Mercedes-Benz_W126

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Mercedes-Benz W126

For a complete overview of all S-Class models see Mercedes-Benz S-Class.

The Mercedes-Benz W126 was a series of flagship vehicles manufactured by German automotive marque Mercedes-Benz. Premiering in September 1979 as the successor to the earlier W116 line, the W126 was the second generation of the Mercedes-Benz flagship to officially bear the S-Class name referring to Sonderklasse or "special class." The W126 was initially offered in straight-6, V8, and turbo diesel sedan models. In September 1981, 2-door coupé versions of the W126 were introduced. Compared to its predecessor, the W126 was more aerodynamic, fuel efficient, capacious, and powerfully engined. The W126 S-Class debuted a new Mercedes-Benz design style which was subsequently used on other vehicles in the company's lineup. The W126 line also introduced many notable Mercedes-Benz safety innovations, including the first airbag supplemental restraint systems, seatbelt pretensioners, and traction control.

The W126 had a twelve year production run between 1979 and 1991, the longest of any S-Class generation since the flagship models were first built in the mid-1950s. The different body styles of the W126 S-Class achieved a combined sales total of 892,123 units (818,063 sedans and 74,060 coupés), making the W126 the most popular S-Class ever produced.

History

Following the debut of the 1970s generation W116 (which also included the flagship Mercedes-Benz 450SEL 6.9), Mercedes-Benz began plans for the next-generation S-Class model. Codenamed "project W126," the project had specific goals: an improved ride, better handling, and improved fuel efficiency. These improvements were aimed at helping retain the S-Class' market leadership as the world's best-selling prestige luxury sedan. Following the 1970s oil crisis, Mercedes-Benz had made fuel efficiency an especially pertinent goal (named "Energy Program"), even in the large V8 engined versions of the S-Class.

In terms of the body design, the objective of the W126 design team, led by Mercedes-Benz's Bruno Sacco, was to produce a car that was sleeker and more aerodynamic (and thus lighter and faster) 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. The maximum speed was also increased (250 km/h in the most powerful model).

After six years of development, the W126 was formally introduced at the Internationale Automobil-Ausstellung (International Motor Show, or IAA) in Frankfurt on September 1979. The initial lineup featured seven models in standard (SE, SD) and long (SEL, SDL) wheelbase sedan body styles: the 280 SE/SEL, 380 SE/SEL, 500 SE/SEL and 300 SD. Technically, the long wheelbase (SEL) variants were codenamed V126, but this was not popularly known. In 1981, the coupe version (SEC) 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.

Four years after the introduction of the fuel-efficiency "Energy Program," the model range had been reworked completely. In September 1985, again at the IAA in Frankfurt, the reworked model range was reintroduced. Apart from visual changes to the bumpers, side covers and alloys, the changes made to the available collection of engine variants was most visible. Two newly-constructed 6 cylinder engines and a new 4.2L V8 were added, and other engines were further upgraded.

The W126 generation was replaced by the W140 in 1992, although a satellite factory in South Africa is known to have continued production until 1994.

Styling

The W126 S-Class premiered the next generation of Mercedes-Benz car styling, which came to dominate the lineup in the 1980s. Because the appearance differed from the rest of the Mercedes-Benz fleet at that time, some people did not appreciate the design at its debut. Compared to its predecessor, the W116, the new model had a sleeker, lower profile look, with more aerodynamic qualities than before (drag coefficient of Cd 0.36 for the sedans, 0.34 for the coupés). For the first time, a Mercedes-Benz sedan was not equipped with traditional chrome bumpers; polyurethane deformable bumpers were used, and visually aligned with body panels.

The interior featured pleated leather on the doors, woodgrain trim on the center console and across the dash, and a simplified layout with symmetrically placed buttons.

The W126 S-Class carried the following general dimensions: length (sedan), (coupe); width (sedan), (coupe); height (sedan), (coupe), wheelbase (sedan), (coupe).

Models

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 (coupe), and diesel models.

