1. HDV fuel economy certification approaches around the globe
Dr. Felipe Rodríguez
Geneva, January 7, 2019
HD CO2 & FUEL EFFICIENCY HARMONIZATION WORKSHOP
78th GRPE Meeting

2. Overview of HDV activities in the G20 Transport Task Group
Outline
Overview of HDV activities in the G20 Transport Task Group
Overview of HDV CO2/FE certification approaches around the globe
Comparison of EU and US methodologies
Vehicle simulation tool
Air drag determination
Harmonization possibilities for HDV CO2/FE certification

3. Overview of HDV activities in the G20 Transport Task Group

4. What is the G20 Transport Task Group?
A voluntary platform for G20 countries to share respective experience and work together to improve the energy and environmental performance of motor vehicles, especially HDVs. 
Leading members: the EU and United States
Participants: Argentina, Australia, Brazil, Canada, China, Germany, India, Italy, Japan, Mexico, Russia, and the United Kingdom
IPEEC coordinates Transport Task Group and G20 activities
ICCT and GFEI are implementing organizations

5. Current TTG activities
Build domestic support and enhance capability for action to reduce the energy and environmental impacts of motor transport, especially HDVs.
Deep Dives
Identify and exchange best practices among G20 countries on the implementation of cost‑effective energy efficiency and emission control measures in the transportation sector.
Policy Exchanges
Conduct analysis and outreach to assess the opportunities, barriers, costs and benefits of HDV programs, and subsequently recommend a course of action for participating G20 countries.
Research Agenda

6. TTG History Nov 2014 June 2015 Oct 2015 Sept2016 Jul 2017 June 2017
RESEARCH AGENDA
Policies to reduce fuel consumption, air pollution, and carbon emissions from vehicles in G20 nations
FOUNDED
Australian G20 Presidency
2014
Nov 2014
2015
June 2015
Oct 2015
2016
Energy Ministers Communiqué
TTG History
POLICY EXCHANGES
Under the Turkey G20 Presidency, energy ministers agree to further support the work of the TTG
Continue policy exchanges over phone and webinar
Sept2016
Jul 2017
June 2017
Jan 2017
2017
from 2014 to 2018
World Class Standards
Under the China G20 Presidency, the Energy Efficiency Leading Programme encourages G20 members to work toward given examples of world-class clean fuel and vehicle standards
Energy Action Plan
RESEARCH AGENDA
G20 Hamburg Climate and Energy Action Plan for Growth
Impacts of world class vehicle efficiency and emissions regulations in select G20 countries
Topics of recent policy exchanges
EU Real Driving Emissions (RDE) Type Approval Test for LDVs
Argentina’s energy efficiency programs in transport
European Commission’s HDV CO2 Standards Proposal
Aug 2017
2018
Sept 2018
2019
RESEARCH AGENDA
Status of policies for clean vehicles and fuels in select G20 countries
DEEP DIVE
6 month in-depth webinar series on HDV CO2 certification
1ST IN-PERSON TTG MEETING
Argentina G20 Presidency

7. Objectives of the TTG Deep Dive project
Support voluntarily participating G20 TTG members to:
measure and certify heavy-duty vehicle (HDV) fuel consumption
design and implement HDV labeling programs and standards
tailor existing methodologies and simulation models (i.e. GEM and VECTO) to suit new regional contexts, obviating the need for brand new methods

8. Overview of HDV CO2/FE certification approaches around the globe

9. HDV standards developments around the globe 1/2
Type
FE & CO2 (ex. Canada); CAFE
FE; individual vehicle
FE; CAFE
CO2
Vehicle scope
GVWR > 3.85t
19 sub-categories, by vehicle type / duty cycle and GVW
GVW > 3.5t
66 sub-categories, by vehicle type / duty cycle and GVW
25 sub-categories, by type (bus/lorry) and GVW
Undecided.
Possible GVW>16 tonnes
Rigid trucks and tractor trailers 4x2 and 6x2
Timeframe
(full implementation)
MY2014 Phase 1
MY2018 Phase 2
MY2014 China I
MY2016 China II
MY2021 China III
MY2015
MY2025 (proposal)
2025 and 2030
(not yet adopted, standards proposal announced in 2018)
Certification
Engine dyno + component testing + whole vehicle simulation
Chassis dyno (base vehicles) or whole vehicle simulation (variants)
Engine dyno + whole vehicle simulation
Aero/Rolling tests (proposal)
Flexibilities
ABT scheme
None
Averaging. Initial credit system; now reduced at half.
Averaging and banking
Enforcement
Type approval
~Inspection / maintenance
Under development
Adapted from: White, B., & Hill, N. (2017). Analysis of fuel economy & GHG emission reduction measures from HDVs in other countries and of options for the EU. Ricardo Energy & Environment.

