The Mercedes-Benz W125 Rekordwagen was an experimental, high-speed automobile produced in the late 1930s. The streamlined car was derived from the 1937 open-wheel race car Mercedes-Benz W125 Formel-Rennwagen, of which also a streamlined version was raced at the non-championship Avusrennen in Berlin.

The main difference to the Grand Prix race car, which had to adhere to the 750 kg (1,653 lb) limit, was the engine. While the GP car had the 8-cylinder inline M125, which was rather tall, the record car was fitted with a V12 engine that was lower, which reduced drag.

The car is on display in the Mercedes-Benz Museum in Stuttgart.

1938 Mercedes-Benz W125 specifications

  • Engine: MD 25 DAB/3 60 Degree V12
  • Engine Position: Front Longitudinal
  • Aspiration: Twin Roots superchargers
  • Valvetrain: DOHC 4 valves per cylinder
  • Displacement: 5,576.75 cc / 340.31 in³ (82.0 x 88.0 mm)
  • Compression: 9.17:1
  • Power: 541 kW (736 PS; 725 hp) @ 5800 rpm
  • Power/displacement 131.97 PS (97.06 kW; 130.16 hp) per litre
  • Power/weight: 621.1 PS (456.8 kW; 612.6 hp) per tonne
  • Transmission: 4-speed manual
  • Engine cooling: Ice supplemented normal coolant as air intakes were

kept very small to improve aerodynamic flow over and around the car

The record

Rudolf Caracciola's record of 432.7 km/h (268 mph) over the flying kilometre on 28 January 1938, still remains the fastest ever officially timed speed on a public road as of 2010. It also was the fastest speed ever recorded in Germany until Rico Anthes bettered it with a Top Fuel Dragster on the Hockenheimring drag strip.

This record breaking run was made on the Reichs-Autobahn A5 between Frankfurt and Darmstadt, where onlookers were rattled by the brutal boom of the side spewing exhaust stacks as the silver car hurtled past. By nine that morning, Caracciola and team chief Alfred Neubauer were having a celebration breakfast at the Park Hotel in Frankfurt.

Sadly, popular driver Bernd Rosemeyer was killed later the same day when trying to beat that record for Auto Union. This also put an end to the record attempts of Mercedes, even though Hans Stuck later wanted to beat the overall land speed record with the Porsche-designed Mercedes-Benz T80 which was powered by a 3,000 horsepower (2,200 kW) airplane engine.