Here’s an even better source, which makes it absolutely clear that their electric engines are too weak in the real world.

“In practice, the combustion engine frequently assists the electric motor in CD mode, especially during acceleration, at higher speeds or uphill driving. On average, the ICE supplies power during almost one third of the distance driven in CD mode. This is largely due to insufficient e-motor power, as most PHEVs are not designed to operate fully electrically under typical real-world conditions.”

“ The largest gap between WLTP and real-world PHEV emissions occurs in CD mode, often referred to as an “electric” mode where real-world CD emissions are even higher than the WLTP average. According to T&E analysis, real-world CO₂ emissions in CD mode average around 68 gCO₂/km, which is nearly nine times as high as the estimated 8 gCO₂/km in CD mode under the WL TP methodology, and almost twice the WL TP average overall emissions (including both electric and combustion modes). In practice, the combustion engine frequently assists the electric motor in CD mode, especially during acceleration, at higher speeds or uphill driving. On average, the ICE supplies power during almost one third of the distance driven in CD mode. This is largely due to insufficient e-motor power, as most PHEVs are not designed to operate fully electrically under typical real-world conditions. This relationship is illustrated by the correlation between e-motor-to-combustion-engine power ratio and emissions in CD mode: vehicles with an average power ratio between electric motor and combustion engine of 0.9, emit approximately 45 gCO2/km in CD mode. An average PHEV with a ratio of 0.7 has emissions of around 68 gCO2/km. Vehicles in the lower decile in terms of their ratio of electric motor to combustion engine power, where it drops to around 0.5, have average CD mode emissions of 105 gCO2/km. In real-world conditions, petrol PHEVs consume around 3 L/100km in electric mode. “

https://uploads.transportenvironment.org/production/files/20...