1991 Mercedes-Benz C112

For the 1990 racing season in Group C, Mercedes-Benz in cooperation with the Swiss Sauber team fielded the C 11. Quite successfully: the team was world champion at the end of the season. This spurred on the engineers at Mercedes-Benz. They were looking for a way to test active dynamic handling systems for large-scale production cars and came up with the high-performance sports car C 112. It was powered by a six-liter V12 engine which developed 300 kW (408 hp) and put 580 Newton meters of torque on the crankshaft. The idea was to transfer this performance optimally to the road at the physical limits with the highest level of active safety.

Active Body Control

The C 112 was the first car to afford active suspension named Active Body Control (ABC). Each wheel is equipped with a combination of spring and hydraulic servo cylinder. Sensors detect all vehicle motions – vertical displacement, roll and pitch. To eliminate the motion, computers evaluate the data and control the active suspension elements accordingly. The result: an unprecedented level of stable roadholding.

The sports car features active rear-wheel steering. It corrects directional deviation which can be caused, for instance, by ruts and side wind or by road surfaces with changing tire-to-road adhesion. Even in critical situations, for example load changes during cornering, it maintains the handling and traction behavior to which the driver is accustomed. An anti-lock braking system (ABS) and acceleration skid control (ASR) of the latest generation complement the technology.

Equipped with all these features, the C 112 offers neutral handling irrespective of load and roadway condition, even during high-speed cornering. Its safety reserves were thus higher than those of previous sports cars – a result from which volume-built Mercedes-Benz cars also benefited.

Active aerodynamics

And the C 112 has even more to offer. One of its highlights is active aerodynamics. Fully adjustable, the front spoiler and the rear airfoil are adapted to the particular driving situation to ensure the optimum compromise between low air resistance on the one hand and high downforce on the other.

During normal operation the rear airfoil is inactive and forms an integral part of the rear body structure; in this inactive state the car has the optimum Cd, and lift forces tend toward zero. But it’s quite a different story during high-speed cornering at the critical limit: here, appreciably larger wheel contact forces permit decidedly greater lateral acceleration and more stable handling.

In such a situation, the rear airfoil extends to the rear and upward within a tenth of a second and, in extreme instances, also changes the angle of incidence. The lip of the front spoiler, changing its height, works together with the rear airfoil. The system enables higher cornering forces and immediately extends the critical limits for the driver.

The rear spoiler is also used to improve the emergency stopping properties: with lightning speed it is raised into the wind when required and helps slow the vehicle down. In addition, the brake system intelligently distributes the brake pressure between front and rear wheels to achieve optimum deceleration. Other components tested in the C 112 are tire pressure monitoring, which warns the driver of sudden pressure loss, a distance warning radar for vehicles traveling ahead, and partly new and different sensor systems for steering, clutch, brakes, doors, seat and mirror adjustment.

The return of the gullwing doors

As the first vehicle since the C 111, the C 112 again featured gullwing doors. Since the 1950s they have been a symbol of the sports cars from Mercedes-Benz: the 300 SL coupe (W 194/198 series, 1952 and 1954, respectively) was the first to have them – and a car whose excellent technical qualities made it a standout in its day. The C 112 with its streamlined body takes that up again.

In Detail

Keyword: 1991 Mercedes-Benz C112