First: the loan has been successfully processed, but you haven't signed the loan contract yet. Don't worry about this situation. As long as you don't sign the contract, you'll be fine.

Second: the loan has been successfully processed and the contract has been signed, but if you don't want to borrow money, you can pay the car money in one lump sum, not just the down payment;

Third: the loan was successfully processed, the contract was signed and the down payment was paid. Then, if you default, you can only pay the full amount in advance, and you may have to pay a certain penalty, usually 3% of the remaining loan amount.

Good luck!