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

Plug-in hybrid electric vehicles emit nearly 5x more planet-heating pollution than lab-reported figures show, as per a recent analysis.

Growing Discrepancy Between Official and Real-World CO2 Output

Statistics reveals that PHEVs emit just 19% lower CO₂ than conventional petrol and diesel cars, based on research carried out by a non-profit group. This differs significantly with lab tests, which suggested a 75% reduction in pollution.

Analysts examined information from in-vehicle fuel consumption monitors of eight hundred thousand cars registered in Europe from 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, up from 3.5 times in 2021.

“Actual CO2 output are increasing, while lab-reported figures are falling,” stated a senior analyst participating in the study. “This discrepancy is widening and poses a serious issue. As a result, PHEVs emit nearly as much as petrol cars.”

Key Factors Driving the Discrepancy

Analysts linked most of the gap to overestimates of the “utility factor” – the ratio of kilometers driven in battery mode relative to total mileage. They found that just a quarter of driving was done in electric mode, while official assumptions assumed over four-fifths.

Even, when operating in electric mode, emission amounts were significantly higher than lab estimates. That occurred because electric motors were not strong enough to function independently, leading to engines burning gasoline for almost a third of the distance completed in EV mode.

Regulatory and Economic Implications

According to estimates, the underestimation of PHEV emissions enabled several large automaker companies to escape more than €5bn in penalties from 2021 and 2023, by artificially easing compliance with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs could pay approximately €500 extra per year in running costs than is assumed under laboratory tests.

“The strong claims that manufacturers often promote about their plug-in hybrid cars are clearly way off the truth,” commented a transport expert. “Buyers are being misled into believing that by buying a PHEV, they are helping the environment and cutting money. Actually, PHEVs are little improved than standard gas and diesel vehicles in terms of energy use, CO₂ production, and running expenses.”

Political Debate and Automotive Lobbying

Plug-in hybrid vehicles have recently been brought back into policy discussions as carmakers have pressed the EU to relax CO₂ targets. A proposed ban on sales of new combustion engine cars in 2035 has faced heavy pressure from the car industry and resistance from EU countries with significant automotive industries.

Several senior politicians have proposed plug-in hybrids as a potential “compromise” option to include in the legislation.

One external energy policy specialist, who was unaffiliated with the research, described the report a “highly valuable addition” after a long period in which parts of the automotive sector argued there was too little data to properly evaluate actual emissions.

“The results demonstrate, without question, that the gap in lab and actual PHEV energy use and CO₂ emissions is significantly larger than for gasoline or conventional cars,” they stated. “Any policy adjustments regarding PHEVs should be implemented with utmost caution and considering this data.”