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Plug-in hybrid electric vehicles release nearly five times greater global warming emissions than official figures indicate, as per a recent analysis.

Widening Gap In Lab and Real-World CO2 Output

Statistics reveals that PHEVs emit only 19% lower CO₂ than traditional gas and diesel cars, based on research carried out by a non-profit organization. That contrasts sharply with laboratory estimates, which assumed a 75% decrease in emissions.

Analysts studied data from in-vehicle energy use meters of 800,000 cars registered in Europe between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than lab estimates, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while lab-reported figures are falling,” said a senior researcher participating in the study. “That discrepancy is growing and creates a serious issue. Consequently, PHEVs emit nearly as much as petrol vehicles.”

Primary Reasons Behind the Discrepancy

Analysts linked most of the difference to inflated estimates of the “electric driving share” – the percentage of kilometers driven in battery mode relative to overall mileage. The team found that only 27% of driving was done in electric mode, while official estimates assumed 84%.

Even, when operating in electric mode, emission levels were well above lab projections. This occurred because EV motors were not strong sufficient to function independently, leading to engines using fossil fuels for nearly a third of the travel completed in EV mode.

Policy and Economic Implications

According to estimates, the underestimation of PHEV emissions allowed several large carmaker groups to escape more than €5bn in penalties from 2021 and 2023, by falsely easing adherence with EU fleet-average CO₂ targets.

Additionally, owners of PHEVs could spend about €500 extra annually in running costs than would be assumed under lab tests.

“The bold statements that manufacturers often promote about their plug-in hybrid cars are clearly way off the mark,” stated a automotive expert. “Consumers are being misled into believing that by buying a PHEV, they are helping the environment and saving money. In reality, PHEVs are little improved than regular gas and diesel cars in terms of energy use, CO₂ emissions, and running costs.”

Policy Discussion and Automotive Pressure

Hybrid cars have lately been drawn again into political debates as automakers have lobbied the EU to weaken CO₂ targets. A planned prohibition on new internal combustion vehicles in 2035 has faced intense pressure from the car industry and resistance from EU countries with large car manufacturing.

Some senior politicians have proposed PHEVs as a potential “flexibility” solution to include in the regulation.

An external energy economics expert, who was not involved with the research, described the analysis a “highly valuable addition” after years in which segments of the automotive sector claimed there was insufficient data to accurately assess real-world CO2 output.

“These findings show, beyond any doubt, that the gap in lab and actual PHEV fuel consumption and CO₂ output is significantly greater than for gasoline or diesel vehicles,” the expert stated. “All policy adjustments concerning PHEVs should be made with extreme care and in the light of that data.”