CEN/TR 18238:2026

SLOVENSKI STANDARD
01-oktober-2025
Goriva za motorna vozila - Bencin E20 - Ozadje zahtevanih parametrov, njihovih
omejitev in utemeljitve
Automotive fuels - E20 petrol - Background on the parameters required, their respective
limits and justification
Kraftstoffe - E20 Ottokraftstoffe - Hintergrund zu den erforderlichen Parametern, ihren
jeweiligen Grenzwerten und ihrer Bestimmung
Carburants automobiles - Essence E20 - Historique des paramètres requis, leurs limites
respectives et leur justification
Ta slovenski standard je istoveten z: FprCEN/TR 18238
ICS:
75.160.20 Tekoča goriva Liquid fuels
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

FINAL DRAFT
TECHNICAL REPORT
FprCEN/TR 18238
RAPPORT TECHNIQUE
TECHNISCHER REPORT
August 2025
ICS 75.160.20
English Version
Automotive fuels - E20 petrol - Background on the
parameters required, their respective limits and
justification
Kraftstoffe - E20 Ottokraftstoffe - Hintergrund zu den
erforderlichen Parametern, ihren jeweiligen
Grenzwerten und ihrer Bestimmung

This draft Technical Report is submitted to CEN members for Vote. It has been drawn up by the Technical Committee CEN/TC 19.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a Technical Report. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a Technical Report.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. FprCEN/TR 18238:2025 E
worldwide for CEN national Members.

FprCEN/TR 18238:2025 (E)
Contents Page
European foreword . 4
Introduction . 5
1 Scope . 7
2 Terms and definitions . 7
3 Considerations for generally applicable requirements – Table 1 of
FprCEN/TS 18227:2025 . 7
3.1 Introduction . 7
3.2 Research octane number (RON) and motor octane number (MON) . 9
3.2.1 Octane and auto-ignition . 9
3.2.2 Impact of RON . 10
3.2.3 Impact of MON and fuel sensitivity . 12
3.2.4 Determining minimum octane limits in the E20 CEN/TS 18227 . 13
3.3 Lead content . 14
3.4 Density . 14
3.5 Sulfur content . 14
3.6 Manganese content. 14
3.7 Oxidation stability . 14
3.8 Existent gum content . 14
3.9 Corrosion protection . 14
3.9.1 Corrosion by water . 14
3.9.2 Corrosion by sulfur. 15
3.10 Water content . 15
3.11 Appearance . 16
3.12 Hydrocarbon type content and final boiling point (FBP) . 16
3.13 Benzene content . 17
3.14 Oxygen content . 17
3.15 Oxygenates . 18
4 Considerations for climate dependent requirements – Table 2 of the
FprCEN/TS 18227:2025 . 18
4.1 Volatility requirements table . 18
4.2 Overview of volatility limit proposals . 19
4.3 E70 . 19
4.4 E100 . 20
4.5 E150 . 22
4.6 Final Boiling Point (FBP) . 22
4.7 Distillation residue . 23
4.8 Vapour Lock Index (VLI) . 23
5 Considerations about vapour pressure requirements . 23
5.1 Vapour pressure limits . 23
5.2 Vapour pressure waiver – volatility Class A . 23
6 Test method validity . 25
Annex A (informative) Overview discussion oxygenates in CEN/TC 19 WG21 (Specification for
unleaded petrol) . 26
FprCEN/TR 18238:2025 (E)
A.1 Elastomer compatibility . 26
A.2 Impact of oxygenates on octane and other performance metrics . 28
A.2.1 General . 28
A.2.2 Southwest Research Institute (SwRI) Studies . 30
A.2.3 NREL Study . 38
A.3 Oxygenate effects on WTW GHG emissions . 48
A.4 Studies of oxygenate effects on pollutant emissions . 50
A.5 Oxygenate limits . 52
A.5.1 Ethanol . 52
A.5.2 C5+ ethers . 55
A.5.3 Methanol . 57
A.5.4 Other oxygenates . 57
Annex B (informative) Test method validity E20 petrol . 58
Bibliography . 62

FprCEN/TR 18238:2025 (E)
European foreword
This document (FprCEN/TR 18238:2025) has been prepared by Technical Committee CEN/TC 19
“Gaseous and liquid fuels, lubricants and related products of petroleum, synthetic and biological origin”,
the secretariat of which is held by NEN.
This document is currently submitted to the Vote on TR.

