1971 Mercedes 300 SEL 6.8 AMG meets S63 AMG showcar

Two very special S-Class models from the AMG stable meet at the Spa-Francorchamps, Belgium.

1971 300 SEL 6.8 AMG finished in second place at the 24-hour race in Spa-Francorchamps on 25 July 1971. This surprised everyone as the car weighed 3,600 lbs and still featured stock air suspension and even exotic wood trim. It was the heaviest car on the track, but the mighty 6.8-liter AMG engine offered plenty of power on long straights to finish before lightweight sports cars.

Next to the old racing touring car from 1971 we have the new S63 AMG showcar with identical sponsoring and the start number “35”. In the heart of the Mercedes S63 AMG “Thirty Five” is a new hand built twin-turbo 5.5-liter V(, that in stock condition produces 544 horsepower and 590 lb-ft of torque.

Inside the showcar this engine is tweaked to 571 horsepower and 664 lb-ft of torque. The engine is mated to a wet clutch Speedshift MCT 7-speed transmission with full manual mode, taking the big sedan from 0-60 mph in an amazing 4.3 seconds.

For all the little details about both cars take a look at the very long press release after images.

Press release:

Spa-Francorchamps (Belgium) – Wide, spectacular and clad in an authentic racing car outfit – two very special S-Class saloon models from the AMG stable. One is the racing touring car of 1971, the 300 SEL 6.8 AMG, and the other is the S 63 AMG showcar. With identical sponsoring and the memorable start number “35”, the new high-performance model is a reminder of an historic success: on 25 July 1971, the bright red four-door saloon crossed the finishing line in second place at the 24-hour race in Spa-Francorchamps. This triumph in the car’s very first race made AMG world-famous overnight.
The highly experienced Hans Heyer and Clemens Schickentanz took turns behind the wheel of the AMG touring car. AMG was anything but the favourite to win this classic Belgian long-distance race: it faced the mighty opposition of the Ford Capri RS, BMW 2800 CS, Chevrolet Camaro, Opel Commodore and Alfa Romeo GTA. Nobody expected that the large luxury saloon from Affalterbach in provincial Swabia would be able to keep up with the well-established teams.
5th place in the starting line-up for AMG

The red four-door saloon already showed its potential in training, when Clemens Schickentanz surprised everyone with the fifth-fastest training time. Indeed nobody at AMG had expected fifth place in a starting line-up of 60 cars. 80,000 spectators wondered about the fast, red saloon with its long wheelbase – the only Mercedes taking part in the race. Pole position was occupied by the favourite, the Chevrolet Camaro driven by Ivo Grauls and Peter Hoffmann, followed by the Alpina-BMW 2800 CS of Niki Lauda/Gérard Larousse, then the first works Ford Capri with Dieter Glemser and Alex Soler-Roig, and the Schnitzer-BMW 2800 CS piloted by Rauno Aaltonen and Helmut Kelleners. All in all, 60 racing touring cars were seeking to beat the stopwatch on the then 14.1 kilometre course in the Ardennes, driven by well-known names such as Hans-Joachim-Stuck, Jochen Mass, Toine Hezemans, Willy Kauhsen, Achim Warmbold and Rainer Braun.

On the first lap, driver Hans Heyer in the 300 SEL 6.8 AMG was able to manoeuvre into 3rd place right behind the Ford Capri (Glemser/Soler-Roig) and the Chevrolet Camaro (Grauls/Hoffmann). After a turbulent race with a rainstorm at midnight and numerous breakdowns, the “35” finally crossed the finishing line in second place behind the works Capri driven by Glemser/Soler-Roig. The AMG saloon had absolved exactly 308 laps in the 24 hours. Technical problems: none at all. A sensational result.

Top speed of 265 km/h and exotic wood trim in the cockpit
Hans Heyer looks back fondly on this race: “We knew we could win, but the others did not know that yet!” The AMG saloon was unbeatable on the straight, however the braking system substantially adopted from the standard model had problems coping with the weight of the car (1635 kilograms). “But on the old Spa course the discs had plenty of time to cool down, and nobody was able to catch us on the long straights,” the now 67 year-old reminisces. With a top speed of 265 km/h, the 300 SEL 6.8 AMG was tailor-made for the fast Belgian track. The interior had a luxurious atmosphere with its standard appointments such as power steering, air suspension, carpets, panelled doors and a dashboard with exotic wood trim. The spectators along the trackside enthusiastically cheered the large saloon with its unmistakable V8 sound. “The outsider quickly became the public’s favourite,” says Hans Heyer.

