| In March 1991 the youngest generation of the S-class (internal designation: construction-series 140) was presented on the Geneva Automobile Salon. The design of the bodywork took as its model the traditional styling elements typical of Mercedes-Benz and, in so doing, became another member of the passenger-car model family designed very homogeneously. Like it was already the case with the SL-types of the construction-series 129, in keeping the traditional basic shape the cooling mask as the characteristic feature of the new S-class was newly interpreted in terms of style. With this variant of a classic topic called ,Plakettenkhler" (,tag radiator") the radiator cowling with its considerably thinner chrome frame was integrated organically into the bonnet, the Mercedes-star was not placed on the radiator's mask but put slightly backwards on the bonnet. Overall the development of the design concept of the new S-class had been aimed at realizing a high degree of aerodynamic quality simultaneaously considering maximum suitability for everyday life.
Like it had been the case with the predecesor models of the construction-series 126 and generations of construction-series of the Mercedes-Benz upper-class, there was - apart from the normal version -a variant with prolonged wheel base and this prolongation by 100 mm only enlarged the rear footwell. As for the engines, four aggregates for the domestic market were available for the time being with only the 5.0-litre V8-four valve-engine M 119 being an old acquaintance. Like in the 500 E, the so-called ,Einheitsdeck-Motor" whose fully electronic injection system Bosch ,LH-Jetronic" was controlled via a hot film air mass sensor was used here. The other three engines had been newly developed: The 4.2-litre four-valve V8-engine had been developed from the time-tested 4.2-litre two-valve -engine according to the model of the 5.0-litre driving unit, and the six-cylinder series-engine with 3.2-litre displacement was based on the 3.0-litre four-valve-engine introduced two years earlier. By the way the following interesting detail should be mentioned: the type designations of the 3.2-litre and 4.2-litre models did not exactly reflect the displacement as it is usua. For reasons of homogeneity the designations 300 SE/SEL and 400 SE/SEL were chosen instead..
A completely new constructed vehicle was the 6.0-litre V12-engine not only representing the first passenger car twelve-cylinder of Mercedes-Benz produced in series but, at the same time, went down in history as the most powerful Mercedes-Benz passenger car-engine with a nominal performance of 300 kW (408 hp). The nominal torque amounted to 580 Nm and exceeded the 500 Nm-limit already at 1,600 r/m. Like the six-cylinder and the two V8-engines the twelve-cylinder was equipped with four-valve technology, inlet camshafts adjustable in operation as well as electronic injection system with hot film air mass sensoring. With all engines the minimization of the pollutant emissions and the fuel consumption was the prime target. The new fully electronic ignition calculates the optimum ignition point from overall 300 ignition maps doing it seperately for each cylinder and adjusted to the knock limit. The M 120 was the only twelve-cylinder-engine in the world to be fitted with this cylinder-selective anti-knock control. This system was absolutely vital to attain the high compression-ratio of 10:1 necessary for an optimized use of consumption..
Completely novel, too, was the engine- and driving management with all controlling modules communicating with one another via a common data channel.. With that the controlling devices can get active together. This is used among other things for the fast heating of the catalytic converters after the cold start of the engine, moreover for the anti-slid control and for the new engine.drag torque control securing the driving stability when the foot is taken off the accelerator even on a slippery road. With a volume of 7 litres the V12 was equipped with the largest catalytic converter-system for passenger cars in the world. It was dimensioned in such a way that the consumption of fuel was not increased an a long-term stability was ensured.. Through a novel concept of double wall and three-layer exhaust manifolds and likewise double wall pipes the ceramic-catalytic converters embedded in a heat insulated soaking mat reached the optimized operating temperature in an extremely short time.
Apart from the exhaust optimization and reduction there were other details in the S-class making it the pioneer of an environmentally compatible automobile production.. The S-class was the first vehicle of the era of the cfc-free automobiles and pointed the way in terms of recycling.: The plastic components were not only completely reusable and clearly marked but, moreover, were already produced in many cases by using regranulate. In the year 1992 the S-class was awarded the environmental prize of the US-American ,Environmental Protection Agency", the "Stratospheric Ozone Protection Award".
