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The SL: Five Generations of Motoring Excellence
by Marcus B. Fitzhugh

On June 15, 1951, the Daimler-Benz Board of Management reached a decision that impacts us to this day: Mercedes-Benz would return to worldwide motorsports. In the 1950's, this decision led to Mercedes-Benz winning multiple Formula 1 world championship titles, the constructors' crown in the sports car category, the European Touring Car Championship, and the Sports Car Championships of both Italy and the United States. It was also the foundation for the legendary SL.

Very few combinations of letters have achieved the charismatic appeal of the name "SL". This was actually conceived simply as an abbreviation for "sporty" and "light". These two letters today represent the continuation of a living legend.

The legend began in the grey post-war period. Purses were empty, the Autobahns virtually deserted, and there were more than enough parking spaces to go round. Policemen stood at crossroads directing traffic because there were few traffic lights. This was a dark time for German auto manufacturers, but there were visions; one of which was to see the Mercedes-Benz 300 SL. Due to cost implications and a shortage of time, the original SL wasn't a "clean sheet of paper design". For this project, the W186 sedan (the famous "three hundred") was used as the technical basis. Despite the restrictions, we can see this sports car was successful right from the start. Rudolf Uhlenhaut, who was a vital catalyst to the 300 SL project, later said "We took the standard engine from the 300 and built a tubular frame and aluminum body around it."

The concept proved to be a good one and, in 1952, an SL was already second across the finishing line of the famous Mille Miglia rally. But the true charisma of the two letters really became apparent later that same year, when the 300 SL took part in the Carrera Panamericana. The magnificent double victory of Karl Kling and his co-driver Hans Klenk, and Hermann Lang and Erwin Grupp in this notorious long-distance race made the gullwing coupe the focus of attention. This was confirmed by the 300 SL having been the fastest in Berne, at the 24 Hours of Le Mans, and on the Nürburgring - all in the same year.

Impetus from the US

Despite its success on the racing circuit, at that point it was still a "race car". The 300 SL, as a road-going sports car and thus as the nucleus of all SLs, was almost never built. The future of the SL was heavily influenced by a message that came from the US. That message was from an Austrian gentleman, Max Hoffman. Hoffman wanted to buy cars from Daimler-Benz that didn't exist.

Mr. Hoffman is still known today by the nickname of "Maxie". This brilliant salesman had a real sense for trends and what might become one. Maxie was convinced that he could sell 1000 road-going versions of the Mercedes-Benz 300 SL on the North American continent. Thanks to its racing success, the sports car had become famous in Europe. Maxie approached Daimler-Benz and proposed that a production car for the public would sell in the US. Hoffman's arguments convinced Daimler-Benz's Board of Management, and the road-going version of the 300 SL was revealed at the international motor show in New York on February 6, 1954.

1957 to 1963: the gull-wing model becomes a roadster

Three years later, in March 1957, the gull-wing model was succeeded by the Roadster, which continued to be produced until 1963. Once again, the US market was a deciding factor in this decision. Here in the US, powerful, open cars were all the rage. From 1958 onwards, the Roadster, whose long, vertically arranged headlamps also differentiated it from the coupe, was available with a hardtop as well. This was the foundation for the Mercedes-Benz philosophy that an SL should be open but, at the same time, suitable for all weather driving.

The 300 SL was immensely popular in both versions, and enthusiasts from all over the world wanted to buy one. The well-known German motor journalist and author, Fritz B. Buch, stated - "It has lodged itself in my heart." It is no surprise that the coupe version was honored with the title of "Sports Car of the Century" at the conclusion of the 20th century.

The 300 SL was a jewel on wheels. International celebrities shared this view and were frequently seen in the Mercedes-Benz sports car. Film star Zsa Zsa Gabor bought herself a 300 SL, as did the newspaper magnate William Randolph Hearst. Aristocratic heads such as the Duke of Edinburgh and Shah Reza Pahlevi were just as proud to drive the SL. Even the King of Rock n Roll, Elvis Presley, bought an SL.

