• The original Mille Miglia racing car from 1955 at the Mercedes-Benz Museum
• Numerous controls for long-distance racing on public roads
• Racing sports car with Formula 1 technology clinches the world championship at the 1955 Targa Florio

“Close-up” – the name of this series from the Mercedes-Benz Museum says it all. Each instalment tells surprising, exciting and interesting stories about vehicles from the exhibition. On the occasion of the “70th anniversary of the 1955 motorsport season”, the focus this time is on the Mercedes-Benz 300 SLR racing sports car with number 722 in Legend Room 7: Silver Arrows – Races and Records.

No. 3/2025: Mercedes-Benz 300 SLR racing sports car “722”

An imposing number: The “722” stands out immediately. The large, red number shines on the front, sides and rear of the Mercedes-Benz 300 SLR racing sports car at the Mercedes-Benz Museum. This is one of the brand’s most famous racing cars – the Silver Arrow with which Stirling Moss and Denis Jenkinson won the Mille Miglia 70 years ago. What a successful racing début for the 300 SLR! The number stands for 7:22 am. That was the set time for the British team to leave the starting line on 1 May 1955. It was the beginning of an epic 1,000-mile road race from Brescia to Rome and back.

Made for the road: A Silver Arrow with indicators and lights, number plate and country identifier? The equipment of the 300 SLR in the racing curve in Legend Room 7 seems unusual for a motorsport vehicle. The dashboard even looks almost like something from a 1950s passenger car. But this is deceptive: the racing sports car was a thoroughbred competition vehicle based on the W 196 R Formula 1 racing car. Unlike the latter, the 300 SLR had road approval. It was built for long-distance races on public roads closed for this purpose, as well as for competitions on racing circuits.

Workplace: The Mercedes-Benz 300 SLR has a large array of controls. For example, a rotary switch to the left of the steering wheel activates the ignition and switches the parking, dipped and main beam headlamps in several stages. The starter button is located directly to its left. The indicator switch is located to the right of the steering wheel. The red control lamps for the indicators and ignition are to the right of the rev counter; the blue lamp for the main beam is to the left. By way of comparison, the W 196 R has just three round gauges and one switch.

Fresh air and sparks: In the 300 SLR, the driver also operates the fresh air flap with a lever at the bottom left of the dashboard, regulates cold starting with the choke on the far right behind the steering wheel, and keeps an eye on the warning indicator for the fuel reserve on the right below the rev counter. And finally, the Scintilla magneto ignition switch is positioned almost level with the front passenger. The choice between the settings 0, 1, 2 and 1+2 determines which magneto is switched on – or whether both work at the same time. The Swiss manufacturer Scintilla (Italian for “spark”) has been majority-owned by Bosch since 1954.

Full focus: The driver has a direct view of the large, centrally positioned Veglia rev counter through the steering wheel. The scale goes up to 11,000 rpm, with the red marker for the optimum engine speed at 7,000 rpm – that is where the three-litre M 196 S in-line eight-cylinder engine produces a continuous output of 203 kW (276 hp). To the left and right of the rev counter are smaller gauges for oil pressure and coolant temperature. The only thing the racing car lacks is a speedometer, because the motto is always this: drive as fast as the technology and route allow.

Three or four spokes: The perfection of Mercedes-Benz even allowed racing drivers to choose the steering wheel. 70 years ago, Stirling Moss opted for a three-spoke steering wheel in order to always have an optimum view of the instruments. Immediately after winning the Mille Miglia, the British racing driver was given the steering wheel as a souvenir. Instead, the mechanics fitted the four-spoke version in his racing sports car in 1955. Today, the 300 SLR “722” is once again equipped with an authentic reproduction of the three-spoke steering wheel. As a matter of honor, Stirling Moss always used his original 1955 steering wheel as a brand ambassador in this car.

