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PHEVs produce nearly five times more global warming emissions than official data show, according to a recent report.

Widening Discrepancy In Lab and Actual CO2 Output

Statistics shows that PHEVs emit only one-fifth less CO₂ than traditional petrol and diesel cars, based on research carried out by a advocacy group. This contrasts sharply with laboratory estimates, which suggested a 75% decrease in emissions.

Analysts examined information from in-vehicle energy use monitors of 800,000 vehicles registered in the EU from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than official figures, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official figures are falling,” said a lead researcher participating in the report. “That gap is growing and poses a significant problem. Consequently, PHEVs emit almost as much as petrol cars.”

Primary Reasons Behind the Emissions Gap

Analysts linked most of the difference to overestimates of the “electric driving share” – the percentage of kilometers driven in battery power compared to total distance. The team found that just 27% of travel was completed in EV mode, while official estimates suggested over four-fifths.

Even, when operating in EV mode, emission amounts were well above official estimates. That happened because electric motors were insufficiently powerful enough to function independently, leading to combustion motors using gasoline for nearly one-third of the distance completed in EV mode.

Policy and Financial Consequences

Based on estimates, the lowballing of PHEV CO2 output allowed several large carmaker groups to escape more than €5bn in penalties between 2021 and 2023, by artificially easing compliance with EU average fleet CO₂ standards.

Additionally, drivers of PHEVs would spend approximately €500 more annually in running costs than is estimated under lab tests.

“The strong claims that manufacturers often promote about their plug-in hybrid cars are clearly far from the truth,” stated a automotive expert. “Buyers are being duped into thinking that by buying a PHEV, they are helping the planet and cutting costs. Actually, PHEVs are only slightly improved than regular gas and diesel cars in terms of energy use, CO₂ production, and running costs.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid vehicles have recently been brought again into policy debates as automakers have lobbied the EU to weaken CO₂ targets. A planned ban on new internal combustion cars in 2035 has faced heavy pressure from the automotive industry and resistance from EU countries with significant automotive manufacturing.

Several senior officials have proposed plug-in hybrids as a possible “compromise” option to introduce in the legislation.

An independent energy policy specialist, who was unaffiliated with the study, called the report a “very useful addition” after years in which parts of the car industry claimed there was too little data to properly evaluate actual emissions.

“The results show, without question, that the difference in lab and actual PHEV fuel consumption and CO₂ emissions is significantly greater than for gasoline or diesel cars,” they stated. “All policy changes concerning PHEVs should be implemented with extreme care and considering that data.”