Gst on sale of old car

https://www.gstindia.com/applicability-of-gst-on-sale-of-used-old-motor-vehicle/

Dear Yogesh it depends when you have sold.

Where sold on or after 25th January 2018, then refer notification 08/2018-CT(R) & 01/2018-CC(R):

Rate will be 18%/12% without cess - based upon cubic capacity and length of the car. 

If sold earlier suggest you to refer to my article published in Taxmanagement India: https://www.taxmanagementindia.com/visitor/detail_article.asp?ArticleID=8338&kw=GST-on-Used-Cars