One particular story marks the beginning of the chain of victories enjoyed by Mercedes-Benz in Grand Prix racing in the 1930s. For the 1934 season Mercedes-Benz built a monoposto with a supercharged engine to comply with the then applicable 750 kg formula: devoid of fuel, coolant, oil and tires, the curb weight of such racers should not exceed 750 kg. But upon their debut in the Eifel Race on the Nürburgring, and painted white as was obligatory for German racers, the cars were suddenly a couple of kilos too heavy.
To this day the experts still argue over whether it was Alfred Neubauer, the legendary racing manager at Mercedes-Benz, who in fact came up with the ingenious idea of getting the mechanics to grind off the white paint to reveal the silver-coloured metal, so ensuring that the requisite weight limit was reached. Or were the race cars actually already silver in colour when they arrived at the track? Neither the one theory nor the other has ever been proven – which does nothing to detract from the legend of the “Silver Arrows”. On the contrary.
Whatever the truth behind the story, the racer developed under the internal designation W 25 was immediately successful. Manfred von Brauchitsch won the Eifel Race and thus the first test of strength for the W 25. The W 25 went on to win one race after another until 1936, with meticulous refinements and adjustments made along the way to adapt it to the various race circuits. The output of the supercharged eight-cylinder in-line engine varied between 314 and 494 hp according to the fuel used and the intended purpose.
For the Daimler-Benz racing team, the 1934 season represented something of a learning curve. In the French Grand Prix at Monthléry, which followed the Eifel Race, the Silver Arrows drivers did not make it onto the podium. But in the next Grand Prix, the Germany round on the Nürburgring, Mercedes-Benz took second and fifth places. At the Grand Prix in Pescara, Italy, known as the Coppa Acerbo, Italian local hero Luigi Fagioli enjoyed a home win, while a further W 25 finished in sixth place.
Following a mediocre performance in the Swiss Grand Prix, Rudolf Caracciola, who up to that point had had a most unfortunate season, won the Italian Grand Prix at Monza together with Luigi Fagioli. After a bad accident in Monaco in 1933, Caracciola was still not fit enough to complete the full race distance, so handed over the wheel on the 60th lap to Fagioli – a practice that was quite common and perfectly acceptable at that time. Fagioli also won the Spanish Grand Prix at San Sebastian – ahead of Caracciola.
In the last Grand Prix of the season on the Masaryk circuit near the Czech city of Brno, the participating W 25s only managed to finish in second and sixth place. Nevertheless, the overall result for Mercedes-Benz at the end of the team’s first season of racing under the 750 kg formula had been a positive one: out of seven Grand Prix Mercedes-Benz had won four, together with a further three second places.
1935 was Rudolf Caracciola’s great year, as we recount in detail in the printed edition of the Mercedes-Benz Classic Magazine (Issue 3/2015, on sale since 11 November). It was the year in which Mercedes-Benz entered eleven races with the W 25 – and won nine of them. In six races alone Remagen-born Caracciola finished on the top step of the podium, so ending the season as European Champion in the 750 kg formula - a success comparable in significance with winning today's Formula 1 World Championship.
In 1936 the team from Auto Union brought tough opposition for Mercedes-Benz, and the European Championship that year was won by Auto-Union driver Bernd Rosemeyer. But the Mercedes team would not have been the Mercedes team if it had not learnt from such setbacks. For the 1937 season, held once again in conformance with the 750 kg formula, the Untertürkheim racing department developed the W 125. Its 5.6-liter eight-cylinder in-line supercharged engine delivered between 545 and 646 hp, an incredible figure at the time.
The first race of the season, the Tripoli Grand Prix in Libya, was straight away won by the ambitious Mercedes driver Hermann Lang. Rudolf Caracciola came sixth, followed by the Briton Richard Seaman in a W 125. The ‘free-formula’ race on the AVUS circuit in Berlin saw Mercedes-Benz enter several different vehicles, among them streamlined versions of the W 25 (with V12 engine) and of the W 125. In the end, the race was once again won by Hermann Lang. In the subsequent Eifel Race, four Mercedes Silver Arrows finished among the first ten.
After mediocre results in the Vanderbilt Cup in the US and the Belgian Grand Prix at Spa-Francorchamps, Caracciola went on to win the German Grand Prix on the Nürburgring ahead of von Brauchitsch. The Mercedes triumph in the ensuing Monaco Grand Prix was even more emphatic:
First, second and third places, as well as fifth place, went to the Mercedes-Benz W 125, with the victor this time von Brauchitsch ahead of Caracciola. The Coppa Acerbo saw the team take second and fifth places.
Once again, Rudolf Caracciola’s great hour had come. Driving the W 125, he won the Grands Prix of Switzerland, Italy and Czechoslovakia. Further outstanding placings for Mercedes-Benz in these three races made the triumph for the Untertürkheim racing team complete. In the final race of the season at the Donington track in England, von Brauchitsch and Caracciola finished second and third. 1937 finished with Caracciola once again as European Champion, this time with the Mercedes-Benz W 125.
The W 154, built according to the new 3-liter racing formula for the 1938 season, was the first twelve-cylinder auto from Mercedes-Benz. According to the new rules, supercharged engines should not have a displacement of more than 3 liters.
For the chassis and wheel suspension, the Mercedes-Benz engineers turned to proven technology, taking their cues from the successful W 125. The 2963 cc V12 was charged by two single-stage compressors, giving it a possible continuous output of 453 hp.
The brand-new W 154 immediately took second place at the first race of the season, the Grand Prix at Pau, in France. Then, at the Tripoli Grand Prix, Mercedes-Benz managed a one-two-three victory, with Lang winning ahead of von Brauchitsch and Caracciola. Again, the French Grand Prix in Reims saw three W 154s take places one to three, while first and second places for the 3-liter racers were the order of the day in the German Grand Prix. The Coppa Ciano in Livorno was won by Hermann Lang, while Caracciola remained unchallenged in the Coppa Acerbo.
Switzerland brought a further one-two-three triumph for Mercedes-Benz. A third place in Monza, then second, third and fifth places at Donington in England drew the 1938 Grand Prix season to a close. Rudolf Caracciola was the European Champion once again. For the 1939 season, Mercedes-Benz modified the 3-liter V12 in the W 154, increasing its continuous output to 480 hp with the help of a two-stage supercharger.
In the first Grand Prix of 1939, in Pau, France, Mercedes-Benz took first and second places. The Tripoli Grand Prix marked the first appearance for the 1.5-liter W 165 racer – developed in record time just for this race – which took first and second places. The Eifel Race on the Nürburgring was won by Hermann Lang, who also won in Belgium. Following the withdrawal of the W 154s at the French Grand Prix, Rudolf Caracciola went on to win the German Grand Prix on the Nürburgring.
The Mercedes team achieved a one-two-three victory in Switzerland. In the last race of the 1939 season – which was also the last Grand Prix before the Second World War – Manfred von Brauchitsch finished second. The outstanding driver of the 1939 season was Hermann Lang. Born in the Stuttgart suburb of Cannstatt and with an early career as a technician in the racing and testing department at Daimler-Benz behind him, Lang won five out of eight Grands Prix that year, thereby succeeding Rudolf Caracciola as European Champion.