4-ETS (4-wheel Electronic Traction System) As a component of the fourth generation of 4x4 Mercedes systems (called 4Matic), 4-ETS is a traction control mechanism that utilizes a group of sensors to monitor the adhesion of the wheels. If it detects a loss of traction, it individually brakes the slipping wheel or wheels and simultaneously directs the torque to the wheels with grip. If needed, the 4-ETS can distribute torque even to just one wheel if this is the only one adherent to the surface. Hence, in theory, the car can break the deadlock even with three wheels in the air. In reality, the operating principle of the system allows the only wheel to grip sole to receive 25% of the engine torque, which might be insufficient to move the car.
4Matic This is a permanent four-wheel drive system developed by Mercedes-Benz. It is available on most of the models and it revolves around the 4-ETS technology and works closely with the stability control program (EPS) to ensure the maximum of grip on the road in almost any driving conditions (wet pavement, surfaces covered with snow, etc). In addition, the standard setting of the torque delivery (40% to the front wheels, 60% to the back wheels) keep the dynamic characteristics of a rear-wheel drive car, creating the premises of a sporty driving style.
4Motion This is the name given by Volkswagen to its own four-wheel drive system. The technology uses a Torsen center differential (the engine is positioned lengthwise) or a Haldex clutch to automatically distribute the torque between the two axles. When it comes to newer cars, it collaborates with various active safety systems – stability control, traction control, to provide a road stability superior to the cars with rear wheel traction.
4WD (Four-Wheel Drive) This abbreviation is usually used to designate a non-permanent four-wheel drive system where the second drive axle is coupled manually through a lever or a button. For more advanced systems, the management computer can decide to automatically shift from 4x2 to 4x4. 4WD is mainly found on old designs of all-terrain vehicles which were developed during a time when the off-road skills where more important that a high on-road stability.
4WS (Four-Wheel Steering) Broadly, 4WS is a car’s ability to steer both the front and rear wheels. 4WS can be translated as "all-wheel steering”. The system can work, depending on the model, either to help the vehicle turn in a smaller radius or to increase stability at high speeds. Some of the most popular cars equipped with this technology are Nissan Skyline GT-R, Renault Laguna Coupe, the latest generation of BMW's 7 Series (F01/F02) and the pair of all-terrain models Chevrolet Suburban / Chevrolet Silverado.
4XMotion This is a more advanced version of 4Motion, currently available only on the last generation of the Touareg SUV. Unlike 4Motion, 4XMotion distributes power not only between front and rear axles but also between the wheels on the same axle, so the torque modulation process automatically takes place a few times per second.
A-TRAC (Active Traction Control) A-TRAC is a traction control system specially developed by Toyota on 4x4 vehicles. The technology is based on a network of sensors and computers that manage the brakes and engine, used to imitate a lockable differential. A-TRAC brakes the slipping wheel and simultaneously transmits torque to the other wheels withgrip. It is using only a set of open differentials and the effect of a limited slip differential (LSD). With this, the system offers the advantages of a chassis with lockable differentials without its usual problems (low maneuverability in tights curves, heavy steering, worn tires and differentials grip, etc).
ABC (Active Body Control) This is a fully- active suspension control system developed by Mercedes-Benz and considered to be one of the most advanced today. With the help of sensors and hydraulic high pressure radial piston pump, ABC maintains body control during acceleration, braking and steering, which decisively contributes to a high-class comfort.
ABS (Anti-lock Braking System) As the best known and most used active security system, ABS is composed of a management unit, four sensors (one for each wheel), a network of valves and a pump. They are all working together to reduce braking distances. In short, the “brains” of the system detects any abnormal deceleration of the wheels and, with the help of the other components it prevents the wheels from locking up and skidding because of the braking. Closing and opening the circuit is made with an extremely fast pace and the most modern systems can operate even 15 times per second. The vehicle, depending on its type, age and class, can be equipped with single channel ABS or four channel ABS. The latter has sensors and valves for each wheel, giving the best performance.
ABSplus (Anti-lock Braking System plus) ABSplus is a special feature of the classic ABS system of Volkswagen, which becomes active when the car runs on a particularly difficult piece of terrain. It is available on off-road models (e.g.: Touareg) and it initiates a rapid short-term locking of the wheel right before the decrease of pressure in the circuit. It is thereby creating the conditions of accession of small particles in the tire tread, increasing the effect of the braking. The required distance for braking is smaller and the vehicle remains easy to control throughout the process.
