Mercedes Benz, 600, 600sel, V12 engine, black Mercedes Benz, 1992, collectable Benz, collectable Mercedes Benz, award winning Mercedes Benz WYAPEDIA
This description I found on WIKIPEDIA. I have changed it to reflect the 600 SEL more than the other 140's but it still tells the history of  the 140s development........

Mercedes-Benz W140 
The Mercedes-Benz W140 is a series of flagship vehicles that were manufactured by the German automotive company Mercedes-Benz. On November 16, 1990, Mercedes-Benz unveiled the W140 S-Class via press release, later appearing in several February and March editions of magazines. The W140 made its public debut at the Geneva Motor Show in March 1991, with the first examples rolling off the production line in April 1991 and North American examples on August 6, 1991(Wilham came off the line in November 1991). Short (SE) and long (SEL) wheelbase sedans were offered initially, as well as the coupé (SEC=S-Klasse-Einspritzmotor(Fuel injection engine)-Coupé) body style C140 from October 1992. Like all Mercedes-Benz lines, the W140 S-Class was rationalized in late 1993 using the new "letter-first" nomenclature. The SE, SEL, and SEC cars were renamed the S-Class, with alphanumerical designations inverted. For example, the 500 SE became the S 500, and the 500 SEL became the S 500 L. In 1996 the coupé models following a mid-life update were separated into the CL-Class. The W140 series S-Class was superseded by the W220 S-Class sedan and C215 CL-Class coupe in 1999 after an eight-year production run.
Mercedes-Benz built 35910 V12 from 1992 to 1999 

As with its predecessor, the W140 was the first of the "next generation" of Mercedes-Benz models to feature the company's new design theme. This design was later adopted in 1993 for use on the facelifted W124, as well as the new C-Class.
Development on the W140 began in 1981, originally set for an October 1989 production start. The 4 door sedan type body was styled by Bruno Sacco. From 1982 to 1986 several designs were reviewed, until December 9, 1986 when a definitive design by Olivier Boulay was approved. Several prototypes were tested onwards from early 1987 and the final production exterior design was frozen in 1987, with domestic design patents being filed on February 23, 1988 and U.S. patents 6 months later on August 23. The design was said by lead designer Bruno Sacco to be influenced by Jaguar's XJ40 sedan and BMW's E32 7-Series.[citation needed] Before production started, the exterior appearance of the W140 was revised in the form of the grille on all W140s being recessed as opposed to a planned exclusive grille on the top model, a feature which later spread to the rest of the Mercedes-Benz range. In 1987, an 18-month delay was made from 1989 to 1991 to accommodate a V12 engine and a high-performance braking system. This resulted in the final development prototypes being completed in June 1990. Pilot production models were made from June 1990 to January 1991. In 1989, Lexus introduced the LS 400 luxury sedan. To rival the LS 400,[6] extra features were rushed for the launch of the 1991 W140 causing budget overruns and costing the job of Daimler-Benz's chief engineer, Wolfgang Peter.
The W140 introduced innovations such as double-pane window glazing, power-assisted closing for doors and trunk lid, electric windows which lowered back down upon encountering an obstruction, rear-parking markers which rose from the rear wings (discontinued on later vehicles, and replaced with sonar-assisted parking) and a heating system which, if desired, continued to emit warm air after the engine was turned off. For details like this, the W140 is often known as the last Mercedes to be "over-engineered," a Mercedes trait that was costing the company in product delays and overbudgeting. According to Motor Trend, this action reportedly caused project cost overruns and resulted in the departure of Wolfgang Peter, Daimler-Benz's chief engineer. The vehicle is believed to have cost Mercedes-Benz over $1 billion to develop. For the consumer, the W140 cost a considerable 25 percent more than its predecessor, the W126.
The W140 was to feature air suspension as an option, but it was dropped shortly before launch because Mercedes was still perfecting the technology at the time. Mercedes chose to launch air-suspension (AIRMATIC) in the next generation S-Class in 1998. The W140 instead used a 6 litre 402 horsepower V12 engine joined the lineup for the first time with the 600 SEL and 600 SEC. A "V12" badge was affixed to the C-pillar.
In 1993, the 402 horsepower ( 408 hp Europe ) V12 engine was slightly detuned to 389 horsepower to comply with tighter emission control regulations in the United States and Europe. The V8 models were tuned down from 322 horsepower to 315 horsepower. This de-tuning, among other changes, involved the deletion of the full-throttle enrichment circuit, which reduced output by 7 horsepower.

    In June 1993, as part of the new corporate naming campaign, the model range was renamed. This resulted in all SE and SEL models now being re-designated as "S", being followed by the numbering.
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 changes were later introduced in June 1996 as 1996.5 models in Europe and 1997 models in the United States.
Height of the W140 production models varied between years (1992–94 W140 Sedan: 58.7 in; 1992–94 V140 Sedan: 58.9 in; 1995–96 W140 Sedan: 58.4 in; 1997–99 V140 Sedan: 58.3 in; C140 Coupe: 56.7 in; 1997–99 W140 Sedan: 58.5 in).
The car gained unwanted attention when Princess Diana and two others died in a car crash involving a S 280 model, in a Paris tunnel. Only one person survived, sat in the front passenger seat.​

The W140 S-Class introduced several safety innovations which have since become commonplace among many vehicles.

Comfort and convenience
Some innovations for the W140 included:
Double-paned soundproofed glass was a new S-Class innovation first fitted on the W140. This form of window glazing allowed for improved soundproofing, reduced condensation, and other insulation benefits.
Electrically-operated exterior mirrors could be folded at the flick of a switch to ease driving in narrow spaces.
'Parameter steering' was a system which made low-speed driving easier by reducing the effort required to maneuver in speed-sensitive situations such as parking.
Rear-parking markers, or guide rods. These rods extended from the rear corners of the trunk lid when in reverse, providing the driver with a guideline for rear maneuvers. In 1995, this system was replaced by the sonar-based Parktronic system which measured the distance of the bumpers to nearby obstacles.
12-way powered, heated front seats, with 3 setting memory functions and lumbar support.
Windshield wipers w/heated washer system. Later models also included Rain-sensing windshield wipers.
Electrically-operated automatic-dimming inside rear-view mirror that tied into the seat and steering wheel memory.
Heated exterior mirrors. Later models also included auto-dimming driver's side mirror.
Orthopedic seats were an expensive option from the factory but consisted of several different air cushions in the seat that the user can inflate and deflate to find the perfect driving position.
Dual-zone climate control. Four-zone climate control on LWB models.
Reclining and heated rear seats on LWB models. V12 models also have the four-place seating option, which allows fully adjustable rear seats, lumbar support and rear sunshade control. The center seat has been replaced by a burlwood center console, allowing a 2 + 2 seating format.
The climate control system could be set to operate for 20 minutes after the engine had been turned off.
Electric Rear Sunshade
Rear passenger illuminated vanity mirrors.
Soft-Closing Doors and Trunk.
Leather interiors and burl inserts (optional; standard for 500SEC/CL 500).

Drivetrain technologies[edit]
First introduction of CAN bus (5 CAN bus nodes).
The W140 featured a newly developed front axle double wishbone suspension and a rear independent multi-link suspension.
In 1991 the first generation of the ADS (Adaptive Damping System) (Skyhook-type suspension) was introduced. It adjusted the damping level of the shock absorbers to help stabilize the car during high speed driving, aggressive driving, or if the driver loses control of the vehicle.  Became standard on V12 models and optional for V8 models.