Mercedes 300 SL

Mille Miglia cars

The Mercedes-Benz 300 SL is characterized by refined technical solutions, as well as an exterior line that has fascinated entire generations of enthusiasts, with it Daimler-Benz reaffirmed its prestige in those sectors that had made it famous in the pre-war period, namely the class and elegance of its cars, but also their weight in sports competitions.
Another factor that gives great importance to the 300 SL is the fact that it is the progenitor of a whole series of luxury sports cars marked with the acronym SL, an acronym still used today and which stands for Sport Leicht, or Light Sport.
The history of the 300 SL has its roots in the moment in which, in 1949, Daimler-Benz was allowed to once again produce cars. Until that moment it had not been allowed by the Allied authorities who occupied and divided the German territory after the end of the Second World War. The only exception was the W136 range, the design of which dated back to the 1930s.
One of the priorities that Daimler-Benz set itself was to return to winning in motor racing all over the world. A car had to be designed and built that could fulfil this purpose, keeping in mind that the economic resources were not yet sufficient to develop a car from scratch, specifically for competitions. It was therefore necessary to make do with what was already available. It was 27 March 1950. The project was entrusted to Rudolf Uhlenhaut, a brilliant designer of the German company, who in a relatively short time created the 300 SL racing car, powered by the 3-litre M194 in-line 6-cylinder engine, which was also not new, but in turn derived from the 3-litre M186 mounted on the large Typ 300 sedans. The gearbox and suspension were also taken from the series production. This car would go on to win virtually every race it entered (with the exception of the 1952 Mille Miglia, won by a Ferrari 250S). The most visible feature of this car was its tubular trellis chassis, a lightweight solution with considerable rigidity that was unknown at the time. This structure, which was very bulky along the sides, especially at the height of the doors, forced the designers to design doors hinged on the roof rather than on the fender. This solution had a great scenic effect, which is still very pleasing today.

It was at that point that another very particular character entered the scene, a certain Max Hoffman, an importer of European cars in the United States, who proposed to the German manufacturer to produce a series version of the 300 SL racing car, duly modified where necessary for road homologation, and with a few more refinements. Hoffmann personally committed to purchasing 1000 examples of the finished road car, guaranteeing results in terms of sales. It was a bit like the same thing that happened in 1900, when a certain Emil Jellinek ordered 36 cars produced by DMG to his specifications.
For the engine, they chose to use a cutting-edge solution, represented by direct injection, at a time when all petrol cars were carbureted. The base remained the usual 3-litre, but performance underwent a significant increase. Furthermore, the aesthetic part was entrusted to Karl Wilfert and Friedrich Geiger, the latter already author, before the war, of the splendid bodies of the 500K and 540K. After having created some non-definitive prototypes, the two managed to design a very pleasant car body, characterised by elements that would make its design famous, many of whose stylistic solutions would be imitated and taken up by other car manufacturers in the following decades.

Mercedes-Benz 300 SL "Gullwing" (W198 I)
View of the special tubular frame used in the 300SL Gullwing

The 300 SL coupé, known internationally as the Gullwing (i.e. Seagull Wings, in Italy) for the characteristic opening of the two doors hinged above the roof, inherited the tubular frame from its racing "sister", a very cutting-edge solution at the time it was presented, on 6 February 1954 at the New York Motor Show.
It allowed for high torsional rigidity, while maintaining a low weight. The tubular cage, with its very pronounced development along the sides, was the cause that led the designers to create the famous gullwing doors.
This frame was later "dressed" by a splendid coupé body that still inspires great admiration today. The front, typically Mercedes-Benz, however, already appears more modern than the rest of the production. The body of the car is related to the racing 300 SL, from which it differs however in its longer bonnet, the front with a p

more decisive, the characteristic "whiskers" on the wheel arches and the air intakes on the front fenders. Even the tail, which apparently was the part least involved in the restyling, was redesigned to give greater dynamism to the overall view of the car. Some stylistic features used on the 300SL would be dusted off decades later by Mercedes-Benz itself for some of its new models, such as the two longitudinal ribs on the front bonnet, which were also used in 1997 on the first series SLK.
The body is made of sheet steel, but 29 examples were also made with an aluminium body and intended for competitions, which for the 300 SL W198 were reserved only for private drivers. There was also an example with a fibreglass body.

From an engine point of view, the 300 SL Gullwing was equipped with the 3-liter in-line 6-cylinder M198 engine, derived from the Typ 300, albeit indirectly. This engine was the first to use injection fueling on a road car. The mechanical injection system, in this case of the direct type, was developed in collaboration with Bosch.

