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Plug-in hybrid electric vehicles produce nearly five times more global warming emissions than official figures indicate, according to a recent analysis.

Widening Discrepancy In Lab and Actual CO2 Output

Statistics reveals that PHEVs emit just 19% less CO₂ than conventional petrol and diesel cars, based on research carried out by a advocacy group. This differs sharply with lab estimates, which assumed a 75% decrease in emissions.

Analysts examined information from onboard fuel consumption meters of eight hundred thousand vehicles sold in the EU from 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official estimates, up from 3.5 times in 2021.

“Actual CO2 output are rising, while official emissions are decreasing,” stated a lead researcher participating in the report. “That discrepancy is widening and creates a significant issue. As a result, PHEVs emit almost as much as petrol cars.”

Primary Factors Driving the Emissions Gap

Researchers attributed the majority of the gap to overestimates of the “utility factor” – the ratio of miles travelled in electric mode relative to total distance. The team determined that just 27% of driving was completed in EV mode, whereas official assumptions suggested over four-fifths.

Additionally, when operating in EV mode, emission amounts were significantly higher than official estimates. That occurred because electric motors were not strong enough to function independently, leading to engines using fossil fuels for almost a third of the distance covered in electric mode.

Policy and Financial Implications

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

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

“The bold statements that manufacturers like to make about their PHEV vehicles are clearly way off the truth,” commented a automotive expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the planet and cutting money. In reality, PHEVs are only slightly better than standard gas and diesel cars in terms of fuel consumption, CO₂ emissions, and running costs.”

Policy Debate and Automotive Pressure

Plug-in hybrid cars have recently been drawn back into political debates as automakers have lobbied the EU to weaken CO₂ standards. A proposed prohibition on new internal combustion vehicles in 2035 has faced heavy pressure from the car industry and resistance from EU countries with large automotive manufacturing.

Some high-level politicians have proposed PHEVs as a potential “flexibility” option to include in the legislation.

One external energy economics expert, who was not involved with the study, described the report a “highly valuable addition” after a long period in which parts of the automotive industry claimed there was too little data to properly evaluate real-world emissions.

“The results demonstrate, without question, that the gap in lab and actual PHEV fuel consumption and CO₂ emissions is significantly greater than for petrol or conventional vehicles,” they said. “Any regulatory changes regarding PHEVs should be implemented with extreme caution and considering this data.”