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PHEVs emit nearly 5x greater planet-heating pollution than lab-reported data indicate, as per a new analysis.

Widening Gap Between Official and Actual Emissions

Statistics shows that PHEVs emit just one-fifth lower CO₂ than traditional gas and diesel vehicles, according to analysis conducted by a advocacy organization. This differs sharply with laboratory estimates, which suggested a 75% decrease in emissions.

Researchers examined data from in-vehicle energy use meters of 800,000 cars registered in Europe between 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official estimates, up from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported emissions are decreasing,” stated a lead researcher participating in the study. “This discrepancy is growing and poses a significant issue. Consequently, PHEVs emit nearly as heavily as petrol vehicles.”

Primary Factors Driving the Emissions Gap

Researchers attributed most of the gap to inflated estimates of the “utility factor” – the percentage of kilometers travelled in electric mode relative to overall distance. The team found that only a quarter of travel was done in electric mode, whereas lab estimates suggested over four-fifths.

Even, when operating in EV mode, emission amounts were well above official projections. This occurred because EV motors were insufficiently powerful enough to operate independently, resulting to engines using gasoline for almost one-third of the distance completed in EV mode.

Regulatory and Financial Consequences

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

Furthermore, owners of PHEVs could pay approximately €500 more per year in operating costs than is estimated under laboratory conditions.

“The bold statements that manufacturers like to make about their PHEV cars are clearly way off the mark,” stated a transport expert. “Buyers are being duped into thinking that by buying a PHEV, they are helping the planet and saving money. Actually, PHEVs are little better than regular gas and diesel cars in terms of fuel consumption, CO₂ production, and running costs.”

Policy Debate and Automotive Lobbying

Hybrid vehicles have recently been drawn again into policy discussions as carmakers have lobbied the European Union to weaken CO₂ targets. A planned ban on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the car industry and resistance from member states with large automotive industries.

Several senior politicians have proposed plug-in hybrids as a possible “compromise” solution to introduce in the legislation.

An independent energy economics specialist, who was not involved with the study, described the report a “very useful contribution” after a long period in which segments of the automotive industry argued there was insufficient data to properly assess real-world CO2 output.

“These findings demonstrate, without question, that the difference between lab and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or conventional cars,” the expert said. “All regulatory changes regarding PHEVs should be made with extreme caution and in the light of that data.”