ACC (Automatic/Adaptive Cruise Control) Having different names in the automotive industry (depending on the manufacturer) ACC is different from the regular systems and it is responsible for maintaining speed with the help of a feature that allows it to a. maintain a constant distance from the vehicle ahead, b. to automatically brake the car (even to a complete stop) in case the car in front does the same thing. The first systems were using lasers to record the distance between vehicles but they soon proved to be inefficient in bad weather conditions. Today, most automatic/adaptive cruise controls use radar waves and some of them already offer several running programs.
Active Steering This is the name given by BMW to its own power electric variable gear ratio power steering system first introduced on the fifth generation of 5 Series (2005). The technology allows the steering angle vary depending on the vehicle’s speed. This way, it facilitates large maneuvers at low speeds (such as those in the parking lot) and it gives the car more stability at high speed. In the first case, computer varies the ratio so that the steering wheel needs less than two turns to move the wheel lock to lock. In the second case, the steering ration increases, and it takes larger movements of the steering wheel to give the vehicle stability. Active Steering is working closely with the stability control system (EPS) to automatically adjust the steering angle when the direction needs small adjustments unnoticed by the driver (e.g.: wind from the side or small bumps on the road).
AFU (Assistance Au Freinage d’Urgence) French name for the power-assisted brake system used by Renault and PSA group. See BAS.
AHC (Active Head Restraint) AHC is a passive security system which protects the cervical vertebrae of any possible dislocations which might occur when the car is hit from behind. Studies show that over 90% of the injuries arising from such incidents occur at the neck level. This is what led car manufacturers to develop a system to protect the driver’s neck and the front passenger. When another car comes into collision with the vehicle, the headrests instantly move forward, preventing the head to suddenly move towards the back. But such safeguards however have their own limitations. A recent study conducted by National Administration of Roads in Sweden and the insurance company Folksam showed that the effectiveness of this technology differs greatly from one car to another. Therefore, AHC cannot become a guarantor for limiting the impact in the cervical area.
Airmatic Airmatic is the name of the air suspension implemented by Mercedes on its flagship models. The technology is offering two choices for setting the suspension dampers – Comfort or Sport - depending on the road conditions. For example, even if it runs in Comfort mode, the car can instantly become more incisive when the driver performs a maneuver to avoid an obstacle. Airmatic also offer the possibility to set the ride height and the stabilization of the vehicle depending on the number of people (or weight of luggage) on board.
APCS (Advanced Pre-Collision System) Similar to the Pre-Safe technology developed by Mercedes-Benz, APCS is a complex system for prevention and protection in case of collision implemented by Lexus on its flagship model LS. Created to detect and warn the driver of a possible frontal collision, APCS can be distinguished from the other active systems because of its ability to actually take the necessary measures to protect the passengers of an imminent impact. Once the intricate network of sensors and video cameras has sent the information that there is an animal of an object in front of the car, the electronic “brain” warns the driver and if he does not react in time, the system applies a slight braking force. If the same computer concludes that the collision cannot be avoided, it prepares the front seats passengers by tightening the seatbelts and generating the maximum braking force. The system is working closely with BAS and Active Pedestrian Detection System technology, the latter being use to detect pedestrians.
ASC (Active Stability Control) This is the name given by Mitsubishi to its own stability control system. See EPS.
ASC+T (Automatische Stabilitats-Control + Traktion) This is the old stability control implemented on BMW cars and later replaced by DSC. It became a standard feature on BMW cars starting from 1996. ASC+T is using the ABS sensors to detect any wheel slipping, and it is than compensating the lack of traction by changing the angle of the throttle and brakes the wheels. The braking force can vary from wheel to wheel, depending on the degree of adhesion. See EPS.
ASR (Anti-Slip Regulation) This is an alternative name for the traction control system. See TC/TCS.
Attention Assist This is a system used for detecting driver fatigue and warning. It was developed by Mercedes-Benz. Studies revealed that 25% of serious accidents occur due to fatigue. This is why Mercedes has created a technology that "notes" driver behavior and compares it with his personal profile, created during the first kilometers of travel. If the sensors register a change in the driver’s behavior - which betrays a state of lethargy -, Attention Assist warns the driver both acoustically and with lights that it is time to take a break. The system is in operation at 80 km/h and deactivated at over 180 km/h. What determines the system to take preventive measures is the way the driver turns the steering wheel and the rotation speed.
