child restraint MERCEDES-BENZ S-CLASS COUPE 2015 Owners Manual

Care
360° camera ................................ .350
Automatic car wash ....................... 345
Carpets .......................................... 353
Display .......................................... .351
Exhaust pipe .................................. 351
Exterior lighting ............................ .349
Gear or selector lever .................... 352
High-pressure cleaner .................... 347
Interior .......................................... .351
Matt paintwork .............................. 348
Night View Assist Plus ................... 351
Notes ............................................. 345
Paint .............................................. 347
Plastic trim ................................... .352
Reversing camera .......................... 350
Roof lining ...................................... 353
Seat belt ........................................ 353
Seat cover ..................................... 352
Sensors ......................................... 349
Steering wheel ............................... 352
Trim pieces ................................... .352
Washing by hand ........................... 347
Wheels .......................................... .348
Windows ........................................ 348
Wiper blades .................................. 349
Wooden trim .................................. 352
CD player (on-board computer) ........254
Central locking
Locking/unlocking (key ).................. 85
Centre console
Overview .......................................... 36
Stowage space .............................. 317
Centre console in the rear com-
partment
Stowage compartment .................. 319
Changing the media source ............. 254
Child
Restraint system .............................. 61
Child seat
Forward-facing restraint system ...... 64
ISOFIX .............................................. 62
On the front-passenger sea t............ 63
Rearward-facing restraint system .... 64
Recommendations ........................... 68
Suitable positions ............................ 65
Top Tether ....................................... 62
Cigarette lighter ................................ 324 Cleaning
Mirror turn signal ........................... 349
Climate control
Automatic air conditioning ............. 139
Auxiliary heating/ventilation .......... 149
Controlling automaticall y............... 142
Convenience opening/closing
(air-recirculation mode) ................. 146
Cooling with air dehumidification .. 141
Demisting the windows .................. 144
Demisting the windscreen ............. 144
ECO start/stop function ................ 140
Indicator lamp ................................ 142
Ionisation ....................................... 149
Notes on using the automatic cli-
mate control .................................. 140
Overview of systems ...................... 138
Perfume atomizer .......................... 147
Problem with the rear window
heating .......................................... 146
Problems with cooling with air
dehumidification ............................ 142
Setting the air distribution ............. 143
Setting the air vents ...................... 155
Setting the airflow ......................... 144
Setting the climate mod e............... 143
Setting the temperature ................ 143
Switching air-recirculation mode
on/of f............................................ 146
Switching on/of f........................... 141
Switching residual heat on/off ...... 147
Switching the rear window heat-
ing on/of f...................................... 145
Switching the synchronisation
function on and off ........................ 144
Cockpit
Overview .......................................... 30
COLLISION PREVENTION ASSIST
PLUS
Activating/deactivating ................. 260
Display message ............................ 274
Operation/note s.............................. 72
COMAND display
Cleaning ......................................... 351
Combination switch .......................... 128
Consumption statistics (on-board
computer) .......................................... 250
Convenience closing feature ............ 101 Index
7

General notes ................................ 330
Important safety notes .................. 330
Opening/closing the garage door .. 332
Programming (button in the rear-
view mirror
) ................................... 330
Synchronising the ro lling code .......331
Gear indicator (on-board com-
puter, Mercedes-AMG vehicles) ....... 265
Gearshift program
SETUP (on-board computer) .......... 265
Genuine Mercedes-Benz parts ........... 23
Glove compartment .......................... 317H
HANDS-FREE ACCESS .......................... 96
Hazard warning lamps ......................128
Head restraints
Adjusting ....................................... 111
Adjusting (manually) ..................... .111
Adjusting (rear) .............................. 112
Head-up display
Adjusting the brightness ................ 262
Displays and operating .................. 247
Function/notes ............................ .247
Important safety notes .................. 247
Selecting displays .......................... 261
Setting the position ....................... 262
Storing settings (memory func-
tion) ............................................... 123
Headbag
Display message ............................ 277
Headlamp flasher .............................. 128
Headlamps
Misting up ...................................... 132
see Automatic headlamp mode
Heater booster function ................... 153
Heating
see Climate control
High-pressure cleaners .................... 347
