1. WLTP Road Load Family concept
WLTP rev1e
BMW,
WLTP Road Load Family concept
Proposal on a family definition for road load determination

2. from WLTP-DTP-LabProcICE-172 - Comparison RLD flatbelt_VW.pdf
WLTP Road Load Family
Status and Introduction
In the current GTR two coast downs are necessary for one CO2-family.
Coast down testing is very time consuming and inflexible (weather, track capacity, …)
Many parameters that must be equal within one CO2-family (for good reasons) have no other effect on the road load except for their effect on weight and aerodynamics which is accounted for in the interpolation.
Example: The engine is decoupled during coast down, therefore neither the engine type nor the engine temperature is relevant for road load determination.
A definition of a road load family, that is bigger than the CO2-family, is possible.
A road load family avoids unnecessary workload without losing accuracy.
Such a family has synergistic effects e.g. a family for the alternative warm-up procedure or for a validation/calibration of a wind tunnel could also be this road load family.
If the concept of developing a road load family is agreed, the details should be worked out in a small subgroup.
from WLTP-DTP-LabProcICE Comparison RLD flatbelt_VW.pdf
WLTP Road Load Family Concept, BMW,

3. from WLTP-DTP-LabProcICE-172 - Comparison RLD flatbelt_VW.pdf
WLTP Road Load Family
Clarification of road load influences
influences on road load
assessed by
mass
combined approach
rolling resistance
aerodynamics
drivetrain type (2WD/4WD)
tbd in
road load family
drivetrain losses
gearbox type (MT, AT, …)
tbd
not relevant
for road load
The engine has no influence on road load, as it is decoupled, apart from:
Weight, aerodynamic (and rolling resistance) influences.  They are covered by the calculation of the individual road load coefficients!
from WLTP-DTP-LabProcICE Comparison RLD flatbelt_VW.pdf
WLTP Road Load Family Concept, BMW,

4. from WLTP-DTP-LabProcICE-172 - Comparison RLD flatbelt_VW.pdf
WLTP Road Load Family
Calculation of road load influences, Annex 7
Calculation of road load for individual vehicles in the CO2 vehicle family
Calculation of cycle energy per phase
Calculation of the CO2 value for an individual vehicle by the CO2 interpolation method
Formulas for road load family
Formulas for both families
Formulas for CO2-family
from WLTP-DTP-LabProcICE Comparison RLD flatbelt_VW.pdf
WLTP Road Load Family Concept, BMW,

5. from WLTP-DTP-LabProcICE-172 - Comparison RLD flatbelt_VW.pdf
WLTP Road Load Family
Proposal for road load Family
Proposal:
Use CO2-family as a starting point.
Exclude parts, which are decoupled in neutral.
Increase transmission ratio tolerance, as its influence on road load is almost negligible.
Additionally define maximum range for weight, rolling resistance and aerodynamics.
This would result in the following situation:
Diesel and gasoline (and different power of them) can be in the same road load family.
2WD/4WD and MT/AT would be in different road load families.
Road load influence (e.g. mass-difference of engines) to be included.
Next steps, if concept is agreed:
Work out exact figures.
Carry out at least one validation measurement.
Remark: Until now no expert discussion has taken place.
This discussion will take place within the following group:
Contact Persons:
Rob Cuelenaere (TNO), Christoph Lueginger (BMW)
Experts:
Markus Bergmann (Audi), Norbert Ligterink (TNO), Toshihisa Yamaguchi (Japan), Annette Feucht (Audi), Björn Ramacher (VW), Nakhawa (India), Iddo Riemersma (T&E), Bill Coleman (VW), Caro Hosier (Ford), Laura Bigi (PSA), Bob Latu (Renault), Bertrand Mercier (PSA)
Time frame: ?
from WLTP-DTP-LabProcICE Comparison RLD flatbelt_VW.pdf
WLTP Road Load Family Concept, BMW,

6. WLTP – Family Definitions
Example With limited parameters
RLD: Road Load Determination ATCT: Ambient Temperature Correction Test CA: Combined Approach
1. RLD – Family 3 series MT Gasoline / Diesel
2. RLD – Family 3 series AT Gasoline / Diesel
CA Family 3 series MT Gasoline
CA Family 3 series MT Diesel
CA Family 3 series AT Diesel
CA Family 3 series AT Gasoline
2. ATCT Family, Gasoline MT / AT
1. ATCT Family, Diesel MT / AT
2. ATCT Family, Gasoline MT / AT
3. RLD – Family 5 series MT Gasoline / Diesel
4. RLD – Family 5 series AT Gasoline / Diesel
CA Family 5 series MT Gasoline
CA Family 5 series MT Diesel
CA Family 5 series AT Diesel
CA Family 5 series AT Gasoline

7. from WLTP-DTP-LabProcICE-172 - Comparison RLD flatbelt_VW.pdf
WLTP Road Load Family
Backup
Backup
from WLTP-DTP-LabProcICE Comparison RLD flatbelt_VW.pdf
WLTP Road Load Family Concept, BMW,

8. from WLTP-DTP-LabProcICE-172 - Comparison RLD flatbelt_VW.pdf
WLTP Road Load Family
CO2-Family definition
5.6. CO2 vehicle family
Unless vehicles are identical with respect to the following vehicle/powertrain/transmission characteristics, they shall not be considered to be part of the same CO2 vehicle family:
(a) Type of internal combustion engine: fuel type, combustion type, engine displacement, full-load characteristics, engine technology, and charging system shall be identical, but also other engine subsystems or characteristics that have a non-negligible influence on CO2 under WLTP conditions;
(b) Operation strategy of all CO2-influencing components within the powertrain;
(c) Transmission type (e.g. manual, automatic, CVT);
(d) n/v ratios (engine rotational speed divided by vehicle speed). This requirement shall be considered fulfilled if, for all transmission ratios concerned, the difference with respect to the transmission ratios of the most commonly installed transmission type is within 8 per cent;
(e) Number of powered axles;
(f) [RESERVED: family criteria for EVs].
from WLTP-DTP-LabProcICE Comparison RLD flatbelt_VW.pdf
WLTP Road Load Family Concept, BMW,