Sir Stirling Moss described the 1955 Mercedes-Benz 300 SLR as “The most fantastic car in the world”. A man considered by many as the greatest driver to ever live, Moss is well versed to make such a claim, having immortalised the 300 SLR in the 1955 Mille Miglia, setting the record which will never be broken. With such a start, the SLR was bound for greatness, but the tragedy at the 1955 Le Mans forced the prototype racers early retirement. Here is the story of the Mercedes-Benz 300 SLR’s rise and fall.
The brainchild of Rudolf Uhlenhaut, the genius who designed and engineered the Mercedes W125 and 300 SL, the 300 SLR was based on the W196 Formula 1 car rather than its road going sibling, the 300 SL. Fitted with one of the greatest engines ever devised, a fuel injected supercharged 3-litre inline-8, the power plant was positioned behind the front axle making the SLR front-mid engined, improving handling. Combined with a rear mounted fuel tank and gearbox, the SLR garnered the reputation of being one of the best performing machines on four wheels, with sublime handling, unparalleled high speed stability, near perfect weight distribution and immense power. Producing around 300hp fed to the rear wheels, the 300 SLR topped the scales at 900kg thanks to an aluminium spaceframe chassis and a featherweight magnesium Elektron body (the same material used to body the 1935 Bugatti Aérolithe concept).
In terms of design, the 300 SLR is a peculiar case. Sharing a clear visual lineage to its road going brother, the 300 SL, there’s an odd beauty to the SLR’s clear cut, form follows function shape. A design accentuated by wire wheels, an asymmetrical side exhaust, exaggerated headrests, a single vertically hinged driver’s door and a large bonnet bulge to clear the 33-degree canted engine, there’s an artistry to Uhlenhaut’s pragmatic design, a trait very few can achieve from a utilitarian prerequisite.
After the completion of nine 300 SLR chassis, the car debuted at the 1955 Mille Miglia, the race which would cement the SLR as one of the greatest cars of all time. Mercedes entered two 300 SLR’s in the race, one piloted by Juan Manuel Fangio, the other by Sir Stirling Moss and navigator, Denis Jenkinson. Released on half minute intervals, the cars were adorned with starting number. Moss’ car, starting at 7:22AM was adorned with the number 722. Favourites to win, Moss and Jenkinson did so, driving 1000 miles from Brescia to Rome and back on public roads in just 10 hours, 7 minutes and 48 seconds, smashing all previous Mille Miglia records, which due to the 1957 crash and cancellation of the race, will stand forever. An achievement thanks just as much to the 300 SLR as to Moss’ driving ability, the car averaged a huge speed of 99mph across the race, nearly touching 200mph on the stretch back to Brescia. The 1000-mile endurance race required cars to meet very specific requirements. Being a street race, cars had to be able to run flat out for extended periods of time whilst negotiating public roads, hairpin corners and humpback bridges, one which Moss hit at around 160mph, launching the car around 200 feet through the air. The large, powerful, stable SLR proved the perfect car for such a race with its sparse, functional design, truly brilliant engineering and technological achievement decades ahead of its time. Sir Stirling Moss’ Mille Miglia run, arguably the greatest feat of motor racing of all time, has inspired watches, clothing, artwork and even a series of special edition Mercedes-McLaren SLR’s. With such provenance, it’s no wonder Moss’ Mercedes-Benz 300 SLR 722 is today considered the most valuable car in the world.
Although Sir Stirling’s run in the 300 SLR is quite rightly remembered as the Mille Miglia’s greatest moment, Juan Manuel Fangio’s run should not be forgotten. Competing without a navigator, Fangio completed the 1955 Mille Miglia just 32 minutes behind Moss, a blistering time, enough to claim 2nd place, which may have claimed victory if Fangio wasn’t plagued throughout the race with engine problems, the power plant running on only 7 cylinders.
Whilst Mercedes observed the 300 SLR’s incredible aptitude in street races like the Mille Miglia and Targa Florio (where the SLR secured a 1-2 victory), the short lived SLR only competed in one major circuit race, the 1955 Le Mans, a race which would see the world’s worst motorsport disaster. The 7th year since the races halt due to WWII, Mercedes equipped the 3 300 SLR’s competing with a revolutionary airbrake. Essentially a large hatch above the fuel tank behind the driver’s head, the airbrake proved very successful in stopping the car and reducing wear on its enormous drum brakes. The first 34 laps of the race went past without inciendnt, until Mike Hawthorn turned his Jaguar D-Type sharply towards the pits, forcing Lance Macklin to take evasive action, sending his Austin Healey 100S into the path of Pierre Levegh’s Mercedes 300 SLR. Levegh struck the rear of the Austin Healey which acted like a ramp, launching the Mercedes into the crowd of spectators, killing 84 people, including Levegh and injuring 120 others. What followed were scenes of widespread devastation. As the SLR had broken into several pieces as it tumbled through the crowd, fuel and debris were spread along the grandstands. Worsening the truly horrific accident were the fire response crew who doused the alight magnesium body with water, sending hot magnesium onto the fleeing crowd. In response to the terrible accident, Mercedes-Benz immediately withdrew from the race, retiring from motorsport entirely until the 1980’s.
Whilst the 1955 Le Mans spelt the end of the 300 SLR’s racing career, the race bread machine was reborn as a road car. Two coupe versions of the SLR, commonly referred to as the Uhlenhaut Coupes were built, essentially road legal race cars capable of performing as the roadsters did, making them by far the fastest road cars in 1955. Originally built for competition, any plans for racing the prototype coupes were scrapped after the Le Mans tragedy. Rudolf Uhlenhaut himself used one of the coupes as a daily driver, once reportedly driving from Stuttgart to Munich in under an hour, touching 180mph.
Had the tragic events of the 1955 Le Man’s not occurred, the SLR would have likely became the most successful sports racing cars of the period, certainly possessing the performance and pedigree to do so. Despite its short life, the Mercedes-Benz 300 SLR remains to many the greatest car ever built, quite certainly the greatest of the 1950’s experimental race cars.