FprCEN/TR 18238:2025 (E)
Introduction
Commonly available petrol blends include E5 (corresponding to blends oxygenated with C5+ fuel ethers
(e.g. MTBE, ETBE, TAME) up to 22 % (V/V) and/or up to 5 % (V/V) ethanol content) and E10
(corresponding to blends oxygenated with C5+ fuel ethers (e.g. MTBE, ETBE, TAME) up to 22 % (V/V)
and/or up to 10 % (V/V) ethanol content). Both fuel specifications are defined in the European petrol
standard EN 228 [1].
The Renewable Energy Directive (RED) and subsequent amendments encourage the use of renewable
fuels as blending components in petrol. At the CEN/TC 19 meeting in May 2011, a priority was placed on
“E10+” petrol in order to be prepared for future market and legislative decisions. It was agreed that a
detailed assessment of biofuels and blends in Europe over the coming decade was needed that should be
prepared through a multi-stakeholder approach. To develop this longer-term vision, CEN/TC 19 worked
together as Industry and Stakeholder partners to complete this assessment and outline the possible
constraints and advantages of a future E10+ petrol. This led to the publication of CEN/TR 16514 [2].
In April 2023, European regulation 2023/851 was adopted that dictates that all new cars and vans
registered in Europe after 2035 should not produce any tailpipe CO emissions, which effectively means
a ban on new light-duty vehicles powered by internal combustion engines (ICEs) using fuels containing
carbon. However, light-duty vehicles equipped with ICEs will continue to operate for several decades, so
renewable fuels are needed in increasing amounts to replace fossil fuels and help meet the increasing
targets for lower carbon and greenhouse gas emissions from the transport sector.
In 2022, a Task Force (TF) under CEN/TC 19 was formed with the intent of developing consensus on
technical requirements for an E10+ fuel specification, with the following terms of reference:
The scope of work of the TF is to ‘study the DIN and CUNA work to develop consensus on technical
requirements for an E10+ fuel specification what could be formed into a CEN/TS (Technical Specification)
and supported with sufficient technical substantiation to be written into a CEN/TR (Technical Report)’. In
layman’s words: the group of experts shall take what has been done already and draft a fuel quality
specification for petrol blended with more than 3,7 % (m/m) of oxygen-containing products. That shall be
presented to CEN/TC 19 WG21 for discussion, agreement and continual balloting. In parallel, all
deliberations and discussions around each property, limit as well as test method applicability, should be
recorded to become an official technical background report by CEN.
Motivated by the decarbonisation of the transport sector, several organisations executed studies with
alternative fuels that formed the basis of this Technical Specification. In 2017, ENI and FCA (Fiat) started
a study on an alternative alcohol-based fuel (15 % methanol and 5 % ethanol – A20) to validate a fuel
with a maximum oxygen content of 10 % (m/m). The fuel was tested in five cars. Eventually, CUNA (Italian
Technical Commission for Unification in the Automotive Industry) published a specification for this A20
fuel [3]. In 2021 and 2022, DIN executed a study with the intention to align on product properties options
for a petrol fuel containing ~20 % ethanol [4]. Furthermore, a CEN Technical Report (CEN/TR 16514)
was prepared by TC/19 in 2013 “Automotive fuels – Unleaded petrol containing more than 3,7 % (m/m)
oxygen – Roadmap, test methods and requirements for E10+ petrol”. That report discusses the
considerations required for the introduction of E20 petrol, covering the legislative, environmental,
production and operation factors.
This document is concerned with explaining the rationale underpinning the technical limit values and
related controls that are defined in the E20 CEN/TS 18227 as discussed in the CEN E20 Task Force and
adopted in CEN/TC 19 WG21 (specification for unleaded petrol). Some work was done in consideration
of the applicability of test methods employed in EN 228 to the E20 CEN/TS 18227 and is recorded in
CEN/TR 16514 [2], with an update given in this report. At the time of publication of this document, petrol
with a higher ethanol content than 10 % (V/V) or oxygen content higher than 3,7 % (m/m) is not allowed
FprCEN/TR 18238:2025 (E)
on the market in EU countries according to the Fuel Quality Directive (FQD) [5], therefore revisions to
the FQD in these aspects would be required to enable E20 petrol to be placed on the market in the
European Union.
NOTE In the TF it was agreed to name the new specification ‘E20’ instead of ‘E10+’ to better align with standard
practices in CEN and align with pump marking practice in Europe e.g. E5 and E10 existing petrol grades whereby
the petrol fuel grades are defined by the maximum allowable ethanol content.

