Timeline: EEA report references to real world emissions and Euro standard discrepancies
European Environment State and Outlook Reports (SOER): SOER 2005, SOER2010 air pollution fiche, SOER2015 synthesis (translated) and Part B transport
TERM reports: 2004 (CO2 and NOx), 2005, 2006, 2007, 2008, 2011, 2012, 2013, 2014, 2015
Air Quality in Europe reports: 2011, 2012, 2013, 2014, 2015
NEC Directive Status reports: published in 2010, 2011, 2012, 2014, 2015
Cars and vans CO2 monitoring: 2014 (Apr and Oct), 2015 (Apr and Nov), 2016 (Apr)
Policy evaluation and other: EEA Signals 2013 – Every breath we take; Road user charges for heavy goods vehicles (HGV) 2013; Evaluation of progress
under the EU National Emission Ceilings Directive 2012, Projections in hindsight 2015.
Date
Oct
2004
Publication
TERM 2004 p10
Nov
2005
SOER 2005 p99
Mar
2006
TERM 2005 p19
Feb
2007
TERM 2006 p19
And similar:
TERM 2007 p19
Description
There is, however, increasing evidence that standardised test cycles used for the type approval of vehicles do not
necessarily represent real world driving conditions. The issue of 'chip-tuning' of diesel vehicles to boost power at the
expense of fuel consumption and low emissions is a cause for concern (Danish Miljøstyrelsen, 2004)
There is also a concern that emissions from transport are not falling as quickly as expected due to test cycles not
reflecting real-world driving conditions, the chip-tuning of diesel cars and other non-combustion emission sources
(brakes, car tyres) that increase in line with traffic growth and congestion.
Emission standards do not always offer a correct picture of emissions nor do they lend themselves easily to direct
comparison between modes. Firstly, engines are tested with different test cycles that put different stresses on the
engines. Even though test cycles are approximations of real-world loads on engines, they will inevitably have
shortcomings.
Air quality is affected by a combination of emission and meteorological factors. It is therefore too early to offer solid
conclusions on the impact of transport on air quality development in urban areas. However, two elements may help to
explain why the improvement still fails to appear: the increased use of diesel in urban areas and an increase of the
TERM 2008 p18
Sep
2010
NEC Directive Status
report 2009 p5
And similar in 2010
NECD status report
(published in 2011),
2011 (2012), 2012
(2013), 2013 (2014)
and 2014 (2015)
reports
Nov
2010
SOER2010 Air
Pollution thematic
assessment p24
Nov
2011
TERM 2011
NOx p14 and Box
2.16 p28.
CO2 Section 7.5 and
7.6 p60-61
Nov
2011
Air Quality in Europe
2011 p43
fraction of NOX emitted as NO2 since 2000. Oxidation catalysts and regenerative traps in modern diesel vehicles have
been found to cause the increase (AQEG, 2006)
2009 status report: although overall emissions have decreased since 1990, the reduction has not always been as large as
originally anticipated. This is partly because the sector has grown more than expected and partly because vehicle
emission standards have not always delivered the foreseen level of NOX reductions
2011 status report: although overall emissions have decreased since 1990, the reduction has not always been as large as
originally anticipated. This is partly because the sector has grown more than expected and partly because vehicle
emission standards have not always delivered the foreseen level of NOX reductions
2015 status report: Actual emissions from vehicles driven on roads under normal conditions are also higher than
originally expected, with 'real-world emissions' often largely exceeding the permitted test-cycle emissions used for
certification of vehicles complying with Euro standards. This is particularly true for light-duty diesel vehicles.
