Many enthusiasts know the Auto Union Silver Arrows, the legendary Grand Prix racing cars of the 1930s. But few people know that a road-legal sports version with a 16-cylinder engine was also planned for these pioneers. : the Auto Union Type 52. 90 years later, Audi Tradition built this car, the Schnellsportwagen, and will present it to the public for the first time at the Goodwood Festival of Speed ​​in England.

Back to the time when the Auto Union Type 52 was imagined: the Auto Union AG company, founded in 1932 by the merger of Audi, DKW, Horch and Wanderer, became a major player in motorsport from its beginnings, to make its new logo, the four rings, a name recognized throughout the world. The same year, regulations for the Grands Prix held from 1934 to 1936 were published, setting the maximum mass at 750 kg. In 1933, Auto Union AG commissioned the design office of Ferdinand Porsche, located in Stuttgart, to develop a racing car based on these new 750 kg regulations. Work on the Auto Union Type A (internally called the Type 22) began as early as March 1933. A year later, Hans Stuck set a world record by driving the car on the AVUS circuit in Berlin. It was when racing cars from Auto Union and Mercedes-Benz appeared on the international scene that the legend of the Silver Arrows was born.

Fast as arrows, these powerful cars captivated audiences with their futuristic design and revolutionary technology. While Mercedes-Benz favored front-mounted engines, Auto Union was the first to place the engine at the rear, behind the driver. This mid-engine layout is the standard in Formula 1 today. In the years that followed, Auto Union set several world records, winning numerous hillclimbs, three German championships and the European championship in 1936 with Auto Union Type C.

However, part of the story remains to be told. Few people know: while the Grand Prix racing cars were being developed, Auto Union AG and the design office of Ferdinand Porsche were also planning a road-legal sports sedan. Concept documents called the vehicle “Schnellsportwagen”, apparently its intended marketing name. Today, with its distinctive features, the car closely resembles a classic Gran Turismo.

The project, known as the Auto Union Type 52, was intended to be sold to customers to compete in long-distance races like the Mille Miglia or sports car competitions such as the Spa endurance races -Francorchamps or Le Mans. The car was also referred to as a production racing car.

Everyday versatility and sporty dynamics were listed in the design specifications of the Auto Union Type 52

Already at the end of 1933, the Porsche design workshop produced the first sketches, which took on a more concrete form in 1934. The project managers decided to build a prototype – but, according to our current knowledge, the one -it was never built. The project was abandoned in 1935 and its trace was lost in the archives of Audi and Porsche. However, the developers left a lot of work on paper. The project was based on the technology of the Grand Prix racing car developed at the same time: the chassis of the Auto Union Type 52 was designed as a ladder frame with a centrally positioned engine. The Auto Union Type 22 transmission was used, but the compression of the powerful 16-cylinder engine was reduced to allow the car to run on regular gasoline. At the same time, engineers reduced the gear ratio of the Roots supercharger. The Auto Union Type 52 engine was expected to provide approximately 200 horsepower from 4.4 liters of displacement at 3,650 rpm. Its maximum torque of 4,450 kgf-cm (436 Nm) was reached at a speed of 2,350 rpm. Compared to the Grand Prix legend, this represented a considerable reduction in power, but the excellent performance figures calculated by the engineers, of around 200 km/h, show that the Schnellsportwagen would have lived up to its name. In its day, it would have been one of the most powerful road-legal vehicles in the world – a true “Schnellsportwagen”.

Building the car: historical documents as a starting point

Audi Tradition commissioned Crosthwaite & Gardner to build the Auto Union Type 52 using archival documents, plans and design sketches that have survived to this day. The British restoration experts, who also took care of the Silver Arrows for Audi’s historic vehicle collection, completed the construction of the Schnellsportwagen after several years of work in 2023. All components were custom-made and have been handcrafted specifically for the model. At more than five meters long, the Auto Union Type 52 is a sensation: its elongated silhouette reflects how its engineers designed the car for optimal aerodynamics and maximum performance. Unlike its Grand Prix counterparts, the car is more suited to daily driving, as the designers intended, with a high roof, headlights and space for luggage. There is also space for two spare tires. But that’s where the comfort features of this three-passenger car end. As is typical for a racing car, the driver of the Auto Union Type 52 sits in the middle, with the rear seats offset slightly to the side. With three passengers, 70 kilograms of luggage and 150 kilograms of equipment, the spec sheet says the car’s total weight is 1,750 kilograms, with a curb weight of 1,300 kilograms.

