engine AUDI A7 2014 Workshop Manual

198 Intelligent technology
@ Tips
-ABS and ASR on ly work correctly when
all four wheels are equipped w ith identi­
ca l tires. Different tire sizes can lead to a
reduct ion in engine power.
- You may hear noises when the systems described are working.
Switching on and off
- If the indicator light DJ or til] (USA
mode ls)/ [I] (Canada models) appears,
there may be a malfunction
¢ page 20 ,
¢page 19.
ESC turns on automatically when you start the engine.
Fig. 18 2 Cent er co nsole, f). O FF bu tton
ESC levels
Sport mode on
The following situations are exceptions where
it may be usefu l to switch on sport mode to
allow the wheels to sp in:
- Rocking the vehicle to free i t when i t is st uck
- Dr iving in deep snow or on loose g round
- Driving with snow chains
Sport mode off
Beha vio r
The ESC a nd ASR stabilization fun ct ions The fu ll stabilization function o f the ESC
are limited¢ .&,.
Op eration Pr ess the 1.$ O FFI button .
Indicato r I) turns o n.
lights
Driv er mes- Stabiliza tion control (ESC ): Sport.
sage s Warning! R educed stability
,8. WARNING
You should only switch sport mode on if
your driving abilities and road cond itions
permit.
- The stabilization function is limited
when sport mode is sw itched on. The
dr iv ing whee ls could spin and the vehicle
cou ld swe rve, especially on slick or slip­
pery road surfaces .
{D) Tips
-Sport mode cannot be switched on when
adaptive cruise control* is switched on.
-
and ASR is availab le again .
Press the
1 .$ O FF I button again.
fl tu rns off.
Stabilization c ontrol (ESC ): On
- If the rear spo iler system malf unct ions,
s port mode may no t switch on o r it may
sw it c h off ag ain autom atically.

200 Intelligent technology
Braking
General information
What affects braking efficiency?
Operating conditions and driving habits
The brakes on today's automobi les are sti ll
subject to wear, depending largely on operat­
ing conditions and driving habits
c:> ,&. On
vehicles that are either driven mostly in stop­
and-go city traffic or are driven hard, the brake pads should be checked by your author­
ized Audi dealer more often than specified in
the
Warranty & Maintenan ce booklet . Failure
to have your b rake pads inspected can result
in red uced brake performance.
On steep slopes, you shou ld use the brak ing
effect of the engine. This way, you prevent un­
necessary wear on the brake system. If you
must use yo ur brakes, do not hold the brakes
down continuously. Pump the brakes at inter­
va ls.
Moisture or road salt
Unde r certain conditions, for example, when
driving through water or very heavy rain, or
even after washing your vehicle, the braking
effect can be red uced due to moisture (or in
freezing conditions ice) on the brake pads. A
few careful brake applications should dry off the brake pads or remove any ice coatings.
When you are driving at higher speeds with
the windshield wipers on, the brake pads will
briefly touch the brake discs in regular inter­
vals so as to improve reaction t ime when brak­
ing on wet surfaces. You the driver will not no­
tice anything .
The effectiveness of the brakes can be reduced
when the vehicle is dr iven on a salt-covered
road and the brakes are not used . Here too,
you should clean off accumulated salt coat ing
from brake discs and pads with a few careful
applications of the brake
c:> ,& .
Corrosion
There may be a tendency for dirt to build up
on the brake pads and corrosion to form on the
discs if the car is not driven regu larly or
o n Ly for short trips with litt le use of the
brakes.
If the brakes are not used frequently, or if cor­
r osion has formed on the discs, it is advisable
to clean off the pads and discs by braking
firmly a few times from a moderately h igh
speed
c:> .&. .
Faults in the brake system
If you shou ld notice a sudden increase in
brake pedal travel, then one of the two brake
circuits may have fai led
c::> .&. .
Low brake fluid level
Malfunctions can occu r in the brake system if
the brake fluid level is too low. The brake fluid
l evel is monitored electronically.
Brake booster
The brake booster works with vacuum pres­
su re which is created only when the eng ine is
running
c::> ,& .
Brake lining wear status
Brake lining wear may be checked by visual in­
spect ion of the condition of the brake pads
t hr ough the open ings in the wheel. If neces­
sary, the wheel may be removed for this in­
spect ion
c:> page 266, Changing a wheel.
.8_ WARNING
-You shou ld perform braking maneuvers
for the purpose of cleaning the brake
system only if road conditions permit.
