Mercedes-Benz S-Class (W140)

59 sales analyzed · 17 topics from real Bring a Trailer & Cars & Bids comments.

“The ultimate “bank vault” Mercedes. The W140 feels like it is machined from a solid block of steel.”RepairGuy · Jul 22, 2024 at 6:17 PM

• Biodegradable wiring harness (all US cars through 1995)mechanical
  The single most-discussed W140 issue: Mercedes used biodegradable insulation on engine wiring harnesses, and the marque-knowledgeable consensus is that every US W140 through the 1995 model year is affected, tied to LH-SFI injection. Sellers repeatedly (and sometimes wrongly) claim early 1992 cars are exempt; the counter-view is that undisturbed low-mileage cars simply haven't failed yet. …
• AC evaporator core failure and labor-intensive replacementmechanical
  The dash-buried evaporator core is a notorious W140 failure point, reportedly riveted to the firewall so that replacement requires pulling the entire dashboard. Quoted costs range from ~$2,800 at the low end to $4,000-$10,500 at dealers, with book time around 24-25 hours. …
• The M120 V12 (600SEL/S600) as a high-water-mark enginemechanical
  The M120 6.0L V12 is revered as Mercedes' most ambitious engine of the era, described as the only quad-cam four-valve-per-cylinder V12 the company built, with linear power and near-bulletproof durability once maintained. US output was 402 bhp for 1992, dropping to 389 bhp for 1993 and later. …
• Overbuilt bank-vault construction and safety reputationhistory
  Owners repeatedly frame the W140 as the last no-budget Mercedes, reportedly the product of roughly a billion dollars of 1980s R&D, feeling machined from solid steel and effectively armored. Its safety mythology is tied to Princess Diana's crash, with commenters citing its ~5,000 lb mass. …
• Early pre-facelift versus late cost-reduced carsbuying
  The community splits on which era to buy. One camp prizes the early (1992-1994/95) pre-facelift cars for purer build quality, better aesthetics and unique gadgets, arguing later cars show progressive cost-cutting. …
• Market standing: long undervalued, now appreciating, economy-sensitivemarket
  Commenters describe the W140 as historically unloved and a basement bargain that is finally being recognized, echoing the earlier W126 appreciation curve. V12 600s that once traded near half current money have roughly doubled over a decade. …
• PSE vacuum soft-close doors, trunk and pop-out handlemechanical
  The pneumatic (PSE) system running the soft-close doors, trunk, central locking and the pop-out trunk handle is a common age failure, with door pumps still available but the trunk pump now NLA and the membrane going brittle. Fixes range from resetting a fuse or refurbishing/converting to manual mode, to replacing the vacuum pump. …
• Early-only gadgets: reverse parking rods, power rear-view mirrorcosmetic
  Pre-facelift cars carry a set of signature gadgets that later cars lost: the motorized reverse parking rods (telescopic corner markers) that rise in the trunk, the fully electric memory interior rear-view mirror, switchblade keys, double-pane glass and a hidden in-dash cell phone pad. These features are treated as conversation-starters and a reason to seek out early cars, even as owners admit the parking rods are functionally useless. …
• Infrared key fobs are unobtainableownership
  Working factory infrared remote key fobs are treated as essential and effectively NLA; Chinese replacements reportedly do not work. Missing fobs materially dent value and complicate ownership, though commenters note Mercedes has floated a new run of main keys and third parties can cut keys at roughly $150-$500 (valet vs full). …
• Mechanical odometer/cluster failure and mileage authenticitybuying
  Early cars used plastic-geared mechanical odometer clusters that frequently broke, often under warranty and reportedly if the trip odometer was reset while moving; Mercedes replaced many with digital clusters via a documented VIN-based warranty program that carried the stated mileage forward. The upshot for buyers is that a swapped cluster can make true mileage unverifiable, so Carfax cross-checks and cluster documentation are recurring due-diligence themes. …
• Driving character: serene, comes alive at highway speeddriving
  Owners describe the W140 as a continent-crushing highway car that feels most composed above 70 mph, delivering unmatched quiet and comfort while being too cumbersome and thirsty (single-digit city, high-teens highway MPG) to make sense around town. Long-trip praise is near-universal, with multiple owners rating it the best-riding car they have driven. …
• Maintenance cost and buying advice: buy sorted, not cheapbuying
  The prevailing advice is to buy a well-sorted, well-documented car and budget roughly $1-2k/year, because a cheap neglected example becomes a horror story with control arms, engine and trans mounts, ignition coils, AC parts and vacuum pumps all wanting attention at 30-plus years. The community adage is that with these cars you buy the service records and prior owners, and the early cars are explicitly not for the faint of heart. …
• M104 inline-six (300SE/S320) character and desirabilitymechanical
  The earliest 300SE/SEL used an oddball M104.990 3.2L LH-injection six, unique to the W140, rated around 228 hp and 229 lb-ft and considered notably torquier than the CIS-E M104s in the W124/W129. The short-wheelbase 300SE/S320 is called out as the sweet spot of the six-cylinder cars, and these engines are cited running to very high mileage (one owner referenced a 630,000-mile 1997 S320). …
• Suspension: SLS self-leveling, 600 ADS, and fast-wearing bushingsmechanical
  The 500/600 cars use a rear hydraulic self-leveling suspension (SLS) described as simple nitrogen-sphere damping without electronics, while the S600 adds the more complex Adaptive Damping System (ADS) that owners credit with transforming the drive. Across the range the car's ~5,000 lb mass wears ball joints and suspension bushings quickly, making front-end condition a key inspection item. …
• Rust points, UV damage and outdoor-storage tellscosmetic
  Rust concentrates around the trunk lock button area, and cars stored outdoors show UV damage in the rear vanity mirrors and third brake light as well as faded paint. A separate quirk: the hollow rocker panels have rearward-facing rubber drain grommets that, if knocked out (often by flatbed haulers), let the rocker resonate at speed like an organ pipe. …
• Interior leather quality declined in later yearscosmetic
  Commenters distinguish the thicker, firmer top-grain leather of early and mid cars (through 1997) from the softer leather of 1998-1999 cars, which looks the same but is felt to wear worse long term. Owners defend the material as genuinely high-quality versus modern thin or synthetic hides, and note it hardens with age but softens again with conditioning; re-dyed interiors are treated as a red flag. …
• V12 600 rarity and low surviving productionmarket
  The V12 600 cars are cited as very low production, especially for US-market and specific colors, and enthusiasts track survivors closely. One owner gives per-year S600 figures for the late cars and estimates perhaps half survive in good shape; color/spec rarity data circulates for individual paints. …