3

SL road car heritage

In the vintage years, enthusiasts were able to buy touring car versions of the Mercedes-Benz racers – the SSK was as awesome on the highways and byways as it was on the track, and no-one will ever forget the lightened SSKL version built strictly for competition use. Now, shaking off the ill-effects of war once and for all, Daimler-Benz was able to modernize its passenger car range, and once again offer connoisseurs of motoring what was essentially a race car for the road ...

The summer of 1953 marked the arrival of the slab-sided ‘Ponton’ series, giving the styling cue for a whole new generation of Mercedes-Benz models. It was launched in 1.8-litre four-cylinder guise (W120), although a 2.2-litre six-cylinder version (W180) had joined the line-up by the following spring.

The first all-new post-war Mercedes-Benz was the Type 180 (W120), often referred to as the ‘Ponton’ model. This had a unit-construction body (adopted for the first time by the marque), and modern styling that would influence the passenger car line for many years after its public debut in September 1953.

Meanwhile, the announcement of two new sports cars at the 1954 International Motor Sports Show in New York had enthusiasts in raptures: the three-litre, fuel-injected 300SL, with styling inspired by the 1953 SL prototype, and the much simpler, smaller-engined 190SL. Although it would be some time before either SL made it into the showrooms (the second Type W198 300SL, for instance, wasn’t built until six weeks after the New York exhibition had ended, and even that was still a pre-production prototype), it was no coincidence that they were announced just as the latest W196 F1 car was about to hit the Grand Prix scene.

With the 190SL an unexpected bonus in New York, it’s not surprising that the 300SL was the first to appear in dealerships, with series production of the Type W198 model having started in August 1954. As it happens, Fritz Nallinger, the firm’s Technical Director, was bitterly opposed to the idea of a road car, but when Max Hoffman in the States placed an advance order for 500 units to kick-start the project, commercial concerns took precedence, and its birth was almost guaranteed. In many ways, it was a repeat of 1900, with a thinly disguised sports-racer acting as a technological showcase for the German brand.

Mercedes-Benz designations

For many years, Mercedes-Benz models have been identified by a vehicle class letter (or series of letters) and a number, which usually relates to an engine size. It’s a system that has continued to this day, with C 350 being a C-Class saloon with a 3.5-litre power-unit, although the engine displacements don’t always tie-up precisely in the way they used to.

The designation that interests us the most at this stage in the story, however, is 300SL. The ‘300’ denotes a three-litre powerplant, while ‘SL’ is short for Sport and Licht – in English, this would translate into a description of a lightweight sports (LWS) model.

For reference, the addition of an ‘R’ suffix (to make SLR) distinguished a pure racing model from the later production road cars, while a ‘C’ (to make SLC) denotes a coupé version of the SL. One will also come across a ‘K’ quite often in Mercedes circles, which used to refer to short chassis models pre-war (as in Kurz), but nowadays is taken to mean Kompressor, the German for supercharger.

The type W198 300SL

The regular 300 series had been styled by the master, Hermann Ahrens, who had previously conceived the classic lines of the 500 and 540K Roadsters, but the thoroughly modern lines of the SL were the work of Walter Häcker and his team.

Compared with the 1952 racers, the W198 had crisper styling, with a new grille incorporating a large three-pointed star on the lower front-end, parallel power bulges in the bonnet to clear the engine, and headlights that sat more upright than before. The heavy bumpers were classed as a necessity for a road car, and the air vents on the trailing edge of the front wings had been introduced on the 1953 prototype (built on chassis number 11) to reduce aerodynamic drag and allow better cooling of the engine bay.

The 300SL (nearest the camera) and 190SL making their debut appearance at the third International Motor Sports Show in New York, an event which opened on 6 February 1954. Although not quite production specification, they were nonetheless very close to the final design.

With the distinctive ‘gullwing’ doors open, one is afforded a glimpse of the cockpit of the 1954 300SL show car.

The side-exit exhaust, introduced midway through the 1952 racing season and carried over to the 1953 model, was not suitable for road use, so a normal silencer arrangement was used with a pipe poking out of the tail on the nearside, and the fussy-looking rear vents were deleted, whilst many of the other details, such as the wheelarch blisters and chrome trim on the sills, were purely cosmetic – items added in a bid to make the car more appealing visually.

Interestingly, although a spaceframe was still employed (very similar to that of the racer, with the same 2400mm/94.5in wheelbase, albeit with a certain amount of additional bracing), most of the body panels were steel for the production models, with only the front and rear lids and door skins crafted in aluminium. On saying that, a handful of all-alloy cars were built for competition work (a total of 58), and there was even a single glassfibre prototype.

Compared to the New York show car, the production ‘gullwing’ model had different door handles and side windows, along with numerous detail changes to the interior. The W198 300SL was built at a rate of around 25 cars per month initially, moving up to 50 soon after.

British advertising from November 1954 for the 300SL model.

A 300SL pictured in a Hollywood showroom in the USA in 1955.

The dry-sump straight-six power-unit (Type M198) was a leading edge piece of technology, and, although already proved on the 1953 prototype, the 300SL became the first series-production road car to sport fuel-injection.

With experience relating to fuel-injection gained during the war via aero-engine development and knowledgeable engineers like Hans Scherenberg (then in charge of the central design office) assigned to the M198 project, the Bosch system was quickly releasing copious amounts of reliable power and torque, and any lingering thoughts about moving over to Weber carburettors were duly dismissed.