Other road users must not be put at risk -
you may cause an accident!
- Before descending a steep grade, reduce
speed and sh ift transmission into a lower
gear or lower driving range. Do not ride
the brakes or hold the pedal down too
long or too often . This could cause the
brakes to get hot and diminish braking
efficiency.
- Do not "ride the brakes" by resting your
foot on the pedal when you do not intend
to brake. This may cause the brakes to

overheat, premature wear and increased
stopp ing distance.
- Under certain climatic and operating
conditions such as passing through wa­
ter, driving in heavy rain or after wash ing
the vehicle, the effect iveness of the
brakes can be reduced. In winter, ice can
accumulate on the brake pads, linings,
discs and drums. Carefully apply brakes
for a test. Brakes will dry and ice coat­ ings will be cleaned off after a few ca re­
f ul brake applications.
- Driv ing for an extended period of time on
salt-covered roads w ithout using your
brakes can also affect braking efficiency.
Clean off accumulated salt coating from
brake discs and pads w ith a few caref ul
brake applicat ions.
- If you damage the front spoiler, or if you
install a different spoiler, be sure the air
flow to the front brakes is not obstruct­ ed. Otherwise the brake system could
overheat reducing the effectiveness of
the ent ire brake system.
- Failure of one brake c ircuit will impair
the braking capability resulting in an in­
c reased stopp ing distance. Avoid driv ing
the vehicle and have it towed to the near­
est Aud i dea ler o r q ualified workshop.
- Never let the vehicle roll to a stop w ith
the engine shu t off.
- If the brake booster is not work ing, the
brake pedal must be pressed conside ra­
bly harder to make up for the lac k of
booster assistance.
Electro-mechanical
power assist
The electro-mechanical power assist helps
the driver when steering.
Powe r steering adapts electronically based on
the vehicle speed.
Indicator lights and message s
• Steerin g defective! Stop th e vehicle
Int ellig ent technolog y 201
If this indicato r light turns on and stays on
and t his message appears, the power steering
may have failed.
Do
not con tinue dr iv ing . See your au thor ized
Audi dealer or other qualified repair facility
for assistance .
'I-Y Steering: System malfun ction! You may
c ontinue dri ving
If the indicato r light turns on and the mes­
sage appea rs, the stee ring may be more diffi­
c ult to move o r more sens itive than usual.
Drive slowly to your authorized Aud i dealer or
qualified workshop to have the ma lfunction
corre cted.
0) Tips
If the . or 1:z;lj indicator light on ly stays
on for a short t ime, yo u may continue dr iv­
i ng.
Driving with your
quattro
App lies to veh icl es: w ith all-w hee l drive
With all-wheel drive, all four wheels are driv­
en.
General information
Wi th a ll W heel Drive, power is distributed to
all four wheels . This happens automatically
depending on your driving style and the road
conditions at the time . See also
~ page 196.
With the sport different ia l* , power distribu­
tion to the rear wheels is variable and can be
adjusted with Audi dr ive select*
~ page 102.
Always read and follow safety precautions
~ .&. .
Winter tires
When dr iving in the winter, yo ur vehicle with
all-wheel drive has an advantage, even wit h
regular tires . In winter road conditions it may
be advisable to mount winter tires (or all-sea­
son tires) for improved driveability and brak­
ing: these tires must be moun ted o n
all four
wh eel s.
See also~ page 258, Winter tires. ..,.
•
•

202 Intellig ent technol ogy
Tire chain s
Where t ire cha ins are mandatory on certain
roads, this normally a lso applies to vehicles
with a ll- wheel drive
c::> page 259, Snow
chains .
Replacing wheels /t ir es
Vehicles with all-whee l drive must a lways
have tires of the same size. Also avoid t ires
with different tread depths. For details see
page
c::> page 2 54, New tires and replacing
tires and wheels.
Off -Ro ad dri ving?
Your Aud i does not have enough ground clear­
ance to be used as an off -road veh icle.
It is
therefore best to avoid rough tracks and un ­
even terrain as much as possible . Also refer to
c::> page206.
A WARNING
Always adjust your driving to road and traf­
fic condit ions. Do not let the extra safety
afforded by all-wheel dr ive tempt you into
taking extra r isks.
- Although the all-wheel dr ive is very ef­
fective, always remember that braking capacity is limited by t ire traction . You
should the refore not dr ive at excessive
speeds on icy or slippery road su rfaces.