The AMG racing saloon was technically based on the Mercedes-Benz 300 SEL 6.3. With an engine output of 184 kW (250 hp) at 4000 rpm and a top speed of 220 km/h, this luxury saloon was Germany’s fastest regular production car at the time. It was not only an enlarged displacement from 6330 to 6835 cc that increased the output to 315 kW (428 hp) at 5500 rpm, and torque from 500 to 608 newton metres. AMG co-founder Erhard Melcher “tweaked” the eight-cylinder power unit using classic methods: high-precision camshafts and modified rocker arms, lighter connecting rods, new Mahle pistons, larger intake valves, modified combustion chambers, polished intake and exhaust ducts, a new intake tract with two throttle flaps and a racing exhaust system ensured a better gas throughflow and made higher engine speeds possible. Endurance was improved by installing an additional oil cooler and finely balancing the crankshaft.

The wings were flared to make room for the lightweight size 10 x 15 and 12 x 15-inch magnesium wheels adopted from a C 111 test car. Aluminium doors helped to reduce the car’s weight from the original 1830 to 1635 kilograms. Larger front wishbones, a more robust rear axle with a heavy-duty differential and smaller, stiffer suspension air bellows made the saloon fit for the racetrack.

Sensational success reported on German TV news
The unexpected success in the 24-hour race at Spa-Francorchamps made AMG, which was founded in 1967, well-known overnight – and marked the start of an impressive success story. Even the German TV news “Tagesschau” reported on this sensational result. “It really was a sensation at the time,” AMG founder Hans Werner Aufrecht remembers. The courage shown by Aufrecht and his partner Melcher in entering such a car in the classic 24-hour race had been well rewarded.
Afterwards the 300 SEL 6.8 AMG took part in the 2×6 hour race at Paul Ricard on 11 and 12 September 1971, accompanied by a privately entered 300 SEL 6.3 with an AMG engine. In March 1972, now repainted in yellow, the 300 SEL 6.8 AMG took part in the trials for the Le Mans 24-hour race, but did not take to the starting line for the June race. The car was however entered in the 24-hour race at the Nürburgring in June 1972, and in the Nuremberg 200-mile race at the Norisring on 6 August 1972, where Hans Heyer took first place in the “Standard and special touring cars above 2000 cc” category with the four-door saloon, which had meanwhile been painted red again. The success story of the 300 SEL 6.8 AMG came to an end there: a rule-change by the Fédération Internationale de l’Automobile (FIA) put the brakes on this muscular racer, as only cars with an engine displacement of up to five litres were permitted to enter European Touring Car Championship races in future. AMG sold its racing saloon to the French Matra group, where it was converted for high-speed tests on aircraft tyres. Its subsequent fate is unknown. In spring 2006 Mercedes-AMG built a replica of the 300 SEL 6.8 AMG according to the original drawings, so as to keep this unique success story alive.

Spectacular S 63 AMG”Thirty-Five” showcar in the style of the racing touring car
Like its historic predecessor, the new S 63 AMG showcar does not fail to attract attention. Eye-catching details include the imposing tyre sizes of 275/35 R 20 and 325/30 R 20 at the front/rear, and the 4.5 cm flare on each wing. The start number 35 and practically all the sponsoring stickers follow the original. Instead of fire-red non-metallic paintwork, the body of the showcar is finished in “AMG Le Mans red metallic”, a colour available exclusively for the new SLS AMG. The functional interior is enhanced with black/carbon-fibre piano lacquer trim. A rollover cage, two AMG sports bucket seats with four-point seat belts and an AMG sports steering wheel lined in leather/Alcantara underline the racing touring car look. This spectacular showcar provides an outlook on the series production version of the new S 63 AMG, which is due to be launched in September 2010.

“AMG Performance 2015” as the continuation of a success story
The car is powered by the new AMG 5.5-litre V8 biturbo engine and the AMG SPEEDSHIFT MCT 7-speed sports transmission. Mercedes-AMG is continuing this impressive story with its “AMG Performance 2015” strategy, and meeting its promise to continuously reduce both the fuel consumption and emissions of new models with the new engine/transmission combination – while reaching new heights with the central brand value of “performance”.
The new AMG 5.5-litre V8 biturbo engine will play a major part in the Mercedes-AMG model strategy over the next few years.

