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PHEVs release almost five times greater planet-heating emissions than lab-reported figures indicate, according to a new analysis.

Widening Discrepancy In Official and Actual CO2 Output

Statistics reveals that PHEVs emit only 19% lower CO₂ than traditional gas and diesel cars, according to analysis conducted by a advocacy organization. This differs sharply with lab estimates, which suggested a three-quarters decrease in pollution.

Researchers examined data from in-vehicle energy use meters of eight hundred thousand vehicles sold in Europe between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from three and a half times in 2021.

“Actual emissions are increasing, while official emissions are falling,” said a lead researcher involved in the report. “This discrepancy is growing and poses a serious problem. As a result, PHEVs pollute almost as heavily as gasoline vehicles.”

Key Factors Driving the Emissions Gap

Researchers linked the majority of the gap to overestimates of the “electric driving share” – the ratio of miles travelled in electric power relative to total mileage. The team determined that just a quarter of driving was completed in electric mode, while official estimates assumed 84%.

Even, when operating in electric mode, emission amounts were well above official projections. That happened because electric motors were insufficiently powerful sufficient to operate alone, resulting to engines using fossil fuels for nearly one-third of the distance covered in electric mode.

Regulatory and Economic Implications

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

Furthermore, drivers of PHEVs would spend about €500 extra per year in operating costs than would be assumed under laboratory conditions.

“The bold claims that manufacturers often promote about their PHEV vehicles are clearly far from the truth,” stated a automotive analyst. “Consumers are being misled into thinking that by buying a PHEV, they are helping the planet and saving costs. Actually, PHEVs are little better than regular gas and diesel cars in terms of energy consumption, CO₂ emissions, and running costs.”

Policy Debate and Automotive Lobbying

Plug-in hybrid cars have lately been brought again into political discussions as carmakers have lobbied the European Union to weaken CO₂ standards. A proposed ban on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the car industry and resistance from EU countries with large automotive manufacturing.

Several high-level politicians have suggested plug-in hybrids as a potential “compromise” option to include in the regulation.

An external energy policy expert, who was unaffiliated with the study, called the report a “very useful addition” after a long period in which parts of the car sector argued there was insufficient information to properly evaluate actual CO2 output.

“These findings show, without question, that the difference in official and actual PHEV fuel consumption and CO₂ emissions is significantly greater than for petrol or conventional vehicles,” they stated. “All regulatory changes regarding PHEVs should be made with utmost care and considering that data.”