Verified answer

If you're asking for tax reasons allowance is on form. If you use for business only you can deduct all expense's. if for pleasure and business you have to average mileage for each.

I am unaware where you live and what are the cost of various element in answering the query.

But generically:

Calculate Estimated cost of ownership assuming certain miles per month, number of years of ownership.

Then the cost of ownership is:

Cost of vehicle+ cost of finance+ cost of maintenance+cost of fuel for the assumed miles- resale value

Then the cost of driving is the cost of ownership/estimated miles of running. Which should be the cost of reimbursement also