W126 (1979-1985)

Chassis code	Years	Model	Engine	Market
W126.021	1981-1985	280 S	M110.924 2.8L straight-6 carburetor	World excluding US
W126.022	1981-1985	280 SE	M110.987 2.8L straight-6	World excluding US
W126.023	1981-1985	280 SEL	M110.987 2.8L straight-6	World excluding US
W126.12	1981-1985	300 SD	OM617.951 3.0L straight-5 diesel	USA and Canada only
W126.032	1984-1985	380 SE	M116.963 3.8L V8
W126.033	1981-1983	380 SEL	M116.963 3.8L V8
W126.043	1982-1983	380 SEC	M116.963 3.8L V8
W126.036	1984-1985	500 SE	M117.963 5.0L V8	World excluding US & Aus
W126.037	1984-1985	500 SEL	M117.963 5.0L V8	for US and Canada '84 and '85
W126.044	1984-1985	500 SEC	M117.963 5.0L V8	for US and Canada '84 and '85

W126 (1986-1991)

Chassis code	Years	Model	Engine	Market
W126.12	1986-1991	260 SE	M103.941 2.6L straight-6	World excluding US & Australia
W126.024	1988-1991	300 SE	M103.981 3.0L straight-6	'89-'91 US
W126.025	1988-1991	300 SEL	M103.981 3.0L straight-6	'88-'91 US
W126.125	1986-1987	300 SDL	OM603.961 3.0L straight-6 diesel
W126.134	1991	350 SD	OM603.97 3.5L straight-6 diesel
W126.135	1990-1991	350 SDL	OM603.97 3.5L straight-6 diesel
W126.034	1986-1991	420 SE	M116.965 4.2L V8	World excluding US
W126.035	1986-1991	420 SEL	M116.965 4.2L V8
W126.046	1986-1991	420 SEC	M116.965 4.2L V8	World excluding US
W126.036	1986-1991	500 SE	M117.965 5.0L V8	World excluding US
W126.037	1986-1991	500 SEL	M117.965 5.0L V8	World excluding US
W126.044	1986-1991	500 SEC	M117.965 5.0L V8	World excluding US
W126.038	1986-1991	560 SE	M117.968 5.6L V8	n/a in US, Australia
W126.039	1986-1991	560 SEL	M117.968 5.6L V8
W126.045	1986-1991	560 SEC	M117.968 5.6L V8

Production figures

Saloon models

Model	Cal. Years	Built
260 SE	1985-1991	20,836
280 S	1979-1985	42,996
280 SE	1979-1985	133,955
280 SEL	1980-1985	20,655
300 SE	1985−1991	105,422
300 SEL	1985-1993	40,956
380 SE	1979-1985	58,239
380 SEL	1980-1985	27,014
420 SE	1985-1991	13,996
420 SEL	1985-1991	74,017
500 SE	1979-1991	33,418
500 SEL	1980-1991	72,733
560 SE	1988-1990	1,251
560 SEL	1985-1991	75,071
300 SD	1980-1985	78,725
300 SDL	1986-1987	13,830
350 SD	1990-1991	2,066
350 SDL	1990-1991	2,925

Coupé models

Model	Cal. Years	Built
380 SEC	1981-1985	11,267
420 SEC	1985-1991	3,680
500 SEC	1981-1991	30,184
560 SEC	1985-1991	28,929

Features

Novel luxury features/options included the following safety, comfort, and technological features. Whilst almost all of these features are available on modern luxury cars today, each in its own right was considered very significant in the 1980s. The harmonious and "matter-of-fact" way which these were combined, as well as their renowned durability, has added to the appeal of W126.

Safety

Airbags, as an additional measure of occupant protection. The driver side airbag premiered on 1981 models, as an optional extra (standard from 1985 on 500 SEL and 500 SEC), and the passenger side airbag premiered in 1986 (as an optional extra; due to its expense, few early production W126 cars were thus equipped). The passenger side airbag became standard in 1991 during the models final year.
Traction control system (TCS), also known as Acceleration Slip Regulation (ASR) to prevent wheelspin (a Mercedes-Benz first). Available on European models only until the year 1990, when it was available to 560 SEL customers in the United States.
Seat belt pretensioners ETR enabled all seat belts (with exception of rear centre lap belt on sedans) to tighten when the car sensed conditions that could lead to an accident (such as sudden, forceful braking).
Anti-lock braking system (ABS) (as introduced by its predecessor, the W116) was optional until 1986 except on premier 500SEL and 500 SEC models.
Crumple zones which absorbed impact energies, reducing passenger injury.

