Evolution of the Mercedes-Benz S-Class

_s-class_horizontal_line-up_1.jpgEvolution of the S-Class

The first in a new series of reference guides tracing the development of the current Mercedes-Benz product range by model and chassis number

Article by Richard Simonds, Gary Anderson & Andrew Atwood | Images from Daimler Archive | Illustrations by Stephan McKeown

Over the next several issues, we will be discussing how Mercedes-Benz automobile models have evolved from the end of World War II to the present. The easiest way to understand their characteristics and how they've changed over time is to think about them from the top down, and in groups over time.

The importance of chassis numbers

For Mercedes-Benz, marketing and product development strategies have always included distinct models to match each level of customers' desires. In today's world, the models are S-Class at the luxury level; E-Class for the executive market; C-Class for the general family market; and the most recent addition to the lineup, the A/B-Class, designed as an affordable offering to introduce younger owners to the brand.

Within each of these market levels, the product lines have evolved in response to technological developments, design trends and changing product preferences. Because development of a new model is an expensive proposition, generally requiring three to five years from first specifications to factory production and market introduction, completely redesigned chassis occur only at intervals rarely shorter than five years - intervals can be much longer - with minor changes made during those periods.

At the beginning of a design's development, the chassis series is assigned a code number, in German called the "Wagner" number or "W-number"; that becomes the major reference to the series of models built on that chassis. Until recently, the chassis number was shown as the first three digits of the vehicle's identification number.

To make things more confusing, the chassis numbers assigned do not have any relationship to any series' attribute; nor are they assigned in numerical sequence, which can be a challenging issue for people who are new to the hobby.

During the production period for each chassis series, the practice was to designate models based on the capacity of the engines available with. For example, the 2.2-liter engine in the 1951 W187 defined the car model as the 220.

By 1959, alphabetic characters were being linked to the engine capacity to indicate the models available in that chassis series. For example one of the models in the W111 series was the 220SE, with a 2.2-liter engine, S for sedan and E for fuel injection. In 1993, the naming conventions changed, with models designated by the alphabetic class designation followed by numbers indicating the engine capacity, such as the 1994 S600, with its 6-liter V-12 engine. The practice of linking model designator to engine capacity continued until just very recently.

In this sequence of articles - starting with the luxury S-Class series and its predecessors - perhaps we can demystify these perplexing chassis series codes as we discuss its evolution over the past 65 years.

1951-1954 W187 series

The first cars Mercedes-Benz built after World War II were the 170S sedans on the W136 chassis, essentially carried over from before the War, taking advantage of tools and dies the company had managed to safely store away during hostilities.

Built on the new W187 chassis, the 220 was introduced at the first postwar Frankfurt International Motor Show in April 1951. The W187 chassis used the same prewar design as the W136, with an oval tubular frame in an x-configuration onto which the body was attached. This design was stronger than the typical cross-braced ladder frame used by most manufacturers at that time. However, because there was both a metal chassis frame with body panels consisting of steel panels over ash wood frames, the car was heavy and complex to build.

A few changes were made to update the design from the 170, including integrating the headlights into the fenders for better airflow, and installing more powerful brakes to handle the 80 horsepower produced by the new 2.2-liter 6-cylinder engine. Establishing a practice that would be followed until after the end of the century, the 220 model took its name from the capacity o fthe engine.

Production of the body-on-frame W187' run, a small number of coupes and cabriolets were hand-built on the chassis in an effort to re-establish Mercedes-Benz's reputation as a producer of more stylish automobiles for the affluent customer. Because the company was uncertain about the new Ponton's acceptance, production of the cabriolets and coupes on the W187 chassis continued into 1955.

1954-1959 W180/W105/W128 Ponton series

By 1954, the company had developed the W180 chassis, a completely new unitized body (unibody) chassis in which the entire platform and inner body were stamped and welded into one unit, following an approach developed by a few other manufacturers in the late 1930s. The engine and independent front suspension assembly were fastened to a front sub-frame. A second sub-frame extended rearward to hold the single-pivot rear axle differential assembly adapted from the W196 racecars, allowing each rear wheel to be independently sprung.

The first model built on this chassis, the 220a sedan, was introduced in March 1954 and it immediately gained the nickname "Ponton" due to the more flush fitting and streamlined fenders forming a single visual unit that designers thought resembled the pontoons used in World War II portable bridges.

With a much more contemporary design, smoother ride, better handling, and quieter interior than their predecessors, the new Pontons were a big success. The unibody construction has been used on every Mercedes-Benz sedan since that time - and the rest of the automotive industry soon followed suit.

Expanding the price range to serve less affluent customers, in March 1956 the company introduced a slightly less expensive version called the 219 - built on a slightly modified chassis with engine mounts lengthened to accommodate the longer engine - and designated the W105. When a fuel-injection engine was introduced in September of 1958, the chassis with that engine carried the designation W128.

As with the previous chassis series, the company hand-built 220S and 220SE coupes and cabriolets on the same W180/W128 chassis in limited numbers to draw attention to the marque and attract customers into the showrooms. And with the "Hydrak" semi-automatic transmission, these cars could be very comfortable boulevard cruisers.

