WORKING PAPER 2015–8
Real-world fuel consumption of popular
European passenger car models
Authors: Uwe Tietge, Peter Mock, Nikiforos Zacharof, Vicente Franco
Date: 28 December 2015
Keywords: fuel consumption, CO2 standards, vehicle test procedures
Summary
Gap between ‘real-world’ and offiical CO2 values
Official fuel consumption values of
new passenger cars in Europe are
becoming increasingly unrepresentative of real-world performance.
The divergence between official and
real-world fuel consumption values
more than quadrupled over the last
fourteen years. After EU-wide CO 2
standards were introduced in 2009,
official fuel consumption values
decreased by 15 percent while
real-world figures only decreased by 2
percent. This divergence undermines
climate change mitigation efforts and
costs the average car owner €450
per year.
This study compares official fuel
consumption values measured in
laboratories with the real-world
performance of 20 popular vehicle
models. All models claim significant
improvements in fuel efficiency since
2009, with reductions in official fuel
consumption values ranging from 8 to
30 percent. On-road measurements,
however, indicate that eight models
made little to no improvement in
real-world fuel efficiency. Five models
achieved more than a 10 percent
reduction in real-world fuel consumption since 2009. Model overhauls
are frequently followed by abrupt
60%
auto motor und sport (D)
50%
Travelcard (NL)
km77.com (E)
45% (company cars)
40% (all data sources)
auto motor & sport (S)
36% (private cars)
40%
The trend toward increasingly unrealistic fuel consumption values can be
traced back to the exploitation of flexibilities in the current vehicle testing
procedure. While the Worldwide
Harmonized Light Vehicles Test
Procedure (WLTP) will be introduced
in the EU in 2017 and will help align
official and real-world fuel consumption values, it will not by itself solve
the problem of unrealistic fuel consumption values. Further actions are
needed, including in-use conformity
testing of randomly selected vehicles
on the road and the establishment of
a EU-wide type-approval authority.
Touring Club Schweiz (CH)
honestjohn.co.uk (GB)
30%
AUTO BILD (D)
20%
8%
10%
0%
reductions in official fuel consumption
values. Real-world fuel consumption
values are, however, rarely reduced to
the same extent, indicating that fuel
efficiency improvements measured
during laboratory testing do not fully
materialize on the road.
n = approx. 0.6 million vehicles
2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014
Year
Figure 1: Divergence between real-world and manufacturers’ reported CO2 emissions
for various real-world data sources, including average estimates for private cars,
company cars, and all data sources.
© INTERNATIONAL COUNCIL ON CLEAN TRANSPORTATION, 2015
Introduction
The growing divergence between
real-world fuel consumption values
and official laboratory measurements of new European passenger
cars undermines policies designed
to mitigate climate change and
reduce fuel expenses for consumers.
The latest “From Laboratory to
Road” study of the International
Council on Clean Transportation
(ICCT) estimates real-world fuel
WWW.THEICCT.ORG
REAL-WORLD FUEL CONSUMPTION OF POPULAR EUROPEAN PASSENGER CAR MODELS
The divergence between official and
real-world CO­2 values is important for
all stakeholders:
• For society as a whole, the gap
undermines efforts to mitigate
climate change and reduce fossil
fuel imports into the EU.
• Fo r g ove r n m e n t s , t h e g a p
compromises tax systems and
incentive schemes that are based
on CO2 values and can thus lead
to lost tax revenues and misallocation of public funds.
• For car manufacturers, the
divergence puts those that want
to report realistic CO2 emission
values at a competitive disadvantage. Manufacturers reporting
unrealistic CO2 values may also
damage their credibility and may
erode public and regulator trust
in the industry.
• For an average car owner,
the divergence translates into
increased fuel expenses of €450
per year.
This paper focuses on the consumer
impacts of the growing divergence
by p r e s e n t i n g r e a l - wo r l d f u e l
consumption values for selected
popular car models. For consumers,
real-world fuel consumption
values have been decreasing less
than suggested by official values.