Direct injection for 210 hp of power

The Mercedes-Benz 300 SL was not just an object of popularity and respect: for many it represented, quite simply, the epitome of the modern sports car. 215 hp from an engine displacement of three liters and (for those times) an incredible top speed of over 250 km/h proved its true sporting ancestry. Dr. Rudolf Uhlenhaut, the "father" of the SL, made it quite clear when he said, "Feel free to consider the SL models as sports cars - as long as the emphasis is on Sport."

The 300 SL was, to its core, a high-tech product in the innovative tradition of Mercedes-Benz. Starting with a basic straight six-cylinder engine that produced 115 horsepower, the racing engineers bred a high-performance unit. To increase power to 210 horsepower, they developed the first direct gasoline injection system for a production passenger car with a four-stroke engine. The injection jets were positioned in the upper part of the cylinder wall where, in a normal 300 engine, the spark plugs were located. In the SL engine, the spark plugs were moved to the side of the cylinder head. Porsche began using this same direct injection technology over fifty years later. The engineers at Mercedes-Benz were truly ahead of their time.

With the addition of a sports camshaft and a compression ratio of 8.55:1, the engine produced 215 hp at 5800 rpm. This engine had a power output of 71.5 hp per liter at a time when most engines made 30 hp per liter of displacement. The SL' engine speed was also quite impressive. Mercedes-Benz claimed a 6000 rpm cruising speed, with a 6600 rpm maximum speed. Back then, engine speeds over 4000 rpm were rare.

Each of these high-performance engines was tested for 24 hours on a test bed, with one in six tested at full throttle. The engines would then be dismantled and checked before being re-assembled and subjected to an additional eight hours of endurance testing. Only after this procedure had been completed, were they considered fit to be installed in the SL Roadster.

Bodywork engineering based on aircraft construction

An even greater technical sensation was caused by the car's tubular frame. This was a principle derived from aircraft construction. The intricate construction was performed by experts who had welded individual fine steel tubes. This produced a frame that was light, yet rigid. Efforts to make the frame as sturdy as possible in the original coupe version resulted in a very high sill which left no room for normal doors. This inevitably gave rise to another spectacular innovation that was to become the hallmark of the 300 SL: its gull-wing doors. However, when it came to the Roadster, the engineers redesigned the tubular frame construction by lowering it in the door area. This made getting in and out easier and increased trunk space. The idea behind the open-top car had always been to offer a sporty tourer or luxury convertible.

A further prominent feature of the SL models of the nineteen-fifties were the crescent-shaped protrusions over the wheels. This gave the SL a striking appearance. These were originally designed to protect the sides of the vehicle from dirt and damage from loose gravel. They were officially known as "splash shields".

The Mercedes engineers also improved the Roadster in other important points. For example, it was given a new single-joint swing axle with a lower pivot point and compensating spring. This was superior to the original double-joint axle and was less demanding on drivers driving at the limits. From 1961 onwards, SL Roadster also had four wheel disk brakes - a rarity for its era.

In regard to the 300 SL Roadster, Road & Track magazine wrote "When a comfortable interior is matched by remarkably good vehicle handling, with wheels that grip in what can only be described as an incredible fashion, with light and precise steering and with performance that is as good as, if not better than, any car so far built, then there's only one thing left to say: the sports car of the future has arrived!"

Unfortunately, this dream had to end. On February 8, 1963, production of the 300 SL ceased. Up until that point, 3,258 cars had been built, 1,858 of them as Roadsters.

1963 to 1971: forms that move

The SL is a story with many sequels. The successor to the 300 SL was already waiting in the wings and celebrated its premiere at the Geneva Motor Show in 1963. This was another eye catching model from Stuttgart. This wasn't so much because of it being a concept that offered improved spaciousness and touring comfort. Those features had already been signed off on back in October of 1958. That was done by the Board Member responsible for Passenger Car Development, Professor Dr Fritz Nallinger. The attraction here was more because of its unusual appearance for that of a sports car. It was the unusual proportions and lines of the car that differentiated the 230 SL (internally known as the W113) from all others. Its dominant design feature was a removable hardtop which, unconventionally, was lower in the middle than at the sides.

