Plug-in Hybrid Cars Emit Almost as Heavily as Petrol Cars, Study Finds

Plug-in hybrid electric vehicles produce nearly 5x greater global warming emissions than official data show, according to a new analysis.

Widening Gap In Official and Actual Emissions

Statistics shows that PHEVs emit only 19% less CO₂ than traditional gas and diesel vehicles, according to research carried out by a non-profit group. This contrasts sharply with laboratory estimates, which suggested a 75% decrease in emissions.

Researchers studied information from in-vehicle energy use monitors of 800,000 vehicles sold in the EU from 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, increased from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are decreasing,” stated a senior analyst involved in the report. “This gap is growing and poses a significant problem. As a result, PHEVs emit nearly as heavily as gasoline cars.”

Primary Reasons Behind the Emissions Gap

Researchers attributed most of the difference to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in battery mode compared to overall distance. The team determined that just a quarter of travel was done in EV mode, while official assumptions assumed 84%.

Additionally, when operating in EV mode, emission amounts were significantly higher than official projections. That occurred because EV motors were not strong enough to operate independently, resulting to engines burning gasoline for nearly one-third of the travel completed in EV mode.

Regulatory and Financial Consequences

According to calculations, the underestimation of PHEV emissions enabled four large carmaker groups to escape over €5bn in penalties between 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ standards.

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

“The bold claims that automakers like to make about their plug-in hybrid vehicles are obviously way off the mark,” commented a transport expert. “Consumers are being misled into believing that by purchasing a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are only slightly improved than standard gas and diesel cars in terms of energy consumption, CO₂ production, and running expenses.”

Political Discussion and Industry Lobbying

Plug-in hybrid cars have lately been brought again into policy debates as automakers have lobbied the EU to weaken CO₂ standards. A planned ban on new combustion engine cars in 2035 has faced intense pressure from the automotive industry and resistance from member states with significant car industries.

Several high-level officials have proposed PHEVs as a possible “compromise” option to introduce in the regulation.

One independent energy policy 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 sector claimed there was too little data to properly assess real-world CO2 output.

“These findings demonstrate, beyond any doubt, that the difference in official and real-world PHEV energy use and CO₂ emissions is much, much larger than for gasoline or diesel cars,” they stated. “Any policy changes concerning PHEVs should be implemented with extreme caution and considering this data.”