An exhaust gas system includes an arrangement for conveying an exhaust gas stream and a thermodynamic engine connected to the exhaust gas stream conveying arrangement for recovery of heat from the exhaust gas stream. The thermodynamic engine includes a working fluid circulation circuit. The exhaust gas system includes at least one working fluid release arrangement which is connected between the working fluid circulation circuit and the exhaust, gas conveying arrangement for releasing the working fluid from the working fluid circulation circuit to the exhaust gas conveying arrangement. The exhaust gas stream conveying arrangement includes at least one exhaust gas treatment unit. Further, the working fluid release arrangement is connected upstream of or directly to the exhaust gas treatment unit.