Because it's a pre-WWII Mercedes-Benz, only three 540K Special Roadsters are still known to exist.
The 1937 Mercedes-Benz 540K Special Roadster is another model to have set multiple records at auction. The less expensive of the two once belonged to F1 boss Bernie Ecclestone, who sold it for about $8.2 million in 2007. Since then, a different 540K went for $9.6 million at Pebble Beach. It is the most ever paid for Mercedes, or indeed any German car, and it represents the absolute height of the brand at the forefront of both engineering and luxury.
The 540K was more or less based on the 500K, but with a number of improvements being made. The 500K was also distinctly a sports car, whereas with the 540K, customers were given a huge number of customization options, including body type. The coupes have become the most prized, but there were sedans, both hardtop and convertible, and even an armored version (guess which group of Germans these were popular with in the Thirties and Forties...). The 540K was unveiled in 1936, and served as Mercedes-Benz's halo car, available only through special order.
Mercedes was already a big company in comparison to other luxury automakers at the time, and their in-house manufacturing and design capabilities were such that, unlike other luxury cars which were sold as a chassis only and then taken to a coachbuilder to make a body, most 540K's were sold as complete packages. Of the 406 copies of the 540K to have been sold, only 70 had bodies made by independent coachbuilders, representing a significant shift in the manufacture of luxury automobiles. But the custom-bodied cars aren't the valuable ones, it is the Special Roadster which commands the highest prices.
These were exclusive at the time they were built, with only 26 made, and selling for $12,000 (about $187,000 today) when new. Although, as you might expect from a prewar German car, not all of them made it through the war, and only three are known to exist today. One of these, the one formerly owned by Ecclestone, was bought by an Englishman in 1937, who hid it in his garage all through the war, too embarrassed to be seen driving a German car, particularly one so flamboyant. It might or might not be obvious from the pictures, but the Special Roadster is huge, as was the norm at the time.
Its over seventeen feet in total length is among the biggest of any car to carry only two people. Yet the styling is so elegant that this length seems normal and proportionate, a testament to the design of Hermann Ahrens. Despite its size, the 540K is relatively light, even compared to the 500K. This is because the girder-frame design which was used for the 500K (as well as most cars of the era) was done away with for the 540K, and a tube frame was used instead. This was technology derived from the Mercedes Silver Arrow race cars, and was just one of the technological advantages which the 540K had over competing cars.
The 540K also featured vacuum-assisted hydraulic brakes, synchromesh for three of the four forward gears, and four wheel independent suspension. These features were at the cutting edge of technology in 1936, and Mercedes took a great deal of pride in them. Mercedes nomenclature was somewhat less convoluted in those days, as compared to now, and the 540K features, as the name suggests, a 5.4-liter supercharged engine; the K standing for "kompressor", German for supercharger. The presence of the supercharger is hinted at by the external exhaust pipes, a popular feature on supercharged cars at the time.
The inline eight-cylinder engine produced 180 horsepower, which was less than some competitors, but the 540K's relative lightness more than made up for this. Chassis production continued up through 1940, when the Second World War necessitated a switch in production. Bodies for the 540K were still produced for several years, although there was a large drop off in the number made from 1941 onward. Production more or less ended in 1944 when the Allies, with very good reason, bombed the Mercedes factory in Stuttgart. It is reported that some replacement bodies were produced after this, although it isn't know how many.
With all that was lost in WWII, the 540K is pretty far down on the list of tragedies. But it is still unfortunate that the era of such elegant prewar cars came to an end. They wouldn't have lasted much longer anyway, but cars like the 540K remain as a reminder of just how beautiful a car can be when form is put before function. No car will ever again be as pure a work of art as it was in the days before airbags, passive pedestrian protection and 5mph bumpers. Hence the high price commanded by the 540K Special Roadster.