roll-up sun-blind

Sliding sunroof
frame
(plastic)
Roll-up sunblind

Sliding sunroof motor

Lifting arm
guide frame

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17

Bumper system
Front bumper
Characteristic elements of the vehicle's front end are the
one-piece bumper cover and single-frame radiator grille.
Large air intakes are located at the lower front.

Shock
absorber

ACC radar sensor
Impact absorber
Bumper cover locking element
Radiator
grille

Front bumper cover

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Underbody
The Audi A3 has a highly effective acoustic and aerodynamic underbody designed to withstand mechanical and
thermal stresses. In addition to aerodynamics, attention
was paid to sound absorption, body protection and thermal
engine management during the development phase.

The result is improved airflow around the engine and transmission capsule, the cross-members and the wheel arches,
thus allowing a low drag coefficient (cw) of 0.31 to be
achieved.

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18

Passive safety
Components
The passive occupant protection system has the following
components:

•
•
•
•
•
•
•
•
•
•
•
•

Airbag control module
Driver and passenger airbags
Front side airbags
SIDEGUARD® head airbags
Driver and passenger side knee airbag
Front airbag crash sensor
Crash sensors for side impact detection in the doors
Crash sensors for side impact detection in the C pillars
Front inertia reel seat belts with electric and pyrotechnic
belt tensioners
Safety belt warning for all seats
Safety belt switches on all seats in the seat belt buckles
Safety occupancy sensor in front passenger seat
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Optional equipment

•

Rear passenger side impact airbags

Vehicle Airbags

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19

Passenger front airbag
The 2015 A3 sedan for the North American market will
come equipped with a two-stage adaptive hybrid gas
generator front passenger airbag.

Front Passenger Airbag Igniter 1

Front Passenger Airbag Igniter 2

Gas generator

Housing
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Driver and passenger knee airbags
The Audi A3 sedan is equipped with both driver and
passenger knee air bags. Both airbags use tubular hybrid
gas generators.
Driver Knee Airbag

Passenger Knee Airbag

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20

Front safety belt tensioner
In combination with Audi pre sense basic, the 2015 Audi A3
is equipped with reversible safety belt tensioners driven by
electric motors. This is in addition to the pyrotechnic belt
tensioners.
When Audi pre sense basic detects specific driving situations, signals are sent to the data bus. The airbag control
module evaluates the signals and, if necessary, instructs
the seat belt tensioner control module to partially or fully
tension the safety belts via an electric motor. For further
information on Audi pre sense, refer to the chapter on
Active safety, page 25.

Safety belt tensioner
control module

Reversible tensioner
with electric motor

Active belt force
limiter

Pyrotechnic safety
belt tensioner
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21

Pelvic belt tensioner with locking buckle
The 2015 A3 will be equipped with pyrotechnic tensioning
safety belts that help to reduce injury to the pelvic area
during certain types of collisions.
Vehicles with this style safety belts will also have a new
locking-type buckle.
In certain types of accidents, the pelvic belt tensioners, in
conjunction with the new locking buckle, help protect the
occupant in the following manner:

•
•
•
•

To help separate the pelvic force from the thoracic
force
To help reduce the chest deflection force
To help limit the movement of the pelvis
To help improve the contact between the pelvis and
seat

Lock buckle

Automatic safety belt retractor

Safety belt guide
piece

Coupling

Belt tensioner

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Operation during an accident
When the Airbag Control Module determines the criteria
for an accident severe enough to deploy the pyrotechnic
safety belts has been exceeded, the shoulder portion of the
safety belt is tensioned from the clamping point of the
locking buckle in the direction of the belt tensioner by the
pyrotechnic devices in the automatic safety belt retractor.
At the same time, the retractors are triggered and the lap
portion of the safety belt is tensioned by the movement of
a steel cable attached to the safety belt.

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22

Locking buckle
A newly designed safety belt buckle is used. The lock
buckle prevents movement and forms a separate load path
for the shoulder and lap portion of safety belt in the event
of an accident.

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Design and operation
The locking buckle has a movable spring loaded piece that
allows the safety belt to move freely under normal operating conditions.

Cover

During an accident in which the Pelvic belt tensioner has be
triggered, the locking piece is displaced and blocks the
safety belt from moving.

Seat Belt

locking piece with spring

Lock buckle

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23

Function
Not blocked

Locking piece

Seat belt

Lock buckle
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Blocked

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24

Active Safety
Audi pre sense
Audi pre sense is able to detect critical driving situations,
and initiate measures to prepare the vehicle and occupants
for an impending collision.

Please note that Audi pre sense cannot prevent collisions.
It serves only to assist the driver and potentially reduce the
severity of the collision.