The configuration of the injection system was very clever, with the injector nozzles placed in the original sparkplug holes in the upper part of the six-cylinder block (a throwback to the days before the plugs were moved to a new head for the SL) to give direct injection. Air, meanwhile, was pulled in through a beautifully crafted plenum chamber and ram pipe casting that became a signature part of the 300SL’s design.

With a standard 8.5:1 compression ratio, the 2996cc (85 x 88mm) unit ultimately developed 200bhp DIN at 5800rpm – a figure higher than that quoted for the original SL racing cars. Specifying the ‘sports camshaft’ released another 15bhp, and cars were often supplied with higher compression ratios as well; a 9.5:1 c/r gave ten more horses.

The 1000th 300SL was built in early December 1955. Incidentally, all ‘gullwing’ coupés were sprayed silver unless the customer specifically requested another colour.

The all-synchromesh four-speed transmission was carried over from the 1952 racer, and likewise, various axle ratios were available, the highest allowing an observed top speed of 154mph (246kph) – remarkable for the time. At this stage, the steering, suspension and braking setup was pretty much carried over, too, albeit with softer springs and dampers than the 1952 racers (those intending to use the car in competition could specify the stiffer setup as an option), and the addition of trailing links at the back. Even the 15-inch wheel and tyre combination was retained rather than taking up the 16-inch rims selected for the 1953 prototype, although a brake servo was added to the specification list for 1954 to make the car more civilized.

With a more comfortable interior, a hinged steering wheel to aid entry and egress, and greater attention paid to heating and ventilation (the grille in the front bulkhead and two slots in the trailing edge of the roof were added for this reason), the 300SL was an ideal road car, albeit much heavier than the vehicle that spawned it, being catalogued at 1260kg (2772lb). At DM 29,000, it was around DM 5000 cheaper than the hand-built 300S line, but still twice the price of a 1.5-litre Porsche Speedster.

The company’s victory in the 1955 Mille Miglia was memorable, and has been recalled in motoring publications literally hundreds of times since, although winning in such a convincing manner has always tended to overshadow the GT Class win by John Fitch’s regular 300SL, which finished the Italian event in fifth; Olivier Gendebien was second in the GT category (seventh overall) in a similar machine.

Fitch later recalled that while Italian exotica had an advantage in top speed, the SL “... was tough, and that’s why it won races.” It also won the hearts of the press and public alike. Jesse Alexander reported in Road & Track: “The 300SL seems to be the perfect example of the modern trend in Continental automobiles, that of producing a fast but extremely comfortable sports touring car with the use of an aesthetically-pleasing, aerodynamic, lightweight body in conjunction with an untemperamental yet efficient engine.”

The venerable John Bolster of Autosport fame concluded his January 1955 road test with the following prose: “The Mercedes-Benz 300SL is a car of beautiful appearance and almost incredible performance. Its construction and finish are of the very highest class, and its whole design represents a technical tour de force. It has perfect traffic manners, and the sheer joy of handling it on the open road has to be experienced to be believed. There are other cars which are kinder to the less experienced driver, but for the man who is competent to exploit its full performance, this is one of the world’s greatest cars.”

Coupé production ended in 1956, with the last few of the breed sold in the following year. 1400 had been built in total, with four out of every five cars ultimately shipped to the States (the 300SL was listed at close to $7000 on arrival in the US, although prices quickly rose to $8905). Incidentally, in 1994, a ‘gullwing’ 300SL came to light that was bought piece-by-piece by an enthusiast in America some two years after production of the model ended. When Bob Doehler, a Studebaker designer, acquired the final parts in 1961, he was sadly unable to complete the project, and the car sat in a half-finished state until he died in 1993. Would this add another unit onto the production total?

The 300SL was ideally suited to track work and road rallies. This picture was taken during the Swedish Grand Prix weekend in 1955, with Karl Kling leading Wolfgang von Trips. Kling went on to win the race.

Memories of the 1956 Liège-Rome-Liège Rally, which Mercedes won.

GP racing & the 300SLR

Mercedes-Benz made its long-awaited return to Grand Prix racing in 1954 with the 2.5-litre normally-aspirated W196 model, fielded with both streamlined and open-wheeled bodies. Having made their debut at Rheims in July, the straight-eight machines went on to dominate the GP scene in 1954 and 1955 in much the same way as the pre-war Silver Arrows had.

Regulations at the time allowed sports-racers to be developed from GP cars, and Daimler-Benz responded with the 300SLR for use in the 1955 World Sports Car Championship. Being based on the Grand Prix car of the time, the 300SLR (W196S) had nothing in common with the regular 300SL, although the 2.5-litre engine was bored out to give a three-litre capacity, hence the similarity in its designation. The body enclosed the wheels, in much the same way as the streamlined GP cars used on faster circuits.

The 300SLR gave a stunning performance on the Mille Miglia, but at Le Mans, one of the cars was involved in an horrific accident on the pit straight. This prompted the decision for the Mercedes-Benz team to stop racing, although some inside the company say it was largely down to the concerns of Professor Nallinger, who felt that road car development was suffering as a result of all the firm’s top designers and engineers being far too busy in motorsport-related activities. Whatever, it was certainly a sad occasion on 24 October 1955, when Alfred Neubauer dropped covers over his beloved racing cars in full view of the press. He wept openly at the event. Enthusiasts everywhere felt his sorrow ...

Mintex advertising from 1955, featuring the W196R monoposto of Stirling Moss.

