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Plug-in hybrid cars produce nearly five times more planet-heating emissions than lab-reported data indicate, according to a recent analysis.

Widening Discrepancy In Lab and Actual CO2 Output

Data shows that PHEVs emit just one-fifth lower CO₂ than conventional gas and diesel cars, based on analysis carried out by a advocacy group. This contrasts sharply with lab tests, which assumed a three-quarters reduction in emissions.

Analysts examined data from onboard fuel consumption meters of eight hundred thousand vehicles sold in Europe from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were nearly five times greater than official estimates, increased from three and a half times in 2021.

“Real-world CO2 output are rising, while lab-reported figures are decreasing,” said a lead researcher involved in the study. “That gap is growing and poses a significant problem. Consequently, PHEVs pollute almost as much as petrol vehicles.”

Primary Reasons Driving the Emissions Gap

Analysts linked the majority of the gap to inflated estimates of the “electric driving share” – the percentage of miles travelled in electric power relative to total mileage. The team found that only 27% of driving was completed in EV mode, whereas lab estimates suggested over four-fifths.

Additionally, when operating in electric mode, pollution amounts were significantly higher than official projections. This occurred because electric motors were not strong enough to operate alone, resulting to engines using fossil fuels for nearly one-third of the distance completed in electric mode.

Regulatory and Financial Implications

Based on estimates, the lowballing of PHEV CO2 output allowed several major carmaker groups to avoid more than €5bn in penalties between 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ targets.

Furthermore, owners of PHEVs could spend about €500 more per year in operating costs than would be estimated under lab conditions.

“The bold claims that automakers often promote about their PHEV vehicles are obviously way off the mark,” stated a transport expert. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the planet and cutting money. Actually, PHEVs are little better than regular gas and diesel cars in terms of fuel consumption, CO₂ production, and running costs.”

Political Discussion and Industry Pressure

Hybrid cars have lately been drawn back into policy discussions as carmakers have lobbied the EU to relax CO₂ standards. A planned ban on new internal combustion cars in 2035 has faced intense pressure from the automotive sector and opposition from member states with significant automotive manufacturing.

Several senior politicians have proposed plug-in hybrids as a possible “flexibility” option to include in the regulation.

An external energy economics expert, who was unaffiliated with the research, called the analysis a “very useful contribution” after a long period in which parts of the automotive sector claimed there was too little data to properly assess actual CO2 output.

“The results demonstrate, without question, that the gap between lab and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for gasoline or conventional cars,” they said. “All regulatory changes concerning PHEVs should be made with utmost care and considering that data.”