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PHEVs emit nearly five times more planet-heating pollution than lab-reported data show, as per a recent analysis.

Widening Gap Between Lab and Real-World Emissions

Statistics reveals that PHEVs release only 19% lower CO₂ than traditional petrol and diesel cars, according to analysis carried out by a advocacy group. This differs sharply with laboratory estimates, which suggested a three-quarters decrease in pollution.

Researchers studied data from onboard energy use meters of 800,000 cars sold in Europe from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, increased from 3.5 times in 2021.

“Real-world emissions are increasing, while official figures are decreasing,” said a senior analyst participating in the report. “This discrepancy is widening and creates a serious issue. Consequently, PHEVs emit almost as heavily as gasoline cars.”

Key Reasons Behind the Discrepancy

Analysts attributed the majority of the gap to overestimates of the “utility factor” – the percentage of miles travelled in battery mode compared to overall distance. They determined that only a quarter of driving was completed in electric mode, while official estimates suggested over four-fifths.

Even, when operating in EV mode, emission amounts were well above official estimates. This happened because EV motors were not strong enough to operate independently, resulting to engines burning gasoline for almost one-third of the distance covered in EV mode.

Policy and Economic Consequences

According to calculations, the lowballing of PHEV emissions enabled several large carmaker companies to escape over €5bn in fines from 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ targets.

Furthermore, drivers of PHEVs could pay about €500 more per year in operating costs than would be estimated under laboratory conditions.

“The strong claims that manufacturers often promote about their PHEV cars are obviously way off the truth,” commented a transport analyst. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the environment and saving costs. Actually, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of energy consumption, CO₂ production, and running expenses.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid cars have recently been drawn back into policy debates as automakers have pressed the European Union to weaken CO₂ targets. A planned prohibition on new internal combustion vehicles in 2035 has faced intense pressure from the car sector and opposition from EU countries with large car industries.

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

One external energy economics specialist, who was not involved with the study, called the analysis a “very useful addition” after years in which parts of the automotive sector claimed there was insufficient data to accurately assess actual CO2 output.

“The results show, without question, that the difference in official and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or conventional cars,” they said. “Any policy changes regarding PHEVs should be implemented with utmost care and considering this evidence.”