The bank can repossess the car and if anything is used as collateral they can claim that as well. It is best to not get yourself in debt you cannot pay off.
One way to calculate debt is to figure out what your income is per week, and divide that by the weekly payments for the car. Lets say you make 3200, and your debt is 450 a week.
As shown below
Income ÷ Payments
3200 ÷ 450 = 0.14
Now multiply that by 100 to get your percentage,
0.14 x 100 = %14
Financial advisors recommend that you keep your debt-to-income ratio under 30%.