Appropriately enough, this sports car became known as the "pagoda". This was because its roof was reminiscent of Japanese temple architecture. Yet the reasons behind this development were not so much those of style as of safety. Mercedes engineer Béla Barényi, the pioneer of modern safety engineering, had already designed and patented this unusual roof shape in 1956. He recognized the advantages that it offered in terms of rigidity, thus offering the vehicle occupants maximum possible safety. Similarly impressive was the generous headroom in the 230 SL, even with its "pagoda roof" in place.

Sport and comfort combined

This second SL generation aroused conflicting opinions among many people at the time. The 230 SL was a true tourer, but its performance was certainly not that of a tame cruiser: its 2.3-liter six-cylinder engine produced 150 hp, and the top speed was 200 km/h. The press remained enthusiastic about the fact that it was the most refined sports car ever to exist. As a test report of the time noted, "This is a fast, road-hugging car with good brakes and good visibility."

Coming on the heels of the original SL, it was hardly surprising that the second generation was also able to demonstrate its sporting prowess. In 1963, Eugen Böhringer and Klaus Kaiser won the punishing Spa-Sofia-Liège rally after a four-day non-stop run.

Once again, Mercedes-Benz introduced technical advancements with this generation SL. One sensation was the easy manual operation of the car's soft-top. One magazine referred to it as "the fastest soft-top in the world". Innovative elements were also applied by Mercedes-Benz in the area of the car's safety engineering. The 230 SL was the first sports car in the world to feature a "safety body with rigid passenger compartment and front and rear crumple zones". Mercedes sedans in the upper and medium class had featured this trailblazing invention from Béla Barényi since 1959 and 1961, but the SL marked the arrival of this technology in the world of the sports car.

In 1965, the German news magazine "Der Spiegel" tried to analyze what lay behind the fascination of the SL. In a wide-scale survey, only 4.4 per cent of drivers quoted its exclusivity or its high image value. Many more people were impressed by quite different factors: its high speed, bold styling, sporty character, the delightful possibility it offered of turning an open car quickly and easily into a coupe, its maneuverability, handling, and high quality proved far more attractive.

The 230 SL progressed over the following years. In early 1967 it was replaced by the 250 SL, which featured a sophisticated oil cooler, through which cooling water was circulated. 5196 models of this version were produced. Just eleven months later, still in 1967, it was followed by the 280 SL, which featured a larger bore engine and produced 170 hp at 5750 rpm. Between 1963 and 1971, 48,912 "pagodas" were built and sold. The sports car was a hit in the US and, in the last year of its production, almost 70 percent of 280 SLs went to North America. For the Americans, the Mercedes Roadster had one invaluable advantage over every other European sports car: it came with a first-class power steering system and automatic transmission.

1971 to 1989: the 18-year reign of the third SL

Production of the next generation began in 1971. These took over from the "pagoda", and bore the internal code number R107. This SL series was remarkable for the variety of models it offered. The models ranged from the 280 SL with a straight six-cylinder to the 560 SL with a V8 engine. During the course of production, the third generation SL had eight different engines (not including special versions for other countries). These produced between 177 and 245 hp and had top speeds between 200 and 225 km/h. This marked a decisive step on the part of Mercedes-Benz towards large engines. Eight cylinders and a large displacement have been a big part of the SL concept ever since.

The life span of the R107 SL was unusually long. During its run, America had five Presidents and Germany had three Chancellors. With an uninterrupted production life of 18 years, the R107 was the longest produced passenger car model of the Mercedes-Benz brand and, by 1989, a total of 237,287 of them had been sold.

The charm of the seventies

The question of what role the R107 played in the SL legend is not an easy one to answer. As a two-seater weighing almost 1.6 tons, it didn't appear to be either sporty (S) or light (L). However, the experts praised its dynamic appearance. Race car driver Hans Herrmann noted, "It's powerful, yet not ostentatious. It simply oozes superiority and masculinity."

To the observer, the body of the R107 revealed generous curves and an opulent amount of chrome. The lines of the R107 family had been designed with great care and attention to detail. The trunk lid, for example, repeated the concave curvature of the roof towards the center of the car. This was done in the interests of a harmonious overall appearance. Stylistic adventures were consciously avoided by the designers of the SL. By giving the car such uncomplicated lines they provided it, almost without realizing it, with the basis for its long life.

