Guide: Mercedes-Benz C112
Background
Following the 1955 Le Mans disaster, when Pierre Levegh’s 300 SLR crashed into the crowd killing 83 spectators, Mercedes-Benz withdrew from motor racing.
Aside from the odd long-distance rally and some occasional back-door support for AMG, Mercedes were absent for practically the next 30 years.
The firm’s return to racing began during the early-to-mid 1980s.
First came the launch of a Cosworth-engined 190 E Group A homologation special at the Frankfurt Motor Show in September 1983. Initially conceived for rallying, the 190 E Cosworth actually proved more successful in the German Touring Car Championship where it raced from 1988 to 1993.
Having implemented the 190 E Group A programme, Mercedes simultaneously began a Group C collaboration with Swiss sports racing car manufacturer, Sauber.
Beginning in 1985, the initially discrete partnership yielded relatively little during its first couple of seasons.
However, the newly-liveried Silver Arrows of 1988 were a big improvement and finished a close runner up to Jaguar in the World Sportscar Championship.
Mercedes then took back-to-back Driver and Manufacturer titles in 1989 and 1990.
Against this backdrop of sports car success, Mercedes’ new advanced design department, DAS, developed a flagship supercar concept inspired by the firm’s dashing Group C machines.
Mercedes had not produced such a car since the C111 concepts built between 1969 and 1970.
Back then, customers had lined up to try and buy one of the handsome Gullwinged C111s. Frustratingly though, Mercedes stuck to their guns and used the model purely for R&D purposes.
The last time Mercedes had publicly offered a top flight sports car was between 1954 and 1963, when the 300 SL Gullwing and Roadster were produced.
The ultra hi-tech Mercedes-Benz C112 was unveiled at the Frankfurt Motor Show in September 1991.
Riddled with sophisticated electronic systems far in advance of anything available at the time, the C112 was created to test an array of future technologies.
Chassis
The new car’s riveted and bonded aluminium monocoque had a 2700mm wheelbase. It weighed just 59kg.
Light aluminium alloy subframes were added to reinforce the doors and the roof. A removable steel subframe that carried the rear suspension was bolted to to the monocoque.
Multi-link suspension followed a double wishbone pattern. An additional hydraulic ram made up a fifth link at the rear.
Electronically-controlled spring / damper units provided an early form of active suspension and meant body roll was practically non-existent.
Other state-of-the-art features included rear wheel steering, traction control, tyre-pressure monitoring and a distance-sensing radar.
Anti-lock brakes were also fitted. The ventilated steel discs had a 332mm diameter at the front and 304mm diameter at the rear. They were even bigger than than those used by the heavy S-class saloons.
Four-piston Brembo calipers were fitted all round.
The brakes, clutch and steering were power-assisted.
New 18-inch Speedline five-spoke magnesium wheels were unique to the C112. They measured 8.25-inches wide at the front and 13-inches wide at the rear. Both Goodyear and Michelin tyres were trialled.
A 100-litre fuel tank was installed in the engine bay, up against rear bulkhead.
Engine / Gearbox
Also in the C112’s engine bay was an unmodified example of Mercedes’ new type M120 60° V12.
Introduced as an option on the W140 S and CL-class in 1991, the M120 power unit was the first Mercedes V12 since the 44-litre Type MB509 used in the Panzer VIII tank of World War 2.
This latest all-alloy power unit featured Nikasil-coated cylinder bores, DOHC heads with four valves per cylinder and forged steel connecting rods.
It displaced 5987cc thanks to a bore and stroke of 89mm and 80.2mm respectively.
Sequential fuel-injection was developed in-house and a pair of three-way catalytic converters were installed for emission control.
Engine management was courtesy of the latest Bosch LH-Jetronic.
With a compression ratio of 10.0:1, peak output was 408bhp at 5200rpm and 427lb-ft at 3800rpm.
As they had nothing suitable on the shelf, Mercedes fitted a brand new six-speed gearbox developed specially for the rear-wheel drive C112.
Bodywork
Through the use of advanced underbody aerodynamics and active spoilers, the C112 had a drag coefficient of just 0.30. This was the lowest of any sports car available at the time.
Hydraulic front and rear spoilers activated simultaneously when the ECU judged the tyres were losing grip.
The rear spoiler was also deployed to dramatically reduce stopping distance in an emergency; it automatically adjusted to 45° and trebled the car’s normal aerodynamic profile to 0.90.
The C112’s body was fabricated by Carrozzeria Coggiola. The bumpers were Kevlar, but the rest of the panels were predominantly aluminium.
Covered headlights were chosen instead of the eponymous pop-up-type to avoid destabilising the airflow.
A wide nose inlet underneath the front bumper fed fresh air to the brakes and water radiator. Enormous scoops were also added down each flank (for the engine radiators and rear brakes).
Gullwing doors housed two-piece side windows and a body coloured wing mirror high on each A-pillar. In the event of a roll, the Gullwing doors had a manual mechanism that enabled them to be bent open.
The hinged engine cover had no provision for a spare wheel or any luggage space.
Kevlar venturi tunnels were integrated with the exhaust and rear bumper.
Interior
Inside, the luxurious cockpit with its well-padded seats was a far more comfortable proposition than most supercars of the era.
All the instrumentation and switchgear was housed in a new curved binnacle.
A four-spoke airbag steering wheel would have been standard equipment along with air-conditioning, electric doors, electric windows, heated electric seats, electric mirrors, satellite navigation, power steering, a Becker radio cassette and on-board computer.
Mercedes configured the original C112 show car with a black and two-tone grey leather interior.
Weight / Performance
Weight was quoted as 1569kg.
Mercedes claimed a 0-62mph time of 4.9 seconds and 192mph top speed if de-restricted.
However, like nearly all their high powered models from the 1990s, Mercedes would have electronically limited the C112 to 155mph.
Reception
Although the C112 was unveiled at a time when most major economies were in the midst of a multi-year recession, Mercedes reputedly took 700 firm orders of interest.
Ways of building the car were explored (including at Sauber’s Hinwil factory), but ultimately, the project was abandoned as motorsport success was considered a better way to enhance the Mercedes brand.
Text copyright: Supercar Nostalgia
Photo copyright: Mercedes-Benz - https://www.mercedes-benz.com