Reduced emissions from the road transport sector have occurred despite the general increase in activity within the
sector, and have been achieved mainly as a result of fitting catalysts to vehicles, a process driven by the introduction of
respective EU standards. It is important to note, however, that a number of NOX vehicle emission standards have not
been as effective in reducing real-world NOX emissions as was originally anticipated, especially for diesel vehicles (both
passenger vehicles and heavy- and light-duty vehicles). Much of the past reduction in NOX from road transport can thus
mainly be ascribed to gasoline passenger cars and not diesel vehicles (Vestreng et al., 2009)
The actual emissions from vehicles (often termed 'real-world emissions') may exceed the type-approval emissions for
each vehicle type. This is particularly the case for NOX emissions from diesel vehicles. The emission factors used in the
emissions inventories by EU Member States have been regularly updated according to new findings. Thus, the reported
developments in the emissions presented here should include the 'real-world driving' emission factors as far as is
possible.
and
Section 7.5 ‘Laboratory testing versus real-life driving’ presents a discussion of differences between real-world and NEDC
testing for CO2, including ‘The assumptions underlying the NEDC do not properly represent actual driving styles of
average car users: this is seen in terms of accelerations and speeds, for instance. It is commonly reported in motor
magazines that it is difficult to achieve the energy efficiency claimed in advertising of new vehicles, even though the
values used are taken from type-approval testing.’ Illustrative CO2 measurements are quoted from a TNO2010 study.
First AQ in Europe report.
Actual emissions from vehicles (often termed 'real world emissions') may exceed the allowed emissions specified in the
Euro emission standards for each vehicle type. This is particularly the case for NOX emissions from light-duty diesel
Sep
2012
Oct
2012
Nov
2012
vehicles. EU Member States regularly update the emission factors used in their emission inventories and their previously
reported emissions. Reported developments in emissions should therefore include 'real world' emission factors.
Air Quality in Europe Under real-world driving conditions, emissions from vehicles often exceed the test cycle limits specified in the Euro
2012 p38, 60
emission standards (EEA, 2011d). Reported emissions data from countries are based on the best knowledge available
concerning real-world emissions. However, the lack of vehicle exhaust measurements, especially for newer vehicle
technology types, often means the reported emission estimates are of relatively high uncertainty, and may not always
reflect the actual, potentially higher, on-road driving emissions
Policy evaluation
Nevertheless, the following examples illustrate some key instances in which new knowledge has led to significant
studies eg
revision of emission estimates. NOX emissions from road transport higher than foreseen under real operating conditions:
‘Evaluation of
In order to improve air quality, the pollutant exhaust emissions of road vehicles are limited by regulation. Regulatory
progress under the
limits apply to exhaust emission measurements during vehicle type approval procedures with the New European Driving
EU National Emission Cycle (NEDC). Over the last three decades, limit values were lowered in steps from EURO 0 to EURO 5. Further steps have
Ceilings Directive’
already been defined for the coming years (EURO 6). Air quality, however, has not improved as much as predicted on the
basis of the tightening of emissions standards, especially with respect to nitrogen oxides (NOX). One reason for this is the
gap between the performance of emission control measures during type approval tests (NEDC) and their effectiveness
under real-life urban driving conditions
TERM 2012 p32,
In simple terms, the 'euro standards' for vehicle emissions have not succeeded in bringing down real NO2 emissions to
p35, p55
the levels set out in the legislation. Further discussion on this disparity can be found in Sections 4.3 and 4.5 and Chapter
5.