Juan-Manuel Fangio about to start the 1955 Mille Miglia in a 300SLR.

The type W121 190SL

Series production of the 190SL convertible started in May 1955, about six months behind schedule. This was rather ironic, given that the 190SL was always going to provide Daimler-Benz with better volume sales in the States than the 300SL, so one would have thought it would have been more prudent to get the cheaper machine out first. However, people had an image of the ‘gullwing’ body whenever the SL moniker was mooted, hence the model release order, and the smaller-engined car could then ride on its fame using the same Sport Licht badge.

While it’s fair to say the 300SL was built using many production parts sourced from the regular road car line, the ratio was much higher in the 190SL. Even the chassis was based on a shortened Type 180 pressed-steel floorpan rather than a dedicated tubular spaceframe, whilst most of the running gear and chassis components were simply lifted straight out of the Type 180 parts bins. This reduced cost and development time, with advantages far outweighing the disadvantages for the manufacturer.

Cover of the 190SL catalogue. The smaller-engined SL was priced at DM 16,500 in Germany.

An early 190SL on the filmset of High Society, the smaller rear lights indicating that the car was made before June 1956. Whilst always fitted to US cars, rear bumper guards had become standard for all markets in July 1957, when they were modified to carry the number plate lights.

Styled under the watchful gaze of Walter Häcker, the final prototype was exhibited at the Geneva Show in the spring of 1955. Compared with the 1954 show car, the bonnet, bumpers and lights were revised, and the grille and rear wings brought more into line with the 300SL, although the ‘Ponton’ styling influence was still very much in evidence on the latter.

A hardtop was available from the off, giving the buyer the choice of a convertible roadster (with soft-top only), or a car with a hardtop, supplied with or without a hood. Interestingly, the hardtop model was called a coupé in official paperwork, and came with additional chrome trim on the sills and wheelarch blisters. Early hardtops were crafted from aluminium, but were made from pressed steel from the spring of 1956.

The 190SL may not have been quite as glamorous as the 300SL, but it was an accomplished sporting tourer that was infinitely more affordable to buy and run. The North American market was by far the most important outlet for European sports cars, of course, with the 190SL introduced to US buyers at a reasonable $3998.

Engine bay of the 190SL.

A press photograph of a 190SL with hardtop dated June 1958. The later-style hardtop introduced in October 1959 gave far better rearward visibility. The only significant change applied to the 190SL that helped with identification after that was to the bootlid lock, which was separated from the lid lift in 1960.

The body itself was largely all-steel on the 190SL, although the front and rear lids and door skins were aluminium. Even lighter doors were announced in the New York press material and appeared in several catalogues thereafter. These, along with the fitment of a lightweight aero-screen and removal of the bumpers helped reduce weight for those wishing to go racing at weekends.

On a more practical note, while the 300SL had next to nothing in the way of trunk space due to its oversized fuel tank, with a parcel shelf behind the seats providing the main luggage area, the 190SL had a good-sized boot. Fitted luggage was available from the maker for both cars. In addition, a third transverse jump-seat was listed for the 190SL, fitting in behind the two front ones, or a bench-style front seat was another option.

The engine was a high output 1897cc sohc four, with the same bore as the 300SL, but a shorter 83.6mm stroke. This bore/stroke combination was quite different to that of the original Type 180, adding 130cc to the cubic capacity, which had started out at 1767cc for the sedans, but it was duly adopted for the 1956 190 series, as well as the Type 180a of 1957 vintage. In the 190SL, a pair of twin-choke Solex carburettors and an 8.5:1 compression ratio gave 105bhp DIN at 5700rpm, with power taken to the rear wheels through a four-speed manual transmission.

Using the Type 180 floorpan allowed the Daimler-Benz engineers to employ the sedan’s front subframe arrangement for the SL, with the engine, gearbox and front suspension system carried on an independent pressed-steel cradle that was then attached to the body via rubber mounts to isolate NVH – an incredibly advanced feature for the time. The concept was further refined in January 1956 thanks to an improvement in the way the engine was mounted in the subframe.

The suspension itself was quite conventional, with fabricated upper and lower arms at the front, coil springs around damper units, and an anti-roll bar. The back end featured a low-pivot swing axle with the addition of revised, fairly hefty trailing links to give superior roadholding, the handling situation being further helped by the adoption of 13-inch wheels and tyres, which, although of unusually small diameter for the day, had the effect of reducing the roll centre height.

Braking was via drums all-round, but with the drums themselves made from cast-iron rather than the expensive Al-Fin bimetal (ribbed alloy sleeves over cast drums) items used on the three-litre car. They were still finned, at least, for enhanced heat dissipation, while a servo was initially offered as an option before becoming standard shortly after production began. Steering, meanwhile, was via the familiar recirculating-ball system for so long championed by the men in Stuttgart; lhd or rhd was available, unlike the 300SL coupé, which was officially sold with left-hand drive only.

The 190SL was subjected to a number of detail changes over the years. By far the most important were carried out in time for the 1960 Model Year, when the engine’s compression ratio was upped to 8.8:1 to maintain power output at 105bhp (120bhp SAE), and a new hardtop was introduced to give better visibility. A total of 25,881 190SLs had been built by the time production ended in February 1963.