Besides the reduction in the consumption of fuel and the optimization of environmental compatibility, perfect comfort and safety were the main aims. Apart from many other factors the careful conception and tuning of the chassis played a part. A newly developed double-wishbone front axle was used as the front wheel suspension. This double-wishbone front-axle was mounted on a chassis sub-frame with its main force-application points in order to attain a decoupling of the bodywork from audible and perceptible vibrations. The rear-wheel suspension was derived from the multilink suspension of the other passenger car's construction-series but basically revised regarding wheel control, and modified corresponding to the special requirements of the S-class. The link geometry was newly designed under consideration of the considerably higher longitudinal and transversal forces, the crossed execution of the upper link is remarkable keeping the axle space small despite the high swing-arm radius.
In terms of active safety the S-class limousines of the construction-series excelled in having an extraordinarily good straight-running stability even on uneven roads, a very low side-wind sensitivity , a precisely working steering as well as the high insensitivity of the driving behaviour with different loads. A basic novelty represented the braking system of the eight- and twelve-cylinder models putting more pressure on the rear wheels. In so doing the stability of the braking system could be raised and the wear-and-tear at the front wheel brakes could be reduced.
The particularly high driving comfort of the S-class was ensured through a considerable reduction of the rolling noises and vibrations that are transferred on the saloon, the minimization of the nodding movements occuring when the driver starts and and brakes, the reduction of rolling and swaying movements when cornering or driving on uneven roads as well as the steering virtually insensitive to impacts. With the eight- and twelve-cylinder variants a so-called ,Parameterlenkung" (,parameter steering") with a speed-sensitive steering-wheel torque was used reducing the steering forces the driver has to apply.when driving slowly, for instance when parking.
Passive safety did not fall by the wayside despite the progress being made in terms of driving comfort and active safety. The high safety-level already attained by the construction-series of the predecessor could still be considerably increased through a whole bunch of measures and, this way, the new bodywork structure offered still more safety in all kinds of accidents. Through a series of solutions in detail for the smoothening of potential contact points the protection of the partner was given more attention. The standard central locking and the electric window lifters which also belonged to the basic equipment ensured a high level of control comfort..It was the double glazed windows used for the first time in a construction-series of passenger cars that contributed in a high degree to the improvement of comfort; they united a whole series of characteristics regarding safety and comfort: Prevention of a fogging and ice formation propensity as well as formation of condensed water, increased heat insulation, increased deadening against outer noise sources, better outer air diversion and prevention of wind noises at the window weatherseals.
Another two design details - outside rear-view mirrors foldable backwards and pop-up backup markers as backup aid - facilitated manoeuvering in narrow and blind circumstances.. The backward-folding of the outside rear-view mirrors driven by an electronic engine to get more space when manoeuvering in restricted situations, was induced by the centrally located switch on the middle console with which also the usual adjusting of the mirror glasses was done. In order to estimate the distance of obstacles when manoeuvering backwards, pop-up backup markers were installed on the right- and left-hand side in the wings in the vehicle's rear. The 65 mm long rods popped up pneumatically in vertical direction 2 seconds after shifting into the rear and were retracted 8 seconds after the renewed change of gear.
