Active Cylinder Management ACT  

Treating resources responsibly: this aim, pursued by Volkswagen, explains the introduction of Active Cylinder Management. For journeys in an engine speed range between 1,400 and 4,000 rpm and at speeds of up to 130 km/h, two of the four cylinders can be deactivated with no perceptible effect, irrespective of the gear selected. This optimises engine efficiency. The multifunction display informs you which mode the engine is currently in.
In vehicles with Active Cylinder Management ACT, fuel consumption can be reduced by up to 0.5 l/100 km and CO2 emissions by 10 g/km in a combined driving cycle. Depending on the driving situation, savings of up to 1 l/100 km are even possible.

A VW Golf’s cylinder

Active Info Display

The Active Info Display supplies vehicle data and information straight to the cockpit. The high-resolution screen replaces the original speedometer and allows the user to adapt five different views to their needs.
For instance, in navigation mode, the speedometer and rev counter move to the edge to allow more space for the map. However, if desired, information such on driving, navigation and assist functions can also be included in the speedometer and rev counter interfaces. The Active Info Display is also connected to other assist systems in the vehicle. This allows infotainment system data shown in the centre console, such as telephone contact images or CD covers, to be displayed directly in the driver’s field of vision.

View of the Active Info Display through the steering wheel

Active recuperation

Active recuperation is a comfort and safety feature of Volkswagen's electromechanical power steering. The feeling of being centred and the building steering torque at the slightest steering angles convey a previously unseen precision. The active recuperation improves steering comfort and the feeling of safety, as fewer steering corrections need to be made.

Engine and wheel rims on the VW Golf R, view from below

Active safety

Active safety encompasses all systems which actively intervene in driving activity to help defuse emergency situations. The main aspects of active safety are as follows:

  • Driving stability: This results in particular from the running gear design with regard to drive concept, suspension and corner stability. Steering precision, brake performance and brake stability are also involved.
  • Condition safety: This describes the impact on occupants caused by vehicle vibrations, noises from the running gear and engine and climatic influences.
  • Perceptual safety: This is improved in particular by good lighting system arrangements and visibility conditions (panoramic view, good view of the rear in the smallest blind corners possible).
  • Operating safety: this is achieved specifically through good ergonomics and logical arrangement of all operating levers and switches, e.g. for lighting, wipers, air conditioning or infotainment. The elements must be as easy as possible to reach from the driver’s seat.

The combination of active and passive safety features ensure optimum protection of all vehicle occupants.

Schematic diagram of the active safety systems in a Volkswagen

Adaptive chassis control DCC  

The adaptive chassis control improves the vehicle’s driving characteristics dramatically. The driver is no longer tied to a specific running gear design and can adapt their vehicle to suit them. They can make their selection with ease at the touch of a button in the centre console.
They can choose a normal, sporty or comfort setting. The electric damping adjustment adjusts automatically. The system reacts constantly to different driving situations.

Schematic diagram of the adaptive chassis control DCC using the example of a VW Golf

Adaptive chassis with active roll stabilisation

The adaptive chassis with electromechanical active roll stabilisation can reduce rolling on corners. As it is electromechanical rather than hydraulic, like conventional stabilisers, the system can react much more quickly within its limits and operate even at low speeds. This enables a palpable boost in steering precision, agility, stability and traction on uneven terrain.


Schematic diagram of an adaptive chassis with electromechanical active roll stabilisation using a Touareg as an example.

Adaptive Cruise Control ACC  

Adaptive Cruise Control ACC uses a distance sensor to measure the distance and speed relative to the vehicles in front.
To do this, the driver sets the speed and the required trailing distance in terms of time. When following vehicles, target and actual distance can be shown by way of comparison in the multifunction display.
A sensor monitors the area in front of the vehicle constantly. The driver can use the accelerator to end ACC and accelerate faster. Pressing the brake pedal immediately deactivates the ACC function. All system notifications are shown in the central multifunction display.
In conjunction with a dual clutch gearbox, ACC brakes the vehicle to a standstill, for instance, in queues or traffic situations. Depending on the situation, the ACC will then start again itself within a set period of time.
Depending on vehicle equipment, ACC can be activated up to a speed of 160 km/h or 210 km/h (Touareg up to 250 km/h).