1959-1965 W111/W112 Finback series

With their squared fender lines and distinctive tailfins, the W110 and W111 sedans looked different than their Ponton predecessors. Nicknamed "Finback" in the United States and "Heckflosse" in Germany due to the rear fender styling, this chassis series utilized a reworked unibody frame as the basis for models with various engine types. The fintail rear fenders were not as radical as those of some U.S. manufacturers but represented a German approach to being competitive in an important luxury-car market.

Although the earlier ponton models had reinforced body construction to protect passengers in a collision, Béla Barényi designed the new W111 unibody with passive safety systems - especially crumple zones - to protect passengers. One beneficial byproduct of these new crumple zones was the visually distinctive and massive rear trunk area.

The W111 coupes and cabriolets shared the unibody platform but featured rounded rear fenders and other styling cues that presaged the W108 and W109 sedans that followed. They were large cars that could very comfortably hold four or five passengers. The 220SE, 250SE and 280SE coupes and convertibles - especially the 280SE 3.5 with its 3.5-liter V-8 engine - have become collectors' cars.

The W112 models were top-of-the-line sedans, coupes, and cabriolets with air suspension, four-wheel disc brakes with anti-dive compensator (a first in the industry) and the 3.0-liter 6-cylinder alloy-block engine derived from the now-famous 300SL. Production of the sedans on the W111/W112 chassis, with their distinctive rear fenders, ended in 1965 when the New Generation series was introduced. However, because the New Generation series didn't include a two-door model, coupes, and cabriolets built on the W111 chassis would continue to be offered through 1971.

1965-1972 W108/W109 New Generation series

The New Generation sedans introduced in August 1965 were built on the longer W108/W109 chassis required by the new sedans' increased size The W108/W109 models lost their fins and incorporated more rounded fenders and simpler taillight assemblies in an effort to modernize the styling. Nevertheless, they carried on with exactly the same headlight assemblies as the W111/W112 models before them.

Three models were offered - the 250, 280 and 300 - with engine choices ranging from a 2.8-liter 6-cylinder to 3.5- and 4.5-liter V-8s with electronic fuel injection, as well as differing trim levels, to compete in the expanding international luxury market. Some items then being offered as standard equipment included electric power windows, pneumatically operated door locks and air conditioning, as well as electric sunroofs.

A hydro-pneumatic compensating spring on the rear suspension for heavy loads was offered on some of the W108 V-8 models. However, it wasn't needed on the W109 300SE models as the air suspension from the W112 was carried over to it, as well as the four-wheel disc brake system with anti-dive compensators.

In March 1966, an even longer-wheelbase model was introduced - the 300SEL. And in March 1968, the 300SEL 6.3 was introduced, powered by the V-8 engine from the Model 600 Grand Pullman Limousine, feted by the motoring press as "the greatest sedan in the world" and "truly the executive road racer."

1972-1980 W116: The first S-Class cars

In 1972, the company again redesigned its top-of-the-line offerings on the new W116 chassis, and began using the S-Class designation for the first time, though continuing to refer to the line-up with the term "New Generation." Each S-Class model was named for the capacity of its engine, followed by the model designation. The W116 chassis featured the 280S and 280SE with 6-cylinder engines, and a new 350SE with the 3.5 liter V-8. Six months later, the 450SE with its new 4.5-liter V-8 was added to the lineup.

The new W116 chassis had improved safety crumple zones and a ddouble-wishbone front suspension with a steering design that improved handling. Gone was the old swing axle from the W108 and earlier cars, replaced by an all-new trailing-arm independent rear suspension, which inherently provides an anti-dive capability for hard braking. The fuel tank was moved in front of the rear axle for protection in a rear-end collision and for better weight distribution.

The ultra-luxurious 450SEL 6.9 was introduced in May 1975, with its hydro-pneumatic suspension giving full level control for maximum driving comfort, central locking, air-conditioning and an available headlamp washer system. A new anti-lock braking system (ABS) was introduced in 1978, starting a revolution in "active safety" features to complement "passive safety" features pioneered by Mercedes-Benz.

New emissions regulations being introduced in the United States and major European countries required the development of new fuel-injection systems such as CIS (continuous fuel injection). In addition, to meet the needs for higher fuel economy as gasoline prices escalated after the global fuel crisis of 1973, the 300SD was introduced with a turbodiesel engine.

1979-1985 W126 S-Class series

The S-Class on the W126 chassis was the car that indelibly stamped Mercedes-Benz as the luxury car manufacturer to beat in terms of style, performance, and luxury. The company was also the unquestioned market leader in the increasingly important area of passenger safety, developing an impressive array of passive and active safety features. For the first time, a sedan could be involved in a 55 kph (34.2 mph) frontal offset crash with no damage to the passenger cell. Research in metal alloys, redesign of bumpers and side-impact protection, as well as air-bag systems (1981), brought passenger safety - and acclaim for Mercedes-Benz - to a new level.

