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Plug-in hybrid electric vehicles emit almost five times more global warming emissions than official figures indicate, according to a recent report.

Growing Discrepancy In Lab and Real-World CO2 Output

Statistics reveals that PHEVs release just 19% less CO₂ than conventional gas and diesel vehicles, based on analysis carried out by a non-profit organization. That differs sharply with lab estimates, which assumed a 75% reduction in pollution.

Researchers studied information from onboard energy use meters of eight hundred thousand cars sold in Europe between 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, up from 3.5 times in 2021.

“Actual emissions are increasing, while official figures are decreasing,” said a lead researcher involved in the report. “That discrepancy is widening and creates a serious problem. Consequently, PHEVs emit almost as much as gasoline cars.”

Primary Factors Driving the Emissions Gap

Researchers linked most of the gap to inflated estimates of the “electric driving share” – the percentage of miles travelled in battery power compared to total distance. The team determined that only a quarter of driving was done in electric mode, whereas official estimates suggested 84%.

Even, when operating in EV mode, emission amounts were well above lab estimates. This occurred because electric motors were insufficiently powerful enough to function independently, leading to engines burning fossil fuels for almost a third of the travel completed in EV mode.

Policy and Economic Implications

Based on estimates, the underestimation of PHEV emissions allowed several large automaker groups to escape more than €5bn in penalties from 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ targets.

Furthermore, owners of PHEVs would spend approximately €500 extra per year in running expenses than would be estimated under lab conditions.

“The bold statements that manufacturers often promote about their plug-in hybrid vehicles are obviously way off the truth,” stated a automotive expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are helping the environment and saving costs. In reality, PHEVs are little improved than regular petrol and diesel cars in terms of fuel consumption, CO₂ production, and operating costs.”

Policy Discussion and Industry Pressure

Plug-in hybrid vehicles have lately been drawn again into political discussions as automakers have lobbied the European Union to weaken CO₂ targets. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced heavy pressure from the automotive industry and opposition from EU countries with large automotive manufacturing.

Some high-level officials have proposed PHEVs as a potential “compromise” solution to introduce in the legislation.

An external energy policy expert, who was not involved with the study, called the analysis a “highly valuable addition” after a long period in which parts of the car industry claimed there was insufficient information to accurately assess actual CO2 output.

“The results show, without question, that the difference between official and actual PHEV energy use and CO₂ output is significantly larger than for gasoline or conventional vehicles,” they stated. “All regulatory changes concerning PHEVs should be made with extreme care and considering that evidence.”