Plug in Hybrid electric Vehicles Emit Almost as Much as Gasoline Vehicles, Study Finds

Plug-in hybrid cars release almost 5x greater planet-heating pollution than official data show, according to a new analysis.

Widening Gap Between Official and Real-World Emissions

Statistics reveals that PHEVs emit just 19% less CO₂ than conventional gas and diesel vehicles, according to analysis conducted by a advocacy group. This contrasts significantly with laboratory tests, which assumed a 75% reduction in pollution.

Analysts studied data from in-vehicle energy use meters of eight hundred thousand vehicles registered in the EU from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, up from three and a half times in 2021.

“Real-world CO2 output are rising, while lab-reported emissions are decreasing,” stated a senior analyst involved in the study. “This gap is growing and poses a serious problem. Consequently, PHEVs pollute nearly as heavily as petrol cars.”

Primary Factors Driving the Discrepancy

Analysts attributed the majority of the gap to inflated estimates of the “utility factor” – the ratio of miles travelled in battery power compared to overall mileage. The team found that only a quarter of travel was completed in electric mode, while official estimates assumed over four-fifths.

Additionally, when running in electric mode, emission amounts were well above official estimates. This occurred because EV motors were insufficiently powerful enough to function alone, resulting to combustion motors burning gasoline for almost a third of the distance completed in electric mode.

Regulatory and Financial Implications

Based on estimates, the underestimation of PHEV emissions enabled several large automaker groups to escape more than €5bn in fines from 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ standards.

Additionally, owners of PHEVs could spend about €500 extra per year in running expenses than is assumed under lab conditions.

“The bold claims that automakers like to make about their plug-in hybrid vehicles are obviously far from the mark,” commented a transport expert. “Consumers are being misled into believing that by buying a PHEV, they are helping the environment and saving money. In reality, PHEVs are only slightly better than standard gas and diesel vehicles in terms of energy use, CO₂ emissions, and running costs.”

Political Discussion and Automotive Lobbying

Plug-in hybrid cars have lately been drawn back into policy discussions as automakers have pressed the EU to weaken CO₂ standards. A planned ban on new combustion engine cars in 2035 has faced intense pressure from the car sector and resistance from member states with large automotive manufacturing.

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

An independent energy economics expert, who was unaffiliated with the study, described the report a “highly valuable addition” after years in which parts of the car industry argued there was insufficient information to properly evaluate actual emissions.

“The results show, without question, that the difference between lab and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or diesel cars,” the expert stated. “All policy adjustments concerning PHEVs should be implemented with utmost care and in the light of that evidence.”