The creation of the new ‘Super Mercedes’ with the internal designation W 150 began at around the end of 1936 and can be attributed to two circumstances: on the one hand the increased demand from industry and government circles for a more modern premium vehicle, and on the other hand the realisation that the existing ‘Super Mercedes’ model with its conservative suspension including rigid axles at the front and rear plus a chassis of the type found in the very early days of the automobile no longer met the standards laid down by Daimler-Benz AG.

There was also the fact that by then the entire range of passenger cars and racing cars – with the exception of the Nürburg model – had been changed over to designs which included front and rear independent suspension and that since 1931 when it built the Model 170, Mercedes-Benz had been a major protagonist in the arena of advanced passenger car chassis. Daimler-Benz was even already appearing on the international stage as a licensor for the progressive front suspension with two trapezoidal links and coil springs. Even the American motor industry, which tended to be more reserved in such matters, was now using this front suspension.

It was above all a challenge facing design boss Max Wagner: to come up with an up-to-date chassis for the new ‘Super Mercedes’, and the experience gained when redesigning the W 125 and W 154 racing cars proved valuable to him. As was the case with the latter models, for the new ‘Super Mercedes’ he used a chassis made of pipes as a longitudinal member. At the front axle this had trapezoidal links of unequal length and coil springs, and at the rear what was known as a parallel wheel axle – a DeDion axle with coil springs. The thrusts at the rear axle were absorbed by V-shaped front-facing members, which were pivoted on the centre transverse pipe.

The outer longitudinal members made of pipes were curved far downwards in front of the rear axle in order to achieve a low centre of gravity. The longitudinal members were connected to six transverse pipes which were pierced and welded with the longitudinal members. In conjunction with the large shock course for the spring, this torsionally rigid design with bending resistance resulted in excellent road holding, which was unusual amongst such big and heavy luxury cars. This was illustrated by a quotation from the only test report of the time, which appeared on 23 May 1939 in the British magazine ‘The Motor’: ‘Normally a limousine of this size will not be driven in a spectacular manner. We did some fast travelling on winding roads and the general standard of handling and road holding is undoubtedly very good indeed. The car holds its course admirably through fast bends, and the absolute rigidity of the tubular chassis is well reflected in the road holding. Although no ride control is employed, the suspension system provides a good combination of soft riding in town with steady cornering and freedom from excessive roll on the open road, and the whole car gives an impression of considerable stability.’

But it was not merely the chassis design that made such a difference compared with the predecessor – the larger dimensions played a part too. The wheelbase increased by 130 millimetres, the track width at the front increased by 100 millimetres, and at the rear by as much as 150 millimetres. And so the task of the body designers working under Hermann Ahrens was to create lighter, more spacious bodies, whose length grew by an extra 400 millimetres, making them precisely 6 metres long. But the vehicle weight also increased with the size. Whilst the brochure for model series W 07 still referred to 2700 kilograms, the weight for model series W 150 went up to between 3400 kilograms and 3600 kilograms – also according to the brochure. And in some cases it did not stop there. For the special-protection version as a six-seater, 4400 kilograms of mass had to be set in motion – as much as 4550 kilograms in the case of the even more heavily armoured four-seater.

The engine output was also increased for these weights. In the naturally aspirated version the engine output increased by 5 hp (3.7 kW) to 155 hp (114 kW), with a switched-on positive-displacement blower by 30 hp (22 kW) to 230 hp (169 kW). The shafts of the outlet valves were filled with sodium salt for better cooling.
The three-speed transmission from the predecessor with engageable overdrives did not survive in the successor either. It was superseded by a four-speed transmission with a fifth gear as a high-ratio overdrive.

So as not to be punished by shorter refuelling intervals with the increased engine output and significantly higher weights, the tank capacity went up from 120 litres to 195 litres. For what was the world’s largest representative vehicle when it entered the market Daimler-Benz gave the top speed as 170 km/h, though this was drastically cut to 80 km/h for the heavily armoured versions with their bullet-proof twenty-chamber tyres.

Superb performance
This is what ‘The Motor’ wrote about the performance and top speed of the conventional Pullman saloon in 1939:

‘Changing gear gently, without the second-saving brutality that has normally to be employed for test purposes, it proved possible to cover the standing quarter-mile in 21 seconds. From a standstill to 50 mph took 12.2 secs. and to 60 mph. 17 secs., which suggests the standard of performance available without necessarily indicating the absolute maximum results obtainable. Cutting the blower in for a quarter of a mile sufficed to raise the speed from 75 mph to 87 mph, demonstrating its value in maintaining high averages after temporary checks. Timed over a quarter of a mile, the car clocked 100 mph. With some ease, carrying four people; indeed, it was accelerating along the Railway Straight at Brooklands. The speedometer is very nearly accurate erring slightly on the side of slowness lower down the range, and the ultimate readings obtained suggest that the absolute maximum speed is in the region of 108 mph, a truly impressive velocity for an eight seater limousine weighing 3 tons.’

The career of the ‘Super Mercedes’ (W 150) unarguably suffered due to the Second World War, which began shortly after production started. This was also borne out by the body variants produced: the open-top touring cars favoured by the government dominated, in stark contrast to the predecessor model, for which more civilian bodies had been made, such as cabriolets and Pullman saloons.

The bodies for the ‘Super Mercedes’ (W 150) were manufactured solely at the special vehicle production facility in Sindelfingen, which also met exclusive requirements. The designation ‘Sindelfingen body’ became a seal of approval in vehicle construction. The best-known example of this was the Cabriolet B, which was built as a one-off specimen for the heir to the Persian throne and is now a valuable item in the possession of an American collector.