Bringing together the Silver Arrows

Bitter rivals in pre-war racing, it is ironic that Daimler-Benz acquired a majority interest in Auto Union in 1958. Auto Union had brought together Horch, Wanderer, Audi and DKW in 1932 – four car companies with expertise in quite different market sectors. With the end of the war, most of the Auto Union factories were placed in what became known as East Germany, so a new company was established in Ingolstadt not long after hostilities ceased. Initially, only the DKW brand rose from the ashes, however.

Complete control of Auto Union was secured in December 1959, when Daimler-Benz was also showing an interest in owning a chunk of BMW. The latter deal fell through, but the Stuttgart firm nurtured the revived Auto Union name before selling the business to Volkswagen in 1964. VW duly brought back the Audi name once it took control of its new subsidiary, later merging it with NSU, which held the rights to the Wankel rotary engine – a power-unit that set the motoring world alight, with Daimler-Benz also falling for its appeal.

Today, Auto Union is ably represented by Audi AG, its cars carrying the same four rings on their noses as the pre-war racers designed by Professor Ferdinand Porsche. Audi is still owned by the Volkswagen group, which is in merger talks with Porsche. It’s a small world in the German car industry!

The second generation 300SL models

The 300SL had been a magnificent ambassador for the Mercedes-Benz marque, especially in America. Granted, the 190SL brought greater success in the showrooms, but the glamour associated with the ‘gullwing’ model was an advertising agent’s dream. It was expensive to build, however, and the two SL lines were hardly close in concept. The new 300SL (Type W198 II), first shown at the 1957 Geneva Salon, would take most of the three-litre car’s attributes and package them in a roadster body, thus bridging the gap for the marketing men to go to work on a campaign that gave meaning to the SL badge – at the request of Max Hoffman in the States, the Sport Licht moniker would from now on forever be associated with open sports cars.

Fascinating picture of the lightweight roadster body being carried to the production line. The untrimmed shell tipped the scales at 185kg (407lb).

Contemporary colour shot of an early Type W198 II model.

Full-scale production began in May 1957. The biggest difference was found in the bodywork, with the ‘gullwing’ arrangement giving way to an open structure with regular doors and frameless wind-up windows. This, of course, led to significant changes in the centre section of the spaceframe, which was further modified to allow a slightly longer tail (combined with a smaller fuel tank, this freed up more trunk space) and a fractionally wider track.

Although very similar to its predecessor in most other respects, careful observation revealed some beautiful detailing on the new car, with fabulous Lichteinheit front lights (bringing headlights, foglights and indicators into a single unit, although US-spec lights were different by necessity), longer chrome flashes in the side vents, and sharper swage lines in the rear wings.

In addition, while the 190SL soft-top required a regular tonneau cover, the 300SL hood dropped into an area behind the seats, being covered by a hinged metal panel when not in use – a very clever piece of design, and something carried over to future SL generations. Introduced at DM 32,500, the roadster was given the option of a removable hardtop in the summer of 1958.

Mechanically, the biggest change was applied to the rear axle, with a new low-pivot swing axle design that incorporated a novel, central compensating spring. The steering was slower than that of the ‘gullwing’ model, though still faster than that on the 190SL, and while drums were still fitted, the latest three-litre car gained servo-assisted discs from March 1961; the 220SE was the first Mercedes-Benz with disc brakes, although they were sourced from Girling and fitted on the front axle only in this case – the SL used a Dunlop setup on all four wheels.

Also, due to the extra chassis bracing required with an open car, plus the luxurious appointments of the interior, the new 300SL was significantly heavier than the closed coupé, so a high-lift sports camshaft was fitted as standard to enhance power output (the sohc six developed 215bhp at 6100rpm). In March 1962, the SL was given an alloy block to save weight, although cast cylinder liners were employed to prolong engine life.

Production shot from 1958, with a 300SL roadster being tended to on the line. Note the modified spaceframe chassis.

British advertising from March 1959.

This elegant roadster with optional hardtop was featured in a catalogue released in late 1959, although this particular shot was taken the previous year.

In the meantime, two lightweight roadsters were produced by the works for use in the American SCCA series. These so-called 300SLS models were completed in the spring of 1957, handing Mercedes stalwart Paul O’Shea the SCCA Class D championship by a country mile.

In the spring of 1959, Autosport noted: “On the whole, driving this superb machine was an exhilarating experience. Only a race-bred machine could behave like the 300SL, and although there may be a few faster cars, it would be difficult to imagine anything else which could compete as regards sheer perfection of engineering and a remarkably high standard of finish.”

Like the ‘gullwing’ model, though, this second 300SL was also destined to be a rarity, with only 1858 units built by the time production ended in 1963. Historically significant in so many ways, these were to be the last Daimler-Benz passenger cars to feature a separate chassis.

The ‘Pagoda’ roof series

The last of the 300SL and 190SL models were built in February 1963. However, the 300SLs were little more than exotic, small volume masterpieces. It was the 190SL that had sold in worthwhile numbers, and the next generation Sport Licht model (first presented in March 1963 at the Geneva Show) was basically a replacement for the four-cylinder car – a mainstream vehicle using off the shelf components, blending a strong sporting image with everyday practicality – but with the added bonus of a fuel-injected six to endow the new car with a technological spirit inherited from the 300s.

As Road & Track pointed out at the time of the W113 series’ debut: “The 230SL is a median between the 300SL and 190SL in almost all respects. The 170bhp injection engine of the 230SL offers performance between that of the 120bhp 190SL engine and the 250bhp 300SL powerplant. As a ‘sports touring car,’ it has good roadability with sedan smoothness. The interior is smart rather than luxurious, reflecting the functionalism associated with sports cars, although it is not quite as austere as that of true competition cars.”

