A new trend in the Australian automotive market has emerged, raising questions about the effectiveness of plug-in hybrid electric vehicles (PHEVs). These vehicles combine a traditional combustion engine with an electric motor powered by a rechargeable battery. While PHEVs can reduce emissions and fuel costs, their environmental benefits depend heavily on how often users recharge them.

Recent data reveals that low charging rates among PHEV owners could lead to millions of additional tons of carbon emissions across the national fleet. This follows European research indicating that many PHEV users do not recharge their vehicles regularly, effectively using them as conventional cars with heavy batteries.

PHEVs typically have enough battery capacity to cover a standard day’s driving in urban Australia. If a user depletes their battery daily and recharges each night, their emissions could be significantly lower—about one-fifth of those from a comparable petrol or diesel vehicle. However, if they only recharge a few times a week, their emissions increase substantially. The financial implications are notable, with irregular charging potentially costing PHEV owners over $1,000 more in petrol annually, amounting to around $20,000 over 15 years.

In online communities, many PHEV owners assert that they charge their vehicles frequently, often dismissing contrary reports. One owner claimed, "Have only fuelled the [PHEV] two or three times in the five months I've owned it." However, fuel consumption analyses suggest a different reality. A recent study, based on data from hundreds of thousands of PHEVs in Europe, found that these vehicles are often driven with depleted batteries, resulting in emissions nearly five times higher than official EU estimates, making them almost as polluting as traditional petrol cars.

The question remains whether Australian PHEV users recharge more frequently than their European counterparts. The Electric Vehicle Council, representing major PHEV manufacturers, cited a 2024 survey of 625 Australian PHEV owners, which indicated that most charge their vehicles nightly and drive in electric mode for about 65% of their trips. EV Council CEO Julie Delvecchio stated, "Australians predominantly drive PHEVs in EV mode and charge them regularly."

BYD, a leading PHEV seller in Australia, reported that their servicing data showed PHEVs were driven in electric mode about half the time. Harry Li, BYD Australia’s product engineering manager, noted that Australians benefit from better access to home charging due to lower-density housing and a higher adoption of rooftop solar.

However, some experts challenge this view. Thomas Earl, director of data analysis at the Brussels-based advocacy group Transport and Environment, suggested that Australian PHEVs might emit even more CO2 than those in Europe. He pointed out that Australian PHEVs tend to be heavier and are often driven longer distances. While Australians may have better access to off-street parking and home charging, this does not guarantee more frequent charging. Earl added, "In Europe, we have much higher public charging availability."

The issue of PHEV charging habits may be further complicated by the prevalence of company cars, as surveys of private PHEV owners do not fully represent the broader user base. This discrepancy highlights the need for more comprehensive data to understand the true impact of PHEVs on emissions in Australia.