This study combines electricity supply mix profiles and observed charging behaviour to compare the environmental performance of a petrol-hybrid electric vehicle (PHEV) with a class-equivalent internal combustion engine (ICE) vehicle over the full life cycle. Environmental performance is compared using a suite of indicators across the life cycle, accounting for both marginal and average electricity supply mixes for Australia’s National Energy Market (NEM) grid. The use of average emission factors for the NEM grid can serve as a good proxy for accounting charging behaviour, provided that there is a strong correlation between the time of charging and total electricity demand. Compared with an equivalent ICE, PHEVs charged from Australia’s NEM can reduce greenhouse gas emissions over the life cycle. Potential burden shifts towards acidification, eutrophication and human toxicity impacts may occur, but these impacts are uncertain due to modelling limitations. This study has the potential to inform both short and long term forecasts of the environmental impacts associated with EV deployment in Australia and provides a better understanding the temporal variations in emissions associated with electricity use in the short term.