Mercedes-Benz
W 25 Grand Prix car

Why it matters

The W 25 was Mercedes-Benz's first car for the 750 kg Grand Prix formula and the first of the Silver Arrows. Designed under chief engineer Hans Nibel, it returned the company to the top of Grand Prix racing and took Rudolf Caracciola to the 1935 European Championship. Its supercharged straight-eight grew from 3.4 to 4.7 litres in three years, and its all-round independent suspension and hydraulic brakes were advanced for the period.

How rare is it?

Six separate kinds of rarity – never combined into one number.

Each kind of rarity is rated separately and never combined.

Production

Every figure says what it counts.

Independent counts (e.g. engine and colour) are never combined into a calculated figure. Surviving examples are never presented as original production.

History

Development began in spring 1933 and test drives started in January 1934 near Milan. The first W 25 won the Eifel Race on 3 June 1934 with Manfred von Brauchitsch. Legend says the car was a kilogram over the weight limit and that its white paint was sanded off overnight, giving the Silver Arrows their name. Six W 25s were built for 1934, with M 25 A and M 25 B engines, and two more were built for 1935.

The engine was enlarged in steps: 3364 cc in 1934, 3718 cc and then 3992 cc in the M 25 B from August 1934, 4309 cc in the M 25 C from July 1935, and 4740 cc in the ME 25 for 1936. In 1935 the car dominated the first European Championship season. For 1936 it was rebuilt with a shorter 2505 mm wheelbase, a de Dion rear axle and a transverse gearbox. Six short cars were built, but Auto Union's V16 cars proved superior and the team withdrew after the Swiss Grand Prix. The W 125 followed in 1937.

Technical specifications

Engine

Transmission & drivetrain

Chassis, body & dimensions

Performance

“Not yet verified” means no source has been checked for that value yet. Nothing is estimated to fill a gap.

Identification guide

How to tell an original from a replica or later conversion.

The W 25 can be identified by its pressed-steel ladder frame with two cross-braced U-profile longitudinal members drilled with hundreds of lightening holes, a supercharged inline eight with the blower and two pressure carburettors at the front, and a four-speed gearbox at the rear axle driven by a propeller shaft running at engine speed. Wheelbase is 2715 mm on the 1934 and 1935 cars and 2505 mm on the 1936 short-wheelbase car. The 1934 and 1935 cars have a swing rear axle on quarter-elliptic springs; the 1936 car uses a de Dion axle. The front axle has two T-shaped control arms per wheel and a coil spring housed in the axle tube. Engines are marked M 25 A, AB, B, C or ME 25 according to the stage of development.

Sources

Each number links to the exact facts it supports.

1. 1
   Mercedes-Benz Grand-Prix racing car W 25, 1934 (Classic M@RS) Level A Mercedes-Benz Group AG (Classic M@RS, Mercedes-Benz Public Archive)

   • a total of six W 25s were built
   • first version of the eight-cylinder ... called the M 25 A
   • supercharged inline eight-cylinder positioned as a front-mid engine
   • supercharged inline eight-cylinder
   • 78 mm x 88 mm and a total displacement of 3364 cc
   • two intake and exhaust valves per cylinder ... exhaust valves were sodium-cooled
   • Roots blower and the two hermetically sealed updraft carburettors
   • constantly engaged Roots blower ... dry forced induction
   • between 314 hp/231 kW and 354 hp/260 kW at 5800 rpm
   • 354 hp/260 kW at 5800 rpm
   • propeller shaft running at engine speed ... 4-speed gearbox
   • 4-speed gearbox
   • gearbox positioned on the rear axle and on to the differential
   • two multiple cross-braced U-profile longitudinal members made of pressed steel
   • Two T-shaped transverse control arms served as wheel control elements at the front
   • a swing axle ... quarter elliptical spring and a friction shock absorber
   • hydraulic actuation of the internal-expanding shoe brakes ... fitted all round

   Accessed 2026-11-12
2. 2
   Mercedes-Benz Classic public archive: Mercedes-Benz Grand Prix racing car W 25, 1934 Level A

   • 6 W 25s built for the 1934 season (races and record runs). The factory archive adds two more W 25s built for 1935 and six short-wheelbase W 25s for 1936 (separate archive pages)

   Accessed 2026-11-12
3. 3
   Mercedes-Benz Grand-Prix racing car W 25 SWB, 1936 (Classic M@RS) Level A Mercedes-Benz Group AG (Classic M@RS, Mercedes-Benz Public Archive)

   • a de Dion axle was now used
   • previous wheelbase was shortened from 2715 mm to 2505 mm
   • the W 25 weighed in at 847 kg

   Accessed 2026-11-12