- Premiere of Active Body Control
- Adjustable rear spoiler acting as airbrake
The C 112 research car took Daimler researchers on a pioneering journey into the future of driving dynamics and in so doing laid the groundwork for many of the technical innovations which are featured in series-production Mercedes-Benz models today.
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.
The C 112 study took the form of a high-calibre, mid-engined sports car with unmistakable Mercedes gullwing doors. Powered by a 300-kW/408-hp twelve-cylinder engine coupled to a six-speed manual transmission, the sensationally styled body of the research car was home to new innovations which were positively revolutionary back in 1991, such as proximity control and a tyre-pressure monitoring system. These two systems were ready for series production at Mercedes-Benz in 1998 and 1999 respectively and are now available for a range of the brand’s model series.
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.
And the C 112 has even more to offer: the primary area of interest for the C 112 development team was driving safety and driving dynamics, with a number of technological firsts intended to optimise performance. In order to streamline the aerodynamics for example, the C 112 was equipped with adjustable spoilers with active control at both the front and rear which altered their position as dictated by the current driving situation. When driving in a straight line under normal handling conditions, the rear spoiler was designed to be flush with the bodyshell structure at the rear where it was barely perceptible at first glance.
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.
A similar type of system can be seen today in the SLR McLaren high-performance sports car: integrated into the boot lid is an extending spoiler which automatically rises to an angle of ten degrees above a speed of 95 km/h to exert more pressure at the rear axle. The spoiler also doubles as an extra airbrake.
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.
- Vehicle: Mercedes-Benz C 112
- Introduced in: 1991
- Where: Frankfurt International Motor Show (IAA)
- Goals: High-performance sports car for testing active dynamic handling systems
- Powertrain: Four-stroke spark-ignition engine, 12 cylinders, 6.0 liters displacement, 300 kW (408 hp), rear-wheel drive, six-speed manual transmission
- Active Body Control (ABC): Production launch in the Mercedes-Benz CL (1999, C 215 series)
- Active rear-wheel steering
- Active aerodynamics
- Actively controlled rear airfoil for increasing downforce at the rear axle and for acting as air brake: Production launch in the Mercedes-Benz SLR McLaren (2003, C 199 series)
- Electronic tire pressure control system: Production launch in the Mercedes-Benz CL (1999, C 215 series)
- Autonomous intelligent cruise control: Production launch under the name DISTRONIC in the Mercedes-Benz S-Class (1998, W 220 series)
- Electro-hydraulically operated gullwing doors
- Novel sensors for steering, clutch, brakes, doors, seat and mirror adjustment