Overview

• Real-world CO2 from plug-in hybrids in 2023 measured 4.9 times higher than lab results, up from 3.5 times in 2021.
• The cars deliver only about 19% lower CO2 than petrol or diesel in practice, far below the 75% cut assumed in tests.
• Researchers analysed onboard fuel-use data from 800,000 European vehicles and found electric-mode driving averaged 27% versus 84% in official assumptions.
• The undercount let four major car groups avoid more than €5bn in EU fleet-CO2 fines from 2021 to 2023, the report estimates.
• Drivers face roughly €500 extra per year in running costs versus lab-based expectations, prompting calls for tighter rules as the EU adjusts its utility-factor method.