- On wet road surfaces, be careful not to
dr ive too fast because the front wheels
cou ld beg in to s lide on top of the w ater
(aquaplaning) .
If this should occ ur, you
wi ll have no warning from a sudden in ­
crease in engine speed as with a front­
wheel drive vehicle. A lways drive at
speeds wh ich are suited to the road con­
ditions -risk of crash.
Energy management
Starting ability is optimized
Energy management controls the distribution
of electrical energy and thus optimizes the
availability of electrical energy for starting the engine.
If a vehicle with a conventional energy system
is not driven for a long per iod of t ime, the bat­
tery is discharged by idling current consumers (e .g. immobilize r). In certa in circumstances it
can resu lt in the re be ing insufficient energy
available to start the engine.
Intelligent energy management in your vehi­
cl e ha ndles the distribution of e lectr ica l ene r­
gy . Start ing ability is ma rkedly improved and
the life of the battery is extended .
Bas ica lly, energy management consists of
b att ery diagn osis, idlin g current manage ­
m ent
and dynamic en erg y manag em ent .
Battery di agnosis
Battery diagnosis continuously determines
the state of the battery. Sensors determine
battery voltage, battery cu rrent and battery
tempe rature. This determines the current
state o f charge and the power of t he battery .
Idling current management
Idling current management reduces energy
consumption while the vehicle is standing .
With the ig nition sw itched
off, it controls the
energy supply to the various electri ca l compo ­
nents. Da ta from ba ttery diagnos is is cons id ­
ered.
Depend ing on the batte ry's state of cha rge,
individual cons ume rs a re g radually turned
off
to prevent excessive discharge of the battery
and th us maintain starting capability.
Dynamic energy manag ement
While the vehicle is being d riven, dynamic en­
ergy ma nagement distr ibutes the energy gen­
era ted a ccord ing to t he needs of the individ u-
al components .
It regula tes consumption, so
t h at more electrical energy is not being used ..,.

than is being generated and ensures an opti­mal state of charge for the battery.
@ Tips
- But even energy management cannot
negate the limits o f physics. Consider
that the power and life of a battery are
limited.
- If starting ab ility is threatened, the indi­
cator light (•) appears ¢
page 17.
What you should know
The highest priority is given to maintaining
starting capability.
The battery is severely taxed in short-dis tance
driving, in city traffic and d uring the co ld time
of year . Abu ndant e lectrica l energy is re­
q uired, but only a litt le is generated . It is also
cr itical if the engine is not runn ing and electri­
cal components are turned on. In th is in­
stance energy is being consumed but none is
be ing generated.
It is in precisely these situations that you w ill
notice energy management actively regulat­
i n g the distribution of energy.
Vehicle stand s for an e xte nded period
If yo u do not drive you r vehicle over a period
of severa l days or weeks, electrical compo­
nents are grad ually cut back or switched off.
This reduces energy consumption and main­ tains starting capab ility over a longer per iod.
Some of the conven ience functions may not
operate, such as the inter ior lights o r the
power seat adjustment. The conven ience
f u nctions will be ava ilable again whe n you
switch on the igni tion and start the engine.
With the engine turned off
If you lis ten to t he radio, for example, with
the eng ine turned off or use othe r MM I fu nc­
tions, the bat te ry is being discha rged .
If starting capability is jeopardized due to en ­
e rgy consumpt ion, the follow ing warning ap­
pears in the MMI disp lay :
Int ellig ent technolog y 203
Plea se start the engine soon or the sy stem
will be turned off .
The wa rni ng ind ic ates th at the sys tem w ill be
t u rned o ff autom atically a fter 3 minu tes. If
you w ish to continue using the funct ions, yo u
have to start the engine.
With the engine running
Althoug h elec trical energy is generated when
t h e ve hicl e is being driven, t he battery can be­
come d isc harged. This happe ns mostly when
little energy is being generated and a g reat
deal consumed and the battery's state of
charge is not opt imal.
T o b ring the energy ba lance back in to equili ­
brium, consumers which req uir e especially
l a rge amounts of energy a re temporari ly cut
back or sw itched off. Heat ing systems in par­
ticular require a great deal of energy. If you notice, for example, that the heated seats* or
the heated rear window are not heating, they
have been temporarily cut back or switched
off . These systems w ill be availabl e again as
soon as the ene rgy balance has been restored.
