It was marketed as the second generation of the Mercedes-Benz S-Class, and manufactured in sedan/saloon (1979–1991) as well as coupé (1981–1990) models, succeeding the company's W116 range.

The aerodynamic drag was reduced through lengthy wind tunnel testing and reshaping of the front end and bumper along with hiding the wipers underneath the hood/bonnet for smoother flow.

Reducing the weight was accomplished by extensive use of high-strength low-alloy (HSLA) sheet and polyurethane deformable material for bumpers and side claddings.

At the same time, the "Energiekonzept" (Energy Concept) was introduced to improve the fuel efficiency of S-Class through engine revisions.

The Second Series has a "hill-hold" feature that prevents the vehicle from rolling back suddenly when disengaging the brake and engaging the throttle pedals at the steep incline.

The transmission in European models has a S/W switch to allow the start in either first (Standard) or second (Winter) gear respectively.

The topographical sensor also offers a better driving experience with cruise control by adjusting the throttle smoothly and automatically without sudden lurching or decelerating when maintaining the desired speed.

The HPF III automatically lowers the chassis by 24 mm when the vehicle is travelled at least 120 km/h for improved aerodynamic flow and better high speed stability.

The system adjusts the damping rate from soft to hard based on speed and road condition for extra comfort and better drivability.

Due to its complexity and tendency to fail catastrophically, HPF III was very difficult to service and was often, at the owner's request, removed and replaced with coil springs and shock absorbers from models without hydropneumatic suspension system.

[citation needed] First Series (1979–1985) At the introduction in September 1979, the 2.8-litre DOHC six-cylinder inline M110 engine from the 280 S/SE/SEL was carried over from the W116.

Mercedes-Benz developed a special silicon coating as to harden the cylinder liners against excessive wear and tear.

The smaller of the two V8 engines was initially the only one offered in the US market, to help meet Corporate Average Fuel Economy (CAFE) requirements.

The 380 SEL received a poor customer perception in the United States as being severely underpowered and due to mechanical issues with the single timing chain.

This programme revised the combustion chambers and piston heads with lower compression ratio in the V8 engines.

The new six-cylinder inline M103 engine had a single overhead camshaft and electronic-mechanical fuel injection and was available in two sizes: 2.6 and 3 litres.

This engine, classified as ECE-Variante (German name), has a higher compression ratio of 10:1 and cannot be retrofitted with a catalysator at a later date.

The new engine had an ill-gotten reputation for higher percentage of aluminium cylinder head failure due to poor placement of the diesel particulate filter and due to the erosion of the head gasket, allowing cooling fluid to seep into the cylinders.

In 1990, the same engine was bored out to 3.5 litres as to compensate for reduced performance due to stricter emission regulations.

The bored out 3.5-litre version did not have any of aforementioned issues other than some units experiencing the unexplained erosion of head gasket.

First Series (1979–1985) The automatic transmission had four speeds with direct drive in the fourth gear for the entire run from 1979 to 1991.

Second Series (1985–1991) From 1986 onward, the automatic transmission was revised to include the option of selecting S (Standard) and E (Economy) shifting points.

When the W126 was introduced in the United States in September 1980, Mercedes-Benz only offered the smaller 3.8-litre V8 engine to avoid the gas guzzler penalty under Corporate Average Fuel Economy (CAFE) regulations.

[22] In 1988, an intense lobbying effort by Mercedes-Benz and other foreign manufacturers led U.S. Congress to eliminate this consumer option and revise the rules for registered importers.

[31][32] Three armoured 560 SEL ordered by Saddam Hussein had a series of pipes that shot flames out of the sides.