Atmospheric pollution has been a major problem in human technological development and motor vehicles are one of the major sources of particulate matter pollution. This book investigates current models designed to predict air pollutant emissions and fuel consumption for road traffic and presents the outputs of statistical models developed to derive emission factors. Information on the use of Geographic Information Systems and traffic area air pollution monitoring stations is presented in order to comprehend the variations of traffic-related air pollution. Furthermore, this book reports the pros and cons of hydrogen-fuelled internal combustion engines, a study of the new technology to produce syngas from methane with a compression ignition engine. An overview of the characteristics of the factors influencing the thermal efficiency of spark ignition engines fuelled with hydrogen is given as well.