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Plug-in hybrid cars release almost five times greater planet-heating pollution than official figures show, according to a recent analysis.

Widening Gap In Lab and Actual CO2 Output

Statistics shows that PHEVs release only 19% less CO₂ than conventional gas and diesel vehicles, according to analysis carried out by a non-profit group. This differs sharply with lab estimates, which suggested a three-quarters decrease in emissions.

Researchers examined information from onboard fuel consumption meters of eight hundred thousand vehicles registered in Europe from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab estimates, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while official emissions are decreasing,” stated a lead researcher involved in the report. “This gap is growing and creates a serious issue. Consequently, PHEVs pollute nearly as heavily as gasoline cars.”

Primary Reasons Driving the Emissions Gap

Analysts linked most of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers driven in electric mode compared to total distance. The team determined that just 27% of travel was completed in EV mode, whereas official assumptions suggested over four-fifths.

Additionally, when operating in electric mode, emission amounts were significantly higher than lab estimates. That occurred because EV motors were insufficiently powerful enough to operate independently, resulting to combustion motors burning fossil fuels for nearly a third of the distance completed in EV mode.

Regulatory and Financial Consequences

Based on calculations, the lowballing of PHEV CO2 output enabled four large carmaker groups to escape more than €5bn in penalties between 2021 and 2023, by artificially easing adherence with EU fleet-average CO₂ targets.

Additionally, drivers of PHEVs could spend approximately €500 extra per year in running expenses than would be assumed under lab conditions.

“The strong claims that manufacturers like to make about their plug-in hybrid vehicles are obviously far from the truth,” stated a automotive analyst. “Buyers are being misled into thinking that by purchasing a PHEV, they are helping the environment and saving money. Actually, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of fuel use, CO₂ emissions, and operating costs.”

Political Discussion and Industry Pressure

Plug-in hybrid cars have recently been brought again into policy discussions as automakers have pressed the EU to relax CO₂ targets. A proposed prohibition on new internal combustion vehicles in 2035 has faced intense lobbying from the automotive sector and opposition from member states with large automotive industries.

Some high-level politicians have suggested PHEVs as a possible “compromise” solution to include in the legislation.

An independent energy policy expert, who was unaffiliated with the research, described the analysis a “highly valuable contribution” after years in which segments of the car sector claimed there was insufficient information to properly assess actual emissions.

“These findings show, beyond any doubt, that the gap between lab and actual PHEV energy use and CO₂ emissions is significantly larger than for petrol or diesel cars,” the expert stated. “Any policy changes concerning PHEVs should be implemented with utmost caution and considering this evidence.”