At the Frankfurt International Motor Show IAA, in September 1977, the so-called "T-Model" was presented as the third body variant of series 123. "T" was to be interpreted as "tourism and transport". For the first time a estate solely produced by Mercedes-Benz was part of the official model range. From April 1978 onwards, the production was carried out in the Bremen plant. Having been reserved to the manufacturing of delivery trucks before, it now step by step was equipped to assemble passenger cars.
Technically and stylistically the estates corresponded mostly to the saloons on which they had been based. Except for the deviant tail end and the thus resulting changes, no differences could be seen. Aggregates, brake system and chassis were practically taken over unchanged from the saloons. Thus the estates, too, were equipped with a semi-trailing arm rear-axle. In the standard version, however, it was now combined with a hydropneumatic levelling system as well as with a double-wishbone front wheel suspension with zero steering offset.
The estates saw an immediate success and were offered with Diesel and petrol engines. At first, the model range comprised Types 240 TD, 300 TD, 230 T, 250 T and 280 TE. As with the saloons there were differences in the equipment of the body. Only the top model 280 TE exhibited rectangular wide-band headlamps and chromed air-inlet grills in front of the windscreen. All other types were equipped with the characteristic twin head-lamps and the black air-inlet grills.
In the years 1978 and 1979 the same changes were made in the range of engines of the estates as in the corresponding saloon types. First in August 1978 the performance of the 240 TD was stepped up to 72 hp. One year later, in September 1979, the 5-cylinder Diesel engine of the 300 TD as well as the 6-cylinder carburettor engine experienced a power increase.
Between June and November 1980 three new variants completed the type program of the estates. In June the 230 TE was presented. It replaced the 230 T with carburettor engine which had been produced for two years. The totally redeveloped 2.3-liter 4-cylinder engine with mechanically controlled petrol injection mobilised 136 hp and superseded the traditional carburettor engine, equal in piston displacement, not only in the estates, but also in coupé and saloon.
In October 1980 the series production of Type 300 TD Turbodiesel started. It had already been presented in the autumn of the previous year. It was equipped with the 125 hp strong version of the 3.0-liter 5-cylinder engine, which from that time onwards was also built into the S-Class export model 300 SD. The 300 TD Turbodiesel was the first Mercedes-Benz passenger car with turbocharged engine that was available on the domestic market. In terms of price it took the top position within the model series. Accordingly, it presented itself, as the 280 TE, in the upper body equipment with rectangular wide-band headlamps and chromed air inlet grills infront of the windscreen.
Since November a further estate variant left the assembly line. It had already been presented to the public in June together with the 230 TE. The new Type 200 T had a 2.0-liter 4-cylinder engine with 109 hp which had been developed together with the 136 hp strong 2.3-liter injection engine. Both aggregates were different versions of the M 102 engine series which had been designed from scratch.
Furthermore, all models now were delivered with a power steering as standard equipment and with ALS (August 1980) and airbag (January 1982) on demand.
In September 1982 the estates as well as the other type families of series 123 benefitted from a comprehensive model improvement. The most conspicuous characteristic of the improved variants was the rectangular wide-band head lamps which so far had only been built into top models. The air-inlet grills in front of the windscreen were now all black. In order to minimise wind noise the protecting cover of the A-pillars was optimised. A number of details of the interior equipment were also improved. For 250 T all these measures, however, were too late. Its production had already been stopped in August 1982. In January 1986, production of the first Mercedes-Benz estate range was discontinued. The successors had already gone into series production in October/November 1985. In a period of more than eight years 199,517 units were manufactured in the Bremen plant.