Part Two: The matinée idol’s lesser-appreciated sibling.
Like everybody else, Mercedes-Benz’s engineering teams had rather a lot to contend with by the late 1960s. Not simply developing the nascent W116 S-Class, the most ambitious and luxurious mainstream saloon yet to bear the three pointed star, or perfecting the advanced rotary-engined C111 prototype – in addition to ongoing developments for both conventional petrol and diesel powertrains, there was also a seemingly limitless tsunami of emissions and safety mandates emanating from the land of the free.
Facing large investments, and no small level of commercial risk associated with new model programmes, the Mercedes-Benz supervisory board are believed to have vetoed a proposal to directly replace the existing W111/112 coupé and convertible models.
However, longstanding head of Body Development and Research, Karl Wilfert believed he had the solution, developing a proposal for a fixed-head, four-seater coupé version of R107, which was then presented to the supervisory board. Given the level of technical and production-engineering carry-over, a business case was established and the programme officially sanctioned in 1969.
The C107 which emerged employed a longer wheelbase version of the R107 body, lengthened aft of the door strike-plate by a not inconsiderable 360 mm (14.2 inches). Rear compartment aside, the cabin was near-identical to that of the sister-SL model; the driving environment being as up to date in ergonomics, and materials as it was in passive safety features.
While the SLC’s external style closely followed that of its 2-seater sibling, the extra length in the body did not simply provide a more commodious cabin, it also moderated the SL’s somewhat truncated silhouette – a factor of its short 2460 mm (96.6 inch) wheelbase – the extra length enabling a somewhat more balanced shape.
But while one dimension giveth, another taketh away; the addition of the fixed canopy raising a number of packaging and engineering-related questions which the car’s slightly inharmonious mien would have difficulty answering. A certain mismatch between height and length for example, meaning that like its SL sibling (if for differing reasons), the C107 too lacked a wholly convincing set of proportions.
Furthermore, as Mercedes body engineers discovered, despite the additional length aft of the doors, the retracting rear quarter windows as designed could not avoid fouling the rear wheel wells. Since a Mercedes coupé without a fully retractable suite of side glazing was as unthinkable as larger, thicker C-pillars would have been from a visual perspective, an ingenious trompe d’oeil solution was arrived at; a series of metal louvres vacuum-sealed between an additional pair of fixed rear quarter panes, the upward slanting DLO outline closely reflecting that of the SL’s removable hard top.
It was a clever if rather frivolous solution, one which not only seemed a little out of character for the normally somewhat po-faced Sindelfingen carmaker, but one which successfully masked the rather seat-of-the-pants nature of its execution. But not only would it prove as aesthetically divisive as it was influential, it would become the SLC’s defining feature.
Very much in the US Personal Luxury Coupé vein, the SLC, while not entirely in a class of its own, lacked much by way of direct opposition at its Frankfurt motor show debut in October 1971. This would arrive in the fullness of time, but not before the paradigm shift of the 1973 oil embargo.
Two years later saw the advent of the SLC’s closest on-paper rival, Jaguar’s much delayed XJ-S. Browns Lane’s offering was faster, more sporting in responses and arguably, more rakish in appearance, but neither car were what the gentlemen of the press would describe as ravishing beauties. In Autumn 1975 Car Magazine pitched a 450 SLC against Jaguar’s newly launched GT and found the two cars very closely matched indeed.
While Car’s Mel Nichols found the Jaguar’s handling to be beyond reproach, he discovered that the SLC, while initially feeling less nimble, was in fact just as surefooted – a possible consequence of that longer wheelbase. The XJ-S could show the Mercedes a clean pair of heels in the higher speed ranges, where its superior aerodynamics aided matters, but in most conditions Nichols found the SLC to be just as quick. Where the Mercedes really scored was in cabin space, ambience and standard of finish, which was light years ahead of the rather austere looking (and in places, feeling) XJ-S. The Mercedes got the nod, by a hair.
The SLC’s fine chassis was likely the rationale behind the car’s motorsport career, initially fielded by AMG in 1978’s European Touring Car Championship, driven by Hans Heyer and Clemens Schickentanz. The SLC scored a single victory in three years of campaigning, taking the win at the Nürburgring Six Hours in 1980 with Schickentanz and Jörg Denzel sharing driving duties.
In the Autumn of 1977, Mercedes introduced the 450 SLC 5.0, featuring a brand new all-aluminium 4973 cc V8 engine, destined for the upcoming W126 S-Class range. This model, featuring front and rear spoilers was intended to homologate the car for the following year’s World Rally Championship, where the SLC would be fielded in selected events, driven by amongst others, Hannu Mikkola.
From the outset, both 107 models had been intended to receive a wide range of engines; Mercedes’ M130 six cylinder, the 3.5 litre M116, 4.5 M117 litre V8s and ultimately, the M950/3 and M950/4 Wankel units. However, Mercedes, like everyone else lost faith in rotary power, while the advent of a newer 2.8 litre M110 unit saw this selected as the entry level powerplant.
This 182 bhp fuel injected 2746 cc unit made its debut for both SL and SLC models in 1973, the delay arising from supply being prioritised for the saloon models. Despite being no great performer in the heavyweight SL/SLC duo, this economy engine did much to maintain European demand in a more straitened post-1974 environment.
1980 saw the 5.0 litre V8 become standardised, alongside a smaller capacity 3818 cc V8, which would become the mainstay US market engine, owing (it’s believed) to CAFE fuel efficiency strictures. The 1979 advent of the W126 would seal the SLC’s fate – Mercedes-Benz product planners decreeing that Sindelfingen’s large coupé ambitions were henceforth better served under S-Class underpinnings. In 1981, the C126 was introduced – the big coupé rendering the SLC obsolete with close to 63,000 built over a near-ten year lifespan.
Overshadowed by its more glamourous SL counterpart, which not only outlived it by some considerable margin, but outsold it as well, the C107 SLC nevertheless proved surprisingly successful, and given its shared underpinnings, highly profitable. But more than anything, the SLC would prove unique in the Mercedes-Benz pantheon – the first and last of its ilk.
 According to some sources, Karl Wilfert developed the C107 in secret, thereby risking censure from his superiors. This however is not borne out in the official telling of the car’s development.
 Was the R107 SL’s wheelbase slightly too short? There is reason to suspect that it was, just as there are (purely aesthetic) reasons to suggest the SLC’s was (slightly) too lengthy. Proportions notwithstanding however, the SLC presents a more realised, more convincing visual proposition than its 2-seater sibling.
 The incredibly complex three-quarter vent treatment was very much Karl Wilfert’s idea and visual taste, for which he argued forcibly, and successfully.
 The C107 SLC was received with a good deal of interest at Allesley, Coventry; with none other than Sir William Lyons singling it out as a benchmark for the nascent XJ-S then in development. Curiously, a similar issue arose with the treatment of the rear three quarter glass – Jaguar stylists also opting for a less than convincing vent arrangement. The influence of the 107 series proved more widespread – seen in the the De Tomaso Longchamp/ Maserati Kyalami duo and arguably, Cadillac’s Allanté.
Another notable SLC aficionado was a certain LJKS.
Source: Mercedes-Benz 280 SL – 500 SLC – Der Schritt zur Modellvielfalt : Günter Englen. I am also indebted to Christopher Butt for his kind assistance.