Those railcars were introduced in the 1960s to replace the existing rolling stock of most of the urban services of Argentina, such as Roca, Urquiza, Mitre and Sarmiento lines.

They are commonly nicknamed Chanchas (Spanish for Piggies) In 1958 the Ministry of Transport of Argentina signed an agreement with Fiat Ferroviaria to acquire 210 brand-new railcars.

Although the first railcars were manufactured in Italy and France, most of them were made in Argentina, in a factory specially designed for that assignment located in Ferreyra, Córdoba and named "Materfer".

The train featured extensive use of stainless steel, was originally named the Zephyr, and was meant as a promotional tool to advertise passenger rail service in the United States.

The Mitre Line's concessionary, Trenes de Buenos Aires, then acquired 8 new units made by Materfer and soon nicknamed them Pitufos (a Spanish translation for "Smurfs") due to their small size.

[3] A short revival of the 7131 occurred in 2008, when defunct company Trenes Especiales Argentinos used a railcar (that had been previously refurbished[4]) to run the Gran Capitán service between F. Lacroze to Posadas, Misiones.