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Plug-in hybrid cars emit almost five times greater planet-heating emissions than lab-reported figures show, according to a recent analysis.

Growing Gap In Lab and Real-World CO2 Output

Statistics shows that PHEVs emit just 19% lower CO₂ than traditional petrol and diesel cars, according to research carried out by a advocacy group. That contrasts significantly with laboratory tests, which assumed a 75% reduction in emissions.

Analysts examined information from onboard energy use meters of 800,000 cars sold in Europe between 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while lab-reported figures are falling,” said a lead researcher participating in the study. “This discrepancy is widening and poses a significant problem. Consequently, PHEVs pollute almost as heavily as petrol cars.”

Key Reasons Behind the Discrepancy

Researchers attributed the majority of the difference to inflated estimates of the “electric driving share” – the percentage of kilometers driven in electric mode relative to overall mileage. They found that just a quarter of driving was completed in electric mode, while lab estimates suggested over four-fifths.

Additionally, when operating in electric mode, pollution amounts were significantly higher than official projections. This occurred because electric motors were not strong sufficient to function independently, resulting to engines burning fossil fuels for nearly a third of the distance completed in electric mode.

Regulatory and Financial Consequences

According to calculations, the lowballing of PHEV emissions allowed four major automaker companies to escape over €5bn in fines between 2021 and 2023, by artificially simplifying compliance with EU average fleet CO₂ targets.

Additionally, drivers of PHEVs could pay about €500 extra per year in operating costs than is assumed under laboratory tests.

“The bold claims that manufacturers often promote about their PHEV vehicles are clearly way off the truth,” stated a automotive expert. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the planet and cutting money. In reality, PHEVs are little improved than standard gas and diesel cars in terms of fuel use, CO₂ production, and operating expenses.”

Policy Discussion and Automotive Lobbying

Hybrid vehicles have recently been drawn back into political debates as automakers have pressed the European Union to relax CO₂ targets. A proposed prohibition on new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive sector and opposition from EU countries with significant car manufacturing.

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

One independent energy economics expert, who was not involved with the research, described the report a “very useful contribution” after a long period in which parts of the car sector claimed there was insufficient information to properly evaluate real-world CO2 output.

“The results demonstrate, beyond any doubt, that the difference between lab and actual PHEV fuel consumption and CO₂ output is significantly greater than for petrol or diesel vehicles,” they stated. “All policy adjustments regarding PHEVs should be implemented with extreme care and in the light of this data.”