You w ill also notice that engine id le speed has
been increased slightly . Thi s is no rmal and not
a cause for concern. By inc reas ing engi ne id le
speed the additional e nergy requi red is gene r­
ated and the b attery is charged.
•
•

204 Driving and environment
Driving and
environment
The first 1,000 miles
(1,500 km) and
afterwards
New engine
The engine needs to be run-in during the first
1,000 miles (1,500 km).
For the fir st 600 miles (1,000
kilometers ):
.,. Do not use full throttle.
... Do not d rive at engine speeds that are more
than 2/3 of the max imum permitted RPM.
... Avoid high engine speeds.
From 600 to 1,000 mile s (1 ,000 to
1,500 kilometers):
... Speeds can gradually be increased to the
max imum pe rm iss ible road or eng ine speed .
During and after break-in period
.,. Do not rev the eng ine up to high speeds
when it is cold. Th is app lies whether the
transm ission is in N (Neutra l) or in gear.
After the break-in period
... Do not exceed maximum engine speed un­
der any circumstances.
.,. Upshift into the next hig her gear
before
reaching the red area at the end of the tach­
ometer scale
c:> page 11.
During the first few hours of driving, the en­
g ine's interna l friction is higher than later
when all the moving parts have been broken
in . How well this break- in process is do ne de­
pends to a conside rable extent on th e way the
ve hicl e is driven during the first 1,0 00 miles
(1, 500 k ilome ters).
0 Note
E xtremely high engi ne speeds are auto­
mat ica lly reduced. However, these rpm
lim its are progr amme d for an engine well
r u n- in, not a new engine .
{® For the sake of the environment
Do not drive with unnecessarily high en­
g ine speeds - upshifting ear ly saves fuel,
reduces no ise and protects the environ­
ment.
, New tires
If your vehicle is runni ng on new tires, drive
part icularly caref ul for the first 350 miles
(500 kilomete rs) afte r fitt ing.
A WARNING
N ew tires tend to be sl ippery and mus t al­
so be "b roken -in" . Be s ure to remember
this dur ing the fi rst 350 mi les ( 500 kilo ­
meters) . Brake gently . Avoid fo llow ing
closely behind other vehicles or other sit­
uations that m ight require sudden, hard
braking .
New brake pads
Remember that new brake pads do not have a
full bra king effect dur ing the fi rst 250 m iles
(400 kilomete rs) afte r they a re insta lled.
New brake pads have to be "burnished in" be­
fo re t hey have optima l grab
c:> A .
During the break- in period, you should avoid
putting severe loads on the brakes. Severe
l oads include, for example, sudden hard brak­
i ng, in particular at very high speeds or, for
example, on mounta in passes .
A WARNING
New b rake pa ds don't have t he bes t stop­
pi ng power and mus t be "broke n-in " dur­
i ng the in iti al 1 00 to 150 mi les (150 to
20 0 k ilometers) of no rma l city driving . You
can compensate for this by pressing the
br ake peda l mo re f irm ly . This also applies
l ater when new pads are installed.

Catalytic converter
Applies to vehicles: with gasoline engine
It is very important that your emission con­
trol system (catalytic converter) is function­
ing properly to ensure that your vehicle is run­
ning in an environmentally sound manner .
... Always use lead-free gasoline c::> page 218,
Fuel supply .
... Never run the tank down all the way to emp­
ty .
... Never put too much motor oil in your engine
c::> page 232, Adding engine oil <t::r..
.,. Never try to push-or tow-start your veh icle.
The catalytic converter is an eff icient "clean­
up" device built into the exhaust system of
the vehicle. The catalytic converter burns
many of the pollutants in the exhaust gas be­
fore they are released into the atmosphere.
The exclusive use of unleaded fuel is cr it ically
i mportant for the life of the cata lytic convert­
e r and proper functioning of the engine.
& WARNING ,~
T he temperature of the exhaust system is
high, both when driving and after stopping
the engine .
- Never touch the exha ust tail pipes once
they have become hot. This could result
in burns.
- Do not park or operate the vehicle in
areas where the hot exhaust system may
come in contact with dry grass, brush,
fuel spill or other material which can
cause a fire.
- Do not apply additional undercoating or
rustproofing on or near the exhaust
manifold, exhaust p ipes, catalytic con­
verter or heat shields . During driving, the
substance used for undercoating cou ld
overheat and cause a fire.
