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Plug-in hybrid cars release almost 5x more global warming emissions than official data show, as per a new report.

Widening Discrepancy In Official and Actual Emissions

Data shows that PHEVs emit only 19% less CO₂ than traditional petrol and diesel cars, according to analysis conducted by a non-profit organization. This differs significantly with laboratory tests, which assumed a 75% decrease in pollution.

Analysts studied data from onboard energy use monitors of eight hundred thousand vehicles registered in the EU from 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, up from 3.5 times in 2021.

“Actual CO2 output are rising, while official emissions are decreasing,” said a senior analyst involved in the study. “This gap is widening and creates a significant problem. Consequently, PHEVs emit almost as much as petrol vehicles.”

Primary Factors Driving the Discrepancy

Analysts linked most of the difference to inflated estimates of the “utility factor” – the percentage of kilometers travelled in battery mode relative to total distance. The team determined that just a quarter of driving was done in EV mode, whereas lab estimates suggested over four-fifths.

Even, when running in electric mode, emission amounts were significantly higher than official estimates. That happened because EV motors were not strong sufficient to operate independently, resulting to combustion motors burning gasoline for nearly a third of the distance covered in EV mode.

Policy and Financial Implications

According to calculations, the underestimation of PHEV emissions enabled four large automaker groups to avoid more than €5bn in penalties from 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ standards.

Furthermore, owners of PHEVs would spend approximately €500 extra annually in running costs than is assumed under laboratory conditions.

“The bold statements that manufacturers like to make about their PHEV vehicles are clearly far from the mark,” stated a automotive analyst. “Buyers are being duped into thinking that by buying a PHEV, they are helping the planet and cutting costs. Actually, PHEVs are little better than standard petrol and diesel cars in terms of energy use, CO₂ production, and running expenses.”

Policy Discussion and Industry Lobbying

Hybrid cars have recently been drawn back into policy discussions as automakers have lobbied the European Union to relax CO₂ targets. A planned prohibition on sales of new internal combustion vehicles in 2035 has faced intense lobbying from the automotive sector and opposition from member states with large car industries.

Several high-level officials have proposed plug-in hybrids as a potential “compromise” solution to introduce in the legislation.

An external energy economics specialist, who was not involved with the research, called the analysis a “very useful addition” after a long period in which parts of the automotive industry claimed there was insufficient data to accurately assess real-world emissions.

“The results show, without question, that the difference in lab and actual PHEV energy use and CO₂ output is significantly greater than for petrol or conventional cars,” the expert said. “Any policy changes concerning PHEVs should be made with extreme caution and considering that evidence.”