While the engine, transmission and 5-speed gearbox were taken over from the Grand Prix car, the engineers opted for different technical solutions for the suspension and damping. Instead of a combination of transverse leaf springs and friction dampers as on the Auto Union Type 22, the Type 52 uses longitudinal torsion spring suspension in combination with hydraulic dampers. During development, the 116 liter fuel tank was repositioned under the seats. On the Grand Prix car, the much larger tank is located directly behind the driver, at the vehicle’s center of gravity, providing the Silver Arrows with ideal weight distribution whether the tank is full or empty. Both the Auto Union Type 52 and Type 22 used drum brakes on all four wheels.

Comments from Stefan Trauf and Hans-Joachim Stuck on the Auto Union Type 52

Audi Tradition will present the Schnellsportwagen to the public for the first time at Goodwood this weekend. Stefan Trauf, Head of Audi Tradition: “We are delighted to present the Auto Union Type 52 at the Goodwood Festival of Speed. This car inspires enthusiasm for design and technology. For me, it is an absolute dream car In its time, unfortunately, it remained a dream – a dream that we can now make real, 90 years later The Auto Union Type 52 is a testament to the ingenuity of its creators and innovation. technology of the time being able to experience the Schnellsportwagen live is a great pleasure for me.”

The Auto Union Type 52 model will be driven at Goodwood by record winner Tom Kristensen at the 24 Hours of Le Mans and racing legend Hans-Joachim “Strietzel” Stuck. The latter’s father, Hans Stuck, made history as a “Champion of Hill Climbs”, scoring numerous victories driving Auto Union Grand Prix cars at popular hill climbs in the 1930s. After his first test drive with the Auto Union Type 52, Hans-Joachim Stuck said: “When I sometimes drive the Auto Union Type C, which my father drove in his day, at Audi Tradition events, the excitement and the The fascination of motorsport fans is palpable. It is a great honor and pleasure to drive the Auto Union Type 52 at Goodwood for the first time. The Schnellsportwagen is simply breathtaking: its engine noise is incredibly sonorous – as if coming from an orchestra. And the design of the Auto Union Type 52 will really impress you – it’s genius!”

A look at the challenges of building this one-of-a-kind model

The Auto Union Type 52 did not reach us completed, but only at the prototype stage. So there are no photos of a completed model. During the dissolution of Auto Union AG in the Russian occupation zone after World War II, most of the historic Grand Prix cars disappeared, as did many files and photographs. Likewise, there are no verified reports from which conclusions can be drawn about the final configuration of the planned Schnellsportwagen, to the extent that one existed. However, plans provide a clear vision of the direction of development and the goals pursued by engineers.

During the construction phase, Audi Tradition and the experts from Crosthwaite & Gardiner were in constant and intensive communication. Timo Witt, head of Audi’s historic vehicle collection, had to solve a whole series of technical problems. Decisions for or against certain technical solutions had to be made.

Today, Timo Witt, after completing this project, says: “One conclusion that emerged from our exchange is that developers in the 1930s probably should have adjusted some technical details during testing, too. Likewise, we We had to lengthen the wheelbase of the Auto Union Type 52 compared to the original design documents because this was technically unavoidable in combination with other components such as the front suspension, engine, steering and transmission. interior is inspired by Auto Union Grand Prix cars, with a modern interpretation of colors and fabrics.”

None of the specified documents specified what color the car would have been at the time. So Audi Tradition once again took the racing car as a reference and chose silver for the finish. When it came to the engine that would power the Auto Union Type 52, Audi deliberately decided to deviate from the designers’ original plan. Audi Tradition used the Auto Union Type C 16-cylinder engine; its power was not limited for the Type 52 to ensure compatibility with Grand Prix cars. For this reason, the engine runs on a special mixture of methanol. Based on the information transmitted, which Audi Tradition has interpreted and implemented with considerable care, the Auto Union Type 52, which will be presented for the first time at Goodwood, is the closest approximation of the Schnellsportwagen Auto Union Type 52 imagined there about 90 years ago but never built – until now!