Commission Implementing Decision (EU) 2018/2079Show full title

ANNEX U.K. METHODOLOGY TO DETERMINE THE CO₂ SAVINGS OF THE USE OF THE ENGINE IDLE COASTING FUNCTION

1. INTRODUCTION U.K.

To determine the CO₂ savings that can be attributed to the use of the Engine Idle Coasting Function, it is necessary to specify the following:

(1)

The test vehicles;

(2)

The procedure to precondition the vehicle;

(3)

The procedure to perform the dynamometer road load determination;

(4)

The procedure to define the modified testing conditions;

(5)

The procedure to determine the CO₂ emissions of the eco-innovative vehicle under modified testing conditions;

(6)

The procedure to determine the CO₂ emissions of the baseline vehicle under Type 1 hot start conditions;

(7)

The calculation of the CO₂ savings;

(8)

The calculation of the uncertainty of the CO₂ savings.

2. SYMBOLS, PARAMETERS AND UNITS U.K.

Latin symbols U.K.

—

CO₂ savings [g CO₂/km]

CO₂

—

Carbon dioxide

c

—

Conversion parameter

B_MC

—

Arithmetic mean of the CO₂ emissions of the baseline vehicle under modified testing conditions [gCO₂/km]

E_MC

—

Arithmetic mean of the CO₂ emission of the eco-innovation technology vehicle under modified testing conditions [gCO₂/km]

—

Arithmetic mean of the CO₂ emission of the baseline vehicle under type approval (NEDC) hot start conditions [gCO₂/km]

B_TA

—

Arithmetic mean of the CO₂ emission of the baseline vehicle under type approval (NEDC) testing conditions [gCO₂/km]

E_TA

—

Arithmetic mean of the CO₂ emission of the eco-innovation technology vehicle under type approval (NEDC) testing conditions [gCO₂/km]

RCD_RW

—

Relative coasting distance under real world conditions [%]

RCD_mNEDC

—

Relative coasting distance under modified testing conditions [%]

UF

—

Usage factor of the coasting technology

—

Statistical margin of the total CO₂ saving [g CO₂/km]

—

Standard deviation of the arithmetic mean of the CO₂ emission of the baseline vehicle under type approval (NEDC) hot start conditions [gCO₂/km]

—

Standard deviation of the arithmetic mean of the CO₂ emission of the eco-innovation vehicle under modified testing conditions [gCO₂/km]

s_UF

—

Standard deviation of the arithmetic mean of the usage factor

Subscripts U.K.

RW

—

Real-world conditions

TA

—

Type approval (NEDC) conditions

B

—

Baseline

3. TEST VEHICLES U.K.

The test vehicles shall fulfil the following requirements:

(a)

Baseline vehicle: a vehicle with the innovative technology deactivated or not installed. For that vehicle, it shall be verified that the coasting function is not activated during the NEDC test (i.e. the test run to obtain );

(b)

Eco-innovative vehicle: a vehicle with the innovative technology installed and active in default or predominant mode. The predominant driving mode is the driving mode that is always selected when the vehicle is switched on regardless of the operating mode selected when the vehicle was previously shut down. Engine-on coasting function may not be deactivated by the driver in the predominant driving mode;

4. VEHICLES PRECONDITIONING U.K.

In order to reach the hot testing conditions of the powertrain, one or more complete preconditioning NEDC or mNEDC driving cycles shall be performed.

5. ROAD LOAD DETERMINATION U.K.

The dynamometer road load determination shall be carried out on a chassis dynamometer as follows:

• Preconditioning the vehicle according to point 4;

• Performing the dynamometer road load determination, according to the procedures defined in the UN/ECE Regulation No 83 Annex 4a — Appendix 7.

6. DEFINITION OF THE MODIFIED TESTING CONDITIONS U.K.

6.1. Definition of the Coast Down Curve U.K.

The determination of the coast down curve in coasting mode shall be carried out on a chassis dynamometer and following these two compulsory steps:

• Bringing the vehicle to operating temperature using the preconditioning procedure;

• Executing a coast down in coasting mode from 125 km/h to either a standstill or to the lowest possible coasting speed.

6.2. Generation of the modified NEDC Speed Profile (mNEDC) U.K.

The speed profile of the mNEDC shall be generated according to the following rules:

• The test sequence is composed of an urban cycle made of four elementary urban cycles and an extra-urban cycle;

• All acceleration ramps are identical to the NEDC-profile;

• All constant speed levels are identical to the NEDC-profile;

• The deceleration values when coasting function is deactivated are equal to the ones within the NEDC-profile;

• The speed and time tolerances shall be in accordance with paragraph 1.4 of Annex 7 to UN/ECE Regulation No 101.