AVS (Adaptive Variable Suspension) This is the air suspension system developed by Lexus, similar to Airmatic.
AWD (All-Wheel Drive) This is the generic name given to all-wheel drive systems mainly used by on-road cars. Implemented in order to obtain a more secure road holding and a maximum traction on roads with low grip, the AWD system involves all four wheels at any speed without damaging the differentials. These, unlike regular lockable differentials, have the ability to manage the torque between the axles and, more recently, between the wheels on the same axle. These torque transmission technologies, however, show their limits off-road, their lack of structure, which is making them useless on extreme places - forest roads, dirt roads, etc.
BAS Developed by Baimler-Benz in the early 90s, brake assist system was created after a study which showed that 90% of the drivers don’t press enough the brake pedal. The reason was the fear of blocking the wheels. Meanwhile, the popularization of the ABS reduced the rate down to 70% according to Renault. Broadly, BAS compensates the driver’s “timidity” by automatically applying the required braking force for every particular situation. Also, it maintains the high pressure in the circuit during deceleration, releasing it only when it “feels” the relaxation of the brake pedal. The technology exploits the full potential of the braking system and it is one of the most efficient methods in avoiding accidents, as it is applying the correct force starting from the first moment.
BLIS (Blind Spot Information System) Created by Volvo and then introduced by Ford – the former mother company – on most of its models, BLIS is a system created for detecting the cars which entered in the blind spot of the rear mirrors. Two cameras – one for each rear mirror – are monitoring the traffic on the vehicle’s left and right hand side and they are warning the driver about the entry of a car in the blind spot (using a light signal). Ford also has a Cross Traffic Alert feature which is using the same principle to alert drivers driving backwards outside a parking lot.
CBC (Cornering Brake Control) This is an active safety system developed by BMW whose functioning principle is similar to the EBD (electronic brake force distribution). The technology activates the brake to counter over-steer when the driver suddenly brakes to turn around corner. See EBD.
CDI (Common-Rail Diesel Injection) This is the most advanced, effective and efficient fuel injection system for diesel engines. Today, it is used by most of the automotive manufacturers. The technology is different from the other direct injection systems because of two main characteristics: all of the fuel injectors are supplied by a common fuel rail and a high pressure pump stores fuel at high pressure up to and above 2,000 bars. With the help of the common rail, piezoelectric valves and a management computer (ECU), the technology controls the fuel quantity entering the injectors, the number of injectors, the time and the degree of fuel atomization, decisively contributing to achieving a maximum efficiency and a low vibration level. Also, common-rail diesel engines do not require preliminary heating and produce less noxious than older engines with compression ignition.
CMBS (Collision Mitigation Brake System) This is the name given by Honda to its system for monitoring the distance ahead of the vehicle. See CWBS.
CST (Controllo Stabilita) This is the name given by Ferrari for its stability control system. See ESP.
CVT (Continuously Variable Transmission) Continuously variable transmission is an automatic transmission that can sleeplessly change through an infinite number of effective gear ratios between maximum and minimum values. This can be achieved through several methods but the most common involves a set of cone pulleys and a trapezoidal transmission. Changing gear is produced by pulling/pushing the pulleys mounted on the same tree. As a result, the diameter of the belt reaches a peak, the other one is at minimum. Compared with the traditional transmission, CVT is much more flexible and thus more efficient, allowing the engine to operate at optimal parameters of consumption across a wider range of speeds.
CWAB (Collision Warning with Auto Brake) This is a pre-crash system similar to PreSafe from Mercedes – superior to CWBS – developed by Volvo. See PreSafe.
CWBS (Collision Warning with Brake Support) CWBS is a system of prevention against frontal impacts developed by Volvo, which is using radar waves to detect vehicles ahead. If the distance between the two cars is small, the system beeps and if the distance between the two vehicles becomes dangerously small, the car with the CWBS alerts the driver through a light signal onto the windshield. The system goes to a next level of alerting when the driver has a late response to the received signals, and it prepares the brakes for an emergency stop. Two things can happen: either the driver takes his foot off the acceleration pedal (and the system applies a normal force brake, but faster than the reaction of the driver) or he presses the brake pedal fast and with strength (in which case CWBS brakes at full capacity in order to avoid collision).