FprCEN/TR 18238:2025 (E)
1 Scope
This document gives the technical rationale for the requirements and parameters for petrol with a
minimum oxygen content of 3,7 % (m/m), a maximum of 8,0 % (m/m) and a maximum of 22 % (V/V) fuel
ethers with 5 or more carbons and/or 20,0 % (V/V) ethanol as defined in CEN/TS 18227.
NOTE 1 This document is directly related to CEN/TS 18227 and will be updated once further publications take
place.
NOTE 2 For the purpose of this document, the terms “% (m/m)” and “% (V/V)” are used to represent respectively
the mass fraction and the volume fraction.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp/
— IEC Electropedia: available at https://www.electropedia.org/
3 Considerations for generally applicable requirements – Table 1 of
FprCEN/TS 18227:2025
3.1 Introduction
Table 1 shows the requirements and test methods for E20 petrol as defined in CEN/TS 18227. The clauses
below explain the background and decisions around these parameters.
Table 1 — Requirements and test methods for petrol with a minimum oxygen content of
3,7 % (m/m) and a maximum oxygen content of 8,0 % (m/m) from the E20
FprCEN/TS 18227:2025
a
Property Units Limits Test method

Min Max
b
Research octane number, RON  98,0 -- EN ISO 5164
b
Motor octane number, MON  85,0 -- EN ISO 5163
Lead content mg/l -- 5,0 EN 237
EN 13723
c 3
Density (at 15 °C) kg/m 720,0 775,0 EN ISO 3675
EN ISO 12185
c
Sulfur content mg/kg -- 10,0 EN ISO 13032
EN ISO 20846
EN ISO 20884
d
Manganese content mg/l -- 2,0 EN 16136
Oxidation stability minutes 360 -- EN ISO 7536
FprCEN/TR 18238:2025 (E)
a
Property Units Limits Test method

Existent gum content mg/100 m -- 5,0 EN ISO 6246
(solvent washed) l
Copper strip corrosion rating Class 1 EN ISO 2160
(3 h at 50 °C)
Water content % (m/m)  0,200 EN 15489
EN 15692
e
Appearance  clear and bright Visual inspection
c
Hydrocarbon type content % (V/V)   EN 15553
EN ISO 22854
- olefins  -- 18,0
EN 18015
- aromatics  -- 35,0
c
Benzene content % (V/V) -- 1,00 EN 12177
EN ISO 22854
EN 18015
c i j
Oxygen content  % (m/m) 3,7 8,0 EN 1601
i
EN 13132
EN ISO 22854
EN 18015
c
Oxygenates content % (V/V)   EN 1601
EN 13132
f
- methanol -- 3,0
g k --
EN ISO 22854
- ethanol  20,0
- iso-propyl alcohol -- 12,0
EN 18015
- iso-butyl alcohol -- 15,0
- tert-butyl alcohol -- 15,0
- ethers (5 or more C atoms) -- 22,0
h
- other oxygenates -- 15,0
FprCEN/TR 18238:2025 (E)
a
Property Units Limits Test method

a
See also 6.6.1 in FprCEN/TS 18227:2025.
b
A correction of 0,2 for MON and RON shall be subtracted for the calculation of the final result, before reporting
according to the requirement of the European Fuels Directive 98/70/EC [5], including subsequent
Amendments [6], [7], [8], [9], [10]. [11] and [12]. See also 6.5 and 6.6.2 in FprCEN/TS 18227:2025.
c
See also 6.6.2 in FprCEN/TS 18227:2025.
d
See also 6.3.3 in FprCEN/TS 18227:2025.
e
Appearance shall be determined at ambient temperature.
f
Stabilising agents shall be added.
g
Ethanol when used as a blending component shall conform to EN 15376 (see 6.1 in FprCEN/TS 18227:2025).
Stabilising agents may be added.
h
Other mono-alcohols and mono-ethers with a final boiling point no higher than prescribed in Table 2 of
FprCEN/TS 18227:2025.
i
EN 13132 contains no precision statement for an oxygen content above 3 % (m/m). Based on the available
round robin data CEN/TC 19 accepts an average reproducibility value of R = 0,37 for all test results above that
level.
j
EN 1601 is applicable for samples containing > 15 % (V/V) of ethers using a dilution step lowering the amount
of ethers to a value below 15 % (V/V).
k
No minimum limit for ethanol content has been set, but this may be opened for review at a later stage. More

information can be found in this document.