In October 1992 on the Paris Auto Salon the types 300 SE 2.8 and 300 SD were presented enriching the programme of the S-class by two variants that were lower in price and particularly economic. The 300 SD caused a great stir: Although having been exported since October 1991 in the U.S.A. it now was available as the first S-class Diesel-model on the domestic market. The SD 300 was driven by 3.5-litre six-cylinder-engine with exhaust-gas turbo charger already known from the predecessor-model of the construction-series 126 but now used in a revised version with 110 kW (150 hp). The second newly presented vehicle, the 300 SE 2.8, like the 300 SE, was fitted with a six-cylinder series-engine with four-valve technology also being part of the motor-family M 104. From the same time onwards, the newly developed 2.8-litre variant was also used in the construction-series 124 and was fitted with a micro-processor-controlled injection system that was no longer regulated by a hot-wire but a hot film air-mass sensor. Apart from the two new models the eight-cylinder and twelve-cylinder types with revised engines were presented in Paris. With all three aggregates people had renounced the mixture enrichment at full throttle entailing a slightly reduced performance but benefitting the exhaust emission behaviour. In June 1993 the type-designations were changed analogous to the construction-series of the passenger-car programme; from now on the ,S" was placed in front of the three-digit figure and the additions like e.g. ,E", ,D" and ,L" were dropped. The 500 SE , as an example, became the S 500, and the 600 SEL was called the ,S 600 lang" (,S 600 long") according to the new nomenclature-system. Since then the type label on the deck lid shows only the class to which the car belongs and the displacement; the variant of the bodywork (normal or long wheel base) which is obvious anyway (at least when looked at it twice) is no longer shown. The clearest changes were made at the type designations of the 4.2-litre types and the six-cylinder models. Instead of the previous figures rounded to whole hundreds for the sake of a uniform appearance, now those figures were used that corresponded to the real number of displacement. Thus, for instance, the 300 SE became the S 320 and the 300 SD became the S 350 turbo-Diesel. Besides the purely formal changes the two 3.2-litre models also benefitted from technical improvements; the hitherto non-accessible engine was replaced by a revised version having already been used in the construction-series 124 since October 1992 and which was now also fitted with a resonance-type switch-over induction system and an injection system with hot film air-mass sensor. In so doing the torque could be increased and the maximums of the performance respectively torque could be shifted to lower speed ranges. In connection with an additional reduction in the frictional power the fuel consumption was reduced by 7.5 per cent. at slightly improved driving performances.
In March 1994 on the Geneva salon the limousines of the S-class were presented slightly revised in terms of styling. A series of changes in detail made for a lighter well proportioned and more dynamic appearance with the same dimensions. This was attained above all through a distinct pulling-in of the lower parts of bumpers and side-protection surfaces as well as a horizontal structure of these surfaces through an all-round running sib..A changed design of the headlights and the radiator grill reinforced this effect. With the modified headlights with optimized free-form reflectors making for an increased light efficiency of 60 per cent., the field of the dipped beam was no longer separated from the main beam through a centre rib thus reaching a widening in the external appearance. Colourless cover glasses of the front direction-indicator lights supported this impression.. The six-cylinder and eight-cylinder models were fitted with a newly designed delicate radiator grid with a vertical ridge in the middle..For the V12-types an own version with chromed transversal lamellas and considerably widened chrome frame was used..A vital role for the harmonic overall appearance of the S-class was the formal revision of the rear end. So the lower radii of the deck lid rebates rounded down analogous to the coup models. The strip of .lamps used up to now was widened in the section under the rear lamps and moulded to the now bichromatically shaped rear lamps. With that the level of the boot was lowered in its external appearance and the rear gave the impression to be wider and lying lower. From May 1995 onwards the ultrasonic parking aid ,Parktronic" could be delivered with which the distance to an obstacle is calculated in an electronic control device by means of ultrasonic signals being reflected by the obstacle. Sender and receiver of the ultrasonic signals are united in sensors being integrated in the front and rear bumpers..The protective function of the bumpers is not affected through this. With the two V12-models the Parktronic has been part of the standard equipment since May 1995. .At the same time the backup markers in the rear wings were dropped at all S-class limousines as they were no longer needed. After the measures for the improvement of the models presented in March 1994 chiefly concerned the design of the vehicles, some technical improvements with the eight- and twelve-cylinder models became effective in September 1995. A completely new developed 5-speed automatic gearbox with converter lockup clutch already being used in the S 600 coup since May 1995, now superseded the 4-speed gearbox with hydraulic steering with the limousines, too. The core of this technical miracle is an electronic control of the gearbox adjusting the shifting of gears fast and autonomously to every driving