Mercedes-Benz W126 buyer's guide
The definitive S-Class of the 1980s — Bruno Sacco's flagship.
Years: 1979–1991 · Models: 280S/SE/SEL, 300SE/SEL, 380SE/SEL, 420SE/SEL, 500SE/SEL, 560SEL, 300SD, 300SDL, 350SD, 350SDL
Overview
The W126 was the best-selling S-Class generation: a formal, aerodynamically refined flagship sold for twelve years in standard and long wheelbases, with six-cylinder, V8, and diesel power. In the United States the big V8 SELs became the executive car of the decade. Production was vast, values were low for years, and the best low-mileage cars are now being collected in earnest.
Engines
The M110 and M103 sixes; the M116 and M117 V8s from 3.8 to 5.6 litres; and the OM617 and OM603 diesels, including the 3.5-litre six-cylinder diesel of the last cars.
What to check
- On the early 380 V8s, whether the original single-row timing chain has been converted to the later double-row design — an unconverted car needs the work priced in immediately.
- On all V8s, timing-chain guides and rails, which age and embrittle; listen for start-up rattle and ask for records.
- Rust under the rear window and in the rear parcel-shelf area, at the battery tray, and in the trunk — the W126's characteristic weak points.
- On the 350SD/SDL's 3.5-litre diesel, the engine's history: this version of the OM603 has a known weakness for connecting-rod and head problems ('rod bender'), so records matter more than mileage claims.
- Climate control function, and the rear self-leveling suspension fitted to many SELs.
Values
The 560SEL leads in the United States, with low-mileage, fully documented V8s of any size behind it; the 300SDL is the diesel connoisseur's car. As always in a high-production series, the premium belongs to preserved, papered cars, and modified examples trail badly.
Buying tips
Ask the timing-chain question of every V8 seller and the engine-history question of every 350 diesel seller. Beyond that, buy the W126 the way you buy the W123: on records and rust, not equipment.
See the 42 W126 cars currently listed.