What Made the 6.9 Sublime

The 450 SEL 6.9 was unveiled at the 1974 Geneva Show. It combined much of the hardware of the W116 S-Class that arrived in 1972, the first large Mercedes sedan to carry that storied designation, with an upgraded version of the 6.3-liter M100 single-overhead-cam V-8 originally developed to power Benz’s 1963 Rolls-Royce fighter, the 600, and subsequently slotted under the hood of the W109 SEL sedan to create the 300 SEL 6.3.

For the 450 SEL 6.9, the engine was bored to increase its capacity to just under 6.9 liters and fitted with Bosch K-Jetronic fuel injection and a 3.2-gallon dry-sump lubrication system. Like the original M100, the 6.9-liter version had a forged crankshaft and forged connecting rods and pistons. The valves were sodium filled to keep them cool at high speed. Each engine was hand-built and bench-tested for more than four hours, 40 minutes of which was under full load.

In European trim, the 6.9-liter M100 developed 282 hp at 4,250 rpm and 406 lb-ft at 3,600 rpm. In the U.S. version of the car, which was introduced in 1977 as the Mercedes-Benz 6.9, emissions control regulations cut power to 250 hp and torque to 360 lb-ft. For context, most contemporary American V-8s of similar capacity were by then struggling to make 200 hp, though Ford and Chrysler offered special police pursuit big-blocks that in 1977 produced 197 hp and 255 hp, respectively.

This Old S-Class Terrorized Porsches and Ferraris—and It Has a Modern Counterpart

The iconic 450 SEL 6.9 continues to shine some 50 years on, with evolutionary ties that bind it to the contemporary Mercedes S450d.Angus MacKenzieWriter

ManufacturerPhotographerSep 12, 2025

The greatest Mercedes-Benz S-Class ever made was a 450. That number still appears on the decklid of S-Class models sold in Europe and other parts of the world. But today’s diesel-powered S450d is a very different beast from the 450 SEL 6.9 that in the second half of the 1970s terrorized Porsches and Ferraris on autobahnen all over Germany.

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The S450d is a terrific car, arguably the pick of the current S-Class litter, even though America’s disdain for diesels means we don’t get it here. It’s powered by Mercedes-Benz’s velvety 3.0-liter straight-six turbodiesel, an engine whose 362 horsepower at 4,000 rpm is underpinned by a muscular 553 lb-ft of torque available from just 1,350 rpm. That’s 34 percent more torque than produced by the entry-level S-Class in the U.S., the S500, 7 percent more than output of the S580, and the same amount as produced by the S580e hybrid. It’s the torque that’s the key to the appeal of the S450d.

What Made the 6.9 Sublime

The 450 SEL 6.9 was unveiled at the 1974 Geneva Show. It combined much of the hardware of the W116 S-Class that arrived in 1972, the first large Mercedes sedan to carry that storied designation, with an upgraded version of the 6.3-liter M100 single-overhead-cam V-8 originally developed to power Benz’s 1963 Rolls-Royce fighter, the 600, and subsequently slotted under the hood of the W109 SEL sedan to create the 300 SEL 6.3.

For the 450 SEL 6.9, the engine was bored to increase its capacity to just under 6.9 liters and fitted with Bosch K-Jetronic fuel injection and a 3.2-gallon dry-sump lubrication system. Like the original M100, the 6.9-liter version had a forged crankshaft and forged connecting rods and pistons. The valves were sodium filled to keep them cool at high speed. Each engine was hand-built and bench-tested for more than four hours, 40 minutes of which was under full load.

In European trim, the 6.9-liter M100 developed 282 hp at 4,250 rpm and 406 lb-ft at 3,600 rpm. In the U.S. version of the car, which was introduced in 1977 as the Mercedes-Benz 6.9, emissions control regulations cut power to 250 hp and torque to 360 lb-ft. For context, most contemporary American V-8s of similar capacity were by then struggling to make 200 hp, though Ford and Chrysler offered special police pursuit big-blocks that in 1977 produced 197 hp and 255 hp, respectively.

In an era when an emissions-strangled Corvette took 6.8 seconds to get from 0 to 60 mph and covered the quarter mile in 15.3 seconds at 91 mph, the large and luxurious Mercedes-Benz 6.9 was barely half a second slower to 60 despite having a three-speed automatic transmission and a curb weight of 4,300 pounds. It took 17.1 seconds to dispatch the standing quarter, sailing through the traps at 90 mph. With more power and torque on tap, the European-spec version was even quicker, taking just 7.2 seconds to hit 60, and on Germany’s unrestricted autobahn it could hit a top speed of 140 mph. It was, at the time, the quickest and fastest four-door sedan in the world.

