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Do not touchyour ESC button!

Do not touch your ESCbutton. ESC is switchedon by default when you startyour vehicle, so it does notrequire switching on. Somemanufacturers are producingcars without the ESC button(e.g. Ford), so that drivers are

protected by ESC at all times.The majority of cars are ttedwith an ESC button whichcan be used to switch ESCoff when unusual conditionsare encountered, such asmoving off in deep snow. TheESC button should not be

touched unless those unusualconditions are encountered.For further information,please consult your vehiclehandbook.

ESC is particularly effective in poor driving conditionssuch as ice and snow.

A study for the UK Department for Transport by Loughborough Universityhas shown that on UK roads, cars tted with ESC are 25% less likelyto be involved in a fatal accident than those without ESC. If every vehiclewere tted with ESC, this would equate to 380 fewer fatal accidentsannually. Serious crashes involving skidding or overturning could bereduced by up to 59%.

What are the benets?

is ESC ?whatESC is often soldwith differentnames: ESP, VSA,DSTC and others.

ESC is a major safety featurewhich could save your life

Electronic Stability C ontrol, ESC, helpsto prevent the driver from losing controlin a skid. ESC automatically controls the vehicle by comparing thesteering actions carried out by the driver to what the vehicle is actually doing.If the ESC senses that the vehicle is veering from the required course a skid it automatically brakes selected wheels to bring the car back into line.

OversteerIf you swerve to avoid anobstacle such as a rapidlane change on a motorway,oversteer can occur makingthe vehicle turn more thanintended, ultimately leadingto a spin. ESC can preventthis by braking individualwheels to maintain control.

UndersteerIf you are driving too fastinto a corner, understeercan occur. This would resultin a loss of steering controlas your car continues to followa straight path and not steeras required. ESC can helpretain steering control andallow the car to travel in thedesired direction.


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Outriggers tted to the VolkswagenTransporter to prevent risk of rollover

ut does ESCally work?hilst the tment ratingslp to inform consumersout buying cars ttedth ESC, it is a completelyfferent question to verifyat ESC actually works.Thatcham has been

sting ESC systems

dynamically since 2008,following an internationaltest procedure. The aimof this dynamic testing is toverify that the ESC systemsare actually operating asthey should do. Euro NCAPhas followed suit and isnow testing cars in thesame way.

LegislationIn the US, there is aregulation (FMVSS 126)that requires ESC to bemandatory on all cars by2012. This regulationhas been proposed asa GTR (Global TechnicalRegulation). In Europe ESCwill be compulsory for newtypes of car from November

2011, and for all newcars by November 2014.The regulations includespecication of the ESCsystem components andfunctionality, the ESCon/off switches, and tell-tales on the dashboardas well as the dynamictest procedure.

Thatcham has been publishing ESC tment ratings for the last fewyears to raise awareness of this important safety technology, and to

encourage drivers to buy cars tted with ESC. Manufacturers haverisen to the challenge and now more widely t ESC as standard.

Thatcham has a programme ofdynamic testing of vehicles forESC functionality, in additionto the publication of tmentratings (see www.thatcham.org/esc). This dynamic testingis based on the procedure inthe GTR 8 which assessesthe performance requirementsof the ESC system, resultingin either a pass or fail. Forgreater detail on the testprocedure and assessmentcriteria, please also seeResearch News specialedition on ESC 2009.

A steering robot is requiredto carry out this testing whichtakes over from the driver toprovide the steering input in asafe, precise and repeatable

way. The test has severalstages and begins with brakeand tyre conditioning. Aslowly increasing steer testis performed to dene thesteering wheel angle input Afor the Sine with Dwell. Thetest is then performed afteranother series of the tyreconditioning runs. The test isa Sine with Dwell manoeuvreat 50mph and comprisesa sinusoidal steer in onedirection, followed by a steerin the opposite direction, witha dwell of 500 millisecondsat the second peak. The runsare repeated with both theleft and right initial inputs. Theruns start with a small steeringinput and build up to asteering wheel angle of 270.

