What is the cheapest way to pay off this loan?

I recently took out a loan in order to buy a car for work.

The contract is over a five year term, with a total of 60 monthly repayments, at an interest rate of 13% pa.

The way the lender wants me to repay the loan is to make 60 payments of $485 (it turns out each payment incurs a $10 administration fee).

My initial instinct was to pay as much as I can afford each month in order to reduce my total interest payments. However there is a clause in the contract that attracts an early repayment fee, calculated as follows:

An Early Termination Fee … is:
i) $750 if the Amount of Credit exceeds $12000; or
ii) otherwise, 6.25% of the Amount of Credit,
and thereafter the amount of the fee is that amount multiplied by the number of unexpired whole months in the term at the time the contract is paid out divided by the number of whole months in the term.

As I write this I have a credit of $21000 (rounded up for simplicity), and 60 months left on the contract.

My question is what is my best strategy for repaying this loan, that is the cheapest to me in the long run? (Also assume this is the lowest interest rate I can get, my credit score isn’t great, I’ve been told by the lender that I should talk to them about refinancing once I have more payslips as evidence of income…in 6 months time).