DAC (Downhill Assist Control) Downhill Assist Control is a system developed by Toyota, which assists the driver when driving down a hill. The technology allows descending at a maximum speed of 25 km/h, and it automatically and continuously modulates the brake applied to the wheels so that they do not loose adhesion. DAC works closely with other brake control systems (such as ABS and A-TRAC) while the driver only has to watch the road and steer.
DBC (Dynamic Brake Control) This is the name given by BMW for the braking assistance system. See BAS.
Distronic This is the automatic cruise control installed on Mercedes-Benz models. The system is using a special sensor placed in the radiator grille, to maintain a pre-set distance from the vehicle ahead. If the vehicle ahead reduces speed, Distronic slows down the car and operates the brakes if necessary. Unlike Distronic Plus, cars equipped with Distronic cannot automatically brake to a complete stop.
Distronic Plus Distronic Plus is an update of Distronic and it uses a combination of video cameras and radar waves to keep a preset distance from the vehicle ahead (and to slow down if necessary) but also to completely stop the car if the vehicle ahead does the same. As a part of a complex package of precrash systems (together with blind spot informative system and the lane departure system), Distronic Plus is monitoring the surroundings up to a maximum speed of 200 km/h working with BAS technology to warn the driver when he does not press enough the brake pedal.
DOHC (Double Overhead Camshaft) The acronym is used for the engine with two camshafts located within the cylinder head. See OHC.
DSC (Dynamic Stability Control) This is the name given by BMW (and other producers) to the stability control system. See also ESP.
DSG (Direct-Shift Gearbox) This is an electronically controlled manual gearbox with double clutch developed in the laboratories of Volkswagen Group. It is available on most models in the range. DSG in the six or seven steps variant has as a main advantage the smooth gear shifting due to its feature that allow it to preselects one of the clutches when the one already working is ready to “hand over”. Each of the two clutches controls certain gears (for example, for the six steps gearbox, one is acting on gear 1,3 and 5, while the other one on 2, 4 and 6), and the shifting between gears is very fast (three to four hundredths of a second), precisely because of the pre-selection feature. The next gear is not selected but it is ready in every other respect. Beyond the balanced functioning and thanks to the settings in the control module, DSG transmission allows 10% reduction of the fuel consumption when the automatic function is used.
DSTC (Dynamic Stability & Traction Control) This is the name given by Volvo to its stability control system. See ESP.
Dualogic Dualogic is a manual transmission available on FIAT group models. From the mechanical point of view, it is similar to a classical manual gearbox, but the fact that it offers the possibility to also choose an automatic program (an electronic actuator is replacing the clutch pedal) makes it different than a regular transmission. Dualogic has several functioning programs (Manual, Automatic and Economic) and its main advantage is that, in theory, it combines the comfort of an automatic transmission with the fuel economy of a manual system.
EBD (Electronic Brake Distribution) Along with ABS and BAS, EBS (electronic brake force distribution) is one of the most important active safety systems. It is designed to prevent the destabilization of the vehicle when the driver is forced to brake all of the sudden for various reasons. With the help of a network of sensors and a management computer, EBD detects the differences between the car speed and the rotation of the wheels, so that it can determine the extent in which it has to brake each wheel so that the car does not loose stability. The system can prove its utility in various occasions as sudden braking (when there is an immediate transfer of the masses of the rear axle to the front axle) and up to avoiding obstacles or loss of adhesion in curves (when the over steering is avoided by applying the different braking forces - less in the inside wheels to prevent them from blocking).
EBV (Electronic Brake Variator) This is the alternative name for the electronic distribution of the brake force system. See EBD.
EDL (Electronic Differential Lock) EDL is not really a differential lock but, although it has a different working principle, it has a few of the advantages of a locking differential, as safe completion of a slippery surface. Therefore, when one wheel starts rotating at high speed, the system will brake the wheel and direct the torque to the wheel with better adhesion. On Volkswagen group cars, EDL is active up to a speed of 50 km/h and is regarded as one of the best methods for a good traction without wearing tire.
EPS (Electric Power Steering) Power assisted steering. Instead of a hydraulic mechanism or a “hybrid”, this type of servomechanism uses a simple electronic engine to reduce effort at steering. Latest applications and obviously more advanced adjust the degree of assistance according to the vehicle speed and even of the road condition, keeping a high level of stability. Unfortunately, a large number of electric assisted steering systems lack feedback – the link between the power needed to steer and the effort of the driver, which makes it hard to sporty drive.
