In August 1953, Mercedes-Benz presented the Type 180 - internally code named W 120 - , the first passenger car with a ponton-type body. The "ponton" body, which had been built for the first time in 1946 in the USA, was characterised by fully integrated fenders and a rectangular plan. This concept resulted in lower air resistance, less wind noise and also in a much more spacious cabin. Another novelty in the history of the Mercedes-Benz passenger car was the integral body which was firmly welded onto the framework construction. There was a marked improvement in torsion rigidity compared to the conventional construction of the 170 models.
With these construction features, the Type 180 had a concept, which was unusually modern for those times and it was unanimously approved by automobile experts around the world; the only point of regret was the laterally controlled engine, carried over from the 170 Sb model. Although there was no real cause for complaint, with a mere 52 hp, it was somewhat lacking in temperament.
Compared to its predecessor, driving performance was improved once again; front and rear axle suspension were basically the same as in the 170 Sb, some aspects were modified, however. The wheels of the double wishbone front axle were no longer attached directly to the frame, but were suspended from a sub-frame. This was a U-shaped axle-carrier, consisting of two pressed-steel pieces, which were welded together. Not only the front wheel suspension was attached to this device, but also the engine, gearbox and the steering assembly. The sub-frame itself was tucked away in three silent blocks at the front of the frame, emitting a minimum of noise. For rear wheel suspension, the well-tried jointed cross shaft axle was used. The two wheels were now additionally guided by two longitudinal pull rods, which were situated at a great distance from each other.
In January 1954 the model series 120 was rounded off by the 180 D model, which was identical with its fuel-powered sister model except for the Diesel-engine which had been taken from the 170 DS, 12 V electric equipment and adjusted rear axle transmission. From now on, ingrained Diesel drivers could benefit too from the advantages of this modern car concept.
The Diesel as well as the fuel-powered car received a new rear axle in 1955: the single joint cross shaft axle with lowered pivot that had been introduced one and a half years before into the 220 a model and had resulted in much better ride performance due to a lower track and camber change.
Half a year later, in March 1956, a third model completed the production range of 4-cylinder models. The Type 190 was mainly based on the well-tried 180 model. It had a much more powerful 75 hp engine, however. The superiorially steered 1.9 liter unit was originally carried over from the 190 SL, but had been tamed to a large degree by compression and the use of more suppliant camshaft as well as single register carburettors. It was no longer supported at the front only, as had been the case with the 180 / 180 D models, but there were now two additional supports in the rear portion. The brakes were adjusted to the performance of the car: The Type 190 featured ribbed "turbo-cooled" brake drums as well as broader brake shoes.
The exterior of the 190 model was different from that of its more profane counterparts in that it was equipped with different details. Characteristic features were swivel windows at the front doors, chrome trimmings running below the windows, a broader radiator mask with horizontal chrome ribs, decorative trims of different lenghts along the air inlet vents extending onto the fenders to the right and the left of the radiator mask, bigger taillights, louvered wheel rims and wheel caps with a more prominent Mercedes star.
True to the motto "even more value for the same money" almost all passenger car models were presented in August 1957, some with more, some with less significant improvements. All three 4-cylinder saloons had new interiors, number plate illumination, which was integrated into the bumper guards and a recessed handle in the boot lid. The 180 model underwent the most profound changes: the revised version, internally code named 180 a, now also had a 1.9-liter engine with overhead camshaft. This was based on the aggregate of the Type 190, but was derated to 65 hp by reducing compression and the use of a simple carburettor instead of the register carburettor. Moreover, it only required regular fuel. The exterior of the 180 a , too, was upgraded: In contrast to its Diesel-powered sister model, it was equipped with bigger taillights, decorative trims at the air inlet vents and the broader radiator grill of the 190 model - the last, however, without chrome ribs.
From April 1958 the 180 and 180 D models came on the market with swivel windows in the front doors; at the same time the wheel caps of the 190 with the larger star were introduced.
In September 1958 a second Diesel model was added to the car range: the 190 D. The 1.9-liter Diesel engine with 50 hp had been developed from the petrol engine of the 190. The new engine's higher performance and quieter running (in comparison with the 180 D) meant that the new Diesel became an immediate success on the market.