After EU-wide CO2 standards were
introduced in 2009, official fuel
con sum p t io n va lue s d e cre as e d
1
See Tietge, U. et al., “From laboratory to
road: A 2015 update,” http://www.theicct.
org/laboratory-road-2015-update
10
Fuel consumption [l gasoline/100 km equivalents]
consumption values from data on
almost 600,000 cars from eleven
data sources covering six European
countries.1 The data sources include
websites, records from leasing
companies, and on-road vehicle
tests. Based on this data, the study
concludes that the divergence
between real-world and official
CO 2 values of new cars increased
from about 8 percent in 2001 to 40
percent in 2014 (see Figure 1).
8
7.9
7.8
7.8
7.8
7.8
7.8
7.8
7.3
7.1
7.1
7.0
6.9
6.9
6.8
-2% change since 2009
7.7
6.6
6
7.3
6.2
7.2
7.2
7.2
7.2
7.2
-15% change since 2009
6.0
5.8
5.6
5.4
5.3
4
2
EU average: Official values
0
2000
EU average: Estimated real-world values
based on Spritmonitor.de data
2002
2004
2006
2008
2010
2012
2014
Vehicle build year
Figure 2. Development of average official and real-world fuel consumption values of
new European passenger cars.
by 15 percent through 2014, while
real-world values only decreased by
2 percent (see Figure 2). A closer
look at individual vehicle models
helps explain this trend.
Performance of
individual models
Virtually all models in the European
market show a growing divergence
b e t we e n o n - r o a d a n d o f f i c i a l
fuel consumption. Nonetheless,
while this is a systemic, industrywide problem, an examination of
individual models reveals that the
divergence can vary significantly
between different models.
Figure 3 and 4 show the development of official and real-world fuel
consumption values for twenty of
the most popular car models in
Germany from 2001 to 2014.2 Each
model’s share of the German new car
2
For two of the best-selling models, the
Mini Cooper Mini (3 percent market share)
and Fiat Punto (2 percent market share),
the calculation of real-world values was
not possible due to insufficient data. The
analysis thus covers 20 of the 22 best-selling
car models.
2 INTERNATIONAL COUNCIL ON CLEAN TRANSPORTATION market is presented in the graphs.
T h e t we n t y m o d e l s re p re s e n t
roughly 40 percent of all passenger
cars registered in Germany during
this time. Official fuel consumption values were calculated as
gasoline consumption equivalents
of the sales-weighted average CO 2
values of both diesel and gasoline
vehicles. 3,4 Real-world values were
based on data from Spritmonitor.de,5
a free web service that allows users
to track their fuel consumption by
entering odometer readings and the
amount of fuel added during fill-ups.
For each model, fuel consumption values of gasoline and diesel
variants were adjusted by the gap
observed in Spritmonitor.de data to
arrive at an estimate of real-world
fuel consumption.
3
The ICCT, “European Vehicle Market
Statistics,” http://eupocketbook.theicct.org/
4CO2 values of diesel and gasoline cars
were converted to gasoline consumption
equivalents using a conversion factor of 1 l
gasolline/100 km ≈ 23.4 g CO2 /km.
