Mercedes-Benz 450 SEL 6.9: Luxury legend from 1975 tested

What will you one day be able to proudly say you were there? And what would you have to choose from all that you've experienced, up to this very moment, as you gaze at the first light that gives the new day its gray contours at the edge of the darkness of night?

Aha, you think, it's that time again. First the flickering light of the underground garage, the final heaviness with which the door slams into the mortise lock, the turning of the key, the firing of the eight cylinders, their echo off the bare walls, the drive to the roller shutter, through the lamp-lit darkness of the city onto the A81. Finally, the kilometers to Boxberg, where your thoughts circle and travel – back to the time when a new car was still an event. Like in May 1975, when the 450 SEL 6.9 took the rank of top model in the W 116 series. Mercedes had it ready sooner, but postponed its debut until the oil-crisis-depressed mood toward cars with massive V8 engines brightened. But then the 6.9 arrived – suddenly, unexpectedly, an event, a sensation.

What elevates it to that level? We'd be happy to tell you – let's see if we have enough time. The 6.9 may initially appear to be the successor to the previous-generation 300 SEL 6.3 – although even then, there would be easier successors. But it is much more – according to the test in issue 21/1975, "The Best Car in the World." Unlike the somewhat self-promoting 6.3, the 6.9's exterior hardly differs from the 61 hp weaker, 25,000 DM cheaper 450 SEL. The engineers discreetly tucked away all the extravagance beneath the body of the 10 cm longer long-wheelbase version. After all, the 6.9 travels in circles where you don't steer a car from the front left, but rather from the rear, controlling the fortunes of corporations or countries. In the velour-upholstered salon, such gentlemen travel with air conditioning and headrests as standard.

The chassis enhances the secluded comfort. The 6.9's hydropneumatic suspension is twice as soft on the diagonal-swing rear axle (from the /8) as on the steel-sprung 450 SEL, and 50 percent softer on the wishbone front axle. Hose lines connect the spring-damper elements on each side, and the pressurized oil system, controlled by two regulators, maintains constant body level via the anti-roll bars.

The hydraulic oil is designed for pressures up to 175 bar (equivalent to 177.45 atm). And isn't it precisely this kind of knowledge that immediately earns you, as a newcomer, the status of a neighborhood asset dedicated to accuracy and diligence at the street festival? Your proposal to introduce a uniform lawn cutting height and hedge density will certainly be appreciated.

Now for the V8: It's based on the 6.3; a four-millimeter bore increases the volume to 6,834 cc, and the power also rises to 286 hp thanks to the skillful mechanical fuel injection. To describe the monumental torque, we'll dig out the wonderful unit of the meter-kilogram, which peaks at 56 mkg (122 lb-ft) and never drops below a plateau of 50 mkg (491 lb-ft) from 1,000 to 4,200 rpm (in Nm? 550 and 491). The three-speed torque converter automatic transmission passes the excess torque of the dry-sump V8 to a limited-slip differential. Its 40 percent effective torque would mitigate the strain on the two Michelin XWXs somewhat—if you were to take the risk.

But that was a misunderstanding. You don't just unload all that power and performance on a whim like a checking account with an overdraft. The V8's potential should be viewed as an investment, where the idle dividend alone ensures a very relaxed living at speed.

That should do it now. Up ahead, the exit, three right turns, and then you'll see them standing there, the two from the gas station. Of course, they arrived first, Hans-Dieter and Otto. So: fill up, step on the scales. It says 1,939 kg. That would give a power-to-weight ratio of 6.78 kg/hp, but that's a number with no significant, well, value.

Much more interesting are the values we collect after installing the measurement electronics: those of the speedometer's proactive caution, which prefers to display a little more so as not to constantly exceed the speed limits. Or those of the unexpected presence that the V8, with its volume of sound, is able to establish in the interior noise measurements. Or those of the deceleration performance, which testifies to the fact that the 1970s must have been a time of great optimism, when even the Mercedes developers believed that the four discs with 8.16 m/s² of deceleration force could curb the impetuosity of the 6.9.

As the track flattens out from the banked curve to the straight, Otto stops. Two or three short bursts of acceleration pulsate through the engine and the front of the car, at the edge of which, just before the horizon, the star trembles. Otto presses his left foot on the brake, tensioning the drivetrain with his right foot by gently pressing the accelerator. Foot off the brake, the star stretches skyward until the starting torque support and rear tires engage and the SEL pushes forward. Because the axle is long due to the V8's epic pulling power, and each gear of the automatic transmission is even longer, the first of what was already a limited two gear changes only occurs shortly before 100 km/h. Immediately afterward, they are completed: zero to 100 km/h – in 8.3 seconds, 0.1 seconds slower than in the 1975 test. Up to 140? Plus 0.5 seconds – a tenth per decade, which puts the insignificance of this value into quite reasonable perspective.

Once upon a time, such haste would propel the 6.9 into another dimension. It was the era when a faster car made a real difference. The W 116 competed with airplanes—as a means of travel for people whose time was money.

They travel in concentrated comfort. We drive the 6.9 over rough track eight – after its 250 meters over deep craters and towering boulders, you could wipe out a newer car or two. The Mercedes glides over the track. Its suspension comfort was, is, and remains: incredible, unmatched, outstanding. The fact that it wobbles through the slalom curves with indirect steering and a soft setup only reinforces its destiny as a car for those who always strive for great goals.

Our focus is still on measuring the spacious interior. Then we pack up. Turn the key, and the oil pressure gauge jumps just before the three mark, signaling readiness to leave, just like before the first of the now 649,580 km. On its long journey, the 6.9 bore witness to the times in which what we now call history was written. The 450 SEL is a part of it, but one that extends beyond past and present—into a future as the all-time best.