The Mercedes-Benz W126 is a series of passenger cars made by Daimler-Benz AG. It was marketed as the second generation of the Mercedes-Benz S-Class, and manufactured in sedan/saloon (1979–1991) as well as coupé (1981–1990) models, succeeding the company's W116 range. Mercedes-Benz introduced the 2-door C126 coupé model, marketed as the SEC, in September 1981. This generation was the first S-Class to have separate chassis codes for standard and long wheelbases (W126 and V126) and for coupé (C126).

Over its 12-year production (1979–1991), 818,066 sedans/saloons and 74,060 coupés were manufactured, totaling 892,126 and making the W126 by far the most successful generation of S-Class to date, because it is the longest in production.

History

After the debut of the W116 S-Class in 1972, Mercedes-Benz began preparing for the next generation S-Class, in October 1973. The project, code-named "Project W126", aimed to provide an improved ride, better handling, and improved fuel efficiency. The 1973 oil crisis and increasingly stringent emission and safety regulations in the United States influenced the development of the W126, leading to reduced emissions and improved fuel efficiency.

The W126 design team, led by Mercedes-Benz's chief designer Bruno Sacco, aimed to design a more aerodynamic shape and retain the unmistakable S-Class design elements. The aerodynamic drag was reduced through lengthy wind tunnel testing and reshaping of the front end and bumper along with hiding the wipers underneath the hood/bonnet for smoother flow. Reducing the weight was accomplished by extensive use of high-strength low-alloy (HSLA) sheet and polyurethane deformable material for bumpers and side claddings. The lighter alloy material was used for the heavily revised M116/M117 V8 engines for reduced weight. Both contributed to the reduction of fuel consumption by 10% as compared to its predecessor.

After six years of development, the W126 was introduced at the IAA Frankfurt in September 1979. At the introduction, S-Class was available in two wheelbase lengths (standard and long) and three petrol engine options with one six-cylinder inline engine and two V8 engines. The diesel engine option was introduced in September 1981 exclusively for the North American market.

At the 1981 IAA Frankfurt, the C126, a coupé version of the S-Class, was introduced with 380 SEC and 500 SEC trims initially offered. It was the first time that a coupé version was derived from an S-Class chassis. However, the styling was different between the two, making it the first time that the coupé had fully distinct styling, later evolving into CL-Class. Carrying on the tradition of past Mercedes coupé models, the C126 featured a pillarless design with no B pillar between the front and rear side windows. At the same time, the "Energiekonzept" (Energy Concept) was introduced to improve the fuel efficiency of S-Class through engine revisions.

The W126 was revised in 1985 for the 1986 model year. The revised "Second Series" model range was introduced at the 1985 IAA Frankfurt with new six-cylinder petrol and diesel engines and the V8 petrol engines enlarged to 4.2 and 5.5 litres. The 5-litre V8 was carried over. Visual changes included smoother bumpers and side claddings, revised "Gullydeckelfelge" (German for manhole-cover wheel rim) alloy wheels, and a deeper front bumper with integrated air dam.

The W126 generation was replaced by the W140 in 1991.

Styling

From 1973 to 1975, Mercedes-Benz designers worked on the successor to the W116. After several design concepts were presented, the final design for the W126 was approved and frozen in 1976. The design work for the coupé began immediately after the approval and was finalised in 1977. Design patents were first filed on 3 March 1977 and later on 6 September 1977 at the United States Patent Office.

Compared to its predecessor, the W116, the W126 featured improved aerodynamics with a drag coefficient of Cd 0.36 for the sedan/saloon and 0.34 for the coupés.

Models

The pre-facelift model range (1979–1985 for sedan/saloon and 1982–1985 for coupé) included the 280 S/SE/SEL, 300 SD (North American market only), 380 SE/SEL/SEC, and 500 SE/SEL/SEC. The revised second series (1986–1991) with petrol engines included 260 SE, 300 SE/SEL, 420 SE/SEL/SEC, 500 SE/SEL/SEC, and 560 SE/SEL/SEC. The updated version of the diesel model, 300 SDL, was exclusive to the North American market (the first time the S-Class with diesel engine was offered in long wheelbase) and then the 350 SD/SDL (the first diesel S-Class to be available in both wheelbase lengths).

