Auto Union was an amalgamation of four German automobile manufacturers, established in 1932 in Zwickau, Saxony, during the Great Depression. The company has evolved into present day Audi, as an independent subsidiary of Volkswagen Group.
The trademark symbol of Auto Union was four overlapping rings, symbolizing the four member companies (all four in a line, in an attempt to avoid confusion with the five Olympic rings). The trademarks and company names of the member companies - Horch, Audi, DKW and Wanderer - were continued, with the four ring logo being integrated with the brand logo. The four ring logo of Auto Union is still a trademark, and now used by present-day Audi. Auto Union continued to market the two-stroke engined DKW brand until 1964.
Auto Union is best known for its racing team (Auto Union Rennabteilung, based in Zwickau), which was the main opponent of Mercedes-Benz in 1930s Grand Prix motor racing. The Silver Arrows of these two German teams dominated not only GP car racing from 1934 onwards, but set records that would take decades to beat. For example, the power levels of the unlimited 1937 models were only equalled in the early 1980s by turbocharged Formula One Grand Prix cars.
The Auto Union race cars were designed by the famous engineer Ferdinand Porsche; they were based on an earlier design he had done using a mid-engined layout similar to the famous 1923 Benz Tropfenwagen, or "Teardrop" aerodynamic design. (That unique car was built under the direction of Max Wagner, who was now at Daimler-Benz, and was raced by his current business partner, Adolf Rosenberger).
The mid-engined cars, where the drivers sat in front of the engines, were unusual; it took over 20 years until this concept, made famous in these cars, became generally adopted in motor racing. This was mostly because the cars were said to be hard to master, which was in part due to the swing axle rear suspension design initially adopted by Porsche (relatively advanced for its day, it is now utterly obsolete because of its many problems), although other factors (such as simple unfamiliarity with the very different handling characteristics) were also involved in creating that reputation.
The cars used supercharged engines that eventually produced almost 550 horsepower (which also contributed toward the handling difficulties, as it promoted oversteer which the cars already had in abundance). The engine was originally the V16 engine that Porsche had started designing earlier; when, starting in 1938, the maximum engine displacement for Grand Prix cars was limited to 3 litres for blown engines, it became a V12. It was originally designed to 6 litre specifications, but would start at 4,360 cc and . It had two cylinder blocks, inclined at an angle of 45 degrees, with a single overhead camshaft to operate all 32 valves. The cylinder heads were hemispherical, with the intake valves on the inside, directly connected to the camshaft through rocker arms. The rocker arms of the exhaust valves were connected to the camshaft by pushrods that passed through tubes situated above the spark plugs; thus the engine had three valve covers. The engine was designed to provide optimum torque at low engine speeds. (Bernd Rosemeyer later drove one around the Nürburgring in a single gear, to prove the engine was flexible enough to do it!)
The suspension would be all-independent but, unlike the Mercedes, would use parallel trailing arms and torsion bars at the front, while at the rear it initially used swing half-axles and a transverse leaf spring, the latter eventually being replaced by torsion bars, with radius arms added to absorb the torque. For the 3-litre V12 car, the rear suspension would be replaced with a de Dion suspension, following the lead of Mercedes-Benz but it was too late to do anything about the reputation the cars had gained.
The fuel tank was located in the center of the car, directly behind the driver (who would be placed well towards the front), so that the car's front-rear weight distribution would remain unchanged as the fuel was used - the exact same location used in modern open-wheel racing cars, and for the same reason. The chassis tubes were initially used as water carriers from the radiator to the engine, but this was eventually abandoned after they often sprung small leaks.
Much has been written about the difficult handling characteristics of this car, but its tremendous power and acceleration were undeniable - a driver could induce wheelspin at over ! A specialized hill climbing version of the car, equipped with dual rear wheels on each side to provide the traction needed to transfer this power, was built.
Additional work was needed on the car's cornering behavior; accelerating out of a corner would cause the inside rear wheel to spin furiously. This was much abated by the use of a Ferdinand Porsche innovation, a ZF manufactured limited slip differential, introduced at the end of the 1935 season. The body was subjected to strenuous testing in the wind tunnel of the German Institute for Aerodynamics.
The list of drivers for the initial 1934 season was headed by Hans Stuck; he won the German, Swiss and Czechoslovakian Grand Prix races (as well as finishing second in the Italian and Eifel Grands Prix), along with wins in a number of hill-climb races, becoming European Mountain Champion. (There was no European Championship for the circuit races that year, or he would have won that too). August Momberger placed second in the Swiss Grand Prix.
