Market surveillance of vehicle emissions : heavy-duty vehicles.
Date: 2023-05-31
Institutions: Joint Research Centre
Subjects: large vehicle, market supervision, motor vehicle pollution, reduction of gas emissions, research report, technical regulations, testing

Market Surveillance of Vehicle Emissions:  
Heavy-duty Vehicles 

Joint Action with Market Surveillance Authority from France 

Loos, R., Gioria, R., Selleri, T., Gruening, C., 
Suarez-Bertoa, R., Bonnel, P. 

2023 

ISSN 1831-9424 

EUR 31524 EN 

 
 
 
 
This publication is a Technical report by the Joint Research Centre (JRC), the European Commission’s science and knowledge service. It 
aims  to  provide  evidence-based  scientific  support  to  the  European  policymaking  process.  The  contents  of  this  publication  do  not 
necessarily  reflect  the  position  or  opinion  of  the  European  Commission.  Neither  the  European  Commission  nor  any  person  acting  on 
behalf of  the  Commission  is  responsible  for  the  use  that  might  be  made  of  this  publication.  For  information  on  the  methodology  and 
quality underlying the data used in this publication for which the source is neither Eurostat nor other Commission services, users should 
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any  opinion  whatsoever  on  the  part  of  the  European  Union  concerning  the  legal  status  of  any  country,  territory,  city  or  area  or  of  its 
authorities, or concerning the delimitation of its frontiers or boundaries. 

Contact information  
Name: Robert Loos and Pierre Bonnel 
Address: Via Enrico Fermi, 2749, 21027 Ispra (VA), Italy 
Email: robert.loos@ec.europa.eu or pierre.bonnel@ec.europa.eu 
Tel.: 0039.0332.786407 

EU Science Hub 
https://joint-research-centre.ec.europa.eu 

JRC133635 

EUR 31524 EN 

PDF 

ISBN 978-92-68-03939-7 

ISSN 1831-9424 

doi:10.2760/264418  KJ-NA-31-524-EN-N 

Luxembourg: Publications Office of the European Union, 2023 

© European Union, 2023 

The  reuse  policy  of  the  European  Commission  documents  is  implemented  by  the  Commission  Decision  2011/833/EU  of  12  December 
2011  on  the  reuse  of  Commission  documents  (OJ  L  330,  14.12.2011,  p.  39).  Unless  otherwise  noted,  the  reuse  of  this  document  is 
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This means that reuse is allowed provided appropriate credit is given and any changes are indicated.  

How to cite this report: Loos, R., Gioria, R., Selleri, T., Gruening, C., Suarez-Bertoa, R., Bonnel, P. Market surveillance of vehicle emissions: 
Heavy-duty vehicles, Publications Office of the European Union, Luxembourg, 2023, doi:10.2760/264418, JRC133635. 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
      
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Contents  

Abstract ....................................................................................................................................................................................................................................................................... 1 

Acknowledgements .......................................................................................................................................................................................................................................... 2 

1 

Introduction..................................................................................................................................................................................................................................................... 3 

2  Heavy-duty emissions requirements ..................................................................................................................................................................................... 4 

2.1 

Introduction ....................................................................................................................................................................................................................................... 4 

2.2  Tailpipe emissions ...................................................................................................................................................................................................................... 5 

2.3  World Harmonized Vehicle Cycle (WHVC) ............................................................................................................................................................ 6 

2.4  On-Board Diagnostics ............................................................................................................................................................................................................. 7 

2.4.1  Objectives and definitions ................................................................................................................................................................................ 7 

2.4.2  OBD testing ..................................................................................................................................................................................................................... 7 

2.5  Detection of Auxiliary Emissions Strategies (AES) ...................................................................................................................................... 8 

2.5.1 

Type approval requirements ........................................................................................................................................................................... 8 

2.5.2  Market surveillance verifications ............................................................................................................................................................... 8 

2.6  Durability ............................................................................................................................................................................................................................................. 9 

2.6.1 

Type approval requirements and methods ...................................................................................................................................... 9 

2.6.2  Methodology for durability assessment........................................................................................................................................... 10 

2.7  Overview of market surveillance tests ................................................................................................................................................................ 12 

3  Tailpipe emissions testing ............................................................................................................................................................................................................. 13 

3.1  Test vehicle .................................................................................................................................................................................................................................... 13 

3.2  Vehicle reception and examination ......................................................................................................................................................................... 14 

3.3  Emissions tests under regulated conditions ................................................................................................................................................... 14 

3.3.1 

Testing conditions .................................................................................................................................................................................................. 14 

3.3.2 

Test results ................................................................................................................................................................................................................... 15 

3.4  Emissions outside the regulated conditions ................................................................................................................................................... 16 

3.4.1 

Testing conditions .................................................................................................................................................................................................. 16 

3.4.2 

Test results ................................................................................................................................................................................................................... 17 

3.5  Effect of a single parameter and relative analysis ................................................................................................................................. 20 

3.5.1 

Introduction .................................................................................................................................................................................................................. 20 

3.5.2 

Data logger on OBD port ................................................................................................................................................................................ 20 

3.5.3 

Driving cycle ................................................................................................................................................................................................................ 21 

3.5.4 

AdBlue and Fuel level ......................................................................................................................................................................................... 22 

4  Other verifications................................................................................................................................................................................................................................. 24 

4.1  On-Board Diagnostics .......................................................................................................................................................................................................... 24 

4.2  Assessment of durability .................................................................................................................................................................................................. 25 

5  Conclusions .................................................................................................................................................................................................................................................. 27 

5.1  Main results ................................................................................................................................................................................................................................... 27 

5.2  Recommendations for market surveillance emissions testing on heavy-duty vehicles....................................... 27 

i 

 
 
References ............................................................................................................................................................................................................................................................. 28 

List of abbreviations and definitions ........................................................................................................................................................................................... 29 

List of figures ..................................................................................................................................................................................................................................................... 30 

List of tables ........................................................................................................................................................................................................................................................ 31 

ii 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Abstract 

This report presents the results for the work conducted jointly by the JRC and the French Market Surveillance 
Authority as a joint action of market surveillance (MaSu) and regarding emissions from motor vehicles. One 
N2  Diesel  heavy-duty  vehicle  (HDV)  was  tested  during  this  pilot  activity  on  the  road  under  regulated 
conditions fulfilling the Euro VI In-Service Conformity (ISC) requirements, and in the laboratory on a chassis 
dynamometer  under  the  word-harmonized  vehicle  cycle  (WHVC).  The  tests  were  performed  with  three 
different payloads (10%, 55% and 100%). During the on-road tests, emissions of NOx, CO, hydrocarbons, CH4 
and CO2 were measured using a portable emissions measurement system (PEMS). 

The document is structured in three main chapters:  

- An overview of the emissions requirements applicable to heavy-duty engines/vehicles and methodologies for 
their  verification,  covering  tailpipe  emissions,  on-board  diagnostics  (OBD),  detection  of  auxiliary  emissions 
strategies (AES), durability requirements, and an overview of market surveillance tests. 

-  The  tailpipe  emissions  test  results  and  compliance  findings,  including  emissions  tests  under  regulated 
conditions, and tests conducted outside the regulated conditions (e.g. WHVC tests), with a tentative to identify 
the parameters likely to cause an increase of emissions and/or triggering auxiliary emissions strategies (AES) 
or illegal defeat devices.  

-  And  other  verifications  on  on-board  diagnostics  (OBD)  and the  assessment  of  durability, which  cannot  be 
made using the type-approval procedure.  

The  results  show  that  the  tested  HDV  complies  with  the  regulatory  limit  values  as  the  emissions  for  the 
gaseous pollutants (NOx, CO and THC) were below the applicable conformity factors (ISC tests).  

1 

 
 
Acknowledgements 

The authors gratefully acknowledge the colleagues from the Market Surveillance Authority of France for their 
active  support  during  the  project,  including  helpful  and  relevant  comments  during  the  preparation  of  this 
report.  

The authors would also like to thank the JRC Vehicle Emissions Laboratory  (VELA) personnel (Cadario Mauro, 
Forloni Fabrizio, Quarto Riccardo, Trifonova Elitsa, Ungureanu Florentin, Zappia Alessandro, Bonamin Andrea) 
for their contributions, in particular for the organisation of the testing and for conducting the testing activities. 

Authors 

Loos, R., Gioria, R., Selleri, T., Gruening, C., Suarez-Bertoa, R., Bonnel, P. 

2 

 
 
 
1 

Introduction 

Since September 2020 and the entry into force of Regulation 2018/858 (EC, 2018a), a new organisation is in 
force  for  the  approval  and  market  surveillance  (MaSu)  for  automotive  products.  The  main  trigger  for  the 
regulatory update was the so-called Dieselgate. The subsequent investigations and recommendations by the 
European  Parliament  led  to  the  main  contents  of  Regulation  2018/858,  reorganising  the  roles,  instruments 
and responsibilities of the enforcement authorities. The primary objective of the new Regulation is to protect 
the  consumer’s  interest  by  ensuring  that  vehicle  and  components  on  the  EU  market  are  safe  and 
environmental friendly. The new Regulation also endeavours to ensure fair competition by establishing a level 
playing field for all market actors, e.g., by fostering collaboration and exchange of information between the 
enforcement authorities. In that context, the European Commission became a player of the MaSu. To establish 
its functions, the Commission started in  2017 to rely on the Joint Research Centre (JRC) existing  capacities 
and competences until the final setup of facilities and teams completed in 2021. The Commission activities 
will  be  multiple  and  range  from  the  verification  of  vehicles  emissions  and  safety  compliance  to  the 
collaboration  with  national  authorities  to  facilitate  the  exchange  of  information  or  the  peer-review  of 
technical actors. 