The W126 series offered seven models with a choice of four engines ranging from a carburetor-fed 2.8-liter 6-cylinder to a fuel-injected, 5.0-liter all-aluminum V-8. Also available in this series was a limousine model with a wheelbase six inches longer than the regular sedan. The company's Energy Concept program instigated the redesign of engines for greater fuel economy and reduced emissions to meet customer demand and legislative mandates.

A striking new coupe was introduced in 1981 on the W126 chassis, firmly establishing the SEC series. This elegant and desirable two-door machine had a wheelbase three inches shorter than the sedan, and featured a powerful 3.8-liter V-8 engine.

1985-1992 Updated W126 S-Class series

Updated in 1985, the improved W126 chassis was not changed significantly, but the bodies were noticeably restyled with improved aerodynamics. Larger brakes were accommodated in 15-inch wheels.

Suspension changes improved handling, and continuing development and refinement of engines increased the luxury and variety of models built on the W126 chassis. New 6-cylinder engines and improved V-8s were available, with the 560SEL and 560SEC reaching the epitome of gasoline-engine development by the end of the series.

Diesel variants, benefiting from continued technical development, also saw reduced emissions, improved fuel economy, and increased longevity. In June 1989, the 350SD and SDL were introduced to critical acclaim. During the W126 series' 12-year production, 818,036 were produced; 97,546 of those had diesel engines. This was the most successful premium-class series in Mercedes-Benz history.

1991-1994 W140 S-Class series

Visually, the W140 chassis series introduced in 1991 was marked by significant changes to the radiator grille and more contemporary body styling. While still incorporating traditional Mercedes-Benz styling features, the new grille was less vertical and bulky and was integrated into the body lines. Electronically, the car was far beyond the competition in that it used a two-wire CAN (Controller Area Network) communication system to minimize wiring, speed up data transfer between control modules and allow different systems to share information. Underneath, new steel and aluminum alloys improved passive collision protection for passengers. The body design also protected other road users. Active safety features included a new double-wishbone front suspension and a multilink rear suspension, improved ABS braking, and speed-sensitive power-assisted steering. Central locking and power windows were standard. Double-glazed sound-proof glass improved acoustic comfort, reduced fogging in extreme cold, provided better heat insulation and improved external airflow, reducing wind noise.

The 140 chassis was powered by a new series of engines, including a 6-cylinder, two V-8s and a 6.0-liter V-12 - all with 4-valves per cylinder and improved drivability and fuel efficiency. In October 1992, the 300SD 3.5-liter, 6-cylinder turbodiesel engine joined the W140 lineup.

Mercedes-Benz changed its naming convention in June 1993 with the class designation letter followed by the model name (e.g., 500SE became S500, 600SE became S600, and so forth).

The 500SEC and 600SEC coupes were introduced in January 1992 and rode on a slightly shortened W140 chassis with a 115.9-inch wheelbase. The coupes were available with every safety and performance feature that was available in the sedans.

1994-1998 Updated W140 series

Other than some typically discreet styling refinements and feature enhancements, there were no major changes to the W140 chassis in the March 1994 update. The electronic Parktronic system with back-up obstacle warning was added in May 1995. In September 1995, technical improvements were made to the V-8 and V-12 engines, and a 5-speed automatic transmission with a torque-converter lock-up clutch was added to W140 sedans after having been introduced in the 500SEC and 600SEC coupes the preceding May. The Electronic Stability Program (ESP) was introduced in September 1995. Brake Assist, a safety system that anticipated emergency braking situations, became standard in December 1996. The diesel version of the updated W140 - an S350 Turbo Diesel - came into the lineup in June 1996.

The S600 Pullan premiered as the official state limousine with a 39-inch longer wheelbase than the S600 LWB. Thus, rear-seat passengers could sit facing each other to facilitate conversation.

The 500SEC and 600SEC coupes benefitted from the engine, transmission and safety changes that were made to the W140 sedans. They also received the same stylistic modifications to the grille, body panels and rear lights that were made to the sedans.

1998 to present

In 1998, the S-Class once again underwent significant changes in design, length, and equipment, signified by a new chassis series number, the W220. In 2005, with relatively few changes made, that chassis was replaced by the W221 chassis series. Models built on the W221 platform continued production until 2013.

A dramatic series of changes were made with the most recent S-Class sedan launched with the 2014 model year, built on the W222 chassis. This chassis is also being used as the platform for Mercedes-Maybach ultra-luxury limousines.


1951-1954 W187


1954-1959 W180/128 Ponton


1959-1968 W111/112 Finback

1964 220SE

1965-1972 W108-109

1972 280SEL 3.5

1972-1980 W116

1980 450SEL 6.9

1979-1985 W126

1982 500SEL

1985-1992 W126 Update

1985 560SEL

1991-1994 W140

1994 S600

1994-1998 W140 Update

1995 S600


1956-1960 W180 Ponton

1958 22SE Coupe

1961-1971 W111/112

1968 220SE Cabriolet

1982-1991 W126

1981 560SEC Coupe

1992-1998 W140

1992 S420 Coupe