Plug-in hybrid electrical vehicles (PHEVs) are generally considered to be a cleaner alternative to conventional passenger cars. However, there is still very limited information available regarding criteria pollutant emissions from these vehicles. This paper shows, for the first time, the emissions of criteria pollutants, unregulated pollutants, and CO 2 and also electric range from two very different PHEVs, one Euro 6 parallel plug-in hybrid and one range-extended battery electric vehicle (BEVx), applying the new world harmonized light-duty test procedure at ambient temperatures equal to 23 and −7 °C. The impact of using a cabin air heating system on vehicle electric range and emissions at cold temperature has also been studied. Cold ambient temperatures and, to a larger extent, the use of heating systems have been shown to lead to a pronounced negative impact on emissions and shorter electric ranges. Results also show that modern PHEVs can emit similar, or even higher, levels of pollutants (e.g., particle number) as Euro 6 conventional gasoline and diesel vehicles.

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The Vehicle Energy Consumption calculation Tool (VECTO) is used for the official calculation and reporting of CO2 emissions of HDVs in Europe. It uses certified input data in the form of energy or torque loss maps of driveline components and engine fuel consumption maps. Such data are proprietary and are not disclosed. Any further analysis of the fleet performance and CO2 emissions evolution using VECTO would require generic inputs or reconstructing realistic component input data. The current study attempts to address this issue by developing a process that would create VECTO input files based as much as possible on publicly available data. The core of the process is a series of models that calculate the vehicle component efficiency maps and produce the necessary VECTO input data. The process was applied to generate vehicle input files for rigid trucks and tractor-trailers of HDV Classes 4, 5, 9 and 10. Subsequently, evaluating the accuracy of the process, the simulation results were compared with reference VECTO results supplied by various vehicle manufacturers. The results showed that the difference between simulated and reference CO2 emissions was on average-0.6% in the Long Haul cycle and 1% in the Regional Delivery. Such a process could be a powerful tool for calculating HDV CO2 emissions for development and analysis purposes, e.g. for new vehicle prototypes or multistage vehicles, and for creating VECTO equivalent models that can be used to assess alternative operating conditions and mission profiles of existing vehicle models. The methodology was applied for creating input of various components in the US tool for HDV certification, GEM, for generic sample-vehicle models available.

The Vehicle Energy Consumption calculation Tool (VECTO) is used in Europe for calculating standardised energy consumption and CO2 emissions from Heavy-Duty Trucks (HDTs) for certification purposes. The tool requires detailed vehicle technical specifications and a series of component efficiency maps, which are difficult to retrieve for those that are outside of the manufacturing industry. In the context of quantifying HDT CO2 emissions, the Joint Research Centre (JRC) of the European Commission received VECTO simulation data of the 2016 vehicle fleet from the vehicle manufacturers. In previous work, this simulation data has been normalised to compensate for differences and issues in the quality of the input data used to run the simulations. This work, which is a continuation of the previous exercise, focuses on the deeper meaning of the data received to understand the factors contributing to energy and fuel consumption. Fuel efficiency distributions and energy breakdown figures were derived from the data and are presented in this work. Correlation formulas were produced to calculate the energy loss contributions of individual components and resistances (air drag, rolling resistance, axle losses, gearbox losses, etc.) over the Regional Delivery and Long Haul cycles, given a limited number of input parameters such as vehicle characteristics and average component efficiencies. Default values and meaningful ranges of variation of these parameters obtained from the data of the fleet are also reported in this work. The importance of air drag and rolling resistance losses are highlighted since these losses account for about 70% of the energy consumed downstream the engine. Finally, based on the correlation formulas to calculate the individual energy losses, a method is presented that calculates the final energy consumption and CO2 emissions for all the regulated HDTs classes and that does not rely on the use of VECTO.

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In 2019, passenger car CO2 emissions peaked at 3.2 billion metric tons globally. Despite efforts to curb vehicle CO2 emissions and the ambitious targets adopted for greenhouse gas mitigation in the European Union (EU), emissions from road vehicles increased steadily over the past decade. Electrified vehicles have gained significant market share in the last years and are an essential technical option to reduce CO2 emissions. Range anxiety and insufficient charging infrastructure limit electrified vehicles’ customer acceptance and market attractiveness. The use of auxiliary systems under certain circumstances may reduce vehicle range. In this regard, energy management improvements lead to better vehicle range results. As well-considered in numerous studies, the most consuming auxiliary system is the vehicle’s heating, ventilation and air-conditioning (HVAC) system, also known as Mobile Air-Conditioning (MAC). The present work explores the influence of different parameters on the energy consumption of the MAC system in plug-in hybrid vehicles (PHEV) and battery electric vehicles (BEV). For this purpose, one PHEV and one BEV were tested in laboratory conditions at different cell temperatures of −7°C (19.4°F), 22°C (71.6°F) and 35°C (95°F), over the Worldwide Harmonised Light vehicle Test Cycle (WLTC). Laboratory tests with the same conditions were repeated with MAC on and off for each temperature. For the reference 23°C (73.4°F) condition, additional factors affecting energy consumption were analysed, such as the impact of depleting/sustaining modes on the MAC performance in PHEV, or the effect of warm and cold start in PHEV and BEV. Results suggest that the electric energy required to heat the cabin at low temperature (−7°C) could be 4–10 times higher than the energy needed to cool down the cabin in hot conditions (35°C). Compared to the vehicle energy required at the wheels during a WLTC, the MAC impact at −7°C ranges from 35% to 45% while at 35°C goes from 15% to 18%.

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