This is made possible by networking various in-vehicle
systems. The systems send data continuously to the data
bus. Other control modules are able to evaluate this information and take appropriate action.

Audi pre sense basic
Longitudinal dynamics function
When vehicle is moving forward at a speed greater than
18.6 mph (30 km/h) and the driver executes a “hazard
braking maneuver” in which the brake pressure reaches a
defined level, the reversible safety belt tensioners are
partially tensioned.

Drive profile selection switch module
E592

If the ESP is set to “Sport” or “OFF” using either the ASR/
ESP Button, Driving Profile Selection Switch or if the Audi
drive select is set to “dynamic” via the MMI, the safety belts
will not be partially tensioned.

ASR/ESP Button
E256

609_075

609_076a

Emergency braking function
During an “emergency braking” maneuver in which the
brake pressure exceeds a defined value for a defined period
of time, the reversible safety belt tensioners are fully
tensioned by the electric motors.

25

In this scenario, the Airbag Control Module evaluates
the signals sent on the data bus from the ABS/ESP Control
Module, then it instructs the Seat Belt Tensioner Control
Modules to fully tension the safety belts. Depending on the
situation, the ABS/ESP Control Module can also activate the
hazard warning flashers.

Transverse dynamics function

Crash function in the low speed range

If the vehicle oversteers or understeers, the ESP system
tries to stabilize it. If the vehicle becomes unstable because
certain physical limits have been exceeded, the Airbag
Control Module initiates a partial tensioning of the electrically reversible safety belt tensioners.

If the Airbag Control Module detects a head-on collision with
low vehicle deceleration (no airbag deployment), it decides
whether or not to fully tension the safety belts based on a
situation-specific control module algorithm.

If the vehicle can no longer be stabilized, the safety belt
tensioners are fully tensioned.

It does not take any other precautions, such as turning on the
hazard warning flashers, or closing a window or sunroof.

At the same time, the side windows and the tilt/slide
sunroof (if installed) begin to close.

•

If ESP is set to "Sport" or "Off" or if Audi drive select is
set to "dynamic", the safety belts are not partially tensioned.

•

If ESP is set to "Sport" mode or "Off", the safety belts are
fully tensioned only if the driver actively applies the
brakes.

Audi pre sense front
Driver Assistance Systems
Front Camera

Audi pre sense front is optional and is offered only when
the vehicle is equipped with Adaptive cruise control.
The Distance Regulation Control Module monitors the
traffic in its path and continuously measures the distance
between itself and a vehicle driving ahead.
The module evaluates relevant data from other control
modules and transfers signals to the data bus. The ACC
control module uses these signals to initiate various actions
between the ABS/ESP Control Module and the Instrument
Cluster Control Module as necessary.
Audi pre sense front is active even if the ACC system is not
activated. It has the following functions:

A

Providing driver warning information when following a vehicle ahead at a critical distance in certain
situations.

B

In the event of an impending collision with a
moving or stopped vehicle, the driver is warned
and assistance is provided by automatic braking or
by increasing the braking force applied by the
driver, which reduces reaction time and vehicle
speed.

C

625_054

Distance Regulation
Control Module

Full deceleration is provided in the event of an
impending collision with a moving, stopped or
stationary vehicle at a speed of less than 18.6 mph
(30 km/h).

26

Function A
The driver is warned visually by a message in the Driver
Information System when approaching another vehicle
ahead or when following this vehicle at a critical distance at
a synchronized speed.

Approaching
vehicle driving ahead

Speed
synchronization

The critical distance is defined as the distance at which a
collision is likely to occur in the event of sudden heavy
braking of a vehicle driving ahead, even if the driver of the
following vehicle reacts quickly.

Following at a critical distance
including visual distance warning
(ACC warning lamp)

Collision

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Function B
When the vehicle approaches a moving vehicle, the Instrument Cluster Control Module warns the driver visually and
audibly if certain defined limits are exceeded. These warnings are issued within a certain period of time prior to the
last braking opportunity for collision avoidance before the
actual collision.
The timing of warnings depends on the driver's degree of
activity. Depending on steering, pedal and turn signal
inputs, the system classifies the driver as active or inactive
and, consequently, as attentive or inattentive. If the driver
is attentive, the warning will be issued later than for an
inattentive driver.
At the same time, the ABS/ESP Control Module prefills the
brake system and modifies the deployment algorithms for
Hydraulic Brake Assist. This means that Hydraulic Brake
Assist begins to build up brake pressure even at low brake
pedal actuation speeds.
If the driver does not respond to the warnings or, for
example, eases off the accelerator, the ABS/ESP module
performs a warning braking application.
The warning braking application is a very brief but easily
noticeable braking operation and does not serve to slow the

