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Plug-in hybrid cars emit almost 5x more planet-heating pollution than official figures show, according to a recent analysis.

Widening Gap In Official and Actual CO2 Output

Data shows that PHEVs emit just 19% lower CO₂ than conventional gas and diesel cars, according to research carried out by a advocacy group. That differs sharply with laboratory tests, which assumed a 75% reduction in emissions.

Analysts examined information from onboard fuel consumption meters of 800,000 vehicles sold in Europe between 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, increased from three and a half times in 2021.

“Actual emissions are rising, while official emissions are decreasing,” said a lead researcher involved in the report. “That gap is widening and creates a serious issue. As a result, PHEVs emit nearly as heavily as petrol vehicles.”

Primary Factors Behind the Emissions Gap

Analysts attributed most of the gap to inflated estimates of the “utility factor” – the percentage of kilometers travelled in battery power relative to total distance. They determined that just a quarter of travel was completed in EV mode, whereas lab estimates suggested over four-fifths.

Even, when operating in electric mode, pollution amounts were significantly higher than official estimates. That happened because EV motors were not strong sufficient to operate independently, leading to combustion motors burning gasoline for nearly one-third of the travel completed in electric mode.

Regulatory and Financial Implications

According to calculations, the lowballing of PHEV emissions allowed several major carmaker companies to avoid more than €5bn in penalties from 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ standards.

Additionally, owners of PHEVs could spend about €500 more per year in operating costs than is assumed under lab conditions.

“The strong statements that manufacturers often promote about their plug-in hybrid cars are obviously way off the mark,” stated a automotive expert. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are only slightly better than standard gas and diesel vehicles in terms of fuel use, CO₂ production, and running costs.”

Policy Debate and Industry Lobbying

Plug-in hybrid cars have recently been brought again into policy discussions as automakers have lobbied the European Union to relax CO₂ targets. A proposed prohibition on new combustion engine cars in 2035 has faced intense pressure from the car sector and resistance from EU countries with large automotive industries.

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

An independent energy policy expert, who was not involved with the study, called the report a “very useful addition” after a long period in which segments of the car industry argued there was too little data to properly evaluate real-world CO2 output.

“The results show, beyond any doubt, that the gap between lab and real-world PHEV energy use and CO₂ output is significantly greater than for petrol or diesel cars,” they stated. “Any policy adjustments regarding PHEVs should be implemented with extreme caution and in the light of that evidence.”