🔗 Share this article

Plug-in hybrid cars release almost 5x greater planet-heating pollution than lab-reported figures indicate, as per a recent analysis.

Growing Gap Between Lab and Real-World CO2 Output

Data reveals that PHEVs release only 19% lower CO₂ than traditional petrol and diesel vehicles, according to analysis carried out by a non-profit organization. That contrasts significantly with lab tests, which assumed a three-quarters reduction in pollution.

Researchers examined information from in-vehicle fuel consumption meters of 800,000 vehicles sold in Europe from 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab estimates, up from 3.5 times in 2021.

“Actual emissions are rising, while lab-reported emissions are decreasing,” said a senior researcher involved in the report. “This gap is growing and poses a serious problem. As a result, PHEVs emit almost as heavily as petrol vehicles.”

Key Factors Behind the Discrepancy

Researchers attributed most of the gap to overestimates of the “utility factor” – the ratio of miles driven in battery mode relative to overall distance. The team found that just 27% of travel was completed in EV mode, while lab estimates assumed over four-fifths.

Additionally, when running in electric mode, pollution amounts were significantly higher than lab projections. That happened because EV motors were not strong sufficient to function independently, resulting to combustion motors using fossil fuels for nearly one-third of the distance completed in electric mode.

Policy and Economic Implications

Based on estimates, the lowballing of PHEV emissions allowed four large carmaker companies to escape over €5bn in penalties from 2021 and 2023, by falsely easing adherence with European Union fleet-average CO₂ targets.

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

“The strong claims that automakers often promote about their PHEV cars are clearly way off the mark,” commented a transport expert. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are only slightly improved than standard gas and diesel cars in terms of fuel use, CO₂ emissions, and operating costs.”

Policy Debate and Industry Lobbying

Plug-in hybrid vehicles have recently been drawn again into political debates as automakers have lobbied the EU to weaken CO₂ targets. A planned ban on new internal combustion cars in 2035 has faced heavy pressure from the car industry and resistance from EU countries with large automotive industries.

Some senior politicians have suggested plug-in hybrids as a possible “compromise” option to introduce in the regulation.

One external energy economics expert, who was unaffiliated with the research, described the report a “highly valuable addition” after a long period in which parts of the automotive sector argued there was insufficient data to accurately evaluate actual CO2 output.

“These findings show, beyond any doubt, that the gap between lab and actual PHEV energy use and CO₂ emissions is much, much larger than for gasoline or conventional cars,” the expert stated. “Any policy changes regarding PHEVs should be implemented with utmost caution and in the light of this data.”