See also:
Driver assist systems
‘Front Assist’ area monitoring system

Two Volkswagen vehicles seen from above at night. Schematic view of the Adaptive Cruise Control ACC sensor system

Adaptive suspension 

With adaptive suspension, the vehicle’s air suspension can be kept at a constant level on both axles, irrespective of the vehicle’s load level.1 Four height sensors constantly determine the distance between the axles and vehicle body. Differences from the target distance can therefore be offset immediately.1

Different systems are used to compensate in conventional suspension and air suspension. Automatic adaptive suspension can lead to more driving comfort as it helps prevent the rear of the vehicle from sinking when loaded.1 Adaptive suspension can also make journeys with trailers more workable.

1 within the system’s limitations

See also:
Air suspension (CDC)

Schematic diagram of the air suspension with adaptive suspension


The SCR (selective catalytic reduction) catalytic converter converts the exhaust gas component nitrogen oxide (NOx) selectively into nitrogen and water without the formation of undesired side products. The conversion is performed using the synthetic 32.5 per cent reducing agent AdBlue® (ISO 22241-1 / AUS 32), which is added to an additional tank. The dosage is based on the exhaust gas flow rate; engine management in conjunction with an NOx sensor behind the SCR catalytic converter ensure a precise dosage.
Depending on the vehicle, the customer may also have to top up AdBlue® themselves, or have it topped up by their authorised workshop, between services. provides a free service helping customers who top up themselves find suitable filling stations.

See also:
NOx exhaust gas treatment

Ansicht eines Cockpit Displays mit Anzeigen der Füllstände AdBlue

Additional instrument 

The displays in the additional instrument above the centre console - optionally available or part of special equipment bundles for the Scirocco, Beetle and Beetle Cabriolet - inform the driver of charge pressure and engine oil temperature. The multifunctional stopwatch measures idle time and journey times.

VW additional instruments with engine oil temperature control, turbo charge pressure control and centre function stopwatch


The aerodynamics of a vehicle’s body have an impact on fuel consumption, maximum speed and noise emissions. The drag coefficient detected in the wind tunnel sums up the aerodynamic properties. This value is affected by different sizes, such as the body shape (saloon, van or hatchback). The design of the underbody also has an impact. The drag is produced by the displacement of the air surrounding the vehicle and its friction with the vehicle surface.

The formula for calculating drag is as follows:
Drag = vehicle speed squared x end face x Cd x ½ air density.

The typical economical Volkswagen body design and narrow panel gaps and spaces reduce turbulence and facilitate a low level of drag, ensuring economical consumption levels and lower CO2 emissions. However, the most important influencing factor is the vehicle speed, as when the speed doubles, drag quadruples.

See also:


VW Golf R on a racetrack, front view
Fuel consumption Golf R in l/100 km: urban 8.2-8.1 / extra-urban
6.6-6.5 / combined 7.2-7.1; CO₂ emissions combined, g/km: 164-162;
efficiency class: D


Together with the seat belt, airbags reduce the risk of severe injuries to the head and chest in collisions causing correspondingly severe accidents. If the crash sensors record an impact that meets the trigger value, the airbag control unit starts the gas generator. It fills the airbag within 35 to 45 milliseconds. The activated airbags restrain the head and upper body and distribute the impact over as wide an area as possible. After just 120 milliseconds, the gas has escaped and the airbag has collapsed. Optimum protection is only provided if the vehicle occupants are properly strapped in, as the airbags and belt tensioner work together to form a coordinated safety system. As well as the front airbags, side airbags, knee airbags and a curtain airbag system are also available.