5See www.spritmonitor.de
WORKING PAPER 2015-8
REAL-WORLD FUEL CONSUMPTION OF POPULAR EUROPEAN PASSENGER CAR MODELS
10
8
Audi A3 (1.7% market share)
10
Audi A4 (2.3% market share)
REAL-WORLD
REAL-WORLD
2009
-0.6%
8
2009
-4.2%
6
OFFICIAL
OFFICIAL
-16.4%
6
-21.5%
Nmin = 102
Nmax = 273
4
2000 2002 2004 2006 2008 2010 2012
2014
Nmin = 48
Nmax = 376
4
2000 2002 2004 2006 2008 2010 2012
BMW 3-series (2.7% market share)
Audi A6 (1.3% market share)
10
REAL-WORLD
2014
10
2009
REAL-WORLD
-3.8%
OFFICIAL
8
8
2009
-20.1%
6
Fuel consumption (l gasoline/100km equivalents)
6
4
2000 2002 2004 2006 2008 2010 2012
+0.9%
-17.6%
Nmin = 34
Nmax = 221
4
2000 2002 2004 2006 2008 2010 2012
8
REAL-WORLD
2009
-5.8%
6
OFFICIAL
-17.0%
Nmin = 65
Nmax = 345
2014
Ford Focus (1.9% market share)
REAL-WORLD
4
2000 2002 2004 2006 2008 2010 2012
10
2009
REAL-WORLD
8
OFFICIAL
-23.6%
Nmin = 139
Nmax = 484
4
2000 2002 2004 2006 2008 2010 2012
10
2009
+2.6%
8
OFFICIAL
6
-23.1%
Nmin = 32
Nmax = 161
2014
Mercedes-Benz C-Class (2.4% market share)
REAL-WORLD
4
2000 2002 2004 2006 2008 2010 2012
10
REAL-WORLD
-11.0%
8
OFFICIAL
-30.0%
-3.1%
OFFICIAL
-21.8%
6
Nmin = 27
Nmax = 156
Nmin = 71
Nmax = 270
4
2000 2002 2004 2006 2008 2010 2012
2014
Mercedes-Benz E-Class (1.8% market share)
2009
2009
6
2014
Mercedes-Benz A-Class (1.7% market share)
-13.8%
6
2014
Ford Fiesta (1.5% market share)
8
6
10
4
2000 2002 2004 2006 2008 2010 2012
10
REAL-WORLD
2009
8
2014
BMW 5-series (1.4% market share)
OFFICIAL
-12.5%
Nmin = 89
Nmax = 590
Nmin = 30
Nmax = 189
10
-0.8%
OFFICIAL
2014
4
2000 2002 2004 2006 2008 2010 2012
2014
Build Year
Figure 3: Official and real-world fuel consumption values of popular car models in Germany. Arrowheads mark the timing of major
technical overhauls. Minimum and maximum number of Spritmonitor.de entries per year presented in the bottom-left corners.
WORKING PAPER 2015-8
INTERNATIONAL COUNCIL ON CLEAN TRANSPORTATION 3
REAL-WORLD FUEL CONSUMPTION OF POPULAR EUROPEAN PASSENGER CAR MODELS
10
8
Opel Astra (2.6% market share)
REAL-WORLD
10
2009
+1.0%
Opel Corsa (2.0% market share)
8
2009
+0.3%
REAL-WORLD
6
4
10
8
Fuel consumption (l gasoline/100km equivalents)
6
4
10
8
OFFICIAL
-16.6%
Nmin = 72
Nmax = 513
2000 2002 2004 2006 2008 2010 2012
2014
Peugeot 206, 207, 208 (2.3% market share)
REAL-WORLD
4
10
2000 2002 2004 2006 2008 2010 2012
REAL-WORLD
-10.4%
-20.5%
2000 2002 2004 2006 2008 2010 2012
2014
Škoda Octavia (1.3% market share)
4
10
2009
OFFICIAL
6
6
2000 2002 2004 2006 2008 2010 2012
2014
Toyota Yaris (1.4% market share)
8
REAL-WORLD
-27.5% 6
Nmin = 96
Nmax = 538
2000 2002 2004 2006 2008 2010 2012
-15.9%
Nmin = 83
Nmax = 347
OFFICIAL
10
2009
-18.8%
Nmin = 13
Nmax = 271
2014
Škoda Fabia (1.4% market share)
-11.3%
4
-12.5%
OFFICIAL
Nmin = 35
Nmax = 309
8
2009
OFFICIAL
REAL-WORLD
6
2014
VW Golf (5.8% market share)
4
10
2009
OFFICIAL
Nmin = 18
Nmax = 238
+4.8%
-8.4%
2000 2002 2004 2006 2008 2010 2012
2014
VW Passat (2.6% market share)
REAL-WORLD
8
REAL-WORLD
8
2009
2009
-4.9%
6
OFFICIAL
10
8
Nmin = 417
Nmax = 1,058
2000 2002 2004 2006 2008 2010 2012
2014
VW Polo (2.4% market share)
REAL-WORLD
-18.9%
6
-21.7%
4
Nmin = 53
Nmax = 396
4
10
2000 2002 2004 2006 2008 2010 2012
REAL-WORLD
8
4
2009
-8.2%
2009
OFFICIAL
Nmin = 93
Nmax = 518
2000 2002 2004 2006 2008 2010 2012
2014
VW Touran (1.5% market share)
-8.0%
6
-0.3%
OFFICIAL
OFFICIAL
-16.6%
6
-19.2%
2014
4
Nmin = 68
Nmax = 241
2000 2002 2004 2006 2008 2010 2012
2014
Build Year
Figure 4. Official and real-world fuel consumption values of popular car models in Germany (continued). Arrowheads mark the timing
of major technical overhauls. Minimum and maximum number of Spritmonitor.de entries per year presented in the bottom-left corners.
