Timelessly elegant, safe, and do-it-yourself-friendly, the W126 is considered by many marque experts to be the best S-Class ever made. An ample supply of fine examples remains on the road.
The Best of the Best: The U.S. Market W126 S-Class 1981-1991
Article Pierre Hedary & Gary Anderson
Contributions Daniel Stahl & Richard Simonds Images Daimler Archives
Few luxury sedans survive long enough to become classics; fewer still are actually affordable by the average enthusiast. The W126-chassis Mercedes-Benz, produced for a stunning 12 years from 1979 to 1991 and sold in the United States from 1981, is a strong contrast in both respects. The W126 was, according to many experts and marque aficionados, the best S-Class Mercedes-Benz ever made.
Examples that received the care and respect they deserved when new are still being driven today. In fact, enough of them have survived in excellent condition that they are not only affordable as entry-level classics, but are even good values for the person who wants a daily driver that is luxurious, stylish and easy to work on for the price of the cheapest new econobox.
Background
In the years following the 1973 gasoline crisis and the furor arising from Ralph Nader’s book Unsafe at Any Speed, automotive manufacturers were challenged to meet increasingly stringent safety requirements, as well as higher standards of fuel efficiency. Mercedes-Benz had been testing a gasoline-powered aluminum-block V-8 and a high output [for the time] turbocharged diesel engine, and was already selling its 2.8-liter twin-cam six in the W116 sedan, introduced in 1973. The W116 car was a well-made car, but the climate control, U.S. bumpers, emissions systems, and other components needed further development to meet world requirements; a completely new design was required to fully address these outstanding issues.
Mercedes-Benz complied: In 1979, the first new W126 Sonder Klasse (special class) models – the 380SE, 500SE and 280S – were delivered to showrooms in Europe. Two years later, the company introduced the 380SEL, the long-wheelbase version of the 380SE, and the 300SD diesel-engine version of the W126, to customers in the United States.
The 300SD was an instant hit. Sales took off and the big sedan won Motor Trend’s Car of the Year Award, a first for such a large vehicle. Extremely well-made, nicely-optioned 300SDs – often pictured in the light ivory color that graced Mercedes-Benz sales brochures – are still a common sight on today’s roads.
The long-wheelbase, gasoline-powered 380SEL did not fare so well. The V-8 produced an anemic 155 horsepower. As smooth as the engine was, timing chain problems were its Achilles’ heel, and Mercedes-Benz technicians were soon plagued with complicated and expensive chain replacements. The stylish but still mechanically challenged 380SEC coupe joined the lineup for model year 1982.
In terms of the gasoline-powered cars, many owners went further afield. The thriving gray market captivated the imagination of many Mercedes-Benz customers, and private dealers began bringing high-performance European W126 cars into the country by the dozens, federalizing and reselling them to eager clients. When companies like AMG, Brabus, Schulz and others joined in the customization and performance party, things got even better.
In 1985, ABS became standard on the W126, heralding a new era of performance and safety. In that same year, the U.S. lineup included the 500SEL, 380SE and 300SD. These models were replaced by the more powerful 420SEL and 560SEL/SEC in 1986. Handsome and refined, one of these new V-8 flagships became the luxury automobile to own if you wanted a big sedan.
On the other hand, the 300SDL with the OM603 turbodiesel that replaced the 300SD in 1986 suffered at the start with cylinder head issues. Thankfully Mercedes-Benz updated the heads with improved versions, but the model was still withdrawn two years later.
Meanwhile, standard airbags and automatic seatbelt tensioners were added to protect drivers of these increasingly fast sedans. In 1988, the 300SE and 300SEL joined the line-up; in 1989, interiors, cooling systems and exterior panels were updated. In 1990, the 350SD/SDL joined the lineup, and the last W126 cars were sold in the United States during the closing months of 1991.
The number of these cars still on the road attests to their workmanship and reliability. The quality of the W126 range is so high that many perfect examples still exist. Few can dispute the charm, elegance and practicality these cars still convey.
