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PHEVs emit nearly 5x more global warming emissions than official data indicate, as per a recent report.

Growing Gap In Lab and Real-World CO2 Output

Statistics reveals that PHEVs emit just one-fifth lower CO₂ than traditional petrol and diesel vehicles, based on research carried out by a non-profit group. That differs significantly with lab estimates, which assumed a 75% reduction in emissions.

Analysts studied data from onboard fuel consumption meters of 800,000 vehicles registered in Europe from 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were nearly five times greater than official estimates, up from three and a half times in 2021.

“Actual CO2 output are increasing, while official emissions are decreasing,” said a senior researcher involved in the report. “That gap is growing and poses a significant issue. Consequently, PHEVs emit nearly as much as petrol vehicles.”

Primary Factors Behind the Emissions Gap

Researchers linked most of the difference to overestimates of the “electric driving share” – the percentage of kilometers driven in battery mode relative to overall distance. They found that just 27% of travel was done in electric mode, whereas official estimates assumed 84%.

Additionally, when operating in EV mode, emission amounts were significantly higher than official estimates. That occurred because EV motors were not strong enough to function alone, leading to engines burning gasoline for nearly one-third of the distance completed in EV mode.

Policy and Economic Implications

Based on calculations, the underestimation of PHEV emissions allowed several major carmaker groups to avoid over €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs could spend approximately €500 extra annually in running expenses than would be estimated under laboratory tests.

“The bold claims that manufacturers often promote about their PHEV cars are clearly far from the truth,” commented a transport analyst. “Buyers are being misled into thinking that by buying a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are only slightly better than standard gas and diesel vehicles in terms of energy consumption, CO₂ production, and running costs.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid vehicles have lately been drawn back into political debates as carmakers have pressed the EU to relax CO₂ standards. A planned prohibition on sales of new internal combustion vehicles in 2035 has faced intense pressure from the car industry and opposition from EU countries with large automotive industries.

Some senior politicians have suggested PHEVs as a potential “compromise” option to introduce in the legislation.

One external energy economics specialist, who was not involved with the study, called the analysis a “very useful contribution” after years in which parts of the automotive sector claimed there was insufficient data to accurately assess actual emissions.

“The results demonstrate, beyond any doubt, that the gap in lab and real-world PHEV fuel consumption and CO₂ output is much, much larger than for gasoline or diesel vehicles,” they said. “Any policy adjustments regarding PHEVs should be made with utmost caution and in the light of that data.”