(D Note
- Be aware that just one tank f illing with
leaded fuel will already seriously de-
grade the performance of the catalytic
conve rter.
Dri vin g and en vironm ent 205
-Do not exceed the correct engine oil level
c::>page 232.
-Do not drive until the fue l tank becomes
completely empty. The engine cou ld mis­
fire . Unburned fuel could also get into
the exhaust system and this cou ld cause
the catalytic converter to overheat.
- Do not switch off the ignition while the
vehicle is mov ing .
- Do not continue to operate your veh icle
under these conditions, as otherwise fuel
can reach the catalyt ic converter. Th is
cou ld result i n overheating of the con­
verter, requir ing its replacement.
- To assure efficient operation of the Emis­
sion Control System:
- Have you r vehicle main tained properly
and in accordance w ith the se rv ice rec­
ommendations in your Warranty & Maintenance book let.
- Lack of proper maintenance as we ll as
improper use of t he vehicle wi ll impair
the function of the emission cont ro l
system and could lead to damage.
@) For the sake of the env ironment
Even when the Emission Control System is
ope rat ing properly, the exhaust gas can
have a sulfur-like exhaust gas smell under
some operat ing states. This depends on
the sulfur content of the fuel being used .
Using a different brand of fuel may help,
or filling the tank with lead-free s uper
g rade gasoline.
Diesel particulate filter
App lies to vehicles: wit h diese l eng ine
The diesel part iculate filter filters nearly all of
the soot pa rticles out of the exhaust . T he fil­
te r clea ns itself automat ica lly unde r no rma l
driv ing cond itions. If the filter cannot clean it ­
self (for example, because you are on ly driving
sho rt distances), the filter becomes clogged
with soot and the
Ill symbo l for the diesel
particulate filter i lluminates
c::> page 22. ..,_
•
•

206 Driving and en vir onm ent
8_ WARNING
- Do not park your vehicle over flammable
materials such as grass or leaves because
the high temperature of the diesel par­
t icu late filter could start a fire .
- Do not apply an underbody protectant in
the exhaust system area or a fire could start.
Avoid damaging the vehicle
When you are driving on poor roads, or over
curbs, steep ramps, etc., make certain that
low-lying parts such as spoilers and exhaust
system parts do not bottom out and get dam­
aged.
This is especia lly true for vehicles with low­
slung chassis (sports chassis)* and fully load­
ed vehicles.
Driving through water
on roads
Note the following to avoid vehicle damage
when dr iving through water, for example on
flooded roads:
- The water must not be any higher than the bottom of the vehicle body.
- Do not drive faster than wa lking speed.
8_ WARNING
After driving through water, mud, slush,
etc., the brakes may be slow to take effect
because of wet brake rotors and pads. Dry
the brakes f irst by brak ing carefully to re­
sto re the full braking effect.
(D Note
- Vehicle components such as the engine,
transmission, suspension or electrical
system can be severely damaged by driv­
ing through water.
- Always switch off the Start-Stop-System
when driving through water~
page 81.
-
(D Tips
-Check the depth of the water before d riv­
ing through it .
- Do not stop the vehicle, drive in reverse
or switch the engine off when driving
through water.
- Keep in mind that oncoming vehicles
may create waves that raise the water
level and make it too deep for your vehi­
cle to drive through safely.
- Avoid driving through salt water because
it can cause corrosion.
Shutting down vehicle
If you would like your vehicle to remain inop­
erative for a longer period of time, contact an
Audi or other specialized dealer. They can ad­
vise you on necessary precautions e .g. corro ­
sion prevention, maintenance and storage .
Pay attention to additional information con­
cern ing the battery. Refer to
~ page 238.
Operate your vehicle
economically and
minimize pollution
General
Your personal style of driving will determine
the economy of your vehicle, as well as ex­
haust and noise levels.
Fuel economy, env ironmental impact, and
wear on your eng ine , brakes and tires largely
depend on three factors:
- your personal driving style
- operating conditions
- technical limitations
If you anticipate what you need to do next and
drive economically, you can easily cut your
fuel consumption by 10-15 percent . This sec­
tion will give you some tips on how you can
help the environment and your pocketbook.

@ Tips
The consumption estimates as published by ENVIRONMENTAL PROTECTION AGENCY (EPA) and Transport Canada may not corre­
spond to your actual consumption on the
road, wh ic h will vary depend ing upon vehi­
cle load and speed, road and weather con­
ditions, tr ip length, etc.
