The ships' propulsion system consisted of four Belluzzo geared steam turbines powered by eight oil-fired Yarrow boilers. The engines were rated at and a top speed of . On sea trials, both "Littorio" and "Vittorio Veneto" exceeded the design specifications for their power plant. "Littorio" reached and , while "Vittorio Veneto" made and , both at light loadings. In service, however, the ships averaged . Figures for "Roma"s speed trials have not been recorded. The ships carried of fuel oil, which enabled a maximum range of at a cruising speed of . At , the ships' range increased slightly to . The entire machinery system accounted for about 5.6 percent of the total displacement.