Mercedes-Benz W126

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Mercedes-Benz W126
1984 Mercedes-Benz 380 SE (W 126) sedan (2015-08-07) 01.jpg
1984 Mercedes-Benz 380 SE (W126)
  • December 1979 – October 1991 (sedan)
  • September 1981 – October 1991 (coupé)
  • ?–1994 (sedan, South Africa)
AssemblyGermany: Sindelfingen
Malaysia: Johor Bahru (OASB)[1]
South Africa: East London
DesignerBruno Sacco, Werner Breitschwerdt (sedan: 1975, 1976; coupe: 1977)
Body and chassis
ClassFull-size luxury car (F)
Grand tourer (C126)
Body style4-door sedan
2-door coupé (C126)
LayoutFR layout
RelatedMonteverdi Tiara
3.0 L OM617 diesel
2.6 L M103
2.8 L M110
3.0 L M103
3.0 L OM603 diesel
3.5 L OM603 diesel
3.8 L M116
4.2 L M116
5.0 L M117
5.5 L M117
Transmission4-speed 4G-TRONIC automatic
4-speed manual
5-speed manual
WheelbaseSedan (SWB): 2,935 mm (115.6 in)
Sedan (LWB): 3,075 mm (121.1 in)
Coupe: 2,850 mm (112.2 in)
LengthSedan (SWB): 4,995–5,020 mm (196.7–197.6 in)
Sedan (LWB): 5,135–5,160 mm (202.2–203.1 in)
Coupe: 4,910–4,935 mm (193.3–194.3 in)
WidthSedan: 1,820 mm (71.7 in)
Coupe: 1,828 mm (72.0 in)
HeightSedan (SWB): 1,430–1,437 mm (56.3–56.6 in)
Sedan (LWB): 1,441 mm (56.7 in)
Coupe: 1,406 mm (55.4 in)
PredecessorMercedes-Benz W116 (sedan)
Mercedes-Benz C107 (coupé)
SuccessorMercedes-Benz W140
Mercedes-Benz C140 (coupé)

The Mercedes-Benz W126 is the company's internal designation for its second generation S-Class, manufactured in sedan (1979-1991) and coupe (1981-1990) configurations, succeeding the company's W116 range.

Mercedes introduced the 2-door C126 coupé model, marketed as the "SEC", in September 1981, based on the standard wheelbase S-Class sedan.

Over the twelve years,1979-1991,[2][3] W126 S-Class production reached 892,123 — including 818,063 sedans and 74,060 coupés. It is the most successful S-Class in term of the number of units produced and the duration it was in production.

The S-class nameplate is an abbreviation for the German Sonderklasse or "special class".


Following the debut of the 1970s generation W116 (which also included the limited-production Mercedes-Benz 450 SEL 6.9), Mercedes-Benz began plans for the next-generation S-Class model in October 1973. Codenamed "project W126,"[2] the project aimed to provide an improved ride, better handling, and improved fuel efficiency,[3] to help retain the model's marketing position.[2] Mercedes-Benz made fuel efficiency a goal (named "Energy Program"),[4] in the large V8 engined versions of the S-Class.

The W126 design team, led by Mercedes-Benz's Bruno Sacco, aimed to design a more aerodynamic shape than the previous model. The application of lighter materials and alloys combined with thorough wind tunnel testing to reduce overall drag meant the car consumed about 10% less fuel than its predecessor.[3] The W126 featured the first seatbelt pretensioners.[2]

After six years of development, the W126 was introduced at the Internationale Automobil-Ausstellung (International Motor Show, or IAA) in Frankfurt in September 1979.[5] The initial range featured seven models in standard (S S-KLasse-Vergaser, SE S-Klasse-Einspritzmotor, SD S-Klasse-Diesel) and long (SEL, SDL) wheelbase sedan body styles: the 280 S/SE/SEL, 380 SE/SEL, 500 SE/SEL and 300 SD. The long-wheelbase (SEL) variants were internally codenamed V126.[2] In 1981, the coupé version C126 (SEC, acronym for (German) S-Klasse-Einspritzmotor-Coupé) of the W126 S-Class premiered at the IAA with the 500 SEC model. In 1981, Wheels Magazine selected the W126 model 380 SE as its Car of the Year.[6]

Although the top of range Mercedes-Benz 450 SEL 6.9 of the previous generation was not directly replaced, the W126 carried forward the hydropneumatic suspension of the 6.9 as an option on the 500 SEL and later on 420 SEL and 560 SEL models.