4 INTERNATIONAL COUNCIL ON CLEAN TRANSPORTATION WORKING PAPER 2015-8
REAL-WORLD FUEL CONSUMPTION OF POPULAR EUROPEAN PASSENGER CAR MODELS
All models included in the analysis
show a decrease in official fuel consumption values from 2001 to 2014.
This trend is particularly pronounced
for the Mercedes-Benz C-Class and
the BMW 5-series, which achieved a
40 percent decrease in official fuel
consumption values between 2001
and 2014. These reductions do not
necessarily translate into fuel savings
on the road: the divergence between
real-world and official fuel consumption values ranged from 33 to 51
percent in 2014.
The analysis of individual car models
reveals that technical overhauls (see
arrowheads in Figure 3 and Figure
4), particularly after EU-wide CO 2
standards were introduced in 2009,
are often followed by sharp decreases
in official fuel consumption values
while real-world values typically do
not decrease by the same magnitude.
This development is particularly
pronounced for the VW Passat
after the model generation B7 was
introduced in 2010. The facelift was
followed by a 1.0 l/100 km drop in
official fuel consumption values but
real-world performance remained
virtually unchanged. Other models
such as the Audi A4, Ford Fiesta,
M e rce d e s - B e n z A- C l a ss , Š ko d a
Octavia, and VW Golf show similar
increases in the divergence between
real-world and on-road fuel consumption values after technical overhauls.
Figure 5 summarizes the reduction
in official and real-world fuel consumption of the 20 selected models
from 2009 to 2014. Five models out
of the top 20 — the BMW 5-series,
Mercedes-Benz A-Class, Opel Astra,
Opel Corsa, and Toyota Yaris —
actually increased real-world fuel
consumption since EU-wide CO 2
standards were introduced in 2009.
Another three models — the Audi
Real−world fuel consumption change, 2009−2014 [%]
5
Toyota Yaris
Mercedes−Benz A−Class
BMW 5−series
0
VW Passat
Mercedes−Benz E−Class
VW Golf
VW Polo
-10
Audi A4
Opel Corsa
BMW 3−series
Audi A6
Audi A3
−5
Opel Astra
Mercedes−Benz C−Class
Ford Fiesta
VW Touran
Škoda Fabia
Škoda Octavia
Ford Focus
-15
Peugeot 206, 207, 208
−20
−30
−25
−20
−15
−10
−5
Official fuel consumption change, 2009−2014 [%]
Small
Lower medium
Real-world = official reduction
Medium
Upper medium
Real-world = 0.5*official reduction
Figure 5. Reduction in official and real-world fuel consumption since 2009 for 20
popular car models. Data points are colored by vehicle segment. The two lines mark
the 1:1 and 1:2 ratios between real-world and official fuel consumption reductions.
