🔗 Share this article

PHEVs release almost five times more planet-heating emissions than official figures show, according to a new analysis.

Widening Discrepancy Between Lab and Actual Emissions

Data shows that PHEVs release just one-fifth less CO₂ than traditional petrol and diesel cars, according to research conducted by a non-profit group. This contrasts significantly with laboratory tests, which assumed a 75% reduction in emissions.

Researchers studied information from onboard energy use meters of 800,000 cars sold in the EU from 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, up from three and a half times in 2021.

“Actual emissions are rising, while official emissions are decreasing,” stated a lead researcher participating in the study. “This discrepancy is widening and poses a serious issue. As a result, PHEVs emit almost as heavily as gasoline cars.”

Primary Reasons Behind the Emissions Gap

Researchers linked most of the gap to overestimates of the “electric driving share” – the ratio of miles driven in battery mode relative to total mileage. The team found that only a quarter of travel was completed in EV mode, whereas lab estimates suggested 84%.

Additionally, when running in EV mode, pollution amounts were well above official estimates. This occurred because electric motors were insufficiently powerful enough to function independently, leading to engines using fossil fuels for nearly a third of the distance covered in electric mode.

Policy and Financial Consequences

According to calculations, the underestimation of PHEV emissions enabled four large carmaker companies to escape more than €5bn in fines from 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs could pay approximately €500 more annually in operating expenses than would be estimated under laboratory tests.

“The strong statements that manufacturers often promote about their PHEV vehicles are obviously way off the mark,” commented a transport expert. “Buyers are being misled into thinking that by buying a PHEV, they are helping the environment and saving costs. In reality, PHEVs are only slightly improved than standard gas and diesel cars in terms of fuel use, CO₂ production, and running expenses.”

Political Debate and Industry Pressure

Hybrid cars have lately been drawn again into political discussions as automakers have lobbied the EU to relax CO₂ targets. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced intense lobbying from the car industry and opposition from member states with significant automotive industries.

Several senior officials have proposed plug-in hybrids as a possible “flexibility” option to introduce in the legislation.

One independent energy economics expert, who was not involved with the research, called the report a “highly valuable addition” after years in which segments of the car industry argued there was too little information to properly assess actual emissions.

“The results show, without question, that the difference in official and real-world PHEV energy use and CO₂ emissions is significantly greater than for petrol or diesel cars,” the expert said. “Any policy changes regarding PHEVs should be made with extreme caution and in the light of this evidence.”