Big “D”: The racing sports car has a large “D” on the boot lid. This is a clever detail in its own right: the country identifier for the Federal Republic of Germany can be flipped up and unlocks the hatch. There are two spare wheels underneath. For all the car’s roadworthiness, a rear silencer has been dispensed with and two open tailpipes trumpet their message on the right side of the vehicle. That is why there is no door there. Only the driver can get in and out more easily on the left with the help of a low, upswinging flap.

Just like in the saddle: A look inside the roadster reveals the unusual layout of the pedals. The accelerator and brake pedals are located to the right of the wide transmission tunnel, while the clutch is operated on the left. The upholstery of the bucket seat is covered in chequered blue gabardine fabric, also familiar from the 300 SL “Gullwing” (W 198). The side bolsters are covered with blue leather. In the transmission tunnel, the drive shaft rotates at up to 7,800 rpm and transmits the power of the eight-cylinder engine to the transmission on the rear axle.

Aerodynamic: The body of the 300 SLR is aerodynamically optimised. This also includes the two streamlined shrouds behind the head restraints. These can be folded up with a quick-release fastener. The one on the driver’s side exposes the fuel filler cap. A plastic windscreen protects the crew of the 300 SLR from the powerful airstream in the open-top racing car. In 1955, the material allowed for a frameless construction with a strong curvature, especially at the sides.

Full speed ahead with the pacenotes: Owing to the special pedal layout, the driver’s seat widens towards the front. The co-driver therefore has to make do with a narrower and lower bucket seat. Nevertheless, it is essential that the co-driver has a good view of the route. The navigation by co-driver Denis Jenkinson was a major factor in the victory in the 1955 Mille Miglia. The British motoring journalist read the details of the route out to Stirling Moss from a roll of paper held in a sturdy metal case screwed to the dashboard. An authentic reproduction of these pacenotes is on display in front of the racing curve as part of the Mercedes-Benz Museum’s “33 Extras” series.

At the limit: The British star racing driver got the utmost out of the 300 SLR in the 1955 Mille Miglia. Whether on narrow mountain passes, through towns or on long, flat straights, thanks to the navigating Jenkinson, he always drove at the limit. After 10:07:48 hours for the 1,600 kilometres and with a sensational average speed of 157.6 km/h, the two crossed the finishing line. “Almost 100 mph!” A magic number that Moss never forgot. The outstanding speed ensured a spectacular victory and the best time ever achieved at the Mille Miglia. Juan Manuel Fangio in second place in the overall rating completed the double triumph for Mercedes-Benz.

Car autograph: “We did it together – my thanks and affection”. Sir Stirling Moss wrote this dedication and signed his name on the silver paint of the bonnet directly in front of the driver’s seat on 19 May 2005, 50 years after his legendary victory. “The 300 SLR was the finest car ever built”, he said in 2015 about the vehicle, adding, “To drive this Mercedes was fantastic!” The racing driver’s life was inextricably linked with the 300 SLR. When he passed away on 12 April 2020 at the age of 90, Mercedes-Benz Classic honoured him with, among other things, the short film “The Last Blast”. It shows a unique drive of the “722” through London, the home of the great Mercedes-Benz racing driver and long-standing brand ambassador of Mercedes-Benz Classic. Link: https://media.mercedes-benz.com/article/0c4a0a8f-bb46-43f7-b578-fa5827b921a1/(lightbox:video/1db0357c-347e-4c0a-bf8b-231cab8b68c5)

Successful season 70 years ago: 1955 was the most successful motorsport season until then for Mercedes-Benz. After a dramatic finale in the Targa Florio in October, the 300 SLR (W 196 S) won the World Sportscar Championship for the brand. Fangio won his second Formula 1 World Championship in a row with the Silver Arrow W 196 R. 1955 also saw the serious accident at Le Mans with 83 fatalities, among them Mercedes-Benz works driver Pierre Levegh. However, the tragedy was not the decisive factor in the brand’s withdrawal from racing at the end of the 1955 season. The decision had been made beforehand because, from 1956 on, the company wanted to concentrate entirely on the development of new production vehicles. The 300 SLR enjoyed just one brilliant year on the racetrack.