🔗 Share this article

Plug-in hybrid cars emit nearly 5x greater planet-heating pollution than lab-reported data indicate, according to a new report.

Growing Discrepancy In Lab and Real-World CO2 Output

Data reveals that PHEVs emit just 19% less CO₂ than traditional gas and diesel cars, based on research conducted by a advocacy organization. That contrasts sharply with laboratory estimates, which assumed a three-quarters decrease in pollution.

Researchers studied data from onboard energy use meters of 800,000 cars registered in Europe from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than official estimates, increased from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported emissions are decreasing,” stated a senior researcher involved in the report. “This gap is growing and creates a significant issue. Consequently, PHEVs emit nearly as heavily as petrol cars.”

Primary Factors Driving the Emissions Gap

Analysts linked the majority of the difference to inflated estimates of the “utility factor” – the ratio of miles travelled in battery power compared to total mileage. The team determined that just a quarter of driving was completed in electric mode, while lab estimates assumed 84%.

Additionally, when running in electric mode, pollution levels were well above lab estimates. This happened because EV motors were insufficiently powerful enough to operate alone, leading to engines using gasoline for nearly a third of the distance covered in EV mode.

Policy and Financial Implications

Based on estimates, the lowballing of PHEV emissions allowed several major carmaker groups to escape more than €5bn in penalties between 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ targets.

Additionally, owners of PHEVs could spend about €500 more per year in operating costs than is assumed under laboratory conditions.

“The strong claims that automakers often promote about their plug-in hybrid cars are obviously far from the mark,” stated a automotive expert. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of energy consumption, CO₂ emissions, and running expenses.”

Policy Discussion and Industry Pressure

Plug-in hybrid vehicles have lately been drawn again into political debates as automakers have pressed the European Union to weaken CO₂ standards. A planned prohibition on new combustion engine cars in 2035 has faced heavy pressure from the automotive sector and resistance from EU countries with large car manufacturing.

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

One independent energy policy expert, who was unaffiliated with the study, described the report a “highly valuable contribution” after a long period in which segments of the car industry argued there was too little information to accurately assess real-world emissions.

“The results show, beyond any doubt, that the difference between lab and actual PHEV energy use and CO₂ output is significantly larger than for petrol or conventional cars,” they stated. “Any regulatory changes concerning PHEVs should be made with extreme care and considering that data.”