In effect, Daimler-Benz brought the two extremes of SL motoring together in one reasonably priced machine, ideal for road use, but less suited to serious competition duty – at least on the track, for the 230SL would later prove itself to be a fine rally car. The distinctive removable hardtop – the famous ‘Pagoda’ roof – gave three body configurations (open, closed via the soft-top hood, or as a comfortable coupé with the hardtop in place), while the option of a manual or automatic transmission broadened its appeal still further, especially in the United States.

An advanced styling prototype for the W113 series SL. Note the 220SL badge on the tail and the conventional profile of the hardtop. The signature ‘Pagoda’ hardtop that followed on production models was ultimately designed in such a way as to give maximum strength and increased glass area, while the signature concave dip in the centre section gave the car a lighter, more compact appearance, without detracting from the original intention of enhancing visibility through larger glass sizes.

German advertising for the 230SL, introduced at DM 20,600 in basic guise, which translated to around $6700 in the States. Pilot production had begun in March 1963, with full-scale production starting four months later, in July. The fuel-injected 2.3-litre sohc six under the bonnet was the first Daimler-Benz engine to use an alternator instead of a dynamo for charging the electrical system.

The 230SL

Initial work on the Type W113 SL began in October 1958 under Fritz Nallinger, although Hans Scherenberg took over the reins as Technical Director not long after the new car was launched. In the meantime, the body design – executed by the talented Frenchman, Paul Bracq, whilst under the supervision of the new chief stylist, Friedrich Geiger – had gone through countless minor changes, not just to become more contemporary (early sketches leaned heavily toward 190SL and 300SL styling cues) and aesthetically pleasing, but also to incorporate the necessary engineering hard points prescribed by Rudy Uhlenhaut and Karl Wilfert, as well as Bela Barenyi’s various safety innovations.

Whereas the 190SL had borrowed the 180 sedan’s platform and technology, the 230SL was based on a shortened floorpan from the ‘Fintail’ 220SEb (introduced in the summer of 1959), the body being very much in keeping with the Mercedes-Benz ‘family’ styling of the time. Indeed, followers of Mercedes-Benz lore would be able to quite easily spot the likeness between the W113 and the larger W111/3 220SEb Coupé of 1960 vintage. One thing obvious to all, however, was how strikingly modern this new SL was compared to its predecessors.

The 230SL proved to be a useful rally car. This picture shows the winner of the 1963 Spa-Sofia-Liège Rally, handled by Eugen Böhringer and Klaus Kaiser.

Publicity shot of the 230SL taken in Paris. Despite weight-saving techniques, such as the use of aluminium doors and lids, the 230SL still tipped the scales at a hefty 1295kg (2850lb).

The frontal styling was perhaps the strongest sign of SL DNA, clearly paying homage to the last of the 300SLs. From the grille and lights back, though, a straight-line approach was much in evidence, with the W113 series character lines as sharp as those of the earlier SLs were rounded. The profile was vaguely similar to that of the 220SEb Coupé, and even the C-post on the SL’s removable hardtop was narrower at the bottom than the top, aping that of its bigger brother. The tail also followed 220SEb Coupé design practice, with a familiar bumper and bootlid style, the same small fins formed by the tops of the rear wings, and the resemblance in the rear lights and chromework surrounding them.

It’s fair to say the 230SL was fairly conservative from a styling point of view, but the lack of ornamentation gave the new car a very clean and functional look. In addition, a by-product of using the W111 floorpan dictated a wider track, and, after being shortened to 2400mm (94.5in), the 230SL looked far more purposeful than the 190SL it replaced. In combination with reduced overhangs and bigger wheels and tyres filling out the arches, the new car also managed to look lighter and more nimble than its predecessor at the same time.

Just as the 190SL had used a special version of the 180 saloon’s engine, the W113 SL also borrowed its motive power from the contemporary sedan family. There were thoughts of a 220SL at first, but a more powerful lump was created solely for the two-seater. It’s strange, but the SL’s engine was actually an evolution of the final six-cylinder ‘Ponton’ unit (127.980) rather than a W111 series engine, as it carried the M127 II designation, whereas the six used in the ‘Fintail’ SE was the M127 III (127.982). Only the 127.981 had a 2.3-litre capacity, though, achieved by increasing the bore from 80mm to 82mm, whilst retaining the 72.8mm stroke. This gave a displacement of 2306cc, instead of the 2195cc listed against the 220SE models.

The 127.981 had an alloy head that played host to bigger valves and a hotter camshaft, and while the main block was cast-iron, the lower section of the crankcase was also made of aluminium alloy to reduce weight. With a revised Bosch port injection system with a six-plunger pump, modified exhaust manifold, plus a hike in the c/r (taking it up to 9.3:1), the 2.3-litre unit developed a healthy 150bhp DIN – an increase of 35bhp on the 127.980, or 30bhp on the 127.982.

A four-speed manual transmission was the norm, although, for the first time on an SL, a Daimler-Benz four-speed automatic was available as an option, sporting the now-famous staggered selector gate to reduce the chances of unwanted changes. Interestingly, throughout the W113 era, its layout was the opposite of today’s quadrant, with ‘Park’ at the bottom of the gate.

