The year 1969 went down in history as one of the most spectacular in the last century. This is not only due to the moon landing. The Mercedes-Benz C 111 landed at the Frankfurt IAA exhibition in September – looking like a UFO from a distant galaxy.
The world had never seen a car like this before. A low-profile orange sports car, the sight of which was enough to make one dream of racing to success. Hardly surprising that, immediately after this key automotive trade fair, a series of blank cheques arrived at the offices in Untertürkheim, because so many people wanted to order the dream car – no matter what it would cost them. However, the 4.40 metre long and 1.10 metre high gullwing design was not intended at all to follow the sports car legend that was the Mercedes-Benz 300 SL.
The Mercedes-Benz C 111 is a legend: as a dream sports car with a Wankel rotary engine, as a record-breaking diesel-powered car and as a circuit record-chaser with a V8 engine.
The Mercedes-Benz C 111 was designed by the then young designer Bruno Sacco – including the rear end design, which emphasised the technological aspect.
The C 111 was an experimental vehicle intended to test technologies that were groundbreaking in their combination. It was not only about the Wankel rotary engine and the mid-engine concept, but also about advanced chassis designs and plastic bodies. And on top of all that, there was the simply breathtaking design.
The Mercedes-Benz C 111 was not always just a C 111, however. There were two different generations of this design in Mercedes-Benz weissherbst livery, whereby the better known one was actually variant II, which celebrated its premiere at the Geneva Motor Show in the spring of 1970. Compared to the IAA debut, it had a completely different front end and a whole series of detailed improvements. However, the C 111 made a name for itself not only due to its unique styling and spectacular paint finish, but more importantly due to the Wankel rotary engine which powered this hand-built dream sports car.
Whilst the 1969 IAA car had a three-rotor Wankel engine with an output of 206 kW/280 PS, the two-seater was upgraded in the winter of 1969/70 by a further rotor to produce 257 kW/350 PS, which gave the C 111-II a top speed of up to 300 km/h. Rotary piston engines were able demonstrate their advantages such as the rotary principle, compact dimensions and remarkable responsiveness. Yet even when the Mercedes-Benz engineers pushed the Wankel engine to the very limits of its design, the result did not meet the high standards of Mercedes-Benz in terms of reliability and durability.
Of the twelve cars built, eleven were powered by Wankel engines, and the last vehicle was built in 1975 as a turbo-diesel test vehicle. Two of the cars, one each from the first and second series, were temporarily equipped with eight-cylinder petrol engines for testing and comparison purposes.
Almost like a UFO from 1970 – the C 111 against the unique mountain panorama of the Montafon.
This Mercedes-Benz C 111 has been fitted with a 3.5-litre V8 engine since 2014 – just as it was in 1970.
The 3.5-litre V8, which produced 147 kW/200 PS, powered the 300 SEL 3.5, 280 SE 3.5 Coupé and Cabriolet models presented in 1969 as well as the 350 SL introduced in 1971, among others, and with its electronically controlled fuel injection system, it was, at the time, the most state-of-the-art Mercedes-Benz production engine. Whilst the 3.5-litre M 116 engine was linked to an automatic transmission or a four-speed manual gearbox on the S-Class predecessors, it was paired with a five-speed manual transmission on the C 111. In late 1970, the M 116 was installed in the fifth vehicle of the second series – at the time the car was completed, there were no more four-rotor Wankel engines available, but the test series had to begin.
The stylish houndstooth seats were not only available in black and white, but also in orange, which was perfectly matched to the exterior weissherbst colour.
With its radio, cigarette lighter and ashtray, this fascinating vehicle had obviously been designed for everyday use. In the early 1970s, smoking was just as popular as the weissherbst colour, flared trousers and stick-on flowers. Above the vertically mounted radio, there were several round dials in the dashboard which provided information about the temperatures of water and oil, the petrol tank level and oil pressure.
The gullwing doors that were reminiscent of the Mercedes-Benz 300 SL were fitted with glued-in windows and a small flap at the height of the sports seats in a contemporary houndstooth pattern allowed some fresh air to enter the vehicle by means of a rotary control. The only drawback of this inside this dream sports car was the fact that temperatures rose rapidly despite the built-in air conditioning system due to the relatively confined interior space.
The engine of the Mercedes-Benz C 111 – whether it was the four-rotor Wankel, turbo-diesel or the V8 shown here – needed copious amounts of cooling air.
In order to be able to demonstrate the 1970 dream sports car in operation whilst at the same time preserving the original remaining Wankel engine components for posterity, Mercedes-Benz Classic equipped one of the vehicles with an M 116 again in 2014 – and, to demonstrate originality, they used the same model that was fitted with this engine in 1970. The conversion took place in the prototype workshop of Passenger Car Development in Sindelfingen – in the same section that swapped the engines in 1970.
After serial production of the C 111, which had been requested by the public again and again, was finally shelved for a variety of reasons, the second life of this spectacular sports car began. From 1975, the Mercedes-Benz C 111 was to demonstrate the capabilities of diesel engines. To this end, a 3-litre OM 617 turbo-diesel, which was being prepared for series production and was to be used in the US models of the 116 and 123 series from 1977 onwards, was installed as a mid-engine. Whilst the production version had a naturally aspirated engine with an output of 59 kW/80 PS, the turbocharged engine in the C 111 developed 140 kW/190 PS and 363 Nm maximum torque, thanks to a Garrett exhaust turbocharger and charge-air cooler.
On the high-speed Nardò circuit, the C 111, almost unchanged in its outward appearance, broke almost all the records for diesel engines valid at that time in June 1976. Over a distance of 16,000 kilometres, the orange-coloured wedge drove at an average speed of 252 km/h in a 64-hour record drive with four alternating pilots.
The engine was installed behind the passenger compartment as a mid-engine concept. This ensured ideal weight distribution.
In 1978 the Mercedes-Benz C 111-IV set a new circuit record. A 500 PS, twin turbocharger V8 engine produced close to 404 km/h.
During this record drive, it became clear that there was still further potential both in the engine and the car. As a result, two copies of a third version of the C 111 were built in 1977 which featured decisive innovations compared to the predecessor: a floor assembly with a longer wheelbase and narrower track, an aerodynamically optimised body with a cW drag factor of only 0.157 and an even more powerful five-cylinder turbo-diesel engine producing 129 kW/230 PS.
The record-breaking C 111-III, now sporting a silver paint finish, achieved no less than nine world speed records and eleven international class records with average speeds of around 320 km/h during a twelve-hour record run in Nardò. The average consumption during the full-throttle run was a sensationally low 16 litres per 100 kilometres.
The record-breaking test in April 1978 came just in time for the market launch of the 300 SD, which went down in automotive history as the world’s first turbo-diesel series passenger car and, at the same time, the first S-Class with a diesel engine.
One of the two record-breaking cars was then converted for another spectacular record run. The C 111-IV was given a redesigned body with a front spoiler and two fins at the rear as well as a much more powerful engine.
A bored-out 4.8-litre version of the 4.5-litre series V8 engine, which achieved 368 kW/500 PS thanks to its twin turbochargers. The aim was to break the circuit record set by Mark Donohue in 1975. In May 1979, the Mercedes-Benz C 111-IV, again on the record track in Nardò, reached almost 404 km/h and surpassed Donohue’s record by nearly 50 km/h.