This study estimates the total cost of ownership of corporate battery-electric vehicles (BEVs) in Australia across a range of charging scenarios. It finds that time-varying tariffs have the potential to drive down the costs of vehicle ownership if charging is done at a time when greener and (often) cheaper electricity is available. The degree of benefit varies with several key parameters and operational characteristics, so efficient charging requires careful planning. With the right incentives and infrastructure in place, BEV fleets can serve as a valuable resource for load flexibility for grid operators.