Prefill
brake system
Hydraulic Brake Assist
reacts with higher
sensitivity

Driver warning
visual, audible
(forward collision
warning)

vehicle down. It alerts drivers to the traffic situation and
indicates to drivers that they must react immediately in
order to avoid an impending collision. Depending on how
attentive the system evaluates the driver to be, the
warning braking application occurs within a specific period
of time ahead of the last opportunity for braking and
evasive action in order to avoid a collision.
If the driver still fails to react or ease off the accelerator,
the vehicle is braked by partial braking operation I, which
applies up to 35% of maximum braking force.
If Driver Assistance Systems Front Camera also detects the
obstacle, the braking force is increased to up to 60% of the
maximum by partial braking operation II.
If the driver applies the brakes, a target braking action can
be performed in all phases described above (prefill brake
system, reconfiguration of Hydraulic Brake Assist, driver
warning, warning braking application, partial braking
operations I and II). During the target braking action, the
Audi pre sense front system calculates whether the driver is
applying sufficient braking force to be able to avoid a
collision. If this is not the case, the required brake pressure
is increased depending on the situation.

Warning
braking

Partial braking operation I or
partial braking operation II
(on models with front camera
for driver assistance systems)

Collision

Target braking

27

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Function C
Audi pre sense front also includes a function for “full deceleration at speeds from 18.6 mph (30 km/h).”
If the Distance Regulation Control Module detects an
impending collision when the vehicle is travelling at a
speed of less than 18.6 mph (30 km/h), ABS/ESP Control
Module pre-fills the brake system.
The deployment algorithms for Hydraulic Brake Assist are
adjusted at the same time. Hydraulic Brake Assist thus
begins to build up brake pressure even at low brake pedal
actuation speeds. If the driver fails to brake or does not
apply sufficient braking force in a critical situation, the
ABS/ESP Control Module executes a braking action and
applies near-maximum braking if necessary.

Prefill
brake system
Hydraulic Brake Assists reacts
with higher sensitivity

Before the braking action occurs, the driver is alerted both
audibly and visually through the DIS that the vehicle is
about to brake independently or provide additional braking
force.
If the vehicle has independently braked to a standstill
without driver intervention, three more audible signals are
given.
The three additional signals given alerts the drivers that
they must actively take control over the vehicle by applying
the brake. If the driver fails to take control (especially in a
vehicle equipped with an automatic transmission) the
vehicle will begin to roll.

Full deceleration with
visual and audible driving warning
prior to intervention

Collision

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System characteristics with respect to "full
deceleration at speed of less than 18.4 mph
(30 km/h)"

•

The driver is not given advance warning.

•

The system reacts to crossing or oncoming vehicles and
objects with low radar scatter (for example, pedestrians).

•

The system reacts to vehicles which are travelling in the
same direction, have stopped or are stationary.

Driver prioritization over system
If the driver clearly takes evasive action, accelerates or
brakes during the individual phases of Audi pre sense front
(functions A to C), the action momentarily being taken by
Audi pre sense front (for example, partial braking operation I)
will be suppressed or cancelled.
If the obstacle is no longer relevant after evasive action has
been taken, Audi pre sense front will cease to provide
assistance in this case.

28

Settings and displays
There are two options for deactivating Audi pre sense front
in the MMI.

•

Option 1: Prewarning off – the audible and visual warnings (distance and forward collision warnings) are
deactivated.

•

Option 2: System off – the audible and visual warnings
(distance and forward collision warnings), warning
braking, partial and target braking and the "full deceleration at speeds of below 18.4 mph (30 km/h)" functions
are deactivated. The functions remain deactivated until
they are reactivated in the MMI.
Both versions of Audi pre sense are activated

609_078a

If only the pre-warning has been deactivated, no text
message is displayed in the DIS.
If the system has been deactivated, the driver is warned by
a text message in the DIS - Audi pre sense off - whenever
the ignition is switched on. This alerts the driver to the fact
that the system is switched off.

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If the ESP is set to “Sport” or “OFF” using the ASR/ESP
Button, then the audible and visual warnings, the warning
braking, the partial and target braking, and the "full deceleration at speeds of below 30 kph" functions of Audi pre
sense will also be deactivated.

Audi pre sense remains deactivated until:

•

ESP is reactivated with the ASR/ESP button.

•

the ignition is switched off and on again, thereby
reactivating ESP.

•

ACC is activated, since this would result in automatic
activation of ESP.

If ESP (Electronic Stabilization Program) is set to "Sport" or
"Off", the following text is temporarily displayed in the DIS:
"Audi pre sense: off".

29

Notes