Plug-in Hybrids Pollute Almost As Much As Petrol Cars, Report Finds
Summary
A new analysis by non-profit group Transport & Environment finds that plug-in hybrid electric vehicles (PHEVs) emit far more CO2 in the real world than official lab tests suggest. Using onboard fuel-consumption meters from around 800,000 European cars registered between 2021 and 2023, researchers say PHEVs delivered only a 19% reduction in CO2 compared with petrol/diesel cars — versus the 75% reduction implied by lab testing. Real-world emissions in 2023 were about 4.9 times higher than the standardised tests indicated (up from 3.5x in 2021).
The study highlights a big gap between test assumptions (drivers will mostly run on electricity) and actual behaviour and vehicle performance: many PHEV drivers rarely charge, some PHEV electric systems are too small for typical driving, and heavier combined systems reduce efficiency when running on petrol.
Key Points
- Transport & Environment analysed onboard fuel-meter data from ~800,000 European cars (2021–2023).
- PHEVs cut CO2 by about 19% in real-world use versus petrol/diesel cars, not the 75% suggested by lab tests.
- Real-world CO2 from PHEVs in 2023 was 4.9 times greater than standardised laboratory test values (a rise from 3.5x in 2021).
- The discrepancy is driven by driver behaviour (many owners don’t plug in), limited EV range on some models, and how PHEVs operate at higher speeds.
- Findings have policy implications: manufacturers lobby to count PHEVs towards fleet targets and to influence the EU debate on post-2035 ICE rules and subsidies.
Content summary
The report compares lab-derived emissions figures with real-world data gathered from large-scale onboard meters. It shows that standardised test cycles markedly overstate the electric-mode use of PHEVs — regulators assume a high share of electric driving that simply doesn’t match what drivers actually do. The study also notes that some PHEV designs switch to the petrol engine at highway speeds or under higher load, reducing expected benefits.
Commentary around the report emphasises mixed individual outcomes: conscientious owners can get near-BEV performance from some PHEVs, but many corporate or unincentivised drivers seldom charge, so fleet averages look poor. Critics argue the vehicle class can be both a legitimate transitional solution and a form of greenwashing depending on design, incentives and charging access.
Context and relevance
This matters because Europe is amid a policy debate on how to meet fleet-emission targets and what role hybrids should play after 2035. If laboratory tests continue to guide regulation and subsidies, they risk rewarding vehicles that underdeliver in the real world. The report strengthens calls for test-procedure reform, tighter rules on incentives, and better alignment of tax breaks with real-world performance and charging availability.
For buyers, fleet managers and policymakers the takeaway is clear: PHEVs are not a guaranteed emissions win. Benefits depend heavily on charging behaviour, vehicle design (actual EV range and how the ICE is used) and supporting infrastructure.
Why should I read this?
Short and blunt: if you’re thinking of buying a PHEV, running a fleet, or following EU clean-car rules — read this. It’s a reality check on the “plug-in” promise: some PHEVs are legit, many aren’t delivering the advertised CO2 savings once you factor in how people actually use them. Saves you from being misled by lab numbers and marketing.
Author style
Punchy: this isn’t academic hair-splitting — it’s a policy and consumer wake-up call. If regulators shift based on this, subsidies and fleet obligations could change quickly, so the details matter. Read the full report if you care about emissions accuracy, incentives or buying choices.