Mercedes-Benz 450SEL 6.9

42 sales analyzed · 16 topics from real Bring a Trailer & Cars & Bids comments.

“6.9’s are like old boats. Two happiest days, when you buy them and when you sell them.”naccer · Aug 24, 2017 at 8:59 AM

• The M100 6.9L V8: overbuilt and long-livedmechanical
  The 6.9's M100 engine is repeatedly described as bulletproof, stout and never stressed, with owners reporting it can run enormous mileage without invasive work. The main acknowledged wear item is valve-guide wear on high-mileage cars, and commenters argue a strong compression test makes opening up the engine unnecessary, pushing back on fears of a prohibitively expensive rebuild. …
• Known wear points: driveshaft flex disc, brakes, camshaftmechanical
  A former owner catalogs the recurring failures: the rubber donut supporting the two-piece driveshaft tears out under hard throttle, the small brake pads wear quickly, and the suspension pump leaks. Camshaft wear is disputed, with one owner reporting a flat lobe on the right bank, another insisting M100s did not tend to suffer cam failures, and a third saying the cams wear only if the oilers are not upgraded. …
• Hydropneumatic suspension: cost reputation versus realitymechanical
  The 6.9's unique all-four-corner hydropneumatic suspension is the car's defining complication and the biggest source of price hesitation. Some warn it is very expensive to touch with parts that cannot be found; defenders counter that the bad reputation is undeserved and the system is extremely reliable once a neglected car is sorted, with a full four-corner rebuild quoted at roughly 20 hours of labor plus parts. …
• These cars hate to sit: drive regularly and carry suspension blocksownership
  A consistent refrain is that the 6.9 deteriorates when stored and drives better the more it is used, with the suspension in particular needing regular exercise. Owners advise driving it at least weekly and fitting the emergency suspension blocks for storage or long-distance transport to protect the hydraulic components. …
• The three-speed automatic (722.0)driving
  The 6.9 uses the 722.0 three-speed automatic with torque converter, which owners call a touch sluggish off the line but very well matched to the M100 and virtually indestructible, with in-gear acceleration that impresses. Commenters note the W109 6.3 had a four-speed while the W116 6.9 got three gears, and that a four-speed conversion is possible; one owner disputes the count, insisting the transmissions are four-speeds that simply start in second. …
• Freight-train torque and performance characterdriving
  Owners describe the 6.9's appeal as effortless, freight-train-like torque rather than drag-strip launches: it can lay rubber at 30 mph and pulls seamlessly from 60 to 120 mph. Several rate it as shaming even a later 560, and note the car set the 155 mph gentlemen's limit later adopted by Mercedes and BMW. …
• US 250hp rating versus Euro 286 PShistory
  US-market cars were rated 250 SAE net hp against 286 PS DIN for the European version, the deficit attributed to the US car's lower compression ratio and emissions equipment. Commenters underline that SAE net and DIN are effectively the same measurement, and repeatedly note how remarkable 250 hp was for the era. …
• DOT bumpers versus Euro bumperscosmetic
  The large US DOT 'park bench' bumpers versus slim Euro bumpers is the most frequent cosmetic debate. Many owners consider the roughly $3,000 Euro swap the first and best thing to do, while purists argue changing an original-spec car lowers its value and MB concours judging deducts for it. …
• A/C and vacuum system quirksmechanical
  A/C that only needs a recharge, or that holds a charge poorly, appears in listing after listing, and R12 refrigerant is noted as expensive and no longer manufactured. Door-lock and climate-control faults are almost always vacuum-related, a well-known age issue, and the A/C servo is a common trouble spot that one owner temporarily cured with a whack of a hammer. …
• Rust: windshield pinch weld and bumper corrosioncosmetic
  The W116 is described as notorious for rust in certain spots, with the windshield pinch weld a near-universal issue costing around $3,000 to repair correctly plus a $125 gasket. Bumper rust originates inside the rubber-encased metal strip where water gets trapped, eventually bulging and splitting the rubber; buyers are urged to inspect the undercarriage carefully. …
• Parts availabilityownership
  Parts supply is genuinely disputed. Some owners say they have never failed to source a part and that the KJET fuel injection is shared with millions of cars so parts are plentiful and cheap, and seals and trim remain available (if expensive) from the Classic Center. …
• Running costs and the DIY imperativeownership
  Owners agree the 6.9 is expensive to run and never meant for cheap fixes, and that competent shops willing to work on them are increasingly scarce. Whether the car is 'extremely complex' is disputed: some say farming out the work will vacuum your wallet but a mildly mechanically inclined owner can fix most issues themselves, while others insist they are genuinely complex and can cost thousands in labor to sort. …
• Market: records and appreciationmarket
  The threads track a rising market, with BaT records climbing from $61k to $74k and ultimately a $100,000 sale, and prior high sales cited at $77,000 (Barrett-Jackson) and other results in the low-to-mid $60ks. Commenters frame the 6.9 as inheriting the M100 collector baton from the pricier 6.3 and repeatedly argue that the days of buying a good one for under $20k are over. …
• Seller presentation, documentation and PPI drive resultsbuying
  A run of 6.9s failed to meet reserve on BaT, and the community consensus is that a car this complex will not sell without thorough photos, undercarriage shots, driving and cold-start videos, and service records. Commenters urge sellers to pay for a PPI and post the results, and stress that documented history eliminates the unknowns that suppress bidding on a sophisticated car. …
• Cultural cachet, celebrity ownership and rarityhistory
  The 6.9 carries outsized cultural weight from the film Ronin, C'était un rendez-vous, and its second-place Cannonball Rally run, and buyers new were said to be almost exclusively heads of state, royalty, celebrities and tycoons, with Steve McQueen and Johnny Cash among named owners. That mystique rests on genuine scarcity, with roughly 1,816 officially sold in the US and only about 485 brought to North America in 1977. …
• Euro / grey-market cars versus US-specbuying
  Euro-market 6.9s are more powerful and carry the nicer covered headlights, slim bumpers, and dash-knob-adjustable suspension height that US federal rules deleted, most of which can be added back to a US car. Grey-market examples are described as tricky and caught in a value grey area, carrying a risk discount that can make them real bargains, while the big money now wants a true US car or a documented direct Euro import. …