Time

S t e e r

i n g w

h e e

l a n g

l e

-

Sine with Dwell steering input usedfor dynamic ESC test

dynamictesting

The runs startwith a smallsteeringinput andbuild up toa steeringwheel angleof 270.

The latest tment ratingsfor 2010 are available atwww.thatcham.org/esc

criteria


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ove:esponsive vehicle:L (lateral displacement


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Alfa Romeo Guilietta

FinalHeading(greatest

magnitude)

21.5

Stability CriterionResponsiveness CriterionGTRPass

Aston Martin DB9


magnitude)

41.4


Alfa Romeo MiTo


magnitude)

42.3

Stability CriterionResponsiveness Criterion

GTRPass

Audi A1


magnitude)

36.3


GTRPass

The test results are compiledfor the sample of vehiclestested since 2008. For thispublication, graphics areprovided as an indicationof the lateral displacement

and yaw velocity accordingto the GTR. The additionalcalculation of nal heading isprovided in the table. Resultsdata is also available atwww.thatcham.org/esc

resultsdynamic test

esultsAudi A4


magnitude)

29.9


GTRPass

Citron C3 Picasso


magnitude)

17.4


GTRPass

Audi Q5


magnitude)

41.0


GTRPass

Citron C4


magnitude)

12.1


GTRPass

BMW 5-Series


magnitude)

18.4


GTRPass

Citron DS3


magnitude)

36.2


GTRPass

BMW X1


magnitude)

15.2


Ford C-Max


magnitude)

15.5


Chevrolet Cruze


magnitude)

31.4


GTRPass

Ford Fiesta


magnitude)

34.7


GTRPass


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Honda Accord


magnitude)

12.7


GTRPass

Hyundai i20


magnitude)

18.0


GTRPass

Honda Civic


magnitude)

39.9


GTRPass

Hyundai iX35


magnitude)

12.4


GTRPass

Honda CR-Z


magnitude)

35.5


GTRPass

Jaguar XF


magnitude)

29.9


GTRPass

Honda Insight


magnitude)

24.4


Kia Soul


magnitude)

24.2


Honda Jazz


magnitude)

30.1


GTRPass

Kia Sportage


magnitude)

14.6


GTRPass

Kia Venga


magnitude)

24.6


GTRPass

Mercedes E-Class E220 CDi


magnitude)

27.9


GTRPass

Mazda 3 Sport


magnitude)

57.5


GTRPass

Mercedes E-Class E350


magnitude)

13.9


GTRPass

Mazda 3 TS2


magnitude)

60.3


GTRPass

MINI Countryman


magnitude)

12.5


GTRPass

Mazda 6


magnitude)

20.1


Mitsubishi Lancer


magnitude)

20.8


Mazda CX-7


magnitude)

19.6


GTRPass

Nissan Cube


magnitude)

18.9


GTRPass


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Peugeot 3008


magnitude)

17.5


GTRPass

Saab 9-5


magnitude)

22.8


GTRPass

Peugeot 308


magnitude)

25.8


GTRPass

Seat Exeo


magnitude)

14.5


GTRPass

Peugeot 308cc


magnitude)

13.7


GTRPass

Skoda Superb


magnitude)

37.0


GTRPass

Peugeot 5008


magnitude)

11.7


Skoda Yeti


magnitude)

49.2


Renault Grand Scenic


magnitude)

31.3


GTRPass

Subaru Impreza RC


magnitude)

47.7


GTRPass

Subaru Impreza WRX STI


magnitude)

39.3


GTRPass

Toyota Prius


magnitude)

18.9


GTRPass

Suzuki Swift


magnitude)

62.0


GTRPass

Toyota Urban Cruiser


magnitude)

25.2


GTRPass

Toyota Avensis


magnitude)

13.3


GTRPass

Toyota Verso


magnitude)

