How often do owners actually charge their PHEVs?

By | April 3, 2024

charge an ultra-low electric vehicle on a London street

Do owners actually charge PHEVs that often?Miles Willis – Getty Images

  • The European Commission report examines real-world fuel consumption and CO2 emissions data from 600,000 vehicles from 2021, and finds a significant gap between type-approval figures for PHEVs and real-world data.

  • The report also examined fuel consumption and CO2 data for petrol and diesel models, finding a smaller gap between official WLTP type-approval numbers and real-world data collected from cars.

  • Following this report, the European Commission plans to change the WLTP testing procedures for PHEVs from 2025 to take into account the observed gap.


Plug-in hybrids have long been seen as a logical step towards a battery-electric future, offering a battery that can be charged and travel all-electric mileage that would suit most local driving and commuting tasks. At least in theory.

And with demand for EVs easing into 2023 — and the overall EV adoption rate moving up at a snail’s pace year over year — automakers are once again looking to plug-in hybrids to give energy-conscious buyers an EV-like option.

But a recent European Commission study confirms what many in the industry suspect about plug-in hybrids: people don’t charge them as often to get the most out of EV driving mode.

The report used data collected from around 600,000 vehicles in Europe over the course of 2021, including petrol, diesel and plug-in hybrids of both fuel types, using fuel consumption monitors installed in the vehicles to measure actual fuel consumption compared to advertised consumption.

On-board fuel consumption monitoring equipment (OBFCM) has been a requirement in all new cars and small vans sold in Europe since January 2021, with manufacturers collecting the data remotely and during service visits.

As expected, actual emissions from petrol and diesel vehicles showed a gap between the official average type-approval CO2 emissions and the vehicles’ actual consumption, as measured by OBFCM devices. Gasoline cars included in the study saw an average gap of 23.7%, while diesel cars saw a gap of 18.1%.

European Commission PHEV study chartEuropean Commission PHEV study chart

The report found a significant gap in the actual average fuel consumption and CO2 emissions of PHEVs, compared to their official WLTP type-approval numbers.European Commission

But this gap was not particularly surprising to research managers or manufacturers.

“Such a gap was expected because there are several factors that influence real-world emissions, not all of which can be fully replicated in a laboratory test, such as traffic conditions, landscape, road conditions, ambient temperature, use of air conditioning and electronics and driving behaviour,” the committee said.

The real surprise was the gap shown by plug-in hybrids included in the study, with actual CO2 emissions on average 3.5 times higher than WLTP (Worldwide Harmonized Light Vehicles Test Procedure) type-approval values. are the European equivalent of EPA numbers. Similarly, actual fuel consumption figures for PHEV models were significantly higher than WLTP values.

“The large discrepancy found for these vehicles between actual values ​​and WLTP values ​​shows that they are being charged and driven in electric mode much less than they were expected to be used and that the assumptions used for calculating of the WLTP test result are incorrect. in real conditions,” the report said.

The WLTP calculation for fuel consumption and CO2 emissions uses a so-called utility factor, which is the expected share of the distances driven in EV mode in PHEVs.

As a result, the European Commission is already planning to revise the official WLTP testing procedure for PHEVs from 2025 to take this gap into account.

It is wise to remember that this report applies to vehicles sold in the EU in 2021, so does not take into account absolute all PHEVs on the road in the EU, nor does it reflect PHEV use in other regions where their emissions data is calculated based on different assumptions, including in the US.

The report also found quite a bit of variation among automakers when collecting the data, as well as other peculiarities in the sample population of cars. Thus, additional studies on the use of PHEVs will likely be needed to establish other important data.

The electric range offered by PHEVs in the EU and elsewhere also plays a role in their use, as we can think of enough commutes that even daily charging would exhaust the EV range of PHEV models quite quickly.

These are all factors that are difficult to explain in such a study, which mainly concerns WLTP expectations about vehicle use.

But the report also seems at first glance to confirm what some EV industry observers have long suspected: If owners wanted to charge their vehicle regularly and use it primarily for local driving, they would buy an EV from the start in instead of a PHEV and would invest in a level 2 charger for their garage.

Because car owners don’t do that to have If you want to charge a PHEV to get it out of the garage or driveway in the morning, charging habits can vary widely from owner to owner. Not all PHEV owners may even have a regular one access to an EV charger based on where they live, which is another interesting variable that is difficult to capture in such a study unless owners themselves report such things.

The circumstances under which owners ultimately acquire plug-in hybrids should also not be overlooked, we add. A PHEV model may well have been the only one at a dealer with the options the buyer wanted, or it may have been discounted at the end of a model year and purchased by someone who was not specifically looking for a plug-in from the start. in hybrid. because they wanted to take advantage of the electric range.

Owners’ motivations for purchasing or leasing a plug-in hybrid may not be taken lightly when it comes to their daily use, we suspect.

But the implications of the report could be quite unfavorable for PHEV manufacturers, at least in the EU, because carmakers must meet a certain emission standard for type-approval across their entire range. A revision of the WLTP calculations for PHEVs in 2025 could drastically change these fleet-wide averages, and a closer look at the EPA figures for PHEVs could also reveal some surprises about their use and actual emissions.

Do you consider plug-in hybrids as a useful stepping stone to electric vehicles, Or are they a veneer of more energy-conscious driving behavior? Let us know what you think.

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