🔗 Share this article

Plug-in hybrid electric vehicles release nearly 5x greater planet-heating emissions than official data show, according to a recent report.

Widening Gap Between Lab and Real-World CO2 Output

Statistics shows that PHEVs emit only 19% less CO₂ than traditional petrol and diesel vehicles, according to analysis conducted by a non-profit organization. That contrasts sharply with lab tests, which assumed a three-quarters reduction in pollution.

Researchers studied information from onboard energy use monitors of 800,000 cars sold in Europe between 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, increased from 3.5 times in 2021.

“Real-world CO2 output are rising, while official emissions are decreasing,” said a lead analyst participating in the report. “This gap is growing and creates a serious issue. As a result, PHEVs emit almost as heavily as petrol vehicles.”

Key Reasons Behind the Discrepancy

Researchers attributed most of the gap to inflated estimates of the “electric driving share” – the ratio of miles driven in battery power relative to total distance. They found that just a quarter of driving was done in EV mode, while lab estimates suggested 84%.

Additionally, when running in EV mode, emission amounts were significantly higher than official projections. This occurred because electric motors were not strong enough to operate independently, leading to engines using fossil fuels for nearly a third of the distance covered in electric mode.

Policy and Financial Consequences

Based on calculations, the lowballing of PHEV emissions allowed four major carmaker groups to avoid more than €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with EU fleet-average CO₂ targets.

Additionally, owners of PHEVs could spend approximately €500 extra annually in running expenses than is estimated under lab tests.

“The bold claims that automakers 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 money. Actually, PHEVs are little better than regular gas and diesel cars in terms of energy use, CO₂ production, and running costs.”

Political Discussion and Automotive Pressure

Hybrid cars have recently been brought again into political discussions as carmakers have pressed the European Union to weaken CO₂ targets. A proposed ban on new internal combustion vehicles in 2035 has faced heavy pressure from the car sector and resistance from member states with significant automotive industries.

Some high-level officials have proposed plug-in hybrids as a possible “flexibility” solution to include in the regulation.

One independent energy economics expert, who was unaffiliated with the study, described the report a “highly valuable addition” after years in which segments of the car sector argued there was insufficient information to properly assess real-world emissions.

“The results demonstrate, beyond any doubt, that the difference in lab and actual PHEV fuel consumption and CO₂ output is significantly greater than for gasoline or diesel cars,” they said. “Any policy changes regarding PHEVs should be made with utmost caution and in the light of this evidence.”