The Apex of full-sized Mercedes coupés.
During the 1970s, when the engineers at Daimler-Benz’s Sindelfingen nerve centre were in the driving seat, Mercedes could be relied upon to do things properly. For if their cars were mostly on the large side – often somewhat heavy-jowled – they were mostly fit for their purpose, whether intended for the commercial trades, for plutocratic conveyance, or simply chariots of the indulgent.
Research and development was key to the three pointed star’s pre-eminence. Mercedes engineers not only worked through what ever technical challenge they were attempting to overcome, but also considered all of the alternatives – frequently going so far as to build an exhaustive array of prototypes to eliminate from their deliberations the merely plausible.
The 126 series was the result of one such engineering research programme, initiated in 1971, and gaining particular impetus following the shock to the ecosystem that followed the 1973 oil embargo. In its aftermath the watchword at Stuttgart Untertürkheim became one of efficiency. If the once intemperate luxury car was to survive into the following decade, it was going to have to study frugality, cleave the air in a less restrictive fashion and jettison those corpulent excess kilogrammes.
But a more compact car was out of the question for a host of reasons, as outlined to journalists in 1979 by head of development, Friedrich van Winsen, not least the fact that Mercedes’ customer data at the time illustrated that S-Class customers covered twice the annual mileage of the average German, while conveying a greater number of passengers. No, smaller was not a viable option; the answer had to lie with a more intelligently engineered car.
The W126 programme would achieve fruition in Autumn 1979 with the debut of the second-generation S-Class. To those established qualities of active and passive safety, user convenience and driver-focus, Mercedes’ engineering team, overseen by Professor Werner Breitschwerdt, melded those principles of efficiency and social responsibility which so defined its genesis. Much as intended, the W126, in true Sindelfingen fashion, reset the luxury saloon benchmark, just as its W116 predecessor had done seven years earlier.
Mercedes-Benz outlined the W126 concept to the world’s press in typically understated terms: “to further improve in a sensible manner those features which had characterised all previous top-class Mercedes cars; a maximum of comfort and performance, based on the latest findings in engineering, safety and reliability, complemented by a level of quality in manufacture and styling that sets the standards“.
Continuity, while simultaneously embracing radical change was very much the order of play when it came to the 1979 Sonderklasse, but for its more indulgent two-door equivalent, a slightly different set of priorities would come to the fore. Its direct predecessor, the C107 SLC series, had been based on the equivalent SL; and while the outgoing SLC had its proponents, it was something of an anomaly in Untertürkheim terms, being the first, and as it would prove, only example of a full-sized Mercedes coupé to be twinned with the more sporting SL line.
Even if it looked a good deal lighter on its feet than its forebears – or indeed its successor for that matter – the 1971 SLC was no lightweight. But despite healthy sales over its lifespan, the Mercedes supervisory board concluded that this approach was no longer the preferred direction of travel. The C-126 therefore would mark a return to business as usual, closer to the highly regarded W111 coupés of yore in scale and ‘presence’.
By consequence, and for sound cost and marketing reasons, the SEC was twinned with W126, both in engineering and stylistic terms. Sharing running gear and technical hardware with the saloon, the C126’s bodyshell employed a short-wheelbase (3″ less) version of the saloon floorpan. A coupé in the dictionary sense of the word, its roofline was an inch lower, for a more rakish profile. To save weight, aluminium was employed to skin the bonnet, boot lid and rear bulkhead.
Having ascended to the design leader role, the W126/C126 programme was to mark the first model line to be wholly overseen by Bruno Sacco; his brief being to reflect the styling of the saloon, but to subtly shift the emphasis from stiff formality towards something at least approaching a more relaxed demeanour. Central to this was the nose treatment – for the first time on a full-size Mercedes coupé, a horizontal grille motif[1] would reflect that of the SL model line rather than the more formal, vertical arrangement which had been the norm.
In terms of surfacing and overall body architecture, the SEC cleaved closely to the W126[2], but the second and most profound departure lay in the treatment of the canopy. The lower roofline lent the silhouette an element of almost Italianate grace, culminating in the beautiful sweep of the C-pillar towards the rear deck line[3]. Like all Mercedes coupés, there was a pillarless arrangement to the side glazing, the glass retracting to create an seamless, unimpeded opening. Elegance reigned[4].
