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PHEVs release nearly five times greater global warming pollution than lab-reported figures show, according to a new report.

Growing Gap In Lab and Actual CO2 Output

Data reveals that PHEVs emit just 19% less CO₂ than conventional gas and diesel cars, based on analysis conducted by a advocacy organization. This contrasts sharply with laboratory tests, which assumed a three-quarters decrease in emissions.

Researchers examined data from onboard energy use meters of eight hundred thousand cars sold in Europe between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab estimates, increased from 3.5 times in 2021.

“Real-world emissions are rising, while lab-reported emissions are decreasing,” said a lead researcher involved in the study. “That gap is growing and creates a significant problem. Consequently, PHEVs pollute almost as heavily as gasoline vehicles.”

Key Reasons Driving the Discrepancy

Analysts attributed most of the difference to overestimates of the “electric driving share” – the ratio of miles driven in battery mode relative to total distance. They found that just a quarter of driving was completed in electric mode, while official assumptions assumed over four-fifths.

Additionally, when operating in electric mode, pollution levels were well above lab estimates. This happened because electric motors were not strong sufficient to operate independently, leading to combustion motors using gasoline for almost one-third of the distance completed in EV mode.

Policy and Financial Consequences

According to calculations, the lowballing of PHEV CO2 output enabled four large carmaker companies to escape over €5bn in fines from 2021 and 2023, by artificially easing compliance with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs could spend approximately €500 more annually in running expenses than is assumed under laboratory conditions.

“The strong statements that manufacturers often promote about their plug-in hybrid vehicles are clearly far from the mark,” commented a transport expert. “Buyers are being duped into thinking that by buying a PHEV, they are helping the environment and saving money. Actually, PHEVs are only slightly better than regular gas and diesel cars in terms of energy consumption, CO₂ production, and operating costs.”

Political Discussion and Automotive Pressure

Hybrid cars have lately been brought back into political debates as automakers have lobbied the EU to weaken CO₂ targets. A planned prohibition on new combustion engine cars in 2035 has faced heavy pressure from the automotive sector and opposition from member states with significant automotive manufacturing.

Some high-level politicians have proposed PHEVs as a possible “compromise” solution to introduce in the legislation.

An external energy policy expert, who was not involved with the study, described the report a “very useful addition” after a long period 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 lab and actual PHEV fuel consumption and CO₂ output is much, much greater than for gasoline or diesel vehicles,” they stated. “All regulatory changes regarding PHEVs should be implemented with utmost caution and in the light of this data.”