Drive smoothly and keep a lookout
ahead
Vehicles use the most fuel when they are ac­
celerating.
~ Avoid unnecessary accelerating and braking.
Vehicles use the most fuel when they are ac­
celerating . If you anticipate what is go ing to
h appen next, you will need to b rake less and,
thus, accelerate less. Let the vehicle coast
wheneve r poss ible -fo r example when you see
that the nex t tr affic light is red.
Avoid full throttle
Driving at moderate speeds saves fuel and
improves your mileage.
~ T ry and keep well below your car's max imum
speed.
Accelerating gent ly reduces fuel consump­
tion, engine wear, and does not dist urb the
environment.
Fuel consumption, exhaust emissions and en­
g ine no ise increase d ispropo rtionately at high
speeds. If you dr ive at approxima tely three
q uarters of top speed, fue l consumption will
be red uced by one ha lf. Never dr ive faste r
than the posted speed limit and wea ther con­
d itions permit.
Reducing unnecessary idling
E ven when your car is just idling it burns up
fuel.
~ S hu t the engine off when you a re not dr iv ing
t h e vehi cle.
Dri vin g and en vironm ent 207
~ Do not warm up the vehicle by lett ing the
engine run at id le .
T he id ling phase is au toma tic ally red uced for
vehicles with the Start/S top system . It is eff i­
cient to switch off the engine in vehicles with­
out the Start-Stop-System when stopped at
railroad crossings and long red lights. Turning
the engine off for just 30-40 seconds saves more fuel than is burned by start ing the en-
. . gme again .
It takes a long t ime for the engine to warm up
fully when it is run ning at id le. However, wear
and noxious emissions are especia lly high
when the eng ine is warm ing up. So you should
dr ive away as soon as you start the engine and
avo id running at high rpms whi le the engine is
sti ll warming up.
(L} Note
Do not leave eng ine idling unattended af­
ter start ing.
If wa rni ng lights sho uld come
o n t o indi cate improper ope rat ion, t hey
wo uld go unheeded. Extended idlin g also
produces heat, wh ich could res ult in ove r­
heating or other damage to the veh icle or
other p roperty .
Regular maintenance
A badly tuned engine unnecessarily wastes a
lot of fuel.
~ Have your ve hicle servi ced at reg ular i nter-
vals .
By havi ng your ve hicle regu la rly se rviced by an
Audi dealer he lps to ensu re tha t it ru ns prop­
erly and economically . The condition of your
vehicle not on ly affects its safety and ability to
ho ld its va lue, it a lso affects
fuel consump­
tion .
Check your oil each t ime y ou fill your tank.
The amou nt of o il used is re lated to engine
l oad and speed.
It is normal for the oil consumption of a new
engine to reac h its lowest value after a certa in
mileage has been d riven. .,..
•
•

208 Driving and environment
You must drive your vehicle about 3,000 miles
(5,000 kilometers) before you can properly
assess o il consumption.
This also applies to fuel consumption and en­
gine output.
0 Note
- Have yo ur vehicle maintained properly
and in accordance with the service rec­
ommendations in your Warranty
& Main­
tenance booklet. Lack of proper mainte­
nance as well as improper use of the ve­
hicle will impair the funct ion of the
emission control system and could lead
to damage .
- Do not alter or remove any component of
the Emi ssion Control System unless ap­
proved by the manufacturer .
- Do not alter or remove any dev ice, such
as heat shields, switches, ignition wires,
valves, wh ich are designed to protect
your vehicle's Emission Control System
and othe r important veh icle compo­
nents.
Fewer short trips
Fuel consumption will always be relatively
high on short trips .
.. Try to avo id driving short d istances with a
co ld engine .
The engine and ca talyt ic converter have to
reach their optimal
operating temperature to
reduce fuel consumption and noxious emis­
sions effect ively.
Just after starting, a cold engine in a mid-size
car only achieves a fuel economy of 6-8 miles
per gallon (30-40 l/100 km) . After about a
half a mile, fuel economy climbs to 12 mpg
(20 l/100 km). After abo ut
2 .5 miles (4 km),
the engine is at its proper ope rat ing tempera­
ture and fue l economy has reached a normal
l eve l. So you can see that you should avoid
short trips whenever possible. T
he
outside temperature is also critical in this
regard. Your car consumes more fue l in the
winter than in the summer.