ESP (Electronic Stability Program) One of the most important inventions in the field of active safety if not even the most important, the electronic stability program is responsible for maintaining the vehicle on the road when, for various reasons, it tends to deviate from the vertical axe. Developed by Bosch in mid 90s and first used by Merced-Benz and BMW, ESP uses a complex network of sensors which measure the rotating speed of the wheels to take the necessary measures for the stability of the car, like individual braking of a wheel and/or reducing the intensity of the acceleration. The electronic stability program is intensively working with the ABS (using part of its sensors) and with other system governing the method of directing the torque on pavement. Its effectiveness was already proved on most of the highways of the world. In the USA, about 9,000 lives could be saved annually if all the cars would be equipped with ESP.
ETC (Electronic Throttle Control) ETC is an acceleration activity control system using electronic signal instead of mechanical links, which are more common. There are multiple advantages, from the high reliability of this technology to a more efficient exploitation of the propellant motor group (obtained by precise control of the throttle). Note however that in several conditions there have been signalized sensibilities of the system because of electromagnetic interferences and short circuits which allegedly resulted in unintended acceleration.
ETS (Enhanced Traction System) This is the name given by General Motors to its traction control system. See also TC/TCS.
GPS (Global Positioning System) Space-based global navigation satellite system. The devices use signals received from satellite to determine the coordinates of the position of the car.
HAC (Hill-Start Assist Control) This is a name given by Toyota to its hill start assist system. See Hill Start.
HBA (Hydraulic Brake Assist) This is the hydraulic brake assist system similar to BAS. See also BAS.
Hill Holder Invented by Studebaker 75 years ago, the hill start assist system (so called Hill Holder) eliminates the need to press the brake pedal when starting the car up the hill. Today, technology uses sensors to detect the inclination of the road and it has links with the braking system. This way it eliminates the risk of slipping down the hill and accidentally stopping the engine. Hill Holder is a technical application used mainly by vehicles with manual transmission but also by those with automatic transmission.
HUD (Head-Up Display) This is the system that displays the information about the trip (speed, distance, etc.) introduced in the automotive industry by General Motors.
ICCS (Intelligent Cruise Control System) ICCS is the name given by Nissan to its intelligent cruise control. See ACC.
JTD (uniJet/MultiJet Turbodiesel) This is the term used for FIAT group’s common rail turbo diesel engine range. See CDI.
KDDS (Kinetic Dynamic Suspension System) KDDS is a technology used by 4x4 Toyota/Lexus models for improved off-road skills. Invented by a small research-development laboratory in Australia, the system acts on the stabilizer bars (their adjustment is made through interconnected hydraulic cylinders) and, when needed, it declutches them for an increased ability to move the vehicle. KDDS does not start until one of the wheels is suspended in the air, which means it is not active the whole time the car is on the road.
LDW/LDWS (Lane Departure Warning System) LDW/LDWS is a system designed to warn the driver when the car is leaving the lane unless the turn signal is on. The system warns the driver through audio or visual signals or even vibrations in the chair or on the steering wheel. This was first used in commercial vehicles (trucks, cabs, etc.)
LKA/LKS (Lane Keeping Assist/Lane Keeping System) This is an alternative term for the lane departure warning system. See LDW/LDWS.
LSD (Limited Slip Differential) Limited slip differential is a type of differential that allows a small difference between the speeds of the wheels, which are kept under control through mechanical connections. The most common variant of LSD is the one with friction discs and an arch with the function of pressing the planetary gears on the body when one of the wheels is slipping. This way, the pinions and the body rotate together and the wheel with adhesion receives more torque. The friction between the pinions and the differential body can be increased with the help of conic surfaces (similar to the synchronous in the gearbox), but regardless the type, the advantage of the differential with limited slipping remains the same: the directing of the torque to the wheel with adhesion without the usual problems of the locking differential (tires wear, degradation of mechanical components, etc).
MMI (Multi Media Interface) This is a versatile computer system designed to control all the infotainment of the Audi models. The mobile phone, audio system, navigation, TV, internet and/or the features of the manufacturer are all included in the Multi Media Interface menu which, depending on the generation and variant, can be accessed either from a knob or from four or eight buttons called “hardkeys”.
OHC/SOHC (Overhead Camshaft/Single Overhead Camshaft) This is the name for the configuration of the engine where the camshaft cylinder is placed above the combustion chamber. If there is a single camshaft for each row of cylinders, than the system is a SOHC. For modern engines with a configuration in four valves per cylinder, there are two camshafts per row of cylinders, so a DOHC (Double Overhead Camshaft) system. SOHC/DOHC engines are more complex and more expensive than the OHV (Overhead Valves or “pushrod” type), but they allow the crankshaft to reach a higher speed. The OHC configurations include less moving parts and a more precise timing of the closing/opening of the valves, therefore a higher power of the torque.