Hill start assist .................................. 164
HOLD function
Activating ....................................... 206
Activation conditions ..................... 206
Deactivating ................................... 206
Display message ............................ 291
Function/notes ............................ .205
General notes ................................ 205 Horn
...................................................... 30
HUD
see Head-up display I
Ignition lock see Key positions
Immobiliser .......................................... 80
Indicator and warning lamp
Restraint system ............................ 309
Indicator and warning lamps
COLLISION PREVENTION ASSIST
PLUS .............................................. 312
Coolant .......................................... 310
Engine diagnostics ......................... 310
Indicator lamps
Display message ............................ 280
see Warning and indicator lamps
Indicators
see Turn signals
Insect protection on the radiator .... 340
Instrument cluster
Overview .......................................... 32
Warning and indicator lamps ........... 33
Instrument cluster lighting .............. 244
Intelligent Light System
Activating/deactivating ................. 262
Display message ............................ 282
Overview ........................................ 129
Setting the dipped-beam head-
lamps for driving on the right/left .. 263
Interior lighting
Control .......................................... .132
Emergency lighting ........................ 133
Overview ........................................ 132
Reading lamp ................................. 132
Interior motion sensor
Deactivating ..................................... 82
Function .......................................... .81
Priming ............................................ 81
Switching off .................................... 82
ISOFIX child seat securing system ....62 J
Jack Storage location ............................3 5712
Index

Night View Assist Plus
Activating/deactivating ................. 234
Cleaning ......................................... 351
Display message ............................ 290
Function/note s............................. 232
Pedestrian and animal recogni-
tion ................................................ 233
Problem (fault) ............................... 236
Switching automatic activation
on/of f............................................ 259
Notes on running in a new vehicle .. 160O
Occupant safety Automatic front-passenger front
airbag deactivation .......................... 51
Automatic measures after an acci-
dent ................................................. 60
Children in the vehicle ..................... 60
Important safety notes .................... 43
PASSENGER AIRBAG indicator
lamp ................................................. 43
Pets in the vehicle ........................... 69
PRE-SAFE ®
(anticipatory occu-
pant protection) ............................... 58
PRE-SAFE ®
PLUS (anticipatory
occupant protection PLUS) .............. 59
Restraint system introduction .......... 42
Restraint system warning lamp ........ 43
Odometer
see Total distance recorder
see Trip meter
Oil
see Engine oil
On-board computer
AMG menu ..................................... 265
Assistance graphic menu ............... 257
Assistance menu ........................... 258
Display messages .......................... 266
Displaying a service message ........ 344
DISTRONIC PLUS ........................... 201
Factory settings ............................. 264
Head-up display ............................. 247
Important safety notes .................. 244
Instrument cluster menu ............... 263
Light menu ..................................... 262
Media menu ................................... 254 Menu overview .............................. 249
Message memory .......................... 266
Navigation menu ............................ 251
Operating the TV ............................ 255
Operating video DVD ..................... 255
Operation ....................................... 245
Radio menu ................................... 253
Service menu ................................. 258
Settings menu ............................... 258
Standard display ............................ 249
Telephone menu ............................ 256
Trip menu ...................................... 249
Vehicle menu ................................. 264
Operating instructions
Vehicle equipment ........................... 24
Operating safety
Declaration of conformity ................ 25
Important safety note ...................... 24
Operating system
see On-board computer
Outside temperature display ........... 245
Overhead control panel ...................... 38
Owner's Manual
Overview .......................................... 24 P
Paint code .......................................... 404
Paintwork (cleaning instructions) ... 347
Panic alarm .......................................... 42
Panorama roof ................................... 103
Parking
Important safety notes .................. 181
Parking brake ................................ 183
Position of exterior mirror, front-
passenger side ............................... 121
Reversing camera .......................... 220
Switching off the engine ................ 182
see PARKTRONIC
Parking aid
see 360° camera
see Active Parking Assist
see Exterior mirrors
see PARKTRONIC
see Reversing camera
Parking assistance
see PARKTRONIC Index
15

Rear-view mirror
Anti-dazzle mode (automatic) ........ 121
Dipping (manual) ........................... 119
Refuelling
Fuel gaug e....................................... 32
