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PHEVs release nearly five times greater planet-heating pollution than lab-reported figures show, according to a new report.

Widening Discrepancy In Official and Real-World CO2 Output

Statistics shows that PHEVs release just one-fifth lower CO₂ than conventional gas and diesel vehicles, according to analysis carried out by a advocacy organization. That contrasts significantly with lab estimates, which suggested a 75% decrease in emissions.

Researchers studied data from onboard fuel consumption meters of 800,000 vehicles sold in the EU from 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, increased from 3.5 times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are falling,” said a senior analyst involved in the study. “That gap is widening and poses a serious issue. As a result, PHEVs emit almost as much as petrol vehicles.”

Key Reasons Behind the Emissions Gap

Analysts linked most of the gap to overestimates of the “electric driving share” – the ratio of kilometers driven in battery power compared to overall distance. The team determined that just a quarter of travel was done in electric mode, whereas lab assumptions suggested over four-fifths.

Additionally, when running in electric mode, emission levels were well above lab projections. This occurred because electric motors were not strong enough to operate independently, leading to engines burning gasoline for nearly a third of the distance covered in electric mode.

Policy and Financial Implications

According to calculations, the underestimation of PHEV CO2 output allowed several major carmaker groups to escape more than €5bn in fines from 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ targets.

Furthermore, drivers of PHEVs would spend approximately €500 more per year in operating costs than is estimated under laboratory conditions.

“The strong statements that manufacturers like to make about their PHEV vehicles are clearly far from the truth,” stated a transport analyst. “Consumers are being duped into thinking that by purchasing a PHEV, they are helping the environment and saving costs. Actually, PHEVs are only slightly improved than standard gas and diesel cars in terms of fuel consumption, CO₂ production, and running expenses.”

Political Discussion and Automotive Lobbying

Plug-in hybrid cars have lately been drawn back into policy debates as automakers have pressed the EU to weaken CO₂ targets. A planned ban on new combustion engine vehicles in 2035 has faced heavy lobbying from the car industry and opposition from member states with large car industries.

Several high-level officials have proposed PHEVs as a potential “flexibility” option to include in the regulation.

One external energy economics expert, who was not involved with the study, described the analysis a “very useful addition” after a long period in which parts of the automotive industry argued there was too little information to properly assess real-world emissions.

“The results show, beyond any doubt, that the gap in lab and actual PHEV fuel consumption and CO₂ output is significantly larger than for petrol or conventional cars,” they stated. “All regulatory changes concerning PHEVs should be made with extreme care and in the light of that evidence.”