OHV (Overhead Valve) The configuration of the camshaft engine is placed inside the engine block and the valves are activated though a push rod gear. OHV engine has a few advantages compared to the CHO one, especially related to its physical dimensions. With camshaft located in the block, it has a more compact structure and it is less complex, but it has the disadvantage that it cannot be configured for high speed regimes. Gear Drive valve has several moving parts, therefore it is heavier and it has a larger inertia, and the push rods tend to bend or even break at high speeds of the crankshaft.
Parktronic This is the name given by Mercedes to its parking assist system. Like other similar technologies, Parktronic is using a group of sensors to detect objects in the vicinity of the vehicle and sends the information about the distance to the driver. Detection is performed with the help of ultrasound technology similar to the one of the sonar.
PASM (Porsche Active Suspension Management) Name given by Porsche to its chassis with active suspension whose structure includes the presence of a set of electronically controlled dampers. The pressure in the damping system is continuously and automatically adjusted depending on the configuration of the running surface and the driving style, but it follows settings for the two running programs: Normal and Sport. In the case of the version for Cayenne, there is a third program, called Comfort.
PCS (Pre-Collision System) This is the general name given to the safety systems designed to prevent collision or to lessen the impact in case of the collision. Depending on the technology and manufacturer, it warns the driver with audio or visually, it gives a better position in case of the collision (withdraws the seat and improves lateral support), moves the headrests to avoid the dislocation of the cervical vertebrae, tightens the seat belts and strengthens the braking system. See APCS, Pre-Safe.
PDC (Park Distance Control) Term used by BMW for its parking assist system. See also Parktronic.
PDK (Porsche Doppelkupplungsgetreibe) Name given by Porsche for its dual clutch transmission. See DSG.
PHC (Porsche Hill Control) Name given by Porsche for its hill start assist system. See Hill Start.
Pre-Safe Launched in the autumn of 2002, the pre-crash system developed by Mercedes-Benz was using ESP and BAS sensors to track the extent to which the car is about to enter collision. If the information recorded by the sensors were giving the information about a possible collision, the system was preparing the passengers for the impact by strengthening the seatbelts, rising the headrests, adjusting the front and back seats and closing the windows and hutch. Later, Pre-Safe was updated with the Pre-Safe Brake function which activates the brakes up to 40% with 1.6 seconds before the collision and 100% with 0.6 seconds before it.
PSM (Porsche Stability Management) Name given by Porsche to its stability control system. See ESP.
PTM (Porsche Traction Management) One of the most advanced technologies to efficiently direct torque to the wheels, PTM has as the central element the all-wheel drive system with an electronically controlled multi-plate clutch, which is closely working with the anti-slip system and where appropriate with the system for locking the read differential. It is available on the 4x4 version of 911 and of the Cayenne SUV, and it is superior to the old systems of Porsche not only because of the much more advanced network of sensors used for monitoring the road conditions (the sensors send information about the wheels speed, lateral and longitudinal acceleration an steering angle), but also because of the central multi-plate clutch whose response to the engine’s input is much faster than the one of viscous multiple-disc clutch.
Quattro Name given by Audi to its all-wheel drive. See also AWD.
R Tronic R Tronic is a semi-automatic transmission with 6 gears available on Audi models. See Dualogic.
RSC (Roll Stability Control) Launched by Ford on the 2005 Lincoln Navigator, Roll Stability control is an advanced version of the classical stability program ESP which takes into account not only the vehicle’s tendency to rotate around its axis but also the tendency to rollover. Compared to a regular stability control system, CSR encompasses a second gyro sensor which measures the car tendency to rollover. If the values are alarmingly high, the sensor sends the information to the management computer which takes the necessary measures (reduces the engine power with up to 15% and brakes one or more wheels). The rollover tendency is monitored 150 times per second, letting the RSC prove its utility especially when the car is overloaded.
S Tronic This is the name given by Audi for its dual clutch transmissions. See DSG, PDK.
SBC (Sensotronic Brake Control) The “by-wire” brake control system with electromechanical elements and electronic control systems instead of the traditional mechanical-hydraulic components, SBC was developed by Mercedes-Benz at the beginning of 2000. But the technology had a poor reliability and because of a large number of complains, Mercedes decided to withdraw it from the market.