Four years after the introduction of the fuel-efficiency "Energieskonzept" (Energy Concept) in 1981, the model range was extensively revised. In September 1985, again at the IAA in Frankfurt, the revised model range was introduced. Apart from visual changes to the bumpers, side covers and larger 15-inch wheels with a new design on the hubcaps and alloys (optional), there where technical upgrades as well as revised engine availability. A new generation of inline-six petrol and diesel engines and new 4.2- and 5.5-litre V8s were added, and other engines were revised.

The W126 generation was replaced by the W140 in 1991, although a satellite factory in South Africa continued limited production until 1994.


Facelift Mercedes-Benz 560 SEL (V126)

From 1973 to 1975, Mercedes-Benz designers worked on the successor to the W116. In December 1975, after several design concepts being presented, the design for the W126 S-Class was approved and frozen in 1976.[7] Design work on the coupe began immediately afterward, being finalized in 1977.

Compared to its predecessor, the W116, the W126 featured improved aerodynamics (with a drag coefficient of Cd 0.36 for the sedans, 0.34 for the coupés).[2] The W126 was the first Mercedes equipped with polyurethane deformable bumpers.[3] Design patents were first filed on March 3, 1977 and later on September 6, 1977 at the United States Patent Office.[8]

In 1985, Mercedes-Benz issued a facelift for the W126, with revised bumpers, body side protection mouldings, and wheel designs. The 14" alloy rims largely standardized throughout the MB family since 1969 were replaced with the 15-slot flat-faced silver painted alloy rims.

The interior featured pleated leather on the doors and leather seats in the North American markets; while global markets offered velour seating trim. Zebrano wood trim was used on all S-Class models during the first phase of the generation's run (1979-1985) with burled walnut available in the second phase (1986-1991) the 560SEC and 560SEL.


Pre-facelift Mercedes-Benz W126 380 SE (standard wheelbase version)
Facelift Mercedes-Benz 560 SEL V126 (long-wheelbase version)
Facelift 1989 Mercedes-Benz 300 SE
Pre-facelift Mercedes-Benz C126 SEC (coupe)
Pre-facelift Mercedes-Benz C126 SEC (coupe)
Facelift Mercedes-Benz C126 SEC (coupe)
Facelift Mercedes-Benz C126 SEC (coupe)

The W126 series (named in accordance to their engine size) initially included the 280, 300, 380, and 500 series models. Following the first S-Class mid-cycle refresh, the W126 series included 260, 300, 350, 420, 500, and 560 models. Variants included SE (standard wheelbase), SEL (long-wheelbase), SEC (coupé), and diesel models (SD and SDL).


Features included the following safety, comfort, and technological features.


Late model W126 with Airbag, leather seats, and Burlwood interior wood trim. Left hand Drive.
  • Use of high strength low alloy steel (HSLA) in its construction to reduce the weight without compromising the structural strength and integrity.
  • Anti-lock braking system (ABS) (first appeared in its predecessor, the W116) was standard on 500 SEL and 500 SEC and optional for the rest of model range until 1985. The ABS eventually became standard for the entire model range during the second series (1986-1991).
  • Seat belt pretensioners ETR enabled all seat belts (with exception of rear centre shoulder belt on sedans) to tighten when the car sensed conditions that could lead to an accident (such as sudden, forceful braking or sudden deceleration during the collision).
  • Crumple zones front and rear which absorbed impact energies, reducing passenger injury.
  • Fluted taillamps, the design pioneered on the R107, was carried over. The fluted design maintains the visibility of taillamps when the dirt accumulates on the outer edges.
  • Driver's airbags were introduced in 1981 as an extra-cost option for all models and engines. From September 1987 on, the passenger's airbags were added as extra-cost option for the 1988 model year. The consumers could choose either driver's airbag only or driver's and passenger's airbags. For the US market, the driver's airbags were standard from 1987 onward due to the federal regulations; the passenger's airbags were extra cost option until 1989 when they became standard for models with V8 engines only and 1991 for the rest of model range.
  • Traction control system (TCS), also known as Acceleration Slip Regulation (ASR) to prevent wheelspin (a Mercedes-Benz first). Available only on European models from 1989 until the model year 1991, when it was introduced on 560 SEL and SEC models in the United States for that last production year only.
  • A third brake lamp in the centre of rear windscreen was federally mandated from 1986 model year on for the US version only. In some markets, it was offered as standard or extra-cost option.

