Plug-in Hybrid Vehicles Pollute Nearly as Heavily as Gasoline Cars, Study Reveals

Plug-in hybrid electric vehicles produce almost five times more planet-heating emissions than lab-reported figures show, as per a recent analysis.

Widening Gap Between Lab and Real-World Emissions

Data shows that PHEVs release only 19% lower CO₂ than conventional petrol and diesel vehicles, according to research conducted by a non-profit group. This contrasts significantly with lab estimates, which suggested a 75% reduction in emissions.

Analysts examined data from onboard energy use monitors of 800,000 cars registered in the EU from 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official figures are decreasing,” said a senior analyst involved in the report. “This discrepancy is growing and poses a significant problem. Consequently, PHEVs emit almost as much as gasoline vehicles.”

Key Reasons Driving the Discrepancy

Researchers attributed most of the gap to overestimates of the “utility factor” – the ratio of kilometers travelled in electric mode relative to overall distance. They found that just 27% of driving was completed in EV mode, whereas lab estimates suggested 84%.

Even, when operating in electric mode, emission levels were significantly higher than lab estimates. This happened because electric motors were not strong sufficient to operate independently, resulting to combustion motors burning gasoline for nearly a third of the distance completed in electric mode.

Regulatory and Financial Implications

Based on calculations, the lowballing of PHEV emissions allowed four large automaker groups to avoid more than €5bn in fines from 2021 and 2023, by falsely easing compliance with EU average fleet CO₂ targets.

Furthermore, drivers of PHEVs could spend about €500 more per year in operating costs than would be estimated under lab tests.

“The strong claims that manufacturers like to make about their PHEV cars are clearly way off the mark,” commented a automotive expert. “Buyers are being duped into thinking that by buying a PHEV, they are helping the planet and saving costs. In reality, PHEVs are only slightly better than regular petrol and diesel cars in terms of fuel use, CO₂ production, and running costs.”

Political Debate and Automotive Lobbying

Plug-in hybrid cars have lately been brought again into political debates as automakers have lobbied the European Union to weaken CO₂ targets. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced heavy lobbying from the car sector and resistance from EU countries with large car industries.

Several high-level officials have suggested PHEVs as a potential “compromise” option to introduce in the legislation.

An independent energy economics expert, who was not involved with the study, called the report a “very useful addition” after a long period in which parts of the car sector claimed there was too little data to properly assess real-world CO2 output.

“The results demonstrate, without question, that the difference in official and real-world PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or diesel cars,” the expert stated. “Any policy changes regarding PHEVs should be made with utmost care and considering this data.”