In this context, the mainstream activities of the JRC are the MaSu verifications in accordance with Regulation 
2018/858. This includes a  variety of activities comprising  for instance the risk assessment and information 
gathering, the testing and compliance verifications, the peer-review of technical services and some research 
activities. For the compliance verifications, a yearly 80% of the tests is dedicated to “active” MaSu. “Active” is 
opposed  to  “reactive”  testing  and  encompasses  the  vehicles  selected  according  to  the  risk  assessment 
principles and whose list is shared with the EU “Forum for the exchange of information on enforcement”. The 
JRC  has  published  two  MaSu  reports  focused  on  light-duty  vehicles  emissions  testing  (Bonnel,  et  al.,  2022; 
Clairotte, et al., 2020).   

In  addition  to  the  above,  the  JRC  contributes  to  the  In-Service  Conformity  (ISC)  processes  (defined  in 
Regulation 2017/1151 (EC, 2017) last amended by Regulation 2018/1832 (EC, 2018b) for light-duty vehicles; 
for heavy duty vehicles Regulation 2011/582), acting upon request from its policy partner DG GROW or upon 
findings from the EU MaSu testing (Bonnel, et al., 2022). 

3 

 
 
2  Heavy-duty emissions requirements 

2.1 

Introduction 

EU  Regulation  2009/595  (EC,  2009)  establishes  common  technical  requirements  for  the  type-approval  of 
heavy duty vehicles (HDV), engines and replacement parts with regard to their emissions. It requires new HDV 
and engines to comply with new emission limits. In addition, it lays down rules for in-service conformity (ISC) 
of  vehicles  and engines,  durability  of  pollution  control  devices (determination  of  deterioration  factors),  OBD 
systems, measurement of fuel consumption and CO2 emissions, accessibility of vehicle OBD and vehicle repair 
and  maintenance  information.  Regulation  2011/582  (EC,  2011)  implements  and  amends  Regulation 
2009/595. It adopts measures for implementing the use of portable emissions measurement systems (PEMS) 
for verifying the actual in-use emissions and verifying and limiting off-cycle emissions (OCE)1. 

The  emissions  requirements  that  compression  and  positive  ignition  HD  engines and  vehicles  must  fulfil  are 
summarised in Table 1.  The  second  column "compliance demonstration for approval"  shows tests and other 
obligations that manufacturers must perform to get the approval for their vehicles/engines. 

The  following  paragraphs  discuss  the  possibilities  for  verifying  the  requirements  during  the  MaSu  tests.  In 
some  cases,  the  replication  of  the  type  approval  tests  is  impractical,  expensive  or  even  impossible.  In  that 
case,  ad-hoc  methodologies  must  be  proposed,  always  accounting  for  a  risk  assessment  and  therefore 
considering the probabilities of non-compliance, the risks for health, safety, and the environment. 

Table 1: Overview of emissions requirements for HDV or Engines. 

Type of 
Requirement 

Compliance demonstration for approval 

Tailpipe Emissions  WHTC (worldwide harmonised transient driving cycle) 

engine test 

WHSC (worldwide harmonised steady state driving 
cycle) engine test 

PEMS (portable emissions monitoring system) in-
service conformity (ISC) testing of vehicles or engines2 
OCE (off-cycle emissions) 

Functional tests at type approval 

Documentary checks 

Deterioration Factors assigned from Regulation or 
determined through service accumulation 

On-Board 
Diagnostics 

Durability 

Auxiliary Emissions 
Strategies 

Documentary: declaration of AES in the Extended 
Documentation Package 

Crankcase 
Emissions 

Source: JRC, 2023. 

Crankcase emissions test 

1  OCE  are  emissions  that  occur  at  engine  speed/load  points  not  covered  by  the  relevant  certification  test 
(prohibition of defeat strategies). Annex 10 of UN Regulation 49 (UN, 2013) sets out the test procedures for 
testing  off-cycle  emissions  during  type  approval  and  in  actual  use  of  the  vehicle  (e.g.  under  wide  ambient 
conditions). 

2 ISC PEMS testing is laid down in ANNEX II of Regulation 2011/582 (EC, 2011) and Annex 8 of UN Regulation 
49 (UN, 2013). 

4 

 
 
                                                        
 
The WHTC test is a transient engine dynamometer schedule of 1800 s (30 min) duration defined by the global 
technical  regulation  (GTR)  No.  4  developed  by  the  UN  ECE  GRPE  (Working  Party  on  Pollution  and  Energy) 
group. Normalised engine speed and torque values over the WHTC cycle are schematically shown in Figure 1 
(UN, 2013). 

Figure 1: World Harmonised Transient Cycle (WHTC). 

Source: UN, 2013. 

2.2  Tailpipe emissions 

At type approval, the compliance for tailpipe emissions is verified for the engine transient cycle (WHTC), the 
engine stationary cycle (WHSC) and during a PEMS "ISC demonstration test". 

For MaSu or ISC testing, it would be clearly impractical and expensive to extract the engines from the vehicles 
and  to  verify  their  compliance  on  engine  dynamometers.  In  the  mid-2000,  the  PEMS  ISC  procedures  were 
developed with the clear intention to overcome that difficulty. Unlike the RDE test for light-duty vehicles, the 
heavy-duty ISC PEMS test was not really designed to assess the real  driving emissions  performance of the 
vehicle/engine (there was no legal mandate for RDE on HDV) but rather to provide confidence that the engine 
of  a  vehicle  tested  on-road  would  comply  on  the  regulated  certification  cycles  (WHTC,  WHSC)  if  extracted 
from  the  vehicle.  This  approach  was  primarily  dictated  by  the  fact  that  the  emissions  certification  is 
conducted for engines and not for vehicles. Heavy-Duty engines must comply with the emission limit values 
given in Table 2 (EC, 2009; EC, 2011). 

Table 2: Euro VI emissions limits for heavy-duty engines. 

Pollutant 

Limit Values 

WHSC (CI)  WHTC (CI)  WHTC (PI) 

Unit 

CO 

THC 

NMHC 

CH4 

NOx 

NH3 

PM 

PN 

1500 

130 

4000 

160 

400 

10 

10 

460 

10 

10 

4000 

mg/kWh 

mg/kWh 

mg/kWh 

mg/kWh 

mg/kWh  

ppm 

mg/kWh 

160 

500 

460 

10 

10 

8E+11 

6E+11 

6E+11 

#/kWh 

CI: Compression ignition; PI: Positive Ignition 

Source: EC, 2011. 

5 

 
 
 
 
 
 
 
 
 
 
These  emission  limits  apply  also  for  on-road  heavy-duty  PEMS  ISC  tests,  including  the  conformity  factors 
given in Table 3 (ANNEX II of Regulation 2011/582).  

Table 3: Heavy-duty ISC measurement conformity factors (CF). 

Standard 

Gaseous 

Euro VI a/b/c/d 

Euro VI e 

1.5 

1.5 

Source: EC, 2011 and JRC, 2023. 

PN 

n.a. 

1.63 

For  PEMS  ISC  testing,  some  requirements  vary  and  depend  on  the  Euro  VI  stage  (a,b,c,d,e).  The  main 
differences are recapped in Table 4. 

Table 4: Euro VI PEMS ISC requirements. 

Standard 

Trip 
composition 

PN 

included 

Power 
threshold 
(%) 

Payload 
(%) 

Cold start 
included 

Euro VI 
a/b/c 

Euro VI d 

Euro VI e 

Speed based 

First 
acceleration 

method 

First 
acceleration 

method 

Source: EC, 2011 and JRC, 2023. 

no 

no 

20 

20 

50-60 

10-100 

no 

no 

yes 

10 

10-100 

yes 

2.3  World Harmonized Vehicle Cycle (WHVC) 

The World Harmonised Vehicle Cycle (WHVC) is a chassis dynamometer test developed based on the same set 
of  data  used  for  the  development  of  the  World  Harmonised  Transient  Cycle  (WHTC)  engine  test 
(https://dieselnet.com/standards/cycles/whvc.php; 
https://unece.org/DAM/trans/doc/2014/wp29/ECE-TRANS-
WP29-2014-85e.pdf). Vehicle speed over the WHVC test cycle is shown in Figure 2. 

6 

 
 
 
 
Figure 2: World Harmonised Vehicle Cycle (WHVC).  

Source: https://dieselnet.com/standards/cycles/whvc.php. 

The  duration  of  the  WHVC  test  is  1800  s.  The  test  includes  three  segments,  representing  urban,  rural  and 
motorway driving. 

- 

- 

- 

The first 900 seconds represent urban driving with an average speed of 21.3 km/h and a maximum 
speed of 66.2 km/h. This segment includes frequent starts, stops and idling. 

The  following  481  seconds  represent  rural  driving  with  an  average  speed  of  43.6  km/h  and  a 
maximum speed of 75.9 km/h. 

The last 419 seconds are defined as highway driving with a maximum speed of 87.8 km/h. 

