Data bus  

The data bus is used for rapid exchange of all possible information between sensors, actuators and control units etc. in the vehicle. It ensures that information from one sensor can be passed on to several control units via digital exchange and processed in said control units. This greatly reduces the risk of a complete breakdown.
An example of how this works, for instance, is the rain sensor: if this says ‘it’s raining’, the data bus activates the wiper, brake disc wipe function, windscreen ventilation and light.

Daytime headlights  

Additional light reducing the risk of an accident in daylight.
Daytime headlights:
Dipped beam headlight switched on during the daytime
Daytime running light:
Separate light built into the headlight
The functions switch on automatically when the engine is started.

Front view of Volkswagen at night, headlight detail

Daytime running light 

Additional light reducing the risk of an accident in daylight

Daytime running light
Separate lights built into the headlight or bumper. The Passat and Polo are examples of vehicles with daytime running lights in their bumpers.

Daytime headlight
Dipped beam headlight switched on during the daytime

The functions switch on automatically when the engine is started.

VW Touran viewed from front with headlight with LED daytime running light on a parking space, an industrial area in the background

Diesel direct injection  

In diesel direct injection, the fuel is injected directly into the combustion chamber. Diesel with direct injection is currently the most efficient combustion engine with the highest level of efficiency. With high-pressure injection, the diesel engine finally reached a level of performance that is comparable with modern petrol engines with exhaust gas turbocharging.

See also:

Image of direct fuel injection

Diesel particulate filter

A diesel particulate filter is a system for removing diesel soot from diesel engine exhaust gases.
The filter with the catalytic coating operates without additives and uses a filter coating containing precious metals that works in two ways. Passive regeneration involves a slow, gentle conversion of soot in the catalytic converter into CO2. This process takes place within a temperature range of 350 - 500 °C and runs continually without special measures being taken, primarily in mainly motorway operation.
Only in longer operation with low load, such as in city traffic, does an active increase in exhaust gas temperature to around 600 °C ensure additional filter regeneration every 1,000 to 1,200 kilometres. The particulates stored in the filter burn off at this temperature.

See also:
Catalytic converter

Image of the diesel particulate filter in a Volkswagen

Differential lock  

A differential balances different wheel speeds in the case of driven axles.
Different wheel speeds occur when the wheels on one axis cover distances of different lengths when taking a corner. So, for instance, the wheel on the outside of the corner is turning faster than the wheel on the inside. In most cases, a bevel wheel differential balances speed on driven axles. A differential lock prevents one wheel from turning freely and directs the force to the wheel with better traction. Speed balancing can be blocked manually or automatically up to 100%. This means that on a slippery surface, for instance, up to 100% of the force can be directed to the wheel with the best traction.
Vehicles with all-wheel drive require a transfer box which distributes the drive torque between the front and rear axle. As the axles turn at different speeds when taking corners, speed balancing is also required here. The differential used here is known as the centre differential.

See also:
Electronic differential lock XDL

VW Arteon seen from above at night, making a right turn. The differential lock sensor system is shown using arrows.

Digital radio DAB

With the Digital Audio Broadcasting System (DAB), the radio or radio navigation system receives not only audio signals (music and voice), but also data signals (information on traffic, schedule, music, weather, etc.). If the radio or radio navigation system is equipped with a suitable display, graphics such as maps or animations can also be displayed.

See also:
Radio navigation system

Interior view of a VW Arteon with focus on the on-board computer and digital radio

Digital Sound Processing (DSP)

Volkswagen's Digital Sound Processing offers a new dimension to listening. A special algorithm can control the sounds in the vehicle interior and offers an almost equally balanced sound experience at every seat. It distributes sound around the listeners as in a concert hall. The spatial impression is even improved in conventional stereo sources, which are converted for playback in several different audio channels.

Interior view of a VW Golf, front side speaker detail

Direct injection  

There are different types of direct injection:

  • Direct petrol injection
  • Diesel direct injection

See also:
Direct petrol injection
Diesel direct injection

Image of a Volkswagen direct injection

Direct petrol injection engine  

In a direct petrol injection, fuel is injected straight into the combustion chamber with a maximum pressure of over 100 bar. In comparison to conventional injection into the intake manifold, this process is much more precise and does not depend on valve opening times.
A special combustion chamber shape ensures optimum circulation of the fuel and air mixture. Volkswagen motors with a direct petrol injection engine offer outstanding efficiency. Fuel savings in comparison with motors with the same performance and conventional injection technology can be up to 15% with an adjusted driving style. The direct petrol injection engine is the basis for innovative TSI technology.