Reasons to Buy
Safety, reliability, and comfort made them excellent for daily driving or long-trip touring
Heating and a/c systems were significantly improved and made a W126 comfortable and usable all year around
Engines (both gasoline and diesel) and drive trains were increasingly robust and long-lived with proper maintenance
Interiors (especially M-B Tex) are durable and easy to clean
Values are exceptional at this point in their life cycle (27-36 years old) but are expected to begin appreciating for well-cared-for, preservation-class vehicles
Diesels get mileage comparable with new Mercedes-Benz diesels (high 20s to low 30s on the road)
The W126 is still contemporary looking and offers comfort for passengers, plenty of luggage space and excellent visibility
Reasons Not to Buy
Many examples for sale suffer from lack of maintenance, which may not be readily apparent in a casual inspection
Genuine OEM Mercedes-Benz parts are relatively expensive and may not always have been used in servicing
Aluminum-block engines were vulnerable to overheating, especially if coolant systems were not carefully maintained
Gasoline-engine models are not as fuel efficient as diesels, especially compared with modern cars
In spite of excellent rust protection, the elaborate design of the body makes it vulnerable to rust, which is easily camouflaged and expensive to repair
Checkpoints
Early 380SE/SELs should be checked for timing-chain updates, with chain guides, chains and tensioners replaced
Excessive oil consumption, especially on gasoline engines, may mean worn valve guides or head gaskets; this is an indication of an engine in need of rebuilding
350SD/SDL engines are particularly prone to damage from overheating, and to rod failure; check maintenance records for proof that the engine has been recently replaced or budget for engine replacement
Bio-diesel or vegetable oil conversions should be avoided because the lubricity and cetane rating of these fuels can lead to catastrophic engine failure
Plastic radiators are prone to leakage and cracking, which may also lead to overheating and engine wear
Front-suspension ball joints and bushings are prone to wear or failure and require specialized tools to replace
A/C compressors should be checked for effective operation, ensuring cold air is produced from center dashboard vents; if necessary, replace with a new Behr unit
HVAC defroster vents should close completely when a/c is operated, otherwise a/c actuators may need replacement. A/C repair is complicated because of dashboard design
Seats that sag indicate broken springs and worn-out horsehair pads; torn or cracked leather or MB-Tex may need replacement
Dashboards with cracked vinyl, worn leather and discolored or damaged wood trim are likely to be expensive to restore
Rear-window glass is prone to delamination, leading to rust in rear shroud sheet-metal panel
Back-door vent windows operate by sliding-jaw gear. A replacement part is made; replacement is complex and costly
Airbags should be replaced every 10 years on all cars; check if this was done by an authorized Mercedes-Benz Center
Buying tips
If you are a first-time W126 buyer, look for a 300SD. These cars are known for clocking over half a million miles with no real problems. They are easy to start in all conditions, are quiet and quite powerful, and good examples are easily found. While the model was known for cylinder head issues, most still-running examples have been sorted, and the result is impressive – a comfortable and quick diesel sedan that gets 28 mpg or better, with little noise and no turbo lag.
The successor 350SD was known for connecting rods unable to handle the engine’s torque; many units had to be rebuilt under warranty. Many machinists also agree that these engines would leak oil through their valve guides, and on colds starts, the fluid pressure on top of the piston could damage the connecting rods. Poor fuel quality, lackluster maintenance by some owners, and stop-and-go traffic all conspired to damage these engines, marring their reputation. However, these can be fantastic cars when their engines are “right.”
The best gasoline-engine model is the 1988 300SE/SEL with its bulletproof easy-to-service, I-6 M103 engine. It’s not as fast as the V-8s, but has better balanced performance and is easy to service. A detailed prepurchase inspection, with partial disassembly of the engine to check for timing-chain servicing, head-gasket condition and possible valve wear is money well spent unless you’ve budgeted for a rebuilt replacement engine. Alternatively, a well-sorted 420SEL or 560SEL is a hoot to drive.
