EU data reveals a significant CO2 gap
Plug-in hybrids can be very efficient in everyday use if their batteries are charged regularly and they are consistently driven in electric mode. However, this appears to happen far less often than official fuel consumption figures assume.
An analysis of EU driving data shows that plug-in hybrids registered in 2024 averaged 145 g of CO2 per km in real-world use. By contrast, the official figure for these vehicles was just 24 g of CO2 per km. This means their actual emissions were around six times higher on average.
| Registration year | Official CO2 figure | Real-world CO2 figure | Difference |
|---|---|---|---|
| 2023 | 28 g/km | 138 g/km | around 4.9 times higher |
| 2024 | 24 g/km | 145 g/km | around 6.0 times higher |
The study is based on consumption data from around 220,000 vehicles, recorded using onboard fuel consumption meters. The opposing trends are striking: while the official figure fell by around 15% from 2023 to 2024, real-world emissions rose by approximately 5%.
Why plug-in hybrids look better on paper
Type approval calculations use what is known as a utility factor. This factor estimates the proportion of a plug-in hybrid’s mileage that is covered on electric power. The higher the assumed electric share, the lower the official CO2 figure.
If a vehicle is rarely charged in everyday use, the combustion engine does a much larger share of the work. It must also carry the additional weight of the battery and electric drivetrain. High assumed electric share → low test figure, infrequent charging → significantly higher real-world consumption.
A plug-in hybrid is not automatically a low-emission vehicle. What matters is how often it is charged and actually driven on electric power.
In 2024, the real-world tailpipe emissions of the plug-in hybrids studied were only 14% lower than those of conventional gasoline and diesel vehicles. The latter averaged 169 g of CO2 per km. These figures cover only emissions while driving, not a full life-cycle assessment.
EU plans to correct the calculation from 2027
In 2025, the EU began gradually adjusting the assumed share of electric driving to reflect real-world usage data. A further correction is planned for 2027. As a result, the official CO2 figures of many plug-in hybrids would rise even though the vehicles themselves would remain technically unchanged.
Parts of the automotive industry are calling for this next step to be scrapped. Their argument is that higher official emissions figures could make plug-in hybrids less attractive, undermine investment and hamper sales of an important transitional technology.
On the other hand, these figures influence not only purchasing decisions but also European fleet CO2 targets. Overly optimistic assumptions can provide manufacturers with greater relief on paper than is justified by the actual reduction in emissions. This is precisely why the methodology is so fiercely contested economically and politically.
Plug-in hybrids remain a growing market
In the first half of 2026, plug-in hybrids accounted for almost one in ten new passenger-car registrations across the EU. These models are also becoming more prominent again in Germany due to new offerings and intense pricing pressure, as demonstrated by the latest discounts on BYD plug-in hybrids.
At the same time, the technology continues to evolve. Larger batteries and faster charging can increase the proportion of driving done on electric power, as illustrated by concepts offering long electric ranges and short charging times, such as the BYD Ti 9. However, the potential of such vehicles can only be realized if suitable charging facilities are available and used regularly in everyday life.
What the stricter figures mean for the DACH region
Germany and Austria, as EU members, would be directly affected by the new calculation. Switzerland would be affected indirectly through changes to model availability, pricing and product planning because manufacturers generally develop their vehicles for the European market as a whole. Together, Germany, Austria and Switzerland are commonly referred to as the DACH region.
More realistic CO2 figures would not automatically reduce a plug-in hybrid’s fuel consumption. However, they would give buyers, fleet operators and lawmakers a more honest picture of the emissions that can be expected under average usage conditions.
Further political discussions about the planned correction have been announced for fall 2026. From an objective perspective, there are strong arguments for bringing official assumptions closer to real-world usage while not dismissing plug-in hybrids across the board. When charged regularly, they can still cover a large proportion of everyday journeys on electric power.