See also:

Image of Volkswagen direct petrol injection engine

Distance radar

The distance radar is part of the Adaptive Cruise Control ACC.

See also:
Adaptive Cruise Control ACC
‘Front Assist’ area monitoring system
Driver assist systems

Two Volkswagen vehicles seen from above at night. The distance radar sensor system is shown using lines.

Diversity aerial

High-rise buildings and mountains reflect the electromagnetic waves from radio and TV broadcasters. This means that an aerial does not just receive a signal but also delayed reflections which can lead to a deterioration in the quality of reception. This is known as multipath distortion. In diversity aerials, several (up to four) aerials receive the radio signal, and the receiver filters out most of the signal distortions by skilfully connecting the aerials’ signals. This ensures the best reception quality and an outstanding radio sound even in situations where reception is difficult.

Side view of the VW Arteon R-Line, roof with diversity aerial detail

Double wishbone axle

In the double wishbone axle, the hub carrier is carried by two triangular wishbones and a track rod. The suspension strut on the lower wishbone is responsible for vertical support. This suspension system is characterised by its compact height and large loading width and offers particularly beneficial wheel suspensions for sporty running gears. This is convenient for features such as the 4MOTION drive, transferring higher load forces and a high level of directional stability. The double wishbone axle is compact and prevents strong load change reactions in combination with a suitably positioned track rod. Other designs include the highly compact longitudinal double wishbone axle and trapezium link rear axle.

See also:
MacPherson axle
MacPherson suspension strut
Semi-trailing arm axle
Multi-link rear axle
Trapezium link rear axle
Torsion beam rear axle
Four-link front axle

Driver Alert System 

The Driver Alert System recommends that the driver take a break based on specific parameters. After all, a lack of attention and increased tiredness can, in the worst case scenario, cause the vehicle to leave the road. That’s why the Driver Alert System detects deviations from normal driving behaviour and provides support on long journeys.

To do this, from a speed of 65 km/h, the system continually analyses driving behaviour and draws conclusions on the driver’s fitness to drive.

Various signals, such as steering behaviour, are analysed. If tiredness is detected, the system recommends that the driver take a break by means of a visual and audio signal. The Driver Alert System therefore helps the driver make the right decision.

See also:
Driver assist systems

Driver Alert System ‘break’ warning lamp

Driver assist systems  

Volkswagen aims to enable accident-free driving with forward-looking vehicles. Driver assist systems help detect critical situations in advance and help reduce the risk of accidents. They offer drivers more comfort and make driving easier for them.

See also:
Adaptive Cruise Control ACC
‘Front Assist’ area monitoring system
‘Lane Assist’ lane keeping system
‘Park Assist’ parking assist system
Proactive occupant protection system
‘Side Assist’ lane change system
‘Rear View’ camera system

Two Volkswagen vehicles driving on a road, one in front of the other. The driver assist systems’ sensor system is shown using lines between the vehicles.

Driving cycle  

The legislator prescribes standardised test procedures for the type testing of new vehicles. The procedures measure exhaust emissions, consumption and CO2 emissions, as well as the range with electric vehicles. In the past, this was done in the EU on the basis of the New European Driving Cycle (NEDC). The latter was superseded in September 2018 by the WLTP (Worldwide Harmonized Light Vehicles Test Procedure). The WLTP is intended to provide customers with more realistic current consumption values and ranges. The new test cycle is considerably longer and the test procedure is significantly more complex than the previous one.

Driving mode selection  

Driving mode selection makes it possible to implement personalised settings which have a direct impact on the vehicle in a specific context. Depending on the mode selected, steering, motor characteristics and gearbox control are adjusted to suit the driver’s personal driving style.
Five different modes are available for selection: Eco (economical), Sport (sporty), Normal, Comfort and Individual (individually combined).

Interior of a Volkswagen focusing on the on-board computer with driving mode selection

Driver steering recommendation  

Driver steering recommendation is a safety function that is implemented by the electromechanical power steering:
in critical situations, it tells the driver which direction they should steer in to stabilise the car. Of course, with this function, the vehicle does not steer itself, but makes steering in the right direction easier than in the wrong one.