In Europe, a 500SEL was available with four-wheel hydraulic suspension. These gray-market cars are not for the faint of wallet, but handling is beyond anything else Mercedes built at the time. The option was offered on some 560SELs, but this model is difficult to find.
When reconditioning interiors, use Mercedes-Benz horsehair pads and ensure that the grain of the leather is correct. Many suppliers are selling incorrect rough-grain leather, which is also less attractive and uncomfortable. Most interior trim is still available from Mercedes-Benz or the leading interior-trim suppliers, though it will be costly.
While gray-market cars were once frowned upon, these models have now come into their own. While their velour interiors are hard to get repaired, the high-horsepower Euro engines with manual gearboxes are exciting to own. AMG did some wonderful things with bodies and power plants, making the W126 its flagship, and attaching twin-cam heads to the V-8 engines. In states such as California, make sure your car can pass the emissions test before you buy it.
The best W126 cars are still under $15,000, though AMG versions can fetch as much as $50,000. As they become more collectable, their value will only rise. These cars pay off in the long term, as many satisfied owners can attest. Even with the cost of service, these cars deliver more than you have to put into them, and with reasonable care are likely to continue to do so for decades to come.
Chronology
1979 First W126s (280S, 280SE, 380SE, 500SE) delivered in Europe
1980 280SEL, 380SEL and 500SEL joined the range in Europe
1981 300SD and 380SEL put on sale in the U.S.
1982 380SEC and 500SEC introduced (the 500SEC in Europe only)
1984 In the United States, 380SE and 500SEL replace 380SEL; 500SEC replaces 380SEC
1985 ABS now standard
1986 300SDL replaces 300SD; 560SEL and 420SEL replace previous gasoline models;
560SEC introduced in the U.S.; airbags and KE-Jetronic fuel injections now standard
1988 300SE and 300SEL replace the 300SDL in the U.S.
1990 350SD and 350SDL introduced in the U.S.
1991 Last W126 series are sold, to be replaced by the W140 series
Specifications: Mercedes-Benz W126 U.S. Models
Sedans: Model Years Chassis Engine Power Torque
300SD 1981-1985 126.120 617.951 1981-83: 120 170
1984-85: 123 184
1985: CA:118 177
Global Production 76,726
380SEL 1981-1983 126.033 1981: 116.961
1982-83: 116.963 155 196
Global Production 27,014
380SE 1984-1985 126.032 116.963 155 196
Global Production 58,239
500SEL 1984-1985 126.037 117.963 184 247
Global Production: 72,693
300SDL 1986-1987 126.125 603.961 1986 Fed: 148 201
1986 CA: 143 195
1987: 143 195
Global Production: 13,830
420SEL 1986-1991 126.035 116.965 201 228
Global Production: 74,017
560SEL 1986-1991 126.039 117.968 238 287
Global Production: 75,071
300SE 1988-1991 126.024 103.981 177 188
Global Production: 105,422
300SEL 1988-1991 126.025 103.981 177 188
Global Production: 40,956
350SDL 1990-1991 126.135 603.970 134 229
Global Production: 2,925
350SD 1991 126.134 603.970 134 229
Global Production: 2,066
Coupes: Model Years Chassis No. Engine No. Power Torque
380SEC 1982-1983 126.043 116.963 155 196
Global Production: 11,267
500SEC 1984-1985 126.044 117.963 184 247
Global Production: 30,184
560SEC 1986-1991 126.045 117.968 238 287
Global Production: 28,929
W126 S-Class Sedan
W126 S-Class Coupe
Front and rear three-quarter views of the handsome 560SEC coupe.
A cutaway drawing of a W126 S-Class sedan.
Head of Mercedes-Benz styling, Bruno Sacco, with scale a model of a W126 coupe.
The W126 interior is both classic and contemporary, with advanced safety and comfort features, including an airbag and an early on-board trip computer (right-hand gauge in instrument binnacle).
The U.S.-market 300SDL turbodiesel and 300SE.
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