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PHEVs release almost five times greater global warming emissions than lab-reported data indicate, as per a new report.

Widening Gap In Lab and Actual CO2 Output

Data shows that PHEVs emit just one-fifth less CO₂ than traditional gas and diesel cars, according to analysis conducted by a advocacy organization. This differs significantly with laboratory tests, which assumed a 75% reduction in emissions.

Analysts examined data from onboard fuel consumption meters of 800,000 cars sold in the EU between 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than official estimates, increased from 3.5 times in 2021.

“Real-world CO2 output are increasing, while lab-reported figures are decreasing,” stated a lead analyst involved in the study. “This gap is growing and poses a serious problem. Consequently, PHEVs emit almost as heavily as petrol cars.”

Key Factors Driving the Emissions Gap

Researchers attributed the majority of the gap to overestimates of the “electric driving share” – the percentage of kilometers driven in electric mode relative to overall mileage. They found that only a quarter of driving was completed in EV mode, whereas lab estimates assumed over four-fifths.

Additionally, when running in EV mode, pollution amounts were significantly higher than lab projections. This happened because electric motors were insufficiently powerful enough to function alone, resulting to engines using gasoline for almost a third of the distance completed in electric mode.

Regulatory and Economic Implications

Based on estimates, the underestimation of PHEV emissions allowed several major carmaker groups to avoid over €5bn in fines from 2021 and 2023, by artificially simplifying adherence with EU average fleet CO₂ targets.

Furthermore, drivers of PHEVs could spend about €500 extra annually in operating costs than is assumed under laboratory tests.

“The bold statements that automakers like to make about their PHEV cars are obviously way off the truth,” stated a transport expert. “Buyers are being misled into believing that by purchasing a PHEV, they are helping the planet and cutting costs. Actually, PHEVs are only slightly better than standard petrol and diesel cars in terms of fuel consumption, CO₂ production, and operating expenses.”

Political Discussion and Industry Lobbying

Plug-in hybrid vehicles have lately been brought back into policy discussions as carmakers have lobbied the EU to relax CO₂ standards. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the car industry and opposition from member states with significant automotive industries.

Some high-level politicians have proposed plug-in hybrids as a possible “flexibility” option to include in the legislation.

An independent energy policy expert, who was unaffiliated with the study, described the report a “very useful addition” after years in which segments of the car industry claimed there was insufficient data to accurately assess actual CO2 output.

“These findings demonstrate, beyond any doubt, that the difference between official and actual PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or diesel vehicles,” they stated. “Any regulatory adjustments concerning PHEVs should be implemented with extreme caution and in the light of this evidence.”