7-speed sports transmission will also guarantee a thrilling yet economical power transfer in future AMG high-performance cars. The new engine/transmission combination is another milestone in the success story of Mercedes-AMG, which
began in 1967. Another highlight in the company’s more than 40 year history is undoubtedly the SLS AMG: this gull-wing model which was launched in March 2010 is the first automobile to be completely independently developed by Mercedes-AMG. It means that as the performance brand within Mercedes-Benz Cars, AMG is not only fielding a masterpiece but also demonstrating development expertise at the highest level.

Direct petrol injection with spray-guided combustion and twin turbocharging
With an overall displacement of 5461 cc, the new AMG 5.5-litre V8 biturbo unit makes do with exactly 747 cubic centimetres less compared to the naturally aspirated AMG 6.3-litre V8 with a displacement of 6208 cc. In addition to downsizing, AMG is also utilising the advantages of direct petrol injection with spray-guided combustion and piezo-electric injectors: thanks to its higher thermodynamic efficiency, this technology makes more efficient use of fuel and leads to lower exhaust emissions. AMG combines this spray-guided combustion with twin turbochargers. Other highlights include a crankcase wholly of aluminium, four-valve technology with adjustable camshafts, an air/water intercooler, generator management and a start/stop function as standard.

This high-tech package leads to a high output and torque yield, together with fuel consumption figures that are unrivalled in the competitive lineup. The AMG 5.5‑litre V8 biturbo engine develops a peak output of 400 kW (544 hp) and maximum torque of 800 newton metres. In conjunction with the AMG Performance package these figures are increased to 420 kW (571 hp) and 900 newton metres. The major difference between the two performance classes is an increase in the maximum charge pressure from 1.0 to 1.3 bar. A look at the performance diagrams shows that no other engine in this output class achieves the figures delivered by the new AMG biturbo.

Quantum leap: fuel consumption reduced by 25 percent
With a provisional NEDC fuel consumption of 10.5 litres per 100 kilometres, the new S 63 AMG is 3.9 litres more economical than the preceding model powered by the naturally aspirated AMG 6.3-litre V8 – despite an increase in output by 14 kW (19 hp) resp. 34 kW (46 hp) and in torque by 170 and 270 newton metres. Engine specialists consider this achieved fuel saving of more than 25 percent to be nothing less than a quantum leap. CO2 emissions have likewise been significantly reduced: at 246 grams per kilometre, the figure is 28.5 percent lower than for the previous model. Both performance variants have identical fuel consumption and CO2 figures.

With figures like these, the new S 63 AMG is not only considerably better than all its competitors, but also more fuel-efficient than much less powerful cars in this segment.

In some cases, in terms of its enormous output and torque figures, the new AMG 5.5-litre V8 biturbo engine is twice as efficient as many a medium or compact class diesel engine.

At the same time the S 63 AMG delivers superior performance at sports car level: the high-performance saloon accelerates from zero to 100 km/h in 4.5 seconds, and has an electronically limited top speed of 250 km/h. The 100 km/h mark is reached in just 4.4 seconds with the AMG Performance package, with the top speed increased to an electronically limited 300 km/h.

Engine production – tradition of hand-built excellence
Like all AMG engines, the new eight-cylinder biturbo is assembled by hand in the AMG engine shop taken into commission in 2002. A single, highly-qualified technician assembles the M 157 according to the “one man, one engine” philosophy, maintaining the very strictest quality standards – as attested by his signature on the characteristic AMG engine plate.
Key data at a glance*:

AMG 5.5-litre V8 biturbo engine

5461 cc
Bore x stroke

98.0 x 90.5 mm
Compression ratio


400 kW (544 hp) at 5500 rpm
420 kW (571 hp) at 5500 rpm**
Max. torque

800 Nm at 2000-4500 rpm
900 Nm at 2500-3750 rpm**
Engine weight (dry)

204 kg
Power/weight ratio

0.41 kg/hp
0.39 kg/hp**
* provisional figures; ** with AMG Performance package

Exciting power delivery, characteristic sound
These figures raise high expectations which the 400 kW (544 hp) AMG 5.5-litre V8 biturbo certainly meets. The flat torque curve ensures enormous pulling power in all speed ranges: 670 newton metres are already available at 1500 rpm, and the maximum torque of 800 newton metres is delivered just 500 rpm later, remaining constant to 4500 rpm. Even more effortless performance is ensured by the engine variant with the AMG Performance package, which has a peak output of 420 kW (571 hp). In this case the eight-cylinder delivers 875 newton metres of torque at just 2000 rpm, with a constant 900 newton metres available between 2500 and 3750 rpm.