WORKING PAPER 2015-8
A4, BMW 3-series, and VW Passat
— made little progress, with less
than one percent real-world fuel consumption reductions in the same time
period. Among the models evaluated,
the Peugeot 206-208 had the highest
reduction in real-world fuel consumption values since 2009 (about 19
percent). The Ford Focus, MercedesBenz C-Class, Skoda Fabia, and
Skoda Octavia all reduced real-world
fuel consumption by more than 10%
since 2009.
Reasons for
the growing gap
Real-world driving is a generic term
that covers the wide range of driving
conditions that vehicles are subject
to during actual use. The real-world,
on-road fuel consumption of cars
varies depending on vehicle and road
characteristics, driving style, and environmental conditions. Nonetheless,
when looking at real-world fuel consumption data from a large numbers
of vehicles, the results of the vast
majority of vehicles tend to cluster
around a central estimate, and official
fuel consumption values have become
increasingly unrepresentative of this
estimate over time. More importantly,
average real-world driving characteristics do not change significantly
from year to year and, thus, should
have little impact on the trends from
one year to the next.
Spritmonitor.de data show that the
share of different driving styles has
remained fairly constant over time,
indicating that behavioral changes
are not a viable explanation for the
increasing gap.6 Figure 2 shows that
driving style, ranging from economical
to speedy driving, significantly
impacts fuel consumption. According
to Spritmonitor.de data, economical
driving on average reduces fuel consumption by 7 percent compared
to balanced driving, while speedy
6 Spritmonitor.de users can select one of three
driving styles (economical, balanced, or
speedy) when entering data after fill-ups.
INTERNATIONAL COUNCIL ON CLEAN TRANSPORTATION 5
driving has the opposite effect with
a 6 percent increase (both effects
being constant over time). In other
words, not even economical drivers
can achieve the fuel efficiency
reported by manufacturers, and the
gap has been widening.
It should be noted that EU CO 2
targets apply to the average for all
vehicles sold per year by each manufacturer. Vehicle manufacturers are
therefore not obliged to reduce fuel
consumption values for every model
every year and most vehicles are
redesigned every five years or so,
with occasional significant mid-cycle
facelifts. Following the introduction
of all-new model generations and
model facelifts, official fuel consumption values typically decline (see
Figures 3 and 4). Real-world fuel consumption values, however, frequently
do not follow this trend, indicating
that improvements in fuel efficiency
measured during laboratory testing
do not fully materialize on the road.
The pattern of sudden increases in
the divergence between real-world
and official fuel consumption values
indicates that the growing gap is a
product of unrealistic official fuel
consumption values.
A joint study by Element Energy
and the ICCT identified four key
factors for the increasing divergence
between real-world and official
fuel consumption values in the EU.7
These factors are primarily related
to different flexibilities in the vehicle
testing procedure:
• Road load determination. The
aerodynamic and rolling resistances that a vehicle has to
overcome during driving, the
so-called road load, have to be
determined prior to laboratory
t e s t i n g . M a n u f a c t u re r s a re
increasingly exploiting flexibilities
and tolerances in this stage, like
7
Fuel consumption [l gasoline/100 km equivalents]
REAL-WORLD FUEL CONSUMPTION OF POPULAR EUROPEAN PASSENGER CAR MODELS
10.0
8.0
Real-world: speedy
Real-world: balanced
Real-world: economical
6.0
Official
4.0
2000
2002
2004
2006
2008
2010
2012
2014
Build Year
Figure 6. Real-world fuel consumption values for different driving styles, including
economical, balanced, and speedy driving (based on Spritmonitor.de data).
removing side mirrors, reducing
ve h i c l e we i g h t , a n d u s i n g
tolerances in the measurement
procedure to their advantage.
• Laboratory test design. Vehicles
are tested under conditions that
are unrepresentative of average
re a l -wo r l d co n d i t i o n s (e.g . ,
ambient test temperatures of 20
to 30°C) and regulations allow
for flexibilities and tolerances that
manufacturers are increasingly
exploiting.