In the arrangement of the car’s volumes, forms and intersections, the SEC was a masterclass[5]. But there was science too behind the beauty. The SEC’s coefficient of drag was 7 % lower than that of its W126 saloon stablemate; its Cd at 0.34 an improvement of 15% over its SLC forebear (which appeared lower slung) while its CdA was 7% less.
The cabin was also derived from that of the saloon, the dashboard and instrument panel being shared and identical in layout. The seats however were of a different, more enveloping design with increased side bolstering. The rear seats too were of the individual type. A neat touch was an arm which extended to offer the seatbelt to front seat occupants as soon as they key was inserted into the ignition. Typical Mercedes insofar as this could be termed as both a safety and convenience feature. Otherwise, all was as logically laid out[6] and superbly assembled from quality materials as any Daimler-Benz product of the era.
While most of its technical hardware was shared with the saloon, the SEC marked the debut of Mercedes ‘Energy Concept’ series of V8 engines. Based upon the existing power units, the two V8s offered were essentially redesigned, the 3.8 litre employing a longer stroke length, and a lower compression ratio, providing more torque at lower crankshaft speeds, improving driveability and economy, especially in its high-geared top ratio[7]. This was no idle boast either. In a July 1982 test report, Autocar described the economy figures obtained from their subject 380 SEC[8] as being “outstandingly good”.
The W126’s road behaviour was lauded by all who drove it for the thoroughness of Mercedes’ chassis engineering and the car’s imperious capabilities in all road conditions. The SEC further improved upon this, motor journalists citing the coupé’s improved steering response, more surefooted handling and of course its superb braking capability, bolstered considerably by the (highly desirable) option of the Bosch ABS anti-lock system.
During this period, the major European carmakers maintained something of an unofficial non-compete agreement, where the likes of Mercedes, BMW and Jaguar agreed not tread upon one another’s toes, instead playing to their respective marque-specific qualities. But even allowing for this, and acknowledging that the SEC played very much to Mercedes’ core strengths, the big Swabian coupé, like its saloon sibling existed very much in a class of one. While others such as Porsche or BMW might have fielded cars which nipped at the SEC’s heels, none could really offer anything close to the sheer breadth of talent the big Mercedes coupé embodied.
Just over 73,000 SECs were built over a ten year production run, the final example leaving Sindelfingen’s tracks in August 1991[9]. The C140 that replaced it was a fine car, but one that suffered to a certain extent from the same excess of ambition and mission creep that afflicted its saloon donor, and while there have been S-Class coupés of various stripes on sale up to 2021[10], none of the generations that followed came close to the essential rightness, patrician grace, calm and sheer rigor of the SEC[11].
Some stars just shine that much brighter.
[1] Bruno Sacco: “Of all the Mercedes-Benz models I was responsible for designing, the C 126 has the most beautiful front end.”
[2] With the possible exception of the front wings (fenders), it is unlikely that a single external pressing was shared with the W126 saloon.
[3] Amongst the styling studies for C126, was one whose C-pillar and rear screen treatment reflected that of the W111 Coupé from the 1960s. While elegant, it’s clear Sacco and the Mercedes Supervisory board made the correct choice.
[4] The distinctive external door handles were cleverly designed to resist road grime, but looked unsightly. Sacco and his design team loathed them, but Engineering would not be moved.
[5] The eminent Italian former design chief retains a 1989 560 SEC in his personal garage.
[6] In its 1981 Car review, it stated, “There is no on-board computer, and Daimler-Benz say, there won’t be one. Mercedes’ owners, they say, want to drive their cars, not play games with them“. Oh, has the world changed or have I changed?
[7] The SEC was only available with Mercedes’ own 4-speed automatic transmission. There was no manual option.
[8] Initially, US market SECs were only offered in 380 form to comply with CAFE restrictions. With full emissions equipment it was no ball of fire. This was remedied in 1984, with the introduction of the 5ooSEC.
[9] This was retained by the Daimler Museum.
[10] The S-Class coupé is no more, the C222 being the final iteration of the line.
