The X4500 class are one of four classes of similar design (X4300, X4500, X4630, X4750) known as "Caravelles" as when built the engine sound reminded railwaymen of the contemporary French SE210'Caravelle' jet airliner.
The X4500 class are one of four classes of similar design (X4300 X4630) known as "Caravelles" as when built the engine sound reminded railwaymen of the contemporary French SE210'Caravelle' jet airliner. X4300 X4630 is X4750. X4300 is X4500.