Mercedes-Benz W140

1991-1993 S-Class (W140) Pre-Facelift

1994–1998 S-Class (W140) Facelift

The development on the W140 began in 1981, with official introduction originally set in September 1989. Several different design proposals were studied from 1982 until 1986, when a definitive design proposal by Olivier Boulay was selected on 9 December 1986. Several engineering prototypes were evaluated from early 1987, with the final exterior design locked in September 1987. The design patents were filed on 23 February 1988 in West Germany and 23 August 1988 in the United States.[4] The lead designer Bruno Sacco attributed Jaguar's XJ40 sedan and BMW's E32 7-Series as a major influence in W140 design.[5][6] The initial exterior design proposal called for the two different cooling grille designs to denote the lower and upper model, similar to the idea of round and rectangle headlamps on the W123 (1976-1985). Innovative metal-forming technology allowed the extension of the engine hood/bonnet to the front bumper, with the grille placed inside the extruded metal. The W140 became the second model after the R129 (1989-2001) to have this extruded metal grille.

When BMW introduced a new 7-Series (E32) in 1986, the first post-war German passenger V12 engine, M70, was offered. This surprise announcement forced Mercedes-Benz to delay the introduction of the W140 by eighteen months to 1991. The delay allowed Mercedes-Benz to develop the new V12 engine and to rearrange the engine bay to accommodate the gargantuan V12 engine along with upgrading the brake system. The final development prototypes were completed in June 1990, with pilot production models being built from June 1990 to January 1991.

The project cost overruns and eighteen-month delay resulted in the departure of Wolfgang Peter, Mercedes-Benz' chief engineer.[7] The price of a W140 was considerably higher than its predecessor, the W126, (up to 25 per cent) leading to slow sales during the recession of 1990-1994.

The slow sales of the W140 can also be attributed to the wave of Japanese luxury cars that were introduced before the W140 was launched; while the base price of a six-cylinder 300SE was $71,500 in 1992, the Lexus LS400 started at $44,300, the Infiniti Q45 started at $43,600, and the Acura Legend started at $28,800. This led many prospective W140 buyers to switch to its competitors, due to their lower prices, lower maintenance costs, better reliability, and in the case of the LS400, an ownership experience that was just as good, if not better than its European competitors.

As a result of the price increases and stiff competition, Mercedes-Benz shifted from "engineer's design" to "market-driven design" in the 1990s. Many enthusiasts argue that the W140 was the "last true S-class," as its successor, the W220, was criticized for having inferior engineering, and in the case of early models, poor reliability.

Two engines, a stillborn V16 engine based on an elongated V12 engine and an 8.0 W18 engine[8] meant for a hypothetical 800 SEL/S 800 were, again, developed in response to the purported rumour of BMW exploring a V16 engine and testing it in a 7-Series (E32) mule, named Goldfisch V16. The W18 did not proceed past the blueprint stage, but Mercedes-Benz had a small fleet of 85 W140 prototypes with V16 engines. Due to the increasing concern for climate protection and fear of sending a wrong message to the public in the early 1990s, the V16 engine was quietly cancelled.[9]

In March 1994, the updated W140 was unveiled at the 1994 Geneva Auto Salon and went on sale in April 1994.

In 1995, the two tone exterior appearance was made to be monotone, low-beam xenon headlamps were added and the rear indicator lenses became clear. The change were later was introduced in June 1996 as 1996.5 models in Europe and 1997 models in the United States.

The W140 received notoriety in 1997 when Diana, Princess of Wales died in a car crash, involving an S 280 model, in a Paris tunnel.[10][11]

The three body types are carried over from the W126: four-door sedan/saloon in two wheelbase lengths and one two-door coupé. The model types are assigned as W140 for standard wheelbase, V140 for long wheelbase, and C140 for coupé. In 1996, S-Class coupé was renamed as CL-Class and spun off from S-Class. A longer Pullman version with 4140 mm wheelbase was introduced in 1995 with two engine choices (S 500 Pullman and S 600 Pullman). The S 600 Pullman could be ordered with armour package.

The Sultan of Brunei ordered eighteen S 73 T station wagons/estates with AMG-prepared M 297 7.3-litre V12 engines putting out 391 kW (532 PS; 524 hp) and 750 N⋅m (553 lb⋅ft) to be built, with ten units delivered. The S 73 T had an S-Class coupé front end and the rear part of an S210 station wagon/estate installed, and rear lights of S-Class sedan.[12]

A one-off custom-built S 500 lang Landaulet Popemobile was built for Pope John Paul II in 1997.

