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PHEVs emit nearly 5x more planet-heating pollution than official figures show, according to a new report.

Growing Gap In Lab and Real-World CO2 Output

Data shows that PHEVs emit just 19% less CO₂ than traditional petrol and diesel cars, according to analysis conducted by a non-profit group. That differs significantly with laboratory estimates, which suggested a 75% reduction in emissions.

Analysts examined data from in-vehicle energy use monitors of eight hundred thousand vehicles sold in Europe between 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, increased from 3.5 times in 2021.

“Actual emissions are rising, while official figures are decreasing,” said a senior analyst participating in the report. “This gap is widening and poses a significant issue. Consequently, PHEVs emit nearly as heavily as petrol cars.”

Primary Reasons Driving the Emissions Gap

Analysts attributed the majority of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers driven in battery mode compared to overall distance. The team determined that only 27% of driving was done in EV mode, whereas lab assumptions assumed 84%.

Even, when operating in EV mode, pollution levels were significantly higher than lab estimates. This happened because electric motors were not strong sufficient to function alone, leading to combustion motors using gasoline for almost one-third of the distance completed in EV mode.

Policy and Economic Implications

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

Furthermore, owners of PHEVs could pay approximately €500 extra per year in running expenses than is estimated under laboratory conditions.

“The strong claims that manufacturers like to make about their PHEV vehicles are clearly way off the truth,” commented a automotive expert. “Buyers are being misled into thinking that by buying a PHEV, they are helping the environment and saving costs. In reality, PHEVs are little improved than regular gas and diesel cars in terms of fuel use, CO₂ emissions, and running expenses.”

Policy Debate and Industry Pressure

Plug-in hybrid cars have lately been drawn back into policy discussions as carmakers have lobbied the European Union to relax CO₂ targets. A planned prohibition on new combustion engine vehicles in 2035 has faced heavy lobbying from the automotive industry and resistance from EU countries with significant car industries.

Several senior officials have proposed PHEVs as a potential “flexibility” option to introduce in the regulation.

An external energy economics specialist, who was unaffiliated with the study, described the report a “very useful addition” after a long period in which segments of the car industry argued there was too little data to properly evaluate actual emissions.

“These findings demonstrate, without question, that the difference between lab and actual PHEV fuel consumption and CO₂ emissions is much, much larger than for gasoline or diesel vehicles,” they said. “All policy adjustments concerning PHEVs should be implemented with extreme care and considering that data.”