A powertrain system for a motor vehicle comprises a power unit (2), a differential module (3) and a propeller shaft (4) provided to extend in a frontward-rearward direction of a vehicle body to transmit drive power of the power unit (2) to the differential module (3). The propeller shaft (4) is divided into a front shaft segment (4a) a rear shaft segment (4b) through the intermediary of a third universal joint (43), and adapted to be contracted in such a manner that the front shaft segment (4a) is fitted into an end of the rear shaft segment (4b) over a contractable range D1, together with a part of the third universal joint (43). The differential module (3) has a module body (31), and a rear support section (33) which supports the module body (31) to allow a front portion of the module body (31) to be swingably moved downwardly.