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Plug-in hybrid electric vehicles release almost 5x greater planet-heating pollution than lab-reported data show, as per a recent analysis.

Widening Discrepancy Between Official and Real-World CO2 Output

Data reveals that PHEVs emit only 19% less CO₂ than conventional gas and diesel cars, based on analysis carried out by a advocacy group. That differs significantly with lab tests, which assumed a 75% decrease in emissions.

Analysts studied information from onboard energy use meters of 800,000 vehicles sold in Europe from 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official estimates, up from three and a half times in 2021.

“Actual emissions are rising, while official emissions are decreasing,” stated a lead researcher participating in the study. “That discrepancy is widening and poses a serious problem. Consequently, PHEVs emit nearly as much as gasoline vehicles.”

Key Reasons Driving the Emissions Gap

Analysts attributed most of the gap to overestimates of the “electric driving share” – the ratio of kilometers travelled in electric power compared to total distance. The team determined that only 27% of driving was done in electric mode, whereas official assumptions assumed over four-fifths.

Additionally, when running in EV mode, emission levels were significantly higher than official estimates. That occurred because electric motors were insufficiently powerful sufficient to function alone, leading to combustion motors using gasoline for nearly one-third of the distance completed in electric mode.

Policy and Economic Consequences

According to estimates, the lowballing of PHEV emissions enabled four major carmaker groups to avoid over €5bn in fines from 2021 and 2023, by falsely easing compliance with EU fleet-average CO₂ targets.

Additionally, drivers of PHEVs could pay about €500 more per year in operating costs than is assumed under laboratory tests.

“The bold claims that automakers often promote about their plug-in hybrid vehicles are obviously way off the truth,” stated a automotive expert. “Buyers are being duped into thinking that by purchasing a PHEV, they are benefiting the planet and cutting money. Actually, PHEVs are little better than standard gas and diesel cars in terms of energy consumption, CO₂ production, and operating expenses.”

Political Debate and Automotive Pressure

Hybrid cars have recently been brought back into political debates as carmakers have lobbied the European Union to weaken CO₂ standards. A proposed ban on new internal combustion cars in 2035 has faced intense lobbying from the automotive industry and opposition from member states with large automotive industries.

Several senior officials have proposed plug-in hybrids as a possible “flexibility” option to introduce in the regulation.

An independent energy policy specialist, who was unaffiliated with the research, described the analysis a “highly valuable addition” after years in which segments of the car sector argued there was insufficient data to properly evaluate actual CO2 output.

“The results demonstrate, beyond any doubt, that the difference in lab and actual PHEV energy use and CO₂ emissions is much, much greater than for gasoline or diesel cars,” they said. “Any policy changes regarding PHEVs should be implemented with extreme care and in the light of that evidence.”