Comfort and convenience[edit]

Early model W126 without airbag, MB-Tex seats, and Zebrano interior wood trim. Right Hand Drive.
  • Courtesy lights on the underside of the doors, to enable the occupant to see the ground when exiting the vehicle at night.
  • Rear reading lamps were fitted to the C-pillar enabling rear passengers to read or work at night without distracting the driver. Extra cost options for the rear seat passengers were: individually adjusted seat heaters (never offered in coupé models during its entire production run); bench seat that can move forward and back electrically by 10 cm (long wheelbase models only); foot rests; from 1987 on, rear windscreen window shades that are electrically raised and lowered by switch on centre console; and the back of front seats are contoured as to give more legroom.
  • From 1979 to 1984, the driver and front passenger seat heaters were separate extra-cost options. From 1985 to 1991, both driver and front passenger seat heaters were offered as a single extra-cost option.
  • Beginning with 1985 model year, the rear individual seats and centre console as appeared in coupé model could be fitted to the long wheelbase models if the owner desires, giving the car a 2+2 seating format. The individual seat is electrically adjustable by moving forward and back only.
  • An optional fully automatic climate control system that used an interior temperature sensor to more accurately climatise the cabin. This sensor was mounted overhead (near the sunroof switch) so that when the roof was open, the sensor would detect cool air-flow and call upon the system to adjust heat flow accordingly.
  • Exterior temperature sensor with LCD display set in main instrument console below the speedometer to inform the driver of exterior conditions. This was delineated in Fahrenheit for US-market cars and in Celsius for the rest of the world.
  • Due to the B-pillar moving further back in the coupé models with longer doors, Mercedes-Benz developed seat belt presenters. When the doors are closed and the motor started, the presenters extend the shoulder anchor points forward to the driver and front passenger by about 30 cm. This facilitates easier reach and grab of seat belts. Once the seat belts are anchored or after 30 seconds, the presenters descended back into the B-pillar.
  • W126 premiered the power seat control, a first for Mercedes-Benz. Instead of placing the toggle or button switches with same shapes in the hard to reach or see areas, Mercedes-Benz developed the haptic switches in shape of a seat: one switch resembling the seat back is for adjusting the seat back; another switch resembling the seat is for moving the seat forward and back as well as raising and lowering. The two memory function buttons allow the front occupants to set and select their preferred positions accordingly. After the 17-year patent expired, this design was widely copied by other manufacturers in the late 1990s. Another first for Mercedes-Benz is an electrically adjustable steering column that extends and contracts by toggle switch underneath the steering column. The steering column position can be stored in the driver's side memory function along with the preferred seat position.
  • W126 was first from Mercedes-Benz to have the theft deterrent system as option installed at the factory. EDW (Einbruch-Diebstahl-Warnanlage, break-in theft alarm system) can emit the alarm sound and immobilise several components (radio, brakes, ignition lock, and a few others) if the car was being towed away or if any of hood/bonnet, trunk/boot, doors were forcibly opened. From 1984 on for the models with central locking system, the owner can turn the front door lock further to bolt the doors as to make them very difficult to be forcibly opened. The owner can order the separate bolt system for the trunk/bolt, making it equally difficult to pry the trunk/boot open. They require a special key with red dot.

