At the Geneva Motor Show of March 1994 the S-Class saloons were presented with discreet stylistic modifications. A series of modified details gave the optical illusion of a lighter, better proportioned and more dynamic appearance – even though external dimensions remained unchanged. This was achieved by a distinctive 'tucking-in' of the lower parts of the bumpers and side skirts and by the horizontal subdivision of these surfaces by means of a swage line running all the way round. The effect was reinforced by modifying the design of the headlights and radiator protection grill. In the modified headlights with optimised variable-focus reflectors, which increased light output by 60 percent, the dipped-beam compartment was no longer separated by a central bar from the high-beam compartment, thus lending the illusion of greater breadth. This impression was underlined by the addition of colourless glass covers for the front turn indicator lights. The six and eight-cylinder models were given a newly designed, more slender radiator grill with a vertical articulation at the centre. For the V12 models there was also a special version with chrome-plated crossbars and an appreciably broader chrome frame. Design modifications to the rear end were also a significant factor in the harmonious overall impression conveyed by the S-Class. For example, the lower radii of the boot lid joints were rounded off in the same style as the coupé models. The taillight band was made broader beneath the rear lights and shaped to fit the new bichromatic design of the rear lights. This served to visually flatten off the height of the boot and to make the rear as a whole appear broader and lower set.
From May 1995 the ultrasonic parking aid PARKTRONIC was available as an option. Ultrasonic signals emitted by the system were reflected by any obstacle encountered and the distance between vehicle and obstacle was then calculated by an electronic control unit. Transmitters and receivers of the ultrasonic signals were combined in sensors integrated into front and rear bumpers, without diminishing in any way the protective function of the bumpers. PARKTRONIC was fitted as standard equipment to the two V12 models from May 1995 onwards. At the same time, the now superfluous guide rods in the rear wings were discontinued in all S-Class saloons.
Following on from the model refinement measures introduced in 1994, which were mainly limited to the styling, the eight and twelve-cylinder models saw a number of technical improvements in September 1995. A completely new five-speed automatic transmission with torque converter lockup clutch – a unit that had been fitted to the S 600 coupé since May 1995 – now replaced the four-speed transmission with hydraulic control in the saloons. At the heart of this technological marvel was an electronic transmission control unit which adapted gear-shifting rapidly and automatically to any given driving situation and which continuously exchanged data with the electronic engine management system. In addition to these pioneering innovations, the new automatic transmission was also much more compact and lighter than comparable five-speed transmissions. To further improve fuel consumption and reduce harmful emissions the engines underwent more revisions. The two V8 engines were given a modified crankshaft, an optimised valve control system, lighter pistons, dedicated ignition coils for each cylinder and an improved electronic engine management system of the Motronic ME 1.0 type, which featured a hot-film air flow sensor in place of the hot-wire air mass sensor. Modifications to the V12 engine were less extensive and affected only the arrangement of the ignition coils and the electronic engine management system. Thanks to the various modifications to the engine and the introduction of the new automatic transmission, fuel consumption for the V8 and V12 models was reduced by 7 percent on average without any loss in output, with exhaust emissions falling by more than 40 percent. September 1995 also saw the introduction of the ESP electronic stability programme as an option for all S-Class models with eight-cylinder engines, a system that helped the driver to correct driving errors by automatically counteracting momentary instability through sensor-controlled brake intervention, thereby contributing to road safety. Since this time ESP has been fitted as standard in both twelve-cylinder models.
In addition to the model refinement package outlined above and presented at the Frankfurt International Motor Show, in September 1995 a new S-Class variant was premiered: the S 600 long-wheelbase Pullman. Developed as an official state limousine and equipped with special protection technology, this vehicle continued a long Mercedes-Benz tradition. The special-production car measured 6213 millimetres in length and was therefore exactly one metre longer than the long-wheelbase S 600. The extra length served to benefit the rear passengers, comfortably accommodated on seats that faced each other and separated if required from the driver's compartment by a glass partition. The Pullman saloon in the 140 series was also available as both S 500 and S 600 without armouring. The first units of both variants were produced in August 1996.
In line with tradition, the normal five-seater saloons in the S-Class were also available as armoured versions – with a choice of 5.0-litre V8 or 6.0-litre V12 engine. Production of both these special protection models began in February 1992, one year after main production start-up for the 140 series.
In June 1996 the S-Class underwent further improvements. Now the five-speed automatic transmission with torque converter lockup clutch and electronic engine management was also available for the six-cylinder models – as an option on the S 280, and as standard on all other models. At the same time the ASR acceleration skid control system also became part of the basic equipment on the six-cylinder models. Other innovations of note included sidebags as standard for driver and front passenger on all models, seat occupancy sensors to operate the front passenger airbags, an intelligent rain sensor that controlled the wiper interval in accordance with the volume of spray on the front windscreen, and luggage nets in the boot and front passenger footwell. Xenon headlights with a wash/wipe system and dynamic range adjustment were available as optional equipment. Externally, too, the S-Class saloons had undergone slight modifications when they were presented in June 1996. Immediately apparent were the satin-finish detachable body components, now painted in the colour of the car rather than as previously in the contrast colour.
In addition to these detail improvements described above, in June 1996 a model change in the S-Class came into effect, with the S 350 Turbodiesel being replaced by the S 300 Turbodiesel. In contrast to its predecessor, the new diesel model had a turbocharged engine with four valves per cylinder and charge air cooling. Engine output was 27 hp higher, at 177 hp; torque was increased by 20 Newton metres and was available over a broad range of engine speeds; exhaust emissions and fuel consumption were much lower as a result of optimised combustion. Electronically controlled five-speed automatic transmission came as standard in the S 300 Turbodiesel.
From December 1996, the S 280 and S 320 models with automatic transmission could also be fitted with the ESP electronic stability programme. At the same time a new innovation had its world premiere as an additional active safety feature – Brake Assist, which was fitted as standard in all 129 and 140 models from December 1996. Brake Assist (BAS) is able to recognise emergency braking situations and, if required, to boost brake power to maximum more quickly than was previously the case, thereby shortening stopping distances considerably.
In March 1997 a further variant in the 140 series was produced: the long-wheelbase S 500 landaulet, a one-off vehicle for Pope John Paul II. The landaulet soft-top was operated electrohydraulically to afford a clear view of the Holy Father seated on his centrally positioned thronal seat. It was also equipped with folding seats for two attendants.
At the Paris Motor Show in September 1998, the public was introduced to six S-Class saloons from the 220 series, which now succeeded the 140 series after a period of seven and a half years. Series production of the 140 models at the Sindelfingen plant had already stopped by this point, and only the armoured versions and the Pullman saloons continued to be built. By September 1998, a total of 406,532 series 140 saloons had been produced, of which 28,101 units had diesel engines.
At the start of its career and particularly in Germany, the largest ever S-Class did not have an easy time – despite the car's undeniable qualities. A valedictory appeared in the Frankfurter Allgemeine Zeitung of 25 August 1998 under the headline: "The end of the good patriarch. Sentimental farewell: The S-Class was always better than its reputation." This obituary written by Wolfgang Peters included the lines: "...No other car offered such ride comfort and suspension, and no other car in this size category could be driven in such safety and with such agility at the same time. The S-Class was a giant that had been taught to dance on the points of its toes. [...] The new S-Class promises to be lithe and lissom: Some of us are missing the fatter version already."