🔗 Share this article

Plug-in hybrid electric vehicles produce nearly 5x more global warming pollution than lab-reported data show, according to a recent analysis.

Widening Discrepancy Between Official and Real-World CO2 Output

Data reveals that PHEVs release just one-fifth less CO₂ than traditional gas and diesel vehicles, based on research conducted by a non-profit group. This contrasts significantly with laboratory estimates, which assumed a three-quarters reduction in emissions.

Analysts examined information from onboard fuel consumption monitors of eight hundred thousand cars registered in the EU from 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than official estimates, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while lab-reported figures are falling,” said a senior researcher involved in the report. “This gap is widening and creates a serious issue. Consequently, PHEVs pollute almost as much as gasoline cars.”

Primary Reasons Behind the Discrepancy

Analysts attributed the majority of the gap to overestimates of the “electric driving share” – the percentage of miles driven in battery power relative to total mileage. The team determined that only 27% of driving was completed in EV mode, while official assumptions assumed 84%.

Additionally, when operating in electric mode, pollution amounts were significantly higher than lab projections. This occurred because EV motors were not strong enough to operate alone, resulting to engines using fossil fuels for nearly a third of the travel covered in EV mode.

Regulatory and Economic Implications

Based on estimates, the lowballing of PHEV emissions enabled several major automaker companies to escape more than €5bn in fines from 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ targets.

Furthermore, drivers of PHEVs could pay about €500 more annually in operating expenses than is estimated under lab tests.

“The strong statements that manufacturers often promote about their PHEV cars are clearly way off the mark,” commented a transport expert. “Consumers are being misled into thinking that by buying a PHEV, they are helping the planet and cutting costs. In reality, PHEVs are only slightly better than regular petrol and diesel cars in terms of energy consumption, CO₂ emissions, and operating costs.”

Political Debate and Automotive Pressure

Hybrid cars have recently been brought back into political debates as carmakers have lobbied the EU to relax CO₂ standards. A proposed prohibition on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the automotive sector and opposition from EU countries with large automotive industries.

Several senior politicians have proposed PHEVs as a possible “compromise” option to include in the legislation.

One external energy economics specialist, who was unaffiliated with the study, described the report a “very useful addition” after a long period in which parts of the car sector argued there was insufficient information to accurately 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 larger than for gasoline or conventional vehicles,” the expert stated. “Any policy changes regarding PHEVs should be implemented with extreme caution and in the light of that evidence.”