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PHEVs emit nearly five times greater planet-heating pollution than lab-reported figures indicate, according to a recent analysis.

Widening Gap Between Lab and Actual Emissions

Statistics reveals that PHEVs release just 19% lower CO₂ than conventional petrol and diesel vehicles, according to research conducted by a advocacy group. This contrasts significantly with laboratory estimates, which assumed a 75% reduction in emissions.

Analysts examined data from onboard energy use monitors of 800,000 cars sold in Europe between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, up from three and a half times in 2021.

“Real-world CO2 output are rising, while official emissions are decreasing,” said a lead researcher involved in the study. “That discrepancy is widening and poses a serious problem. As a result, PHEVs emit almost as heavily as gasoline cars.”

Key Reasons Driving the Discrepancy

Researchers attributed the majority of the difference to inflated estimates of the “electric driving share” – the percentage of miles travelled in electric mode compared to overall mileage. The team determined that just a quarter of driving was done in electric mode, whereas lab estimates suggested over four-fifths.

Additionally, when running in electric mode, pollution levels were well above lab estimates. This occurred because electric motors were insufficiently powerful sufficient to operate alone, resulting to combustion motors burning gasoline for almost a third of the travel completed in electric mode.

Policy and Financial Implications

According to estimates, the lowballing of PHEV emissions enabled four major automaker companies to escape over €5bn in penalties from 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ targets.

Furthermore, owners of PHEVs would pay approximately €500 more annually in operating costs than is estimated under laboratory conditions.

“The strong statements that automakers often promote about their PHEV vehicles are clearly far from the mark,” commented a automotive expert. “Consumers are being duped into believing that by buying a PHEV, they are helping the environment and cutting money. Actually, PHEVs are little better than standard gas and diesel cars in terms of fuel use, CO₂ production, and running expenses.”

Political Debate and Industry Lobbying

Plug-in hybrid vehicles have recently been brought again into political debates as carmakers have pressed the European Union to relax CO₂ targets. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the automotive industry and resistance from member states with large automotive industries.

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

An independent energy economics expert, who was not involved with the study, called the analysis a “highly valuable contribution” after a long period in which parts of the automotive sector claimed there was too little information to properly evaluate real-world CO2 output.

“These findings demonstrate, beyond any doubt, that the difference between lab and real-world PHEV fuel consumption and CO₂ output is much, much greater than for gasoline or conventional cars,” they stated. “All policy changes concerning PHEVs should be implemented with extreme caution and considering this data.”