Only after I sat down to analyze the ground-breaking Mercedes-Benz automatic transmission of 1961 did I realize the true significance of the 300SE Fintail. Both the car and the transmission were well worth investigation on their own, but their combination was quite sensational. At a stroke, the company which had remained faithful to the original aging 300 Adenauer flagship model for so long had advanced once more to become not only style, but also technical leaders.

 

 

In August 1961 Mercedes-Benz launched its original Fintail, the W112 300SE. This technological tour-de-force had self-levelling air suspension, four-wheel disc brakes, and more. Yet its most important feature was the first use of Mercedes’ own in-house automatic transmission. That four-speed automatic became an increasingly popular fitment to almost all the company’s models. I must explore its features before going on to list the merits of the W112 300SE itself.

Almost from the dawn of the twentieth century, the cars which defined the Mercedes-Benz pedigree have been pioneers. In many cases, features were under development for years before they were ready to go into production, such as fuel injection and anti-lock braking, for example. Once on public view these features invariably became world leaders. Occasionally, just occasionally, management trod carefully, letting rivals take the first and often difficult steps to establish reliability and durability.  

 

 

Perhaps this explains why the company did not reveal its own automatic transmission until 1961, a full 16 years after post-war car production had resumed. Most of the firm’s serious technical rivals, including Cadillac, Lincoln, Rolls-Royce, and even Jaguar, had beaten Mercedes-Benz to it. The difference with the new Mercedes-Benz transmission was that the engineers, as always, had spent time researching, testing and making sure that everything was just so, which is more than could be said about some of the crudities exhibited by some existing rival products.

 

Even so, by the mid-1950s Mercedes-Benz, realizing the increasing demand for an automatic transmission, had cast around for an acceptable proprietary unit to use, and like Jaguar and other manufacturers, had settled on the Borg Warner Model DG. This transmission had three forward ratios and was manufactured in the United States. By 1961 the research and development of Mercedes-Benz’ own complex automatic transmission had been completed, with initial production about to begin at the Untertürkheim plant in downtown Stuttgart. First to benefit were supposed to be the 220SEb and 220SEb Coupe. 

 

However, it was the brand-new W112 300SE, not ready for sale until late 1961, that was the first model to benefit. The new automatic transmission was always intended to be standard on that model when sold in the United States, and a strongly-promoted option for all other markets. The company’s publicists made much of the new sedan’s features. This meant that the press had to sift through a great deal of technical information such as analysis of the air suspension, four-wheel disc brakes, power assisted steering, and the new aluminum cylinder block for the 3.0-liter engine before being able to look at the particulars of the new transmission.

 

 

It was clear that the new Mercedes-Benz system was different in every detail from the GM Hydramatic that Cadillac and Rolls-Royce used. Unofficially, the Mercedes engineers admitted that they had studied the details of this American transmission very closely indeed. Both the German and American units had four internal ratios and used a fluid coupling rather than a torque converter to link the engine to the transmission, but diverged in the details.

 

Cutaway technical drawings of the Mercedes-Benz transmission show what looked like a fiendishly complicated assembly, which was claimed to be only three inches longer and 30 pounds heavier than the standard manual transmission. The fluid coupling was a Foettinger component, claimed to be more efficient than any rival variety, with the manufacturer claiming that, “The aim is to provide at low slip the high torque capacity of a larger coupling, and at stall the low capacity of a small coupling.”

 

Mercedes-Benz claimed that it had saved internal space by arranging for only two planetary gear sets instead of the three used by rivals, and that the Mercedes transmission was more versatile, and therefore more usable, than any of its rivals. It was also clear that the company intended to concentrate on this transmission and its development, rather than doing much new work on manual transmissions in future years. 

 

 

The new 300SE used a derivative of the existing Fintail monocoque four-door sedan, designed in 1957 to replace earlier Ponton models. The 300SE went on sale late in 1959, and there was never any doubt that it would be the flagship of the entire range, at least for the next few years. 

 

Together with a four-inch longer wheelbase version tagged as the 300SEL, the elegant, well-detailed shape of the 300SE offered every possible new technical feature which more traditional vehicles like the Adenauer had always lacked. For those reasons, we have nominated the 300SE as a “great car for a great day.” 

