Mercedes-Benz W25 Prototyp – Spark

1934 Mercedes-Benz W25 Prototyp
Spark - SP1039 (resin) 

Published 07/26/19

Up until the early 1930’s, Mercedes-Benz racing warhorse was the SSK. It was quite successful on tracks, but times were changing. For 1934, the Association Internationale des Automobile Clubs Reconnus (AIACR) introduced the “750 kg Formula”. This new formula for Grand Prix racing determined cars with a maximum dry-weight of just 750 kg. Also, the minimum race length would be 500 km. Since the SSK weighed considerably more than 750 kg, so Mercedes needed something totally new. This new car would be the W25. Project chief was Hans Nibe, with Max Wagner responsible for the chassis. The chassis was of a traditional box section type, with  cross-bracing. To make things lighter, it was extensively drilled. Covering the chassis was a streamlined body work of hand-beaten aluminum alloy painted in white.

The engine was the responsibility of Albert Heess and Otto Schilling. The new engine, called M25, was a traditional affair. It was an inline-8 with forged steel cylinders in 2×4-cylinder blocks with welded on water jackets. With DOHC and a Roots supercharger, initially (M25A) it had a displacement of 3360 cm³, producing 302 hp. Later on it was enlarged, with the last version (M25C) having 4310 cm³ and producing 402 hp. The supercharger pushed air into two carburetors, with a relief valve to vent out the surplus pressure. When the driver lifted the gas that created the famous high pitched Mercedes-Benz scream. A groundbreaking aluminum gearbox transmitted power to the road, placed in unit with the rear axle. The suspension was all-independent and hydraulically-assisted drum brakes provided stopping power.

Work on the W25 Prototyp started in March 1933 and the new car was ready for testing in February 1934. After initial shakedown Mercedes took the W25 Prototyp to Monza for track testing, but Manfred Von Brauchitsch had a tire failure and crashed. Then in April another pilot crashed the second car at Nürburgring after having problems with the differential. Despite the rocky start, the car was ready for the IV Internationalles AVUSrennen on May 27th. However, after having serious problems with the carburetors, Mercedes withdrew their three cars right after practice. With that, the W25 officially debuted on race tracks in early June, at the VIII ADAC Eifelrennen, at Nürburgring. The team had three cars in the race, and Von Brauchitsch’s #20 finished in first place. In late 1934 Mercedes even developed a LSR version of the car, the unique Rennlimousine.

Being the W25 Prototyp, it’s the very first Silberpfeil from Mercedes-Benz. Ironically, it’s NOT silver, but white, since Mercedes only officially adopted silver after Nürburgring in June. The story that Alfred Neubauer had the white cars stripped of the white paint to save weight is just legend. According to Neubauer’s autobiography, the term Silberpfeil came up after the W25 raced in silver that day. But the fact is that the term showed up in the specialized press years before. And more importantly, the Nürburgring race was actually a Formula Libre race, so the cars were not limited to 750 kg.

Even if Neubauer wasn’t 100% correct in his memoir, the model is 100% awesome. It’s Spark at its finest, and a treat to a Silberpfeil nut like me. I think it’s a new release from Spark, and being a Silberpfeil, not something for everybody. Since it’s not exactly plentiful, if you find one, jump on it. I have the feeling that this one will be rare in the future.