2.4  On-Board Diagnostics 

2.4.1  Objectives and definitions 

The present section introduces the definition and the primary requirements for the On-Board Diagnostics. An 
‘On-Board Diagnostic (OBD) system’ means a system on-board a vehicle or engine, which has the capability: 

- 

- 

- 

of detecting malfunctions, affecting the emission performance of the engine system (including after 
treatment systems); and 

of indicating their occurrence by means of an alert system; and 

of identifying the likely area of the malfunction by means of information stored in computer memory 
and communicating that information off-board (EC, 2009); 

The main requirements for the system are as follows: "The OBD system shall be  designed, constructed and 
installed on a vehicle so as to enable it to identify types of deterioration or malfunction over the entire life of 
the vehicle". In addition, "In-use performance related data to be stored (...) shall be made readily available by 
the manufacturer to national authorities and independent operators without any encryption" (EC, 2011). 

2.4.2  OBD testing 

At  type  approval,  the  compliance  for  OBD  is  verified  in  accordance  with  the  requirements  laid  down  in 
Annex X of Regulation 2011/582 and its amendments. 

7 

 
 
 
 
The verification of the OBD compliance includes several aspects: 

- 

- 

- 

The tests to verify that the OBD system properly reacts to deterioration or malfunctions of both the 
engine and the emissions control systems. 

As  the  tests  at  type  approval  cannot  cover  all  in-use  situations  and  should  be  considered  as 
demonstration tests, documentary checks to assess of the functioning of the OBD system. 

The availability of the data stream required for in-use testing. 

For  market  surveillance,  repeating  the  tests  conducted  at  type  approval  is  impractical  and  expensive. 
Should the repetition of the type approval tests be conducted, the OBD system would, in principle, have to be 
verified  for  all  the  monitored  components  required  by  the  regulation  for  different  technologies.  Access  to 
defective  or  deteriorated  components  might  be  difficult  for  MaSu  authorities  and  their  supporting  testing 
services. 

To overcome these difficulties, several types of verifications can be envisaged to check the proper functioning 
of the OBD system. The intention is not to repeat the approval tests but rather to complement them under a 
possibly range of operating conditions wider than the one used for type approval. 

- 

- 

- 

As a first level, the OBD system should be checked with an OBD scan tool to verify the absence of 
errors and the presence of the required in-use data. 

As a second level, the data recorded during all the tests conducted on a single vehicle should include 
the  IUPR  (In-Use  Performance  Ratios)  to  determine  whether  the  IUPR  complies  with  the  applicable 
limits at all times. 

As  a  third  and  more  advanced  level,  the  simulation  of  malfunction  of  components,  engine 
management or emission control system can be added to the testing. This method should be applied 
on  a  case-by-case  basis, possibly  based  on  evidence  gathered  during  the  risk assessment. For this 
purpose, appropriate technical guidance shall be developed. 

2.5  Detection of Auxiliary Emissions Strategies (AES) 

2.5.1  Type approval requirements 

The EU HD Regulation (2009/595) provide definitions and generic obligations for defeat devices (DD) and the 
possible  use  of  AES.  In  addition,  “for  the  approval  authorities  to  be  able  to  assess  the  proper  use  of  AES, 
taking  into  account  the  prohibition  of  defeat  devices",  the  manufacturers  have  the  obligation  to  provide  an 
extended documentation package. 

2.5.2  Market surveillance verifications 

The assessment methodology used and presented in this report is only one of the methodologies included in 
the Guidance proposed by the Commission to the Forum for the Exchange of Information on Enforcement. The 
methodologies  in  the  Guidance,  including  the  one  below,  will  be  subject  to  a  regular  review  by  the  Forum. 
Using  the  latest  emissions  data  collected  by  the  participating  authorities,  the  review  shall  assess  the 
suitability of the methodology and/or its emissions thresholds. 

In line with the definitions for defeat devices, two distinct cases are possible: 

- 

- 

“Mainstream  Defeat  Devices”:  Devices/strategies  that  act  outside  the  regulated  boundaries  and 
triggered  by  the  vehicle  operating  conditions  other  than  its  localisation  (expressed  e.g.  as  ambient 
temperature, altitude and driving dynamics ranges) of the current legislative tests or;  

“Test  detection  Defeat  Devices”:  Devices/strategies  triggered  by  the  PEMS  test  equipment  (e.g., 
backpressure increase at the tailpipe, connection of a data recorder on the  OBD port) or the vehicle 
localisation (i.e., anything informing the vehicle that it is being tested on-road for tailpipe emissions). 

8 

 
 
The laboratory tests are not  considered  for that case, as the concern is the  vehicles environmental 
performance under real driving conditions and as vehicles are tested using “dyno modes”. 

The present work addresses only case a) for which the vehicles are tested under variations of the regulated 
testing conditions referred to as "modalities" to detect the presence of defeat devices. The set of modalities is 
not fixed but instead kept open and may be varied for the different vehicles. 

MaSu  testing  shall  include  testing  the  vehicle  with  the  regulatory  methodologies  (for  HDV,  a  PEMS  test 
conducted according to the ISC rules). This step ensures that the vehicle/engine - when compliant - is free of 
malfunctioning, bad maintenance or other similar issues which would increase unduly the level of emissions. 
The  “modalities”  are  sets  of  testing  conditions  under  which  increases  in  emissions  and  therefore  defeat 
devices/strategies might be observed. For tests lasting between 30 minutes (typical laboratory duration) and a 
maximum  of  two  hours  (light-duty)  or  even  three  hours  (heavy-duty),  the  effect  of  an  emissions  increase 
caused by an AES can be observed if: 

- 

- 

The AES/DD is activated for a sufficient duration; 

The corresponding emissions increase is not statistically diluted over the total emissions of the entire 
test. 

The  vehicle  tailpipe  emissions  over  the  entire  test  (or  section  of  the  test)  are  be  expressed  as  "Emissions 
Ratios"  (ER).  The  ER  is  defined  as the  vehicle  emissions  during  the  test  divided  by  the  applicable  emissions 
limit.  For  light-duty  vehicles,  the  ER  is  calculated  considering  the  provisions  of  the  applicable  version  of 
Regulation (EU) 2017/1151 (EC, 2017). For the modalities under non-regulated conditions, the corrections for 
extended  conditions  and/or  CO2  were  not  applied.  For  the  pollutants  without  conformity  factors  and 
unregulated  under  real  driving  conditions  (e.g.  CO  for  RDE-LDV  tests),  the  on-road  emissions  were  simply 
divided by the applicable limit. In such a case, the calculated ER is not used to verify the vehicle compliance 
but rather to assess whether the emissions are anomalous and if an investigation should be triggered. 

In  this  work,  the  ER  calculated  for  unregulated  conditions  were  compared  to  emissions  thresholds  and 
investigations on AES were prioritised according to the following values: 

- 

- 

- 

ER < 1.3 Low priority 

1.3 < ER < 2.5 Medium priority 

ER > 2.5 High priority 

The above thresholds are greater than 1 but the adopted decision rules were – by no means – a way to ignore 
emissions  exceeding  the  limits  under  non-regulated  conditions.  The  primary  objective  was  to  detect  the 
presence of AES and to prioritise investigations based on their environmental impact. 

2.6  Durability 

2.6.1  Type approval requirements and methods 

At  type  approval,  the  durability  Test  (Verifying  the  durability  of  engine  systems)  according  to  Regulation 
2009/595 (UN/ECE Reg. 49 – Annex 7; UN, 2013) is performed during a service accumulation schedule  that 
includes periodic testing for gaseous and particulate emissions over the WHTC and WHSC engine  cycles. The 
service  accumulation  schedule  depends  on  the  vehicle  category  in  which  the  engine  will  be  installed  and 
ranges  from  160.000  km  to  233.000  km.  A  linear  fit  is  applied  to  the  measured  data  points  for  each 
pollutant.  Using  the  linear  fit,  the  respective  multiplicative  deterioration  factor  (DF)  is  derived  from  the 
extrapolated  emission  at  the  useful  life  divided  by  the  emission  at  the  start  of  the  service  accumulation 
schedule. For an additive DF, the emission differences are calculated at these two points of the linear fit. 

9 

 
 
 
 
 
Table 5: Vehicle useful life for the durability requirement of emission control systems according to UN-ECE R49, Article 
5.4. The sooner of mileage and vehicle age is considered.  

Vehicle type 

Useful life / 
mileage 

Useful life / 
vehicle age 

M1, N1, M2 

160.000 km 

5 years 

N2, N3 with mass  16 tons 

300.000 km 

6 years 

M3 Class I, II and A 

M3 Class B  7.5 tons 

N3 > 16 tons 

M3 Class III 

M3 Class B > 7.5 tons 

Source: UN, 2013. 

700.000 km 

7 years 

As  alternative,  assigned  multiplicative  deterioration  factors  can  be  used  without  performing  a  service 
accumulation schedule; they are listed in Table 6. 

Table 6: Assigned multiplicative deterioration factors according to UN-ECE R49 – Annex 7, for both WHTC and WHSC test 
cycles.  

CO  THC1  NMHC2  CH4

2  NOx  NH3  PM  PN 

1.3  1.3 

1.4 

1.4 

1.15  1.0  1.05  1.0 

1applies to compression engines only, 2to positive ignition engines. 

Source: UN, 2013. 

The  engines  now  shall  meet  the  respective  emission  limits  for  each  pollutant  after  the  application  of  the 
deterioration factors to the results of the engine type approval emissions tests. This procedure is thus aimed 
to ensure the durability of the emission control systems over the useful life of the vehicle, which is category 
dependent and listed in Table 5.  