3.2 Research octane number (RON) and motor octane number (MON)
3.2.1 Octane and auto-ignition
The octane number is a measure of the ability of a petrol fuel running in a spark ignition engine to resist
auto-ignition, [13, 14]. Auto-ignition occurs when rising temperature and pressure from the primary
combustion causes unburned fuel to ignite ahead of the flame front. This uncontrolled secondary
combustion causes pressure in the cylinder to spike and causes the auto-ignition (or knock) to occur. This
is most likely to occur at high speed/high load conditions. A similar undesirable condition is called pre-
ignition, when the fuel ignites on its own before the spark. This is typically a problem under low-speed,
high-load conditions. Both knock and pre-ignition can cause engine damage and therefore vehicle
manufacturers tune engines to avoid such adverse running conditions when the engine runs on lower
octane fuels. Such de-tuning reduces the fuel efficiency potential of the engine, hence increases Tank-To-
Wheels (TTW) CO emissions. Conversely, where higher octane fuels are available, vehicle manufacturers
can tune engines to harvest the efficiency benefits such as: running more thermodynamically efficient
ignition timing, employing higher compression ratios, running higher loads and reducing enrichment
which can all result in lower TTW CO emissions from the vehicle [16].
FprCEN/TR 18238:2025 (E)
Figure 1 — CO2 and fuel consumption benefits of RON in an adapted engine [16]
The octane number of a fuel is traditionally measured in engine tests compared to references from n-
heptane with an octane number of zero and isooctane (2,2,4-trimethylpentane) with an octane number
of 100. The Research Octane Number (RON) is designed to emulate typical driving conditions whereas
the Motor Octane Number (MON) is designed to be indicative of high-speed, high-load performance and
tends to be around 10 points lower than RON. The arithmetic mean of the MON and RON is used to define
octane quality in some countries and is known as the AKI (Anti-Knock Index). Furthermore, the difference
between RON and MON is sometimes referred to when discussing octane rating and is known as the fuel
‘sensitivity’.
3.2.2 Impact of RON
Use of higher RON fuels has since long been associated with performance enhancements such as benefits
in acceleration and power and in some publications, increasing Sensitivity (RON-MON), has been shown
to deliver greater benefits in modern vehicles [14]. The latter focus has turned to determining the
potential for fuel efficiency benefits of octane in both standard [15] and optimized [16] vehicles. Both
performance and fuel efficiency benefits tend to be most prevalent at high duty driving conditions. In [15]
benefits in brake-specific fuel consumption (BSFC) of up to 6,7 % were observed in a high-performance
Euro 6 saloon at full load steady-state conditions with a RON 99 fuel compared to a RON 95 fuel. In
another part of the test programme a fleet of 5 Euro 6 direct injection turbo-charged vehicles with engine
displacements ranging from (1,0 – 2,0) l were tested at full load steady-state with fuels of RON 95, 97 and
100. Fleet average benefits in BSFC of up to 2 % were observed for the RON 97 fuel and of up to 4,1 % for
RON 100 fuel compared to the RON 95 fuel, Figure 2. Given that BSFC is directly proportional to the CO
emissions of vehicles, such benefits would result in similar reductions in CO emissions on a TTW basis.
FprCEN/TR 18238:2025 (E)
Figure 2 — Fleet average reduction in BSFC with higher RON fuel
In the Concawe study [16] fuel efficiency benefits in a high-compression (CR 12.2) downsized direct
injection turbocharged engine scaled linearly with RON and benefits of 3,9 % were observed over real
driving conditions with RON 102 fuel vs RON 95 fuel. Further materials were presented by Concawe [17]
describing RON effects on fuel consumption and brake efficiency in an adapted and non-adapted engine.
The results showed how benefits scaled linearly with RON between 95 and 102 and that benefits
increased with drive cycle severity and with the level of engine adaption.