See also:
Electromechanical power steering

Interior view of the VW Passat R-Line

DSG dual clutch gearbox  

Dual clutch gearboxes consist of two separate gear train halves. Depending on the gear, the two gearboxes are alternately connected to the engine in a force-locking manner via the double clutch using two drive shafts. The dual clutch therefore enables automatic switching without an interruption in traction. The gearbox is controlled using what is known as a mechatronic module, where the electronic gearbox control unit, various sensors and hydraulic mechanism are combined in a compact unit.
The dual clutch gearbox DSG (direct shift gearbox) has two driving programs: normal and sport mode. In sport mode, the DSG goes further up the gears and shifts down a gear sooner if necessary. However, the gears can also be switched manually. This can be done with great sporting effect using the Tiptronic switch on the multifunction steering wheel. However, clutch operation is always fully automatic. The six-gear DSG is designed for more powerful performance and torques over 250 Nm. The dual clutch consists of two multiplate clutches running in an oil bath.

The seven-gear DSG is available in two different specifications:

  • for smaller engines: The maximum torque is 250 Nm. The dual clutch here runs dry, without an oil bath.
  • for engines with higher loads: The maximum torque is 600 Nm. This DSG is therefore designed for higher torques.
Interior view of a VW Golf, clutch gearbox in centre console detail

Dynamic headlight range control

Dynamic headlight range control ensures optimum headlight settings and road illumination. It ensures a consistent headlight range for all vehicle load levels and stops the vehicle from dazzling oncoming traffic. The system operates automatically and adapts the headlights’ angle of inclination to the current load level.
Dynamic headlight range control offsets the load from passengers and luggage and corrects the headlight setting when starting, accelerating and braking.
The control unit processes signals from the electronic speedometer and ABS control unit as well as signals from incline sensors. This allows the system to distinguish whether the vehicle is at a standstill or driving steadily. The control unit also differentiates changes in speed signals (accelerating and braking). The headlight range is adjusted in split-seconds. Depending on speed, the motors in the headlights ensure optimum light distribution, whether you’re on the motorway, a country road or in the city. If the vehicle is equipped with xenon light, automatic headlight range control is legally required. Volkswagen also uses dynamic headlight range control as standard.

See also:
Bi-xenon headlights

Front view of a Volkswagen, headlight detail

‘Dynamic Light Assist’ advanced main-beam control

‘Dynamic Light Assist’ offers improved road illumination to ensure more comfort when driving in city traffic.
The variable road illumination system makes it possible to keep the main beam headlight on when driving without dazzling oncoming traffic. A masking function makes it possible to partially dip the main beam headlight. Information on other road users and road illumination is recorded by a camera on the interior mirror which informs the ‘Dynamic Light Assist’ system. This improves overall road illumination dramatically.
‘Dynamic Light Assist’ gives lighting a brand new feel that always suits the traffic situation.

See also:
Bend lighting

A Volkswagen on a road by night from above. Light Assist is shown as a beam of light

Dynamic parking brake auto release function

The dynamic parking brake auto release function increases driving comfort on starting in vehicles with an electronic parking brake. The driver can simply start driving without releasing the electronic parking brake first. This is particularly useful for ‘hill starts’.
To ensure the best possible start, some models with manual gearboxes have a clutch sensor that assesses the clutch mechanism and ensures an optimum reaction from the system. Simply press on the accelerator and release the clutch to put the vehicle in motion. In models with automatic gearboxes, all the driver needs to do is press on the accelerator. From a technical perspective, the electronic parking brake control unit assesses the signals on engine torque and speed, gradient and acceleration and clutch pedal position, in order to determine the ideal point at which to release the brake.

See also:
Parking brake, electronic
Auto Hold function

Interior view of a Volkswagen with focus on the dynamic parking brake auto release function on the

Dynaudio sound system

The ambitious DYNAUDIO sound system consists of high-quality speakers with DSP (Digital Signal Processor) technology and a digital multi-channel amplifier. The speakers and their installation position are adapted precisely to the vehicle interior. The result is a rich spectrum of sound that has previously only been found in the high-end segment.
This sound experience is achieved with equipment including sophisticated textile dome tweeters and high-quality bass speakers. They create a natural resolution of high and deep frequencies and an even distribution of sound across the entire interior. The membranes are also particularly high quality thanks to the especially light, stable and almost resonance-free MSP (magnesium silicate polymer). Special double magnets guarantee a dynamic and robust performance.

DYNAUDIO Executive Surround in the VW Tiguan