The Mercedes-Benz W126 S-Class, emerging in 1979, marked a pivotal shift for the marque. While its predecessor, the W116, cemented Mercedes’ reputation for safety and engineering excellence, the W126 elevated the S-Class into a symbol of luxury and status throughout the 1980s. The 1986 model year is particularly significant, representing a mid-cycle refinement that enhanced both performance and prestige, most notably with models like the 1986 Mercedes 420sel.
The W126’s design philosophy emphasized aerodynamic efficiency and fuel economy, a departure from the boxier designs of previous generations. This resulted in a 14 percent reduction in drag and a relatively lean curb weight of around 3,600 pounds for base models. In an era dominated by gas-guzzling American sedans, the six-cylinder and diesel versions of the W126 showcased impressive efficiency for their class. Furthermore, Mercedes-Benz continued to champion safety, offering a driver’s side airbag throughout most of the production run, and introducing a passenger airbag in 1989, which became standard in 1990. Advanced safety features such as traction control and seatbelt pretensioners were also introduced in this generation, setting new benchmarks for automotive safety.
For the US market, the W126 S-Class can be broadly categorized into two series: 1979-1985 and 1986-1991. The initial years saw the introduction of the 380SE/SEL and 500SEL, both powered by V8 engines. However, 1986 marked a significant update, bringing the 300SE/SEL (inline-six), the 420SEL, and the 560SEL (V8) to American shores. The coupe versions, known as SEC models, followed a similar pattern, with 380 and 500 variants in the early years, and 420 and 560 post-refresh. It’s worth noting that the earlier 380 models, and even the initial 420s, are often considered to be somewhat underpowered due to emission controls. The 300 models introduced in 1986 were surprisingly close in performance to the US-spec 420SEL.
Diesel engines also played a crucial role in the W126 lineup. From 1980 to 1985, the US received the five-cylinder 300SD. This was followed by the six-cylinder 300SDL in 1986 and 1987, and later the 350SD and 350SDL models in 1990 and 1991, maintaining Mercedes-Benz’s diesel presence in the luxury segment.
The 1986 mid-cycle update brought more than just engine enhancements to the W126. Visually, these later models are distinguished by their modern flush-face halogen headlamps and integrated headlight wipers. Interior upgrades included electronic automatic climate control, an electronically adjustable steering column, and leather trim on the steering wheel and shift lever. Heated front seats, standard on the 560SEL and 560SEC, were optional across the rest of the range. For the ultimate in rear passenger luxury, a two-place rear seating option with power-adjustable seats was offered for the first time on the 500SEL and 560SEL. This exclusive option included a burl-walnut center console and plush Arametta suede-like leather upholstery.
In terms of mechanical robustness, the powertrains of the Mercedes W126 are renowned for their durability, often exceeding 200,000 miles without major issues. Engines frequently outlast transmissions. However, typical wear items such as front-end and steering bushings and components will require replacement over time. While general repairs are comparable in complexity to other European cars of the era, parts costs can be a significant factor in ownership expenses. Vacuum-operated power locks can be a source of intermittent problems, and the climate control system, while advanced for its time, is less effective than modern systems and can be costly to diagnose and repair.
Diesel engines in the W126 generally offer even greater longevity than their gasoline counterparts. However, fuel system issues can arise in colder climates or with infrequent use. It’s worth noting that the 350SD and SDL models have not achieved the same level of reliability reputation as other W126 diesels due to reported issues with bent connecting rods and cracked cylinder heads in certain years. For later diesel models, engine mount replacement is considered essential. Owners of 1986 and 1987 300SD California-emissions models should ensure that the original particulate filter has been replaced with an oxidation catalyst.
The W126 S-Class gained notoriety as a popular choice for gray-market importation into the US during the mid to late 1980s, prior to the Motor Vehicle Safety Compliance Act of 1988. The 500SE and 500SEL models were particularly sought after, considered the pinnacle of the W126 lineup from 1985 to 1991. However, Mercedes-Benz USA did not officially offer these models in the US with the same level of features and finishes available in Europe. This discrepancy led dealerships and individuals to import approximately 22,000 W126 vehicles through unofficial channels.
The 1986 Mercedes 420SEL stands as a prime example of the W126’s enduring appeal. It represents the refined luxury, engineering prowess, and lasting legacy of the W126 S-Class after its significant mid-cycle enhancements. For enthusiasts and collectors seeking a classic Mercedes-Benz that embodies 1980s opulence and robust German engineering, the 1986 420SEL remains a compelling choice.
