| Year
(of specifications) |
1969 - 1979 prototypes |
| Engine |
various,
including Wankel rotary |
| Transmission |
- |
| Max
speed |
250
mph (V8 petrol engine) |
| 0-60
mph |
- |
| Horsepower |
190
- 350 hp |
| weight |
- |
C
111 was the designation of the futuristic study displayed by
Mercedes-Benz in September 1969 at the Frankfurt International
Motor Show (IAA). In the spring of 1970, an even more elegantly
clad C 111-II made its appearance at the Geneva Motor Show,
prompting interested parties to send blank checks to Stuttgart
to secure one of these cars for themselves.
However, it had never been planned to produce the new Gullwing
in series, and the Mercedes-Benz C 111 was not to appear in
showrooms. It was to serve as an experimental car. Designed
to to test glass-fiber-reinforced plastics as a bodywork material,
and a variety of unusual engines.
The first Mercedes-Benz C 111 of 1969 was powered not by a conventional
reciprocating-piston engine but by a Wankel – or rotary-piston
- engine.
The performance of the C 111, even with the three-rotor engine,
was convincing right from the start. In 1969, the Wankel engine
developed 280 hp from 600 cubic centimeters of chamber volume
per rotary piston and gave the car a top speed of 260 km/h;
with this engine, the car accelerated from standstill to 100
km/h in five seconds. The C 111-II of 1970 was powered by a
large four-rotor Wankel engine which developed 350 hp and gave
the car a top speed of 300 km/h. The second C 111 accelerated
from standstill to 100 km/h in highly respectable 4.8 seconds.
While some of the engines in the C 111-I cars had still featured
dual ignition which was difficult to adjust, the four-rotor
engine was equipped with single ignition exclusively. Both engines
were direct-injection units.
The development department of Mercedes-Benz eventually succeeded
in solving the engineering-design problems involved in the rotary-piston
principle, especially in engine mechanics, but the problem of
the Wankel engine’s poor degree of efficiency, due to the
elongated, variable combustion chambers of the rotary-piston
principle, was not to be overcome with technical modifications.
This problem was simply inherent in the design: in a Wankel
engine, the fuel burns within the space between the convex side
of the rotary piston and the concave wall of the piston housing
rather than the cylindrical combustion chamber of a reciprocating-piston
engine. The variable, anything but compact combustion chambers
of the Wankel engine were responsible for poor thermodynamic
fuel economy as compared to a reciprocating-piston engine, resulting
in significantly higher fuel consumption for the same output.
The engines of the first two C 111 versions were straightforward
gas-guzzlers. And since the pollutant content in the exhaust
gas of the Wankel engines was also too high, Mercedes-Benz discontinued
work on this type of engine in 1971, in spite of its impressively
smooth running characteristics and compact size.
In 1976, due to the oil crisis and the need for more frugal
engines, Mercedes-Benz engineers installed a three-liter diesel
engine with five cylinders in the C 111-II for the first tests.
In the car, now called C 111-IID, the OM 617 LA engine developed
as much as 190 hp, thanks to turbocharging and intercooling,
as opposed to the 80 hp output of the production engine which
powered the Mercedes-Benz 240 D 3.0. In June 1976, the Mercedes-Benz
C 111-IID reached spectacular speeds on the test track at Nardo
near Lecce in Italy. In the course of 60 hours, four drivers
established a total of 16 world records – thirteen of these
applying to diesel-engined cars and three to cars in general,
irrespective of their type of engine. During the tests, an average
speed of 156 mph (252 km/h) was recorded.
In 1977, encouraged by the record breaking C 111-IID, Mercedes-Benz
set about creating a car designed specifically for establishing
speed records. Designated the Mercedes-Benz C 111-III the new
car was narrower than the first C 111, had a longer wheelbase
and improved aerodynamic properties, thanks to complete streamlining
and rear airfoils. The 230 horsepower diesel engine managed
to propel the C 111-III to over 186 mph (300 km/h). With this
new car Mercedes-Benz established nine absolute world records
in the late 1970s.
The last version of the sports car, the Mercedes-Benz C 111-IV
presented in 1979, broke the track record by reaching a speed
of 403.978 km/h. This time, it was no longer a diesel engine
working under the plastic skin but a V8 gasoline engine with
a displacement of 4.5 liters and an output of 500 hp. The shape
of the bodywork was equally a far cry from the first version.
Ten years on, and the bodywork crafted with esprit and courage
in 1969 had become a slim, elongated rocket with two airfoils
and massive spoilers.
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