situation and is permanently in contact with the electronic engine-control for the exchange of data. Besides these novelties pointing the way, the new automatic gearbox is also clearly more compact and lighter than comparable gearboxes with five driving positions. The engines were revised once again for the further reduction of the fuel consumption and the emission of exhaust gases. To this end the two V8-driving units were fitted with a modified crankshaft, an optimized valve control, weight-reduced pistons, direct-fire ignition-coils for every cylinder as well as an improved electronic engine-control of the type Motronic ME 1.0 in which a hot film instead of the hitherto hot-wire air-mass sensor was integrated. The changes in the construction of the V12-engine were not so extensive and only concerned the arrangement of the ignition-coils and the electronic engine-control. As a consequence of the different engine-modifications and the use of the new automatic gearbox, the fuel consumption of the V8- and V12-types could be reduced by 7 per cent. on average, the emission of exhaust gases could even be lowered by more than 40 per cent. at the same performance. Also from September 1995 onwards the ,Electronische Fahrstabilitts-Programm" (ESP) (electronic driving stability programme) was available on request for all S-class models with eight-cylinder engine. This ,ESP" supports the driver by counteracting the unstable moment through a specific brake intervention controlled through a sensor and, this way, contributes to the driving safety. Since then the ESP is part of the standard equipment of the two twelve-cylinder types. Apart from the mentioned measures for the model-improvement presented on the occasion of the IAA in Frankfurt, also a new variant of the S-class made its debut in September 1995: the S 600 lang Pullman having been developed as a new state limousine with special protection technology and, in so doing, was taking up a long-standing tradition at Mercedes-Benz. The specially produced vehicle measures 6,213 mm and, this way, is exactly one metre longer than the S 600 with long wheel base. The prolongation is of benefit to the front passengers sitting on comfortable seats in face-to-face arrangement; the passengers can separate the rear compartment from the driver's section by means of a partition window. The Pullman limousine of the construction-series 140 is available as S 500 and S 600 also without special protection; the first vehicles of both variants were created in August 1996.
According to tradition the normal five-seated limousines of the S-class are also offered in the special-protection-version; you can choose between the models with 5.0-litre V8- and 6.0-litre V12-engine. The production of both special-protection types started in February 1992, one year after the main series of the construction-series 140 was started. In June 1996 the S-class was revalued again. The six-cylinder models, too, were now available with the new 5-speed automatic gearbox with converter lockup clutch and electronic steering - with the S 280 on request, with all other types this was part of the standard equipment. At the same time the anti-slip-control (ASP) was also taken in the basic equipment with the six-cylinder models. Novelties that should be mentioned are also that all models are fitted with sidebags for the driver and front passenger, an identification system for occupied seats for the release of the front passenger's airbag, an ,intelligent" rain sensor regulating the wipe interval depending on the wetting of the windshield as well as luggage nets in the boot and the front passenger's footwell. Xenon-headlights with a headlight cleaning system and dynamic headlight-range adjustment are available as special equipment. Their external appearance, too, has been slightly modified with the S-class limousines since June 1996; conspicuous features are now the add-on parts painted in brilliant silk body colour which, up to then, had been painted in contrasting colours. But besides the described improvements in detail a model-change in the S-class also became effective in June 1996: The S 350 turbo-Diesel was superseded by the S 300. In contrast to its predecessor, the new Diesel-model is fitted with a turbo-engine with four-valve technology and charge-air cooling. The engine's performance is at 177 hp and thus 27 hp higher than its predecessor; the torque was increased by 20 Nm and is now available on a wide speed-range; the emission of exhaust gases and the fuel consumption could be significantly reduced through the optimized combustion. The S 300 turbo-Diesel is delivered with the electronically controlled 5-speed automatic gearbox as standard.
Since December 1996 the types S 280 and S 320 fitted with an automatic gearbox can also be equipped with the driving dynamic system ESP (electronic driving stability programme). At the same time another innovation - a world premiere - is used that also contributes to active safety: the braking assistant being fitted in all the models of the construction-series 129 and 140 as standard from December 1996 onwards. The braking assistant BAS is able to detect emergency brakings and, if need be, to set up automatically and within a shorter period of time than before the maximum brake boost...In so doing the vehicle's braking distance is reduced decisively.
With the S 500 lang landaulet having been created as a special vehicle for the Vatican, another variant of the construction-series 140 was completed in March 1997 and handed over to Pope John Paul II. The landaulet-folding top is operated electro-hydraulically and allows you to see the Pope taking a seat on his throne seat placed in the middle. There are folding seats available for two escorting persons.
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