15.3


GTRPass

Toyota iQ


magnitude)

14.7


Vauxhall / Opel Astra Exclusiv CDTi


magnitude)

46.4


Toyota Land Cruiser


magnitude)

10.9


GTRPass

Vauxhall / Opel Astra SRi


magnitude)

42.4


GTRPass


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Vauxhall / Opel Insignia


magnitude)

40.3


GTRPass

Volkswagen Scirocco


magnitude)

40.1


GTRPass

Vauxhall / Opel Meriva


magnitude)

17.3


GTRPass

Volkswagen Sharan


magnitude)

12.9


GTRPass

Volkswagen Golf 5


magnitude)

52.3


GTRPass

Volkswagen Tiguan


magnitude)

17.7


GTRPass

Volkswagen Golf 6


magnitude)

38.2


Volkswagen Transporter


magnitude)

13.0


Volkswagen Polo


magnitude)

28.2


GTRPass

Volvo XC60


magnitude)

23.4


GTRPass

Citron DS3: GTR Pass


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All the new cars tested to date have passed thisdemanding ESC dynamic test. This shows thatthese cars, which are sold as having ESC systemstted, also have the functionality to operate

and maintain control of the car in this severemanoeuvre. However, they do not all performthe same way, and some differences betweenthe systems are revealed.

throttle response and ESCsystem (known as VehicleDynamic Control (VDC)by Alfa Romeo). In Dynamic

Mode, the MiTo actuallyfailed the ESC test, sodrivers must be aware ofhow these systems operateto ensure they are protectedby ESC at all times. This isan example which highlightsthe differences betweenESC systems. Whilst all carspass the GTR test, the ESCsystems do not necessarilyintervene in the same way.

Driving modesThe Alfa Romeo MiTo has asystem called DNA, meaningDynamic, Normal and AllWeather driving modes. Thissystem adjusts the steering,

not all ESC systems are

equal

nterventionsESC

ESC InterventionsWhilst all the cars pass the GTR test, the results indicatethat ESC application varies greatly between vehicles.

All cars achieved a pass on the responsiveness criterionaccording to the GTR. In further analysis, the smallestdisplacement was selected for each vehicle, whichrepresents the run that is closest to a failure. There wasa large range in these lateral displacements, and thisindicates the wide variety in performance of the vehiclestested. The Toyota Land Cruiser had the smallest lateraldisplacement, whereas the Alfa Romeo MiTo had thelargest. Whilst a displacement closer to 1.83m is closerto failure according to the GTR, it is also possible thata larger displacement could pose a risk. A greaterdisplacement might indicate departure from thecarriageway, with associated risk of collision.

Some systems intervenepromptly to avoid loss ofcontrol. However, othervehicles allow much greateryaw velocities beforeintervention. All the vehiclestested passed the stabilitycriterion according to theGTR but there was a widevariety in responses. Thegreatest magnitude yawvelocity was selected for

each vehicle, which representsthe run that is closest to afailure since the ideal resultis 0%. The range at 1 secondafter completion of steer wasfrom -15% to 17% (fail is over35%), and at 1.75 secondsthe yaw velocities ranged from-7% to 4% (fail is over 20%).Again, this indicates the widevariety in performance ofthe vehicles.

T h e T o y o

t a L a n d C r u i s e r h a d t h e s m a l l e s t l a t e r a l

d i s p l a c e m e n t

. . . t

h e S u z u

k i S

w i f t h a d t h e l a r g e s t


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SubaruThe Subaru Impreza RC is anexample of a large negativeyaw velocity, and in particular,this has a larger magnitudethan the positive value. Thisnegative value represents ayaw in the opposite direction.

In many cases, the car willexperience both positive andnegative yaw velocities as itsettles following the steeringinput.

Time (s)

Yaw velocity (/s)PassSteering RobotAngle ()

-

-

--

-

-

-

.