FprCEN/TR 18238:2025 (E)
Figure 3 — Summary of RON benefits on brake efficiency with respect to RON, driving cycle
severity and level of engine adaptation
Similar findings were reported from Horizon 2020 study [19] in a fleet of vehicles including one vehicle
with optimized engine. Efficiency and CO benefits from higher RON scaled with test cycle severity and
level of engine adaptation.
3.2.3 Impact of MON and fuel sensitivity
MON is also increased when blending oxygenates into typical hydrocarbon petrol fuel, [20] though to a
lesser extent than the impact on RON. However, reducing fuel sensitivity (RON-MON) has been associated
with reducing the benefit potential of increasing RON, as shown in Figure 4 [21]. Furthermore, increasing
fuel sensitivity has been proven to increase the performance benefits associated with high RON fuels [22].
Work done by Total [23] and presented by Concawe [24] showed that increasing MON could also increase
propensity for knock in a high CR (12.5:1) turbocharged engine.
FprCEN/TR 18238:2025 (E)
Figure 4 — Thermal efficiency, crank angle 50 (CA50) and exhaust temperature effects of
different sensitivity fuels, [21]
3.2.4 Determining minimum octane limits in the E20 CEN/TS 18227
Oxygenated fuel components used in petrol such as ethanol and ethers have lower volumetric energy
content compared to their hydrocarbon counterparts owing to their oxygen content and lower carbon
content. Therefore, increasing the minimum octane limit in a high-oxygenate petrol is important to
partially offset the volumetric fuel economy penalty that drivers would otherwise experience from
fuelling with a higher oxygen-content fuel [19]. Splash blending an additional 10 % ethanol to E10 would
result in a 3 RON increase and in this example the same BOB (blendstock for oxygenate blending) could
be used for both E10 and E20 products. This rationale supports setting RON minimum limit to 98.
Increasing the MON minimum limit would reduce the fuel sensitivity and therefore the potential for
increasing efficiency associated with higher RON fuel. This rationale supports retaining the MON
minimum limit at the FQD point of 85.
In TF meeting #4, a Concawe presentation [18] set out potential refining CO benefits of utilising the RON
benefit of higher oxygenate blending to reduce the RON of the BOB, instead of delivering a higher RON
reduction for production of an
finished fuel. This benefit was determined as being between 0-1 % CO2
E20 petrol with RON 95 vs an E20 petrol with RON 98. This WTT benefit would be at the expense of any
TTW benefit that could be delivered by a higher RON fuel. In response to this point, in a presentation from
a vehicle manufacturer [25] it was argued that reducing the RON of the BOB could result in the use of
alternative BOBs containing high boiling paraffinic and naphthenic components characterised by
relatively long evaporation times. The use of such components could increase the risk of LSPI.
On consideration of all the evidence presented, the TF decided on the following for the draft TS minimum
octane limits:
— RON: 98
— MON: 85
FprCEN/TR 18238:2025 (E)
3.3 Lead content
Lead content for the E20 CEN/TS 18227 is set to a maximum limit of 5 mg/l. This is in line with the limit
set in EN 228 which in turn aligns with the maximum allowed in the FQD. In the TF discussions, there
were no proposals to deviate from a 5 mg/l limit as the addition of higher oxygenate content is not
expected to impact lead content. However, it was agreed that any revision of the lead limit agreed in the
EN 228 revision would be adopted for the E20 CEN/TS 18227.
3.4 Density
Limits on density (at 15 °C) for the E20 CEN/TS 18227 is set at a range of (720,0 – 775,0) kg/m . This is
in line with the limits set in EN 228. The density of ethanol sits slightly above the given range (ca.
789,0 kg/m at 20 °C) and the densities of commonly used ethers sit within, towards the lower end, of the
above range (e.g. MTBE 740, ETBE 736 kg/m at 20 °C) and overall, higher oxygenate content up to the
proposed limit of 8 % (m/m) oxygen is not expected to have a large impact on finished fuel density. In the
TF discussions, there were no proposals to deviate from the EN 228 density range.
3.5 Sulfur content
Maximum sulfur content limit for the E20 CEN/TS 18227 is set at 10 mg/kg. This is in line with the limit
set in EN 228 which in turn aligns with the maximum allowed in the FQD. In the TF discussions, there
were no proposals to deviate from a 10 mg/kg limit as the addition of higher oxygenate content is not
expected to impact sulfur content.
3.6 Manganese content
Maximum manganese content limit for the E20 CEN/TS 18227 is set at 2 mg/l. This is in line with the
limit set in EN 228 which in turn aligns with the maximum allowed in the FQD. In the TF discussions, in
addition to the 2 mg/l limit, it was proposed and accepted to add the note “no intentional addition”.
3.7 Oxidation stability
Requirements for oxidation stability for the E20 CEN/TS 18227 were adopted from EN 228 and based on
the induction period test, EN ISO 7536 which is deemed suitable for fuels complying with the E20
CEN/TS 18227 as is already in use for E85 fuels. The minimum induction period agreed for fuels
described by the E20 CEN/TS 18227 is 360 min, as is the limit applied in EN 228.
3.8 Existent gum content
Requirements for existent gum content for the E20 CEN/TS 18227 were adopted from EN 228 as there
were no arguments presented to deviate. Therefore, the maximum limit in the E20 CEN/TS 18227 is
5,0 mg/100 ml.
3.9 Corrosion protection
3.9.1 Corrosion by water
A presentation was given on the corrosion resistance of fuels containing higher ethanol levels. Various
corrosion mechanisms can occur with such fuels, including stress corrosion cracking and corrosion of
steel via trace contaminants (see 3.9.2).
The parameters affecting steel corrosion propensity are controlled in the ethanol specification [27], but
there is no mandatory corrosion testing requirement in EN 228 addressing iron corrosivity by water in
petrol. It was pointed out that there are no inherent issues with corrosion in European (E10) or US (E15)