 

Although the 300SE would soon be surpassed for sheer bulk and complexity in 1963 by the 600 (see The Star, January-February 2020), the 300SE would remain one of Mercedes-Benz’s most successful prestige models. To quote just one statistic, from 1961 to 1965 no fewer than 5,202 standard length 300SE sedans, and 1,546 long-wheelbase 300SEL versions were produced. 

 

We can measure how exclusive the 300SE was by comparing the overall W111/W112 production figures for all four-door sedans. No fewer than 344,551 were made, which means that only two percent of Fintails built at Sindelfingen were 300SE/300SEL types.  

 

 

Two major technical features of the new models caught everyone’s attention: the considerably redesigned six-cylinder 2,996cc engine, and the complex self-leveling air suspension, which had both been specifically developed for this new deluxe sedan. In terms of its geometry, the all-independent suspension was an evolution of what was already in use on smaller and less expensive Ponton models. Both cars included a double wishbone suspension at the front and a low-pivot rear swing axle, with power-assisted steering.

 

Mercedes-Benz, of course, was very proud of its six-cylinder M186 engine, not only for the way that it had powered that wonderful post-war star, the Adenauer 300, but for the way it had reacted so well to addition of direct fuel injection, and for its ability to make a world-wide success of the gullwing 300SL. Now, though, its design was already a decade old, but the company had no thought of abandoning this engine to history just yet. 

 

The new generation 300SE’s engine made more power, and was substantially redesigned with an aluminum cylinder block in place of the original cast-iron version. This was claimed to save 77lb/35kg in weight, and the engine boasted the latest port-type Bosch fuel injection instead of the 300SL’s direct injection. The new engine also featured a higher 9.0:1 compression ratio. However, time had marched on. The original 2,996cc engine of 1951 had produced 115 horsepower, and this revised unit made 160 horsepower. From 1964 the output would be boosted to no less than 170 horsepower.

Although the W112 had a somewhat craggy body style (engineers did not talk about, least of all try to minimize, drag coefficient back then), the new engine would be able to propel the car at up to 120 mph, enough to make it king of the German autobahn – at least for a time. 

 

 

It was the complex new air suspension, however, which must have given the company’s quality control inspection team cause for sleepless nights at first. The new system involved the fitment of pressurized units set at 120 PSI in place of conventional steel springs, and the installation of a belt-driven Warner air compressor. The system also allowed the driver to adjust the ride height of the system, and self-levelling control of the rear suspension was part of the assembly. 

 

Beyond all that, there was the need to accommodate a compressed air reservoir to make the whole thing self-adjusting. The result was a positive cat’s-cradle of piping linking front to rear, and corner to corner. The four-wheel disc brakes meant that the rears had to have torque-control arms to keep the car level under hard braking, along with sensors which were tied to the front and rear steel anti-sway bars. The fact that power-assistance was also provided to the steering gear by a Vickers engine-driven vane-type pump, made the chassis of this machine more complex than any other road car on the world market at the time. 

 

Ten years earlier, the Stuttgart company would not have been able to design such a complex machine. Development of the W112 300SE must have taken up an extraordinary amount of time, effort, and money, but it seems as if Mercedes-Benz was finally ready to prove to the world that it was back at the head of the engineering league, and ready to face up to any rival in the world with one simple challenge: Beat that! 

 

 

The company’s clientele expected that all this enterprise would come at a price, but a quotation of USA FOB price levels proved them wrong. In 1960, the last of the Adenauer-style sedans cost $10,070, but by 1962/1963, when the new W112 Fintail 300SE had established itself, the cost had dropped away to $8,662, while the longer-wheelbase 300SEL was priced at $9,910.

 

Was the 300SE still expensive? You might think so, but it is worth remembering that in those days the patrician British Rolls-Royce Silver Cloud III retailed at $16,655, and this was an old-style car with traditional styling, drum brakes, and a solid beam rear axle. Mercedes-Benz, on the other hand, was justifiably proud of the many engineering and design advances the company had made with the new W112.