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Plug-in hybrid electric vehicles emit almost 5x more planet-heating emissions than lab-reported figures show, as per a recent report.

Widening Discrepancy Between Official and Real-World Emissions

Data shows that PHEVs release only 19% less CO₂ than conventional gas and diesel cars, according to research carried out by a advocacy organization. This contrasts sharply with laboratory tests, which assumed a three-quarters reduction in emissions.

Researchers examined data from onboard energy use monitors of 800,000 cars sold in Europe from 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, up from three and a half times in 2021.

“Real-world CO2 output are increasing, while official emissions are decreasing,” stated a senior researcher involved in the report. “That gap is widening and poses a serious problem. Consequently, PHEVs pollute almost as heavily as petrol cars.”

Key Factors Driving the Discrepancy

Researchers linked the majority of the gap to overestimates of the “electric driving share” – the percentage of kilometers travelled in battery power compared to total distance. They determined that just 27% of travel was done in EV mode, while official assumptions assumed over four-fifths.

Even, when operating in EV mode, pollution amounts were significantly higher than lab projections. This occurred because electric motors were insufficiently powerful enough to operate independently, resulting to combustion motors using fossil fuels for nearly one-third of the distance covered in EV mode.

Regulatory and Financial Implications

According to estimates, the underestimation of PHEV emissions allowed several major carmaker companies to avoid over €5bn in fines from 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ standards.

Furthermore, drivers of PHEVs could spend approximately €500 more per year in operating costs than would be estimated under lab tests.

“The strong statements that manufacturers often promote about their plug-in hybrid cars are clearly way off the truth,” commented a transport analyst. “Consumers are being duped into thinking that by purchasing a PHEV, they are helping the environment and saving money. In reality, PHEVs are little improved than standard gas and diesel cars in terms of fuel use, CO₂ production, and running expenses.”

Policy Discussion and Automotive Lobbying

Hybrid cars have lately been drawn again into political discussions as carmakers have pressed the European Union to relax CO₂ targets. A proposed prohibition on new internal combustion vehicles in 2035 has faced heavy lobbying from the car industry and resistance from member states with large car industries.

Several senior politicians have proposed PHEVs as a possible “flexibility” option to include in the regulation.

An independent energy policy specialist, who was unaffiliated with the study, called the report a “highly valuable addition” after a long period in which parts of the car industry argued there was too little data to properly assess actual CO2 output.

“The results demonstrate, without question, that the difference in lab and real-world PHEV energy use and CO₂ output is significantly greater than for petrol or conventional cars,” the expert said. “All regulatory changes regarding PHEVs should be made with utmost care and in the light of this evidence.”