To me, novated leasing is only cost effective if your kms travelled for the year is more than 25km, otherwise you will be paying a lot in FBT. For eg, 0-14999km the % applied to the cost base of your car is 26% x 2.1292 x 48.5%- cost $50,000 FBT= $13424 but if you travelled more than 25000km FBT=$5679 (rate at 11%). Of course you will incur more running expenses.
The cost of your salary packaging will include leasing, running expenses and FBT.