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The aim of this paper was to explore the influence of CNG fuel on emissions from light-duty vehicles in the context of the new Euro 6 emissions requirements and to compare exhaust emissions of the vehicles fueled with CNG and with gasoline. Emissions testing was performed on a chassis dynamometer according to the current EU legislative test method, over the New European Driving Cycle (NEDC). Additional tests were also performed on one of the test vehicles over the World Harmonized Light Vehicles Test Cycle (WLTC) according to the Global Technical Regulation No. 15 test procedure. The focus was on regulated exhaust emissions; both legislative (CVS-bag) and modal (continuous) analyses of the following gases were performed: CO (carbon monoxide), THC (total hydrocarbons), CH4 (methane), NMHC (non-methane hydrocarbons), NOx (oxides of nitrogen) and CO2 (carbon dioxide).

Diesel (compression ignition, CI) engines are increasingly exploited in light-duty vehicles, due to their high efficiency and favorable characteristics. Limited work has been performed on CI cold-start emissions at low temperatures. This paper presents a discussion and a brief literature review of diesel cold-start emissions phenomena at low ambient temperatures and the results of tests performed on two European light-duty vehicles with Euro 5 CI engines. The tests were performed on a chassis dynamometer within an advanced climate-controlled test laboratory at BOSMAL Automotive Research and Development Institute, Poland to determine the deterioration in emission of gaseous (HC, CO, NOx, CO2) and solid (PM, PN) pollutants following the EU legislative test procedure (testing at 20°C to 30°C and at -7°C, performed over the NEDC). The tests revealed appreciable increases in emissions of regulated pollutants.

Concern over greenhouse gas (GHG) emissions and air quality has made exhaust emissions from passenger cars a topic interest at an international level. This situation has led to the re-evaluation of testing procedures in order to produce more “representative” results. Laboratory procedures for testing exhaust emissions are built around a driving cycle. Cycles may be developed in one context but later used in another: for example, the New European Driving Cycle (NEDC) was not developed to measure fuel consumption, but has ended up being used to that end. The new Worldwide harmonized Light vehicles Test cycle (the WLTC) will sooner or later be used for measuring regulated exhaust emissions. Legal limits for emissions of regulated pollutants are inherently linked to the test conditions (and therefore to the driving cycle); inter-cycle correlations for regulated pollutants are an important research direction.

This paper reports testing conducted on multiple vehicle types over two European legislative driving cycles (the current NEDC and the incoming WLTC), using a mixture of legislative and non-legislative measurement devices to characterise the particulate emissions and examine the impact of the test cycle and certain vehicle characteristics (engine/fuel type, idle stop system, inertia) on particulate emissions. European legislative measurement techniques were successfully used to quantify particle mass (PM) and number (PN); an AVL Microsoot sensor was also used. Overall, the two driving cycles used in this study had a relatively limited impact on particulate emissions from the test vehicles, but certain differences were visible and in some cases statistically significant.

Due to concern over emissions of greenhouse gases (GHG; particularly carbon dioxide - CO2), energy consumption and sustainability, many jurisdictions now regulate fuel consumption, fuel economy or exhaust emissions of CO2. Testing is carried out under laboratory conditions according to local or regional procedures. However, a harmonized global test procedure with its own test cycle has been created: the World Harmonized Light Vehicles Test Cycle - WLTC. In this paper, the WLTC is compared to the New European Driving Cycle (NEDC) and the FTP-75 cycle used in the USA. A series of emissions tests were conducted at BOSMAL on a chassis dynamometer in a Euro 6-complaint test facility to determine the impact of the test cycle on CO2 emissions and fuel consumption. While there are multiple differences in the test cycles in terms of dynamicity, duration, distance covered, mean/maximum speed, etc, differences in results obtained over the three test cycles were reasonably limited.