Comfort and convenience

Courtesy lights on the underside of the doors, to enable the occupant to see the ground when exiting the vehicle in the dark. And on sedan models, individual, rear cabin reading lamps aimed at the rear seat occupants' laps so as to avoid distracting the driver at night.
Eight-way powered, dual stage heated front seats, with two setting memory functions for both front occupants to retain positions of power adjustable steering column and seat position for driver; and seat position for front passenger. The seat heaters were standard on the 560 SEL, and an option on other models.
Two-way powered, dual stage heated rear "Chesterfield" bench seat (pre 1990 SELs) with four-way manually adjustable rear headrests that was standard on flagship 500 SEL and 560 SEL models.
As an option on the 500 SEL and 560 SEL, individual, power adjustable rear seats were provided with a burl walnut grained centre console that replaced the centre seat to allow for a 2 + 2 seating format.
Fully automatic climate control system that used an interior temperature sensor to more accurately climatize the cabin. This sensor was mounted near the sunroof so that when the roof was ajar, the sensor would detect cool windchills and call upon the system to adjust heat flow accordingly.
Exterior temperature sensor with display set in main instrument console below the speedometer to inform the driver of exterior conditions.

Drivetrain technologies

Four-speed automatic transmission with a topographical sensor that monitored the vehicle's position (whether on an incline or decline) and gas pedal position. The result was an extraordinary capacity to "hold back" acceleration when coasting downhill and to maintain the S-Class' position without using the brake pedal after coming to a complete stop on a steep incline. The transmission also featured a "limp home mode" in case of electronic failure and was programmed to start in second gear so as to permit smooth, wheel spin free launches. Second gear start could be switched on and off in European models with a S/W switch to allow more performance orientated driving versus winter driving.
The W126 carried forward the self-leveling hydropneumatic suspension of the 6.9 W116 model. There were two versions of the self-levelling suspension for the sedan: a rear only hydraulic suspension using two nitrogen ballasts to automatically level the car, and a four-wheel hydraulic levelling system that could be set in three positions. The coupes were only available with the rear-levelling from the factory. In the US, rear-levelling was standard on both the 560 SEC and the 560 SEL, and optional on the 500 SEC and SEL.
Cruise control that used the transmission's topographical sensor to appropriately add and cut back the throttle fluidly as needed in order to maintain the desired set speed. The result was a cruise control that was free of the sudden throttle inputs and undesired downhill excess speed that plagued many current cruise control systems.

U.S. grey market models

500 SEL

The 500 SEL has an interesting place in US history, since American demand for this particular car drove the establishment of a large grey market. The detuned, yet very expensive US specification 380 SE/SEL/SEC was underpowered, according to contemporary reports, and fuelled demand for the more powerful version available in the rest of the world. Approximately 22,000 units per year of grey market Mercedes-Benz (including the 500 SE/SEL) were sold in the early 1980s, according to contemporary reports in the Los Angeles Times.

Problem models

350 SD/SDL

Some engines had a design defect which causes ovaling of cylinders' walls, bent rods, excessive oil consumption (1 quart per 200 miles or one litre per 300 kilometres is not uncommon), and eventually engine failure. Mercedes-Benz did not accept responsibility for this defect, even when problems arose before warranty terms were met. Most of these engine failures have so-far occurred on vehicles driven under high load or city driving, while highway driven engines do not show signs of problems until many miles later, if at all. Fixing the problem can cost the owner more than $10,000 or 8000€ which exceeds the value of the car. All 350 SD/SDL's will develop this issue, but will not reoccur after being repaired, therefore a thorough pre-purchase check by a qualified mechanic can give the potential buyer a better idea of what they are getting into. Some 350s have gone well over , problem free.

380 SE/SEL

Following the fuel crisis, part of the programme was to reduce weight and increase power with decreased engine weight. On early versions of the 380, the engines came with a single row timing chain. These models were plagued with chain failure problems and some of the problems were corrected by Mercedes-Benz, free of charge. Some models, however, escaped retrofit and may at some point fail as a result. All models built in 1985 were equipped with the dual-row chain from the factory.

The reason for the susceptibility of a single row chain on this engine is because of the intricate rails and tensioner design, along with the two tall cam towers the chain must circulate around. Simple single cam engines generally do not have these problems when using a single belt.

Special variants

Popular tuners

AMG, offered Bodykits for all W126 models, as well as a widebody kit for the coupe. 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.
Brabus, Offered Body kits Similar to the AMG package and engine tuning.
Lorinser, Offered Body kits Similar to the AMG package and minor engine tuning.
Koenig Specials, offered a famous widebody kit, a supercharger, and twin-turbo kits.
MKB, offered various engine kits
RennTech, offered most of the AMG engine tuning packages except for the DOHC engine.
Carat, body kits, wooden seatback trays, wood trim, AMG installer/dealer.

Armored models

Like the current model S-Guard, specially modified W126 S-Class models were produced for the transport of diginitaries and world leaders. Among the modifications made included a wheelbase stretch, bulletproof glass, and armored body panels.