Indeed, the R107 really did become something of an automotive monument. Its understated charm made it ageless. The doors felt heavy to the touch and shut with a satisfyingly solid "thunk". All the details seemed part of a homogenous whole, engineered for eternity. This was hardly surprising given that the engineers had been aiming to make this open-top car as sturdy as a sedan.

Suspension engineering takes a new route

The engineering was not reminiscent of anything monumental, but was in the true tradition of the SL - very innovative. This was demonstrated even in small, creative ideas. The R107, for example, was the first car to feature the pronounced horizontal ridges on the rear lights. This allowed the lights to remain visible in conditions where dirt would dim other taillights. The car's suspension engineering also followed an unconventional route: at the front, A-frame arms were attached to a sub-frame, while in the rear, a sub-frame with state-of-the-art semi-trailing arms was responsible for wheel control. Models with over 3.5 liters engine capacity were even equipped with a newly designed, sophisticated semi-independent rear suspension system. In this system, the upper arms were linked to the semi-trailing arms by the wheel linkage in order to reduce the stress on the rear axle during acceleration. In Hans Hermann's judgment it was "A fool-proof car, if you don't overdo it too much."

Trendsetter on safety issues

Mercedes-Benz also prepared the new SL for owners whose driving style was too aggressive and/or when the laws of physics were ignored. For them, the SL pioneered a unique safety concept. It featured crumple zones and longitudinal members that, because of their shape and the varying thickness of the steel used, would deform and absorb energy in a pre-defined manner. At the same time, the engine and transmission unit were designed to be forced back and down, therefore minimizing damage to the interior of the vehicle. Although common today, this was a first for safety in the event of a crash.

A sturdy A-pillar with a hollow cross section provided additional safety in the event of a roll-over. Its unusually high rigidity was due to an innovative welding process, which was used instead of conventional spot welding. This was also the first car in which Mercedes-Benz installed the front windscreen using an adhesive bonding process. This was a clever move which ensured further stability. Further innovative details rounded off the cutting edge safety concept. The dashboard was covered with energy-absorbing PVC foam and the knee area made safer with impact-absorbing bolsters. Another new idea was a door handle without a release button. The door is opened by simply pulling the handle. This ensured that it cannot open unintentionally in the event of a collision.

Mercedes-Benz was meticulous in ensuring that further safety details were introduced to the R107 during the course of its production life.

  • Along with other Mercedes models, in 1973 the SL was equipped with standard equipment inertia-reel seat belts and headrests.
  • Anti-lock brakes (ABS) were made available for the first time for the entire SL series in 1980.
  • From early 1982 onwards, a steering-wheel airbag could be ordered as an option for the SL.

Celebrities' darling

Its unmistakable star quality led to the R107 being given a supporting role in the famous TV soap opera "Dallas". In the lives of other celebrities, however, the SL took on the leading automotive role. Amongst them were Uschi Glas, Mario del Monaco, Kurt Edelhagen, Peter Maffei, Heinz Oestergard, Curd Jürgens, Gerd Müller and many more.

The R107 series also achieved success in the world of motor racing. The race cars were SLC coupes rather than SL Roadsters. The SLCs were the early predecessors of today's CL Coupes. The SLC was launched in 1971, and was based on the SL. Between August 17 and September 24, 1978, several SLCs participated in a South American rally called the Vuelta America del Sud. They covered 28,602 kilometers in the process, including 6000 kilometers of special tests. The victorious team was comprised of Andrew Cowan and Colin Malkin in a Mercedes-Benz 450 SLC. In 1979, the SLC also placed second in one of the world's most arduous rallies, the East African Safari Rally. That same year, SLCs completed the Bandama Rally on the Ivory Coast with an impeccable four-car victory - a success that was repeated with a double victory in 1980.

