Alessandro Tansini

Road transport accounts for the largest share of EU transport-related greenhouse gas (GHG) emissions, and its decarbonisation increasingly relies on the electrification of the light-duty vehicle (LDV) fleet. However, most environmental assessments still rely on type-approval consumption values and coarse vehicle categories, overlooking both real-world performance and the heterogeneity of the passenger-car fleet. This study presents a comprehensive, extended Well-to-Wheel (WtW) assessment of the European Economic Area’s newly registered LDV fleet in 2023, covering ca. 11.3 million vehicles. The approach integrates three elements: (i) a detailed vehicle classification distinguishing standard cars, sport utility vehicles (SUVs), multipurpose vehicles (MPVs), and vans by powertrain, fuel type and size; (ii) real-world energy and fuel consumption factors derived from On-Board Fuel and Energy Consumption Monitoring (OBFCM) data covering about 8 million vehicles, complemented by dedicated battery electric vehicle (BEV) driving campaigns; and (iii) an extended WtW methodology that integrates upstream (Well-to-Tank) and tailpipe (Tank-to-Wheel) emissions with vehicle production impacts. Results show that climate change impacts decrease consistently with the degree of electrification, with BEVs achieving approximately 50% lower impact than internal combustion engine vehicles (ICEVs), despite production-phase emissions accounting for up to half of their total footprint. Vehicle size strongly influences both energy consumption and emissions, with electricity consumption in large BEV SUVs up to twice that of compact models. These findings underline the importance of jointly considering real-world operation, vehicle categorisation and production-related impacts when assessing decarbonisation pathways, offering policy-relevant insight into the evolving climate performance of the EU passenger vehicle fleet.

Although particulate matter (PM) pollution from vehicles’ exhaust has decreased significantly over the years, the contribution from non-exhaust sources (brakes, tyres) has remained at the same levels. In the European Union (EU), Euro 7 regulation introduced PM limits for vehicles’ brake systems. Regenerative braking, i.e., recuperation of the deceleration kinetic and potential energy to the vehicle battery, is one of the strategies to reduce the brake emission levels and improve vehicle efficiency. According to the regulation, the shares of friction and regenerative braking can be determined with actual testing of the vehicle on a chassis dynamometer. In this study we tested the regenerative capabilities of a plug-in hybrid vehicle, both in the laboratory and on the road, under different protocols (including both smooth and aggressive braking) and covering a wide range of driving conditions (urban, rural, motorway) over 10,000 km of driving. Good agreement was obtained between laboratory and on-road tests, with the use of the friction brakes being on average 7% and 5.3%, respectively. However, at the same time it was demonstrated that the friction braking share can vary over a wide range (up to around 30%), depending on the driver’s behaviour.

The driving style is a crucial variable for real-world vehicle energy performance. This study uses a state-of-the-art methodology to separately assess its impact on the energy consumption. A benchmark driving cycle is modified according to specific driving styles, and the corresponding energy consumption is theoretically simulated. The driving style characterisation includes acceleration, braking and gear-shifting patterns for each driver through ad-hoc metrics. The methodology establishes a comparative analysis regarding the energy impact of a pool of drivers. Furthermore, the variability of a driver’s consumption on different vehicle technologies is assessed by considering an internal combustion engine- (ICE) vehicle and a plug-in hybrid electric vehicle (PHEV). The results reveal that each driver exhibits characteristic and heterogeneous acceleration and braking styles, with the gear-shifting style playing a significant role in the vehicle’s fuel consumption. From a policy perspective, this work contributes in the understanding of the discrepancies in energy consumption between officially reported values and the real-world performance.

Hybrid Electric Vehicles (HEVs) are a prominent solution for reducing CO₂ emissions from transport in Europe. They are equipped with at least two propulsion energy converters, an Internal Combustion Engine (ICE) and one or more Electric Machines (EMs), operated in a way to exploit synergies and achieve fuel efficiency. Because of the variety in configurations and strategies, the use of simulation is essential for vehicle development and characterisation of energy consumption. This paper introduces a novel simulation approach to estimate the CO₂ emissions from different hybrid architectures (series, parallel, power-split) and electrification degrees (mild, full, plug-in and range extender) that is relatively simple, flexible and accurate. The approach identifies the optimal power split between the energy converters for any given time in a driving cycle according to three evaluation levels: supervisor, ICE manager and optimiser. The latter relies on the Equivalent Consumption Minimisation Strategy (ECMS) and the limitations imposed by the other two layers. Six light-duty HEVs with different hybrid architectures were tested to support the development of the approach. The results show an indicative accuracy of ±5%, enabling to run assessments of hybrid powertrain solutions and supporting regulatory and consumer information initiatives.

Plug-in Hybrid Electric Vehicles (PHEVs) are one of the main technology options for reducing vehicle CO2 emissions and helping vehicle manufacturers (OEMs) to meet the CO2 targets set by different Governments from all around the world. In Europe OEMs have introduced a number of PHEV models to meet their CO2 target of 95 g/km for passenger cars set for the year 2021. Fuel consumption (FC) and CO2 emissions from PHEVs, however, strongly depend on the way they are used and on the frequency with which their battery is charged by the user. Studies have indeed revealed that in real life, with poor charging behavior from users, PHEV FC is equivalent to that of conventional vehicles, and in some cases higher, due to the increased mass and the need to keep the battery at a certain charging level. The discrepancy between official and real life figures of FC, electric range, and CO2 emissions has been often attributed, at least partly, to the inadequacy of the New European Driving Cycle (NEDC) to represent the real-world conditions of vehicle use. In an attempt to deal with this problem, which has strong implications on the effectiveness of the CO2-reduction policies, the European Commission has decided to introduce already in 2017 the Worldwide Harmonized Light Vehicles Test Procedure (WLTP). Aim of the present work is to compare WLTP and NEDC procedures for what concerns the determination of fuel consumption (FC), CO2 emissions and electric ranges of two plug-in hybrid vehicles tested in the Joint Research Centre (JRC) of the European Commission laboratories. Results show that the electric range determined following the WLTP procedure is significantly shorter than the NEDC electric range. On the contrary, results show that WLTP-based FC and CO2 will tend to be lower than the corresponding NEDC-based values with the increase in the battery size and corresponding electric range.