Important safety notes .................. 178
Notes for Mercedes‑ AMG vehi-
cles ................................................ 406
Refuelling process ......................... 179
see Fuel
Remote control
Auxiliary heating/ventilation .......... 151
Changing the batteries (auxiliary
heating) ......................................... 153
Garage door opener ....................... 330
Programming (garage door
opener) .......................................... 330
Replacing bulbs
General notes ................................ 133
Replacing the battery (auxiliary
heating remote control) .................... 153
Rescue card ......................................... 27
Reserve (fuel tank)
see Fuel
Reserve fuel
Display message ............................ 286
Warning lamp ................................. 310
Residual heat (climate control) ........ 147
Restraint system
Display message ............................ 276
Introduction ..................................... 42
Warning lamp ................................. 309
Warning lamp (function) ................... 43
Rev counter ........................................ 244
Reversing camera
Cleaning instructions ..................... 350
Displays in the COMAND display ... 221
Function/note s............................. 220
Reversing feature
Side windows ................................... 99
Reversing function
Boot lid ............................................ 94
Roller sunblind ............................... 103
Reversing lamp (display message) .. 282
ROAD SURFACE SCAN ....................... 209
Roller sunblind
Panorama roof ............................... 103 Rear window .................................. 324
Roller sunblind of the panorama
roof
Opening and closing ...................... 104
Operating ....................................... 103
Resetting ....................................... 104
Roof lining and carpets (cleaning
instructions) ...................................... 353
Roof load (maximum) ........................ 410 S
Safety Children in the vehicle ..................... 60
see Occupant safety
see Operating safety
Safety system
see Driving safety systems
SD memory card
Selecting ........................................ 254
Seat
Adjusting the front-passenger
seat from the driver's seat ............. 110
Seat backrest display message ..... 299
Seat belt
Correct usage .................................. 45
Seat belts
Adjusting the driver's and front-
passenger seat belt ......................... 47
Cleaning ......................................... 353
Display message ............................ 275
Fastening ......................................... 46
Important safety guidelines ............. 44
Introduction ..................................... 44
Rear seat belt status indicator ......... 48
Releasing ......................................... 47
Warning lamp ................................. 302
Warning lamp (function) ................... 48
Seating
Seating comfort packag e............... 113
Seating comfort package ................. 113
Seats
Active multicontour seat ................ 113
Adjusting (electrically) ................... 110
Adjusting the 4-way lumbar sup-
port ................................................ 113
Adjusting the head restraint .......... 111 Index
17

Useful information
i This Owner's Manual describes all mod-
els, series and optional equipment for your
vehicle that were available at the time of
going to press. National variations are pos- sible. Note that your vehicle may not be
equipped with all of the functions descri-
bed. This is also the case for systems and
functions relevant to safety.
i Read the information on qualified special-
ist workshops: (Y page 26). Panic alarm
X
To prime: press the!button :for
approximately one second.
A visual and audible alarm is triggered if the alarm system is primed.
X To deactivate: press the!button :
again.
or
X Press the Start/Stop button.
The key must be in the vehicle.
The panic alarm function is only available in
certain countries. Occupant safety
Introduction to the restraint system
The restraint system can reduce the risk of
vehicle occupants coming into contact with
parts of the vehicle's interior in the event of an accident. The restraint system can also
reduce the forces to which vehicle occupants
are subjected during an accident.
The restraint system includes the:
R Seat belt system
R Airbags
R Child restraint system
R Child seat securing system
The components of the restraint system work
in conjunction with each other. They can only
offer protection if all vehicle occupants
always:
R have the seat belt correctly fastened
(Y page 45)
R have the seat and head restraint adjusted
properly (Y page 109)
As the driver, you must also make sure that
the steering wheel is also adjusted properly.
Observe the information on the correct driv-
er's seat position (Y page 108).
In addition, you must make sure that the air-
bags can inflate properly if they are deployed (Y page 48).
An airbag supplements a correctly worn seat
belt. As an additional safety device, the airbag
increases the level of protection for vehicle
occupants in the event of an accident. The
airbags are not deployed, for example, in the event of an accident in which sufficient pro-
tection is offered by the seat belt. In addition,
only those airbags, which in the applicable
accident situations offer additional protec-
tion, are deployed in the event of an accident.
However, the seat belt and airbag generally
do not protect against objects penetrating
the vehicle from the outside.
Information on how the restraint system
operates can be found under "Deployment of
belt tensioners and airbags" (Y page 57).
