Auto Glossary




The pillar situated between the rear side windows and the rear window, that supports the roof. It's the last roof supportive pillar on normal four door sedans.


A vehicle design that moves the front wheels out farther on a front-wheel drive vehicle, which in turn results in a longer distance between the front and rear wheels. This creates more passenger area up front, therefore increasing interior leg-room room and comfort.
Cab forward


CAS is a detection system that uses radars, cameras, sensors and other equipment to detect a potentially imminent crash. Once the danger is detected, a warning is sent to the driver. If no reaction is detected, the system automatically brakes or steers.
Collision Avoidance System


A Jaguar developed system, the Computer Active Technology System (CATS) uses a network of sensors to monitor the driver's driving style and road conditions. The adaptive shock absorber on each wheel is constantly tuned by a microprocessor that calculates what to do by gathering data from all the sensors.
Computer Active Technology Suspension


Developed by BMW engineers, CBC (Cornering Brake Control) regulates the pressure individually in each wheel brake cylinder so that the car can brake optimally during a turn. In order to do this, CBC is using the ABS sensors to determine each wheel's rotational speed and will try to compensate the natural tendency of a vehicle to oversteer if braking during a turn.
Cornering Brake Control


The drag coefficient (Cd or Cw) is measuring how much aerodynamic drag a vehicle has. The bigger volume of air a vehicle has to push out of its way while traveling, the higher its Cd value will be, thus requiring more power and fuel to sustain that speed.
Coefficient of drag


CDI (Common rail Diesel Injection) is the marketing name given by Mercedes to their modern diesel engines, which are using common rail injection technology. In essence, common rail is a development of the direct injection system. Conventional direct injection diesel engines must build up fuel pressure for each cylinder injection, whereas in CDI (and other common rail systems) the pressure is generated independently of the injection sequence and remains constantly available in the fuel line (on a common rail).

Acting as an accumulator or a separate reservoir, the common rail is usually situated above the cylinders and is distributing the fuel to the injectors and a high and constant pressure. Regulated by the engine ECU, special solenoid valves control the amount of fuel being injected in each cylinder. The biggest advantage of this system is the power and fuel economy induced by the efficiency of common rail over conventional injection systems.
Common rail Diesel Injection


A normal differential is used in cars to help power the drive wheels while allowing them to spin independently of each other during cornering (same power, different rotational speeds). In vehicles with four-wheel drive, a center differential is required because during a tight turn all four wheels are rotating with different speeds.

Receiving power from the engine through the transmission or the transfer box, the center differential regulates the power between the front and rear axles, thus allowing different rates of traveling.

Center Differential


CFRP is a very strong yet lightweight material used in a wide range of products, from sports goods to aerospace engineering. In the auto industry, CFRP is used to bring down the weight of the car without compromising strength.
Carbon fiber reinforced plastic


The term "chassis" usually describes a vehicle's structural frame, on which the actual body sits, but this is only true on "body on frame" vehicles. In vehicles with unitized or "unibody" construction, the chassis comprises everything but the doors, hoods, engine and suspension elements.


Rear door locks that are controlled by the passengers in front and are designed to keep children from exiting the vehicle prematurely.
Child-security locks


An extra rear brake lamp that's placed high inside or outside the vehicle, designed to give tailgating drivers an additional reaction time for avoiding a rear collision. The "third brake light" - the way it's sometimes called - is using LED technology on most vehicles.
Center high-mounted stop lamp


COE is a truck body style with a flat face or semi-hood.
Cab Over Engine


Used in a vehicle's suspension system, a coil spring consists of a spiral shaped bar of resilient metal (usually steel or steel alloy). While traveling, the spring can be compressed or extended repeatedly while retaining its flexibility and without permanent deformation.
Coil Spring


A member made of composite material that acts as an energy-absorbing device in the event of a collision, improving the vehicle body's stabilization during the crash.
Composite cross car beam


A steel, aluminium or other similar material which connects the piston to the crankshaft in a combustion engine.
Connecting rod


Control Trac is the marking name for a system developed by the Ford Motor Company. In essence it is a computerized non-permanent 4WD system that evaluates the road conditions with the help of various sensors, and it can automatically switch the vehicle from two to four-wheel drive whenever wheel-slip occurs.
Control Trac


A coupe (or coupé) is a two or four-seater vehicle with a fixed roof and only two doors. There is no globally accepted official definition for the term though. According to SAE (Society of Automotive Engineers) standards, a coupe is a fixed-roof automobile which has less than 33 CuFt (approximately 934 liters) of interior volume. Any car with a greater interior volume is technically called a two-door sedan, not a coupe, even if it has only two doors.



The crankcase is the housing which contains the crankshaft, primary driveshaft and gearbox.


The crankshaft is the part of the engine which translates the engine piston's linear motion into a more usable spinning motion. It is usually connected to a flywheel, in order to reduce the pulsating characteristic of the four-stroke cycle in the combustion engine and to the driveshaft consequently.


CRDi is the marketing name given by Hyundai-Kia to all of the common rail diesel engines powering their vehicles.
Common Rail Diesel direct Injection


The crossmember is a metallic section bolted or sometimes welded across the frame of a vehicle, usually to "cover" the underside of the engine bay, in order to support the engine and/or the transmission in their place.


A crossover is a type of automobile which blends the main characteristics of at least two car segments. Most crossover cars nowadays bring together the versatility of a family car with that of an SUV.


Curb weight is the weight of an empty vehicle, without cargo and driver and passengers, but including maximum amounts of fuel, oil, coolant and standard equipment, including the spare tire and tools. In the EU legislation, curb weight means the cars has to be weighed with the reservoir filled at 90%, a 68 kg driver, 7 Kg of luggage and all the other fill ups made.
Curb Weight

CV joint

A CV (Constant Velocity) or a homokinetic joint is a type of universal joint, designed to transmit power from a rotating shaft to a wheel through a variable angle but with a constant rotational speed. They are usually used between the front half-shafts and front wheels in a front or four-wheel drive vehicle. Some rear-wheel drive cars with independent rear suspension also use CV joints at the end of the axle half-shafts.
Constant Velocity Joint


In essence, a Continuously Variable Transmission (CVT) is a type of automatic gearbox with an infinite number of gears situated between two values (a maximum and a minimum). One of the most common types of CVT consists of a steel or rubber belt and two conical pulleys. Unlike a normal transmission, which effectively has to choose between a given number of planetary gears, the CVT just varies the diameter of the conical inner surfaces on which the steel/rubber belt rides.

Most of them use either hydraulic pressure or spring tension to adjust the distance between the two pulleys. The main advantage of CVTs over conventional transmissions resides in their smoothness, since basically there is no interruption of power during the "shifting" maneuver. The main shortcoming is the amount of torque they can handle, which depends strictly to the material of which the belt is being made of. This can be neglected to a certain amount by designs which are using more complicated roller arrangements instead of belts and pulleys.

Continuously Variable Transmission

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