fuels, but there are corrosion problems in other (developing) markets.
In fuels up to 20 % ethanol, there is an additional risk of corrosion when water separation occurs. The
applicability of the NACE TM0172 [28] steel corrosion test to the E20 CEN/TS 18227 was discussed. This
FprCEN/TR 18238:2025 (E)
test is designed to measure the corrosion resistance of a fuel when water is present. Results of this test
showed a wide variation in corrosion resistance between different market fuels. Poor corrosion
protection properties of a fuel can be mitigated by the application of corrosion inhibitor additives.
Requirements for corrosion inhibitors across different standards were discussed:
— EN 228 (E5/E10) and EN 15293 (E85) [26] state that corrosion inhibitors are required “when there
is a risk of water separation”
— EN 15376 (ethanol specification) [27] recommends “producers consider the use of corrosion
inhibitors”
A proposal was made to either mandate the use of corrosion inhibitors in the E20 CEN/TS 18227 or to
introduce the NACE TM 0172 test in the standard.
A member mentioned that corrosion inhibitors had been linked to deposit formation in fuel systems.
Another member mentioned that corrosion is linked to water concentration, which can vary in the supply
chain, therefore testing corrosion protection anywhere upstream of the retail forecourt could
misrepresent the corrosion performance critical to the end user. Control of water contamination was
deemed to be most significant to achieve corrosion protection.
It was agreed to limit the water content in part to limit the corrosion risk (see 3.10). Furthermore, it was
agreed that the guidance wording for fuel handling that may affect corrosion propensity will be
strengthened as follows in the E20 CEN/TS 18227:
Given the known potential for some petrol to absorb water, the use of anticorrosion additives may be used
to prevent corrosion.
This is particularly important in the case of fuel containing higher ethanol content above 10 % V/V.
Furthermore, fuel complying to this document, contains less than 0,200 % (m/m) water. If a risk of corrosion
be suspected, NACE TM0172 steel corrosion tests can give further guidance towards the use of anticorrosion
additives.
Alternatively, in cases where petrol is expected to encounter humid environments or direct contact with
water, ethanol is considered unsuitable and ethers are used instead. This is particularly relevant for
marine petrol and petrol for vehicles that are likely to sit idle for extended periods of time.
NOTE For further information on preventing contamination by water or sediment that may occur in the supply
chain or for cross-contamination it is advisable to check CEN/TR 15367, Parts 2 and 3 respectively [29, 30].
3.9.2 Corrosion by sulfur
The copper strip corrosion test for rating corrosiveness by active sulfur components (EN ISO 2160) will
be adopted in the E20 CEN/TS 18227 with the requirement ‘class 1’ after 3 hrs testing at 50 °C. This
requirement and limit is in line with EN 228.
3.10 Water content
Water in the fuel can lead to corrosion. Validation results from Bosch show that a water content
significantly above 2,000 mg/kg triggers damage to oxide layers on steel surfaces, leading to higher wear
by tribo-corrosion, for example at fuel injector valve needles. It could also trigger corrosion-induced wear
originating from local cell formation, for example at valve seats.
SGS survey data shows that E10 blends exhibit water contents well below 0,200 % (m/m) on a global
basis. European market survey data presented by Shell (E5-E10 Europe fuel water content 2018-2022,
courtesy of SGS) shows that there is no correlation between ethanol content and water (up to E10). Also,
E20 blends, for example in Thailand, show water contents below 0,200 % (m/m).
FprCEN/TR 18238:2025 (E)
The fuel survey data about the water content of E10 and E20 petrol blends include the additional water
uptake of petrol blends by hygroscopicity that increases with rising ethanol content [31].
Already many fuel system components have been introduced into markets where E20 fuels are present.
Based on the data above, and to protect the vehicle fuel equipment, the water content limit has been set
at 0,200 % (m/m). No evidence was found that the introduction of a water limit of 0,200 % (m/m) would
be problematic for fuel suppliers (Shell presentation). Water housekeeping for fuel distribution and
storage is also important.
The water content limit of maximum 0,200 % (m/m) has also been defined to safeguard against
intentional addition of water. Dilution of ethanol-blended E20 with water would remain undetected as
phase separation of the petrol blend into two phases, a phase rich of water/ethanol and a phase consisting
of ethanol/hydrocarbons, happens at significantly higher water concentrations, e.g. for E15 at above
15 000 mg/kg water (15 °C). The lower phase, rich in ethanol and water, is highly corrosive, the upper
phase consisting predominantly of hydrocarbons and ethanol significantly lacks octane. If suppliers
observe that E20 petrol separates into two phases, it can be the case that the fuel no longer meets the
standard. Exact water tolerance depends on additional factors, e.g. hydrocarbon composition [32].
3.11 Appearance
Requirements for appearance for the E20 CEN/TS 18227 were agreed to be as for EN 228, i.e. ‘clear and
bright’.
3.12 Hydrocarbon type content and final boiling point (FBP)
ACEA and other Task Force members proposed some different limits from EN 228 with respect to
hydrocarbon content, higher aromatics and FBP. These measures were designed to reduce exhaust
particulate emissions and limit the low speed pre-ignition (LSPI). risk. The proposals are summarized in
Table 2 below.
Table 2 — Proposed limits for olefins, aromatics and FBP
Property Limit incumbent in Limit proposed for
EN 228 (if applicable) E20 CEN/TS 18227
Olefin content (% V/V) 18 15
Aromatic content (% V/V) 35 30
C9+ aromatic content (% V/V) N/A 10
C10+ aromatic content (% V/V) N/A 2
Final boiling point (°C) 210 200

