Mercedes-Benz W25 Monaco 1936

Mercedes W25, when the "silver arrow" overtook Alfa Romeo's P3

When FISA created a new regulation for the 1934 season responsible for limiting the weight of GP models to just 750 kilos, Mercedes saw a fantastic opportunity to develop a car with which to surpass the SSKs developed by Ferdinand Porsche at the same time. that swept away the hegemony achieved by the Alfa Romeo P3 during the first two editions of the European Drivers' Championship.

Talk about the car Mercedes-Benz W25 is to talk about the beginning of German domination in the European Drivers' Championship. Developed from 1934 until the very beginning of the Second World War, this was based on a constant duel between Mercedes and Auto Union while, below, as if it were a separate race, manufacturers such as Alfa Romeo, Maserati, Delage or Bugatti tried to save the furniture competing with each other for the middle positions.

In fact, reviewing the history of those seasons yields overwhelming results in relation to the success of the mechanics protected since the Third Reich. a domain especially visible in the case of Mercedes-Benz, which won three of the four editions held between 1935 and 1938.

What's more, although it may seem incredible, that German hegemony could only be challenged once when, in 1935, Tazio Nuvolari and his Alfa Romeo P3 achieved victory in German GP disputed at the Nürburgring.

Mercedes-Benz SSKL
The W25 marked a substantial advance over the huge, heavy SSKLs based on Ferdinand Porsche's work with the SSKs. Here we see one of them with Rudolf Caracciola at the controls after winning the Avus Cup in 1931.

One of the most epic feats in the career of the man from Mantua, who managed to surpass the much more performance W25 and Type B based on brave piloting to the point of suicide game.


By the early 1930s GP vehicles were becoming more and more powerful. So much so that the Association Internationale des Automobile Clubs Reconnus (AIACR) -predecessor of the current FIA- presented through the Fédération Internationale du Sport Automobile (FISA) a new regulation for the dispute of the European Drivers Championship.

Based on limiting the weight and not the displacement, this set a maximum of 750 kilos without fluids or tires for the 1934 season in which, paradoxically, the continental title was not disputed. Thus, those responsible for those races believed in how by reducing the result on the scale - the SSK reached 1.700 kilos with its 06-liter six-cylinder M7.1 engine - they could reach more acceptable powers for the tracks of the moment.

Mercedes-Benz W25 Carrera on Hill 1934
In addition to entering circuits, the W25 was used for hill races during its debut year in competition.

However, that had just the opposite effect. And, financed by the Nazi government - which had motorsports as its one of their propaganda means– Mercedes-Benz and Auto Union interpreted a technological escalation for which, just a few years later, they already greatly exceeded 500 HP with their W125 and Type C respectively.

Mercedes-Benz W25 Fagioli Monaco 1935
Fagioli with his W25 competing in the Monaco GP in 1935.

What's more, the 300 km/h barrier - not achieved in F1 until the seventies - was easily exceeded, reaching up to 380 km/h on exceptional occasions.


With Hans Nivel in charge of technical direction after the departure of Ferdinand Porsche in order to create the P-Wagen used by Auto Union, Mercedes-Benz presented in November 1933 its W25 adapted to the regulations of the European Drivers' Championship planned for the next year. And wow, the truth is that that meant a whole step forward regarding the SSKs evolved since 1928.

Not in vain, here we were not dealing with a vehicle adaptable to street or circuit. Far from it, that car was born for and for victory in the GPs of the moment with a design that is not only extremely light but also unexpectedly powerful.

Mercedes W25 Presentation in November 1933
Factory presentation of the W25 in November 1933.

With all this, while its empty weight was dangerously close to the 750 kilos imposed by the AIACR, its engine with eight cylinders in line, 32 valves, 3.360 cc and hemispherical combustion chambers delivered 354 CV to 5.800 rpm. All this with a double camshaft and fed by two carburetors and a Roots volumetric compressor capable of ensuring good performance even at low rpm.

Eifel 1934 Premiere Mercedes-Benz W25
Premiere in competition during the 1934 GP Eifelrennen.

In short, the Mercedes-Benz W25 was a machine outstanding and disruptive capable of inaugurating the peak of the “silver arrows”.


Although its debut on the circuit was expected on the Automobil-Verkehrs und Übungs-Strade (AVUS) layout - where thanks to its straights with four kilometers each one could easily develop top speeds -, the premiere in competition of the Mercedes-Benz W25 was delayed until the beginning of the summer of 1934, choosing the GP Eifelrennen as the stage.

Held since 1927 at the Nürburgring after having been raced on public roads, this was not only the first step of the new car in the world of racing but also his first chance for victory. From here, the trio composed of Luigi Fagioli - former pilot of the Maserati with 16 cylinders-, Manfred Von Brauchitsch and Rudolf Caracciola took victory in up to four relevant events including the Italian GP in Monza.

Spanish GP 1935 Lasarte
Starting grid of the 1935 Spanish GP held on the Lasarte track.

Likewise, during the return of the European Drivers' Championship the Mercedes-Benz W25 won in five of the seven scoring tests -including the Spanish GP held in Lasarte- to elevate Rudolf Caracciola as champion after having won four of those events.


While the European Drivers' Championship had marked a solid hegemony for Alfa Romeo and its P1932 in its 3 edition, the truth is that the new regulations announced for the 1934 season seemed having caught the Italian house on the wrong foot. What's more, in 1932 the Istituto per la Ricostruzione Industriale nationalized it to immediately outsource its presence on the circuits to Scuderia Ferrari.

W125 Premiere at Tripoli GP 1937
The W125 replaced the W25 for the 1937 season. Here we see it during its debut at the Tripoli GP.

Likewise, Adolf Hitler's own financial support for racing program performed by Mercedes-Benz and Auto Union launched at "Silver arrows" beyond the most optimistic forecasts.

In fact, the successes of the Mercedes-Benz W25 in 1934 and 1935 were followed by the victory of the Auto Union Type C in the 1936 European Drivers' Championship winning with Bernd rosemeyer three of the five qualifying GPs for that edition.

A real shock for the star's company, which replaced the W25 in 1937 with the presentation of the W125. Raised in its displacement to 5.6 liters, the new regulations planned for 1938 - limiting supercharged engines to three liters and naturally aspirated engines to 4.5 - determined it as a brief model having to be replaced by the W154; the greatest exponent of those GP Mercedes and, furthermore, protagonist in many world speed records.

Images: Mercedes-Benz Group.

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Written by Miguel Sánchez

Through the news from La Escudería, we will travel the winding roads of Maranello listening to the roar of the Italian V12; We will travel Route66 in search of the power of the great American engines; we will get lost in the narrow English lanes tracking the elegance of their sports cars; We will speed up the braking in the curves of the Monte Carlo Rally and we will even get dusty in a garage while rescuing lost jewels.

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