[11] The combination of Prof. Werner Breitschwerdt in Research & Development and Bruno Sacco in design was to prove an unsurpassed combination of talents at Sindelfingen. So much so that few to this day can quite grasp just how far ahead of their rivals Mercedes were at this time. Tellingly, Mercedes-Benz’s current styling imperator has since derided Sacco’s work, the stable genius of Carlsbad describing it as “forced”. This is wrong on so many levels that it’s almost laughable – not least that the correct usage of the term suggests an involuntary act – which in Sacco’s case may well have been the case. After all, Sacco couldn’t help being gifted, just as his Gordenness can’t help being distinctly mediocre.
For 1986, both W126 and C126 received a minor cosmetic facelift, while for the SEC, engine capacities encompassed 420, 500 (in some markets) and 560 designations.
In 1983, Breitschwerdt became Chairman of the Board of Management of Daimler-Benz AG, a position he was ousted from in 1987, much to Mercedes-Benz’s detriment.
Sources: Car magazine – December 1979/ Autocar – 17 July 1982/ Car magazine – December 1981/ Mercedes-Benz.com
Driven To Write 
Good morning, Eóin. This star definitely shown bright. I never liked the door handles, but I didn’t realize they were designed with the purpose of keeping them clean. I still think I’d wash my car just that little more often.
On a sidetone: the onboard computer, or reiserechner as it was called, was available as an option (code 245) from 1984 onwards. There’s an interesting article in German about it here.
https://www.fuenfkommasechs.de/der-w126-damals/innovationen/reiserechner/
The door handles were like the ribbed tail lights, on a long trip in bad weather they retained their useful function, in the handle’s case, they remained clean, in the light’s case, they remained visible.
The engineering people at MB thought, quite rightly that people with the means to purchase new Mercedes Benzes don’t have time to stop and clean things that they shouldn’t have to.
I miss the Mercedes Benz design teams that used to think like that.
You are right. I like the old Benz engineering, but I also like washing my car. Isn’t it strange that the exterior doorhandles are handled in a different way on the W126 and C126?
The W126 saloon was meant to be driven by an employee with the owner sitting in the rear. The C126 was meant to be driven by the owner.
Employees can get their hands dirty, owners can’t.
And yet most W126 owners I knew back in the day drove the cars themselves.
The logic is the other way round.
If you wanted a car to be driven in it had to be a W126 (and very often an armoured version), at least in Germany.
It was not Mercedes’ fault if you didn’t have the money to pay a driver.
Late in the day of the W126 the logic changed and the W126 got the leather steering wheel the C126 always had but was considered unhygienic before for the saloon because owner and employee would have used the same surface that could not be sterilised.
One of my country’s wealthiest men had one of these, a 500 SEC, which he’d bought new on the car’s release. A genuine billionaire, one of the very few in New Zealand, with a fortune based on the family’s paper mills, he used the car daily, and said it was all the car anyone would want. He turned down all of the local importers offers of replacement with later S coupes as ‘un-neccessary’. His comment after seeing the C140 was ‘They must be joking’.
He had the car until his death in 2016 and his children have kept the car in his memory.
https://en.wikipedia.org/wiki/John_Spencer_(businessman)
Ah… the SEC. My favorite Mercedes of all time. Now and then I still trundle the classifieds and dream. What if?
Who knows one day? I’m crazy enough to have a 955 Cayenne S as a daily driver so it still might happen.
I know an immaculate 560SEC for sale. It comes at a price, though.
For all the undoubted design and engineering brilliance and rigour I was struck by how badly the steering wheel is offset.
Well observed, Joel, and a surprising compromise in such a large car.
I also think the steering wheel is too big.
One other thing I always wondered: with the reiserechner in place, as in the photo above, do you lose the digital outside temperature gauge? Because all the photos I see always show the time on that display instead.
Were these the last ‘GT Coupes’ to be available with steel wheels and hubcaps? (As seen in the 2nd, 3rd, and 5th photos.) Even on these, amongst the more expensive cars when new, alloys weren’t standard?
Freerk: The steering wheel is oversized so that the car could still be operated if the steering’s servo-assistance failed.
David: While no proof, I can report that just today, I came across a tidy C140, piloted by appropriately mature a driver, on steel wheels with hubcaps. Back on the early ’90s, even the most luxurious of cars would typically be on steel wheels during winter season.
I like the logic behind the big steering wheel, but I wonder how often the power steering fails.
