Plug-in Hybrid Cars Emit Nearly as Much as Petrol Cars, Study Reveals

Plug-in hybrid electric vehicles release nearly 5x more planet-heating pollution than lab-reported figures indicate, as per a new report.

Widening Gap Between Lab and Actual Emissions

Data shows that PHEVs release only one-fifth lower CO₂ than traditional petrol and diesel cars, based on analysis carried out by a advocacy organization. This contrasts sharply with lab estimates, which suggested a three-quarters decrease in emissions.

Researchers examined information from onboard fuel consumption meters of eight hundred thousand vehicles registered in Europe between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official estimates, increased from 3.5 times in 2021.

“Actual CO2 output are increasing, while lab-reported figures are falling,” stated a senior researcher involved in the report. “This discrepancy is growing and creates a significant problem. Consequently, PHEVs pollute almost as much as gasoline vehicles.”

Primary Factors Behind the Emissions Gap

Researchers linked the majority of the gap to overestimates of the “electric driving share” – the ratio of kilometers travelled in battery power relative to total distance. The team determined that only 27% of travel was completed in electric mode, whereas lab assumptions suggested over four-fifths.

Even, when running in EV mode, emission amounts were significantly higher than official estimates. This occurred because electric motors were not strong enough to function independently, resulting to engines using gasoline for almost one-third of the travel covered in EV mode.

Policy and Economic Consequences

Based on calculations, the lowballing of PHEV emissions enabled four large carmaker companies to escape over €5bn in fines from 2021 and 2023, by artificially simplifying adherence with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs would spend about €500 more annually in operating costs than is assumed under laboratory tests.

“The bold statements that automakers often promote about their PHEV cars are clearly way off the mark,” stated a automotive expert. “Buyers are being duped into thinking that by buying a PHEV, they are helping the planet and cutting costs. Actually, PHEVs are little improved than regular petrol and diesel vehicles in terms of fuel use, CO₂ production, and running expenses.”

Political Debate and Automotive Lobbying

Hybrid cars have recently been drawn back into policy debates as carmakers have lobbied the European Union to weaken CO₂ targets. A proposed prohibition on sales of new combustion engine vehicles in 2035 has faced intense pressure from the car sector and opposition from EU countries with large automotive manufacturing.

Some senior officials have suggested plug-in hybrids as a possible “compromise” option to include in the legislation.

An independent energy economics specialist, who was unaffiliated with the research, described the report a “very useful contribution” after a long period in which segments of the car industry argued there was insufficient information to properly evaluate real-world emissions.

“These findings show, beyond any doubt, that the difference in lab and actual PHEV fuel consumption and CO₂ emissions is significantly greater than for gasoline or conventional cars,” they said. “All policy changes regarding PHEVs should be made with utmost caution and considering this evidence.”