The original 'Bahnstormer: Auto Union's Schnellsportwagen becomes a reality

• 
• 
• 
• 
• 
• 
• 
• 
• 
• 
• 
• 
• 
• 
• 
• 

Everyone knows the Auto Union Silver Arrows, the legendary 1930s Grand Prix racing cars. But hardly anyone knows that a road-legal sports car version with a 16-cylinder engine was also planned for these pioneering racing cars: the Auto Union Type 52. Now Audi has built this car, the Schnellsportwagen, and presented it to the public for the first time at the Goodwood Festival of Speed in July, 2024.

Back to the time when the Auto Union Type 52 was imagined: Auto Union AG, formed in 1932 from the merger of Audi, DKW, Horch and Wanderer, became a motor sport contender from early on to make its new logo, the four rings, a household name around the world. The same year, the rules were published for the new 750 k.g. formula used in Grands Prix from 1934 to 1936. In 1933, Auto Union A.G. commissioned the Stuttgart design office of Ferdinand Porsche to develop a racing car based on the 750 k.g. formula. Work on the Auto Union Type A (internally, Porsche called it the Type 22) began in March, 1933. Just one year later, Hans Stuck set a world record driving the car on the AVUS circuit in Berlin. When the innovative Auto Union and Mercedes-Benz race cars burst onto the international racing scene, the legend of the Silver Arrows was born.

Swift and sleek as their namesake, these mighty powerhouses captivated audiences with their futuristic design and revolutionary technology. While Mercedes-Benz favoured front-mounted engines, Auto Union was the first to place the engine behind the driver—a layout which would eventually set the standard for Formula One cars. In the years that followed, Auto Union set several world records, winning numerous hill climbs, three German championships, and the European championship in 1936 with the advanced Auto Union Type C. The rest, of course, is history...

Or maybe not quite, as one part of the story remained untold. Few people know that while the Grand Prix cars were being developed, Auto Union A.G. and the Ferdinand Porsche design office also planned a road-legal sports saloon. The concept papers called the vehicle Schnellsportwagen, apparently its intended marketing name. Today, with its distinctive characteristics, the car must be considered a pioneering effort to create a Grand Touring car.

The Auto Union Type 52, as the project came to be known, was intended to be sold to customers for driving in long-distance races such as the Mille Miglia, or in sports car competitions such as the endurance races at Spa-Francorchamps and Le Mans. There was also talk of it being a factory racing car.

Sporty dynamics and everyday suitability

As early as the end of 1933, the Porsche design office drew up the first design sketches, which took on a more concrete form in 1934. The project managers decided to build a test car, but as far as we know today, it never materialised. The project was abandoned in 1935, and its trail lost in the archives of Audi and Porsche. But the developers left much ground-breaking work on paper. It was based on the technology of the Grand Prix racer that was developed at the same time; the chassis from the Auto Union Type 52 was designed as a ladder frame with a mid-mounted engine. The drivetrain of the Auto Union Type 22 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, the engineers reduced the gear ratio of the Roots supercharger. The Auto Union Type 52’s engine was to draw around 200 PS from 4.4 litres of displacement at 3,650 r.p.m. Its maximum torque of 4,450 k.g.f.-c.m. (436 Nm) was achieved at a moderate 2,350 r.p.m. Compared to the Grand Prix legend, this was a reduction in output, but the excellent performance of around 125 m.p.h., as calculated by the engineers, shows that the Schnellsportwagen would have lived up to its name. In its day, it would have been one of the most powerful street-legal vehicles on the road and in sports car competitions – truly a "rapid sports car."

Building the car: historical documents as the starting point

Audi commissioned Crosthwaite & Gardiner to build the Auto Union Type 52 using surviving archive documents, plans, and design sketches. The British restoration experts also curated the Silver Arrows for Audi’s historic vehicle collection and, after multi-year work, finished building the Schnellsportwagen in 2023. All components are custom-made and were handcrafted specifically for the model. At over five metres (16ft. 5in.) long, the Auto Union Type 52 makes an impact; its elongated silhouette reflects how its engineers designed the car for optimal aerodynamics and maximum performance. Unlike its Grand Prix siblings, the car is more suitable for everyday driving, as the designers intended, with an overhead roof, headlights, and room for luggage. There is also space for the two spare tires. But that is where the three-passenger car’s comfort features end. As is typical for a race car, the Auto Union Type 52 driver sits in the middle, with the rear passenger seats slightly offset to the side. With three passengers, 70 k.g. (154lb.) of luggage, and 150 k.g. (331lb.) of equipment, the technical data sheet lists the car’s total weight at 1,750 k.g. (3,858lb.), with an unladen weight of 1,300 k.g. (2,866lb.).

