Lenders have responsible lending conduct obligations, and must not enter into loan agreements if the loan is unsuitable for the customer. So rest assured, any reputable lender will be completing thorough checks into your financial situation.
WARNING: If you read this website, your chances of getting car finance with bad credit will dramatically improve.
One of the major factors that a lender will look at to determine this is your income.
If you earn less than what is considered to be enough to cover typical monthly living expenses then you can be declined for credit even if you have a perfect credit rating. Having children will add to the living expenses and any other dependants you have living in your care under the age of 18. As well as other luxury costs like Foxtel, private health cover.
Even those people who earn a lot of money may be declined for credit as their expenses might be too high. So often people buy an investment property which doesn't make money and when it becomes untenanted it can cause even those with big incomes to start missing payments.
If you are a university student working part time, you may consider asking the lender to let you put Mum or Dad as a guarantor (subject to Mum or Dad approving). This will help your chances of being successful in applying for a car loan.
Summary
Lenders will carefully review your financial situation. However, you need to make sure that you can comfortably afford to repay the loan, as well as ideally being able to save at least $200 a month for a rainy day.