See also:
Crash test

Schematic diagram of two curtain airbags in a Golf

Airbag control unit

The airbag control unit detects and measures a collision and activates the relevant restraint systems according to the type and severity of the accident. Up to six external acceleration sensors (crash sensors) supply the control unit with information.
The airbag control unit is equipped with accelerator sensors for the vehicle’s longitudinal, transverse and vertical axes. The control unit also has a yaw rate sensor, which records the vehicle’s rotation along its longitudinal axis. The sensors in the control unit measure and compare the signals from the other sensors. This allows the control unit to assess the direction and severity of the accident and to trigger the relevant restraint systems. The control unit is connected to other CAN data bus systems via the crash signal outputs, to make orientation and rescue of occupants easier after an accident.
Volkswagen’s extensive research and constant development have helped refine control of the restraint systems so they offer optimum protection in a wide range of different types of accidents. The two-step triggering of the front airbag, which depends on the severity of the accident, helps reduce the risk of injury further for drivers and passengers. The system can distinguish between an accident and a strong shock, which might be caused by impact from a stone or a deep pothole, for instance. This ensures that no restraint systems are triggered if the vehicle has not crashed.

Schematic diagram of the airbag control unit in a Volkswagen

Air conditioning system 

The main components of the air conditioning system are the cooling system, heating and blower unit. It enhances a vehicle's ventilation system.

Volkswagen offers a semi-automatic air conditioning system and a ‘Climatronic’ automatic air conditioner for its models.

‘Climatronic’ regulates the interior temperature based on a preset preferred temperature, automatically adjusting the blower speed and operating the air distribution flaps. It therefore offers a comfortable climate in practically all operating and weather conditions and air flow through the passenger compartment with as little draught as possible. The ‘Climatronic’ electronic control system records all major influencing factors and disturbances and supplies more or less cool air accordingly.

Additional comfort features are available thanks to integration of the control unit into the CAN bus: Automatic air recirculation on activating windscreen washing or going into reverse gear protects vehicle occupants from unpleasant odours. The speed-based blower speed control with automatic vent temperature adjustment reduces noise levels on slow journeys.

‘Climatronic’ also activates the defrost function for foggy or icy windows at the touch of a button. At high blower capacity, the entire air flow is steered towards the inside of the window. If the outside temperature is over 2.5 °C, the cooling system also kicks in to dry the air.

In this way, ‘Climatronic’ by Volkswagen improves the wellbeing of vehicle occupants and boosts comfort and visibility. The pleasant temperature control helps maintain the driver’s ability to react and concentrate.

Depending on the vehicle, different equipment is used:

- Air conditioning system with 1-zone temperature control

- Air conditioning system with 2-zone temperature control: splits the passenger compartment into two climate zones. Drivers and front passengers can select their own temperatures separately.

- Air conditioning system with 3-zone temperature control:

drivers, front passengers and passengers in the rear passenger compartment can adjust their own temperatures separately.

‘Air Care Climatronic’ air conditioning system with 2- or 3-zone temperature control

(An active biogenic filter also pretends fungal spores and tiny allergens from entering.)

Image of the air conditioning system in a VW Up!

Air Curtains

The term ‘air curtain’ refers to narrowing air inlets in the vehicle’s front bumper. The air inlets below the headlights ensure that the air is guided through the bumper and only re-emerges behind the wheel housing. The wheels are not affected. This improves the aerodynamics while increasing the surface pressure of the vehicle front end.

VW Golf R viewed from below at an angle, air curtains detail
Fuel consumption Golf R in l/100 km: urban 8.2-8.1 / extra-urban
6.6-6.5 / combined 7.2-7.1; CO₂ emissions combined, g/km: 164-162;
efficiency class: D

Air quality sensor  

The air quality sensor is part of Volkswagen's ‘Climatronic’ automatic air conditioning system. Its job is to detect harmful substances in fresh air which occur as oxidisable or reducible gases. Oxidisable gases include, for instance, carbon monoxide (CO), hydrocarbons (benzene or petrol vapours) or other fuel components which have not completely combusted. Nitrogen oxides (NOx) are reducible gases.

In poor-quality air, such as in traffic jams or when driving through a tunnel, the control system activates ‘Climatronic’ air recirculation and prevents the polluted fresh air from damaging the air quality in the vehicle interior.

See also:
Air conditioning system