It is not only the unrivalled torque delivery of this turbocharged eight-cylinder that makes the heart beat faster, as the agile responsiveness with no irritating charger delay leads to an effortlessness and dynamism previously unknown in this output class. All perfectly matched by the characteristic, sonorous engine note. Moreover, this AMG high-performance engine naturally meets all the requirements with respect to smooth, quiet running and the comfort on long journeys that is to be expected of a Mercedes.

MCT 7-speed sports transmission with Controlled Efficiency mode and start/stop function
Power is transferred by the AMG SPEEDSHIFT MCT 7-speed sports transmission used exclusively by AMG, which is already familiar from the SL 63 AMG and E 63 AMG and combines high emotional appeal with outstanding driving dyna-mics and a high level of efficiency. The wet start-up clutch replaces a conventional torque converter, and helps to save fuel. The exemplary fuel economy is also in large measure due to the standard start/stop function. This system is active in the transmission’s Controlled Efficiency (“C”) mode, and switches the eight-cylinder engine off when the car comes to a stop. In “C” mode the sports saloon always starts off in second gear, and the transmission shifts to the next, higher gears at a decidedly early stage. With its high torque at low engine speeds, the V8 engine encourages a smooth, effortless driving style.

The eight-cylinder biturbo engine also features the generator management system familiar from the E 63 AMG: whenever the engine is on the overrun or when braking, kinetic energy is used to charge the battery rather than being wasted as heat in the usual way. In all other operating modes a combination of onboard network and generator management enables the generator to be kept at a low voltage. This reduces the load on the engine and makes for fuel savings of around 0.15 litres per 100 kilometres according to the NEDC standard, and up to 0.2 l/ 100 km in city traffic with its frequent overrun and braking phases.

Long tradition of powerful AMG V8 engines
Powerful eight-cylinder engines are an inseparable part of AMG’s corporate history. One milestone in this history was the M 117, the first eight-cylinder with four-valve technology: with a displacement of 5.6 litres, 265 kW (360 hp) and 510 newton metres of torque, this V8 accelerated the Mercedes-Benz 300 CE 5.6 AMG to a top speed of 303 km/h in 1987. This made the coupé Germany’s fastest series-production car; American AMG fans reverently christened it “The Hammer”. Another important engine in the history of AMG was the supercharged AMG 5.5-litre V8 introduced in 2001: the M 113 K developed an output of up to 428 kW (582 hp) and torque of 800 newton metres. The supercharged AMG 5.5-litre V8 in the SLR McLaren of 2003 was even more powerful – it developed up to 478 kW (650 hp) and 820 newton metres. 2005 saw the debut of the AMG 6.3-litre V8 engine; depending on the model, the naturally aspirated, high-revving M 156 developed up to 386 kW (525 hp) and 630 newton metres. Exclusively reserved for the new SLS AMG, the likewise 6.3-litre M 159 has a maximum output of 420 kW (571 hp) and maximum torque of 650 newton metres.

The supercharged AMG 5.5-litre V8, the AMG 6.3-litre V8 and the AMG 6.0-litre V12 biturbo were all able to win the Best Performance Engine category in the International Engine of the Year Awards.

Hans Heyer highly successful in touring car and sports car races
Hans Heyer, born in Mönchengladbach on 16 March 1943, has taken part in 1000 races in more than 35 years of motorsports. He has competed as a works driver for many brands, including AMG-Mercedes, Ford, Lancia, Porsche, Jaguar and BMW. Heyer is Germany’s most successful Go-Kart driver of all time, winning four European championships, two world vice-championships, four German championships and two Dutch championships. He won the precursor to the DTM series three times, the German motor racing championship and achieved three first places in the 24-hour race at Spa-Francorchamps. In 1974 he crowned this successful career with the European touring car championship title.

