As governments and consumers alike push toward greener mobility, plug-in hybrid electric vehicles (PHEVs) have often been touted as a compromise between traditional combustion engines and full electrification. They promise the flexibility of a petrol or diesel engine for long trips combined with the environmental benefits of battery power for short drives. But a new analysis raises serious doubts about how much greener they really are.
What the Data Reveals
An investigation of almost 800,000 PHEVs registered in Europe between 2021 and 2023 reveals a surprising reality: in real-world driving, these vehicles emit nearly five times more CO₂ than official laboratory tests suggest. In fact, the analysis shows that these PHEVs produce only about 19 % less CO₂ than comparable petrol or diesel cars — far short of the 75 % reduction often claimed based on lab figures.
Why the Discrepancy?
The key issue lies with what’s called the “utility factor” — that is, how much of the total distance a PHEV actually drives on battery power versus the internal combustion engine. The official assumption places this at around 84 % in electric mode, but real-world data pins it at closer to 27 %.
Moreover, even during the periods the car is supposedly in electric mode, the internal combustion engine still kicks in — burning fossil fuels for almost a third of that “electric” distance in some instances. This undermines the core environmental argument of PHEVs.
The Consequences For Drivers and Policy
Beyond just the emissions figures, this gap has tangible implications.
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Many drivers are likely paying hundreds of euros more per year in running costs than they would expect, based on the optimistic lab figures
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Manufacturers using these optimistic figures may have avoided billions in fines under EU fleet-average CO₂ targets, which use the lab data as a benchmark.
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At a policy level, the findings raise questions: is the continued promotion of PHEVs as a “bridge” technology justified if their real-world benefits are minimal?
What’s Next for Mobility?
This isn’t necessarily the death-knell for PHEVs, but it does mean a more sober assessment is required:
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Buyers should consider how often they can realistically switch to electric mode, and whether their driving patterns align.
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Policymakers may need to re-think how they regulate and incentivise plug-in hybrids, especially if full EVs offer clearer environmental benefit.
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Manufacturers may face increasing pressure to improve the real-world performance of plug-in hybrids or pivot more directly to all-electric platforms.
Final Thoughts
The idea of plug-in hybrids still holds intuitive appeal: part-electric for short trips, petrol or diesel for longer ones. But as the data now shows, the ideal rarely matches the reality. If the bulk of driving isn’t actually done on battery power — or the combustion engine is still frequently engaged — the environmental benefits shrink considerably. For those serious about reducing emissions, fully electric vehicles may now stand out as a clearer path forward.
Reference: The Guardian The Guardian
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