In addition to the diesel-electric railcars of the 0300 series, diesel-hydraulic vehicles of the 0400 series were procured from 1965. These vehicles were manufactured in Portugal and were soon also called “Rolls Royce” because of the manufacturer of the engines. One power car and one control car were coupled, with the motor car having two engines. These powered one axle of each bogie via a hydraulic transmission. 

Although all 19 vehicles were later converted to the 0450 series, modernization took place in 1994 and 1995. The installation of new Volvo engines was planned, but ultimately only the interior was revised. Wooden partitions were now made of glass to improve the sense of space. Upholstery, trim and lighting have been updated and a toilet has been removed to make more room.