🔗 Share this article

PHEVs release almost five times greater planet-heating emissions than official figures show, according to a recent analysis.

Widening Discrepancy Between Official and Actual CO2 Output

Data shows that PHEVs emit just 19% lower CO₂ than traditional gas and diesel cars, according to research carried out by a advocacy group. This contrasts significantly with lab estimates, which assumed a three-quarters reduction in emissions.

Researchers studied data from onboard fuel consumption monitors of eight hundred thousand vehicles sold in the EU between 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were nearly five times greater than lab estimates, up from 3.5 times in 2021.

“Real-world emissions are rising, while lab-reported emissions are decreasing,” stated a senior analyst participating in the study. “That discrepancy is growing and creates a significant issue. As a result, PHEVs pollute almost as much as petrol cars.”

Key Reasons Driving the Emissions Gap

Researchers linked the majority of the gap to overestimates of the “electric driving share” – the ratio of kilometers travelled in battery power relative to overall distance. They determined that only a quarter of travel was done in EV mode, whereas official assumptions assumed 84%.

Additionally, when running in EV mode, pollution amounts were significantly higher than official projections. That occurred because electric motors were not strong sufficient to operate alone, leading to engines using fossil fuels for almost one-third of the travel covered in EV mode.

Policy and Financial Consequences

According to estimates, the underestimation of PHEV CO2 output allowed four major carmaker companies to avoid over €5bn in fines from 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ targets.

Furthermore, drivers of PHEVs could pay approximately €500 more annually in running expenses than is estimated under lab tests.

“The strong statements that automakers often promote about their plug-in hybrid vehicles are obviously far from the mark,” stated a automotive analyst. “Buyers are being misled into believing that by buying a PHEV, they are helping the environment and cutting costs. In reality, PHEVs are little better than standard gas and diesel vehicles in terms of energy consumption, CO₂ emissions, and running costs.”

Policy Discussion and Industry Pressure

Plug-in hybrid cars have recently been drawn back into policy discussions as carmakers have pressed the EU to weaken CO₂ targets. A proposed prohibition on new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive industry and opposition from EU countries with large automotive industries.

Several high-level officials have suggested plug-in hybrids as a potential “compromise” option to include in the regulation.

One external energy policy expert, who was unaffiliated with the study, called the analysis a “very useful addition” after years in which parts of the car sector argued there was insufficient information to properly assess real-world CO2 output.

“The results demonstrate, without question, that the gap between lab and real-world PHEV energy use and CO₂ output is significantly greater than for gasoline or conventional vehicles,” the expert stated. “Any policy changes concerning PHEVs should be made with extreme caution and in the light of this evidence.”