The moment you drive your car off the lot, it will depreciate in value. This means that if you don’t put much money down on your car, it’s immediately worth less money than you owe your lender. Even if you sell your car, you’d still be on the hook for the remaining balance. Because of this, it’s important to put down as much as is comfortable when you’re purchasing a car. A good rule of thumb to aim for is 20%.