SH-AWD (Super Handling All Wheel Drive) The all-wheel system developed by Honda for its premium make Acura. SH-AWD is one of the first AWD solutions able to modulate torque not only between the front and rear wheels but also between the rear wheels. In normal road conditions (running in a straight line at cruising speed and low speed when cornering), the front axle receives 70% of torque. But when acceleration is pressed strongly, the system sends 40% of the torque to the rear axle. The percentage can go as high as 70% when the driver is “forcing” the cornering. The system can even send 70% of torque to the wheel outside the cornering.
Stabilitrak This is the name given to the stability control system of some manufacturers from GM group (Cadillac Chevrolet). See also ESP.
TC/TCS (Traction Control System) The traction control system is a technology designed to limit the wheels slip when they are on a surface with low adhesion. It is using similar sensors to the ABS ones, and is measuring the rational speed differences to determine of one of the wheels is skidding. If it detects such a situation, the system activates the brake on the wheel. Some systems influence the engine activity also, reducing the power directed to the wheels. Still it is important to say that the traction control systems do not improve the traction, but only reduce wheel slipping.
TDI (Turbocharged Direct Injection) Acronym used by Volkswagen to name the direct-injection turbo diesel engines. These work either based on a pump injector principle or the last generation ones, on common-rail.
TFSI (Turbo fuel stratified injection) Acronym used to designate direct fuel injection engines (usually on petrol) with turbocharger boost system. Used by Volkswagen group, the acronym became famous because of the advantages of the engine, such as low consumption and low noxious emission compared to larger engines with larger cubic capacity and equal power.
Tiptronic S This is an automatic transmission with manual function available on Porsche models. The driver can change the gears using the pedals behind the steering wheel or he can drive in the automatic mode which has more programs available. Compared to the Tiptronic generation, Tiptronic S allows the driver to use the manual mode without exiting the automatic one.
TSI Acronym used by Volkswagen group to designate its twin charger technology (turbocharger and supercharger). The first one starts working at 3,500 rpm while the second one works between 0 and 3,500 rpm – with a peak of the activity between 2,400 and 3,500 rpm. Compared to a supercharger engine with two turbochargers – and suffering low regimes from the delayed operating of the turbines (the so-called “lag”) – TSI engines offer respectable torque advantages of a very early crankshaft spins, while increasing to high speed power. The only disadvantage of the system is related to the high complexity and expensive components which limit its use on a larger scale.
VANOS/Double VANOS (Variable Nockenwellensteuerung) Name used by BMW for its variable valve timing system. See VVT.
VarioCam/VarioCam Plus Name used by Porsche for its variable valve timing system. See VVT.
VDC (Vehicle Dynamics Control) Name used by various manufacturers (Alfa Romeo, Subaru, Nissan) for the stability control system. See ESP.
VGRS (Variable Gear Ratio Steering) Alternative name used by Toyota and Honda for variable gear ratio steering system. See Active Steering.
VSA (Vehicle Stability Assist) Name used by Honda for its stability control system. See ESP.
VSC (Vehicle Stability Control) This is the name given by Toyota, Lexus and Daihatsu to the stability control system. See ESP.
VTEC (Variable Valve Timing & Lift Electronic Control) This is the name given by Honda to its variable valve timing system. See VVT.
VVT (Variable Valve Timing) The variable valve timing is a technology that allows varying the duration and the amplitude of the opening/closing of the valves according to the engine load. In a regular engine, cam profile and position result from the necessity to obtain certain performances at the predetermined speed regime. This is where its inefficiency on alternative speed range comes from (lack of torque at low speed or lack of power at high speed). The variable valve timing (by changing the timing of the activity of the valves) solves these disadvantages ensuring the efficient functioning of the engine on a wider speed range.
VVT-i (Variable Valve Timing with intelligence) This is the name given by Toyota to its variable valve timing system. See VVT.
WHIPS (Whiplash Protection System) Name used by Volvo for its system of protection against whiplash injuries in case of a rear impact. See AHC.
xDrive All-wheel drive developed by BMW, which in normal road conditions is distributing 60% of the torque to the rear axle. When the road conditions require, xDrive – whose central element is an electronically controlled multi-plate clutch – can direct up to 100% of torque to either axle, ensuring optimum traction in almost any conditions.