4.3 Real-world emission performance of vehicles Under real-world or 'normal' driving conditions, emissions from vehicles
often exceed the test cycle limits specified in the Euro emission standards (see Box 2.16 of the TERM 2011 report (EEA,
2011b)). Several studies (Pelkmans and Debal, 2006; VojtisekLom et al., 2009; Rubino et al., 2007; Weiss et al., 2012 )
have indicated that real world NOX emissions of light-duty diesel vehicles might substantially exceed Euro 2–5 emission
limits. Tests performed by JRC (Weiss et al., 2011) on passenger cars and light commercial vehicles show that Euro 3–5
diesel vehicles exceed the emission limits by a factor of 2–4 in real world driving. The exceedance can be much higher on
sub-sections of individual 'on-road' tests which are comparable in duration to standard laboratory testing with the New
European Driving Cycle (NEDC). The exceedance also occurs with heavy duty vehicles (HDV), albeit to a lesser extent
(Verbeek et al., 2010). The emission factors used by EU Member States for estimating emissions when developing
inventories have been updated to reflect this as far as possible, such as in the COPERT 4 road transport emissions model
(Emisia, 2012). There is further evidence from roadside remote sensing of emissions that the divergence could be even
greater than indicated by currently available emission factors (Carslaw et al., 2011; Beevers et al., 2012). Roadside
remote sensing is a technique which measures the concentration of pollutants in the exhaust plume of every vehicle that
passes the sensing equipment. Further remote sensing studies in the Netherlands (Velders et al., 2011) have highlighted
the problem with Heavy Goods Vehicles (HGVs) equipped with Selective Catalytic Reduction (SRC) for NOX control. Many
HGVs use this technology to meet the Euro V standards, but while it appears effective at high speeds, under low-load
urban conditions, the technology is much less efficient due to the low exhaust temperatures making the catalyst
ineffective at reducing NOX in the tailpipe. If this technology is used, emissions from Euro V vehicles can therefore
actually be higher than the Euro IV equivalents under so called slow urban conditions unless the technology has been
optimised (HBEFA, 2010). As a longer term solution, the European Commission is developing new test procedures aimed
at more accurately reflecting real world conditions.
Feb
2013
Road user charges
for heavy goods
vehicles (HGV)
Actual 'real-world' vehicle emissions differ considerably both from limit values laid down for vehicles in legislation, and
from vehicle approval test conditions.
Jul
2013
Oct
2013
EEA Signals – Every
breath we take
Air Quality in Europe
2013 p41,
Another problem in controlling air pollution comes from the difference between laboratory tests and real world
conditions
Under real-world driving conditions, emissions from vehicles often exceed the test-cycle limits specified in the Euro
emission standards (EEA, 2011a).
p62
Actual emissions from vehicles (often termed 'real world emissions') may exceed the allowed test cycle emissions
specified in the Euro emission standards for each vehicle type. This is particularly the case for NOX emissions from lightduty diesel vehicles.
Dec
2013
TERM 2013 Box 4.1
p40
Apr
2014
Monitoring CO2
emissions from
passenger cars
Member States report CO2 emission levels determined as part of the type approval test procedure. These levels are
measured under laboratory conditions using a legislative driving cycle (i.e. the New European Driving Cycle (NEDC)). This
should make the measurements comparable between manufacturers, but not necessarily representative of realworld
conditions. In fact, NEDC cycles represent an artificial driving speed pattern with low accelerations, constant speed
cruises, and many idling events. As a result, the measured emissions levels can be different from those in real world
conditions. The driving cycles influence not only CO2 emissions but also air pollutants, such as NOX. Although not
discussed further in this document, differences between test cycle and real world NOX emissions have proved
Oct
2014
Monitoring CO2
emissions from
passenger cars and
vans in 2013 p6
And all of Chapter 5
(detailed analysis)
Nov
2014
Air Quality in Europe
2014 p25
Box 5.2 p32
particularly problematic for air quality policy. While vehicle emission standards for NOX have been increasingly
strengthened (based on NEDC cycles) in recent years, the reductions from this sector have not been as large as originally
anticipated due to the higher realworld emissions that have occurred.
In recent years there has been a growing awareness of the need to ensure that emissions measured in the type approval
driving cycle better represent 'real-world' driving conditions. In particular, numerous studies have highlighted the often
significant divergence between type approval and real-world CO2 emissions. Reflecting this, a substantial effort has been
made in EU in recent years to update the current type-approval procedure by introducing the Worldwide harmonized
Light vehicles Test Procedure (WLTP) approach that aims to better represent actual vehicle operations on the road.
Despite such differences, it is nevertheless clear that real emission reductions have occurred as a result of the
introduction of the EU CO2 emission performance standards for light duty vehicles. To illustrate the scope of the
potential differences, this report also presents results of an assessment comparing the current reported regulatory 'typeapproval' emissions with estimated 'real-world' emissions. Real-world CO2 emissions were estimated based upon a set of
models constructed to determine fuel consumption of passenger cars predicted on the basis of independent variables
reported by Member States, including the vehicle mass, engine capacity and type-approval CO2 emissions. The main
findings of the assessment are:
• EU wide, the real-world to type-approval CO2 emissions ratio for petrol cars is comparable to the one for diesel cars for
all vehicle sizes. Looking at the overall petrol and diesel fleet, the ratio is somewhat higher for diesel cars (21 %) than for
petrol ones (19 %) because the relative contribution of large cars (with an engine size above 2.0 litres) is higher for diesel
than for petrol.
