Plug-in hybrids (PHEVs), and their cousins, range-extender electric vehicles, are seen by many – not least the world’s big car makers – as being a useful stepping stone between petrol and diesel models and fully electric cars.
The theory goes that a PHEV gets drivers who are unsure about making the electric leap used to the idea of plugging in and driving around on electric power, while still having a petrol (occasionally a rarer diesel) engine and fuel tank for reassurance on longer journeys.
As electric sales stalled, car makers scrambled to bring forward a line-up of improved PHEVs with longer ranges on electric power (many can now manage more than 120km on one charge, officially speaking). Chinese car makers, meanwhile, are pivoting hard towards PHEVs and REEVs (whereby a car is always driven by its electric motor but has a petrol engine on board as a generator for longer ranges) as these don’t attract the same hefty EU tariffs as fully electric models.
There’s a problem, though. The temptation with a PHEV or an REEV is just to fill up and drive as you’ve been used to for so many years, and not fully use the electric part of the set-up. In doing so, you’re not allowing the car to work properly, and you’re increasing its real-world emissions to the point where there may not have been much point in buying a PHEV in the first place.
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Eco think-tank Transport & Environment (T&E) has just issued research which it says shows that PHEVs are no better for the environment than a conventional petrol-engined car. T&E says its data, taken from real-world testing, shows that PHEVs emit five times as much carbon as the lab testing says they should. The group says this shows that the car industry’s lobbying for PHEVs to be considered ‘technology neutral’ is bunkum.
Lucien Mathieu, cars director at T&E, said: “Plug-in hybrids are one of the biggest cons in automotive history. They emit almost as much as petrol cars. Even in electric mode they pollute eight times as much as official tests claim. Technology neutrality cannot mean ignoring the reality that, even after a decade, PHEVs have never delivered.”
However, T&E’s numbers don’t seem to show quite that big a disaster for PHEVs. While it’s true that the real-world figures are well above what the laboratory tests show – they claim a 75 per cent reduction in emissions compared to an equivalent petrol car – T&E’s data still shows that on average, a PHEV model will have emissions 19 per cent lower overall. That seems like a win to some, at least.
Some of T&E’s reasoning also seems a little off-piste, as the report suggests: “Even when driven in electric mode, PHEV engines consume 3 litres of petrol per 100km, on average, the EEA data shows. As a result, they emit 68g of CO2/km in electric mode – 8.5 times as much as official tests claim. This is because the electric motors in PHEVs generally have insufficient power for higher speeds or steep inclines and the engine needs to kick in. On average, the engine supplies power during almost one-third of the distance driven in electric mode, according to the data.”
While T&E’s data looks solid, the fact is that almost all PHEVs are rated to be able to run on fully electric power at speeds of up to 130km/h, and in testing, The Irish Times has found few, if any, contemporary PHEV models that won’t tackle a steep hill in EV mode, given sufficient charge.
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Car makers are also committing to more PHEV models, with bigger batteries and longer electric ranges, to keep up with consumer demand. In Ireland so far in 2025, the demand for PHEV models has picked up significantly, rising by 53 per cent to more than 18,000 cars so far this year.
Even longer-range models are bad news, though, says T&E, “as bigger batteries make the vehicles heavier and, therefore, burn more fuel in engine mode. These heavier vehicles also consume more energy than smaller cars when driven on the battery. Plug-in hybrids with an electric range above 75km actually emit more CO2 on average than those with a range between 45km and 75km, the data shows.”
Audi recently announced that it’s rowing back on previous commitments to become an all-electric brand, taking a more wait-and-see approach and continuing to develop internal combustion engines and hybrids.
Hyundai has also announced that it’s going to create a series of range-extended electric models, due to go on sale in 2026, and which “will combine the advantages of internal combustion engines” in response to “the recent slowdown in EV demand”.
These new Extended Range Electric Vehicles (EREVs) are hardly new in technology terms – the idea is basically that of a range-extender, technology that dates back to the mid-2000s and the arrival of cars such as the original Chevrolet Bolt and Opel Ampera. Those cars used a compact battery with a capacity of between 16kWh and 17kWh (depending on the production year), with a range of up to 61km when fully charged from the mains.
When on a longer journey than that, both cars used an old General Motors ‘EcoFlex’ 1.4-litre petrol engine (which had been knocking around various GM and Opel models since the 1990s) to act as a generator which could charge the battery and keep you mobile, for a touring range of around 480km.
Mazda uses similar technology in its new MX-30 R-EV, which uses a compact rotary petrol engine as a range-extender, while it could be argued that the Nissan Qashai e-Power is of similar design (although its battery is much smaller and can’t be charged from the mains).
Hyundai’s new models will use both petrol and electric power, with the battery being charged from the mains for shorter journeys. These new EREV models will have four-wheel drive, and Hyundai claims they will have a combined petrol and electric range of up to 900km.
“The new EREV maximises the use of the existing engine to improve customer appeal and secure cost competitiveness with similar EVs by reducing high-cost battery capacity,” said a Hyundai spokesperson. “It provides EREV customers with a responsive EV-like driving experience, allowing consumers to naturally transition to EVs during future demand recovery periods. This vehicle serves as a key bridge to electrification.”
Hyundai’s president and chief executive Jaehoon Chang said: “In the electrification era, Hyundai has distinguished itself by rapidly launching a comprehensive line-up of EVs, catering not only to mass-market brands but also to the luxury and high-performance segments. Building on our advanced technology and dedication to innovation, we aim to secure a leading position in the market as the adoption of electrified vehicles gains momentum.”
The rules on PHEVs are tightening, though. The new Euro 6e-bis emissions regulations come into force this year, and are mandatory from the beginning of 2026. They include much more rigorous, arguably more realistic testing for PHEVs. For example, a Mercedes C300e PHEV saloon with just over 125km of electric range is advertised with a WLTP CO2 emissions figure of 12g/km, whereas this has jumped to 47g/km under Euro 6e-bis. That isn’t enough to cause the C300e to jump up from the second-lowest tax band in Ireland, but other vehicles doubtless will – even if a €10-a-year increase is hardly the biggest penalty in the world for doing so.
Nonetheless, T&E is adamant that PHEVs are a bad thing, and that as the EU prepares to look again at its 2035 combustion engine sales ban, such cars should not be given a bye to remain on sale. Lucien Mathieu said: “Weakening the rules for plug-in hybrids is like drilling a hole in the hull of Europe’s car CO2 law. Instead of steering the market toward affordable zero-emission cars, carmakers will flood it with expensive, polluting PHEVs. That risks sinking the EV investment certainty the market desperately needs.”