During the vehicle useful life, the durability compliance is verified: 

-  Via  In-Service  Conformity  Tests.  Engines  shall  comply  with  emissions  limits  for  a  mileage 
depending on the vehicle type where they are built into as described in Table 5 above. For ISC testing, 
PEMS  tests  shall  be  performed  as  described  in  UN-ECE  R49,  Annex  8  and  conformity  factors  per 
pollutant not exceeded.  

-  Within the market surveillance activities in accordance with Regulation 2018/858, the durability 
should be assessed with a mileage of up to the vehicle’s useful life. However, for practical and costs 
reasons, some procedures used for type approval cannot be applied during the MaSu assessment. For 
instance,  under  current  and  foreseeable  future  conditions,  repeating  the  service  accumulation 
schedule of the type approval procedure is out of scope. Similar to LDV, an alternative methodology 
is therefore proposed and used by the JRC to assess the durability of emission control systems (or 
risks associated to the durability). 

2.6.2  Methodology for durability assessment 

To assess the durability of emission control systems, the emissions are measured  and deterioration factors 
applied as described below. 

- 

The emissions from PEMS-ISC or WHVC tests are measured. The latter ones are not required at type 
approval, but possible to be performed during MaSu. 

10 

 
 
- 

- 

For  emissions  above  the  regulatory  limits  taking  the  ISC  conformity  factors  (1.5  for  gaseous 
pollutants)  into  account,  the  vehicle  is  found  to  not  comply  with  the  Regulation,  including  the 
durability requirement, in the context of MaSu. 

Vehicles  exhibiting  emissions  below  the  regulatory  limits  are  treated  as  follows  according  to  their 
present mileage. 

 

 

For  vehicles  with  a  mileage  below  8.000  km  (which  is  an  arbitrary  choice  to  stabilise  new 
engines – should be between 60 and 125 hours), the DF from the type approval for the specific 
vehicle are directly applied to the measured emissions. 

For  vehicles  with  a  mileage  above  8.000  km,  the  DF  are  linearly  interpolated  at  the  vehicle’s 
present  mileage  to  obtain  their  type  approval  values  at  8.000  km  and  become  1  for 
multiplicative and 0 for additive DF at the mileage of the useful life (MUL, see Table 5). These 
interpolated  DF  are  applied  to  the  measured  emissions.  The  interpolated  deterioration  factor, 
DFint, is thus calculated by: 

𝐷𝐹𝑖𝑛𝑡 = 𝐷𝐹 × (1 −

𝑀𝑖𝑙𝑒𝑎𝑔𝑒 − 8.000
MUL − 8.000

) + 𝑖  ×  

𝑀𝑖𝑙𝑒𝑎𝑔𝑒 − 8.000
MUL − 8.000

𝑤𝑖𝑡ℎ 𝑖  = 1 𝑓𝑜𝑟 𝑚𝑢𝑙𝑡𝑖𝑝𝑙𝑖𝑐𝑎𝑡𝑖𝑣𝑒 𝑎𝑛𝑑 𝑖 = 0 𝑓𝑜𝑟 𝑎𝑑𝑑𝑖𝑡𝑖𝑣𝑒 𝐷𝐹𝑠 

(1) 

DF  are  applied  to  each  single  emissions  test  in  order  to  obtain  emissions  projected  to  the  mileage  of  the 
useful life and the projected emissions are averaged3 and Risk Areas are defined according to the respective 
Durability Ratio (DR) = projected emission average / (emission limit * ISC conformity factor): 

- 

- 

- 

red (0.9 ≤ DR),  

orange (0.8 ≤ DR < 0.9), 

green (DR < 0.8). 

The  Risk  Areas  limits  should  be  reviewed  according  to  the  experience  that  will  be  gained  applying  the 
proposed methodology. 

3 For all emissions tests conducted on a vehicle 

11 

 
 
 
 
 
                                                        
 
2.7  Overview of market surveillance tests 

Table  7  provides  an  overview  for  the  testing  approaches  that  might  be  adopted  for  MaSu.  The  approaches 
indicated  as  "being  assessed"  are  addressed  by  the  participating  authorities  and  the  JRC  and  are  always 
subject to discussion, approval and review by the Forum for the exchange of information on enforcement. 

Table 7: Testing options for MaSu verifications. 

Requirement 

Market surveillance tests 

Remarks 

Tailpipe Emissions 

HDV: PEMS ISC test 

On-Board 
Diagnostics 

OBD scan tool 

And/or Presence and quality of 
mandatory data 

ANNEX II of 
Regulation 2011/582 

Simplified 
approaches being 
assessed 

And/or In-Use Performance Ratios (IUPR) 
recording 

And/or software analysis 

Durability 

Estimation of degradation over lifetime + 
Risk-based approach 

Simplified approach 
being assessed 

Auxiliary Emissions 
Strategies 

Tests under non-regulated conditions 

Guidance document 

Verification of AES declarations in the 
Extended Documentation Package 

Continuous 
improvement 

Source: JRC, 2023. 

And/or software analysis 

12 

 
 
3  Tailpipe emissions testing 

3.1  Test vehicle 

Figure 3 shows a picture of the tested N2 HDV; Table 8 gives the vehicle and Table 9 the engine 
characteristics.   

Figure 3: Picture of the HDV tested.  

Source: JRC, 2023. 

Table 8: Test vehicle characteristics. 

Vehicle Brand 

Renault Trucks 

Type 

Vehicle Category 

MCDA2C 

N2 

Emissions standard 

Euro VI Step D 

Maximum Laden Mass 

Fuel 

VIN 

Model year 

WVTA 

12 tons 

Diesel 

VF640J560KB012332 

2019 

e2*2007/46*0135*26 

Emissions TA number 

595/2009*2018/932D 

Mileage 

17577 km 

Source: JRC, 2023. 

13 

 
 
 
 
 
 
 
 
Table 9: Engine characteristics. 

Engine Manufacturer 

Volvo Powertrain 

Engine code 

DTI 5 210 EUVI 

Cylinders 

Ignition 

4 in line 

Compression ignition with turbocharger 

Emissions control 

EGR, DOC, DPF, SCR, ASC 

Displacement 

Power 

Maximum Torque 

Transmission type 

Source: JRC, 2023. 

5132 cm3 

158 kW 

819 N.m 

Automatic 

3.2  Vehicle reception and examination 

To ensure that the test and inspection activities are performed on properly maintained and used vehicles, the 
test  vehicle  was  examined  using  a  checklist  for  vehicle  examination  and  maintenance,  which  meets  the 
requirements  and  contents  of  Appendix  1  (Criteria  for  vehicle  selection  and  failed  vehicles  decision)  of 
Regulation 2018/1832 and included for instance: 

- 

- 

- 

Vehicle owner interview; 

Physical examination of the vehicle; 

Control of the documentation including the maintenance documents. 

3.3  Emissions tests under regulated conditions 

3.3.1  Testing conditions 

The HDV was tested on the road under regulated conditions fulfilling the Euro VI In-Service Conformity (ISC) 
requirements. The tests (hereinafter ISC) were performed using three different payloads, namely: 10%, 55% 
and 100%. Table 10 shows the conditions, work and different share of urban, rural and motorway time and 
share operations.  

Table 10: Conditions, work and time shares for the PEMS ISC tests. 

Test 

Payload 
(%) 

Average 
ambient 
temp. (°C) 

Work 
(kWh) 

Duration 
(min) 

(without 
cold start) 

Urban 
time 
share 
(%) 

Rural 
time 
share 
(%) 

Motorway 
time share 
(%) 

ISC_1_55% 

ISC_2_55% 

ISC_3_55% 

ISC_1_10% 

55 

55 

55 

10 

ISC_1_100%  100 

ISC_2_100%  100 

Min. required 

Max. 
permitted 

14.7 

14.4 

14.4 

13.4 

14.2 

14.1 

136.2 

147.7 

143.1 

139.8 

149.5 

136.0 

84.41 

84.15 

94.26 

73.01 

92.22 

72.93 

56.72 (a) 

113.44 (b) 

44.7 

49.2 

48.9 

46.3 

46.1 

46.2 

40 

50 

22.3 

21.9 

1.9 

22.1 

23.8 

21.4 

20 

30 

33.0 

28.9 

49.2 

31.6 

30.1 

32.4 

25 

35 

(a) 4 times the engine work on WHTC; (b) 8 times the engine work on WHTC 

Source: JRC, 2023. 

14 

 
 
 
 
 
 
 
 
 
3.3.2  Test results 

Figure 4 shows the speed profile of the ISC route used (test duration 150 min), which fulfils the requirements 
applicable to Euro VI D Class N2 heavy-duty vehicles. During the on-road tests, emissions of  NOx, CO, THC, 
CH4 and CO2 were measured using a portable emissions measurement system (PEMS). 

Figure 4: ISC test speed profile.  

Source: JRC, 2023. 

According  to  the  rules  in  force  for  ISC  regulatory  data  processing  (Appendix  1  of  ANNEX  II  of  Regulation 
2011/582), the emissions are calculated using moving averaging windows and the 90% cumulative percentile 
value for a given regulated pollutant. The 90% cumulative percentile is determined for the valid windows, i.e. 
the ones for which the power exceeds the threshold of 20% of maximum engine power. 

The emissions in mg/kWh were calculated using both the work and CO2 based moving averaging windows, and 
the results were identical (not shown). The emissions are divided by the corresponding engine limit (Table 2) 
and  these  emission  ratios  (ER)  (called  as  well  “conformity  factor”  in  Regulation  2011/582)  are  checked 
against the conformity factor CF (1.5) (Table 3).   

