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Plug-in hybrid electric vehicles emit almost 5x greater planet-heating emissions than official data show, as per a new analysis.

Widening Discrepancy In Lab and Actual CO2 Output

Data shows that PHEVs release just 19% less CO₂ than conventional gas and diesel cars, according to research carried out by a advocacy organization. This differs significantly with laboratory estimates, which suggested a 75% decrease in emissions.

Analysts studied data from in-vehicle energy use monitors of eight hundred thousand vehicles sold in the EU from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than official estimates, up from 3.5 times in 2021.

“Actual emissions are increasing, while official emissions are decreasing,” stated a senior analyst involved in the report. “That discrepancy is widening and poses a serious problem. Consequently, PHEVs pollute nearly as heavily as petrol vehicles.”

Key Factors Driving the Discrepancy

Analysts linked most of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers driven in battery power relative to total mileage. They determined that just 27% of travel was done in EV mode, whereas official estimates suggested over four-fifths.

Even, when operating in electric mode, pollution amounts were well above official estimates. This happened because EV motors were insufficiently powerful sufficient to operate alone, leading to engines burning fossil fuels for nearly one-third of the distance covered in EV mode.

Regulatory and Financial Consequences

Based on calculations, the underestimation of PHEV CO2 output allowed several major automaker companies to avoid more than €5bn in fines from 2021 and 2023, by falsely simplifying compliance with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would pay about €500 extra annually in running costs than is estimated under laboratory conditions.

“The strong statements that automakers like to make about their PHEV cars are clearly far from the truth,” stated a automotive analyst. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the planet and cutting money. In reality, PHEVs are only slightly improved than standard gas and diesel vehicles in terms of energy consumption, CO₂ emissions, and operating expenses.”

Political Debate and Industry Pressure

Plug-in hybrid cars have lately been drawn again into policy discussions as carmakers have lobbied the EU to weaken CO₂ targets. A proposed ban on sales of new combustion engine cars in 2035 has faced intense lobbying from the automotive industry and opposition from member states with large car industries.

Several senior officials have suggested plug-in hybrids as a possible “compromise” solution to introduce in the regulation.

One independent energy policy expert, who was unaffiliated with the study, described the report a “highly valuable contribution” after a long period in which segments of the automotive sector argued there was insufficient information to accurately evaluate actual emissions.

“The results demonstrate, beyond any doubt, that the difference between lab and actual PHEV energy use and CO₂ output is significantly larger than for petrol or diesel vehicles,” they stated. “All regulatory changes regarding PHEVs should be made with extreme care and in the light of that evidence.”