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PHEVs emit nearly 5x more planet-heating pollution than official data show, according to a recent report.

Growing Gap Between Lab and Actual CO2 Output

Statistics shows that PHEVs emit just 19% lower CO₂ than traditional gas and diesel cars, according to analysis conducted by a non-profit organization. This differs significantly with lab estimates, which assumed a 75% decrease in pollution.

Researchers examined information from onboard energy use meters of 800,000 cars sold in the EU from 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, increased from 3.5 times in 2021.

“Actual emissions are increasing, while official emissions are decreasing,” said a lead researcher involved in the study. “That gap is growing and poses a significant issue. As a result, PHEVs pollute almost as heavily as petrol cars.”

Primary Factors Behind the Discrepancy

Analysts linked the majority of the difference to overestimates of the “utility factor” – the ratio of miles travelled in battery power relative to total mileage. The team determined that only 27% of driving was done in EV mode, while official estimates suggested over four-fifths.

Additionally, when operating in electric mode, pollution levels were significantly higher than official estimates. This happened because EV motors were not strong sufficient to function independently, leading to engines burning gasoline for nearly one-third of the distance covered in electric mode.

Regulatory and Economic Implications

According to calculations, the lowballing of PHEV emissions allowed four major carmaker companies to avoid more than €5bn in penalties from 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ standards.

Additionally, owners of PHEVs would pay approximately €500 more per year in running expenses than is estimated under lab tests.

“The bold claims that automakers often promote about their plug-in hybrid vehicles are obviously far from the mark,” commented a transport analyst. “Buyers are being duped into believing that by buying a PHEV, they are helping the planet and cutting money. In reality, PHEVs are only slightly better than regular gas and diesel vehicles in terms of energy consumption, CO₂ emissions, and running costs.”

Political Discussion and Automotive Pressure

Hybrid vehicles have recently been brought again into political discussions as carmakers have pressed the European Union to relax CO₂ targets. A proposed ban on sales of new internal combustion vehicles in 2035 has faced intense lobbying from the automotive sector and resistance from EU countries with significant car industries.

Some senior politicians have proposed PHEVs as a potential “compromise” solution to introduce in the legislation.

An external energy economics expert, who was not involved with the research, called the report a “highly valuable contribution” after a long period in which segments of the car industry claimed there was insufficient data to accurately assess actual CO2 output.

“These findings show, beyond any doubt, that the difference in official and actual PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or diesel vehicles,” they stated. “All policy changes concerning PHEVs should be made with utmost caution and considering that data.”