Fixed Assets Disposal.....

1) since the car is for business purpose GST  will applicable on margin  on sale of an  old  car as per as per notification 8/2018 dated 25-1-2018 ( please refer), prepare Tax  invoice .

2)  Capital  gain Tax may be applicable because car was used for business purpose  just confirm .

3)  You have  deduct (sale)   fixed  asset  from Gross block  .Deprecation up to September  may applicable . 

4)  please  refer IND AS 105  sale of non current  asset

  Entries in the books of accounts

1)     Sale booking  entry as per Tax invoice

    Trade Debtors  A/c  Dr

    To Asset         A/c   Cr

    To  CGST       A/c   Cr

    To  SGST       A/c   Cr

(  Booking of  sales of an asset )

When you received  payment

 Bank            A/c  Dr

 Deprecation  A/c  Dr

To Trade Debtors   A/c  Cr

To Profit on Sale    A/c  CR

( receipt of payment on sale of an asset)

Profit  will be transfer to P&L  entry

Profit  on Sale    A/c   Dr

To Profit  & Loss  A/c   CR

( profit on sale of an asset transfer to P&L)