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PHEVs produce nearly 5x greater planet-heating pollution than official data indicate, as per a new report.

Widening Gap In Lab and Actual CO2 Output

Data shows that PHEVs release only one-fifth lower CO₂ than traditional gas and diesel vehicles, based on analysis carried out by a non-profit group. This contrasts sharply with laboratory estimates, which assumed a 75% decrease in pollution.

Researchers examined data from in-vehicle fuel consumption meters of eight hundred thousand vehicles registered 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, increased from three and a half times in 2021.

“Real-world emissions are increasing, while official figures are decreasing,” said a senior analyst participating in the study. “That discrepancy is growing and poses a serious problem. As a result, PHEVs emit almost as much as gasoline cars.”

Primary Reasons Behind the Emissions Gap

Analysts linked most of the difference to inflated estimates of the “electric driving share” – the percentage of miles driven in electric power relative to overall mileage. They determined that just 27% of travel was done in electric mode, while official assumptions assumed 84%.

Even, when operating in electric mode, emission amounts were well above lab estimates. This happened because EV motors were not strong enough to operate independently, resulting to engines burning gasoline for nearly a third of the distance completed in electric mode.

Policy and Economic Consequences

According to calculations, the underestimation of PHEV emissions enabled four large carmaker companies to escape over €5bn in fines between 2021 and 2023, by falsely simplifying adherence with European Union fleet-average CO₂ targets.

Furthermore, owners of PHEVs could spend about €500 more per year in running costs than is assumed under laboratory conditions.

“The bold claims that manufacturers often promote about their PHEV cars are clearly far from the truth,” stated a transport expert. “Buyers are being misled into believing that by purchasing a PHEV, they are helping the planet and saving money. In reality, PHEVs are only slightly improved than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and running costs.”

Political Discussion and Industry Lobbying

Plug-in hybrid vehicles have recently been brought again into political debates as carmakers have pressed the European Union to relax CO₂ targets. A proposed ban on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive sector and opposition from EU countries with large car manufacturing.

Several high-level politicians have proposed plug-in hybrids as a potential “compromise” solution to introduce in the legislation.

An external energy policy specialist, who was not involved with the research, described the analysis a “very useful contribution” after a long period in which segments of the automotive industry claimed there was too little data to accurately assess actual emissions.

“These findings demonstrate, without question, that the gap in official and real-world PHEV fuel consumption and CO₂ output is significantly greater than for gasoline or conventional cars,” they stated. “All policy adjustments concerning PHEVs should be made with utmost caution and considering that data.”