The Mercedes 6.9 almost didn’t make it to the US, due to the energy crisis and issues with federalizing it. But the demand was great in the US, especially from former 300SEL 6.3 owners ready for a comparable replacement. They got, finally, two years after the 6.9 first went on the market in Europe. And it was worth the wait. And the money.
Its engine was of course an updated one that made the 6.3 such a legend in its time. Now packing 6.9 liters, its rated net output was a rather modest 250 hp at an equally modest 4,000 rpm. Torque was ample, at 360 lb.ft. at 2500 rpm. It may not sound like much, but this was 1977, and it was enough to scoot the heavy (4400 lbs test weight) big sedan from 0-60 in 8.2 seconds (6.3: 6.9 sec.). And it could hit 138 mph.
The 6.9’s other major unique asset was a hydropneumatic suspension system, a la Citroen, but using nitrogen and oil. It was highly effective, in terms of offering a very svelte ride at lower speeds but the nature of nitrogen meant that it became progressively stiffer with increased demands on the system.
The 6.9’s interior (this one is well used) was of course classic Mercedes of the times, meaning a bit too spartan and austere for the times, and even somewhat more so than its 6.3 predecessor. Power seats? Nein!