The HX 81 is powered by an MAN D2868 8-cylinder diesel engine with direct fuel injection. With cubic capacity of 16,160 cm³, the engine has a 500 kW (680 hp) output. In terms of off-road mobility, the HX 81 essentially matches the performance of the HX 77. The vehicle is designed to serve either as a semi-trailer or tank transporter; it has a maximum authorized gross train weight of 130 tons. This means that it can carry modern main battle tanks across rough terrain.