As shown in Table 11, the emissions for the gaseous pollutants (NOx, CO and THC) were below the CF for all 
the valid ISC tests.  For CO and THC, very low emissions  were measured during all the tests.  NOx emissions 
were higher, but still below the CF. 

It must be noted that PN measurements are not formally required for PEMS testing of Euro VI-d engines (it 
applies from Euro VI-e only). Within such a pilot/research activity, it would have been a valuable addition but 
PEMS PN instruments were not available when the experiments were conducted.  

15 

0.010.020.030.040.050.060.070.080.090.0100.00100020003000400050006000700080009000Vehicle Speed (km/h)Tme (s) 
 
 
 
 
 
 
 
 
Table  11:  Gaseous  pollutants  (NOx,  CO  and  THC)  emission  ratios  (ER)  for  the  ISC  tests  compared  with  the  conformity 
factor (CF).  

Test 

NOx 

CO 

THC 

ISC_1_55% 

0.673 

0.024 

0.060 

ISC_2_55% 

0.474 

0.027 

0.039 

ISC_3_55% 

0.587 

0.029 

0.040 

ISC_1_10% 

0.566 

0.020 

0.048 

ISC_1_100% 

0.342 

0.030 

0.041 

ISC_2_100% 

0.442 

0.031 

0.057 

Conformity 
Factor (CF) 

Source: JRC, 2023. 

1.5 

1.5 

1.5 

3.4  Emissions outside the regulated conditions 

3.4.1  Testing conditions 

According to the recommended methodology, the vehicle must be tested under a series of conditions falling 
outside  the  regulated  boundaries  to  search  for  the  presence  of  Auxiliary  Emissions  Strategies  (or  Defeat 
Devices) exhibiting a high environmental impact. The selected testing conditions included on-road testing and 
in-laboratory chassis dynamometer testing. To this end, the emissions for  two tests/operating conditions for 
which only one parameter is changed were compared. 

The on-road tests not fulfilling the regulatory requirements (Table 12) included: 

-  One  real  world  driving  (hereinafter  RDE)  route  that  does  not  include  boundaries  for  the  vehicle 
speed (higher vehicle speed was allowed on the highway). Moreover, the test did not strictly follow 
the  urban-rural-motorway sequence required by the regulatory procedure,  but included rural and 
urban driving after the motorway. 

-  One route focused on highway operation (hereinafter LONG). 

The operation profiles of these routes were selected to assess potential changes once the predetermined 
sequence prescribed for the ISC was not followed. The tests performed using the RDE route were conducted 
with 55% payload.  

Table 12 illustrates the shares of urban, rural and motorway operations for the RDE and the LONG routes. As 
for the ISC tests, emissions of NOx, CO, hydrocarbons and CH4 and CO2 were measured using PEMS. 

Table 12: Conditions of non-regulatory on-road tests.  

Test 

Payload 
(%) 

Average 
ambient 
temp. 
(°C) 

Duration 
(min) 
(without 
cold start) 

Work (kWh)  Urban 

time share 
(%) 

RDE_1_55% 

55 

LONG_1_55%  55 

15.5 

14.0 

136.0 

200.7 

83.98 

149.87 

Min. required 

Max. 
permitted 

56.72 (a) 

113.44 (b) 

53.3 

28.8 

40 

50 

(a) 4 times the engine work on WHTC; (b) 8 times the engine work on WHTC 

Source: JRC, 2023. 

Rural 
time 
share 
(%) 

20.2 

14.2 

20 

30 

Motorway 
time share 
(%) 

26.5 

57.0 

25 

35 

16 

 
 
 
 
 
 
 
 
Table 13  gives the work, duration, average speed, and ambient temperature for the  urban, rural, motorway 
shares and total test for the RDE, LONG, and WHVC tests at different ambient temperatures.  

Table 13: Non-regulatory on-road and laboratory WHVC tests. 

Test 

Section 

Work 
(kWh) 

Duration 

(min) 

Average 
speed 
(km/h) 

RDE_1_55% 

Total 

83.98 

136.0 

Urban 

30.16 

72.5 

Rural 

18.57 

27.5 

Motorway 

35.26 

36.0 

LONG_1_55% 

Total 

149.8 

200.7 

Urban 

18.66 

57.7 

Rural 

20.23 

28.5 

Motorway 

110.9 

114.5 

WHVC 0°C 

Total 

15.73 

30.7 

WHVC 20°C 

Total 

14.69 

30.0 

WHVC 35°C 

Total 

14.44 

30.4 

WHVC -7°C 

Total 

16.08 

30.4 

WHVC -20°C 

Total 

16.33 

30.5 

Source: JRC, 2023. 

3.4.2  Test results 

52.8 

30.4 

65.1 

88.6 

66.3 

22.5 

68.8 

87.7 

39.2 

40.1 

39.6 

39.6 

39.6 

Ambient 
temp. 

Cold/
Hot 

AES Modality 
(Y/N - 
Category) 

(°C) 

15.5 

14.9 

15.7 

16.7 

14.0 

13.0 

14.4 

14.3 

0 

20 

35 

-7 

-20 

Y/2 

Y/2 

Y/2 

Y/2 

Y/2 

Y/2 

Y/2 

Y/2 

Y/2 

Y/2 

Y/2 

Y/2 

Cold 

Cold 

Hot 

Cold 

Cold 

The  results  of  the  non-regulated  tests  for  the  gaseous  pollutants  NOT  using  the  regulatory  calculation 
method, i.e. the uncorrected emissions for the considered test and without exclusions (whole ISC or WHVC test 
or sub-sections of that test, i.e., urban, rural, motorway) are given in Table 14. 

The emissions are presented as emissions ratios (ER), i.e., emissions in mg/kWh divided by the applicable limit 
(of the WHTC engine test) × CF (only for on-road tests, not for WHVC tests). Then, the emissions are checked 
against the thresholds proposed in the Guidance (ER < 1.3: Low priority; 1.3 < ER < 2.5: Medium priority; ER > 
2.5: High priority).  

The NOx emissions of the WHVC tests were below the threshold of 1.3 for the hot tests, but above (red) for 
the cold tests. 

17 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Table 14: Gaseous pollutants emission ratios (ER) (×CF for on-road tests) for RDE, LONG, and WHVC tests. 

Test 

RDE_1_55%_Total 

RDE_1_55%_Urban 

RDE_1_55%_Rural 

NOx 

0.65 

1.56 

0.19 

RDE_1_55%_Motorway 

0.11 

LONG_1_55%_Total 

LONG_1_55%_Urban 

LONG_1_55%_Rural 

0.35 

2.17 

0.13 

LONG_1_55%_Motorway  0.09 

CO 

0.04 

0.06 

0.03 

0.02 

0.02 

0.06 

0.02 

0.02 

THC 

0.05 

0.09 

0.05 

0.02 

0.05 

0.12 

0.05 

0.04 

WHVC 0°C cold (hot) 

2.27 (0.41) 

0.048 (0.003) 

0.049 (0.028) 

WHVC 20°C cold (hot) 

1.85 (0.32) 

0.119 (0.003) 

0.041 (0.037) 

WHVC 35°C cold (hot) 

2.46 (0.35) 

0.030 (0.003) 

0.024 (0.023) 

WHVC -7°C cold (hot) 

3.75 (0.68) 

0.071 (0.002) 

0.065 (0.033) 

WHVC -20°C cold (hot) 

4.75 (1.17) 

0.193 (0.014) 

0.176 (0.062) 

Threshold 1 

Threshold 2 

Source: JRC, 2023. 

1.3 

2.5 

1.3 

2.5 

1.3 

2.5 

A  clear (well  known; e.g.  Giechaskiel  et  al.,  2022)  temperature  effect  on  the  emissions can  be  seen  for  the 
WHVC tests. The lowest NOx emissions were observed at 20°C, and higher emissions measured at 0°C, 35°C, -
7°C,  and  -20°C,  respectively.  Moreover,  much  higher  NOx  emissions  were  measured  for  cold  (coolant 
temperature < 30°C) than for hot tests (coolant temperature above 70°C) (Table 14).  

The increase of NOx emissions over time on the WHVC is show in Figure 5. The differences between the four 
plotted temperatures (-20°C, -7°C, 0°C, 20°C) is a result of the combined effect of: 

- 

- 

"Physical" effects: the vehicle conditioning influences the time required for the engine and after-
treatment  to  warm-up  (for  the  engine  coolant  temperature)  and  for  some  after-treatment 
technologies to reach significant abatement levels (exhaust temperature); 

Effects of the parameters of the emissions control strategies: activation/deactivation of SCR. 

For understanding the effect of emissions control strategies upon the emissions and to understand whether it 
matches with the strategies declared by the manufacturer, the abovementioned plots should be accompanied 
at least by the (cumulative) rate of the EGR and SCR urea injection. These parameters were not available for 
that vehicle but one can easily guess the difference in urea injection between  -7°C and -20°C. For the latter 
and  according  to  a  probable  temperature  protection  AES  of  the  injection  system,  the  urea  is  not  injected 
during the whole test, contrary to the test at -7°C, for which it probably starts around 500 seconds. 

18 

 
 
 
 
 
 
Figure 5: Effect of WHVC test temperature upon cumulative NOx emissions. 

Source: JRC, 2023. 

Figure 6: Effect of WHVC test temperature upon engine coolant temperature.  

Source: JRC, 2023. 