Having said that I once was towed by an emergency vehicle in a car which engine refused to start. It had a smallish steering wheel and since the engine wasn’t running there was no power steering. It’s a good workout at low speeds 😉
“After all, Sacco couldn’t help being gifted, just as his Gordenness can’t help being distinctly mediocre.”
Good morning, Eóin. It’s bad enough that Wagener is, as you rightly say, mediocre, and simply not up to the job, but shameful that he has the temerity to cast aspersions on Sacco and his brilliant work.
The W126 is just sublime.
Did Wagener really cast aspersions? Good grief. You could fill a top 20 of greatest car designs with five of Sacco´s cars.
I was awestruck seeing a sparkling black one of these parked in the garage of a friend from school. It was the most imposing, yet svelte automobile I’d ever seen and I was surprised I knew someone who had one. Part of the amazement, and telling of my proletarian upbringing, was the thought that this was the most expensive car I’d ever seen, but it was a coupe. How are the four kids supposed to fit? Simple answer, they don’t.
The big advantage of the Coupe was – besides the striking design – the comfort of the seats. The seats of the W126 Sedan were the weak point in the most important category for a luxury car, comfort.
So if you are searching a W126 Sedan, you have to search for a rare version with the seats of the Coupe instead the flat bench. Ordering these seats was very expensive, about 7000€ extra.
By the way, Mercedes did create their own Alcantara cloth. It was called Amaretta and was available for the W126.
So i would pick a 420 SEC in red with brown amaretta seats…..
Interestingly, all those SECs are on oval West German ‘export’ number plates.
The SEC was the darling of F1 drivers in the 80s. I remember a Mercedes-Benz advert that lined up all the drivers’ SECs on the starting grid. Unfortunately, I can’t find it, so instead, here are some pictures of F1 drivers and their SECs:
Epic 1980s style and ‘stache for Keke Rosberg, posing in front of his AMG-kitted SEC:
https://scontent-mad1-1.xx.fbcdn.net/v/t31.18172-8/15272141_10154294830278772_8009896517097684781_o.jpg?stp=cp0_dst-jpg_e15_p320x320_q65&_nc_cat=107&ccb=1-7&_nc_sid=2d5d41&_nc_ohc=_Dbumu-Rf9YAX_QKK03&_nc_ht=scontent-mad1-1.xx&oh=00_AfCXqccTYRmzxnPvW7haTFJiYtKHER8QBIJhXZ4eEvuaPg&oe=63CBA436
Ayrton Senna looking cool with his tastefully discreet (i.e. non-modified) SEC:
Our great Nigel Mansell looking a bit like a kid posing in front of his dad’s Mercedes 🙂
https://www.benzworld.org/attachments/12_1243329_67200495452am-jpg.20910/
cesargrauf: In addition to the F1 drivers you mentioned, you can add John Watson, who also took delivery of an SEC in 1982. Another notable owner was the British art critic and author, Brian Sewell.
I am not sure all of the F1 drivers owned their SEC’s outright. As I understand it, it was s very successful publicity stunt by Mercedes, and I would guess what they were “given” was a free three year lease from the executive lease program. In essence, they were running around in a leased car but without having to pay the actual lease, as a sort of gratuitous perk from Mercedes.
Intetestingly, the members of Abba had a similar deal with the Swedish BMW importer, that’s why they were all driving around in BMW’s in the 70’s. Also the American astronauts had a similar executive deal with General Motors, they were allowed to pick out two new cars every year that they were free to use, most times a Corvette and a station wagon. I think Neil Armstrong was the only one that didn’t pick out a Corvette?
Ingvar: According to Tom Wolfe’s “The Right Stuff”, John Glenn drove a Peugeot.
Ah, so it was. There’s always one in a crowd that have to be different….
The point of the Mercedes publicity stunt is that they got the SEC “trending” in that kind of crowd, which I’m sure lead to a lot of additional sales. Because come to think of it, the idea is quite genius. What would a Formula One driver really need after a day of driving the fastest cars in the world as their day job? Well, not another superhyper car but the most luxurious and comfortable ride in the world to and from their work.
The C126 is one of the few cars that you have to drive to really understand. It’s not sporty, even if a 560 with the ECE engine is still a very fast car, it’s not soft, it’s not flashy; it’s simply right so right in many ways, and a magnificent way to travel, forty years on still better than most of what is available today
I was lucky enough to drive, five or six years ago, a low mileage 560 SEC in very good condition. I think it´s rather soft, and I´m not a fan of hard riding cars. But I understand it; SEC buyers wanted their cars that way.
