The prototypes were so heavy that they could only go at 13km/h, although the design specifications said it should go at 20km/h. The problem was that there was no engine powerful enough to make it faster. It was 10.2 metres long, 3.71 metres wide, 3.63 metres tall and weighed 188 tons. It weighed so much that it couldn't go across most bridges and was designed to ford or submerge under streams.
The Maus's main armament was initially a 128mm KwK 44 L/55 with 32 rounds (based on the 12.8cm PaK 44 artillery piece, it can destroy most enemy vehicles as far as 3.5 kilometres with one shot) and its secondary gun is a 75mm KwK 44 L/36.5 with 200 rounds. Hitler changed the gun to a 150mm one when he said that the 128mm looked like a toy gun compared to the rest of the tank.
The first prototype, the V1, had a MB509 V12 petrol engine, DB603 derivative and the second prototype, the V2, had a MB517 V12 diesel engine. It has a power to weight ratio of 6.4 hb/t and the tracks hold the hull 500mm off the ground. It has a total fuel capacity of 4,200 litres and the highest operational range is 160 km on road and 62 km off-road. It has suprisingly wide tracks at 1.1 metres wide. The best armour was around the mantle at 460mm and the worst was at the hull sides and rear at 190mm. When the training grounds for the Maus were captured by the Soviets, they found the Maus prototypes and put the V2 turret on the V1 hull to make the V1/2.