-

-

-

-

-

-

- -

-

-

-

-

-

-

-

-

-

-

l

-90

-70

-50

-30

-10

10

30

50

70

90

-1 0 1 2 3 4 5

-300

-200

-100

0

100

200

300

Yaw velocity-15%

l

Y a w v e

l o c i

t y ( / s )

Mazda 3 TS2: exampleof a large positive yaw velocity

MazdaThe Mazda 3 TS2 is anexample of the greatestmagnitude (17%) of yawvelocity shown in thetesting. This shows thata large amount of yaw is

allowed before the ESCsystem intervenes.

-

-

--

-

-

-

.

-

-

- -

-90

-70

-50

-30

-10

10

30

50

70

90

-1 0 1 2 3 4 5

-400

-300

-200

-100

0

100

200

300

400

Yaw velocity17%

-

-

-

-

-

-

-

-

- l

-

-

-

-

-

-

-

-

-

-

l

Y a w v e

l o c i

t y ( / s )

Time (s)


Subaru Impreza RC: exampleof a large negative yaw velocity

rangeperformance

Suzuki Swift: example of large nalheading

SuzukiThe Suzuki Swift had thegreatest nal heading of 62,which was the largest of allthe cars tested. This vehiclealso had the greatest yawvelocity result of 16% at 1second after COS, which isalso one of the highest. Thehigher the yaw velocity andthe longer the duration, themore the vehicle turns, andtherefore the greater the nalheading. Once the steeringmanoeuvre is completed andthe steering wheel returnsto straight ahead, the ESCsystem has to work to controlyaw and bring the vehicle pathback in line with the

drivers intention. A larger nalheading might increase therisk that the vehicle leavesthe carriageway, which mayconsequently pose a greatercollision risk.

Volkswagen Tiguan: exampleof tightly controlled yaw velocity

VolkswagenThe Volkswagen Tiguan isan example of a vehicle withvery tight control on the yawvelocity, which returns to zerovery quickly after the steeringmanoeuvre. However, this

might be attributed to the rollcontrol elements of the systemrather than directly to the ESCsystem (that controls yaw).

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

- l

-

-90

-70

-50

-30

-10

10

30

50

70

90

-1 0 1 2 3 4 5Time (s)

-300

-200

-100

0

100

200

300

Yaw velocity 0%

Y a w v e

l o c

i t y ( / s )



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12/13

In 2006, Thatcham beganto produce tment ratingsfor ESC, and found thatonly 40% of UK models

were being sold with ESCtted as standard. Now,after 5 years, this gurehas increased to 75%.

ESC has recently beenmade a regulatoryrequirement globally. Allbrand new models soldmust be tted with ESC asstandard from 2012, and allcars including facelifts andupdates by 2014. Lookingback at the standardtment rates in 2008,the increase in standardtments compared to

2007 was only 6%; but for2010 tments comparedto 2009, that increasehas doubled to 12%. We

are now beginning to seethe increase in standardtments that is required bythe impending regulatoryrequirements.

New modelstted withstandard ESCThe majority of newmodels are being broughtto market with ESC ttedas standard. Some oldercars remain available withESC not available or asan option. Car buyersmight want to save some

money during these timesof economic pressure,but compromising vehiclesafety capability is surely

a high risk strategy.Thatcham recommendsthe purchase of a car ttedwith ESC, even if it costsmore. For full informationabout the ESC tments,please refer to the websitewww.thatcham.org/esc .The tment informationcan be used to helpinform people makinga car purchase about theavailability of ESC, whetherit is a new car purchaseor an older car.

For ESC tment information:www.thatcham.org/esc

2006 2010

29%

7%

75%

4%

40%

27%

4%

14%

Not available at all

Optional across the entire range

Standard across the entire range

Combination of fitment

NOTE: ESC cannot defy the laws of PhysicsIf you are travelling too fast for the road conditions,ESC can only try to help prevent an accident occurring.

Real world example of a single vehicle rollover crash,where ESC might be effective. ESC UK tment


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