The suspension was taken directly from the 220SEb. It was actually quite similar to that of the 190SL up front, albeit with detail improvements. The rear, too, was also fairly familiar, although a transverse compensator spring (as used on the later 300SLs) was added aft of the differential, allowing engineers to adopt softer road springs combined with firmer damping for enhanced comfort and anti-roll characteristics.

The extra width of the 220SEb platform allowed a wider track to take full advantage of radial tyre technology, which was still pretty much in its infancy compared to the development time that had gone into crossplies (still employed on the saloons). The ride/handling compromise was perfected by Rudy Uhlenhaut, with the latest low-pivot swing axle ideally suited to the higher cornering power of radial rubber. Both Firestone and Continental (who made a new tyre called the Halbgurtel) were approached to produce a suitable tyre for the SL, with improved driver feedback and sidewall protection. Ultimately, the 185 HR14 tyres, which were quite fat for the day, rode on 5.5J steel rims, at least until July 1964, when a 6J rim was adopted.

The servo-assisted braking system was familiar to W111 series drivers, as well, with 253mm (10.0in) diameter discs up front, and slightly smaller drums on the back. However, the SL did benefit from split circuits for added safety. The recirculating ball steering was another carry-over, with a well-weighted PAS system offered as an option.

The interior was upgraded for superior comfort, with the unusual secondary instrument layout following W111 saloon practice, while the multi-function stalk was a very modern feature. A third transverse seat was available for the back, as per the 190SL.

Dozens of minor changes were applied to the 230SL in a programme of constant development, but the most important ones included fitment of a larger fuel tank (up from 65 litres/14.3 imperial gallons to 82 litres/18.1 gallons) from November 1965, and a change in gearing and final-drive options at about the same time. Then, from May 1966, a ZF five-speed manual transmission became available as an option, with better gear spacing and an overdriven top, but delivery took time, and at DM 1200, it was quite expensive, too, being only DM 200 cheaper than an automatic gearbox. As a result, 5MT cars were something of a rarity.

The last 230SL was built in January 1967. Pilot production of the 250SL started in November 1966, with full-scale production beginning in the following month. As such, the 230 and 250 run overlapped for a short time before the 250SL made its official debut at the Geneva Show.

The 250SL

The 1967 Geneva Show opened on 9th March, providing an ideal public launch location for the 250SL. In reality, there was little to differentiate between the 2.3- and 2.5-litre cars, as many of the running changes applied to the 230SL were carried over. It was under the bonnet, therefore, where one had to look for the biggest difference.

Surprisingly, given the overall quality of the engineering, down to the finest detail, the M127 engine had only four main bearings. This situation was changed with the introduction of the 250SL, its M129.982 six-cylinder unit – taken virtually straight from the 1967 Model Year W108 250SE saloons – having a seven-bearing bottom-end for greater refinement.

As far as the other leading features were concerned, compared with the 230SL engine, the 82mm bore was retained, but a longer, 78.8mm stroke increased the cubic capacity to 2496cc. With a revised head carrying new valves and ports, plus a hike in the compression ratio (up to 9.5:1), power output was officially the same, but torque output was improved by a worthwhile 10 per cent.

A taller final-drive was adopted on manual cars, although the three transmission options continued. The other big mechanical change was in the uprated braking system, with discs now fitted all-round. As per Porsche practice, and that of some other European sports car makers that found it difficult to produce an efficient parking brake, the rear discs had integrated drums for the handbrake only, giving the ultimate compromise between high-speed stopping power and holding ability once the car had come to a halt.

With the 250SL came an interesting variant known as the California Roadster. In this format, the hood and its metal cover were deleted to make way for a bench rear seat that could accommodate children on shorter journeys. Alternatively, once folded, it provided a useful luggage shelf. The hood could not be retro-fitted, so the arrangement was recommended only for those living in areas with little rainfall, such as the US State that lent its name to the model.

Most of the 250SL press cars had early dashboards and door furniture, although July 1967 saw a minor change in preparation for the 1968 Federal regulations. Much of the switchgear and door trim was modified to make it friendlier to those coming into contact with it in an accident situation, three-point seatbelt mounts were introduced, a new energy-absorbing steering column was fitted (readily identified by the revised centre boss and horn ring on the wheel), foam padding was added to the windscreen frame, and the handles that secured the tops to the header rails became removable. In addition, American spec cars could be readily identified by their side repeater indicators, attached to the front and rear wings of US-bound cars for the 1968 season.

The 250SL was to be short-lived, however, the last being manufactured in January 1968, which is when 280SL production officially began (two months after an initial pilot run). The 250SL is therefore a rare model, with only 5196 built.

About the only way to distinguish a 250SL from its 2.3-litre brethren from the outside was via the badge on the tail. The soft-top dropped underneath a panel like that found on the 300SL roadsters on all W113 variants.

The 280SL

Just as the 250SE was replaced by the 280SE in the W108 line-up at the beginning of 1968, the 250SL was upgraded to the 280SL at the same time. The M130 engine was given a hotter camshaft, though, endowing the SL version with 10bhp more, 250rpm further up the rev-range. With 170bhp DIN on tap, the 2778cc engine (86.5 x 78.8mm) was 20bhp more powerful than its predecessors, and torque increased to 177lbft.

As before, 4MT, 5MT and 4AT gearboxes were offered, and there was very little change to the chassis components. More rubber bushes extended service intervals, and the tyre construction was changed (although the actual size remained the same), but otherwise there was little to report.