Drivetrain technologies[edit]

  • Four-speed automatic transmission has a new topographical sensor that improved the drivability by monitoring the vehicle's position (flat surface, incline, or decline) and the position of throttle pedal. This prevents the unintended acceleration when coasting downhill without the frequent braking to maintain the speed. The Second Series has a "hill-hold" feature that prevents the vehicle from rolling back suddenly when disengaging the brake and engaging the throttle pedals at the steep incline. The transmission in European models has a S/W switch to allow the start in either first (Standard) or second (Winter) gear respectively. The topographical sensor also offers a better driving experience with cruise control by adjusting the throttle smoothly and automatically without sudden lurching or decelerating when maintaining the desired speed.
  • The W126 carried forward the self-leveling hydropneumatic suspension of the W116 450 SEL 6.9 model. Like the W116 and W123, the rear-wheel hydropneumatic suspension system was offered in W126 as an option. The four-wheel hydropneumatic suspension system, updated and named HPF II, was available as extra cost option for 380 SEL and 500 SEL from 1981 to 1985 and never for the rest of the model range or two-door models (380 SEC and 500 SEC). It was offered in 500 SE for a very brief time in 1985. For the Second Series (1986-1991), the hydropneumatic suspension was heavily redesigned and named HPF III. The HPF III automatically lowers the chassis by 24 mm when the vehicle is travelled at least 120 km/h for improved aerodynamic flow and better high speed stability. The system adjusts the dampering rate from soft to hard based on speed and road condition for extra comfort and better drivability. Additionally, the driver can select to raise the car by 35 mm if travelling over coarse-surfaced road (only up to 80 km/h). From 1986 to 1990, the HPF III option was available in 420 SEL, 500 SEL, 560 SE, and 560SEL. For the final year of production, HPF III was available in longer wheelbase only (420 SEL, 500 SEL, and 560 SEL). Due to its complexity and tendency to fail catastrophically, HPF III was very difficult to service and was often, at the owner's request, removed and replaced with coil springs and shock absorbers from models without hydropneumatic suspension system.[9]
  • At the 1983 International Motor Show Frankfurt, Mercedes-Benz introduced Reiserechner, its first trip computer option, in W126 for the 1984 model year.[10] The trip computer has a rectangular control panel on the centre console between the power window switches and the round information panel in the instrument clusters. A panel occupies the gauge cluster formerly used by tachometer, which moved to the left gauge cluster, sharing with oil, fuel, and temperature gauges. The information panel contains a large horizontal LCD display in the middle. Each of four sections has three arrows, illuminating the driver's selection. The upper left section is ZEIT (time); the upper right, WEG (route); lower left, GESCHW. (GESCHWINDIGKEIT, speed); lower right, VEBR. (VERBRAUCH, fuel consumption). The control panel has a large raised cross in the middle, dividing the panel into four corresponding sections of two buttons each in a four-by-two grid. The haptic touch allows the driver to feel his way around the control buttons without taking his eyes off the road: a typical Mercedes-Benz safety consideration. The four buttons in the middle allow the driver to select ZEIT, WEG, GESCHW., or VEBR.: the selection of their subfunctions is cycled through by pressing the button a few times. Two buttons on left side are for selecting short distance (K = KURZSTRECKENBETRIEB) and activation for inputting the number (P = PROGRAMMIERTASTE). Two buttons on right side are for selecting long distance (L = LANGSTRECKENBETRIEB) and deactivation of inputting the number (E = EINGABEABSCHLUẞTASTE). The top row of buttons (K, upper-left section, upper-right section, and L) has input of 1000, 100, 10, and 1, which are activated by pressing P and deactived by E. The option was dropped in W126 a few years later due to its complexity of configuring the trip computer, requiring an accompanying 18-page instruction handbook to understand its operation, and due to the frequent failure of its control panel buttons.


First Series (1979-1985)

At the introduction in September 1979, the 2.8-litre DOHC six-cylinder inline M110 engine for 280 S, 280 SE, and 280 SEL was carried over from W116. The new generation of M116/M117 V8 engines had a significant innovation: aluminium block without iron sleeves as found in the competitors’ engines. Mercedes-Benz developed a special silicon coating as to harden the cylinder liners against excessive wear and tear. The V8 engines were offered in two sizes: 3.8 litres (M116) and 5.0 litres (M117). The smaller of two V8 engines was offered in the US market only, which turned out to be a disaster, both due to timing chain repair issues, and to being severely underpowered, with 0-60 acceleration in a leisurely 11 seconds and a modest top speed of 117 mph (188 km/h). [11] [12] The S-Class coupés were fitted with V8 engines only for the first time.

