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Particle number (PN) emission limits were introduced in the European Union’s regulations for light-duty and heavy duty vehicles in the years 2011-2014. Since then, PN measurements have become a common practice in the automotive sector. Many studies showed that the current methodology, which counts particles >23 nm, misses a large fraction of particles for some engine technologies, such as port fuel injection vehicles or vehicles fueled with compressed natural gas (CNG). However, data for the latest technology vehicles are lacking. For this reason, we measured PN emissions >23 nm and >10 nm of >30 CNG, gasoline and diesel-fueled vehicles. Two systems were measuring in parallel from the full dilution tunnel; one with an evaporation tube and the other with a catalytic stripper. The PN emission levels spanned over three orders of magnitude depending on whether there was a particulate filter installed or not.

The aim of this paper is to analyse the results of regulated and unregulated emissions and carbon dioxide (CO2) emissions of passenger cars equipped with compression-ignition engines that meet the emission Euro 6d standards. Both test vehicles featured selective catalytic reduction (SCR) systems for control of oxides of nitrogen (NOx) and one vehicle also featured a passive NOx absorber (PNA). Research was performed using the current European Union exhaust emission test methods for passenger cars (Worldwide harmonized Light vehicles Test Procedures (WLTP)). Emission testing was performed on a chassis dynamometer, within a climatic chamber, at two different ambient temperatures: 23°C (i.e. Type I test) and -7°C (known as a Type VI test - currently not required for this engine type according to EU legislative requirements).

European Union RDE (real driving emissions) legislation requires that new vehicles be subjected to emissions tests on public roads. Performing emissions testing outside a laboratory setting immediately raises the question of the impact of ambient conditions - especially temperature - on the results. In the spirit of RDE legislation, a wide range of ambient temperatures are permissible, with mathematical moderation (correction) of the results only permissible for ambient temperatures <0°C and >+30°C. Within the standard range of temperatures (0°C to +30°C), no correction for temperature is applied to emissions results and the applicable emissions limits have to be met. Given the well-known link between the thermal state of an engine and its emissions following cold start, ambient temperature can be of great importance in determining whether a vehicle meets emissions requirements during an RDE test.

Vehicular ammonia emissions are currently unregulated, even though ammonia is harmful for a variety of reasons, and the gas is classed as toxic. Ammonia emissions represent a serious threat to air quality, particularly in urban settings; an ammonia emissions limit may be introduced in future legislation. Production of ammonia within the cylinder has long been known to be very limited. However, having reached its light-off temperature, a three-way catalyst can produce substantial quantities of ammonia through various reaction pathways. Production of ammonia is symptomatic of overly reducing conditions within the three-way catalyst (TWC), and depends somewhat upon the particular precious metals used. Emission is markedly higher during periods where demand for engine power is higher, when the engine will be operating under open-loop conditions.

Ethanol has long been a fuel of considerable interest for use as an automotive fuel in spark ignition (SI) internal combustion engines. In recent years, concerns over oil supplies, sustainability and geopolitical factors have lead multiple jurisdictions to mandate the blending of ethanol into standard gasoline. The impact of blend ethanol content on gaseous emissions has been widely studied; particulate matter emissions have received somewhat less attention, despite these emissions being regulated in the USA. Currently, in the EU particulate matter emissions from SI engines are partially regulated - only vehicles featuring direct injection SI engines are subject to emissions limits. A range of experiments was conducted to determine the impact of fuel ethanol content on the emissions of solid pollutants from Euro 5 passenger cars.

Non-plugin hybrids represent a technology with the capability to significantly reduce fuel consumption (FC), without any changes to refuelling infrastructure. The EU market share for this vehicle type in the passenger car segment was 3% in 2018 and this powertrain type remains of interest as an option to meet the European Union (EU) fleet average CO2 limits. EU legislative procedures require emissions limits to be met during the chassis dynamometer test and in the on-road real driving emissions (RDE) test, while official CO2/FC figures are quantified via the laboratory chassis dynamometer test only. This study employed both legislative test procedures and compared the results. Laboratory (chassis) dynamometer testing was conducted using the Worldwide Harmonised Light Vehicles Test Procedure (WLTP). On-road testing was carried out in accordance with RDE requirements, measuring the concentration of regulated gaseous emissions and the number of solid particles (PN).

This paper presents a study of passenger cars in terms of emissions measurements in tests conducted under real driving conditions (RDE - Real Driving Emissions) by means of PEMS (Portable Emission Measurement System) equipment. A special feature of the RDE tests presented in this paper is that they were performed under Polish conditions and the specified parameters may differ from those in most other European Union countries. Emission correction coefficients have been defined, based on the test results, equal to the increase (or decrease) of driving emissions during the laboratory (‘chassis dyno’) test or during normal usage in relation to the EU emission standards (emission class) of the vehicle.

Due to limited fossil fuel resources and a need to reduce anthropogenic CO₂ emissions, biofuel usage is increasing in multiple markets. Ethanol produced from the fermentation of biomass has been of interest as a potential partial replacement for petroleum for some time; for spark-ignition engines, bioethanol is the alternative fuel which is currently of greatest interest. At present, the international market for ethanol fuel consists of E85 fuel (with 85 percent ethanol content), as well as lower concentrations of ethanol in petrol for use in standard vehicles (E5, E10). The impact of different petrol-ethanol blends on exhaust emissions from unmodified vehicles remains under investigation. The potential for reduced exhaust emissions, improved security of fuel supply and more sustainable fuel production makes work on the production and usage of ethanol and its blends an increasingly important research topic.

