction.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic side view of a thermoelectric generator.    Bundle (11)    Inlet collector box (30)    Outlet manifold (31)    Inlet tube (33)    Outlet tube. (34)