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Plug-in hybrid electric vehicles emit almost five times more global warming emissions than lab-reported data show, according to a recent analysis.

Widening Gap In Lab and Actual CO2 Output

Statistics shows that PHEVs emit only one-fifth less CO₂ than conventional gas and diesel cars, according to analysis carried out by a non-profit group. That contrasts significantly with lab estimates, which suggested a 75% reduction in emissions.

Researchers studied data from onboard fuel consumption monitors of eight hundred thousand cars sold in Europe from 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than lab estimates, up from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported figures are decreasing,” said a lead analyst participating in the report. “This discrepancy is widening and poses a serious issue. Consequently, PHEVs pollute almost as heavily as gasoline cars.”

Key Reasons Driving the Discrepancy

Analysts attributed most of the gap to inflated estimates of the “utility factor” – the ratio of kilometers driven in electric power compared to total distance. They determined that just 27% of driving was done in EV mode, whereas official assumptions assumed over four-fifths.

Additionally, when running in electric mode, pollution amounts were significantly higher than lab estimates. That occurred because EV motors were insufficiently powerful enough to function independently, leading to engines burning fossil fuels for nearly a third of the travel completed in electric mode.

Policy and Economic Consequences

According to calculations, the lowballing of PHEV CO2 output enabled four major carmaker groups to avoid more than €5bn in penalties between 2021 and 2023, by falsely easing compliance with EU fleet-average CO₂ targets.

Additionally, owners of PHEVs would spend about €500 extra per year in operating costs than would be assumed under laboratory tests.

“The strong claims that manufacturers like to make about their plug-in hybrid cars are obviously far from the truth,” commented a transport expert. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and cutting money. Actually, PHEVs are only slightly improved than standard petrol and diesel vehicles in terms of energy use, CO₂ emissions, and operating costs.”

Policy Debate and Automotive Pressure

Hybrid cars have recently been drawn again into policy debates as carmakers have lobbied the EU to relax CO₂ standards. A proposed ban on new combustion engine vehicles in 2035 has faced heavy pressure from the automotive sector and opposition from member states with significant car industries.

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

An independent energy economics expert, who was not involved with the study, called the analysis a “very useful contribution” after a long period in which parts of the car industry argued there was insufficient data to properly evaluate actual emissions.

“These findings show, without question, that the difference between official and actual PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or conventional vehicles,” the expert stated. “All regulatory adjustments regarding PHEVs should be implemented with utmost care and considering this data.”