Even people that declared their incomes, they might get checked as well. Its the irregular spending VS income gap that they're looking at.
It depends on who is applying for the loan, if your name, then you definitely need a guarantor. If your mom or dad, then it depends on his or her financial stability.
A college student can easily get a part time job that'll earn RM1.5k per month, with a payslip, maximum loan amount would be subjected to 1/3 of your monthly income. That means if the loan you applied for incurs that you have to pay RM600 per month from your RM1500 salary, your loan will need a guarantor or else will be disapprove. But if the loan amount is less than a third of your income, then you do not need a guarantor.
The need for a guarantor are also subjective to the brand of vehicle, year of make, and popularity of the vehicle as well. This is due many vehicle had depreciation rates far greater than the amount you will repay the finance companies for years to come, and if you've stopped paying, that particular vehicle cannot reimbursed the amount you owe. As far as i know, there are categories of vehicles, such as Toyota, Honda, Nissan, Proton, Perodua, BMW, Merc are all in the same category, whereas Mitsubishis, Volvo, Mazdas, Isuzus, Suzukis are in the second gap, then come the Fiats, Alfas, Audis, Renaults. The last group will always find difficulty in buyers, getting loan, and once get, extension of repayment would be minimal, most would only go up to 7 years, and interest rates are high (disregarding those that rebate to financial institutes. )