1989 to 2001: styling and engineering reach new heights

In spite of the successful renaissance of the SL idea, work had already begun on its successor in the early nineteen-eighties. A briefing paper stated "Independent, sporty design, compact external dimensions combined with improved interior spaciousness, comfortable ride and interior, to be achieved by emphasizing the driving experience."

The next generation finally celebrated its premiere at the International Motor Show in Geneva in 1989. The new SL, whose internal code was the R129, was introduced as a legitimate heir of the SL name. Its exterior was the object of considerable enthusiasm. In the opinion of many experts, it was closer to the 300 SL of 1954 than either of its predecessors had been. The ex-Formula 1 World Champion, Juan Manuel Fangio, expressed his feelings back then as follows: "For me, the new Mercedes-Benz SL combines, at the very highest level, the characteristics of a sports car with the qualities of a comfortable roadster and, as such, is a remarkable demonstration of the current state of automotive engineering."

The SL of the nineties was perhaps not flamboyant, but was instead something of a timeless automotive sculpture that exuded serenity and yet excitement at the same time. Its pronounced wedge shape was evidence of both taste and style - and of the "strong symbolism" which Bruno Sacco had aimed to achieve. "A new car should not just look new, but also be noticeably new. And people will only recognize innovative engineering if it is combined with a similarly innovative appearance."

Particularly characteristic of the powerful look of the car, is the line from the headlamp along the fender to the top of the A-pillar. Even apparently insignificant details show top engineering quality. The soft-top, which is at its widest at the imaginary B-pillar position, still manages to merge into the narrowing body lines. This was achieved by Mercedes-Benz with a particularly clever ruse: as the roof opens, the mechanism pushes the soft-top out by about 25 millimeters to each side.

Thanks to its sophisticated mechanism, the soft-top can be opened or closed while waiting at traffic lights, allowing drivers to take advantage of every single ray of sun. And the draft stop, specially designed and developed for the SL, ensures that open-top driving remains draft-free and yet convincingly genuine. This feature has since been frequently copied by other manufacturers.

Technical sensations ensure high levels of safety

The SL didn't just offer the enjoyment of open-air driving - it also raised the level of occupant protection and comfort of a roadster to that of a Mercedes sedan. The standard safety package of the SL included a sensor-controlled roll-over bar that would trigger automatically by spring power and hydraulics within 0.3 seconds in the event of a crash or an extreme driving situation. Also, the A-pillar hides a reinforcing tube, which provides a practical enhancement to the protective effect of the unique automatic roll-over bar.

The SL of 1989 was the first standard production car to be equipped with integral seats with integrated inertia-reel seat belts, designed especially for this vehicle. The dimensions of the seat frame allow it to absorb energy in the event of a lateral impact, in which case the broad cast aluminum frame member between the door sill and the seat cushion will deform. 20 patents have been issued for very specific elements within this integral seat.

The power of twelve cylinders

A twelve-cylinder engine with six liters of displacement and 394 hp, effortlessly took the SL to 250 km/h. This marked the peak with regard to the engines for standard production models. The R129 had initially included straight six-cylinder and V8 engines. Beginning in 1998 the straight six was replaced with a cutting-edge, high-performance vee six. The new vee sixes were a marked improvement in both fuel consumption and emissions figures. Superior handling was also ensured by a newly developed independent multi-link suspension. This new suspension provided significant improvements in straight-running and stability.

From 1989 until July 2001 more than 180,000 "R129" models were produced.

2001 and beyond: a stylish synthesis of tradition and innovation

With its sleek styling and advanced engineering, the sports car unveiled by Mercedes-Benz in autumn 2001 continued the long tradition of the SL Roadsters. With this latest incarnation, the SL began its fifth generation.

Along with the innovative vario-roof, which transforms it from an open-top roadster into a weather-proof coupe (or vice versa) in a matter of moments, the new SL-Class also features the electrohydraulic Sensotronic Brake Control system (SBC™), a world first for Mercedes-Benz which works in tandem with the proven Electronic Stability Program ESP® and the Active Body Control (ABC). High standards of occupant protection are ensured by high-strength body construction, two-stage driver and passenger airbags, innovative head/thorax bags in the doors, newly developed integral seats, high-performance belt tensioners, belt force limiters and the sensor-controlled roll-over bars. The SL-Class offers a complete package of state-of-the-art electronic control systems.

