The locomotive was commissioned to replace and expand the freight service operated by the aging 254 series.

While originally delivered in a red livery, the locomotives were repainted green to match FGC's corporate identity.

The locomotive is based on the Stadler SALi (South American Light Loco), a version of the Euro Dual for a meter gauge railway operated by Ferroviaria Andina in Bolivia.

[1] The locomotives are used to transport two main cargo types; potash and salt trains from the Súria mines and cars from the SEAT factory in Martorell, along the Llobregat–Anoia Line to the port of Barcelona.

[2] The dual power technology of the 257 series allows trains to draw power from the 1500V catenary used by commuter trains (FGC 213 Series) in the mainline tracks between Sant Boi and Manresa while operating as a diesel train in the non-electrified industrial branches.