The record was broken on November 4, 2017.
Mercedes was driven by speed in the 1930s. This culminated in the W125 record. Rudolf Caracciola was the racing driver and the W125 twelve-cylinder monster set a new world record for speed on January 28, 1938. It clocked 432.7 kph (268.8 miles) over a kilometer on the German autobahn.
Mercedes celebrates the remarkable achievement nearly 80 years after it was made. It was largely unnoticed until just a few months ago. Koenigsegg and its Agera RS set a new world record last November with a speed of 276.9 mph (445.54 kph), over a flying kilometer. The W125 set the record for the flying miles with 432.4 km/h (268.74mph). This was also improved by Koenigsegg last season, when it set five records.
It is remarkable to see the W125 maintain their records for so long.
It had to be as smooth as possible. Four decades later, measurements in the wind tunnel showed that the body had a drag coefficient only 0.169. This figure is a good example of the world’s most aerodynamic (albeit limited) production car, the Volkswagen XL1. It had a drag coefficient of only 0.169.
Next came the engine. It was a 5.6-liter V12 that produced 765 horsepower (or 563 kilowatts in 1938). It was able to produce an additional 29 horsepower (21 kW), thanks to the addition of carburetors. The engine had been tested eight weeks prior in an unsuccessful record attempt. The engineers worked for a longer time to improve reliability and optimize the fuel/air mixture supply to each cylinder. The body was also redesigned from scratch to improve aero, and the aircraft manufacturers provided expertise.
The engine was equipped with a custom ice-cooling system. It consisted of the radiator placed in a container containing 48 liters (12.6 Gallons) of water and 5 kg (11 pounds) of ice. This brilliant idea was from the German test institute of aviation Berlin-Adlershof. It also had positive effects on aerodynamics, as the airflow through radiator would have increased its drag coefficient.
The new records set by Koenigsegg are unlikely to last another eight decades, considering that Bugatti’s Chiron and Hennessey’s Venom F5 announced plans to attempt to break the 300-mph barrier with their production cars. Koenigsegg even suggested that the Agera RS may break 300 mph. It seems like we are just beginning with top speed records.