10. HDV standards developments around the globe 2/2
Type FE
Undecided; possibly FE
Undecided; likely both FE and CO2
Undecided; likely FE
Vehicle scope
>12t
Segmentation on GVW, number of axles, and truck type (rigid – tractor)
>3.85t
Undecided
>3.5t
4 sub-categories by duty cycle
Timeframe
(full implementation)
Steering group since 2014
CSFC standards:
Certification
Track testing at 40/60km/h
As US Phase 2
Flexibilities
Under development
Enforcement
Evaluation
Comments
In force from April 2018
Proposal for HDV F/CO2 timeline: Phase 1 ( ). Phase 2 ( ) Phase 3 ( ):
2012 General Law on Climate Change requires vehicle efficiency standards
Official announcement expected in near term
Adapted from: White, B., & Hill, N. (2017). Analysis of fuel economy & GHG emission reduction measures from HDVs in other countries and of options for the EU. Ricardo Energy & Environment.

11. US and Canada HDV fuel consumption certification
Coastdown test
Wind average correction
Tires test
GEM - Engine cycle generation
Engine testing:
Cycle averaged map
GEM
Transient correction
Standard vehicle specifications
Engine dyno mapping
Transmission and axle test
Powertrain correction
Powertrain testing option
Off cycle technologies
Declared CO2 and FC value
Input data
Dyno testing
Correction
Simulation
Output data

12. Europe HDV fuel consumption certification
Constant speed air drag test
Transmission and axle test
VECTO
WHTC test
Cross wind and speed profile correction
Transient correction
Tires test
Vertical load correction
Engine dyno mapping
Auxiliaries
Declared CO2 and FC value
Input data
Dyno testing
Correction
Simulation
Output data

13. China HDV fuel consumption certification
“Base” vehicle
“Variant” vehicle
Chassis dyno
Coastdown test data
Simulation modeling
Engine dyno mapping
Weighting factors to each vehicle type (e.g. bus, long-haul tractor)
Run C-WTVC cycle: record FC on urban, rural, and motorway segments of cycle
Measurement and calculation of fuel consumption
Input data
Output data
Dyno testing
Correction
Simulation

14. Japan HDV fuel consumption certification
Engine dyno testing
Standard vehicle specifications
Declared CO2 and FC value
Simulation modeling
Input data
Output data
Dyno testing
Correction
Simulation

15. (base vehicles tested, variants simulated)
Most regions use HDV simulation in combination with component certification to determine CO2 emissions
Rolling resistance, aerodynamic drag
From Testing
Standard Value
Chassis dyno testing
(base vehicles tested, variants simulated)
Payload
~1/2 payload
Full Payload
Constant speed testing
(40 and 60 km/h)
Transmission and axle losses
From Testing
Powertrain dyno testing (Optional)
Simulation Model
Engine map
From Testing
Test cycles
3 cycles (weighted, incl. grade)
2 cycles (weighted, incl. grade)
1 cycle (‘mini-cycles’ weighted)
5 cycles (incl. grade)

16. Comparison of EU and US methodologies

17. Vehicle simulation models

18. ”Fuel consumption simulation of HDVs in the EU: Comparisons and limitations” (2018)
A comparison study of the latest releases of GEM and VECTO
Although focused on VECTO, it describes the model architectures of both GEM and VECTO
Just main results are shown in this presentation
Rodríguez, F. (2018). Fuel consumption simulation of HDVs in the EU: Comparisons and limitations. International Council on Clean Transportation.

