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Plug-in hybrid cars produce almost 5x greater planet-heating emissions than official data show, according to a recent analysis.

Growing Gap In Lab and Real-World Emissions

Data shows that PHEVs release just 19% lower CO₂ than conventional gas and diesel cars, according to analysis carried out by a advocacy organization. That differs significantly with lab tests, which suggested a three-quarters reduction in pollution.

Researchers examined data from onboard energy use meters of 800,000 cars registered in the EU between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than official estimates, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official figures are decreasing,” stated a lead analyst participating in the report. “This discrepancy is growing and creates a serious issue. Consequently, PHEVs emit almost as heavily as gasoline vehicles.”

Key Reasons Driving the Discrepancy

Researchers attributed most of the difference to inflated estimates of the “utility factor” – the percentage of miles driven in electric mode relative to total distance. They determined that only 27% of travel was done in electric mode, while official estimates suggested over four-fifths.

Even, when operating in EV mode, pollution levels were well above official estimates. This occurred because EV motors were insufficiently powerful sufficient to operate alone, leading to engines using fossil fuels for nearly one-third of the distance covered in EV mode.

Policy and Economic Consequences

According to calculations, the lowballing of PHEV emissions enabled several major carmaker groups to escape over €5bn in penalties between 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ standards.

Additionally, owners of PHEVs would spend approximately €500 more per year in operating costs than is assumed under lab tests.

“The strong claims that manufacturers often promote about their plug-in hybrid vehicles are clearly way off the mark,” commented a automotive analyst. “Buyers are being duped into thinking that by buying a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are little better than regular petrol and diesel vehicles in terms of energy consumption, CO₂ production, and running costs.”

Political Discussion and Automotive Lobbying

Hybrid cars have lately been drawn again into policy discussions as carmakers have lobbied the European Union to weaken CO₂ targets. A proposed ban on sales of new internal combustion vehicles in 2035 has faced heavy pressure from the car industry and opposition from EU countries with significant car industries.

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

One independent energy economics expert, who was unaffiliated with the study, described the analysis a “highly valuable addition” after years in which parts of the car sector claimed there was insufficient data to properly assess real-world CO2 output.

“The results show, beyond any doubt, that the difference in lab and actual PHEV energy use and CO₂ emissions is significantly larger than for petrol or diesel cars,” they stated. “Any regulatory adjustments regarding PHEVs should be made with extreme care and considering that data.”