Measurement of car engines exhaust pollutants emissions is very important because of their harmful effects on the environment. This article presents the assessment of repeatability of the passenger car engine exhaust pollutants emission research results obtained in the conditions of a chassis dynamometer. The research was conducted in a climate chamber, enabling the temperature conditions to be determined from − 20 to + 30 °C. The emission of CO, CH₄, CO₂, NO_X, THC, and NMHC was subjected to the analysis. The aim of the research is to draw attention to the accuracy of the pollutant emission research results in driving cycles, and the comparison of pollutant emission results and their repeatability obtained in successive NEDC cycles under cold and hot start conditions. The results of the analysis show that, in the case of a small number of measurements, the results repeatability analysis is necessary for a proper interpretation of the pollutant emission results on the basis of the mean value. According to the authors’ judgment, it is beneficial to determine the coefficient of variation for a more complete assessment of exhaust emission result repeatability obtained from a small number of measurements. This parameter is rarely presented by the authors of papers on exhaust components emission research.

The problem of global warming and the related climate change requires solutions to reduce greenhouse gas emissions, in particular CO₂. As a result, newly manufactured cars consume less fuel and emit lower amounts of CO₂. In terms of exhaust emissions and fuel consumption, old cars are significantly inferior to the more recent models. In Poland, for instance, the average age of passenger cars is approximately 13 years. Therefore, apart from developing new solutions in the cars produced today, it is important to focus on measures that enable the reduction in CO₂ emissions in older vehicles. These methods include the adaptation of used cars to run on gaseous fuels. Natural gas is a hydrocarbon fuel that is particularly preferred in terms of CO₂ emissions. The article presents the results of research of carbon oxides emission (CO, CO₂) in the exhaust gas of a passenger car fueled by petrol and natural gas. The emissions were measured under the conditions of the New European Driving Cycle (NEDC) test and in real road tests. The test results confirm that compared to petrol, a CNG vehicle allows for a significant reduction in CO₂ and CO emissions in a car that is several years old, especially in urban traffic conditions.

Among the solutions that make it possible to reduce CO₂ emissions in the transport sector, particularly in urban traffic conditions, are hybrid vehicles. The share of driving performed in electric mode for hybrid vehicles is highly dependent on motion resistance. There are different methods for determining the motion resistance function during chassis dynamometer testing, leading to different test results. Therefore, the main objective of this study was to determine the effect of the chassis dynamometer load function on the energy demand and CO₂ emissions of a full-hybrid passenger car. Emissions tests according to the New European Driving Cycle (NEDC) were carried out on a chassis dynamometer for three different methods of determining the car’s resistance to motion. The study showed that adopting the motion resistance function according to different methods, results in differences in CO₂ emissions up to about 35% for the entire cycle. Therefore, the authors suggest that in the case of tests carried out with chassis dynamometers, it is necessary to also provide information on the chassis dynamometer loading function adopted for the tests.

Differences between the results obtained in laboratory and road tests of vehicles depend on a number of factors. Among the most important of these are driving cycle and road load. These parameters also affect the hybrid drive control, including the combustion engine operation or driving in electric mode. In most studies, tests carried out on chassis dynamometers concern type approval cycles (NEDC—New European Driving Cycle, WLTC—World-wide harmonized Light duty Test Cycle, FTP— Federal Test Procedure), which differ from real on-road tests. Consequently, the different driving cycles do not allow for results similar to those obtained during on-road driving, especially as the actual cycles on the road are unrepeatable. It is also important to determine the effect of the motion resistance function adopted for chassis dynamometer tests on exhaust emissions and fuel consumption. For this purpose, the authors tested a hybrid car under road and laboratory conditions for the same driving cycle. The analysis was conducted for an example urban road cycle in Rzeszow (URRC). The purpose of the study was to determine the differences in the results of gaseous emissions (THC, CO, CO₂, NO_x) and fuel consumption (energy) of a hybrid car under road conditions, with the results of tests conducted on a chassis dynamometer, for the same cycle and three functions of resistance.

The search for alternative liquid fuels for compression-ignition (CI) internal combustion engines includes waste-derived fuels such as hydrotreated vegetable oil (HVO) and pyrolytic oils from end-of-life tires (tire pyrolytic oil, TPO) and plastics—polystyrene pyrolytic oil (PSO). The application of these fuels requires meeting a number of criteria, including exhaust pollutant emissions. The scientific objective of this study was to compare pollutant emissions—carbon dioxide (CO₂), carbon monoxide (CO), total hydrocarbons (THC), nitrogen oxides (NO_x), particulate matter (PM)—and fuel consumption of a passenger car CI engine fueled with diesel B7, HVO, and a blend consisting of 90% HVO, 5% TPO, and 5% PSO (vol.), hereinafter referred to as HVO–TPO–PSO. The tests were carried out using a chassis dynamometer equipped for conducting standardized WLTC Class 3b driving cycles, with exhaust gases measured by laboratory-grade analyzers to ensure accuracy and repeatability. Fueling the engine with HVO resulted in the lowest CO₂, CO, THC, NO_x, and PM emissions across all phases of the driving cycle. The addition of pyrolytic oils to HVO increased NO_x and CO₂ levels while maintaining benefits in PM, THC, and CO reduction compared to the B7 reference fuel. The results demonstrated the applicability of HVO–TPO–PSO blends in engine applications while indicating the need for further durability studies. The adopted research approach addresses a significant knowledge gap by providing a unique analysis of the impact of HVO blends with tire and plastic pyrolysis oils on pollutant emissions and internal combustion engine fuel consumption under WLTC 3b operating conditions.