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Plug-in hybrid electric vehicles release nearly 5x more planet-heating emissions than official data indicate, according to a recent analysis.

Growing Gap In Lab and Real-World CO2 Output

Data shows that PHEVs release only one-fifth lower CO₂ than conventional petrol and diesel cars, according to analysis conducted by a advocacy organization. This contrasts sharply with lab tests, which suggested a 75% reduction in pollution.

Analysts examined data from onboard energy use meters of eight hundred thousand cars sold in the EU from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, up from 3.5 times in 2021.

“Actual CO2 output are increasing, while lab-reported emissions are falling,” stated a senior researcher involved in the report. “This gap is widening and creates a serious problem. Consequently, PHEVs pollute almost as heavily as gasoline vehicles.”

Key Factors Behind the Emissions Gap

Analysts linked the majority of the gap to inflated estimates of the “utility factor” – the ratio of kilometers driven in battery power compared to total mileage. The team determined that only a quarter of driving was done in EV mode, whereas lab estimates suggested over four-fifths.

Even, when operating in electric mode, emission amounts were well above lab estimates. That occurred because electric motors were insufficiently powerful enough to function independently, resulting to combustion motors burning gasoline for nearly one-third of the distance covered in EV mode.

Regulatory and Financial Implications

According to estimates, the lowballing of PHEV CO2 output enabled four large automaker companies to avoid more than €5bn in fines from 2021 and 2023, by falsely easing compliance with EU average fleet CO₂ standards.

Additionally, owners of PHEVs would pay about €500 more annually in running expenses than would be estimated under lab tests.

“The bold claims that automakers like to make about their PHEV cars are clearly way off the truth,” stated a transport expert. “Consumers are being duped into thinking that by buying a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are little better than regular gas and diesel cars in terms of energy use, CO₂ production, and running costs.”

Policy Discussion and Industry Pressure

Plug-in hybrid vehicles have lately been drawn back into political discussions as carmakers have pressed the EU to weaken CO₂ standards. A planned ban on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the automotive industry and opposition from member states with significant automotive manufacturing.

Several high-level officials have suggested PHEVs as a possible “compromise” option to introduce in the regulation.

An external energy policy expert, who was not involved with the study, described the analysis a “highly valuable addition” after years in which segments of the automotive industry argued there was insufficient data to properly assess real-world emissions.

“These findings demonstrate, beyond any doubt, that the difference between lab and actual PHEV fuel consumption and CO₂ output is much, much larger than for petrol or diesel vehicles,” they said. “Any regulatory changes regarding PHEVs should be implemented with utmost care and in the light of that data.”