Plug-in hybrids have long been perceived as a convenient intermediate step towards full vehicle electrification. The idea seems logical: a relatively small battery allows for daily electric-powered trips, while an internal combustion engine remains for long journeys.
It is this combination of two powerplants that has given PHEVs a reputation for low emissions. Government support programs relied on this reputation: manufacturers and buyers received tax incentives, and fleets gained advantages in meeting environmental requirements.
However, real-world operating conditions are beginning to cast doubt on this picture. A comprehensive ICCT study indicates that actual CO₂ emissions from plug-in hybrids can significantly exceed figures obtained during laboratory tests. Even modern PHEVs with larger batteries and greater electric range do not always demonstrate the expected emission reductions if the owner does not regularly plug the car in for charging.
Laboratory assumes one thing, driver does another
At the heart of the problem is the so-called utility factor – a mathematical coefficient used by regulators to calculate the proportion of a vehicle's mileage in all-electric mode. It is this indicator that allows assessing what part of the journey a PHEV supposedly covers without starting the internal combustion engine.
The problem is that current calculations may overestimate the actual frequency of vehicle charging. If the methodology assumes that the owner regularly plugs the car into the grid, official emission figures look significantly more attractive. In real life, driver behavior can be completely different.
The ICCT study points to a significant gap between assumed charging habits and actual operation. As a result, official emission figures do not always reflect how vehicles are used on the roads.
A large battery doesn't help if it's not charged
PHEVs have one feature that particularly strongly affects real fuel consumption. If the owner does not charge the car regularly, the internal combustion engine is forced to constantly carry the additional weight of the battery. In some cases, this involves hundreds of kilograms, which in such a scenario are practically not used for their intended purpose.
As a result, fuel consumption turns out to be noticeably higher than declared by the manufacturer. Data from private and corporate fleets show that the actual fuel consumption of plug-in hybrids is often two to four times higher than official figures.
A paradoxical situation arises: the car was created to cover a significant part of daily trips on electricity, but without regular charging, its advantages sharply diminish.
The main problem may be in the methodology itself
Researchers believe that the situation can be changed primarily at the level of regulations. It is proposed to adjust the utility factor so that it reflects real data on driver behavior, rather than assuming an ideal operating scenario.
This approach should make the assessment of environmental friendliness more objective. Currently, manufacturers can receive environmental bonuses and corresponding regulatory advantages for cars that, in real-world operation, can show significantly worse results than during certification tests.
According to researchers, revising the methodology is also necessary to maintain technological neutrality in the automotive market. Different types of powertrains should be evaluated based on indicators that are as close as possible to their real-world behavior on the roads.
Does this mean PHEVs should be banned?
Not necessarily. The concept of a plug-in hybrid itself remains quite rational. Such a car can combine electric mode for daily trips and an internal combustion engine for long journeys.
The problem arises when a PHEV is automatically considered an eco-friendly alternative to an electric vehicle, regardless of how its owner uses it. The environmental effect directly depends on the driver's habits.
If the battery is regularly charged and the car actually uses electric traction where it is designed to, the meaning of such a powertrain is preserved. If charging is practically not used, the internal combustion engine is forced to constantly carry a heavy battery, and real fuel consumption becomes significantly higher than declared.
PHEVs cannot be automatically considered electric vehicles
A plug-in hybrid occupies an intermediate position between a traditional internal combustion engine car and a full-fledged electric vehicle. That is why evaluating it solely by laboratory indicators is not enough. It is necessary to take into account the real mode of use.
This is especially evident in modern models with large batteries. Theoretically, they are capable of providing significant electric range, but this potential only makes sense when the owner actually uses the ability to charge the car.
Even modern and technically complex PHEVs should therefore not be automatically considered environmentally efficient. Their result depends on two factors at once – the car's capabilities and the behavior of the person behind the wheel.
Regulators will have to take real life into account
The automotive industry continues to develop different powertrain options, and plug-in hybrids occupy a separate niche among them.
For example, the Ford Ranger PHEV shows that the concept itself can be useful from a practical point of view. But the environmental effect of such a car still depends on how regularly the owner uses the electric part of the powertrain.
Therefore, the question today is not whether to completely abandon PHEVs. It is much more important to stop automatically classifying them as low-emission vehicles solely on the basis of laboratory calculations.
Regulatory methodologies must take into account the real habits of owners, primarily the actual frequency of charging. Only then will environmental programs be able to correspond to what happens to cars after they leave the test bench.
A plug-in hybrid itself is neither a failure nor a universal solution to the environmental problem. Its effectiveness is determined by how often the car actually runs on electricity.
That is why the main conclusion of the research seems quite simple: PHEVs should be evaluated not only by what they are capable of doing, but also by how owners use them in real life.