For 40 t heavy-duty vehicle electric powertrains, efficiency is key to maximize driving range and make best use of the energy stored on board. Reaching best efficiency while providing the required drive performance was the guideline when developing the MAHLE electric axle for heavy-duty semi-trucks. The eAxle integrates electric motors, thermal management products, transmission and differential.To cope with the high component density of the electric truck, it was crucial to implement a highly integral arrangement that optimizes the use of the installation space within the frame rails. A concept analysis showed that a twin drive unit concept was the most favorable for efficiency and package. The bearing layout was selected for optimum efficiency. The dimensioning of the axle and its components is based on standard European load cycles for heavy goods transport.The MAHLE Superior Continuous Torque (SCT) electric motor combines a 93% continuous power to peak ratio with 96.5% peak efficiency with an innovative oil cooling concept. In the electric axle, two SCT electric motors have been neatly integrated and provide in total 480 kW continuous power. Each SCT electric motor is connected to the differential independently via a two-speed gearbox. This enables the operation in partial load with one electric motor to minimize transmission losses and enables gear shifting without interruption of the traction force.The thermal management targets optimal cooling performance of electric motors and gearbox whilst meeting minimal package requirement. Three MAHLE liquid management modules including electric oil pump, heat exchanger, and oil filter, combined with the integrated oil channels minimize external interfaces. Upfront testing of the components and the measurements of the electric axle verified the targeted performance. The optimized system including the inverters, electric motors and gearbox achieves a measured electric to mechanical efficiency of 91.6%.