1. Feed-back approach on RLD
Implementation options for feed-back approach on road load determination
Iddo Riemersma – Transport & Environment
EU-WLTP meeting 15 October Brussels

2. Problem description
Customer expectation: Realistic fuel consumption figures
Required: Test procedure aiming at representative conditions for production vehicles (cycle, road load, temperature etc.)
Road load not tested on production vehicle but on a pre-production vehicle, at a special test track and under ideal conditions
‘Flexibilities’ in current ISO road load test procedure: this offsets the homologation test results

3. Justification data
TU Graz measured 9 to 24% higher CO2 emissions compared to TA value on 6 production vehicles by applying actual measured road load.
T&E road load study showed on average 11% higher CO2 due to non-representative road load
VTT measured 28% difference between reported and measured CO2, using actual road-load factors

4. Different approaches Feed forward approach Feed back approach
Requirements
Requirements
Coast down test vehicle
Road load data
Production vehicle
Requirements
Requirements
Requirements
Requirements
Coast down test vehicle
Road load data
Production vehicle
Road load data

5. Objectives WLTP
More representative test cycle and test procedure, leading to representative fuel consumption/CO2 emissions
Level playing field for manufacturers
Closing the gap between actual and homologation road-load helps to achieve these objectives
Only way to close the gap is to check road-load of production vehicles (feed-back approach)
All subsequent testing will be based on realistic road-load

6. Options for feed-back approach
Check on paper Verify road-load relevant components/settings of production vehicles
Check by measurement Verify actual road-load on a run-in production vehicle

7. Check on paper Easy to implement, e.g. in CoP
Cost-effective solution, little administrative burden
Simple verification procedure, no extra tolerances
BUT:
No guarantee on a representative road-load
Tight vehicle requirements and tolerances needed

8. Check by measurement Best guarantee on a representative road-load
Implementation via ISC or independent in-use verification
Limited vehicle requirements and tolerances needed
BUT:
Extra tolerance range needed for production variance (and if applicable: user influences)
Practical difficulties / extra costs

9. Implementation details
Sample size
Should be balanced against added costs
Based on road-load consistency between vehicles
Related to sanctioning measures
Sample timing/frequency
Better towards start of production
Allow sufficient run-in time

10. Implementation details
Tolerance
Road-load variation due to production variance, user influences, test conditions, test-to-test variation
Balanced tolerance: not too wide, not too narrow
Alternative: manufacturer declared road load
New or in-use production vehicle
New vehicle: more repeatable result
In-use vehicle: more representative result

11. Implementation details
Embedded or alongside legislation
Easy option: add to existing requirements (CoP or ISC)
Objective option: independent verification programme
Execution of verification
Manufacturer (easy, but possibly unrealistic road-load)
Technical Service / Type-approval authority
Independent test house (objective road-load, but more difficult to organise)

12. Recommendations Road-load verification by measurements
Testing of in-use vehicles
Verification testing at independent test houses
3 to 5 vehicles per vehicle family (or family group)
Manufacturer declared road-load (not to exceed)
Road load verification separated from type-approval
Obligation for road-load verification laid down in EU legislation (with execution and sanctioning details)

13. Next steps Discussion is needed on:
The necessity of a feed-back approach for road-load
How to establish a feed-back loop (options)
Implementation details and their relations
How to embed the feed-back approach into EU legislation