19 

051015202530354001020304050607080901000200400600800100012001400160018002000Cumul NOx [g]Vehicle speed [km/h]Time [s]CUMULATIVE NOx EMISSIONSVehicle speed-20degC_Cold-7degC_Cold0degC_Cold20degC_Cold-2002040608010001020304050607080901000200400600800100012001400160018002000Coolant Temperature [degC]Vehicle speed [km/h]Time [s]COOLANT TEMPERATUREVehicle speed-7degC_Cold0degC_Cold20degC_Cold-20degC_Cold 
 
 
 
 
3.5  Effect of a single parameter and relative analysis 

3.5.1 

Introduction 

The approach used in section 3.4 to search for Auxiliary Emissions Strategies is “absolute” and makes use of 
fixed thresholds, whose main goal is to trigger attention and potential investigations when high emissions are 
measured for certain operating conditions (modalities). In the present paragraph, the results are analysed in a 
relative  manner,  i.e.,  comparing  two  modalities  for  which  only  one  parameter  was  changed  to  determine 
whether the change of value for that parameter triggers a modification of the emissions strategy. The cases 
covered during these tests are the following: 

- 

- 

- 

The presence (or absence) of a data logger on the OBD port: such a case is designed to determine 
whether  the  vehicle  detects  a  PEMS  emissions  test  with  a  data  logger.  This  would  be  a  “case  B” 
defeat device if the emissions strategy changes; 

A low  AdBlue level: in this situation,  it is permitted to reduce the engine power through the  vehicle 
electronics but not to modify the emissions strategy; 

The  driving  cycle:  the  reference  cycle  (WHVC)  is  driven  in  a  “reverse”  mode,  all  other  parameters 
being equal, to determine whether the driving cycle triggers a modification of the emissions strategy; 
this would be a cycle detection defeat device. 

3.5.2  Data logger on OBD port 

WHVC  hot  tests  were  performed  at  20°C  with  the  OBD  port  connected  and  with  OBD  disconnected.  OBD 
connection is essential for heavy-duty testing as the work performed during the test is calculated using data 
coming through this channel. Hence, being connected to the OBD is a potential indication of the vehicle being 
tested.  As  illustrated  in  Table  15  and  Figure  7,  NOx  emissions  during  the  hot  operation  of  the  WHVC  were 
relatively low in both cases with actually lower NOx for the test where the OBD was not connected. Thus, no 
OBD logger defeat device was detected.  

Table 15: Vehicle emissions in (mg/kWh) with and without OBD connected. “Raw data” for THC, and diluted data for NOx 
and CO.  

Test 

NOx 

CO 

THC 

With OBD connected 

172 

Without OBD 

122 

Source: JRC, 2023. 

68 

79 

6 

2 

20 

 
 
 
 
 
 
Figure 7: OBD logger; NOx, CO, and THC emissions with and without OBD connected. 

OBD Logger

h
W
k
/
g
m

200,0

150,0

100,0

50,0

0,0

NOx

CO

THC

With OBD connected

Without OBD

Source: JRC, 2023. 

3.5.3  Driving cycle 

A normal WHVC with the sequence urban-rural-motorway was compared with a reversed cycle. A cold WHVC 
was combined with a hot WHVC, and the emission results for the sequence WHVC(cold) + WHVC(hot) (urban, 
rural, motorway  + urban,  rural, motorway) and the  reverse cycle (urban,  rural, motorway + motorway, rural, 
urban) are shown in Table 16 and Figure 8. A change in the phase sequence of a hot test should not result in 
a disproportionate difference on the emissions. Indeed, the emissions measured were in good agreement for 
both tested conditions. 

Table 16: WHVC tests compared with reverse WHVC tests. Vehicle emissions in (mg/kWh). 

Test 

NOx 

CO 

THC 

WHVC(cold) + WHVC(hot) 

504 

246 

Reverse WHVC(cold) + 
WHVC(hot) 

437 

321 

6 

4 

Source: JRC, 2023. 

21 

 
 
 
 
 
 
Figure 8: Comparison of normal and reverse driving cycle.  

Driving cycle

600,0

500,0

h
W
k
/
g
m

400,0

300,0

200,0

100,0

0,0

NOx

CO

THC

WHVC(cold) + WHVC(hot)

Reverse WHVC(cold) + WHVC(hot)

Source: JRC, 2023. 

3.5.4  AdBlue and Fuel level 

Finally, a possible influence of the AdBlue and fuel levels on the emission performance was investigated. The 
NOx emissions for low AdBlue level vs normal and low fuel level vs normal are shown in Figure 9. Although 
the  NOx  emissions  during  the  WHVCcold  varied  slightly  for  the  test  performed  with  low  fuel  level  (FuelLow) 
from those obtained during the test at normal and low AdBlue level (AdBlueLow) conditions, they were still in 
good agreement. Moreover, the emissions during the WHVChot were comparable for all the three conditions.  

Figure 9: NOx emissions for WHVC tests (normal, low AdBlue, and low Fuel level). 

NOx emission diluted (Tair=20°C)

Cold start

Hot start

]
h
W
k
/
g
[

1

0,8

0,6

0,4

0,2

0

Normal

AdBlueLOW

FuelLOW

Source: JRC, 2023. 

22 

 
 
 
 
 
 
The  CO  emissions  for  the  WHVCcold  test  with  low  AdBlue  level  were  however  considerably  lower  than  with 
normal level (Figure 10).   

Figure 10: CO emissions for WHVC tests (normal, low AdBlue, and low Fuel level). 

CO emission diluted (Tair=20°C)

Cold start

Hot start

]
h
W
k
/
g
[

0,7
0,6
0,5
0,4
0,3
0,2
0,1
0

Normal

AdBlueLOW

FuelLOW

Source: JRC, 2023. 

The THC emissions of all tests (normal, low AdBlue, low fuel level) were nearly identical (Figure 11). 

Figure 11: THC emissions for WHVC tests (normal, low AdBlue, and low Fuel level). 

THC emission diluted (Tair=20°C)

Cold start

Hot start

]
h
W
k
/
g
[

0,2

0,15

0,1

0,05

0

Source: JRC, 2023. 

Normal

AdBlueLOW

FuelLOW

23 

 
 
 
 
 
 
4  Other verifications 

4.1  On-Board Diagnostics 

OBD  scan  is  part  of  the  vehicle  acceptance  procedure.  The  actions  performed  are  listed  in  the  “Criteria  for 
vehicle  selection  and  failed  vehicles  decision”  laid  down  in  the  Appendix  1  of  ANNEX  II  to  Regulation 
2018/1832.  The  OBD  scan  is  performed  with  the  help  of  a  BOSCH  system  (DCU100  tablet,  ESI[tronic]  2.0 
Software and KTS540 OBD module). In line with Regulation 2018/1832, the OBD scan tool is employed in the 
scan modes 7 and 9. 

The following data are recorded before and after each emission test campaign, as defined in Appendix 1 to 
Regulation  2018/1832  (Functional  Aspects  of  On-Board  Diagnostic  (OBD)  Systems)  Par.  6.5.3.4  and  Par. 
6.5.3.2. 

-  MessageCount VIN 

- 

Vehicle Identification Number 

-  MessageCount CALID 

- 

Calibration Identifications 

-  MessageCount CVN 

- 

Calibration Verification Numbers 

-  MessageCount IPT 

- 

In-use Performance Tracking for spark ignition engines 

-  OBD Monitoring Conditions Encountered Counts 

- 

- 

- 

- 

- 

Ignition Counter 

Catalyst Monitor Completion Counts Bank 1 

Catalyst Monitor Conditions Encountered Counts Bank 1 

Catalyst Monitor Completion Counts Bank 2 

Catalyst Monitor Conditions Encountered Counts Bank 2 

-  Oxygen Sensor Monitor Completion Counts Bank 1 

-  Oxygen Sensor Monitor Conditions Encountered Counts Bank 1 

-  Oxygen Sensor Monitor Completion Counts Bank 2 

-  Oxygen Sensor Monitor Conditions Encountered Counts Bank 2 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

EGR and/or VVT Monitor Completion Condition Counts 

EGR and/or VVT Monitor Conditions Encountered Counts 

AIR Monitor Completion Condition Counts (Secondary Air) 

AIR Monitor Conditions Encountered Counts (Secondary Air) 

EVAP Monitor Completion Condition Counts 

EVAP Monitor Conditions Encountered Counts 

Secondary Oxygen Sensor Monitor Completion Counts Bank 1 

Secondary Oxygen Sensor Monitor Conditions Encountered Counts Bank 1 

Secondary Oxygen Sensor Monitor Completion Counts Bank 2 

Secondary Oxygen Sensor Monitor Conditions Encountered Counts Bank 2 

Air Fuel Ratio Imbalance Monitor Completion Counts Bank 1 

Air Fuel Ratio Imbalance Monitor Conditions Encountered Counts Bank 1 

24 

 
- 

- 

- 

- 

- 

- 

Air Fuel Ratio Imbalance Monitor Completion Counts Bank 2 

Air Fuel Ratio Imbalance Monitor Conditions Encountered Counts Bank 2 

Particulate Filter Monitor Completion Counts Bank 1 

Particulate Filter Monitor Conditions Encountered Counts Bank 1 

Particulate Filter Monitor Completion Counts Bank 2 

Particulate Filter Monitor Conditions Encountered Counts Bank 2 

-  MessageCount ECUNAME 

- 

ECUNAME 

During every cycle of the campaign at least the basic diagnostic data are recorded as specified in Appendix 1 
to Regulation 2018/1832, 6.5.3.4 and Par. 6.5.3.2: diagnostic trouble codes, engine coolant temperature, fuel 
control  system  status  (closed-loop,  open-loop,  other),  fuel  trim,  ignition  timing  advance,  intake  air 
temperature,  manifold  air  pressure,  air  flow  rate,  engine  speed,  throttle  position  sensor  output  value, 
secondary  air  status  (upstream,  downstream  or  atmosphere),  calculated  load  value,  vehicle  speed  and  fuel 
pressure. If available, also all the other PIDs related to this regulation are recorded. 

