The world’s first super discrete super limousine is this week’s Car of the Week: the Mercedes-Benz 300 SEL 6.3.

The modern Brabus SV12 R Biturbo 800 is about as good as you can get with absurdly fast large cars. 800 horsepower that are just as home doing 155 mph on the Autobahn as they are driving over rough roads on the way to the synergy meeting back at corporate. This Car of the Week is the first car to take on a similar task.

The W109 S-Class was the 2nd in command for Mercedes at the time. The 600 was already the choice for heads of state. But in 1968, a Mercedes engineer by the name of Erich Waxenberger had a brilliant thought: What if the 6.3 litre V8 from the 600 were placed into the S-Class?

The result was unbelievable: a full-size car that could hold its own with the finest sports cars of its time, and at the same time carry five adults in supreme luxury all the way to 145 mph, without anything to suggest this incredible ability except for that little 6.3 badge on the back, which customers could remove.

Another thing going for it is rarity, as just over 6500 of these were produced. You also have to remember this was a time when both the 600 and the magnificent 300 SL “Gullwing” were produced. Who was going to pay attention to another large car with a large engine?

Due to the low production volumes, the SEL is now extremely valuable, with prices ranging from about $25,000 to over $100,000 for a well preserved example with low mileage.

The first sleeper ever, and beginner of the tradition of fast Mercedes sedans, I give you the Mercedes 300 SEL 6.3.