A new study by the French Institut Mobilités en Transition (IMT) casts fresh doubt on the future of plug-in hybrid vehicles (PHEVs), arguing that prolonging their sale in Europe beyond 2035 would harm both household budgets and the continent’s climate ambitions.
The study finds that for buyers of new vehicles, plug-in hybrids cost about 7% more to operate over their lifetimes than comparable battery-electric vehicles (BEVs). For used-car buyers—the majority of low- and middle-income households—the gap widens to 18% on average and nearly 30% in some usage profiles.
A crucial moment for Europe
The IMT is an independent think-tank dedicated to analysing and promoting the transition of the mobility and transport sector. It was incubated for 2 years at the Institut du Développement Durable et des Relations Internationales (IDDRI) and then launched as a separate entity in 2023.
The findings come at a crucial moment: the European Commission is reviewing whether to soften the planned phase-out of combustion-engine and hybrid cars, set to take effect in 2035.
Researchers warn that the burden would fall disproportionately on modest households, who tend to purchase older, second-hand vehicles, for which maintenance costs are most critical.
The IMT study shows that the real cost gap between plug-in hybrids and fully electric cars grows sharply once vehicles leave the showroom.
For new-car buyers, PHEVs end up about 7% more expensive to run over their lifetimes because they carry two powertrains—a combustion engine and an electric system—making them heavier, more complex, and costlier to maintain.
Their official fuel figures are also misleading in real-world use: many drivers start their journeys with partially charged batteries, meaning the petrol engine engages far more often than test cycles assume. Even when driven in electric mode, the added weight of the combustion system makes them less efficient than a dedicated battery-electric car.
Disparity is more severe in second-hand market
But the disparity becomes far more severe in the second-hand market, where most low- and middle-income households make their purchases. As PHEVs age, their smaller batteries tend to degrade more quickly, reducing electric range and pushing drivers to rely increasingly on petrol.
Maintenance costs also rise sharply once warranties expire, since owners must shoulder the risks of both an ageing combustion engine and an ageing electric drivetrain.
And because many used-car buyers lack easy access to home or workplace charging, the electric side of the vehicle is often under-utilised, further inflating fuel bills.
Combined with faster depreciation and growing uncertainty around future regulations, these factors push operating costs to 18 percent above those of a comparable BEV on average—and close to 30 percent in some usage patterns.
Transitional technology?
On paper, and by several car manufacturers advocating a revision of the European ICE ban of 2035, plug-in hybrids are often presented as a transitional technology that offers the “best of both worlds.” In practice, the study suggests the opposite.
Across the full lifecycle—from manufacturing to use to end-of-life—PHEVs emit significantly more greenhouse gases than fully electric cars. While they use smaller batteries and therefore require fewer raw materials, their repeated reliance on combustion engines during real-world driving erodes the climate benefits promised in laboratory tests.
Depending on the segment and usage patterns, the study estimates that PHEVs can emit 70% to more than 100% more greenhouse gases than equivalent BEVs.
The report echoes previous findings that many plug-in hybrid drivers recharge less frequently than assumed, relying far more on petrol than official test cycles suggest.
Making charging mandatory?
The debate around plug-in hybrids has intensified in Europe after the German automotive industry association (VDA) recently floated the idea of making regular charging mandatory for PHEV drivers.
VDA President Hildegard Müller suggested how “regular charging could become mandatory” in PHEV design. Within a certain driving distance, the battery must be charged; if not, the vehicle’s performance could be reduced, for instance, the combustion engine’s power might be throttled.
The proposal, meant to preserve the technology’s green credentials, has triggered mixed reactions: industry outlets call it a pragmatic fix for poor real-world performance. At the same time, environmental groups such as Transport & Environment condemn it as an attempt to prolong a technology that fails to deliver genuine emissions cuts.
Critics also warn that a “charging obligation” raises practical and legal questions, from enforcement to infrastructure availability, and could divert attention from the EU’s broader push toward fully electric vehicles.
Maintaining the ICE ban
While several automakers have recently lobbied Brussels to keep plug-in hybrids alive beyond 2035, IMT’s conclusion is unequivocal: the EU should maintain the ban on new partially combustion-powered vehicles.
Beyond environmental and consumer impacts, the study warns of broader economic risks. Allowing plug-in hybrids to continue past 2035 could weaken Europe’s push to build a competitive battery industry and keep the EU dependent on imported fossil fuels.
In scenarios modelled by IMT, vehicles that still rely partly on combustion engines worsen Europe’s trade balance, due both to fuel imports and reduced incentives for domestic production of small, affordable electric vehicles.