In TF meeting #8 a presentation was given that summarized fuel effects on particulate emissions from a
Euro 6 Direct Injection Spark Ignition (DISI) passenger car concluding that C9/10+ aromatics and FBP
had little effect on particulate emissions especially in the presence of gasoline particulate filters (GPFs)
which are typically fitted to modern DISI vehicles in Europe [42].
Another presentation from Concawe reported fuel effects in several Euro 6 vehicles and delivered similar
conclusions, with vehicle technology contributing to broader effects on particulate emissions than fuel
composition [50].
Also, in meeting #8 ACEA presented fuel survey data that showed a strong correlation between C10+
aromatics and FBP and suggested that setting a FBP maximum limit of 200 °C could be used to control
fuel properties most affecting particle production and LSPI risk, see Figure 5.
FprCEN/TR 18238:2025 (E)
Figure 5 — Correlation between FBP and C10+ aromatic content
A Concawe presentation of SGS Summer 2022 market survey data in meeting #8, showed that for 114
fuels sampled, around half would not comply with the proposed C9+ and C10+ limits, therefore applying
such limits could result in substantial changes to fuel production in Europe. Whereas applying an FBP
limit of 200 °C would only affect 22 of 114 fuels.
In TF meeting #9 a presentation was given which showed that fuels with higher FBPs tended to produce
higher incidences of LSPI events. Another presentation showed that, according to data from the BEP525
study, [33] adding 20 % ethanol to 60 different base petrol fuels reduced FBP on average by 3,5 °C.
Furthermore, reducing FBP by lowering the cut temperature between streams shifts quantities from the
petrol to kerosene pool which could be a logical change in the future as petrol demand drops in Europe
due to the impact of electrifying light-duty vehicles.
It was agreed to adopt an FBP maximum limit of 200 °C in the E20 CEN/TS 18227. The olefin and aromatic
content limits from EN 228 are copied into the E20 CEN/TS 18227 and no new limits for C9+ or C10+
limits or control to limit LSPI are adopted, given that the lower FBP maximum provides some of the
benefits that can be achieved from applying limits to the aforementioned qualities, but without the
complexity of adopting additional parameter limits.
3.13 Benzene content
Maximum benzene content limit for the E20 CEN/TS 18227 is set at 1 % (V/V). This is in line with the
limit set in EN 228 which in turn aligns with the maximum allowed in the FQD.
3.14 Oxygen content
Limits for oxygen content were discussed in meeting #4. There was general agreement to set the upper
limit at 8 % (m/m) to enable a maximum ethanol content of 20 % (V/V) which alone would provide 7,4 %
(m/m) oxygen. A higher oxygen content supports the decarbonisation of the transport sector and can be
achieved with various oxygenates. Arguments were made to have the lower oxygen limit set at 0 % (m/m)
to retain maximum fuel manufacturing flexibility and arguments to set the limit to 5 % (m/m) to
FprCEN/TR 18238:2025 (E)
maximize CO benefits and have a more tightly defined range to enable targeted vehicle calibration. An
alternative lower oxygen limit of 3,7 % (m/m) was proposed and adopted.
3.15 Oxygenates
Considerations for oxygenates and their respective limits were discussed at length in the Task Force and
ultimately adopted in WG 21. The different arguments are summarized in Annex A. Discussions covered
the impact of oxygenates on elastomers, engine performance, efficiency, pollutant and CO emissions. In
particular, there were differing views on the merits of including a lower ethanol content limit, but it was
concluded that no lower limit would be included in the TS. Instead it was agreed to introduce a footnote
indicating that this could be reviewed later. The maximum limit for ethanol was set at 20 % (V/V) and a
maximum C5+ ether limit was maintained at 22 % (V/V). There were no proposals to deviate from EN 228
upper limits for iso-propyl alcohol, iso-butyl alcohol, tert-butyl alcohol, ‘other oxygenates’ (excluding C5+
ethers and ethanol) and so the EN 228 limits were adopted for E20 petrol for these components.
4 Considerations for climate dependent requirements – Table 2 of the
FprCEN/TS 18227:2025
4.1 Volatility requirements table
The Table 3 below lists the limit values related to volatility agreed for the E20 CEN/TS 18227.
Table 3 — Volatility classes for petrol with a minimum oxygen content of 3,7 % (m/m) and a
maximum oxygen content of 8,0 % (m/m) from the E20 FprCEN/TS 18227:2025
a
Property Units Limits Test method