See "Children in the vehicle" for further infor-
mation on children travelling in the vehicle as well as on child restraint systems
(Y page 60). 42
Occupant safetySafety

Important safety notes
G
WARNING
If the restraint system is modified, it may no
longer work as intended. The restraint system
may then not perform its intended protective function by failing in an accident or triggering
unexpectedly, for example. There is an
increased risk of injury, possibly even fatal.
Never modify parts of the restraint system. Do not attempt to modify the wiring as well as
electronic components or their software.
If it is necessary to modify an airbag system to
accommodate a person with disabilities, con- tact a Mercedes-Benz Service Centre for
details. Restraint system warning lamp
The functions of the restraint system are
checked after the ignition is switched on and
at regular intervals while the engine is run-
ning. Therefore, malfunctions can be detec-
ted in good time.
The 6 restraint system warning lamp in
the instrument cluster lights up when the igni- tion is switched on. It goes out no later than afew seconds after the vehicle is started. The
components of the restraint system are in
operational readiness.
A malfunction has occurred if the 6
restraint system warning lamp:
R does not light up after the ignition is
switched on
R does not go out after a few seconds with
the engine running
R lights up again while the engine is running G
WARNING
If the restraint system is malfunctioning,
restraint system components may be trig-
gered unintentionally or might not be trig-
gered at all in the event of an accident with a high rate of vehicle deceleration. This can
effect belt tensioners or airbags, for example. There is an increased risk of serious or even
fatal injuries.
Have the restraint system checked and
repaired immediately at a qualified specialist
workshop.
PASSENGER AIRBAG indicator lamp
PASSENGER AIR BAG OFF indicator lamp
:
and PASSENGER AIR BAG ON indicator
lamp ;are part of the automatic deactiva-
tion system of the front-passenger front air-
bag.
The indicator lamps display the status of the
front-passenger front airbag.
R PASSENGER AIR BAG ON lights up: the
front-passenger front airbag is enabled. If,
in the event of an accident, all deployment
criteria are met, the front-passenger front
airbag is deployed.
R PASSENGER AIR BAG OFF lights up: the
front-passenger front airbag is disabled. It
will then not be deployed in the event of an
accident.
Depending on the person in the front-
passenger seat, the front-passenger front air-
bag must either be disabled or enabled; see
the following points. You must make sure of
this both before and during a journey.
R Children in a rearward-facing child
restraint system: the PASSENGER AIR
BAG OFF indicator lamp must be lit. The
front-passenger front airbag is disabled. It
is imperative to observe the notes on the Occupant safety
43Safety Z

"Automatic front-passenger front airbag
deactivation system" (Y page 51) and on
"Children in the vehicle" (Y page 60).
R Children in a forward-facing child
restraint system: depending on the instal-
led child restraint system and the age and
size of the child, the front-passenger front
airbag is either disabled or enabled. There-
fore, it is imperative to observe the notes
on the "Automatic front-passenger front
airbag deactivation system" (Y page 51)
and on "Children in the vehicle"
(Y page 60).
R All other persons: the PASSENGER AIR
BAG ON indicator lamp must be lit. The
front-passenger front airbag is enabled.
Depending on the build of the person on the
front-passenger seat, the PASSENGER AIR
BAG OFF indicator lamp may light up. The
front-passenger front airbag is disabled. It
will then not be deployed in the event of an accident. In this case, the front-passenger
seat should not be used.
It is imperative to observe the notes on the
"Automatic front-passenger front airbag
deactivation system" (Y page 51) as well
as on "Seat belts" (Y page 44) and "Air-
bags" (Y page 48). There you can also find
information on the correct seat position. Seat belts
Introduction A correctly worn seat belt is the most effec-
tive means of restraining the movement of
vehicle occupants in the event of a collision or
if the vehicle overturns. This reduces the risk of vehicle occupants coming into contact with
parts of the vehicle interior or being ejected
from it. The seat belt also helps to keep the
vehicle occupants in the best position in rela-
tion to the airbag being deployed.
The seat belt system consists of:
R seat belts
R belt tensioners and belt force limiters If the seat belt is pulled quickly or sharply by
the seat-belt extender, the inertia reel locks.
The belt strap cannot be pulled out any fur-
ther.
The belt tensioner tightens the seat belt in the
event of a collision so that it fits tightly across
your body. However, it does not pull the vehi- cle occupants back in the direction of the seat
backrest.