• The deviation from the NEDC profile shall be minimised and the overall distance must comply with the NEDC specified tolerances;

• The distance at the end of each deceleration phase of the mNEDC-profile shall be equal to the distances at the end of each deceleration phase of the NEDC-profile;

• For all phases of acceleration, constant velocity and deceleration, standard NEDC tolerances shall be applied.

• During coasting phases the ICE is decoupled and no active correction of the vehicles velocity trajectory is permitted.

• Lower speed limit for coasting v_min: The coasting mode has to be disabled at the lower speed limit (15 km/h) for coasting by pressing the brake pedal.

• Minimal stop time: The minimum time after every coasting deceleration to a standstill or constant speed phase is 2 seconds ( in Figure 1).

• Minimum duration for constant speed phases: The minimum duration for constant speed phases after acceleration or coasting deceleration shall be at least 2 seconds ( in Figure 1).

• During the deceleration phases, the coasting mode can be enabled if the speed is below v_max, v_max being the maximum speed of the test cycle.

• The coasting mode may be disabled for speeds higher than v_min.

Figure 1 Illustration of parameters used to generate mNEDC U.K.

Shift profile generation for vehicles with manual gearbox U.K.

For vehicles equipped with manual gearboxes, the gearshift table shall be adapted using the following assumptions:

1.

The gearshift selection during vehicle acceleration remains as defined for the NEDC

2.

the timing for the downshifts of the modified NEDC differ from the one of the NEDC in order to avoid downshifts during coasting phases (e.g. anticipated before deceleration phases)

The pre-defined shift points for the ECE portion of the NEDC cycle are modified as described in the following table:

¹ PM = gearbox in neutral, clutch engaged. K1, K2 = first or second gear engaged, clutch disengaged. U.K.

7. DETERMINATION OF THE CO₂ EMISSIONS OF THE ECO-INNOVATIVE VEHICLE UNDER MODIFIED TESTING CONDITIONS (E_MC) U.K.

The emissions of CO₂ of the eco-innovative vehicles shall be measured in accordance with Annex 6 of UN/ECE Regulation No 101 (Method of measuring emissions of carbon dioxide and fuel consumption of vehicles powered by an internal combustion engine only). The following elements shall be modified:

• The preconditioning of the vehicle

• The speed profile

• The number of tests

Preconditioning of the vehicle U.K.

The preconditioning shall be conducted according to Section 4 of the present Annex.

Speed profile U.K.

The speed profile shall be generated according to Section 6 of the present Annex.

Number of tests U.K.

The complete test procedure on the test bench shall be repeated at least three times. The arithmetic mean of the CO₂ emission from the eco-innovation vehicle (E_MC) and the respective standard deviation of the arithmetic mean ( ) shall be calculated.

8. DETERMINATION OF THE CO₂ EMISSIONS OF THE BASELINE VEHICLE UNDER MODIFIED TYPE APPROVAL HOT START CONDITIONS ( ) U.K.

The CO₂ emissions of the baseline vehicles have to be measured in accordance with Annex 6 of UN/ECE Regulation No 101 (Method of measuring emissions of carbon dioxide and fuel consumption of vehicles powered by an internal combustion engine only). The following elements shall be modified:

• The preconditioning of the vehicle

• The number of tests

Preconditioning of the vehicle U.K.

The preconditioning shall be done according to Section 4 of the present Annex.

Number of tests U.K.

The complete test procedure under type approval (NEDC) hot start conditions on the test bench shall be repeated at least three times. The arithmetic means of the CO₂ emission from the baseline vehicle ( ) and the respective standard deviation of the arithmetic mean ( ) shall be calculated.

9. CALCULATION OF THE CO₂ SAVINGS U.K.

The formula to calculate the CO₂ savings is the following:

Formula 1: U.K.

Where

:

CO₂ savings [gCO₂/km]

B_MC

:

Arithmetic mean of the CO₂ emissions of the baseline vehicle under modified testing conditions [gCO₂/km]

E_MC

:

Arithmetic mean of the CO₂ emission of the eco-innovation technology vehicle under modified testing conditions [gCO₂/km]

B_TA

:

Arithmetic mean of the CO₂ emission of the baseline vehicle under type approval (NEDC) testing conditions [gCO₂/km]

E_TA

:

Arithmetic mean of the CO₂ emission of the eco-innovation technology vehicle under type approval (NEDC) testing conditions [gCO₂/km]

UF_MC

:

Usage factor of the coasting technology under modified conditions, which is 0,52 for vehicles equipped with a conventional powertrain and an automatic transmission and 0,48 for vehicles equipped with a conventional powertrain and a manual transmission with an automated clutch.

UF_TA

:

Usage factor of the coasting technology under type approval (NEDC) conditions

Since the innovative technology is not active under type approval (NEDC) conditions, the general equation for calculating the CO₂ savings can be simplified as follows:

Formula 2: U.K.

