[3] In 1970–71 the FS ordered a further series of coaches called Gran Confort, similar to the TEEs but compatible only with the 3 kV direct current electrification system, which were destined for Trans Europ Express trains in domestic service on the Italian rail network.

[2] At the inception of the first Trans Europ Express lines, most of the planned links were not yet fully electrified, and the service was entrusted to Diesel self-propelled trains expressly built by the railway administrations that had joined the TEE grouping.

[9] In the following years, with a view to solving the above electrification problems, the replacement of the TEE railcars was taken up by the FS with two proposals developed by its Material and Traction Service, which had as a common element the realization of an electric-powered trainset that, like the Swiss electric train, did not require the replacement of the traction unit at the borders:[8] The ordinary-material solution, which would have offered 40 percent more seats for the same cost, led to a study in which, in addition to the four-voltage locomotive, three models of carriages derived from the X-type were defined, namely a 54-seat first-class carriage, a 30-seat first-class carriage with luggage compartment, radio cabin and customs compartment, and a 42-seat dining car, 12 of which could be reserved, with crew compartment, pantry and kitchen.

[12] The final solution came in 1967, when the FS entrusted FIAT – Railway Material Division of Turin with the study of a new series of coaches with a high degree of comfort, meeting the international standards set by the TEE grouping and capable of traveling at speeds of 200 km/h (120 mph).

[1][13] In 1969, following the positive outcome of the studies, the FS ordered a group of 28 TEE carriages from FIAT, subdivided as follows:[14] The first car with F.71 bogies began trial runs in late 1970.

Finally, details such as the electrically operated Venetian blinds incorporated between the double glasses of the large windows and the closets for storing clothes behind the seats in the compartment cars were not neglected.

With regard to safety, FIAT's engineers did not stop at strict compliance with the standards of the Union internationale des chemins de fer (UIC) Form 567, which was mandatory for the carriages to be admitted to international service, but went further, making the structural design of the body so that it provided greater protection than required for passengers in the event of a collision.

The coaches were made compliant with the International Coach Regulations (RIC), enabled without restriction to board in normal service on the ferries of the Italian, German (Deutsche Bundesbahn – DB), Danish (Danske Statsbaner – DSB) and Swedish (Statens Järnvägar – SJ) railroads according to UIC board 569, and enabled to run coupled on curves with a minimum radius of 80 m.[16] The need to run on the Western European rail networks, which were electrified with four different power systems, and the high demand for electricity from carriage services (particularly from air-conditioning equipment)[17] required the use of multi-voltage converters that were not available at the time with sufficient power levels and reliability.

This choice, which was almost obligatory, allowed a significant lightening of the carriages and quickened the maneuvers of switching the power supply at border stations, but made the presence of the generator wagon indispensable in the composition of the trains.

The results of the structural analysis led to a major revision of the previously used concept, which was replaced by a new scheme consisting of an H-shaped frame made up of two double swan-neck shaped stringers and lacking the end cross members.

Each unit comprised a copper coil for refrigeration and an electric radiator for heating, which were invested by a flow of air produced by a pair of centrifugal fans that, after dehumidification, was fed into a distribution ducting that led to vents located on the top of the carriage.

Finally, from the latter was obtained by means of an inverter the alternating voltage of 220 V 50 Hz, which was necessary for the supply of the utilities that had to be ensured even in the absence of the locomotive, such as the lighting of the carriages and the sockets for razors and towels in the toilets.

In addition to being distinguished by a different exterior livery, characterized by the lower part of the body and the roof in slate gray[36] and an antique ivory band[36] with two signal red threads[36] at the windows,[37] the Gran Confort differed from the TEEs in the electrical power supply system for the auxiliary services, which, instead of the pair of centralized rotating units on the generator van, provided for the installation on each carriage of a 45 kVA motor-alternator powered at 3 kV direct current directly from the electric heater pipe.

Each pair of couches was equipped with removable tables, sheltered in special compartments under the windows, which allowed the carriage to be used to subsidize the dining car in case of need.

[2][39] The cars, for whose furnishings materials were chosen to ensure comfort and ease of cleaning, included, in order, the following rooms:[40] The kitchen was equipped with an electric stove and a sink with hot and cold water.

In the case of high composition trains, since parallel connection of the alternators was not planned, it was necessary to place the generator van in the middle of the convoy so that each section would be independently powered.

However, a fairly frequent series of breakdowns soon highlighted the inadequacy of the initial choice of a single motor-generator to power more than five coaches, forcing the FS to take remedial action.

After an initial period of line testing to verify the influence of disturbances generated by on-board equipment on the telephone and signaling circuits of the railway administrations concerned, they were put into regular service on May 28, 1972, on the TEE Lemano between Milan and Geneva.

[45] Toward the end of the 1970s, the commercial policies of passenger rail transportation began to evolve toward a system that could provide services with high quality and speed features to a wider customer base.

These new trends led the French and German railroads to establish the first Intercity lines as a replacement for the corresponding TEEs, often retaining their name and train path by expanding the service to second class.

[2][55] The dining cars, converted from the early 1990s with the elimination of the boarding doors on the side opposite the kitchen as for the newer Gran Confort series, were reclassified 50 83 88-90 900-905 WR.