19. Input comparison between GEM and VECTO
Component
VECTO input
GEM input
Engine
Displacement, idle speed, fuel consumption map, full load torque curve, motoring friction curve, brake-specific fuel consumption over the Worldwide Harmonized Transient Cycle (WHTC)
Displacement, idle speed, fuel consumption map, full load torque curve, motoring friction curve, fuel consumption over the ARB Transient Drive Cycle for 9 different vehicle configurations
Transmission
Transmission type, gear ratios, torque loss map as a function of torque and speed for each gear, maximum torque and speed per gear
Transmission type, gear ratios, and maximum torque per gear.
Optional: Power loss map as a function of torque and speed for each gear
Axle
Axle ratio and torque loss map as a function of torque and speed
Axle ratio
Optional: Power loss map as a function of torque and speed
Aerodynamic drag
Air drag area as determined during the constant speed procedure. For rigid trucks, a standard box is used. For tractors, a standard trailer is used.
Air drag area as determined by the coastdown methodology. Standard trailers are used for tractor modeling.
Tires
Tire dimensions, rolling resistance coefficient (Crr), and load applied during the rolling resistance test for each axle
Rolling resistance coefficient (Crr) for each axle, and drive tire revolutions per mile
Vehicle
Curb vehicle weight, gross vehicle weight rating, and axle configuration
Vehicle weight reduction (sum of standardized weight reductions per component), vehicle regulatory subcategory (e.g., Class 8, sleeper cabin, high roof), and axle configuration
Other
Auxiliaries: Technology used for the following auxiliaries: cooling fan, steering system, electric system, pneumatic system, A/C system (whether it is present or not), and power take-off
Off-cycle technologies: Improvements through the application of the following technologies: Speed-limiter, neutral-idle, intelligent controls, accessory load reduction, extended idle reduction, tire pressure system, and other technologies.

20. GEM’s model architecture
GEM does not feature a graphical user interface.
GEM was developed in Matlab Simulink as a forward-looking model: The simulation runs from the accelerator pedal to the wheels.
The GEM architecture is comprised of four main modules: Powertrain, Vehicle, Driver, and Ambient.
The Driver module is a closed-loop controller

21. VECTO’s model architecture
VECTO was developed in C# as a backward-looking model: the simulation flow occurs in the opposite direction to the way it takes place in the actual vehicle.
The Driver Model converts the drive cycle information into an acceleration request, to ultimately locate an appropriate operating point in the engine fuel map
Once a valid engine operating point is found, the simulation moves to the next point in the driving cycle.

22. Comparison results: Constant speed cycles with grade
The engine work is useful to gauge the agreement in energy flows observed by the engine.
The fuel consumption is useful to assess the impact of the shifting strategies. For a given engine work, the shifting strategy determines the regions of the engine map.
Absolute error: 0.64%

23. Comparison results: Transient cycle
Despite the differences in model architecture (forward vs backward-looking), driver model, and shifting strategy; both VECTO and GEM produce similar results in terms of engine work and fuel consumption.
Absolute error: 2.03%

24. Air drag certification

25. EU’s constant speed test for air drag measurement
EU’s air drag test procedure (see EU 2017/2400 Annex VIII) measures the torque at the wheel at a high and a low speed to determine the air drag area (CdA in m2).
The methodology requires the measurement of the torque at the wheel, the vehicle position, and the wind speed and angle as observed by the vehicle.

26. US’s coast-down test for air drag measurement
The coast-down procedure that is followed in the United States it is described in §
The data measured in the coast-down test are the vehicle speed, the air speed and direction as observed by the vehicle. Furthermore, the road grade, wind speed and direction, ambient temperature, and atmospheric pressure as measured from a stationary weather station are also recorded.

27. Comparison of key points between US and EU air drag tests (1/2)
Parameter
EU constant speed
US coastdown
Torque meter
Hub, rim or half shaft torque meter
None
Vehicle warm up
90 minutes at high-speed target speed before zeroing torque meters
At least 30 minutes at 80 km/h
Low-speed test
Between 10 and 15 km/h
From 35 km/h to 12 km/h
High-speed test
Between 85 and 95 km/h
From 116 km/h to 93 km/h
Torque drift
Must not exceed 25 Nm
N/A
Anemometer calibration
Run test for anemometer calibration misalignment
No anemometer calibration for misalignment. Use of stationary weather station

