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PHEVs emit nearly five times greater global warming emissions than lab-reported data indicate, according to a recent analysis.

Widening Gap Between Lab and Real-World CO2 Output

Statistics shows that PHEVs emit only one-fifth lower CO₂ than traditional petrol and diesel vehicles, according to analysis carried out by a advocacy group. This contrasts significantly with lab tests, which suggested a three-quarters reduction in emissions.

Researchers studied data from onboard energy use meters of 800,000 vehicles sold in the EU between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than lab estimates, up from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported figures are decreasing,” said a senior analyst participating in the study. “This gap is widening and poses a serious issue. Consequently, PHEVs pollute nearly as much as gasoline cars.”

Key Factors Behind the Emissions Gap

Analysts attributed most of the gap to overestimates of the “electric driving share” – the percentage of kilometers travelled in battery power relative to total distance. The team determined that just 27% of travel was done in electric mode, while lab assumptions suggested over four-fifths.

Even, when running in EV mode, pollution amounts were significantly higher than lab projections. That happened because electric motors were not strong enough to operate alone, resulting to combustion motors burning gasoline for nearly one-third of the travel covered in electric mode.

Policy and Economic Consequences

Based on calculations, the lowballing of PHEV emissions enabled four large automaker groups to escape more than €5bn in fines from 2021 and 2023, by artificially simplifying compliance with EU average fleet CO₂ standards.

Furthermore, drivers of PHEVs could pay about €500 more annually in operating expenses than is estimated under lab tests.

“The strong statements that manufacturers often promote about their plug-in hybrid cars are obviously far from the truth,” stated a automotive expert. “Buyers are being duped into believing that by purchasing a PHEV, they are helping the environment and cutting money. In reality, PHEVs are only slightly improved than regular petrol and diesel cars in terms of fuel use, CO₂ emissions, and operating expenses.”

Political Debate and Industry Lobbying

Plug-in hybrid vehicles have recently been drawn back into policy discussions as automakers have lobbied the EU to relax CO₂ targets. A planned ban on sales of new internal combustion cars in 2035 has faced heavy pressure from the car sector and resistance from EU countries with large automotive manufacturing.

Several high-level officials have suggested PHEVs as a possible “flexibility” option to introduce in the legislation.

One independent energy policy expert, who was unaffiliated with the research, called the analysis a “highly valuable contribution” after years in which parts of the automotive sector claimed there was too little information to properly assess real-world CO2 output.

“These findings show, beyond any doubt, that the difference in lab and real-world PHEV energy use and CO₂ emissions is much, much greater than for petrol or conventional vehicles,” the expert stated. “Any policy changes regarding PHEVs should be made with utmost care and considering this evidence.”