Heyer was also very successful with prototype sports cars, with victories including the 1000-kilometre races in Monza, Mugello, Kyalami and on the Nürburgring. He also competed in the 24-hour race in Le Mans several times, and became sports car brand world champion in 1976 and 1980. In 1977 Hans Heyer even competed in a Formula 1 race for ATS.
In 1985 Hans Heyer took to the starting line for the Paris–Dakar marathon rally, winning the truck category and taking 28th overall place. In 1986 and 1987 Heyer worked as a development and test driver for the AMG-Mercedes team, and also as racing manager in 1988 and 1989. In 2004 Hans Heyer announced his final retirement from active racing after his 1000th race. His son Kenneth, aged 29, has followed his father’s footsteps and is entering the ADAC GT Masters and the FIA GT European championships in 2010.

Tyrolean hat as a trademark
Hans Heyer’s trademark was his Tyrolean hat: he elevated this striking head cover into a trademark over several decades – and it also “opened doors” for him automatically. “There were times when I did not need to show identification for
anything. My hat was so well-known that I got in everywhere, even at Formula 1 events.”

Clemens Schickentanz still active today
The greatest sporting successes of Clemens Schickentanz, born on 24 May 1944 in Coesfeld, include overall victory in the first ever 24-hour race on the Nürburgring in 1970, together with Hans-Joachim Stuck. Even more publicity was assured by the second place with the 300 SEL 6.8 AMG at the 24-hour race in Spa-Francorchamps with Hans Heyer in 1971. In 1973 Clemens Schickentanz won the GT European championship and the Porsche Cup; at the 24-hour race in Le Mans he took 3rd and 4th place in 1973 and 1983. His race record is also studded with numerous victories in 1000 km races. Clemens Schickentanz has never officially ended his active carer as a racing driver, and still appears on the starting line for classic car races.

The driver duo of Hans Heyer/Clemens Schickentanz was not only successful with the Mercedes-Benz 300 SEL 6.8 AMG. In 1978 they drove the new 450 SLC 5.0 AMG in the European touring car championships. At the end of the season they had achieved two third places in Monza/Italy and on the Salzburgring in Austria. In 1980 Clemens Schickentanz alternated with Jörg Denzel behind the wheel of the silver coupé. After a second place in Monza, they achieved their first victory in the Touring Car Grand Prix on the Nürburgring.

Legendary racetrack with many bends: Spa-Francorchamps
The Spa-Francorchamps racetrack in the Belgian Ardennes was opened in 1921, and is regarded as hallowed ground by racing drivers and fans – it almost has the same legendary appeal as the North Loop of the Nürburgring.

The seven kilometre long circuit is already very special because of its very varied course and very considerable differences in altitude, which is why it is often referred to as the “Ardennes Rollercoaster”. Spa-Francorchamps is world-famous by virtue of its notorious “Eau Rouge” combination of bends. Shortly after the starting/finishing line and the “La Source” hairpin, the track dips into a fast left/right combination. This is immediately followed by a respectable uphill gradient transitioning into the fast and also blind “La Radillon” left-hand bend.

A test of courage for any racing driver. There is only space for one car to pass through this demanding combination of bends – no chance for two or even three abreast. It is also important to take the ideal line to gain impetus for the long “Kemmel” straight that follows. Another key point is the ultra-fast double left-hander named “Blanchimont”, where speeds of up to 300 km/h are attained before the racing cars have to be braked hard to take the “Bus Stop” chicane.
“Eau Rouge” is particularly synonymous with exciting racing incidents – but has also been the scene of tragic accidents in the past. The extraordinarily talented German driver Stefan Bellof lost his life at Eau Rouge on 1 September 1985, during a sports car race. Following numerous rebuilding measures on this bend and other stretches, passive safety has been drastically improved for both the drivers, the spectators and the track marshals.

World Champion Michael Schumacher holds the lap record
The official lap record in Spa-Francorchamps is held by the seven-times World Champion Michael Schumacher: his lap time of 1:43.726 minutes dates from 2002, and corresponds to an average speed of 241.837 km/h. Mercedes-GP-Petronas driver Michael Schumacher on the Belgian Grand-Prix track: “This racetrack is one of the few that has retained its historic charm – and one of the last where the drivers really make the difference.” AMG Mercedes DTM driver David Coulthard: “I would say that at least 90 percent of all drivers consider Spa-Francorchamps to be their favourite course.”
Spa-Francorchamps is now the venue for the Belgian Grand Prix Formula 1 race (27 to 29 August 2010) and the 24-hour race (31 July to 1 August 2010) – the very event in which the 300 SEL 6.8 AMG achieved its second place in 1971.

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