28. Comparison of key points between US and EU air drag tests (2/2)
Parameter
EU constant speed
US coastdown
Tire rolling resistance (RRC) influence
The RRC is assumed to be constant and the same at high and low speed
The post-processing takes into account the speed dependence of the RRC
Spin axle losses
Torque measured at wheel, powertrain losses are irrelevant
The spin axle losses are estimated using a quadratic regression on the tire rotational speed.
CdA yaw angle correction
Correction to zero yaw based on generic formula
Correction to a yaw angle of 4.5° using CFD or wind tunnel testing
Cross wind correction
VECTO applies correction internally
GEM does not perform any further crosswind correction

29. Comparison of the drag area determination procedures in the European Union and the United States
ICCT is carried out air drag testing of EU and US vehicles over both testing procedures, constant speed and coast-down.
Results indicate that the US coast-down test results in lower aerodynamic drag values, compared to the EU constant-speed test.
Two upcoming papers, comparing the US and EU air drag testing methodologies, will be published in the first quarter of 2019

30. Takeaway messages
VECTO and GEM show very good agreement when simulated over a large set of identical vehicles
Results indicate that the US coast-down test results in lower aerodynamic drag values, compared to the EU constant-speed test
The accurate simulation of CO2 emissions of HDVs is more dependent on the component input data than on the selected model (VECTO vs GEM). Harmonization of component certification benefits the implementation of future regulatory measures.

31. Harmonization possibilities for HDV CO2/FE certification

32. Overall conditions: Region specific adaptations necessary
The CO2 certification methodology requires certain regions specific adaptations in the overall conditions (in blue).
VECTO and GEM are physics based models that does not require major specific adaptations to be used by other regions.
The component testing procedures developed by the EU are applicable to other regions without modifications.
Fleet segmentation
Duty cycles
Payloads
Standard bodies
Testing procedure

33. Certified component performance data
There are five key components that ne to measured to provide the necessary input for the simulation tool. The EU has in place a regulation that defines in detail the certification procedure for each of these components
Transmission and driveline
Aerodynamic drag
Engine
Tire rolling resistance
Vehicle characteristics

34. Tire rolling resistance measurement
In the US, the tire rolling resistance is measured using the test procedure defined by the standard ISO
In the EU, the rolling resistance is measured according to UN/ECE R117. The provisions established in UN/ECE R117 are largely equivalent to those in ISO
The determination of the rolling resistance can be done by measuring the horizontal reaction force, the torque input at the drum, the tire-drum system deceleration, or the power input at the drum.
ISO / UN/ECE R117 include provisions for an inter-laboratory alignment procedure using a control tire, to allow direct comparison between different test rigs and methods.

35. Engine transient correction procedure in the EU
Urban transient correction
WHTC test
COLD
Urban, rural, motorway
Rural transient correction
WHTC test
WARM
Urban, rural, motorway
Highway transient correction
Engine mapping
Fuel consumption
full load and motoring
Hot/cold balancing factor
Fuel’s lower heating value
Fuel correction factor
Input data
Dyno testing
Correction
Simulation
Output data

36. Engine transient correction procedure in the US
Phase 2 GEM cycle generator
Minimum 24 engine cycles (3 vehicle cycles for 8 configurations)
Minimum 8 standard vehicle configurations
Engine testing:
Cycle averaged map
Engine mapping
Fuel consumption
full load and motoring
Transient correction
Input data
Dyno testing
Correction
Simulation
Output data

37. Measurement of transmission and axle losses
In the EU, the measurement procedure of the torque losses of transmissions and axles is described in regulation EU 2017/2400, Annexes VI and VII.
For transmissions and other torque transferring components, three measurement options are possible, with increasing degrees of complexity.
In the US, the measurement of transmission and axles is an optional procedure. The default transmission and axle power maps are shown below.
The measurement procedure of the power losses of transmissions and axles is described in § and § respectively.

38. Takeaway messages
The US and EU component certification methodologies have several common points.
Axles, tires, and engine mapping procedures are similar.
Key differences include the aerodynamic drag determination methodology and the engine transient correction.
Harmonization of component certification has many advantages:
Facilitates transparent comparison of performance between different markets.
Facilitates the implementation of future regulatory measures.
Facilitates adapting GEM/VECTO to country-specific needs.
Streamlined processes and reduced cost of compliance for international manufacturers.

39. Questions? Contact the HDV team at the ICCT