Engines

In September 1985, two newly-constructed 6 cylinder SOHC engines, M103 (already used in the new middle class Mercedes-Benz W124 series), replaced the 2.8 litre DOHC M110 engines. The carburetted version was replaced by a 2.6 litre fuel injection engine, while the 3.0 litre version replaced the fuel injected M110. Also new was a 4.2 litre V8 engine, designed to replace the 3.8 litre version used in the W126 sedans, coupes, and the SL-Class. The 5 litre engine was modified to receive electronic ignition and electronic-mechanical fuel injection in form of the Bosch KE-jetronic system. Performance was increased to . An ECE version of the 5 litre M117 V8 engine was also available from September 1987 with a power output of

The most spectacular new engine was the 5.6 litre V8 that was a further development from the 5 litre version. An increased stroke meant it could turn out a hefty . There was a higher compression version available, if required, that produced some . This version was only available without catalytic converter. But even without the catalytic converter this ECE version, as it was known, would meet the emission requirements of the European community.

A 3.0 litre inline 5 cylinder turbo diesel was offered from 1981-1985 in North America. They are known for covering many hundreds of thousands of miles with few problems. In 1986 the 300SD was replaced with the 300SDL. It was simply a stretched version of the 300SD but the 5 cylinder engine was replaced with a new inline 6 cylinder which improved power and put some of the sluggishness of the previous diesel away.

Engine	Cyl.	Power	Torque	0-100km/h	Maximum speed	Notes
2.6 12V	I6					From MY 1986
2.6 12V*	I6					From MY 1986
2.8 12V carb.	I6			11.0s		MY 1980-1985
2.8 12V inj.	I6			10.0s		MY 1980-1985
3.0 12V*	I6					From MY 1986
3.0 12V	I6					From MY 1986
3.8 16V	V8					MY 1980-1981
3.8 16V	V8			9.3s		MY 1982-1985
4.2 16V*	V8					MY 1986
4.2 16V	V8			9.0s		MY 1986
4.2 16V*	V8			8.3s		From MY 1987
4.2 16V	V8			8.1s		From MY 1987
5.0 16V	V8			8.0s		From MY 1986
5.0 16V	V8					MY 1980-1981
5.0 16V	V8			8.1s		MY 1982-1985
5.0 16V	V8			7.6s		MY 1986
5.0 16V*	V8					MY 1986
5.0 16V*	V8			7.5s		From MY 1987
5.0 16V	V8			7.3s		From MY 1987
5.6 16V*	V8			7.6s		MY 1986
5.6 16V*	V8			7.2s		From MY 1987
5.6 16V	V8					MY 1986
5.6 16V RÜF	V8					From MY 1987
5.6 16V ECE	V8			6.9s		MY 1986/87
3.0 TD	I5			16.0s		MY 1980-1985
3.0 TD	I6			13.0s		MY 1986/87
3.45 TD	I6			13.0s		MY 1990/91

Note: * = Catalyst version

Awards

The W126 S-Class was a champion in the luxury car market, dominating worldwide sales during its production run. At the same time, it also achieved several awards during its production period:

Car of the Year. The W126 model 380 SE was the Wheels Magazine Car of the Year in 1981.

Safety. The W126 was awarded by the U.S. Highway Loss Data Institute as the "The Safest Passenger Car of the Year" in 1988 and 1989.

Customer satisfaction. In 1987, 1988, 1989, and 1990, with the W126 S-Class leading its sales, Mercedes-Benz received the highest customer ratings in the J.D. Power Sales Satisfaction Index.

Legacy

The W126 S-Class, the most successful production S-Class in history, has secured a place as one of the most well-remembered luxury vehicles--described by some as a "classic." Its twelve-year production run was longer than any S-Class before or since, and following the debut of the W140 S-Class in 1991, the additional two years of production in South Africa was a testament to the W126's popularity in the export market. Although an expensive car to maintain, mostly due to the increased expense of Mercedes-Benz replacement parts, a late model W126, if properly driven, can still be a viable proposition today. Many W126s have been prominently featured in films long after production ended.

This legacy stands in contrast with the W140 chassis which had very complex accessory systems, particularly the W140 HVAC system, electrical wiring (due to the push to manufacture environmentally friendly plastics), and auto-door closing features. Among actual owners, W126s are known for their simple maintenance, straight forward problems diagnosis, and long term reliability. It is one of the last Mercedes-Benz models that was still easily maintainable and repairable by owners.