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Plug-in hybrid cars emit nearly five times greater planet-heating pollution than lab-reported figures show, according to a recent report.

Widening Discrepancy In Lab and Actual CO2 Output

Statistics shows that PHEVs release just one-fifth less CO₂ than traditional gas and diesel cars, according to research carried out by a advocacy group. This contrasts significantly with lab estimates, which suggested a three-quarters reduction in emissions.

Researchers examined information from onboard energy use monitors of 800,000 cars sold in the EU between 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, up from three and a half times in 2021.

“Actual CO2 output are increasing, while official emissions are decreasing,” stated a senior analyst participating in the report. “This discrepancy is growing and creates a serious issue. As a result, PHEVs pollute nearly as heavily as gasoline cars.”

Primary Factors Behind the Discrepancy

Researchers attributed most of the difference to overestimates of the “electric driving share” – the ratio of kilometers driven in battery mode compared to total distance. They found that just a quarter of driving was done in electric mode, whereas official estimates suggested 84%.

Even, when operating in EV mode, pollution levels were significantly higher than lab projections. This happened because EV motors were insufficiently powerful enough to function alone, leading to engines using fossil fuels for almost a third of the travel covered in EV mode.

Regulatory and Economic Implications

Based on calculations, the lowballing of PHEV emissions enabled four major carmaker companies to escape over €5bn in fines from 2021 and 2023, by artificially simplifying compliance with European Union average fleet CO₂ targets.

Furthermore, drivers of PHEVs could pay about €500 extra per year in running expenses than is assumed under lab conditions.

“The strong statements that automakers like to make about their plug-in hybrid vehicles are obviously way off the mark,” commented a transport analyst. “Consumers are being misled into thinking that by buying a PHEV, they are helping the planet and cutting money. Actually, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of energy use, CO₂ emissions, and operating expenses.”

Political Debate and Automotive Pressure

Hybrid vehicles have lately been drawn again into political debates as carmakers have lobbied the EU to weaken CO₂ targets. A planned prohibition on new internal combustion vehicles in 2035 has faced heavy pressure from the automotive sector and opposition from EU countries with large automotive manufacturing.

Several senior politicians have proposed plug-in hybrids as a potential “compromise” solution to introduce in the regulation.

One independent energy policy specialist, who was unaffiliated with the study, described the analysis a “highly valuable addition” after a long period in which segments of the car industry argued there was insufficient information to accurately assess actual CO2 output.

“These findings show, beyond any doubt, that the gap between official and actual PHEV energy use and CO₂ emissions is significantly greater than for gasoline or conventional vehicles,” the expert said. “All regulatory changes concerning PHEVs should be implemented with extreme caution and considering that evidence.”