Apart from looking at the badge on the tail, the quickest way to identify a 280SL is by its wheel trim, which became a one-piece cover rather than a separate outer ring and nave plate that had allowed the body-coloured wheel to show through. Alloy wheels (6J x 14) were available as a dealer option from 1969, although they were ultimately offered as a factory-fitted option from August 1970.

By this time, of course, American regulations were becoming more and more demanding, especially in the fields of safety and emissions. While most of the interior and exterior changes have been documented in the 250SL section, in the name of promoting cleaner exhaust gases, 2.8-litre Federal engines sported a modified fuel-injection system, a tamer camshaft to give different valve timing, a fuel shut-off valve that kicked in when the driver backed off the throttle under low-speed deceleration, and a viscous-coupled, thermostatically-controlled cooling fan. The end result was an 8 per cent drop in power, but complying with the rules was the only way to get cars into the States – the world’s biggest market for European sporting machinery. To make up for this, early cars were given a shorter rear axle ratio, although they’d fallen back into line with domestic models by the end of 1969.

The last 280SL was built in March 1971, bringing the ‘Pagoda’ roof generation to an end. Including the 23,885 280SLs produced, the total W113 run came to 48,912 units. The next generation was even more successful ...

The 280SL, readily identified by its new wheelcovers. Other than the badging and wheel trims, though, there was little difference between the 2.3-, 2.5- and 2.8-litre cars from the outside. Note the ‘clap hands’ wipers – a signature piece of W113 design, as they were unique to this SL generation.

With ever-more stringent crash regulations, time was running out for the W113 series, despite the 280SL’s popularity in the showrooms. In reality, the styling had also become dated when viewed alongside cars like the Mercedes C111.

A new direction

The W113 series had been in the showrooms for eight years, and was as popular as ever. However, the times had changed politically, and demands for cleaner and safer cars – not to mention calls for cheaper and easier repairs from insurance companies – meant that the ‘Pagoda’ roof models had reached the limit of their development. Some were shocked by the sheer size of their replacement, with some even stating it was a mockery of the Sport Licht moniker, but the 107 series would go on to be the longest-running model line in Daimler-Benz history nonetheless ...

Design work on the W113’s replacement – the R107 – began in earnest in 1965. Initial design proposals were radically different to the established SL lines, with flowing curves replaced by a distinctly boxy character.

Ironically, due to uncertainty regarding the long-term future of the open sports car, running parallel with the new concept, a simple facelift programme was kept in place until mid-1968, when attention turned completely toward a full model change situation, with all-new running gear in a brand new body.

German advertising announcing the R107 series. Rather than the usual ‘W’ suffix (for ‘Wagen’), an ‘R’ was chosen for ‘Roadster’, allowing differentiation from the coupé model, which had a C107 code.

The first 107 series models

The R107 roadster took shape under Chief Designer Friedrich Geiger, with all manner of proposals finding their way to his desk before he settled on a Joseph Gallitzendörfer styling sketch as the basis for the final design.

Three full-size styling bucks (labelled Model I, II and III) were reviewed on 18 June 1968, alongside a mildly facelifted W113 model, and the new generation was born after the Board gave the nod to the Model III mock-up, which displayed strikingly modern and bold lines, yet still managed to incorporate enough of the earlier SL DNA to make it recognizable as a continuation of the bloodline.

Things progressed quickly thereafter, and with the powertrain already entering production in the V8 models to be launched at the 1969 Frankfurt Show, there were even thoughts of releasing the new two-seater in the spring of 1970. However, Hans Scherenberg was still jumpy about the constant changes to US regulations, and recommended not only delaying production, but putting a back-up plan into action that gave rise to the long-wheelbase C107 – a close-coupled coupé based on the structure of the open car, known as the SLC.

The 350SL as it was first presented to the press, seen here with the hardtop in place. Note the hardtop profile, which paid homage to earlier SLs.

The mighty V8 engine of the 350SL.

The 350SLC making its debut at the 1971 Paris Salon.

Ultimately, the 107 series models (soft-top as standard with a removable hardtop for the SL roadster, and a fixed-head coupé configuration for the SLC), would provide the basis for a whole new generation of passenger cars, with various styling cues being duly adopted for the W116 S-Class to give a ‘family’ look to the Mercedes range.

Compared to the W113, the R107 was bigger all-round – it was important to think ahead on the safety front, with the increasing importance of the Americans for the German maker, and the extra bulk allowed more engineering options, as well as added comfort for passengers. Indeed, with its completely modernized interior, the SL was destined to move even further away from pure sports than its predecessor, the Grand Touring car being infinitely more appealing to a wider market.

The wheelbase on the new open car was 55mm (2.2in) longer than that of the W113 models, leading to an overall length increase of 95mm (3.7in), and the width was 30mm (1.2in) up. Despite the track being slightly narrower, due to the all-steel construction of the body and more luxury features, there was a weight gain of 200kg (440lb) compared to the 280SL, but computer-aided design made the shell stronger than ever before, to the point where a Targa bar (once thought a necessity to clear Federal regulations) was no longer needed.

Modern fascia of the 107 series models, this being the 350SLC version.

An early R107 model with the hood down, hidden by the metal tonneau cover that was an SL styling signature, and the distinctive ‘Barock’ alloy wheels.

Motive power was provided by the 3.5-litre V8 introduced with the 280SE 3.5 and 300SEL 3.5 models – the M116 unit having a bore and stroke of 92 x 65.8mm to give a cubic capacity of 3499cc. With D-Jetronic fuel-injection and a 9.5:1 c/r, it developed a level 200bhp, along with 211lbft of torque.

