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Plug-in hybrid cars release almost 5x more planet-heating emissions than lab-reported data show, as per a recent report.

Widening Gap Between Lab and Real-World CO2 Output

Data reveals that PHEVs release just one-fifth less CO₂ than traditional gas and diesel vehicles, according to analysis carried out by a advocacy organization. This differs sharply with lab tests, which suggested a three-quarters reduction in pollution.

Analysts studied information from onboard fuel consumption monitors of 800,000 vehicles sold in Europe from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official estimates, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official figures are falling,” said a senior researcher involved in the study. “This discrepancy is widening and poses a significant issue. As a result, PHEVs pollute almost as heavily as gasoline vehicles.”

Key Reasons Driving the Emissions Gap

Analysts attributed most of the gap to inflated estimates of the “utility factor” – the ratio of kilometers travelled in electric mode relative to overall distance. The team determined that only 27% of driving was done in electric mode, whereas lab assumptions assumed 84%.

Additionally, when running in electric mode, emission amounts were well above lab projections. This happened because EV motors were insufficiently powerful sufficient to operate independently, resulting to combustion motors using gasoline for almost one-third of the distance covered in electric mode.

Policy and Financial Implications

Based on estimates, the underestimation of PHEV emissions enabled several major carmaker groups to escape over €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ standards.

Additionally, owners of PHEVs would pay approximately €500 more annually in running costs than is estimated under lab tests.

“The bold claims that manufacturers often promote about their PHEV vehicles are clearly far from the mark,” stated a automotive expert. “Buyers are being misled into thinking that by buying a PHEV, they are benefiting the environment and cutting costs. Actually, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of energy use, CO₂ emissions, and operating costs.”

Policy Debate and Automotive Lobbying

Hybrid cars have lately been brought again into political debates as automakers have pressed the European Union to relax CO₂ targets. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced intense pressure from the car sector and opposition from EU countries with significant automotive manufacturing.

Some senior officials have suggested PHEVs as a possible “flexibility” solution to include in the regulation.

An independent energy policy expert, who was not involved with the research, called the report a “highly valuable addition” after a long period in which segments of the car sector claimed there was too little data to properly evaluate real-world emissions.

“These findings show, beyond any doubt, that the gap between lab and actual PHEV fuel consumption and CO₂ output is significantly greater than for petrol or conventional cars,” they stated. “All policy changes concerning PHEVs should be implemented with utmost care and in the light of this data.”