Here’s big-hair Maradona and his 500 SEC with Spanish temporary plates. This was toward the end of his Barcelona football years.
„the SEC marked the debut of Mercedes ‘Energy Concept’ series of V8 engines.“
That is not quite true. The M116/116 line of engines debuted in 1979 with the W126 sedan in 3.8 and 5.0 guise and were in fact also available in the C107 SLC for the 1981 model year. For the release of C126, both engines were slighlty tweaked, with output of the 380 SEC going down to 204hp from the 380 SLC‘s 218hp (not to be
mistaken with the measly 155hp the CAFE-strangled US version of the 3.8 managed)
Ok, after some quick fact checking, I take that back! 😄
While the major change during the M116/117’s career came in 1979 with the switch from cast iron to aluminium engine block, 1981 brought further changes to bring fuel consumption further down – a.k.a. the „energy concept“. And yes, these revised alu M116/117 made their debut in the SEC, I stand corrected.
btw, as a former owner of both a 380 SLC and a 500 SEC, I can attest both are faboulus. When deciding which one is better I‘d say the SEC. It’s beyond impressive even by today’s standards.
In the early Nineties a friend told me with a big grin that he had bought one of those five litre cars recommended by the EU.
His was a C126 500 SEC in dark grey with black leather and nearly every option except a C net car phone.
The former owner had died and nobody from the family wanted the car do it was his for not much money.
“In the early Nineties a friend told me with a big grin that he had bought one of those five litre cars recommended by the EU.”
When VW released the Lupo 3L there was a story about Renault was going to launch a Clio 3L, too. So VW engineers hurried up to get their Lupo first, but finally, the Clio “3L” was the mid-engined 3.0 V6.
Regarding footnote [2] and body panels common between W126 saloon and C126 coupé.
As far as I could find the front wings have different spare parts numbers and the wheelarch liners have the same. The wings of the 560 versions of both body styles have different parts numbers from the rest because the 560 wheelarch lip is wider because the cars had wider tyres.
So far for Mercedes’ thoroughness of engineering.
I have a list of the changes made to both body styles over the production run and it’s simply amazing what they were paying attention to.
‘vacuum reservoir for central locking moved from engine compartment to boot for less sensitivity to temperature’
‘switch for (vacuum operated!) headlight range adjustment provided with lock valves to prevent loss of pressure and unnecessary movement of lights’
‘sound deadening material stuffed between edges of fuel tank and lower C post to recude swoosh sounds under cornering’
‘electronic control for low fuel warning light introduced to eliminate unnecessary activation of light under cornering at certain fuel levels in tank’
That’s what I would call ‘the best of nothing’
And, to be fair, engineers love fiddling – it’s in the job description (and M-B had a culture which allowed engineers to flourish).
By way of illustration, here are the changes for 1950 for the Volkswagen Beetle. That tailpipe enlargement must have made all the difference.
Small emblem hubcap replaced big emblem.
5 torsion leaves in each tube.
Gaskets between cylinders and heads.
Bosch headlights replace VW item on saloon and cabriolet.
Tailpipe increased from 31 to 32mm.
Inlet manifold now made of light alloy.
Small cut-outs in tops of door windows.
Hydraulic brakes on export saloons and cabriolets.
Automatic engine cooling control by bellows.
Brake master cylinder reduced from 22.2mm to 19.5mm.
Rear brake cylinders reduced from 19.05mm to 15.9mm.
Carby fitted without hinged float from chassis 213301 to 213455.
Option cloth sunroof.
Hole for external crank handle discontinued on Cabriolet in late 50.
Heat riser added to intake manifold.
Offset wrist pin to reduce piston slap.
Stronger alloys for exhaust valves and inserts.
Here’s the full (mind-boggling) list:
http://www.vw-resource.com/years.html
One of the best cars I have owned. An unusual marriage of the traditional virtues of Mercedes engineering solidity with a covetable style. And excellent seats! My current car, a 2000 era Lexus GS300 lacks the style but has the same sense of depth of thoughtfulness and quality. And great seats, too.