PHEVs emit 350% more CO2 than claimed because lax drivers don’t charge them: EU

A new European Commission report shows that while its estimates for true ‘real world’ emissions from petrol and diesel cars have been proven, PHEVs are “currently not realising their potential” – by about 3.5 times the claims of their manufacturers.

Using data collected from mandatory on-board fuel consumption monitors (OBFCM) installed in all new EU-market liquid-fuelled cars since January 2021, the Commission put the results down to PHEV vehicles “not being charged and driven fully electrically as frequently as assumed”.

Petrol & diesel cars

Emissions around 20% higher than claimed

According to the report, the average gap observed between the real-world and the official type-approval average CO2 emissions and fuel consumption of new cars registered in 2021 was 23.7% for petrol cars and 18.1% for diesel cars (1-1.5 L/100km or 28-35 g CO2/km).

The Commission said the gap between WLTP laboratory claims and its real-world data was anticipated, “as there are different factors affecting real-world emissions which cannot all be fully replicated in a laboratory test, such as the traffic conditions, landscape, road conditions, ambient temperature, use of air-conditioning and on-board electronics, and driver behaviour”.

Local scrutiny

Readers may recall that the Australian Automobile Association (AAA) has been running its own tests on the fuel consumption of vehicles sold here, in compliance with European Union legislation, arriving at results that showed some popular cars use up to 20% more fuel than claimed.

The AAA says its testing was carefully designed to produce accurate and repeatable consumption data that minimises the influence of human factors like driving style and different traffic levels.

Plug-in hybrid electric vehicles (PHEV)

For PHEVs, the European Commission’s report points to data showing CO2 emissions 3.5 times higher (4 L/100km or 100g/km CO2) on average.

As noted above, the Commission says this confirms most PHEVs are not being charged regularly enough to enable frequent pure-electric driving, or even proper hybrid-like efficiency, with the small petrol engine effectively dragging an electric motor and battery pack around.

Importantly, the Commission notes that even though carmakers are required to report efficiency and emissions data from all new vehicles, compliance has been “rather poor”.

JLR sent data from 43% of its customer cars, with Mercedes-Benz and Volvo reporting 27% and 24% respectively – but most brands reported data on 5% or less of their fleets.

"While this first data is not yet broad or representative enough to draw firm conclusions, it does provide valuable preliminary insights for car emissions," the report said.

Regardless, the current results are potentially a disastrous hit to the marketing and reputation of PHEV technology, which, used as intended, could result in emissions levels as low as 20g/km of CO2 emissions – at least as tested to WLTP standards.

It’s this sort of claimed efficiency that has led to PHEVs being held up as an ideal interim technology for buyers not ready or able to transition to battery-electric vehicles.

They’ve likewise proven useful to brands, with the WLTP-approved low emissions claims of PHEVs making for a convenient path to complying with strict emissions targets. The same strategy will likely lead to more PHEVs being offered in Australia, once the New Vehicle Efficiency Standard (NVES) comes into effect.

A number of PHEVs are also exempt from Australia’s Fringe Benefits Tax, making them popular options for fleets and novated leases.

In February 2023, European lobby group Transport & Environment said: "Plug-in hybrids are sold as the perfect combination of a battery for all your local needs and an engine for long distances. But real-world testing shows this is a myth.”

Currently, the markedly low emissions claims for PHEVs is derived from a “utility factor” to calculate CO2 emissions, which assumed PHEV owners spent around 70-85% of their driving time in full-electric mode.

"Assumptions used for calculating the WLTP test result do not hold in real-world conditions,” the European Commission report notes.

To account for this, the European Commission says it has recalculated the utility factor to a 50-50 split for private vehicles from 2025, with fleet cars to be assessed by the same split from 2027. “These changes [...] may need to be further adjusted based on real-world data,” the Commission said.

The Commission says buyers should still be glad that World harmonised Light vehicle Testing Procedure (WLTP) replaced the older New European Driving Cycle (NEDC) test in 2018, with the more advanced testing having halved the gap between tested and real-world emissions.

PHEVs in Australia

Year to date (end of March 2024), Australia has seen 3426 PHEV sales – up significantly from 1461 for the same period last year.

The number of PHEVs available in Australia is a longer list than some might realise, ranging from the popular Mitsubishi Outlander PHEV and Eclipse Cross PHEV models to more recent arrivals like the Cupra Formentor, Mazda CX-60 and Alfa Romeo Tonale.