The  OBD  compliance  verifications  make  sure  that  all  standard  parameters  defined  by  SAE  J1979  /  ISO 
15031-5 are provided in every vehicle tested for market surveillance compliance. 

4.2  Assessment of durability 

The  risk  of  non-complying  with  the  durability  requirements  has  been  assessed  in  accordance  with  the 
methodology developed in paragraph 2.6. 

The  Durability  Ratios (DRs)  are  calculated  using  the  interpolated  deterioration  factors  for  the  vehicle  at  the 
present  mileage  of  17577  km.  As  vehicle  ageing  throughout  the  tests  done  at  the  JRC  was  negligible 
compared  to  the  300  000  km  of  the  vehicle  type’s  mileage  of  useful  life,  a  single  set  of  DFs  is  used 
throughout the tests. With the vehicle’s mileage, the following interpolated Deterioration Factors (DFs) (Table 
17) are calculated according to Equation (1). 

Table 17: Assigned and interpolated Deterioration Factors at the vehicles present mileage. 

CO 

THC  NMHC  CH4  NOx  NH3  PM  PN 

DFass  1.3 

1.3 

1.4 

1.4 

1.15  1.0  1.05  1.0 

DFint  1.29  1.29  1.39 

1.39  1.15  1.0  1.05  1.0 

Source: JRC, 2023. 

In the assessment for a reproducible emissions measurement of the whole vehicle that is reasonably similar 
to the engine test at type approval with regards to the behaviour of the engine, the WHVC test performed at 
20°C has been identified (see Table 13 & Table 14 for ERhot & ERcold). These WHVCs have been performed as 
both cold and hot start tests. Using the hot and cold start weighing factors of 0.86 and 0.14, respectively, a 
combined emission ratio for WHVC, multiplied by the respective DFint can be calculated according to formula 
(2): 

𝐷𝑅𝑊𝐻𝑉𝐶 = 𝐷𝐹𝑖𝑛𝑡 × (0.86 × 𝐸𝑅ℎ𝑜𝑡 + 0.14 × 𝐸𝑅𝑐𝑜𝑙𝑑)  

(2) 

The single steps to arrive at the durability ratio (DR) are reported in Table 18, the risk for durability issues 
with DR = 0.61 for this vehicle is low. 

25 

 
 
 
 
 
 
 
Table 18: Durability emission (ER) ratio using WHVC tests on the roller bench - ER data from Table 14. 

NOx_ER  CO_ER  THC_ER 

WHVC 20°C hot  0.32 

0.003 

0.037 

WHVC 20°C cold  1.85 

0.119 

0.041 

weighted ER 

DRWHVC 

Source: JRC, 2023. 

0.53 

0.61 

0.019 

0.038 

0.025  0.048 

For the pollutant with highest risk, i.e. NOx in this case, and as an alternative to the use of roller bench based 
WHVC tests for HDV to assess durability risks, ISC tests performed on the road with PEMS are evaluated (see 
Table  10  for  the  tests  performed  during  this  pilot).  Here,  work  based  moving  average  windows  with  a  hot 
engine are extracted that have a relative engine power between 18 and 22 % of the nominal engine power. 
The  average  pollutant  emissions  for  these  MAWs  are  multiplied  with  DFint  for  the  respective  pollutant  to 
obtain the projected emissions for the vehicles mileage at the useful life.  

These projected emissions are now compared to the emission limits multiplied by the ISC conformity factor, 
i.e. CF=1.5 for gaseous pollutants: 

𝐷𝑅𝐼𝑆𝐶 = 𝐷𝐹𝑖𝑛𝑡 × 𝑀𝐴𝑊𝑒𝑚𝑖𝑠𝑠𝑖𝑜𝑛𝑠 (𝑙𝑖𝑚𝑖𝑡 ∗ 𝐶𝐹𝐼𝑆𝐶)

⁄

(3) 

The DRs obtained with this methodology for all ISC tests with the different payload are summarized in Table 
19, together with a comparison to the WHTC limit itself. 

Table 19: Durability ratios calculated for all ISC tests, using extracted emissions for 18-22% power MAW with hot engine. 

Test 

average  NOx 
(mg/kWh) 

DFint  x  avg 
NOx (mg/kWh) 

DRISC  

ISC1_10 

136 

ISC1_55 

267 

ISC2_55 

205 

ISC3_55 

183 

ISC1_100  66 

ISC2_100  70 

Source: JRC, 2023. 

157 

307 

236 

210 

76 

80 

0.23 

0.44 

0.34 

0.30 

0.11 

0.12 

For the vehicle tested in this pilot, also the DRISC = 0.44 falls into the low category. As for the ISC test, the cold 
start period was excluded, the value durability ratio  DRISC is slightly lower compared to the one obtained for 
DRWHVC = 0.61 which explicitly included the cold start test. 

26 

 
 
 
 
 
 
 
 
5  Conclusions 

5.1  Main results 

The  tailpipe  emissions  compliance  of  the  vehicle  was  verified  on  the  road  under  regulated  conditions  by 
performing  In-Service  Conformity  (ISC)  tests  with  three  different  payloads  (10%,  55%  and  100%),  and  the 
vehicle regulated pollutant (NOx, CO, THC) emissions were found below the ISC applicable conformity factors 
in all cases.  

In  addition,  non-regulated  laboratory  WHVC  tests  were  conducted  at  different  ambient  temperatures  and 
under  cold  and  hot  testing  conditions.  During  these  WHVC  tests  a  clear ambient  temperature  effect  on  the 
emissions was observed, since the lowest NOx emissions were found at 20°C testing temperature, and higher 
emissions at 0°C, 35°C, -7°C, and -20°C, respectively. In addition, much higher NOx emissions were measured 
under cold start conditions compared to hot start. The emission ratio (ER) was between 0.32 and 1.17 for hot 
tests and between 1.85 and 4.75 for cold tests. CO and THC emissions were very low in all cases.  

The  laboratory  tests  are  conclusive  to  verify  the  presence  of  possible  auxiliary  emissions  strategies  (AES) 
when using the 1.3/2.5 thresholds: ambient temperature triggers modulations or interruptions of the EGR and 
SCR functioning and these are typical auxiliary emissions strategies for Diesel heavy-duty engines. 

The other tests using the relative approach (using as parameter the connection of the OBD logger, AdBlue or 
fuel level, or reverse driving cycle) did not exhibit any suspicious emission behaviour.  

The durability compliance was assessed by applying the proposed method of the JRC. The durability ratio (DR) 
was below 0.8 (green low risk area) for all tests. 

Particle  Number  (PN)  was  not  measured  because  PN  measurements  are  not  formally  required  for  PEMS 
testing of Euro VI-d engines (it applies from Euro VI-e), and a PEMS PN instruments was not available when 
the experiments were conducted.  

5.2  Recommendations  for  market  surveillance  emissions  testing  on heavy-duty 

vehicles 

A test program for verifying the emissions compliance of Euro VI heavy-duty engines should include at least: 

-  For  the  compliance  with  tailpipe  emissions  limits,  PEMS  tests  conducted  according  to  the  In-Service 
Conformity  (ISC)  rules  laid  down  in  Regulation  2011/582:  this  should  include  at  least  one  route  and  two 
payloads (low, high) for challenging the engine into various areas of its map; 

- For the compliance with On-Board Diagnostics requirements, the use of an OBD scan tool to check for the 
presence and quality of the mandatory data (i.e., the parameters required to conduct the ISC PEMS test); 

-  For  assessing  the  potential  presence  of  Auxiliary  Emissions  Strategies  (AES),  tests  under  non-regulated 
conditions  designed  to  trigger  the  variation  of  the  after-treatment  functioning.  Ambient  temperature  is  the 
parameter  with  the  highest  likelihood  to  trigger  modifications  in  the  functioning  of  diesel-after  treatment 
technologies (EGR,  SCR)  but  a  controlled  environment  (emissions  chassis  dynamometer)  is required  for that 
purpose. As alternative, one can recommend to test the same vehicle using PEMS during winter and summer 
conditions, always on the same route; 

-  For  assessing  the  risk  of  non-compliance  with  the  durability  requirements,  a  methodology  has  been 
proposed  but  faces  the  same  limitation  as  for  the  previous  point:  ideally,  WHVC  tests  on  a  chassis 
dynamometer can provide the conditions to benchmark the engine emissions under reference conditions close 
to those on the engine type approval cycle (WHTC). As alternative, a methodology making use of the moving 
windows  on  a  PEMS  test  has  been  proposed  but  it  will  require  experience  and  data  from  more  vehicles  to 
determine whether it’s reliable. 

27 

 
 
References 

Bonnel. P. et al., 2022. European market surveillance of motor vehicles - Results of the 2020-2021 European 
Commission Vehicle Emissions Testing programme, EUR 31030 EN, Publications Office of the European Union, 
Luxembourg, 2022, ISBN 978-92-76-49645-8, doi:10.2760/59856, JRC128360.  

