Hi Shipra,
I strongly suggest you research on the fuel reimbursement policy disucssion on citehr. This policy has been under lot of contraint in corporate industry due to its natures of being tax free and now taxable. You as HR cannot draft this policy alone. You will need the help of CA or your Finance Department to frame the rule.
On your side as HR what best you can do is network with your companies in your like business and see what they are offering their employees and probaby match them or give better to retain employees. If you know someone working in Central Government Office/Sem Government office, you can also seek inputs from them, as the offices have a well planned rules for fuel expenses based oficer positions and locations.
Here is a helper below for you, which will make you rethink on how to draft your policy.
VALUATION OF PERQUISITES - MOTOR CAR | SIMPLE TAX INDIA
Hope its helpful.
Ukmitra