Plug-in hybrids to lose ‘low-CO2’ status as EU reassesses how green they really are

The environmental rating of hybrid cars is set to become a lot more realistic following publication of an updated EU assessment of how little plug-in hybrids contribute to reducing emissions. It means many hybrids will no longer count as “low-CO₂” and will not qualify for tax breaks and regulatory benefits that incentivise motorists and companies to buy them.

Plug-in hybrid electric vehicles (PHEVs) were once advertised as the go-to cars for climate-conscious drivers, combining an electric motor with a petrol- or diesel-fuelled second engine. The thinking was that PHEVs could allow for e-motoring wherever possible, but with the back-up of a combustion engine if necessary. But it has become clear that the number of kilometres driven by PHEV owners on the electric motor is quasi non-existent, which means regulatory and monetary benefits are going towards fossil fuelled motoring.

For a hybrid car to count as “low-CO₂” within EU car CO₂ standards, it has to emit no more than 50 grams of CO₂ per kilometre. For the average PHEV to achieve that, over 70% of its distance must be driven on the electric motor. It means that hybrids qualify as “low-CO₂” on the basis of type-approval tests, yet poor design and driver behaviour means emissions in reality are much higher than the tests suggest. Standard hybrids – which are self-charging and not plug-in – will not be affected by the change. 

The  latest data show that, on average, privately owned PHEVs emit three times more CO₂ (and therefore use three times more fuel) than recorded in official tests. For company cars it is even worse, with just 11-15% of kilometres driven electrically, when official assumptions are for 70-85%. 

In emissions terms, this means the average PHEV sold last year emits between 114 and 190 g/km of CO₂ instead of the officially expected 38 g/km. With carmakers facing more stringent CO₂ targets, the low official CO₂ emissions of PHEVs are driving rising sales. In 2021 they were 71% up on 2020 sales, with almost 1 million units sold, making emissions from road transport worse under the guise of moving to greener technology.

In February, the European Commission published an update on the “utility factors” of PHEVs, which is the fraction of distance that a PHEV operates using predominantly electricity used for calculating CO₂ emissions. T&E heavily criticised the draft for failing to tackle the gap between the share of e-kilometres assumed to be driven and the share driven in reality. The Commission’s draft acknowledged the discrepancy, but proposed nothing to address it until at least the end of this decade.

Now an updated draft proposes to assume a lower, more realistic share of km driven by PHEVs electrically, though it doesn’t make use of company car usage data until 2027. Company cars make up 71% of new PHEV sales.

T&E’s emissions engineer Anna Krajinska said: “We welcome the Commission’s updated draft as a step in the right direction. It is now up to the Member States to support the proposals and ensure that the gap between official and real world PHEV emissions is closed as quickly as possible. Carmakers don’t even need two years to fix this as no technological solutions are needed, only a change in production of models based on a realistic assessment of driver behaviour.

“The more false incentives PHEVs enjoy, the more it slows down the development of battery electric vehicles, which is where the real solution to cleaning up road transport lies.”

The Commission’s draft also includes a review of the proposed utility factors in 2024 and 2026 based on data collected from on-board fuel consumption metres, which are likely to give a far more comprehensive assessment of the percentage of distance driven on the electric motor. This will provide an opportunity to further amend the 2025 and 2027 utility factors based on real-world usage data from new PHEVs sold since 2021.

T&E has published a  briefing document, Making PHEVs count, which sets out the research by the Fraunhofer Institute and the International Council on Clean Transportation highlighting the discrepancy between kilometres driven electrically and the official assumptions used to categorise PHEVs as “low-CO₂”.