If you lease a car, you can generally claim a GST credit for each lease instalment amounts paid in each period which included GST.
At the end of the lease, you may have to pay a residual payment to take ownership of the car. You might also be able claim a credit for the residual payment, provided the amount paid included GST. You also need to ensure you are only claiming the business use percentage of the lease expenses so that you do not claim GST credits on any personal use portion of the vehicle.
You input the lease instalment amount and the business use percentage in the Airtax BAS form under 'car hire'.