On this early winter morning in 2004, several snowflakes swirled between two sunbeams on a private Mercedes circuit in the heart of Stuttgart. In the hangar, which is very warm, we are waiting for one of the rarest, but also one of the most formidable road cars of the brand with a star. : 1955 Mercedes 300 SLR coupe. Exceptional, meeting this Mercedes is exceptional in many ways. Beneath its exterior, reminiscent of a standard 300 SL, this “R” variant hides a real racing engine borrowed from the F1 eight-cylinder Mercedes that Fangio won the world championship in in 1954 and 1955. that the owner, even the car manufacturer, is willing to entrust a steering wheel of such rarity to anyone. Moreover, in almost 70 years of life, this 300 SLR has seen hardly thirty drivers… and two journalists… We cannot thank Etoile for this exceptional sign of trust.
Long preparation required
Obviously, for this trial run, we are accompanied. In this case, Gert Straub, the engineer responsible for the maintenance and use of the vehicle. It is he who begins the heating procedure. Turn the ignition key, turn on the fuel pump and start the starter: damn, never heard such a rumble! Competition obliges, intake and exhaust couldn’t be more direct. It’s not like anything known, it’s not music, but it’s certainly impressive, even terrifying. The first few minutes stabilized at 3000 rpm, then three more with a puff of gas to 6000 rpm, and the engine is silent. No, no problem. But after warming up the engine, it is necessary to put in “cold” spark plugs, the only ones capable of ensuring operation at a stabilized temperature.. The mechanic opened a large hatch at the bottom of the right front fender and began to change 16 spark plugs! Yes, in addition to using innovative mechanical direct injection, this inline eight has dual ignition.
Spark plug change done, 300 SLR coupe reaching out for me. Despite the butterfly doors, access requires some flexibility, which is not my forte.. To make matters worse, a huge transmission tunnel (approximately 70 cm) separates the brake pedal from the clutch pedal because the engine block, tilted to the left for better aerodynamics, imposes a diagonal gear shaft passage under the driver’s seat. . Without a seat belt, sitting with legs wide apart, hands resting on a huge steering wheel, I worry about the quality of the brakes. “These are four large ventilated drums with a hydraulic booster. It works very well with one caveatsaid Gert Straub, smiling at me.Help is proportional to speed. Over 200 km/h it brakes very well, but at low speed… it’s better to pump and push hard! For the gearbox, the five gears are synchronized, but it still squeaks a little. And then the grid is a little special: the first is at the top left, the second is in the middle at the bottom, the third is in front, the fourth is at the bottom right, and the fifth is in front. Plus, it’s a vintage clutch. Therefore, it is forbidden to force him to skate. You turn on 3000 rpm and then suddenly let go. Let’s go to ?“
ten minutes delay
OK, let’s go, 3000 rpm, let go of everything: almost without losing momentum, The 300 SLR Coupe gains momentum. If this 8-cylinder engine does not like to work below 2500 rpm, then above 4000 rpm it shows amazing power and really explodes after 6000 rpm., and to the switch located at 7800 rpm. Admittedly, thanks to a lightweight chassis and body made of magnesium and aluminum alloy (80%-20%), this 300 SLR coupe weighs just over 1,100kg. But even after 50 years, rare sports cars are able to accelerate with such force and not lose traction, despite the bitumen temperature close to 0ºC.
Evil, this engine is also for the ears. Because after ten minutes of this shock treatment, the insistent whistle made me wish I had given up on the noise canceling plugs. If, despite the firm but fairly precise steering, the chassis seems to digest 310 hp without much difficulty. and not too tight corners, braking inevitably dates this silver arrow. Lack of bite, obligatory pumping and insufficient power: this is undoubtedly the weak point of the machine. Perhaps, as Gert told me, it improves above 200 km/h, but out of respect for this almost unique object, and not so much for lack of courage, I did not want to try.
Deprived of competition by a dramatic crash that killed 81 spectators at the 24 Hours of Le Mans on June 11, 1955, Rudolf Uhlenaut, the designer of this unique barquet, worked alternately on the development of road cars, then on the C 111 equipped with a rotary piston engine . However, he did not give up on his two 300 SLR coupes, which he had long used as ultra-fast utility vehicles. Unaware that one of them will be the most expensive car in the world in 2022…
1955 Mercedes 300 SLR Coupe data sheet
- Engine: 8 cyl. inline, 16 s, 2982 cc
- Power: 310 HP at 7400 rpm.
- Torque: 317 Nm at 5950 rpm
- Transmission: rear, mechanical 5 speed.
- Dimensions (L/W/H): 4.35/1.75/1.21 m
- Tank: 155 l
- Weight: 1117 kg
- Maximum speed: 284 km/h
- Average consumption: approx. 30 l/100 km