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PHEVs release almost 5x more global warming pollution than official data indicate, according to a new analysis.

Widening Gap In Lab and Real-World Emissions

Statistics reveals that PHEVs emit just one-fifth lower CO₂ than conventional petrol and diesel vehicles, according to analysis conducted by a non-profit group. That differs sharply with laboratory tests, which suggested a 75% decrease in pollution.

Researchers studied data from in-vehicle energy use meters of 800,000 vehicles sold in the EU between 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab estimates, up from 3.5 times in 2021.

“Actual emissions are rising, while official figures are falling,” stated a lead researcher participating in the study. “This discrepancy is growing and poses a serious problem. Consequently, PHEVs pollute almost as much as petrol vehicles.”

Primary Reasons Driving the Emissions Gap

Analysts attributed most of the gap to overestimates of the “electric driving share” – the percentage of kilometers driven in battery mode relative to overall distance. They found that only 27% of travel was done in EV mode, while lab estimates assumed 84%.

Even, when operating in EV mode, pollution amounts were well above official projections. That happened because EV motors were not strong sufficient to operate alone, resulting to engines using gasoline for nearly a third of the distance completed in electric mode.

Policy and Financial Consequences

According to estimates, the lowballing of PHEV CO2 output enabled four large carmaker companies to avoid over €5bn in penalties between 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ targets.

Additionally, drivers of PHEVs could pay approximately €500 more annually in operating costs than is estimated under laboratory tests.

“The strong statements that automakers often promote about their PHEV cars are clearly way off the truth,” commented a automotive expert. “Buyers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and cutting costs. Actually, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of energy use, CO₂ production, and operating costs.”

Policy Discussion and Industry Pressure

Hybrid cars have lately been brought back into political discussions as carmakers have pressed the European Union to weaken CO₂ targets. A planned ban on new combustion engine vehicles in 2035 has faced heavy lobbying from the automotive sector and opposition from member states with large car manufacturing.

Some senior politicians have suggested PHEVs as a possible “flexibility” option to include in the regulation.

One independent energy economics specialist, who was not involved with the research, described the analysis a “highly valuable addition” after a long period in which segments of the automotive sector claimed there was too little information to properly evaluate actual emissions.

“The results demonstrate, without question, that the gap between official and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or conventional vehicles,” the expert stated. “Any regulatory adjustments concerning PHEVs should be implemented with utmost care and in the light of this data.”