🔗 Share this article

Plug-in hybrid cars produce nearly five times greater planet-heating pollution than lab-reported figures show, according to a new report.

Growing Gap Between Official and Actual CO2 Output

Statistics shows that PHEVs release just one-fifth less CO₂ than traditional petrol and diesel vehicles, according to research carried out by a advocacy group. This differs sharply with lab tests, which suggested a 75% decrease in pollution.

Researchers studied data from in-vehicle energy use monitors of 800,000 vehicles registered in Europe between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official estimates, up from three and a half times in 2021.

“Actual CO2 output are rising, while lab-reported figures are decreasing,” stated a senior analyst participating in the report. “That discrepancy is widening and creates a significant problem. Consequently, PHEVs pollute almost as heavily as gasoline cars.”

Key Factors Behind the Discrepancy

Analysts linked most of the gap to inflated estimates of the “utility factor” – the ratio of kilometers driven in battery power compared to total mileage. The team determined that only 27% of driving was done in EV mode, whereas official assumptions suggested over four-fifths.

Even, when running in electric mode, pollution levels were well above official estimates. This occurred because electric motors were not strong enough to operate alone, leading to engines burning gasoline for nearly one-third of the travel completed in electric mode.

Regulatory and Financial Consequences

According to estimates, the lowballing of PHEV CO2 output allowed four large carmaker groups to escape more than €5bn in penalties between 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ standards.

Additionally, drivers of PHEVs would pay approximately €500 more per year in running expenses than would be assumed under laboratory tests.

“The bold claims that automakers like to make about their PHEV vehicles are obviously far from the mark,” commented a transport expert. “Consumers are being duped into thinking that by buying a PHEV, they are helping the environment and cutting money. In reality, PHEVs are little improved than standard gas and diesel cars in terms of fuel use, CO₂ production, and operating costs.”

Policy Debate and Automotive Lobbying

Hybrid vehicles have recently been brought again into policy debates as carmakers have pressed the EU to weaken CO₂ targets. A proposed prohibition on new combustion engine vehicles in 2035 has faced intense pressure from the automotive sector and resistance from member states with significant automotive manufacturing.

Some senior politicians have proposed PHEVs as a potential “compromise” option to include in the legislation.

One independent energy economics expert, who was unaffiliated with the study, called the analysis a “highly valuable contribution” after a long period in which segments of the car sector argued there was insufficient information to properly evaluate real-world CO2 output.

“The results show, beyond any doubt, that the gap between official and actual PHEV energy use and CO₂ emissions is significantly greater than for petrol or conventional cars,” the expert stated. “All regulatory adjustments concerning PHEVs should be made with utmost caution and in the light of this data.”