Mercedes’ never released sports prototype
The history of the C111 begins in 1967, when the brand with the star decides to create an experimental vehicle responsible for studying the field of technological possibilities: rotary piston engine, use of fiberglass for the bodywork, studies on diesel engines, aerodynamic studies, etc.
In 1969, the C111 tackled fiberglass bodywork and the viability of Wankel technology. On the style side, the design, due to an Italian designer from Mercedes, mixes curves and taut lines under a bright orange dress; for many, the gullwing doors are a callback to the 300 SL and imagine mass production.
The first generation C111 is 4.23 m long on a wheelbase of 2.62 m and weighs 1,100 kg. We especially notice its butterfly doors reminiscent of the 300 SL. Mercedes pictures
Experimental, we tell you
In 1969, it was only an experiment, particularly in terms of motorization. NSU and Citroën have already launched the production of a 999 cm Wankel birotor3 ; at Mercedes, it will be a 280 hp tri-rotor which allows the first generation C111 to reach 270 km/h.
The following year, Mercedes further developed its project. The C111 version 2 is refined with a Cx of 0.32 and a height of 1.12 m. This is designed by computer. It receives a four-piston engine (displacement equivalent to 2.4 l) which develops 350 hp at 7,000 rpm and achieves 0 to 100 km/h in 4.8 seconds.
The aerodynamics of version 2 have been refined. The “pop-up” headlights are still present. Mercedes pictures
From Wankel to diesel
At the Geneva Motor Show, some of the brand’s customers are pressing for a series of C111s to be produced, like the 300 SL. For the manufacturer, it is always a question of studies, especially since Mercedes quickly finds the faults of the Wankel engine, which is very greedy in oil and fuel; and reliability is not in line with the brand’s standards.
Engineers not wanting to miss the march of innovation, they will imagine a new experiment by mounting a diesel engine; especially since in 1973, the first oil shock condemned excessive consumption.
Version 3 of the C111 dates from 1978. Its turbocharged 3-litre diesel engine reaches 230 hp; a record. Mercedes pictures
A record-breaking turbo diesel
Since that date, Mercedes – which, along with Peugeot, is one of the champions and precursors of the diesel cycle engine – has been studying the feasibility. In 1976, the C111 2 became the C111 2D (for diesel).
You take a naturally aspirated 4-cylinder 3-litre 80 hp diesel (the OM 617), you add a turbo and you manage to get 190 hp out of it! Result: in June 1976, the C111 2D broke 16 records during a 60-hour test at an average of 252 km/h.
For the Star, it is over to imagine a commercialization; place for records and research. This will be done with the C111 version 3 of 1978. The engine is pushed to 230 hp and 9 records fall; over a 12-hour drive, the C111 will reach an average speed of 316 km/h.
The fins improve lift on the front and rear axles; it’s not particularly beautiful, but it’s very effective. The power of 500 hp delivered is exceptional for the time. Mercedes pictures
From diesel to gasoline
In 1979, Mercedes abandoned diesel to install a petrol V8. Engineers abandon aerodynamic finesse for maximum efficiency, with large reinforcements of fins and fins. Version 4 receives a 4.8 l block boosted by two KKK turbos which delivers 500 hp. The C111 4 sets a new record with an average speed of 403.978 km/h over a lap of the Italian Nardo circuit.
In total, Mercedes will have built 16 C111s of all types; versions 1 and 2 total 13 copies, version 3 was produced in two copies and version 4 in only one. Note that the C111 does not really look like a prototype; the finish is very neat with superb seats with houndstooth upholstery. There is even a radio…
