THIS REPLY IS IN CORRECTION OF MY PREVIOUS REPLY PLEASE IGNORE MY PREVIOUS ONE.
FBT and Income tax both are separate and u should not confused in both the calculation. Even u incur loss u have to pay FBT on the expenditure. When u incur any expenditure (liable for FBT) u are liable to pay FBT. Depreciation is also an expense during the period when u use the car therefore it is liable to pay FBT.
However FBT is only payable on that part only which is allowable as expense. For the purpose of FBT Depreciation will be calculated in the manner as provided u/s 32 in Pro-rata basis. If at the end of the year block of asset doesnot exit or the value of block of asset is in negative then there will be no depriciation hence no FBT will be payable.
Even though if u have paid FBT on estimated basis then u r required to adjust the FBT and eligible for credit. I think you should claim refund of FBT in the return.