Further special features included the various special-protection versions which existed in the familiar body forms, both open-top and closed. Vehicles with an armoured windscreen could be recognised by additional exterior slits which were linked up with the heating and ensured clear windscreens. Over the course of a special campaign during the war by order of the government calling for specially armoured vehicles (‘Aktion P’), ten four-door and four-window saloons were built. As has already been mentioned, they were even heavier than the special-protection Pullman saloons. Their windows were made of 40-millimetre multilayer glass. The floor was armoured with 8.8-millimetre plates, the rest of the body including the roof with 3.3-millimetre plates of special steel. One of those who carried out these modifications was Friedrich Geiger, who was to become the first Head of Design at Daimler-Benz in the 1950s. From the outside, only the very early vehicles could be told apart from the later models, due to their twin-row bumper and the absence of a boot flap. Their younger counterparts could be identified by the rubber-covered one-row bumpers, usually with two chromed bumper guards and a boot flap. The transition of the front wing to the running boards was non-uniform; sometimes it had a flowing design, but very often the wing was at an offset position to the running board.

In the case of the final special-protection cars built the running boards were left out altogether or concealed beneath trim, with the aim of preventing unwanted passengers from jumping onto the running boards. As was also the case decades later with the Model 600, particularly wide chromed window frames were an indication of especially thick window panes in a special-protection car. The doors were locked electromagnetically and the spare wheels used as an armoured shield. By way of compensation for the increase in weight, the wings were made of light alloy.

The new ‘Super Mercedes’ was the subject of a great deal of customer interest when it was launched – amongst authorities and civilian customers alike. However, because of the outbreak of war on 1 September 1939, only a few vehicles were delivered to civilians, as orders from the authorities were given priority. After the war the ‘Super Mercedes’ body served as a vehicle for heads of state, and was to be found in the royal fleets of Sweden and Norway, for instance, plus it was used when Winston Churchill visited the Norwegian King Haakon in Oslo in May 1948 and during the visit of Queen Elizabeth of England with Prince Philip in 1955.

The 1939 brochure showed the Pullman saloon, Cabriolet D, Cabriolet F and open-top touring car body variants.

The following bodies made up the 88 ‘Super Mercedes’ (W 150) produced between 1938 and 1943:

1 chassis (International Car and Motorcycle Show of 1938, Berlin) 1 Cabriolet B
5 Cabriolet D 7 Cabriolet F
46 open-top touring cars, some armoured 10 saloons, 4 doors, 4 windows, armoured
18 Pullman saloons, 4 doors, 6 windows, some armoured

A successor was developed for the model series W 150. In 1938, the model series W 148 had already been integrated into the development planning process, though at that time it was still intended to be a replacement for the Model 500 N (W 08). But during the course of the development period it increasingly took up the position of successor for the model series W 150. Chief engineer Fritz Nallinger believed that this made more sense, as he explained in April 1941, for instance.

The W 148 model series was intended to mark the creation of a more modern representative vehicle that equalled the ‘Super Mercedes’ of model series W 150. In those years modernity also meant ‘downsizing’, without having to relinquish space and comfort. These efforts were supported by the powerful 170 hp (125 kW) compact V12 M 148 engine, which was considerably shorter than the large-dimensioned eight-cylinder in-line engine M 150 that had previously been used in the W 150, and the M 08 eight-cylinder in-line engine of the Model 500 N. Engine designer Wilhelm Syring had employed an inventive design in order to keep the unit compact – one that had also been used by Maybach for his V12 engines: the crankshaft’s crank pins, which were located next to the main bearings fitted to the block, had only one crank web. The other one was integrated in the main bearing, which was what made the engine very short. By those days’ standards this V12 engine was positioned very far forward over the front axle, leaving sufficient room for the occupants whilst at the same time reducing the exterior dimensions.

Apart from the advantage where the amount of space available was concerned and the more modern technical concept with hemispherical combustion chambers, the M 148 also offered economic benefits.
It could be produced much less expensively than the large M 150 eight-cylinder in-line engine, as it was also used as a static engine but was manufactured in relatively large quantities and was increasingly replacing the M 08 engine as a current-generator drive system. Up until 1945, 3420 units were produced of the M 148 and the 6.5-litre M 173 derived from it, which was exclusively used for stationary applications.

Even though the wheelbase of the W 148 model series was 100 millimetres shorter than that of the W 150 model series and the overall length was no less than 170 millimetres shorter, it still had a representative appearance. Occupants would have enjoyed the same level of spaciousness as they did in the legendary ‘Super Mercedes’. It was also so impressive because of the unrivalled reputation of a V12 engine whose smooth running characteristics were never able to match those of an eight-cylinder in-line engine. Despite the more compact dimensions the W 148 model series was no lightweight, tipping the scales with a mass of 3210 kilograms, but it did still undercut the previous ‘Super Mercedes’ by nearly 400 kilograms. Having said that, as development progressed, the company was forced to do without the weight reduction. The government was demanding more and more special-protection versions, and these would also have made the W 148 model series heavier than originally planned. In turn this would then have necessitated a more powerful engine – though that would have been an easy task for the experienced engine technicians from Untertürkheim. The belt-driven supercharger version of the M 148 was already available in the form of the M 157, which had an output of 155 hp (114 kW) without supercharging, and 240 hp (176 kW) with it.

The W 148 model series was more than just a pilot project. Up until 1942, work commissioned by the government was carried out on two open-top touring cars and two Cabriolet B vehicles. There was evidence that five test cars with various bodies in Pullman saloon and Cabriolet F guise were built, but as the war continued work was stopped in 1942. One Pullman saloon survived the war in a camp in the Black Forest, but no-one knows exactly what happened to this interesting vehicle – presumably it was scrapped. The other cars were probably destroyed by bombs that fell in Untertürkheim and Sindelfingen during the war.

Source: Daimler AG