The engine of a 300 SL Gullwing

The idea of ​​this new type of fueling was suggested by Hans Scherenberg, a brilliant engineer already employed by Daimler-Benz Avio, the aeronautical section of Daimler-Benz. Scherenberg had in fact used injection fueling on the planes used in the Second World War. In reality, this engine was already intended to be used on an advanced version of the 300 SL racing car, the W194. But the project never came to fruition and the new engine, initially destined to be a failure, took advantage of Hoffmann's order to be mounted on the 300 SL road car. The M198 engine delivered up to 215 HP of maximum power and guaranteed performance at the absolute top of world automotive production at the time.

As for the transmission, this made use of a 4-speed synchronized gearbox with a single dry plate clutch and a ZF self-locking differential.
The suspensions were independent: the front axle had quadrilaterals and a stabilizer bar, while the rear axle had oscillating half-shafts with a single articulation and longitudinal arms. This last solution, which characterized the production of all 300 SLs with coupé body, proved to be unsuitable for a sports car of its rank and was replaced in 1957 with the arrival of the roadster. Coil springs and hydraulic shock absorbers were also mounted on both axles.
The braking system consisted of four finned drums in aluminum alloy, with a hydraulic circuit and brake booster. The technical picture was completed by the recirculating ball steering.

The splendid lines of two 300 SL "Gullwings" with the characteristic open doors

The performance of the 300 SL was remarkable for the time: the maximum speed was between 220 and 258 km/h, depending on the axle ratio, which could be chosen from five different variants. In the mid-fifties, this feature was the prerogative of racing cars only and had never happened before in a road car. And in fact, even if only for a short time, the 300 SL Gullwing was able to boast the record of the fastest production car in the world. Regarding acceleration, the car reached 100 km/h from a standstill in 10 seconds. As for consumption, the 300 SL coupé traveled an average of 100 km with 17 liters of fuel. Pushing hard, the requirement reached 19 liters, but at a leisurely pace it could also go down to 12 liters.

The particular physical structure of the 300 SL's body forced those who climbed aboard to literally climb over the threshold to access the passenger compartment, which was decidedly very high due to the considerable bulk of the tubular frame along the sides. Once inside, they had to let themselves fall back onto the seat. In short, they had to have a certain physical predisposition, a fact that could have repercussions on the sales of the car, according to the German company. Furthermore, it was Max Hoffmann again who pointed out to the Daimler-Benz top brass how such a method of accessing the passenger compartment could be uncomfortable for a lady wearing a skirt. It was for this reason that in 1957 the 300 SL Gullwing was discontinued and replaced by the corresponding roadster version, which was positioned at a higher level than the 190 SL, introduced in 1955 and inspired by the 300 SL in its external aesthetics.

Mercedes-Benz 300 SL Roadster (W198 II)

Introduced in 1957, the 300 SL Roadster (W198 II) differed from the previous coupé in many respects. The most obvious was clearly the different body configuration, this time with traditionally opening doors, made possible by an appropriate revisitation of the tubular lattice frame, pr

ivato of part of the belt line tubes and strengthened for compensation by tubes placed between the transmission tunnel area and the part relative to the tail, in order to maintain torsional rigidity despite the absence of the roof. Aesthetically, the roadster also offers a front where the new vertically developed front headlights stand out, helping to clearly distinguish it from the smaller 190 SL.
There were also innovations from a technical point of view: the engine benefited from a new, more powerful camshaft, in order to bring the maximum power to 225 HP. New solutions also in the rear, equipped with a transverse spring to compensate for the lateral thrusts, in order to make up for the defects of the rear used on the coupé.
In 1958, for the 300 SL Roadster, the hard-top was made available, at an extra cost. In 1961, there were other significant innovations, consisting of the new M198 III engine with aluminum alloy monoblock, disc brakes on the 4 wheels and the new steering box. On some pre-1961 models, during restoration, the 4 disc brakes were mounted, to the detriment of originality, but with beneficial effects from the points of view of functionality and safety.
The performance remained considerable, even if slightly lower. Depending on the axle ratio, the maximum speed was between 215 and 250 km/h.
The production of the 300 SL Roadster ceased in 1963. The legacy of this car will be partially collected by the W113 range, which will also and above all replace its sister 190 SL. But today there is disagreement on this, because there are also those who argue that in fact the first car from the company capable of worthily replacing the 300 SL arrived only 40 years later, when the SLR McLaren was launched.
In fact, the W113 range was halfway between the two previous models, because it was more powerful and exclusive than the 190 SL, but never as much as the 300 SL.

Mercedes-Benz 300 SL AMG
In 1996, AMG mechanically updated 11 examples of the 300 SL. These models, which remained unchanged in design, featured new alloy wheels wrapped in sports tires, a new propulsion unit represented by a V8 engine managed by a four-speed W4A automatic transmission, a new catalytic converter for the management of harmful emissions, Bilstein suspension, braking system derived from the Mercedes-Benz AMG C36 and new interiors.