The belt tensioner does not, however, correct an incorrect seat position or correct the rout-
ing of a seat belt that is worn incorrectly.
When triggered, seat belt force limiters help
to reduce the peak force exerted by the seat
belt on the vehicle occupant.
The belt force limiters on the front seats are
synchronised with the front airbags, which
take on a part of the deceleration force. This
can reduce the forces to which the vehicle
occupants are subjected during an accident.
! If the co-driver's seat is not occupied, do
not engage the seat belt tongue in the
buckle on the co-driver's seat. Otherwise,
the belt tensioner could be triggered in the
event of an accident and would have to be
replaced.
Important safety notes G
WARNING
The seat belt cannot perform its intended pro- tective function if it is not fastened correctly. Also, an improperly fastened seat belt can
cause additional injuries in the event of an
accident, sudden braking or abrupt changes
of direction. There is an increased risk of
injury, possibly even fatal.
Always make sure that all vehicle occupants
are wearing their seat belt properly and are
seated correctly. G
WARNING
The seat belt does not offer the intended level of protection if you have not moved the back-
rest to an almost vertical position. When brak-
ing or in the event of an accident, you could 44
Occupant safetySafety

slide underneath the seat belt and sustain
abdomen or neck injuries, for example. This
poses an increased risk of injury or even fatal injury.
Adjust the seat properly before beginning
your journey. Always ensure that the backrestis in an almost vertical position and that the
shoulder section of your seatbelt is routed
across the centre of your shoulder. G
WARNING
Persons under 1.50 mtall cannot wear the
seat belts correctly without a suitable, addi-
tional restraint system. The seat belt cannot
perform its intended protective function if it is not fastened correctly. Also, an improperly
fastened seat belt can cause additional inju-
ries in the event of an accident, sudden brak-
ing or abrupt changes of direction. There is an increased risk of injury, possibly even fatal.
Secure persons less than 1.50 mtall in a suit-
able restraint system.
If a child younger than twelve years old and
under 1.50 m in height is travelling in the
vehicle:
R always secure the child in a child restraint
system suitable for this Mercedes-Benz
vehicle. The child restraint system must be appropriate to the age, weight and size of
the child.
R always observe the instructions and safety
notes on the automatic front-passenger
front airbag deactivation system
(Y page 51)
R always observe the instructions and safety
notes on "Children in the vehicle" in this
Owner's Manual (Y page 60) in addition
to the child restraint system manufactur-
er's installation instructions G
WARNING
Seat belts cannot protect as intended, if:
R they are damaged, have been modified, are
extremely dirty, bleached or dyed
R the seat belt buckle is damaged or
extremely dirty
R modifications have been made to the belt
tensioners, belt anchorages or inertia reels
Seat belts may sustain non-visible damage in an accident, e.g. due to glass splinters. Modi-
fied or damaged seat belts can tear or fail, for example in the event of an accident. Modified
seat belt tensioners may be deployed unin-
tentionally or fail to be deployed when
required. There is an increased risk of injury,
possibly even fatal.
Never modify safety belts, seat belt tension-
ers, seat belt anchorages and inertia reels.
Ensure that seat belts are not damaged or
worn and are clean. After an accident, have
the seat belts checked immediately at a quali- fied specialist workshop.
Mercedes-Benz recommends that you only
use seat belts which have been approved
specifically for your vehicle by Mercedes-
Benz. Otherwise, your vehicle's general oper- ating permit could be invalidated.
Correct seat belt use Observe the safety notes on the seat belt
(Y
page 44).
All vehicle occupants must fasten their seat
belts correctly before starting the journey.
Also make sure during the journey, that all
vehicle occupants have their seat belt cor-
rectly fastened.
When fastening your seat belt, always make
sure that:
R the seat belt buckle tongue is only inserted
into the correct belt buckle for the corre-
sponding seat.
R the seat belt fits closely across your body.
Avoid wearing bulky clothing, e.g. a winter
coat. Occupant safety
45Safety Z

In order to avoid such risks, always ensure
that all vehicle occupants:
R fasten their seatbelts correctly, including
pregnant women
R are seated correctly and maintain the fur-
thest possible distance from the airbags
R observe the following notes
Always ensure that there are no objects loca-
ted between the airbag and the vehicle occu-
pant.
