Plug-in Hybrid Electric Vehicle (PHEV)

Hybrid vehicle whose batteries can be recharged from the mains or from a charging station.

What is a plug-in hybrid electric vehicle (PHEV) ?

A plug-in hybrid is a hybrid vehicle whose batteries can be recharged from the mains or from a charging station. This type of car is also known by the acronym PHEV, which stands for Plug-in Hybrid Electric Vehicle.

In the English name, the notion of Plug-in indicates the possibility of connection to the electrical network for recharging. Compared to a non-plug-in hybrid, a plug-in hybrid gains in operating range with the electric engine.

Depending on the technology, plug-in hybrids can run in full electric mode for 50 to 60 km. Beyond that, when the batteries are discharged, the combustion engine takes over.

The carbon emissions of plug-in hybrids can therefore be reduced compared to non-plug-in hybrids, and even more so compared to a combustion vehicle.


The specificities of a plug-in hybrid electric vehicle

A plug-in hybrid vehicle is first and foremost a hybrid car. It works with two engines used in combination:

  • an internal combustion engine, gasoline or diesel ;
  • an electric engine powerful enough to propel the car in 100% carbon-free mode.

A rechargeable battery pack is used to store the energy needed to power the electric engine. The hybridization system is optimized by a computer which controls the whole system to obtain the best yields.

This hybridization system is the most sophisticated of all, and therefore the most complex to implement on vehicles. It allows:

  • to use the combustion engine and regenerative braking to recharge the battery while driving the vehicle, such as mild hybrids or full-hybrids ;
  • and in addition, to connect the battery to a power outlet or an external terminal so that it can be recharged when stationary.


Examples and practical application

The advantages of a plug-in hybrid electric vehicle

  • Like all hybrid vehicles, PHEVs consume less fossil fuel and therefore emit less CO2 than gasoline- or diesel-powered cars.
  • Due to the rechargeable batteries, the range given during 100% electric driving is sufficient for daily trips, as it generally varies between 50 and 60 km. As a result, urban uses are the most decarbonized.
  • The biggest advantage of plug-in hybrids is their eligibility for the ecological bonus. Depending on the region, the price of the registration certificate can be reduced for the acquisition of a plug-in hybrid vehicle.

The minuses of a PHEV

  • The main disadvantage of plug-in hybrids is their very high purchase price, starting at 35 and 40, 000 Euro for small models. In order to make the batteries rechargeable, numerous adaptations must be made to the vehicle's architecture. This leads to additional manufacturing costs and a significant increase in sale prices: the difference between a plug-in hybrid and a conventional hybrid can be as much as 5000 Euro.
  • With a more powerful and heavier battery and a more complex system, a plug-in hybrid is actually heavier than a non-plug-in hybrid. That's about 100 kg more than a full-hybrid car (HEV) and 300 kg more than a mild-hybrid car (MHEV). This increases the energy requirements to move the vehicle, and reduces the savings that can be achieved. On long journeys at high speed, the electric engine weighs down the vehicle and can therefore lead to over-consumption.


PHEVs in numbers

According to the Argus, 141,008 plug-in hybrids (gasoline or diesel) were sold in 2021, out of the 1,659 million cars purchased in total. The increase in one year is relatively significant as only 74627 PHEVs had been sold in 2020.

Another study indicates that of all plug-in hybrids, there were 133,902 gasoline models in 2021, which represents the vast majority of PHEVs. This volume, which has been rising sharply since 2020, now represents just over 8% of the French automotive market.

In France, the two leading manufacturers in the national market led the 2021 sales in terms of volume with:

  • 21,757 PHEVs sold for the Peugeot brand, representing 16.25% of the market share ;
  • 11,879 PHEVs sold for the Renault brand, representing 8.87% of the market share.

The following are the foreign brands:

  • Mercedes which takes 3rd place in the ranking with 10,918 PHEVs sold (8.15%) ;
  • Volvo in 4th position with 10,636 PHEVs sold (7.94%) ;
  •  BMW in 5th position with 10,596 PHEVs sold (7.91%);
  • Audi in 6th position with 9,657 PHEVs sold (7.21%).

The French brands Citroën and DS are ranked 7th and 8th respectively:

  • with 7,116 PHEVs sold (or 5.31%) for the brand with the chevrons ;
  • with 6,609 PHEVs sold (or 4.94%) for DS.

Out of all vehicles sold, plug-in hybrids with gasoline engines represented a percentage of sales in 2021 that varied considerably by brand:

  • 61.53% for Volvo ;
  • 23.05% for BMW ;
  • 21.5% for Mercedes ;
  • 19.28% for Audi ;
  • 7.61% for Peugeot ;
  • 4.42% for Renault ;
  • 4.40% for Citroën.

In the ranking by model, Peugeot wins with its 3008 SUV, which will sell 16,962 units in 2021, followed by the Renault Captur E-tech Plug-in with 8,180 units sold, and the Citroën C5 Aircross (7,097 units purchased).


Regulatory framework

The fuel consumption and CO2 emissions measured on hybrid vehicles fell under the NEDC (New European Driving Cycle) approval standard until September 1, 2018. This model for calculating consumption and carbon emissions has proved to be inadequate and far from reality, particularly following the Dieselgate scandal.

This has led the European Union to abandon the NEDC standard in favour of the international standard. The approval procedures are now set by the so-called WLTP (Worldwide harmonized Light vehicles Test Procedure), whose tests are closer to the real values.

However, given that the theoretical results are sometimes far from the actual consumption and emissions, the EU is considering revising its calculation methods for the approval of cars. It could be a question of taking into account the real consumption of the cars from values read by the meters, and not from tests on a test bench. Plug-in hybrids could be penalized by this new method of calculating carbon emissions, which is not expected to be applied before 2025.