Environmental performance of plug-in hybrid electric vehicles: Impacts of driving cycles, ambient temperature, and auxiliary loads

Plug-in Hybrid Electric Vehicles (PHEVs) play an important role in the transition to sustainable transportation, but their real-world performance often deviates from type-approval values. These deviations stem from factors not captured in standard test procedures, including driving dynamics, ambient temperature, and use of auxiliary systems. As a result, real-world fuel consumption for PHEVs in Europe is, on average, up to five times higher than certified values. To address this gap, the present study provides an empirical evaluation of the performance of eight PHEV passenger cars using controlled test-bench measurements under various conditions. The analyses focus on the influence of low ambient temperature, dynamic driving, and auxiliary heating on electric range, energy consumption (fuel and electric energy demand), and carbon dioxide and key pollutants emissions. Results show a substantial reduction in electric range under demanding conditions, increasing reliance on the combustion engine and leading to higher fuel consumption and emissions. These findings underscore the limitations of current type-approval procedures and the importance of considering real-world usage conditions in environmental assessments. • Type-approval tests underestimate real-world energy use and emissions of PHEVs • Controlled testing reveals large variation in performance across PHEV models • Cabin heating, low temperatures, and dynamic driving reduce PHEV performance • Demanding conditions shorten electric range and increase consumption and emissions