R Adjust the seats properly before beginning
your journey. Always make sure that the
seat is in an almost upright position. The
centre of the head restraint must support
the head at about eye level.
R Move the driver's and front-passenger
seats as far back as possible. The driver's
seat position must allow the vehicle to be
driven safely.
R Only hold the steering wheel on the out-
side. This allows the airbag to be fully
deployed.
R Always lean against the backrest while driv-
ing. Do not lean forwards or lean against
the door or side window. You may other-
wise be in the deployment area of the air-
bags.
R Always keep your feet in the footwell in
front of the seat. Do not put your feet on the dashboard, for example. Your feet may oth-
erwise be in the deployment area of the
airbag.
R Always secure persons less than 1.50 mtall
in suitable restraint systems. Up to this
height, the seat belt cannot be worn cor-
rectly.
If a child is travelling in your vehicle, also
observe the following notes:
R Always secure children under twelve years
of age and less than 1.50 mtall in suitable
child restraint systems.
R Child restraint systems should be fitted to
the rear seats. R
Only secure a child to the front-passenger
seat when the front-passenger front airbag
is disabled, and only then in a rearward-
facing child restraint system. If the
PASSENGER AIR BAG OFF indicator lamp is
permanently lit, the front-passenger front
airbag is disabled (Y page 43).
R Always observe the instructions and safety
notes on the automatic front-passenger
front airbag deactivation system
(Y page 51) and on "Children in the vehi-
cle" (Y page 60) in addition to the child
restraint system manufacturer's installa-
tion instructions.
Objects in the vehicle interior may pre-
vent the airbag from functioning cor-
rectly. Before starting your journey and to
avoid risks resulting from the speed of the
airbag as it deploys, make sure that:
R there are no people, animals or objects
between the vehicle occupants and an air-
bag.
Do not place any objects on the dashboard,
e.g. above the front-passenger front airbag.
R there are no objects between the seat, door
and B-pillar.
R no hard objects, e.g. coat hangers, are
hanging on the grab handles or coat hooks.
R no accessories, such as cup holders, are
attached to the vehicle within the deploy-
ment area of an airbag, e.g. to doors, side
windows, rear side trim or side walls.
R no heavy, sharp-edged or fragile objects
are in the pockets of your clothing. Store
such objects in a suitable place. G
WARNING
If you modify an airbag cover or affix objects
such as stickers to it, the airbag can no longer function correctly. There is an increased risk
of injury.
Never modify an airbag cover or affix objects
to it. Occupant safety
49Safety Z

Front sidebags
:and rear sidebags ;
deploy next to the outer bolster of the seat
backrest.
When deployed, the sidebag offers additional thorax protection. It also offers additional pel-
vis protection for occupants in the front
seats. However, it does not protect the:
R head
R neck
R arms
In the event of a side impact, the sidebag is
deployed on the side on which the impact
occurs.
Vehicles with the automatic front-passenger
airbag deactivation system: the sidebag on
the front-passenger side deploys under the
following conditions:
R an occupant is detected on the front-
passenger seat or
R the belt tongue is engaged in the belt
buckle of the front-passenger seat
If the belt tongue is engaged in the belt
buckle, the sidebag on the front-passenger
side deploys if an appropriate accident situa- tion occurs. In this case, deployment is inde- pendent of whether the front-passenger seatis occupied or not. Windowbags Windowbags
:are integrated into the side
of the roof frame and deploy in the area from the A-pillar to the C-pillar.
When deployed, the windowbag enhances the
level of protection for the head. However, it
does not protect the chest or arms.
In the event of a side impact, the windowbag
is deployed on the side on which the impact
occurs.
If the system determines that they can offer
additional protection to that provided by the
seat belt, a windowbag may be deployed in
other accident situations (Y page 57). Automatic front-passenger front air-
bag deactivation
Introduction In order to recognise a child restraint system
on the front-passenger seat, the automatic
front-passenger front airbag deactivation sys-tem categorises the person in the front-
passenger seat. Depending on that result, the
front-passenger front airbag is either enabled or disabled. If a rearward-facing child
restraint system is fitted to the front-
passenger seat, the PASSENGER AIR BAG
OFF indicator lamp must light up after the
system self-test and remain lit. The front-
passenger front airbag is disabled. Occupant safety
51Safety Z