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Plug-in hybrid cars emit nearly five times more planet-heating emissions than official data show, as per a new report.

Growing Discrepancy In Official and Actual CO2 Output

Data reveals that PHEVs release just one-fifth lower CO₂ than traditional petrol and diesel cars, according to analysis carried out by a advocacy group. This differs significantly with lab estimates, which assumed a three-quarters decrease in emissions.

Analysts studied data from onboard fuel consumption meters of eight hundred thousand cars sold in the EU from 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official estimates, increased from three and a half times in 2021.

“Real-world CO2 output are rising, while lab-reported figures are decreasing,” said a senior researcher participating in the report. “That gap is growing and creates a significant issue. Consequently, PHEVs pollute almost as heavily as gasoline cars.”

Key Factors Behind the Discrepancy

Analysts attributed most of the gap to overestimates of the “electric driving share” – the ratio of kilometers travelled in battery power relative to overall mileage. They found that only a quarter of driving was completed in EV mode, while official estimates assumed over four-fifths.

Additionally, when operating in EV mode, pollution amounts were significantly higher than lab projections. That occurred because electric motors were insufficiently powerful enough to operate alone, leading to engines burning gasoline for nearly one-third of the distance completed in EV mode.

Regulatory and Financial Implications

Based on estimates, the lowballing of PHEV CO2 output enabled four large automaker groups to avoid more than €5bn in penalties from 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ targets.

Furthermore, drivers of PHEVs could pay about €500 extra annually in operating costs than is assumed under lab tests.

“The bold claims that manufacturers like to make about their plug-in hybrid vehicles are clearly far from the mark,” stated a transport analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and saving money. Actually, PHEVs are only slightly improved than regular petrol and diesel cars in terms of fuel use, CO₂ production, and operating costs.”

Policy Debate and Industry Pressure

Hybrid vehicles have lately been brought again into political debates as automakers have lobbied the EU to weaken CO₂ standards. A proposed ban on new combustion engine cars in 2035 has faced intense pressure from the car sector and opposition from member states with large automotive industries.

Several high-level politicians have suggested PHEVs as a possible “compromise” option to introduce in the regulation.

An independent energy policy specialist, who was not involved with the study, called the report a “highly valuable addition” after years in which parts of the automotive sector claimed there was insufficient information to accurately evaluate actual emissions.

“The results demonstrate, beyond any doubt, that the difference between official and actual PHEV energy use and CO₂ emissions is significantly larger than for gasoline or conventional cars,” they stated. “All policy changes regarding PHEVs should be made with utmost care and considering this evidence.”