• The CO2 emissions ratio for petrol cars varies from 18 % for small cars to 32 % for large cars, whereas for diesel cars it
ranges from 22 % for small cars to 27 % for large cars
Actual emissions from vehicles (often termed 'real-world driving emissions') may exceed the allowed test-cycle emissions
specified in the Euro emission standards for each vehicle type. This is particularly the case for NOX emissions from lightduty diesel vehicles (EC, 2013a, Williams and Carslaw, 2011). EU Member States regularly update the emission 'factors'
(values used to estimate how much of a particular pollutant is present in emissions of a particular type) used in their
emission inventories and their previously reported emissions. Reported developments in emissions should therefore
include 'real-world' emission factors.
Dec
2014
TERM 2014 p13,
Box 2.11 p27
The 2015 target for the average CO2 emissions of new passenger cars was attained in 2013. However, the divergence
between fuel consumption and resulting CO2 emissions, when comparing tests against real-world conditions, remains a
point of concern.
Numerous studies have documented the often significant divergence between type-approval and real-world CO2
emissions. It appears that there may indeed be an increasing divergence between type-approval and real-world fuel
consumption, and hence, CO2 emissions. A recent study (Ntziachristos et al., 2014) suggests that the difference is 11 %
for petrol cars and 16 % for diesel cars. The study also stated that the difference can reach 60 % for newer vehicle
models registered in the low 90 g CO2/km to 100 g CO2/km category. Another recent report (ICCT, 2014) suggests that
the divergence increased from 10 % on average in 2001 to 23 % by 2011, and to more than 30 % in 2013. Despite the
difference in CO2 emissions when measured using real-world and type-approval approaches, real emission reductions
have occurred as a result of regulations based upon the current type-approval monitoring regime. Using implied
emission factors based on total consumption and activity, researchers (Papadimitriou et al., 2014) calculated a 2 % fleetwide fuel consumption reduction for both diesel and gasoline passenger cars in 2010 compared to 2005. The improved
testing method and the increased focus on real world emissions are expected to bring about additional reductions in
future.
p47
Mar
2015
SOER2015 Synthesis
report p101
Mar
2015
SOER2015 Part B
Transport fiche
Apr
2015
Monitoring CO2
emissions from
passenger cars
Highlight
...this is also the effect of the divergence between vehicle test results and actual on-road vehicle performance for NOX
(EEA, 2013a; Weiss et al., 2012) and, for similar reasons, for CO2. For NOX, the divergence also exist in the most modern
diesel vehicles. Recent research has estimated that the average on-road emission levels of NOX is seven times the
certified emission limit for Euro 6 vehicles, with a few vehicles performing substantially better than others (Franco et al.,
2014). As the authors state, the fact that one of the vehicles tested is already compliant with the Euro 6 standard in real
driving conditions indicates that the technologies for 'realworld–clean' diesels is already in place.
Alongside increasing traffic volumes, the promotion of diesel vehicles is contributing to air quality problems. This is
because diesel cars generally emit more particulate matter and nitrogen oxides than petrol cars but less carbon dioxide,
although recent data indicate that the carbon dioxide difference is decreasing (EEA, 2014l). In addition, NOX emissions
from diesel vehicles under real-world driving conditions often exceed the test-cycle limits specified in the Euro emission
standards, a problem that also affects official fuel consumption and CO2-emission values.
A less positive development is the increase in the fraction of NOx emitted as NO2 by diesel vehicles, leading to
exceedances of NO2 values in many European cities. Increasing traffic volumes, coupled with the promotion of diesel
vehicles in many EU Member States, have thus become one of the main reasons why countries do not meet EU air
quality regulations.
