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PHEVs produce almost five times greater planet-heating pollution than lab-reported data indicate, as per a recent analysis.

Widening Discrepancy Between Lab and Actual Emissions

Data shows that PHEVs emit just 19% less CO₂ than traditional gas and diesel cars, according to research carried out by a advocacy group. That differs significantly with lab tests, which assumed a three-quarters decrease in emissions.

Analysts studied information from in-vehicle fuel consumption monitors of 800,000 vehicles registered in the EU between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official estimates, up from 3.5 times in 2021.

“Actual CO2 output are rising, while lab-reported figures are decreasing,” said a senior researcher involved in the study. “That gap is widening and poses a serious problem. Consequently, PHEVs pollute nearly as heavily as gasoline cars.”

Primary Factors Driving the Discrepancy

Analysts linked the majority of the gap to overestimates of the “electric driving share” – the percentage of kilometers travelled in battery power relative to total distance. They found that only a quarter of driving was completed in electric mode, whereas official estimates assumed 84%.

Even, when running in EV mode, pollution amounts were significantly higher than lab projections. This occurred because EV motors were not strong enough to function independently, resulting to engines using fossil fuels for nearly a third of the travel completed in electric mode.

Policy and Financial Implications

According to estimates, the lowballing of PHEV emissions enabled four large carmaker groups to avoid more than €5bn in penalties from 2021 and 2023, by falsely simplifying adherence with EU average fleet CO₂ standards.

Additionally, drivers of PHEVs could spend approximately €500 more per year in running costs than is assumed under lab conditions.

“The strong claims that automakers like to make about their PHEV cars are obviously far from the truth,” stated a automotive expert. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are only slightly improved than regular gas and diesel cars in terms of fuel consumption, CO₂ emissions, and running expenses.”

Political Debate and Industry Lobbying

Hybrid cars have recently been brought again into policy debates as automakers have pressed the European Union to relax CO₂ targets. A proposed prohibition on sales of new combustion engine cars in 2035 has faced heavy pressure from the car industry and resistance from EU countries with large automotive manufacturing.

Some high-level officials have proposed plug-in hybrids as a possible “flexibility” option to introduce in the regulation.

One independent energy economics specialist, who was not involved with the study, described the report a “highly valuable addition” after a long period in which segments of the automotive industry claimed there was too little information to properly assess actual CO2 output.

“The results demonstrate, without question, that the difference between lab and real-world PHEV energy use and CO₂ output is significantly larger than for gasoline or diesel cars,” the expert said. “Any regulatory changes concerning PHEVs should be implemented with utmost care and considering this data.”