Plug in Hybrid Vehicles Pollute Almost as Heavily as Gasoline Cars, Report Reveals

Plug-in hybrid electric vehicles emit almost 5x more global warming emissions than lab-reported data show, as per a recent report.

Widening Discrepancy Between Official and Actual Emissions

Statistics reveals that PHEVs release only 19% less CO₂ than conventional gas and diesel vehicles, based on analysis carried out by a advocacy group. This differs significantly with lab estimates, which suggested a 75% decrease in pollution.

Analysts examined information from onboard energy use monitors of eight hundred thousand vehicles registered in the EU between 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while official figures are decreasing,” said a senior analyst participating in the report. “This discrepancy is widening and creates a serious issue. Consequently, PHEVs emit nearly as heavily as petrol cars.”

Key Reasons Driving the Emissions Gap

Researchers linked the majority of the difference to overestimates of the “utility factor” – the percentage of kilometers travelled in electric mode relative to overall mileage. The team found that just 27% of travel was completed in EV mode, while official estimates suggested over four-fifths.

Additionally, when running in electric mode, emission levels were well above official projections. That occurred because electric motors were not strong enough to operate independently, leading to combustion motors using gasoline for nearly a third of the travel completed in EV mode.

Policy and Economic Consequences

According to estimates, the underestimation of PHEV CO2 output allowed several large carmaker companies to escape over €5bn in penalties from 2021 and 2023, by artificially easing compliance with EU average fleet CO₂ targets.

Additionally, drivers of PHEVs could pay about €500 extra per year in running expenses than would be estimated under lab tests.

“The strong statements that automakers often promote about their PHEV cars are clearly far from the mark,” commented a transport expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are benefiting the planet and cutting money. Actually, PHEVs are little better than standard petrol and diesel vehicles in terms of fuel use, CO₂ emissions, and running costs.”

Policy Debate and Automotive Pressure

Plug-in hybrid cars have recently been drawn back into policy discussions as carmakers have lobbied the European Union to weaken CO₂ targets. A planned ban on new combustion engine vehicles in 2035 has faced intense lobbying from the automotive industry and opposition from member states with large car manufacturing.

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

An external energy policy expert, who was unaffiliated with the study, called the report a “very useful addition” after a long period in which parts of the automotive industry argued there was insufficient information to accurately evaluate actual emissions.

“The results show, beyond any doubt, that the gap between official and actual PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or conventional vehicles,” they stated. “All regulatory adjustments concerning PHEVs should be made with extreme care and considering this evidence.”