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PHEVs produce nearly five times more planet-heating emissions than official figures show, according to a new report.

Widening Discrepancy Between Official and Real-World Emissions

Statistics reveals that PHEVs emit just one-fifth lower CO₂ than traditional gas and diesel vehicles, based on analysis conducted by a advocacy organization. That differs sharply with laboratory estimates, which assumed a three-quarters reduction in emissions.

Researchers studied data from onboard energy use monitors of eight hundred thousand cars registered in Europe between 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were nearly five times greater than official estimates, increased from 3.5 times in 2021.

“Actual emissions are rising, while official emissions are decreasing,” said a senior analyst involved in the study. “That discrepancy is widening and poses a serious problem. Consequently, PHEVs pollute almost as much as petrol cars.”

Key Reasons Driving the Emissions Gap

Researchers linked most of the gap to inflated estimates of the “utility factor” – the ratio of kilometers driven in battery mode relative to total distance. The team determined that just 27% of travel was done in electric mode, whereas lab estimates assumed over four-fifths.

Additionally, when running in EV mode, emission levels were significantly higher than lab projections. This occurred because EV motors were insufficiently powerful sufficient to operate alone, leading to engines using fossil fuels for almost one-third of the distance completed in EV mode.

Policy and Economic Consequences

Based on estimates, the lowballing of PHEV CO2 output allowed several large automaker companies to avoid over €5bn in penalties from 2021 and 2023, by falsely easing adherence with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs would spend about €500 more per year in running costs than is assumed under laboratory conditions.

“The bold claims that automakers often promote about their plug-in hybrid cars are clearly way off the truth,” commented a automotive expert. “Consumers are being misled into believing that by purchasing a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of energy consumption, CO₂ production, and operating expenses.”

Political Discussion and Automotive Pressure

Plug-in hybrid vehicles have lately been brought back into policy debates as carmakers have lobbied the European Union to relax CO₂ targets. A proposed prohibition on new combustion engine vehicles in 2035 has faced intense pressure from the automotive sector and opposition from EU countries with significant car industries.

Some high-level officials have suggested PHEVs as a possible “compromise” solution to include in the regulation.

An independent energy policy specialist, who was unaffiliated with the study, called the analysis a “highly valuable contribution” after years in which parts of the automotive sector claimed there was insufficient data to accurately evaluate real-world CO2 output.

“These findings demonstrate, beyond any doubt, that the gap in lab and actual PHEV energy use and CO₂ emissions is significantly larger than for gasoline or diesel vehicles,” the expert stated. “Any policy changes concerning PHEVs should be made with extreme care and in the light of that evidence.”