To make matters worse, NOx emissions from diesel vehicles under real-world driving conditions often exceed the testcycle limits specified in the Euro emission standards, a problem that also affects official fuel consumption and CO2emission values. In general, an average diesel car emits more PM and NOX than petrol, but less CO2. Recent data show
that the CO2 difference is decreasing.
Member States report new vehicles’ CO2 emission levels, calculated on the basis of a standardised driving cycle. This
cycle allows a comparison of emissions by manufacturers, but it does not necessarily represent real-world driving
conditions. Later this year, the EEA plans to publish a separate report highlighting the key reasons for the growing
differences observed between official and real world driving emissions
May
2015
Projections in
Hindsight p29
Nov
2015
Monitoring CO2
emissions from
passenger cars and
vans in 2014 p5
Air Quality in Europe
2015 p15
Nov
2015
Dec
2015
TERM2015 p8
This is at least partly explained by the observed lower effectiveness of reducing NOX by vehicle Euro standards, for which
the differences in assumed effectiveness compared to the situation on the ground are well documented (e.g. EEA,
2013b)
The reported CO2 emissions data presented in this report are based on measurements performed in the laboratory using
a standard European vehicle test cycle. Such measurements may not reflect real-world driving performance.
Actual emissions from vehicles (often termed 'real-world driving emissions') may exceed the allowed test-cycle emissions
specified in the Euro emission standards for each vehicle type. This is particularly the case for NOX emissions from lightduty diesel vehicles (EC, 2013a, Williams and Carslaw, 2011). EU Member States regularly update the emission 'factors'
(values used to estimate how much of a particular pollutant is present in emissions of a particular type) used in their
emission inventories and their previously reported emissions. Reported developments in emissions should therefore
include 'real-world' emission factors.
In recent years a growing discrepancy has been observed between the official and real-world emissions. While a new
testing procedure has been developed so that the official results may in the future better represent actual vehicle
performance, the date for introducing this new procedure in the EU has not yet been agreed.
p9
As noted for CO2, there are also significant differences currently observed between official and real-world vehicle
emissions of NOX
Section 5.1.4 p49
(policy evaluation)
There is a significant discrepancy between official vehicle CO2 emission measurements and vehicles' performance in the
real world. A recent comparison of fuel consumption data from more than half a million private and company vehicles
across Europe has shown how this discrepancy between 'type approval' CO2 measurements, made on the basis of a
standardised laboratory test, and real-world values has grown over the last 12 years (ICCT, 2014). In particular, the gap
has increased considerably since 2007, when the binding EU average CO2 target for passenger cars was first proposed.
While the average discrepancy between type approval and on-road CO2 emissions was below 10% in 2001, by 2013 it
had increased to around 30%. Moreover, while the average discrepancy between type approval and real-world CO2
values was initially similar for diesel and petrol vehicles, since 2010 the difference between the two technologies has
increased: for conventional diesel vehicles, the gap is 5% greater than for conventional petrol vehicles. Several other
European studies have also demonstrated the magnitude of the gap between the current New European Driving Cycle
legislative and real-world CO2 emissions. All studies confirm this gap: the average discrepancy between type approval
and on-road CO2 emissions is in the range of 10–40%. For NOX emissions from diesel vehicles the gap is even larger, with
real-world emissions being on average up to four or five times higher than the official test measurements (ICCT, 2015).
Jan
2016
Apr
2016
Explaining road
transport emissions
Monitoring CO2
emissions from
passenger cars
Highlight
Non-technical guide.
Member States report new vehicles’ CO2 emission levels, measured under standardised laboratory conditions, following
the requirements of the New European Driving Cycle (NEDC) test procedure. This procedure is designed to allow a
comparison of emissions for different manufacturers. However, there is now wide recognition that the NEDC test
procedure, dating from the 1970s, is out-dated and does not necessarily represent real-world driving conditions and
emissions due inter alia to a number of flexibilities that allow vehicle manufacturers to optimise the conditions under
which their vehicles are tested.