The term UF_MC of the Formula 2 will be hereafter simply written as ‘UF’ since it is the unique usage factor thanks to the previous simplification.

To determine B_MC, the same modified testing conditions should be followed by a vehicle which does not have the coasting function.

The assumption is that the baseline vehicle is able to perform a sailing curve (line 2′ in Figure 2) without disconnecting the engine from the wheels, although with lower efficiency than a coasting vehicle (able to disconnect the engine from the wheels). Sailing is intended as the hypothetical coasting behaviour of the baseline vehicle.

Figure 2 Sailing curve for baseline vehicle U.K.

A common characteristic of a baseline vehicle is that, during deceleration phases of the type approval (NEDC) (3) and modified (2′ + 3′) testing conditions, no fuel is used (cut-off).

The definition of the coasting curve (1′ + 2′ + 3′) for the baseline vehicle is a complex process since different parameters are involved (e.g. gear range, electric power demand, transmission temperature). Since it would therefore be difficult for the driver to follow this speed trace without exceeding the speed and time tolerances, it has therefore been proposed to use a conversion parameter (i.e. c-factor) to calculate the CO₂ emissions of the baseline vehicle under modified conditions (B_MC) from the CO₂ emissions of the baseline vehicle emissions under type approval (NEDC) hot start conditions ( ).

The relation between and B_MC is defined using the c-factor, shown on the following Formula 3

Formula 3: U.K.

As consequence, Formula 2 becomes

Formula 4: U.K.

Where

c

:

Conversion parameter which is 0,960

:

Arithmetic mean of the CO₂ emission of the baseline vehicle under type approval (NEDC) hot start conditions [gCO₂/km]

E_MC

:

Arithmetic mean of the CO₂ emission of the eco-innovation vehicle under modified testing conditions [gCO₂/km]

UF

:

Usage factor of the coasting technology under modified conditions, which is 0,52 for vehicles equipped with a conventional powertrain and an automatic transmission and 0,48 for vehicles equipped with a conventional powertrain and a manual transmission with an automated clutch.

Determination of the Usage Factor U.K.

The usage factor has been defined by Formula 5.

Formula 5: U.K.

With:

RCD_RW

:

Relative coasting distance under real world conditions [%];

RCD_mNEDC

:

Relative coasting distance under modified NEDC testing conditions [%].

The relative coasting distance RCD under real world conditions is defined as the distance travelled with coasting active divided by total driving distance per trip.

10. CALCULATION OF THE UNCERTAINTY U.K.

The uncertainty of the total CO₂ saving should not exceed 0,5 g CO₂/km (Formula 6).

Formula 6: U.K.

:

Statistical margin of the total CO₂ saving [g CO₂/km],

The formula to calculate the statistical margin is

Formula 7: U.K.

Where

:

Statistical margin of the total CO₂ saving [g CO₂/km],

c

:

Conversion parameter which is 0,960

:

Arithmetic mean of the CO₂ emission of the baseline vehicle under type approval (NEDC) hot start conditions [gCO₂/km]

:

Standard deviation of the arithmetic mean of the CO₂ emission of the baseline vehicle under modified testing conditions [gCO₂/km]

E_MC

:

Arithmetic mean of the CO₂ emission of the eco-innovation vehicle under modified testing conditions [gCO₂/km]

:

Standard deviation of the arithmetic mean of the CO₂ emission of the eco-innovation vehicle under modified testing conditions [gCO₂/km]

UF

:

Usage factor of the coasting technology, which is 0,52 for vehicles equipped with a conventional powertrain and an automatic transmission and 0,48 for vehicles equipped with a conventional powertrain and a manual transmission with an automated clutch.

s_UF

:

Standard deviation of the arithmetic mean of the usage factor, which is 0,027;

11. ROUNDING U.K.

The calculated CO₂ savings value ( ) and the statistical margin of the CO₂ saving ( ) must be rounded up and expressed to a maximum of two decimal places.

Each value used in the calculation of the CO₂ savings (i.e. and E_MC) can be applied unrounded or must be rounded up and expressed to a minimum number of decimals which allows the maximum total impact (i.e. combined impact of all rounded values) on the savings to be lower than 0,25 gCO₂/km.

12. DEMONSTRATION THAT THE MINIMUM THRESHOLD IS EXCEEDED IN A STATISTICALLY SIGNIFICANT WAY U.K.

In order to demonstrate that the 1 gCO₂/km threshold is exceeded in a statistically significant way, the following Formula shall be used:

Where

MT

:

Minimum threshold [gCO₂/km]

:

CO₂ savings [gCO₂/km]

:

Statistical margin of the total CO₂ saving [g CO₂/km],

Where the CO₂ emission savings, as a result of the calculation using Formula 4 are below the threshold specified in Article 9(1) of Implementing Regulation (EU) No 725/2011, the second subparagraph of Article 11(2) of that Regulation shall apply.