The principal problem in the design of the "Maus" was developing an engine and drivetrain which was powerful enough to adequately propel the tank, yet small enough to fit inside it — as it was meant to use the same sort of "hybrid drive", using an internal-combustion engine to operate an electric generator to power its tracks with electric motor units, much as its Porsche-designed predecessors, the VK 30.01 (P), VK 45.01 (P), and Elefant had. The drive train was electrical, designed to provide a maximum speed of and a minimum speed of . However, during actual field testing, the maximum speed achieved on hard surfaces was with full motor field, and by weakening the motor field to a minimum, a top speed of was achieved. The vehicle's weight made it unable to use most bridges, instead it was intended to ford to a depth of or submerge up to a depth of and use a snorkel to cross rivers.