E.g. $100,000 loan 4% interest over 5 years = $120,000/60months = $2,000/monthly repayment
which is around 1/4 of gross income. (excluding fuel, insurance, maintenance, repairs etc)

This should keep the car 2nd hand value curve above the outstanding loan amount line graph.
So that you can sell the car without the need to top up any cash to settle the loan.
Should you need the $2,000 monthly for higher priority objectives in life such as housing, marriage, maternity, illness etc