While the styling of this Mercedes sports car mirrors its advanced technology, it also stresses appeal, driving enjoyment, and the fascination of top-down motoring. Discreetly but effectively, in a nod to SL tradition, the designers have also incorporated cues from the very first SL of 1954. Typical SL features have stylishly woven together new elements from the Mercedes design language of today, which offer perspectives on the future of the Roadster. These include twin headlamps with a particularly dynamic new treatment, whose state-of-the-art clear-lens design creates an enhanced and distinctive appearance.

High-tech engines with six, eight and twelve cylinders

A dynamic sports car experience is provided not only by the innovative vehicle dynamics systems but also by the powerful six, eight and twelve-cylinder engines, whose outputs range from 245 hp to 500 hp.

Heading the line-up is a newly developed twelve-cylinder unit which combines performance with refinement. Equipped with twin turbochargers, air-to-water intercoolers, three-valve cylinder heads, alternating-current twin-spark ignition and other high-tech innovations, this is one of the most advanced passenger car engines in the world. With the 500 hp V12, it is also one of the most powerful in its class. Peak torque of 800 Newton meters comes on stream at 1800 rpm and remains constant through to 3600 rpm, providing effortless performance in any situation. The SL 600 accelerates from 0 to 100 km/h in just 4.7 seconds, with 60 to 120 km/h arriving a scant 4.9 seconds later. Top speed is electronically limited to 250 km/h.

The impressive performance of the twelve-cylinder model is combined with superb refinement and extremely low noise. This has resulted in ultra-civilized motoring enjoyment. The extensive standard equipment list of the SL-Class meets the aspirations of drivers who demand not only impeccable engineering but also high standards of comfort and exclusiveness. Automatic climate control, xenon headlamps (bi-xenon for the SL600), leather-upholstered integral seats, multifunction steering wheel, modern hi-fi, power seats with memory, and many other luxury features are equipped as standard on the eight and twelve-cylinder models. Optionally, a wide range of innovative assistance systems can be supplied, like DISTRONIC proximity control, the TELEAID automatic emergency call system, the COMAND control and display system (standard on the SL 600), and the electronic tire pressure monitoring system.

Based on the past, the future is bright for future generations of the SL.

Worldwide Model Chronology of the Mercedes-Benz SL Roadsters

Period Internal Code Models and Engines Numbers Produced
1957 - 1963 W198 300 SL (1957- 1963): in-line six, 215 hp 1,858
1963 - 1971 W113 230 SL (1963- 1967): in-line six, 150 hp
250 SL (1966- 1968): in-line six, 150 hp
280 SL (1968- 1971): in-line six, 170 hp
48,912
1971 - 1989 R107 280 SL (1974- 1985): in-line six, 185 hp
300 SL (1985- 1989): in-line six, 180 hp
350 SL (1971- 1980): V8, 200 hp
380 SL (1980- 1985): V8, 218 hp
420 SL (1985- 1989): V8, 204 hp
450 SL (1971- 1980): V8, 225 hp
500 SL (1980- 1989): V8, 240 hp
560 SL (1985- 1989): V8, 227 hp
237,287
1989 - 2001 R129 SL 280 (1993- 1998): in-line six, 193 hp
SL 280 (1998- 2001): V6, 204 hp
300 SL (1989- 1993): in-line six, 190 hp
300 SL-24 (1989- 1993): in-line six, 231 hp
SL 320 (1993- 1998): in-line six, 231 hp
SL 320 (1998- 2001): V6, 224 hp
500 SL (1989- 1998): V8, 326 hp
SL 500 (1998- 2001): V8, 306 hp
600 SL (1992- 2001): V12, 394 hp
180,200
From 2001 R230 SL 500 (from 2001): V8, 306 hp
SL 600 (from 2003): V12, 500 hp
SL 350 (from 2002): V6, 245 hp
SL 550: V8 382 HP
SL 55 AMG: Supercharged V8 510 HP
SL 65 AMG: V12 738 HP
69,900*


 

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