This paper evaluates the possibility of using bioethanol blends (mixtures of gasoline fuel and ethanol derived from biomass) of varying strengths in an unmodified, small-displacement European Euro 5 light-duty gasoline vehicle. The influence of different proportions of bioethanol in the fuel blend (E5, E10, E25, E50 and E85) on the emission of gaseous pollutants, such as: carbon monoxide, hydrocarbons, oxides of nitrogen and carbon dioxide was tested at normal (22°C) and low (-7°C) ambient temperatures for a light-duty vehicle during the NEDC cycle on a chassis dynamometer. Engine performance metrics were also tested. All test results are presented in comparison to standard European gasoline (E5). Tailpipe emission data presented here suggest that modest improvements in air quality could result from usage of low-to-mid ethanol blends in the vehicle tested.

Ammonia is a reactive nitrogen compound (RNC - nitrogen-based gaseous molecules with multiple adverse impacts on human health and the biosphere). A three-way catalyst can produce substantial quantities of ammonia through various reaction pathways. This study presents a brief literature review, and presents experimental data on ammonia emissions from seven Euro 5 passenger cars, using different gasoline fuels and a CNG fuel. All vehicles were tested on a chassis dynamometer over the New European Driving Cycle. For six of the vehicles, ammonia was quantified directly at tailpipe (using two different analyzers); emissions from one vehicle were subjected to Fourier Transform Infra-Red (FTIR) analysis. Emissions of ammonia from these vehicles were generally low in comparison to other chassis dynamometer studies, perhaps attributable to the favorable laboratory test conditions and the age of the vehicles.

The subject of exhaust particulate emissions from road vehicles continues to gain attention and further, more stringent legislative demands are expected in this area. While the European Union has been at the forefront in recent decades, other jurisdictions are making progress towards more comprehensive control and limitation of exhaust particulate. This technical overview examines past, current and likely future (Euro 7) legislative requirements and also presents sample results from a range of vehicle types, in order to make comparisons and discuss the impact of expected regulatory updates. The impacts of powertrain trends, including hybridization, on exhaust particulate emissions and their control are briefly analyzed. Regulatory trends including the intention to move the lower boundary of the size range considered from 23 nm to 10 nm and the elimination of fuel- and technology-specific limits on particulate emissions are discussed and their implications analyzed.

In this study, two vehicles were tested under real driving conditions with gaseous exhaust emissions measured using a portable emissions measurement system (PEMS). One of the vehicles featured a hybrid powertrain with a spark ignition internal combustion engine, while the other vehicle featured a non-hybrid (conventional) spark ignition internal combustion engine. Aside from differences in the powertrain, the two test vehicles were of very similar size, weight and aerodynamic profile, meaning that the power demand for a given driving trace was very similar for both vehicles. The test route covered urban conditions (but did include driving on a road with speed limit 90 km/h). The approximate test route distance was 12 km and the average speed was very close to 40 km/h.

This paper discusses the legislative situation regarding type approval of plug-in hybrid vehicles (also known as off-vehicle charging hybrid-electric vehicles, OVC-HEV) in the range of exhaust emissions and fuel consumption. A range of tests were conducted on two Euro 6d-complaint OVC-HEVs to quantify emissions. Procedures were based on EU legislative requirements. For laboratory (chassis dyno) testing, two different test cycles and three different ambient temperatures were used for testing. Furthermore, in some cases additional measurements were performed, including measurement of emissions of particulate matter and continuous analysis of regulated and unregulated pollutants in undiluted exhaust. Consumption of electrical energy was also monitored. On-road testing was conducted on the test vehicle tested on the chassis dyno in the tests mentioned above, as well as on a second OVC-HEV test vehicle.

Despite an overall trend towards harmonization in vehicle regulations, regional differences persist in the area of exhaust emissions and fuel economy. The test procedure employed can exert a significant impact on the results obtained. In this paper, the EU and US type approval procedures for light duty vehicles are briefly compared and results obtained from several types of test procedure are presented. Specifically, emissions tests were performed on a single SUV which met US Tier III emissions limits. The vehicle featured a conventional, naturally aspirated spark ignition engine with indirect fuel injection and an aftertreatment system consisting of three-way catalysts with no dedicated particulate filtration device. The vehicle’s engine displacement, total mass and power-to-mass ratio were relatively representative of the upper end of the US market, but represented an outlying vehicle in terms of the characteristics of the EU fleet.

Ethanol has a long history as an automotive fuel and is currently used in various blends and formats as a fuel for spark ignition engines in many areas of the world. The addition of ethanol to petrol has been shown to reduce certain types of emissions, but increase others. This paper presents the results of a detailed experimental program carried out under standard laboratory conditions to determine the influence of different quantities of petrol-ethanol blends (E5, E10, E25, E50 and E85) on the emission of regulated and unregulated gaseous pollutants and particulate matter. The ethanol-petrol blends were laboratory tested in two European passenger cars on a chassis dynamometer over the New European Driving Cycle, using a constant volume sampler and analyzers for quantification of both regulated and unregulated emissions.

Exhaust gas aftertreatment systems can, under certain conditions, create undesired chemical species as a result of their elimination reactions. A prime example of this is ammonia (NH3), which is not formed in the combustion reaction, but which can be formed within a three-way catalyst (TWC) when physicochemical conditions permit. The elimination of NOx in the TWC thus sometimes comes at the cost of significant emissions of NH3. Ammonia is a pollutant and a reactive nitrogen compound (RNC) and NH3 emissions should be analyzed in this context, alongside other RNC species. Examination of the literature on the subject published over the past two decades shows that ammonia, a species which is currently not subject to systematic emissions requirements for road vehicles in any market, is often identified as forming the majority of the RNC emissions under a range of operating conditions.