The 3.0-litre five-cylinder inline OM617 diesel engine was carried over from W116 with same performance. Inexplicably, the diesel engines were again never offered in the markets outside United States and Canada. The lethargic acceleration, roughness, and lower top speed might not appeal to the European consumers who had higher expectations for the large saloons. This discrepancy wasn't addressed until 1994 when W140 S 350 TURBODIESEL was introduced in Europe for the first time.

In 1981, Mercedes-Benz introduced the “Energiekonzepts” (Energy Concept) programme in reducing the fuel consumption. This programme revised the combustion chambers and piston heads with lower compression ratio in the V8 engines. This revision caused further drop in engine performance.

Second Series (1986-1991)

For the second series introduced in September 1985, the engine range was extensively revised with new six-cylinder inline engines and enlarged V8 engines. Only 5.0-litre M117 V8 was carried over from the first series, expanding the V8 engine range to three.

The revised engine range focused more on reducing pollution and fuel consumption even further. For the first time, the customers outside US and Canadian markets could choose the models with or without catalysators. The models without catalysators can be retrofitted with catalysators at later date if the customers choose to: this retrofit method is called RÜF (Rückrüstfahrzeug — loosely translated as retrofit vehicle). The RÜF models had a mechanical switch in the engine bay to be operated by owners for running on lead or lead-free fuels, a necessary feature for driving outside Germany or in areas within Germany where the lead-free fuel wasn't widespread yet. In 1990, all engines were fitted with catalysators only.

The new six-cylinder inline M103 engine had a single overhead camshaft and electronic-mechanical fuel injection and was available in two sizes: 2.6 and 3.0 litres. The carburetted engine fitted to 280 S was eliminated, marking the end of carburetted engines for S-Class, and replaced with fuel-injected engines for 260 and 300.

The V8 engines were again bored out to 4.2 litres from 3.8 litres for 420 (M116) and 5.5 litres from 5.0 litres for 560 (M117) while 5.0-litre V8 for 500 (M117) was carried over. The V8 engines were fitted with new electronic ignition system and Bosch KE-Jetronic electronic-mechanical fuel injection system, first appeared in W201 190E. The revised V8 engines except 5.0-litre version had slight performance increase.

The most powerful engine ever fitted to W126 S-Class was 5.5-litre V8, putting out 221 kW (300 PS, 296 bhp). This engine, classified as ECE-Variante (German name), has higher compression ratio of 10:5 and cannot be retrofitted with catalysator at later date. In September 1986, the ECE-Variante was superseded by RÜF-Variante, which retains the same horsepower figure without catalysator and lower figure if retrofitted with catalysator at later date. The 560 SEL with 221 kW engine was fastest large saloon, reaching 250 km/h (155 mph), until BMW 750i/750iL was introduced in 1987 with ungoverned top speed of 300 km/h (186 mph). Its performance was comparable to Porsche 911 Carrera 3.2 or Ferrari Mondial. In 1990, 560 SEL had a reduced horsepower figure to 200 kW (272 PS; 268 bhp)

For the US and Canadian markets, a new 3.0-litre six-cylinder inline OM603 diesel engine was introduced, replacing five-cylinder engine with same displacement. It was a first six-cylinder passenger diesel engine by Mercedes-Benz. This new engine was available in long wheelbase version only, 300 SDL, for the first time. For California, the diesel engines were fitted with diesel particulate filter, a world's first for the passenger car. The new engine had an ill-gotten reputation for higher percentage of aluminium cylinder head failure due to poor placement of diesel particulate filter and due to the erosion of head gasket, allowing cooling fluid to seep in the cylinders. However, they failed to perform as designed and were removed from the engines. For 1988, the engine was revised to correct the issues and move the particulate filter further away from the engine. In 1990, the same engine was bored out to 3.5 litres as to compensate for reduced performance due to stricter emission regulations. The bored out 3.5-litre version did not have any of aforementioned issues other than some units experiencing the unexplained erosion of head gasket. The 3.5-litre version was available in both standard and long wheelbases (350 SD and 350 SDL).