Clairotte. M. et al., 2020.  Joint Research Centre  2019 light-duty  vehicles  emissions  testing  - Contribution to 
the EU market surveillance: testing protocols and vehicle emissions performance, EUR 30482 EN, Publications 
Office of the European Union, 2020, ISBN 978-92-76-26952-6, doi:10.2760/783111, JRC122035. 

EC, 2009. Regulation (EC) 2009/595 of the European Parliament and of the Council of 18 June 2009 on type-
approval of motor vehicles and engines with respect to emissions from heavy duty vehicles (Euro VI) and on 
access  to  vehicle  repair  and  maintenance  information  and  amending  Regulation  (EC)  No  715/2007  and 
Directive  2007/46/EC  and  repealing  Directives 80/1269/EEC, 2005/55/EC  and  2005/78/EC.  Off.  J.  Eur.  Union 
OJ L 188, 1–13. 

EC,  2011.  REGULATION  (EU)  2011/582  of  25  May  2011  implementing  and  amending  Regulation  (EC) 
2009/595 of the European Parliament and of the Council with respect to emissions from heavy duty vehicles 
(Euro  VI)  and  amending  Annexes  I  and  III  to  Directive  2007/46/EC  of  the  European  Parliament  and  of  the 
Council. Off. J. Eur. Union OJ L 167, 1–168. 

EC, 2017. Regulation (EU) No 2017/1151 of 1 June 2017 supplementing Regulation (EC) No 715/2007 of the 
European  Parliament  and of  the  Council  on  type-approval  of  motor  vehicles with  respect  to  emissions  from 
light passenger and commercial vehicles (Euro 5 and Euro 6) and on access to vehicle repair and maintenance 
information,  amending  Directive  2007/46/EC  of  the  European  Parliament  and  of  the  Council,  Commission 
Regulation  (EC)  No  692/2008  and  Commission  Regulation  (EU)  No  1230/2012  and  repealing  Commission 
Regulation (EC) No 692/2008. Off. J. Eur. Union OJ L 175, 1–643. 

EC, 2018a. Regulation (EU) 2018/858 of the European Parliament and of the Council of 30 May 2018 on the 
approval  and  market  surveillance  of  motor  vehicles  and  their  trailers,  and  of  systems,  components  and 
separate  technical  units  intended  for  such  vehicles,  amending  Regulations  (EC)  No  715/2007  and  (EC)  No 
595/2009 and repealing Directive 2007/46/EC (Text with EEA relevance.). Off. J. Eur. Union OJ L 151, 1–218. 

EC, 2018b. Regulation (EU) 2018/1832 of 5 November 2018 amending Directive 2007/46/EC of the European 
Parliament  and  of  the  Council,  Commission  Regulation  (EC)  No  692/2008  and  Commission  Regulation  (EU) 
2017/1151 for the purpose of improving the emission type approval tests and procedures for light passenger 
and commercial vehicles, including those for in-service conformity and real-driving emissions and introducing 
devices for monitoring the consumption of fuel and electric energy. Off. J. Eur. Union, L 301, 1–314. 

Giechaskiel, B., Selleri, T., Gioria, R., Melas, A.D., Franzetti, J., Ferrarese, C., Suarez-Bertoa, R. 2022. Assessment 
of  a  Euro  VI  Step  E  Heavy-Duty  Vehicle’s  Aftertreatment  System.  Catalysts,  12,  1230. 
https://doi.org/10.3390/catal12101230.  

UN, 2013. Regulation No. 49, Revision 6; Uniform provisions concerning the measures to be taken against the 
emission  of  gaseous  and  particulate  pollutants  from  compression  ignition  engines  and  positive  ignition 
engines  for  use  in  vehicles;  Agreement:  Concerning  the  Adoption  of  Uniform  Technical  Prescriptions  for 
Wheeled  Vehicles,  Equipment  and  Parts  which  can  be  fitted  and/or  be  used  on  Wheeled  Vehicles  and  the 
Conditions  for  Reciprocal  Recognition  of  Approvals  Granted  on  the  Basis  of  these  Prescriptions; 
E/ECE/324/Rev.1/Add.48/Rev.6−E/ECE/TRANS/505/Rev.1/Add.48/Rev.6; 4 March 2013. 

28 

 
List of abbreviations and definitions 

AES 
ASC 
CH4 
CF 
CO 
CO2 
DG GROW 
DF 
DOC 
DPF 
DR 
EC 
EEA 
EGR 
ER 
EU 
DD 
GTR 
HDV 
JRC 
ISC 
MAW 
MaSu 
n.a. 
NH3 
NMHC 
NOx 
OBD 
OCE 
PEMS 
PI 
PM 
PN 
RDE 
SCR 
THC 
UN ECE   
VELA 
VIN 
WHSC 
WHTC 
WHVC 
WVTA 

Auxiliary Emissions Strategy  
Ammonia Slip Catalyst 
Methane 
Conformity Factor 
Carbon monoxide 
Carbon Dioxide 
Directorate General for Internal Market, Industry, Entrepreneurship and SMEs 
Deterioration Factor 
Diesel Oxidation Catalyst 
Diesel Particle Filter 
Durability Ratio 
European Commission 
European Environment Agency 
Exhaust Gas Recirculation 
Emission Ratio 
European Union 
Defeat Device 
Global Technical Regulation 
Heavy-duty vehicle 
Joint Research Centre 
In-Service Conformity 
Moving Average Window 
Market Surveillance 
Not Applicable / Not Available 
Ammonia 
Non-methane Hydrocarbons 
Nitrogen Oxides 
On-Board Diagnostics 
Off-Cycle Emissions 
Portable Emissions Measurement System 
Positive Ignition 
Particle Mass 
Particle Number 
Real Driving Emissions 
Selective Catalytic Reduction 
Total Hydrocarbons 
United Nations Economic Commission for Europe 
Vehicle Emission Laboratory 
Vehicle Identification Number 
Worldwide harmonised steady state cycle 
Worldwide harmonised transient cycle 
Word-harmonized vehicle cycle 
Whole Vehicle Type Approval 

29 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
List of figures 

Figure 1: World Harmonised Transient Cycle (WHTC). ...............................................................................................................................5 

Figure 2: World Harmonised Vehicle Cycle (WHVC). ....................................................................................................................................7 

Figure 3: Picture of the HDV tested. .................................................................................................................................................................. 13 

Figure 4: ISC test speed profile. ........................................................................................................................................................................... 15 

Figure 5: Effect of WHVC test temperature upon cumulative NOx emissions. ...................................................................... 19 

Figure 6: Effect of WHVC test temperature upon engine coolant temperature. ................................................................... 19 

Figure 7: OBD logger; NOx, CO, and THC emissions with and without OBD connected. ................................................... 21 

Figure 8: Comparison of normal and reverse driving cycle. ............................................................................................................... 22 

Figure 9: NOx emissions for WHVC tests (normal, low AdBlue, and low Fuel level). .......................................................... 22 

Figure 10: CO emissions for WHVC tests (normal, low AdBlue, and low Fuel level). ......................................................... 23 

Figure 11: THC emissions for WHVC tests (normal, low AdBlue, and low Fuel level). ....................................................... 23 

30 

 
 
List of tables 

Table 1: Overview of emissions requirements for HDV or Engines. ..................................................................................................4 

Table 2: Euro VI emissions limits for heavy-duty engines. .....................................................................................................................5 

Table 3: Heavy-duty ISC measurement conformity factors (CF).........................................................................................................6 

Table 4: Euro VI PEMS ISC requirements. ...........................................................................................................................................................6 

Table 5: Vehicle useful life for the durability requirement of emission control systems according to UN-ECE 
R49, Article 5.4. The sooner of mileage and vehicle age is considered........................................................................................ 10 

Table 6: Assigned multiplicative deterioration factors according to UN-ECE R49 – Annex 7, for both WHTC and 
WHSC test cycles. ............................................................................................................................................................................................................ 10 

Table 7: Testing options for MaSu verifications......................................................................................................................................... 12 

Table 8: Test vehicle characteristics.................................................................................................................................................................. 13 

Table 9: Engine characteristics. ............................................................................................................................................................................ 14 

Table 10: Conditions, work and time shares for the PEMS ISC tests. .......................................................................................... 14 

Table 11: Gaseous pollutants (NOx, CO and THC) emission ratios (ER) for the ISC tests compared with the 
conformity factor (CF). ................................................................................................................................................................................................. 16 

Table 12: Conditions of non-regulatory on-road tests. ......................................................................................................................... 16 

Table 13: Non-regulatory on-road and laboratory WHVC tests. ..................................................................................................... 17 

Table 14: Gaseous pollutants emission ratios (ER) (×CF for on-road tests) for RDE, LONG, and WHVC tests. . 18 

Table 15: Vehicle emissions in (mg/kWh) with and without OBD connected. “Raw data” for THC, and diluted 
data for NOx and CO. .................................................................................................................................................................................................... 20 

Table 16: WHVC tests compared with reverse WHVC tests. Vehicle emissions in (mg/kWh). ...................................... 21 

Table 17: Assigned and interpolated Deterioration Factors at the vehicles present mileage. ..................................... 25 

Table 18: Durability emission (ER) ratio using WHVC tests on the roller bench - ER data from Table 14. .......... 26 

Table 19: Durability ratios calculated for all ISC tests, using extracted emissions for 18-22% power MAW 
with hot engine. ................................................................................................................................................................................................................ 26 

31 

 
 
 
 
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