For the W140 series, a new generation of inline-6 and V8 petrol engines was developed with double-overhead camshafts (DOHC), four valves per cylinder, and new variable valve timing. Mercedes-Benz's first passenger V12 engine was introduced in 1991 in a response to BMW's 750i/750iL (E32). Only the 3.5-litre inline-6 diesel engine, OM 603.97x, was carried over from W126, and it remained the only engine in the W140 model range with a two-valves-per-cylinder format until its replacement in 1996. The advent of DOHC, with four valves per cylinder and accompanied by variable valve timing, helped to increase the horsepower and torque figures without imposing a heavy fuel-consumption penalty, all while reducing emissions. All petrol engines were equipped with catalytic converters during the entire W140 model run, regardless of where they were sold.

M 104 petrol engine was introduced in 1992 with two displacements: the smaller 2.8-litre M 104.94x engine was fitted to 300 SE 2.8 (one year only) then S 280 (1994-1998); the larger 3.2-litre M 104.99x engine was fitted to 300 SE/300 SEL (one year only) then S 320 (1994–1998).

The M 119 V8 engines were available in 4.2-litre (M 119 E 42) and 5.0-litre (M 119 E 50) versions and remained unchanged during its entire model run. In 1994, AMG developed a 6.0-litre version (M 119 E 60) with 279 kW (379 PS; 374 bhp) and 580 N⋅m (428 lb⋅ft) in a very limited production for Japanese market. The S 500 AMG 6.0 and CL 500 AMG 6.0 were built from 1994 to 1999 per customer order.[17] For 1993, the V8 engines were detuned for improved emission control.

The M 120 V12 engine was offered in 6.0 litres only for the entire model run. This engine developed 290–300 kW (394–408 PS; 389–402 hp) and 569–580 N⋅m (420–428 lb⋅ft) of torque. The 300 kW (408 PS; 402 bhp) version was available in Europe from 1991 to 1992 and in the United States for 1992 only. In 1993, the V12 was slightly detuned to 290 kW (394 PS; 389 bhp) for lower emission control. An AMG-prepared 6.0-litre M 120 V12 with higher performance rating, 327 kW (445 PS; 439 hp) and 623 N⋅m (460 lb⋅ft), was only available for S- or CL-Class (C140) coupes and not S-Class sedans/saloons.

The 3.5-litre inline-6 diesel engine, OM 603.97x in the 300 SD TURBODIESEL (1991–1993) and S 350 TURBODIESEL (1994–1996) models was offered outside the North American and Japanese markets for the first time. This engine was replaced in 1996 by the entirely new 24-valve OM 606.961 ERE engine. This engine was loosely derived from the M 104 petrol engine, but with a different crankshaft and cylinder head. The smaller engine fitted to S 300 TURBODIESEL put out 130 kW (177 PS; 174 hp) and 330 N⋅m (243 lb⋅ft). The fuel was delivered indirectly in the precombustion chamber before entering the combustion chamber.

W140 remains the only S-Class to have wider range of transmissions during its eight-year run. The transmission choices at the introduction was 5-speed manual and 4-speed 4G-Tronic automatic. A new 5-speed 5G-Tronic was introduced in 1994 for inline 6 petrol engines only. In September 1995, 5G-Tronic was updated with electronic control for more optimal shifting points based on the sensor readings and became the sole automatic transmission option for the entire model range from 1996 to 1998.

The models equipped with inline 6 petrol engines have 5-speed manual transmission as standard with either 4-speed or 5-speed automatic transmission as extra-cost options, making W140 the last S-Class to have manual transmission. In June 1996, both 4-speed and 5-speed automatic transmissions were replaced by 5-speed electronically controlled automatic transmission. The inline 6 diesel engines were never offered with manual transmissions, following the "tradition" with W116 and W126. S 300 TURBODIESEL, introduced in 1996, received the 5-speed electronically controlled automatic transmission.

The models with V8 and V12 engines were offered with 4-speed automatic transmission as standard until August 1995. On September 1995, the 4-speed automatic transmission was replaced by 5-speed electronically controlled automatic transmission.

4MATIC, the all-wheel-drive system introduced in W124 (1985–1996), was never fitted to W140 S-Class. W140's successor, W220, became the first S-Class to have 4MATIC as extra-cost option.

The figures given for acceleration, top speed, and fuel consumption are combination of all types of transmission (5-speed manual, 4-speed automatic, 5-speed automatic, and 5-speed electronically controlled automatic) and three body types (standard, long, and coupé) wherever applicable.