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PHEVs produce nearly 5x greater planet-heating emissions than official data show, according to a new report.

Growing Discrepancy In Lab and Real-World Emissions

Statistics reveals that PHEVs emit just 19% less CO₂ than traditional petrol and diesel vehicles, based on analysis carried out by a non-profit organization. That contrasts sharply with laboratory tests, which assumed a 75% decrease in emissions.

Researchers studied data from in-vehicle energy use meters of eight hundred thousand vehicles sold in the EU from 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official estimates, increased from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported figures are decreasing,” said a senior researcher participating in the report. “That gap is widening and poses a serious issue. Consequently, PHEVs emit almost as heavily as petrol vehicles.”

Key Factors Behind the Discrepancy

Researchers attributed most of the difference to overestimates of the “utility factor” – the percentage of kilometers travelled in battery power compared to total mileage. They determined that just 27% of driving was completed in EV mode, whereas official estimates suggested over four-fifths.

Even, when operating in EV mode, pollution levels were well above official estimates. This happened because EV motors were insufficiently powerful sufficient to operate independently, leading to combustion motors burning gasoline for almost one-third of the distance covered in EV mode.

Policy and Financial Implications

Based on estimates, the lowballing of PHEV emissions allowed four large automaker companies to avoid more than €5bn in fines from 2021 and 2023, by falsely easing compliance with EU average fleet CO₂ targets.

Additionally, drivers of PHEVs would pay about €500 extra per year in operating costs than is estimated under laboratory tests.

“The strong statements that automakers often promote about their plug-in hybrid vehicles are obviously far from the mark,” commented a automotive expert. “Buyers are being duped into thinking that by purchasing a PHEV, they are helping the environment and cutting money. In reality, PHEVs are little better than standard petrol and diesel vehicles in terms of energy use, CO₂ production, and running expenses.”

Political Debate and Industry Pressure

Plug-in hybrid vehicles have recently been drawn back into political debates as automakers have lobbied the European Union to weaken CO₂ standards. A proposed ban on new internal combustion cars in 2035 has faced heavy pressure from the car sector and opposition from member states with large car manufacturing.

Some high-level officials have proposed PHEVs as a possible “flexibility” solution to include in the legislation.

An independent energy policy expert, who was unaffiliated with the research, described the report a “very useful contribution” after a long period in which segments of the car industry claimed there was insufficient information to accurately evaluate actual CO2 output.

“These findings show, beyond any doubt, that the gap between lab and actual PHEV fuel consumption and CO₂ output is much, much greater than for gasoline or conventional vehicles,” they said. “Any policy changes concerning PHEVs should be made with extreme caution and considering this data.”