While the engine, transmission, and open five-speed gearbox were taken from the Grand Prix car, the engineers chose different technical solutions for the suspension and damping. Instead of a combination of transverse leaf springs and friction dampers like the Auto Union Type 22, the Type 52 uses longitudinal torsion spring suspension in combination with hydraulic dampers. During development, the 29-gallon fuel tank was relocated under the seats. In the Grand Prix race car, the significantly larger tank is located directly behind the driver in the vehicle’s center of gravity, giving the Silver Arrows an ideal weight distribution whether the tank is full or empty. Both the Auto Union Type 52 and the Type 22 use drum brakes on all four wire wheels.

Hans-Joachim Stuck comments...

Audi Tradition presented the Schnellsportwagen to the public for the first time at the Goodwood Festival of Speed in 2024, where it was driven by nine-times Le Mans winner Tom Kristensen and the multi-disciplined Hans-Joachim "Strietzel" Stuck. The latter’s father, Hans Stuck, went down in history as the “Hill Climb Champion” for his many victories in Auto Union Grand Prix race cars in the hill climbs popular in the 1930s. Hans-Joachim Stuck, speaking after his first test drive in the Auto Union Type 52: “When I occasionally drive the Auto Union Type C, which my father drove in his day, at Audi Tradition events, the excitement and fascination of the 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 sound is incredibly sonorous – like it came from an orchestra. And the design of the Auto Union Type 52 will practically blow you away – it’s genius!”

As if an appearance at the Goodwood hill-climb with two of the world's greatest living racing drivers wasn't enough, the Type 52 rounded off its début year by being named Bespoke Car of the Year at the International Historic Motoring Awards in December.

The challenges of building this one-of-a-kind model

The Auto Union Type 52 never reached a completed state in period, so there are no pictures of a finished model. During Auto Union AG’s dissolution in the Russian occupation zone following the Second World War, most of the historic Grand Prix racers disappeared, as did many files and photographs. Similarly, there are no verified reports from contemporaries that would allow conclusions to be drawn about the planned Schnellsportwagen’s final configuration insofar as there ever was one. However, the plans provide a clear vision of the direction of development and the goals the engineers were pursuing.

During the building phase, Audi Tradition and the experts at Crosthwaite & Gardiner were in constant and intensive communication, during which Timo Witt, Head of Audi’s historical vehicle collection, had to resolve a range of technicalities. Decisions for or against individual technical solutions had to be made. Witt, after finishing the car project, said: “One insight that came out of our intensive exchange is that the developers in the 1930s would probably have had to adjust some of the technical details in the course of testing, too. Similarly, we had to lengthen the Auto Union Type 52’s wheelbase compared to the original design documents because it was technically unavoidable in combination with other components such as the front suspension, engine, steering, and transmission. The interior is inspired by the Auto Union Grand Prix race cars, with a modern interpretation of colours and fabrics.”

None of the documents specified the colour the car would have had at the time. So, Audi Tradition again took the racing car as its foundation and chose Cellulose Silver for the finish. When it came to the engine that would power the Auto Union Type 52, Audi consciously decided to deviate from the designers’ original plan. Audi Tradition used the 16-cylinder engine from the Auto Union Type C; its output was not restricted to the Type 52 to ensure compatibility with the Grand Prix race cars. For that reason, the engine runs on a special methanol mixture. Based on the information handed down, which Audi Tradition has interpreted and implemented with considerable care, the Auto Union Type 52 is the closest approximation to the Schnellsportwagen that was imagined some 90 years ago but never built – until now!

 

We are indebted to Audi Tradition for allowing us to republish this article, and we hope for plenty of opportunities to see the Schnellsportwagen in action at future events.

Words: Audi Tradition
Photographs: Stefan Warter for Audi Tradition

Make a comment, ask a question, give your opinion, share additional information or start a discussion by filling in the fields below.