In 1935, the engine had been enlarged to five litres displacement, producing . Achille Varzi joined the team and won the Tunis Grand Prix and the Coppa Acerbo (along with placing second in the Tripoli Grand Prix). Stuck won the Italian Grand Prix (along with second at the German Grand Prix), plus his usual collection of hill-climb wins, again taking the European Mountain Championship. The new sensation, Bernd Rosemeyer, won the Czech Grand Prix (and managed a second at the Eifel Grand Prix and Coppa Acerbo).
For 1936, the engine had grown to the full 6 litres, and was now producing ; in the hands of Rosemeyer and his team-mates, the Auto Union Type C dominated the racing world. Rosemeyer won the Eifel, German, Swiss and Italian Grands Prix and the Coppa Acerbo (as well as second in the Hungarian Grand Prix). He was crowned European Champion (Auto Union's only win of the driver's championship), and for good measure also took the European Mountain Championship. Varzi won the Tripoli Grand Prix (and took second at the Monaco, Milan and Swiss Grands Prix). Stuck placed second in the Tripoli and German Grands Prix, and Ernst von Delius took second in the Coppa Acerbo.
In 1937, the car was basically unchanged and did surprisingly well against the new Mercedes-Benz W125, winning 5 races to the 7 of Mercedes-Benz. Rosemeyer took the Eifel and Donington Grands Prix, the Coppa Acerbo, and the Vanderbilt Cup (and well as second in the Tripoli Grand Prix). Rudolf Hasse won the Belgian Grand Prix (Stuck placed second). von Delius managed second in the Avus Grand Prix.
In addition to the new 3-litre formula, 1938 brought other challenges, principally the death of Rosemeyer early in the year, in an attempt on the land speed record. The famed Tazio Nuvolari joined the team, and won the Italian and Donington Grands Prix, in what was otherwise a thin year for the team, other than yet another European Mountain Championship for Stuck.
In 1939, as war clouds gathered over Europe, Nuvolari won the Yugoslavia Grand Prix in Belgrade (with a second place in the Eifel). Hermann P. Müller won the French Grand Prix (and took second in the German Grand Prix). Hasse managed a second place in the Belgian Grand Prix, and Georg Meier a second in the French.
Almost all of the original race cars were lost during or after World War II; after the war, since Auto Union was based in Zwickau, which was in East Germany, this contributed to the problem. One of the cars was brought to Moscow to study its technology. In 1976, the car was at the ZIL factory in Moscow and scheduled to be cut up for scrap metal. Viktors Kulbergs, president of Antique Automobile Club of Latvia, brought it to Riga and in 1997 it was fully restored and rebuilt by Crostwaite & Gardiner Buxted, England and Roach Manufacturing Ower, England. It is now on display at the Riga Motor Museum (Rīgas motormuzejs).
Audi has rebuilt some cars recently based upon remaining parts, plans and knowledge. A hill climbing version was recently rebuilt by the Audi factory, and toured the major car shows, driven by Hans Stuck Jr., son of the original driver Hans Stuck, and a long-time Audi race driver himself.
After the war, only the DKW brand was continued initially. All DKW cars had two stroke engines and front wheel drive. 1958 saw the return of the Auto Union brand, represented by the Auto Union 1000, a small saloon. At the same time the Auto Union 1000 Sp, a stylish coupé model, was produced for Auto Union by the Stuttgart coach builders, Baur. In impoverished postwar Germany, there was no place for luxury cars: the Wanderer and Horch brands never returned, but Audi did. Auto Union's pre-war rival Daimler-Benz acquired the business in 1958, and the six years of their ownership saw the creation of a range of cars that in the 1970s, (the Audi F103 series, the Audi 80, and the Volkswagen Passat), would provide the basis for a Volkswagen renaissance. Volkswagen Group purchased Auto Union in 1964: the Auto Union name, the two stroke engines and the DKW brand were all quickly dropped. The last DKW, the F102, received a new four cylinder four stroke engine. For F103, the Audi brand was revived. From now on, the Audi brand was used to denote cars manufactured by the Ingolstadt-based company. For a while, after being merged with Neckarsulm car maker NSU Motorenwerke AG the official name was "Audi NSU Auto-Union AG", which was simply shortened to "Audi AG" in 1985.
In 1947, Automobiltechnisches Büro (ATB) created the Sokol Typ 650 Formula Two racer in the German Democratic Republic, using the talents of chassis designer Otto Seidan and engine designer Walther Träger (both former Auto Union employees), along with spare Auto Union parts and resembled the Type D. As Awtowelo it was successfully tested but never raced.