Safety

Use of high-strength low-alloy (HSLA) sheet 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). It was an optional extra for all models and engines until late December of 1984 when it was made standard for the V8 models.380 SE / W 126 E 38, 1980 - 1985|https://mercedes-benz-publicarchive.com/marsClassic/en/instance/ko/380-SE--W-126-E-38-1980---1985.xhtml?oid=4855500 SEL / V 126 E 50, 1980 - 1985 Chassis and Drivetrain|https://mercedes-benz-publicarchive.com/marsClassic/en/instance/ko/500-SEL--V-126-E-50-1980---1985.xhtml?oid=4846 Anti-lock braking system (ABS) became standard equipment in September of 1986 for the 260 SE,260 SE / W 126 E 26, 1985 - 1991 Chassis and Drivetrain|https://mercedes-benz-publicarchive.com/marsClassic/en/instance/ko/260-SE--W-126-E-26-1985---1991.xhtml?oid=4993 300 SE300 SE / W 126 E 30, 1985 - 1991 Chassis and Drivetrain|https://mercedes-benz-publicarchive.com/marsClassic/en/instance/ko/300-SE--W-126-E-30-1985---1991.xhtml?oid=4981 and 300 SEL.300 SEL / V 126 E 30, 1985 - 1991 Chassis and Drivetrain|https://mercedes-benz-publicarchive.com/marsClassic/en/instance/ko/300-SEL--V-126-E-30-1985---1991.xhtml?oid=4982 Anti-lock braking system (ABS) was standard in the U.S spec 300 SDL,300 SDL Turbodiesel / V 126 D 30 A, 1985 - 1987 Chassis and Drivetrain|https://mercedes-benz-publicarchive.com/marsClassic/en/instance/ko/300-SDL-Turbodiesel--V-126-D-30-A-1985---1987.xhtml?oid=4991 350 SD350 SD Turbodiesel / W 126 D 35 A, 1990 - 1991 Chassis and Drivetrain|https://mercedes-benz-publicarchive.com/marsClassic/en/instance/ko/350-SD-Turbodiesel--W-126-D-35-A-1990---1991.xhtml?oid=4987 and 350 SDL.350 SDL Turbodiesel / V 126 D 35 A, 1990 - 1991 Chassis and Drivetrain|https://mercedes-benz-publicarchive.com/marsClassic/en/instance/ko/350-SDL-Turbodiesel--V-126-D-35-A-1990---1991.xhtml?oid=4990 Seat Belt Pretensioners enabled all seat belts (with exception of rear centre shoulder belt on sedan/saloon) 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/C107, was carried over. The fluted design maintains the visibility of taillamps when the dirt accumulates on the outer edges. Airbags The driver's side airbag was introduced in 1981 as an extra-cost option for all models and engines. The consumers could either choose driver's airbag only or driver's and passenger's airbags. For the US market, the driver's side airbag became standard for the 1985 model year1985 Mercedes-Benz 500 SEC | Retro Review Show 406 | Original Airdate 10-16-1984|https://www.youtube.com/watch?v=ZIBS0ep420QRoad & Track, March of 1985|https://www.germancarforum.com/threads/ams-test-40-year-celebration-of-mercedes-500sel-w126.60145/post-1468627 onwards. From September 1987 on, the passenger's side front airbag were added as extra-cost option for the 1988 model year. The passenger's front airbag was an extra cost option until 1989 when it 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). This feature was available on European models only from 1989 and 1991 and on North American models (560 SEL and 560 SEC) for 1991 only. A third brake lamp in the centre of rear windscreen was federally mandated in the United States from 1986 model year on. In some markets, it was offered as standard or extra-cost option.

Comfort and convenience

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 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 the world's first 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 for adjusting the seat back; another switch resembling the seat 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.