The power transmitted during actual driving is an important parameter for quantifying the efficiency of drivetrains. The driving power is calculated from the torque and speed of the shaft. The D^x-Power system makes mechanical power measurements on axles and shafts as simple as child’s play. The system does not require an additional stator or reference point. The sensor unit (D^x-SCT) is mounted directly on the vehicle axle using a half-shell housing. There it records the torque (via strain gauges) and the speed via an integrated rpm sensor. The measured data are telemetrically transmitted to the D^x receiver unit (RCI) inside the vehicle. The receiver unit calculates the synchronous values of the two signals in real time according to the formula Power = Torque x Speed and displays all values in physical amounts.