The same 12-cylinder engine as in the Tetrarch was fitted to the Mk VIII, although the increased weight meant that its maximum speed decreased to . The armament remained the same as the Tetrarch's: one machine-gun and a 2 pounder main gun. The tank also kept the unusual steering system used in the Tetrarch design; this steering and mechanical system accomplished turns by the lateral movement of road wheels, which bowed the tracks. When the driver turned the steering wheel all eight road wheels not only turned but also tilted in order to bend the tracks and make the tank turn; the idea was to reduce the mechanical strain and waste of power caused by the traditional system used to turn tanks by braking one track. Unlike the Tetrarch, the steering system of the Mk VIII was power-assisted.