🔗 Share this article

Plug-in hybrid cars produce nearly 5x more planet-heating pollution than official data indicate, according to a new analysis.

Widening Gap Between Official and Actual Emissions

Statistics shows that PHEVs emit just one-fifth less CO₂ than traditional petrol and diesel cars, according to research conducted by a non-profit group. That differs significantly with lab estimates, which assumed a 75% reduction in pollution.

Analysts studied information from in-vehicle fuel consumption monitors of 800,000 cars registered in Europe from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than lab estimates, increased from three and a half times in 2021.

“Actual emissions are rising, while lab-reported figures are decreasing,” stated a lead analyst participating in the study. “That gap is growing and poses a significant issue. As a result, PHEVs emit nearly as much as gasoline vehicles.”

Key Factors Behind the Emissions Gap

Analysts attributed most of the difference to overestimates of the “electric driving share” – the ratio of kilometers driven in electric power compared to total mileage. They found that just 27% of driving was done in EV mode, whereas official estimates suggested over four-fifths.

Even, when operating in EV mode, pollution levels were well above lab estimates. That happened because EV motors were not strong enough to function independently, leading to engines using fossil fuels for almost one-third of the distance completed in electric mode.

Regulatory and Economic Implications

Based on calculations, the lowballing of PHEV emissions enabled several major carmaker groups to avoid more than €5bn in penalties between 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ targets.

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

“The strong statements that automakers like to make about their PHEV vehicles are clearly way off the truth,” stated a transport expert. “Buyers are being duped into thinking that by buying a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are only slightly improved than standard petrol and diesel cars in terms of energy consumption, CO₂ emissions, and running costs.”

Political Discussion and Automotive Lobbying

Hybrid cars have lately been drawn back 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 intense lobbying from the car industry and resistance from EU countries with large automotive manufacturing.

Several high-level politicians have suggested plug-in hybrids as a potential “compromise” option to include in the legislation.

One independent energy policy specialist, who was not involved with the study, called the report a “very useful addition” after years in which segments of the car industry claimed there was insufficient data to properly assess real-world CO2 output.

“These findings show, without question, that the difference in official and actual PHEV fuel consumption and CO₂ output is significantly greater than for gasoline or diesel vehicles,” they said. “Any policy changes regarding PHEVs should be implemented with utmost care and in the light of this data.”