The EU car industry wants plug-in hybrid vehicles to be considered carbon neutral, but data from thousands of vehicles shows that PHEVs emit just 19% less CO2 per km, on average, than petrol and diesel cars.
Carmakers are lobbying and asking EU lawmakers to treat hybrids as clean vehicles under a ‘technology-neutral’ approach to decarbonizing cars. But T&E analysis of emissions data from 127,000 PHEVs finds they emit far more than claimed, and the extra fuel consumed costs the average driver €500 a year.
PHEVs are supposed to reduce emissions and fuel consumption by switching between a battery that is recharged by plugging in and a petrol or diesel engine. But in the real world, CO2 emissions from plug-in hybrids are almost five times what official tests suggest. The real-world data differs significantly from the official ‘WLTP’ tests, where vehicles are driven in a way regulators consider normal.
In the real world, plug-in hybrids emit 135g of CO2 per km on average, according to T&E analysis of data gathered by the European Environment Agency (EEA) from fuel monitors on 127,000 vehicles registered in 2023. Petrol and diesel cars emit 166g of CO2/km on average.
PHEVS are more expensive than BEVs
Even when driven in electric mode, PHEV engines consume 3 liters of petrol per 100km, on average, the EEA data shows. As a result, they emit 68g of CO2/km in electric mode, 8.5 times as much as official tests claim. This is because the electric motors in PHEVs generally lack sufficient power for higher speeds or steep inclines, so the engine needs to kick in. On average, the engine supplies power during almost one-third of the distance driven in electric mode, according to the data.
PHEVs cost drivers €500 more a year than claimed to fuel and charge because of the hidden fuel consumption in both electric and engine modes, the report also finds. Not only are plug-in hybrids expensive to drive, but they are also more costly to buy than clean alternatives.
The average selling price of PHEVs in Germany, France, and the UK in 2025 is €55,700, according to Bloomberg Intelligence. This is €15,200 above the average cost of a battery-electric car.
Lucien Mathieu, cars director at T&E, commented: “Plug-in hybrids are one of the biggest cons in automotive history. They emit almost as much as petrol cars. Even in electric mode, they pollute eight times as much as official tests claim. Technology neutrality cannot mean ignoring the reality that, even after a decade, PHEVs have never delivered.”
More extended range is no solution
PHEV emissions are also increasing because of the trend towards longer electric ranges and larger batteries, which make the vehicles heavier and, therefore, burn more fuel in engine mode. These heavier vehicles also consume more energy than smaller cars when driven on the battery.
Plug-in hybrids with an electric range above 75 km actually emit more CO2 on average than those with a range of 45-75 km, the data shows.
Mercedes-Benz has the most significant gap between its official and real-world PHEV emissions, according to 2023 data, emitting 494% more on average. Its GLE-Class has the highest real-world emissions gap of cars sold that year, exceeding its official value by 611%. The other major European carmakers emitted around 300% more than their official CO2 ratings.
No softening of the ‘utility factors’
The European car industry wants to be allowed to sell PHEVs after the EU’s 2035 deadline for zero-emission cars. Carmakers are also demanding that the EU cancel the ‘utility factors’ it has set to correct the CO2 rating of plug-in hybrids.
The utility factors set for 2025 and 2027 gradually close the gap between official and real-world emissions, making carmakers’ EU CO2 targets more stringent and pushing manufacturers to sell more battery-electric cars. Canceling them would result in a severe decrease in new BEV market share, from 58% to 36%, a net 38% decline in BEV sales.
Lucien Mathieu concluded: “Weakening the rules for plug-in hybrids is like drilling a hole in the hull of Europe’s car CO₂ emissions law. Instead of steering the market toward affordable zero-emission cars, carmakers will flood it with expensive, polluting PHEVs. It also risks sinking the EV investment certainty the market desperately needs.”