First Series (1979–1985)

The automatic transmission had four speeds with direct drive in the fourth gear for the entire run from 1979 to 1991. The 280S, 280SE, and 280SEL had 4-speed manual transmission as standard with 5-speed manual and 4-speed automatic transmissions as extra-cost options.

The manual transmission was not fitted to the V8 engines during the first series.

U.S. models, including the 300SD Turbodiesel, had automatic transmission as sole transmission choice.

Second Series (1985-1991)

From 1986 onward, the automatic transmission was revised to include the option of selecting S (Standard) and E (Economy) shifting points. The models, 260SE, 300SE, and 300SEL were fitted with standard 5-speed manual and optional extra-cost 4-speed automatic transmissions. For one year from September 1986 to June 1987, extra cost automatic transmission option wasn't offered for 260SE and 300SE. The customers ordering 420SE could choose either 5-speed manual or 4-speed automatic transmission. U.S. models had automatic transmission as sole transmission choice.

U.S. Grey Import Market[edit]

Grey-market Mercedes-Benz 500 SE

From its introduction in the United States in late 1980, Mercedes-Benz offered Americans only the smaller 3.8-litre version V8, to address the 1975 US federal Corporate Average Fuel Economy (CAFE) requirements [13] and fuel mileage concerns related to the 1979 oil crisis. The smaller 380 V8, allowed Mercedes to avoid a CAFE penalty in the United States. This Malaise era car was severely underpowered, with 0-60mph acceleration in a leisurely 11 seconds and a modest top speed of 117 mph (188 km/h). [11] [12]

American consumers increasingly demanded the more powerful 5.0-litre 500 SE/SEL/SEC models. Their performance was an amazing revelation in comparison, with 0-60mph acceleration in 7.3 seconds and a top speed of 138 mph (222 km/h). [14] The result was about 22,000 Mercedes-Benz W126 vehicles were imported by individual United States citizens as grey market imports. [13] In 1988, the U.S. Congress eliminated this option. [15]

Special variants[edit]

Mercedes-Benz W126 six-door stretch limousine
  • AMG offered body kits for all W126 models, as well as a widebody kit for the coupé. AMG also offered many levels of engine tuning, but was most famous for the DOHC 6.0-litre engine, based on the original 117.968 engine. Also offered was a Gleason Torsen differential in varying ratios, manual transmission (extremely rare), and various TV/radio consoles.
  • Trasco Bremen offered a stretch limousine version called the "1000 SEL".[16]
  • A variety of coachbuilders offered convertibles based on the SEC (coupé) model. Caruna of Switzerland also offered a full four-door convertible based on the SEL (but using the SE's shorter rear doors). One of these still belongs to Dutch Royal Family, who use it at their resort in Porto Ercole, Italy.[17]
  • Like the current model S-Guard, specially modified W126 S-Class models were produced for the transport of dignitaries and world leaders. Among the modifications made included a wheelbase stretch, bulletproof glass, and armored body panels.


Two AMG-modified 500 SEC cars raced at the 1989 24 Hours of Spa. Both cars failed to finish, with one suffering gearbox issues, while the other had issues with the rear axle.[18]


The W126 model 300 SD received the 1981 Motor Trend Import Car of the Year. The W126 model 380 SE was the Wheels Magazine Car of the Year in 1981,[6] the W126 was awarded the U.S. Highway Loss Data Institute "Safest Passenger Car of the Year" in 1988 and 1989,[2][unreliable source?] and the W126 was the third-ranked luxury vehicle in J.D. Power's 1990 Initial Quality Survey (IQS).[19] From 1987 to 1990, Mercedes received the highest customer ratings in the J.D. Power Sales Satisfaction Index.[20]


The W126 series was the highest volume S-Class on record in terms of production. Three armoured 560 SEL ordered by Saddam Hussein had a series of pipes shooting the flames out of sides.[21]

A limited number of W126 continued to be produced in South Africa until 1994, three years after the introduction of W140 S-Class. No figures were given for South African production. Nelson Mandela was given a commemorative model, a red 500 SE. His 500 SE was the last W126 assembled in South Africa and with components donated by Mercedes-Benz South Africa.[22]

Technical Data[edit]

First Series, 1979-1985