• New technologies. Some fuelsaving technologies, such as
stop-start systems and hybrid
powertrains, tend to be more
effective during laboratory testing
than during real-world driving.
• Other parameters. Auxiliary
systems, such as air-conditioning and on-board entertainment systems, are switched
off during vehicle testing
but consume energy during
real-world operation.
Stewart, A., et al., “Impacts of real-world
driving on emissions from UK cars and vans,”
https://www.theccc.org.uk/publication/
impact-of-real-world-driving-emissions/
6 INTERNATIONAL COUNCIL ON CLEAN TRANSPORTATION Conclusions and
policy implications
The analysis of 20 popular vehicle
models demonstrates that reductions
in real-world fuel consumption fall
short of the improvements in official
values. Moreover, official fuel cons u m p t i o n va l u e s h ave b e co m e
increasingly unrepresentative of
real-world performance over time.
The pattern of abrupt increases in the
gap after model overhauls indicate
that unrealistic official fuel consumption values are the source of the
growing gap.
The growing divergence between
official and real-world fuel consumption values is primarily a result
of the exploitation of flexibilities in
the current testing procedure. A
new test procedure, the Worldwide
Harmonized Light Vehicles Test
Procedure (WLTP), will replace the
current testing procedure in the EU
in 2017. While the WLTP will be an
improvement, it will not by itself
resolve all known issues. Even with the
introduction of the WLTP, fuel consumption tests will still be conducted
in laboratories on pre-series vehicles
specially prepared by manufacturers
WORKING PAPER 2015-8
REAL-WORLD FUEL CONSUMPTION OF POPULAR EUROPEAN PASSENGER CAR MODELS
(so-called golden cars) and auxiliary
systems will continue to be turned off.
While the exploitation of flexibilities
in the current testing procedure
ex p l a i n s t h e g row i n g g a p, t h e
regulatory and institutional context
does little to prevent this development .8 Currently, manufacturers can
shop around in the EU member states,
selecting a type-approval authority
as well as a technical service (thirdparty testing company) to certify
their vehicles. This situation creates
a conflict of interest, potentially
incentivizing type-approval authorities and technical services to support
manufacturers in producing favorable
emission testing results to attract and
retain the manufacturers’ business.
E st a b l i s h i n g a n E U -w i d e t y p e approval authority, acting as a neutral
party between vehicle manufacturers and technical service companies
8 For more details, see Mock, P., German, J.,
“The future of vehicle emissions testing”,
http://www.theicct.org/future-of-vehicle-testing
WORKING PAPER 2015-8
— and being able to mandate vehicle
recalls and impose financial penalties
for non-compliance — is therefore
seen as a critical step towards more
realistic emissions and fuel consumption figures.
low emissions of NOX during
conditions that resemble real-world
use more closely than laboratory
cycles. This system of on-road testing
could be extended to cover vehicle
CO2 emissions.
Furthermore, the current typeapproval process relies solely on
laboratory testing of “golden cars”.
In-use conformity testing of randomly
selected vehicles would ensure that
vehicles meet their specified fuel
consumption value throughout their
useful life. Another measure that
should be combined with in-use
compliance inspections is on-road
fuel consumption testing. For nitrogen
oxide (NOx) emissions, the European
Commission adopted the Real-Driving
Emissions (RDE) procedure, making
use of portable emission measurement systems (PEMS) to verify that
light-duty vehicles have reasonably
More generally, the current lack of
transparency in the type-approval
process and real-world performance
of cars impedes independent verification of fuel consumption values.
For instance, road load values are a
vital component of vehicle testing
but are not publically available.
There is also no EU-wide source of
real-world fuel consumption values.
I n t h e U. S . , t h e E nv i ro n m e n t a l
Protection Agency and Department
of Energy created the FuelEconomy.
gov website,9 allowing consumers to
compare real-world and official fuel
consumption values before making
purchasing decisions.
9See https://www.fueleconomy.gov/mpg
INTERNATIONAL COUNCIL ON CLEAN TRANSPORTATION 7