Car Restoration Projects

The Auto Union Silver Arrows, legendary 1930s Grand Prix race cars, are a significant part of automotive history, but hardly anyone knows that a street-legal, sports-car derivative, with a detuned version of the 16-cylinder GP engine was planned, but never built. Until now.

In conjunction with British specialist vehicle restorers, Crosthwaite & Gardner, Audi has built one Auto Union Typ 52 Schnellsportwagen (fast sports car) and revealed it at the Goodwood Festival of Speed, in July 2024.

Firstly, some background. Auto Union AG was formed in 1932, when Audi, DKW, Horch and Wanderer merged, to combat the dominance of Mercedes-Benz. In the same year, rules were published for a new 750kg maximum-weight formula that would be used in Grand Prix races from 1934. (The idea was that this weight limit would encourage the use of smaller-displacement engines, but it didn’t work out like that.)

With a largish bag of money provided by Hitler’s German Government, Auto Union AG soon commissioned the Stuttgart design office of Ferdinand Porsche to develop a race car for the 750kg formula. Work on the Auto Union Type A began in March, 1933 and just one year later, Hans Stuck set a world record driving the car on the Avus circuit in Berlin.

Almost overnight Auto Union had become a motorsport contender and its new four rings logo was soon familiar to Brits and Europeans. In the years that followed, Auto Union set several world records, won numerous hill climbs, three German championships and the European championship in 1936, with the advanced Auto Union Type C.

When the highly government-subsidised, innovative Auto Union and Mercedes-Benz race cars burst onto the international racing scene, the legend of the Silver Arrows was born. Swift as arrows, these legendary powerhouses captivated audiences with their futuristic design and revolutionary technology. 

Mercedes-Benz continued with front-mounted engines, but Auto Union positioned the engine behind the driver. This mid-engine layout remains the standard in sports car racing and all open-wheel race cars today. 

The Typ 52 Schnellsportwagen 

While the Grand Prix race cars were being developed, Auto Union AG and the Ferdinand Porsche design office also planned a street-legal sports sedan. The concept plans called the vehicle Schnellsportwagen, apparently its intended marketing name. Today, with its distinctive characteristics, the car most closely resembles a classic supercar.

The Auto Union Typ 52, as the project came to be known, was intended to be sold to customers for driving in races typified by the Mille Miglia and the endurance races at Spa-Francorchamps or Le Mans. There was also talk of a factory race car.

The Porsche design office drew up the first design sketches that took on a more production oriented form in 1934. The project managers decided to build a test car, but as far as Audi knows, it never materialised. The project was abandoned in 1935, but much groundbreaking work on paper was filed in the archives of Audi and Porsche. 

These surviving documents show that the car was closely based on the technology of the Grand Prix race car, including its ladder frame and mid-mounted engine.  However, the compression ratio of the 295bhp 16-cylinder engine was to be reduced, to allow the car to run on regular petrol. At the same time, the engineers proposed reducing the drive speed of the Roots supercharger. 

In this detuned state, the Auto Union Typ 52’s engine was expected to produce around 200bhp from its 4.4 litres at 3650rpm. Peak torque  was calculated to be 436Nm at a moderate 22350rpm. 

Compared with the methanol-fuelled Grand Prix legend, this was a reduction in output, but the Schnellsportwagen was geared for excellent performance at up to 200km/h. It would have been one of the most powerful street-legal vehicles on the road.

The modern retro build

Audi commissioned Crosthwaite & Gardner to build the Auto Union Typ 52 and supplied this company with the surviving archive documents, plans and design sketches. The British restoration experts had prior Auto Union experience, having curated the Silver Arrow race cars for Audi’s historic vehicle collection.

The original Auto Union Typ 52 remained a design concpet, so there were no pictures of a finished model. However, the plans provided 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 regular communication, during which Timo Witt, Head of Audi’s historical vehicle collection, had to resolve a range of technicalities. 

“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,” said Timo Witt.

“For example, we had to lengthen the single-seat GP Typ A race car’s wheelbase, because it was technically unavoidable, to accommodate the front suspension, engine, steering and transmission for a three-seater car.

“The interior was inspired by the Auto Union Grand Prix race cars, with a modern interpretation of colours and fabrics.”

Similarly, Audi Tradition again took the race car as the foundation and chose Cellulose Silver for the finish. 

The choice of engine posed some difficulties, because Auto Union had never produced the planned detuned engine. Today, Audi Tradition has plenty of knowledge and experience with the methanol-fulled race car engines that power its Silver Arrows collection vehicles, so it was decided to give the Typ 52 a full-blown race engine.

While the engine, five-speed gearbox and final drive were taken from the Grand Prix car, the engineers chose different technical solutions for the suspension and damping. Instead of transverse leaf springs and friction dampers like the Auto Union Typ A, the Type 52 has longitudinal torsion spring suspension, in combination with hydraulic dampers. Both the Auto Union Typ A and the Typ 52 use drum brakes and wire wheels.

Unlike its Grand Prix siblings, the Top 52 is relatively civilised, with a roof, headlights and room for luggage and two spare tires. As is typical for a race car, the Auto Union Typ 52 driver sits in the middle, with the rear passenger seats slightly offset to the side. The 120-litre fuel tank is positioned under the saets.

With three passengers, 70 kilograms of luggage and 150 kilograms of fuel and equipment, the technical data sheet lists the car’s total weight at 1750 kilograms, with an unladen weight of 1300 kilograms.

All components were custom-made and hand-crafted specifically for the model. At more than five meters long, the Auto Union Typ 52 certainly makes an impact.

Its elongated silhouette reflects how its engineers designed the car for optimal aerodynamics and maximum performance.

On the road at last

Audi Tradition presented the Schnellsportwagen to the public for the first time at Goodwood in July 2024. 

“We are thrilled to present the Auto Union Typ 52 at the Goodwood Festival of Speed,” said Stefan Trauf, Head of Audi Tradition.

“This car gets people excited about design and technology. 

“For me, it is an absolute dream car, because it remained only a dream that we are now, 90 years later, able to bring to life. 

“The Auto Union Typ 52 demonstrates the ingenuity of its creators and the technological innovation of the time. 

“Being able to experience the Schnellsportwagen live is a great pleasure for me.”

The Auto Union Type 52 was driven at Goodwood by Le Mans record winner Tom Kristensen and racing driver Hans-Joachim Strietzel Stuck. The latter’s father, Hans Stuck, went down in history as Europe’s hill climb champion, following 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 Typ 52: 

“When I drive the Auto Union Typ C, which my father drove in his day, at Audi Tradition events, the excitement and fascination of motorsport fans is palpable. 

“It is a great honour and pleasure to drive the Auto Union Typ 52 at Goodwood for the first time. 

“The Schnellsportwagen is simply breathtaking and its sound is incredibly sonorous: like it came from an orchestra. 

“And the design of the Auto Union Type 52 will blow you away – it’s genius!”

Racing driver Hans-Joachim Stuck; Charles Gordon-Lennox, the Duke of Richmond; Le Mans record winner Tom Kristensen and Stefan Trauf, Head of Audi Tradition.

Technical data Auto Union Typ 52

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