PHEV real-world emissions and fuel use exceed official laboratory ratings

Plug-in hybrid electric vehicles (PHEVs) face significant discrepancies between laboratory emission ratings and real-world performance. Data from the Fraunhofer Institute, analyzing nearly one million European PHEVs, revealed an average petrol consumption of just over 6 litres per 100 kilometres, far exceeding the official average figure of 1.57 L/100 km. Similarly, 2024 European datasets showed real-world emissions averaging 145 grams of CO2 per kilometre, compared to an official rating of 24 g/km.

When not being charged, a PHEV functions as a heavy hybrid. Because these vehicles carry large batteries weighing between 150 and 300 kg, they often consume 1–2 L/100 km more than standard hybrids of the same class. In segment D or compact SUV models, fuel consumption in charge-sustaining mode typically ranges from 6–8 L/100 km, potentially reaching 9–10 L/100 km in cities with turbocharged engines.

The issue is largely attributed to user behavior and fleet management. While companies may purchase PHEVs to meet green fleet targets based on low laboratory ratings, drivers often rely on petrol due to the convenience of fuel cards or the lack of accessible workplace and home charging infrastructure. Without consistent charging—ideally four to five times per week—the economic and environmental benefits of the technology are largely lost.