Class Class Class Class Class Class

A B C/C1 D/D1 E/E1 F/F1
b c
Vapour pressure (VP) kPa, min 45,0 45,0 50,0 60,0 65,0 70,0 EN 13016-1
b
kPa, max 60,0 70,0 80,0 90,0 95,0 100,0 EN 13016-3
c
% evaporated at 70 °C, % (V/V), min 20,0 20,0 22,0 22,0 22,0 22,0 EN ISO 3405
E70
% (V/V), max 68,0 68,0 68,0 68,0 68,0 68,0 EN 17306
c
% evaporated at 100 °C, % (V/V), min 46,0 46,0 46,0 46,0 46,0 46,0 EN ISO 3405
E100
% (V/V), max 75,0 75,0 75,0 75,0 75,0 75,0 EN 17306
c
% evaporated at 150 °C, % (V/V), min 80,0 80,0 80,0 80,0 80,0 80,0 EN ISO 3405
E150
EN 17306
c
Final Boiling Point FBP °C, max 200,0 200,0 200,0 200,0 200,0 200,0 EN ISO 3405
EN 17306
c
Distillation residue % (V/V), max 2,0 2,0 2,0 2,0 2,0 2,0 EN ISO 3405
EN 17306
Vapour Lock Index (VLI) index, max – – C D E F
(10 VP + 7 E70) – – – –
Vapour Lock Index (VLI)    C1 D1 E1 F1
(10 VP + 7 E70) 1176 1276 1326 1376
index, max
a
See also 6.6.1 in FprCEN/TS 18227:2025.
b
Dry Vapour Pressure Equivalent (DVPE) shall be reported.
c
See 6.6.2 in FprCEN/TS 18227:2025.

FprCEN/TR 18238:2025 (E)
4.2 Overview of volatility limit proposals
Presentations concerning the determination of volatility limits were made by experts from the vehicle
manufacturers and fuel supplier community. A representative of a vehicle manufacturer summarized the
volatility proposals as illustrated in Figure 6, below:

Figure 6 — Summary of volatility proposals, illustrating the range of views
The following summarises the discussions and decisions on volatility-related limits
4.3 E70
A representative of a vehicle manufacturer proposed to impose a higher E70 minimum (2
...