However, soon after the launch of the new car, a long-stroke 4520cc version was introduced for the US market. Despite the additional displacement, this M117 engine developed 5bhp DIN less than its European counterpart, which shows how strict Federal regulations on emissions had become by this time.

A four-speed manual gearbox was the norm, with a four-speed automatic as an alternative in most countries until mid-1972, when the 3AT unit with torque convertor used in the States from day one was adopted as the automatic gearbox option.

The suspension and steering was based on W114 practice, with braking provided by discs all-round; there was actually talk of offering ABS on the new SL, but it was not ready in time. As for the footwear, low-profile 205/70 radials were mounted on 6.5J x 14 rims, either made from pressed steel or cast alloy – the latter wheels being of the cookie-cutter ‘Barock’ design offered as an option on the last of the W113s.

The 350SL was launched in April 1971 at a price of DM 29,970 in Germany. Exports began in the middle of the year, allowing the ‘350SL 4.5’ to reach American showrooms in August. The 350SLC, meanwhile, made its debut at the 1971 Paris Salon, with sales starting four months later.

The 4.5-litre cars were added to the ROW line-up in the spring of 1973, by which time they were formally known as the 450SL and 450SLC. From August 1974, the European market also gained a 280SL and 280SLC, powered by a 2746cc M110 straight-six that developed 185bhp DIN.

All engines moved over from D-Jetronic to K-Jetronic fuel-injection in the mid-1970s, reducing horsepower, and lower compression ratios on certain units only served to drop output still further. At least the 2.8-litre engine had its power restored in 1978, but the V8s would not make a comeback – they were left in their weakened state until they were replaced by a new range of eight-cylinder powerplants in 1980.

New engines

The 1977 Frankfurt Show witnessed the debut of the five-litre 450SLC 5.0 prototype, which not only employed a great deal of aluminium body parts, it also had an aluminium alloy cylinder block. This signified the birth of a new line of all-alloy V8s that made their debut in the autumn of 1979, and were duly adopted on the SL and SLC models from March 1980.

While the 2.8-litre six was carried over in the 280SL/SLC (albeit hooked up to a new automatic transmission), the 350SL/SLC became the 380SL/SLC, and the 4.5-litre cars became the 500SL/SLC grade, with the old 450SLC 5.0 falling by the wayside in the process. Only the 3.8-litre machines were sold in the States, with 160bhp DIN under the bonnet (as opposed to 218bhp in Europe), while the 4973cc unit sold in other parts of the world produced a healthy 240bhp, linked to a new 4AT gearbox.

One of the first 280SL press pictures. The 2.8-litre six under the bonnet had almost as much power as a Federal-spec 4.5-litre V8, and was quite different to the earlier 280SL unit, having twin-overhead camshafts. The 280SL was available with 4MT, 5MT and 4AT gearboxes.

American-spec cars had different bumpers and headlights. This is the US version of the 450SLC for the 1977 season.

The 450SLC 5.0 model, which entered production in the spring of 1978, actually made a fine rally car, winning two WRC events. This picture shows Hannu Mikkola and Arne Hertz in action on the 1979 Safari Rally.

The SLC variant was dropped at the end of the 1981 season, replaced by the gorgeous 380SEC and 500SEC coupés. Power dropped slightly on the V8s at the same time, as emissions standards tightened up globally, and more luxury items were fitted as standard as the eighties progressed.

Well over 200,000 107 series cars had been sold by 1985, and even if one takes out the 62,888 SLCs from the figure, no-one could deny the SL was a good seller, especially given its high price. Indeed, even without the SLC’s help, it had only taken to the end of 1976 to outsell the entire W113 run, despite a major fuel crisis and a dreadful world economy.

A final fling

The SL just kept selling, so the management in Stuttgart decided to keep it going with a 1986 Model Year update that would allow it to remain in the Mercedes line-up until 1989, when the all-new R129 SL made its long-awaited debut.

The main changes were in the engine bay, with new 3.0-, 4.2- and 5.0-litre power-units adopted for most markets, along with a 5.6-litre V8 for the USA, Japan and Australia. Even the 2962cc six had 188bhp available, while the 5547cc eight gave 242bhp, thus giving the SL the performance it deserved, even in the States.

Also new was the 4AT with switchable ‘Sport’ and ‘Economy’ shift modes, whilst larger 15-inch alloy wheels covered uprated brakes, suspension settings were changed, and a redesigned rear axle was employed, simultaneously improving ride and reducing unwanted NVH. There were subtle bodywork modifications, too, such as a new front airdam and black door handles to replace the old-fashioned chrome ones.

Amazingly, there were still full order books for the SL, even at this time, and a long waiting list in certain countries – buyers in the UK were told to expect a two-year wait before getting their hands on a new car. All told, a total of 300,175 107 series models were built, including SLCs.

A 1981 Model Year 500SL. Note the dark grey lower section, applied to five-litre cars when finished in certain colours, and the rear spoiler. All cars received an aluminium bonnet at this time.

A 1983 R107 SL pictured with its illustrious predecessors.

One of the last R107 models, this being a domestic market 500SL, introduced at DM 89,091. Weighing a hefty 1610kg (3540lb), it was still capable of 140mph (224kph) and a 0-60 time of 7.8 seconds. Note the late-style alloy wheels, introduced for the 1986 season. R107 production finally came to an end in July 1989.