We liked the Mercedes-Benz 6.9. A lot. “The masses will know it’s a car for the rich, but not necessarily for the rich who like to go fast in the best sedan this side of Alpha Centauri,” gushed Ro McGonegal after testing one for the January 1980 issue of MotorTrend. I’ve driven or tested every generation of the S-Class, but I never had the opportunity to drive the 450 SEL 6.9. Until now. Would the reality live up to the legend?

Though notably smaller than 1977’s “downsized” Cadillac Fleetwood Brougham (the Caddy was a full 22 inches longer overall and rode on a nearly 5-inch-longer wheelbase), the 450 SEL 6.9 was nonetheless a big car by European standards. But it looks almost petite when parked next to the S450d I’ve just been driving. The 6.9 is 4.7 inches shorter overall, 5.8 inches shorter in the wheelbase, 2.0 inches narrower, and 2.9 inches lower overall than its modern ancestor. It’s not just a tale of the tape measure, though: The 6.9’s bodysides are much thinner than those of the current S-Class, and the rectilinear design language emphasizes a low beltline topped with an airy greenhouse.

What It’s like to Drive the 450 SEL 6.9

Despite its smaller external dimensions, the 6.9 feels spacious inside. Whereas the S450d cocoons you behind the wheel, seat bolsters wrapping around your body, a giant center console at your right hip, the door trim reaching almost to your left shoulder, and a huge touchscreen at your fingertips, in the 6.9 you ride high, wide, and handsome in a seat that looks like your grandad’s favorite velour armchair. None of the interior hardware crowds in on you, though everything you need is within easy reach, and all-round visibility is excellent.

The analog instruments in the dash binnacle are an object lesson in clarity, logically arrayed and easy to read. The slides and rotaries that control the HVAC system are simple and intuitive to operate. In an era when automakers have become seduced by gimmicky graphics on infinitely configurable digital dashes and obsessed with replacing physical switchgear with buttons in a menu on a screen to save money, the 450 SEL 6.9’s old-school interior is a delight.

The giant steering wheel looks as if it would be more suited to helming a yacht, the power-assisted recirculating ball steering has the lazy on-center free play so characteristic of old Benzes, and there’s plenty of compliance in the meaty sidewalls of the 215/70 Michelin XWX radials on the puny by today’s standards 14-inch alloy wheels. But once you get dialed into its latencies, the 450 SEL 6.9 will go exactly where you direct it, and once it’s taken a set, will hold its line through a corner with a serenity that’s remarkable for a car engineered more than half a century ago. The self-leveling hydro-pneumatic suspension, similar in concept to that used by Citroën but specifically developed for the 6.9, delivers a combination of ride quality and body control that is outstanding.

And that engine. Kicking the 6.9-liter M100 into action is like opening the floodgates of the Hoover Dam, the big V-8 surging the Mercedes down the road with what seems like irresistible force, the automatic transmission imperceptibly slurring its shifts and the limited slip diff ensuring maximum traction out of corners. For a powerplant that made its debut when JFK was in the White House, the M100 is impressively smooth and muscular. Sure, there are modern naturally aspirated V-8s that kick harder but few that enable a car to build speed as stealthily as this big Benz does. As with its modern badge buddy, the S450d, the secret sauce of the 450 SEL 6.9 is the engine’s torque, that 406 lb-ft all present and correct at 3,000 rpm.

The modern Mercedes-Benz S450d shows just how far automotive technology has progressed in the 50 years since the 450 SEL 6.9 stunned the world. It has a diesel engine less than half the size of the 6.9’s that develops 28 percent more power and 36 percent more torque, while consuming less than half as much fuel. It gets to 60 mph 2.3 seconds quicker, is 3.1 seconds quicker over the quarter mile, and is 15 mph faster overall.

But the 450 SEL 6.9 remains a benchmark. Back in the days when Formula 1 drivers bought their own daily drivers, this Mercedes-Benz was their sedan of choice. James Hunt owned one. So, too, did Jack Brabham, who at the time reckoned it to be the best car in the world. He was right.