Hybrid electric vehicles might not be the green machines consumers think they are, with research finding major car brands are making potentially misleading claims about the technology.
Questionable marketing tactics included calling plug-in hybrid vehicles "the best of both words" and calling hybrids "self-charging cars" despite both vehicle types relying on petrol, the report found.
The research, released by the Environmental Defenders Office on Sunday, also questioned net-zero pledges by major car brands when many had yet to commit to ending the production of petrol cars by 2035.
The study, called Driving Change or Just Filling Up the Tank, comes six months after the group raised concerns about Toyota's marketing with Australia's consumer watchdog, and after electric and hybrid vehicles recorded record sales in the country.
EDO safety climate managing lawyer Kirsty Ruddock told AAP the group analysed claims from major car manufacturers to determine whether they overstated positive impacts made by their products or sought to mislead buyers.
She said "greenwashing" claims could be particularly harmful in the automotive industry as transport accounted for 23 per cent of global carbon emissions.
"Information that's misleading may delay people's decision-making and provide not enough information for people to really make the best informed choice," she said.
"The risk is they are misleading people and consumers are buying products that may not be as sustainable as they think."
The study found plug-in hybrid vehicles were often marketed as having "all the benefits of an electric vehicle" without charging challenges, even though research showed they used petrol engines almost twice as often as expected.
Marketing claims hybrid vehicles were "self-charging" also gave the impression they did not require an external power source, even though the cars relied on petrol to operate and produced higher lifetime emissions than electric cars.
Brands including Lexus, Nissan, Toyota, MG and Volvo also referred to hybrid vehicles as being electric without referencing their use of petrol, the study said, with slogans including "electric for everyone" and "live it electric with hybrid".
Ms Ruddock said the marketing terms could blur the lines between vehicle technologies for consumers who were trying to make greener choices.
"We will be feeding this material to the (Australian Competition and Consumer Commission) and saying here are some great examples that might help guide your education and enforcement activities," she said.
Earlier this year, the ACCC revealed 11 out of 29 vehicle brands it surveyed for signs of "greenwashing" had made claims that raised concerns.
The commission has since published draft guidance to companies making claims about cars, including "zero-emission vehicles," warning that any promises should represent emissions produced during a vehicle's entire life-cycle.
Consultation on the ACCC guidance closed earlier this month.
