An analysis found real-world carbon emissions from plug-in hybrid electric vehicles (PHEVs) were about 6 times the official certified levels. A proposal to cap fuel tank capacity at 15 litres, to encourage drivers to charge more often, is drawing attention.

InsideEVs reported on Oct. 18 that the European green transport group Transport & Environment (T&E) said vehicle design and charging performance need to be improved to achieve meaningful emissions reductions from PHEVs.

T&E analysed European Environment Agency data and found real-world carbon dioxide emissions from PHEVs registered in Europe in 2024 were about 6 times the certified figure. Emissions were only 14 percent lower than those of conventional internal combustion engine cars and hybrids, a wide gap from the certified reduction rate of 83 percent.

Distance driven on electricity alone accounted for just 27 percent of total driving distance. Even in segments using the battery, about one-third of the time the internal combustion engine operated as well.

T&E proposed limiting fuel tanks to a maximum of 15 litres and promoting real-world electric driving range of at least 200 km and fast-charging capability above 100 kW by 2030. It also said electric motor output should preferably be at least 3 times higher than the internal combustion engine.

The aim is to cut reliance on gasoline by shrinking fuel tanks and to use electricity as the main power source.

Actual running costs also differed widely from certified figures. T&E estimated annual powertrain costs for 2024-model PHEVs at 1,810 euros (about 2,717,600 won). That is 680 euros (about 1,021,000 won) more than the estimated 1,130 euros (about 1,696,600 won) based on official consumption figures.

Still, cutting fuel tank size does not automatically lead to more charging. If electric range and charging infrastructure are insufficient, it could instead only increase the frequency of refuelling, the analysis said.

The proposal is not an EU regulation, but a recommendation from an environmental group. Calls are growing to focus on real-world driving patterns and emissions, rather than certified figures, when assessing the environmental performance of PHEVs.