The Pz.IV VK 40.2 was a special super-heavy tank designed in 1945 to compete with the Tiger and IS series. This model was the first prototype of the Pz.IV, equipped with a 152mm heavy howitzer. Two independent turrets were also designed, one equipped with a 37.5mm automatic grenade launcher to deal with light armor and soft targets, while the other was equipped with a triple 15.8mm heavy machine gun to deal with low-altitude targets. The tank has strong protection and weighs an astonishing 89 tons. However, it used a very powerful 12-cylinder diesel engine, and the turret was also equipped with a hydraulic drive system, which made its mobility not as difficult to handle as the Mouse tank, but due to the design of the ammunition compartment and extremely poor reliability, only three Vk40.2s were assembled as fire test platforms.